Shell and tube heat exchanger

Shell and tube heat exchangers are a more common type of heat exchanger, more applications in food, chemical, pharmaceutical, petroleum and other industries, and are a general type of equipment. Shell and tube heat exchangers are mainly composed of shell, tube plate heat exchange tube, head, baffle, etc. The materials of shell and tube heat exchangers include ordinary carbon steel, red copper, or stainless steel, etc. The more used shell and tube heat exchangers are made of stainless steel, such as stainless steel heat exchangers, stainless steel condensers, stainless steel coolers. Fixed tube plate shell and heat exchangers are more commonly used tube and shell heat exchangers.

The two media in the shell and tube heat exchanger pass through different spaces, the space through which the in the tube passes is called the tube pass, and the space through which the fluid outside the tube (inside the shell) passes is called the shell pass. The medium in the pass and the tube pass is different, and the selection of the channel for the cold and hot fluid mainly based on the following points: 1) Unclean and easily scaling liquids go through the tube pass, because it is convenient to clean inside the tube;

Corrosive fluids should go through the tube pass, so as not to corro the tube bundle and shell at the same time;

1. High pressure should go through the tube pass, so as not to put pressure on the shell;
2. Saturated steam should go through the shell pass, because saturated steam is relatively clean, the heat transfer coefficient is independent of the flow rate and the condensate is easy to drain;
3. The fluid to be cooled should go through the shell pass, which is convenient for heat dissipation;
4. If the temperature difference between the two fluids is large, rigid structure heat exchangers, it is advisable to let the fluid with a large heat transfer coefficient go through the shell pass, which can reduce the thermal stress;
5. Fluids with small flow and high viscosity should go through the shell process；

The structure of the fixed tube plate shell and tube heat exchanger is relatively simple, compact and inexpensive, but tube outside cannot be mechanically cleaned. In this type of heat exchanger, the tube bundle is connected to the tube plate, the tube plate is welded at both ends of shell, and a top cover is connected to it, and the top cover and the shell are provided with fluid inlet and outlet pipes. A series of baffles are usually arranged perpendicular to the tube bundle outside the tube. The heat exchanger with a large temperature difference has a temperature difference compensation device. The baffles of the heat exchanger are to increase the rate of the shell fluid. The baffles can not only prevent the short circuit of the fluid and increase the flow rate of the fluid, but also force the fluid to pass through tube bundle according to the specified path and counterflow many times, which greatly increases the degree of turbulence. The commonly used baffles are semicircular and disk-shaped, the being more commonly used. The common heat exchange tubes for shell and tube heat exchangers are 19, 25, 32, and the specific ones are determined to the heat exchange area and the material characteristics and temperature pressure. The common lengths of heat exchange tubes are 1 meter, 1.5 meters, 2 meters, .5 meters, 3 meters, 4.5 meters, 6 meters.