旋轉填充床中以醇胺吸收劑捕獲二氧化碳之研究

A Study of CO2 Capture by Alkanolamine Solution in a Rotating Packed Bed

王逸民(Yi-Min Wang)

指導教授 ： 陳昱劭

中原大學/工學院/化學工程研究所/碩士(2016年)

https://doi.org/10.6840/cycu201600673

摘要

本研究使用化學吸收法在旋轉填充床(RPB)中進行二氧化碳捕捉，利用乙醇胺(MEA)溶液與2-甲基乙醇胺(MMEA)溶液，由改變轉速、氣體流率、以及吸收劑濃度在不同的進料之二氧化碳負載量(lean loading)下，觀察二氧化碳移除率與KGa的變化，並估算不同配方下的再生能耗，最後再與其他文獻做比較，找出最佳吸收劑配方與操作條件。
實驗結果顯示，當吸收劑進料之lean loading = 0 mol/mol時，二氧化碳移除率會隨轉速與濃度增加而增加，隨氣體流率增加而降低。當進料之lean loading提高至0.15 mol/mol以上時，由於吸收劑黏度大幅提高使80與100 wt%的吸收劑對二氧化碳的移除率則會低於60 wt%。比較MEA溶液與MMEA溶液的移除率，發現當進料之lean loading = 0 mol/mol時，兩者表現相去不遠，提高進料之lean loading至0.15 mol/mol以上時，則是MMEA溶液對二氧化碳移除率都高於MEA溶液。再生能耗隨吸收劑濃度增加而降低，由於MMEA的反應熱與比熱都低於MEA，所以再生MMEA溶液所需能量都低於MEA溶液。
綜合以上結果，使用60 wt% MMEA當吸收劑之CO2 loading = 0.15 mol/mol時，轉速操作在2400 rpm，氣體流率10 L/min，與現有製程常使用40 wt%的MEA比較，移除率可提高7.3%，且可以減少約17.8%的再生能耗。若loading提高到0.25 mol/mol/時，60 wt%的MMEA的移除率比40 wt%的MEA的移除率更可增加50%。再與傳統填充床做相較，其使用RPB可以增加氣液接觸面積提升質傳效率，大幅減少設備體積降低成本，且KGa提升了15倍以上。顯示在RPB中使用高濃度MMEA溶液做為吸收劑吸收二氧化碳極具有開發的潛力。

關鍵字

旋轉填充床 ； 吸收二氧化碳 ； 醇胺濃度 ； 二氧化碳負載量

並列摘要

In this study, using chemical absorption of CO2 was carried out in rotating packed bed using ethanolamine (MEA) and 2-methylethanolamine (MMEA) solution. Effect of rotor speed, gas flow rate, CO2 loading and alkanolamine concentration on CO2 removal efficiency (E) and mass transfer coefficient (KGa) was investigated and the regeneration energy was calculated.
Experimental result showed that, when lean loading was 0 mol/mol, CO2 removal efficiency increased with rotor speed and alkanolamine concentration, but decreased with gas flow rate. When lean loading was higher than 0.15 mol/mol, a reduction of the removal efficiency of the absorbent with an alkanolamine concentration of 80 and 100 wt% was observed because the viscosity was significantly increased. The removal efficiency of MEA and MMEA was similar when lean loading was 0 mol/mol, and the removal efficiency of MMEA became higher for the lean loading higher than 0.15 mol/mol.
The regeneration energy decreased with increased alkanolamine concentration. Besides, the regeneration energy of MMEA was lower than those of MEA. Compared with a conventional packed bed, the KGa was 15 times higher in an RPB because of the higher gas-liquid interfacial area.
Based on the absorption efficiency and regeneration energy required, an optimum absorbent of 60 wt% MMEA was proposed as lean loading was higher than 0.15 mol/mol. Compared with 40 wt% MEA solution, a 7.3% enhancement of removal efficiency and a 17.8% reduction of regeneration energy were achieved by using 60 wt% MMEA solution at a gas rate of 10 L/min, rotor speed of 2400 rpm and lean loading of 0.15 mol/mol. The enhancement of removal efficiency can be further increased to 50% at a lean loading of 0.25 mol/mol. This indicates that using high concentration of MMEA solution has great potential for CO2 capture in an RPB.

並列關鍵字

rotating packed bed ； CO2 absorption ； alkanolamine concentration

參考文獻

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