US1938094A - Process for decolorizing hydrocarbon distillates - Google Patents

Description

Dec. 5, 1933.

S. E. CAMPBELL PROCESS FOR DECOLORIZING HYDROCARBON DISTILLATES Filed April 24, 1929 J&

Tan/r fig? (s a $2 2?" c r t r c r s a/My 44a 60a 4446 9a 65 INVENTOR Jamie/E far/pk Arm/m5 y Patented Dec. 5, 1933 erur PBGCESS F03 DECGLGRKZING HYDRO- CARBGN DHSTILLATES 5 Claims.

This invention relates to a process for decolorizing oils and particularly applicable to distillates derived from crude oils, such as petroleum, shale oil, and the like, in the refining thereof.

The principal object of th invention is to provide a process for decolorizi g distillates, which distillates will remain stabilized as to color after being subjected to the process.

A further object is to provide a process in which a minimum quantity oi acid is made available to decolorize a maximum quantity of distillate.

A further object is to provide process by which certain color forming compounds and other i1npurities are continuously removed from distillates in such form that they may be recovered as byproducts of value.

A further object is to provide a process by which gasoline, kerosene and/or other distillates are decolorized by the use of acid which is continucusly used until substantially exhausted in chemical reactions with the distillates and/ or impurities therein.

In my co-pending application Serial No. 349,606, filed Mar. 25, 1929, there is disclosed a process in which distiilates are decolorizcd and thereby stabilized as to color by the use of dilute acid, or a dilute acid solution, containing, for instance, less than 93.19% H2804, or less than concentrated sulphuric acid of 66 B. gravity.

The use of dilute acid, through which the distillate is passed, provides for the absorption by chemical reaction of color forming compounds contained in the distillates, such as nitrogenous and other bases, and provides that by the absorption of such bases in the dilute acid up to substantial exhaustion of the acid, the bases may be recovered in the form of by-products of value.

By reference to the drawing, which diagrammatically illustrates a how sheet of the process, a raw distillate, such as the gasoline fraction of crude petroleum, is supplied through a feed pipe 10 and valve 26 to a tower 11, comprising the first of a plurality of dilute acid towers 11, 11" and 11".

The plurality of towers 11, 11', 11", and 11 are connected in series through valve 27, pipe 14, valve 28, tower 11', valve 27, pipe 14', valve 28', tower 11", valve 27, pipe is", valve 28, tower 11", and valve 27" to discharge the acid treated gasoline in a continuous stream flow into pipe 15 initially.

The construction and function of each of the towers are alike and therefore a dsecription of tower 11 will apply to all.

Tower 11 is filled with acid resistant inert ma terial 12, adapted to provide large surface for corn tacting the distillate with the acid, and each tower is filled partially, to the line X-X, with a dilute acid solution through pipe 13 and valves 37, 37, 3'7 and 37", which acid solution is initially supplied i'rom an exterior source through a valve 13.

The acid solution may be any dilute acid solutlon, but preferably a dilute sulphuric acid solution is used one, for instance, less than 93.19% H2894, or about 50% H2804. The strength of the dilute acid solution, however, will vary with the nature or the hydrocarbon distillate under treatment to obtain the desired results.

Pipe 15 divided at a valve 34 to direct the distillate on one side to a. valve 33 and a by-pass manifold connected to towers 11, 11, 11" and 11 through valves 30, 30, 30", and 30 respectivezy, and on the other side of valve 34 is a. withdrawal by-pass manifold 35 which connects the pipe 15 with extensions of pipes 14, 14 and 14" through valves 31, 31' and 31" respectively.

The object of the by-passing of the stream flow or distillate around valve 34 is to be able to subject the distillate to acid treatment in the plurality of towers in rotation so that the acid in each tower is substantially exhausted, as will be further described.

A manifold 38 is connected to each tower 11, 11, 11 and 11" through valves 29, 29, 29" and 29" respectively for passing exhausted acid and reaction products to a storage tank 39 for further treatments.

By continuously flowing a stream of distillate from pipe 10 through the acid towers andconnections, as described, to pipe 15, ( valves 26, 26", 26", 29, 29', 29", 29", 30, 30, 30", 30', 37, 37', 3'7, 37", 31, 31', 31" and 33 being closed) the distillate is contacted with successive portions of a dilute acid solution in series relation, to the end that the color forming compounds comprising nitrogenous bases, and/or other basic impurities, in the distillate are absorbed in decreasing amounts in each tower in proportion as the stream is denuded of such compounds.

The denudation of the basic impurities in the distillate stream by such flow in series causes the dilute acid solution in tower 11 to become substantially exhausted by reaction with such impurities first, while in the last tower 11" the acid 105 solution will be substantially fresh, the amount and strength of acid in each tower being regulated to this end.

Upon the substantially complete exhaustion of the acid in tower 11, valves 26, 2'7, and 28 are 110 closed and valve 26' is opened to maintain the stream flow through the remaining towers 11, 11'' and 11 serially.

Valve 29 is now opened to withdraw the exhausted acid and reaction products through pipe 38 to tank 39, whereupon valve 29 is closed and valve 37 opened to refill tower 11 with fresh weak acid solution.

Valves 37 and 34 are then closed and valves 33, 30, 27 and 31 opened, whereby tower 11 becomes the last in the series and tower 11 the first in the series.

In this manner the plurality of towers are used in rotation to always provide that the stream of distillate shall be subject first to a partially spent acid solution, and last to a substantially fresh acid solution, whereby substantially all color forming and other basic impurities are removed by such treatment.

Not only does such treatment with a dilute acid solution insure the removal of the desired impurities, but such is in strong contrast to known treatments of distillates for the removal of such impurities by the use of concentrated acid, in which there may be as much as of the original strong acid drawn off in the acid sludge with the impurities and which is generally a total loss.

The dilute acid is substantially completely used up and the reaction products are in a form from which by-products of value may be recovered.

The stream of distillate thus treated with dilute acid solution is conveyed through pipe 15 to a settling tank 16, from which any acid carried over is removed through a pipe 17, the rate of throughput being so regulated that a minimum quantity of dilute acid is thus carried over.

From tank 16 the distillate passes through a pipe 18 and valve 40 to an alkali tower 19 which has previously been partially filled by the line Y-Y with a relatively strong alkaline solution, for example, a solution of caustic soda, valves 43 and 49 being closed.

Such solution may be, for instance, a solution containing 30% of sodium hydroxide, or other equivalent alkali, which absorbs the acidic impurities in the acid treated distillate with avidity, to the end that the solution absorbs about an equal volume of acidic impurities, or more, 'depending on the nature of the hydrocarbon material being treated, before becoming exhausted.

Weaker solutions may be used, as well as solutions of potassium hydroxide, or sodium plumbite, but a strong alkaline solution is advantageous to confine the alkaline treatment to a single passage through the alkaline solution, whereby the maximum amount of acidic impurities may be concentrated therein in comparatively small volume and less frequent renewal of the alkaline solution will be required.

However, for convenience, two or more towers 19 and 19' are provided in series, primarily to maintain continuous operation and secondly if it is desired to use dilute alkali solutions. In the latter case, a plurality of alkali towers may be arranged in series relation to be used in rotation as already described for the dilute acid towers.

Tower 19 may thus be connected through pipe 21 and valves 41 and 40 to tower 19', likewise partly filled with caustic soda solution, the distillate passing thence through pipe 42 and valve 41' to a settling tank 22, from which any caustic soda carried over may be withdrawn through a pipe 43.

Thus, in operation, the acid treated distillate is passed through a plurality oi towers contain ing relatively strong caustic soda solutions, in the first of which substantially all impurities of an acid nature are absorbed and the neutralization of any free acid is effected, the second tower, in the use of strong alkali, merely assuring that no acidic compounds remain in the distillate.

The passage of distillate through tower 19 continues until the caustic soda therein becomes substantially completely exhausted by reaction with acidic impurities, which include such compounds as phenols, cresols, and the like, and/or naphthenic acids and the like whereupon the stream flow of distillates is continued by closing valves 40 and 41 and opening valve 43.

The caustic solution in tower 19 being substantially fresh, insures the continuous removal of acidic impurities as previously described for tower 19.

Valve 44 is now opened and the exhausted caustic solution and reaction products are removed therethrough to line 45 and storage tank 46, whence they may be withdrawn through pipe 47 and the acidic impurities recovered as byproducts of value in many ways.

Valve 44 is now closed and valve 48 opened to partly refill tower 19 with fresh caustic solution through a supply pipe 20 to be ready for use upon exhaustion of the caustic solution in tower 19, at which time valves 43, 40, and 41 are closed and valves 49, 41, and a valve 49 in a by-pass line 50 are opened, to permit the recharging of tower 19' with fresh alkali solution.

By the steps of the process thus described, the selective treatment of a stream of distillate is provided to first remove basic impurities, and then remove acidic impurities, in a continuous manner in which the acid and alkali used are The nitrogenous bases and other basic 1m purities removed by the dilute acid treatment and collected in tank 39 may be recovered by a treatment such as is described in United States Patent No. 1,636,136, the strength of the dilute acid solutions employed being such as to convert the basic compounds into sulphates without material polymerization, or without reacting materially on acidic impurities to change, or possibly destroy, such as are desired to be collected in the alkali treatment for recovery as products of value.

Such change, or destruction, may be accomplished by the use of concentrated acid in towers 11, 11', 11 and 11" when treating a distillate such as gasoline.

The distillate, after acid and alkali treatmerits, in settling tank 22 may still contain cerof dilute acid towers ll, 11, 11'', and 11", t0

be used in rotation whereby the distillate is first contacted with partially spent concentrated acid and lastly with substantially fresh concentrated acid, to the end that all the concentrated acid is substantially saturated with impurities, or exhausted.

The concentrated acid preferably used is a strong sulphuric acid in the neighborhood of 66 B. gravity and, inasmuch as the mode of operation of the strong acid towers is like that already described for the weak acid towers, a description of such involves needless repetition to one skilled in the art.

However, the function of the concentrated acid treatment and the results achieved thereby comprise an important step in my process.

While concentrated acid decolorizes a distillate to the required color, in ordinary acid and alkali treatments of distillate, it is known that up to 80% of the concentrated acid is withdrawn in the acid sludge with the reaction products and is only recoverable with difficulty.

Likewise, on treating a distillate primarily with concentrated acid, the oxidizing and other chemical effects thereof may change the basic impurities into compounds which are too complex to recover in appreciable quantities, inasmuch as such compounds are in a form not susceptible of easy recovery.

Presumably, also, certain of the hydrocarbon compounds are oxidized by concentrated acid treatment, forming complex reaction mixtures, and are withdrawn in the body of the exhausted concentrated acid.

The further objects of my invention by the succeeding enumerated steps include the recovery of hydrocarbons oxidized by concentrated acid in a plurality of treatments whereby the concentrated acid is substantially exhausted, the elimination of substantially all concentrated acid losses, the use of a dilute acid recovered from the concentrated acid treatment, and the final decolorization of the distillate treated to a color of 30+ on the Saybolt colorimeter and the stabilization of the color of the distillate.

To these ends the partially decolorized distillate is passed by pipes 51 and 10a through the towers 11a, 11b, 11c, and 11d, wherein it is subjected to the action of concentrated acid, whereby it is finally cleared of the remaining chromogenic substances to gain its color and brilliancy and whereby certain hydrocarbon sulphates are formed by the chemical action of the concentrated acid.

Upon exhaustion of the concentrated acid in any of the towers 11a, 11b, 11c, and 11d, the reaction products are withdrawn through line 38a to a storage tank 39a. The treated distillate passes through pipe 15a to a settling tank 16a or to other suitable means of separating acid and distillate, whence any concentrated acid carried over is withdrawn through a pipe 171:.

From settling tank 16a the distillate passes through a pipe 18a to neutralizing tanks 19a and 191) containing a suitable alkaline solution of sufiioient strength to take care of any acidity in the distillate and thence through a pipe 42a to a wash tank 56 to which water is supplied through a line 57, whereby any alkali is removed and withdrawn through pipe 58.

The distillate thus purified, decolorized, and brilliant, after removal of water, passes from wash tank 56 through line 59 to storage or other uses.

The exhausted alkali may be withdrawn from either of the towers 19a, or 19b through a line 45a to a storage tank 4641, from which tank it may be taken through a pipe 47a for any desired purpose.

The exhausted concentrated acid, together with reaction products thereof, in the tank 39a is fed in predetermined quantities through a line 60 to a chamber 61 filled with water from pipe 5'7 and valve 62 to a predetermined level.

Chamber 61 generally may be of a well known type containing agitating mechanism and having the temperature of its contents controlled by a series of coils 63 through which a refrigerating medium is passed. Coils 63 may be located externally, or internally, of chamber 61, or both.

The temperature of the mixture in chamber 61 is thus controlled to be maintained at any desired degree. In the present case a temperature of about 33 F. is sufficient, with agitation, to hydrolyze the reaction products resulting from the concentrated acid treatment, to the end that certain compounds of value are formed.

Alcoholic, or other derivatives of hydrolysis may be withdrawn from chamber 61 through valve 64 while the acid released is in such form and strength as to be available for use in the weak acid towers 11, 11', 11", and 1", and such is therefore passed, as required, through a valve 65 and pipe 66 to the weak acid charging line 13.

In this manner the further treatment of the distillate by concentrated acid not only completes the decolorization, with stabilization, of the distillate, but by the further action of hydrolysis of the spent acid, by-products of value are recovered, together with weak acid for reuse in the initial step.

While these novel results are obtained, it must not be overlooked that the waste of concentrated acid, as normally used, is substantially eliminated.

The process as described is particularly adaptable to a distillate such as the straight run gasoline obtained from a California crude oil. However, I do not limit myself to treating such fractions, as kerosenes and the gasoline fractions from cracked oils may likewise be treated to advantage, the main difference being in the strength of acid used.

Or the treatment of different fractions may be undertaken. For instance, the gasoline fraction from a straight run crude oil may be passed into the dilute acid system through pipe 10 and after passing through the treatment as described, may be withdrawn through a line 53 to a filter 6''! containing an adsorbent earth, such as fullers earth, and thence through a pipe 54 to storage or use.

The action of the fullers earth is to remove certain chromogenic compounds unaffected by the dilute acid or alkali treatment, which cause turbidity, and to thereby impart the desired brilliancy to the finished product, decolorized and stabilized in color.

At the same time a kerosene fraction may be run into the concentrated acid towers through valve 55 and line 10a, wherein it is brought to the desired color.

Such combination of treatments is often desired, because kerosene requires as a rule stronger or a greater quantity of acid for effective treatment than gasoline, but, by processes heretofore known, the waste of concentrated acid in the acid sludge is very high and this waste I am now enabled to materially reduce and at the same time use the recovered dilute acid in a concurrent step treating gasoline.

The process is equally effective for fractions obtained from cracked oils, in which case it is desirable to apply cooling apparatus to the acid towers to control the exothermic heat of reaction, there being this difference between the fractions from straight run crude oil and from cracked oils, that there is but slight rise in temperature when treating the fractions from straight run crude oils.

I claim as my invention:

1. A process for decolorizing distillates which comprises: passing a stream of hydrocarbon distillate through a dilute sulphuric acid solution in the presence of contact material and an alkaline solution in succession then through a plurality of chambers containing contact material and concentrated sulphuric acid and arranged in series relation, continuing the passage of distillate until the concentrated sulphuric acid is substantially exhausted in the chambers in rotation, removing the exhausted concentrated sulphuric acid and reaction products from successive chambers, and finally treating the exhausted concentrated sulphuric acid and reaction products with water to obtain said dilute sulphuric acid solution.

2. A process for decolorizing distillates which comprises: passing a stream of hydrocarbon distillate through a dilute sulphuric acid solution in the presence of contact material and an alkaline solution in succession then through a plurality of chambers containing contact material and concentrated sulphuric acid and arranged in series relation, continuing the passage of distillate until the concentrated sulphuric acid is substantially exhausted in the chambers in rotation, removing the exhausted concentrated sulphuric acid and reaction products from successive chambers, and finally treating the exhausted concentrated sulphuric acid and reaction products with Water at a low temperature to obtain said dilute sulphuric acid solution.

3. A process for decolorizing distillates which comprises: passing a stream of hydrocarbon distillate through a dilute sulphuric acid solution in the presence of contact material and an alkaline solution in succession then through a plurality of chambers containing contact material and concentrated sulphuric acid and arranged in series relation, continuing the passage of distillate until the concentrated sulphuric acid is substantially exhausted in the chambers in rotation, removing the exhausted concentrated sulphuric acid and reaction products from successive chambers, and finally treating the exhausted concentrated sulphuric acid and reaction products with water at about 33 F. to obtain said dilute sulphuric acid solution.

4. A process for decolorizing distillates which comprises: passing a stream of hydrocarbon distillate through a dilute sulphuric acid solution in the presence of contact material and an alkaline solution in succession then through a plurality of chambers containing contact material and concentrated sulphuric acid and arranged in series relation, continuing the passage of distillate until the concentrated sulphuric acid is substantially exhausted in the chambers in rotation, removing the exhausted concentrated sulphuric acid and reaction products from successive chambers, and finally treating the exhausted concentrated sulphuric acid and reaction products to obtain said dilute sulphuric acid solution and alcoholic derivatives of the distillate.

5. A process for decolorizing distillates which comprises: passing a stream of hydrocarbon distillate through a dilute sulphuric acid solution in the presence of contact material and an alkaline solution in succession, then through a plurality of chambers containing contact material and concentrated sulphuric acid and arranged in series relation, continuing the passage of distillate until the concentrated sulphuric acid is substantially exhausted in the chambers in rotation, removing the exhausted concentrated sulphuric acid and reaction products from successive chambers, and finally treating the exhausted concentrated sulphuric acid and reaction products to obtain said dilute sulphuric acid solution.

SUMNER E. CAMPBELL.

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