3418.     TOWNSEND, D. T. A.  Gasification of Coal.  Gas World, vol. 127, 1947, pp. 79, 406-418; Chem. Age, vol. 57, 1947, pp. 357-360, 399-400.

        Paper presented at the St. Andrews symposium.  An account is given of modern coal gasification developments with special attention to the Lurgi process as being typical of a pressure-operated process.  Gasification uses internal heat normally by burning part of the charge with air or O₂.  In the production of water gas, it is possible to combine the flow and make runs by using steam mixed with O₂ instead of air.  Two main reactions may occur according to the temperature:

        (a)  C+H₂O=CO+H₂-29 cal.

        (b)  C+2 H₂O=CO₂+2 H₂-19 cal.

Reaction (a) occurs at 1,100° and (b) at 600°-700°.  The temperature may be regulated by the rate of steam flow.  Working at a pressure of 20 atm. increases the amount of CH₄, which is formed by a direct hydrogenation of the coal and not by synthesis, and this gives a higher calorific value to the gas; it also enables any CO₂ to be removed by scrubbing with H₂O.  Such treatment gives a uniform gas independent of the type of coal used.  The Lurgi process goes best with lignite coal.  The Lurgi process may be operated to produce synthesis gas for use in the Fischer-Tropsch reaction.