Vacuum pressure swing adsorption for efficient off-gas recycling: Techno-economic and CO2 abatement study

Abstract

We suggest a vacuum pressure swing adsorption that uses CuCl/Boehmite adsorbent as a novel material to efficiently recycle a blast furnace gas into the blast furnace and discuss the techno-economic and CO2 abatement impact. To identify the crucial factors of the separation, five cases are simulated: three adsorption pressures at moderate CO purity, and three purity levels at moderate adsorption pressure. Also, the coke-replacement effects are estimated through the blast furnace simulation to consider the economic benefits. The result shows that the energy efficiency of the separation process varied 72–82%, and injection of highly purified off-gas (99% purity) was the most economically profitable, giving 86.7 US-MM$ of net present value. Cost sensitivity showed that the coke price is the most influential, but the adsorbent cost and carbon taxes have relatively little effect. In the best case, the coke-replacement ratio is 0.26kgCoke mgas−3. The suggested process reduces net emission by 0.19tCO2-eq tHM−1, and this corresponds to the 10% of net reduction which is the competitive strategy compared with the renewable hydrogen blast furnace. This study broadened the understanding of the separation process for off-gas recycling, and optimization of the process should be studied further.