Corrosion of the flue gas heat exchanger tube bundle
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The image below shows the finned heat exchange tube bundle in a certain thermal power plant’s GGH; it is made of ND steel and became unusable after more than a year of use due to severe corrosion and scaling, which represents a bottleneck in the development of GGHs. This system is mainly affected by flue gas dew point corrosion. Since sulfur in the fuel produces SO2 and SO3 during combustion, when the outer surface temperature of the heat exchange surface is lower than the dew point temperature of the flue gases, sulfuric acid mist droplets form on the heat exchange surface, leading to its corrosion.
Consider choosing tubes made of corrosion-resistant material, removing the tube fins, and adding more heat exchanger units. Strict process control. For reference.
The corrosion of the tube bundle in flue gas heat exchangers is mainly caused by sulfur in the fuel, which generates sulfur dioxide and sulfur trioxide during combustion. When these gases in the flue gas combine with water vapor, sulfuric acid dew points are formed on the surface of the heat exchanger. If the surface temperature of the tube bundle is lower than this dew point temperature, sulfuric acid mist is generated, resulting in dew drops forming on the surface. These sulfuric acid mist droplets can cause severe corrosion problems, thereby shortening the service life of the heat exchanger. .
Once the reasons are known, it becomes simple to handle the issue: adjust the process so that the inlet temperature of the cold fluid inside the pipe is higher than the dew point temperature of sulfuric acid in the gas outside the pipe.
This post was last edited by wxf125 on 2024-7-15 at 11:24. This is a conventional heat-tube type economizer, and the wall temperature cannot be controlled, which leads to corrosion. There is a new type of economizer that is small in size yet capable of maintaining stable wall temperatures.