High-Pressure Plant for Experimental Hydrogenation Processes

The paper gives an account of some of the mechanical difficulties experienced in the development and operation of experimental plant for the hydrogenation of coal and tar for the production of motor spirit. Particulars of the various stages of progress are given, from small autoclaves up to a continuous plant capable of producing up to 300 gallons of spirit per day. The pressure plant is operated at 3,000 to 6,000 lb. per sq. in., and at temperatures up to 950 deg. F. Hydrogen produces complete disintegration of the structure of mild steel under the higher temperature conditions. The use of special alloy steels reduces the liability to hydrogen attack, giving longer working life and allowing higher working pressures, but satisfactory service can best be obtained by insulating the pressure-resisting walls from the heating medium so as to avoid heating the metal beyond 200 deg. F. Various methods of making suitable joints for high-pressure pipes and cylinders are described, and the results of microscopic examination of sections of cylinders are given in Appendixes.