System design and analysis of a direct hydrogen from coal system with CO{sub 2} capture

• Published in: Energy & fuels 2007-06, Vol.21 (3)
• Main Authors: Xiang Xu, Yunhan Xiao, Chunzhen Qiao
• Format: Article
• Language: English
• Subjects: 01 COAL, LIGNITE, AND PEAT; 08 HYDROGEN; ADSORPTION; CAPTURE; CARBON DIOXIDE; COAL GASIFICATION; COMPUTERIZED SIMULATION; FLUIDIZED BED REACTORS; HYDROGEN PRODUCTION; SOLID OXIDE FUEL CELLS
• ISSN: 0887-0624; 1520-5029

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 CO{sub 2} 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 CO{sub 2} (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 CO{sub 2} 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. 25 refs., 6 figs., 4 tabs.