Integration And Green Degree Analysis Of The CO₂ Conversion To Carbonate Process

Because CO2 can be seen as a non-toxic,renewable and abundant carbon source and the CO2 conversion process has the potential to mitigate CO2 emissions,the CO2 capture and utilization(CCU)technology has been paid more and more attention.The Aspen Plus software was employed to establish a rigorous process simulation model for the conversion of CO2 to carbonate process in this work,the carbonylation process and the transesterification process are included,which contains the accurate prediction of the physical properties of the azeotrope involved in the system and modeling of sub-systems,such as CO2 conversion,reactive distillation,and pressure-swing distillation processes.The optimization of key equipment in the system was carried out and energy system was optimized through process integration.Based on the process simulation results,a comprehensive evaluation of the material-energy-environment was carried out.According to the calculation results of the system carbon flow analysis,the utilization efficiency of carbon elements in the system process streams reaches 98.54%,achieving the efficient utilization of carbon element.The negative CO2 emission is 0.16 ton CO2 / ton product(DMC+EG),which indicates that the CO2 conversion process has a positive effect on CO2 emission reduction.According to the result of green degree analysis,the system green degree value is 169.66 gd/h,which can be evaluated as an environmentally friendly process.Based on the conversion of CO2 to ethylene carbonate process,and the selective absorption of ethylene carbonate for ethylene oxide,the process of separation and purification process of ethylene oxide using ethylene carbonate as an absorbent was established.Combined with the existing ethylene oxide production process and CO2 conversion process,the process using ethylene oxide mixed gas as a raw material to synthesis ethylene carbonate was established,so-called one step absorption and conversion process.Compared with the existing synthesis route,the ethylene oxide utilization efficiency of the one step absorption and conversion process is increased by4.69%,the investment cost of equipment is reduced by 18.19%,and the energy consumption achieves nearly zero.