Flue gas (sometimes called exhaust gas or stack gas) refers to the gas released by combustion plants, consisting of the reaction products of fuel and combustion air and residual substances such as sulfur oxides, nitrogen oxides, and carbon oxides. If flue gas left untreated, it can have a significant impact on the air quality of both local and regional areas while also increasing the possibility of acid rain. A verity of technologies has been proposed to eliminate acidic pollutants from flue gas.
Wet flue gas desulfurization stands as the prevailing technology for the abatement of SO2 emissions from industrial effluents due to its remarkable efficacy and reliability. During this process, a solution of an alkaline chemical reagent such as limestone (CaCO3), lime (CaO), ammonia (NH3), or sodium hydroxide (NaOH) is employed as a water suspension or solution to convert SO2 to either liquid or solid waste byproducts.
In NOx removal, selective catalytic reduction (SCR) is the most practiced and well-established method. Many different materials have been assessed as catalysts for this process. Nonetheless, the catalyst most commonly utilized in industrial plants to carry out the selective catalytic reduction process is vanadium oxide (known as V2O5).
For the purpose of eliminating both SO2 and CO2, the use of amine treating comes into play. Additionally, there exist adsorption-based techniques which have the capability of co-adsorption of SOX, NOX and CO2.
Flue gas contaminants, environmental requirements and availability of resources would determine the suitable method to remove acidic components from flue gas.