Analysis of Corrosion Mechanism in Metal Compensation Devices of Refinery Waste Heat Boilers

Analysis of Corrosion Mechanism in Metal Compensators for Heat Recovery Boilers in Refineries

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The world's oil and fuel gases all contain a certain amount of impurities. Due to the burning process, these impurities are expected to convert into 50%.

The process involves 50, producing dead acid vapor with the condensation of water and air, with an extremely low residual content. The first stage cannot be excessively wide, ensuring no harm to the waste heat protection. Therefore, the most crucial factor in the acid dew point corrosion process is 50, which generates in two modes: particulate oxidation and molecular oxidation.

Factors Influencing the Corrosion of Metal Dew Point Deposition Compensators in Flue Gas

The dew point temperature of flue gas, in addition to being related to the excess air coefficient affecting the quantity of sulfur dioxide (SO2) in the flue gas, also increases with the rise in the content of large particles in the flue gas. In heating furnaces primarily fueled by fuel oil, the volume content of water vapor in the flue gas is generally around 10% to 12%. Under these conditions, the dew point temperature mainly rises with the increase in SO2 quantity. Moreover, due to variations in the volume content of water vapor and SO2 in the flue gas, the concentration of condensed acidic substances on the cold wall surface differs.

The practical measurement results also reveal that the dew point corrosion of metal compensators is highly related to the surface temperature of the metal. When the surface temperature of the metal is lower than the dew point of the flue gas, acidic liquids form on the metal heat exchange surface, which subsequently corrode the metal surface. As the surface temperature of the metal and the ambient temperature rise, and exceed the dew point of the flue gas, acidic liquids no longer form. Even if the flue gas contains a high amount of moisture, it will vaporize under high temperatures or evaporate from the surface of the metal, thus no longer corroding the metal.

The inlet temperature of the waste heat boiler is significantly higher than the dew point of the flue gas. Dew point liquid may only form when the ambient temperature, at least the surface temperature of the metal, is below the dew point temperature. This can lead to dew point corrosion on the metal compensator. Therefore, ambient temperature is one of the factors affecting dew point corrosion.