余热锅炉中压给水安全门动作的原因分析及处理

Analysis and Treatment of MP Feedwater Safety Valve Operation in Waste Heat Boiler

某厂燃气-蒸汽联合循环机组起动时,其余热锅炉中压省煤器压力过高,造成中压给水安全门动作。通过分析中、低压系统的结构和运行情况,指出造成省煤器超压的原因是由于给水调门布置于省煤器之后,当机组起动时,中压汽包水位上升,使中压给水调门迅速关闭,省煤器给水大量吸热。提出了故障处理的思路是保持省煤器给水流动,具体实施措施是在中压省煤器疏水母管上加装电动截止门和汽动调门,并使中压给水调门关闭时仍有微小的开度。技术改造后的运行结果表明,中压给水压力未超过安全门动作整定值,达到预想效果。

During the startup of a gas-steam combined cycle unit in some power plant, the overpressure of the MP economizer in the waste heat boiler resulted in the operation of the MP feedwater safety valve. Upon structural and operational analysis of the MP and LP systems, the overpressure was deemed to be caused by the increased MP drum level during startup, which led to fast closing of the MP feedwater control valve located behind the economizer and the great heat absorption by the economizer feedwater. It was suggested that the economizer feedwater should be kept flowing. Accordingly, electrically operated stop valve and steam operated control valve were added to the drainage common header of MP economizer, and tiny opening was left after closing the MP feedwater control valve. Operation results thereafter show that the MP feedwater pressure is satisfactory.