1919. ------. [KOPPERS, H.] (Koppers Co.). Continuous Production of Water Gas. United States Patent 2,148,299, Feb. 21, 1939. Chem. Abs., vol. 33, 1939, p. 4002.

Described apparatus and a method of continuously producing water gas of a predetermined definite composition with respect to its ratio of H₂, CO₂, and CO and free of hydrocarbons, from distillable solid fuels, which comprises maintaining in a bed of continuously descending fuel a water gas reaction zone in which the distillation of the fuel is already completed and a pre-distillation zone. The hydrogen-free water gas is withdrawn from the zone of the fuel bed in which pre-distillation of the fuel is already completed. A pre-heated gaseous heat carrier medium of water gas and steam traverse the distillation zone, and the medium is circulated from the distillation zone together with the hydrocarbons through a separate gas heating stage and back to the fuel bed through the water gas reaction zone. Steam is added to the heat carrier medium for the water gas reaction in the fuel bed and for converting the hydrocarbons in the heat carrier medium into CO and H₂ in the heating stage. The improvement comprises cooling the heat-carrier medium, after it issues from the heating stage, but before it enters the water-gas-reaction stage fuel bed down to at least the upper limit of the temperature range critical for producing a gas of predetermined definite composition uniformly with respect to its ratio of H₂+CO+CO₂ from the particular fuel being gasified by the heat-carrier medium in the fuel bed.