Portable Sulphuric Acid Dewpoint Temperature Monitor
The fuels used in boilers, such as coal, heavy oil and natural gas, contains
S. during the combustion process, S and O₂ form SO₂, and a small amount of SO₂ is converted into SO₃ under catalysis of Fe₂O₃, V₂O₅ and other catalysts. Under
normal circumstances, the volume of SO₃ in the boiler flue gas is
1×10-6～50×10-6, and the water vapor is about 10%. When the temperature of the
flue gas is below 200°C, SO₃ and the water vapor are completely combined into
H₂SO₄ vapor. A small amount of H₂SO4 vapor will significantly increases the acid
dew point. When the surface temperature of the boiler heat exchange equipment is
lower than the flue gas acid dew point, the H₂SO₄ vapor will condense on the
surface to become sulfuric acid solution with a concentration of about 80%,
which will adhere to the surface of the heat exchanger and cause acid corrosion.
Typical equipment that is prone to corrosion includes air preheaters, induced
draft fans and flue walls.
