Corrosion of heat pipe exchangers in heating furnace flue gas
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The figure below shows the GGH air preheater of a petrochemical heater, which uses heat pipes for heat exchange. After 3 years of use, some of the heat pipes on the air side have broken, and there is a lot of scaling on the flue gas side, resulting in a severe decline in heat exchange efficiency. Therefore, anti-corrosion measures must be considered for heat pipes in such corrosive environments.
In the GGH air preheater of petrochemical heating furnaces, the heat exchange efficiency declined due to breaks and scaling that occurred in the heat pipes after three years of use. To cope with corrosive environments, anti-corrosion measures must be taken. High-temperature and corrosion-resistant materials can be used to manufacture heat pipes, while enhanced maintenance and cleaning during operation are necessary, with regular removal of deposits to ensure the proper functioning of the heat exchange system. .
These days, enamel-coated versions or those made of duplex steel are commonly used. The breakage of the heat exchanger tubes on the air side, as can be seen from the images, is caused by corrosion inside the tubes, and this may be related to the working fluid.
The pitting corrosion in the first image is quite severe. The sulfur content in the fuel must be controlled, as well as the exhaust gas temperature. For the image below, in addition to corrosion as a cause, other factors should also be considered