Technical And Economic Analysis Of CO₂ Capture From Blast Furnace Gas By Synergic Process Of Membrane Separation And Pressure Swing Adsorption

It is widely recognized that carbon dioxide is the primary greenhouse gas causing greenhouse effect.The amount of carbon dioxide emission from iron and steel industry is huge.Blast furnace gas is the main carbon dioxide emission source in iron and steel industry.CO2 capture of blast furnace gas is considered to be one of the key technologies to achieve large-scale CO2 emission reduction and carbon neutralization in iron and steel industry.Membrane separation and pressure swing adsorption(PSA)are two emerging dry carbon dioxide capture technologies.Both technologies have the limitation of high energy consumption and low capture rate when they are separately applied to the flue gas with low CO2 concentration.The hybrid of membrane separation and PSA,however,can realize synergism with the energy cascade utilization and the optimal match of the two processess,resulting in a reduction of energy consumption and increase of CO2 capture rate.The simulation of hybrid process can helpidentify the technical approach in terms of energy reduction and capture rate improvement.However,previous simulation studies on the hybrid of membrane-PSA processes simply use the steady-state circular simplified model to replace the dynamic cycle process of PSA in membrane-PSA hybrid processes,thus could hardly reflect gas flow mismatch between two processes,leading to the inaccuracy of simulation results.At the same time,previous studies on the economics of blast furnace gas carbon capture were limited to the cost analysis of carbon capture withoutt consideration of the indirect economic benefits of calorific value increase after carbon capture from blast furnace gas.By studying the hybrid mechanism of membrane separation and adsorption carbon capture,this paper analyzed the membrane-PSA hybrid processes andestablished the simulation model of membrane-PSA hybrid processes.At the same time,the existing simulation model of membrane separation-PSA synergistic system was improved.Then,the membrane separation-pressure swing adsorption synergistic system was used to simulate the carbon capture process of steel blast furnace gas.Based on different operating conditions,the carbon capture process of blast furnace gas was simulated by the optimized membrane-PSA hybrid processs.The indirect economic effect of CO2 capture on calorific value of blast furnace gas was identified,and the technical and economic assessment of CO2 capture by the optimized membrane separation-PSA system was systematically conducted.The results of a case study indicated that the steady-state and dynamic process are well integrated by introducing a flow rate correction coefficient.Compared with the previous simulation methods,our technical approach can even help identify the technical pathway towards energy consumption reduction and capture rate improvement.The indirect economic benefits of the calorific value increase of blast furnace gas after carbon capture are related to factors such as synergetic system inflow and outflow rates,CO2 capture rate,and CO2 product purity.