660 MW间接空冷机组小汽轮机改造

Transformation of a small steam turbine for a 660 MW indirect air cooling unit

某超临界660 MW间接空冷机组在夏季高背压工况运行时,随着机组负荷的增加,主机四段抽汽驱动的小汽轮机不能满足给水泵轴功率的需求,出现了小汽轮机高压调节阀开度大、备用冷段再热汽源排挤主机四段抽汽的问题。通过分析运行参数和性能试验,确定了小汽轮机使用四段抽汽出力不足的原因,提出了增加30%通流面积的改造方案。改造实施后,小汽轮机的出力能力增加,机组夏季运行带负荷能力增强,煤耗下降了5.94 g/(kW·h),显著提高了机组的经济效益和运行安全性。改造方案对间接空冷机组小汽轮机的设计和选型具有借鉴意义。

Under the high back pressure working condition in summer,the unit load will increase.The small steam turbine of a supercritical 660 MW indirect air cooled unit drived by four-stage extraction steam could not meet the demand of feedwater pump shaft power.The opening of the small steam turbine high-pressure regulating valve was too large,and the spare cold reheating steam source impeded the four-stage steam.By analyzing operating parameters and performance tests,the reasons for the insufficient output of the four-stage extraction steam for the small steam turbine were determined.A reform scheme to increase 30%flow area of the small steam turbine was put forward.After implementation,the output capacity of the steam turbine was improved,and the load capacity of the unit was increased in summer,and coal consumption decreased by 5.94 g/(kW·h).The scheme is of reference meaning for the design and model selection for indirect air cooled units for its economic and safe benefits.