Techno-economic assessment and comparison of absorption and membrane CO2 capture processes for iron and steel industry

An economic assessment of the post-combustion CO2 capture process for the iron and steel industry is presented herein. Absorption- and membrane-based CO2 capture processes were modeled and simulated using Unisim® and MATLAB®, and an economic assessment based on the multiparameter scaling methodology was used to evaluate the economics of the CO2 capture processes. Flue gases with CO2 concentrations in the range of 4.8–27.3 mol% were selected from a typical steel plant, and their techno-economic impact on process design and CO2 capture cost was systematically analyzed. As the flue gas CO2 concentration increased from 4.8 to 27.3 mol%, the CO2 capture cost of the absorption-based process without CO2 compression decreased from 73.5 USD2019/tCO2 to 55.3 USD2019/tCO2, and that of the membrane-based process decreased from 271.7 USD2019/tCO2 to 41.7 USD2019/tCO2. The economics of the CO2 compression process integrated case were also evaluated. This dramatic change in the capture cost for membrane systems is related to the high partial pressure of CO2 being favored for membranes, compared to absorption-based processes. The case study confirms that the membrane-based CO2 capture process becomes more cost-effective and energy-efficient than the absorption-based process as the CO2 concentration of flue gas increases.