用焦炉气生产液化天然气的制冷循环

Refrigerating cycle for producing LNG from coke oven gas

经过净化的焦炉气(COG)通过甲烷化反应,使CO和CO2转化成甲烷,COG中原有的组分H2、N2、CO、CO2、CH4、CmHn系统,变成H2、N2、CH4系统。本文提出了用低温分离的方法将CH4与H2、N2分离,得到纯度(体积分数)99.5%以上的甲烷,并再进行液化,得到液体甲烷(LNG)的工艺流程,并评述了采用产品甲烷作为制冷剂的带有预冷的后置式甲烷绝热膨胀制冷循环及带有预冷的高压甲烷二次节流制冷循环。

Carbon monoxide and carbon dioxide in purified coke oven gas （COG） could be converted to methane by methanation, which changed the COG from a system containing H2, N2, CO, CO2, CH4 and CmHn to a system consisted of H2, N2 and CH4. A two-stage refrigerating cycle process for production of high purity liquid methane （LNG） from the system containing H2, N2 and CH4 was proposed, in which, CH4 was firstly separated via cryogenic method, then a liquefaction procedure was performed to obtain liquid methane with a purity of above 99.5%. The rearmounted methane adiabatic expansion refrigeration cycle with precooling and product methane as refrigerant and the refrigerating cycle of two stage throttles by methane at high oressure with Drecoolinz were discussed.