Promotion of char oxidation by inorganic constituents

Abstract

A North Dakota lignite has been demineralized and selectively reloaded with calcium, potassium, and sodium cations by an ion-exchange process. Chars produced from the treated samples were burned in a laminar-flow reactor and single-particle temperatures were determined by optical pyrometry. Results show that sodium and potassium cations present in the chars have little effect on the char particle temperatures or burning rates. Calcium cations enhance the char particle temperatures at low concentration (<5000 ppm). The results are consistent with carbon dioxide being produced at the char surface by catalytic action of the char mineral matter.