超重力吸收与批式解吸工艺结合用于乙醇胺(MEA)-乙醇溶液沼气脱碳的研究

High gravity absorption and batch desorption of CO_(2) from biogas using a monoethanolamine (MEA)/ethanol solution

利用超重力反应器对乙醇胺(MEA)-乙醇溶液用于沼气脱碳的吸收性能进行了研究,将批式解吸工艺用于沼气脱碳,对使用了加热器的MEA-乙醇富液的批式解吸性能进行分析。研究发现进液量、进液MEA含量和转子转速的升高以及进气量、进气CO_(2)含量的降低会提升脱碳效果;最佳转子转速为1 000 r/min,此时当进入超重力反应器的n(CO_(2))/n(MEA)<0.4时CO_(2)去除率可以接近100%;解吸液CO_(2)负荷最低可以达到0.03 mol/mol;在MEA浓度4.92 mol/L、解吸时间20 min时,单位解吸能耗(释放单位质量CO_(2)的能耗)达到最低,为3.17 MJ/kg,此时解吸液负荷为0.16 mol/mol。批式解吸可以通过控制解吸时间准确地调节解吸液CO_(2)负荷,吸收-解吸循环次数的增加不会导致脱碳效果的恶化。

This study focuses on the following aspects of the absorption-desorption of CO_(2) from biogas using a monoethanolamine(MEA)/ethanol solution: absorption performance in a rotating packed bed(RPB), batch desorption performance using a heater and recycle performance. The results showed that the CO_(2) absorption performance can be improved by increasing the liquid flow rate, MEA concentration and rotational speed, and by decreasing the gas flow rate and inlet CO_(2) content. The optimum rotational speed was 1 000 r/min, under which conditions the CO_(2) removal efficiency reached nearly 100% when the molar ratio of inlet CO_(2) to inlet MEA was less than 0.4. In the case of desorption, the liquid CO_(2) loading could reach as low as 0.03 mol/mol. The minimum energy consumption per unit CO_(2) was 3.17 MJ/kg, obtained with an MEA concentration of 4.92 mol/L, liquid CO_(2) loading of 0.16 mol/mol, and desorption time of 20 minutes. An increase in the number of cycles did not lead to any degradation of the absorbent.