The plate heat exchanger has a good heat exchange effect, and the plates can be removed for easy cleaning. Shell and tube heat exchanger, the heat exchange tube cannot be disassembled, which will cause some inconvenience for cleaning. 对于换热工况这方面来说有限制，只适应在150摄氏度以内的换热工况换热，而管壳式换热器对于换热工况中的温度，是没有限制的，无论对少度都可以用管壳式换热器。 Plate heat exchangers
are limited in terms of heat exchange conditions. They are only suitable for heat exchange conditions within 150 degrees Celsius, while shell and tube heat exchangers have no restrictions on the temperature in heat exchange conditions. You can use a shell and tube heat exchanger regardless of the degree. From the perspective of price, compared with the shell-and-tube heat exchanger, the cost of plate heat exchanger is low. These are just simple differences. The detailed differences are introduced below by this article:
1. High heat transfer coefficient: Because different corrugated plates are inverted, they form a complex flow channel, which makes the fluid rotate in three dimensions in the flow channel between corrugated plates, which can be at a low Reynolds number (generally Re = 50 ~ 200). Turbulence is generated, so the heat transfer coefficient is high, which is generally considered to be 3 to 5 times that of the shell and tube type.
2. The large logarithmic average temperature difference: the end temperature difference is small. In the shell and tube heat exchanger, the two fluids flow in the tube side and the shell side, respectively, and are generally cross-flow. The logarithmic average temperature difference correction coefficient is small, and the plate type Heat exchangers are mostly co-current or counter-current, and their correction factors are usually around 0.95. In addition, the flow of cold and hot fluids in the plate heat exchanger is parallel to the heat exchange surface and there is no side flow, so the plate heat exchange is made. The temperature difference at the end of the heat exchanger is small, and the heat transfer to water can be lower than 1 ° C, while the shell and tube heat exchanger is generally 5 ° C.
3. Small footprint and compact structure: the heat exchange area per unit volume is 2 to 5 times that of the shell and tube type, and there is no need to reserve a maintenance site to extract the tube bundle like the shell and tube type, so the same heat exchange capacity is achieved. The plate heat exchanger covers about 1/5 ~ 1/8 of the shell and tube heat exchanger.
4, easy to change the heat exchange area or process combination: as long as the plate heat exchanger increases or decreases a few plates, you can achieve the purpose of increasing or decreasing the heat exchange area; change the plate arrangement or replace a few plates, you can achieve all The required process combination is adapted to the new heat exchange conditions, and the heat transfer area of the shell and tube heat exchanger is almost impossible to increase.
5. Light weight: The plate thickness of the plate heat exchanger is only 0.4 ~ 0.8mm, while the thickness of the heat exchanger tube of the shell-and-tube heat exchanger is 2.0 ~ 2.5mm. The frame is much heavier, generally only about 1/5 of the shell and tube weight.
6. Low price: With the same material and the same heat exchange area, the price of plate heat exchanger is about 40% ~ 60% lower than that of shell and tube type.
7. Convenient production: The heat transfer plate of the plate heat exchanger is stamped, has a high degree of standardization, and can be produced in large quantities. The shell and tube heat exchanger is generally made by hand.
8. Easy cleaning: As long as the plate heat exchanger is loosened and the bolts are loosened, the plate bundle can be loosened and the plates can be removed for mechanical cleaning, which is very convenient for the heat exchange process that requires frequent cleaning of the equipment.
9, small heat loss: only the shell plate of the heat transfer plate is exposed to the atmosphere, so the heat dissipation loss is negligible, and no thermal insulation measures are needed. The shell-and-tube heat exchanger has a large heat loss and requires a heat insulation layer.
10. The smaller capacity is 10% ~ 20% of the shell and tube heat exchanger.
11. The pressure loss per unit length is large. Because the gap between the heat transfer surfaces is small and the heat transfer surface has irregularities, the pressure loss is larger than the traditional smooth tube.
12, not easy to scale: due to sufficient internal turbulence, it is not easy to scale, its scale factor is only 1/3 ~ 1/10 of the shell and tube heat exchanger.
13. The working pressure should not be too high, and the medium temperature should not be too high. It may leak. The plate heat exchanger is sealed with a gasket. The working pressure should generally not exceed 2.5 MPa. The medium temperature should be below 250 ° C, otherwise it may leak.
14, easy to block due to the narrow channel between the plates, generally only 2 ~ 5mm, when the heat exchange medium contains large particles or fibrous substances, it is easy to block the channel between the plates.