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.

PYROLYSIS OF THE LOWER PARAFFINS: III. PRODUCTION OF OLEFINES IN BAFFLED METAL TUBES

Results have been obtained which indicate that the conversion of the lower paraffins to olefines by thermal treatment can be satisfactorily carried out in special alloy steel tubes at 800–820 °C. By using baffled tubes it has been found possible to obtain high rates of conversion at temperatures considerably lower than when using open tubes. Actually the temperature has been brought within the range of usefulness of special alloy steels. Heat-resistant alloys of the 18–8 type have been found unsuitable for this purpose, because nickel appears to catalyze the formation of elementary carbon, but nickel-free alloys containing over 20% of chromium have been found satisfactory.