330MW亚临界热电联产机组冷端优化

The Optimization of Cold-end System in 330MW Subcritical Cogeneration Unit

热电联产机组负荷变动频繁、供热流量变化大,凝结式机组冷端模型不能有效指导现场生产。为此以330 MW热电联供机组为例,研究其冷端优化模型,分析影响真空度的关键因素,建立适合热电联供冷端优化数学模型,最后结合现场试验确定循环水泵最佳运行方式。研究结果表明机组最佳真空度受低压缸排汽量、循环水流量、循环水入口温度三个因素共同影响。当排汽流量较低时,两机两泵运行最优,随排汽流量上升两机三泵运行最优,继续提高流量两机四泵最优,循环水温度只影响最优运行方式变化范围,但不改变循环水流量随排汽量变化总趋势。此外新模型可集成在SIS系统上为电厂运行人员提供在线指导,对电厂节能降耗具有重要意义。

The electric load of the cogeneration unit changes frequently,and the heating supply changes greatly.The cold-end model of the condensing unit cannot effectively guide the on-site production.A 330 MW cogeneration unit as an example was taken,to study the cold-end optimization model,analyzing the key factors affecting vacuum,establishing a mathematical model suitable for cogeneration of cold-end optimization,and finally obtains the best operation mode of the circulating water pumps in combination with field tests.The research results show that the optimal vacuum of the unit is affected by three factors:the exhaust mass flow of the low-pressure cylinder,the water flow rate of circulatingpumps,and the circulating water inlet temperature.When the exhaust steam mass flow is less,the model of the two machines and two pumps is optimal.As the exhaust flow increases,the operation of the two machines and three pumps is optimal.Continually increasing the flow rate,the optimal performance is the two machines and four pumps.The temperature of the circulating water only affects the variant range of the optimal operation mode,not changing the general trend of circulating water flow with the variety of exhaust steam.In addition,the new model could be integrated on the SIS system to provide online guidance for power plant operators,which has a great significance for power plant energy saving.