| dc.description.abstract | The steelmaking industry generates coke oven gas (COG), blast furnace gas (BFG), and Linz-Donawitz converter gas (LDG) during the steelmaking process. The heating value of LDG is lower than that of COG, and it contains the highest proportion of CO among the three gases. After separation and purification, CO can be used as the raw material of synthetic chemistry, which has high economic value. It can also achieve the goal of circular economy.
In this study, pressure swing adsorption (PSA) was applied to separate LDG and BFG by simulation study. The composition of LDG was 1.4% H2, 21.3% CO2, 15.8% N2, and 61.5% CO. Furthermore, the composition of BFG was 2.76% H2, 21.27% CO2, 55.19% N2, and 20.78% CO. The zeolite 5A and PU-1 are used to separate and purify CO. PU-1 has high CO adsorption amount and CO/N2 selectivity. However, it has low CO/CO2 selectivity. So a two stage two-bed six-step pressure swing adsorption process for LDG and BFG was designed. The zeolite 5A and PU-1 were adsorbents of the first stage PSA and the second stage PSA, respectively. The first stage PSA process was applied to separate CO2 from LDG and BFG. The outlet stream from the first stage PSA contains low concentration CO2 is taken as the inlet of the second stage PSA process. The second stage PSA process was applied to separate and purify CO from LDG and BFG. When LDG and BFG are taken as the inlet of the PSA process, this study showed that the bottom product CO purity of 96.29% and 95.25% with the recovery of 77.94% and 66.65%, respectively.
Finally, the copper modified adsorbent of Cu(I)AC can be used to separate and purify CO from LDG due to its high CO adsorption amount, CO/CO2 selectivity and CO/N2 selectivity. Therefore, a single-stage three-bed nine-step pressure swing adsorption process for LDG was designed. Because the H2 concentration is much lower than other components in LDG, H2 concentration can be lumped into N2 concentration in this study. The composition of LDG was assumed 16.9% CO2, 18.3% N2, and 64.8% CO, which is taken as the inlet of PSA process. After simulation analysis and design of experiments, this study showed that the bottom product has a CO purity of 95.08% with a recovery of 90.17%, while at step 1/4/7 time 120 s, step 2/5/8 time 48 s, step 3/6/9 time 30 s, bed length 80 cm, feed pressure 1.95 atm, cocurrent depressurization pressure 0.4 atm, and vacuum pressure 0.05 atm. | en_US |