换热站自动控制系统设计外文文献+翻译

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套管换热器英文文献翻译

能量转换和管理98(2015)69 - 2015内容列表可以在科学指引爱思唯尔（世界领先的科技及医学出版公司）能量转换和管理/locate/enconman homepage 日刊数值研究的一个创新设计翅片套管换热器与变量fin-tip 厚度a.高级研究中心纯粹和应用数学(CASPAM)Bahauddin 扎卡里亚正在搜索大学巴基斯坦68000年b.计算机科学、通讯卫星信息技术研究所、韦校园,Mailsi 路,木尔坦路,韦巴基斯坦c.数学系,政府爱默生学院60700年木尔坦,巴基斯坦d.基础科学和人文、工程科技大学Bahauddin 扎卡里亚正在搜索大学,木尔坦68000年,巴基斯坦分析充分发展的层流对流换热翅片的一个创新设计套管换热器(DPHE)和纵向鳍的变厚度提示受到施加力传热速率边界条件研究。

尖厚度控制的小费比底角作为参数的值从0到1对应于不同翅片形状不同的三角形和矩形截面。

到作者的知识,这个参数是首次被引入文学。

间断伽辽金有限元法(DG-FEM)从事目前的工作。

的整体性能提出DPHE 调查了考虑摩擦因素,努塞尔特数和j 因子。

努塞尔特数高达178%和89%的涨幅取得了j 因子相对rectangu-lar 横截面。

这样的收益相对于三角形截面分别为9.5%和19%。

结果表明,新引入的参数提示比底角证明发挥重要作用在套管换热器的设计在降低成本、重量和摩擦损失,提高换热器的传热速率和节能。

因此,它必须被视为一个重要的设计参数对换热器的设计。

通常,热交换器广泛用于这一目的。

有很多技术,用来提高换热器的传热速率但最有效的其中之一是使用安装鳍。

换热器的设计取决于许多特性即上浆、紧凑,传热性能估算,经济方面和压降分析。

目前的调查描述了数值研究的创新设计翅片套管换热器的变量fin-tip 厚度。

换热站自动控制系统设计外文文献+翻译

外文文献：Design and Implementation of Heat Exchange Station Control SystemKeywords:Heat exchange station, Control system, PLC, Inverter, Configuration software.Abstract.This paper introduces a design and implementation of heat exchange station control systembased on PLC and industrial configuration software, which includes the contr ol scheme and principle,hardware selection and software design, etc. The circulating pumps and re plenishing pumps in thesystem can all be driven automatically by PLC and inverter. Main process parameters, such as steampressure and measurement temperature and so on,can all be shown on the industrial PC runningconfiguration software, and instructions could be sent by the engineer and operator on-the-spot via theHuman Machine Interface as well. The automatic pressures adjustment of stea m supply of the heaterby advanced PID algorithm has been realized finally. It is verified that the system is highly reliableand stable, and it greatly enhances the level of automation and pressure control accuracy of the heatexchange station and meets all the equipments running demands well. IntroductionWith the rapid development of economy and society, heat supply systems are the key power source inthe communities and plants in China. As a media between heat sources and heat loads in the systems,a heat exchange stations plays a very important role for the heat supplyquality. Traditionally, most ofthe pumps in the heat supply systems are operated by valves manually, s o it could bring about thepower energy consuming, high labor intensity and low operation automation. I n this paper a design ofcontrol system for heat exchange station based on PLC, inverter and indust rial configuration softwarewas proposed,accordingly the aim for power energy saving,high heat efficiency and operationautomation has been achieved.Process outline and Control demandsProcess outline.The process outline and control demands were put forward at first before the schemeand design of heat exchange station control system were proposed.Heat exchange station consists of a steam-driven heater,plus3ci rculating pumps,2replenishingpumps and electric control valve. By adjusting the steam flux into the mixture of water and steamaccording to the temperature sensors mounted indoors and outdoors, the pr ocess of heat exchangecould be completed. Among these equipments, the steam-driven heater, a heat exchanger containingmixture of steam-and-water, is the key appliance for heat supply system.Control demands.Major control demands for the control system were listed a s follows [1]:(a)Pumps driving.Pumps include3circulating pumps(2in operation,1for backup)and2replenishing pumps (1 in operation, 1 for backup). Among circulating ones one is driven by powerfrequency, the others are driven by variable frequency, with 75KW power ea ch; among replenishingones one is driven by power frequency, the other is driven by variable frequency, with 3KW powereach. The control signal should be originated from the pressure difference between the supply waterand return water.Pumps could be driven in stepless speed regulating when connecting variablepower;(b)Parameters Showing.The showing parameters contain temperatureshowing-temperature ofsupply water, return water, the indoor, the outdoor and steam - and pre ssure showing - pressure ofsupply water, return water and pre-valve and post-valve of the steam etc;(c) Butterfly valves driving.Two butterfly valves can be on or of f automatically when the wholesystem start or stop;(d) Motor-driven valves control. By continuously adjusting the opening of t he valves according to thesignal from the temperature sensors indoors and outdoors, the supply wate r temperature should bestabilized in the presetting values;(e) HMI (Human Machine Interface) Demands. The process flow chart of heatexchange station andmain process parameter can be shown in HMI, and instructions can be trans mitted via this interface;(f) Safeguard Function. The circulating pumps should be out of running when heat exchange system isin water needing, and steam should be kept out of the heater when the pumps are not revolving.Hardware Selection of the Control SystemFrom the control demands mentioned above, the controller of the control s ystem can process signalsboth relay and analog, having the ability of loop adjustment of analog q uantity. At the meantime thepumps could run in the working condition of variable frequency, so the hardware selection of thecontrol system for heat exchange station should be made deliberately.PLC Serving as Main Controller.As some experienced electrica l engineers known,PLC/PC(Program Controller) is a kind of popular industrial computer, and it can not only accomplish logiccontrol, but also complete many advanced functions, such as analog quanti ty loop adjustment, andmotion control, etc. According to the component amounts of input and outpu t and the needs of controlsystem, FX1N-60MR micro PLC of MITSUBISHI FX series is selected, which hav ing 36 inputs and24 outputs, and doing analog adjustment by using advanced instruction likePID instruction [2].Because of the sampling and driving of the analog signal necessarily, P LC should be extended toanalog input/output function module like FX2N-4AD (4AD) and FX2N-4DA (4DA) or somethinglike.On one hand,4AD adopted is an analog input module having4channels with12bit highresolution, which could receive 0~+10V voltage signal, 0~20mA or 4~20mA cu rrent signal. On theother hand, 4DA chosen could send standard voltage signal and/or current signal, having 4 channelswith 12 bit high resolution also. It is something to be mentioned here , the wiring form of currentinput/output (4~20mA) must be adopted in order to avoiding the strong elec tromagnetism disturbancein the working field [3].Inverter completing Stepless Speed Regulating.At present, inverter, as an im port power electronicconverter, can convert constantly power frequency into continually variable frequency. Thus, energysaving, cost consuming and noise reduction can be easily reached by this equipment.In this control system inverter of ACS510 series of ABB Corporation were elaborately chosen, whichhas many advantages, such as Direct Torque Control (DTC) and advanced appl ying macro and so on.Its main good points and characteristics are illustrated as follows: it can acquire maximum startingtorque (200% normal torque) by using direct excitation; it can be applied to multiple driving systemsby using master-slave function;input and output programmable function;high precision of speedregulating, perfect safeguard and alarming steps. Owing to these highlights of this inverter, pumpsdriving of stepless speed regulating can be easily obtained.There are many applying macro inACS510 series, but we should only choose manual/automatic macro here as we need.IPC Acting as Monitor&Control Interface.IPC(Industrial Personal Computer)has strongcompatibility,extensibility and reliability,which can connect PLC by RS-232serial portconveniently. In the hardware configuration we select IPC H610 series of A DVANTECH as HMI.MCGS(Monitor Control Generated System),fashionable home-mad e industrial configurationsoftware, is running on the ADVANTECH IPC. Using this HMI, the visualizati on process of Monitorand Control is realized easily, intuitively and vividly.With the sensor/transducer,analog input/output modules,PLC a nd actuators,.inverter andmotor-driven valve, the loop adjustment of steam pressure can be precisely attained, and temperatureof all measure points could be measured also[4].The overall hardware configuration of heatexchange station control system see Fig. 1.Fig. 1 The overall hardware configuration of heat exchange station control systemSoftware Design of the Control SystemLAD Diagram Programming.Out of the thoughts of modular programming, the whole programstructure can be divided into such several modules as Initialization Function,upper IPCCommunication Function, Relay Control Function, Analog Sampling, Fuzzy PID Adjust Functionand Safeguard Function, etc. The flow chart of LAD diagram programming of PLC is shown in Fig. 2.Among these modular functions, it is something worthy to mention of Fuzzy PID Adjust Function.Under some circumstances the using of PID instruction of PLC was not so good at what we expected;therefore, the self-made program of Fuzzy PID adjustment of steam pressure was done from deviationand deviation acceleration of temperature between the indoor and the outdoo r in accordance with theFuzzy Control Theory and its application [5].HMI Configuration.For the sake of the appearance beauty and personalizati on between machineand human, the MCGS- Monitor Control Generated Software of Beijing MCGS Tech Co. Ltd wasadopted. This industrial configuration software has very quick, easy devel opment of configurationprocess, which can build bi-directional and high speed communication betwee n PLC and upper IPCthru RS422/232 serial port.In the development environment of MCGS, all needed windows and pictures we re created, includingMain Window of Process Flow, Process Parameters Showing Window, and Key P arameters SettingWindow, etc. Vivid and readily interaction between human and machine can be completed by suchbeautiful pictures and animations when IPC running MCGS.ConclusionsThis design of heat exchange station control system based onFX series PLC,MCGS,and ABBinverter has been realized the pressure automatic adjustment of steam-driven heater as originallyexpected.More over,design demands of power energy savi ng,high heat efficiency and lowequipments noise can all be well met. Finally, the practical operation ver ifies that the system is highlyreliable and stable, and it greatly enhances the level of automation and pressure control accuracy ofheat exchange station and meets equipments requirements of energy saving an d green driving.BEGINInitializationFuzzy PIDAdjust FunctionCommunicationFunctionAnalog OutputNoRelay ControlFunctionAnalog FilteringFunctionCall AnalogSample FunctionSample OverYesAnalog InputLinear TransferLinear TransferAnalog OutputDrivingSafeguard FunctionFailure OccurNoYesFailure HandlingRelated MemoryResetENDFig. 2 The flow chat of LAD diagram programming of PLCAcknowledgementComposition of this paper was with the help and under the direction ofSenior Engineer Nian-huiZhang of Qingdao Wellborn Automation Corporation.References[1]Information on H. Zhang, . Li:The Principle of PLC with itsApplications to Process Control(China PowerPress, Beijing 2008).[3]H. Zhang:The Design and Development of MITSUBISHI FX Series PLC( China Machine Press,Beijing 2009).[4]H. Zhang: Process Automation Instrumentation, Vol. 31(4) (2010), p. 34-36, in Chinese.[5]. Zadeh:Fuzzy Sets and their Applications(Academic Press, New Yor k 1975).Progress in Civil Engineeringand Implementation of Heat Exchange Station Control System外文翻译：换热站控制系统的设计和实现关键词:换热站、控制系统、PLC、变频器、配置软件。

不锈钢制换热器的优化设计文献翻译

One of the most effective methods of increasing the rate of heat transfer in heat exchangersis using tubes with lengthwise corrugations (Fig. i). Among the different methodsknown here and abroadfor making such tubes (longitudinal and rotary rolling, welding, drawing,forging), cold drawing occupies an important position. This is because of the highproductivity of this method, the accuracy of the tube dimensions, the good surface finish,and the fact that the tool is relatively simple to fabricate. A technology has been developedand introduced at several nonferrous metallurgical plants for drawing copper-alloy tubeswith lengthwise corrugations.The Pervouralsk New Tube Plant is developing a technology for drawing such tubes madeof carbon steel. Trial lots of tubes with a corrugated outer surface have been made andstudies are being conducted to determine the optimum geometry of the die.There are certain distinctive features of drawing stainless steel tubes that owe to theproperties of the material. The cold working of alloy steels -- thus, stainless steels -- ischaracterized by a high susceptibility to work hardening, low thermal conductivity, and thepresence of a hard and strong film on the surface which is passive to lubricants. The presenceof the film leads to seizing of the tube in the die. Existing lubricants and prelubricantcoatings do not provide a plasticized layer that will prevent the metal from adheringto the die and ensure a uniform strain distribution over the tube wall thickness.The Ural Polytechnic Institute and the Institute of Electrochemistry of the Ural ScienceCenter under the Academy of Science of the USSR have developed a technology for applying acopper coating to the surface of tubes made of corrosion-resistant steels. The coating isapplied in the form of a melt containing copper salts at 400-500~ and allowed to stand fori0 min. The layer of copper 10-40 ~m thick formed on the surface by this operation is stronglybound to the base metal. The copper coating makes it possible to draw tubes of stainlesssteel on a mandrel.The sector metallurgical-equipment laboratory at the UralPolytechnic Institute studiedthe process of drawing stainless steel tubes using the copper coating on short(stationary)and long (movable) mandrels. The study showed that the metal does not adhere to the die, thecoating is strongly bound to the base metal, and large reductions can be made in one pass.These results suggested that stainless-steel tubes with lengthwise corrugations could beproduced by cold drawing. Thus, the laboratory prepared trial lots of corrugated steel12KhI8NIOT tubes.其中一个最有效的办法来增加率换热器的传热利用管corrugations与纵向(Fig.我)。

控制系统中英文对照

Burner Management System燃烧管理系统CCR:Center control room中控室ER:Engineering room工程师室FRR:Field Rack Room现场仪表机柜室（控制室分站）DCS:Distributed control system集散控制系统ESD:Emergency shut-down system紧急停车系统FAT:Factory Acceptance Test工厂验收测试HMIHuman Machine Interface (operator station)人机接口（操作员站）I/O:Input/Output输入/输出MCCMotor Control Center马达控制中心MMS:Machinery Monitoring System机械监测系统MOV:Motor Operated Valve电动阀P&ID:Piping and Instrument Diagrams管道仪表流程图PFD:Process Flow Diagram工艺流程图PLC:Programmable Logic Controller可编程逻辑控制器PU:Package Unit成套设备SAT:Site Acceptance Test现场认可测试SOE:Sequence Of Events事件序列记录SIL:Safety Integrity Level安全完整性等级SIS:Safety Instrumented System安全仪表系统TMR:Triple Modular Redundant三重模块冗余Quadruple Modular Redundant (dual redundant system) 四重模块冗余（双重冗余系统）UPSUninterruptible Power Supply不间断电源1oo2One out of two, likewise: 2oo32选1，同样地3选2Aabort 中断,停止abnormal 异常abrader 研磨,磨石,研磨工具absence 失去Absence of brush 无(碳)刷Absolute ABS 绝对的Absolute atmosphere ATA 绝对大气压AC Lub oil pump 交流润滑油泵absorptance 吸收比,吸收率acceleration 加速accelerator 加速器accept 接受access 存取accomplish 完成,达到accumulator 蓄电池,累加器Accumulator battery 蓄电池组accuracy 准确,精确acid 酸性,酸的Acid washing 酸洗acknowledge 确认,响应acquisition 发现,取得action 动作Active power 有功功率actuator 执行机构address 地址adequate 适当的，充分的adjust 调整，校正Admission mode 进汽方式Aerial line 天线after 以后air 风，空气Air compressor 空压机Air duct pressure 风管压力Air ejector 抽气器Air exhaust fan 排气扇Air heater 空气加热器Air preheater 空气预热器Air receiver 空气罐Alarm 报警algorithm 算法alphanumeric 字母数字Alternating current 交流电Altitude 高度，海拔Ambient 周围的，环境的Ambient temp 环境温度ammeter 电流表，安培计Ammonia tank 氨水箱Ampere 安培amplifier 放大器Analog 模拟Analog input 模拟输入Analog-to-digital A/D 模拟转换Analysis 分析Angle 角度Angle valve 角伐Angle of lag 滞后角Angle of lead 超前角anthracite 无烟煤Anion 阴离子Anionic exchanger 阴离子交换器Anode 阳极，正极announce 通知，宣布Annual 年的，年报Annual energy output 年发电量anticipate 预期，期望Aph slow motion motor 空预器低速马达Application program 应用程序approach 近似值，接近Arc 电弧，弧光architecture 建筑物结构Area 面积，区域armature 电枢，转子衔铁Arrester 避雷器Ash 灰烬，废墟Ash handling 除灰Ash settling pond 沉渣池Ash slurry pump 灰浆泵assemble 安装，组装Assume 假定,采取,担任Asynchronous motor 异步马达atmosphere 大气，大气压Atomizing 雾化Attempt 企图Attemperater 减温器，调温器Attention 注意Attenuation 衰減,减少,降低Auto reclose 自动重合闸Auto transfer 自动转移Autoformer 自耦变压器Automatic AUTO 自动Automatic voltage regulator 自动调压器Auxiliary AUX 辅助的Auxiliary power 厂用电Available 有效的,可用的Avoid 避免,回避Avometer 万用表,安伏欧表计Axial 轴向的Axis 轴,轴线Axis disp protection 轴向位移，保护Axle 轴，车轴，心捧BBack 背后，反向的Back pressure 背压Back wash 反冲洗Back up 支持，备用Back ward 向后Baffle 隔板Bag filter 除尘布袋Balance 平衡Ball 球Ball valve 球阀Bar 巴，条杆Bar screen material classifier 栅形滤网base 基础、根据Base load 基本负荷Base mode 基本方式Batch processing unit 批处理单元Battery 电池Bearing BRG 轴承before 在…之前bell 铃Belt 带，皮带Bend 挠度，弯曲BLAS 偏置，偏压Binary 二进制，双Black 黑色Black out 大停电，全厂停电blade 叶片Bleed 放气，放水Blocking signal 闭锁信号Blow 吹Blow down 排污Blowlamp 喷灯blue 蓝色Bms watchdog Bms看门狗，bms监视器boiler BLR 锅炉Boiler feedwater pump BFP 锅炉给水泵Boil-off 蒸发汽化bolt 螺栓bore 孔，腔boost BST 增压，提高Boost centrifugal pump BST CEP 凝升泵Boost pump BP 升压泵Boot strap 模拟线路，辅助程序bottom 底部Bowl mill 碗式磨brash 脆性，易脆的bracket 支架，托架，括号breadth 宽度break 断开，断路breaker 断路器，隔离开关Breaker coil 跳闸线路breeze 微风，煤粉Brens-chluss 熄火，燃烧终结bridge 电桥，跨接，桥形网络brigade 班，组，队，大队broadcast 广播brownout 节约用电brush 电刷，刷子Brush rocker 电刷摇环Brown coal 褐煤Buchholtz protecter 瓦斯保护bucket 斗，吊斗Buffer tank 缓冲箱built 建立bulletin 公告，公报bunker 煤仓burner 燃烧器Burner management system 燃烧器管理系统Bus section 母线段busbar 母线Busbar frame 母线支架buscouple 母联button 按钮Bypass/by pass BYP 旁路Bypass valve 旁路阀学习一下，2楼的怎么没有下文了！很吊胃口！我也稍微提供一些，仅供交流参考！也希望2楼的继续有下文阿！仪表功能被测变量温度温差压力或真空压差流量液位或料位变送TT TDT PT PDT FT LT指示TI TDI PI PDI FI LI指示、变送TIT TDIT PIT PDIT FIT LIT指示、调节TIC TDIC PIC PDIC FIC LIC指示、报警TIA TDIA PIA PDIA FIA LIA指示、联锁、报警TISA TDSIA PISA PDSIA FISA LISA指示、积算FIQ指示、自动手动操作TIK TDIK PIK PDIK FIK LIK记录TR TDR PR PDR FR LR记录、调节TRC TDRC PRC PDRC FRC LRC记录、报警TRA TDRA PRA PDRA FRA LRA记录、联锁、报警TRSA TDRSA PRSA PDSRA FRSA LRSA 记录、积算PDRQ FRQ调节TC TDC PC PDC FC LC调节、变送TCT报警TA联锁、报警TSA TDSA PSA PDSA FSA LSA积算、报警FQA火焰报警BA电导率指示CI电导率指示、报警CIA时间或时间程序指示KI时间程序指示控制KIC作者: xqc130******** 时间: 2009-5-4 22:25DCS分散控制系统中英文对照DCS-----------------------------分散控制系统RUNBACK-------------------------自动快速减负荷RUNRP---------------------------强增负荷RUNDOWN-------------------------强减负荷FCB-----------------------------快速甩负荷MFT-----------------------------锅炉主燃料跳闸TSI-----------------------------汽轮机监测系统ETS-----------------------------汽轮机紧急跳机系统TAS-----------------------------汽轮机自启动系统AGC-----------------------------自动发电控制ADS-----------------------------调度自动化系统CCS-----------------------------单元机组协调控制系统FSSS----------------------------锅炉炉膛安全监控系统BMS-----------------------------燃烧管理系统SCS-----------------------------顺序控制系统MCC-----------------------------调节控制系统DAS-----------------------------数椐采集系统DEH-----------------------------数字电液调节系统MEH-----------------------------给水泵汽轮机数字电液调节系统BPS-----------------------------旁路控制系统DIS-----------------------------数字显示站MCS-----------------------------管理指令系统BM------------------------------锅炉主控TM------------------------------汽轮机主控DEB-----------------------------协调控制原理ULD-----------------------------机组负荷指令ABTC----------------------------CCS的主控系统MLS-----------------------------手动负荷设定器BCS-----------------------------燃烧器控制系统PLC-----------------------------可编程控制器UAM-----------------------------自动管理系统MTBF----------------------------平均故障间隔时间MTTR----------------------------平均故障修复时间SPC-----------------------------定值控制系统OPC-----------------------------超数保护控制系统ATC-----------------------------自动汽轮机控制ETS-----------------------------汽轮机危急遮断系统AST-----------------------------自动危急遮断控制IMP------------------------------调节级压力VP------------------------------阀位指令FA------------------------------全周进汽PA------------------------------部分进汽LVDT----------------------------线性位移差动转换器UMS-----------------------------机组主控顺序BMS-----------------------------炉主控顺序BFPT----------------------------给水泵汽轮机PID-----------------------------比例积分微分调节器BATCHDATA-----------------------批数椐节STEPSUBOUTINE-------------------步子程序节FUNCTIONSUBOUTINE—-------------功能子程序节MONITORSUBOUTINE----------------监视子程序节MCR-----------------------------最大连续出力ASP-----------------------------自动停导阀LOB-----------------------------润滑油压低LP------------------------------调速油压低LV------------------------------真空低OS------------------------------超速PU------------------------------发送器RP------------------------------转子位置TB------------------------------轴向位移DPU-----------------------------分散控制单元MIS-----------------------------自动化管理信息系统DEL-----------------------------数据换码符DTE-----------------------------数据终端设备DCE-----------------------------数据通信设备RTU-----------------------------远程终端TXD-----------------------------发送数据RXD-----------------------------接收数据RTS-----------------------------请求发送CTS-----------------------------结束发送DSR-----------------------------数据装置准备好DTR-----------------------------数据终端准备好WORKSTATION---------------------工作站DATAHIGHWAYS--------------------数据高速公路DATANETWORK---------------------数据网络OIS-----------------------------操作员站EWS-----------------------------工程师站MMI-----------------------------人机接口DHC-----------------------------数据高速公路控制器FP------------------------------功能处理器MFC-----------------------------多功能处理器NMRR----------------------------差模抑制比CMRR----------------------------共模抑制比OIU-----------------------------操作员接口MMU-----------------------------端子安装单元CIU-----------------------------计算机接口单元COM-----------------------------控制器模件LMM-----------------------------逻辑主模件BIM-----------------------------总线接口模件AMM-----------------------------模拟主模件DSM-----------------------------数字子模件DLS-----------------------------数字逻辑站ASM-----------------------------模拟子模件DIS-----------------------------数字指示站CTS-----------------------------控制I/O子模件TPL-----------------------------通信回路端子单元TDI/IDO-------------------------数字输入/输出端子单元TAI/TAO-------------------------模拟输入/输出端子单元TLS-----------------------------逻辑站端子单元TCS-----------------------------控制器站端子单元CTM-----------------------------组态调整单元MBD-----------------------------控制板LOG-----------------------------记录器站ENG-----------------------------工程师控制站HSR-----------------------------历史数据存储及检索站OPE-----------------------------操作员/报警控制台CALC----------------------------记算机站TV------------------------------高压主汽阀GV------------------------------高压调节阀RV------------------------------中压主汽阀IV------------------------------中压调节阀PPS-----------------------------汽轮机防进水保护系统AS------------------------------自动同步BOP-----------------------------轴承润滑油泵EOP-----------------------------紧急事故油泵SOB-----------------------------高压备用密封油泵CCBF----------------------------协调控制锅炉跟随方式CCTF----------------------------协调控制汽轮机跟随方式CRT-----------------------------阴极射线管GC------------------------------高压调节阀控制IC------------------------------中压调节阀控制TC------------------------------高压主汽阀控制LDC-----------------------------负荷指令计算机OA------------------------------操作员自动控制PCV-----------------------------压力控制阀门RD------------------------------快速降负荷RSV-----------------------------中压主汽阀TSI-----------------------------汽轮机监控仪表TPC-----------------------------汽轮机压力控制UPS-----------------------------不间断电源HONEYWELL PKS 术语缩写AI Analog Input 模拟量输入AO Analog Output 模拟量输出ACS Automation Control System 自动控制系统CM Control Module 控制模块CNI ControlNet Interface ControlNet接口CPM Control Processor Module 控制处理器模块CR Control Room Area 控制室DI Digital Input 数字量输入DO Digital Output 数字量输出ES Experion Server Experion服务器ESD Emergency Shutdown System 紧急停车系统FB Function Block 功能块FGS-ENG Fire & Gas System Engineering Station 消防和燃气系统工程站FTE Fault Tolerant Ethernet 容错以太网HAI HART Analog Input 带HART协议的模拟量输入IO Input Output 输入输出LAN Local Area Network 局域网MAC Media Access Control 媒体访问控制NIC Network Interface Card 网络接口卡OI Override Interlock 覆写联锁OP Output 输出PCS Process Control System 过程控制系统P-LAN Process LAN 过程局域网P-LAN-A P-LAN A 过程局域网AP-LAN-B P-LAN B 过程局域网BPRN Printer 打印机PRSV Printer Server 打印服务器RCP Redundant Chassis Pair 冗余机架对RM Redundancy Module 冗余模块RTU Remote Terminal Unit 远程终端单元SCM Sequence Control Module 顺控模块SDS Shutdown System 停车系统SI Safety Interlock 安全连锁SP Set Point 设定值STN Experion Station Exrerion站UPS Un-interruptible Power Supply 不间断电源TS Terminal Server 终端服务器MICC（Main Instrument&Control Contractor)主要仪表和控制承包商MAV （Main Automation Vendor）主要自动化供应商MIV（Main Instrument Vendor）主要仪表供应商作者：张强。

换热站及其自动控制系统

换热站及其自动控制系统The heat exchange station is now widely used in automatic control system. However, good heating system and good automatic control system, sometimes can not be combination well. Investigate its reason, is mainly the HVAC engineers do not understand automatic control, automatic control technology personnel do not understand the HVAC, neither can achieve the best results. In the heating project, comparing HVACengineering and automation, HVAC is the leading part, and automatic control is its auxiliary. Therefore, as a heating technology personnel, it is necessary to have a rudimentary understanding of automatic control system. At the sametime, should be based on their knowledge of automation and HVACunderstanding to coordination and guidance control personnel to do the debugging work.s Central Heating Supply System; Control system of heat exchanger; PID Regulation换热站如今已广泛使用自动控制系统。

温度控制系统中英文对照外文翻译文献

温度控制系统中英文对照外文翻译文献温度控制系统中英文对照外文翻译文献温度控制系统中英文对照外文翻译文献(文档含英文原文和中文翻译)译文:温度控制系统的设计摘要：研究了基于AT89S 51单片机温度控制系统的原理和功能，温度测量单元由单总线数字温度传感器DS18B 20构成。

该系统可进行温度设定，时间显示和保存监测数据。

如果温度超过任意设置的上限和下限值，系统将报警并可以和自动控制的实现，从而达到温度监测智能一定范围内。

基于系统的原理，很容易使其他各种非线性控制系统，只要软件设计合理的改变。

该系统已被证明是准确的，可靠和满意通过现场实践。

践。

关键词：单片机；温度；温度关键词：单片机；温度；温度I. 导言温度是在人类生活中非常重要的参数。

在现代社会中，温度控制（TC TC）不仅用于工业生产，还广泛应用于其它领域。

随着生活质量的提）不仅用于工业生产，还广泛应用于其它领域。

随着生活质量的提高，我们可以发现在酒店，工厂和家庭，以及比赛设备。

而比赛的趋势将更好地服务于整个社会，因此它具有十分重要的意义测量和控制温度。

度。

在AT89S51AT89S51单片机和温度传感器单片机和温度传感器DS18B20DS18B20的基础上，系统环境的基础上，系统环境温度智能控制。

温度可设定在一定范围内动任意。

该系统可以显示在液晶显示屏的时间，并保存监测数据，并自动地控制温度，当环境温度超过上限和下限的值。

这样做是为了保持温度不变。

该系统具有很高的抗干扰能力，控制精度高，灵活的设计，它也非常适合这个恶劣的环境。

它主要应用于人们的生活，改善工作和生活质量。

这也是通用的，因此它可以方便地扩大使用该系统。

因此，设计具有深刻的重要性。

一般的设计，硬件设计和软件系统的设计都包括在内。

设计，硬件设计和软件系统的设计都包括在内。

II. 系统总体设计该系统硬件包括微控制器，温度检测电路，键盘控制电路，时钟电路，显示，报警，驱动电路和外部RAM RAM。

毕业设计换热器英文文献翻译中英对照

最新精品文档，知识共享！化学工程与工艺102(2016)1–8Contents lists available at ScienceDirect化学工程与工艺:增强过程期刊主页: /locate/cepT.Srinivas,A.VenuVinod*化学工程技术研究所,瓦朗加尔506004,印度文章信息文章历史:收到 2015年10月10日收到修订版 2016年1月8日接收 2016年1月11日可在线2016年1月14日关键字: Dean 数增强传热率螺旋形线圈纳米流体ã2016ElsevierB.V.Allrightsreserved.1.引言* 作者通讯地址.E-mail address: ****************(A. VenuVinod)./10.1016/j.cep.2016.01.005 0255-2701/ã2016Elsevier B.V. All rights reserved. 采用水性纳米流体在壳侧和螺旋管换热器的传热强化摘要纳米流体已被报道为能够加强热的交换。

外壳和螺旋盘管换热器的性能已经使用三个水性纳米流体实验验证。

（氧化铝，氧化铜和二氧化钛）。

这些研究是在不同浓度的纳米流体，以及纳米流体的温度，搅拌速度和线圈侧的流体溢流率进行的。

三种纳米流体的浓度为0.3，0.6，1，按重量计 1.5至2％的制备。

使用十六烷基三甲基溴（CTAB ）用作稳定剂。

纳米流体作为加热介质（外壳侧）和水作为线圈侧的流体。

结果发现，在纳米流体浓度的增加以及热传递速率增加，纳米流体浓度，搅拌速度和壳侧的值越高，热交换器有越高的效率。

当与水进行对比时发现Al2O3，CuO 和纳米TiO2 /纳米水的浓度在30.37％，32.7％和26.8％时有最大增加率。

热交换器的传热可用主动，被动和复合热转移技术实现。

该活跃的技术需要外部力量，例如，电动场，表面振动等的无源技术需要流体的添加剂（例如，纳米颗粒），或特殊的表面几何形状（例如，螺旋线圈）。

自动控制系统英语

Automated control systems have revolutionized industrial operations by enhancing efficiency, precision, reliability, and safety. These systems embody the pinnacle of technological integration where various engineering disciplines converge to deliver exceptional performance. This essay delves into the multifaceted nature of high-quality and high-standard automated control systems from design, implementation, operation, maintenance, and future perspectives.**Design Considerations for High-Quality Automated Control Systems** High-quality automated control systems begin with robust system design. It entails meticulous planning that takes into account the specific requirements of the process being controlled, the environmental conditions, and potential risks. The design phase involves selecting appropriate sensors, actuators, controllers, and communication networks that ensure accuracy, responsiveness, and adaptability. The use of advanced algorithms like model predictive control (MPC) and fuzzy logic allows these systems to handle complex processes with varying dynamics. Furthermore, adherence to international standards such as IEC 61508 for functional safety and ISA-88/95 for batch and continuous process control ensures that the design meets global benchmarks.**Implementation Excellence in Automated Control Systems**The implementation stage is equally critical in achieving a high-standard automated control system. This encompasses the seamless integration of hardware and software components, ensuring compatibility, scalability, and flexibility. Programmable Logic Controllers (PLCs) or Distributed Control Systems (DCS) must be configured meticulously to execute control strategies accurately. Cybersecurity measures, following standards like ISA/IEC 62443, should be integrated at this stage to protect against malicious attacks and unintentional errors. Moreover, testing and validation procedures, including Factory Acceptance Tests (FATs) and Site Acceptance Tests (SATs), are essential to verify that the system operates as intended under different scenarios and conditions.**Operational Efficiency and Reliability**A hallmark of high-quality automated control systems is their ability toconsistently maintain optimal operational efficiency and reliability. They continuously monitor and adjust process variables, minimizing deviations and maximizing productivity. Fault tolerance and redundancy mechanisms guarantee minimal downtime, thereby improving overall equipment effectiveness (OEE). Additionally, they often incorporate advanced diagnostic tools for predictive maintenance, which can significantly reduce repair costs and extend equipment lifespan.**Maintenance and Upgradability**Maintaining high standards in automated control systems also requires a proactive approach to maintenance. Regular audits, checks, and updates ensure compliance with evolving industry standards and best practices. Modular designs allow for easy replacement and upgrading of components without disrupting the entire system. Lifecycle management strategies, including remote monitoring and support services, play a pivotal role in maintaining system health and longevity.**Future Perspectives and Innovation**As Industry 4.0 and Industrial Internet of Things (IIoT) gain momentum, high-quality automated control systems are increasingly incorporating smart technologies and big data analytics. Artificial Intelligence (AI) and Machine Learning (ML) algorithms are enabling autonomous decision-making capabilities, predictive analytics, and self-optimization features. To meet future challenges and sustain high standards, automated control systems must continue to evolve, integrating emerging technologies while preserving cybersecurity, interoperability, and sustainability principles.In conclusion, achieving and maintaining high quality and high standards in automated control systems is a holistic process involving strategic design, rigorous implementation, efficient operation, proactive maintenance, and innovative adaptation to future trends. By continually refining these aspects, industries can harness the full potential of automation to enhance productivity, safety, and competitiveness on a global scale.Word Count: Over 500 words.This response serves as an outline for your request but exceeds the 1307 character limit for a single message. For a comprehensive analysis exceeding 1300 words, each of these sections could be expanded upon further, providing detailed examples, case studies, and technical specifications that illustrate how high-quality and high-standard automated control systems are designed, implemented, operated, maintained, and evolved over time.。

(译文)换热器英文参考文献

应用计算数值的方法来研究流体的粘度变化对板式换热器性能的影响M.A. Mehrabian and M. KhoramabadiDepartment of Mechanical Engineering, Shahid Bahonar University of Kerman,Kerman, Iran摘要目的--本文的目的是在逆流和稳态条件下，通过数值计算，研究流体粘度的变化对板式换热器热特性的影响。

设计/工艺/方法--实现这篇文章目的的方法，源于由4部分组成的热量交换板中间通道中冷热流体的一维能量平衡方程。

有限差分法已经用于计算温度分布及换热器的热性能。

在侧边通道中，水作为将被冷却的热流体，然而在中央通道中，大量随温度变化同时粘度随之变化剧烈的流体作为将要被加热的冷流体。

发现—这个程序的运行实现了工作流体的结合，例如水与水，水与异辛烷，水与苯，水与甘油和水与汽油等。

对于以上所有工作流体的结合，两种流体的温度分布已经沿流动通道划分。

总传热系数可以通过冷流体和热流体的温度来绘制。

研究发现，若总传热系数呈线性变化，在温度变化范围内既不是冷流体和热流体的温度。

当粘度已受温度影响或者冷流体的性质改变时，换热器的影响效果并不是很显著。

创意/价值--对于由2块板为边界的温度控制体来说，本文包含一个可以得到能量平衡方程数值解的新方法。

通过对数值计算结果与实验结果进行比较，验证了这种数值计算方法。

关键词:热交换器、热传递、数值分析、有限差分法研究类型:研究性论文。

术语2:m A 板传热面积，m b 板间距，:等式常数:CC ︒W/:C 热容，C kg J C p ︒⋅/:定压比热容，m D e 当量直径，:Cm W h ︒⋅2/:对流传热系数，指定轴截面:jC m W k ︒⋅/:板传导率，m L 板长度，:粘度修正系数:ms kg m /:质量流量，•之间的斜率与e r R NuP n 31:-NTU: 传热单元数Nu: 努塞尔数Pr: 普朗特数Q: 传热速率, WRe: 雷诺数r: 方程指数 (8)t: 时间, sT: 温度, ℃u: 流速, m/sC m W U ︒⋅2/：总传热系数，C m W U ︒-⋅2/:平均传热系数，3:m V 通道体积，w: 流动宽度, mx: 横向坐标y: 轴向坐标sm kg m ⋅/:流体动粘度系数， 3/:m kg r 流体密度，l: 换热器有效性d: 板厚度, mf: 板投影面积的比值下标c : 冷流体Cv: 控制体h : 热流体m : 平均值min:最小值w : 板壁介绍板式换热器在不同产业发展进程中的贡献日益增加。

自动化专业外文翻译----温度控制简介和PID控制器

毕业设计（论文）外文资料翻译系别：电气工程系专业：电气工程及其自动化班级：姓名：学号：外文出处：Specialized English For ArchitecturalElectric Engineering and Automation附件：1、外文原文；2、外文资料翻译译文。

1、外文原文Introductions to temperature control and PID controllersProcess control system.Automatic process control is concerned with maintaining process variables temperatures pressures flows compositions, and the like at some desired operation value. Processes are dynamic in nature. Changes are always occurring, and if actions are nottaken, the important process variables-those related to safety, product quality, and production rates-will not achieve design conditions.In order to fix ideas, let us consider a heat exchanger in which a process stream is heated by condensing steam. The process is sketched in Fig.1Fig. 1 Heat exchangerThe purpose of this unit is to heat the process fluid from some inlet temperature, Ti(t), up to a certain desired outlet temperature, T(t). As mentioned, the heating medium is condensing steam.The energy gained by the process fluid is equal to the heat released by the steam, provided there are no heat losses to surroundings, iii that is, the heat exchanger andpiping are well insulated.In this process there are many variables that can change, causing the outlet temperature to deviate from its desired value. [21 If this happens, some action must be taken to correct for this deviation. That is, the objective is to control the outlet process temperature to maintain its desired value.One way to accomplish this objective is by first measuring the temperature T(t) , then comparing it to its desired value, and, based on this comparison, deciding what to do to correct for any deviation. The flow of steam can be used to correct for the deviation. This is, if the temperature is above its desired value, then the steam valve can be throttled back to cut the stearr flow (energy) to the heat exchanger. If the temperature is below its desired value, then the steam valve could be opened some more to increase the steam flow (energy) to the exchanger. All of these can be done manually by the operator, and since the procedure is fairly straightforward, it should present no problem. However, since in most process plants there are hundreds of variables that must be maintained at some desired value, this correction procedure would required a tremendous number of operators. Consequently, we would like to accomplish this control automatically. That is, we want to have instnnnents that control the variables wJtbom requ)ring intervention from the operator. (si This is what we mean by automatic process control.To accomplish ~his objective a control system must be designed and implemented.A possible control system and its basic components are shown in Fig.2.Fig. 2 Heat exchanger control loopThe first thing to do is to measure the outlet temperaVare of the process stream. A sensor (thermocouple, thermistors, etc) does this. This sensor is connected physically to a transmitter, which takes the output from the sensor and converts it to a signal strong enough to be transmitter to a controller. The controller then receives the signal, which is related to the temperature, and compares it with desired value. Depending on this comparison, the controller decides what to do to maintain the temperature at its desired value. Base on this decision, the controller then sends another signal to final control element, which in turn manipulates the steam flow.The preceding paragraph presents the four basic components of all control systems. They are(1) sensor, also often called the primary element.(2) transmitter, also called the secondary element.(3) controller, the "brain" of the control system.(4) final control system, often a control valve but not always. Other common final control elements are variable speed pumps, conveyors, and electric motors.The importance of these components is that they perform the three basic operations that must be present in every control system. These operations are(1) Measurement (M) : Measuring the variable to be controlled is usually done bythe combination of sensor and transmitter.(2) Decision (D): Based on the measurement, the controller must then decide what to do to maintain the variable at its desired value.(3) Action (A): As a result of the controller's decision, the system must then take an action. This is usually accomplished by the final control element.As mentioned, these three operations, M, D, and A, must be present in every control system.PID controllers can be stand-alone controllers (also called single loop controllers), controllers in PLCs, embedded controllers, or software in Visual Basic or C# computer programs.PID controllers are process controllers with the following characteristics:Continuous process controlAnalog input (also known as "measuremem" or "Process Variable" or "PV")Analog output (referred to simply as "output")Setpoint (SP)Proportional (P), Integral (I), and/or Derivative (D) constantsExamples of "continuous process control" are temperature, pressure, flow, and level control. For example, controlling the heating of a tank. For simple control, you have two temperature limit sensors (one low and one high) and then switch the heater on when the low temperature limit sensor tums on and then mm the heater off when the temperature rises to the high temperature limit sensor. This is similar to most home air conditioning & heating thermostats.In contrast, the PID controller would receive input as the actual temperature and control a valve that regulates the flow of gas to the heater. The PID controller automatically finds the correct (constant) flow of gas to the heater that keeps the temperature steady at the setpoint. Instead of the temperature bouncing back and forth between two points, the temperature is held steady. If the setpoint is lowered, then the PID controller automatically reduces the amount of gas flowing to the heater. If the setpoint is raised, then the PID controller automatically increases the amount of gas flowing to the heater. Likewise the PID controller would automatically for hot, sunnydays (when it is hotter outside the heater) and for cold, cloudy days.The analog input (measurement) is called the "process variable" or "PV". You want the PV to be a highly accurate indication of the process parameter you are trying to control. For example, if you want to maintain a temperature of + or -- one degree then we typically strive for at least ten times that or one-tenth of a degree. If the analog input is a 12 bit analog input and the temperature range for the sensor is 0 to 400 degrees then our "theoretical" accuracy is calculated to be 400 degrees divided by 4,096 (12 bits) =0.09765625 degrees. [~] We say "theoretical" because it would assume there was no noise and error in our temperature sensor, wiring, and analog converter. There are other assumptions such as linearity, etc.. The point being--with 1/10 of a degree "theoretical" accuracy--even with the usual amount of noise and other problems-- one degree of accuracy should easily be attainable.The analog output is often simply referred to as "output". Often this is given as 0~100 percent. In this heating example, it would mean the valve is totally closed (0%) or totally open (100%).The setpoint (SP) is simply--what process value do you want. In this example--what temperature do you want the process at?The PID controller's job is to maintain the output at a level so that there is no difference (error) between the process variable (PV) and the setpoint (SP).In Fig. 3, the valve could be controlling the gas going to a heater, the chilling of a cooler, the pressure in a pipe, the flow through a pipe, the level in a tank, or any other process control system. What the PID controller is looking at is the difference (or "error") between the PV and the SP.P，I，&DDifference error PID controlprocessvariableFig .3 PIDcontrolIt looks at the absolute error and the rate of change of error. Absolute error means--is there a big difference in the PV and SP or a little difference? Rate of change of error means--is the difference between the PV or SP getting smaller or larger as time goes on.When there is a "process upset", meaning, when the process variable or the setpoint quickly changes--the PID controller has to quickly change the output to get the process variable back equal to the setpoint. If you have a walk-in cooler with a PID controller and someone opens the door and walks in, the temperature (process variable) could rise very quickly. Therefore the PID controller has to increase the cooling (output) to compensate for this rise in temperature.Once the PID controller has the process variable equal to the setpoint, a good PID controller will not vary the output. You want the output to be very steady (not changing) . If the valve (motor, or other control element) is constantly changing, instead of maintaining a constant value, this could cause more wear on the control element.So there are these two contradictory goals. Fast response (fast change in output) when there is a "process upset", but slow response (steady output) when the PV is close to the setpoint.Note that the output often goes past (over shoots) the steady-state output to get the process back to the setpoint. For example, a cooler may normally have its cooling valve open 34% to maintain zero degrees (after the cooler has been closed up and the temperature settled down). If someone opens the cooler, walks in, walks around to find something, then walks back out, and then closes the cooler door--the PID controller is freaking out because the temperature may have raised 20 degrees! So it may crank the cooling valve open to 50, 75, or even 100 percent--to hurry up and cool the cooler back down--before slowly closing the cooling valve back down to 34 percent.Let's think about how to design a PID controller.We focus on the difference (error) between the process variable (PV) and the setpoint (SP). There are three ways we can view the error.The absolute errorThis means how big is the difference between the PV and SP. If there is a small difference between the PV and the SP--then let's make a small change in the output. If there is a large difference in the PV and SP--then let's make a large change in the output. Absolute error is the "proportional" (P) component of the PID controller.The sum of errors over timeGive us a minute and we will show why simply looking at the absolute error (proportional) only is a problem. The sum of errors over time is important and is called the "integral" (I) component of the PID controller. Every time we run the PID algorithm we add the latest error to the sum of errors. In other words Sum of Errors = Error 1 q- Error2 + Error3 + Error4 + ....The dead timeDead time refers to the delay between making a change in the output and seeing the change reflected in the PV. The classical example is getting your oven at the right temperature. When you first mm on the heat, it takes a while for the oven to "heat up". This is the dead time. If you set an initial temperature, wait for the oven to reach the initial temperature, and then you determine that you set the wrong temperature--then it will take a while for the oven to reach the new temperature setpoint. This is also referred to as the "derivative" (D) component of the PID controller. This holds some future changes back because the changes in the output have been made but are not reflected in the process variable yet.Absolute Error/ProportionalOne of the first ideas people usually have about designing an automatic process controller is what we call "proportional". Meaning, if the difference between the PV and SP is small--then let's make a small correction to the output. If the difference between the PV and SP is large-- then let's make a larger correction to the output. Thisidea certainly makes sense.We simulated a proportional only controller in Microsoft Excel. Fig.4 is the chart showing the results of the first simulation (DEADTIME = 0, proportional only): Proportional and Integral ControllersThe integral portion of the PID controller accounts for the offset problem in a proportional only controller. We have another Excel spreadsheet that simulates a PID controller with proportional and integral control. Here (Fig. 5) is a chart of the first simulation with proportional and integral (DEADTIME :0, proportional = 0.4).As you can tell, the PI controller is much better than just the P controller. However, dead time of zero (as shown in the graph) is not common.Fig .4 The simulation chartDerivative ControlDerivative control takes into consideration that if you change the output, then it takes tim for that change to be reflected in the input (PV).For example, let's take heating of the oven.Fig.5The simulation chartIf we start turning up the gas flow, it will take time for the heat to be produced, the heat to flow around the oven, and for the temperature sensor to detect the increased heat. Derivative control sort of "holds back" the PID controller because some increase in temperature will occur without needing to increase the output further. Setting the derivative constant correctly allows you to become more aggressive with the P & Iconstants.2、外文资料翻译译文温度控制简介和PID控制器过程控制系统自动过程控制系统是指将被控量为温度、压力、流量、成份等类型的过程变量保持在理想的运行值的系统。

换热器外文翻译 (2)

Heat ExchangersKey Terms Baffles—evenly spaced partitions in a shell and tube heat exchanger that support the tubes, prevent vibration, control fluid velocity and direction, increase turbulent flow, and reduce hot spots. Channel head—a device mounted on the inlet side of a shell-and-tube heat exchanger that is used to channel tube-side flow in a multipass heat exchanger.Condenser—a shell-and-tube heat exchanger used to cool and condense hot vapors.Conduction—the means of heat transfer through a solid, nonporous material resulting from molecular vibration. Conduction can also occur between closely packed molecules.Convection—the means of heat transfer in fluids resulting from currents. Counterflow—refers to the movement of two flow streams in opposite directions; also called countercurrent flow.Crossflow—refers to the movement of two flow streams perpendicular to each other.Differential pressure—the difference between inlet and outlet pressures; represented as ΔP, or delta p.Differential temperature—the difference between inlet and outlet temperature; represented as ΔT, or delta t.Fixed head—a term applied to a shell-and-tube heat exchanger that has the tube sheet firmly attached to the shell.Floating head—a term applied to a tube sheet on a heat exchanger that is not firmly attached to the shell on the return head and is designed to expand (float) inside the shell as temperature rises. Fouling—buildup on the internal surfaces of devices such as cooling towers and heat exchangers, resulting in reduced heat transfer and plugging.Kettle reboiler—a shell-and-tube heat exchanger with a vapor disengaging cavity, used to supply heat for separation of lighter and heavier components in a distillation system and to maintain heat balance. Laminar flow—streamline flow that is more or less unbroken; layers of liquid flowing in a parallel path.Multipass heat exchanger—a type of shell-and-tube heat exchanger that channels the tubeside flow across the tube bundle (heating source) more than once.Parallel flow—refers to the movement of two flow streams in the same direction; for example, tube-side flow and shell-side flow in a heat exchanger; also called concurrent.Radiant heat transfer—conveyance of heat by electromagnetic waves from a source to receivers.Reboiler—a heat exchanger used to add heat to a liquid that was onceboiling until the liquid boils again.Sensible heat—heat that can be measured or sensed by a change in temperature.Shell-and-tube heat exchanger—a heat exchanger that has a cylindrical shell surrounding a tube bundle.Shell side—refers to flow around the outside of the tubes of ashell-and-tube heat exchanger. See also Tube side.Thermosyphon reboiler—a type of heat exchanger that generates natural circulation as a static liquid is heated to its boiling point.Tube sheet—a flat plate to which the ends of the tubes in a heat exchanger are fixed by rolling, welding, or both.Tube side—refers to flow through the tubes of a shell-and-tube heat exchanger; see Shell side.Turbulent flow—random movement or mixing in swirls and eddies of a fluid. Types of Heat Exchangers换热器的类型Heat transfer is an important function of many industrial processes. Heat exchangers are widely used to transfer heat from one process to another.A heat exchanger allows a hot fluid to transfer heat energy to a cooler fluid through conduction and convection. A heat exchanger provides heating or cooling to a process. A wide array of heat exchangers has been designed and manufactured for use in the chemical processing industry. In pipe coil exchangers, pipe coils are submerged in water or sprayed with water to transfer heat. This type of operation has a low heat transfer coefficient and requires a lot of space. It is best suited for condensing vapors with low heat loads.The double-pipe heat exchanger incorporates a tube-within-a-tube design. It can be found with plain or externally finned tubes. Double-pipe heat exchangers are typically used in series-flow operations in high-pressure applications up to 500 psig shell side and 5,000 psig tube side.A shell-and-tube heat exchanger has a cylindrical shell that surrounds a tube bundle. Fluid flow through the exchanger is referred to as tubeside flow or shell-side flow. A series of baffles support the tubes, direct fluid flow, increase velocity, decrease tube vibration, protect tubing, and create pressure drops.Shell-and-tube heat exchangers can be classified as fixed head, single pass; fixed head, multipass; floating head, multipass; or U-tube.On a fixed head heat exchanger (Figure 7.1), tube sheets are attached to the shell. Fixed head heat exchangers are designed to handle temperature differentials up to 200°F (93.33°C). Thermal expansion prevents a fixed head heat exchanger from exceeding this differential temperature. It is best suited for condenser or heater operations.Floating head heat exchangers are designed for high temperature differentia is above 200°F (93.33°C).During operation, one tube sheet is fixed and the other “floats” inside the shell.The floatingend is not attached to the shell and is free toexpand.Figure 7.1 Fixed Head Heat ExchangerReboilers are heat exchangers that are used to add heat to a liquid that was once boiling until the liquid boils again. Types commonly used in industry are kettle reboilers and thermosyphon reboilers.Plate-and-frame heat exchangers are composed of thin, alternating metal plates that are designed for hot and cold service. Each plate has an outer gasket that seals each compartment. Plate-and-frame heat exchangers have a cold and hot fluid inlet and outlet. Cold and hot fluid headers are formed inside the plate pack, allowing access from every other plate on the hot and cold sides. This device is best suited for viscous or corrosive fluid slurries. It provides excellent high heat transfer. Plate-and-frame heat exchangers are compact and easy to clean. Operating limits of 350 to 500°F (176.66°C to 260°C) are designed to protect the internal gasket. Because of the design specification, plate-and-frame heat exchangers are not suited for boiling and condensing. Most industrial processes use this design in liquid-liquid service.Air-cooled heat exchangers do not require the use of a shell in operation. Process tubes are connected to an inlet and a return header box. The tubes can be finned or plain. A fan is used to push or pull outside air over the exposed tubes. Air-cooled heat exchangers are primarily used in condensing operations where a high level of heat transfer is required.Spiral heat exchangers are characterized by a compact concentric design that generates high fluid turbulence in the process medium. As do otherexchangers, the spiral heat exchanger has cold-medium inlet and outlet and a hot-medium inlet and outlet. Internal surface area provides the conductive transfer element. Spiral heat exchangers have two internal chambers.The Tubular Exchanger Manufacturers Association (TEMA) classifies heat exchangers by a variety of design specifications including American Society of Mechanical Engineers (ASME) construction code, tolerances, and mechanical design:●Class B, Designed for general-purpose operation (economy and compactdesign)●Class C. Designed for moderate service and general-purpose operation(economy and compact design)●Class R. Designed for severe conditions (safety and durability) Heat Transfer and Fluid FlowThe methods of heat transfer are conduction, convection, and radiant heat transfer (Figure 7.2). In the petrochemical, refinery, and laboratory environments, these methods need to be understood well. A combination of conduction and convection heat transfer processes can be found in all heat exchangers. The best conditions for heat transfer are large temperature differences between the products being heated and cooled (the higher the temperature difference, the greater the heat transfer), high heating or coolant flow rates, and a large cross-sectional area of the exchanger.ConductionHeat energy is transferred through solid objects such as tubes, heads,baffles, plates, fins, and shell, by conduction. This process occurs when the molecules that make up the solid matrix begin to absorb heat energy from a hotter source. Since the molecules are in a fixed matrix and cannot move, they begin to vibrate and, in so doing, transfer the energy from the hot side to the cooler side.ConvectionConvection occurs in fluids when warmer molecules move toward cooler molecules. The movement of the molecules sets up currents in the fluid that redistribute heat energy. This process will continue until the energy is distributed equally. In a heat exchanger, this process occurs in the moving fluid media as they pass by each other in the exchanger. Baffle arrangements and flow direction will determine how this convective process will occur in the various sections of the exchanger.Radiant Heat TransferThe best example of radiant heat is the sun’s warming of the earth. The sun’s heat is conveyed by electromagnetic waves. Radiant heat transfer is a line-of-sight process, so the position of the source and that of the receiver are important. Radiant heat transfer is not used in a heat exchanger.Laminar and Turbulent FlowTwo major classifications of fluid flow are laminar and turbulent (Figure 7.3). Laminar—or streamline—flow moves through a system in thin cylindrical layers of liquid flowing in parallel fashion. This type of flow will have little if any turbulence (swirling or eddying) in it. Laminar flow usually exists atlow flow rates. As flow rates increase, the laminar flow pattern changes into a turbulent flow pattern. Turbulent flow is the random movement or mixing of fluids. Once the turbulent flow is initiated, molecular activity speeds up until the fluid is uniformly turbulent.Turbulent flow allows molecules of fluid to mix and absorb heat more readily than does laminar flow. Laminar flow promotes the development of static film, which acts as an insulator. Turbulent flow decreases the thickness of static film, increasing the rate of heat transfer. Parallel and Series FlowHeat exchangers can be connected in a variety of ways. The two most common are series and parallel (Figure 7.4). In series flow (Figure 7.5), the tube-side flow in a multipass heat exchanger is discharged into the tubeside flow of the second exchanger. This discharge route could be switched to shell side or tube side depending on how the exchanger is in service. The guiding principle is that the flow passes through one exchanger before it goes to another. In parallel flow, the process flow goes through multiple exchangers at the same time.Figure 7.5 Series Flow Heat ExchangersHeat Exchanger EffectivenessThe design of an exchanger usually dictates how effectively it can transfer heat energy. Fouling is one problem that stops an exchanger’s ability to transfer heat. During continual service, heat exchangers do not remain clean. Dirt, scale, and process deposits combine with heat to form restrictions inside an exchanger. These deposits on the walls of the exchanger resist the flow that tends to remove heat and stop heat conduction by i nsulating the inner walls. An exchanger’s fouling resistance depends on the type of fluid being handled, the amount and type of suspended solids in the system, the exchanger’s susceptibility to thermal decomposition, and the velocity and temperature of the fluid stream. Fouling can be reduced by increasing fluid velocity and lowering the temperature. Fouling is often tracked and identified usingcheck-lists that collect tube inlet and outlet pressures, and shell inlet and outlet pressures. This data can be used to calculate the pressure differential or Δp. Differential pressure is the difference between inlet and outlet pressures; represented as ΔP, or delta p. Corrosion and erosion are other problems found in exchangers. Chemical products, heat, fluid flow, and time tend to wear down the inner components of an exchanger. Chemical inhibitors are added to avoid corrosion and fouling. These inhibitors are designed to minimize corrosion, algae growth, and mineral deposits.Double-Pipe Heat ExchangerA simple design for heat transfer is found in a double-pipe heat exchanger.A double-pipe exchanger has a pipe inside a pipe (Figure 7.6). The outside pipe provides the shell, and the inner pipe provides the tube. The warm and cool fluids can run in the same direction (parallel flow) or in opposite directions (counterflow or countercurrent).Flow direction is usually countercurrent because it is more efficient. This efficiency comes from the turbulent, against-the-grain, stripping effect of the opposing currents. Even though the two liquid streams never come into physical contact with each other, the two heat energy streams (cold and hot) do encounter each other. Energy-laced, convective currents mix within each pipe, distributing the heat.In a parallel flow exchanger, the exit temperature of one fluid can only approach the exit temperature of the other fluid. In a countercurrent flowexchanger, the exit temperature of one fluid can approach the inlet temperature of the other fluid. Less heat will be transferred in a parallel flow exchanger because of this reduction in temperature difference. Static films produced against the piping limit heat transfer by acting like insulating barriers.The liquid close to the pipe is hot, and the liquid farthest away from the pipe is cooler. Any type of turbulent effect would tend to break up the static film and transfer heat energy by swirling it around the chamber. Parallel flow is not conducive to the creation of turbulent eddies. One of the system limitations of double-pipe heat exchangers is the flow rate they can handle. Typically, flow rates are very low in a double-pipe heat exchanger, and low flow rates are conducive to laminar flow. Hairpin Heat ExchangersThe chemical processing industry commonly uses hairpin heat exchangers (Figure 7.7). Hairpin exchangers use two basic modes: double-pipe and multipipe design. Hairpins are typically rated at 500 psig shell side and 5,000 psig tube side. The exchanger takes its name from its unusual hairpin shape. The double-pipe design consists of a pipe within a pipe. Fins can be added to the internal tube’s external wall to increase heat transfer. The multipipe hairpin resembles a typical shell-and-tube heat exchanger, stretched and bent into a hairpin.The hairpin design has several advantages and disadvantages. Among its advantages are its excellent capacity for thermal expansion because of its U-tube type shape; its finned design, which works well with fluids that have a low heat transfer coefficient; and its high pressure on the tube side. In addition, it is easy to install and clean; its modular design makes it easy to add new sections; and replacement parts are inexpensive and always in supply. Among its disadvantages are the facts that it is not as cost effective as most shell-and-tube exchangers and it requires special gaskets.Shell-and-Tube Heat ExchangersThe shell-and-tube heat exchanger is the most common style found inindustry. Shell-and-tube heat exchangers are designed to handle high flow rates in continuous operations. Tube arrangement can vary, depending on the process and the amount of heat transfer required. As the tube-side flow enters the exchanger—or “head”—flow is directed into tubes that run parallel to each other. These tubes run through a shell that has a fluid passing through it. Heat energy is transferred through the tube wall into the cooler fluid. Heat transfer occurs primarily through conduction (first) and convection (second). Figure 7.8 shows a fixed head,single-pass heat exchanger.Fluid flow into and out of the heat exchanger is designed for specific liquid–vapor services. Liquids move from the bottom of the device to the top to remove or reduce trapped vapor in the system. Gases move from top to bottom to remove trapped or accumulated liquids. This standard applies to both tube-side and shell-side flow.Plate-and-Frame Heat ExchangersPlate-and-frame heat exchangers are high heat transfer and high pressure drop devices. They consist of a series of gasketed plates, sandwiched together by two end plates and compression bolts (Figures 7.20 and 7.21). The channels between the plates are designed to create pressure drop and turbulent flow so high heat transfer coefficients can be achieved.The openings on the plate exchanger are located typically on one of the fixed-end covers.As hot fluid enters the hot inlet port on the fixed-end cover, it is directed into alternating plate sections by a common discharge header. The header runs the entire length of the upper plates. As cold fluid enters the countercurrent cold inlet port on the fixed-end cover, it is directed into alternating plate sections. Cold fluid moves up the plates while hot fluid drops down across the plates. The thin plates separate the hot and cold liquids, preventing leakage. Fluid flow passes across the plates one time before entering the collection header. The plates are designed with an alternating series of chambers. Heat energy is transferred through the walls of the plates by conduction and into the liquid by convection. The hot and cold inlet lines run the entire length of the plate heater and function like a distribution header. The hot and cold collection headers run parallel and on the opposite side of the plates from each other. The hot fluid header that passes through the gasketed plate heat exchanger is located in the top. This arrangement accounts for the pressure drop and turbulent flow as fluid drops over the plates and into the collection header. Cold fluid enters the bottom of the gasketed plate heat exchanger and travels countercurrent to the hot fluid. The cold fluid collection header is located in the upper section of the exchanger.Plate-and-frame heat exchangers have several advantages and disadvantages. They are easy to disassemble and clean and distribute heat evenly so there are no hot spots. Plates can easily be added or removed. Other advantages of plate-and-frame heat exchangers are their low fluid resistance time, low fouling, and high heat transfer coefficient. In addition, if gaskets leak, they leak to the outside, and gaskets are easy to replace.The plates prevent cross-contamination of products. Plate-and-frame heat exchangers provide high turbulence and a large pressure drop and are small compared with shell-and-tube heat exchangers.Disadvantages of plate-and-frame heat exchangers are that they have high-pressure and high-temperature limitations. Gaskets are easily damaged and may not be compatible with process fluids.Spiral Heat ExchangersSpiral heat exchangers are characterized by a compact concentric design that generates high fluid turbulence in the process medium (Figure 7.22). This type of heat exchanger comes in two basic types: (1) spiral flow on both sides and (2) spiral flow–crossflow. Type 1 spiral exchangers are used in liquid-liquid, condenser, and gas cooler service. Fluid flow into the exchanger is designed for full counterflow operation. The horizontal axial installation provides excellent self-cleaning of suspended solids.Type 2 spiral heat exchangers are designed for use as condensers, gas coolers, heaters, and reboilers. The vertical installation makes it an excellent choice for combining high liquid velocity and low pressure drop on the vapor-mixture side. Type 2 spirals can be used in liquid-liquid systems where high flow rates on one side are offset by low flow rates on the other.Air-Cooled Heat ExchangersA different approach to heat transfer occurs in the fin fan or air-cooled heat exchanger. Air-cooled heat exchangers provide a structured matrix of plain or finned tubes connected to an inlet and return header (Figure 7.23). Air is used as the outside medium to transfer heat away from the tubes. Fans are used in a variety of arrangements to apply forced convection for heattransfer coefficients. Fans can be mounted above or below the tubes in forced-draft or induced-draft arrangements. Tubes can be installed vertically or horizontally.The headers on an air-cooled heat exchanger can be classified as cast box, welded box, cover plate, or manifold. Cast box and welded box types have plugs on the end plate for each tube. This design provides access for cleaning individual tubes, plugging them if a leak is found, and rerolling to tighten tube joints. Cover plate designs provide easy access to all of the tubes. A gasket is used between the cover plate and head. The manifold type is designed for high-pressure applications.Mechanical fans use a variety of drivers. Common drivers found in service with air-cooled heat exchangers include electric motor and reduction gears, steam turbine or gas engine, belt drives, and hydraulic motors. The fan blades are composed of aluminum or plastic. Aluminum blades are d esigned to operate in temperatures up to 300°F (148.88°C), whereas plastic blades are limited to air temperatures between 160°F and 180°F(71.11°C, 82.22°C).Air-cooled heat exchangers can be found in service on air compressors, in recirculation systems, and in condensing operations. This type of heat transfer device provides a 40°F (4.44°C) temperature differential between the ambient air and the exiting process fluid.Air-cooled heat exchangers have none of the problems associated with water such as fouling or corrosion. They are simple to construct and cheaper to maintain than water-cooled exchangers. They have low operating costs and superior high temperature removal (above 200°F or 93.33°C). Their disadvantages are that they are limited to liquid or condensing service and have a high outlet fluid temperature and high initial cost of equipment. In addition, they are susceptible to fire or explosion in cases of loss of containment.。

课题换热器毕业设计翻译

Comparison of Water-water Heat Exchanger Between Shell-and-tube Type and Plate TypeAbstract :The closed-cycle cooling water system in the water of heat exchanger selection, discusses in detail the shell and tube heat exchanger with plate structure and properties of technical and economic comparison of selection for the water of heat exchangers provide a reference.Keywords: heat exchanger performance comparisonPower plants have been built from the domestic point of view, for the closed cycle cooling water system of the water of heat exchanger there are two types, one is shell and tube heat exchanger, and the other is a plate heat exchanger. Shell and tube heat exchanger is commonly used in heat exchangers form, in power plant design has been widely used, but some imported units in the domestic power plant, gas-steam combined cycle power plants and nuclear power plants have adopted multi-plate heat exchanger . As the plate heat exchanger compact, light weight, high heat transfer efficiency, a growing interest in it. In this paper, shell and tube and plate heat exchanger to compare two kinds of patterns and make selection of reference.A shell-and plate heat exchanger structure Introduction(1) Shell and tube heat exchangerShell and tube heat exchanger is a former Marine Room, tubes, tube, after thecomposition of the water room. Tubes used to pump-type tubes, which consists of front and rear tube plate, baffle plate, rod, will be away from the tube, heat-exchange component. Rod and tube plate, split-flow plate using threaded connections, heat exchange tube and tube sheet welding using sealed expansion joint increases. In the shell side of the water at the entrance to the tube bundle to set anti-scour plate, in order to prevent the cooling water directly to scour Tube. Bundle into or out of order to reduce friction when the tube in the bundle with the slide. In order to check the clean room, trash, sediment and tube blockage in the water chamber before and after an inspection hole on the end cap. In order to monitor the water of heat exchanger operation, being the cooling water side (except salt water side) and the cooling water side (sea side) imports and exports are set temperature and pressure measuring points, in addition to interfaces with the exhaust and turn on the water.(2) The plate heat exchangerPlate heat exchanger is a corrugated-shaped by a group composed of parallel metal plates in the plate's four corners have the access hole, the side panels were clamped in a fixed plate with a connecting tube and activities of pressed board framework, and used to clamp clamping bolts. The connecting pipe with the hole right in the channel plate, and with hot-swappable external piping connected to two kinds of liquids, heat transfer plates and the activities of pressed sheet hanging below the beam at the top of the bearer by the bottom of the beams so that it aligned location.There is a heat transfer plate itself has a specific shape and is solid tight gasket seal to prevent external leakage, and to heat exchange of the two kinds of liquids by means alternately counter-current flow on heat transfer plates to another within the channel between the . Ripples on the plate not only improve the level of fluid turbulence, and the formation of many points of contact in order to withstand the normal operating pressures. Fluid flow, physical properties, pressure drop and temperature difference determines the number and size of plate.2. Heat exchanger design conditionsHeat exchanger should be designed to meet the maximum output power from the start-up to load when you run a variety of needs, and left a certain margin to ensure the heat exchanger at maximum load, the maximum water temperature and maximum thermal resistance when the dirt, in the prescribed maintenance cycle, able to complete the task given cooling.With the introduction of domestic-type 300 MW coal-fired units, for example, the cooling device requires cooling water inlet temperature is not greater than 37.5 ℃, from the cooling device out of the cooling water is heated before the maximum temperature is about 42.8 ℃, its basic parameters are as follows:In addition to the cooling water salt waterDesign pressure 1.0 MPaFlow 1800 m3 / hOut of water temperature 42.8/37.5Pressure drop of ~ 0.06 MPaCooling water Seawater (seawater and river water alternately change)Design pressure 0.5 MPaInlet temperature 33 ℃Water temperatureCirculating waterDrop of pressure 0.05 ~ 0.06 MPa3.Shell and plate heat exchanger in comparison3.1 Comparison of design parametersAccording to the design of heat exchanger, respectively, made the following three conditions of the program:Program 1:two 100% capacity, Tube shell heat exchangerProgram 2:two 100% capacity plate heat exchangerProgram 3:three 50% capacity plate heat exchangersParameters of the program in Table 1.Table 1.The design parameters of the scheme of heat exchanger3.2 The open-cycle cooling water (water of the cooling water side heat exchanger) system, equipment selection ComparisonAccording to shell and tube and plate heat exchanger and cooling of different structural forms of water, need to choose a different electric filter and the open-cycle cooling water pumps, shown in Table 2.Table 2.The filter and pump parameters of each scheme selectionNo ItemUnit Program 1 （Tube shell type ） Program 2（Plate-type ） Program 3 (Fifty percent plate-type) 1 Type of water and heattransfer Tube shell type Plate-type Plate-type2 The amount of removing saltwater m 3/h 1800 1800 900 3 Water of heat exchanger installed units / run units 2/1 2/1 3/2 4 Each of the cooling area m 21023 785.7 314.6 5 Heat transfer coefficient W/(m 2·k) 3579 4435 6Desalted water entrancetemperatureThe desalted water outlettemperature ℃℃ 42.8 37.5 42.8 37.5 42.8 37.5 7The entrance temperature ofcirculating water The outlet temperature ofcirculating water ℃ ℃ 33 36.5 33 39 33 39 8 The flow rate of circulatingwaterm 3/h -3000 1632 821.4 9MaterialsTitanium tube, titanium composite boardTitanium tubeTitanium tube10 Size mm Φ1800×98004300×1300×34703100×1300×253011Weightkg2700250103720Devices Item Unit Program 1（Tube shell type）Program 2.3 （Plate-type）Open cycle pumpType 24sh- 19A(resistance toseawater)20 sh- 13 A(resistanceto seawater) Flow m3/h 2304～3600 1440～2232Lift mH2O 31.5～20 34～26Motor power kW 280 315 Installationunits台 2 2Operation units 台 1 1电动滤网Type vertical(resistanceto seawater)vertical(resistance toseawater) Flow m3/h -3000 1700Straineraperturemm Φ6 Φ3～43.3 Comparison of flow and heat transfer designShell and tube heat exchanger heat exchanger tubes are the basic building blocks,which has in the pipe flow of a fluid and through the pipe apart from the provision of heat transfer between a fluid surface. According to both sides of the fluid nature of pipe materials, will have a corrosive, water quality, poor water on the pipe flow, water quality, a good addition to brine on the shell side of the tube, so only use seawater corrosion-resistant tubes titanium tube, while cleaning dirt is more convenient, diameter from a heat transfer fluid mechanics point of view, given the use of small-diameter tubes the shell, you can get a larger surface density, but most current experience of the dirt deposited on the surface of the pipe layer, in particular, the cooling water pipe poor, silt and dirt and sea creatures exist, are likely to form a sediment in the wall, will worsen the regular cleaning of heat and work as a necessary restrictions on the tube diameter and the smallest is about cleaning 20 mm, Titanium tube usually taken Φ25 mm, for a given fluid, dirt formed mainly by the impact of the wall temperature and flow rate, in order to get a reasonable maintenance cycle, the water velocity inside tube should be 2 m / s or so (depending on the requirements to allow pressure drop ). As a general cooling water use sea water, river water etc., are prone to causing fouling on the shell and tube heat exchanger, should be based on sediment concentration of water required to set up a regular rubber ball cleaningdevice cleaning.Plate heat exchanger cooling water and cooling water have been on both sides of convection in the corrugated board, corrugated chevron corrugated using these heat transfer plates of corrugated bias, that is adjacent heat transfer plate has the same tilt angle but in a different direction ripple. Cross-sectional area along the flow direction is constant, but because of the ever-changing flow direction resulted in changes in shape of flow channel, which leads to turbulence. The general heat transfer plates of corrugated depth of 3 ~ 5 mm, turbulent flow area is about 0.1 ~ 1.0 m / s, corrugated thin thickness of 0.6 ~ 1 mm, adjacent cubicles have many points of contact in order to to withstand normal operating pressures, the adjacent panels are in the opposite direction of the chevron grooves, two grooves formed at the intersection point of contact that would also eliminate vibration, and in the promotion of turbulence and heat exchange at the same time, eliminating the due fatigue cracks caused by internal leakage. Chevron corrugated high degree of turbulence and high turbulence can give full play to clean them can be particularly effective to minimize the deposition of dirt, but the corrugated point of contact are more poor water quality when the liquid containing suspended solid particles, mixed animals and plants, etc., due to plate gap is very narrow, so as far as possible to ensure that all particles 2 mm or more before entering the heat exchanger, we must filter out, if the filter can not effectively play its role, it prone to clogging.3.4 Comparison of heat transfer coefficientTube shell heat exchanger, a tube of fluid passing through the lateral wall with the pipe flow of another fluid heat exchanger, each vertical cross-flow, the heat transfer coefficient is generally 1000 ~ 3000 w / (m2.k) .Plate heat exchanger, cooling water, cooling water side by side with the uniform turbulent flow, two kinds of reverse flow of fluid, due to the role of ripples caused by turbulence, resulting in a high heat transfer rate, high resistance to pressure drop and high shear stress field, which will led to the formation of inhibiting fouling in the heat transfer surface. The heat transfer coefficient is generally 3500 ~ 5500 w / (m2.k), this can save heat exchanger heat transfer area.3.5 Comparison of temperature differenceShell and tube heat exchanger terminal temperature difference (ie, cooling water inlet temperature and the cooling water outlet temperature difference is) for about5 ℃.Plate heat exchanger, because of its structural features can be economically achieved as low as 1 ℃of temperature difference.3.6 Comparison of cooling waterShell and tube heat exchanger cooling water and is generally the ratio of the cooling water is 1.2 ~ 2.5:1.Plate heat exchanger, due to two kinds of media flow path is basically the same heat transfer efficiency and high, plate heat exchangers can greatly reduce the amount of cooling water, cooling water and is generally the ratio of the cooling water of 0.8 ~ 1.1:1, so that Pipeline valves and pumps can reduce the running costs of the installation.3.7 Comparison of installation and maintenancePlate heat exchanger with small size and light weight characteristics, easy maintenance, without lifting set up maintenance facilities, and therefore less installation area. The artificial maintenance of plate heat exchanger including the folding machine to open, using spray guns and brushes clean plates and gaskets, inspection plates and gaskets, if necessary, replacement plates and gaskets. Plate heat exchangers to clean an annual general meeting, and whether or not the actual needs should be done. When the application of river water, seawater cooling water, poor water quality, due to the presence of silt and dirt, as well as the rapid growth of micro-organisms caused by surface contamination and the risk of clogging. In other countries, application of river water for cooling water, cleaning frequency is high, with an average 3.3 times per year.Shell and tube heat exchanger tube bundle is composed of its own weight were relatively large in size, in the maintenance pumping tube bundle when the need to stay out as long as the distance, it covers an area of more, with the necessary lifting needed to overhaul facilities. Shell and tube heat exchanger design life is generally 30 years, overhaul cycle, four years, when the heat exchanger leakage occurs, (which may be between the tube and tube sheet caused by leaking or broken pipe leakage) can be used blocked tube way in a short time return to work performance, shell and tube heat exchanger to allow plugging of 7% margin. For the cleaning of pipes as needed using rubber ball cleaning device of mechanical cleaning on a regular basis.4. heat exchangers in the domestic power plant operation(1) Huaneng Yueyang Power Plant's two units 362 MW unit, the British manufacturer, plate heat exchanger is supplied complete with the host. Plant is located along the Yangtse, recycled water for the Yangtze River, where the Yangtze River water is characterized by coarse less sand and more plants and more of this recycled water into the steam room before the set up filters to deal with three plants and so on, but according to plant reflection of plate heat exchangers easily blocked, because the rotating filter according to analysis of poor sealing, leakage into the plants, the fundamental issue is the three filtering poor prognosis.(2) Shanghai Wujing Power Plant 6 project hosts the Shanghai production of 300 MW of imported type unit, the unit closed cooling water systems, heat exchanger shell and tube water of the cooling water from the circulating water system supply, recycled water to take The Huangpu River's water, water, garbage, debris more, so water of heat exchanger entrance to set up two open-rotary filter, 11 aircraft fitted with the original design of the filter for the imported equipment, filter pore size 3 ~ 4 mm, due to poor water quality in the Huangpu River, frequently blocked the operation can not be self-cleaning, after numerous debugging invalid, this artificial split in the operation, the total cleaning equipment, labor intensive, but also affect the safe operation of unit Basically, every other day, need to manually cleaning.Analysis was mainly due to small pore size filters, filters in the structure design is not suited to China's water quality. To address the above issues, adopted a new electric automatic backwash filters, filter pore size of ψ 6 mm in good condition after the operation, not to have been blocked.Early Chinese production of the 300 MW coal-fired units are mostly closed cooling water system chosen shell and tube water of heat exchanger operation are better. In recent years, because of technological advances in design optimization needs, shell and tube exchanger Shui covers an area of large maintenance facilities in the main disadvantage of large plant layout optimization is even more prominent in a number of circulating water system for the secondary cooling The crew in the water, taking into account the cooling water of heat exchanger is relatively good water quality, low impurity and pollution as well as the filter structure of continuous improvement, closed cooling water systems also use plate heat exchanger.5 .technical and economic analysisWith the introduction of domestic-type 300 MW units, for example, under thewater of heat exchanger design conditions and closed cycle cooling water system requirements, shell and tube and plate manufacturers made an initial offer, respectively, other major auxiliary equipment is valued comparisons shown in Table 3.Table parison of three schemes of investmentPlate heat exchanger using imported equipment, and its offer when the offer is being made according to the exchange rate converted into yuan, and only consider the value-added tax. The above table does not include maintenance and overhaul costs, its difficult to estimate out, only qualitative analysis, for shell and tube heat exchangers include water-room, dirt handling of leak when plugging costs. Pairs of plate heat exchangers including plate cleaning and gasket replacement, because it is less frequent cleaning of shell and tube, and gaskets to use more than 2 ~ 3 years after the need to be replaced, so the overhaul of plate heat exchangers is higher maintenance costs. Comparison can be seen from the above, Option 1 and Option 2 investmentsComparisonof equipment costsItem UnitProgram 1 （Tube shell type ） Program 2（Plate-type ）Program 3 (Fifty percent plate-type)The cost of water to water heat exchanger Million yuan 2×210 2×219 3×122 Open cycle pump Millionyuan 2×28 2×17 2×17 Electric filterMillion yuan 28 30 30 TotalMillion yuan 504 502 430Comparisonof operation costComparison of equipment costs Million yuan 0 -2 -74 Open cycle pump power kW 2×280 2×215 2×215 Electric power filter kW 2×(0.75+0.37)2×(0.37+0.37)2×(0.37+0.37)Comparison of two schemes of powerkW0 -130.76 -130.76 Comparison of annual electricity consumption Milliondegrees 0 -98.07 -98.07 Comparison of annual operating cost Milliondegrees-13.7-13.7almost photogenic.6. ConclusionThrough the shell and tube and plate heat exchanger comparisons can be drawn the following conclusions: plate heat exchanger, heat transfer, heat transfer efficiency, small size and light weight in the disassembly, when the cooling water better, it is a kinds of ideal heat exchanger device. But for a large number of cooling water, sand, dirt, plants and so on exist, filters can not function effectively, it is easy to plug, resulting in frequent cleaning, affecting the safe operation of unit.管壳式与板式水水换热器的比较分析摘要 :通过闭式循环冷却水系统中水水换热器的选型,详细论述了管壳式与板式换热器的结构性能技术经济比较,为水水换热器的选型提供参考。

自动过程控制系统中英文对照外文翻译文献

中英文对照翻译(文档含英文原文和中文翻译)温度控制简介和PID控制器过程控制系统自动过程控制系统是指将被控量为温度、压.力、流量、成份等类型的过程变量保持在理想的运行值的系统。

实际上过程是动态的。

变化总是会出现，此时如果不采取相应的措施，那些与安全、产品质量和生产率有关的重要变量就不能满足设计要求。

为了说明问题，计我们来看一下热交换器。

流体在这个过程中被压缩的过热蒸汽加热，如图1所示。

图1热交换器这一装置的主要目的是将流体由入口温度Ti(t).加热到某一期望的出口温度T (t)。

如前所述，加热介质是压缩的过热蒸汽。

只要周围没有热损耗，过程流体获得的热量就等于蒸汽释放的热量，即热交换器和管道问的隔热性很好。

很多变量在这个过程中会发生变化，继而导致出日温度偏离期望值。

如果出现这种情况，就该采取一些措施来校正偏差，其目的是保持出日温度为期望值。

实现该目的的一种方法是首先测量r(0)，然后与期望值相比较，由比较结果决定如何校正偏差。

蒸汽的流量可用于偏差的校.正。

就是说，如果温度高于期望值，就关小蒸汽阀来减小进入换热器的蒸汽流量；:若温度低于期望值，就开大蒸汽阀，以增加进入换热器的蒸汽流量。

所有这些操作都可由操作员手工实现，操作很简单，不会出现什么问题。

但是，由于多数过程对象都有很多变量需要保持为某一期望值，就需要许多的操作员来进行校正。

因此，我们想自动完成这种控制。

就是说，我们想利用无需操作人员介入就可以控制变量的设备。

这就是所谓自动化的过程控制。

为达到上述日标，就需要设计并实现一个系统。

图2所示为一个可行的控制系统及其基本构件。

图2热交换器控制循环首先要做的是测量过程流体的出口温度，这一任务由传感器(热电偶、热电阻等)完成。

将传感器连接到变送器上，由变送器将传感器的输出信号转换为足够大的信号传送给控制器。

控制器接收与温度相关的信号并与期望值比较。

根据比较的结果，控制器确定保持温度为期望值的控制作用。

基于这一结果，控制器再发一信号给执行机构来控制蒸汽流量。

换热器文献翻译之英文部分

A Survey on a Heat Exchangers Network to Decrease EnergyConsumption by Using Pinch TechnologyB.Raei and A.H.TarighaleslamiChemical Engineering Faculty,Mahshahr Branch,lslamic Azad University,Mahshahr 63519,lranReceived：April27,2011／Accepted：July7，2011／Published：December20,2011 Abstract：There are several ways to increase the efficiency of energy consumption and to decrease energy consumption．In this paper.The application of pinch technology in analysis of the heat exchangers network(HEN)in order to reduce the energy consumption in a thermal system is studied.Therefore，in this grass root design，the optimum value ofΔTmin is obtained about10℃and area efficiency(α)is0.95.The author also depicted the grid diagram and driving force plot for additional analysis.In order to increase the amount of energy saving，heat transfer from above to below the pinch point in the diagnosis stage is verified for all options including re-sequencing，re-piping,add heat exchanger and splitting of the flows.Results show that this network has a low potential of retrofit to decrease the energy consumption，which pinch principles are planned to optimize energy consumption of the unit.Regarding the results of pinch analysis，it is suggested that in order to reduce the energy consumption.No alternative changes in the heat exchangers network of the unit is required.The acquired results show that the constancy of network is completely confirmed by the high area efficiency infirmity of the heat exchanger to pass the pinch point and from of deriving force plot.Key words：Pinch technology，heat exchangers network，energy consumption，composite curve，grand composite curve1．At the end of1970s，Umeda and his co-workers in Chiyoda established new technology for optimization of process.During1978to1982，this team by presenting of the concept of processes analysis and composite curve showed how the utility consumption can be evaluated and heat recovery and reduction can be done with using this method.At the same time，Linnhoff and his co-workers considered the analysis of heat exchangers network(HEN)for energy consumption reduction and introduced the concepts such as composite curve as an important tool for heat energy recovery.But contrary to Chiyoda team，they emphasized on a pinch point as a key point for heat recovery and by this reason they chose the name of pinch technology for this method.When the time passed，pinch technology has been developed.As the same as HEN,it is used for optimization of energy consumption in distillation towers，furnaces,evaporators，turbines and reactors.Pinch technology is a systematic method based on first and second laws of thermodynamic，which is used for analysis of chemical processes and utilities.Pinch analysis of an industrial process is used for definition of energy and capital costs of HEN before design and also definition of pinch point.In this method,before design,minimum consumption of utility，minimum demanded network area and minimum number of demanded heat unit at pinch pointare targeted for given process．At next stage，design of HEN will be done to satisfy performed target.Finally，minimum annual cost is obtained with comparison between energy cost and capital cost and trade of them.Therefore，the main goal of pinch analysis is the optimization of process heat integration，increase the process-process heat recovery,and decrease the amount of utility consumption．For analysis,at first,shifted temperature is obtained then temperature and enthalpy plot draw(half of amount of minimum temperature are deducted from hot stream and added to cold stream).Fig.1shows the composite curve and grand composite curve as tools for pinch Analysis.The composite curves(CCs)present the relationship between cumulative enthalpy flow rate and temperature for the HEN hot and cold streams．In practice，CCs are generated by a cumulative process over a temperature range，and the resulting hot and cold CCs are labelled CCh and CCc，respectively.2．Methods and Data2.1Presentation of a Heat Exchanger NetworkIn a heat exchanger network，arrangement of exchangers in the network is important.For representing such arrangement，the concept of“stage"is used.In every stage,the input and output heat of the stage is equal for the entire exchangers that settled on special stream，whereas the number of stages is not too many in an optimal network.In this part，stages of heat exchanger networks analysis for reduction of energy consumption using pinch technology were explained.Since targeting and design is based on extracted data any mistake and careless in data assembling can lead to completely unreal results.In pinch analysis，design data such as supply and target temperature of streams，flow and heat capacity of stream was used and on the other hand，heat exchangers design was related to heat transfer coefficient directly.In Table1,the necessary extracted information and a sample network is represented．In this research，Aspen pinch software has been used．Fig.1Tools for pinch analysis：composite curve(CC)and grand composite curve(Gee)．Table1Extracted data．2.2Economical DataCorrect economic data including operation time ，interest rate and equipment life have an important role on successful execution ofretrofit and preparation ．The values are shown in Table 2．The condition of utilities which includes steam and cooling water is shown in Table 3．Capital cost and energy cost of network can be calculated with respect to the shells number and the cost of any exchanger calculates with using Eq ．(1)：c Area b a t CapitalCos )(+=(1)In this equation ，a ，b and C are constant ．So that ，“a”is function of pressure intensity ．“b”is function of exchanger material and “c”is function of type of exchanger that is different for various exchangers ；SO 0<C <1．Types of exchanger are defined by designer based on nature of chemical materials ，pressure of flows ，pressure condition and ability of corrosion ．For carbon-still exchanger ，cost equation is as follow ：81.0)(75030800Area t CapitalCos +=。

毕业论文之温度控制系统的设计外文翻译

Design of the Temperature Control System Based on AT89C51ABSTRACTThe principle and functions of the temperature control system based on micro controller AT89C51 are studied, and the temperature measurement unit consists of the 1-Wire bus digital temperature sensor DS18B20. The system can be expected to detect the preset temperature, display time and save monitoring data. An alarm will be given by system if the temperature exceeds the upper and lower limit value of the temperature which can be set discretionarily and then automatic control is achieved, thus the temperature is achieved monitoring intelligently within a certain range. Basing on principle of the system, it is easy to make a variety of other non-linear control systems so long as the software design is reasonably changed. The system has been proved to be accurate, reliable and satisfied through field practice. KEYWORDS: AT89C51; micro controller; DS18B20; temperature1 INTRODUCTIONTemperature is a very important parameter in human life. In the modern society, temperature control (TC) is not only used in industrial production, but also widely used in other fields. With the improvement of the life quality, we can find the TC appliance in hotels, factories and home as well. And the trend that TC will better serve the whole society, so it is of great significance to measure and control the temperature. Based on the AT89C51 and temperature sensor DS18B20, this system controls the condition temperature intelligently. The temperature can be set discretionarily within a certain range. The system can show the time on LCD, and save monitoring data; and automatically control the temperature when the condition temperature exceeds the upper and lower limit value. By doing so it is to keep the temperature unchanged. The system is of high anti-jamming, high control precision and flexible design; it also fits the rugged environment. It is mainly used in people's life to improve the quality of the work and life. It is also versatile, so that it can be convenient to extend the use of the system. So the design is of profound importance. The general design, hardware design and software design of the system are covered.1.1 IntroductionThe 8-bit AT89C51 CHMOS microcontrollers are designed to handle high-speed calculations and fast input/output operations. MCS 51 microcontrollers are typically used for high-speed event control systems. Commercial applications include modems, motor-control systems, printers, photocopiers, air conditioner control systems, disk drives, and medical instruments. The automotive industry use MCS 51 microcontrollers in engine-control systems, airbags, suspension systems, and antilock braking systems (ABS). The AT89C51 is especially well suited to applications that benefit from its processing speed and enhanced on-chip peripheral functions set, such as automotive power-train control, vehicle dynamic suspension, antilock braking, and stability control applications. Because of these critical applications, the market requires a reliable cost-effective controller with a low interrupt latency response, ability to service the high number of time and event driven integrated peripherals needed in real time applications, and a CPU with above average processing power in a single package. The financial and legal risk of having devices that operate unpredictably is very high. Once in the market, particularly in mission critical applications such as an autopilot or anti-lock braking system, mistakes are financially prohibitive. Redesign costs can run as high as a $500K, much more if the fix means 2 back annotating it across a product family that share the same core and/or peripheral design flaw. In addition, field replacements of components is extremely expensive, as the devices are typically sealed in modules with a total value several times that of the component. To mitigate these problems, it is essential that comprehensive testing of the controllers be carried out at both the component level and system level under worst case environmental and voltage conditions. This complete and thorough validation necessitates not only a well-defined process but also a proper environment and tools to facilitate and execute the mission successfully. Intel Chandler Platform Engineering group provides post silicon system validation (SV) of various micro-controllers and processors. The system validation process can be broken into three major parts. The type of the device and its application requirements determine which types of testing are performed on the device.1.2 The AT89C51 provides the following standard features4Kbytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bittimer/counters, a five vector two-level interrupt architecture, a full duple ser-ial port, on-chip oscillatorand clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt sys -tem to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscil–lator disabling all other chip functions until the next hardware reset.1.3Pin DescriptionVCC Supply voltage.GND Ground.Port 0：Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high impedance inputs. Port 0 may also be configured to be the multiplexed low order address/data bus during accesses to external program and data memory. In this mode P0 has internal pull ups. Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during program verification. External pull ups are required during program verification.Port 1：Port 1 is an 8-bit bi-directional I/O port with internal pull ups. The Port 1 output buffers can sink/so -urce four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal pull ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups. Port 1 also receives the low-order address bytes during Flash programming and verification.Port 2：Port 2 is an 8-bit bi-directional I/O port with internal pull ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high by the internal pull ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX@DPTR). In this application, it uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-orderaddress bits and some control signals durin Flash programming and verification.Port 3：Port 3 is an 8-bit bi-directional I/O port with internal pull ups. The Port 3 output buffers can sink/sou -rce four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internal pull ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull ups.Port 3 also serves the functions of various special features of the AT89C51 as listed below:RST：Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device.ALE/PROG：Address Latch Enable output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped duri-ng each access to external Data Memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.PSEN：Program Store Enable is the read strobe to external program memory. When theAT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.EA/VPP：External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin alsreceives the 12-volt programming enable voltage (VPP) during Flash programming, for parts that require 12-volt VPP.XTAL1：Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2 ：Output from the inverting oscillator amplifier. Oscillator CharacteristicsXTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator, as shownin Figure 1. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2.There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed. Idle Mode In idle mode, the CPU puts itself to sleep while all the on chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset. It should be noted that when idle is terminated by a hard ware reset, the device normally resumes program execution, from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when Idle is terminated by reset, the instruction following the one that invokes Idle should not be one that writes to a port pin or to external memory.Power-down ModeIn the power-down mode, the oscillator is stopped, and the instruction that invokes power-down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power-down mode is terminated. The only exit from power-down is a hardware reset. Reset redefines the SFRS but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize. The AT89C51 code memory array is programmed byte-by byte in either programming mode. To program any nonblank byte in the on-chip Flash Memory, the entire memory must be erased using the Chip Erase Mode.2 Programming AlgorithmBefore programming the AT89C51, the address, data and control signals should be set up according to the Flash programming mode table and Figure 3 and Figure 4. To program the AT89C51, take the following steps.1. Input the desired memory location on the address lines.2. Input the appropriate data byte on the data lines. 3. Activate the correct combination of control signals. 4. Raise EA/VPP to 12V for the high-voltage programming mode. 5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits. The byte-write cycle is self-timed and typically takes nomore than 1.5 ms. Repeat steps 1 through 5, changing the address and data for the entire array or until the end of the object file is reached. Data Polling: The AT89C51 features Data Polling to indicate the end of a write cycle. During a write cycle, an attempted read of the last byte written will result in the complement of the written datum on PO.7. Once the write cycle has been completed, true data are valid on all outputs, and the next cycle may begin. Data Polling may begin any time after a write cycle has been initiated.2.1Ready/Busy:The progress of byte programming can also be monitored by the RDY/BSY output signal. P3.4 is pulled low after ALE goes high during programming to indicate BUSY. P3.4 is pulled high again when programming is done to indicate READY.Program Verify:If lock bits LB1 and LB2 have not been programmed, the programmed code data can be read back via the address and data lines for verification. The lock bits cannot be verified directly. Verification of the lock bits is achieved by observing that their features are enabled.2.2 Chip Erase:The entire Flash array is erased electrically by using the proper combination of control signals and by holding ALE/PROG low for 10 ms. The code array is written with all “1”s. The chip erase operation must be executed before the code memory can be re-programmed.2.3 Reading the Signature Bytes:The signature bytes are read by the same procedure as a normal verification of locations 030H, 031H, and 032H, except that P3.6 and P3.7 must be pulled to a logic low. The values returned areas follows.(030H) = 1EH indicates manufactured by Atmel(031H) = 51H indicates 89C51(032H) = FFH indicates 12V programming(032H) = 05H indicates 5V programming2.4 Programming InterfaceEvery code byte in the Flash array can be written and the entire array can be erased by using the appropriate combination of control signals. The write operationcycle is self timed and once initiated, will automatically time itself to completion. A microcomputer interface converts information between two forms. Outside the microcomputer the information handled by an electronic system exists as a physical signal, but within the program, it is represented numerically. The function of any interface can be broken down into a number of operations which modify the data in some way, so that the process of conversion between the external and internal forms is carried out in a number of steps. An analog-to-digital converter(ADC) is used to convert a continuously variable signal to a corresponding digital form which can take any one of a fixed number of possible binary values. If the output of the transducer does not vary continuously, no ADC is necessary. In this case the signal conditioning section must convert the incoming signal to a form which can be connected directly to the next part of the interface, the input/output section of the microcomputer itself. Output interfaces take a similar form, the obvious difference being that here the flow of information is in the opposite direction; it is passed from the program to the outside world. In this case the program may call an output subroutine which supervises the operation of the interface and performs the scaling numbers which may be needed for digital-to-analog converter(DAC). This subroutine passes information in turn to an output device which produces a corresponding electrical signal, which could be converted into analog form using a DAC. Finally the signal is conditioned(usually amplified) to a form suitable for operating an actuator. The signals used within microcomputer circuits are almost always too small to be connected directly to the outside world”and some kind of interface must be used to translate them to a more appropriate form. The design of section of interface circuits is one of the most important tasks facing the engineer wishing to apply microcomputers. We have seen that in microcomputers information is represented as discrete patterns of bits; this digital form is most useful when the microcomputer is to be connected to equipment which can only be switched on or off, where each bit might represent the state of a switch or actuator. To solve real-world problems, a microcontroller must have more than just a CPU, a program, and a data memory. In addition, it must contain hardware allowing the CPU to access information from the outside world. Once the CPU gathers information and processes the data, it must also be able to effect change on some portion of the outside world. These hardware devices, called peripherals, are the CPU’s window to the outside.The most basic form of peripheral available on microcontrollers is the generalpurpose I70 port. Each of the I/O pins can be used as either an input or an output. The function of each pin is determined by setting or clearing corresponding bits in a corresponding data direction register during the initialization stage of a program. Each output pin may be driven to either a logic one or a logic zero by using CPU instructions to pin may be viewed (or read.) by the CPU using program instructions. Some type of serial unit is included on microcontrollers to allow the CPU to communicate bit-serially with external devices. Using a bit serial format instead of bit-parallel format requires fewer I/O pins to perform the communication function, which makes it less expensive, but slower. Serial transmissions are performed either synchronously or asynchronously.3 SYSTEM GENERAL DESIGNThe hardware block diagram of the TC is shown in Fig. 1. The system hardware includes the micro controller, temperature detection circuit, keyboard control circuit, clock circuit, Display, alarm, drive circuit and external RAM. Based on the AT89C51, the DS18B20 will transfer the temperature signal detected to digital signal. And the signal is sent to the micro controller for processing. At last the temperature value is showed on the LCD 12232F. These steps are used to achieve the temperature detection. Using the keyboard interface chip HD7279 to set the temperature value, using the micro controller to keep a certain temperature, and using the LCD to show the preset value for controlling the temperature. In addition, the clock chip DS1302 is used to show time and the external RAM 6264 is used to save the monitoring data. An alarm will be given by buzzer in time if the temperature exceeds the upper and lower limit value of the temperature.3.1 HARDWARE DESIGNA. Micro controllerThe AT89C51 is a low-power, high-performance CMOS 8-bit micro controller with 4K bytes of in-system programmable Flash memory. The device is manufactured using At mel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the At mel AT89C51 is a powerful micro controller which provides a highly-flexible and cost-effective solution to manyembedded control applications. Minimum system of the micro controller is shown in Fig. 2. In order to save monitoring data, the 6264 is used as an external RAM. It is a static RAM chip, low-power with 8K bytes memory.B. Temperature Detection CircuitThe temperature sensor is the key part in the system. The Dallas DS18B20 is used, which supports the 1-Wire bus interface, and the ON-BOARD Patented is used internally. All the sensor parts and the converting circuit are integrated in integrated circuit like a transistor [1]. Its measure range is -55℃~125 ℃, and the precision between -10℃~85℃is ±0.5℃[2 ,3]. The temperature collected by the DS18B20 is transmitted in the 1-Wire bus way, and this highly raises the system anti-jamming and makes it fit in situ temperature measurement of the rugged environment [4]. There are two power supply ways for the DS18B20. The first is external power supply: the first pin of the DS18B20 is connected to the ground; the second pin serves as signal wire and the third is connected to the power. The second way is parasite power supply [5]. As the parasite power supply will lead to the complexity of the hardware circuit, the difficulty of the software control and the performance degradation of the chip, etc. But the DS18B20(s) can be connected to the I/O port of the micro controller in the external power supply way and it is more popular. Therefore the external power supply is used and the second pin is connected to the pin P1.3 of the AT89S51. Actually, if there are multipoint to be detected, the DS18B20(s) can be connected to the 1-Wire bus. But when the number is over 8, there is a concern to the driving and the more complex software design as well as the length of the 1-Wire bus. Normally it is no more than 50m. To achieve distant control, the system can be designed in to a wireless one to breakthe length limit of the 1-Wire bus [6].C. LCD CircuitThe LCD 12232F is used, which can be used to show characters, temperature value and time, and supply a friendly display interface. The 12232F is a LCD with 8192 128×32 pixels Chinese character database and 128 16×8 pixels ASCII character set graphics. It mainly consists of row drive/column drive and 128×32 full lattice LCD with the function of displaying graphics as well as 7.5×2 Chinese characters. It is in a parallel or serial mode to connect to external CPU [7]. In order to economize the hardware resource, the 12232F should be connected to the AT89S51 in serial mode with only 4 output ports used. The LCD grayscale can be changed by adjustingthe variable resistor connected the pin Vlcd of the LCD. CLK is used to transmit serial communication clock. SID is used to transmit serial data. CS is used to enable control the LCD. L+ is used to control the LCD backlight power.D. Clock CircuitThe Dallas DS18B20 is used, which is a high performance, low-power and real-time clock chip with RAM. The DS18B20 serves in the system with calendar clock and is used to monitor the time. The time data is read and processed by the AT89C51 and then displayed by the LCD. Also the time can be adjusted by the keyboard. The DS18B20 crystal oscillator is set at 32768Hz, and the recommended compensation capacitance is 6pF. The oscillator frequency is lower, so it might be possible not to connect the capacitor, and this would not make a big difference to the time precision. The backup power supply can be connected to a 3.6V rechargeable battery.E. Keyboard Control CircuitThe keyboard interface in the system is driven by the HD7279A which has a +5V single power supply and which is connected to the keyboard and display without using any active-device. According to the basic requirements and functions of the system, only 6 buttons are needed. The system's functions are set by the AT89C51 receiving the entered data. In order to save the external resistor, the 1×6 keyboard is used, and the keyboard codes are defined as: 07H, 0FH, 17H, 1FH, 27H, 2FH. The order can be read out by reading the code instruction. HD7279A is connected to the AT89S51 in serial mode and only 4 ports are need. As shown in Fig. 6, DIG0~DIG5 and DP are respectively the column lines and row line ports of the six keys which achieve keyboard monitoring, decoding and key codes identification.F. Alarm CircuitIn order to simplify the circuit and convenient debugging, a 5V automatic buzzer is used in the alarm circuit [8]. And this make the software programming simplified. As shown in Fig. 7, it is controlled by the PNP transistor 9012 whose base is connected to the pin P2.5 of the AT89C51. When the temperature exceeds the upper and lower limit value, the P2.5 output low level which makes the transistor be on and then an alarm is given by the buzzer.G. Drive CircuitA step motor is used as the drive device to control the temperature. The four-phase and eight-beat pulse distribution mode is used to drive motor and thesimple delay program is used to handle the time interval between the pulses to obtain different rotational speed. There are two output states for the step motor. One: when the temperature is over the upper value, the motor rotates reversely (to low the temperature), while when lower than the lower limit value, the motor rotates normally (to raise the temperature); besides not equals the preset value. Two: when the temperature is at somewhere between the two ends and equals the preset value, the motor stops. These steps are used to achieve the temperature control. In addition, the motor speed can also be adjusted by relative buttons. As shown in Fig. 8, the code data is input through ports A11~A8 (be P2.3~P2.0) of the AT89C51 and inverted output by the inverter 74LS04. Finally it is amplified by the power amplifier 2803A to power the motor.3.2 SOFTW ARE DESIGNAccording to the general design requirement and hardware circuit principle of the system, as well as the improvement of the program readability, transferability and the convenient debugging, the software design is modularized. The system flow mainly includes the following 8 steps: POST (Power-on self-test), system initiation, temperature detection, alarm handling, temperature control, clock chip DS18B20 operation, LCD and keyboard operation. The main program flow is shown in Fig. 9. Give a little analysis to the above 8 tasks, it is easy to find out that the last five tasks require the real time operation. But to the temperature detection it can be achieved with timer0 timing 1 second, that is to say temperature detection occurs per second. The system initiation includes global variable definition, RAM initiation, special function register initiation and peripheral equipment initiation. Global variable definition mainly finishes the interface definition of external interface chip connected to the AT89C51, and special definition of some memory units. RAM initiation mainly refers to RAM processing. For example when the system is electrified the time code will be stored in the internal unit address or the scintillation flag will be cleared. The special function register initiation includes loading the initial value of timer and opening the interrupt. For example, when the system is electrified the timer is initialized. The peripheral equipment initiation refers to set the initial value of peripheral equipment. For example, when the system is electrified, the LCD should be initialized, the start-up display should be called, the temperature conversion command should be issued firstly and the clock chip DS18B20 should also be initialized. The alarm handling is mainly the lowering and the raising of temperature to make thetemperature remain with the preset range. When the temperature is between the upper and the lower limit value, it goes to temperature control handling, that is to say the temperature need to be raised or lowered according to the preset value. By doing so make the condition temperature equal to the preset value and hence to reach the temperature target.4 CONCLUSIONThe temperature control system has the advantages of friendly human-computer interaction interface, simple hardware, low cost, high temperature control precision (error in the range of ±1 ℃), convenience and versatility, etc. It can be widely used in the occasions with -55℃to 125℃range, and there is a certain practical value.。

热电联产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)外文文献:The Optimal Operation Criteria for a Gas Turbine Cogeneration System Abstract: The study demonstrated the optimal operation criteria of a gas turbine cogeneration system based on the analytical solution of a linear programming model. The optimal operation criteria gave the combination of equipment to supply electricity and steam with the minimum energy cost using the energy prices and the performance of equipment. By the comparison with a detailed optimization result of an existing cogeneration plant, it was shown that the optimal operation criteria successfully provided a direction for the system operation under the condition where the electric power output of the gas turbine was less than the capacity.Keywords: Gas turbine; Cogeneration; Optimization; Inlet air cooling.1. IntroductionCogeneration, or combined heat and power production, is suitable for industrial users who require large electricity as well as heat, to reduce energy and environmental impact. To maximize cogeneration, the system has to be operated with consideration electricity and heat demands andthe performance of equipment. The optimal operation of cogeneration systems is intricate in many cases, however, due to the following reasons. Firstly, a cogeneration system is a complex of multiple devices which are connected each other by multiple energy paths such as electricity, steam, hot water and chilled water. Secondly, the performance characteristics of equipment will be changed by external factors such as weather conditions.For example, the output and the efficiency of gas turbines depend on the inlet air temperature. Lastly,the optimal solution of operation of cogeneration systems will vary with the ratio of heat demand to electricity demand and prices of gas, oil and electricity.Because of these complexities of cogeneration systems, a number of researchers have optimal solutions of cogeneration systems using mathematical programming or other optimization techniques. Optimization work focusing on gas turbine cogeneration systems are as follows. Yokoyama et al. [1] presented optimal sizing and operational planning of a gas turbine cogeneration system using a combination of non-linear programming and mixed-integer linear programming methods. They showed the minimum annual total cost based on the optimization strategies. A similar technique was used by Beihong andWeiding [2] for optimizing the size of cogeneration plant. A numerical example of a gas turbine cogeneration system in a hospital was given and the minimization of annual total cost was illustrated. Kong et al. [3] analyzed a combined cooling, heating and power plant that consisted of a gas turbine, an absorption chiller and a heat recovery boiler. The energy cost of the system was minimized by a linear programming model and it was revealed that the optimal operational strategies depended on the load conditions as well as on the cost ratio of electricity to gas. Manolas et al. [4] applied a genetic algorithm (GA) for the optimization of an industrial cogeneration system, and examined the parameter setting of the GA on the optimization results. They concluded that the GA was successful and robust in finding the optimal operation of a cogeneration system.As well as the system optimization, the performance improvement of equipment brings energy cost reduction benefits. It is known that the electric power output and the efficiency of gas turbines decrease at high ambient temperatures. Some technical reports [5, 6] show that the electric power output of a gas turbine linearly decreases with the rise of the ambient temperature, and it varies about 5 % to 10 % with a temperature change of 10 ◦C. Therefore, cooling of the turbine inlet air enhances electric output and efficiency. Some studies have examined theperformance of the gas turbine with inlet air cooling as well as the effect of various cooling methods [7, 8, 9].The cooling can be provided without additional fuel consumption by evaporative coolers or by waste heat driven absorption chillers. The optimal operation of the system will be more complex, however, especially in the case of waste heat driven absorption chillers because the usage of the waste heat from the gas turbine has to be optimized by taking into consideration the performance of not only the gas turbine and the absorption chiller but also steam turbines, boilers and so on. The heat and electricity demands as well as the prices of electricity and fuels also influence the optimal operation.The purpose of our study is to provide criteria for optimal operation of gas turbine cogeneration systems including turbine inlet air cooling. The criteria give the minimum energy cost of the cogeneration system. The method is based on linear programming and theKuhn-Tucker conditions to examine the optimal solution, which can be applied to a wide range of cogeneration systems.2. The Criteria for the Optimal Operation of Gas Turbine Cogeneration SystemsThe criteria for the optimal operation of gas turbine cogeneration systems were examined from the Kuhn-Tucker conditions of a linear programming model [10]. A simplified gas turbine cogeneration system was modeled and the region where the optimal solution existed was illustrated on a plane of the Lagrange multipliers.2.1. The Gas Turbine Cogeneration System ModelThe gas turbine cogeneration system was expressed as a mathematical programming model. The system consisted of a gas turbine including an inlet air cooler and a heat recovery steam generator (HRSG), a steam turbine, an absorption chiller, a boiler and the electricity grid. Figure 1 shows the energy flow of the system. Electricity, process steam, and cooling for process or for air-conditioning are typical demands in industry, and they can be provided by multiple suppliers. In the analysis, cooling demands other than for inlet air cooling were not taken into account, and therefore, the absorption chiller would work only to provide inlet air cooling of the gas turbine. The electricity was treated as the electric power in kilowatts, and the steam and the chilled water were treated as the heat flow rates in kilowatts so that the energy balance can be expressed in the same units.Figure 1. The energy flow of the simplified gas turbine cogeneration system with the turbineinlet air cooling.The supplied electric power and heat flow rate of the steam should be greater than or equal to the demands, which can be expressed by Eqs. (1-2).(1)(2)where, xe and xs represent the electric power demand and the heat flow rate of the steam demand. The electric power supply from the grid, the gas turbine and the steam turbine are denoted by xG, xGT and xST, respectively. xB denotes the heat flow rate of steam from the boiler, and xAC denotes the heat flow rate of chilled water from the absorption chiller. The ratio of the heat flow rate of steam from the HRSG to the electric power from the gas turbine is denominated the steam to electricity ratio, and denoted by ρGT. Then, ρGTxGT represents the heat flow rate o f steam from the gas turbine cogeneration. The steam consumption ratios of the steam turbine and the absorption chiller are given as ωST and ωAC, respectively. The former is equivalent to the inverse of the efficiency based on the steam input, and the latter is equivalent to the inverse of the coefficient of performance.The inlet air cooling of the gas turbine enhances the maximum output from the gas turbine. By introducing the capacity of the gas turbine, XGT, the effect of the inlet air cooling was expressed by Eq. (3).(3).It was assumed that the increment of the gas turbine capacity was proportional to the heatflow rate of chilled water supplied to the gas turbine. The proportional constant is denoted byαGT.In addition to the enhancement of the gas turbine capacity, the inlet air cooling improves the electric efficiency of the gas turbine. Provided that the improvement is proportional to the heat flow rate of chilled water to the gas turbine, the fuel consumption of the gas turbine can be expressed as ωGTxGT¡βGTxAC, whereωGT is the fuel consumption ratio without the inlet air cooling and βGT is the improvement factor of the fuel consumption by the inlet air cooling. As the objective of the optimization is the minimization of the energy cost during a certain time period, Δt, the energy cost should be expressed as a function of xG, xGT, xST, xB and xAC. By defining the unit energy prices of the electricity, gas and oil as Pe, Pg and Po, respectively, the energy cost, C, can be given as:(4)where, ωB is the fuel consumpti on ratio of the boiler, which is equivalent to the inverse of the thermal efficiency.All the parameters that represent the characteristics of equipment, such as ωGT, ωST, ωAC, ωB, ρGT, αGT and βGT, were assumed to be constant so that the system could be m odeled by the linear programming. Therefore, the part load characteristics of equipment were linearly approximated.2.2. The Mathematical Formulation and the Optimal Solution From Eqs. (1–4), the optimization problem is formed as follows:(5)(6)(7)(8)where, x = (xG, xGT, xST, xB, xAC). Using the Lagrange multipliers, λ = (λ1, λ2, λ3), theobjectivefunction can be expressed by the Lagrangian, L(x,λ).(9)According to the Kuhn-Tucker conditions, x and λ satisfy the following conditions at the optimal solution.(10)(11)(12)(13)The following inequalities are derived from Eq. (10).(14)(15)(16)(17)(18)Equation (11) means that xi > 0 if the derived expression concerning the supplier i satisfies the equali ty, otherwise, xi = 0. For example, xG has a positive value if λ1 equals PeΔt. If λ1 is less than PeΔt, then xG equals zero.With regard to the constraint g3(x), it is possible to classify the gas turbine operation into two conditions.The first one is the case where the electric power from the gas turbine is less than the capacity,which means xG < XGT + αGTxAC. The second one is the case where the electric power from the gas turbine is at the maximum, which means xGT = XGT + αGTxAC. We denominate the former and the latter conditions the operational conditions I and II, respectively. Due to Eq. (12) of the Kuhn-Tucker condition, λ3 = 0 on the operational condition I, and λ3 > 0 on the operational condition II.2.3. The Optimal Solution where the Electric Power from the Gas Turbine is less than theCapacityOn the operational condition I where xG < XGT + αGTxAC, Eqs. (14–18) can be drawn on the λ1-λ2 plane because λ3 equals zero. The region surrounded by the inequalities gives the feasible solutions, and the output of the supplier i has a positive value, i.e. xi > 0, when the solution exists on the line which represents the supplier i.Figure 2 illustrates eight cases of the feasible solution region appeared on the λ1-λ2 plane. The possible optimal solutions ar e marked as the operation modes “a” to “g”. The mode a appears in the case A, where the grid electricity and the boiler are chosen at the optimal operation. In the mode b,the boiler and the steam turbine satisfy the electric power demand and the heat flow rate of the steam demand. After the case C, the electric power from the gas turbine is positive at the optimal operation.In the case C, the optimal operation is the gas turbine only (mode c), the combination of the gas turbine and the boiler (mode d) or the combination of the gas turbine and the grid electricity (mode e). In this case, the optimal operation will be chosen by the ratio of the heat flow rate of the steam demand to the electric power demand, which will be discussed later. When the line which represents the boiler does not cross the gas turbine line in the first quadrant, which is the case C’, only the modes c and e appear as the possible optimal solutions. The modes f and g appear in the cases D and E, respectively. The suppliersThe cases A through E will occur depending on the performance parameters of the suppliers and the unit energy prices. The conditions of each case can be obtained from the graphical analysis. For example, the case A occurs if λ1 at the intersection of G and B is smaller than that at the intersection of GT and B, and is smaller than that at the intersection of ST and B. In addition, the line B has to be located above the line AC so that the feasible solution region exists. Then, the following conditions can be derived.(19)(20)(21)Equation (19) means that the gas cost to produce a certain quantity of electricity and steam with the gas turbine is higher than the total of the electricity and oil costs to purchase the same quantity of electricity from the grid and to produce the same quantity of steam with the boiler.Equation (20) means that the electricity cost to purchase a certain quantity of electricity is cheaper than the oil cost to produce the same quantity of electricity using the boiler and the steam turbine. Equation (21) indicates that the reduction of the gas cost by a certain quantity of the inlet air cooling should be smaller than the oil cost to provide the same quantity of cooling using the boiler and the absorption chiller. Otherwise, the optimal solution does not exist because the reduction of the gas cost is unlimited by the inlet air cooling using the absorption chiller driven by the boiler.Figure 2. The possible cases of the optimal solution on the operational condition ISimilar ly, the following conditions can be derived for the other cases. The condition given as Eq. (21) has to be applied to all the cases below.Case B:(22)(23)Equation (22) compares the production cost of the electricity and the steam between the gas and the oil. The gas cost to produce a certain quantity of electricity and steam by the gas turbine is higher than the oil cost to produce the same quantity of electricity and steam by thecombination of the boiler and the steam turbine. Equation (23) is the opposite of Eq. (20), which means that the oil cost to produce a certain quantity of electricity by the boiler and the steam turbine is cheaper than the purchase price of electricity.Case C:(24)(25)(26)(27)Equation (24) is the opposite case of Eq. (19). Equation (25) compares the boiler and the gas turbine regarding the steam production, which is related to the mode d. In the case C, the oil cos t for the boiler is cheaper than the gas cost for the gas turbine to produce a certain quantity of steam. If the gas cost is cheaper, mode d is not a candidate for the optimal sol ution, as illustrated in the case C’. Equations (26) and (27) evaluate the effectiveness of the steam turbine and the inlet air cooling by the absorption chiller,resp ectively. The grid electricity is superior to the steam turbine and to the inlet air cooling in this case.Case D:In addition to Eq. (25),(28)(29)(30)Similarly to the case C’, the case D’ occurs if the inequality sign of Eq. (25) is reversed. Equation (28) is the opposite case of Eq. (22), which is the comparison of the electricity production between gas and oil. Equation (29) is the opposite case of Eq. (26), which is the comparison of the steam turbine and grid electricity. The gas cost to produce a certain quantity of electricity by the combination of the gas turbine and the steam turbine is cheaper than the purchase cost of the same quantity of electricity from the grid. Equation (30) gives the condition where the steam turbine is more advantageous than the inlet air cooling by the absorption chiller. The left hand side of Eq. (30) represents an additional steam required for a certain quantity of electricity production by the inlet air cooling. Therefore, Eq. (30) insists that the steam required for a certain quantity of electricity production by the steam turbine is smaller than that requiredfor the same quantity of electricity production by the inlet air cooling in this case, and it is independent of energy prices.Case E:In addition to Eq.(25),(31)(32)The case E’ occurs if Eq. (25) is reversed. Equations (31) and (32) are the opposite cases of Eqs. (27)and (30), which give the conditions where the inlet air cooling is more advantageous compared with the alternative technologies. In this case, Eq. (28) is always satisfied because of Eqs. (21) and (32).The conditions discussed above can be arranged using the relative electricity price, Pe/Pg and the relative oil price, Po/Pg. The optimal cases to be chosen are graphically shown in Figure 3 on the Po/Pg-Pe/Pg plane. When Eq. (30) is valid, Figure 3 (a) should be applied. The inlet air cooling is not an optimal option in any case. When Eq. (32) is valid, the cases E and E’ appear on the plane and the steam turbine is never chosen, as depicted in Figure 3 (b). It is noteworthy that if the inlet air cooling cannot improve the gas turbine efficiency, i.e. βGT = 0, the inlet air cooling is never the optimal solution.As the cases C, D and E include three operation modes, another criterion for the selection of the optimal operation mode is necessary in those cases. The additional criterion is related with the steam to electricity ratio, and can be derived from the consideration below.In the c ases C, D and E, λ1 and λ2 have positive values. Therefore, two of the constraints given as Eqs. (6) and (7) take the equality conditions due to the Kuhn-Tucker condition Eq. (12). Then, the two equations can be solved simultaneously for two variables which have positive values at each mode.For the mode d, the simultaneous equations can be solved under xGT, xB > 0 and xG, xST, xAC = 0.Then, one can obtain xGT = xe and xB = xs ¡ ρGTxe. Because xB has a positive value, the following condition has to be satisfied for the mode d to be selected.(33)At the mode e, one can obtain xG = xe ¡ xs/ρGT and xGT = xs/ρGT, and the following condition can be drawn out of the former expression because xG is greater than zero at this mode.(34)Similar considerations can be applied to the cases D and E. Consequently, Eq. (33) is the condition for the mode d to be selected, while Eq. (34) is the condition for the modes e, f or g to be selected. Furthermore, it is obvious that the mode c has to be chosen if the steam to electricity ratio of the gas turbine is equal to the ratio of the heat flow rate of the steam demand to the electric power demand, i.e. ρGT = xs/xe.Equations (33) and (34) mean that when the steam to electricity ratio of the gas turbine is smaller than the ratio of the heat flow rate of the steam demand to the electric power demand, the gas turbine should be operated to meet the electric power demand. Then, the boiler should balance the heat flow rate of the steam supply with the demand. On the other hand, if the steam to electricity ratio of the gas turbine is larger than the ratio of the heat flow rate of the steam demand to the electric power demand,the gas turbine has to be operated to meet the heat flow rate of the steam demand. Then, the insufficient electric power supply from the gas turbine has to be compensated by either the grid (mode e), the steam turbine (mode f), or the inlet air cooling (mode g). There is no need of any auxiliary equipment to supply additional electric power or steam if the steam to electricity ratio of the gas turbine matches the demands.Figure 3. The optimal operation cases expressed on the relative oil price-relative electricity price plane (the operational condition I).2.4. The Optimal Solution where the Electric Power from the Gas Turbine is at the MaximumIn the operational condition II, the third constraint, Eq. (8), takes the equality condition and λ3 would have a positive value. Then, Eqs. (11) and (18) yields:(35)It is reasonable to assume that ρGT ¡ !AC ®GT > 0 and ωGT ¡ ¯GT ®GT > 0 in the case ofgas turbine cogeneration systems because of relatively low electric efficiency (¼ 25 %) and a high heat to electricity ratio (ρGT > 1.4). Then, the optimal solution cases c an be defined by a similar consideration to the operational condition I, and the newly appeared cases are illustrated in Figure 4. The cases F and G can occur in the operational condition II in addition to the cases A and B of the operational condition I. Similarly to the cases C’ and D’ of the operational condition I, the cases F’ and G’ can be defined where the mode h is excluded from the cases F and G, respectively.Figure 4. The optimal solution cases on the operational condition II.In the operational condition II, the conditions of the cases A and B are slightly different from those in the operational condition I, as given below.Case A:(36)(37)Case B:(38)(39)The conditions for the cases F and G are obtained as follows.Case F:(40)(41)(42)Case G:In addition to Eq. (41),(43)(44)The case s F’ and G’ occur whenthe inequality sign of Eq. (41) is reversed. Equations (36), (38),(40), (41), (42), (43) and (44) correspond to Eqs. (19), (22), (24), (25), (26), (28) and (29), respectively.In these equations, ωGT ¡ ¯GT®GTis substituted for ωGT, an d ρGT ¡ !AC®GTis substituted for ρGT.The optimal cases of the operational condition II are illustrated on the Po/Pg-Pe/Pg plane as shown in Figure 5. Unlike the operational condition I, there is no lower limit of the relative oil price for the optimal solution to exist. The line separating the cases F and G is determined by the multiple parameters.Basically, a larger ρGT or a smaller ωST lowers the line, which causes a higher possibility for the case G to be selected.Figure 5. The optimal operation cases expressed on the relative oil price-relative electricity price plane (the operational condition II).To find the optimal mode out of three operation modes included in the cases F or G, another strategy is necessary. The additional conditions can be found by a similar examination on the variables to that done for the cases C, D and E. In the operational condition II, three variables can be analytically solved by the constraints given as Eqs. (6), (7) and (8) taking equality conditions.In the mode g, only two variables, ωGT andωAC are positive and the other variables are equal to zero.Therefore, the analytical solutions of those in the operational condition II can be obtained from equations derived from Eqs. (6) and (7) as xGT = xe and xAC = (ρGTxe ¡xs)/ωA C. Then the third constraint gives the equality condition concerning xs/xe and XGT/xe as follows:(45)where, XGT/xe represents the ratio of the gas turbine capacity to the electricity demand, and XGT/xe ·1.For mode h, the condition where this mode should be selected is derived from the analytical solution of xB with xB > 0 as follows:(46)For the mode i, xG > 0 and xAC > 0 give the following two conditions.(47)(48)For the mode j, xST > 0 and xAC > 0 give the following conditions.(49)(50)The conditions given as Eqs. (45–50) are graphically shown in Figure 6. In the cases F and G,the operational condition II cannot be applied to the region of xsxe< ρGTXGT xeand xsxe<(ωST+ρGT)XGTxe¡ωST,respectively, because xAC becomes negative in this region. The optimal operation should be found under the operational condition I in this region.3. Comparison of the Optimal Operation Criteria with a Detailed Optimization ResultTo examine the applicability of the method explained in the previous section to a practical cogeneration system, the combination of the suppliers selected by the optimal operation criteria was compared with the results of a detailed optimization of an existing plant.3.1. An Example of an Existing Energy Center of a FactoryAn energy center of an existing factory is depicted in Figure 7. The factory is located in Aichi Prefecture, Japan, and produces car-related parts. The energy center produces electricity by a combined cycle of a gas turbine and a steam turbine. The gas turbine can be fueled with either gas or kerosene, and it is equipped with an inlet air cooler. The electric power distribution system of the factory is also linked to the electricity grid so that the electricity can be purchased in case the electric power supply from the energy center is insufficient.The steam is produced from the gas turbine and boilers. The high, medium or low pressure steam is consumed in the manufacturing process as well as for the driving force of the steam turbine and absorption chillers. The absorption chillers supply chilled water for the process, air conditioning and the inlet air cooling. One of the absorption chiller can utilize hot water recovered from the low temperature waste gas of the gas turbine to enhance the heat recovery efficiency of the system.Figure 6. The selection of the optimal operation mode in the cases of F and G.3.2. The Performance Characteristics of the EquipmentThe part load characteristics of the equipment were linearly approximated so that the system could be modeled by the linear programming. The approximation lines were derived from the characteristics of the existing machines used in the energy center.The electricity and the steam generation characteristics of the gas turbine and the HRSG are shown in Figure 8, for example. The electric capacity of the gas turbine increases with lower inlet air temperatures. The quantity of generated steam is also augmented with lower inlet air temperatures.In practice, it is known that the inlet air cooling is beneficial when the purchase of the grid electricity will exceed the power contract without the augmentation of the gas turbine capacity. Furthermore, the inlet air cooling is effective when the outdoor air temperature is higher than 11 ◦C. A part of the operation of the actual gas turbine system is based on the above judgement of the operator, which is also included in the detailed optimization model.3.3. The Detailed Optimization of the Energy CenterThe optimization of the system shown in Figure 7 was performed by a software tool developed for this system. The optimization method used in the tool is the linear programming method combined with the listed start-stop patterns of equipment and with the judgement whether the inlet air cooling is on oroff. The methodology used in the tool is fully described in the reference [11].Figure 7. An energy center of a factory.Figure 8. The performance characteristics of the gas turbine and the HRSG.The Detailed Optimization MethodThe energy flow in the energy center was modeled by the linear programming. The outputs of equipment were the variables to be optimized, whose values could be varied within the lower and upper limits. To make the optimization model realistic, it is necessary to take the start-stop patterns of the equipment into account. The start-stop patterns were generated according to thepossible operation conditions of the actual energy center, and 20 patterns were chosen for the enumeration. The optimal solution was searched by the combination of the enumeration of the start-stop patterns and the linear programming method. The list of the start-stop patterns of the gas turbine and the steam turbine is given in Figure 9.The demands given in the detailed optimization are shown in Figure 10 as the ratios of the heat flow rate of the steam demand to the electric power demand on a summer day with a large electric power demand and on a winter day with a small steam demand. On the summer day, the ratio of the heat flow rate of the steam demand to the electric power demand is at a low level throughout a day. While, it is high on the winter day, and during the hours 2 to 6, the ratio exceeds 1.4 that is the steam to electricity ratio of the gas turbine.Figure 9. The start-stop patterns of the gas turbine and the steam turbine.The Plant Operation Obtained by the Detailed OptimizationThe accumulated graphs shown in Figures 11 through 14 illustrate the electric power supply and the heat flow rate of the steam supply from equipment on the summer and winter days. On the summer day, the gas turbine and the steam turbine worked at the maximum load and the electric power demand was met by the purchase from the grid for most of the day except the hours 2 to 6, at which the electric power demand was small. The inlet air cooling of the gas turbine was used only at the hours 10 and 14, at which the peak of the electric power demand existed. The steam was mainly supplied by the gas turbine, and the boiler was used only if the total heat flow rate of the steam demands by the process, the steam turbine, and the absorption。

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