Hunan Xunke Xuguang Technology Co., Ltd.
Hunan Xunke Xuguang Technology Co., Ltd.
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Customizable stainless steel shell and tube heat exchangers
Shell and tube heat exchangers are widely used in chemical, pharmaceutical, food and beverage, alcohol production, refrigeration, civil and other processes. They are mainly composed of shell, tube sheet, 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 pipe 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; the other fluid enters from the shell pipe and flows out from another pipe on the shell. This is called the shell side shell and tube heat exchanger.
Product classification and characteristics
Fixed tube sheet heat exchanger
The structure of the fixed tube sheet heat exchanger is relatively simple, compact and cheap, but the outside of the tube cannot be mechanically cleaned.
The tube bundle of the fixed tube sheet heat exchanger is connected to the tube sheet, which is welded to the two ends of the shell and connected to the top cover. The top cover and the shell are equipped with fluid inlet and outlet pipes. Usually, a series of baffles perpendicular to the tube bundle are installed outside the tube. At the same time, the connection between the tube and the tube sheet and the shell is rigid, and 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 different thermal expansion of the two, a large temperature difference stress is generated, so that the tube is twisted or the tube is loosened from the tube sheet, which even destroys the heat exchanger. In order to overcome the temperature difference stress, a temperature difference compensation device must be provided. Generally, when the temperature difference between the tube wall and the shell wall is more than 60℃, 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 tube wall is less than 60~70℃ and the shell-side fluid pressure is not high. Generally, when the shell-side pressure exceeds 0.6mpa, the compensation ring is too thick and difficult to expand and contract, and loses the function of temperature difference compensation, so other structures should be considered.
Floating head heat exchanger
One tube sheet of the heat exchanger is connected to the shell with a flange, and the other tube sheet is not connected to the shell, so that the tube can expand and contract freely when heated or cooled, but a top cover is connected to this tube sheet, called a "floating head", so this heat exchanger is called a floating head heat exchanger. Its advantages are: the tube bundle can be pulled out for cleaning; the expansion of the tube bundle remains unchanged and is constrained by the shell, so when the temperature difference between the two heat exchanger media is large, no temperature difference stress will be generated due to the different thermal expansion of the tube bundle and the shell. Its disadvantages are complex structure and high cost.
U-tube heat exchanger
In a U-tube heat exchanger, each tube is bent into a U shape, and both ends are fixed on the same tube sheet. Each tube can be freely expanded and contracted, thus solving the problem of heat compensation. The tube pass is at least two passes, the tube bundle can be pulled out for cleaning, and the tube can expand freely. Its disadvantages are 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 sheet. The advantages are simple structure, light weight, and suitable for high temperature and high pressure conditions. In order to increase the flow rate of the shell-side fluid, a certain number of baffles perpendicular to the tube bundle are often installed in the shell. The baffle can not only prevent the fluid from short-circuiting and increase the flow rate of the fluid, but also force the fluid to cross-flow through the tube bundle multiple times according to the specified path, greatly increasing the degree of turbulence.
Commonly used baffles are round and disc-shaped, and the former is more commonly used.
Equipment selection
Basic parameters of shell and tube heat exchanger