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Existence of impurities in the product gas hinders the application of the system which combines gasification with solid oxide fuel cell (SOFC). A new method is proposed to produce qualified syngas, which integrates the gasification unit with the supercritical water unit (SWU). The SWU contains supercritical water mixer, separator, reactor (SWR) and expander. To analyze performance of the proposed process from a systematic perspective, downstream operating units primarily including SOFC, burner, heat recovery steam generation and steam cycle are designed. Model for the whole system is developed by using Aspen Plus and a mathematical model for the SOFC. Sensitivity analysis regarding the fuel utilization factor ( U f ) and the mass ratio of tars to supercritical water (T/W) are conducted in terms of system electrical efficiency, SOFC electrical efficiency and cell voltage. Results show that combustible components in the obtained syngas mainly contain CH 4 , H 2 , and CO. Tars are completely decomposed and only slight amount of light hydrocarbons (except CH 4 ) are present. One SWR can undertake the functions of water gas shift, tar reforming and methane synthesis concurrently. The integrated process can offer a combustible components efficiency of 78.2%, and the system electrical efficiency is predicted to be 46.3%. U f has a significant influence on the SOFC electrical efficiency, while it has slight influence on system electrical efficiency. As the T/W rises from 1.6% to 2%, system electrical efficiency, SOFC electrical efficiency and cell voltage slightly increase. [ABSTRACT FROM AUTHOR]

Advanced technologies such as solid oxide fuel cells generally have a strict requirement on syngas quality especially the concentration of impurities. It is common to sacrifice economy and efficiency to achieve a qualified syngas by applying several cleaning and conditioning steps. The objective of this work is to propose a combined process by integrating the gasification unit with the supercritical water unit (SWU) to provide qualified syngas. The SWU includes supercritical water mixer, separator, supercritical water reactor (SWR) and expander. Detailed operating methods and appropriate equipment are presented. The whole process is modeled by using Aspen Plus to investigate effects of SWR inlet temperature, operating pressure, and mass ratio of tars to supercritical water (T/W) on the final product composition and on the outlet temperature of SWR. Results show that higher SWR inlet temperature facilitates achieving a higher H 2 and CO yield while lower inlet temperature assists in obtaining a higher H 2 /CO ratio. Lower SWR operating pressure benefits to achieve a higher H 2 and CO yield and a higher H 2 /CO ratio. Lower T/W benefits to have a higher H 2 yield and a lower CO yield, leading to a higher H 2 /CO. Tars could be completely decomposed at the given operating conditions in the proposed process. Higher inlet temperature, higher pressure and larger T/W lead to an increased SWR outlet temperature. Combustible components in the syngas mainly contains H 2 , CO, and CH 4 . [ABSTRACT FROM AUTHOR]