Energy Balance of a Staged Process for the Supercritical Water Gasification of a Hydrogen Fermentation Residue of Food Waste

Abstract

This study was conducted to calculate the energy balance of supercritical water gasification with an activated carbon catalyst for a hydrogen fermentation residue of soybean fiber (SFHFR). To circumvent the problem of plugging, we examined the gasification of SFHFR by a staged operation with alternate feeding of water and feedstock. The calculations were applied to a gasification reaction conducted within a tubular reactor at 600°C and 25 MPa, with an average residence time of 73 s. The calculation results were a cold gas efficiency η r [(amount of energy recovery from feedstock as product gas, Eg) / (energy supply from feedstock, E f)] of 0.72 and an energy efficiency η, Eg / [(heat supplied by the electric furnace, E i) + (energy supply from feedstock, Ef)] of 0.30. A comparison between continuous operation and the operation in staged intervals confirmed the effectiveness of the latter.