Experimental Investigation of the Effects of Inorganic Components on the Supercritical Water Gasification of Semi-Coke

Inorganic components in coal play a significant role during the supercritical water gasification (SCWG) process. This study comprehensively investigated the effect of major mineral components (SiO2, Al2O3, and CaO) on the SCWG of semi-coke with/without K2CO3. The inhibition/promotion mechanism and conversion of mineral chemical components were explored. The results showed that, without K2CO3, CaO promoted gasification because CaO's adsorption of CO2 contributed to the fixed carbon steam reforming reaction and the catalysis of highly dispersed calcite. When K2CO3 was added, SiO2 and CaO were prone to sintering and agglomeration due to the formation of low-melting-point minerals, which hindered further gasification of fine carbon particles. Al2O3 prevented the aggregation of slags, increased the probability of fine carbon particles contacting SCW and K2CO3, and promoted complete gasification. This study's results may provide theoretical guidance for the directional control of minerals in coal during SCWG, and complete gasification of solid-phase carbon can be achieved by properly adjusting the mineral components.