Tubular heat exchanger is a type of heat exchanger that is widely used in our industry and has brought a great effect to our lives. However, there is not only one type of tubular heat exchanger. To introduce you to several different types of tube and tube heat exchangers, so that everyone can better choose to use tube and tube heat exchangers in the future.
The working principle of the tube heat exchanger is mainly composed of the head, shell, tube bundle, flange connection and other components. One working medium enters into the heat transfer tube from the inlet end of the head end, and its process can realize the structure of one-pass, two-pass and four-pass according to the process requirements; the other working medium enters the casing from the inlet of one end of the casing And evenly distributed outside the heat transfer tube, the flow state can be set in the tube bundle according to the process requirements of different types and number of baffles. As a heat transfer element-heat exchange tube, brass tube, copper fin tube and steel tube can be used according to the process requirements, so as to ensure that the working medium with different physical properties and different temperatures exchange heat in the heat exchanger to achieve cooling or The purpose of heating.
The structure of this type of heat exchanger is relatively simple, compact, and inexpensive, but the outside of the tube cannot be mechanically cleaned. The heat exchanger tube bundle is connected to the tube plate, the tube plates are welded to the two ends of the shell, and a top cover is connected to the top cover, and the top cover and the shell are equipped with fluid inlet and outlet pipes. A series of baffles perpendicular to the tube bundle are usually installed outside the tube. At the same time, the connection between the tube and the tube plate and the outer shell are rigid, while the inside and outside of the tube are two fluids with different temperatures. Therefore, when the temperature difference between the tube wall and the shell wall is large, due to the difference in thermal expansion between the two, a large temperature difference stress is generated, which causes the tube to bend or loosen the tube from the tube sheet, or even destroy the heat exchanger.
One tube plate of the heat exchanger is connected to the shell with a flange, and the other tube plate is not connected to the shell, so that the tube can freely expand and contract when heated or cooled, but a top cover is connected to this tube plate, which is called " "Floating head", so this heat exchanger is called a floating head heat exchanger. The advantages are: the tube bundle can be pulled out for cleaning; the expansion of the tube bundle is not constrained by the shell, so when the temperature difference between the two heat exchanger media is large, there will be no temperature difference stress due to the difference in the thermal expansion of the tube bundle and the shell .
The tube bundle of this type of heat exchanger can expand freely at one end, the structure is simpler than the floating head type, and the cost is lower than the floating head type. However, the medium in the shell side may leak, and the medium in the shell side should not be treated with volatile, flammable, explosive and toxic media.
U-tube heat exchanger, each tube is bent into a U-shape, the two ends are fixed on the same tube plate, each tube can be freely expanded and contracted, so as to solve the problem of thermal compensation. The tube pass is at least two passes, the tube bundle can be drawn out for cleaning, and the tube can be expanded freely. The disadvantage is that it is difficult to clean the inner wall of the tube, it is difficult to replace the tube, and there are few tubes arranged on the tube plate. The advantage is that the structure is simple, the quality is light, and it is suitable for high temperature and high pressure conditions.