US3224957A - Process of reducing deposition of deposits on heat exchange surfaces in petroleum refinery operations - Google Patents

Description

United States Patent PROCESS OF REDUCING DEPOSITION OF DE- POSITS ON HEAT EXCHANGE SURFACES IN PETROLEUM REFINERY OPERATIONS Eugene A. Kent, Naperville, IlL, assignor to Nalco Chemical Company, Chicago, 111., a corporation of Delaware No Drawing. Filed Jan. 12, 1962, Ser. No. 166,447 5 Claims. (Cl. 20848) This application is a continuation-in-part of my copending application, Serial No. 788,727, filed January 26, 1959, now abandoned.

This invention, in general, relates to a method of inhibiting deposition of organic substances on heated metal surfaces and has particular reference to the prevention of deposits on heated metal surfaces in heat exchangers or the like in the processing of petroleum hydrocarbons. One important aspect of the invention relates to the processing of petroleum hydrocarbon liquids under conditions of high temperatures and the prevention of organic deposits from said petroleum hydrocarbon liquids on heat exchange surfaces.

In the processing of hydrocarbon liquids, particularly petroleum hydrocarbon liquids, elevated temperatures are often used in many necessary and important production operations. To handle liquids at elevated temperatures, heat exchangers and like heating devices are employed to control the heat transfer from one operational step to another. When hydrocarbon liquids contact hot metal surfaces there is some tendency for the liquid to decompose or undergo a chemical reaction that manifests itself in the form of deposits. These deposits may be either coke-like, or they may be in the form of tenacious, soft, sticky sludges. In the first instance, the deposits maybe considered as pyrolytic decomposition products whereas in the second type they may be considered an oxidation products and/ or polymerizate compositions.

In either of the above cases the deposits tend to materially decrease the heat transfer capacity of the metal surfaces and, hence, increase operating expenses. These deposits also require additional efiort and time to remove and restore the equipment to its original operating efficiency.

There are many petroleum refinery operations which can be benefited by the reduction or prevention of the deposit tendencies of the particular petroleum liquid being treated. For example, the reduction or prevention of deposits in heat exchange equipment, such as preheaters, heat exchange apparatus and the like, is important in such petroleum refining operations as cracking, hydroforming, desulfurization, reforming, distillation, absorption, isomerization, thermal desalting and extraction, to name a few. Deposits have been observed to form on heat transfer surfaces at temperatures as low as about 225 F. and may be evidenced at temperatures as extreme as 800 F. and perhaps higher.

One of the most convenient ways of preventing or reducing high temperature organic deposits on heat exchange surfaces is to add a small amount of a deposit-inhibiting or anti-fouling chemical to the hydrocarbon liquid which tends to form high temperature deposits. It is, therefore, an object of the present invention to reduce or prevent the formation of high temperature carbonaceous deposits on heat exchange surfaces by chemical means.

Another object of the invention is to provide a chemical which when added to a hydrocarbon liquid will prevent the deposit-forming tendencies of said liquid when it contacts the exchange surfaces held at elevated temperatures.

In accomplishing these objects in accordance with the invention it has been found that new and improved results in inhibiting the formation of organic deposits from petroleum hydrocarbon liquids during the processing thereof at elevated temperatures, particularly at temperatures within the range of about 225 F. to 800 F., are obtained by adding, preferably by dissolving, in the hydrocarbon liquid a reaction product obtained by reacting at elevated temperatures in aliphatic polycarboxy acid, a monohydroxy, monocarboxylic aliphatic acid, a polyhydroxy, polycarboxylic aliphatic acid, a monohydroxy, polycarboxylic aliphatic acid, or a polyhydroxy, monocarboxylic acid, preferably citric acid, and tetiary-alkyl primary amines. The tertiary-alkyl primary amines have the formula:

it. the amine having 11-22 carbonsthe reaction being carried out with the removal of 0.5-3.0 mols of the water of reaction per mol of the citric acid. More specifically, the tertiary-alkyl primary amine constitutes a compound wherein R and R are lower alkyl groups, usually methyl groups, and R constitutes a long chain alkyl radical composed of 8 to 19 carbons. Tertiary-alkyl primary amines which have been found to be eminently suitable for the instant invention are Primene Sl-R and Primene JM-T. Primene 81-R is reported by its manufacturer to be composed of principally tertiary-alkyl primary amines having 11-14 carbons and has a molecular weight principally in the range of 171-213, a specific gravity at 25 C. of 0.813, a refractive index of 1.423 at 25 C., and a neutralization equivalent of 191. Primene JM-T is reported by the manufacturer to be composed of tertiary-alkyl pri- -mary amines having 18-22 carbons with a molecular weight principally in the range of 2694125, a specific gravity at 25 C. of 0.840, a refractive index of 25 C. of lt456, and a neutralization equivalent of 315. Of the two amines, Primene J M-T is preferred because the ultimate reaction products with citric acid have better oil solubility as compared with equivalent products made with Primene 81-R.

The primary constituent of Primene 81-R is reported to be The primary constituent of Primene JM-T is reported to be essentially the same structure of Primene 81-R, but with 22 carbons.

The acid reactants fall in two primary groups: (a) hydroxy aliphatic carboxylic acids having 1-3 carboxy groups and l-2 hydroxy groups with the general formula (HO) R(COOH) wherein R is a saturated aliphatic hydrocarbon radical with 1-4 carbons, and (b) polycarboxy saturated aliphatic acids with the general formula HOOCR -(COOH) where R is a saturated ether or hydrocarbon radical with 1-4 carbons. The hydroxy groups may be primary, secondary, or even tertiary hydroxy groups. The carboxy groups may be on either or both of the terminal carbons of the aliphatic chains of R or R and/or may be on intermediate carbons of the aliphatic chain of R or R Acids of the above character are citric acid, succinic acid, tricarballylic acid, lactic acid, tartaric acid, tartronic acid, malic acid, diglycollic acid, and the like.

The reaction products herein contemplated which are obtained with removal of less than 1.0 mol of water per mol of acid such as citric acid, i.e., 0.5 mol up to about 1.0 mol of water per mol of acid (especially around 0.5 to 0.8 mol of water removed), are less preferred from the viewpoint of universal applicability in the treatment of {a hydrocarbon liquids herein contemplated than the reaction products obtained with removal of about 1.0 to 3.0 mols of water per mol of acid. The former reaction products occasionally are insutliciently soluble in a particular hydrocarbon liquid to give them the optimum depositinhibiting or anti-fouling properties whereas the latter reaction products have a better overall solubility in the various kinds of liquid hydrocarbons herein contemplated to at least the extent of solubility sufficient to impart optimum deposit inhibition on heated metal surfaces in contact with the treated hydrocarbon liquid.

The reaction product which is most consistently successful in the reduction of tube deposits and improvement of filterability is the reaction product of 2-3 mols of the -tertiary-alkyl primary amines previously described with one mol of citric acid obtained in a reaction with the removal of 1.53 mols of water. The critic acid is preferably anhydrous, or at least substantially anhydrous.

The reaction products of the instant invention may be prepared by any of several methods. They may be reacted at atmospheric pressure or under vacuum without a solvent. Alternatively, a high boiling solvent may be employed to reduce the viscosity of the ultimate product and thus facilitate agitation and mixing of the reactants. The solvent in this case has a boiling point high enough that it is not distilled off to any appreciable extent during the reaction at the prevailing pressure.

Another method of preparation involves the use of a low boiling solvent, such as toluene, which forms an azeotropic mixture with the water of reaction. The distillate is refluxed and the water separated from the low boiling solvent before the latter is returned to the reaction mixture.

In all of the foregoing methods, the reactants are heated sufilciently high to distill off the water of reaction at the prevailing pressure conditions. In reactions at atmospheric pressure, the tertiary-alkyl primary amine and citric acid are mixed together in a vessel equipped with an agitator and heating means and heated to a temperature between about 110 C. and 160 C. for /2 to 2 /2 hours the time temperature relationship depending upon the amount of water of reaction to be removed. The heating of the reactants is terminated when the desired amount of water of reaction is removed-the latter being determined by collecting and measuring the water distilled off. An alternative method for determining the end-point involves ascertaining of the acid number of samples taken at periodic intervalsthe reaction being terminated when the approximate desired acid number is reached. In a preferred form of the invention, the reaction is terminated so as to obtain a product having an acid number, based on the active ingredients, in the range of 65-90, preferably 7585. One preferred method at atmospheric pressure involves heating the amine to a temperature of 50 C.60 C. and adding the citric acid slowly in increments. After all the citric acid is added the reactants are gradually heated to a temperature of 140 C.160 C. in a period of about one-half to one hour. The reaction mixture is held at this temperature for an additional 1. /2 to 2 /2 hours. If desired, the product may be diluted with a suitable hydrocarbon solvent such as heavy aromatic petroleum oils, i.e., at least 50% aromatics, or xylene to the desired concentration.

In a reaction under vacuum, the amine is vigorously stirred and the citric acid is added in portions. The mixture is then rapidly heated. When the temperature is in the range of 100120 C., a full vacuum is slowly applied. The reaction is kept at this temperature for about /z2 hours and is then cooled rapidly to 100 C. A suitable hydrocarbon solvent is then added in an amount suflicient to provide the required concentration.

When a high boiling solvent such as Stoddard Solvent or other commerical high boiling hydrocarbon solvent is employed, the amine and citric acid are mixed with the desired amount of solvent, and the mixture is heated with agitation in the manner previously described. The azeotropic distillation method is carried out by mixing the amine and citric acid with a low boiling solvent such as toluene in a reaction vessel equipped with an agitator, condenser, and Barrett trap for separating the water and solvent in the azeotropic distillate and the mixture is heated with agitation. The solvent begins to reflux, and refluxing is continued with the removal of water from the azeotropic distillate until the desired amount of water is removed.

The invention will be further understood from the following specific examples and it will be understood that the invention is not limited thereto.

EXAMPLE I Three mols of Primene JM-T and one mol of citric acid, along with 368 grams of Stoddard Solvent, are added to a reaction vessel equipped with an agitator, thermometer, Barrett trap and condenser. The mixture is heated until the temperature reaches C. at which point a vacuum is applied. Distillation begins, and about three milliliter of the solvent is distilled over and collected. The temperature of the reaction mixture continues to rise and at about 126 C., the distillation becomes more vigorous. The temperature remains constant thereafter at about 124-126 C. During the reaction period, the temperature rises to about C., and the reaction is stopped when 25.2 milliliters of water have distilled over. This amount of water is equivalent to 1.4 mols of water per mol of citric acid.

EXAMPLE II Primene JM-T and citric acid are reacted at a molar ratio of 3:1, respectively, in a vessel identical with that described in Example I. The reaction mixture is heated and agitated and at 120 C. a vacuum is applied. After a few minutes, distillation of the water begins. As the reaction proceeds, the reaction mixture begins to darken. Heating is continued until the temperature is in the range of 140l50 C. The reaction is continued until about 1.8 mols of water per mol of citric acid are removed. Thereafter the heating is discontinued and the reaction product is diluted with a suitable hydrocarbon solvent to the desired concentration.

EYAMPLE III Three mols of Primene JM-T are added to an open vessel, and the amine is heated to a temperature between 50 and 60 C. One mol of citric acid is added portionwise to the amine. After all of the acid is added, the temperature is raised and held within the range of C. The product begins to darken at this temperature and after 2 /2 hours, an acid number is taken and found to be about 85. The reaction is then stopped and the product was made up into a 75% solution in aromatic hydrocarbon solvent and filtered through a filter cell.

EXAMPLE IV Equal mols of Primene 8l-R and citric acid are mixed with an amount of toluene equal to about twice the total weight of the amine and acid in a reaction vessel identical with that described in Example I. The mixture is stirred and heated. At about 110 C., the toluene begins to reflux and when the water in the azeotropic distillate is removed the color of the reaction mixture changes from a light yellow to a dark brown as the reaction nears completion. After three hours of refluxing about 1.8 mols of water per mol of citric acid have been removed and no further distillation of water is noted. The temperature at this point is about 112 C. and the reaction is stopped.

EXAMPLE V In an apparatus identical with that of Example I, Primene 8lR and citric acid at a molar ratio of 3:1, respectively, are mixed with an amount of toluene aps proximately equal to the total weight of the amine and acid. The reaction mixture is heated and stirred. At about 110 C. the toluene begins to reflux and the water is removed from the azeotropic distillate. When one mol of water per mol of the acid is removed, the reaction is stopped-the temperature at this point being about 118 C.

EXAMPLE VI Four hundred fifty pounds of Primene 81-R is pumped into a stainless steel kettle equipped with stirrer, heater and cooling coils. The amine is heated to 215 F., and 150 lbs. of citric acid is added in four portions over a period of 15 minutes. The exothermic reaction causes the temperature to rise to about 270 F. in about /z hour. Cooling is applied to prevent further temperature rise, and the reaction mixture is held at 260270 F. for two hours and then cooled.

The products produced in accordance with the foregoing reactions are believed to be amine salts of the acid with a portion of the salt groups converted to amide groups by the elimination of water of reaction. Thus, the resultant product is believed to contain both amine salt groups and amide groups.

While the foregoing portion of the disclosure relates primarily to reaction products of citric acid, the preferred acid for purposes of my invention, other hydroxy-substituted, saturated aliphatic carboxylic acids or unsubstituted, saturated aliphatic polycarboxylic acids may be employed without departing from the spirit of the invention. Examples of such acids are succinic acid, tricarballylic acid, lactic acid, tartaric acid, tartronic acid, and rnalic acid. The foregoing acids, including citric acid, may be characterzed by the fact that the total of functional groups, hydroxy and/ or carboxy groups, is at least two and not more than four and that the acids have 36 carbons. In the case of dicarboxy or monocarboxy acids, the amount of tertiary-alkyl primary amine is reduced to two mols or one mol per mol of acid, respectively.

The anti-fouling additives, generally in diluted form in a hydrocarbon solvent, are added and mixed with the petroluem hydrocarbon liquid in amounts generally in the range of about 25-500 p.p.m., the concentration being calculated on the basis of the active ingredients. The quantity added for optimum results will vary between types of petroleum hydrocarbon liquids and temperatures to which they are subjected in the particular processing ope on- While the additives of the instant invention may be employed with some success in many diflerent types of petroleum hydrocarbon liquids, including crude oil, gas oil, heavy distillate oils, etc., they are most outstanding as anti-fouling agents and deposit inhibiting agents when used in light petroleum distillates such as naphthas, diesel oils, kerosene, light furnace oils and the like. In general, these latter petroleum hydrocarbon liquids have distillation end points beginning above that of gasoline up to petroleum hydrocarbon liquids having distillation end points at about 750 F. In the broad sense, the petroleum hydrocarbon liquids to which the present invention is applicable cover a range from the crude oil, including reduced crudes, to petroleum distillates, straight run or cracked, having distillation end points above the distillation end point of gasoline '(about 400 F.). In diesel oils, the additives of this invention are also beneficial in alleviating hot filter plugging and gumming of the diesel injector parts and other fuel handling parts of a diesel engine which become heated during the operation of the engine. A minimum concentration of about 75 p.p.m. of additive is advisable for this beneficial effect.

The following are formulations which may be added to petroleum hydrocarbon liquids for the purpose of inhibiting the deposit forming tendencies of these oils at elevated temperatures on heating surfaces.

6 Composition A Percent Reaction product of Primene JM-T and citric acid at a mol ratio of 3:1, 1.5 mol of water eliminated per mol of citric acid 75.5 Bronoco 365, an aromatic solvent 24.5

Composition B Reaction product of Primene 81-R and citric acid, mol ratio 3: 1, 0.5 mol of water eliminated per mol of citric acid 20 Heavy aromatic hydrocarbon solvent Composition C Reaction product of Primene 81R and citric acid (procedure of Example VI) 20 Bronoco 365 80 Composition D Reaction product of 3 mols of Primene 81-R and 1 mol of citric acid, 1 mol of water eliminated per mol of citric acid 20 Heavy aromatic solvent 80 Composition E Reaction product of 3 mols of Primene 81-R and 1 mol of citric acid, 2 mols of water eliminated per mol of citric acid 20 Heavy aromatic solvent 80 The above compositions were tested in an apparatus of laboratory size designed for determining the anti-fouling or deposit inhibiting tendencies of anti-fouling agents. In the test, the particular oil or petroleum hydrocarbon liquid being tested is preheated and aerated, if called for by test conditions, in a feed tank. Agitation is provided by an aerator or by a power driven mixer. A receiver or waste tank is pressurized with nitrogen to the desired test pressure by opening an automatic regulator until the correct pressure is obtained. The apparatus drain is opened and the receiver valve and bleed valve are closed. Temperature and pressure bypass switches are turned on, and the prepared feed is pumped into a heat exchange pipe in the form of a loop by means of the injection pump. The pump heater is turned on if the feed viscosity justifies its use.

When the feed flows continuously from the drain, that is without air bubbles, a recycle pump is turned on. For a high pressure test, the recycle pump is set at maximum speed in order to facilitate the removal of air from the recirculation loop, a welded stainless steel pipe, diameter inch in the high pressure apparatus. The loops in the low pressure apparatus is a 15", straight, black iron tube, 7 O.D., /2" I.D., with the remaining portion of the loop being A" pipe connected by fittings. When the flow of feed from the drain is once again continuous, the drain valve is closed, and the pressure in the apparatus builds up to the continued injection of fresh feed. When the pressure in the apparatus reaches the level established for the test, a receiver valve is opened rapidly. The nitrogen bleed valve on the waste tank is then cracked slightly to allow displacement of the nitrogen by the waste feed from the apparatus. A balance must be established between the nitrogen bleed rate and the incoming rates of nitrogen to the reciver plus the waste petroleum fluid so that a steady pressure is held throughout the test. Nitrogen is discharged from the waste tank at a rate in excess of the volume of fluid entering the tank. Constant pressure in the waste tank and heat exchange loop is maintained with an automatic regulating valve on the nitrogen supply pressure cylinder.

A recorder is turned and the safety bypass switches are turned off. The power to the heater, a Nichrome wire wound about the pipe and covered by insulation, is then turned on with the rate being established at the desired value by means of the voltmeter and ammeter readings and controlled by a powerstat. The rates are adjusted,

based on past experience with feeds of a similar nature, to give the desired oil temperature for the test. Water is circulated through a double pipe oil cooler for cooling the waste oil. At this point, the recycle pump in the high pressure test is gradually slowed down to a rate predetermined for the test,

An equilibrium or steady-rate condition is reached when the oil temperature levels off and does not rise or fall more than 3 degrees during a half-hour period. The time required to reach equilibrium is usually two hours but may be somewhat more or less in the case of naphthas. The oil and wall temperature differences are determined every half hour with thermocouples after equilibrium is established, and heat transfer coeflicients are calculated. The percentage drop in the heat transfer is then determined. The percentage drop for a blank run is used as the standard of comparison in the evaluation of additives used with the same hydrocarbon liquid in subsequent tests.

The results of tests with various petroleum hydrocar- '3 Polydodecylbenzene sulfonic acid is a mixture of diand higher dodecylbenzene sulfonic acids.

Composition G Percent 5 Solution in a hydrocarbon solvent of reaction product of 3 mols Primene 81-R and one mol citric acid, 2 mols water eliminated per mol citric acid, active component 50 Completely neutralized ethylene diamine salt of polydodecylbenzene sulfonic acid in hydrocarbon solvent, active component Composition H Solution in hydrocarbon solvent of the reaction product of 3 mols of Primene 81-R and 1 mol citric acid, 0.5 mol water eliminated per mol citric acid, 20% active component 50 Solution in hydrocarbon solvent of completely neutralized salt of ethylene diamine and polydodecylbon liquids are reported in the following table. benzene sulfonic acid, 45% active component 50 TABLE I Wall Temp, F. H.T.O. (U) B.t.u. Percent Percent Active Duration Oil Temp. Hr. Ft. F. Reduction Reduction Petroleum Liquid Treatment Cone, of Test, at Equil. F. in U. in Fouling p.p.m. Hrs. Rate Equil. End Equil. End

1. Gas Oil Blank 5 442 683 746 108 88 18.5 Comp. A- 225 5 448 691 711 110 101 8. 2 56 2. Gas 011 Blank 4 452 640 688 119 91 23 Comp. B 30 4 373 568 580 116 108 7 3. Gas 0il Blank".-. 5 470 808 872 83 69 17 Comp. A 150 5 471 790 813 88 81 8 53 4. Topped San .loaquine Crude Blank 5 460 616 655 180 139 23 Comp. A 150 5 467 632 659 170 143 15 8 31 5. Heavy-15% Coker Naphtha Blank 5 398 546 670 91 51 43 Comp. D- 34 5 404 548 576 94 79 15 65 Comp. E 34 5 398 540 583 79 16 63 Comp. A 34 5 408 540 549 102 99 4 92 nk 5 390 628 611 95 72 25 Comp. B 34 5 412 548 565 06 88 68 Comp. B 55 5 406 652 580 93 87 6 5 74 6. West Texas naphtha, Blank 8 490 611 670 233 152 35 Panhandle naphtha, C0mp.A 150 8 485 605 605 229 229 0 natural gasoline. 7. Virgin Naphtha Blank 6 395 486 543 209 140 33 Comp. A 150 6 398 490 524 207 167 19 43 8. Platinum Reformer lank 5 431 558 613 198 137 32 N aphtha. Comp. A" 150 5 437 542 550 246 217 12 62 Comp. E 150 5 441 540 542 254 249 2 94 9. Virgin Naphthat Blank 6 420 661 728 93 75 20 Comp. 13-- 26 6 430 666 682 95 93 2 5 88 10. Gas oil Blank" 5 442 683 746 108 88 18 5 5 452 684 684 115 100 11. Gas Oil 1 5 442 683 746 108 88 18 5 5 453 684 696 115 109 4 9 75 12. Reduced Crude 5 517 778 818 93 82 13 5 532 782 804 97 93 4 1 67 13. 85% Heavy-15% Coker 5 390 528 611 95 72 25 Naphthafl 5 409 560 560 94 94 100 m 150 p.s.i., 2 gal/hr. input, 1.7 ft./see. velocity, aerated. b 150 p.s.i., 1 gal/hr. input, 1.7 itJsec. velocity, nonaerated. 150 p.s.i., 2 gaL/hr. input, 1.7 it./sec. velocity, aerated. d 150 p.s.i., 2 gal/hr. input, 1.7 it./sec. velocity, aerated. 600 p.s.i., 1 gal/hr. input, 0.8 it./sec. velocity, aerated. f 600 p.s.i., 2 gal/hr. input, 2.2 ftJsec. velocity, aerated. I; 600 p.s.i., 2 gal/hr. input, 2.2 ft./sec. velocity, aerated.

h 600 p.s.i., 1 gaL/hr. input, 2.2 ft./sec. velocity, aerated. 600 p.s.i., 2 gal/hr. input, 0.8 it./sec. velocity, aerated.

i 150 p.s.i., l gal/hr. input, 1.4 it./sec. velocity, preheated to F., nonaerated.

Good anti-fouling results have also been noted with anti-fouling compositions comprising a mixture of the previously described tertiary primary alkyl amine-citric acid reaction products and aryl sulfonates or sulfonic acids, particularly alkyl-substituted benzene sulfonic acids and salts thereof such as amine salts.

The following are examples of such compositions:

Composition K Solution in hydrocarbon solvent of reaction product 3 mols Primene 81-R and 1 mol citric acid, 2 mols of water eliminated per mol citric acid, 20% active component 50 Solution in hydrocarbon solvent of completely neutralized ethylene diamine salt of polydodecylbenzene sulfonic acid, 45 active component 50 This combination of chemicals has been observed to 70 have good anti-fouling properties with several types of petroleum hydrocarbon liquids. Results of some tests using these compounds is reported in Table I, supra.

The weight ratio of activecomponents in the above mixture (the weight ratio of the tertiary-alkyl primary 5 aminecitric acid reaction product to the ethylene diamine- 9 polydodecylbenzene sulfonic acid salt) will ordinarily fall within the range of 4:1 to about 1:10 for most effective results. The active concentration of these two ingredients in the hydrocarbon liquid will ordinarily lie within the range of 10500 ppm.

The invention is hereby claimed as follows:

1. In the processing of normally liquid hydrocarbons of petroleum origin in a petroleum refinery operation, the step of passing said normally liquid hydrocarbon of petroleum origin during processing thereof in a petroleum refinery operation in contact with a heated surface in heat exchange relationship therewith, which liquid hydrocarbon contains a small but sufficient amount to inhibit formation of deposits by said liquid hydrocarbon on said heated surface of a reaction product prepared by heating with the removal of water of reaction citric acid and a tertiary-alkyl primary amine of the formula:

wherein R and R are lower alkyl groups and R is an alkyl group having 8-19 carbons, the molar ratio of amine to acid in the reaction mixture lying in the range of 13:l, respectively, until 0.5-3.0 mols of water of reaction per mol of citric acid are removed from the reaction mixture.

2. In the processing of normally liquid hydrocarbons of petroleum origin in a petroleum refinery operation, the steps comprising passing the normally liquid hydrocarbon of petroleum origin during processing thereof in a pctroleum refinery operation in contact with a heated surface in heat exchange relationship therewith, and adding to said liquid hydrocarbon prior to contact with said surface a small but suflicient amount to inhibit formation of deposits originating from said liquid hydrocarbon on said heated surface of a reaction product prepared by heating, with the removal of at least 0.5 mol of water of reaction per mol of an aliphatic acid containing at least two and not more than four functional groups selected from the group consisting of hydroxy and carboxy groups and having 3-6 carbons, a tertiary-alkyl primary amine of the formula:

R1 R -(J-NH and said aliphatic acid wherein R and R are lower alkyl groups and R is an alkyl group having 8-19 carbons, the molar ratio of amine to acid in the reaction mixture being in the range of 13 1, respectively.

3. The process of claim 2 wherein the acid is tricarballylic acid.

4. The process of claim 2 wherein the acid is tartaric acid.

5. The process of claim 2 wherein the acid is succinic acid.

References Cited by the Examiner UNITED STATES PATENTS 2,099,350 11/1937 Stoesser 20848 2,347,527 4/ 1944 Vanderbuilt 20848 2,387,501 10/ 1945 Dietrich.

2,493,715 1/ 1950 Christ 44-71 2,684,292 7/ 1954 Caron et al 4468 2,908,624 10/1959 Johnson et al. 20848 2,923,611 2/ 1960 Wieland 4472 3,035,907 5/1962 Halter 447l FOREIGN PATENTS 790,604 2/1958 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

Claims (1)

1. IN THE PROCESSING OF NORMALLY LIQUID HYDROCARBONS OF PETROLEUM ORIGIN IN A PETROLEUM REFINERY OPERATION, THE STEP OF PASSING SAID NORMALLY LIQUID HYDROCARBON OF PETROLEUM ORIGIN DURING PROCESSING THEREOF IN A PETROLEUM REFINERY OPERATION IN CONTACT WITH A HEATED SURFACE IN HEAT EXCHANGE RELATIONSHIP THEREWITH, WHICH LIQUJID HYUDROCARBON CONTAINS A SMALL BUT SUFFICIENT AMOUNT TO INHIBIT FORMATION OF DEPOSITS BY SAID LIQUID HYUDROCARBON ON SAID HEATED SURFACE OF A REACTION PRODUCT PREPARED BY HEATING WITH THE REMOVAL OF WATER OF REACTION CITRIC ACID AND A TERTIARY-ALKYL PRIMARY AMINE OF THE FORMULA: