Shell and Tube Heat Exchanger Structure

Shell and tube heat exchanger consists of shell, heat transfer tube bundle, tube plate, folding plate (baffle) and tube box and other components. The shell is mostly cylindrical, with tube bundles inside, and the ends of the tube bundles are fixed on the tube plate. Heat transfer of cold and hot two kinds of fluids, one in the tube flow, known as the tube course fluid; the other in the tube outside the flow, known as the shell course fluid. In order to improve the heat transfer coefficient of the fluid outside the tube, usually installed in the shell of a number of baffles. Baffle can increase the shell process fluid velocity, forcing the fluid to travel several times according to the specified lateral through the tube bundle, enhance the degree of fluid turbulence. Heat exchanger tubes in the tube plate can be arranged according to the equilateral triangle or square. Equilateral triangle arrangement is more compact, high degree of fluid turbulence outside the tube, heat transfer coefficient; square arrangement is easy to clean outside the tube, suitable for easy scaling of the fluid.

Fluid every time through the tube bundle is called a tube course; every time through the shell is called a shell course. The figure shows the simplest single shell single tube heat exchanger, referred to as 1-1 type heat exchanger. In order to improve the fluid velocity in the tube, can be set up at both ends of the tube box partition, all the tubes are divided into a number of groups. This way, the fluid only passes through some of the tubes each time, and thus goes back and forth in the tube bundle many times, which is called a multi-pipe process. Similarly, in order to improve the flow rate outside the tube, can also be installed in the shell longitudinal baffle, forcing the fluid to pass through the shell space many times, known as multi-shell process. Multi-tube process and multi-shell process can be applied in conjunction.

Shell and tube heat exchanger due to the temperature of the fluid inside and outside the tube is different, because of the heat exchanger shell and tube temperature is also different. If the difference between the two temperatures is very large, the heat exchanger will produce a large thermal stress, resulting in tube bending, fracture, or pull off from the tube plate. Therefore, when the temperature difference between the tube bundle and the shell exceeds 50 ℃, appropriate compensation measures need to be taken to eliminate or reduce thermal stress.