Design and evaluation of CO2 capture plants for the steelmaking industry by means of amine scrubbing and membrane separation

An option considered for reducing carbon emissions in the iron/steel industry is the use of Top-gas recycle blast furnace (TGR-BF), which captures CO2 from the blast furnace gas (BFG) and recycles the remaining CO and H2 back to the blast furnace (BF). This study suggests four different designs of CO2 capture processes suitable for the TGR-BF application: Amine scrubbing, membrane separation, and a hybrid between the amine scrubbing and the membrane separation with and without heat recovery. In particular, the hybrid-with-heat-recovery design recovers the combustion heat of the impurities (e.g., CO and H2) in the captured CO2 stream. The four alternative processes are simulated and evaluated on the basis of multiple criteria including operating cost, capital cost, rate of CO2 avoided, and CO2 avoidance cost with various electricity sources. Furthermore, sensitivity analysis is performed by perturbing the utility prices. Among the four alternatives, the hybrid-with-heat-recovery design is shown to give the best performance with the avoidance cost of $30.4/tonCO2, outperforming the mature technologies.