Pathway of biomass-potassium migration in co-gasification of coal and biomass

Abstract

The migration pathway of potassium in biomass during coal/biomass co-gasification was studied both qualitatively and quantitatively. A reactor was employed to individually perform pyrolysis and gasification of two raw materials and their blends. An inductively coupled plasma mass spectrometry accurately measured the amount and occurrence of potassium in biomass migration. Results showed that about 58.6 wt% potassium in biomass existed in the water-soluble form. When the blends were pyrolyzed at above 500 °C, about 65.0 wt% potassium in biomass migrated to the coal char, 19.1 wt% potassium in biomass remained in the biomass char and 15.9 wt% potassium in gas phase. The migrated potassium salt in coal char still existed as a 75.4 wt% insoluble sulfate. Reaction temperature and the ratio of Al to Si from the minerals in coal are key issues for the redistribution of potassium in biomass. The water-soluble potassium in biomass helps to catalytic co-gasification.