Tubular exchanger is a type of heat exchanger that is widely used in chemical industry and alcohol production. It is mainly composed of shell, tube plate, heat exchange tube, head, baffle, etc. The required materials can be made of ordinary carbon steel, copper, or stainless steel. During heat exchange, one fluid enters from the connecting tube of the head, flows in the tube, and flows out from the outlet pipe at the other end of the head, which is called the tube side; the other fluid enters from the connecting tube of the shell and flows out from the other connecting tube on the shell, which is called the shell side.
 
Structural Description
       The structure of the tube-and-tube heat exchanger is relatively simple, compact, and cheap, but the outside of the tubes cannot be cleaned mechanically. The tube bundles of this type of heat exchanger are connected to the tube sheets, which are welded to both ends of the shell and connected to a top cover. The top cover and the shell are equipped with fluid inlet and outlet pipes. A series of baffles are usually installed outside the tubes perpendicular to the tube bundle. At the same time, the connection between the tube and the tube sheet and the shell are rigid, and there are two fluids with different temperatures inside and outside the tube. Therefore, when the temperature difference between the tube wall and the shell wall is large, due to the different thermal expansion of the two, a large temperature difference stress is generated, which may cause the tube to twist or loosen from the tube plate, or even damage the heat exchanger.
       In order to overcome the temperature difference stress, a temperature difference compensation device is necessary. Generally, when the temperature difference between the tube wall and the shell wall is more than 50°C, for safety reasons, the heat exchanger should have a temperature difference compensation device. However, the compensation device (expansion joint) can only be used when the temperature difference between the shell wall and the pipe wall is lower than 60 to 70°C and the shell side fluid pressure is not high. Generally, when the shell side pressure exceeds 0.6Mpa, the compensation ring is too thick, difficult to expand and contract, and loses the temperature difference compensation function, so other structures should be considered.