煤制合成天然气过程能量转换分析

摘要

Based on exergy analysis method,for an actual process of coal to SNG with an annual scale of 1.4 × 109 m3,the distribution of exergy loss in each unit and in the whole process were investigated.The results show that general exergy efficiency of gasification unit is the lowest,84.75％,and that of rectisol unit is the highest,98.90％.The prime exergy loss occurrs in gasification unit,reaching to 77.78％ of total exergy loss.The exergy losses in shift unit,rectisol unit and methanation unit are 5.49％,4.04％ and 12.68％ of total exergy loss,respectively.In gasification unit,increasing byproduct steam pressure could not impact exergy efficiency effectively,it is more important to optimize the operating condition of gasifier and scrubber cooler.In methanation unit,higher byproduct steam pressure could improve exergy efficiency obviously and increase steam yield.%基于(火用)分析法及黑箱模型理论,针对规模为14亿m3/a的煤制合成天然气的工艺设计,对其主要工段进行计算分析,得出不同工段及整个工艺的焖损失状况.结果表明:气化工段的普遍(火用)效率最低,甲醇洗工段的普遍(火用)效率最高,分别为84.75％和98.90％,系统的(火用)损失主要发生在气化工段,占整个工艺(火用)损失的77.78％;变换、甲醇洗和甲烷化工段分别占整个工艺(火用)损失的5.49％,4.04％和12.68％;在气化工段,增加副产蒸汽压力对于提高焖效率效果并不明显,提高(火用)效率应着重改善气化炉和洗涤冷却器的操作条件;对于甲烷化工段,增加副产蒸汽压力能明显提高(火用)效率,同时也能增大副产蒸汽量.