Corrosion of plate-type air preheaters
Thread Content
The plate preheater of the incinerator suffers from severe corrosion at the cold air inlet; it is made of 254SMO material and has been in use for only half a year. Please help analyze the reasons and suggest ways to optimize it The cold air contains halogenated alkanes, and the hot gas after combustion contains hydrogen chloride. The inlet temperature of the cold air is at room temperature, while the outlet temperature of the hot air is 120–160°C. There is basically no corrosion from hot air intake and cold air outlet.
Add a preheater to the cold air, and control the outlet temperature of the hot air at 160–180°C to see how it works.
Undoubtedly, due to chemical corrosion, it may be necessary to replace the heat exchanger with a suitable corrosion-resistant material. For reference.
Hello, the heat exchanger that is having problems is used to preheat cold air; if it is preheated using electricity alone, the cost becomes unacceptably high
Thank you for your feedback. Do you have any recommendations for suitable materials? The exhaust gases currently contain halogens primarily
Try the polyaniline coating; it seems like it should work. You can do a hanging slice test to check it out
The exit temperature of the hot air is too low, causing the temperature of the heat exchange wall to be equal to or below the dew point temperature of the hot air, thereby leading to dew point corrosion. You can take a look at this topic: http://bbs.hcbbs.com/thread-3152341-1-1.html
It is impossible for the flow field and temperature field inside the equipment to be evenly distributed; there will inevitably be local dead zones that result in excessively low temperatures, leading to corrosion by hydrochloric acid. It is recommended to modify the design to a co-current heat exchange configuration, whereby the hot air inlet and the cold air inlet are on the same side, as well as the hot air outlet and the cold air outlet. This approach helps to maintain the wall temperature above 100 degrees, thus keeping it at a relatively high level, although the heat exchange efficiency may decrease slightly. Additionally, if the structure permits it, applying anti-corrosion paint as mentioned above is also a measure
If you don’t want to change the structure, using a coating is a better option.
It must be dew point corrosion; our high-temperature ceramic anti-corrosion coating can be used
Dew point corrosion can be alleviated by raising the flue gas temperature; coating treatment also depends on the situation – it’s not very effective if there is significant thinning of the coating