【Weekly Topic】12.21~12.27 Heat pipe corrosion in air preheaters
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Topic: How can air preheaters be improved to effectively reduce heat pipe corrosion and extend their service life?
The lowest wall temperature of the heat pipe air preheater can reach 126°C, **which is higher than the highest temperature of the flue gas dew point of 60°C, as well as higher than the acid dew point of that coal type (around 120°C). This helps to effectively prevent dew formation, corrosion, ash deposition, and wear in the lower sections of the air preheater. An excessively low flue gas temperature can cause dew point corrosion of the equipment, reducing the service life of the air preheater. To this end, the motivation is to avoid corrosion caused by flue gas dew point and improve thermal efficiency.
Use air preheaters resistant to dew point corrosion, such as tin-based alloy composites； Heat enhancement technology using external fins and internal turbulators
The lowest wall temperature of the heat pipe air preheater can reach 126°C, **which is higher than the highest temperature of the flue gas dew point of 60°C, as well as higher than the acid dew point of that coal type (around 120°C). This helps to effectively prevent dew formation, corrosion, ash deposition, and wear in the lower sections of the air preheater. An excessively low flue gas temperature can cause dew point corrosion of the equipment, reducing the service life of the air preheater. To this end, the motivation is to avoid corrosion caused by flue gas dew point and improve thermal efficiency.
How can air preheaters be improved to effectively reduce heat pipe corrosion and extend their service life? By adjusting the heat flux density on the heating side and the cooling side of the heat pipe, as well as changing the heat transfer areas on these sides, it is possible to effectively prevent acid dew point corrosion of the heat exchange tubes by the fluid, thereby extending the service life of the equipment.
By adjusting the heat flux density on the heating side and the cooling side of the heat pipe, as well as changing the heat transfer areas on these sides, it is possible to effectively prevent acid dew point corrosion of the heat exchange tubes by the fluid, thereby extending the service life of the equipment.
Too low a flue gas temperature can lead to corrosion caused by the sulfuric acid dew point in the flue gases, and the dew point temperature increases as the sulfur content in the fuel rises. In addition, scaling may occur in the air preheater; the pH value of such scale can sometimes reach 1–2, which not only reduces the heat transfer coefficient and increases pressure losses but also causes corrosion beneath the scale in the air preheater. The service life of air preheaters can be extended through proper design, by using materials resistant to corrosion caused by the sulfuric acid dew point in flue gases (such as ND steel). Anti-corrosion coatings (such as titanium nano anti-corrosion coatings) can also be applied to air preheaters to protect them and thereby prolong their service life.
How can air preheaters be improved to effectively reduce heat pipe corrosion and extend their service life?
Upgrade the material to increase the temperature after cooling! Ensure that the sulfur content in the gas meets the required standards
By adjusting the heat flux density on the heating side and the cooling side of the heat pipe, as well as changing the heat transfer areas on these sides, it is possible to effectively prevent acid dew point corrosion of the heat exchange tubes by the fluid, thereby extending the service life of the equipment.
Too low a flue gas temperature can lead to corrosion caused by the sulfuric acid dew point in the flue gases, and the dew point temperature increases as the sulfur content in the fuel rises. In addition, scaling may occur in the air preheater; the pH value of such scale can sometimes reach 1–2, which not only reduces the heat transfer coefficient and increases pressure losses but also causes corrosion beneath the scale in the air preheater. The service life of air preheaters can be extended through proper design, by using materials resistant to corrosion caused by the sulfuric acid dew point in flue gases (such as ND steel). Anti-corrosion coatings (such as titanium nano anti-corrosion coatings) can also be applied to air preheaters to protect them and thereby prolong their service life.