US2045696A - Process for refining oil - Google Patents

Description

June 30, 1936.

S. E. CAMPBELL PROCESS FOR REFINING OIL Original Filed Jan. 10, 1930 /8 /.3 A; I 25:15:22 g coNas/vssz.

v 8 Q m s (:1: q 3 c, ://9 k as Q L /Z /4 SULPHVZ oIdX/DE IN I 56 STILL ACID I v i ACID ACID Aa/a new Z awqb 4L KAL 4L KIM IN VEN TOR Patented June 30, 1936 Sumner E. Campbell, Long Beach, Calif.

Application January 10, 1930, Serial No. 419,850

, Renewed February 15, 1 935 4 Claims.

This invention relates to a process for refining hydrocarbon oil and has for its particular object the treatment of distillates obtained by the cracking of petroleum, shale oil, coal tar, and the like to free such distillates from objectionable compounds which make their color unstable, form gummy deposits, and the like.

Another object of the invention is to produce a fuel for internal combustion engines having a high anti-knock value.

Another object is to recover valuable by-products in the refining of distillates.

In the ordinary process of refining cracked distillates, of which cracked gasoline may be referred to as an illustration, a treatment with concentrated sulphuric acid not only removes certain valuable products as impurities, but the finished gasoline is unstable in' color and the treatment is expensive.

In general a cracked distillate contains some saturated hydrocarbons, usually a larger amount of unsaturated hydrocarbons, aromatic, or cyclic hydrocarbons, together with compounds such as nitrogenous and perhaps other bases, acidic compounds such as naphthenic acids and other organic acids, phenols, cresols, and the like, and sulphur in various forms; substantially all of the foregoing, except the saturated hydrocarbons, being absorbed or dissolved as impurities by the solvent used.

Preferably a selective solvent such as liquid sulphur dioxide is herein used to treat a cracked distillate which, after such treatment, is composed predominately of paraflines, naphthenes, and perhaps other saturated and stable compounds having a low anti-knock value, but otherwise being a high class fuel for internal combustion engines.

By now treating such compounds asare removed from the cracked distillates as impurities, certain compounds may be segregated and added to the'original stock to form a fuel having high anti-knock and other properties.

By reference to the diagrammatic sheet of drawing, a cracking stock, such as fuel oil, gas oil, shale oil, coal tar, or the like is fed to a pump [0 and forced thence through a cracking coil ll under such conditions of heat and/or pressure that a substantial molecular change is made to yield the desired distillates.

The pressure may be maintained by a valve 12 and the cracked stock is fed to a flash chamber I3 wherein distillates are vaporized and heavy residuums withdrawn through a valve M, the vapors passing through a line I5 to a fractionator l6, whence heavy distillates are withdrawn through a valve l I, the desired distillates in vapor form then passing through a line l8 to a final condenser l9 whence the condensates pass through a valve and line 2| to a treating chamber 22 containing liquid sulphur dioxide and held at a low temperature therein by cooling coils 23 or otherwise.

Liquid sulphur dioxide is supplied to chamber 22 through line 24 and the treated distillate is taken off through a line 25. The liquid sulphur dioxide with its dissolved impurities is run from chamber 22 into a still 26, whence the sulphur dioxide passes ofi in vapor-form to be condensed under pressure in condenser 21 for further use.

Inasmuch as the cracking system may be entirely under pressure and is well known, and the liquid sulphur dioxide treatment is well known, no further exemplification herein is'deemed necessary. I

The extract containing basic and acidic material, with perhaps a little sulphur dioxide, is now subjected to'a selective treatment with an acid material, such as dilute sulphuric acid, to remove certain basic impurities which include nitrogenif,

The remaining extract then comprises sub stantially a mixture of unsaturated and aromatic hydrocarbons.

The steps of treating the extract taken from still 26 through line 29 and valve 30 with a dilute sulphuric acid, about 40% H2804 and then with an alkaline solution are more particularly set forth in my c'o-pending application Serial Number 349,606, filed March 25, 1929.

As exemplified herein, a similar dilute acid treatment'is given the, extract by passing the same in succession from line'30 and valve 3| through a plurality of acid towers 32, 33, 34, 35, filled with contact material and filled to a predetermined level XX with dilute acid from pipe 36.

The extract flows fromtower 32 to tower 35 through pipes 31, 39, 4| and valves 38, 4E 42 to contact the extract successively with a relatively dilute acid and succe'edingly stronger acid until the acid strength in the first tower 32 is reduced by reaction to a desired degree, or is substantially exhausted.

Valves 44,45, 3|, 3|, 3I', 46, 46, 46", 46, 41, 41', 41 are provided, together with manifolds 48 and 49,to divert the-extract fro-m tower 35 through line 43 to tower 32 after exhausted acid from tower 32, together with reaction products segregated therefrom by the acid, has been withdrawn and tower 32 is recharged with fresh acid, so that tower 33 becomes the first in the 50", 50" respectively and passes through a manifold 5| to a storage tank 52 whence it may be withdrawn as desired for use or further treatment.

In the above dilute acid treatment a plurality of acid towers is kept in operation to provide a stream of extract from which basic material, such as pyridine and its homologues, has been removed and which stream is passed to a settling chamber and thence to a plurality of towers 53, 54 containing an alkaline solution and operated individually, or successively, as before described for the acid towers.

Such alkaline solution absorbs or removes acidic impurities such as naphthenic acids, phenols, cresols, etc., which, when the alkaline solution is reactively exhausted, may be removed therewith through a manifold 55 to a storage tank 56, wherein the alkaline mixture is rendered acid by the introduction of acid through valve 51 which causes the separation of free acidic impurities which may be recovered through valve 58.

The extract thus treated with dilute acid and alkaline solution, comprises a mixture of unsaturated and aromatic hydrocarbons, the first of which are unstable compounds tending to form gums and resins and darken in color.

It is necessary to remove such unstable unsaturated compounds and this is done by passing the mixture through pipe 59 to a tank 60 to which relatively concentrated sulphuric acid, for example 70% to 90% H2804, is supplied through a valve 61 while a temperature of about 0 F. is held by the cooling coils 62.

After a suitable time of treatment, with agitation, at low temperature, a large proportion of the unsaturated compounds combines with the sulphuric acid and is removed through valve 63, the low temperature reducing the tendency to polymerize, which takes place at higher temperatures.

The remaining hydrocarbons, principally aromatic compounds of high anti-knock value, while in acid condition pass through a line 64 to a tank 65 containing an adsorbent clay which removes any remaining acid compounds present and leaves the oil freed therefrom and of stable color.

With certain stocks, the clay treatment may be replaced by an alkaline treatment, caustic soda solution ;for instance, in which case tank 65 is cut out and the oil passes from tank 60 to a tank 66 containing an alkaline solution which neutralizes any acid present, and thence to a wash tank 61 wherein water removes any alkali present.

In either event, the remaining purified aromatic hydrocarbons of high anti-knock value are passed either through valves 68 or 69 to a line 10 and mixed with the saturated hydrocarbons comprising part of the original stock in line 25 whereby a motor fuel of high anti-knock value is produced freed from unstable impurities.

In general, the so mixed fuel passing out of line 25 may have anti-knock properties superior to anti-knock standards for such fuel and therefore such may be blended in desirable proportions with straight run gasoline to improve the antiknock properties of the latter.

It is, of course, obvious that the mixture of substantially pure aromatic hydrocarbons passing through line 10 may be subjected in whole or in part to efiicient fractionation for the separation of individual aromatics such as benzol, toluol, etc., for various other uses.

I claim as my invention:

1. A process of preparing an anti-knock fuel which comprises: cracking an oil to obtain distillate therefrom, separating the distillate into two portions by dissolving out unsaturated and other hydrocarbons with liquid sulphur dioxide, removing the sulphur dioxide, treating the extract with dilute sulphuric acid until such acid is substantially exhausted, then treating the distillate freed from mineral acid and mineral acid derivatives with an alkaline solution to absorb the organic acidic impurities and then with concentrated sulphuric acid at a low temperature, neutralizing the extract while in acid condition with clay, and mixing the extract with the other of said first two portions to obtain a motor fuel free from the basic and acidic impurities in the original oil.

2. A process of preparing an anti-knock fuel which comprises: cracking an oil to obtain distillate therefrom, separating the distillate into two portions by dissolving out unsaturated and other hydrocarbons with liquid sulphur dioxide, removing the sulphur dioxide, treating the extract with dilute sulphuric acid until such acid is substantially exhausted, then treating the distillate freed 2 from mineral acid and mineral acid derivatives with an alkaline solution to absorb the organic acidic impurities and then with concentrated sulphuric acid 'While at a loW temperature, neutralizing the extract, and mixing the extractwith the other of said first two portions to obtain a motor fuel free from the basic and acidic impurities in the original oil,

3. A process of preparing an anti-knock fuel which compriseszcracking an oil to obtain distillate therefrom, separating the distillate into two portions by dissolving out unsaturated and other hydrocarbons with liquid sulphur dioxide, removing the sulphur dioxide, treating the extract with dilute sulphuric acid until such acid is substantially exhausted, then treating the distillate freed from mineral acid and mineral acid derivatives with an alkaline solution to absorb the organic acidic impurities and then with concentrated sulphuric acid while at a low temperature about 0 F., neutralizing the extract, and mixing the extract with ,the other of said first two portions.

4. A process of preparing an anti-knock fuel which comprises: cracking an oil to obtain gasoline distillate therefrom, separating the distillate into two portions by dissolving out unsaturated and other hydrocarbons with liquid sulphur dioxide, removing the sulphur dioxide,

treating the extract with dilute sulphuric acid until the acid is substantially exhausted, then treating the distillate freed from mineral acid and mineral acid derivatives with caustic soda solution to absorb the organic acid impurities and then with concentrated sulphuric acid at a low temperature, neutralizing the extract, and mixing the extract with the other of said first two portions to obtain a motor fuel free from the basic and acidic impurities in the original oil.

' SUMNER E. CAMPBELL.

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