GB543215A - An improved manufacture of hydrocarbons by catalytic cracking - Google Patents

Abstract

543,215. Cracking, coking and hydrogenating oils. STANDARD OIL DEVELOPMENT CO. Dec. 28, 1939, No. 33007. Convention date, Jan. 28, 1939. [Classes 1 (i) and 32] Reduced or topped crudes are subjected to a mild thermal cracking treatment at about 850‹ F. to reduce the vaporizing temperature of the crude to about 700-800‹ F. and the'vapours obtained boiling below 800‹ F. are subjected to treatment with catalysts at 700-900‹ F. and fractionated to recover (a) gasoline (b) a light gas oil of boiling range 350-500‹ F. (c) a heavy gas oil or boiling range 450-700‹ F. and (d) residues, the heavy gas-oil fraction being recycled to the mild thermal cracking stage. The light gas oil is subjected to catalytic hydrogenation while the heavy residues remaining after vaporizing the fractions boiling below 800‹ F. from products of the mild cracking slag are subjected to coking in the presence of catalytic or contact materials. The crude feed is passed through a coil 12, where it is heated to 700-850‹ F. under a pressure of 700 lbs. per sq. inch, into a vaporizing tower 16 in which vaporization is aided by steam fed through line 17. Vapours pass off through line 22, 23 to reaction chambers 25, 25<SP>1</SP> filled with catalysts, e.g. activated clays, synthetic gels of alumina and silica maintained at 700-800‹ F. while the heavy unvaporized residual products are fed through line 21 and coil 102 to coking chambers 106, 106' where they are reduced to coke in the presence of contact material of a similar catalytic nature. The vapours formed in the catalytic converters pass through lines 108, 61 to a common fractionating tower 62 operated under temperature and pressure conditions such that (a) vapours of gasoline boiling range are recovered through line 71 and condenser 72 to receiver (b) a light gas oil is collected on plate 68 (c) a heavy gas oil is collected on plate 65, while bottoms are withdrawn through line 64 and re-cycled through line 110 to coil 102 or coil 12. The heavy gas oil is re-cycled through line 67 and, with or without further cracking and vaporization in coil 91, is fed (a) through line 93 to mix with the vapours passing off from tower 16 (b) through line 95 into bottom of tower 16 (c) or in part through line 97 into the coking vessels 106. The light gas oil fraction is passed through lines 70, 122 to coil 124, where it is mixed with hydrogen from line 155, and heated to 900- 1,200‹ F. and is then passed to catalytic converters 128, 128<SP>1</SP> filled with hydrogenating catalysts, e.g. sulphides of Group 6. Alternatively the hydrogenation reaction may be carried out at 500-800‹ F. The hydrogenated-aromatized products pass to a high pressure separator 133 where hydrogen is separated and re-cycled, and thence through condenser 137 to fractionating tower 140 from which products of gasoline boiling range are recovered through line 145, and condenser 146 to receiver 147. The gasoline products of the cracking and hydrogenation processes may be mixed in line 153. The converters 25, 106, and 128 are preferably provided in pairs. alternately on stream and undergoing regeneration and are constructed as shown in Fig. 2. An insulated metal shell 26 is provided with grid plates 32-35 supporting beds of catalysts 28-31 separated by vapour spaces 36-40. These vapor spaces are connected by vapor conduits 41, 42, 43, 52, 53, the conduits 44, 45, 46 being normally closed by valve caps 44, 45, 46, which during the regeneration cycle are lifted by stems 47, 49 operated by hydraulic cylinders 48, 51 so that the regenerating gases admitted through line 55 may pass through the catalytic beds in parallel being finally removed through line 54.