EFFECTS OF HYDROGEN CONTENT ON NITROGEN EXPANSION LIQUEFACTION PROCESS OF COKE OVEN GAS

摘要

Coke oven gas (COG) is a by-product when producing coke from coal. It is notalways easy to make use of COG, causing waste of energy. Producing liquefiednatural gas (LNG) is an efficient way of utilizing COG. The amount of hydrogenaffects liquefaction process significantly, because its thermal properties are quitedifferent from the other compositions (methane, carbon monoxide, etc.) of COG.Based on nitrogen expansion liquefaction process, this paper simulates a series ofliquefaction processes of COG containing different amount of hydrogen. Afteroptimizing these processes and comparing their parameters, it turns out that thehydrogen content exerts a great influence on the unit power consumption and theliquefaction rate of the processes; however, its effect on the product purity is notdistinct. Furthermore, the liquefaction process is integrated with distillation separationof hydrogen to upgrade the quality of LNG. The ways of achieving energy integrationbetween liquefaction and distillation are suggested, and the influences of someimportant parameters, such as the highest pressure of nitrogen cycle, are analyzed.