Carbon Dioxide Capture Technology For Blast Furnace Gas Of Iron And Steel Industry

The CO2 emissions of China’s steel industry are huge.The main source of CO2 emissions in the steel industry is blast furnace gas.CO2 capture of blast furnace gas is very important for industrial carbon emission reduction.Based on the characteristics of blast furnace gas,this study analyzes the influence of physical and chemical properties of flue gas on capture technology.Combining the capture technology principle and process characteristics,the characteristics of capture technology are analyzed from four aspects:physical and chemical properties of capture products,environmental benefits of capture materials,operating conditions,characteristics of capture technology.The membrane separation method was chosen as the carbon capture method for blast furnace gas.On this basis,the membrane separation and cryogenic technology were integrated,and the hybrid capture technology was studied.In this study,the membrane separation technology and membrane&cryogenic hybrid technology were simulated by PROII software.The variation of parameters such as capture purity,capture rate and capture energy consumption of CO2 in blast furnace gas was studied.Under the condition of obtaining liquid products with the same partial pressure of CO2,the characteristics of the capture performance of the membrane-cryogenic hybrid process and membrane separation process were compared and analyzed.Studies have shown that single-stage membrane separation process captures CO2 in blast furnace gas,which is difficult to achieve high capture purity and high capture rate at the same time.As for a membrane material having preferential permeability to CO2 and following the principle of dissolution and diffusion,reducing temperature can increase the purity of CO2,but will reduce the capture rate of CO2-Under the conditions of constant pressure ratio on both sides of the membrane module and CO2 capture purity of the permeate gas,increasing the pressure of the feed gas will result in an increase in CO2 capture energy consumption but a decrease in membrane area.Increasing the pressure ratio on both sides of the membrane module can simultaneously increase the capture purity and capture rate of CO2,but the energy consumption per unit capture increases.The simultaneous use of the compressor and the vacuum pump balances the high energy consumption when using only the compressor and the high membrane area when only the vacuum pump is used.By reflowing the flue gas in the process,increasing the order of the membrane module can improve the overall capture performance of the process.Optimizing the pressure conditions on both sides of the membrane module can reduce the total membrane area and improve the capture performance of the process.Membrane-cryogenic hybrid systerm can increase the CO2 capture rate by flue gas reflux and increase the stage of stripping membrane module.The capture rate of hybrid process is greatly affected by the capture rate of the membrane separation unit.Increasing the concentration of CO2 in the reflux gas can improve the capture performance of the membrane separation unit.And the capture rate of the hybrid systerm is related to the amount of substance of CO2 in the reflux gas.By optimizing the operating conditions of the hybrid systerm,the unit capture energy consumption can be reduced,and the capture performance of hybrid systerm is superior to the membrane separation process.