505.    ---------------.  [CHEMICAL AND ENGINEERING NEWS.]  Lignite-Gasification Plant at Grand Forks, N. Dak.  Vol. 23, 1945, pp. 1242-1244.

                  Federal Bureau of Mines commercial-size pilot plant for the gasification of lignite is described, and a flow sheet of the operation is shown.  The process as used is a combination of the Reyerson low-temperature, continuous, isothermal system with the Parry vertical, annular, externally heated retort but over a wider range of temperature.  Part of the water gas produced is formed by the reaction between the fresh lignite and its contained moisture in the upper zone, while the balance comes from the lower zone in which the lignite char reacts with steam passed countercurrently from the bottom of the retort.  The 2 streams of water gas combine and pass out at the top through the center.  The system is designed for an output of 75-80 cu. ft. of water gas per hr. per sq. ft. of heated retort surface.  The unit produces 33,000 cu. ft. of a 300-B.t.u. gas per ton of lignite containing 70-72% of H.  The H₂:CO ratio can be varied from 1.8 to 12. with changes in temperature and concentration of steam.  The highest ratios giving maximum H₂ production are obtained at low temperatures, while at higher temperatures a synthesis gas, which is high in CO and suitable for use in Fischer-Tropsch reactions is obtained.