A feasible process for simultaneous removal of CO2, SO2 and NOx in the cement industry by NH3 scrubbing

With the rapid economic and industrial development, the concentration of carbon dioxide in the atmosphere is increasing enormously, which has greatly affected the global climate and human living environment. At present, a lot of technologies have been applied to CO2 removal in fossil fuel-fired power plants, which are one of the main CO2 emission sources. But few researches have been done in the cement industry, which is the third largest CO2 emission source. There is no mature technology of CO2 removal in cement industry mentioned before. This paper proposes a feasible process for simultaneous removal of CO2, SO2 and NOx in the cement industry by NH3 scrubbing. As there is no ready steam source for the regeneration of CO2-rich loading solvent after absorption, a process with the final product of ammonium bicarbonate is developed. With the oxidative additive of NaClO2 added in the aqueous ammonium absorbent, the simultaneous removal of CO2, SO2 and NOx is feasible by NH3 scrubbing. The products of the process are mainly ammonium bicarbonate, ammonium sulfate and ammonium nitrate, which are all good fertilizers for crops and plants. The crystallization of NH4HCO3 is easier for storage and transportation than that for liquid carbon dioxide, which becomes more stable when dicyandiamide (DCD) is added. The thermodynamic analysis proves that the proposed process has the advantages of energy conservation and high thermodynamic perfection degree compared with the traditional ones.