600MW汽轮机旁路系统泄漏热经济性分析毕业论文.doc

分类号毕 业 设 计（论 文）题 目：600MW汽轮机旁路系统泄漏的热经济性分析 Title：Thermal economic analysis of 600 MW steam turbine bypass leakage摘要：旁路系统泄漏的安全性与经济性不容忽视，通过对600MW汽轮机热力系统高低压旁路泄漏的相关研究，从而定量分析对汽轮机组经济性影响的大小，指导现场机组的节能改造。正确认识旁路泄漏因素对机组热经济性影响的规律和热力学实质，指导机组热力系统正确运行和检修，提高电厂的运行水平。采用等效热降的方法定量分析热力系统能损的变化，以采取有效措施防止安全隐患的发生和热经济性的下降，使汽轮发电机组达到高效经济运行的目的。并提出一些应当引起电厂重视解决的问题，对如何提高电厂运行经济性给出了一些建议。关键词：旁路泄漏，等效热降，热经济性Abstract: leak bypass system security and economy can not be ignored, 600MW steam turbine thermal system high and low pressure bypass leakage study, and thus quantitative analysis of the size of the economic impact of the steam turbine unit to guide the scene unit for energy saving. Correct understanding of the bypass leakage on Thermal Economy of Unit rules and thermodynamics in real terms, the guidance of the correct operation and maintenance of the unit thermal system, improve the level of power plant operation. Equivalent enthalpy drop method for quantitative analysis of the thermal energy loss changes, to take effective measures to prevent the occurrence and the decline of the hot economy of the security risks, so that the turbine generator to achieve the purpose of efficient and economic operation. And should cause power plants pay attention to solving problems, and gives some suggestions on how to improve the plant operation economy.Keywords: bypass leakage, equivalent enthalpy drop, heat economy目录1 前 言12 高压旁路与低压旁路热力系统概述32.1 旁路系统的作用及类型32.2 旁路泄漏对汽轮机安全性和经济性的影响43 热力系统计算方法63.1 简捷计算63.2 等效热降94 汽轮机发电机组热力系统计算134.1 抽汽份额的计算134.2 抽汽等效热降及抽汽效率184.3 旁路泄漏的经济性分析205 结论27致 谢28参考文献29关于汽轮机的英汉对照301 前 言电力工业是国民经济的重要基础产业，是国家经济发展战略中的重点。随着国民经济的快速发展，电力需求日益增长，但由于能源问题的日益突出，使开发新的节能技术，提高能源的利用效率变得尤为重要。节能减排是我国能源战略和政策的核心。火电厂既是能源供应的中心也是资源消耗及环境污染和温室气体排放的大户，提高电厂设备运行的经济性和可靠性，减少污染物的排放，已经成为世人关注的重大课题。热经济性代表了火电厂的能量利用、热功能转换技术的先进性和运行的经济性，是火电厂经济性评价的基础。因此，对汽轮机热力系统进行经济运行特性分析就成了一个必要的课题。即是通过各种计算，查找对热经济性影响的原因，并研究制定出相应的措施来提高经济性。随着当前国内电力需求的增加和国内制造能力的提高，高参数、大容量的600MW机组已经逐渐成为我国电力建设中的主力机组。电网负荷的增长以及每天及季节性的电力负荷的变动，调峰负荷也越来越大，这就要求大机组不仅要从本身的设计和结构上考虑周期运行的特点，还要设置合适的旁路系统，以改善机组的安全性、灵活性和负荷适应性。旁路系统是汽轮机中不可缺少的组成部分。但机组运行中 ,若高低压旁路门关闭不严(泄漏 ) ,就会有部分给水走近路 , 容易积聚凝结水，旁路阀突然开启时，会引起汽水冲击的危险。同时蒸汽的泄漏也会使机组的运行经济性下降。旁路泄漏表面上看并无工质损失,是一种潜在的现象 ,尽管泄漏程度不同，但普遍存在，容易被人们所忽视 ,所以有必要对其经济性定量分析进行探讨。要正确认识旁路泄漏因素对机组热经济性影响的规律和热力学实质，指导机组热力系统正确运行和检修。由文献4可知，等效热降法以其独特的特点，被广泛应用于机组热力系统经济性诊断分析及局部因素定量计算。2 高压旁路与低压旁路热力系统概述2.1 旁路系统的作用及类型首先旁路系统是指高参数蒸汽不进入汽轮机，经过与汽轮机并联的减温减压器，进入再热器或直接排入凝汽器的连接系统。它可以分为三类：高压旁路（）：新蒸汽再热冷段;低压旁路（）：再热蒸汽凝汽器;整机旁路（）：新蒸汽绕过汽轮机。 旁路系统的作用保护再热器，防止锅炉超压。回收工质和热量，降低噪音。协调启动参数和流量，缩短启动时间，减少汽机的寿命损耗。甩负荷时锅炉能维持热备用状态。汽机旁路系统的设计和选型对于大型火电机组非常重要，对于超临界机组更有重要意义。考虑不同类型旁路的技术特点及机组运行方式等多方面因素进行选择确定。汽机旁路系统是蒸汽中间再热机组热力系统重要组成系统之一。下面针对常见的旁路系统有所分析。2.2 旁路泄漏对汽轮机安全性和经济性的影响 600MW汽轮机旁路系统图2.1高压旁路阀在机组正常运行时，处于热备用状态，要求旁路阀入口处的温度比主蒸汽温度低100150。在安全性方面分析，若高于此温度，说明旁路阀有蒸汽泄漏，则旁路阀快速开启时，热冲击太大。当减温水泄漏时，低于此温度则容易积聚凝结水，旁路阀突然开启时，会引起汽水冲击的危险。在经济性损失方面，高旁泄漏减少了进入汽轮机高压缸的高品质蒸汽，反映在经济上就是增加汽耗率和煤耗，自然循环效率也下降了。因此旁路泄漏的原因及定量分析对于现场也有这一定的指导意义。高压旁路阀内漏较大的原因：阀门密封面所受紧力不敷。在安装进程中，呈现“机械零位”和“热工零位”重合的现象，或热工零位断定后，呈现阀门密封面紧力不足，导致阀门内漏；阀座下垫片紧缩量过大。在运行进程中，可能呈现垫片变形过大，这也是导致阀门密封面紧力不足的一个间接原因；阀座变形。假如阀座下垫片变形量过大，可导致阀座密封面变形，引起阀门内漏；安装工艺呈现题目。如：阀座下垫片及阀芯垫片装得不正；厂家在对阀座、阀芯密封面破坏部门进行补焊时，焊接材料硬度不敷或焊后呈现变形，致使阀杆、阀芯同轴度超标。低压旁路系统也存在内漏问题,由于该泄漏蒸汽为再热蒸汽,因此泄漏直接减少中压缸和低压缸做功,使凝汽器热负荷增加,提高了机组背压,增加机组热耗。低旁内漏同样对机组安全性、经济性有这重大的影响通过上述的简单介绍，对旁路系统有了一定的认识。下章将详细介绍它在现场中的应用。3 热力系统计算方法3.1 简捷计算3.1.1常规计算热力系统常规计算的目的，在于确定热力系统各部分蒸汽或水的参数及流量，机组的功率和热经济指标。热力系统常规系统计算的方法有两种：一是定功率计算，即功率给定后求解汽耗量；另一种是定流量计算，即预先给定或估计蒸汽消耗量，求解功率或逐步逼近给定功率。3.1.2 简捷计算简捷计算是在改进常规计算的过程中逐步完善形成的。它在计算方法和计算技巧上，对常规计算做了一些改进和加工。首先在原始资料整理上进行改进，把热力系统中繁多的热力参数整理为三类：其一是给水在加热器中的焓升，以表示，按加热器编号有，；其二是蒸汽在加热器中的放热量，用表示，按加热器编号有，以及其它汽源的放热量等；其三是疏水在加热器中的放热量，用表示，按加热器编号有。以图3.1系统为例，可将各种原始数据整理为:式中一公斤水在加热器j中的焓升千焦耳/公斤； 一公斤加热蒸汽在加热器j中的放热量千焦耳/公斤一公斤疏水在加热器中的放热量千焦耳/公斤 加热器的出口水焓千焦耳/公斤加热器的抽汽焓千焦耳/公斤 图 3.1加热器分为两类：一类称疏水放流式加热器，它们属面式加热器，其疏水方式为逐级自流；另一类称汇集式加热器，它们是指混合式加热器或带疏水泵的面式加热器，其疏水汇集于本加热器的进口或出口。在整理原始数据时，根据加热器的类型不同，其加热器的、的计算规定也各不相同。对疏水放流式： 对汇集式加热器： 图3.2疏水放流式 图3.3汇集式加热器 抽汽份额汇集式加热器的热平衡方程为： 加热器的质量方程为： 由以上两式得： 式中 进入加热器的疏水份额若令 即简捷计算的规定，则： 汇集式加热器的抽汽份额就可以直接求得简捷计算须知计算中所用的加热器出口水焓，在带疏水泵的汇集式加热器中，是指混合后的焓值，而不是混合前的焓值。为了使计算简明，计算时把系统的各种附加成分，如轴封加热器的利用、抽汽加热器、轴封加热器、泵的焓升以及外部热源的利用，分别归入相应的加热器内。其归并的原则是以相临两个加热器的水侧出口为界限，凡在此界限内的一切附加成分都归并到界限内的加热器中。附加成分的脚码标注应与加热器一致。综上所述，简捷计算在本质上与热力系统的常规计算并无区别，但在计算形式和方法上作了一些技巧性的改进，从而收到了简单、明了的效果。3.2 等效热降3.2.1 什么是等效热降对于纯凝汽式汽轮机，一公斤新蒸汽的作功就等于它的热降（即焓降）。千焦耳公斤而对于有回热抽汽的汽轮机，一公斤新蒸汽作功式中抽汽作功不足系数抽汽份额显然，它比纯凝汽新蒸汽热降要小，它与纯凝汽式汽轮机的热降又类似，它们都是一公斤新蒸汽的实际作功，为了有别于纯凝汽式汽轮机的热降，故称这个作功为等效热降。3.2.2 等效热降法的应用等效热降法是基于热力学的热功转换原理，考虑到设备质量、热力系统结构和参数的特点，经过严密地理论推演，导出几个实际热力参量及等，用以研究热功转换及能量利用程度的一种方法。等效热降法主要用来分析蒸汽动力装置和热力系统。在火电厂的设计中，用以论证方案的技术经济性，探讨热力系统和设备中各种因素的影响以及局部变动后的经济效益，是热力工程和热系统优化设计的有利工具。对于运行电厂，可用等效热降法分析技术改造，分析热系统节能技术改造，可为改造提供确切的技术依据。新蒸汽做功的计算：对于凝汽式汽轮机，显然，一千克新蒸汽的做功就等于它的热降。 式中蒸汽进汽轮机的初焓； 汽轮机排汽焓对于有回热抽汽的汽轮机，一千克新蒸汽做功式中；抽汽份额；抽汽作功不足系数；r任意抽汽级的编号；Z抽汽级数；等效热降 由上看出，回热抽汽的作功不是1新蒸汽的简单热降，它比纯凝汽新蒸汽热降小。但是，它与纯凝汽式汽轮机中的H又类似，它们都是1新汽的实际作功。为了有别于纯凝汽热降，故称这个作功为等效热降。等效的数量是指回热抽汽式汽轮机1蒸汽的作功，等效于新蒸汽直达冷凝器的热降，即等效热降。3.2.3 抽汽等效热降 抽汽等效热降，在抽汽减少情况下，表示1排挤抽汽作功的增加值；反之，抽汽量增加时，则表示作功的减少值。计算公式的规律是，从一公斤抽汽的焓降（）中减去某些固定成分，可归纳为: 千焦耳/公斤式中取或者，视加热器形式而定，见下面规定；加热器后更低压力抽汽口角码。如果为汇集式加热器，则均以代之。如果为疏水放流式加热器，则从以下直到（包括）汇集式加热器用代替，而在汇集式加热器以下，无论汇集式还是疏水放流式加热器，则一律以代替上面讲的计算等效热降从冷凝器开始，由低向高逐级计算较为便。如若掌握了解了等效热降之间的关系，将使它的计算更为简捷。可由已知的等效热降去求取更高抽汽级的等效热降。疏水放流式加热器与其后相邻加热器之间的等效热降关系汇集式加热器之间的等效热降关系（锅炉与除氧器之间）3.2.4 抽汽效率 抽汽效率是作功与加入热量之比。这里排挤1抽汽，需要加入的热量为，而排挤1抽汽获得的功为。因而，对之比是一个热效率的含义。它反映任意抽汽能级处热变动的程度，和该能级以下（由于加入热量引起）的一切作功变化，即 4 汽轮机发电机组热力系统计算4.1 抽汽份额的计算4.1.1数据整理机组设计参数：机组型号:N600-24.2/566/566汽轮机型式：超临界、单缸、三缸（高中压缸合缸）、四排汽、一次中间再热凝汽式。蒸汽初参数：，各抽汽焓如下图所示：图4.1各抽汽焓及轴封参数见表4.1根据热力参数，按简捷计算方法规定整理原始资料得：图中共八台加热器，其设置如下：汇集式加热器： No.5疏水自流式加热器：No.1、No.2、No.3、No.4、No.6、No.7、No.8其中，为小汽机抽汽量。 1)给水在各加热器中焓升()2）疏水在各加热器中的放热量 3）蒸汽在各加热器中的放热量4）抽汽系数的计算 4.1.2正平衡计算再热蒸汽份额：一公斤再热蒸汽吸热量：一公斤新蒸汽的膨胀内功：再热前：再热后：循环吸热量：实际循环效率：热经济指标计算毛经济指标A. 汽耗量B. 汽耗率C. 热耗率半净经济指标A. 汽耗量 B. 汽耗率C. 热耗率4.2 抽汽等效热降及抽汽效率新蒸汽毛等效热降新蒸汽的净等效热降表4.2器热加据数象对各加热器焓升疏水放热量抽气放热量抽气系数各加热器效率#1105.7102.42319.70.028867.156%#293.9942350.30.0277412.410%#381.581.62375.40.0246716.801%#4168.22527.10.0512724.482%#5178.8227.82613.90.0530130.938833%#6125.4130.12599.50.0414636.6082515%#7169.6178.720340.0783953.4900%#81101936.40.0568155.412875%4.3.旁路泄漏的经济性分析 4.3.1 高压旁路泄漏的分析与计算高压蒸汽旁路阀泄漏泄漏部分流经旁路，经阀节流，其焓不变，相当于循环吸热量减少。等效热降减少： 循环吸热量减少：热经济性下降：机组热耗率增加：机组煤耗率增加：高压旁路1%的蒸汽泄漏量的计算：60万：入口24.2Mpa，566，667t/h.高压旁路的减温水从给水泵出口分流流过高压加热器的水减少，抽汽减少，抽汽的热经济下降，再热器吸热量减少。减温水从给水泵出口流出，泄漏份额，由于不经过高加及其产生的汽流不经过汽轮机的高压缸，故少做功：循环吸热量的下降，分三部分：由于的减温水本来是要加热到新蒸汽焓的，此时加热到了再热器冷段，故少吸的热量为。减温水不流经高压加热器而使循环吸热量增加的部分高加抽汽减少，进入再热器流量增大而使再热器吸热量增加高压旁路1%的减温水泄漏的计算：再热器的吸热量：高压旁路阀蒸汽泄漏，减温水开启，如图4.2图4.2高压旁路减 温水混合根据物质平衡与能量守恒：1kg蒸汽需要减温水，蒸汽需要减温水少做功循环吸热量减少：热效率相对降低：1%的蒸汽泄漏时，减温水自动动作，的份额高压旁路数据1%蒸汽泄漏量1%的减温水1%的蒸汽泄漏时，减温水自动动作的变化量（）-4.186-2.2102-4.61124的变化量（）-4.186-0.701417-4.051047的变化量-0.1621%-0.1928%-0.1993%4.3.2 低压旁路泄漏的分析与计算（1）低压旁路蒸汽泄漏再热蒸汽泄漏部分流经旁路至凝汽器，不经过中、低压缸做功，故等效热降减少： 循环吸热量减少：热效率相对降低： 当低压旁路蒸汽泄漏1%时的计算，=2316.6（2）低压旁路减温水泄漏时:由于低旁减温水从凝结水泵出口抽出，经过一个循环再次回到凝结水泵出口，但是其焓值减少，未在1号加热器内利用，从而1号加热器的抽汽增加，由于增加的抽汽未在汽轮机膨胀做功而使蒸汽的等效焓降减少。循环吸热量变化，由于凝结水量和给水量没发生变化，所以循环吸热量不变：热经济性相对变化：当低旁减温水泄漏量时：由工程热力学附录表查知，由插值法，当P=0.0049MPa时，（3）低压旁路压力调节阀泄漏，减温水开启时混合图4.3低压旁路减温水的混合1kg的蒸汽泄漏量需要的减温水量,根据物质平衡与能量守恒：蒸汽的泄漏量为时，减温水量为60万机组低压旁路减温减压后的设计压力：0.8MPa，设计温度：171，可知=2768.则循环吸热量变化： 热经济性相对变化：低压旁路数据1%蒸汽泄漏量1%的减温水1%的蒸汽泄漏时，减温水自动动作的变化量（）-12.802-0.005700942-12.803128的变化量（）000的变化量-0.9748%-0.0004299%-0.9748919%5 结论高压旁路泄漏计算分析结论：（1）当高压旁路蒸汽泄漏1%时，热经济性下降0.1621%；（2）当高压旁路减温水泄漏1%时，其经济性下降0.1928%；（3）当高压旁路蒸汽泄漏1%时，减温水自动动作，减温减压至再热冷段的设计焓值，其经济性下降0.1993%，比前两种情况的热经济下降更大。总之，高压旁路的任何泄漏，对经济性的影响是不容忽视的，其潜在安全隐患也值得注意！低压旁路泄漏计算分析结论：（1）当低压旁路蒸汽泄漏1%时，热经济性下降0.9748%，远远大于高压旁路的泄漏影响；（2）当低压旁路减温水泄漏1%时，其经济性下降0.0004299%，与高压旁路减温水泄漏相比，经济性几乎没有影响；（3）当低压旁路蒸汽泄漏1%时，减温水自动动作，减温减压至凝汽器的设计焓值，其经济性下降0.97488919%，其对经济性的影响仍然比高压旁路泄漏影响大，且比前两种情况也大。总之，低压旁路的每一次泄漏，对经济性的影响是十分大，在现场中应严格避免！致 谢本论文是在导师XXXXX副教授的悉心指导下完成，经过X老师多次地审阅本文，提出许多修改意见，对提高论文质量起到了至关重要的作用。衷心地感谢老师以及本组的同学对我在毕业设计过程中的无私帮助。尤其感谢导师在理论方面的指导，使我们学到了从未接触的新知识。在大学学习期间，还得到了动力系各位老师的帮助，尤其得到了热动及集控教研室的老师的大力支持，在此表示深深的感谢!参考文献1 杨义波 张燕侠.热力发电厂.中国电力出版社.20102 尚玉琴.工程热力学.中国电力出版社.2010 3 林万超.火电厂热系统定量分析.西安交通大学出版社.19854 林万超. 等效热降及其在火电厂的应用.电力科技通讯.1983 5 李新国.热动专业英语.郑州电力高等专科学校.2011关于汽轮机的英汉对照ENGLISHSTEAM TURBINEThere are two kind of thermal turbo-generator sets for conventional power generation usage , namely the gas turbine and the steam turbine generator is applied more frequently in thermal power plants in our country . Steam turbine is composed of two parts , i.e. a stator and a rotor for the stator , it mainly includes diaphragms , cylinder , shaft bearing bushes , and steam seal strips . The rotor mainly includes main rotor shaft , a shaft gland , blade wheels , blades and a coupling . A steam turbine system operates by converting the thermal energy of steam energy into kinetic energy into kinetic energy and then into mechanic energy . when the steam passes through the muzzles fitted on the diaphragms , the steam expands , and the steam pressure decreases and the flow speed increases . It completes the conversion of the thermal energy of the steam into kinetic energy . After the steam changes its flow direction in the nozzles , it is sprayed to the moving blades and its speed decreases among the blades . Thus it produces a thrust to the blades and makes the wheel rotating . Then the conversion process of steam kinetic energy into mechanic energy is completed . Steam turbines are generally classified into two groups , impulse and reaction . In impulse turbines steam expands in stationary nozzle to attain a high velocity and then flows over the moving blades , converting some of its kinetic energy into mechanical work . In reaction turbines steam expands both in stationary nozzle and moving blades . The relative amount of expansion between them varies from one design to another . In practice , however , the turbines used in power generation always have both impulse as well as reaction section . Figure 13 simply shows a typical steam process of a 350MW turbine . The live steam enters the Hp turbine through the stop valves and the control calves . After expansion in the HP turbine through , the steam passes to the reheater and the HP feedwater heater 7 . The reheated steam enters the IP turbine through the intercept stop valves and the intercept control valves . From the IP turbine exhaust , the steam flows through the cross over pipe to the LP turbine . At the LP turbine exhaust , the expanded steam flows into the condenser , and the resulting condensate in fed back into the steam water cycle .The condensate pumps force the condensate through the low pressure feedwater heaters(1-4) , which are fed with steam from extractions on the LP and IP turbines . thereafter , the condensate enters the deaerator/feedwater tank which is fed with steam steam from extraction 5 on the IP turbine . From the deaerator , the feedwater is pumped back to the boiler by the feedwater pumps via the high pressure feedwater heater (6-7) which are fed with steam form the extraction on the IP and HP turbine respectively .The turbine , together with its boiler , is equipped with a bypass system . The HP-bypass system between the boiler outlet and cold reheat consists of an HP-bypass control valve, a feedwater stop valve and a water injection valve, for steam attemperation .The LP-bypass system between the reheat outlet and condenser consists of a control valve, stop valve, steam dumping device with water injection control valve and associated control system.The HP-bypass reduces the live steam to the conditions prevailing in the reheater , and correspondingly the LP-bypass reduces the reheat system to the condition prevailing in the condenser . Thus , with certain limits , the bypass system enables the boiler to run independently in a closed system , without and steam being admitted to the turbine .Steam turbines have many stages , each of which generally consists of one row of stationary nozzles and one row of moving curved blades . Each stage can only convert a certain amount of thermal energy into mechanical work . So in the power plant multistage turbines are adopted .Steam turbines capacity ranges from a few kilowatts to over 1,000MW . Inlet pressure ranges from a few pounds above atmosphere to the supercritical and temperatures from the saturated to over 1,000F . Speeds for generator drives are 3.600 and 1.800 rpm , while those for gears units can be 10,000rpm or higher .To achieve a high capacity , a turbine may need more than one casing or one shaft . Figure 15 indicates typical arrangements of large condensing turbines .The arrangements a and b are often referred to , respectively , as the tandem-compound two flows and tandem-compound four flows . The arrangements c and d are so called cross-compound two flows and four flows .In general , the cross-compound arrangements are only considered for high capacity machines .CONDENSERCondenserAs mentioned above , condenser is an important component in a power plant . In the condenser , the latent heat of the turbine exhaust steam is transferred to the cooling water is eventually dissipated to the atmosphere . This waste heat limits the thermal efficiency of modern steam power plants to around 40% . The condenser is generally designed to maintain an economic condenser pressure determined by the available cooling water temperature . The steam condenser is discharged from the condenser at a temperature not low than the steam saturation temperature . Also ， the steam condensate is recuperated from the condenser as pure distillate as required for the feed water heating system .The main types of steam condensers are water-cooled surface condensers , water-cooled contact condensers , and air-cooled surface condensers . The most efficient and frequently used is the water-coiled surface condenser ,which is discussed in the unit .Condensers may be single-pass or two-pass . Two-pass condensers have higher temperature rise and require greater heat transfer surface for equal performance of the single-pass . The two-pass condenser is generally more economic in a cooling tower application while the single-pass is frequently selected in normal river , lake ,or seacoast installation . Using more than two passes usually results in an uneconomical operation .Condensers may be either single pressure or dual pressure . Thermodynamically , the dual pressure is superior to the single pressure . However , economic factors must be taken into account in the design decision . The dual pressure condenser has flow and temperature rise characteristics comparable to a two- pass condenser but with an improved heat rate . Therefore , the dual-pressure condenser should be considered in all cooling water tower applications or for the power plant location where a high water temperature is expected . Also , the dual-pressure condenser has a greater improvement in plant heat rate over the single-pressure operation in the application using turbines with heavily loaded exhaust ends .The water box may be divided or nondivided . A divided water box separates the cooling water path at the condenser . It is recommended for installation where fouling from the debris in the water may require removal of one-half of the condenser . In addition this design will facilitate in the locating and plugging of leaking tubes . The water boxes are made of either steel or cast iron . Steel is less expensive and is acceptable for cooling tower and fresh water application . However , it must be protected against corrosion with a suitable coating material .In general , cast-iron water boxes are used for seawater services .The hot well of a condenser is designed to collect the steam condensate . The hot well volume ,expressed in minutes of condensate produced at maximum expected turbine throttle flow , should be at least one minute for installations with deaerating heater and storage tank , and three minutes for installations with closed feedwater heating train .During start-up and operation , high vacuum should be maintained in the condenser . That means the condensate water gathering at the low part of the condenser should be drained in time and the surplus steam which has not been condensed and the leakage air should also be ejected . Condensate water gathering in the hot well can be drained by circulating and condensate pumps .The air and the surplus steam can be ejected by steam-jet air ejector or water-jet air ejector .The working principle of the two types of ejector is the same . Figure 16 shows the working principle of a steam-jet air ejector .The steam-jet air ejector is composed of a nozzle , a mixing chamber and an expansion pipe . The working fluid is ejected into the mixing chamber through the nozzle . In the mixing chamber , the high speed working fluid carries air to the expansion pipe ,the steam or water air mixture changes their kinetic energy to pressure energy and then be discharged through the pipe outlet .汉语蒸汽轮机生产电能普遍使用的热涡轮发电机有两种，它们是燃气轮