Flue gas is a mixture of gases resulting from combustion and other reactions in a furnace, passing off through the smoke flue, composed largely of nitrogen, carbon dioxide, carbon monoxide, water vapor, and often sulfur dioxide
The following industries are the major generators of flue gas:
Power generation, Oil & Gas, Petrochemical, Metals, Construction materials, Polymers manufacturing, Waste incineration and thermal recycling.
When humans burn fossil fuels, sulfur dioxide (SO2), nitrogen oxides (NOx), hydrogen sulphide, hydrogen chloride, etc, are released into the atmosphere. Those air pollutants react with water, oxygen, and other substances to form airborne sulfuric and nitric acid which then mix with water and other materials before falling to the ground as acid rain. Acidic particles and gases can also deposit from the atmosphere to surfaces in the absence of moisture as dry deposition. When the accumulated acids are washed off a surface by the next rain, this acidic water flows over and through the ground, and can harm plants and wildlife, such as insects and fish.