Flue gas corrosion of boiler air preheater tubes
Thread Content
The diagram shows the flue gas preheater module; air flows along the inner wall of the tube bundle, with an inlet temperature of 20–40°C and an outlet temperature of 80–90°C. Flue gas flows along the outer wall of the tube bundle; the combustion medium is water-coal slurry, and the flue gas contains SO2, SO3, as well as corrosive substances such as HF and HCl. The inlet temperature of the flue gas is 150~170°C, and the outlet temperature is 100~130°C. This flue gas preheater has been in use for less than 2 years, and some of its tubes have corroded and perforated (as there was no anti-corrosion coating); this is mainly due to the severe corrosion caused by the flue gas on the carbon steel tubes. Nowadays, applying anti-corrosion coatings can solve this problem. It is required that the preheater after anti-corrosion treatment can be used for more than 3 years.
The corrosion problem of flue gas preheater tubes is mainly caused by corrosive substances such as SO2, SO3, HF, and HCl present in the flue gas. Applying anti-corrosion coatings is a commonly used solution that can effectively extend the service life of preheaters to over 3 years. .
In this working environment, SO3 condenses easily, causing equipment corrosion. Does adding a coating to the pipe affect the heat transfer efficiency?
Is enamel usually used to solve this? The enamel tubes we use don’t last long either; they are used to handle industrial exhaust gases and fuel oil
If the corrosive components in the flue gas are taken into account, should the material selection have been changed at that time? Or is this device a reused one?