Research On CO₂ Capture With Combined Production Of H₂SO₄ And HNO₃ From Oxy-biomass Combustion Flue Gas

Widespread attention has been paid to the causes and effects of gradual increase in CO₂ concentration in the atmosphere.This paper proposed a new approach that it converted the components of flue gas which was made by straw biomass combusting under O₂/CO₂ atmosphere,i.e.SO₂ and NO_X into sulfuric acid?H₂SO4?and nitric acid?HNO3?with H₂ O under the particular temperature and pressure,and compressed the flue gas CO₂ into liquid CO₂,to collect CO₂ based on oxy-biomass combustion.This new approach could contribute to the clean and efficient utilization of biomass energy resources and the mitigation of air pollution and greenhouse effect.This paper is focused mainly on the comprehensive study of the entire system by using the methods of theoretical analysis,experimental research and Aspen Plus simulation,and it also verified the feasibility of oxy-biomass combustion,the conversions of SO₂ and NO to H₂SO4 and HNO3 respectively and the process of processing and capturing CO₂ from flue gas.Firstly,this paper verified the feasibility of oxy-biomass combustion,and summarized the technological process of CO₂ capture with combined production of H₂SO4 and HNO3 from oxy-biomass combustion flue gas.This paper also analyzed the compressing process of CO₂ in oxy-biomass combustion flue gas,and based on the relevant knowledge,the reaction mechanisms in the experiment and simulation were analyzed.Secondly,the experimental research was carried out on the high-pressure system,and the influences of parameters i.e.pressure and temperature on the conversion rate of SO₂ and NO_X were verified through experiment.The results show that the absorption rates of SO₂ and NO increase with the increasing of pressure,while elevating the temperature restricts the absorption rates of SO₂ and NO.Through the detections of outlet gas and ion concentrations,it can be obtained that the conversions of SO₂ to H₂SO4 and NO to HNO3 are incompletely,the absorption rates of SO₂ and NO are higher than the conversion rates of SO₂ and NO respectively.In the overall reaction,SO₂ reacts eailer than NO,and NO acts as catalysts in the conversion of SO₂.Finally,this paper established the whole process of CO₂ capture combined production of H₂SO4 and HNO3 under oxy-biomass combustion flue gas by using the software Aspen Plus,and the results were analyzed by using the method of sensitivity analysis.The results of simulation show that SO₂ and NO conversion rate in flue gas can reach more than 90% under the condition of 30? and 3 MPa.Through sensitivity analysis,it can be found that the longer residence time,the higher conversion rate of NO under the condition of a certain pressure.Higher pressure and lower temperature favor the absorption and conversion of SO₂ and NO.