大型湿冷机组排汽通道流场数值模拟与优化

改进汽轮机通流部分增加通流能力是提高火电机组热经济性的主要方式之一,而排汽通道是汽轮机通流部分的最后一段,因此,可以通过改善汽轮机排汽通道的流场来提高热经济性。运用ANSYS Fluent软件对600 MW水冷机组的汽轮机排汽通道流场进行数值模拟,发现在原设计下,由于小汽机排汽的冲击及贴近壁面处蒸汽流速高的原因,排汽通道出口速度的均匀性较差。针对这种现象,本文通过设计导流结构,对排汽通道流场进行了优化,结果表明:经过流场优化后,机组排汽通道在喉部出口的蒸汽流速的均匀性得到了显著提升,从而有利于提高凝汽器换热性能、降低排汽背压,实现深度节能。

Numerical simulation and optimization on flow field of exhaust channel of large water-cooled unit

Improving the flow passage of the steam turbine to increase its flow capacity is one of the main ways to improve the thermal economy of the thermal generator set, and the exhaust channel is the last section of the flow passage of the steam turbine. Therefore, the flow field of the steam turbine exhaust channel can improve improving thermal economy.In this paper,the ANSYS Fluent software is used to numerically simulate the flow field of the steam turbine exhaust channel of a 600 MW water-cooled unit. It is found that under the original design, due to the impact of the small steam turbine exhaust and the reason of the high steam velocity near the wall, the uniformity of the outlet speed of the exhaust channel is poor. In response to this phenomenon, this paper optimizes the flow field of the exhaust channel by designing a diversion structure. The results show that: after the optimization of the flow field, the uniformity of the steam flow rate at the throat outlet of the exhaust channel of the unit has been significantly improved. Therefore, it is conducive to improve the heat exchange performance of the condenser, reducing the back pressure of the exhaust steam, and achieving deep energy saving.