US1921116A - Process of neutralization - Google Patents

Description

Aug. 8, 1933. CALDWELL PROCESS OF NEUTRALIZATION Filed April 25, 1930 1 VENTO Ly/e 6a/gwe/i BY ,(f M

ATfORNEY Patented Aug. 8, 1933 rnocass or NEUTRALIZATION Lyle Caldwell, Long Beach,-alif., assignor, by mesne assignments, to California First National Bank of Long Beach, Long Beach, Calif., a national banking association, as trustee Application April 25. 1930. Serial No. 447,275

19 Claims. (01. 196-j-41) This invention relates to improvements in a process for refining oils wherein acid treated oils may have their acidity neutralized.

The principal object of the invention is to provide a process of neutralization wherein an acidtreated oil is contacted with an alkaline compound of stable structure in the presence of water and capable offorming water soluble salts of the acid in the oil.

A further object of the invention is to contact a petroleum product, such as gasoline, pressure distillate, kerosene, lubricating oil or the like, which has been treated with an acid, such as sulphuric acid, hydrochloric, and/or the like,

115 with an alkaline mineral whereby water soluble sulphates, chlorides, or the like are formed on the surface of the mineral and then removed by washing the mineral with water.

In the. refining of oils, such as petroleum prodnets and animal or vegetable oils, it is customary,

in order to remove certain undesirable constituents, to subject the oil to a treatment with acid with agitation, whereby the undesired constituents combine with the acid and are removed therefrom in a form known as "sludge, which sludge, being heavier than the oil, will settle by gravity and may be then removed from the oil. However, in such acid treatments, the acid and acid reaction products become very finely divided, to the end that, after the sludge is withdrawn from the oil, certain acid particles are so dispersed as to render the oil acid. Further even than this many of the acid products are soluble in the hydrocarbon oil. Such acid may best be determined by shaking a known quantity of the oil in question with a known quantity of distilled water or other suitable liquid which is immiscible with the oil. The water or other suitable acid solvent is then separated from the oil and its acidity determined by suitable means. I prefer to express this acidity in terms of hydrogen ion concentration by means of the well known pH scale full details of which may be found in any standard reference work such as that of W. M. Clark, The Determination of Hydrogen Ions." As is well known a pH of 7 represents neutrality, relative degrees of acidity being represented by unit figures smaller than '7 and relative degrees of alkalinity by unit figures larger than 7. In other words. a pH 01 4 represents an acid condition, a pH of '7 represents neutrality and a pH of 9 represents a condition of alkalinity. The pH may be determined electrometrically or by indicators.

Therefore any neutralization effect should closely approach '1 on the above scale to obtain the best results.

Ah ordinary alkaline neutralizer is a solution of caustic soda which, when added to acid treated oil after sludge withdrawal, is capable of bringing the pH of the oil to approximately '7. After 7 the alkaline sludge is withdrawn, the oil must be washed with water and perhaps filtered through clay.

However, the use of caustic soda or other alkaline solutions presents difiiculties which are now overcome by this-invention, in addition to performing a desired neutralizing action, all of which can be done in a simple, quick, and highly economical fashion.

For instance, the use of caustic soda requires a procedure usually as follows:

(1) Preliminary washing of acid stock with water.

(2) Washing with caustic soda solution.

(3) Washing with water.

A certain amount of emulsification occurs in each stage of this treatment, and its separation, especially in continuous types of equipment, is a difiicult problem. Frequently the amount of 30 moisture or caustic in suspension with the settled oil or distillate will run as high as one percent and this must be removed by evaporation or by other equally difiicult methods. When there is such residual moisture in a caustic washed oil 35 and evaporation is resorted to, the salts and other impurities in the aqueous portion are deposited in the heating equipment as sediment and frequently as a troublesome scale. In other words, my process eliminates the necessity of excess water and consequently emulsions and the above mentioned difliculties are avoided.

Due to the fact that it is usually impossible to accurately estimate the exact amount .of acid to be neutralized, an excess of caustic is normally employed to be certain that all this acid is removed from the oil. This necessitates large quantities of caustic and as an example, to eflectively neutralize a distillate of approximately 44 BQgravity containing 1000-1300 mg. per liter of mo acid as H2804 it requires approximately 0.5 lb. of caustic soda per bbl. of distillate. Based on a price of 3 cents per lb. the material cost per bbl. of distillate would be 1.5 cents. Using my process and employing either brucite or caustic calcined magnesite for example, the material cost would be approximately 0.4 cents per bbl. for neutralizing this same distillate. g 4

This invention provides a desired neutralization and the elimination of the above described drawno Brucite MgO.HnO 6 to 6. 9 Magnesite M300; 4. 3 Hydro magnesite MgCOL3H O 6. .5 Dead burned magnesite MgO 4. 6 Caustic calcined magnesite MgO 6. 5 Calamine HzZNzSiOs 4. 4 Rhodochrosite M11001 3. 9

In general, while members of the above list give fair results, conditions of operation are that the material shall be insoluble (in a practical manner) in water and form an acid reaction compound which is relatively highly soluble in water.

Preferably brucite is most desirable for use in my process inasmuch as it is found in comparatively large bodies in nature, and has a strong physical structure, especially in the presence of water, yields highly water-soluble salts upon contact with acid and acid-reaction products, and then may have its surfaces easily washed free from reaction-products to give fresh surfaces for further contacting. Brucite is a naturally occurring magnesium compound identified mineralogically as MgO.HzO and being identified chemically as magnesium hydroxide (Mg(OH)2). The magnesium compounds generally are preferred, especially those of strong physical structure in the presence of water which indicates a low solubility in the .water, or substantial insolubility therein.

It is further to be noted that when, for example, where brucite is used, the soluble salt formed, in this case magnesium sulfate, crystallizes with 7 molecules of water of crystallization which is sufficient to remove from the system such traces of moisture as may be necessary to activate the original raw material.

As an illustration of an application of the invention the accompanying flow sheet and drawing show a mode of operation in which neutralization of acid oil is effected and in which washing of the brucite is accomplished for continuous operation.

A tank 10 contains an oil, such as a pressure distillate. which is supplied to an agitator 11 in which the oil is treated with say, ten pounds to the barrel of strong sulphuric acid supplied through pipe 12.

After a period of agitation, the sludge is permitted to settle and is withdrawn through a pipe 13 and the oil having a residual acidity of 1200 parts per million, more or less, may be passed through a filter 14 of the type, for instance, shown in United States Patent 1.739.898, Gard et al.. or through other filter aids such as diatomaceous earth, clay, or the like, or by centrifuging. Such filtering is not necessary but will reduce the acidity of the oil and thereby add to the efliciency of the neutralizing step.

The oil then is ready to be passed into the first of a plurality of neutralizing tanks 15 and 16 through a pipe 17, which tanks are filled to a predetermined depth with brucite, or equivalent material, through a removable top, or manholes (not shown), or in any well known manner.

Each of the tanks 15 and 16 is provided with a frusto-conical bottom holding a screen 18, a discharge pipe 19 for neutralized oil, an overflow pipe 20 for salts in solution, an upper fine mesh screen 21 of metal or cloth for holding the fines, an air pipe 22 for dislodging the fines from screen 21, and a steam or water pipe 23 below the lower screen 18.

The brucite is first crushed in lumps which may be one-half inch, more or less, in diameter, and, after being placed in the tanks, is moistened with water or steam introduced through pipe 23. The acid oil is now passed through pipe 17 into the lower part of tank 15 (tank 16 being cut out of the system) and percolates upwardly through the interstices of the brucite, thereby coming into an intimate and extended contact therewith.

The percolation results in the acid and acid reaction products being brought into contact with the contents of tank 15, whereby a more and more intimate contact of the acid particles with the brucite will follow. Likewise, in the subsequent washing the uppermost smallest particles will go into solution more readily and can be carried out of the tank without clogging the same.

Upon exhaustion of the reactive effects of the brucite in tank 15, which may be determined by the condition of samples taken from the try cook 34, valves 25 and 26 will be closed and valves 27 and 28 will be opened, whereby a continuous on-strcam flow of the acid distillate may be maintained through tank 16.

Valve 29 in discharge pipe 20 of tank 15 is now opened and hot water or steam and water is passed into tank 15 through pipe 23, whereby the sulphates, sulphonic, or other acid compounds, and any tarry or gummy compounds adsorbed on the surface of the brucite are dissolved or removed therefrom, the velocity of the water flow being regulated to remove such of the particles of the brucite as are too fine for eflicient percolation. At the same time a blast of air, water, or steam through pipe 22 will free the screen 21 from any fines for their removal by the water stream.

The fiow of Water is continued until a completely new reactive surface of the brucite is prepared for further use, when the brucite in tank 16 becomes exhausted, to maintain continuous operation. Steam, or air, may then be blown in at pipe 20 to remove excess water through pipe 23.

It is, of course, apparent that any number of tanks 15 may be employed and various equivalent neutralizing materials as well, but the general condition is that the material should be insoluble in water and form soluble salts upon reaction with acid compounds.

The system may be operated under superatmospheric temperatures and pressures, or a combina'tion thereof. This is desirable in the neutralization of acidtreated' lubricating oils, etc., where the viscosity of the cold stock interferes with efiicient percolation.

The process is applicable to oils having an acid reaction and in this respect is not limited to the neutralization of mineral oils containing inorganic acids, such as sulphuric or hydrochloric acids, or the like, but is effective for the neutralization of organic acids, such as sulphonic acids, lwdrochlorides, or the like, as well as the free fatty acids, or organic acids, from vegetable or animal oils, the magnesium, or other reaction compounds, being removable by hot water, steam, or other suitable solvent.

Relatively small quantities of water are necessary to eflectively carry out the reaction by moistening the brucite, or other equivalent material, and this use may be due to the necessity of ionizing the acids.

The water of crystallization formed by the reaction products is normally sumcient to remove this water from the finished product, but at times the neutralized product passing through line 19 may be filtered through clay, fullers earth, diatomaceous earth, or the like, to completely clarify and remove any traces of moisture in the treated oil.

The brucite, or other equivalent material, may be used to exhaustion and this is often desirable to be done, or substantially so, before tanks 15 and 16 are replenished.

The process herein described indicates a true chemical reaction wherein water solublesalts of acids are formed and must not be confused with known processes in which the contacting of acid oil with inert material allegedly causes the agglomeration of acid. particles by surface tension eflects. This distinction is best illustrated by the fact that any particular body of neutralizing material used in my process continually decreases in volume after each contact period and subsequent washing whereas the passage of acid oil through bodies of chemically inert materials, such as sand, leaves the volume of such material unchanged. In the magnesium compounds used, the solubilities of which, in water at from 15 C. to 25 C., are less than 1, magnesium sulphates are formed having a solubility in water at the same temperatures in excess of 25, whereas sand, for instance, is unreactive with sulphuric acid or its reaction products. It is, of course, obvious that the water necessary for moistening the material may be carried in the oil itself.

I claim as my invention:

1. A process of neutralization which comprises: contacting acid hydrocarbon oil with a, mineral containing MgO and moistened by aqueous fluid whereby soluble acid reaction products are formed, and removing such products by washing the mineral with water.

2. A process of neutralization which comprises: contacting acid hydrocarbon oil with a mineral containing MgO and moistened by aqueous fluid whereby water soluble acid reaction products are formed, and removing such products by washing the mineral with water.

3. A process of neutralization which comprises: passing a stream of acid hydrocarbon oil through a body of contact material containing MgO and an aqueous solution of magnesium hydroxide, and holding reaction products in aqueous solution while separating the hydrocarbons therefrom.

4. A process of neutralization which comprises: passing a stream of acid hydrocarbon oil through a body of contact material containing MgO and an aqueous solution of magnesium hydroxide, and holding reaction products in aqueous solution within said body while separating the hydrocarbons therefrom. I

5. A process of neutralization which comprises: passing a stream of aqueous fluid and a stream of acid hydrocarbon liquids in succession through bodies of material containing magnesium oxide.

6. In a process of neutralization the combination of steps which comprise: passing a stream of aqueous fluid and a stream of acid hydrocarbon liquids in succession through a body of material containing magnesium oxide.

7. A process of neutralization which comprises: contacting desludged acid hydrocarbon liquids with suilicient aqueous solution containing magnesium hydroxide in the presence of contact material to intimately mix said liquids and solution, and separating the hydrocarbons from said solution while both are in fluid form; the entire process being conducted at a substantially uniform temperature.

8. A process of neutralization which comprises: passing a stream of hydrocarbon liquids containing sulphuric acid, through a body of contact material containing MgO and coated with an aqueous solution containing magnesium hydroxide and magnesium sulphate, and separating the hydrocarbons from the solution without substantial increase of temperature in the solution while both are in fluid form.

9. A process of neutralization which comprises: passing a stream of hydrocarbon liquids containing sulphuric acid, through a body of contact material containing MgO and coated with an aqueous solution containing magnesium hydroxide and magnesium sulphate at superatmospheric temperature, and separating the hydrocarbons from the solution without substantial increase of temperature in the solution while both are in fluid form.

10. A process of neutralization which comprises: passing a stream of hydrocarbon liquids containing sulphuric acid, through a body of contact material containing MgO and coated with an aqueous solution containing magnesium hydroxide and magnesium sulphate at superatmospheric temperature and superatmospheric pressure, and separating the hydrocarbons from the solution without substantial increase .of temperature in the solution while both are in fluid form.

11. A process of neutralization which comprises: intermingling lnrdrocarbon liquids contalning acid with an aqueous solution of magnesium hydroxide, increasing the concentration of magnesium hydroxide in said solution by the addition thereto of a magnesium salt of said acid, and separating the hydrocarbons from said solution without substantial increase of temperature in said solution while both are in fluid form.

12. A process of neutralization which comprises: intermingling hydrocarbon oil containing acid with an aqueous solution of magnesium hydroxide, increasing the concentration of magnesium hydroxide in said solution by the addition thereto of a magnesium salt of said acid derived from said hydrocarbons, and separating the hydrocarbons from said solution without substantial increase of temperature in said solution while both are in fluid form.

13. A process of neutralization which comprises: contacting desludged acid liquid hydrocarbons with suilicient aqueous solution of magnesium hydroxide to neutralize said acid in the presence of contact material to intimately mix said liquids and solution, and separating the hydrocarbons from reaction products of neutralization while said products are maintained in aqueous solution.

14. A process of neutralization which comprises: contacting liquid hydrocarbons containing acid with a mineral containing not less than 40% mo in the presence of suflicient water to maintain a solution of ma ium acid reaction 1'7. A process of neutralization which comprises: passing a stream of aqueous fluid and a stream of acid hydrocarbon liquids in succession through a body of brucite.

18. A process of neutralization which comprises: passing a stream of aqueous fluid and a stream of acid hydrocarbon liquids in succession through bodies of brucite.

19. A process of neutralization which comprises: passing a stream of aqueous fluid and a stream of hydrocarbon liquids containing sulphuric acid in successionthrough a body of brucite.

LYLE CALDWELL.

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