Abstract: By establishing the three-dimension finite element model of the reheat steam cooling tube of a supercritical boiler, and taking its working temperature and constraints as the boundary conditions, the deformation of the cooling tube is analyzed. The analysis results show that some water subsides at the bottom of the tube due to the poor water atomization, causing a large temperature disparity between the top and bottom of the tube, which leads to a great axial tensile stress at the bottom of the pipe and a high axial compressive stress at the top. The alternating stress caused by the spray of the cooling water in the pipe is the main reason of the tube fatigue. The finite element computation results are closely identical with the actual deformation, with an error of about 8.3%.

Key words: supercritical boiler, reheat steam, cooling tube, fatigue, cracking, finite element analysis