外文文献原告和译文

北京化工大学北方学院
NORTH COLLEGE OF BEIJING UNIVERSITY OF
CHEMICAL TECHNOLOGY
（2011）届本科生毕业设计
外文文献翻译
题目：半干法烟气脱硫
—反应器的优化
学院：理工学院专业：应用化学
学号： 070105131 姓名：谷东亮
指导教师：孟献民老师
教研室主任（负责人）：顾明广老师
2011 年 5 月 18 日
外文文献原稿和译文
原稿
ABSTRACT
The TURBOSORP process is a dry flue gas cleaning system to remove pollutants like
,
,mercury,heavy metals, dioxins and furans, and dust. The main principle of this process is tobring flue gas into an intensive contact with calcium hydroxide, open hearth furnace coke, waterand recirculated material in the Turboreactor, which operates as a circulating fluidized bed in themanner of fast fluidization.
In 2000 AE&E started a development and research project with the aim to simulate the fluiddynamics of the Turboreactor with a commercially used CFD code. Starting with the developmentof the one-phase simulation the existing reactor geometry was optimized concerning the pressureloss. After this step research activities on a two-phase simulation (gas and solid flow) based on theconcept of Euler-Lagrange should help to better understand the mechanism of solid distribution inthe reactor and to calculate the part of the pressure drop of the fluidized bed depending on thesolids.
Among other things the recent results of the start-up phase of a TURBOSORP FGD-plant withoptimized reactor design are described in this paper. As a highlight the Turboreactor pressure losswas reduced by about 20 percent, compared to a conventional reactor design. INTRODUCTION
Today, the application of dry technologies for the cleaning of flue gases of power stations or wasteincineration plants is considered as the state-of-the-art technology. Due to the use of the fluidizedbed technology and of the recirculation of the partially reacted product it has
been possible toeliminate prejudices against this technology which were based upon a bad utilisation of the sorbentand low separation performances.
Because of the considerably reduced investment costs there is an important market potential for thedry technology in addition to the wet technology. Especially in the field of retrofitting and/orrehabilitation of existing plants the dry technology plays an important role.
Presently, various competitors offer dry processes on the market of which the differences in theprocess concept hardly can be discerned. In certain cases, the differences only exist in the planttechnology and in the design of the reactor. Nevertheless, the potential of optimisation aiming atfurther improved desulphurisation performances and at minimum consumption of consumables is not exhausted yet.
As state-of-the-art in the field of flue gas desulphurisation removal efficiencies up to 95 % at Ca/Sratiosup to 1.25 can be achieved with this technology without problems. Even in the field of fluegas cleaning after waste incineration plants the emission limits as prescribed by the 17th Decree ofthe German Federal Immission Act (17. BImSchV) can be achieved (see table
1
.
Table 1: Emission regulations for flue gases from waste incineration - Europe
Austrian Energy and Environment AG (AEE), emerged from the traditional companies WaagnerBiro AG and Simmering Graz Pauker AG, was reestablished in July 2002, after a short intermezzowith the German Babcock Borsig Power Group between 1999 and 2002. By way of theTURBOSORPÒ process AEE offers a dry technology for the flue gas desulphurisation and the fluegas cleaning after waste incineration plants. Because of the use of the most up-to-date design tools like e.g. CFD-modeling of critical plant components, AEE is able to provide an optimum design.Additionally, AEE operates a pilot plant where critical operating cases, as for example extreme fluegas compositions, can be simulated during
experiment
.
PROCESS TECHNOLOGY
In the TURBOSORPÒ process the flue gas flows through a cylindrical apparatus (fluidized bedreactor) from the bottom to the top. The bed material is made up of solids, consisting of calciumhydroxide, calcium carbonate, the solid reaction products of the flue gas cleaning process, and ashesfrom the combustion process. Fresh and active material, either Ca(OH)2 or CaO, is injected into thereactor while solids, that have already undergone several cycles are recirculated into the reactor(refer to Fig. 1). The term …cycle“ means a complete circulation of the sorbent particles through the
whole plant (Turboreactor, separator, buffering tanks that may be installe
.
In order to lower the flue gas temperature for achieving an increased desulphurisation capacitywater is injected horizontally or vertically, usually by means of a water nozzle, which is in thevicinity of the flue gas inlet. 6 In addition to the temperature reduction of the flue gas this also leadsto an increase in the relative humidity. Moreover, the wetting of the recirculated sorbents in thereactor makes new and reactive surfaces accessible at the solids particles as product layers whichwere already formed become detached again by this
wetting (refer to Fig. 2
.
Apart from this activation by means of the water injection a mechanical activation of therecirculated solids particles is also achieved by means of the turbulent flow in the fluidized bedreactor, as the solids particles collide with each other and with the wall. The operating state of thefluidized bed lies within the range of the so-called ²fast fluidized beds², i.e. within the transitionzone to pneumatic conveying.
The flue gas inlet of the Turboreactor is designed as a Venturi nozzle. Due to the high flue gasvelocities in the Venturi nozzle the collapse of the fluidized bed and the falling down of solidparticles through the Venturi nozzle is avoided.
After the outlet from the Turboreactor the solid particles are separated from the flue gas in
aseparator. When using the TURBOSORPÒ process for flue gas desulphurisation either electrostaticprecipitators or fabric filters, preferably with mechanical pre-separators, can be used. When using itfor the cleaning of flue gases of a waste incineration plant, only a fabric filter may be installed. Therecirculation of the separated material in the reactor can be made either pneumatically (fluidizing conveyor) or mechanically (screw conveyor). Fig. 3 shows the process flow diagram of theTURBOSORP process.
For the use of the TURBOSORPÒ process within the framework of the flue gas desulphurisationand/or in the field of gas cleaning after waste incineration plants not only the solids separator isdifferent but mainly the operating range of the process.
Fig. 4 shows the different applications for the TURBOSORPÒ process. Depending on the relationbetween SO2 and HCl there are three types of applications, the TURBOSORPÒ-FGD (flue gasdesulphurization), the TURBOSORPÒ-FGCB (flue gas cleaning after biomass boilers) and theTURBOSORPÒ-FGCW (flue gas cleaning after waste incinerators).
In the TURBOSORPÒ-FGD process the minimum operating temperature depends on the situationof the water dew point of the gas to be cleaned. It is recommended to maintain a minimum distanceof 20 to 25°C from the dew point, which prevents caking or agglomeration of the solids on the wallsin the Turboreactor. The content of chlorine in the flue gas is to be considered as well as thereaction product
, which is strongly hygroscopic, and may lead to caking andagglomeration.
For the use of the TURBOSORPO-FGCW process in the field of flue gas cleaning after wasteincineration plants the content of chlorine of the flue gas is higher than the content of SO2.Furthermore, in the TURBOSORPO-FGC process open-hearth oven coke (HOC) is injected inaddition to the sorbent containing calcium, which guarantees the separation of dioxins/furans aswell as the separation of the volatile heavy metals like mercury, cadmium, and thallium. In theTURBOSORPO-FGCB process the relation of
will be between the FGD and the FGCW.The typical range of the operation temperature can be found in Fig. 5. The exact temperaturedepends also on the relative humidity, the fly ash input into the process and the demandedseparation efficiency for the
.
The product of the TURBOSORPO-FGD process can be dumped in a landfill for non-hazardouswaste without further treatment. Stabilized product can also be used for special building purposeslike sound insulation or the final covering of landfills.
The product from the TURBOSORPO-FGBC or FGCW process can be dumped in a landfill fornon-hazardous waste only after a further stabilization which is required because of the mobilizationof the heavy metals that would occur otherwise.
CFD-SIMULATION
The design and optimization of circulating fluidized beds is still a challenging task. To get a betterunderstanding of the behavior of the multi-phase flow inside the reactor, the application ofComputational Fluid Dynamics (CFD) can be a helpful tool. For the optimization and theinvestigation of the TURBOSORPO process, a research project was started in the year 2000 incooperation of Austrian Energy and Environment and the University ofLeoben to perform CFDsimulationsof this process.
The following milestones were fixed for the research project:
·Development of a strategy to simulate the two-phase flow of solids and flue gases forengineering purposes.
· Consideration of the heat transfer between the solids and the gas.
· Extension of the model to describe the three-phase flow of gas, solids, and water.
· Modeling the evaporation of the water droplets and the drying of the agglomerates. Currently, the third point in the project schedule has been reached.
Theoretical background
We use the commercial CFD-Software FIRE 7.3, of AVL-List GmbH. The program is a generalpurpose CFD-software package and it uses the finite-volume method to simulate fluid systems. Thesolution domain is subdivided into a finite number of volume elements. To each volume element,the conservation equation for mass, momentum, energy and
additional parameters of the flow field(e.g. species concentration) are applied.
To take into account the turbulence of the gas flow, the k-e two-equation model is used.The description of the multiphase flow is based on the Euler-Lagrange approach. While the gasphase is treated as a continuous fluid, the solid particles and liquid droplets are represented by anumber of numerical particles. The motion of the numerical particles is calculated by solvingLagrangian equations of motions in accordance with Newton’s Second Law. The interactionbetween the continuous and the dispersed phase is considered by two-way coupling.
The application of the Euler-Lagrange approach to simulate multi-phase flow in circulatingfluidized beds is somewhat untypical, because it is valid only for dilute flows. Nevertheless, due tothe flow regime of fast fluidization up to pneumatic conveying and the very low overallconcentration of solids and water in the reactor, the assumption of a dilute flow is valid, except nearthe solids feed.
The advantages of this way of multi-phase flow modeling are the capabilities of a more detaileddescription of the properties of the dispersed phase like size distribution or inter-particle forces.For the application of FIRE, it was necessary to extend the code with usersubroutines for thedescription of particle-wall, particle-particle interaction, solids input and recirculation as well aswater injection. A routine for the modeling of the interaction of solids particles with the waterdroplets and the resulting formation of agglomerates is currently in the test phase.
译文
摘要
半干法烟气是一个用干燥的流体清洗系统来去除烟气污染物如二氧化硫、盐酸、氢氟酸、水银、重金属、二恶英和呋喃、尘土的脱硫过程。

这个过程的主要原理就是使干态的烟气与氢氧化钙在脱硫塔中充分接触,并且向脱硫塔中通入工艺水和循环料，同时使物料在脱硫塔内的循环床中呈现出快速流化的状态。

在2000AEE公司开始一项研究，该研究的目的在于模仿固体流态化并期望将其用于商业。

从现有的单相反应器几何仿真优化了关于压力的损失。

在进一步的研究后，建立上拉格朗日概念上的两相（气、固）机理，应该能够更好的帮助理解在反应中的固体分解机理以及在流化床中的压力降。

在本文章中阐述了半干法烟气脱硫的最新成果。

其中最突出的部分是该设计相比传统的工艺，其压力损失降低了。

介绍
当今，干法技术在清理来自发电站或是垃圾场的烟气方面的应用时最先进的工艺。

由于循环流化床技术的应用，就有可能消除各种对干法技术的偏见。

由于投资费用的大大降低，因此除了湿技术干法技术很有市场潜力。

特别是，在这一领域的改造和/或复原现有工厂的干燥技术中发挥着重要作用。

当今，不同的竞争对手在市场上提供了不同的干法工艺过程，由于过程的不同使得干法的概念难以被区别。

在某些情况下，这种不同只存在与车间以及反应器的设计中。

然后工艺的不同在于进一步的提高脱硫效率并且较少脱硫剂的消耗。

作为在脱硫工艺中的先进技术，干法脱硫在钙硫比为 1.25时就能达到
以上的脱硫率并且不会产生其他的不利问题。

实际在垃圾焚烧烟气的处理中，在满足德国制定的标准下就可以实现（如表1。

来源于圆珠笔公司的奥地利能源与环境公司，在2002年7月通过与德国巴布科克电力公司在1999年与2002的短暂协商后进行了重建。

通过半干法脱硫过程AEE
公司提供了一种干法脱硫技术。

由于使用了最先进的设计工具，比如CFD模拟工具，AEE公司能够提供最佳的设计。

初次之外，AEE公司组建了一个小型的工厂，该工厂
过
能够模拟实际的脱硫
工艺技术
在半干法脱硫过程中，烟气是从循环流化床的底部进入再上升到塔的顶部。

床的底料是由氢氧化钙和碳酸钙的固体颗粒，以及与烟气反应后产物颗粒。

当新鲜的氢氧化钙或氧化钙被注入反应器的时候反应器已经经历了周期循环（如图1）。

循环这个术语指的是颗粒在工厂中的整个流程（脱硫反应塔、气液分离器、缓冲器等都包括在
内
为了达到降低烟气的温度，以提高脱硫效率，通常向脱硫塔内加入工艺水，并且
现
工艺水的加入时通过水喷嘴实
表
图1 脱硫原理
除去用工艺水来活化在循环的固体颗粒，通过烟气在循环流化床中的湍流作用也可以活化在循环而来的固体颗粒，同时固体颗粒之间的相互碰撞以及颗粒与反应塔壁的碰撞也可以起到活化固体颗粒的作用。

该工作状态的流化床处于过渡范围内也就是所谓‘快速流化床范围’，即气力输送的范围。

图2 机制激活的循环吸附剂
烟气在进入流化床之前要首相通过底部的文丘里管。

由于在通过文丘里管后烟气的流速被大大的增加，这样就避免了固体颗粒由于重力作用而对脱硫塔的堵塞以及流化床床层的倒塌。

当固体颗粒从脱硫塔中出来之后，就在布袋除尘器中与烟气分离。

当使用半干法进行脱硫时，可以使用静电除尘器或者是纤维过滤器对烟气进行预处理，其中机械分离器预处理效果是最好的。

当半干法处理垃圾焚烧电厂的烟气时，只有纤维过滤器可以用作烟气的用于处理装置。

这种分离混合物的装置可以通过气力输送实现（沸腾输送机）也可以通过机械输送实现（螺杆输送机）。

图3展示了半干法脱硫的流程图。

图3 半干法烟气脱硫
在该结构框架中的烟气脱硫或者是半干法在废物燃烧厂烟气处理方面的应用，不仅有着不同的固体分离器，更重要的是办法在该领域有着不同的适用范围。

图4展示半干法脱硫在不同脱硫场所的不同过程。

根据烟气中二氧化硫和盐酸气体的不同比例，主要有三种脱硫方式：燃烧后烟气处理，燃烧前煤种处理以及垃圾焚烧烟气处理。

图 4 半干法烟气脱硫在不同脱硫实例中的应用在半干法烟气脱硫工艺中烟气的最低温度取决于烟气的酸露点，在这里我们建议烟气的最低温度要高出烟气酸露点20-25
，这样一方面可以防止固体颗粒的结块也可以防止固体在器壁上的粘连。

除此之外还要考虑烟气中氯元素的含量，因为由其生成的
，具有强烈的吸湿性，并由此可能导致固体颗粒的结块。

当半干法脱硫应用于垃圾燃烧后烟气的脱硫处理时，在烟气被净化之后烟气中氯元素的含量大于二氧化硫的含量。

更进一步的由于向平底炉中加入了含有钙的吸附剂，这样就保证了二恶英/呋喃以及如汞，镉，铊等重金属的分离。

在半干法脱硫过程中
之间的比例关系将决定是采用FGD还是FGCW。

其中操作温度范围可以在表5中查的。

烟气的确切进塔温度也依赖于烟气的相对湿度、烟气中粉尘的含量以及要求的脱硫效率。

表5 半干法的操作温度
半干法烟气脱硫的脱硫产物可以丢弃在垃圾场，并且不会造成环境的污染。

除此之外对于性质稳定的产品还可以用作特殊用途的建设，比如声音绝缘、堆填区的最终覆盖。

对与通过FGBC或者是FGCW而得到的产物要等其充分稳定后才可以无污染的排放到垃圾场，因为如果该类方法中的重金属在为稳定之前就会对环境造成污染。

计算机脱硫模拟
设计和优化循环流化床仍然是一个很有挑战性的工作。

为了更好的理解在脱硫塔内各物质的流动状态计算机模拟是一个很有帮助的工具。

为了优化和研究半干法烟气脱硫过程，在2000年奥地利能源与环境公司于莱奥本大学合作进行开展了以计算机模拟为研究手段的工程研究。

下面列举了本次研究的研究项目：
以战略发展模拟一个固气相的工程项目。

思考固气之间的热传递。

扩展两相模拟来描述三相模型，气、液、固的相态。

建立水滴蒸发和干燥的模型。

目前第三个研究项目已经完成。

理论背景
我们使用商业模拟软件FIRE 7.3以及有限体积法来模拟流体系统。

该技术又被分解为几个元素。

对每一个元素，对质量，动量，能量和流场及其他参数（例如物种的浓度）使用了守恒方程。

为了综合考虑烟气的湍动，我们采用了k-e方程所建立的模型。

在模型中，对于多相流的描述是建立在欧拉-拉格朗日方程的基础上的。

在模拟中气相作为连续相来处理，而固体颗粒以及液滴作为分散相即粒子来对待。

对于粒子的运动轨迹运用拉格朗日方程并结合牛顿运动定律进行了求解。

连续相和分散相之间的关系被认为是双向耦合的。

使用欧拉-拉格朗日方程式来模拟循环流化床中多相态的流动状态多少有点不准确，该方程式仅能够精确的描述稀相态的流体。

由于流体的硫化作用非常的迅速，并且在反应塔内固体颗粒的密度也非常的低，因此欧拉-拉格朗日方程式在该反应器中还是适用的，这里假设固体颗粒的体积普遍都较小。

利用这种方式所建立的多项流动模型，其优点是能够详细的描述分散相粒子的尺寸，或分布情况。

为了更好利用碰撞作用，来增加固体颗粒的比表面积、颗粒间的碰撞几率、固体颗粒的循环倍率以及工艺水的量。

同时为固体颗粒以及液滴之间的相互作用建立模型，结块形成的模型正在试验中。