Patent GB-502799-A (GB)
Title: Improvements in the production of motor fuel by vapourizing and cracking hydrocarbon materials
Filed: 1937-09-20
Abstract: 502,799. Cracking oils. OCON, E. A. Sept. 20, 1937, No. 25520. [Class 32] In a multi-stage cracking process, the preheated uncracked charging stock is flashed in a primary fractionating tower with the aid of highly heated cracked products passed into the tower, the products are segregated into gasoline-naphtha fractions, gas oil, and unvaporized liquid residues, the latter are cracked mildly in a primary cracking zone and passed into a blending zone where they are mixed with the gas oil and hot products from a second cracking zone introduced with great velocity, the products from the blending zone are passed into a separating tower in countercurrent to a flow of liquid hydrocarbon, and the uncondensed vapours are fractionated to give gasoline and a composite condensate which is cracked in the second cracking zone. Crude oil is passed through heat exchangers 2, 3 into a fractionating tower 4 in which gasoline, fractions are vaporized with the aid of hot cracked vapours supplied through a line 7 and are led off through a line 16 and condenser 17 to a receiver 14 from which a portion may be recycled as reflux through a line 13. The fractionation may be combined with purification by feeding sulphur absorbent material, e.g. lime or silicious material mixed with phosphoric acid, triethanolamine, ethylenediamine, sodium plumbite, lead acetate, &c. mixed with alcohols, ether, and like solvents from a tank 24 into the tower 4. Virgin gas oil stock is collected on a pan 4x and led through a line 18 into a blending chamber 20 where it is mixed with the products formed by cracking the heavy bottoms collected at the bottom of the tower 4 at 800-900‹ F., in coils 9, 23 of a cracking furnace 10 a portion of the cracked products being bled off through the line 7 and returned to the tower 4 to provide heat for evaporating the crude stock. The mixed contents of the blending chamber 20 pass onto a pan 30x of a separation tower 30 the heavy fuel oil and tarry fraction over, flowing the pan and passing to the bottomof the tower from which they are removed to storage, while the vapours formed pass through a line 41 into a tower 29. In this tower fractionating conditions are regulated so that a gasoline fraction of desired end point is taken off through a line 49 to condenser 48 and receiver 46, while a gas oil fraction is collected at the bottom of the tower and is passed through lines 26, 27 into cracking coils 9 heated to 1000-1100‹ F., the cracked products passing into the blending chamber 20. Part of the products from the coils 9 may also be byepassed to the tower 4 through the line 7. The tower 30 is provided with catalytic material 40 and fractionating &c. conditions therein are controlled (1) by passage of virgin gasoil stock through lines 18 19x, (2) by introduction of heavy bottoms from tower 4 through lines 21, 31, (3) by recycling heavy residues withdrawn through a perforated pipe 38 through line 35, (4) by introduction of a mixture of steam and ammonia through line 32. Steam and ammonia may also be introduced through lines 42 and 5 into the towers 29, 4. U.S.A. Specification 2,052,721 is referred to.