Keywords: absorption, aqueous ammonia, ammonium bicarbonate, ammonium nitrate, ammonium sulfate, carbon dioxide loading, desulfurisation, fertilizer, heat of reaction, monoethanolamine, oxidation, regeneration
Aqua ammonia process for simultaneous removal of CO2, SO2 and NOx
Experimental research work in applying aqueous ammonia solution for the simultaneous reduction of acidic gaseous emission from fossil fuel-fired utility plants is currently being performed at the National Energy Technology Laboratory. The traditional monoethanolamine process for CO2 removal suffers the disadvantages of low carbon dioxide loading capacity, equipment corrosion, amine degradation by SO2 and O2 in flue gas, and high energy penalty during absorbent regeneration. The aqueous ammonia process can simultaneously remove CO2, SO2, NOx, plus HCl and HF that may exist in the flue gas. There could be oxidation of SO2 and NO prior to contacting the aqueous ammonia absorbent. Test results pertaining to the ammonia/carbon dioxide reaction in a semi-continuous reactor system are presented. The parametric effects of sparger design, reaction temperature, and ammonia concentration on gas loadings and absorption rates are discussed. Regeneration test results, including solution-cycling between the regeneration and absorption steps to determine a realistic loading capacity for the ammonia solutions are also presented.