Patent GB-767667-A (GB)
Title: Improved integrated hydrofining process
IPC: C10G45/02
Filed: 1954-07-23
Abstract: A hydrofining process comprises mildly hydrofining a cracked petroleum oil boiling in the motor fuel boiling range (between 275 and 430 DEG F.) in a first hydrofining zone where the hydrogen consumption is below 60 standard cubic feet per barrel of oil feed, mildly hydrofining a second cracked petroleum oil boiling in the heating oil boiling range (between 400 and 650 DEG F.) in a second hydrofining zone where the hydrogen consumption is as above, separating hydrofined products from the two zones, combining the gaseous products including hydrogen from the two zones and passing them to a purification zone to remove hydrogen sulphide and recycling them to the first and second hydrofining zones.  The starting materials may be obtained by distilling a crude oil and cracking the fractions obtained.  A crude oil is distilled in unit 1, and a heavy virgin naphtha boiling between 275 DEG F and 430 DEG F. passed therefrom to a thermal reforming zone 8, from which the product passed to a fractionating zone 10 where constituents boiling below the motor fuel boiling range <PICT:0767667/III/1> are removed, the remainder passing by a line 12 to a prefractionation zone 13.  A virgin heating oil boiling between 400 DEG F. and 550 DEG F. is passed from distillation unit 1 to a sweetening zone 14.  A virgin gas oil boiling between 550 DEG F. and 900 DEG F. is passed from distillation unit 1 to a cracking zone 16 containing a catalyst such as alumina on silica.  A residuum from unit 1 is vacuum distilled in a zone 17, constituents boiling up to 1150 DEG F. being removed and passed to the cracking zone 16. cracked products from zone 16 are passed to a distillation zone 20, where a cracked naphtha and lower boiling constituents are removed by a line 21, a light cracked heating oil (boiling between 400 DEG  to 580 DEG F.) is removed by a line 22 and a heavy cracked heating oil (boiling between 500 DEG  to 650 DEG F.) is removed by a line 23, while a cycle oil is removed by a line 24, a portion being recycled to zone 16 and the remainder passed to a thermal cracking zone 26.  A cracked product is removed from cracking zone 26 by a line 27 and passed to a distillation zone 28, from where a fraction boiling between 400 DEG F. and 650 DEG F. is passed by a line 31 to the prefractionator 13 together with the heavy catalytically cracked heating oil segregated by line 23.  The light catalytically cracked heating oil segregated by line 22 is caustic alkali washed and blended with the heating oil from sweetening zone 14.  A residuum from distillation zone 17 is passed to a visbreaking unit 35, the product being distilled in a zone 37, a fraction boiling between 100 DEG F. and 430 DEG F. being passed therefrom to the prefractionator 13, and a fraction boiling between 400 DEG F. and 650 DEG F. being removed by a line 41.  From prefractionator 13 a heavy fraction boiling above 650 DEG F. is removed and recycled to thermal cracking zone 26 by a line 43, while a naphtha fraction boiling between 275 DEG F. and 430 DEG F. is removed by a line 44, and a heating oil boiling between 400 DEG  and 650 DEG F. is removed by a line 45 and combined with the heating oil removed by line 41.  The fraction removed by line 44 is heated in a furnace 47 and hyrofined in a zone 48 containing a catalyst, preferably cobalt molybdate on alumina, the product being passed to a stripper 50, into which steam is introduced by a line 94. Hydrogen, hydrogen sulphide and low boiling constituents are removed by a line 51, cooled, condensed constituents removed and returned to stripper 50 as reflux, and the hydrogen and hydrogen sulphide passed to a zone 59 where the hydrogen sulphide is removed by a solvent such as diethanolamine, the hydrogen being recycled to hydrofining zone 48. The hydrofined naphtha is removed from the stripper 50 by a line 93, caustic alkali washed, water washed, and removed.  The heating oil removed by line 45 from prefractionator 13 is heated in a furnace 64 and hydrofined in a zone 65 containing a catalyst, preferably molybdenum oxide on alumina, the product being passed to a stripping zone 67. Hydrogen, hydrogen sulphide and low boiling hydrocarbons are removed by a line 68, cooled, condensed constituents removed and returned to stripper 67 as reflux, the hydrogen and hydrogen sulphide being passed to 59, hydrogen being recycled therefrom to hydrofiner 65.  Refined heating oil is removed from stripper 67, caustic alkali washed, water washed, and removed.