Gasification method

a system of synthesis gas manufacture including a gasifier wherein fluidized char is reacted with steam using a particulate heat exchange material to sustain the endothermic steam-carbon reaction to produce a synthesis gas stream which on cooling gives water contaminated with H.sub.2 S and NH.sub.3 and a carbonizer wherein fluidized coal is carbonized below about 700.degree.C to provide said char and vapors which on cooling give oil and water contaminated with H.sub.2 S, NH.sub.3 and organic materials, the improvement which comprises heating solid heat transfer material to a temperature above 500.degree.C, then, after said heating, feeding a stream of said contaminated waters into contact with said preheated heat transfer solid to form superheated steam, feeding said superheated steam to said gasification zone, repeatedly reheating said solid after said contact with said contaminated waters and repeatedly recycling the reheated solid into such contact with additional quantities of said contaminated waters, said solid being substantially inert in said process.