基于活性炭从煤层气中分离甲烷

为探索不同工艺条件下活性炭204-Ⅱ用于从煤层气中分离CH4的效果，在温度253.2~313.2 K、压力0~0.8 MPa，采用容积法测试CH4，N2纯组分在活性炭204-Ⅱ上的吸附平衡，并在293.2 K、0.1~0.5 MPa进行CH4，N2纯组分及其混合体系在活性炭204-Ⅱ固定床上的动态穿透曲线两塔变压吸附分离试验。采用Langmuir-Freundlich模型描述纯CH4，N2在活性炭204-Ⅱ上的吸附等温线，分析不同温度和压力条件下CH4对N2的吸附选择性，明确降低压力和升高温度可以提高CH4和N2的吸附平衡差异。通过动态微分模型对CH4，N2纯组分的固定床穿透曲线进行理论模拟并计算得到传质系数，结果表明，二者传质系数基本相等，确定了CH4和N2在活性炭上的分离是基于吸附平衡差异的机理。低浓度的煤层气通过一步变压吸附过程的分离效果有限，CH4含量为20.13%和47.46%的煤层气可分别提纯至39.83%和71.38%，不同操作压力下的提纯效果接近(0.1~0.5 MPa)。

Separation methane from the coal bed gas based on activated carbon

In order to investigate the separation efficiency of methane in coal bed gas using activated carbon 204-Ⅱ under various operation conditions，in this study，the adsorption equilibriums of pure methane and nitrogen on activated carbon 204-Ⅱ were measured using the volumetric method.The temperature range was 253.2-313.2 K and the pressure range was 0-0.8 MPa.The breakthrough curves of pure component and mixed methane nitrogen gas through a fixed bed were determined using the open flow method in the pressure rang of 0.1-0.5 MPa at 293.2 K.The separation efficiency was investigated using a two column pressure swing adsorption process.Also，the adsorption equilibrium data of pure methane and nitrogen on activated carbon 204-Ⅱ was fitted with the Langmuir Freundlich model.The selectivity of methane nitrogen under various conditions was discussed.It shows that lower pressure and higher temperature will increase the difference of adsorption amounts between methane and nitrogen.The partial difference equation was adopted to analyze the breakthrough curves of pure methane and nitrogen.Coefficients of k in the linear driving force equation were calculated.The k value of methane is approximately equal to that of nitrogen，which demonstrates that the separation mechanism of methane nitrogen on activated carbon is on the basis of adsorption equilibrium.The enrichment of methane is proved to be limited through one process of pressure swing adsorption.The concentration of methane as 20.13% and 47.46% could be improved to 39.83% and 71.38% respectively.In addition，the separation results are almost equivalent in the pressure range of 0.1-0.5 MPa.