含氧煤层气的液化及杂质分离

Liquefaction and impurity separation of oxygen-contained coalbed methane gas

煤层气是一种新型清洁能源,但是大部分含氧煤层气由于加工处理技术的限制没有被合理利用,而是直接被放空,不仅造成了资源的浪费,而且还会严重污染大气环境。为了更好地合理利用含氧煤层气,针对大庆庆深气田含氧煤层气气源条件和组分特点,设计了一种新型的煤层气液化及杂质分离工艺流程,采用精馏塔在低温条件下脱除煤层气中的氧气和氮气,精馏塔塔顶冷凝器和塔底再沸器的能量都分别取自于流程中的制冷剂冷却系统和煤层气液化系统,且从塔顶流出的低温杂质气体返回换热器进行冷量回收。采用流程处理软件HYSYS模拟计算的结果表明,所设计的工艺流程能耗较低,精馏塔脱氧脱氮彻底,产品中甲烷纯度高,甲烷回收率较高,该工艺流程的气源适应性和操作安全性都较好。该液化工艺流程的设计为含氧煤层气的液化及杂质分离提供了一种参考方法。

Coalbed methane(CBM) gas is a kind of new alternative energy resources,but due to the technical limitations,most oxygen-contained CBM gases have to be vented directly into air instead of being reasonably utilized.This will result in not only waste of huge resources but also heavy air pollution.In view of this,based on the gas origin condition and composition features of the oxygen-contained CBM gas in the Qingshen Gas Field found by the Daqing Oilfield Company,a new type of liquefaction and impurity separation process is designed.First,oxygen and nitrogen gases are removed from the CBM gas under low temperature in the rectifying tower.Second,the energy used for the condenser at the top of the tower and the reboiler at the bottom of the tower comes from the refrigeration system and the liquefaction system respectively,meanwhile the low-temperature impurities of gases escaping out of the top tower will be led into the heat exchanger,where cold energy can be thus recovered.The simulation result by use of HYSYS shows that the energy consumption of this designed flow process is rather low;the oxygen and nitrogen gases are removed completely in the rectifying tower;the purity of methane is extremely high in the liquefied CBM with a high methane recovery rate,and the most important of all,this flow process is of high adaptability to many kinds of feed gases and of high operability and reliability.This provides a new approach to the liquefaction and impurity separation processes of oxygen-contained CBM gases.