Adopting coal to synthesize ethylene glycol can not only rationally utilize China’s coal resources,but also increase the self-sufficiency rate of ethylene glycol(EG)and protect the EG industry with healthy and sustainable development.However,the traditional coal to ethylene glycol(CtEG)process is criticized by high energy consumption,low thermodynamic efficiency and poor economic benefits.Therefore,in-depth analysis of the root cause of low efficiency in CtEG process is of constructive significance for improving thermodynamic performance of the system and promoting efficient development of the CtEG industry.In this study,the technology and research status of CtEG process were firstly summarized and analyzed.For typical CtEG process,the basic model of the whole process was established by employing Aspen Plus software.Through simulation,the detailed mass and energy balance equation of the whole process were obtained.By comparing with industrial data,the reliability and accuracy of the simulation results were verified.The influence of key operating parameters on the system performance was investigated by comprehensive analysis.Thus,the rational optimization was proposed according to the research results,which provided a theoretical basis for the subsequent thermodynamic analysis of the system.What’s more,aiming at the shortcomings of traditional thermodynamic analysis methods,this paper proposed an advanced exergy analysis method and optimization framework based on CtEG system.According to the simulation results,the thermodynamic analysis model was established to deeply analyse the energy flow and effectively excavate the energy bottleneck of each unit and system,then put forward the optimization measures.Lastly,contrapose the coal gasification unit with the largest exergy destruction of the whole process,this paper proposes an economic analysis framework based on the CtEG system.Then this article comprehensive analyzed the effects of three different coal gasification plant of the system on technical parameters,thermodynamic and techno-economic performance.The simulation results shows that about 36.94 t/h of EG product can be produced from120 t/h coal.In addition,the operating temperature range of the gasifier is preliminarily determined to be 1300℃~1500℃,and the feed ratio of oxygen to coal is suggested to be0.56~0.65 t/t.The optimized space velocity of DMO synthesis reaction is 3500 h-1,and the mass ratio between CO and MN is 0.93 kg/kg.The recommended reaction pressure and catalyst height of EG synthesis process are 2.5 MPa and 4.2 m,respectively.In addition,the diameter of reaction tube is suggested to be 27 mm.Thermodynamic analysis results shows that conventional exergy analysis method can only diagnose the exergy destruction of CtEG system as 395.04 MW,the total exergy efficiency of CtEG was 33.56%,and the largest exergy destruction of coal gasification unit,accounting for 50.54%.Advanced exergy analysis method was employed to reveal the real potential for performance enhancement of each component by dividing the exergy destruction into endogenous/exogenous and unavoidable/avoidable parts.The result shows that most of exergy destruction of the CtEG process is caused by the internal irreversibility of the system components,and the avoidable part accounts for 64.62%of the total exergy destruction.Moreover,according to improvement strategies,avoidable exergy destruction of the whole CtEG process is decreased from 255.27 MW to 94.79MW,and the exergy efficiency is increased by 12.34%.What’s more,the coal gasification unit with the largest exergy destruction of the whole process was further studied.Based on the process simulation result and the study of thermodynamic performance,the effects of different gasification technologies on the system performance of the whole CtEG process was investigated.In terms of process parameters,the results show that case GSP has the highest carbon and cold gas efficiencies,while case Texaco has the lowest CO2 emission of 2.89 t/t-EG.The CtEG process with GSP gasification technology has the best thermodynamic performance,and the exergy efficiency of the system is 43.98%.With reference to techno-economic performance,case Shell has the highest capital cost(18152 CNY/t-EG),and case Texaco has the highest total production cost(4483 CNY/t-EG),furthermore,case GSP has the highest internal rate of return(18.01%).Comprehensive analysis shows that adopting GSP gasifier for CtEG process has the highest exergy efficiency and economic benefits. |