超临界600 MW直接空冷机组双背压供热改造技术

Double-backpressure heating flexible reformation technology for a supercritical 600 MW direct air cooling unit

火力发电厂的冷端损失是电厂热力系统的最大损失,如果汽轮机排汽余热能够充分回收用于供热,将大幅提高电厂的供热能力和能源利用效率,带来巨大的节能效益、环保效益与社会效益。本文通过朝阳燕山湖发电有限公司超临界600 MW直接空冷机组双背压供热节能改造技术的实践,论述了改造过程中汽轮机末级叶片、低压缸末级叶片、排汽管道系统、凝结水系统、抽真空系统、循环水系统、排汽装置热水井水位平衡系统、凝结水冷却系统、热网循环水二次加热等系统和设备可能存在的问题和改造方案,以及背压限制值、背压控制、空冷岛防冻、双背压运行的启动和退出、换热器泄露处理、凝结水降温系统设置、热网水出口温度等双背压供热系统相关的调控措施,最后从节能减排效果、运行安全性以及灵活性调峰等方面讨论了改造效果。结果表明,改造后机组运行稳定,节能效果显著。该双背压供热灵活性改造技术为火力发电厂灵活性改造提供了新的思路。

Cold end loss is the largest loss of thermodynamic system in thermal power plants.If the exhaust waste heat of steam turbine can be fully recycled for heating,it will significantly improve the ability of heating and efficiency of energy utilization for the power plant,and bring huge benefits such as energy-saving,environmental protection as well as other social benefits.On the basis of the double-backpressure heating energy saving reformation in supercritical600MW direct air cooling unit of Chaoyang Yanshanhu Power Generation Company,the possible problems and retrofit schemes of systems and steam equipments were discussed,like in the final stage blade of the furbine,the exhaust steam pipe system,the condensate water system,the vacuum pumping system,the circulating water system,the water level balance system of hot water well of exhaust unit,the condensate cooling system,and the secondary heating system of circulating water in hot networks.Moreover,the control measures related to the double-backpressure heating system were proposed,like the back pressure limit,back pressure control,air cooling island antifreeze,start-up and stop of double-backpressure operation,heat exchanger leakage treatment,setting up of condensate cooling system,and water temperature control at the heating network outlet.Finally,the retrofit effect was discussed from the aspects of energy saving and emission reduction effect,operation safety and flexible peak-shaving.The technology this article proposed provides a new way for thermal power plant flexibility reformation.