Patent GB-510155-A (GB)
Title: Improvements relating to the conversion of mineral oils into gasoline
IPC: C10G57/02
Filed: 1937-11-26
Abstract: 510,155. Cracking hydrocarbon oils. STEVENS, A. H. (Standard Oil Co. (Indiana)). Nov. 26, 1937, No. 32719. [Class 32] [Also in Group IV] To produce a high yield of anti-knock motor fuel of desired volatility, hydrocarbon oils are cracked to produce a gasoline distillate, from which substantially all hydrocarbons with less than 5 carbon atoms per molecule are separated to yield a distillate of lower vapour pressure than commercial gasoline, the separated hydrocarbons are subjected to a polymerization treatment to produce polymer gasoline which is blended with the gasoline distillate of low volatility together with sufficient butane to give a product of the volatility of commercial gasoline. The final product being comparatively free from butanes is able to accommodate a correspondingly greater proportion of butane without exceeding the desired volatility. Cold crude oil is introduced via line 10 and heater coils 11, 13 and 16 into the upper section of tower 12. Gases and light uncracked naphtha are removed at 17a. Unvaporized material passes via line 18 to the middle section 19 of the tower whence vapours pass by line 20 to tank 47, while the still unvaporized residue passes to tower 23, whence gas oil is vaporized and passed to bubble tower 14 while heavy residues of the crude oil are tapped off at tray 26 and passed to the viscosity breaker furnace 30 to be heated to 850-925‹F. at 100-750 lbs./sq. inch pressure, and then passed back to tower 23 below the tray 26. Gas oil condenses in tower 14 and is drawn off at the bottom and passes to gas oil furnace 37 where it is cracked at 900-1050‹ F. and 100-750 lbs./sq. inch pressure. The cracked gas oil, 15-40 per cent. of which is converted to gasoline passes, if desired, to reaction drum 40, and thence to evaporator 23 below the tray 26. Heavy virgin naphtha from section 19 of the flash tower 12 passes from tank 47 to furnace 49 where it is cracked at 950-1100‹F.- and 200-1500 lbs./sq. inch pressure, the products passing to evaporator 23 below the tray 26. All gases and gasoline formed in the cracking process pass with gas oil from evaporator 23 to tower 14. Unvaporized residium or tar withdrawn from the bottom of tower 23 passes to the bottom section 24 of the flash tower 12 whence any gas oil is distilled and passes to the middle section 19, while heavy residual fuel oil is withdrawn through line 53. Cracked gasoline vapours and gas leave tower 14 through line 54 and pass, if desired, to clay towers 56, 57 (Fig. 2) where gum forming constituents are polymerized and returned to the cracking system. The gasoline vapours and gas pass through a cooler 67 to separator 68 from which fixed gases such as hydrogen and methane are removed, while liquid condensates pass to stabilizer 72 for fractionation-most gases of less than 5 carbon atoms per molecule being sent overhead through line 76 and debutanized gasoline of less than commercial volatility being withdrawn as bottom product. The overhead product passes, if desired, to fractionator 78 which separates a gaseous product (mainly ethane and ethylene) from the 3 and 4 carbon atom hydrocarbons which pass, if desired, via dryers 84, 85, to catalytic polymerization chamber 92. Suitable catalysts are of the sodium chloroaluminate type or of the solid phosphoric acid type. The products pass to fractionator 96, oil heavier than gasoline being returned thence to the cracking system while gasoline and lighter products pass to fractionator 103 for separation into gasoline and lighter hydrocarbons which are further separated in fractionator 108 into butane and lighter hydrocarbons which pass to fuel line 114. If desired, butane may pass with gasoline from the bottom of fractionator 103 and fractionator 108 may be omitted. Vapours from the crude flash tower 12 pass via line 17a to fractionators 116 and 119 for separation into light uncracked naphtha and gases for the fuel line. Gases in the fuel line may be burned or cracked to yield more olefines. The cracked gasoline distillate of less than usual volatility is blended with the polymer gasoline and with butane, either contained in the polymer gasoline or separated therefrom to produce a final gasoline product of desired volatility. A modification of the invention, differing only in matters of detail, is also described.