Advanced exergy analysis and optimization of a coal to ethylene glycol (CtEG) process

Abstract

Coal to ethylene glycol (CtEG) process is criticized for its high energy consumption and poor thermodynamic performance. This process is detailed modeled by dividing it into coal gasification, water gas shift, acid gas removal, dimethyl oxalate synthesis, ethylene glycol synthesis, and ethylene glycol refining units. After comparing and verifying with literature and industrial data, this work conducts a detailed advanced exergy analysis and optimization of the CtEG process. Results show that the exergy efficiency of the CtEG process is only 33.56%, and the coal gasification, dimethyl oxalate synthesis, and ethylene glycol synthesis units have the largest exergy destruction. Furthermore, the exergy destruction of all components in the CtEG process is dominantly endogenous (76.03%) and avoidable (64.62%). The real improvement potential of the CtEG process is 64.62%. A parametric study was then performed to investigate the effect of key parameters on the thermodynamic performance of the CtEG process to reduce its avoidable endogenous and exogenous exergy destruction. After optimization, the exergy efficiency of the improved CtEG process is increased by 12.34%, and the avoidable exergy destruction is reduced by 160.48 MW compared with the reference system. Therefore, the improved CtEG process has better thermodynamic performance than the reference process.