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    降低CO2捕集能耗的少水吸收剂吸收-解吸性能研究

    Research on absorption-desorption performance of low-water absorbents for energy-efficient CO2 capture

    • 摘要: 基于醇胺水溶液的化学吸收法是CO2捕集主要方法,其应用仍受限于稀释剂-水的高蒸发焓导致用于吸收剂再生的能耗较高。文中构建了胺∶物理溶剂∶水=30∶60∶10(质量比)的少水吸收剂,并基于盐析效应筛选出适宜的物理溶剂(聚乙二醇二甲醚,NHD)以降低吸收剂的升温显热和水蒸发潜热。进一步地,借鉴混合胺可充分发挥不同胺的优势的思路,将低反应热的N-甲基二乙醇胺(MDEA)与伯/仲胺复配形成混合胺少水相变吸收剂降低了解吸反应热和再生能耗。优选地,质量比为N-乙基乙醇胺(EAE)∶MDEA∶NHD∶H2O=10∶20∶60∶10的少水相变吸收剂的再生能耗为1.92 GJ·t−1(以CO2计),远低于工业常用质量分数30% MEA水溶液的再生能耗(约为4 GJ·t−1)。

       

      Abstract: The chemical absorption based on aqueous alkanolamine solutions is a leading technology for CO2 capture. However, its widespread application is still constrained by the high energy penalty associated with solvent regeneration, due to the high latent heat of water evaporation. To mitigate this, we formulated a water-lean absorbent with a mass ratio of amine∶physical solvent∶water of 30∶60∶10. Based on salting-out effect, polyethylene glycol dimethyl ether (NHD) was selected as the favorable physical solvent to formulate water-lean phase change absorbent, aiming to reduce both the sensible heat required for heating and the latent heat of evaporation. Furthermore, inspired by the concept of blended amines that synergistically combine the advantages of different amines, the N-methyldiethanolamine (MDEA), known for its low reaction heat, was blended with primary/secondary amines to develop water-lean phase change absorbent. This approach significantly reduced the reaction heat during desorption process and the overall regeneration energy consumption. Notably, the optimized absorbent with a mass ratio of 2-(ethylamino)ethanol (EAE)∶MDEA∶NHD∶H2O of 10∶20∶60∶10 exhibited a remarkably low regeneration energy of 1.92 GJ·t−1 (measure by CO2), which is significantly lower than that of the benchmark 30% (mass fraction) monoethanolamine (MEA) aqueous solution (~4 GJ·t−1).

       

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