考虑凝汽器压力的火电厂循泵出口阀启闭规律优化

当火电厂循环冷却水系统中发生水力瞬变时,凝汽器可能出现冷却水失水现象,这将导致凝汽器压力增高,从而影响汽轮机组运行的稳定性及安全性。循泵出口阀启闭规律的优化设定对凝汽器最大失水量能起到一定的控制作用。本文提出水力过渡过程计算结合凝汽器变工况计算的方法来优化设定阀门规律。经应用于300MW汽轮机组实例表明,采用该法确定的最优规律,凝汽器最小过流量从1.991m3/s增加到2.271m3/s,凝汽器最大压力从22.111kPa降低为16.911kPa。这样既能保证循环水系统的水力安全,又考虑了瞬变过程中凝汽器的动态特性,有利于汽轮机组的安全稳定运行。

Optimization of Open-close Mechanism of Circulation-pump Outlet Valves for a Thermal Power Plant with Condenser Operating Pressure being Considered

When a transient hydraulic change occurs to the circulation water system of a thermal power plant, the condenser may be subjected to a loss of cooling water, leading to an increase of operating pressure of the condenser, and thereby affecting the operating stability and safety of a steam turbine unit. The optimized setting of the open-close mechanism of circulation pump outlet valves can play a definite role in controlling the maximal water loss amount to the condenser. The authors have proposed a method for combining the calculation of a hydraulic transition process with that of the off-design conditions of the condenser to optimize the setting of the valve open-close mechanism. The practical application of the above method for a 300 MW steam turbine unit shows that under the optimized mechanism determined by the method, the minimal flow rate of the condenser has increased from 1.991 m3/s to 2.271 m3/s while the highest pressure of the condenser decreased from 22.111 kPa to 16.911 kPa. As a result, the hydraulic safety of the circulation water system has been ensured with a simultaneous consideration of the dynamic characteristics of the condenser during the transient process, thus contributing to a safe and steady operation of the steam turbine unit.