热能与动力工程毕业论文

热能与动力工程毕业论文题目：500MW机组给水泵选型、布置及不同驱动形式的经济性比较院（部）：热能工程学院专业：班级：姓名：学号：指导教师：完成日期：I目录摘要··································································ⅢABSTRACT·······························································Ⅳ1前言································································12给水系统的确定·······················································22.1单母管制系统··························································22.2切换母管制给水系统····················································22.3单元制给水系统························································33给水泵型号的选择·····················································53.1给水泵的扬程··························································53.2给水泵的配置··························································63.3给水泵流量的确定·····················································114CHTA型高压锅炉给水泵··············································134.1CHTA型高压锅炉给水泵的介绍·········································134.250CHTA/6型高压锅炉给水泵的性能曲线··································154.3CHTA型泵的监视和保护···············································164.4CHTA型泵的外形和安装尺寸···········································185给水泵入口静压力的计算·············································215.1除氧器的运行方式·····················································215.2滑压除氧器在机组负荷改变时的运行状况·································225.3给水泵入口静压力的确定···············································245.4防止给水泵汽蚀的方法·················································276给水泵的拖动························································306.1电动给水泵和汽动给水泵的选择原则·····································306.2给水泵驱动方式的确定·················································306.3小汽轮机的选择·······················································366.4小汽轮机的备用汽源···················································38II7结论··································································40谢辞····································································41参考文献·······························································42III摘要本文主要是为了确定500MW机组的给水泵型号、配置及驱动方式。目前在国内的10台500MW机组全部为进口机组，因此通过本设计可对500MW机组的国产化提供一定的参考。该机组的给水系统为单元制给水系统，给水泵采用了沈阳水泵厂引进西德KSB公司生产的CHTA型高压锅炉给水泵。通过对比国内600MW、660MW机组的给水泵配置方案，确定采用2台50%容量主给水泵作为长期运行使用，一台50%容量泵作为备用给水泵，在主给水泵出现故障时使用。运用定流量法比较了电动给水泵和汽动给水泵的热经济性，在保证主给水泵出现故障而不致影响机组负荷太多时，2台主给水泵小汽轮机驱动汽，备用泵为电机驱动。并简要分析了除氧器滑压运行时，汽轮机组负荷骤变对除氧效果、给水泵汽蚀的影响，提出了一些防止给水泵汽蚀的方法。关键词：500MW机组；给水泵；配置；驱动方式；汽蚀IV500MWunitfeed-waterpumpselection,arrangeAndeconomiccomparisonOfdifferentdrivingformAbstractThispaperistodeterminethefeed-water-pump’smodelof500MWunit,configurationandthedriveway.Thereareonly10setsof500MWunitscurrentlyinthecountryandtheyareallimportedunits.Therefore,thisdesigncanprovideareferenceforthelocalizationof500MWunits.Thefeed-water-pumpadoptstheCHTAtypehighpressureboilerfeedwaterpumpwhichisimportedfromGermanyKSBcompanybyShenyangwaterpumpfactory.Bycomparingthefeedwaterpumpconfigurationschemeofdomestic600MW,660MW,thisdesignadoptstwomainfeedpumpsof50%capacityaslong-termoperationaluse,apumpof50%capacityasbackupwhenthemainfeedwaterpumpbreakdown.Theelectricfeedwaterpumpandsteamfeedwaterpump'shoteconomywerecomparedbytheapplyingofconstantflowmethod.Ensuringtheunitloadatthefailureofmainfeedwaterpumps,thetwomainfeedwaterpumpsshouldbedrivenbysmallturbine,thebackuppumpadoptedmotordriven.Thepaperalsohasabriefanalysisabouttheeffctofdeoxidization,andtheinfluenceofthefeedwaterpumpcavitationwhendeaeratorslidingpressureoperating,alsoputsforwardsomepreventingmethodsofthefeedwaterpumpcavitation.KeyWords:500MWunit；feed-water-pump；configuration；drivemode；cavitationI-1-1前言能源是人类生存和发展的重要物质基础，攸关国计民生和国家安全。推动能源生产和利用方式变革，调整优化能源结构，构建安全、稳定、经济、清洁的现代能源产业体系，对于保障我国经济社会可持续发展具有重要战略意义。近年来，能源紧张成为困扰全球的难题。尤其是近几年来，我国火电厂的生产成本大幅增加。而另一方面，上网电价、热价增长有限，使火电厂利润下滑，甚至亏损。并且国家的宏观政策也发生了变化，提出了能源发展“十二五”规划、科学发展观、资源节约型、环境友好型经济、循环经济、绿色经济，把节约能源放在更加突出的战略地位，提倡减排降耗等。在这种背景下，作为国家发电的主力，火电厂应充分发挥自身能动性，在内部进行技术革新，进一步节能降耗，提高效益。其中，运用小汽轮机带动锅炉给水泵，其工作原理简单易行，可以节约电能，也更增强了锅炉运行的安全系数，是火电厂实施技术革新的一条有效途径。本文即对火电厂小汽轮机带动锅炉给水泵的热经济性作了简要的分析，并为500MW机组选择了合适的锅炉给水泵，为500MW机组的国产化提供了一点参考。-2-2给水系统的确定给水系统是发电厂热力系统的重要组成部分，给水系统的工质流量大，压力高，对发电厂的安全、经济、灵活运行至关重要，例如在任何工况下都要保证不间断地向过路供水。给水系统主要有以下几种类型[1]。2.1单母管制系统图2.1所示为单母管制给水系统，其特点是全部给水泵的供水汇集到一根母管上，即锅炉给水母管，再从该母管引至各台锅炉。其它两根母管分别是吸水母管、压力母管。吸水母管和压力母管均为单母管分段，锅炉给水母管为切换母管。其优点是安全可靠性高；缺点是阀门较多、系统复杂、耗钢材、投资大。适用于中、低压机组的小容量发电厂，或给水泵容量与锅炉容量不配合时，如高压供热式机组的发电厂应采用单母管制给水系统。该系统的备用给水泵多布置在吸水母管与压力母管的两串级分段阀之间。图2.1单母管制给水系统1—锅炉；2—高压加热器；3—除氧器；4—给水泵2.2切换母管制系统-3-图2.2所示为切换母管制给水系统，吸水母管是单母管分段，压力母管和锅炉给水母管均为切换制。其特点是有足够可靠性和运行灵活性。已建的电厂中，给水泵容量与锅炉容量匹配时采用，《设规》未再提这种系统，由于投资大、阀门多、钢材耗量也大，今后不再采用。图2.2切换母管制给水系统1—锅炉；2—高压加热器；3—除氧器；4—给水泵2.3单元制给水系统图2.3所示为单元制给水系统，其优点是没有母管，也没有切换阀门，系统最简单，系统本身的可靠性好。又由于没有母管，管线短，阀门数量少，不仅管道和阀门的投资费用小，而且相应的保温、支吊架的费用也减少。管线短，压损小，热损失少，检修工作量减少，因而运行费用也相应减少。另外，单元制系统也便于布置，并有助于采用煤仓间和除氧间合并的主厂房布置形式，使主厂房的土建等费用减少。缺点是单元制系统的灵活性（在不同工况下保证机组正常运行的适应性）较差。-4-为了提高机组的效率，大容量机组都是再热式机组，其工作参数高的大直径管道均为耐热合金钢管，价格昂贵，有的还要耗用大量外汇来进口，而单元制给水系统的管线短、阀门少，投资省的优点显得很重要。所以本机组的给水系统采用单元制给水系统。图2.3单元制给水系统1—锅炉；2—高压加热器；3—除氧器；4—给水泵-5-3给水泵型号的选择3.1给水泵扬程的确定本机组是超临界机组，锅炉为直流炉。其总扬程可按图3.1所示的给水泵连接系统简图来确定。给水泵的扬程，应为下列各项之和[2]：（1）锅炉额定蒸发量时的给水流量，从除氧给水