Flow Field Computing Techonlogy Of Fluent And Its Application In Power Plants

The direct air cooled system(ACC)was widely used because of its remarkable effect in saving water in the areas where are “rich coal but lack of water” or drought areas.While,during the time of hot summer days,When the ambient wind speed is not zero,especially when there are tall buildings in the upper reaches of the air cooled island,recirculation will be formed,recirculation can decrease the cooling ability of ACC,the back pressure of turbine increases quickly and seriously influenced safe operation of power plant.So,investigating the characteristic of thermal flow field around air cooling island,discussing on the influencing factors of recirculation,it will improve the heat dissipation performance and contribute to theoretical investigation and engineering application.In this paper,the physical model of the tall building of the power plant is established by using the 3D modeling function of CAD,using Gambit software to divide grid of calculation area and appoint boundary type,using fluent to set up turbulence model,boundary conditions,calculation method and wall conditions.The simulation use Realizable k-? model,steady state and separate solver to iterative.The influence of wind speed and wind direction on the recirculation of air cooling island was obtained,when the upstream of air-cooling island has tall buildings,as the wind speed increases,recirculation of ACC increases,otherwise,as the wind speed increases,the recirculation first increases and then decreases.In order to improve the cooling effect of ACC,reduce recirculation.This paper find out the wind effect regular on ACC of recirculation.On this basis,the author proposes the following measures for improvement.1,The original height of wind-break wall around air cooling platform is 15 m,on this basis increased 1~5m.By calculation,with the increase of wind-break wall,the recirculation of air-cooling system reduced.but they decline to slow,especially in the wake of increased to 3m,as the increase of wind-break wall,the effect of reducing recirculation is not significantly.So,recommend to increase the height of wind-break wall 2~3m on the basis of the original height 15 m.2,Retrofitting front bezel to the side of air cooling platform away from the boiler house,which perpendicular to the wind wall,and its width is 0~7m.By calculation,asthe width of front bezel increases,the recirculation first increases and then decreases.When the width of front bezel is 3~5m,the recirculation is minimum.3,Retrofitting side bezels to the both side of air cooling platform.The width of side bezels is 0~6m.By calculation,the side bezels can reduce recirculation.But it is not the width the better.The recirculation is lowest when the width of side bezels is2 m.4,Discussion on the reasonable position of indirect air cooling tower.Indirect air cooling tower will disturbed the hot field of direct air cooling island when wind blows from indirect air cooling tower to direct air cooling island.By calculation,proposed translating indirect air cooling tower 30 m along-X axis,when the effect in recirculation of direct air cooling island is lowest.Provide a reference for engineering design.