In plant for hydrogenating coal to form hydrocarbons, wherein coal in powder or piece form is fed from a hopper into a preparation chamber, is compressed, conveyed and heated by a rotor comprising a rotating friction element and passed, through a feed aperture, into a hydrogenation chamber wherein hydrogen...http://www.google.de/patents/US4344835?utm_source=gb-gplus-sharePatent US4344835 - Method for monitoring and controlling hydrogenation pressure in plant for the hydrogenation of coal with hydrogen to form hydrocarbons
