合成氨原料气双甲(醇烷化)精制工艺条件的讨论

Process conditions for methanolization and methanation purification of ammonia synthesis feed gas

介绍了双甲精制工艺条件的有关技术概念,阐述了合成原料气双甲精制工艺的实质是甲醇化和甲烷化,醇烷化就是甲醇化甲烷化,只有醇烃化才是双甲工艺的扩展提升技术。说明了双甲工艺的压力可在5.0～30.0 MPa进行,甲醇化以中低压节能,进第二级甲醇化CO+CO2以1.8%～2%、出口CO+CO2以0.1%～0.15%运行能耗最少;在合成气精制工艺中甲烷化不可能产生自热反应。通过对3种补充热方式进行分析评述,说明了用氨合成出塔热气加热甲烷化未反应气存在设备安全隐患和开车顺序倒置等难题。

Some technical concepts of process conditions for methanolization and methanation purification of ammonia synthesis feed gas are presented. The above purification process could be operated under the pressure of 5.0-30.0 MPa., but methanolization should be operated under a medium or low pressure to save energy. In the second-stage of methanolization, CO＋CO2 at the inlet should be 1.8 %-2% and CO＋CO2 at the outlet should be 0.1%-0.15 % so that the energy consumption could be the least. Autothermic reaction of methanation could not take place when purifying the synthesis feed gas. By analyzing and assessing three supplemental ways of heating, there are some difficult problems, such as safety concerns of the equipment, inversion of the operation order, etc., when heating unreacted gas in methanation with exit hot gas from ammonia synthesis.