Patent ID: 8252074

Claim:
A method of operating a gasifier, the method including: mixing coarse particulate coal with an average particle size of at least 1 mm and an ash fusion temperature increasing agent to form a mixture and feeding said mixture into a gasification chamber of the gasifier to form a coal bed with a raised ash fusion temperature; feeding oxygen and steam into the gasification chamber; gasifying the coarse particulate coal in the gasification chamber to produce synthesis gas as well as ash and collecting the ash in an ash bed below the coal; and removing the synthesis gas and the ash from the gasification chamber; wherein the ash fusion temperature increasing agent is kaolinite (Al 2 Si 2 O 5 (OH) 4 ), alumina Al 2 O 3 ), silica (SiO 2 ), or titania (TiO 2 ); wherein the gasifier is a fixed bed dry bottom gasifier.