焦炉煤气制甲醇工艺中循环气量的优化

Optimization of recycle gas flow in coke oven gas to methanol process

针对某年产20万t焦炉煤气制甲醇装置,采用一种结合了计算机模拟和压缩机性能分析的新方法优化甲醇合成单元循环气量,以提高经济效益。利用Aspen Plus软件模拟分析了循环量对系统性能、甲醇产量以及各设备能耗的影响,发现其在计算循环压缩机功耗时忽略了循环量的改变对压缩机性能曲线的影响,导致功耗计算不准确。因此,结合压缩机性能分析方法分析了循环量对压缩机压比曲线、轴功率曲线的影响并校正了不同循环量下的功耗。以不更换压缩机为前提,综合考虑能耗和产量,以最大化新增经济收入为目标优化循环量。结果表明,随着循环量的增加,压缩机压比曲线和轴功率曲线均下移,校正的压缩机功耗呈上凸型曲线增长;循环量为390 000 m^3/h时,能新增经济收入365万元/a。

A novel method combining computer simulation and compressor performance analysis is employed to optimize the recycle gas flow in methanol synthesis unit of a 200,000 t/a coke oven gas to methanol facility,in order to improve its economic efficiency.The impacts of the recycle gas flow on the system performance,methanol yield and energy consumption of all equipment are simulated and analyzed by using Aspen Plus. It is found that the effect of changes of recycle gas flow on the compressor performance curve has been neglected in calculating the power consumption of circulating compressor,leading to the inaccurate calculation results. Thus,the effect of the recycle gas flow on pressure ratio curve and shaft power curve of compressor is analyzed by combining compressor performance analysis. The power consumption values under different recycle gas flow are corrected. On the premise of not replacing the compressor,the recycle gas flow is optimized with the target of maximizing the incremental economic income through considering the energy consumption and production.The results show that with the increase of recycle gas flow,the pressure ratio curve and shaft power curve of compressor both move down and the corrected power consumption of compressor increases as a convex curve.The optimized recycle gas flow is 390 000 m3·h（-1）,generating incremental income of RMB 3. 65 million per year.