煤制天然气过程变换单元建模与能量集成

Modeling and heat integration for water gas shift unit of coal to SNG process

我国煤制天然气项目经过国家"十二五"时期进一步升级示范,工艺上取得了突破性进展。然而煤制天然气项目面临集成度不高,整体能耗较大的问题。高效回收利用变换单元放出的反应热是降低煤制天然气项目能耗的一条有效途径。本文首先建立了基于反应动力学的固定床反应器模型,在满足变换反应调整氢碳比要求下,通过对反应操作参数的优化,提高了系统?输出。在对优化后变换单元过程能量分析的基础上,建立了新的变换单元热回收网络。实现了过程反应参数优化和换热网络的集成优化。新工艺的能效比现行工艺提高9个百分点,达到86.3%,投资增加了5.5%,投资回收期为2.1年。

Technologies of coal to synthetic natural gas（SNG）project have made a breakthrough after further upgrade demonstration in the 12 th Five-Year period of China. However,SNG projects suffer from relatively low degree of integration and high energy consumption. High-efficiency recovery and utilization of the reaction heat of the water gas shift（WGS）unit are efficient ways to reduce energy consumption. A fixed-bed reactor model based on reaction kinetics was established. Under the condition of meeting requirement of H2/CO ratio,system exergy output was improved by optimizing the reaction operating parameters. A new heat-recovery network was established based on the energy analysis of the optimized process. Optimization of reaction parameters and integrated optimization of heat exchanger networks were realized. In comparison to the present technology,the energy efficiency of the new process increased by 9%,reaching 86.3%. Investment enhanced by 5.5% and the payback period was 2.1 years.