富氧燃烧烟气压缩净化及高浓度CO2制备工艺研究

富氧燃烧技术是目前最有可能大规模推广和商业应用的碳捕集与封存技术之一,其中,烟气压缩净化及CO₂提纯对于整个富氧燃烧系统至关重要。然而,目前研究多聚焦于富氧燃烧后烟气压缩净化的工艺验证,而对烟气压缩纯化各单元运行特性的研究仍不深入,特别是烟气压缩净化过程杂质污染组分的迁移转化、系统运行参数与污染物脱除效率的关联仍不明确。且现有研究对净化后烟气的深度提纯及高浓度CO₂制备的关注也相对较少,直接关系到富氧燃烧系统运行经济性。因此,针对富氧燃烧烟气净化及CO₂提纯需求,系统探究了富氧燃烧烟气压缩纯化过程SO₂、NO_x吸收脱除以及CO₂深度提纯等各子系统的运行特性,其中SO₂与NO_x脱除采用压缩-酸液吸收,CO₂深度提纯采用低温精馏。结果表明:通过烟气净化可实现SO₂脱除效率达100%,NO脱除效率达99%,同时实现纯度为99.99%的食品级液态CO₂制备。烟气净化过程中,气相反应占据主导,提高压力可缩短反应时间;当SO₂吸收塔运行压力超过0.8 MPa时,SO₂脱除效率可达100%;当NO吸收塔运行压力超过3.0 MPa时,NO排放浓度可达超低排放标准。CO₂提纯过程中,提高压力会降低液体CO₂纯度。SO₂吸收塔运行压力为1.6 MPa、NO吸收塔运行压力为3.0 MPa、CO₂提纯塔运行压力为3.8 MPa时,系统整体功耗最低,为0.37 MJ/kg。

Technical study of flue gas compression cleaning and high-concentration CO2 production in oxy-fuel combustion

Oxy-fuel combustion is one of the most potential CO₂ capture and storage technologies for large-scale promotion and commercial application,and the flue gas compression purification and CO₂ purification is the core unit in the whole oxy-fuel combustion system.How?ever,the current studies focused on the process verification of flue gas compression purification after oxygen enriched combustion,and the operating characteristics of flue gas compression unit,especially the migration and transformation of impurities in the process of flue gas compression and its relationship between the operating parameters and the removal efficiencies of impurities,were still unclear.Be?sides,little attentions have been paid to the purification and production of CO₂ liquid with high purities,which can significantly affect the economic efficiency of the whole oxy-fuel combustion system.Therefore,in order to meet the needs of oxygen enriched combustion flue gas purification and CO₂ purification,the fundamental operating characteristics of the SO₂ and NO_x absorption removal as well as the purifica?tion of CO₂ in the compression and purification process of oxy-fuel combustion were systematically studied in the present work,in which the removal of SO₂/NO_x were achieved by pressurized acid adsorption and the purification of CO₂ was achieved by cryogenic distillation.The results indicate that the removal of SO₂ and NO by flue gas purification can reach 100%and 99%respectively.Meanwhile,the purity of food grade liquid CO₂ can reach 99.99%.In the process of flue gas cleaning,the gaseous reaction is dominant,and the residence time for the adsorption of both SO₂ and NO can be shortened by the increase of reaction pressures.As the operating pressures of the SO₂ adsorp?tion column increase to more than 0.8 MPa,the removal efficiency of SO₂ can be 100%,and when the operating pressure of NO adsorp?tion column is more than 3.0 MPa,the emission of NO can meet the demands for the state ultra-low emission.The purity of liquid CO₂ de?creases with the increase of operating pressure in the column of CO₂ purification.Furthermore,the energy consumption of CO₂ recovery can be as low as 0.37 MJ/kg CO₂,when the operating pressures for SO₂ removal,NO_x removal,and CO₂ purification are 1.6 MPa,3.0 MPa,and 3.8 MPa.