超临界锅炉水冷壁工质温度的控制

Control of Working Medium's Temperature Within Water Walls of Supercritical Boilers

分析了600 MW超临界锅炉下辐射区水冷壁出口工质温度与水冷壁安全性和汽温调节的关系。系统地分析了超临界压力下水和水蒸汽的热物性和在燃用不同煤质对下辐射区水冷壁出口和中间点工质温度的影响。指出水冷壁辐射传热量变化和工质热物性剧烈变化是决定水冷壁工质温度的主要因素,另外,还包括省煤器出口工质温度、蒸发系统的储热量、直吹式磨煤系统调节动态响应特性等。提出了超临界锅炉汽温调节和煤水比调节应注意的几个主要问题。

The relationship between the working medium＇ s temperature, at the water wall＇s exit, in the lower radiation zone of a 600 MW supercritical boiler and the water wall＇s operational safety, as well as its dependenceon steam temperature control, is being an＇,dyzed. Systematically analyzed too are the effects of the physical properties of water and steam,and of firing coals of different quality, on the working medium＇ s temperature at water wall＇ s exit in the lower radiation zone and on the centrum＇s temperature control. It is pointed out that changes in the water wall＇s radiationheat transfer,as well as severe changes in the working medium＇s physical properties, are the main factors that determine the working medium＇s temperature in the water wall,including the working medium＇ temperature at the economizer＇ s outlet, amount of heat stored in the evaporation system and the dynamic response characteristics of the direct fired coal mill system etc.. Some vital points to be heeded concerning steam temperature regulation and coal water ratio in supercritical boiler are mentioned. Figs 6 and refs 9.