双回路汽封系统方案设计与优势分析

Scheme Design and Advantage Analysis of Double-loop Gland Sealing System

针对一次再热、高中压分缸单分流机型热态启动过程中汽封供汽温度的特殊要求,文章提出了一种全新的解决方案——双回路汽封系统,两个完全独立的汽封回路(高温汽封回路和低温汽封回路),这种汽封系统能够在热态启动过程中向高中压缸前后汽封提供不同温度的供汽;能够在自密封前后减小低压汽封减温站来流的温度变化幅度,从而降低减温水流量变化范围,以维持雾化喷嘴的正常工作,通过确保减温水的完全蒸发,来实现低压汽封供汽温度的稳定;能够实现有差异的汽封母管压力控制,双回路汽封系统完全能够满足这类特殊机型的安全稳定运行要求.此外,两条汽封回路的汽封溢流可以接向不同的目的地,从而加大高温汽封回路溢流的热量利用率.

A new type gland seal system is proposed to meet the special requirement for steam supply temperature of steam seal during hot start-up on special steam turbine, for single reheated, HP&IP cylinders divided and one-way flow. That is defined as double-loop gland sealing system which contains of two completely independent gland circuits (high-temperature steam seal circuit and low-temperature steam seal circuit), two-way steam flows with different temperature can be provided dividedly to the front and the behind gland seal of HP&IP cylinders during the hot start -up process, temperature variation range of steam before desuperheating station can be decreased to reduce the variation range of desuperheating station water flow and maintain normol opeation of atomizing nozzle, and realize the stability of steam supply temperature of LP steam seal by ensuring complete evaporation of desuperheating water different seal pressure can be achieved in double-loop gland. Double-loop gland sealing system can be fully satisfied with requirement of the safe and stable operation for such special units. In addition, the overflow of two gland seal loop can be connected to different LP heaters, thus increasing the heat utilization of high-temperature gland seal circuit overflow.