Conceptual Design and Techno-economic Analysis of a Coal to Methanol and Ethylene Glycol Cogeneration Process with Low Carbon Emission and High Efficiency

Coal gasification and coking to methanol (GCtM) is a newly developed and industrialized process in China. However, in the early stages, the idea of integration hardly applied to this process. To improve the degree of integration, this paper developed a coupling process of coproducing methanol and ethylene glycol. The key idea was to find an appropriate distribution of carbon and hydrogen components for maximal resource utilization. The new process introduced additional hydrogen and carbon sinks by adding a new ethylene glycol synthesis unit. It separated excessive H-2 or CO from different syngas streams depending on their composition. This brought more hydrogen and carbon sources. The new process conducted integration by matching sinks and sources. A detailed process modeling and simulation were conducted in Aspen Plus. The simulation results were verified with reference and industrial data. The techno-economic performance was analyzed and compared with the conventional process to find the advantages of the new process. The results showed that the new process had a much higher carbon utilization efficiency of 54% than that of the GCtM process, 40%. The total greenhouse gas emissions of the new process are 1.58 t CO2 equiv t(-1), which is 26.2% lower than that of the GCtM. It was also found that the exergy efficiency was improved from 56.7% to 68.1%. As for economic benefits, the new process decreased total product cost by 35.2% and increased internal rate of return by 4.5%.