| 摘要: | 鋼鐵製造產業在煉鋼的過程中會產生煉焦爐氣(coke oven gas, COG)、高爐氣(blast furnace gas, BFG)以及轉爐氣(Linz-Donawitz converter gas, LDG)，其中轉爐氣的熱值較煉焦爐氣低，且對於此三種氣體中其含有最高的一氧化碳組成比例。而一氧化碳經分離純化可作為合成化學的基礎原料，其經濟價值高，且能達到循環經濟的效應。
本研究擬模擬以變壓吸附法(pressure swing adsorption, PSA)分離轉爐氣進料及高爐氣進料中之一氧化碳，以沸石5A及PU-1作為吸附劑。轉爐氣氣體組成為1.4%氫氣、61.5%一氧化碳、21.3%二氧化碳及15.8%氮氣，而高爐氣氣體組成為2.76%氫氣、20.78%一氧化碳、21.27%二氧化碳及55.19%氮氣，其中雖然PU-1具有較高的一氧化碳吸附量以及一氧化碳對氮氣之選擇性，但其一氧化碳對二氧化碳之選擇性較低，故以兩階段雙塔六步驟PSA程序分離轉爐氣及高爐氣。沸石5A及PU-1分別為第一階段PSA及第二階段PSA之吸附劑，第一階段PSA程序目的為分離二氧化碳，產生含有較低二氧化碳濃度之產品氣，並將其作為第二階段PSA程序之進料，分離純化高濃度之一氧化碳。以轉爐氣及高爐氣為進料時，塔底產物一氧化碳純度分別為96.29%及95.25%，且回收率分別為77.94%及66.65%。
最後本研究以銅離子改質之Cu(I)AC作為吸附劑從轉爐氣中分離純化一氧化碳，由於其具有高的一氧化碳吸附量、一氧化碳對二氧化碳之選擇性以及一氧化碳對氮氣之選擇性，因此以一階段三塔九步驟PSA程序分離轉爐氣。因轉爐氣中的氫氣含量相較其他成分低，故於模擬中，氫氣的含量可以併入氮氣含量中，故本研究以16.9%二氧化碳、18.3%氮氣及64.8%一氧化碳作為進料。經過實驗設計分析後可得到最佳操作條件，在步驟1/4/7時間120秒、步驟2/5/8時間48秒、步驟3/6/9時間30秒、塔長80公分、進料壓力1.95 atm、同向減壓壓力0.4 atm及抽真空壓力0.05 atm的操作條件下，能得到塔底產物一氧化碳純度為95.08 %，且回收率為90.17%。;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. |
