Optimal design, thermodynamic, cost and CO_2 emission analyses of coal-to-methanol process integrated with chemical looping air separation and hydrogen technology

摘要

In China, coal is the main raw material used for methanol production to relieve the domestic supply and demand. The conventional coal-to-methanol (CTM) process suffers from less energy efficiency since high energy consumption of air separation and CO_2 capture. A novel CTM process integrated with chemical looping air separation (CLAS) and chemical looping hydrogen (CLH) is designed and analyzed to reduce energy consumption, CO_2 emission, and improve energy efficiency. The integration of CLAS technology can remove air separation unit and decrease energy consumption to a certain extent. The integration of CLH technology can remove water-gas shift unit and increase the CO_2 concentration and reduce the energy consumption of CO_2 capture. The CLH technology also produces hydrogen used for adjustment of hydrogen to carbon ratio of the syngas. Process modelling results show that the energy consumption of the CLAS and that of the CO_2 capture of the CLH are decreased by 41% and 89%, comparing to those of the conventional air separation and CO_2 capture of the CTM process. In addition, the energy efficiency of the new process is increased by 18% and CO_2 emission reduced by 45% in comparison with the conventional CTM process.