Detachable structure and heat transfer surface of spiral plate heat exchanger
The tube sheet at one end of the spiral plate heat exchanger is fixed with the shell, and the other tube sheet can float freely in the shell. The shell and the tube bundle are free to expand. Therefore, when the temperature difference between the two media is large, there is no temperature difference stress between the tube bundle and the shell.
The floating head end of the spiral plate heat exchanger is designed as a detachable structure, so that the tube bundle can be easily inserted into or pulled out of the shell. This provides convenience for inspection and cleaning. However, the structure of the heat exchanger is complex, and the leakage of the floating end cap can not be known when operating. Therefore, special attention should be paid to its sealing during installation.
The hook ring of spiral plate heat exchanger plays an important role in ensuring the real seal of floating head and preventing the leakage between media. With the development of design and manufacturing technology of Futou heat exchanger and the accumulation of long-term experience, the structural form of hook ring has been improved and perfected.
The tube of spiral plate heat exchanger forms the heat transfer surface of the heat exchanger. The size and shape of the tube have a great influence on the heat transfer. When using small diameter tubes, the heat exchange area per unit volume of the heat exchanger is larger, the equipment is more compact, the metal consumption per unit heat transfer area is less, and the heat transfer coefficient is higher. But make trouble, the pipe is easy to scale, not easy to clean. Large diameter pipes are used for viscous or dirty fluids, while small diameter pipes are used for cleaner fluids.
The arrangement of tubes on the tubesheet of spiral plate heat exchanger not only considers the compactness of the equipment, but also considers the properties of the fluid, structural design and manufacturing. There are four types of dimension arrangement of tubes on tubesheet: equilateral triangle and angular equilateral triangle, which can be used in the case of shell side medium cleaning without mechanical cleaning. The square and corner square arrangement can make the small bridge between pipes form a straight channel, which is convenient for mechanical cleaning. It is generally used in the occasion where the tube bundle can be pulled out to clean between pipes.
Advantages of spiral plate heat exchanger
1. High total heat transfer coefficient. As the fluid flows in the spiral channel, the turbulent flow can be achieved at a lower Reynolds number (generally re = 1400 ~ 1800, sometimes as low as 500), and a higher flow rate (2m / s for liquid and 20m / s for gas) can be selected, so the total heat transfer coefficient is larger.
2. It is not easy to block. Due to the high velocity of the fluid, the suspended solids in the fluid are not easy to deposit, and any sediment will reduce the cross section of the single channel, so the velocity will increase and the clogging area will be scoured, so the spiral plate heat exchanger is not easy to be clogged.
3. Can use low temperature heat source to control temperature. This is due to the long flow passage and complete countercurrent of the two fluids.
4. Compact structure. The heat transfer area per unit volume is three times of that of tube heat exchanger.