国产300MW机组除氧器暂态过程试验研究

A TESTING STUDY ON TRANSIENT PROCESS OF DEAERATOR ADAPTED BY NATION-MADE 300MW UNITS

大型机组除氧器暂态过程一直是机组安全运行广为关注的问题。文中通过对某国产300MW机组在功率突变工况下,除氧器有关参数的测量和计算,利用热力学第一定律建立了除氧器热平衡方程,得出机组在该工况下给水泵不会发生汽蚀的结论。原因为供至除氧器的抽汽压力虽然下降,其他汽源的存在阻止了除氧器压力(给水焓值)的过快降低,给水泵密封水的回水引入前置泵入口,降低了该处水温,使下降速度较除氧水箱水温延缓的现象不明 显。指出该型设计的300MW国产机组除氧器的设计标高可以进一步降低,节省大量的土建投资。而对前置泵入口滤网的堵塞现象应引起充分重视。

The transient process of the deaerator fitted for a large capacity generating unit is a matter closing related to the power plant safety operation, and therefor, it has been generally concerned by now, this paper presents a method by using some relative values of the deaerator parameters measured to calculated a nation-made 300MW unit during its power output saltation, a heat balance equation for the deaerator has been established according to the First Law of Thermodynamics. The results of calculation show that in such case there is no cavitation on feed water pump. The reason is that when the extraction steam pressure falls down, here some other steam source inlet to the deaerator and increase immediately that prevent the pressure inside the deaerator from falling too fast and the back sealing water of the feed water pump inducts to the booster pump to reduce the feed water temperature, so that the phenomenon of temperature decay is faster then water in the deaerator container. All those processes are not prominent (i.e. smoothly). This leads to a conclusion that the design elevation of deacrator may by lowered more, it can give a great deal of construction investments-saving and the congestion phenomenon in booster pump intake should be greally emphassiged.