Abstract: A slagging gasifier has a hearth comprising an annular solid cast structure formed from a high thermal conductivity metal such as copper and shaped to fit above a slag tap of the gasifier. The hearth is provided with one or more integrally formed passageways for circulating a coolant liquid therethrough and has an upper tundish surface with a slope of at least 10.degree. to the horizontal (preferably between 25.degree. and 45.degree.), across which tundish surface the molten slag flows downwardly and inwardly towards to slag tap. The annular structure may be formed from at least three sector-shaped cast parts secured together in situ in the gasifier.

Abstract: A method of operating a gasifier having at least four, and preferably eight, tuyeres, so as to bring about a rapid turndown from full operational loading to a relatively lower operational loading without the risk of either a temporary or permanent loss of a tuyere. The gasifying medium is arranged to be supplied to the tuyeres at either a first velocity and loading or a second, lower, velocity and loading and in carrying out the method the gasifying medium supplied to some or all of the tuyeres is changed abruptly from the first to the second velocity and loading at selected frequent intervals, in a predetermined pattern, so that a selective pulsing operation of the tuyeres occurs to bring about the required reduction in loading.

Abstract: An easily removable unit connecting a pressurized gasifier vessel with a slag quenching chamber, wherein the unit consists of a flanged cylindrical tube arranged to carry the slag tap, burner and all services, supplies, electrical cables to and from the gasifier.