Development And System Evaluation Of New Process Of Gas-assisted Coal To Ethylene Glycol

Facing China’s national conditions of“rich oil and poor coal”,coal-to-ethylene glycol（CtEG）has broad application prospects,which is an effective way to reduce EG dependence on foreign countries.However,carbon-rich and hydrogen-deficient element characteristics of coal lead to prominent problems such as low energy efficiency,high energy consumption and carbon emission.The key is how to integrate hydrogen rich resources with high efficiency,low cost and low carbon emission,so as to realize the efficient complement of carbon and hydrogen elements and optimize techno-economic-environment comprehensive performance.Based on the complementary characteristics of coal,coke oven gas,shale gas and other hydrogen-rich resources,the traditional coal to ethylene glycol（CtEG）process was systematically integrated and optimized.Three new coke oven gas assisted coal to ethylene glycol（CCtEG）process integrating different methane reforming technologies were proposed respectively.They are the CCtEG process integrated with dry reforming technology（D-CCtEG）,integrated with steam reforming technology（S-CCtEG）,and integrated with dry and steam reforming technologies（D+S-CCtEG）.And three similar new shale gas assisted coal to ethylene glycol process,namely D-SCtEG,S-SCtEG and D+S-SCtEG process.Based on the whole process model of coke oven/shale gas assisted coal to ethylene glycol,the techno-economic evaluation of the innovative process was carried out in detail,and the advantages and disadvantages of the new process compared with the traditional process were quantified.The results showed that the CO₂ emission of D-CCtEG,S-CCtEG and D+S-CCtEG decreased from 2.58 t/t-EG to 0.44 t/t-EG,0.69 t/t-EG and0.15t/t-EG,respectively.The carbon utilization efficiency increased from 21.23%to45.67%,44.58%and 57.63%and exergy efficiency increased from 30.68%to 41.27%,34.93%and 45.85%,respectively.It saves about 8.75%,10.54%and 14.88%of production costs and increases and the internal rate of return increase by 3.6%,3.76%and7.2%,respectively.Compared with the conventional CtEG process,the carbon utilization efficiency of D-SCtEG,S-SCtEG and D+S-SCtEG processes increased by 38.24%,37.28%and 38.1%and Exergy efficiency was increased by 17.70%,20.66%and 13.66%,respectively.among which the D-SCTEG and D+S-SCTEG processes could achieve zero emission,and the carbon emission of S-SCTEG process was reduced from 2.58 t/t-EG to 0.57 t/t-EG.In terms of economic performance,because shale gas does not need pretreatment,the total investment of innovative process is reduced by 4.84%,17.73%and 16.18%,the total production cost is increased by 10.48%,13.23%and 9.09%,and internal return of rate also increased from 9.25%to 13.64%,18.65%and 16.43%,respectively.Therefore,the new process of hydrogen-rich resources assisted coal to ethylene glycol has more competitive advantages and is a promising direction of coal chemical industry in the future.