GB517269A - Improvements in manufacture of gasoline and fuel oil by cracking crude petroleum stock - Google Patents

Abstract

517,269. Cracking oils. SINCLAIR REFINING CO. May 17, 1938, No. 14727. Convention date, June 15, 1937. [Class 32] In the heat-treatment of asphaltic petroleum stock containing wax fractions to obtain gasoline and fuel oils a distillate produced in the process is cracked at high temperature and pressure and the products passed into direct contact with the crude stock in order to vapourize therefrom gasoline and gas oil fractions, and the liquid residue is flashed at pressures below atmospheric to vaporize the wax containing fraction which is then condensed and used as the cracking stock. The distillate oil is forced at 660-800 lb. pressure and at 900‹F. by a pump 7 through cracking coils 1 into a vaporizer 2 where it is mixed with crude stock fed by a pump 8 through preheaters 32, 40 and line 22. The vapours formed pass through line 23 to a fractionating tower 4 while the residual oil is flashed in a tower 3 the pressure being reduced from 20-60 lb. per square inch in the tower 2 to a pressure of 10-25 inches in tower 3. The vapours formed are condensed in heat exchangers and coolers 32, 33 and the condensate is collected in receiver 35 and passed through line 42 into the fractionating tower 4 where the total products of the process are fractionated to give a final gasoline product recovered through lines 43, 38 and coolers 39, 50 to receivers 47, 51, and reflux which is fed through line 41 to the pump 7 as stock for the cracking coils 1. A low boiling gas oil fraction is also collected from the tower 4 as a side stream and fed to a stripper 44 from which it is in part rejected from the system through lines 45, 46 and blended with residual tar from tower 3 to give a fuel oil 'and in part is led as absorption medium to a tower 5 to which the gaseous products of the system are fed from the separators 47, 51. The enriched oil is fed by pump 17 through line 42 into the tower 4. The gasoline condensed in receiver 47 is returned through line 48 to the tower 4 as reflux while the gasoline collected in the separator 51 is stabilized by passing it through heat exchanger 64 into a stabilizer tower 6 having a reboiler element 61 heated by hot reflux from the tower 4 circulated by a pump 13.