System design and analysis of a direct hydrogen from coal system with CO2 capture

Hydrogen is regarded as one of the main energy carriers of the future. On the basis of the previous work, a direct hydrogen production from coal based on a CO2 sorbent enhanced gasification process was constructed in this paper using the ASPEN PLUS simulator. The system is mainly composed of two paralleled fluidized bed reactors, namely a gasifier and regenerator. Then, on the basis of the proposed system, more than 95% hydrogen and less than 5% methane, CO, and CO2 (mole percent, dry basis) of gas product is computationally obtained in a wide range of operating conditions. The cold gas efficiency of the system can reach as high as 92.6%. When a hydrogen and power coproduction system is considered, in which hydrogen is used as the fuel of the solid oxide fuel cell combined cycle (SOFC-CC) hybrid system, the system equivalent power efficiency can reach 61.9% considering the CO2 capture and disposal. Finally, the influences of several key parameters on the system performance, such as operating condition of the gasifier, steam/carbon ratio, Ca/C ratio, and carbon conversion ratio, are investigated.