US3594137A - Crude oil containing dispersant useful as diesel engine fuel - Google Patents

Abstract

SYNTHETIC OR NATURAL CRUDE OILS OF LOW INORGANIC SALTS AND LOW SULFUR CONTENT MAY BE USED AS FUELS FOR OPERATING HEAVY DUTY DIESEL ENGINES WHERE THESE CRUDE OILS CONTAIN AT LEAST 0.01 AND UP TO ABOUT 2.0 WT. PERCENT, OR AT LEAST A SUFFICIENT AMOUN ABOVE 0.01 WT. PERCENT TO APPRECIABLY MINIMIZE OR PREVENT CARBON DEPOSITION IN AND ON THE FUEL INJECTORS, OF AT LEAST ONE OVERBASED ALKALINE EARTH METAL SULFONATE AND/OR THE CONDESATION PRODUCT OF AN ALKYLENE POLYAMINE WITH ORGANIC MONO OR DICARBOXYLIC ACIDS OR ANHYDRIDES THEREOF, WHEREIN THE ACIDS OR ANHYDRIDES HAVE SUBSTITUTED THEREIN A LONG CHAIN ALKENYL GROUP OF C40-C250, EITHER OR BOTH ADDITIVES BEING USED AS DISPERSANTS. SULFUR CONTENT OF THE CRUDE OIL SHOULD BE BELOW ABOUT 1.0 WT. PERCENT AND SALT CONTENTS SHOULD BE BELOW ABOUT 3 POUNDS PER THOUSAND BARRELS OF CRUDE OIL. THE CRUDE OIL MAY BE OF PARAFFINIC, ASPHALTIC OR MIXED TYPE.

Description

United States Patent CRUDE OIL CONTAINING DISPERSANT USEFUL AS DIESEL ENGINE FUEL Thorkild F. Lonstrup, Sarnia, Ontario, Canada, assignor to Esso Research and Engineering Company No Drawing. Filed Nov. 27, 1968, Ser. No. 779,598

Int. Cl. C101 1/22, 1/24, 1/32 U.S. CI. 44-51 Claims ABSTRACT OF THE DISCLOSURE Synthetic or natural crude oils of low inorganic salts and low sulfur content may be used as fuels for operating heavy duty diesel engines where these crude oils contain at least 0.01 and up to about 2.0 wt. percent, or at least a sufiicient amount above 0.01 wt. percent to appreciably minimize or prevent carbon deposition in and on the fuel injectors, of at least one overbased alkaline earth metal sulfonate and/ or the condensation product of an alkylene polyamine with organic mono or dicarboxylic acids or anhydrides thereof, wherein the acids or anhydrides have substituted therein a long chain alkenyl group of C -C either or both additives being'used as dispersants. Sulfur content of the crude oil should be below about 1.0 wt. percent and salt contents should be below about 3 pounds per thousand barrels of crude oil. The crude oil may be of paraffinic, asphaltic or mixed type.

The present invention relates to the use as fuels, for operating heavy duty diesel engines, of low sulfur and low salt content, synthetic or natural crude oils and to the discovery that such types of crude oils may be used as such if one or more dispersants such as overbased alkaline earth metal sulfonates and/or condensation products of an alkylene polyamine with organic mono or dicarboxylic acids or their anhydrides, containing a long chain alkenyl group, are added in significant amounts.

Attempts have been made in the past to employ crude oils as fuels for heavy duty diesel engines. The incentive for such attempts has been one of economy, for if this could be accomplished, satisfactorily, the economics would be tremendously attractive. Unfortunately, such attempts in the past have shown very poor results for the reasons, inter alia, that extensive corrosion problems and the formation of high carbonaceous deposits in the engines adversely affect the operation of the fuel injectors and the engines, in general. It was found, additionally, that the consumption of fuel was excessively high when compared to the use of conventional diesel fuels and, more importantly, the attempted use of such crude oils, directly as diesel fuels, gave a diesel lubricating oil useful life of the order of 10,000 miles when used in a railroad diesel engine 'vs. an oil life in excess of 50,000 miles when conventional diesel fuel was used. British Pat. 1,124,611 discloses a conventional diesel fuel containing an ashless disperant and an alkyl nitrate. The principal reason for the short life of the diesel lubricating oil was that excessive sludge and soot deposits accumulated in the oil which deposition was not possible to remove by means of the customary oil filters used in connection with the operation of heavy duty diesel engines.

It was subsequently discovered that the reason for the excessive corrosion and the excessive carbon deposition pertaining to the fuel injectors and lack of general engine cleanliness was brought about largely through the fact that the crude oils employed contained excessive amounts of inorganic salts and excessive amounts of elemental sulfur and sulfur compounds which are naturally occurring in many crude oils produced throughout the world.

Patented July 20., 1971 The effective removal of excessive inorganic salts from crude oils is a conventional process which has been practiced for many years and it was discovered that where the natural crude oils or for that matter, the synthetic crude oils contained more than about three pounds of inorganic salts per thousand barrels of oil, it was necessary to process the oils to bring the amount of inorganic salts below this figure in order for the crude oils to be satisfactorily employed as diesel fuels. The desalting techniques for crude oils are well known as shown by representative U.S. Pats. 2,074,183 and 2,140,574. The desalting of crude oils as before stated is conventional and well known. Essentially, and in its simplest form, crude oil is desalted by adding limited amounts of water to the crude, heating the crude oil under pressure to avoid loss of low boiling constituents, gently stirring the same to avoid emulsion formation and allowing the salts to settle. Decantation, centrifugation or filtering may then be employed to separate the salts from the crude oil and, of course, the remaining water containing the dissolved salts is separated in conventional manner, as for example, by further settling and decantation. "In general, the desalting operation involves washing the salts from the oil under such conditions that rapid separation of the water solution from the oil together with undissolved inorganic salts, as solids, can be effectively carried out.

It was also discovered that excessive amounts of sulfur and sulfur compounds, again naturally occurring in many crude oils as produced throughout the world, caused deleterious effects in the operation and maintenance of heavy duty diesel engines. It was, therefore, found necessary in order to successfully use natural and synthetic crude oils as diesel fuels, additionally, to desulfurize or sweeten these crude oils to the point where the sulfur content, both free and chemically combined, was less than 1.0 wt. percent. Here again, the process of sweetening or desulfurizing oils is conventional and has been known for many years. Many different methods are presently employed in modern refinery practice to accomplish the removal of elemental and chemically combined sulfur from crude oils as they are produced throughout the world. Representative U.S. patents showing such sweetening processes are U.S. Pat. Nos. 607,017; 620,882; 1,654,581; and 1,608,399. The conventional desalting and sweetening operations form no part of the present invention except in so far as such processes are required, when the crude oils require it, in order to reduce such crude oils as possess too high an amount of inorganic salts, sulfur and sulfur compounds must be reduced to below the upper limits hereinbefore defined.

The types of crude oils that may be employed are many and varied, and as a practical matter, constitute all types of crude oils produced throughout the world. These may be of paraffinic, asphaltic, or mixed type e.g. mixed paraffinic and asphaltic components. It is preferred, however, to employ the paraffiuic and mixed type crudes and more especially it has been found that crude oils containing appreciable amounts of aromatic, and to some extent, crude containing appreciable amounts of naphthenic constituents are less desirable than are the parafiinic, mixed crudes, and asphaltic crudes. In general, the crude oils, treated or untreated, which meet the above defined sulfur and salt specifications are suitable for direct use in undiluted or unaltered form if they have an API gravity of between about 25 and about 45 measured at 60 F. and if they have a viscosity of between about 35 and about 250 SUS at F. In using the higher viscosity oils, preheating of the oil is oftentimes employed to lower its viscosity for ease of injection. In general, these crudes will have distillation boiling ranges between about and about 1100 F. Many crudes will have a far narrower boiling range particularly the synthetic crude oils, a typical one being one having a final end point distillation of below 700 F. Conventional diesel fuels have a distillation range between about 350 and about 650 F. but naturally, the crude oils will have appreciable amounts of components boiling below 350 F. and above 650 F. This does not adversely affect the operation of diesel engines. Typical specific crudes which may be employed are desalted Pembina crude from Canada, synthetic crude preparated from Athabasca tar sands of Canada, wherein a hydrogenation of the virgin and delayed coker gas oils is carried out. This last named material is light in color and resembles a distillate fuel and is only slightly higher in its final boiling point than that of conventional diesel fuels although it contains an appreciable front end boiling point slightly higher than that of conventional diesel fuel. Another synthetic type crude oil is that obtained and recovered from the distillation of oil containing shales. This material has an initial boiling point of about 430 F. and a final boiling point of about 1050 R, an API gravity of 19 at 60 F. and a viscosity of 200 SUS at 100 F. Other specific types of crudes which are advantageously employed are those from the Leduc field in Western Canada, the parafifinic crudes of Pennsylvania and the Middle East, the mixed base crude oils of the Mid Continent and the Asphalt base crudes of the Gulf Coast and California.

The desalted and sweetened crude oils above discussed were tried as fuels for marine and railroad heavy duty diesel engines without any further treatments but they did not perform too well in overall merit for the reason that it was found that still with these pretreatments, unsatisfactory used diesel lubricating oil life resulted and heavy fouling of the fuel injectors occurred so much so that in the earliest test, in laboratory engines, it was necessary to change fuel injectors about every 20 hours in order to avoid excessive injector fouling and in order to eliminate injector fouling as a variable. The used oil life Was relatively short. The heavy sludge and fuel soot was deposited in the lubricating oil which depositions were effectively removed by the oil filters. Additionally, the used oil clearly showed the result of the injector fouling because it had as much as a 41% viscosity increase coupled with the aforementioned additional disadvantages. It was found that a most successful operation of these heavy duty diesel engines, from an overall performance standpoint, could be accomplished if the injectors could be maintained relatively clear and free of carbonaceous deposits and if they could, of course, be free of injector corrosion. Surprisingly, the incorporation into the crude oil diesel fuel, of relatively small amounts of either an ash forming dispersant or an ashless dispersant, or both types, gave a surprising effect as to reduced fuel consumption, piston cleanliness, improved lubricating oil life, injector cleanliness, and overall freedom from complications in the operations and maintenance of such heavy duty diesel engines comparable to that attainable using conventional and regular diesel fuel. The major effect seems to be that improved fuel injector performance brought about all of the other improved conditions and the use of these dispersants to the crude oil seems to make it possible to maintain a good injector condition during extended operation of the heavy duty diesel engines.

The overbased alkaline earth metal sulfonates were found to be particularly effective when used in amounts ranging between about 0.01 and about 2.0 wt. percent. Similar amounts of the condensation products of alkylene polyamines with organic mono or dicarboxylic acids or anhydrides thereof wherein a long chain alkenyl group of C -C was attached to the organic nucleus of the carboxylic acid or anhydride accomplished these unexpected results. Again, the last mentioned type of ashless dispersant was useful in amounts ranging between about 0.01 and about 2.0 wt. percent. When a sulfonate was used by itself or as an admixture with the condensation product in a total amount as above specified, excellent results in engine performance were achieved. Larger amounts of either one or both types of dispersants can also be employed with equally excellent diesel engine operating results being achieved but no proportional improvement is obtained by using larger amounts and it merely adds to the expense of the diesel fuel. All that is necessary is that at least 0.01 wt. percent of dispersant or dispersants be used and at least a sufficiently large quantity of either or both types be used to accomplish an appreciable reduction of carbonaceous deposits in and on the fuel injectors of the diesel engine, for surprisingly enough, it has now been discovered that the key to the problem of maintaining diesel engine performance and of avoiding the deterioration of diesel lubricants is directly dependent upon the maintenance of relatively non-corroded fuel injectors. Piston cleanliness and improved lubricating oil life result from the taking advantage of this one important discovery. Furthermore, the use of one or more types of dispersants effectively achieve the maintenance of relatively carbon free fuel injectors.

The overbased alkaline earth metal sulfonates may be natural sulfonates such as the petnoleum sulfonates or mahogany sulfonates or they may be synthetic sulfonates such as long chain alkyl substituted benzene sulfonates. These overbased sulfonates generally have a total base number (TBN) ranging between about 50 and about or even higher, as desired. They are prepared by conventional processes well known to the art and are standard articles of commerce on the open market. Typical disclosures of their production and use are shown in US. Patent Nos. 2,839,470; 2,856,360 and 3,057,896. In general, the calcium and barium overbased sulfonates are used, preferably in the instant invention barium sulfonates are employed. British Pat. 782,058 shows a particular method of preparing the overbased sulfonates which finds widespread utility. The alkyl radical attached to the benzene nucleus in the synthetic sulfonates is usually a paraffinic radical or Wax alkylated substituent on the benzene ring. Alkenyl radicals may be attached to the benzene ring as well. These are prepared by the polymerization of ethylene, propylene, isobutylene or normal butenes, as disclosed in the various patents mentioned.

The condensation product of the alkylene polyamines with the various long chain alkenyl substituted carboxylic acids and anhydrides are also well known and are conventionally prepared by previously disclosed processes. These products are also sold commercially on the open market. They are principally used, as are the previously discussed sulfonates, as dispersants for automotive lubricating oils. Typical patents which disclose the preparation of these materials and their uses are US. Patent Nos. 3,172,892 and 3,219,666, which largely deal with the preparation of the long chain alkenyl substituted carboxylic acid condensation products of polyalkylene polyamines wherein the alkenyl group is a polymer of ethylene, propylene, isobutylene or a normal butene and contains from 40-250 carbon atoms per radical. Typically, British Pat. 1,075,121 discloses the same type of compounds except that a monocarboxylic acid, instead of a dicarboxylic acid, or its anhydride is employed to produce dispersants analogous to those disclosed in the aforementioned two US. patents.

In the test data appearing in the table hereinafter set forth, the ashless dispersant employed was a polyisobutenyl propionic acid condensation product of tetraethylenepentamine having a number average molecular weight of about 2000 and the ash forming dispersant employed was the barium sulfonate of polypropylene substituted benzene, having a TBN of about 59, in a light lubricating oil with an active ingredient concentration of about 45 to about 48 wt. percent. The barium content was about 14.9% barium and about /2 of this barium was colloidal barium carbonate.

The data obtained as a result of comparative diesel engine test runs are shown in the following table. The test carried out involved the use of a Buda single cylinder diesel engine Model B -BD38. Each test was carried out for a period of 200 hours at an engine speed of about 1500 rpm. The injector timing was set at 17.5 BTDC (before top dead center), the power output was about 6.0 brake horsepower, the crankcase lubricating oil temperature was maintained at about 240 F .:2 F., and the water jacket temperature was maintained at about 190 Hi2 F. The exhaust gas temperature varied between about 800" and about 850 F. The oil pressure was at 33 pounds per square inch and the air intake pressure at about 3 pounds per square inch.

In the following table, three types of fuels were employed and were each used Without benefit of additives in the diesel engine runs. The table shows the inspections for each of the three fuels, namely, conventional diesel fuel, desalted Pembina crude, and a synthetic crude oil derived from Athabasca tar sands which was prepared by hydrogenation of virgin and delayed coker gas oil fractions therefrom.

TABLE I Conven- Desalted tion Pembina Synthetic diesel fuel crude crude Gravity, API 60 F 3s. 6 37. 4 42. 4 Sulfur, wt. percent. 0.4 0. 26 0.07 Viscosity, SUS 100 F 36. I 41. 0 45. 0 Salts, lbs/1,000 bbl 0 2. o o Distillation (ASTM D-1160-61) (Atm. equiv. temp.):

A B C D E F G Fuel use, lbs./200 hrs.

(relative 100 109 107 96 111 104 100 Additive, wt. percent:

Ashless dispersant 0.5 0.25 0.05 0.05 Ash-forming dispersant 0.25 0.05 0.05 Injectors replaced, No 0 3 0 0 1 0 0 Carbon deposit, gins. 0.10 2.81 0.13 0.40 0.81 0.3 Used oil, percent:

Visc.increase@100 F..- 8.0 28.0 21.0 6.0 10.0 0.0 0.0 Pentane insol 0.5 2.6 2.4 0.2 0.8 0.7 1.9

l The condensation product of 2.77 moles of polyisobutenyl propionic acid with 1 mole of tetraethylenepentamine in a lubricating oil concentrate containing 70% active ingredient.

2 A polypropylene alkylated benzene overbased barium sulfonate of total base number of 59 minimum in a lubricating oil concentrate, about -48 wt. percent active ingredient in which about one-half of the total barium present was colloidal barium carbonate. The total barium analysis is between about 14.3 and about 14.9%.

3 Obtained from the injector and the precombustion chamber.

4 Very little.

The fuel inspections carried out were by the following procedures: for gravity, ASTM D-287-64; for sulfur, D-l552-64; for viscosity, D-88-56; and for distillation, D-116061.

The data in Table I show that desalted Pembina crude without the additives is inferior to ordinary diesel fuel as a diesel fuel. Its use leads to fouled injectors in a 200 hour test as well as higher fuel consumption and a high viscosity increase of the used crankcase oil. This viscosity increase is mainly caused by the excessive amount of insolubles present, which are mainly derived from poor combustion of the fuel.

In column C it will be seen that .5% of an ashless dispersant added to the desalted Pembina crude eliminated the injector fouling and reduced the carbon deposit to an acceptable level (.13 gram). However, the used oil viscosity increase, with the ashless dispersant, was still high as shown by the 2.4% pentane insolubles in the used lube oil. Column D gives the result of a test in which the desalted Pembina crude contained .5 of a /50 mixture of the barium sulfonate and the ashless dispersant. This additive gave 4% lower fuel consumption when compared with conventional diesel fuel. It also eliminated injector fouling with accompanying low carbon deposit in the injection system. Similarly, the used oil viscosity increase and pentane insolubles were actually lower than obtained with a conventional diesel fuel. Column B shows the same additive combination but used at a lower treat of .1% of combined additives. At this concentration, the additive is still effective although it gave one incidence of injector fouling but even at this low treat level the viscosity increase and pentane insolubles of the used oil were well controlled and of the same magnitude as obtained with a conventional disel fuel, without the use of any of these additives. Synthetic crude (Runs F and G) showed, as a diesel fuel, a high quality performance both with and without dispersant additives, although slightly better performance, as to carbon deposit, was obtained with the use of the additives. Note, of course, that the synthetic crude contained only 0.07 wt. percent sulfur and no salts.

Having now thus fully described and illustrated the present invention, what is desired to be secured by Letters Patent is:

1. A crude oil useable as fuel for a diesel engine containing less than 1% sulfur and less than 3.0 pounds of inorganic salts per 1000 barrels of oil, having an API gravity of about 25 to 45 measured at 60 F a viscosity of about 35 to 250 SUS. at F., a distillation boiling range between about to about 1100 F. and selected from the group consisting of parafiinic, asphaltic, and mixed type crudes, and about 0.01 to about 2.0 wt. percent of a dispersant selected from the group consisting of (A) overbased alkaline earth metal sulfonates and (B) alkylene polyamine condensation products: of (a) alkenyl substituted unsaturated aliphatic dicarboxylic acids or their anhydrides, or (b) alkenyl substituted unsaturated aliphatic monocarboxylic acids or their anhydrides; and wherein said alkenyl group contains about 40 to 250 carbon atoms.

2. A crude oil as in claim 1, wherein said dispersant is an overbased alkaline earth metal sulfonate.

3. A crude oil as in claim 1, wherein said dispersant is an alkylene polyamine condensation product.

4. A crude oil as in claim 1, wherein said dispersant is a mixture of overbased alkaline earth metal sulfonate and alkylene polyamine condensation product.

5. A crude oil as in claim 1, wherein said crude oil is a parafiinic crude oil.

6. A crude oil as in claim 1, wherein the crude oil is a mixed crude oil.

7. A crude oil as in claim 1, wherein the crude oil is an asphaltic crude oil.

8. A crude oil as in claim 2, wherein the sulfonate is an overbased barium long chain alkenyl benzene sulfonate.

9. A crude oil as in claim 3, wherein the alkylene polyamine condensation product is the condensation product of tetraethylenepentamine and C to C alkenyl substituted propionic acid.

10. A process of running a heavy duty diesel engine having a fuel injector which comprises running said engine while fueled with the crude oil of claim 1.

References Cited UNITED STATES PATENTS 3,194,813 7/1965 Le Suer et al 4463X 3,219,666 11/1965 Norman et al 25251.5A 3,372,115 3/1968 McMillan 44-76X 3,374,174 3/1968 Le Suer 44-71X 3,437,465 4/1969 Le Suer 445l 3,471,403 10/ 1969 Le Suer et al 4476X FOREIGN PATENTS 1,075,121 7/1967 Great Britain 2525l.5A 1,11 /1,611 8/ 1968 Great Britain 4476 DANIEL E. WYMAN, Primary Examiner W. J. SHINE, Assistant Examiner U.S. Cl. X.R. 44-63, 71, 76

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,59 37 Dated July 97 Inventor(s) ThOIkild F. Lonstrup It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Table I, column 5, the seven columns in lines 33-41 should be aligned with the three columns in lines 20-32 as follows:

Column A should be aligned with the column labelled "Conventional Diesel Fuel"; Columns B, C,

D and E should be aligned with the column labelled "Desalted Pembina Crude"; and Columns F and G should be aligned with the column labelled "Synthetic Crude".

Signed and sealed this 9th day of April 1971 (SEAL) Attest:

EDWARD MELETCHERJR. C. MARSHALL DANN Attesting Officer Commissionerof Patents FORM PO-IOSO (10-69] USCOMNPDC $037643 u,sv oovsnumzm' PRINTING ornce: llll o:u-n4.