Abstract: Waste oil is treated in a tubular reactor having a length of up to and in excess of 2 km in a plurality of stages each of which involves heating the product to a different temperature and maintaining the product at a different pressure. The released fractions are evacuated from the path for the flow of waste oil and are immediately condensed and distilled to yield a variety of products from oil having a low boiling point to coke. One or more withdrawn fractions can be treated (for example, hydrogenated) in one or more discrete tubular reactors. The heating can involve raising the temperature of waste oil to several times the critical cracking temperature, and the regulation of pressure can involve a reduction of pressure to less than 1 mbar. The last stage of the reactor can be cleaned by abrasive particles, by vibration at high frequencies and/or by acceleration of the conveyed stream to an elevated speed.

Abstract: A single-stage or multi-stage centrifugal blower for hot fluids has a rotor whose housing is made of steel or carbon filaments and whose vanes are made of a ceramic material. The internal surface of the housing is shielded from hot fluids by a lining which is made of a heat-resistant and heat-insulating material and which shares the angular movements of the rotor. The housing can stand pronounced tensional and bending stresses, and the vanes and the lining are designed to stand the pressure of the conveyed and/or compressed fluid or fluids. The blower can be used as a turbine, a suction fan or a pump and can convey gases whose temperature is in excess of 1600.degree. C. and whose pressure is in the range or in excess of 2000 mm water column.

Abstract: Carbon electrodes are impregnated with pitch during transport in mobile vessels which first travel to a heating station where the electrodes are heated in several stages by gases which are hotter from stage to stage. The vessels next travels to a station where the sealed vessels are connected with a suction pump to evacuate the fluid from their interiors and from the pores of the electrodes therein and where the vessels are substantially filled with pitch which is caused to penetrate into the empty pores. The vessels then travel to a station where the contents of the vessels are pressurized to ensure complete permeation of electrodes with pitch. The vessels subsequently travel an optional station where the electrodes in the vessels are baked to convert the pitch into coke, and to one or more cooling stations where the electrodes are heated by air, water and/or nitrogen.