The structural characteristics of the vertical shell and tube heat exchanger are reflected in the orthogonal heat transfer path design of the tube side and shell side fluids. The cylindrical pressure vessel is bounded by the tube sheet to form a dual-medium isolation cavity. The tube bundle array is arranged in a straight line in the direction of gravity. The corrugated surface of the baffle guides the shell side fluid to form turbulence to enhance convective heat transfer. The sealing structure of the tube box and the shell flange connection adopts an asymmetric wedge-shaped gasket to form a composite sealing mechanism of axial preload and radial constraint.