A fixed bed coal gasifier (300) includes a coal gasification chamber with a coal lock above the chamber. A static coal distribution device inside the gasification chamber includes a hollow coal distributor which flares downwardly outwardly with a skirt depending downwardly from an inside of the coal distributor so that a gas collection zone is defined between the skirt and the coal distributor. The gasifier (300) has an ash discharge outlet (606) and a rotatable grate (600) above the outlet (606). The rotatable grate (600) includes at least one upwardly projecting finger or disturbing formation (500) to disturb the ash bed formed in use above and around the grate (600).