Tube and tube heat exchangers are currently widely used in chemical and alcohol production. It is mainly composed of shell, tube plate, heat exchange tube, head, baffle, etc. Material required , can be made of ordinary carbon steel, copper, or stainless steel respectively. During heat exchange, a 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. This is called the tube side.;Another fluid enters through the nozzle of the shell and flows out from another nozzle on the shell. This is called a shell-side tube heat exchanger.
       The structure of the tube heat exchanger is relatively simple, compact and cheap, but the outside of the tube 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, there is a temperature difference compensation device. Generally, the temperature difference between the tube wall and the shell wall50℃When above, for safety reasons, the heat exchanger should have a temperature difference compensation device. But the compensation device(expansion joint)It can only be used when the temperature difference between the shell wall and the tube wall is less than60~70℃and the shell-side fluid pressure is not high. Generally, the shell-side pressure exceeds0.6MpaAt this time, because the compensation ring is too thick and difficult to expand and contract, and loses the temperature difference compensation function, other structures should be considered. The vortex hot film of the tube heat exchanger mainly uses vortex hot film heat transfer technology, which increases the heat transfer effect by changing the fluid motion state. When the medium passes through the vortex tube surface, it strongly washes the tube surface, thereby improving the heat transfer efficiency. Reachable10000W/m2℃. At the same time, this structure achieves the functions of corrosion resistance, high temperature resistance, high pressure resistance, and anti-fouling. The fluid channels of other types of heat exchangers are in the form of fixed direction flow, forming flow around the surface of the heat exchange tube, and the convection heat transfer coefficient is reduced.