PURPOSE: To prevent soundness of the structure of a tube plate being impaired due to the generation of stress depending on the difference in the termal expansion quantity, by correlatively enlarge the spiral pitch of heat transfer pipes of layers adjacent to respective shrouds, in the titled shell and tube type heat exchanger in which a large number of heat transfer pipes having different spiral diameters are arranged in multilayers in a heat exchange region to form a heat transfer pipe.
CONSTITUTION: When a clearance between an outside cylindrical shroud 13 and an outermost heat transfer pipe is represent by A, a clearance between an inside cylindrical shroud 14 and an innermost heat transfer pipe by D, and clearances between helical coil heat transfer pipes, B and C, clearances A and D become greater than B and C from the restriction of structural formula. When a fluid flowing down through the clearances A and D becomes more than a fluid flowing through the clearances B and C. As a result, the temperature of at the steam outlet on the water side tends to elevate. In this case, the spiral pitch of the heat transfer pipes in the outermost layer and the innermost layer is made larger than the spiral pitch of the heat transfer pipes in the other layers. The length of each of these heat transfer pipes is shortened, whereby the heat exchange quantity is lowered and the temperature is also lowered to reach an average value and to make small the temperature difference at the tube plate part 16. Consequently, the stress due to the difference in the thermal expansion is reduced to make it possible to keep soundness of the structure of the tube plate part.
SOUMAN YOSHITO
NEMOTO KAZUAKI
