煤制甲醇中的合成气深冷分离制LNG的工艺研发

Technical research and development of cryogenically separating LNG from syngas in coal-to-methanol

关键词:  深冷分离  甲醇合成气  LNG  膨胀制冷循环  精馏塔

Key words:  cryogenic separation  methanol syngas  LNG  refrigeration cycle with expander  distillation column

摘要:

基于杭氧承担的国内煤制芳烃10×10⁴ t/a项目中的合成气深冷分离制LNG成套装置为背景,研发出一种带膨胀机的液化工艺。利用高压氮气通过透平膨胀机绝热膨胀的循环制冷提供大部分冷量,并利用双塔低温精馏实现合成气的分离与LNG的液化,气体在膨胀机中膨胀降温的同时,能够输出功并用于驱动增压机。该工艺相对于混合冷剂工艺来说,具有整体紧凑、占地面积小、冷剂消耗少(约89%)、综合运行成本较低、安全性高、启动时间短以及适应在70%~110%的变负荷工况下运行等特点,充分实现了从工艺到设备国产化的目标。

Abstract:

Based on a complete set of equipment of cryogenically separating LNG from syngas in the domestic project from coal to aromatics of 100 000 tons/year which was undertaken by Hangyang Limited, a liquefaction process with expander has been developed. Most of cold capacity was provided by using high-pressure nitrogen via the refrigeration circle of turbo expander by adiabatic expansion. Separation of synthesis gas and LNG liquefaction was achieved by using double column cryogenic distillation. When the gas was expanding in the expander, the power was output to drive the supercharger. Compared with the mixed refrigerant process, the liquefaction process with expander has advantages of compact layout, small occupation area, less refrigerant consumption (about 89%), low integrated operation cost, high safety, rapid start, as well as adapting to the varying load conditions from 70% to 110%. It has realized the nationalization of technique and equipment.