The shell and tube heat exchanger is composed of shell, heat transfer tube bundle, tube sheet, baffle (baffle) and tube box. The shell is mostly cylindrical, with a tube bundle inside, and both ends of the tube bundle are fixed on the tube plate. Two fluids, hot and cold, that exchange heat, one flows in the tube, called tube-side fluid; the other flows outside the tube, called shell-side fluid. In order to improve the heat transfer coefficient of the fluid outside the tube, several baffles are usually installed in the housing. The baffle can increase the fluid velocity on the shell side, forcing the fluid to pass through the tube bundle multiple times in a prescribed way, and enhance the degree of fluid turbulence. The heat exchange tubes can be arranged in an equilateral triangle or square on the tube plate. The equilateral triangle arrangement is relatively compact, the fluid outside the pipe has a high degree of turbulence, and the heat transfer coefficient is large; the square arrangement makes it easy to clean the outside of the pipe and is suitable for fluids that are prone to fouling.
1. Fixed tube-plate heat exchanger. The tube plates at both ends of the tube bundle are integrated with the shell, with a simple structure, but only suitable for heat exchange operations when the temperature difference between the cold and hot fluids is not large and the shell side does not require mechanical cleaning. When the temperature difference is slightly larger and the shell pressure is not too high, an elastic compensation ring can be installed on the shell to reduce thermal stress.
2. Floating-head heat exchanger. The tube sheet at one end of the tube bundle can float freely, completely eliminating thermal stress; and the entire tube bundle can be extracted from the shell, which is convenient for mechanical cleaning and maintenance. Floating head heat exchangers are widely used, but the structure is more complicated and the cost is higher.
3. U-shaped tube heat exchanger. Each heat exchange tube is bent into a U shape, and the two ends are fixed on the same tube plate in the upper and lower areas respectively, and are divided into two chambers with the help of the partition in the tube box. This type of heat exchanger completely eliminates thermal stress, the structure is simpler than the floating head type, but the pipe side is not easy to clean.
4. Vortex hot film heat exchanger. The vortex hot film heat exchanger uses the latest vortex heat film heat transfer technology to increase the heat transfer effect by changing the fluid motion state. When the medium passes through the surface of the vortex tube, the surface of the tube is strongly washed, thereby improving Heat exchange efficiency. Up to 10000W/m2℃. At the same time, this structure realizes the functions of corrosion resistance, high temperature resistance, high pressure resistance, and anti-scaling. The fluid channels of other types of heat exchangers are in the form of fixed directional flow, forming a flow around the surface of the heat exchange tube, and the convection heat exchange coefficient is reduced.
The shell and tube heat exchanger is the main type of heat exchange equipment. This type of heat exchanger has a simple structure, reliable operation, convenient and reliable materials, and is suitable for various high temperature and high pressure environments. It is currently the most widely used heat exchanger device.