Abstract: Coal to SNG process has such advantages as simple flowsheet and equipment,high reliability and low investment per heating value. A model was developed using process simulation software Aspen Plus for the process producing SNG from coal,and exergy distribution of the process and exergy loss of each unit were calculated based on the exergy analysis method. In the process,the exergy efficiency of the rectisol unit was the highest,98.22%,and that of the gasification unit was the lowest,58.99%. Exergy loss mainly took place in the gasification unit,accounting for 72.69% of the total exergy loss. The internal exergy loss caused by heat transfer and chemical reactions irreversibility was the major loss in the gasification unit. Optimizing gasification temperature and molar ratio of steam to oxygen could be the key to improving exergy efficiency and reducing exergy loss of the process

Key words: coal to SNG, Aspen Plus, process simulation, exergy

摘要： 煤制天然气过程具有设备流程简单、技术成熟可靠、单位热值投资成本低等优点.本文运用Aspen Plus 软件建立煤制天然气流程的过程模型,并采用(火用)分析法对系统主要单元进行计算分析,得出系统的(火用)分布状况及各单元的(火用)损失量.结果表明,低温甲醇洗单元的(火用)效率最高,为98.22%,煤气化单元的(火用)效率最低,为58.99%.同时,系统的(火用)损失也主要发生在煤气化单元,占系统总(火用)损失的72.69%.煤气化单元中主要的(火用)损失是由于传热不可逆和化学反应的不可逆性引起的内部(火用)损失,通过优化气化温度、汽氧摩尔比等方式改善气化炉的气化条件是提高气化(火用)效率、降低系统(火用)损失的关键.

关键词: 煤制天然气, Aspen Plus, 过程模拟, (火用)