3388.     --------------.  [THAU, A.]  [Large-Scale Water-Gas Production for Chemical Synthesis.]  Oel u. Kohle, vol. 38, 1942, pp. 589-601, 617-624, 685-690, 721-727, 749-765; Gas Times, vol. 44, 1945, p. 32; Gas Abs., Inst. Gas Technol., vol. 1, No. 7, 1945, p. 12.

        For the manufacture of NH₃, a synthesis gas containing H₂ and N₂ in the ratio 3:1 is required, while, for the production of MeOH and liquid fuels, a gas consisting of H₂ and CO in the ratio 2:1 is required.  The production of synthesis gas of such required compositions has been achieved in Germany by 5 distinct systems of gasification processes.  The method of supplying the required heat for the endothermic decomposition of steam by C has been chosen by the author as the basis of classification.  (1) In the 1^st class belong the gas generators, employing coke or brown coal as fuel, which operate with intermittent blast and make cycles, such as those built by the Bamag and Viag concerns.  The Viag generators, however, combine this method of heating with the principle of recirculation.  (2) The 2d group comprises those processes that employ O₂ for the internal supply of heat, which makes the operation continuous.  The Winkler, Lurgi, and Thyssen-Galocsy processes belong in this class.  (3) Among the process using indirect heat transfer by recycling part of the produced gases that had been preheated to the required high temperature in intermittently operated regenerators, belong the Pintsch-Hillebrand, Koppers, and Wintershall-Schmalfeldt processes.  (4) A group employing direct heat transfer by external heating comprises the Bubiag-Didier, Reiche Zeche, and Ahrens processes, although in the latter the principle of heat transfer by recirculation is combined with external heating.  (5) The last class includes all other methods of heat transfer employed, such as heating of the reaction chamber by means of electricity as in the Hole and Stassano processes, the use of highly superheated steam in the Pattenhausen process, the use of molten salt bath proposed by Lichtenberger and Halser.  The gas produced by some of these methods needs further processing with steam, either to convert the excess CO into H₂, CO+H₂O→H₂+CO₂, or to decompose the CH₄ into CO and H₂, as is done in the Wild, Gesent, Bamag, and Viag processes by means of a catalyst employed, which also removes the organic S compounds.  In the Kuhlman, Linde, and Padovani processes, the same end is achieved by hot surfaces.  For the removal of the excess CO₂ the alkazid process, pressure washing with water, or other processes have been used.

        THENARD, A.  See abs. 3389.