Share to: Shell-and-tube heat exchanger

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Product details: The tubular exchanger is a type of heat exchanger that is widely used in the chemical industry and alcohol production today. It is mainly composed of a shell, tube sheet, heat exchange tubes, head, baffle plates, etc. The required materials can be ordinary carbon steel, red copper, or stainless steel. During heat exchange, one fluid enters at the connection pipe of the end cap, flows through the pipes, and exits through the outlet pipe at the other end of the end cap; this is referred to as the tube side ； Another fluid enters through a nozzle on the shell and exits through another nozzle on the shell; this is known as a shell-and-tube heat exchanger. The fixed-tube-sheet type shell-and-tube heat exchanger has a simple and compact structure as well as low cost, but it cannot be mechanically cleaned on the outside of the tubes. In this type of heat exchanger, the tube bundle is connected to the tube sheet, which is welded to both ends of the shell; a top cover is attached to the tube sheet. The top cover and the shell are equipped with fluid inlet and outlet nozzles. Typically, a series of baffles perpendicular to the tube bundle are installed outside the tubes. At the same time, the connections between the tubes and tube sheets and the shell are rigid, while there are fluids at different temperatures inside and outside the tubes. Therefore, when there is a large temperature difference between the tube wall and the shell wall, differences in their thermal expansion lead to significant temperature stress, which can cause the tubes to bend or become loose from the tube sheet, thereby damaging the heat exchanger. To overcome thermal stress, temperature difference compensation devices are used; generally, when the temperature difference between the tube wall and the shell wall exceeds 50°C, it is advisable for heat exchangers to be equipped with such compensation devices as a precaution. However, compensation devices (expansion joints) can only be used when the temperature difference between the shell wall and the tube wall is below 60–70°C and the pressure of the fluid in the shell side is not high. Generally, when the shell-side pressure exceeds 0.6 Mpa, the compensation ring becomes too thick and is unable to expand or contract, thus losing its function of compensating for temperature differences; in such cases, other designs should be considered. In a floating-head heat exchanger, one tube sheet is connected to the shell via flanges, while the other tube sheet is not connected to the shell, allowing the tubes to expand and contract freely as they are heated or cooled. However, a cover is attached to this tube sheet, which is referred to as the \"floating head\"; hence, this type of heat exchanger is called a floating-head heat exchanger. Its advantage is that the tube bundle can be pulled out for cleaning ； The expansion of the tube bundle is constrained by the shell, so when there is a large temperature difference between the two fluids in the heat exchanger, no thermal stress is generated due to the differences in thermal expansion between the tube bundle and the shell. Its disadvantages are complex structure and high cost. stuffing box type: In this type of heat exchanger, one end of the tube bundle can expand freely; its structure is simpler than that of the floating head type, and its cost is also lower. However, there is a risk of leakage of the medium in the shell side, and volatile, flammable, or explosive media should not be handled in the shell side. U-tube type: In a U-tube heat exchanger, each tube is bent into a U shape, with its ends fixed to the same tube sheet; each tube can expand and contract freely, thereby addressing the issue of thermal compensation. The tube bank consists of at least two banks; the tube bundle can be removed for cleaning, and the tubes can expand freely. Its disadvantages are that the inner wall of the tube is difficult to clean, the tubes are hard to replace, and there are few tubes arranged on the tube sheet. The advantages are simple structure, light weight, and suitability for high-temperature and high-pressure conditions.