Development of high temperature filter for molten coal slag removal

This paper proposes an innovative coal combustion/gasification furnace incorporating pebble bed filter for high temperature molten slag removal. The experimental demonstration of this high temperature filter is reported. Molten coal slag particles generated by injecting fly ash of coal into high temperature natural gas fired combustion gas are successfully trapped and extracted from the filter, and 97.7% slag removal efficiency is demonstrated. Alumina pebbles receive significant attack from the reaction with the molten slag under the temperature around 1700 °C, while this attack can be greatly suppressed by lowering the operating temperature of the filter below about 1600 °C. A new coal gasification combined cycle power generation system employing the pebble bed coal gasifier is proposed, whose thermal efficiency is expected to reach as high as about 50%.