Shell and tube heat exchanger temperature compensation measures

- May 14, 2018 -

The shell and tube heat exchanger is another name for the column-tube heat exchanger, and is a type of inter-wall heat exchanger in which the wall surface of the tube bundle enclosed in the housing serves as a heat transfer surface. At present, the commonly used models mainly include fixed tube-plate steam-water heat exchangers, tube-and-water heat exchangers with expansion joints, floating-head steam-water heat exchangers, and U-shaped shell-and-tube steam-water heat exchangers. There are several types of wave-type shell-and-tube steam-water heat exchangers and sectional water-water heat exchangers.


Introduced from the fixed tube-plate heat exchanger one by one, the tubesheets at both ends of its tube bundle are integrated with the housing, and the structure is simple. It is suitable for the heat exchange operation when the temperature difference between the hot and cold fluids is not large and the shell process does not require mechanical cleaning. When the temperature difference is slightly greater and the shell pressure is not too high, an elastic compensating ring can be mounted on the housing to reduce the thermal stress.


The tube plate at one end of the floating head heat exchanger tube bundle in the shell-and-tube heat exchanger is free to float, the thermal stress is completely eliminated, and the entire tube bundle can be withdrawn from the shell, which is convenient for mechanical cleaning and overhaul, so this type of shell Heat exchangers are widely used.


U-tube heat exchanger is very easy to understand, each of its heat exchange tubes are bent into a U-shaped, both ends are fixed on the same tube sheet in the next two areas, with the help of the partition inside the tube is divided into two compartments, This heat exchanger completely eliminates thermal stress and the structure is simpler than floating head type.


Eddy-current hot-film heat exchanger is also one of the shell and tube heat exchanger. It increases the heat transfer effect by changing the fluid movement state. When the medium passes through the vortex tube surface, it strongly flushes the surface of the tube, thereby increasing the heat exchange efficiency. , up to 10000W/m2°C, at the same time, this structure achieves corrosion resistance, high temperature resistance, high pressure resistance, and anti-scaling


In practical application, it is necessary to reasonably control the parameters of the above various shell-and-tube heat exchangers, mainly involving heating area, hot water flow, heat exchange amount, and thermal media parameters. Since the temperature of the fluid inside and outside the shell and tube heat exchanger tube is different, the temperature of the shell and the tube bundle is also different. Therefore, when the temperature difference between the tube bundle and the shell exceeds 50° C., appropriate compensation measures must be taken to eliminate or reduce the thermal stress.