Experimental investigation on the supercritical water gasification of coal by integrating the hydrogen oxidation process into a supercritical water fluidized bed

Abstract

The autothermal gasification process is crucial for the industrial application of supercritical water gasification (SCWG) in a supercritical water (SCW) fluidized bed. However, researchers often consider providing external heat to investigate the gasification process and seldom achieve autothermal gasification. Herein, the hydrogen oxidation process was integrated into an SCW fluidized bed to provide heat for the gasification process and to investigate gasification results under various experimental conditions. Using this method, a carbon gasification efficiency of 98.6% and a H2 yield of 68.03 mol/kg were obtained at an experimental temperature of 690 °C. After the gasification products were partially oxidized in the oxidation zone, a H2 yield of 13.6 mol/kg and a total carbon content of <10 ppm in the liquid products were obtained. Compared with the uniform electrical heating method, the heating method based on the hydrogen oxidation process in SCW has obvious advantages, can improve the coal slurry concentration and mass ratio of coal to SCW in the reactor, and maintain a milder temperature under near-complete gasification conditions. This work provides a basis for heat supply in the industrial application of SCWG technology.