High-temperature heat exchangers, thin tube sheets
Thread Content
Hello, experts in heat exchangers. I previously built a small exhaust gas processor in which the exhaust gas was burned directly, with cold air being mixed in the exhaust ducts before it was released into the atmosphere. Now I want to implement waste heat recovery – by using a shell-and-tube heat exchanger to heat the air used for burning the exhaust gas through a waste heat recovery unit, and then allowing that heated air to enter the exhaust gas processor. The flue gas temperature is around 650 degrees Celsius, the air inlet temperature is 20 degrees, and an increase of 200 degrees is expected. The air pressure is 8 Pa, and the flue gas has no pressure. Which type with a thin tube sheet would be more suitable? Based on temperature considerations, it should be type d, but I think type c is more convenient for processing and welding. But GB151 states that the operating temperature is 300 degrees. Although it is not a pressure vessel, the lack of relevant standards makes it difficult to find references. Please take this into consideration. c refers to the tube sheet that is submerged below the flange, while d refers to a flexible tube sheet; I’m unable to upload images, alas. . . .
It is also included in Appendix L of GB151, as well as in Dong Qiwu’s book \"Heat Exchangers\", page 14
Is this an air preheater? :D
I’m not sure if I’m correct, but it’s about using this hot flue gas at 650°C to heat the air to 200°C, and wanting to use some kind of heat exchanger to recover that heat, right? If that is the case, the first thing to consider is whether the resistance to flue gas emission can meet the production requirements; not to mention that without pressure, the flue gas cannot be expelled, and thus there will be no flue gas at all. Then, there needs to be sufficient heat exchange area, and finally, a heat exchanger suitable for large temperature differences (between the gases on both sides) is required. There are also other factors to consider, such as \"corrosion of the heat exchanger by flue gas, impurities in the flue gas, and scaling on the surface of the heat exchanger\". In my opinion, it’s enough to use a few pipes just as a symbol; you probably want to utilize the recovered heat to heat the air and use it as a high-temperature combustion gas in order to improve thermal efficiency. We also need to see the amount that can be recycled to determine whether it’s worth it. Otherwise, there would be no such thing as \"waste heat\".
I can discuss the design and production of stainless steel plate-fin waste heat recovery units.
Fully welded stainless steel plate type, operating temperature of 900 degrees, pressure of 1 MPa – an efficient gas-to-gas heat exchange device. Please contact me privately for more details. Tubular types are rarely used for gas-to-gas heat exchange; finned tubes are the minimum requirement in such cases