大型燃煤电站汽轮机排汽通道结构优化研究

Study on Structure Optimization of Exhaust Steam Passage of Steam Turbine in Large Coal-fired Power Station

针对河北某电厂600 MW湿冷机组,运用ANSYS Fluent软件对汽轮机排汽通道流场进行数值模拟。研究发现:在原设计下,由于排汽缸轴向排汽及凝汽器接颈存在扩散角,排汽通道内出现了较大的低速漩涡区域,对凝汽器换热性能具有负面作用,而给水泵汽轮机排汽对低速漩涡区域具有一定的补充作用,能够一定程度上改善流场。针对这种现象,通过设计导流结构,对排汽通道流场进行了优化,结果表明:经过流场优化后,机组排汽在主凝结区最上层管束平面处的流速均匀性得到了显著提升,从而有利于提高凝汽器换热系数、降低机组背压、提升机组发电效率。

For a 600 MW wet-cooled unit of a power plant in Hebei province,ANSYS Fluent software was used to numerically simulate the flow field of the steam turbine exhaust passage.It was found that under the original design,due to the axial exhaust steam of the exhaust cylinder and the diffusion angle of the condenser neck,a large low-speed vortex area appeared in the exhaust steam passage,which had a negative effect on the heat transfer performance of the condenser.The exhaust steam of the feed water pump steam turbine had a certain supplementary effect on the low-speed vortex area and could improve the flow field to a certain extent.Aiming at this phenomenon,the exhaust passage flow field was optimized through the design of diversion structures.The results show that after optimizing the flow field,the crew exhaust steam condensed in the main area of the upper tube bundle planar velocity uniformity has been significantly increased,which is benefit to improve the condenser heat transfer coefficient,reduce the unit back pressure,and promote the efficiency of generating units.