Stress And Flow Field Analysis Of Air Cooling Exhaust Steam Pipes

As an important component of air-cooling island, exhaust steam pipes of direct air cooling unit are typical large-diameter thin-wall pipe, whose performance directly affects the economy and security of power plant. Scholars at home and abroad mostly focus on the operation characteristics of air-cooling island. Therefore, researching of exhaust steam pipes from the perspective of stress analysis is not comprehensive enough. In this paper, software of FLUENT, CAESAR II and ANSYS are adopted to simulate the stress and flow field of the exhaust steam pipes of air-cooling unit.In this paper, the exhaust steam pipes of a 330 MW air-cooling unit are the studying object. Software of FLUENT is used to simulate the inner flow field. Software of CAESAR II is used to simulate the pipe stress. The displacement, the torque, the thrust force of interface of the shunt and horizontal manifold are obtained. Those results are set as boundary conditions. In the software of ANSYS, the FSI module is used to simulate the stress suffered by pipe wall and the internal flow field of shunt and horizontal manifold. The width of manifold elbow design of non-standard are changed on the basis of the requirements of allowable stress for air-cooling exhaust steam pipe. The best design width of non-standard part at manifold elbow is obtained by numerical simulation of the stress suffered by pipe wall of horizontal manifold and the internal flow field of exhaust pipes of air-cooling unit at different width of non-standard part.The results show that: the shunt and horizontal manifold of air-cooling unit are the stress-concentrated part. The adding of structural and thermal stress of the exhaust steam pipes under the design conditions is within the allowable range. When the manifold elbow design of non-standard width is in the range of 500-800 mm, changing the width of manifold elbow design of non-standard has little effect on stress distribution in horizontal manifold, but it has a certain influence on the inner flow field of air-cooling exhaust steam pipe. The best design width is considered to be 600 mm in regard with the flow field uniformity.