US1709315A - Oe san francisco - Google Patents

Description

April 16, 1929. LACHMAN 1,709,315

METHOD OF REFINING MINERAL OILS Filed Dec. 8. 1926 HYPOCHLORITE IN V EN TOR.

A TTORNEYS Patented Apr. 16,1929.

UNITED STATES mans PATENT OFFICE.

ARTHUR LACHMAN, F BERKELEY, CALIFORNIA, ASSIGNOR RICHFIELDOIL GOM- PANY OF CALIFORNIA, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF DELA- WARE.

METHOD OF REFINING MINERAL OILS.

essb For thepurpose ofsiinplifying the description, referencewillbe made to gasoline only. i

Crude gasoline is usually obtained by distillation or by cracking ofcrude petroleum and 5 consists of a mixture of saturated and unsaturated hydro-carbons, together with as-' phaltic materials, sulphur compounds, nitrogen bases and other substances of an unde fined nature. These latter substances are readily oxidi'zable at ordinary temperatures and are responsible for the color changes which take place when refined gasoline 1S stored. These oxidizable substances are removed with difficulty when gasoline is'refined by the methods now in common use. In order to show thenature of my invention, it is desirable to describethe methods now in common use in oil refineries, and particularly that step of gasoline-refining which consists in de-odorizing and stabilizing the same. Crude gasoline obtained from the stillsor cracking retorts', after condensation is treated with approximately 6 to 8 per cent by weight of sulphuric acid-according to the nature of the crude gasoline. The treatment usually consists in agitating the mixture of gasoline-and sulphuric acid for an hour or more and then permitting it to settle, after which sulphuric acid sludge is withdrawn and'the gasoline is washed with a solution of alkali and finally with water. This treatment removes most of the impurities, but a subsequent-treatment is frequently necessary in order to complete the de-odorization. For this purpose a solution of sodium plumbite is commonly employed. The general objections toatreatment of this character are method is frequently subject to discoloration upon storage. Secondly, considerable quantities of sulphuric'acid are required which are difficult to recover. Thirdz as 'm uch as ten percent of the valuable hydrocarbons contained in; the crude gasoline may be lost. Fourth The treatment must frequently be that described.

followed with a deodorizing process such as My invention consists in the discovery that the sulphuric acid normally used in refining crude gasoline may be replaced with phos phoric acid and that gasoline treated with phosphoric acid and in some instances subsequently with a small amount of sulphuric acid or sodium hypo-chlorite will be waterwhite; stable as to color upon exposure to the air and will, furthermore, require smaller amounts of acid and will reduce crude gasoline losses to a maximum of less than 2%.

a The process briefly stated consists in treating gasoline or other volatile hydro-carbons by passing thesame whilein a vapor state through or in contact with a body of phosphoric acid to remove nearly all of its impurities and subsequently completing the refining operation by condensing the vapor and then treating it with a small percentage of sulphuric acid but preferablyby washing it .with a strongly alkaline solution of sodium hypo-chlorite. For the purpose of describing the process in more detail, reference will be made to the accompanying drawings, which is a diagrammatic view of one form of apparatus which may be employed.

Referring to this drawing, A indicates a cracking retort or the like from which the crude gasoline vapors discharge throughthe pipe line 2. B indicates a tower of suitable height and diameter filled with a resistant material, such as fireb'rick or the like indi cated at 3 which forms numerous tortuous passages through the tower. Disposed above the tower or adjacent to the same is a tank containing phosphoric acid preferably commercial acid of approximately 85% strength. This tank is connected with the top of the tower by means of a pipe 4 having a regulating valve 5. This pipe terminates over a spreader plate 6 and this plate evenly distributes the acid when the valve 5 is opened over the brickwork or resistant material. The acid then flows downward through this material and may finally be discharged as follows :-1st: Gasoline purified by this through the bottom by a pipe 7, after which it is treated for recovery. The tower is also provided with a steam or water inlet pipe 8 which intermittently .or continuously supplies a predetermined amount 'ofwater to the acid. The vapor from the still or cracking retort A enters the lower end of the tower at w a point 9. 'It passes up through the numerous tortuous passages inthe brickwork and comes into intimate contact with the phos phoric acid travelling or flowing over the same. Both acid and vapor are maintained at a; teniperatureyat from 160 to 200 C, and

the-vapordischarges at the upper end of the treatment of the refining oi? crude gasolin'e by my process. v During this treatment thema v o-r portion oithe impurities are removedand carried out with the phosphoric acid as a v sludge.

ll1is-treatinent is, however, not sufficient and the condensed gasoline obtained is not commercially usable due to the presence of some odorous and gummy materials, as well to its water content and furthertreatment is, accordingly, necessary. The condensate is conducted to a settling tanklEZ where the water allowed to deposit and is v withdrawn. Thegasoline is then agitated for a :iew minutes with a strongly alkaline solution of sodium.hypochlorite. This removes the microns and gummy constituents which have escaped the action of the phosphoric s acid. Aiter agitation ior iew minutes the mixture is again allowed to settle, theallnr line sludge is withdrawn and the gasoline is now ready for use, requiring only occasionaily a slight nitration toreinove any suspended alkaline sludge.- It is essential that the solution. of sodium hydroxide employed for this purpose bestrongly alkaline and carrygarelatively. high contcntoi: sodium hypo-chlorite. i

As an example of the proportions of the :Illtttfilflttls required forthe above described process for 100 pounds of gasoline approxiniately three pounds of phosphoric acid will be required duringthe first stepotf the refining operation. ,lThe strength of the phosphoric acid isv the ordinary.commercial strength of 85% butthis may be varied within reasonable limits. The temperature at which the processis carried out will of itself determine the concentration of the acid. but the concentration oft-he acid may be controlled by regulating the quantity of water or water vapor admitted. From; 98 to 99 pounds of water-white gasoline .will be obtained by this step which. is separated from the. waterwhich distills over w th it, which i p I ti vatii'i the condensate with a stron ly alkawill be '2to dpoimds; as the process norcarried out. p ,The gasoline is now sepa- 1T-ated iti'ointhewater andis thereupon agipassing the tatod with a solution of one-quarter pound of sodium hydroxide and one eighth of a pound 01" sodium hypo-chlorite dissolved in one pound of water. This agitation with the alkaline sodium hypo-chlorite solution sliouldbe carried out at ordinary room temperature iif necessary with the aid of outside cooling. The agitation requires only from five to tenminutes. The gasoline loss through this operation is less than onequarto pound. Thcgasoline may thereupon be stored torfuture use or filtered if required for prompt service. i

Summing up the two steps of the operation, it will bemoted that an exceedingly small amount of'acid is required when comparison is made with thecommon sulphuric acic treatn'irnt in the manner described.

Furthermore, the total loss of gasoline is reduced to a substantial amount of less than 2% of the total quantity treated. The sodium-hypo-chlorite is not recoverable but.

the phosphoric acid as well as the'sodium hydroxide maybe recovered and will be the subject ofv separate application Havin thus described my invent-iomwha I claim anddesire tosecure by Letters Pat- 2. A method of'refining mineral oils, which consists in heating the oil to 'form a vapor at a temperature of approximately 160 to 200 Oi, passing the heated: vapor through or-in contact with a body of phosphoric acid maintained at a similar temperature and having a concentration of approximately 85%, maintaining the concentration of the acid substantially constant by the addition of water and finallv condensing the vapor after passagejthroughthe acid.

3. A method of refining mineral oils which consists in heating'the oil to form a vapor,

dcnsate with a solution containing 18% sodium hydroxide and 9% sodium hypoehlorite.

4. A method of refining mineral oils which consists in heating the oil to form a vapor, passing the heated vapor through or. in contact with a body of phosphoric acid, maintaining theacid in a fluid condition by 'an of waterand; condensingithe vapor adcition passingthrough the fluid acid,wand

line solution of hypo-chlorite.

ARTHUR Laen iiiii.

heated vapor through or in convtact with a body ofphosphoric acid and then condens ngthe vapor, and treating the con-

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