适于汽轮机多供热方式灵活运行的循环水泵优化改造方案

The Optimized Retrofit Scheme of Circulating Water Pump Suitable for Turbine Flexible Operation with Multiple Heating Mode

两台300MW抽汽机组采用低压缸切除方案进行灵活运行改造后,将存在纯凝、抽凝及背压3种运行工况,凝汽器进汽量与所需循环水量会出现大幅改变,原有循环水系统无法适应汽轮机的复杂运行工况。为此,根据电厂实际情况提出了3种循环水系统优化改造方案,通过投资预算、运行灵活性及节能效益等多方面的综合对比分析,得到了最佳的实施方案:汽轮机存在大抽汽量、复杂运行工况的循环水系统采用高低速泵改造方案,能够实现循环水与汽轮机变工况运行的适应性调节,且可避免出现机组真空降低或凝结水过冷度增大的问题,具有显著的节能、节水效应。

After the flexible operation of two 300MW extraction units with a low-pressure cylinder cut-off scheme,the unit will have three operating conditions:pure condensation,extraction condensation,and back pressure,and the condenser steam intake and required circulating water volume will be greatly changed.The original circulating water system can't adapt to this complex situation.Therefore,three optimization schemes of circulating water system are put forward,which are based on the actual situation,and through the comprehensive comparative analysis method,including investment budget,operation flexibility,and energy-saving benefits,the best implementation scheme is obtained:When the steam turbine has large extraction capacity and complex operation conditions,the scheme of high and low speed pump will be applied in circulating water system,which realizes the adaptability of circulating water adjustment and steam turbine off-design condition.At the same time,it can avoid the problems of unit vacuum reduction or condensate supercooling increasing.This method has a remarkable effect on energy-saving and water-saving.