Coal gasification apparatus, coal gasification method and integrated coal gasification combined cycle power generating system

摘要

A coal gasification apparatus is constructed such that a gasification furnace and a heat recovery unit for recovering heat obtained by a coal gasifying reaction in the coal gasification furnace without imposing load on subsequent equipment are integrally provided in a single vessel. The heat recovery unit is provided immediately above the gasification furnace and composed of heating tubes extending perpendicularly to a generated gas flow, and the gasification furnace is composed of a lower furnace portion and an upper furnace portion. An upper stage nozzle is disposed in the upper furnace portion and a lower stage nozzle is disposed in the lower furnace portion. The lower furnace portion supplies coal and a large amount of oxidizer via the lower stage nozzle to provide a temperature sufficient to melt an ash content, and the upper furnace portion supplies coal and a small amount of oxidizer via the upper stage nozzle to provide a temperature insufficient to melt the ash content, whereby the deposition of the ash content on furnace walls and the heat recovery unit is prevented. Also, the heating tubes, which constitute the heat recovery unit, are composed of two stages, which are different in surface temperature from each other, whereby the generated gas can be efficiently decreased in temperature to ease influences on constituent materials of the subsequent equipment.