文档介绍：华中科技大学文华学院
毕业设计(论文)
题目:300MW单元机组汽包水位控制系统分析、设计与仿真
学部(系): 机械与电气工程学部
专业年级: 09级热能与动力工程
300MW单元机组汽包水位控制系统分析、设计与仿真
摘要
锅炉给水控制系统是火力发电厂非常重要的控制子系统,稳定的汽包水位是汽包锅炉安全运行的重要指标。火电厂给水系统构成复杂,汽包水位受到机组负荷、汽包压力、温度、给水量等多项参数的影响:不同负荷阶段,给水设备不同,又需要采取不同的控制方式。目前使用的火电厂给水控制系统存在着各自的不足之处,往往难以满足火电机组复杂工况的要求。针对这些情况,为了保证汽包水位维持在要求值,本文首先分析了给水控制对象的动态特性,在此基础上设计出了采用汽动调速泵、电动调速泵、调节阀三者结合的汽包水位控制系统,低负荷时通过改变旁路调节阀的开度来调节给水量,用单冲量控制系统控制汽包水位;高负荷时通过改变给水泵转速改变给水量,用串级三冲量控制系统控制汽包水位,保证对汽包水位蒸汽流量和给水流量的准确测量。给水调节阀、汽泵、电泵之间,单冲量系统和三冲量系统之间都能实现无扰切换,既能满足机组全程控制要求,又有良好的调节性能和运行经济性。
关键词:锅炉给水控制;三冲量控制系统;单冲量控制系统
The Design Of Boiler Feedwater Control System Of The 300MW Thermal Power Unit
Abstract
Feedwater Control System is one of the most important control system in a thermal Power plant . Stabilization of the drum level is one of essential parameter which indicated safe operation of the drum boiler. Drum level is affected by the unit load, press and temperature of the drum, feedwater flux and etc. Because of using different equipment at different stages, it should apply different control methods. The effect of full range feed-water control system does not often be satisfied when power unit is in difficult situation because of its imperfect. In order to maintain the level of the drum water in requested value, Basing on analysis of feed-water character firstly, this system adopts timing which is moved by steam and electromotion-timing pump and adjusting valve. It utilizes bypass valves to regulate the feed-water and uses single impulse to control the level of drum in lower load. At the high load condition, change the rotating speed of steam or electricity feed water pumps to ensure the water level of the drum, using three impulse to control the level of drum .The level of steam and feed-water can be measured nicety. Non-disturbance switching can be realized among feed-water valves, steam and electricity driven pumps, single and three impulse. That not only meet the requirements of the whole-course control of the unit, but also ens