GB267958A - Improvements in cracking hydrocarbon oils or their distillates by distillation underpressure - Google Patents

Abstract

267,958. Stransky, S., and Hansgirg, F. March 18, 1926, [Convention date]. Hydrocarbons, cracking.-In cracking hydrocarbons by heating under pressure, the heating is effected by electric resistances having large heating surfaces distributed throughout the liquid space of the still, which is also provided with an agitator. This enables the light hydrocarbons formed by the decomposition to be rapidly vaporized and removed. The temperature and pressure in the still may be controlled automatically; for example, by pyrometers regulating varying resistances or operating switches, &c. The hydrocarbons to be cracked may be passed in series through two or more stills. The relation between the gas space and the liquid space of the still which produces the highest yield of low-boiling products is formed experimentally and is maintained approximately constant. Oil to be treated is forced by a pump 24 through heat-exchangers: 18, 23 into a still 1 containing electric-resistance heaters 2 of large surface and fitted with an agitator 26. The vapours pass through a dephlegmator 13, filled with Raschig rings, and an outlet valve 15 controlled by a pyrometer 17 to maintain a definite temperature, to a condenser 18. The electric supply to the heaters 2 is controlled either by a pressure gauge 6 or a pyrometer, which operates a potential-adjusting device 4 in connection with a transformer 3. A definite level is maintained in the still 1 by means of a condenser formed of concentric tubes 10, 11 dipping into the oil. Variations in the level of oil cause variations in the dielectric constant of the condenser and these are utilized to vary the opening of a valve for the residual oil. The residual oil is discharged into an expansion chamber 21, the vapours from which pass to a condenser 22, and the unvaporized oil to the heat-exchanger 23.