US1660295A - Treatment of hydrocarbon residues and product obtained thereby - Google Patents

Description

Patented Feb. 21, 1928'.

UNITED STATES- PATENT OFFICE.

RALPH T. GOODWIN, 0F ELIZABETH, NEW JERSEY, ASSIGNOR TO STANDARD 'OIL DE- VELOPMENT COMPANY, A CORPORATION OF DELAWARE.

mnna'rmnnr onnxnnooamson RESIDUES AND rzaonuo'r oiaramnn THEREBY.

No Drawing.

ing the residues therefrom, constitutes an:

other feature of the invention.

In the operation of refinery cracking equip-.

ment there are produced heavy oil residues or tar,.the value of which is im'pairedby their tendency to form solid or-;-semi-solid carbonaceous matter on more or less prolonged standing. This carbonaceous matter may form a precipitate, or a suspension, or both. For convenience it may be referred to as a. sediment.

For example, the pressure tar obtained from pressure stills is ordinarily made substantially unsalable as a fuel oil because of this characteristic, and is frequently not well adapted even for fuel use in the refinery. The deposited carbon may clog the pipes or burners, or cause other difiiculties. Similar trouble is experiencedwith cracking coil tar and analogous materials. The expedients heretofore proposed for correcting this, such as blending with a lighter oil, distilling and fluxing back a portion of the distillate, settling, filtration, and the like, fail to remove the real source of difliculty and do not give complete satisfaction.

In accordance with the present invention, heavy residues are substantially freed from sediment-forming bodies by treatment with an acidic material preferably a dilute water solution of an aci Ordinarily a small percentage of acid, onehalf to one percent -'by volume of the oil treated, is sufficient. However, larger proportions of acid may be used without disadvanta e. Sulfuric acid is most economical, but ot er acids having the property of precipitating the sediment may be used, for example, dilute hydrochloric acid, dilute acetic acid, and dilute solutions of salts, such as sodium acid sulfate or aluminum sulfate, which hydrolyze to form acids. Sulfuric acid of 30-60 Be. is suitable. Weaker acids sometimes fail to act completely, and

stronger acids may give trouble by the for-- Application filed April 25, 1925. serial m. 25,941.

It is frequently bring the acid and oil rapidly into intimate contact... The oil may be treated with the acid at ordinary pressure; sometimes, however, it is advantageous to use superatmospheric pressure.

n a preferred form of the invention, when working with cool tar, about one-half r centby volume of 37 B. sulfuric aci is added and the mixture is heated to about 20027 5 F. Carbonaceous sediment settles out rapidly, leavin an upper layer of tar substantially free om solids and B. S. I term this material stabilized tar, as it does not produce substantial amounts of sediment even after long standing. This tar, after removal of the sediment, will ordinarily pass specification requirements for Bunker C fuel oil, and some tars treated in the manner described will pass specifications for higher grades. Besides its use .as a fuel oil, the product may be disposed of to advantage in other ways, for example as a stock for cracking when suitably blended. with as oil or the like. Heretofore, pressure tar as not been considered suitable for cracking on account of the large amount of carbon deposited. This difficulty is substantially avoided by the treatment in accordance with this invention. Various other blends may be prepared from the pressure tar.

Aparticularly important advantage of the invention is in connection with the operation of cracking equipment. In present practice, the necessity of obtaining a residue which canbe practically disposed of imposes a serious limitation upon the operation. In pressure distillation, if an amount of pres.-

sure distillate approaching the maximum is.

sediment-producing bodies. A similar limitation is encountered in the operation of cracking-coil and drum equipment and the like.

' In accordance with the present invention, cracking is regulated to produce objectionable residues of the type just described and these are treated with dilute acid, thereby fitting them for use as a fuel, or otherwise.

This procedure enables me to reduce the temperature to about 250275 F. The

proper amount of acids may then be intro duced into the tar line. The tar and acids are mixed, for example in a mixing column. The treatment with acid may take place under the pressure prevailing in the distillation apparatus. The mixtureof oil and acid is run to a settling orthickening device, and after a suitable periodthe greater portion'of the tar may be drawn off as a clean product. The remaining portion containing solids may be substant ally completely clarified by filtration, preferably througha rotary continuous vacuum filter. Other forms of filter may be used. The whole of the treated residue may be filtered or it may be allowed to settle and the liquid separated by decantation, siphoning off or the like.

Inert ranular material, for example powpered co re, may be added to secure more eificient filtration. The solid material sepa rated in the filter or otherwise may be used as a fuel, with or without briquetting. When coke is used as a filter aid, especially good fuel briquettes may be made from the material collected in the filter. 1 Heavy oils, such as crude still bottoms, may be blended with pressure tar and the mixture then treated with acid in accordance with this invention. Crude still bottoms and the like ordinarily contain more or less cracked material that gives rise to objectionable deposits. Acid treatment tends to accelerate the formation of sediment, but the bottoms are of such high viscosity that settling of the sediment is slow. However, I have found that if the bottoms are diluted with pressure tar or the like, and then treated, good results are btained. The acid causes sediment to separate from both the bottoms and the -tar. The treated mixture is valuable as a fuel oil, since its specific gravity and viscosity are relatively low, and sediment and water are substantially removed.

In some cases it is desirable to blend the pressure tar or the like with a light oil prior to treatment with the acid, or to use a blending agent to facilitate the filtration of the tar after treatment. The treated tar, after separation of solids and acid solution, ordinarily contains a trace of acid. This may be neutralized or removed, but it is ordinarily unobjectionable.

In my application for United States patent, Serial N 0. 3,595, filed January 20, 1925, I have described and claimed the stabilization of pressure tar or the like by treatment with acid oil.

Various details of the procedure described in connection with this invention may be modified within the scope of the appended claims, in which itis my intention to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

1. Process of treating a heavy hydrocarbon oil residue derived from a cracking process, and normally characterized by formation of carbonaceous sediment onstanding, comprising bringing the said residue into contact with a small amount of an acidic body in non-sludge-forming concentration, whereby relatively rapid formation of sediment is obtained, and separating the sediment.

2. Process of treating a hydrocarbon oil residue of the type of pressure tar, comprising bringing the residue into contact with a small amount of a dilute acidic body in nonsludge-formingconcentration, whereby a relatively rapid formation of sediment is obtained, adding an inert granular material to the mixture, and separating the oil from the sediment and added solids.

.3. Process for stabilizing pressure tar, comprising treating the tar with a dilute aqueous solution of sulfuric acid in nonsludge-forming concentration at an elevated temperature, whereby a relatively rapid precipitation of sediment is obtained, and separating the sediment.

4. Process for stabilizing pressure tar, comprising treating the tar with about onehalf to one percent by volume of sulfuric acid of 3060 B., heating to 200275 E, whereby relatively rapid precipitation of sediment is obtained, and separating the sediment.

5 The invention according to claim 4, in WlllCh the treatment with acid is carried on under superatmospheric pressure.

6. Process of preparing a commercially valuable heavy hydrocarbon oil, comprising sub ectin an oil to cracking conditions, continuing t e crackin treatment until a residue characterized y "a tendency to form cracking conditions, continuing the cracking treatment'until a residue characterized by a tendency to precipitate large amounts ofith carbonaceous sediment is produced, drawing the residue from the cracking one, introducing a dilute acid in non-sludgeforming concentration into the stream of residue, 'mixing the acid and residue, and separating the sediment.

8. Process of preparing heavy hydrocarbon residues, comprising subjecting an oil to cracking conditions, withdrawing the residue from the cracking zone, mixing a dilute solution of an acid in non-sludge-forming concentration with the residue While the same remains at substantially the temperature of the cracking operation, settling and removing separated sediment, and Withdrawing the substantially clear supernatant liquid.

9. Process of preparing heavy hydrocarbon residues, comprising subjecting an oil to cracking conditions, withdrawing the residue from the cracking zone, treating the residue without substantial loss of temperature with a dilute acid in non-sludge-forming concentration, whereby a relatively rapid precipitation of sediment is obtained, separating the sediment, withdrawing the substantially clear supernatant liquid, and filtering the residual liquid containing solids.

10. Process of preparing heavy hydrocarbon residues, comprising subjecting an oil to cracking conditions, mixing a small amount of a dilute water solution of acid in non-sludge-formin concentration with the hot residue, where y a relatively rapid formation of sediment is obtained, and separating the liquid from the sediment.

11. A heavy hydrocarbon oil prepared by treating pressure tar with-a small amount of acid in non-sludge-forming concentration.

12. A heavy hydrocarbon oil prepared by treating a mixture of pressure tar and crude still bottoms with adilute acid in non sludgeforming concentration.

RALPH :r. GOODWIN.