US2303970A - Method for desulphurizing mineral oils - Google Patents

Description

Dec. 1, 1942, F; E. WILKINSON METHOD FOR DESULPHURIZING MINERAL OILS Filed Aug; 27, 1940 Ibane/s55' mma@ Ohh (HNR Patented Dec. l, li942 METHOD FOR DESULPHURIZIN G MINERAL OIL Francis E. Wilkinson, Glendale, Calif. Application August 27, 1940, Serial No. 354,339

6 Claims.

This invention relates generally to the processing of petroleum oil and the derivative products of the oil and more particularly relates to processes for the desulphurization of certain petroleum products.

In present day practices great volumes of a product known as pressure distillate is produced in the cracking of petroleum oils. This product, as an example, has a specific gravity of 47.1 Baum A. P. I., an initial boiling point of between 204 and 210 F., and an end point from approximately 3961 to 408 F. In appearance the distillate is dark reddish brown and it contains varying quantities oi sulphur depending upon the locality where the petroleum is produced. It is the ordinary practice to treat this distillate for the purpose of vlowering the sulphur content and decolorizing it, the sulphur content being required to be reduced to four-tenths of 1% or lower. Ordinarily a sulphuric acid and caustic soda treatment is employed to accomplish this followed by a doctor solution treatment. These treatments require considerable expensive apparatus and the process itself takes considerable time, usually requiring in the neighborhood of twenty-four hours to complete. After being treated the product is mixed with either casing head gasoline or straight run gasoline to bring down the initial boiling point and reduce the sulphur content to less than one-tenth of 1% to meet specications of rst structure gasoline and at the same-time provide a suitable gasoline that can be leaded by treatment with tetraethyl lead.

It is an object of this invention to provide a simple method requiring a much shorter time than the common acid process and which is made possible by the use of an organic material instead of sulphuric acid, which material is noncorrosive to the apparatus and which is Very cheap as compared to the materials used in other processes.

Referring to the drawing which is for illustrative purposes only, the gure illustrates diagrammatically the flow sheet of one arrangement of apparatus which may be utilized in carrying out my process.

More particularly describing my method or process, the distillates to be treated may be what are commonly known as processed heavy pressure distillates and kerosene distillates from cracking plants, al1 of which may be termed raw untreated gasoline stock. In the drawing this raw stock from the tank, indicated at I, is introat 3, it being understood that this agitator as well as the other apparatus referred to may be oi any well known or standard type of apparatus commonly used in the industry.

For the purpose of 'cleaning the distillates to be treated and to remove some of the sulphur compounds and other coloring materials, what I have termed a rst treating solution, consisting of raw denatured alcohol, is introduced into the agitator 3 from a tank 4th'rough pipe 5 where the alcohol and distillate are thoroughly mixedl and agitated. This agitated mixture, from the agitator 3, ows through pipe B to a settling tank, indicated at l, where I have found that the distillates which have become a yellowish color separate and rise to the top of the settling tank leaving a residue of bottoms which contain sulphur compounds, sludges and very nearly all of the first treating solution, that is, the raw denatured alcohol.

This rst treating solution of raw denatured alcohol may be recovered and reused in the system. For this purpose the bottoms from the settling tank I are discharged through pipe 8 into a still 9 which is heated to approximately from to 190 F. to distill ol the alcohol which passes through pipe I0 to a condenser II and from this condenser through pipe I2 to the first treating solution tank 4. The bottoms or residues from the still 9, including some water carrying sulphur compounds and coloring matter, are discharged through pipe I3 to a sump or collector. The distillates from the settling tank 1 are discharged through pipe I4 to an agitator or mixer I5 into which is introduced a second treating solution from tank I6 through pipe Il.

This second treating solution preferably' consists of solutions containing organic acids such as a very dilute solution of oxalic, tartaric or citric acids. Such treating solution is mixed in the agitator I5 in the percentage of from ve to ten per cent of the distillates being treated. I have found that by adding a very small quantity of a neutral soap, for instance, approximately three ounces of soap to one barrel of distillate to the second treating solution that the amount oi such solution required may be greatly reduced.

I have found that certain by-products of plants in which fruit, particularly citrus fruit, is processed for the forming of citric acid, pectin and oils such as lemon oil can be used. As for instance, the residue of clay, used in producing such products, which clay is impregnated duced through pipe 2 into an agitator indicated 55 0r contains some of the chemicals or substances of the fruit being' treated and the products therefrom during the treatment above referred to, I have found to be particularly efficient for the purposes desired. As an example, one and onehalf pounds (l1/2 lbs.) of this clay product added to a barrel of distillate produces an entirely satisfactory agent.

I have also found that the Wash water and other solutions from the citrus fruit plants reierred to may be used as the second treating agent above referred to.

From the agitator l5 the mixture of the distillates and the second treating solution is discharged into a still I8 through pipe I9.'

Natural gas or other hydro carbon gas is passed through a high frequency electrolyzer generally indicated at 20. The gas coming' from any suitable supply, not shown, is introduced into a tube `2 equipped with an inner coil 22 and an outer coil 22. From the tube 2| the eleotrolyzed gas then containing nascent hydrogen passes through pipe 23 into the bottom of the still Where it bubbles up through the liquid therein. The still I8 is operated at a temperature of approximately 420 F, which is the highest distillation temperature for the products treated, the temperatures in the entire system ranging from 120 to 420 F. with little or no pressure maintained on the system. The residuum is relieved from the sill through pipe 24 and consists of sulphonated compounds, water and sludge. The distillates from the still are passed through pipe 25 to a condenser 26 and from the condenser pipe 21 to any suitable storage.

The condensed product has changed from a yellowish color, when introduced into the still, to from slightly lemon yellow to water white and sweet smelling. If desired a subsequent Washing step of the character commonly used in other desulphurizing processes may be employed to remove any flocculent or suspended matter which settles with the water from the distillate.

After the washing step, just above referred to, if desired the sulphur content may be further reduced by treating the distillate with doctor solution such as used in ordinary desulphurizing methods. However, this is not ordinarily necessary in View of the fact that with my treatment of the distillates with the organic material referred to the sulphur content is reduced from approximately nine-tenths of one percent in the distillates when introduced into the still to approximately three-tenths of Vone percent in the finished product which latter percentage is less than the required minimum percentage for the mixture of the distillate with gasoline as is the common practice for making motor fuel.

With my process, instead of requiring twentyfour hours or more as is the time required with common methods now used for desulphurizing,

the desired results may be accomplished in ali-- proximately two hours time.

I claim as my invention: y

1. In the method of desulphurizing pressure distillates and the like the steps of adding to the distillate a quantity of an aqueous solution of citrus fruit acid compounds; agitating the mixture; and distilling the resultant mixture to a temperature of approximately 420 F.

2. In the method of desulphurizing pressure distillates and the like the steps of adding to the distillate an aqueous solution of citrus fruit acid compounds; and distilling the resultant mixture to the end point of gasolines.

3. In the method of desulphurizing pressure distillates and the like the steps of adding to the distillate a quantity of an aqueous solution of citrus fruit acid compounds; distilling the resultant mixture at a temperature to vaporize the gasolines therein; and cooling and condensing the vapors.

4. In the method of desulphurizing pressure distillates and the like the steps of adding an alcohol to the distillate; agitating the mixture; then allowing the mixture to settle; removing the lighter constituents to an agitator; addingto the mixture an aqueous solution of citrus fruit acid compounds; thoroughly agitating such mixture; distilling the resultant mixture and during such distillation introducing into the mixture a gas containing hydrogen resulting from the electrolyzation of a hydrocarbon gas; and con densing the distilled product.

5. In the method of desulphurizing pressure distillates and the like the steps of adding to the distillate a denatured alcohol; agitating the mixture; then allowing the mixture to settle; removing the lighter constituents to an agitator; adding to the mixture an aqueous solution of citrus fruit acid compounds and a soap; thoroughly agitating such mixture; distilling the resultant mixture and during such distillation introducing into the mixture a gas containing hydrogen resulting from the electrolyzation of a hydrocarbon gas; and condensing the distilled product.

6. In the method of desulphurizing pressure distillates and the like the steps of adding to the distillate a denatured alcohol; agitating the mixture; then allowing the mixture to settle; removing the lighter constituents to an agitator; adding to the mixture an aqueous solution of citrus fruit acid compounds obtained from the washing of citrus fruit; thoroughly agitating such mixture; distilling the resultant mixture and during such distillation introducing into the mixture a gas containing hydrogen resulting from the electrolyzation of hydrocarbon gas; and condensing the distilled product.

FRANCIS E. WILKINSON.

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