Control Flue Gas Acid Dew Point To Prevent Low-temperature Acid Corrosion Of Boilers

Coal, oil and other fuels contain a certain amount of sulfur. During the combustion process, sulfur combines with oxygen to generate sulfur dioxide and trace sulfur trioxide. These trace amounts of sulfur trioxide greatly increase the flue gas dew point. When the temperature of the heating surface at the rear of the boiler is lower than the flue gas dew point, a highly concentrated sulfuric acid solution will condense on the wall, causing serious corrosion. Therefore, this dew point is called the acid dew point. Correctly measuring the flue gas acid dew point can control the appropriate exhaust temperature, prevent condensation corrosion, and recover as much heat as possible to ensure the safe and economical operation of the boiler.

The flue gas acid dew point is the temperature at which the liquid reaches a two-phase equilibrium with the steam covering its surface. The boiler flue gas contains about 10% H2O steam and a certain amount of SO3. When the temperature is below 200°C, SO3 and H2O generate H2SO4 steam. Therefore, the flue gas acid dew point is the temperature at which the H2O-H2SO4 mixed steam and the H2O-H2SO4 solution are in two-phase equilibrium.

After using the flue gas acid dew point analyzer, you can accurately know the acid dew point value in the flue gas of the boiler and heating furnace, as well as the oxygen content, water vapor (% water vapor value) or dew point value (-50℃～100℃) and water content (G grams/KG per kilogram) and humidity value RH. Users can control the exhaust gas temperature within a range slightly higher than the flue gas acid dew point according to the instrument display or 2-way 4-20mA output signal to avoid low-temperature acid corrosion and increase boiler operation safety.