Patent GB-696957-A (GB)
Title: Improvements in or relating to the catalytic treatment of hydrocarbons
IPC: C10G15/00
Filed: 1950-09-08
Abstract: Hydrocarbons are cracked by contacting the feed material with a catalytic solid <PICT:0696957/III/1> <PICT:0696957/III/2> comprising one or more electrically-conductive surfaces heated by an electric current, the wattage per square unit of catalytic surface being adjusted to give the required catalytic activity, and continuously removing the coke deposited on the catalytic surfaces during the process.  The hydrocarbon feed material is preheated, and pumped in the liquid state through line 7, Fig. 1, one-way valve 18, and one or other of branch-lines 9a, 9b into the right- or left-hand portion of horizontal cylinder 20 which is made of an alloy of one or more noble metals (silver or platinum), and is surrounded by a layer of insulating material 44 such as glass-wool.  An electric current is applied to the wall of cylinder 20 from transformer 34, the wattage per square unit of surface being adjusted by slide-switch 38 so as to obtain a greater proportion of light, medium or heavy hydrocarbons, as principal product.  Within the cylinder is housed an insulated piston 23 fixed to a rod 24 which reciprocates in openings 26a, 26b in the walls of two extension-chambers 25a, 25b, one at each end of the cylinder.  The feed-valves 22a, 22b operate alternately: they may be double-seat valves which operate automatically by pressure difference, opening when the piston travels away from them and closing at once when the piston travels towards them.  Alternatively, the valves may be electrically controlled.  The vapours formed by the cracking are discharged through conduit 13a or 13b into fractionating column 14 from which the required product is withdrawn through line 15, while the material withdrawn through line 16 may be recycled. The vapour-conduits 13 are provided with automatic valves 42a, 42b which are alternately opened and closed in accordance with the reciprocal movement of the piston.  Valves 22a and 42b are open while valves 22b and 42a are closed, and vice versa.  The coke deposited on the inner wall of cylinder 20 is scraped off by the piston, and pushed out into one or other of the containers 11a, 11b which are provided with cooling-sleeves 31.  These containers are normally closed by members 29a, 29b which are pressed against either end of the cylinder, disc 30a or 30b pushes the respective member 29 out of its sealing position into the adjacent extension-chamber 25.  The cooled coke is discharged intermittently from containers 11.  The apparatus, although sealed, is preferably maintained at atmospheric pressure.  More than one cylinder may be employed, e.g. three cylinders can be connected to form a Y-system associated with one transformer.  In another embodiment, Fig. 4, the cracking is carried out in a chamber 110 within which is supported a cylinder 120 made of catalytic material, and supplied with electric current from a transformer 134.  The liquid hydrocarbon to be cracked is admitted into chamber 110 until cylinder 120 is completely immersed therein. The coke deposited on cylinder 120 is removed by blades 160 attached to rotary frame 159.  The blades on the upper arm of the frame are in staggered relationship with the blades on the lower arm so that, when the frame rotates, each blade travels over a different path on the surface of cylinder 120.  In an alternative arrangement, cylinder 120 may be rotary and the scraper stationary.  The scraped-off coke is collected in containers 168.  In a further embodiment, two chambers are employed, each being provided with a plurality of electrically-heated tubes or bars of catalytic material passing through apertures in a scraper-plate which slides on rails.