锅炉毕设文献翻译
自动化专业毕业论文外文文献翻译
目录Part 1 PID type fuzzy controller and parameters adaptive method (1)Part 2 Application of self adaptation fuzzy-PID control for main steam temperature control system in power station (7)Part 3 Neuro-fuzzy generalized predictive control of boiler steam temperature ..................................................................... (13)Part 4 为Part3译文：锅炉蒸汽温度模糊神经网络的广义预测控制21Part 1 PID type fuzzy controller and Parametersadaptive methodWu zhi QIAO, Masaharu MizumotoAbstract: The authors of this paper try to analyze the dynamic behavior of the product-sum crisp type fuzzy controller, revealing that this type of fuzzy controller behaves approximately like a PD controller that may yield steady-state error for the control system. By relating to the conventional PID control theory, we propose a new fuzzy controller structure, namely PID type fuzzy controller which retains the characteristics similar to the conventional PID controller. In order to improve further the performance of the fuzzy controller, we work out a method to tune the parameters of the PID type fuzzy controller on line, producing a parameter adaptive fuzzy controller. Simulation experiments are made to demonstrate the fine performance of these novel fuzzy controller structures.Keywords: Fuzzy controller; PID control; Adaptive control1. IntroductionAmong various inference methods used in the fuzzy controller found in literatures , the most widely used ones in practice are the Mamdani method proposed by Mamdani and his associates who adopted the Min-max compositional rule of inference based on an interpretation of a control rule as a conjunction of the antecedent and consequent, and the product-sum method proposed by Mizumoto who suggested to introduce the product and arithmetic mean aggregation operators to replace the logical AND (minimum) and OR (maximum) calculations in the Min-max compositional rule of inference.In the algorithm of a fuzzy controller, the fuzzy function calculation is also a complicated and time consuming task. Tagagi and Sugeno proposed a crisp type model in which the consequent parts of the fuzzy control rules are crisp functional representation or crisp real numbers in the simplified case instead of fuzzy sets . With this model of crisp real number output, the fuzzy set of the inference consequence willbe a discrete fuzzy set with a finite number of points, this can greatly simplify the fuzzy function algorithm.Both the Min-max method and the product-sum method are often applied with the crisp output model in a mixed manner. Especially the mixed product-sum crisp model has a fine performance and the simplest algorithm that is very easy to be implemented in hardware system and converted into a fuzzy neural network model. In this paper, we will take account of the product-sum crisp type fuzzy controller.2. PID type fuzzy controller structureAs illustrated in previous sections, the PD function approximately behaves like a parameter time-varying PD controller. Since the mathematical models of most industrial process systems are of type, obviously there would exist an steady-state error if they are controlled by this kind of fuzzy controller. This characteristic has been stated in the brief review of the PID controller in the previous section.If we want to eliminate the steady-state error of the control system, we can imagine to substitute the input (the change rate of error or the derivative of error) of the fuzzy controller with the integration of error. This will result the fuzzy controller behaving like a parameter time-varying PI controller, thus the steady-state error is expelled by the integration action. However, a PI type fuzzy controller will have a slow rise time if the P parameters are chosen small, and have a large overshoot if the P or I parameters are chosen large. So there may be the time when one wants to introduce not only the integration control but the derivative control to the fuzzy control system, because the derivative control can reduce the overshoot of the system's response so as to improve the control performance. Of course this can be realized by designing a fuzzy controller with three inputs, error, the change rate of error and the integration of error. However, these methods will be hard to implement in practice because of the difficulty in constructing fuzzy control rules. Usually fuzzy control rules are constructed by summarizing the manual control experience of an operator who has been controlling the industrial process skillfully and successfully. The operator intuitively regulates the executor to control the process by watching theerror and the change rate of the error between the system's output and the set-point value. It is not the practice for the operator to observe the integration of error. Moreover, adding one input variable will greatly increase the number of control rules, the constructing of fuzzy control rules are even more difficult task and it needs more computation efforts. Hence we may want to design a fuzzy controller that possesses the fine characteristics of the PID controller by using only the error and the change rate of error as its inputs.One way is to have an integrator serially connected to the output of the fuzzy controller as shown in Fig. 1. In Fig. 1,1K and 2K are scaling factors for e and ~ respectively, and fl is the integral constant. In the proceeding text, for convenience, we did not consider the scaling factors. Here in Fig. 2, when we look at the neighborhood of NODE point in the e - ~ plane, it follows from (1) that the control input to the plant can be approximated by(1)Hence the fuzzy controller becomes a parameter time-varying PI controller, itsequivalent proportional control and integral control components are BK2D and ilK1 P respectively. We call this fuzzy controller as the PI type fuzzy controller (PI fc). We can hope that in a PI type fuzzy control system, the steady-state error becomes zero.To verify the property of the PI type fuzzy controller, we carry out some simulation experiments. Before presenting the simulation, we give a description of the simulation model. In the fuzzy control system shown in Fig. 3, the plant model is a second-order and type system with the following transfer function:)1)(1()(21++=s T s T K s G (2) Where K = 16, 1T = 1, and 2T = 0.5. In our simulation experiments, we use thediscrete simulation method, the results would be slightly different from that of a continuous system, the sampling time of the system is set to be 0.1 s. For the fuzzy controller, the fuzzy subsets of e and d are defined as shown in Fig. 4. Their coresThe fuzzy control rules are represented as Table 1. Fig. 5 demonstrates the simulation result of step response of the fuzzy control system with a Pl fc. We can see that the steady-state error of the control system becomes zero, but when the integration factor fl is small, the system's response is slow, and when it is too large, there is a high overshoot and serious oscillation. Therefore, we may want to introduce the derivative control law into the fuzzy controller to overcome the overshoot and instability. We propose a controller structure that simply connects the PD type and the PI type fuzzy controller together in parallel. We have the equivalent structure of that by connecting a PI device with the basic fuzzy controller serially as shown in Fig.6. Where ~ is the weight on PD type fuzzy controller and fi is that on PI type fuzzy controller, the larger a/fi means more emphasis on the derivative control and less emphasis on the integration control, and vice versa. It follows from (7) that the output of the fuzzy controller is(3)3. The parameter adaptive methodThus the fuzzy controller behaves like a time-varying PID controller, its equivalent proportional control, integral control and derivative control components are respectively. We call this new controller structure a PID type fuzzy controller (PID fc). Figs. 7 and 8 are the simulation results of the system's step response of such control system. The influence of ~ and fl to the system performance is illustrated. When ~ > 0 and/3 = 0, meaning that the fuzzy controller behaves like PD fc, there exist a steady-state error. When ~ = 0 and fl > 0, meaning that the fuzzy controller behaves like a PI fc, the steady-state error of the system is eliminated but there is a large overshoot and serious oscillation.When ~ > 0 and 13 > 0 the fuzzy controller becomes a PID fc, the overshoot is substantially reduced. It is possible to get a comparatively good performance by carefully choosing the value of αandβ.4. ConclusionsWe have studied the input-output behavior of the product-sum crisp type fuzzy controller, revealing that this type of fuzzy controller behaves approximately like a parameter time-varying PD controller. Therefore, the analysis and designing of a fuzzy control system can take advantage of the conventional PID control theory. According to the coventional PID control theory, we have been able to propose some improvement methods for the crisp type fuzzy controller.It has been illustrated that the PD type fuzzy controller yields a steady-state error for the type system, the PI type fuzzy controller can eliminate the steady-state error. We proposed a controller structure, that combines the features of both PD type and PI type fuzzy controller, obtaining a PID type fuzzy controller which allows the control system to have a fast rise and a small overshoot as well as a short settling time.To improve further the performance of the proposed PID type fuzzy controller, the authors designed a parameter adaptive fuzzy controller. The PID type fuzzy controller can be decomposed into the equivalent proportional control, integral control and the derivative control components. The proposed parameter adaptive fuzzy controller decreases the equivalent integral control component of the fuzzy controller gradually with the system response process time, so as to increase the damping of the system when the system is about to settle down, meanwhile keeps the proportional control component unchanged so as to guarantee quick reaction against the system's error. With the parameter adaptive fuzzy controller, the oscillation of the system is strongly restrained and the settling time is shortened considerably.We have presented the simulation results to demonstrate the fine performance of the proposed PID type fuzzy controller and the parameter adaptive fuzzy controller structure.Part 2 Application of self adaptation fuzzy-PID control for main steam temperature control system inpower stationZHI-BIN LIAbstract: In light of the large delay, strong inertia, and uncertainty characteristics of main steam temperature process, a self adaptation fuzzy-PID serial control system is presented, which not only contains the anti-disturbance performance of serial control, but also combines the good dynamic performance of fuzzy control. The simulation results show that this control system has more quickly response, better precision and stronger anti-disturbance ability．Keywords：Main steam temperature；Self adaptation；Fuzzy control；Serial control1. IntroductionThe boiler superheaters of modem thermal power station run under the condition of high temperature and high pressure, and the superheater’s temperature is highest in the steam channels．so it has important effect to the running of the whole thermal power station．If the temperature is too high, it will be probably burnt out. If the temperature is too low ,the efficiency will be reduced So the main steam temperature mast be strictly controlled near the given value．Fig l shows the boiler main steam temperature system structure.Fig.1 boiler main steam temperature systemIt can be concluded from Fig l that a good main steam temperature controlsystem not only has adequately quickly response to flue disturbance and load fluctuation, but also has strong control ability to desuperheating water disturbance. The general control scheme is serial PID control or double loop control system with derivative. But when the work condition and external disturbance change large, the performance will become instable. This paper presents a self adaptation fuzzy-PID serial control system. which not only contains the anti-disturbance performance of serial control, but also combines the good dynamic character and quickly response of fuzzy control ．1. Design of Control SystemThe general regulation adopts serial PID control system with load feed forward ．which assures that the main steam temperature is near the given value 540℃in most condition ．If parameter of PID control changeless and the work condition and external disturbance change large, the performance will become in stable ．The fuzzy control is fit for controlling non-linear and uncertain process. The general fuzzy controller takes error E and error change ratio EC as input variables ．actually it is a non-linear PD controller, so it has the good dynamic performance ．But the steady error is still in existence. In linear system theory, integral can eliminate the steady error. So if fuzzy control is combined with PI control, not only contains the anti-disturbance performance of serial control, but also has the good dynamic performance and quickly response.In order to improve fuzzy control self adaptation ability, Prof ．Long Sheng-Zhao and Wang Pei-zhuang take the located in bringing forward a new idea which can modify the control regulation online ．This regulation is:]1,0[,)1(∈-+=αααEC E UThis control regulation depends on only one parameter α.Once αis fixed ．the weight of E and EC will be fixed and the self adaptation ability will be very small ．It was improved by Prof. Li Dong-hui and the new regulation is as follow;]1,0[,,,3,)1(2,)1(1,)1(0,)1({321033221100∈±=-+±=-+±=-+=-+=ααααααααααααE EC E E EC E E EC E E EC E UBecause it is very difficult to find a self of optimum parameter, a new method is presented by Prof ．Zhou Xian-Lan, the regulation is as follow:)0(),ex p(12>--=k ke αBut this algorithm still can not eliminate the steady error ．This paper combines this algorithm with PI control ，the performance is improved ．2. Simulation of Control System3.1 Dynamic character of controlled objectPapers should be limited to 6 pages Papers longer than 6 pages will be subject to extra fees based on their length ．Fig .2 main steam temperature control system structureFig 2 shows the main steam temperature control system structure ，)(),(21s W s W δδare main controller and auxiliary controller,)(),(21s W s W o o are characters of the leading and inertia sections,)(),(21s W s W H H are measure unit.3.2 Simulation of the general serial PID control systemThe simulation of the general serial PID control system is operated by MATLAB, the simulation modal is as Fig.3.Setp1 and Setp2 are the given value disturbance and superheating water disturb & rice .PID Controller1 and PID Controller2 are main controller and auxiliary controller ．The parameter value which comes from references is as follow ：667.37,074.0,33.31)(25)(111111122===++===D I p D I p p k k k s k sk k s W k s W δδFig.3. the general PID control system simulation modal3.3 Simulation of self adaptation fuzzy-PID control system SpacingThe simulation modal is as Fig 4.Auxiliary controller is:25)(22==p k s W δ.Main controller is Fuzzy-PI structure, and the PI controller is:074.0,33.31)(11111==+=I p I p k k s k k s W δFuzzy controller is realized by S-function, and the code is as fig.5.Fig.4. the fuzzy PID control system simulation modalFig 5 the S-function code of fuzzy control3.4 Comparison of the simulationGiven the same given value disturbance and the superheating water disturbance，we compare the response of fuzzy-PID control system with PID serial control system. The simulation results are as fig.6-7.From Fig6-7,we can conclude that the self adaptation fuzzy-PID control system has the more quickly response, smaller excess and stronger anti-disturbance．4. Conclusion(1)Because it combines the advantage of PID controller and fuzzy controller, theself adaptation fuzzy-PID control system has better performance than the general PID serial control system.(2)The parameter can self adjust according to the error E value. so this kind of controller can harmonize quickly response with system stability．Part 3 Neuro-fuzzy generalized predictive controlof boiler steam temperatureXiangjie LIU, Jizhen LIU, Ping GUANAbstract: Power plants are nonlinear and uncertain complex systems. Reliable control of superheated steam temperature is necessary to ensure high efficiency and high load-following capability in the operation of modern power plant. A nonlinear generalized predictive controller based on neuro-fuzzy network (NFGPC) is proposed in this paper. The proposed nonlinear controller is applied to control the superheated steam temperature of a 200MW power plant. From the experiments on the plant and the simulation of the plant, much better performance than the traditional controller is obtained.Keywords: Neuro-fuzzy networks; Generalized predictive control; Superheated steam temperature1. IntroductionContinuous process in power plant and power station are complex systems characterized by nonlinearity, uncertainty and load disturbance. The superheater is an important part of the steam generation process in the boiler-turbine system, where steam is superheated before entering the turbine that drives the generator. Controlling superheated steam temperature is not only technically challenging, but also economically important.From Fig.1,the steam generated from the boiler drum passes through the low-temperature superheater before it enters the radiant-type platen superheater. Water is sprayed onto the steam to control the superheated steam temperature in both the low and high temperature superheaters. Proper control of the superheated steam temperature is extremely important to ensure the overall efficiency and safety of the power plant. It is undesirable that the steam temperature is too high, as it can damage the superheater and the high pressure turbine, or too low, as it will lower the efficiency of the power plant. It is also important to reduce the temperaturefluctuations inside the superheater, as it helps to minimize mechanical stress that causes micro-cracks in the unit, in order to prolong the life of the unit and to reduce maintenance costs. As the GPC is derived by minimizing these fluctuations, it is amongst the controllers that are most suitable for achieving this goal.The multivariable multi-step adaptive regulator has been applied to control the superheated steam temperature in a 150 t/h boiler, and generalized predictive control was proposed to control the steam temperature. A nonlinear long-range predictive controller based on neural networks is developed into control the main steam temperature and pressure, and the reheated steam temperature at several operating levels. The control of the main steam pressure and temperature based on a nonlinear model that consists of nonlinear static constants and linear dynamics is presented in that.Fig.1 The boiler and superheater steam generation process Fuzzy logic is capable of incorporating human experiences via the fuzzy rules. Nevertheless, the design of fuzzy logic controllers is somehow time consuming, as the fuzzy rules are often obtained by trials and errors. In contrast, neural networks not only have the ability to approximate non-linear functions with arbitrary accuracy, they can also be trained from experimental data. The neuro-fuzzy networks developed recently have the advantages of model transparency of fuzzy logic and learning capability of neural networks. The NFN is have been used to develop self-tuning control, and is therefore a useful tool for developing nonlinear predictive control. Since NFN is can be considered as a network that consists of several local re-gions, each of which contains a local linear model, nonlinear predictive control based onNFN can be devised with the network incorporating all the local generalized predictive controllers (GPC) designed using the respective local linear models. Following this approach, the nonlinear generalized predictive controllers based on the NFN, or simply, the neuro-fuzzy generalized predictive controllers (NFG-PCs)are derived here. The proposed controller is then applied to control the superheated steam temperature of the 200MW power unit. Experimental data obtained from the plant are used to train the NFN model, and from which local GPC that form part of the NFGPC is then designed. The proposed controller is tested first on the simulation of the process, before applying it to control the power plant.2. Neuro-fuzzy network modellingConsider the following general single-input single-output nonlinear dynamic system:),1(),...,(),(),...,1([)(''+-----=uy n d t u d t u n t y t y f t y ∆+--/)()](),...,1('t e n t e t e e (1)where f[.]is a smooth nonlinear function such that a Taylor series expansion exists, e(t)is a zero mean white noise and Δis the differencing operator,''',,e u y n n n and d are respectively the known orders and time delay of the system. Let the local linear model of the nonlinear system (1) at the operating point )(t o be given by the following Controlled Auto-Regressive Integrated Moving Average (CARIMA) model:)()()()()()(111t e z C t u z B z t y z A d ----+∆= (2) Where )()(),()(1111----∆=z andC z B z A z A are polynomials in 1-z , the backward shift operator. Note that the coefficients of these polynomials are a function of the operating point )(t o .The nonlinear system (1) is partitioned into several operating regions, such that each region can be approximated by a local linear model. Since NFN is a class of associative memory networks with knowledge stored locally, they can be applied to model this class of nonlinear systems. A schematic diagram of the NFN is shown in Fig.2.B-spline functions are used as the membership functions in theNFN for the following reasons. First, B-spline functions can be readily specified by the order of the basis function and the number of inner knots. Second, they are defined on a bounded support, and the output of the basis function is always positive, i.e.,],[,0)(j k j j k x x λλμ-∉=and ],[,0)(j k j j k x x λλμ-∈>.Third, the basis functions form a partition of unity, i.e.,.][,1)(min,∑∈≡j mam j k x x x x μ(3)And fourth, the output of the basis functions can be obtained by a recurrence equation.Fig. 2 neuro-fuzzy network The membership functions of the fuzzy variables derived from the fuzzy rules can be obtained by the tensor product of the univariate basis functions. As an example, consider the NFN shown in Fig.2, which consists of the following fuzzy rules: IF operating condition i (1x is positive small, ... , and n x is negative large),THEN the output is given by the local CARIMA model i:...)()(ˆ...)1(ˆ)(ˆ01+-∆+-++-=d t u b n t y a t y a t yi i a i in i i i a )(...)()(c i in i b i in n t e c t e n d t u b c b -+++--∆+ (4)or )()()()()(ˆ)(111t e z C t u z B z t yz A i i i i d i i ----+∆= (5) Where )()(),(111---z andC z B z A i i i are polynomials in the backward shift operator 1-z , and d is the dead time of the plant,)(t u i is the control, and )(t e i is a zero mean independent random variable with a variance of 2δ. The multivariate basis function )(k i x a is obtained by the tensor products of the univariate basis functions,p i x A a nk k i k i ,...,2,1,)(1==∏=μ (6)where n is the dimension of the input vector x , and p , the total number of weights in the NFN, is given by,∏=+=nk i i k R p 1)( (7)Where i k and i R are the order of the basis function and the number of inner knots respectively. The properties of the univariate B-spline basis functions described previously also apply to the multivariate basis function, which is defined on the hyper-rectangles. The output of the NFN is,∑∑∑=====p i i i p i ip i i i a y aa yy 111ˆˆˆ (8) 3. Neuro-fuzzy modelling and predictive control of superheatedsteam temperatureLet θbe the superheated steam temperature, and θμ, the flow of spray water to the high temperature superheater. The response of θcan be approximated by a second order model:The linear models, however, only a local model for the selected operating point. Since load is the unique antecedent variable, it is used to select the division between the local regions in the NFN. Based on this approach, the load is divided into five regions as shown in Fig.3,using also the experience of the operators, who regard a load of 200MW as high,180MW as medium high,160MW as medium,140MW as medium low and 120MW as low. For a sampling interval of 30s , the estimated linear local models )(1-z A used in the NFN are shown in Table 1.Fig. 3 Membership function for local modelsTable 1 Local CARIMA models in neuro-fuzzy modelCascade control scheme is widely used to control the superheated steam temperature. Feed forward control, with the steam flow and the gas temperature as inputs, can be applied to provide a faster response to large variations in these two variables. In practice, the feed forward paths are activated only when there are significant changes in these variables. The control scheme also prevents the faster dynamics of the plant, i.e., the spray water valve and the water/steam mixing, from affecting the slower dynamics of the plant, i.e., the high temperature superheater. With the global nonlinear NFN model in Table 1, the proposed NFGPC scheme is shown in Fig.4.Fig. 4 NFGPC control of superheated steam temperature with feed-for-ward control.As a further illustration, the power plant is simulated using the NFN model given in Table 1,and is controlled respectively by the NFGPC, the conventional linear GPC controller, and the cascaded PI controller while the load changes from 160MW to 200MW.The conventional linear GPC controller is the local controller designed for the“medium”operating region. The results are shown in Fig.5,showing that, as expected, the best performance is obtained from the NFGPC as it is designed based on a more accurate process model. This is followed by the conventional linear GPC controller. The performance of the conventional cascade PI controller is the worst, indicating that it is unable to control satisfactory the superheated steam temperature under large load changes. This may be the reason for controlling the power plant manually when there are large load changes.Fig.5 comparison of the NFGPC, conventional linear GPC, and cascade PI controller.4. ConclusionsThe modeling and control of a 200 MW power plant using the neuro-fuzzy approach is presented in this paper. The NFN consists of five local CARIMA models.The out-put of the network is the interpolation of the local models using memberships given by the B-spline basis functions. The proposed NFGPC is similarly constructed, which is designed from the CARIMA models in the NFN. The NFGPC is most suitable for processes with smooth nonlinearity, such that its full operating range can be partitioned into several local linear operating regions. The proposed NFGPC therefore provides a useful alternative for controlling this class of nonlinear power plants, which are formerly difficult to be controlled using traditional methods.Part 4 为Part3译文：锅炉蒸汽温度模糊神经网络的广义预测控制Xiangjie LIU, Jizhen LIU, Ping GUAN摘要：发电厂是非线性和不确定性的复杂系统。
济南大学毕业设计外文资料翻译参考格式(理工科类)2014
Powder Technology ,2007,178:114–118)Regulating characteristics of loop seal in a 65 t/h oil shale-fired circulating fluidized bed boilerXiangxin Han, Zhigang Cui, Xiumin Jiang⁎, Jianguo LiuInstitute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China摘要本文对65t/h油页岩燃烧流化床锅炉的环封调节特性的研究是为了引导一个工业冷却试验。
环封的起始特性、空气供给度的影响和密闭液态空气是需要调查的。
与其他的校正模型比，保持流化空气速率恒定和调节供应空气流量的联合监控模式可使环封获得更好的调节质量，也为循环流化床锅炉稳定运行提供更可靠的保证。
为了防止循环材料在循环底部的沉积和结渣,流化空气流量和空气供应度最好为分别为循环材料的最小流化速度的2-3倍和1.2-1.5倍。
这些实验结果可以为调节65t/h循环流化床锅炉的热条件和设计一个新的环封作为一个参考。
关键词油页岩，循环流化床，环封，调节特性曲线1.引言油页岩的燃烧技术主要包括粉燃料炉、气泡流化床和循环流化床。
因为它非常低的污染排放量和对低级的化石燃料的良好适应性,油页岩循环流化床技术已经被广泛认为是在所有油页岩的利用率模式中最干净、最经济的途径。
作为一个循环流化床锅炉循环回路的重要组成部分,固体循环回收系统控制固体循环率。
一般来说,有两种类型的阀门可用于固体循环系统:一类是是机械阀,另一类是是非机械阀。
典型机械阀门有旋转形，螺丝形,蝶形,和滑动形阀门,机械的移动部件驱动并控制燃料的流动率。
锅炉的计算机控制外文翻译外文文献英文文献
英文翻译Boiler computer controlBoiler computer control：The boiler micro computer control, is a new technology which the recent years developed, it was the microcomputer soft, the hardware, the automatic control, the boiler energy conservation and soon several technical in close integration with product, our country existing center, small boiler more than 300,000, the coal consumption accounted for our country raw coal output every year 1/3, at present the majority industry boiler still was at the energy consumption to be high, to waste, the environmental pollution in a big way and so on the serious production condition. Enhances the thermal efficiency, reduces the coal consumption, carries on the control with the microcomputer is has the profound significance the work. As the boiler control device, its primary mission is guaranteed the boiler the security, is stable, the economical movement, reduces operator's labor intensity. Uses the micro computer control, can carry on the process to the boiler the automatic detection, the automatic control and so on many functions. The boiler microcomputer control system, generally is composed by the below several parts, namely by the boiler main body, a measuring appliance, the microcomputer, the hand automatic cut over operation, the implementing agency and the valve, the slippery difference electrical machinery and so on partially is composed, a measuring appliance the boiler temperature, the pressure, the current capacity, the oxygen quantity, the rotational speed isometric transforms the voltage, the electric current and so on sends in the microcomputer, the hand automatic cut over operation part, manual when by the operator hand control, controls the slippery difference electrical machinery and the valve with themanipulator and so on, is automatic when sends out the control signal to the microcomputer partially to carry on the automatic operation after the execution. The microcomputer carries on the monitor to the entire boiler movement, reports to the police, the control guaranteed the boiler is normal, reliably moves, except for this for guaranteed the boiler movement these curity, when carries on the microcomputer system design, to the boiler water level, the boiler dome pressure and so on the important parameter should establish the conventional measuring appliance and the alarm device, guaranteed the water level and the dome pressure have the dual even tertiary alarm device, this is essential, in order to avoid the boiler has the significant accident.Control system:The boiler is a more complex controlled member, it not only adjustment quantity many, moreover between various types and quantities mutually relates, mutually affects, mutually restricts, boiler interior energy conversion mechanism quite complex, therefore must establish a more ideal mathematical model to the boiler quite to be difficult. Therefore, has made the boiler system simplification processing, decomposes is three relatively independent governing systems. Certainly also may subdivide other system like amount of wind control loops in certain systems, but it mainly is following three parts: (1) the chamber negative pressure (2) the boiler combustion process has three duties for the main tuning quantity special burning regulator system: To coal control, to wind control, chamber negative pressure control. The maintenance coal gas and the air proportion cause the air too much coefficient about 1.08, the combustion process efficiency, the maintenance chamber negative pressure, therefore the boiler combustion process automatic control is a complex question. As for 3×6.5t/h the boiler burning diffuses the blast furnace coal gas, the request is the blast furnace coal gas which maximum limit uses diffuses, therefore may most greatly strive according to the boiler to move, does not make the strict request to the steam pressure; The burning efficiency does not make a higher request. Such boiler combustion process automatic control simplifies as the chamber negativepressure primarily parameter decides the coal gas flow control. (3) the chamber negative pressure Pf size is directed the amount of wind, the drum amount of wind and the coal spirit (pressure)three influences. The chamber negative pressure too is small, the chamber and outside divulges the blast furnace coal gas to the outside to riching, endangers the equipment and the movement personnel's security. The negative pressure too is big, the chamber leaks the amount of wind to increase, discharges fume the loss to increase, drawing fan electricity consumes the increase. Tried to find out according to the many years man-power manual regulation that, 6.5t/hboiler Pf=100Pa carries on the design. The adjustment method is the original state first by the manual regulation air and the coal gas proportion, achieved the ideal burning condition, all opens when the drawing fan achieved chamber negative pressure 100Pa, after the investment is automatic, only adjusts the coal gas reed valve, enable under the fluctuation of pressure the blast furnace coal gas current capacity to tend to the original state coal gas current capacity, maintains in burning the blast furnace coal gas and the air proportion achieves the optimum condition.Boiler water-level control unit ：The steam drum water level is affects the boiler safe operation the important parameter, the water level excessively high, can destroy the soft drink disengaging gear the normal work, is serious when can cause the steam including water to increase, increases on the pipe wall the scaling and the influence steam quality. Water level excessively low, then can destroy the water cycle, causes Water Wall bursting, is serious when can create does the pot, damages the steam drum. Therefore its value has outdone lowly all possibly creates the significant accident. It is adjusted the quantity is the steam drum water level, but adjusts the quantity is for the water current capacity, through to gives the water current capacity the adjustment, enables the steam drum interior the material to achieve the dynamical equilibrium, changes in the permission scope, because the boiler steam drum water level assumes the positive character isticto the vapor current capacity and for the fluent quantity changer But when load (vapor current capacity) sharp growth, the performance actually is "Counter response characteristic "Namely so-called " False water level " Creates this reason is because time load increase, causes the dome pressure to drop, causes the steam drum boiling temperature to drop, the water ebullition suddenly intensifies, forms the massive steam bubbles, but makes the water level to raise. The steam drum water monitor system, in the essence is maintains the boiler turnover water volume balance the system. It is by the water level took the water volume balance or not control target, through adjusts the water volume how many to achieve the turnover balance, maintains the steam drum water level in the soft drink separation contact surface biggest steam drum nearby the position line, enhances the boiler the vaporization efficiency, the guarantee production safety. Because the boiler water level system is equipped with Since the balance the ability to control the object, in the movement has the false water level phenomenon, in the practical application may use the water level single impulse, the water level steam quantity double weight and the water level, the steam quantity according to the situation, gives the water volume three impulses the control systems. Eliminates the oxygen pressure and the water-level control: Partially eliminates the oxygen to use the single impulse control plan, single return route PID adjustment.Monitoring management system management system:Above the control system generally completes the control by PLC or other hardware systems below, but must complete the function in on position computer: Real-time accurately examines the boiler the movement parameter: For comprehensively grasps the overall system the movement operating mode, the supervisory system the real-time monitor and the gathering boiler related craft parameter, the electrical parameter, as well as the equipment running status and so on. The system has the rich graph storehouse, through the configuration may the boiler equipment graph together with the related movement parameter demonstration in the picture; In addition, but also can tabulate the parameter or form and so on grouping demonstrates. The generalized analysis promptly sends out the control command: The supervisory system basis monitors the boiler performance data, according to the control strategy which establishes, sends out the control command, adjusts the boilersystem equipment the movement, thus guaranteed the boiler is highly effective, the reliable movement.(1) diagnoses the breakdown with to report to the police the management: The host controls the center to be allowed to demonstrate, the management, the transmission boiler movement each kind of alarm, thus causes boiler safe explosion-proof, the safe operation rank big enhancement. At the same time, to the records management which reports to the police may cause the owner regarding boiler movement each kind of question, weakness and so on to know from A to Z. In order to guarantee the boiler systematic security, reliably moves, the supervisory system will act according to the parameter which will monitor to carry on the breakdown diagnosis, once will break down, the supervisory system promptly on the operator screen the visual display alarm spot. Reports to the police the correlation demonstration function to cause the user definition the demonstration picture to relate with each spot, like this, when reports to the police occurs, the operator may immediately visit should report to the police the emergency procedures which detailed information and defers to recommends adopts to carry on processing. (2) historic record movement parameter: The supervisory system real-time database will maintain the boiler movement parameter the historic record, moreover supervisory system also. Is equipped with special reports to the police the event diary, with records reports to the police/the event information and operator's change The historic record data basis operator's request, the system may demonstrate is the spurt value, also may for some period of time in mean value. The historic record data may have the many kinds of display mode, for example display mode and so on curve, specific graph, report form; In addition the historic record data also may by apply take the network as the foundation many kinds of application software. (3) calculates the movement parameter: The boiler movement certain movement parameters cannot directly survey ,like the year movement load, the steam consumption, make up the water volume, the condensed water returns to the quantity, the equipment accumulation running time and so on. The supervisory system has provided the rich standard processing algorithm, according to movement parameter which obtains, Derived quantity calculates these.译文:锅炉的计算机控制锅炉的计算机控制：锅炉微计算机控制，是近年来开发的一项新技术，它是微型计算机软、硬件、自动控制、锅炉节能等几项技术紧密结合的产物，我国现有中、小型锅炉30多万台，每年耗煤量占我国原煤产量的1/3，目前大多数工业锅炉仍处于能耗高、浪费大、环境污染等严重的生产状态。
燃煤锅炉 外文翻译 外文文献 英文文献 中英翻译
Controlling the Furnace Process in Coal-Fired BoilersThe unstable trends that exist in the market of fuel supplied to thermal power plants and the situations in which the parameters of their operation need to be changed (or preserved), as well as the tendency toward the economical and environmental requirements placed on them becoming more stringent, are factors that make the problem of controlling the combustion and heat transfer processes in furnace devices very urgent. The solution to this problem has two aspects. The first involves development of a combustion technology and,accordingly, the design of a furnace device when new installations are designed. The second involves modernization of already existing equipment. In both cases,the technical solutions being adopted must be properly substantiated with the use of both experimental and calculation studies.The experience Central Boiler-Turbine Institute Research and Production Association (Ts KTI) and Zi O specialists gained from operation of boilers and experimental investigations they carried out on models allowed them to propose several new designs of multicell and maneuverable—in other words, controllable—furnace devices that had been put in operation at power stations for several years. Along with this, an approximate zero-one-dimensional, zone wise calculation model of the furnace process in boilers had been developed at the Tsk Ti, which allowed Tsk Ti specialists to carry out engineering calculations of the main parameters of this process and calculate studies of furnaces employing different technologies of firing and combustion modes .Naturally, furnace process adjustment methods like changing the air excess factor, stack gas recirculation fraction, and distribution of fuel and air among the tiers of burners, as well as other operations written in the boiler operational chart, are used during boiler operation.However, the effect they have on the process is limited in nature. On the other hand, control of the furnace process in a boiler implies the possibility of making substantial changes in the conditions under which the combustion and heat transfer proceed in order to considerably expand the range ofloads, minimize heat losses, reduce the extent to which the furnace is contaminated with slag, decrease the emissions of harmful substances, and shift to another fuel. Such a control can be obtained by making use of the following three main factors:(i) the flows of oxidizer and gases being set to move in the flame in a desired aerodynamic manner;(ii) the method used to supply fuel into the furnace and the place at which it is admitted thereto;(iii) the fineness to which the fuel is milled.The latter case implies that a flame-bed method is used along with the flame method for combusting fuel.The bed combustion method can be implemented in three design versions: mechanical grates with a dense bed, fluidized-bed furnaces, and spouted-bed furnaces.As will be shown below, the first factor can be made to work by setting up bulky vorticisms transferring large volumes of air and combustion products across and along the furnace device. If fuel is fired in a flame, the optimal method of feeding it to the furnace is to admit it to the zones near the centers of circulating vorticisms, a situation especially typical of highly intense furnace devices. The combustion process in these zones features a low air excess factor (α< 1) and a long local time for which the components dwell in them, factors that help make the combustion process more stable and reduce the emission of nitrogen oxides .Also important for the control of a furnace process when solid fuel is fired is the fineness to which it is milled; if we wish to minimize incomplete combustion, the degree to which fuel is milled should be harmonized with the location at which the fuel is admitted into the furnace and the method for supplying it there, for the occurrence of unburned carbon may be due not only to incomplete combustion of large-size fuel fractions, but also due to fine ones failing to ignite (especially when the content of volatiles Daff < 20%).Owing to the possibility of pictorially demonstrating the motion of flows, furnace aerodynamics is attracting a great deal of attention of researchers and designers who develop and improve furnace devices. At the same time, furnace aerodynamics lies at the heart of mixing (mass transfer), a process the quantitativeparameters of which can be estimated only indirectly or by special measurements. The quality with which components are mixed in the furnace chamber proper depends on the number, layout, and momenta of the jets flowing out from individual burners or nozzles, as well as on their interaction with the flow of flue gases, with one another, or with the wall.It was suggested that the gas-jet throw distance be used as a parameter determining the degree to which fuel is mixed with air in the gas burner channel. Such an approach to estimating how efficient the mixing is may to a certain degree be used in analyzing the furnace as a mixing apparatus. Obviously, the greater the jet length (and its momentum), the longer the time during which the velocity gradient it creates in the furnace will persist there, a parameter that determines how completely the flows are mixed in it. Note that the higher the degree to which a jet is turbulence at the outlet from a nozzle or burner, the shorter the distance which it covers, and, accordingly, the less completely the components are mixed in the furnace volume. Once through burners have advantages over swirl ones in this respect.It is was proposed that the extent to which once through jets are mixed as they penetrate with velocity w2 and density ρ2 into a transverse (drift) flow moving with velocity w1 and having density ρ1 be correlated with the relative jet throw distance in the following wayWhere ks is a proportionality factor that depends on the “pitch” between the jet axes (ks= 1.5–1.8).The results of an experimental investigation in which the mixing of gas with air in a burner and then in a furnace was studied using the incompleteness of mixing as a parameter are reported in 5.A round once through jet is intensively mixed with the surrounding medium in a furnace within its initial section, where the flow velocity at the jet axis is still equal to the velocity w2 at the nozzle orifice of radius r0.The velocity of the jet blown into the furnace drops very rapidly beyond the confines of the initial section, and the axis it has in the case of wall-mounted burners bends toward the outlet from the furnace.One may consider that there are three theoretical models for analyzing the mixing of jets with flow rate G2 that enter into a stream with flow rate G1. The firstmodel is for the case when jets flow into a “free” space (G1= 0),the second model is for the case when jets flow into a transverse (drift) current with flow rate G1 G2，and the third model is for the case when jets flow into a drift stream with flow rateG1<G2. The second model represents mixing in the channel of a gas burner, and the third model represents mixing in a furnace chamber. We assume that the mixing pattern we have in a furnace is closer to the first model than it is to the second one, since 0 <G1/G2< 1, and we will assume that the throw distance h of the jet being drifted is equal to the length S0 of the “free” jet’s initial section. The ejection ability of the jet being drifted then remains the same as that of the “free” jet, and the length of the initial section can be determined using the well-known empirical formula of G.N. Amphibrachic [6] ：S0= 0.67r0/a, (2)where a is the jet structure factor and r0 is the nozzle radius.At a = 0.07, the length of the round jet’s initial section is equal to 10 r0 and the radius the jet has at the transition section (at the end of the initial section) is equal to 3.3 r0. The mass flow rate in the jet is doubled in this case. The corresponding minimum furnace cross-sectional area Ff for a round once through burner with the outlet cross-sectional area Fb will then be equal to and t he ratio Ff/Fb≈20. This value is close to the actual values found in furnaces equipped with once through burners. In furnaces equipped with swirl burners, a= 0.14 and Ff/Fb≈10. In both cases, the interval between the burners is equal to the jet diameter in the transition section d tr , which differs little from the value that has been established in practice and recommended in [7].The method traditionally used to control the furnace process in large boilers consists of equipping them with a large number of burners arranged in several tiers. Obviously, if the distance between the tiers is relatively small, operations on disconnecting or connecting them affect the entire process only slightly. A furnace design employing large flat-flame burners equipped with means for controlling the flame core position using the aerodynamic principle is a step forward. Additional possibilities for controlling the process in TPE-214 and TPE-215 boilers with a steam output of 670 t/h were obtained through the use of flat-flame burners arranged in two tiers with a large distance between the tiers; this made it possible not only to raise orlower the flame, but also to concentrate or disperse the release of heat in it [1]. A very tangible effect was obtained from installing multicell (operating on coal andopen-hearth, coke, and natural gases) flat-flame burners in the boilers of cogeneration stations at metallurgical plants in Ukraine and Russia.Unfortunately, we have to state that, even at present, those in charge of selecting the type, quantity, and layout of burners in a furnace sometimes adopt technical solutions that are far from being optimal. This problem should therefore be considered in more detail.If we increase the number of burners nb in a furnace while retaining their total cross-sectional area (ΣFb=idem) and the total flow rate of air through them, their equivalent diameters deq will become smaller, as will the jet momentums GB, resulting in a corresponding decrease in the jet throw distance Hb and the mass they eject. The space with high velocity gradients also becomes smaller, resulting in poorer mixing in the furnace as a whole. This factor becomes especially important when the emissions of Box and CO are suppressed right inside the furnace using staged combustio n (at αb < 1) under the conditions of a Fortinbras nonuniform distribution of fuel among the burners.In [1], a quantitative relationship was established between the parameters characterizing the quality with which once through jets mix with one another as they flow into a limited space with the geometrical parameter of concentration = with nb = idem and GB = idem. By decreasing this parameter we improve the mass transfer in the furnace; however, this entails an increase in the flow velocity and the expenditure of energy (pressure drop) in the burners with the same Fb. At the same time, we know from experience and calculations that good mixing in a furnace can be obtained without increasing the head loss if we resort to large long-range jets. This allows a much less stringent requirement to be placed on the degree of uniformity with which fuel must be distributed among the burners. Moreover, fuel may in this case be fed to the furnace location where it is required from process control considerations.For illustration purposes, we will estimate the effect the number of burners has on the mixing in a furnace at = = idem. schematically shows the plan views of two furnace chambers differing in the number of once through round nozzles (two andfour) placed in a tier (on one side of the furnace). The furnaces have the same total outlet cross-sectional areas of the nozzles (ΣF b) and the same jet velocities related to these areas (wb). The well-known swirl furnace of the TsKTI has a design close to the furnace arrangement under consideration. According to the data of [1], the air fraction βair that characterizes the mixing and enters through once through burners into the furnace volume beneath them can be estimated using the formula βair = 1 – (3) which has been verified in the range = 0.03–0.06 for a furnace chamber equipped with two frontal once through burners. Obviously, if we increase the number of burners by a factor of 2, their equivalent diameter, the length of the initial section of jets S0 and the area they “serve” will reduce by a factor of Then, for example, at = 0.05, the fraction βair will decrease from 0.75 to 0.65. Thus, Eq. (3) may be written in the following form for approximately assessing the effect of once through burners on the quality of mixing in a furnace:βair = 1 – 3.5f nb ' ,where is the number of burners (or air nozzles) on one wall when they are arranged in one tier both in onesided and opposite manners.The number of burners may be tentatively related to the furnace depth af (at the same = idem) using the expression (5)It should be noted that the axes of two large opposite air nozzles ( = 1)—an arrangement implemented in an inverted furnace—had to be inclined downward by more than 50° [8].One well-known example of a furnace device in which once through jets are used to create a large vortex covering a considerable part of its volume is a furnace with tangentially arranged burners. Such furnaces have received especially wide usein combination with pulverizing fans. However, burners with channels having a small equivalent diameter are frequently used for firing low-calorific brown coals with high content of moisture. As a result, the jets of air-dust mixture and secondary air that go out from their channels at different velocities(w2/w1 = 2–3) become turbulence and lose the ability to be thrown a long distance; as a consequence, the flame comes closer to the water walls and the latter are contaminated with slag. One method by which the tangential combustion scheme can be improved consists of organizing the so-called concentric admission of large jets of air-dust mixture and secondary air with the fueland air nozzles spaced apart from one another over the furnace perimeter, accompanied by intensifying the ventilation of mills [9, 10]. Despite the fact that the temperature level in the flame decreases, the combustion does not become less stable because the fuel mixes with air in a stepwise manner in a horizontal plane.V ortex furnace designs with large cortices the rotation axes of which are arranged transversely with respect to the main direction of gas flow have wide possibilities in terms of controlling the furnace process. In [1], four furnace schemes with a controllable flame are described, which employ the principle of large jets colliding with one another; three of these schemes have been implemented. A boiler with a steam capacity of 230 t/h has been retrofitted in accordance with one of these schemes (with an inverted furnace) . Tests of this boiler, during which air-dust mixture was fed at a velocity of 25–30 m/s from the boiler front using a high concentration dust system, showed that the temperature of gases at the outlet from the furnace had a fairly uniform distribution both along the furnace width and depth . A simple method of shifting the flame core over the furnace height was checked during the operation of this boiler, which consisted of changing the ratio of air flow rates through the front and rear nozzles;this allowed a shift to be made from running the furnace in adry-bottom mode to a slag-tap mode and vice Versace. A bottom-blast furnace scheme has received rather wide use in boilers equipped with different types of burners and mills. Boilers with steam capacities ranging from 50 to 1650 t/h with such an aerodynamic scheme of furnaces manufactured by ZiO and Bergomask have been installed at a few power stations in Russia and abroad . We have to point out that, so far as the efficiency of furnace process control is concerned, a combination of the following two aerodynamic schemes is of special interest: the inverted scheme and the bottom-blast one. The flow pattern and a calculation analysis of the furnace process in such a furnace during the combustion of lean coal are presented in [13].Below, two other techniques for controlling the furnace process are considered. Boilers with flame–stoker furnaces have gained acceptance in industrial power engineering, devices that can be regarded to certain degree as controllable ones owing to the presence of two zones in them . Very different kinds of fuel can be jointly combusted in these furnaces rather easily. An example of calculating such a furnacedevice is given in [2]. As for boilers of larger capacity, work on developing controllable two-zone furnaces is progressing slowly . The development of a furnace device using the so-called VIR technology (the transliterated abbreviation of the Russian introduction, innovation, and retrofitting) can be considered as holding promise in this respect. Those involved in bringing this technology to the state of industry standard encountered difficulties of an operational nature (the control of the process also presented certain difficulties). In our opinion, these difficulties are due to the fact that the distribution of fuel over fractions can be optimized to a limited extent and that the flow in the main furnace volume has a rather sluggish aerodynamic structure. It should also be noted that the device for firing the coarsest fractions of solid fuel in a spouting bed under the cold funnel is far from being technically perfect.Centrifugal dust concentrators have received acceptance for firing high-reactive coals in schemes employing pulverizing fans to optimize the distribution of fuel as to its flow rate and fractions. The design of one such device is schematically shown in [9]. Figure shows a distribution of fuel flow rates among four tiers of burners that is close to the optimum one. This distribution can be controlled if we furnish dust concentrators with a device with variable blades, a solution that has an adequate effect on the furnace process.燃煤锅炉的燃烧进程控制存在于火电厂的市场的燃料供应，某些操作参数需要改变（或保留）的情况下，以及经济和环境方面倾向的要求使他们变得更加严格的不稳定趋势是导致使控制燃烧与传热过程炉设备非常紧迫的主要因素。
燃煤锅炉的燃烧进程控制大学毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：燃煤锅炉的燃烧进程控制文献、资料英文题目：Controlling the Furnace Process in Coal-Fired Boilers文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14Controlling the Furnace Process in Coal-Fired BoilersThe unstable trends that exist in the market of fuel supplied to thermal power plants and the situations in which the parameters of their operation need to be changed (or preserved), as well as the tendency toward the economical and environmental requirements placed on them becoming more stringent, are factors that make the problem of controlling the combustion and heat transfer processes in furnace devices very urgent. The solution to this problem has two aspects. The first involves development of a combustion technology and,accordingly, the design of a furnace device when new installations are designed. The second involves modernization of already existing equipment. In both cases,the technical solutions being adopted must be properly substantiated with the use of both experimental and calculation studies.The experience Central Boiler-Turbine Institute Research and Production Association (Ts KTI) and Zi O specialists gained from operation of boilers and experimental investigations they carried out on models allowed them to propose several new designs of multicell and maneuverable—in other words, controllable—furnace devices that had been put in operation at power stations for several years. Along with this, an approximate zero-one-dimensional, zone wise calculation model of the furnace process in boilers had been developed at the Tsk Ti, which allowed Tsk Ti specialists to carry out engineering calculations of the main parameters of this process and calculate studies of furnaces employing different technologies of firing and combustion modes .Naturally, furnace process adjustment methods like changing the air excess factor, stack gas recirculation fraction, and distribution of fuel and air among the tiers of burners, as well as other operations written in the boiler operational chart, are used during boiler operation.However, the effect they have on the process is limited in nature. On the other hand, control of the furnace process in a boiler implies the possibility of making substantial changes in the conditions under which the combustion and heat transfer proceed in order to considerably expand the range of loads, minimize heat losses, reduce the extent to which the furnace is contaminatedwith slag, decrease the emissions of harmful substances, and shift to another fuel. Such a control can be obtained by making use of the following three main factors:(i) the flows of oxidizer and gases being set to move in the flame in a desired aerodynamic manner;(ii) the method used to supply fuel into the furnace and the place at which it is admitted thereto;(iii) the fineness to which the fuel is milled.The latter case implies that a flame-bed method is used along with the flame method for combusting fuel.The bed combustion method can be implemented in three design versions: mechanical grates with a dense bed, fluidized-bed furnaces, and spouted-bed furnaces.As will be shown below, the first factor can be made to work by setting up bulky vorticisms transferring large volumes of air and combustion products across and along the furnace device. If fuel is fired in a flame, the optimal method of feeding it to the furnace is to admit it to the zones near the centers of circulating vorticisms, a situation especially typical of highly intense furnace devices. The combustion process in these zones features a low air excess factor (α< 1) and a long local time for which the components dwell in them, factors that help make the combustion process more stable and reduce the emission of nitrogen oxides .Also important for the control of a furnace process when solid fuel is fired is the fineness to which it is milled; if we wish to minimize incomplete combustion, the degree to which fuel is milled should be harmonized with the location at which the fuel is admitted into the furnace and the method for supplying it there, for the occurrence of unburned carbon may be due not only to incomplete combustion of large-size fuel fractions, but also due to fine ones failing to ignite (especially when the content of volatiles Daff < 20%).Owing to the possibility of pictorially demonstrating the motion of flows, furnace aerodynamics is attracting a great deal of attention of researchers and designers who develop and improve furnace devices. At the same time, furnace aerodynamics lies at the heart of mixing (mass transfer), a process the quantitative parameters of which can be estimated only indirectly or by special measurements. Thequality with which components are mixed in the furnace chamber proper depends on the number, layout, and momenta of the jets flowing out from individual burners or nozzles, as well as on their interaction with the flow of flue gases, with one another, or with the wall.It was suggested that the gas-jet throw distance be used as a parameter determining the degree to which fuel is mixed with air in the gas burner channel. Such an approach to estimating how efficient the mixing is may to a certain degree be used in analyzing the furnace as a mixing apparatus. Obviously, the greater the jet length (and its momentum), the longer the time during which the velocity gradient it creates in the furnace will persist there, a parameter that determines how completely the flows are mixed in it. Note that the higher the degree to which a jet is turbulence at the outlet from a nozzle or burner, the shorter the distance which it covers, and, accordingly, the less completely the components are mixed in the furnace volume. Once through burners have advantages over swirl ones in this respect.It is was proposed that the extent to which once through jets are mixed as they penetrate with velocity w2 and density ρ2 into a transverse (drift) flow moving with velocity w1 and having density ρ1 be correlated with the relative jet throw distance in the following wayWhere ks is a proportionality factor that depends on the ―pitch‖ between the jet axes (ks= 1.5–1.8).The results of an experimental investigation in which the mixing of gas with air in a burner and then in a furnace was studied using the incompleteness of mixing as a parameter are reported in 5.A round once through jet is intensively mixed with the surrounding medium in a furnace within its initial section, where the flow velocity at the jet axis is still equal to the velocity w2 at the nozzle orifice of radius r0.The velocity of the jet blown into the furnace drops very rapidly beyond the confines of the initial section, and the axis it has in the case of wall-mounted burners bends toward the outlet from the furnace.One may consider that there are three theoretical models for analyzing the mixing of jets with flow rate G2 that enter into a stream with flow rate G1. The first model is for the case when jets flow into a ―free‖ space (G1= 0),the second model isfor the case when jets flow into a transverse (drift) current with flow rate G1 G2，and the third model is for the case when jets flow into a drift stream with flow rateG1<G2. The second model represents mixing in the channel of a gas burner, and the third model represents mixing in a furnace chamber. We assume that the mixing pattern we have in a furnace is closer to the first model than it is to the second one, since 0 <G1/G2< 1, and we will assume that the throw distance h of the jet being drifted is equal to the length S0 of the ―free‖ jet’s initial section. The ejection ability of the jet being drifted then remains the same as that of the ―free‖ jet, and the length of the initial section can be determined using the well-known empirical formula of G.N. Amphibrachic [6] ：S0= 0.67r0/a, (2)where a is the jet structure factor and r0 is the nozzle radius.At a = 0.07, the length of the round jet’s initial section is equal to 10 r0 and the radius the jet has at the transition section (at the end of the initial section) is equal to 3.3 r0. The mass flow rate in the jet is doubled in this case. The corresponding minimum furnace cross-sectional area Ff for a round once through burner with the outlet cross-sectional area Fb will then be equal to and the ratio Ff/Fb≈20. This value is close to the actual values found in furnaces equipped with once through burners. In furnaces equipped with swirl burners, a= 0.14 and Ff/Fb≈10. In both cases, the interval between the burners is equal to the jet diameter in the transition section d tr , which differs little from the value that has been established in practice and recommended in [7].The method traditionally used to control the furnace process in large boilers consists of equipping them with a large number of burners arranged in several tiers. Obviously, if the distance between the tiers is relatively small, operations on disconnecting or connecting them affect the entire process only slightly. A furnace design employing large flat-flame burners equipped with means for controlling the flame core position using the aerodynamic principle is a step forward. Additional possibilities for controlling the process in TPE-214 and TPE-215 boilers with a steam output of 670 t/h were obtained through the use of flat-flame burners arranged in two tiers with a large distance between the tiers; this made it possible not only to raise or lower the flame, but also to concentrate or disperse the release of heat in it [1]. A verytangible effect was obtained from installing multicell (operating on coal andopen-hearth, coke, and natural gases) flat-flame burners in the boilers of cogeneration stations at metallurgical plants in Ukraine and Russia.Unfortunately, we have to state that, even at present, those in charge of selecting the type, quantity, and layout of burners in a furnace sometimes adopt technical solutions that are far from being optimal. This problem should therefore be considered in more detail.If we increase the number of burners nb in a furnace while retaining their total cross-sectional area (ΣFb=idem) and the total flow rate of air through them, their equivalent diameters deq will become smaller, as will the jet momentums GB, resulting in a corresponding decrease in the jet throw distance Hb and the mass they eject. The space with high velocity gradients also becomes smaller, resulting in poorer mixing in the furnace as a whole. This factor becomes especially important when the emissions of Box and CO are suppressed right inside the furnace using staged combustion (at αb < 1) under the conditions of a Fortinbras nonuniform distribution of fuel among the burners.In [1], a quantitative relationship was established between the parameters characterizing the quality with which once through jets mix with one another as they flow into a limited space with the geometrical parameter of concentration = with nb = idem and GB = idem. By decreasing this parameter we improve the mass transfer in the furnace; however, this entails an increase in the flow velocity and the expenditure of energy (pressure drop) in the burners with the same Fb. At the same time, we know from experience and calculations that good mixing in a furnace can be obtained without increasing the head loss if we resort to large long-range jets. This allows a much less stringent requirement to be placed on the degree of uniformity with which fuel must be distributed among the burners. Moreover, fuel may in this case be fed to the furnace location where it is required from process control considerations.For illustration purposes, we will estimate the effect the number of burners has on the mixing in a furnace at = = idem. schematically shows the plan views of two furnace chambers differing in the number of once through round nozzles (two and four) placed in a tier (on one side of the furnace). The furnaces have the same totaloutlet cross-sectional areas of the nozzles (ΣF b) and the same jet velocities related to these areas (wb). The well-known swirl furnace of the TsKTI has a design close to the furnace arrangement under consideration. According to the data of [1], the air fraction βair that characterizes the mixing and enters through once through burners into the furnace volume beneath them can be estimated using the formula βair = 1 – (3) which has been verified in the range = 0.03–0.06 for a furnace chamber equipped with two frontal once through burners. Obviously, if we increase the number of burners by a factor of 2, their equivalent diameter, the length of the initial section of jets S0 and the area they ―serve‖ will reduce by a factor of Then, for example, at = 0.05, the fraction βair will decrease from 0.75 to 0.65. Thus, Eq. (3) may be written in the following form for approximately assessing the effect of once through burners on the quality of mixing in a f urnace:βair = 1 – 3.5f nb ' ,where is the number of burners (or air nozzles) on one wall when they are arranged in one tier both in onesided and opposite manners.The number of burners may be tentatively related to the furnace depth af (at the same = idem) using the expression (5)It should be noted that the axes of two large opposite air nozzles ( = 1)—an arrangement implemented in an inverted furnace—had to be inclined downward by more than 50° [8].One well-known example of a furnace device in which once through jets are used to create a large vortex covering a considerable part of its volume is a furnace with tangentially arranged burners. Such furnaces have received especially wide usein combination with pulverizing fans. However, burners with channels having a small equivalent diameter are frequently used for firing low-calorific brown coals with high content of moisture. As a result, the jets of air-dust mixture and secondary air that go out from their channels at different velocities(w2/w1 = 2–3) become turbulence and lose the ability to be thrown a long distance; as a consequence, the flame comes closer to the water walls and the latter are contaminated with slag. One method by which the tangential combustion scheme can be improved consists of organizing the so-called concentric admission of large jets of air-dust mixture and secondary air with the fuel and air nozzles spaced apart from one another over the furnace perimeter,accompanied by intensifying the ventilation of mills [9, 10]. Despite the fact that the temperature level in the flame decreases, the combustion does not become less stable because the fuel mixes with air in a stepwise manner in a horizontal plane.V ortex furnace designs with large cortices the rotation axes of which are arranged transversely with respect to the main direction of gas flow have wide possibilities in terms of controlling the furnace process. In [1], four furnace schemes with a controllable flame are described, which employ the principle of large jets colliding with one another; three of these schemes have been implemented. A boiler with a steam capacity of 230 t/h has been retrofitted in accordance with one of these schemes (with an inverted furnace) . Tests of this boiler, during which air-dust mixture was fed at a velocity of 25–30 m/s from the boiler front using a high concentration dust system, showed that the temperature of gases at the outlet from the furnace had a fairly uniform distribution both along the furnace width and depth . A simple method of shifting the flame core over the furnace height was checked during the operation of this boiler, which consisted of changing the ratio of air flow rates through the front and rear nozzles;this allowed a shift to be made from running the furnace in adry-bottom mode to a slag-tap mode and vice Versace. A bottom-blast furnace scheme has received rather wide use in boilers equipped with different types of burners and mills. Boilers with steam capacities ranging from 50 to 1650 t/h with such an aerodynamic scheme of furnaces manufactured by ZiO and Bergomask have been installed at a few power stations in Russia and abroad . We have to point out that, so far as the efficiency of furnace process control is concerned, a combination of the following two aerodynamic schemes is of special interest: the inverted scheme and the bottom-blast one. The flow pattern and a calculation analysis of the furnace process in such a furnace during the combustion of lean coal are presented in [13].Below, two other techniques for controlling the furnace process are considered. Boilers with flame–stoker furnaces have gained acceptance in industrial power engineering, devices that can be regarded to certain degree as controllable ones owing to the presence of two zones in them . Very different kinds of fuel can be jointly combusted in these furnaces rather easily. An example of calculating such a furnace device is given in [2]. As for boilers of larger capacity, work on developingcontrollable two-zone furnaces is progressing slowly . The development of a furnace device using the so-called VIR technology (the transliterated abbreviation of the Russian introduction, innovation, and retrofitting) can be considered as holding promise in this respect. Those involved in bringing this technology to the state of industry standard encountered difficulties of an operational nature (the control of the process also presented certain difficulties). In our opinion, these difficulties are due to the fact that the distribution of fuel over fractions can be optimized to a limited extent and that the flow in the main furnace volume has a rather sluggish aerodynamic structure. It should also be noted that the device for firing the coarsest fractions of solid fuel in a spouting bed under the cold funnel is far from being technically perfect.Centrifugal dust concentrators have received acceptance for firing high-reactive coals in schemes employing pulverizing fans to optimize the distribution of fuel as to its flow rate and fractions. The design of one such device is schematically shown in [9]. Figure shows a distribution of fuel flow rates among four tiers of burners that is close to the optimum one. This distribution can be controlled if we furnish dust concentrators with a device with variable blades, a solution that has an adequate effect on the furnace process.。
锅炉系统毕业设计论文中英文资料对照外文翻译文献
中英文资料对照外文翻译文献锅炉系统1 冷凝器1.1 简介欧堡生产的冷凝器是用直管和一个外部密封浮头组成的管壳式冷凝器。
这种冷凝器主要用作废气锅炉，蒸汽加热或洗舱海水加热器的转储冷凝器/冷却器排水。
并取得权威船级社批准。
温度计，排水阀，空气阀，压力表的安装设计为½“BSP内螺纹安装。
这些组件可能是指定的。
而蒸汽或水的控制设备是可选的。
1.2 安装空间要求安装时必须有足够的空间供作清洗，检查或更换管的插入与撤出。
冷凝器必须安置在水平并稳定的表面。
1.3 存储如果冷凝器在安装前要闲置一段时间，应存放在干燥的储藏室里。
如果储藏室潮湿，冷凝器必须放在装有硅胶的包装袋子里。
为了避免破坏，建议冷凝器放在原包装中。
冷凝器已经在交付前做过液压试验。
试验中所用测试媒质含有一定的数额抗腐蚀保护物质。
当冷凝器需闲置的时间较长，建议使用指定产品作为防腐蚀物质1.4 安装冷凝器设计为垂直或水平安装。
在水平安装的情况下，蒸汽喷嘴必须朝上，而冷凝水出口喷嘴朝下。
如果是垂直安装冷凝器，蒸汽入口和海水出口端必须朝上。
排水和空气排放阀必须安装在冷凝器在最低和最高点的中间线的位置。
任何选择性的控制设备必须根据具体指示安装。
步骤A：将冷凝器安装在水平平面上。
步骤B：钻基础固定螺栓孔。
步骤C：将螺栓放入孔中并拧紧。
连接冷凝器步骤D：移除所有的塞子和盲板，然后再连接冷凝器。
步骤E：在连接中确保没有杂质进入。
步骤F：管道连接起来，确保从管道和冷凝器之间没有强制力的产生。
1.5 调试启动前要确保所有连接都牢固地拧紧是很重要的。
同样重要的是，冷凝器和连接管道空气要彻底排出。
步骤A：如果装有安全阀，必须加以调整到最大设计压力或较低。
步骤B：法兰螺栓要拧紧。
拧紧法兰螺栓时始终使用扭矩扳手。
步骤C：运行一小时，停止冷凝器，并重新拧紧所有螺栓。
步骤D：启动阶段，冷凝器的两边都要排出空气，必须认真仔细的检查回路的泄漏。
1.6 性能冷凝器性能须附和传热计算表规定的要求。
锅炉毕设文献翻译
自然循环热水锅炉水动力回路分析法摘要：水动力计算都依据《热水锅炉水动力计算方法》,不足的是这种方法不能准确确定每根单管的工质流量，且不能准确确定工作点。
为了避免其不确定性，研究得出了一种数值水动力计算方法即水动力回路分析法，简称回路分析法。
该方法考虑了各种因素对锅炉本体每根管内工质流量的影响，在其热负荷、结构参数和工质流动阻力系数给定的条件下，可以准确计算出每根单管内的工质流量。
在相同的参数条件下，分别用标准法和回路分析法对某单一循环回路的水动力特性进行计算，计算结果验证了水动力回路分析法的正确性。
然后分别用标准法和回路分析法对一台自然循环热水锅炉的水动力特性进行计算，结果表明水动力回路分析法更准确并可接受。
关键词：热水锅炉；水动力；回路分析法引言：由于自然循环热水锅炉的大容量和对于断电保护、给水质量以及运行水平的低要求，它已经在中国广泛应用[1]。
然而，在上升管和下降管中工质的密度差过小可能会导致自然循环有效压力较低，如果结构不合理，将会产生爆管。
因此，在自然循环热水锅炉设计中，如何确定流动工质的安全速度和避免爆管导致受热面过冷沸腾是非常重要的。
在中国早期，有很多研究者致力于关于自然循环热水锅炉水动力计算的研究，一些人提出了对于几个简单循环回路和某些复杂循环回路的水动力计算方法，但是大多数方法只适用于简单回路。
西安交通大学的朱教授提出了一种应用计算机流体力学分析的方法，他将流动工质的特点和使用一种两端参考作为主动解决方法的直流循环原则做了比较。
这种方法的优势在于解决过程的方便性，但是对于复杂循环的解决过程非常复杂[2]。
自从上世纪七十年代，对于管流分布热力学模型的研究显著增多[3-8]。
目前，水动力计算方法使用“热水锅炉水动力计算法”[9](以下简称一般方法)，它提供了保证循环安全的一般方法。
该方法采用图解的方式确定介质的工作点，这是非常准确和高效的。
在解决整个问题时用到一些假设。
本文的目的是提供一种新的水动力数值计算方法，简称水动力回路分析法，即回路分析法。
工业锅炉节能毕业论文中英文资料外文翻译文献
工业锅炉节能中英文资料外文翻译文献专业英文资料Boiler energy savingIndustrial boiler energy saving technology related to many, what is the most important increase industrial furnace thermal utilization ratio of pot namely, increasing the thermal efficiency of the industrial boiler. This section from burning, transportation line maintenance, new technology and new equipment and the application of the industrial boiler auxiliary equipment of energy saving, pot boiler water processing, etc and the industrial boiler room way of energy saving is discussed in this paper.1. The furnace of industrial boiler furnace arch arch is very important. The role is to make arch furnace chamber of the mixture of gases and radiation and hot gas organization flow, to make the fuel and ignition and combustion when. Sua and at present industrial boiler with the actual YongQiLiang rated load are often not with horse, the use of coal changes greatly, and often have large design coal poor vision, so in actual use, often to furnace necessary improvement in arch coal need to be comfortable.For transformation of the former furnace arch situation, the existing problem is: for the use of coal and coal than design poor miscellaneous, boiler flue gas temperature appear the chamber exports low (about 700℃), more than 200 ℃ design low. The new coal fire late, often appear fire bed broken fire, fire from about 0.6 ~ coal disc 1 cm, furnace combustion is not strong, ash high carbon content. According to the problems furnace arch structure, from improving the ignition of fuel conditions and raise the temperature of boiler furnace to reform.After improvement furnace arch, in actual shipped in from the observed, the transformation effect is good, people away from coal furnace fuel after disc 0.3 MRP on fire, fire bed combustion intense, flame full of degree good, strong rotation. Due to the lower arch before, after extended arch, the arch of the throat and mouth shape between into space from the original 2 cm or so down to 1 cm. To strengthen the disturbance of the air mixed, to form the airflow, strengthen the furnace combustion, improve the efficiency of the district and the whole arch before furnace temperature, make its reach to 1400℃ above, improved the ignition of fuel conditions. Coal in the ignition, of furnace temperature rise, make the carbon content and ash significantly less. The flue gas mixture and strengthen the hydrocyclone separation of flue gas carbon particles needed to fall in the fire bed and new fuel layer further burns out.2. The reasonable air supply and regulationIn the chain furnace, the furnace, the furnace of reciprocating vibration, according to the different characteristics of the combustion process, reasonable air supply, to promote the furnace combustion is very important. As in the chain furnace, along with fuel keep movement, which in turn happen on fire, burning, and burn the stage. Burning along the length direction is the stoker stages, zoning, so along the length direction along the air quantity is also different. The preheating zone along the head and tail burn stage, air requirements small; The burning along the middle stage, air requirements. According to this13characteristic, must use block supply air, to meet the needs of the burning. The current domestic production of the boiler although all are to consider this one characteristic, with the wind in subsection room, and equipped with air inlet adjustment. But according to the survey.3.The secondary airSecond wind to strengthen the air combustion is very effective. Second wind have the following function:(1) strengthen the furnace of air disturbance and mixed, make the furnace of oxygen and flammable gas mixture evenly, make chemical don't fully burning loss and the chamber excess air coefficient reducing. (2) secondary air in furnace flue gas vortex formed, on the one hand, extended the suspension fine coal grain in the chamber of a stroke, increase the fine particles suspended furnace in the residence time of, make it have a full time to burn, make not complete combustion heat loss; Another result of air separation of spiral effect, make coal dust grain and the grain re-blows rejection within, and reduce the small fly ash escape from the quantity, the mechanical incomplete combustion heat loss.英译汉14锅炉的节能工业锅炉的节能技术涉及多方面 , 最主要是提高工业锅炉的热能利用率 , 即提高工业锅炉的热效率。
燃煤锅炉 外文翻译 外文文献 英文文献 中英翻译
燃煤锅炉外文翻译外文文献英文文献中英翻译外文出处: A. A. Shatil’, N. S. K. A. A. S., & V. Kudryavtsev, A. (2008). Controllingthe furnace process in coal-fired boilers. Thermal Engineering, 55, 1, 72-77.Controlling the Furnace Process in Coal-Fired BoilersThe unstable trends that exist in the market of fuel supplied to thermal power plants and the situations in which the parameters of their operation need to be changed (or preserved), as well as the tendency toward the economical and environmental requirements placed on them becoming more stringent, are factors that make the problem ofcontrolling the combustion and heat transfer processes in furnace devices very urgent. The solution to this problem has two aspects. The first involves development of a combustion technology and,accordingly, the design of a furnace device when new installations are designed. The second involves modernization of already existing equipment. In both cases,the technical solutions being adopted must be properly substantiated with the use of both experimental and calculationstudies.The experience Central Boiler-Turbine Institute Research and Production Association (TsKTI) and ZiO specialists gained from operation of boilers and experimental investigations they carried out on models allowed them to propose several new designs of multifuel andmaneuverable—in other words, controllable—furnace devices that had been put in operationat power stations for several years. Along with this, an approximate zero-one-dimensional, zonewise calculation model of the furnace process in boilers had been developed at the TsKTI, which allowed TsKTI specialists to carry out engineering calculations of the main parameters of this process and calculate studies of furnaces employing different technologies of firing and combustion modes .Naturally, furnace process adjustment methods like changing the air excess factor, stack gas recirculation fraction, and distribution offuel and air among the tiers of burners, as well as other operations written in the boiler operational chart, are used during boiler operation.However, the effect they have on the process is limited in nature. On the other hand, control of the furnace process in a boiler implies the possibility of making substantial changes in the conditions under which the combustion and heat transfer proceed in order to considerably expand the range of loads, minimize heat losses, reduce the extent to which the furnace is contaminated with slag, decrease the emissions of harmful substances, and shift to another fuel. Such a control can be obtained by making use of the following three main factors:(i) the flows of oxidizer and gases being set to move in the flamein a desired aerodynamic manner;1(ii) the method used to supply fuel into the furnace and the placeat which it is admitted thereto;(iii) the fineness to which the fuel is milled.The latter case implies that a flame-bed method is used along withthe flame method for combusting fuel.The bed combustion method can be implemented in three design versions: mechanical grates with a dense bed, fluidized-bed furnaces, and spouted-bed furnaces.As will be shown below, the first factor can be made to work bysetting up bulky vortices transferring large volumes of air and combustion products across and along the furnace device. If fuel isfired in a flame, the optimal method of feeding it to the furnace is to admit it to the zones near the centers of circulating vortices, a situation especially typical of highly intense furnace devices. The combustion process in the se zones features a low air excess factor (α< 1) and a long local time for which the components dwell in them, factors that help make the combustion process more stable and reduce theemission of nitrogen oxides .Also important for the control of a furnace process when solid fuelis fired is the fineness to which it is milled; if we wish to minimize incomplete combustion, the degree to which fuel is milled should be harmonized with the location at which the fuel is admitted into the furnace and the method for supplying it there, for the occurrence of unburned carbon may be due not only to incomplete combustion of large-size fuel fractions, but also due to fine ones failing to ignite (especially when the content of volatiles Vdaf < 20%).Owing to the possibility of pictorially demonstrating the motion of flows, furnace aerodynamics is attracting a great deal of attention of researchers and designers who develop and improve furnace devices. At the same time, furnace aerodynamics lies at the heart of mixing (mass transfer), a process the quantitative parameters of which can be estimated only indirectly or by special measurements. The quality with which components are mixed in the furnace chamber proper depends on the number, layout, and momenta of the jets flowing out from individual burners or nozzles, as well as on their interaction with the flow of flue gases, with one another, or with the wall.It was suggested that the gas-jet throw distance be used as a parameter determining the degree to which fuel is mixed with air in the gas burner channel. Such an approach to estimating how efficient the mixing is may to a certain degree be used in analyzing the furnace as a mixing apparatus. Obviously, the greater the jet length (and its momentum), the longer the time during which the velocity gradient it creates in the furnace will persist there, a parameter that determines how completely the flows are mixed in it. Note that the higher the degree to which a jet is turbulized at the outlet from a nozzle or burner, the shorter the distance which it covers, and, accordingly, the less completely the components are mixed in2the furnace volume. Once through burners have advantages over swirl ones in this respect.It is was proposed that the extent to which once through jets are mixed as they penetrate with velocity w2 and density ρ2 into a transverse (drift) flow moving with velocity w1 and having density ρ1 be correlated with the relative jet throw distance in the following way Where ks is a proportionality factor tha t depends on the ―pitch‖ between the jet axes (ks=1.5–1.8).The results of an experimental investigation inwhich the mixing of gas with air in a burner and then in a furnace was studied using the incompleteness of mixing as a parameter are reported in 5.A round once through jet is intensively mixed with the surrounding medium in a furnace within its initial section, where the flow velocity at the jet axis is still equal to the velocity w2 at the nozzle orifice of radius r0.The velocity of the jet blown into the furnace drops very rapidly beyond the confines of the initial section, and the axis it has in the case of wall-mounted burners bends toward the outlet from the furnace.One may consider that there are three theoretical models for analyzing the mixing of jets with flowrate G2 that enter into a stream with flowrate G1. The first model is for the case when jets flow into a ―free‖ space (G1= 0),the second model is for the case when jets flowinto a transverse (drift) current with flowrate G1G2，and the third model is for the case ,when jets flow into a drift stream with flowrate G1<G2. The second model represents mixing in the channel of a gas burner, and the third model represents mixing in a furnace chamber. We assume that the mixing pattern we have in a furnace is closer to the first model than it is to the second one, since 0 <G1/G2< 1, and we will assume that the throw distance h of the jet being drifted is equal to the length S0 of the―free‖ jet’s initial section. The ejection ability of the jet being drifted then remains the same as that of the ―free‖ jet, and the length of the initialsection can be determined using the well-known empirical formula of G.N. Abramovich [6] :S0= 0.67r0/a, (2)where a is the jet structure factor and r0 is the nozzle radius.At a = 0.07, the length of the round jet’s initial section is equal to 10 r0 and the radius the jet has at the transition section (at the end of the initial section) is equal to 3.3 r0. The mass flowrate in the jet is doubled in this case. The corresponding minimum furnace cross-sectional area Ff for a round once through burner with the outlet cross-sectional area Fb will then be equal to and the ratio Ff/Fb?20. This value is close to the actual values found in furnacesequipped with once through burners. In furnaces equipped with swirl burners, a= 0.14 and Ff/Fb?10. In both cases, the interval between theburners is equal to the jet diameter in the transition section d tr , which differs little from the value that has been established inpractice and recommended in [7].3The method traditionally used to control the furnace process inlarge boilers consists of equipping them with a large number of burners arranged in several tiers. Obviously, if the distance between the tiers is relatively small, operations on disconnecting or connecting themaffect the entire process only slightly. A furnace design employinglarge flat-flame burners equipped with means for controlling the flame core position using the aerodynamic principle is a step forward. Additional possibilities for controlling the process in TPE-214 and TPE-215 boilers with a steam output of 670 t/h were obtained through the use of flat-flame burners arranged in two tiers with a large distance between the tiers; this made it possible not only to raise or lower the flame, but also to concentrate or disperse the release of heat in it [1].A very tangible effect was obtained from installing multifuel (operating on coal and open-hearth, coke, and natural gases) flat-flame burners in the boilers of cogeneration stations at metallurgical plants in Ukraine and Russia.Unfortunately, we have to state that, even at present, those in charge of selecting the type, quantity, and layout of burners in a furnace sometimes adopt technical solutions that are far from being optimal. This problem should therefore be considered in more detail.If we increase the number of burners nb in a furnace while retaining their total cross-sectional area (ΣFb=idem) and the total flowrate ofair through them, their equivalent diameters deq will become smaller, as willthe jet momentums Gbwb, resulting in a corresponding decrease in the jet throw distance hb and the mass they eject. The space with high velocity gradients also becomes smaller, resulting in poorer mixing in the furnace as a whole. This factor becomes especially important whenthe emissions of NOx and CO are suppressed right inside the furnaceusing staged combustion (at αb < 1) under the conditionsof a fortiori nonuniform distribution of fuel among the burners.In [1], a quantitative relationship was established between the parameters characterizing the quality with which once through jets mix with one another as they flow into a limited space with the geometrical parameter of concentration = with nb = idem and Gb = idem. By decreasing this parameter we improve the mass transfer in the furnace; however,this entails an increase in the flow velocity and the expenditure of energy (pressure drop) in the burners with the same Fb. At the same time, we know from experience and calculations that good mixing in a furnace can be obtained without increasing the head loss if we resort to large long-range jets. This allows a much less stringent requirement to be placed on the degree of uniformity with which fuel must be distributed among the burners. Moreover, fuel may in this case be fed to the furnace location where it is required from process control considerations.For illustration purposes, we will estimate the effect the number of burners has on the mixing in a furnace at = = idem. schematically shows the plan views of two furnace chambers4differing in the number of once through round nozzles (two and four) placed in a tier (on one side of the furnace). The furnaces have the same total outlet cross-sectional areas of the nozzles (ΣFb) and the same jet velocities related to these areas (wb). The well-known swirl furnace of the TsKTI has a design close to the furnace arrangement under consideration. According to the data of [1], the air fraction βair that characterizes the mixing and entersthrough once through burners into the furnace volume beneath themcan be estimated using the formula βair = 1 – (3) which has been verified in the range = 0.03–0.06 for a furnacechamber equipped with two frontal once through burners. Obviously,if we increase the number of burners by a factor of 2, their equivalent diameter, the length of the initial section of jets S0 and the area they ―serve‖ will reduce by a factor of Then, for example, at = 0.05, the raction βair will decreas e from 0.75 to 0.65. Thus, Eq. (3) may be written in the following fform for approximately assessing the effect of once through burners on the quality of mixing in a furnace:βair = 1 – 3.5f nb ' ,where is the number of burners (or air nozzles) on one wall when they are arranged in one tier both in onesided and opposite manners.The number of burners may be tentatively related to the furnacedepth af (at the same = idem) using the expression (5)It should be noted that the axes of two large opposite air nozzles ( = 1)—an arrangementimplemented in an inverted furnace—had to be inclined downward by more than 50? [8].One well-known example of a furnace device in which once throughjets are used to create a large vortex covering a considerable part of its volume is a furnace with tangentially arranged burners. Such furnaces have received especially wide use in combination with pulverizing fans. However, burners with channels having a small equivalent diameter are frequently used for firing low-calorific brown coals with high content of moisture. As a result, the jets of air-dust mixture and secondary air that go out from their channels at different velocities(w2/w1 = 2–3) become turbulized and lose the ability to be thrown a long distance; as a consequence, the flame comes closer to the waterwalls and the latter are contaminated with slag. One method by which the tangential combustion scheme can be improved consists of organizing the so-called concentric admission of large jets of air-dust mixture and secondary air with the fuel and air nozzles spaced apart from one another over the furnace perimeter, accompanied by intensifying the ventilation of mills [9, 10]. Despite the fact that thetemperature level in the flame decreases, the combustion does not become less stable because the fuel mixes with air in a stepwise manner in a horizontal plane.Vortex furnace designs with large vortices the rotation axes ofwhich are arranged transversely with respect to the main direction of gas flow have wide possibilities in terms of5controlling the furnace process. In [1], four furnace schemes with a controllable flame are described, which employ the principle of large jets colliding with one another; three of these schemes have been implemented. A boiler with a steam capacity of 230 t/h has been retrofitted in accordance with one of these schemes (with an inverted furnace) . Tests of this boiler, during which air-dust mixture was fed at a velocity of 25–30 m/s from the boiler frontusing a highconcentration dust system, showed that the temperatureof gases at the outlet from the furnace had a fairly uniformdistribution both along the furnace width and depth . A simple method of shifting the flame core over the furnace height was checked during the operation of this boiler, which consisted of changing the ratio of air flowrates through the front and rear nozzles;this allowed a shift to be made from running the furnace in a dry-bottom mode to a slag-tap mode and vice versa. A bottom-blast furnace scheme has received rather wide use in boilers equipped with different types of burners and mills. Boilers with steam capacities ranging from 50 to 1650 t/h with such anaerodynamic scheme of furnaces manufactured by ZiO and Sibenergomash have been installed at a few power stations in Russia and abroad . We have to point out that, so far as the efficiency of furnace process control is concerned, a combination of the following two aerodynamic schemes is of special interest: the inverted scheme and the bottom-blast one. The flow pattern and a calculation analysis of the furnace process in such a furnace during the combustion of lean coal are presented in [13].Below, two other techniques for controlling the furnace process are considered. Boilers with flame–stoker furnaces have gained acceptancein industrial power engineering, devices that can be regarded to certain degree as controllable ones owing to the presence of two zones in them . Very different kinds of fuel can be jointly combusted in these furnaces rather easily. An example of calculating such a furnace device is given in [2]. As for boilers of larger capacity, work on developing controllable two-zone furnaces is progressing slowly . The development of a furnace device using the so-called VIR technology (thetransliterated abbreviation of the Russian introduction, innovation, and retrofitting) can be considered as holding promise in this respect. Those involved in bringing this technology to the state of industry standard encountered difficulties of an operational nature (the control of the process also presented certain difficulties). In our opinion, these difficulties are due to the fact that the distribution of fuel over fractions can be optimized to a limited extent and that the flow inthe main furnace volume has a rather sluggish aerodynamic structure. It should also be noted that the device for firing the coarsest fractions of solid fuel in a spouting bed under the cold funnel is far from being technically perfect.Centrifugal dust concentrators have received acceptance for firing high-reactive coals in schemes employing pulverizing fans to optimize the distribution of fuel as to its flowrate and6fractions. The design of one such device is schematically shown in [9]. Figure shows a distribution of fuel flowrates among four tiers of burners that is close to the optimum one. This distribution can be controlled if we furnish dust concentrators with a device with variable blades, a solution that has an adequate effect on the furnace process.7燃煤锅炉的燃烧进程控制存在于火电厂的市场的燃料供应，某些操作参数需要改变(或保留)的情况下，以及经济和环境方面倾向的要求使他们变得更加严格的不稳定趋势是导致使控制燃烧与传热过程炉设备非常紧迫的主要因素。
锅炉烟气除尘系统设计 环境工程外文资料翻译
毕业论文外文资料翻译题目某燃煤采暖锅炉烟气除尘系统设计学院资源与环境学院专业环境工程班级学生学号指导教师张玲二〇一二年四月二十日济南大学- 1 -济南大学- 2 -济南大学- 3 -济南大学- 4 -- 5 -济南大学- 6 -济南大学- 7 -济南大学- 8 -济南大学- 9 -济南大学- 10 -济南大学Chemical Engineering and Processing 40 (2001) 245–254.新的旋风式分离器的计算方法与纷飞挡板和底部清洁的天然气 - 第二部分：实验验证Tomasz Chmielniak a,*, Andrzej Bryczkowskia,b煤化工Zamkowa1，41-803 Zabrze，波兰研究所化学和工艺设备，波兰西里西亚技术Uni6ersity，M. Strzody7，44-100格利维采1999年11月23日收到，在2000年6月6日修订后的形式;2000年6月6日采纳摘要派生模型预测研究所收集的效率和压力下降，煤化工（IChPW）与一个旋转挡板的旋风式分离器的设计测试和实验验证的结果。
试点工作包含测试气体流速和分离效率和压降转子转速的影响。
密封流除尘效率的影响进行了测试。
一个旋转挡板分隔的特点是高效率和低的压降。
挡板高度的扩展可以得到较高的除尘效率和更低的压降。
计算方法与实验结果显示了良好的实验预期。
©2001 Elsevier Science B.V.版权所有。
关键词粉尘分离；气旋；旋流挡板；收集效率；压降1介绍由于旋转分离元素的粉尘分离器的优势，致使过去几年对这类设备[1-5]建设的深入研究和理论描述。
它还涉及建设一个在化工、煤炭加工（IChPW）研究所开发的新型旋风式分离器旋流挡板[6]。
在这个问题上[6]前文推导的理论模型来预测一个旋转挡板分离器的收集效率和压力下降。
在本文章中，发达国家的计算方法的实验和实证检验的结果报告。
2 旋风式分离器的计算方法的理论与旋流挡板2.1收集效率级效率的模型来预测的基础上的Laith和利希特气旋的计算方法[7]。
锅炉设计外文翻译---燃煤锅炉的个案事故研究
附录A英文原文A. Kusiak and A. Burns, Mining Temporal Data: A Coal-Fired Boiler CaseStudy, Proceedings of the 9th International Conference, KES 2005, Melbourne,Australia, September 14-16, 2005, in R. Khosla, R.J. Howlett, L.C. Jain (Eds),Knowledge-Based Intelligent Information and Engineering Systems: V ol. III,LNAI 3683, Springer, Heidelberg, Germany, 2005, pp. 953-958.Mining Temporal Data: A Coal-Fired Boiler CaseStudyAndrew Kusiak and Alex BurnsIntelligent Systems Laboratory, Industrial Engineering3131 SeamansCenter, The University of IowaIowa City, IA52242 – 1527, USAandrew-kusiak@AbstractThis paper presents an approach to control pluggage of a coal-fired boiler.The proposed approach involves statistics, data partitioning, parameter reduction,and data mining. The proposed approach was tested on a 750 MW commercialcoal-fired boiler affected with a fouling problem that leads to boiler pluggagethat causes unscheduled shutdowns. The rare-event detection approachpresented in the paper identified several critical time-based data segments thatare indicative of the ash pluggage.1 IntroductionThe ability to predict and avoid rare events in time series data is achallenge that could be addressed by data mining approaches. Difficulties arise from the fact that often a significant volume of data describes normal conditions and only a small amount of data may be available for rare events. This problem is further exacerbated by the fact that traditional data mining does not account for the time dependency of the temporal data. The approach presented in this paper overcomes these concerns by defining timewindows.The approach presented in this paper is based on the two main concepts. The first is that the decision-tree data-mining algorithm captures the subtle parameter relationships that cause the rare event to occur [1]. The second concept is that partitioning the data using time windows provides the ability to capture and describe sequences of events that may cause the rare failure.2 Event Detection ProcedureIn the case study discussed in the next section rare events can be detected by applying the five step procedure. These five steps include:Step 1: Parameter CategorizationThe parameter list is divided into two categories, response parameters and impact parameters. Response parameters are those that change values due to a rare event or a failure, e.g., an air leak in a pressurized chamber. Impact parameters are defined as parameters that are either directly or indirectly controllable and may cause the rare event. These are the parameters that are of greatest interest for the determination of rare events.Step 2: Time SegmentationTime segmentation deals with partitioning and labeling the data into time windows (TWs). A time widow is defined as a set of observations in chronological order that describe a specified amount of continuous observations. This step allows the data mining algorithms to account for the temporal nature of the data. The most effective method to segment the data is bydetermining/estimating the approximate date of failure and set that as the last observation of the final time window.Step 3: Statistical and Visual AnalysisThis step involves statistical analysis of the data in each time period that was designated in the previous step. Process shifts, changes in variation, and mean shifts in parameters are helpful in indicating that the appropriate time windows and parameters were selected.Step 4: Knowledge ExtractionData mining algorithms discover relationships among parameters and an outcome in the form of IF … THEN rules and other constructs (e.g., decision tables) [1], [5]. Data mining is natural extension of more traditional tools such as neural networks, multivariable algorithms, or traditional statistics. In the detection of rare events, the decision-tree and rule-induction algorithms are explored for two significant reasons. First, the algorithms generate explicit knowledge in the form understandable by a user. The user is able to understand the extracted knowledge, assess its usefulness, and learn new and interesting concepts. Secondly, the data mining algorithms have been shown to produce highly accurate knowledge in many domains.Step 5: Analysis of Knowledge and ValidationThis step deals with validation of the knowledge generated by the data mining algorithm. If a validation data set is available it should be used to validate the accuracy of the rules. If no similar data is available then unused data from the analysis or a 10-fold cross-validation can be utilized [6].3 Power Boiler Case StudyThe approach proposed in this research was applied to power plant data. Data mining algorithms are well suited for electric power applications that produce hundreds of data points at any time instance.This case study deals with an ash fouling condition that causes boilershutdowns several times a year on a commercial 750 MW tangentially-fired coal boiler. The ash fouling causes a build up of material and pluggage in the reheater section of the boiler. Once the build up becomes substantial the boiler performance is negatively affected. This leads to the derating and the eventual shutdown of the boiler. The cleaning of the boiler during the shutdown requires 1 to 3 days. This problem is made more difficult by the fact there is no method to determine the level of ash build up without shutting down the boiler to physically inspect the area. Furthermore, in analysis all parameters were within specifications, so there was no obvious single parameter that is causing the pluggage. To investigate the problem considered in this paper, data was collected on 173 different boiler parameters. This included flows, pressures, temperatures, controls, demands, and so on. The data was collected in one-minute intervals over the course of three months. The data collection began directly following a shutdown where the reheater section of the boiler had no pluggage. The collection period ended approximately three months later when the boiler had to be shutdown for pluggage removal. This data set contained over 168,000 observations.The list of 173 parameters, which included both response and impact parameters, was analyzed. The list was reduced to include twenty-six impact parameters. This parameter categorization and reduction was accomplished with the assistance of domain experts as well as statistical analysis such as correlation and multivariate analysis.The initial step for time segmenting the data was to determine an approximate date for the failure event. In this application the failure event was defined by the date when the boiler was derated due to the pluggage. The cause of the shutdown was confirmed through visual inspection of the affected region. This date was then set to be the last day of the final time window (TW6).The windows were set to be approximately one week long. A week was chosen for several reasons. First, the boiler was inspected approximately onemonth prior to its derating. During the inspection the reheater section of the boiler was completely free of ash. This information provided the knowledge that the pluggage required less the one month to manifest itself to the point of shutdown. It was hypothesized that the pluggage requires several days to build up. Based on this information one week was deemed to be an adequate time window. One week also provided a sufficient number of observations (over 10,000 per window) for the data mining algorithms.Using the derate date and a one-week-long time window, the data was divided into six time windows shown in Figure 1. Time window 1 (TW1) was included to ensure that there was adequate data to describe normal operating conditions.There appears be a process shift between time windows 3 and 5 in Figures 1. The west tilt demonstrates a mean shift during window three and the hot reheat steam temperature displays a mean shift as well as a large increase in variation starting in time window four and culminating in window five. The results of this analysis lead to the hypothesis that the events that lead to the eventual pluggage occur between time windows three and five. It also confirms the selection of parameters and window size.The data mining approach was then applied to the data set to predict the predefined time windows (decision parameter). The algorithm produced a set of rules that described the parameter relationships in each time window.The knowledge extracted by the algorithm had an overall 10-fold classification accuracy of 99.7%. The confusion matrix (absolute classification accuracy matrix) is shown in Figure 2. The matrix displays the actual values and the values predicted by the rules during the cross-validation process.It can be seen from the data in Figure 2 that there are few predicted values that are off by more than one time window from the actual window. The results provided in the confusion matrix provide a high confidence in the proposed solution approach.Another test data set was extracted from the week following time window 1 and was labeled time window 2 (Test TW2). The last portion of the data (Test TW3) was obtained from the week after the generator was derated and the outcome was labeled time window 6 (TW6). The total test set contained over 30,000 observations.The rules and knowledge that were extracted from the original data set were then tested using the test data set. For purposes of analysis time windows1 – 3 were considered normal and time window 4 – 6 were considered faulty. The resulting confusion matrix is shown in Figure 3.The rules accurately predicted the normal cases, but they were not as effective in predicting the fault cases. This is most likely explained by the fact that the test data labeled, time window 6, was extracted after the boiler had been derated. The derating of the boiler significantly changes the combustion process and was not included in the original data set. In spite of this, the overall classification accuracy of the test data set is greater than 89%. The high cross-validation accuracy indicates that the rules accurately capture the changes in the process that lead to the ash fouling, pluggage, derating, and eventual shutdown of the boiler.4 Future ResearchEvent detection for control advisory systems has also been successfully demonstrated for applications that are dynamic and involve rare and catastrophic events [4]. Finch et al. [2] developed expert diagnostic information system, MIDAS, to alert users to abnormal transient conditions in chemical, refinery, and utility systems [3].The approach presented in this research produced rule sets that can be utilized for the development of a meta-control system. Integrating concepts from expert advisory systems and intelligent power control systems will form the meta-control system architecture for the avoidance of the ash pluggage.5 ConclusionIn this paper a data mining approach to predict failures was proposed and successfully implemented. The research utilized parameter categorization and time segmentation to overcome the limitation of traditional data mining approaches applied to temporal data. The proposed approach produced a knowledge base (rule set) that accurately described the subtle process shifts and parameter relationships that eventually may lead to the detection and avoidance of failures.This approach was applied to a commercial tangentially-fired coal-boiler to detect and avoid an ash fouling pluggage that eventually leads to boiler shutdown. The approach produced a rule set that was over 99.7% accurate. The knowledge base was also validated with a separate test data set that has predicted failures with accuracy of over 89.8%.The discovered knowledge will be used to develop an advance warning system reducing the number of boiler shutdowns. The intelligent warning system will have a significant economic impact. This translates into reduced cost to the consumer and a more efficient power industry.References1. Quinlan, J.R., “Induction of decision trees,” Machine Learning, vol. 1, no. 1, pp. 81-106, 1986.2. Branagan, L. A., and Wasserman, P. D., "Introductory use of probabilistic neural networks for spike detection from an on-line vibration diagnostic system", Intelligent Engineering Systems Through Artificial Neural Networks, vol. 2, pp. 719-724, 1992.3. Finch, F. E., Oyeleye, O. O., and Kramer, M. A., "Robust event-oriented methodology for diagnosis of dynamic process systems", Computers & Chemical Engineering, vol.14, no. 12, pp. 1379-1396, Dec, 1990.4. Pomeroy, B. D., Spang, H. A., and Dausch, M.E., "Event-based architecturefor diagnosis in control advisory systems", Artificial Intelligence in Engineering, vol. 5, no. 4, pp. 174-181, Oct, 1990.5. Pawlak, Z., Rough Sets: Theoretical Aspects of Reasoning About Data, Boston: Kluwer, 1991.6. Stone, M. "Cross-validatory choice and assessment of statistical predictions," Journal of the Royal Statistical Society, vol. 36, pp.111-147, 1974.附录B中文翻译燃煤锅炉的个案事故研究摘要这篇论文讲述了控制燃煤锅炉堵塞的方法。
毕业设计翻译---耐硫变换废热锅炉控制系统
基于模型预测控制利用不确定集方法的鲁棒优化摘要（原文上知网检索-The Robust Optimization Based Model Predictive Control using Box Uncertainty Set）论文考虑了鲁棒优化(RO)在模型预测控制中的应用。
这个优化方法包含了不确定数据，也就意味着当解决方案必须确定时优化问题的数据并不是精确的被知道。
鲁棒优化(RO)已经广泛应用于各种适用场合，在本文中，展现了在模型预测控制(MPC)中的应用。
基于模型预测控制的鲁棒优化(RO based-MPC)被用于废热锅炉控制的仿真模拟之中。
关键词：对偶问题，鲁棒优化，模型预测控制，内点法，二次模型性能I介绍MPC是一种控制算法，显性的使用过程的模型通过最小化一个目标函数。
这个模型被用来预测将来的过程输出。
众所周知，MPC在过程工业中处理限制性的多变量的控制问题。
知道过程输出，一个控制序列能够被计算用来简化设计的目标函数。
然而，工厂中每一步只用控制信号的第一个元素，这就是被熟知的区间后退策略。
在下一次采样时会重复上一次的计算方法。
在优化过程中，MPC用一个线性动态过程的模型，线性输入的限制，输出，和输入的减小量最终在一个最优控制的一次规划或二次规划中。
在这种情况中，工厂的动态的过程是不确定的，鲁棒MPC 已经有了解决了这个问题策略，适用于描述不确定性的一般方法工厂使用各种可用的数学模型文献中可用的框架。
接下来，考虑到闭环鲁棒性的一组性能指数会被选择。
鲁棒MPC然后通过在每个采样间隔求解鲁棒最优控制序列获得。
区间后退策略在每个采样间隔都被用来完成MPC算法。
这个方法降低了容量和大量的计算，用于能够处理不确定问题的优化项目。
最近，一种叫做RO的方法在数学编程和应用研究中被广泛研究。
RO方法被设计用来解决优化问题，当数据不确定或只知道不确定集中的数据。
这种方法最先被Ben-Tal和Nemirovski采用。
燃煤循环流化床锅炉外文翻译
英文文献翻译1；文献原文(1)Coal-Fired, Circulating Fluidized-Bed Boilers in ActionElectric utilities burning coal continueto search for cost-effective ways toincrease electricity generation whilestill meeting increasingly stringent emissionstandards. Over the last several years,fluidized-bed combustion has emerged as aviable option. One company with significant experience in the area of industrial andutility boiler design has developed a compact atmospheric internal recirculation circulating fluidized-bed (IR-CFB) boiler forcommercial application.Performance data for Babcock & WilcoxIR-CFB installations at Southern IllinoisUniversity (SIU) and an industrial facility inIndia are reported in a recent paper preparedby S. Kavidass and Mikhail Maryamchik ofBabcock & Wilcox (Barberton, Ohio),C. Price of SIU (Carbondale, Illinois), andA. Mandal of Kanoria Chemicals & Industries Ltd. (Renukoot, India). The paper, entitled ―B&W’s IR-CFB Coal-Fired BoilerOpe rating Experiences,‖ was presented atthe Fifteenth Annual International Pittsburgh Coal Conference, held September 14–18, 1998 inPittsburgh, Pennsylvania.IR-CFB Boiler DesignIn a fluidized-bed boiler, crushed coal isintroduced into a furnace containing a bedof either an inert material (like sand orcrushed limestone) or dolomite. Pressurizedair, fed into the bottom of the furnace, blowsupward through the bed and causes the coaland bed materials to ―fluidize‖ in a highlyturbulent, suspended state. Figure 1 profilesa typical IR-CFB furnace, demonstrating thechange in bed density with increasingheight. The turbulence of the fluidized-bedsystem allows prolonged contact betweenthe air and the particles of coal, resulting inmore complete combustion at a lower temperature than older systems (which reducesnitrogen oxides). If sorbent material such aslimestone is used as bed material, emissionsof sulfur dioxide are likewise reduced due toconversion to calcium sulfate. Further, because combustion occurs at a lower temperature, the process is relatively insensitiveto the type of fuel burned. This allows theuse of alternative fuels such as coal waste,biomass fuels, petroleum coke, and otherlower British thermal unit (Btu) material.A circulating fluidized bed captures thesolids carried out of the furnace and returnsthem to the primary combustion chamber.This recycling feature increases the fuel residence time in the furnace, which increasescombustion efficiency. The Babcock &Wilcox IR-CFB boiler provides two stagesof solids recirculation, maximizing fuelburnout and sulfur capture. Also, designvelocities at the furnace exit are relativelylow, which significantly reduces erosion ofthe upper furnace and primary solids separator.Unique Design FeaturesOne of the features of Babcock & Wilcox’s IR-CFB design is the use of a U-beamsolids separation system. As shown in Figure 2, the U-beam system consists of rowsof U-shaped vertical rods attached to theroof of the furnace that interrupt the flow ofthe gases exiting the furnace. Two rows ofU-beams are placed inside the furnace itself,and four rows of U-beams are installed behind the furnace rear wallplane. The in-furnace U-beams capture about 75% of thesolids, which slide down the length of thebeams back into the combustion chamber.The remaining solid particles captured in theexternal U-beams are collected in a particlestorage hopper, which is periodically emptied back into the furnace forreburning.Theflue gas velocity across the U-beams isaround 8 meters/second (26.5 ft/sec) or less,producing a relatively low gas-side pressuredrop (less than 1 inch of water column) ascompared to conventional cyclone-typeseparators (6 to 10 inches of water column).The IR-CFB furnace is made of gas-tightmembrane enclosure water-cooled wallswith studded tubing spaced every fourinches. The lower furnace walls (up to aheight of 7.3 meters [24 ft]) are protectedwith an ultra high-strength, abrasion-resistant, low-cement refractory material lessthan 1 inch in thickness, which is placedover the studs protruding from the coolingtubes. A band of metal spray is typicallyapplied to further protect against erosion atthe point where the refractory material ends.The very thin application of refractory material means faster startup and less maintenance cost.Other beneficial characteristics of the IR-CFB boiler design include:* Use of in-furnace surfaces (division andwing walls) for furnace temperature control;* Gravity fuel feed and simplified secondary ash recycle system;* Absence of hot expansion joints, allowingsignificantly reduced maintenance;* Smaller footprint, which allows retrofitinside existing structural steel.Operating Experience at Two InstallationsThe IR-CFB design has been installed attwo locations—one at SIU in Carbondale, Illinois, and the second at the KanoriaChemicals & Industries Ltd. (Kanoria) sitein Renukoot, India. The SIU installation is a35-megawatt (MW) boiler that burns high-sulfur, low-ash Illinois coal, while the 81-MW Kanoria unit uses low-sulfur, high-ashcoal. The SIU boiler has a crushed limestonebed to combat the higher sulfur content ofthe fuel, while the Kanoria boiler uses a sandbed.SIU Unit dataThe SIU boiler is located close to the OldBen II coal mine in southern Illinois. Theplant was completed in 1996 and startedoperation in mid-1997. Performance testingwas completed in September 1997. Table 1shows the design and performance data forthe SIU boiler.Raw coal, delivered by truck, is movedby drag chain conveyor to a crusher. A24-hour capacity silo stores the pulverizedcoal. The coal is introduced into the furnaceby one gravimetric feeder through the sidewall. Two 60-MMBtu/hr gas-fired, over-bed burners and two 25-MMBtu/hr gas-fired, in-bed lances provide heat for startup.A multi-cyclone dust collector is used as asecondary solids separator (downstreamfrom the U-beams). The overall solids collection efficiency exceeds 90% and solidscollected in the cyclone are returned to thefurnace via an air fluidized conveyor. Abaghouse provides final particulate control.The bed material is periodically drainedfrom the furnace to control bed solids build-up and to remove any oversized material.The SIU unit has a single 8-inchdiameterdrain pipe to remove the bed, which iscooled with a screw ash cooler using recirculated plant water supply.Cold startup to 100% maximum continuous rating (MCR) can be achieved withinfive hours and the observed boiler dynamicload response is 5%–6% per minute. Aboiler turndown of 5:1 has been achievedwithout auxiliary fuel (a turndown ratio of3.5:1 to 4:1 is guaranteed). Further, all majorequipment has performed reliably whilemeeting or surpassing permitted emissions.A soot blower installed at the horizontalconvection pass floor has experienced plugging with ash and residual moisture. Whilethe boiler can operate successfully withoutthe soot blower, more investigation isneeded to overcome this operational glitch.Kanoria Unit DataThe Kanoria facility is located within thestate of Utter Pradesh, India, in close proximity to the Singaroli coal mine. The boilerwas constructed in 1996 and began commercial operation in February 1997. Performance testing continued until September1997. Design and performance data for theKanoria boiler are also shown in Table 1.In contrast to the Illinois coal, the Kanoriafuel is erosive, low in sulfur, and high in ash.Crushed coal is introduced via two volumetric drag chain feeders through the front wallof the furnace. Two 60-MMBtu/hr oil-firedover-bed burners provide heat for startup.Solids collected by the U-beams are reinjected by gravity into the furnace at fourlocations. The Kanoria unit uses an electro-static precipitator for final particulate control. Bed draining is accomplished throughtwo bed drain pipes and ash coolers; finematerial is returned to the furnace, whileoversize particles are diverted to the ashdisposal system.The observed boiler efficiency of 88.8%is higher than originally anticipated andcombustion efficiency has exceeded 99%,due to very low unburned carbon and lowflue gas outlet temperatures. However, theerosive nature of the fuel initially causedtubing leaks in the water-cooled furnacewall, which have been remedied by applyingadditional metal spray at the refractory interface and adjusting the interface angle.Also, furnace temperature exceeded designvalue on several occasions due to insufficient upper furnace inventory caused by failures of the first fields of the electrostaticprecipitator and the ash conveying system.Adjustments to the precipitator rectifier andthe ash silo backpressure have solved theseproblems.In summary, two examples of IR-CFBboilers are successfully operating at 100%MCR with varying fuel types. IR-CFB appears reliable and incorporates several verylow-maintenance features that reduce operating costs.（2）Why Build a Circulating Fluidized Bed Boilerto Generate Steam and Electric PowerAbstractIn Asia, demand for electric power continues to rise steeplydue to population growth, economic development, and progres-sive substitution of alternate technologywith clean forms ofenergy generation. Atmospheric circulating fluidized bed (CFB)echnology has emerged as an environmentally acceptable technology for burning a wide range of solid fuels to generate steamand electricity power. CFB, although less than 20 years old, is amature technology with more than 400 CFB boilers in operation worldwide, ranging from 5 MW e to 250 MW e.Electric utilities and Independent Power Producers must nowselect a technology that will utilize a wide range of low-costsolid fuels, reduce emissions, reduce life cycle costs, and provide reliable steam generation for electric power generation.Therefore, CFB is often the preferred technology. Even thoughpulverized coal (PC) fired boilers continue to play a major roleworldwide, they have inherent issues such as fuel inflexibility,environmental concerns and higher maintenance costs.This paper discusses the benefits of CFB boilers for utilityand industrial applications. Specific emphasis is given to B&W’snternal Recirculation CFB (IR-CFB) technology, CFB technology comparisons, PC vs. CFB technology, emissions benefits,and economics including maintenance cost and boiler reliabilty. IntroductionBabcock & Wilcox (B&W) is a leading global supplier ofindustrial/utility boilers and has supplied more than 700 unitstotaling more than 270,000 MW e. Many of B&W’s CFB boilerdesign features have been adapted from vast experience designing and building boilers of all types and sizes for industrial andelectric utility applications. B&W’s design is an inherently compact, distinctive internal recirculation fluidized bed (IR-CFB)boiler featuring U-Beam solids separators. The furnace and convection pass of the IR-CFB boiler are within a single, gas–tightmembrane enclosure as commonly found in Pulverized Coal(PC) fired boilers. This CFB technology has been successfullyintroduced in the global market.To date, B&W, including B&W joint ventures and licenseecompanies, has sold 16 CFB boilers worldwide, shown in Table 1.B&W offers IR-CFB boilers up to 175 MWe, both reheat andnon-reheat, with full commercial guarantees and warranties. TheIR-CFB boiler is simple in configuration and compact, requiresa smaller boiler foot print, has minimal refractory, requires lowmaintenance, features quick startup, and provides high avail-ability.The modern way of burning solid fuels requires fuel flex-ibility and reliable technology, plus good combustion efficiencywith low emissions. CFB technology is well suited for a widerange of sold fuels. CFB technology is proven, mature and competitive.What is CFB technology?CFB technology utilizes the fluidized bed principle in whichcrushed (6 –12 mm x 0 size) fuel and limestone are injectedinto the furnace or combustor. The particles are suspended in astream of upwardly flowing air (60-70% of the total air) whichenters the bottom of the furnace through air distribution nozzles.The balance of combustion air is admitted above the bottom ofthe furnace as secondary air. While combustion takes place at840-900 C, the fine particles (<450 microns) are elutriated outof the furnace with flue gas velocity of 4-6 m/s. The particlesare then collected by the solidsseparators and circulated back into the furnace. This combustion process is called circulatingfluidized bed (CFB). The particles’ circulation provides efficient heat transfer to the furnace walls and longer residence timefor carbon and limestone utilization. Similar to PC firing, thecontrolling parameters in the CFB combustion process are temperature, residence time and turbulence.Designers and power plant operators have vast experience in PC-fired boiler design and operations. Adapting and under-standing CFB technology by those familiar with the PC environment requires time. CFB technology brings the capability ofdesigns for a wide range of fuels from low quality to high quality fuels, lower emissions, elimination of high maintenance pulverizers, low auxiliary fuel support and reduced life cycle costs.A PC vs. IR-CFB comparison is given in Table 2.The combustion temperature of a CFB (840-900 C) is muchlower than PC (1350-1500 C) which results in lower Nox for-mation and the ability to capture SO2with limestone injectionin the furnace. Even though the combustion temperature of CFBis low, the fuel residence time is higher than PC, which resultsin good combustion efficiencies comparable to PC. The PC pulverizers, which grind the coal to 70% less than 75 microns, require significant maintenance expenses. These costs are virtually eliminated in CFB because the coal is crushed to 12 - 6 mmx 0 size. Even though CFB boiler equipment is designed forrelatively lower flue gas velocities, the heat transfer coefficientof the CFB furnace is nearly double that of PC which makes thefurnace compact. In an IR-CFB, auxiliary fuel support is neededfor cold startup and operation below 25% versus 40-60% MCRwith PC. One of the most important aspects is that CFB boilers release very low levels of SO2 and NO x pollutants compared to PC, as shown in Table 2. PC units need a scrubber system, whichrequires additional maintenance.CFB is a fuel-driven and flexible technologyCFB can be the technology of choice for several reasons.The CFB can handle a wide range of fuels such as coal, wastecoal, anthracite, lignite, petroleum coke and agricultural waste,with low heating value (>1500 kcal/kg), high moisture content(< 55%), and high ash content (< 60%). The fuel flexibility provides use of opportunity fuels where uncertainty of fuel supplyexists and economics are an issue. If a CFB boiler is designedfor coal, the same boiler can be used to burn lignite or petroleum coke or anthracite. The material handling and feeding system should be properly designed to meet these fuel variations.Such fuel flexibility is not available in the competing conventional PC-fired boiler technologies. This is one of the importantfeatures of CFB that the customer needs to analyze carefullybefore selecting a technology.Environmental benefits of CFB technologyThe CFB combustion process facilitates steam generationfiring a wide range of fuels while meeting the required emissions such as sulfur dioxide (SO2 ) and nitrogen oxides (NO x)even more effectively than World Bank guidelines, as shown inTable 3.The major environmental benefit of selecting CFB technology is the removal of SO2(90-95%) and NO x(emission is lessthan 100 ppm) in the combustion process without adding postcombustion cleaning equipment such as wet or dry flue gasdesulfurization (FGD) systems and selective catalytic reduction(SCR) systems. When the limestone is injected into the furnace,the following reactions occur.* Oxidation of sulfurS+O2 --> SO2* Limestone is calcined to form calcium oxideCaCO3--> CaO + CO2–425 kcal/kg (of CaCO3 )* Sulfur dioxide gas reacts with solid CaOSO2+ 1/2 O2 + CaO --> CaSO4 (Solid) +3740 kcal/kg (of S) The resulting calcium-sulfate-based ashes are chemicallystable and are easily disposed. This ash can be used as raw material for cement manufacturing, soil stabilization, concreteblocks, road base, structural fills, etc. Limestone injection isrequired for fuels with sulfur greater than >0.5%. Lime (CaO)and unburned carbon content must be considered in re-use applications, depending on the fuel being fired.NO x present in flue gas generally comes from two sources:the oxidation of nitrogen compounds in the fuel (fuel NO x) andreaction between the nitrogen and oxygen in the combustionair (thermal NO x). With low temperature and staged combustion,the oxidation of fuel nitrogen is suppressed resulting in verylow NO x emissions. NO x emissions are <100 ppm with CFB.CO and hydrocarbon emissions in the CFB boiler are wellcontrolled. In recent years, financial institutions have pushedthe power project developers to meet the World Bank emissionsrequirements. Therefore obtaining the project permit is less difficult with CFB technology.Design features of B&W IR-CFB Boiler technologyB&W IR-CFB technology is very comparable to PC-firedboilers in arrangement. The IR-CFB boiler design consists ofthe following major systems, shown in Fig. 1. The main CFBboiler components are:* Boiler furnace* Furnace bottom air distributor and nozzles* Primary solids separators and recirculation system* Secondary solids separators and recirculation system* Pendant superheater / reheater* Economizer and horizontal tubular air heater* Air assisted gravity fuel /limestone feed systemBoiler FurnaceThe furnace cross section is selected based on flue gas superficial velocity. B&W typically uses furnace depths of 3.7 m,4.6 m and 5.4 m, depending on the unit size. The furnace enclosure is made of gas-tight membrane water-cooled walls having63.5 mm or 76 mm tube diameters on 102 mm centers. The furnace primary zone is reduced in plan area cross section to provide good mixing and promote solids entrainment at low load.The auxiliary startup burners, fuel feed points and secondaryash re-injection (multicyclone/MDC) points are located in thisregion.A thin layer of refractory is applied on all lower furnace walls,including the lower portion of the division walls and wing wallnose to protect against corrosion and erosion. An ultra highstrength abrasion-resistant low cement alumina refractory 16-25 mm thick is applied over a dense pin studded pattern. B&Whas patented aRDZ TM reduced diameter zone feature that elimihas nates erosion concern at the furnace interface. The furnace temperature is precisely controlled by maintaining proper inventory and thus the combustion efficiency and the limestone utili-zation are maximized.Air Distrbutors and NozzlesThe furnace bottom air plenum or wind box is made of water-cooled panels or casing depending on startup air temperature. Bubble caps are fitted on the water-cooled distributor floorpanels as shown in Fig. 2. The bubble caps are designed to distribute air uniformly, prevent the back sifting of solids at lowload operation, and create good turbulence for fuel /sorbentmixing in the primary zone. The bubble caps are spaced 102mm x 117 mm with 60-70% of total combustion air admittedthrough the bottom. The balance 30-40% of total air is admittedthrough overfire nozzles (high velocity) in the front and rearfurnace walls.Primary Solids SeparatorsThe solids separation system is a key element of any CFBboiler design. The B&W separation system is designed for thelife of the unit without replacement, influencing life cycle costs.The B&W IR-CFB has a two stage primary solids separator asshown in Fig. 3, comprised of in-furnace U-Beam separatorsand external U-Beam separators. The in-furnace U-Beams (tworows) are able to collect nearly 75% of the solids. The remaining solids are collected by the four rows of external U-Beamsand are discharged from the hopper directly into the furnace throughthe transfer hopper located beneath the external U-Beams (See Fig.4). The flue gas velocity across the U-Beams is approximately 8-10 m/s, limiting the gas-side pressure drop to 0.25 kPa as compared with a typical cyclone separator’s pressure drop of 1.5 to 2.0kPa. A commercially available, high-grade stainless steel materialis used for the U-Beam separators.Secondary Solids SeparatorThe multicyclone dust collector (MDC) is located in the convective pass either upstream or downstream of the economizer.The MDC typically has a top inlet and top outlet as shown inFig. 5. The MDC tube diameter is normally 229 mm arrangedover the second pass entire cross section. The MDC providesoutstanding retainment of fine particles up to 50 microns. TheMDC collection tubes and spin vanes have high hardness (550BHN), designed for longer life and easy replacement duringplanned outages.The small quantities of fines which escape from the externalU-Beams are collected by the MDC. The collected fines arestored in the MDC hopper. Variable speed rotary feeders or inclinedscrews are used to control the ash recycle flow rate fromthe hopper. Precise furnace temperature control is achieved byadjusting the speed of the rotary feeders or inclined screws, taking the temperature signal from the furnace.The superheater may consist of vertical pendant type primary and secondary banks, located in the convection pass, aswell as surface in the furnace in the form of superheater wingwalls. An attemperator is used to control the final steam temperature over the design load range. The flue gas velocities arerelatively low and selected byconsidering the dust loading andash erosivity of the fuel. When required, the reheater is locatedin the convection pass, and steam bypass is recommended tocontrol the final reheater temperature.Economizer and Horizontal Tubular air heaterThe economizer is designed with tubes running front to backin an in-line arrangement. Flue gas velocities used consider thedust loading and ash erosivity of the fuel. If the MDC is locatedupstream of the economizer, higher velocities are used and boththe economizer and the air heater are located in an in-line arrangement to minimize ash fouling. The air heater is locatedafter the MDC and the economizer. The flue gas is outside thetubes and air is passed through the tubes. A hopper is providedat the bottom of the air heater and the ash collected in the hopper is purged to the ash disposal system. The tube material andflue gas velocities are selected by considering the dust loadingand the ash erosivity of the fuel. A steam coil air heater (SCAH)is used to protect the cold end of the air heater if required.Air-Assisted Gravity Fuel/Limestone Feed SystemFuel handling and feeding is one of the major challenges inCFB boiler operation, especially with waste fuels because ofhigh fines and moisture content. The crushed fuel (6-12 mm x0) is stored in the silo, usually located in front of the boiler asshown in Fig. 6. Fuel is fed to the boiler via down spout fromsilo discharge to feeder and a series of feeders and gravity feedchutes. The fuel chute will have at least a 65 degree angle fromhorizontal. Primary air is used to sweep the fuel into the furnace and as seal air to the feeders. The number of feed points isset to achieve even fuel distribution in the furnace.The limestone handling and feeding system is relativelysimple compared to the fuel feed system. Limestone is fed either pneumatically or mechanically into the CFB boiler. Thepneumatic system feeds the limestone directly into the furnacethrough furnace openings in the front and rear walls. In themechanical system, the limestone is fed into the discharge endof the fuel feeders via rotary feeders. The limestone falls bygravity down the fuel feed chute with the fuel into the furnace,and is a function of fuel velocity and required emissions.CFB Technology ComparisonVirtually all major boiler manufacturers are involved inCFB technology. Two distinct types of solids separation systems are used. One type is cyclone–based, which provides singlestage solids collection systems, and the second type is impactseparator-based, which provides a two-stage solids separationsystem. A comparison of B&W IR-CFB technology features withthose of other major commercial CFB technologies is given inTable 4.Advantages of the B&W IR-CFB Boiler technology*Boiler is compact with primary U-Beam separators andprovides internal solids recycle.* Boiler has a smaller foot print (up to 20 to 30% less building volume compared to a hot cyclone-based CFB boiler)* Boiler design is especially suitable for retrofitting of olderPC-fired boilers within the existing support steel.* Two-stage solids separation efficiency (>99.7%) provideshigher carbon efficiencies and better limestone utilization through higher solids residence time.* Wide turndown ratio (4:1) without auxiliary fuel is possible due to the selection of furnace velocity and control-lable solids recycle.* Less refractory in the boiler allows for quicker startupand lower maintenance costs.Economics of CFB TechnologyCFB technology can burn a wide range of low cost solidfuels and competes well with oil/gas fired plants. The decision-makers often ask, ―What are capital and operating costs andbenefits of a CFB boiler?‖ The experience in Europe and NorthAmerica suggests that for a sulfur fuel (>0.5%S) and less than150 MW, a CFB boiler has 8-15 percent lower capital costs aswell as 5-10% lower operating costs than a PC-fired boiler because of the FGD system. In general, CFB-based power plantsprovide low emissions control costs and low O&M costs, whichlead to lower life cycle costs. In the end, owner profit marginincreases and payback period improves as shown in Table 5.Costs not included in Table 5 are items such as land, projectdevelopment, permitting, escalation, taxes and owner’s costs,since these costs are common for both PC and CFB-based powerplants.Reliability of CFB TechnologyCFB boiler design is simple and proven, compared to othertechnologies. Experience indicates that operating and maintenance costs are relatively lower than PC-fired boilers becauseof the ability to burn lower rank fuels, thus reducing fuel costescalation uncertainty. Since maintenance areas are very minimal in the CFB boiler, the availability of the boiler is relativelyhigher. The CFB design allows emissions reduction without significant capital cost, since SO2 and NO x removal are inherentwithin the combustion process.ConculusionEven though a number of competing technologies areavailable in the market for steam and electric power generation, CFB is an excellent choice due to its fuel flexibility, widerturndown without support oil/gas, superior environmental performance, lower operating and maintenance costs, and safe, reliable and simple boiler operation. The B&W IR-CFB boilerdesign offers compact, superior performance due to two-stagesolids separation, and is cost effective for multiple fuel firingin both PC retrofit and greenfield applications.2；译文（1）燃煤循环流化床锅炉运行情况燃煤发电行业继续搜寻成本效益的方式,以增加发电量,同时达到日益严格的排放标准. 过去几年,流化床燃烧已成为一种可行的选择. 一个公司有重大领域的经验,工业及电站锅炉设计开发了紧凑型大气内部循环流化床(红外CFB )锅炉投入商业应用.Babcock & Wilcox的红外流化床装置, 最近在南伊利诺伊大学和印度的一个工业设施中，在一份由S.kavidass和米哈伊尔Maryamchik的Babcock &Wilcox (巴伯顿,俄亥俄州) , C.SIU(代尔,伊利诺州) ,和A的[27]卡诺里亚&化学工业有限公司( renukoot ,印度) 被报道 . 这份文件题为"巴威的红外循环流化床燃煤锅炉的操作经验" ,并提交于15年度国际匹兹堡煤炭会议于9月14-18 , 1998年在匹兹堡,宾夕法尼亚州.红外型循环流化床锅炉设计在循环流化床锅炉，煤粉被引入炉膛内的床上，其中包含或惰性物质（如砂或粉碎石灰石）或白云石。
电厂锅炉英文文献
电厂锅炉英文文献以下是一篇关于电厂锅炉的英文文献，供参考：Title: Boiler in Power Plant - A ReviewAbstract:Boilers play a crucial role in power plants, providing steam for electricity generation. This paper reviews the various types of boilers used in power plants, their working principle, and the challenges faced in their operation. It also discusses the importance of efficient boiler performance in ensuring reliable power generation.Introduction:Power plants heavily rely on boilers for steam generation, which in turn drives the turbines to generate electricity. Boiler technology has evolved significantly over the years, with advancements in efficiency, reliability, and environmental friendliness. This review provides a comprehensive overview of boiler technology in power plants, highlighting the key components and their functions. Types of Boilers:There are several types of boilers used in power plants, including pulverized coal-fired boilers, circulating fluidized bed boilers, and supercritical boilers. Each type has its unique characteristics and advantages. Pulverized coal-fired boilers are the most common type, where coal is ground into fine particles and burned in a furnace to produce steam. Circulating fluidized bed boilers use a bed of sand and fuel particles to achieve efficient combustion. Supercritical boilers operate at high pressures and temperatures toimprove efficiency.Working Principle:Boilers operate on the principle of heat transfer from the combustion of fuel to the working fluid, typically water or steam. Fuel is burned in the furnace, generating heat that is transferred to the water/steam in the boiler tubes. The heat transfer process is facilitated by convection and radiation. The resulting steam is then used to drive the turbines for electricity generation.Challenges in Boiler Operation:Boiler operation faces several challenges, including maintaining high efficiency, controlling emissions, and ensuring safety. Efficiency is crucial as it directly impacts the overall power plant performance. Design and operational factors affect boiler efficiency, and continuous monitoring and optimization are required to maximize efficiency. Emission control is also a significant challenge, as power plants are subject to strict environmental regulations. Lastly, safety considerations are paramount to prevent accidents and ensure the well-being of personnel.Conclusion:Boilers are vital components in power plants, responsible for steam generation and subsequently electricity production. Understanding the different types of boilers, their working principles, and the challenges in their operation is essential for efficient and reliable power generation. Ongoing research and development in boiler technology aim to further improve efficiency, reduce emissions, and enhance safety in power plant operations.。
热能毕业设计外文文献及翻译
用于分析在直燃式步进式加热炉板坯瞬态加热的传热模型摘要一个可以预测板坯表面温度分布和热流情况的数学传热模型已开发出来了，主要是通过充分考虑在炉膛内的板坯的热辐射和瞬态热传导方程来实现的。
该炉型是参照散热介质在空间中的变恒温过程和恒定的吸收系数来设计的。
钢坯由步进梁从一个固定梁移动到下一个固定梁上，是以通过加热炉预热段.加热段和均热段为钢坯热传导方程的边界条件的加热炉模型。
辐射热通量的计算是通过采用有限体积法，在炉子的内部，以炉墙.炉顶.炉底构成的充满烟气的环境里，作为板坯的瞬态传导方程的边界条件来进行计算的。
板坯的传热特性和温度特性是通过调查可以改变板坯吸收系数和发射率的参数来确定的。
比较多次的实践工作表明，目前用于预测板坯在加热炉中的传热过程和热流量的状况示范工程得到了很好的效果。
关键词：加热炉;钢坯加热;辐射传热;瞬态热传导;有限体积法1 导言在过去数十年以来，炉子进入降低能源消耗和污染物排放量的阶段，而分析钢坯瞬态热特性，在加热炉工程应用上已吸引了相当多注意。
此外，限定板坯在炉子内有均匀的温度分布才能出炉的重要性大大增加了，只有准确、快速的预测炉内板坯的温度，才能为以后的轧制过程提供比较好的原料，因为这决定了钢铁产品质量的高低。
在本质上，在炉膛内的整个燃烧过程和由此产生的热气流同时影响传热.对流和热辐射过程。
然而，复杂的炉子内部的三维结构包括固定梁和步行梁打滑问题使的难以在经济上做出准确的分析。
因此，模型和方法对于预测炉子内部燃烧特性和传热过程中存在着很高的要求。
尤其是，准确预测热辐射量是最重要的，因为热辐射传热超过流过板坯表面总热流的90％。
现在没有一个单一的辐射模型就能够解决所有在工程应用中遇到的情况，所以应选择一个合适的途径为自己的侧重点。
为了预测通过板坯表面上的辐射热通量，从而准确计算出炉子内板坯的温度分布，其解决方法是板坯必须是做连续运动，无灰的燃烧烟气作为该炉辐射气体，以及复杂的炉壁几何结构包括弯曲的板坯和防滑管道堵塞的影响，还有就是一定量的计算。
毕业论文 15TH燃油锅炉脱硫除尘工艺设计 外文翻译30_secret
酸森林烟道气体脱硫
【摘要】
烟道气体当一含白云石的石灰[CaMg(CO3)2]是使用在产生发电厂电中高硫煤的燃烧期间去除SO2的时候,desulfurization(FGD)副产品被建立.这研究评价北方红栎(Quercus rubraL)的成长.在一酸森林土壤(壤土的,混合壤土的,混合,长于湿地的,典型Hapludult Rayne 泥沙)和水中在乘土壤的石灰要求等于0.25,0.5,1.0,1.5,2.0和
2.5速度方面topically 应用被或者在淋溶层以内混合当FGD 在附近产品的时候沥出液品质用按每月一次用水将土壤过滤出来和沥出液样品为pH 值,传导性,P,S,B 和金属被分析(艾尔,Ca,Cr CuFe,Mn,K,Mg,Pb,Ti 和Zn).当土地是用FGD 处理的时候,树成长在相当大的程度上增加(p40.05)1.5倍于石灰要求速度和当FGD 在是应用的时候,最伟大成长(关于untreated 控制手段75%增加)发生.当FGD 副产品在二次(或者高)石灰要求速度方面是应用的时候,硼毒力症状在电厂组织中被注意到.
在中硫集中在处理沥出液四个月之后从不到控制手段土壤)增加到
234 mgl 1(在2.5倍于石灰要求用FGD 处理土地).硼也接近在沥出液中从毒力集中
在最高速度方面在开头沥滤期间处理土壤,但是集中倾向于用时间拒
绝.应用到酸森林土壤上面FGD 副产品有潜力,提供成长对一商业上重要树品种红栎的好处但是对将应该是需要来避免使用FGD 材料介意其可以发布B 的中毒的水平的.
【关键词】酸土壤;煤灰烬;煤燃烧副产品;烟道脱硫(FGD)副产品;飞灰;再循环;。
焦煤炉中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)原文：Energy saving and some environment improvements in coke-oven plants AbstractThe enthalpy of inlet coal and fuel gas is discharged from a coke-oven plant in the following forms: chemical and thermal enthalpy of incandescent coke, chemical and thermal enthalpy of coke-oven gas, thermal enthalpy of combustion exhaust gas, and waste heat from the body of the coke oven. In recent years the recovery of several kinds of waste energy from coke ovens has been promoted mainly for energy saving purposes, but also for the improvement of environmental conditions. Among the various devices yet realized, the substitution of the conventional wet quenching method with a coke dry cooling is the most technically and economically convenient. The aim of this paper is mainly a review of the main types of coke dry cooling plants and a detailed examination of the infiuence of some parameters, particularly of temperature and pressure of the produced steam, and on the energy efficiency of these plants.1. Introduction1.1. Usable energyThe energy of a system-environment combination is usually defined as the amount of work attainable when the system is brought to a state of unrestricted equilibrium (thermal, mechanical and chemical) by means of reversible processes, involving only the environment at a uniformly constant temperature and pressure and comprising substances that are in thermodynamic equilibrium. Notwithstanding the quite different meaning, chemical energies differ from lower heating values slightly, as is discussed in [1,2]. The chemical energy generally falls between the higher and lower heating values but is closer to the higher.Nomenclaturec p constant pressure heat capacity [kJ/(kg K)]Ex energy [kJ]Ex u usable energy[kJ]ex specific energy[kJ/kg]G v volume flow rate [m3(nTp)/h]G v*specific volume flow rate [m3(nTp)/t dry coke]i specific enthalpy [kJ/kg]p pressure [bar]s specific entropy [kJ/(kg K]T temperature [︒C, K]T o environment temperature [︒C, K]v specific volume [m3/kg]Фenergy effciency [dimensionless]Nonetheless, the chemical energy is not suitable for quantifying the technical value of a fuel for two reasons: (i) Prior to considering heat transfer, it is necessary to account for the essentially irreversible combustion process, which decreases the exergies of various fuels greatly in different ways. (ii) The work corresponding to reversible expansion of several components (in particular CO2) down to their atmospheric partial pressures cannot be obtained from the combustion gas, as is implicit in the energyde®nition. In addition, this work differs with fuel type. Consequently, Bisio [3] defined usable energyas the exergeticvalue following an adiabatic combustion with a given excess air ratio (e.g., 1.1) minus the energyloss resulting from irreversible mixing of com-bustion gas with the atmosphere after having reached atmospheric pressure and temperature.The ratio of usable energyto lower heating value of a given fuel is termed the merit factor. This factor is always less than one and increases as the technical and economic values of a fuel rise.The parameter “usable exergy”, as has been de®ned and applied in [3], is suitable in the examin-ation of plants, that utilize fuel mixing, when the aim is to reduce both the total fuel consumption and, chiefly, the more valuable component one.1.2. Coke-oven energy recoveriesThe chemical energy of a fuel gas, which is used for a coke oven, amounts to 2500-3200 MJ/t dry coal. This energy, degraded to thermal energy of various operative values, is discharged from the plant in such forms:1.Thermal energy of incandescent coke (43-48%)2.Thermal enthalpy of coke-oven gas (24-30%)3.Thermal energy of waste gas (10-18%)4.Permeability, convection and radiation heat from the external surface of coke oven, and various losses (10-17%)The oil crisis of 1973 created a strong impulse towards a new thinking on the consumption and rational utilization of energy, particularly in the highly industrialized countries with limited indigenous energy resources. At the same time, attention throughout the world was also increas-ingly focused on environment problems.The possible utilization of the thermal energy of incandescent coke is dealt with in many papers . Usually, in coking technology the coke is cooled by being sprayed with water under special quenching towers. In recent years, the various types of dry cooling plants allow the recov-ery of nearly 80% of the thermal energy of incandescent coke. The possibilities of utilizing reco-vered energy are as follows:1.Production of steam and electricity.2.Preheating of coking coal.3.Room heating.The thermal energy of coke-oven gas, which is the second largest in the above listing, has so far been rarely utilized. Various studies, however, have been carried out for the possible utilization of this waste energy and a technique has recently been commercialized in Japan. The thermal energy of combustion exhaust gas is utilized to preheat both the combustion air and fuel gas mixture through a large-capacity regenerator. Consequently the waste gas temperature is reduced to approximately 200 C. Lately, the further recovery of heat from waste gas has been reported in a few cases using a heat pipe installed in the ¯ue.The various kinds of heat wasted from the coke-oven external surface have been decreased by the reinforced sealing and better thermal insulation of coke ovens.In the following sections, the main types of coke-oven energy recoveries will be considered for a comparison.1.3. Protection of the environmentAs with the problem of energy saving and recovery, the last years have been characterized by increased prevention of atmospheric and water pollution by industrial emissions and domestic wastes. Work to control atmospheric pollution has been carried out in all developed countries. According to Zaichenko et al. , as a result of including measures for environmental protection, the investment and the coking costs are increased by 15%. However, if the calculations included allowance for losses caused by adverse effects of atmospheric pollution on workers health, instal-lation of engineering facilities for maintaining clean air can be cost-effective. In any case, it is obvious that an environmental facility is particularly tempting when, as with coke dry cooling plants, in addition to environment advantages, an energy recovery can be associated, even if the investment costs are higher and not justi®ed only by energy saving.2. Coke dry quenching2.1. Methods for energy recovery and saving from coke at the coke-oven outletThe idea of recovering thermal energy from incandescent coke by means of an inert gas dates back to the early 1900s. The ®rst industrial plants, designed particularly by the Sulzer Brothers (Winterthur, Switzerland) were carried out in the '20s and '30s both in the USA and in Europe (Germany, France, UK, Switzerland) [4,18]. However, the greater investment costs of dry quench-ing plants, in comparison with those of the wet quenching ones, were amortized with dif®culty in a period in which energy was very cheap. Consequently, dry quenching plants were given up.In the early 1960s, a new interest arose: in the USSR, dry cooling plants, which basically followed the Sulzer design, were built with the primary aim of preventing the coke from freezing in winter, as happens with wet quenched coke. The plant, constructed in various countries accord-ing to the Soviet Giprokoks process [6], is schematically shown in Fig. 1. The red-hot coke, at a temperature of about 1100︒C, is pushed from ovens, A, into containers placed on cars. Loaded cars are moved to the dry cooling plant, where containers, B, are lifted by bridgecrane, C, and unloaded through the charging system, D, into pre-chamber, E. Then,hot coke is transferred into the cooling chamber, F, in small batches. After leaving the cooling chamber through the discharg-ing system, G, coke runs, at a temperature of about 200︒C, onto conveyor belt, H. Coke is refriger-ated by a circulating gas, composed mainly by nitrogen and moved by the main blower, I. This gas transfers thermal energy in boiler, N, which produces superheated steam, O, at a pressure up to 100 bar. Before entering the boiler, the gas is scrubbed in the coarse de-duster, J, removing coarse particles of coke dust to protect the boilersurface from erosion. After leaving the boiler, the gas streams through the ®ne deduster, K, where ®ne dust is scrubbed out.In 1983 a dry cooling plant, schematically shown in Fig. 2, began operation in Germany. Its main characteristic is that 1/3 of the thermal energy is transferred directly from the coke to the vaporizing water and the remaining 2/3 through the inert gas. The advantages are a lower quantity of circulating gas with a correspondingly lower consumption of electrical energy by the blower and a greater energy recovery. Refrigerating walls in the cooling chamber represent the critical point of the plant i.In Germany, a combination of the coke dry cooling and coal preheating plant has been developed [5,9,14±16]. This system realizes primary energy saving (e.g. gas) instead of energy recovery of lower energyvalue (steam) and thus it is thermodynamically preferred (see, e.g., [29]). In addition, the well-known advantages of the single processes with respect to coke quality and increased output have been con®rmed. The completely closed system permits significant environmental improvements in the coking plant sector, avoiding the immissions of dust into the atmosphere in a practically complete way.Jung [13] considered the convenience of using water gas (H 2+CO) as the heat transfer fluid.Indeed, water gas has a thermal diffusivity three times that of nitrogen, and thus it allows us to reduce the boiler surface by 50%.In an anonymous note of “Metal Producing” [10], it was stated that the most convenient uses of the energy recovered from coke dry quenching (at least in the USA) are the following: the drying of coal and the heating of makeup water for boilers that provide steam in the coke plant per se. Indeed, the energy is available when the coke plant is running, which is of course when it is required. In addition, these quantities of energy match fairly well.2.2. Research on the optimal temperatures and pressures of steam2.2.1. Generalities about energy and energyanalysisIn Fig. 3 energy and energyflow diagrams are reported for a typical coke dry cooling plant with inlet coke temperature=1050°C and outlet coke temperature=200°C. Both diagrams are use-ful, however, only energyflow is suitable to visualize the operative value of the various energies.From Fig. 3 one remarks that with such devices it is possible to recover about 44% of the energyvalue of the incandescent coke thermal energy, corresponding to about the 20% of the energyvalue of the inlet coal.Owing to the relatively low value of the energyefficiency of a coke dry quenching system, it seems interesting to research the optimal values of some parameters, and in particular the charac-teristics of the steam produced (pressure and temperature) in order to obtain the more con-venient plant.A computer analysis has been made, assuming some input data, experimentally obtained from a recent actual plant. The input data are the temperature and pressure values of the gas flowing through the plant, the mass flow rates of coke at the inlet and outlet of the coke cooling chamber,and at the outlet of the coarse deduster, the mass flow rate, temperature and pressure of steam,the blower is entropic efficiency, and the efficiency in the electromechanical conversion of the electroblower. The fundamental data are:quenched coke mass flow rate 56 t/hsteam mass flow rate 28 t/hinlet coke temperature 1050°Coutlet coke temperature 200°Cspecific volume flow rate of gas 1650m 3 (nTp)/t dry coke.By varying the temperature and pressure of steam and/or the gas flow rate, one has determinedthe variation of the system energy efficiency, Ф , so defined:where: Ex st =steam exergy; Ex wa =boiler feed water; Ex c =energycorresponding to the electrical work of the electroblower; Ex co =coke physical energy(thus, excluding the chemical component of energy to be utilized in blast furnace).2.2.2. Specific energydependence upon temperature and pressureLet us consider specific energyas a function of temperature, T and pressure, p. In the diagram of Fig. 4, the steam specific energyfor an open system is reported as a function of pressure for various values of temperature. It is to be remarked that specific energyincreases always as T increases at constant p (for temperatures above that of the environment), whereas not always exincreases as p rises at constant T. This result seems puzzling and contrary to the concept of exergy.To justify the topic in a valid way, let consider the definition of specific energyfor an open sys-tem:and thenThe variation of specific enthalpy, di, and of specific entropy, ds, as a function of T and p can be written as [30]:and thenFrom these relations, one obtains that energyincreases as temperature rises, when T>T o , and the opposite is verified, when T<T o , as is well known. About the influence of pressure, one can say that energyincreases as pressure rises, when (T-T o .) and ∂1vtp have opposite sign, and, since with very few exceptions ∂1vtp> 0, when (T-T o )>0.When (T-T o ) and ∂1vtp have the same sign, one cannot exclude the possibility that exergy decreases when pressure goes up. This indeed is verified in a range in which the attractive forces are greatly prevailing on the repulsive forces [31]. For the problem that is here considered, this happens for superheated steam not far from the critical point. This analysis justifies that some is othermal curves of Fig. 4 have a maximum for a given pressure.On the other hand, this result could be yet puzzling. Indeed, it is well known that the operative value increases always with pressure. To this purpose, let us compare the following parameters:From these relations, in the range in which for the steam ∂2ex Tp <0 it follows:and then it follows that, if energydecreases as pressure goes down, the decrease of enthalpy is higher and consequently, even if the operative of the unit mass of steam goes down, the ratio of this operative value to the “cost” for obtaining it (i.e. the necessary heat) goes up and this is in agreement with the fact that a higher pressure is technically always more valuable. 2.2.3. Analysis results“Recovered exergy”has been determined; the numerator of relation (1) gives this parameter.As an example, in Figs. 5 and 6 the recovered energyis shown for one value of the specific volume flow rate of gas, alternatively, with steam pressure in abscissae (and temperature as parameter) or with steam temperature in abscissae (and pressure as parameter). One remarks that the recovered energygoes up almost linearly as the steam temperature increases, and goes up always as the steam pressure rises (contrary to the steam specific entropy), but with negative second derivative.In Fig. 7 the recovered energyis shown for one value of steam temperature as a function of the specific volume flow rate of gas (in abscissae) for various steam pressures (reported as parameter). To justify the diagrams, it must be remarked that as the specific volume flow rate of gas increases, the heat exchanged in the boiler between the gas and the water-steam increases with negative second derivative. Consequently, for every fixed couple of values of T and p, the team flow rate and the total steam energyexhibit the same behavior. On the contrary,owing to the increase of the necessary gas compression work, the recovered energyhas a maximum in correspondence with a given specific volume flow rate of gas. This maximum, for every temperature value, tends to a higher specific volume flow rate, as the pressure increases. In particular, at p=80 bar, the maximum is near to the value G v * =1650m 3 (nTp)/t dry coke .The variations of the energyefficiency, owing to its definition and the constancy of the physical energyof the incandescent coke, are totally similar to those of the recovered exergy. Thus, onlytwo diagrams for energyefficiency in correspondence to a specific volume flow rate of gasG v* =1650m 3 (nTp)/t dry coke are reported. In Figs. 8 and 9, energyefficiency vs steam pressure (with steam temperature as parameter) or vs the steam temperature (with steam pressure as parameter),respectively, is reported.On the basis of the various diagrams (not all here reported), the specific volume flow rate of gas G v* =1650m 3 (nTp)/t dry coke seems to be the more convenient. The very low increase of the recovered energy(and thus of the energyefficiency), that can be noted for some values of the couple (T, p) of the steam in correspondence to values of the specific volume flow rate of gas G v* slightly higher than 1650 m 3 (nTp)/t dry coke does not probably compensate the higher plant and maintenance costs.The temperature rise allows a remarkable energyefficiency increase. Thus, it seems convenientto choose the maximum temperature consistent with the use of materials which are not particularly expensive. The limit value of T=540°C can be presently chosen.As the pressure rises, energyefficiency increases remarkably till a pressure of about 80 bar, and then the increase is progressively reduced. For what is known to authors, the maximum value till now applied is of 103 bar in a steel plant of Japan. Thus, it seems that the more convenient pressure value is about 100 bar.焦炉设备的能源节约和环境改善摘要在下面几种形式中焦炉设备的进口煤和燃气的热量是不可控制的：炽热焦的化学和热焓，焦炉煤气的化学和热焓，燃烧排放气的热焓，还有从焦煤炉体中浪费的大量热量。
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自然循环热水锅炉水动力回路分析法
摘要：水动力计算都依据《热水锅炉水动力计算方法》,不足的是这种方法不能准确确定每根单管的工质流量，且不能准确确定工作点。
为了避免其不确定性，研究得出了一种数值水动力计算方法即水动力回路分析法，简称回路分析法。
该方法考虑了各种因素对锅炉本体每根管内工质流量的影响，在其热负荷、结构参数和工质流动阻力系数给定的条件下，可以准确计算出每根单管内的工质流量。
在相同的参数条件下，分别用标准法和回路分析法对某单一循环回路的水动力特性进行计算，计算结果验证了水动力回路分析法的正确性。
然后分别用标准法和回路分析法对一台自然循环热水锅炉的水动力特性进行计算，结果表明水动力回路分析法更准确并可接受。
关键词：热水锅炉；水动力；回路分析法
引言：
由于自然循环热水锅炉的大容量和对于断电保护、给水质量以及运行水平的低要求，它已经在中国广泛应用[1]。
然而，在上升管和下降管中工质的密度差过小可能会导致自然循环有效压力较低，如果结构不合理，将会产生爆管。
因此，在自然循环热水锅炉设计中，如何确定流动工质的安全速度和避免爆管导致受热面过冷沸腾是非常重要的。
在中国早期，有很多研究者致力于关于自然循环热水锅炉水动力计算的研究，一些人提出了对于几个简单循环回路和某些复杂循环回路的水动力计算方法，但是大多数方法只适用于简单回路。
西安交通大学的朱教授提出了一种应用计算机流体力学分析的方法，他将流动工质的特点和使用一种两端参考作为主动解决方法的直流循环原则做了比较。
这种方法的优势在于解决过程的方便性，但是对于复杂循环的解决过程非常复杂[2]。
自从上世纪七十年代，对于管流分布热力学模型的研究显著增多[3-8]。
目前，水动力计算方法使用“热水锅炉水动力计算法”[9](以下简称一般方法)，它提供了保证循环安全的一般方法。
该方法采用图解的方式确定介质的工作点，这是非常准确和高效的。
在解决整个问题时用到一些假设。
本文的目的是提供一种新的水动力数值计算方法，简称水动力回路分析法，即回路分析法。
本文的研究内容主要包括基本模型、基本原理、基本
方程及其可行性。
它使用分流的解决方法，这种方法更全面、准确和高效。
1模型研究
1.1基本模型
水动力计算的关键问题是获得在额定负荷下管中流动工质的特点[12-13]。
其中P1和P2分别是1-1和1-2处各自的压强，ρ是管中工质的平均密度，g是重力加速度，h是管子的高度，w是管内工质的流动速度，f是该管的的截面面积系数。
当工质从1-1处流向1-2处是，等式右边第二项的加号必须变为减号。
由于等式右边第二项的符号随流动工质的流动方向变化而改变，这是很难确定的。
此外，压力是速度的平方，所以这是一个非线性方程组。
为了克服上述的困难，这里介绍新的参数：
然后等式一与等式二变为：
其中E、U、G、R分别表示工质的动力、压力、流动率和流动阻力。
这两个方程类似于直流电路中电流的计算公式，单一管中有压力和阻力，单管等效图如图2所示。
在等式7中。
G是一个矢量，当工质从底部流向顶部时，G是正的，否则为负。
1.2回路分析法的基本原则
在回路分析法中，回路中的工质流量和分支中的工质流量被视为
未知量，方程根据工质压力的代数和为零的原则导出，即在循环回路中ΣU=0 和在循环中每个节点中流入的流量和等于流出的流量之和，即ΣG=0。
为了确保方程组有解，一个独立的回路必须被选为循环路径，并且工质在回路中的流动方向必须被确定。
顺着循环的方向，如果压力降低则为正，否则为负。
方程组通过计算机用迭代法求解[14-15]。
如果工质流量的计算结果是正的，则公职的流动方向与规定方向相同，反之则不同。
工质的流量和流动方向可以根据回路中工质的流量和流动方向确定。
以一个单回路循环为例，只包括一个上升管和一个下降管的单回路循环示意图如图3所示。
2结果与分析
2.1 计算实例
一个单回路的水动力特性采用一般方法和回路分析法进行分析，并且这两种方法采用相同的参数。
这个简单循环的结构如图3所示，结构参数列于表1，计算结果列于表2。
表1 结构参数
回路参数上升管下降管
总长/m 7 6
总高/m 5 5
热功率/kw 1000 1000
总阻力系数 2 1.5 管子直径/(mm*mm) 159*6 133*4 进口温度94 94
表2计算结果
方法质量流量（Kg/h）相对误差一般分析法25043 0.0559
回路分析法25057 ——
结果表明，在相同的参数下，因为相对误差很小，两种计算方法几乎是相同的。
因此。
回路分析法是正确的。
2.2 计算实践
在这一部分，用回路分析法和一般方法对一个具有自然循环的参数为
SHL7-1.0/115/70-AII的热水锅炉的水动力特性进行计算和分析，其结构参数、阻力系数、每个受热面的热负荷系数和计算结果都提供了参考[16]。
图4到图6分别显示的是工质在每个回路每个管中的流量曲线图，图7显示的是在对流回路中管中每个部分的流量曲线图。
表3分别列出了一般方法和回路分析法的计算结果。
图4到图7表明用回路分析法计算回路流量比较准确，并且过冷沸腾可以被直接检查出来，而一般分析法只能计算出管中工质的平均流量。
表3两种方法计算结果数据比较
方法前水冷壁
回路流量后水冷壁
回路流量
侧水冷壁
回路流量
对流循环
流量
流通率下降管进
口温度
一般法21600 23800 24100 196000 2.16 94.50
回路分析
法
21601 23850 24392 187916 2.10 93.66
相对误差0.0046 0.21 1.2 4.12 2.78 0.89 表3反映了水动力循环分析法和一般分析法的计算结果和计算出来的相对误差，循环回路的工质流量相对误差小于百分之五，流通率很小，并且下降管的进口温度非常低。
相对误差虽然小但是仍然存在，这有几个导致这个问题的原因。
首先，在一般分析法中，循环回路中的每个管子被视为相同的，这意味着每个管子是在相同的情形下而在回路分析法中每个管子在他们各自的工质状态下。
另一个原因是在回路分析法中，摩擦对流量的影响是分段考虑和计算的。
此外。
一般分析法中，必须用图解的方法来确定工作点，与回路分析法相比这更加不准确。
3总结
研究了一个单回路的水动力特性和发现了回路分析法的基本模型。
用
回路分析法和一般分析法计算和研究了自然循环热水锅炉的书动力特性，得到以下结论。
基本模型与直流电路中分流方法的模型相似，但是这个模型的关键点之一是方程组是非线性的。
两种方法的计算结果是相同的，表明了循环分析的正确性。
但是循环分析法考虑了影响每个管子流入总量和每个管子准确流量的因素。
此外，这种方法避免了用图解的方法来识别工质的工作点，因此它比一般分析法更准确一些。
回路分析法必须应用计算机来提高效率，因为手算求解方程组太复杂了。