Highly efficient carbon utilization of coal-to-methanol process integrated with chemical looping hydrogen and air separation technology: process modeling and parameter optimization

Abstract Methanol is an important feedstock of chemical engineering and energy source, and it is mainly produced by coal route in China. The coal-to-methanol suffers from serious CO2 emissions and carbon resource waste since water gas shift is involved in this process to increase hydrogen content of syngas for meeting methanol synthesis. A novel coal-to-methanol process integrated with coke-oven gas chemical looping hydrogen and chemical looping air separation is designed and analysed to improve carbon utilization efficiency, methanol production, and reduce CO2 emissions. The major advantage of the novel process is that the integration between coal gasification and chemical looping technology can remove the water gas shift unit and reduce fuel consumption. To produce one tonne methanol, the coal consumption is 1.45 tonne for the coal-to-methanol, while the coal consumption for the novel process is reduced to 0.75 tonne at the cost of additional 0.35 tonne coke-oven gas under optimized operating conditions. By parameter optimization and process integration, the carbon utilization of the novel process is increased from 38.4% to 56.1% and the CO2 generation of the novel process is therefore reduced from 1.47 to 0.71 kmol/kmol methanol. The novel process also possesses relatively large prospect in terms of economic performance.