What are the types of plate and tube heat exchangers?

Plate and tube heat exchanger - tube heat exchanger

Tubular (also known as shell-and-tube, shell-and-tube) heat exchanger is the most typical partitioned wall heat exchanger. It has a long history of industrial application and still occupies a dominant position in all heat exchangers. The tubular heat exchanger is mainly composed of a shell, a tube bundle, a tube sheet, and a head. The shell is mostly circular, and parallel tube bundles are installed inside, and both ends of the tube bundle are fixed on the tube sheet.

Plate-and-tube heat exchanger—fixed tube-sheet type

In the fixed tube-sheet heat exchanger, the tube sheets at both ends are directly welded to the shell. It is mainly composed of shell, tube sheet, tube bundle, head and other main components. The shell is provided with a tube bundle, and the two ends of the tube bundle are fixed on the tube sheet by welding, expansion joint or expansion welding, and the outer periphery of the tube sheet and the head flange are fastened with bolts. The fixed tube-sheet heat exchanger has the advantages of simple structure, low cost, easy manufacture, and convenient cleaning and maintenance of the tube side, but it is difficult to clean the shell side, and there is a temperature difference stress after the tube bundle is manufactured. When there is a large temperature difference between the heat exchange tube and the shell, an expansion joint should be provided on the shell.

Plate and tube heat exchanger - floating head

One end of the floating head heat exchanger is fixed between the shell and the tube box, and the other end of the tube plate can move freely in the shell, that is, the thermal expansion of the shell and the tube bundle can be free. Therefore, there is no temperature difference stress between the tube bundle and the shell. Generally, the floating head is detachable, and the tube bundle can be drawn out and loaded freely. This structure of the floating head heat exchanger can be used in the working condition where there is a large temperature difference between the tube bundle and the shell. The cleaning and maintenance of the tube bundle and shell are relatively convenient, but its structure is relatively complicated, and the requirements for sealing are relatively high.

Plate and tube heat exchanger - "U" type tube

The U-shaped tube heat exchanger is a U-shaped heat exchange tube, and the two ends are fixed on the same tube sheet. Since the shell and the heat exchange tubes are separated, the heat exchange tube bundle can expand and contract freely, and no temperature difference stress will be generated due to the temperature difference of the medium. The U-tube heat exchanger has only one tube sheet, no floating head, and a relatively simple structure. The tube bundle can be pulled out and loaded freely, which is convenient for cleaning. It has the advantages of a floating head heat exchanger. However, since the heat exchange tubes are made into U-shaped bends with unequal radii, the outermost heat exchange tube can be replaced after damage. Other tubes The damage can only be blocked. At the same time, compared with the fixed tube-sheet heat exchanger, because the heat exchange tube is limited by the bending radius, there is a gap in the center of the tube bundle, and the fluid is easily short-circuited, which affects the heat transfer effect.