Does high-temperature sulfur dioxide react with water vapor?
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The high-temperature flue gas is at 370°C, containing 20% sulfur dioxide and 15% water vapor; will a chemical reaction occur in the flue duct? What material is good for flue ducts?
Dew point corrosion occurs on the pipe walls, as sulfur dioxide contains sulfur trioxide; when this reacts with water vapor to form water, sulfuric acid is produced. The corrosion rate of sulfuric acid increases at high temperatures, and metal materials generally begin to corrode within minutes under such conditions. Add WeChat to discuss: 18196202161
It is as follows: flue gas dew point corrosion occurs when the flue gas temperature is low enough for condensation to form, and this condensed water causes corrosion and damage to the metal. The dew point temperature is related to the sulfur content of the fuel, so the dew point temperatures are not exactly the same. Depending on the sulfur content of the fuel, the dew point temperature is generally in the range of 105–130°C. When possible, it is best to use the dew point temperature for actual measurements on-site. If the operating conditions are high-temperature flue gas at 370°C, containing 20% sulfur dioxide and 15% water vapor. Such conditions are not caused by metal degradation due to dew point corrosion; rather, other causes of corrosion affect the metal. However, these conditions do not cause as severe metal corrosion as low-temperature dew point corrosion. One can consult literature and draw on other experiences to select materials appropriately.
If the operating conditions are high-temperature flue gas at 370°C, containing 20% sulfur dioxide and 15% water vapor. Such conditions are not caused by dew point corrosion
The materials produced using current manufacturing processes are not pure; for example, sulfur contains trace amounts of other minerals, and as a result, the flue gas contains various other impurity gases. Therefore, the value of the mixed dew point will vary. Furthermore, have you monitored the temperature of the pipe walls? If not, I suggest that you measure it while the system is in operation. If the temperature is between 200–300°C, it’s best to increase the thickness of the insulation layer to ensure that the pipe wall temperature remains above the dew point temperature. I hope this helps you.
No high temperature is needed; sulfur dioxide reacts with water at room temperature to form sulfurous acid. In flues, when there is excess oxygen present, sulfurous acid, which is formed from sulfur dioxide and water, is quickly oxidized to sulfuric acid; this is a major cause of dew point corrosion in flues.