利用吸附余压的煤层气半开式氮膨胀液化流程

Coal bed methane liquefaction by semi-open nitrogen expansive liquefaction process utilizing the residual pressure of adsorption

煤层气（CBM）液化是对其开发利用的一种有效方式。我国煤层气中常常含有较多氮气，要作为能源加以利用，必须进行甲烷提浓。液化前通过变压吸附可以实现氮／甲烷的分离。构建了一种新型的吸附一液化一体化的氮膨胀液化流程，将吸附后排出的带余压氮气用于氮膨胀循环，为煤层气液化提供冷量。通过HYSYS软件模拟计算考察了不同含氮量和不同吸附余压下系统单位产品液化功的变化情况，并与普通氮膨胀液化流程进行比较。结果表明，高含氮量下，一体化的流程能够大大降低系统功耗。

Liquefaction is an effective way for development and utilization of coal bed methane （CBM）. Generally, CBM is usually full of nitrogen, which is usually required to be removed to enrich the methane content when it is utilized as an energy resource. This could be achieved by adsorption before liquefaction. In this paper, a novel nitrogen expansive liquefaction process is proposed, which integrates two parts of adsorption and liquefaction together by introducing the waste nitrogen with residual pressure into the semi-open nitrogen expansive liquefaction cycle. Taking the unit product liquefaction power consumption as the major index and nitrogen content of CBM feed gas together with residual pressure of waste nitrogen as variables, the system performance of this integrated process is studied and compared with that of the nitrogen expansive liquefaction process without integration. By simulation and calculation with HYSYS software, it is confirmed that, for CBM with high nitrogen content, the energy conservation effect is significant.