AU4608585A

AU4608585A - (improved) fuel compositions

Info

Publication number: AU4608585A
Application number: AU46085/85A
Authority: AU
Inventors: K. Mekenon; T.J. Tierney
Original assignee: EPOCH INT HOLDING
Current assignee: EPOCH INTERNATIONAL HOLDING SA
Priority date: 1984-06-27
Filing date: 1985-06-26
Publication date: 1986-01-24
Also published as: DK88886A; OA08217A; ES8609441A1; ES544573A0; EP0191033A1; WO1986000333A1; JPS62500525A; DK88886D0; EP0191033A4; MW1186A1; RO95015A; NO860669L; BR8506797A; HUT40156A; FI860839A; FI860839A0

Description

FUEL COMPOSITIONS

Background of the Invention

1. Field of the Invention

The present invention is concerned with greatly improved fuel compositions having a number of desirable properties such as significantly increased combustion efficiencies so that the fuels are more economical in use. More particularly, it is concerned with such fuels which are supplemented by minor amounts of certain polyolefins or derivatives thereof; the fuels of the invention include typical hydrocarbon fuels such as gasoline or diesel fuel in combination with an appropriate polyolefin additive, and also emulsified fuels containing substantial fractions of water.

2. Description of the Prior Art

A vast number of additives have been proposed in the past for use with conventional hydrocarbon fuels such as gasoline, diesel fuel or the like. In many cases additives have been proposed to remedy specific problems, such as the elimination of knocking through the addition of tetraethyl lead to gasoline. Other agents have also been proposed for the purpose of enhancing combustion efficiency, and hence the work output derived per unit of fuel consumed.

Alas, while the prior art is replete with attempts at providing significant enhancement of combustion efficiency, few if any truly successful additives have been discovered.

Researchers in the art have also proposed that significant quantities of water could be added to liquid hydrocarbon fuels to form a combustible emulsion which would, theoretically, lessen the consumption of the expensive hydrocarbon fuel. Indeed, such proposals extend back to the late nineteenth century. Here again though, no truly successful fuel/water emulsion has been developed in the past. The numerous problems heretofore experienced with such emulsified fuels include the fact that, when relatively large quantities of water are present, the combustion temperature is lowered; moreover, the presence of substantial water lowers the overall caloric value of the fuel. Finally, many prior fuel/water emulsions are relatively unstable, and tend to separate over time. Of course, if large quantities of surfactants are employed in such emulsions, the problem of phase separation can be avoided; however, this is inherently a very expensive proposition, and therefore in order to be truly economical, the amount of surfactant eraployed in an emulsified fuel must be relatively small.

Patent No. 2,896,593 relates to a two cycle fuel which includes a mixture of lead-free, straight run gasoline and from about 6-9% by volume polyisobutylene. This combination is said to be particularly useful in two cycle engines, where the polyisobutylene prevents engine fouling.

Patent No. 3,753,905 is likewise directed to a two cycle fuel which includes poly- butene along with mineral oil and other additives. Patent No. 3,085,978 is in some respects similar to the last mentioned patent, and teaches the use of polybutene along with a calcium salt of petroleum sulfonic acid in the context of a fuel composition. Patents Nos. 3,909,214 and 3,782,912 describe the use of polyolefins as fuel additives, along with other constituents such as amine salts and the like. However, none of the above mentioned patents relate specifically to emulsified fuels.

Other patents of background interest include U.S. Patents Nos. 4,162,143, 2,642,345, 4,339,246, 2,356,647, 4,392,865, 2,920,948, 3,163,603, 3,451,931, 4,125,382, 2,873,182, 3,410,671, 2,959,551, 3,271,310, 3,783,131 and 3,779,922.

Summary of the Invention

It has now been discovered that greatly improved fuel compositions can be provided which overcome many of the intractable problems discussed above. Broadly speaking, the invention resides in the discovery that use of certain types of polyolefinic compounds, typically in relatively minor amounts, gives significantly enhanced combustion efficiencies.

In one aspect of the invention, an improved fuel essentially free of lubricating oil is provided. The fuel comprises (and preferably consists essentially of) a combustible hydrocarbon material, and up to about 2.5% (e.g., about 0.1- 2.5%) by weight of a polyolefinic additive. The type and amount of additive serve to increase the work output per unit of fuel obtained using the improved fuel, as compared with the work output per unit of fuel obtained under the same conditions and using the identical fuel except for the absence of the polyolefinic additive therein. The additive is selected from the group consisting of polyolefins having recurring C₂-C₁₀ monomers therein (i.e., the monomers contain from 2 to 10 carbon atoms, inclusive), and derivatives of such polyolefins.

In preferred forms, the hydrocarbon material is selected from the group consisting of liquid hydrocarbons such as the gasolines, diesel fuels and heavy fuel oils of virtually any specific composition and type. The polyolefinic additive (the most preferred polyolefin being polybutene or polyisobutylene) is advantageously present at a level of from about 0.1 to 2% by weight, and most preferably at a level of from about 0.3 to 0.8% by weight. However, those skilled in the art will recognize that the specific amount of polyolefinic additive to be employed in a particular situation depends upon the hydrocarbon base material being employed, and the desired characteristics in the ultimate polyolef.in-supplemented fuel. For example, in the case of indoline it has been surprisingly discovered that good results are obtained when using polybutene at a level of up to about 1% (e.g., about 0.1-1%) by weight, but that significantly above this level of usage the results are dramatically reduced.

A wide variety of polyolefinic additives can be used in the context of the invention. While polyolefins having recurring C₂-C₁₀ monomers can be used, the most preferred polyolefins have recurring C₃-C₆ monomers therein. In addition to the most preferred polybutene additive, additives such as polyethylene, polypropylene, and polypentene can be employed; moreover, the various isomers of the polyolefins find utility in the invention, as well as diolefins and mixed polymers (e.g., co- and terpolymers). Finally, various types of polyolefin derivatives can also be employed, such as polyolefinic substituted with various moieties such as aryl groups and the like.

In certain forms of the invention, use can also be made of additional additives such as an aromatic compound (e.g., toluene) and another fuel different than the base hydrocarbon (e.g., diesel fuel in the case of a gasoline-based fuel).

In another aspect of the invention, liquid emulsified fuels are provided which broadly include respective quantities of a liquid hydrocarbon combustible fuel, water, at least one surfactant, and an additive selected from the group consisting of polyolefins having recurring C₂-C₁₀ monomers therein. Here again, the combustible fuel is advantageously selected from the group consisting of the gasolines, diesel fuels and heavy fuel oils, although other possibilities such as the residual oils could also be employed.

Preferably, the combustible fuel component is present at a level of from about 5 to 99% by weight, and more preferably from about 55 to 90% by weight. On the other hand, the water fraction is preferably present at a level of from about 1 to 95% by weight, and most preferably from about 10 to 45% by weight. In the case of emulsified fuels, the polyolefinic additive should be present at a level of up to about 2.5% by weight, and more preferably at a level of from about 0.1 to 2% by weight.

Various types of surfactants can be employed in the invention, in order to produce stable emulsions having good handling and combus tion characteristics. Broadly speaking, one or more surfactants can be used, although in practice it has been found that a combination of surfactants is best suited to the purposes of the invention. The surfactants should be present at a level of up to about 5% by weight, but in this case the prime consideration is one of cost. That is to say, an excess amount of surfactants may not deleteriously affect the characteristics of the fuel, but would be impractical from an economic standpoint.

Brief Description of the Drawing

The single Figure is a plot obtained during the tests described in Example I and illustrates the gain in horsepower/unit of fuel obtained with the improved fuels of the invention, and also that in the case of the indoline hydrocarbon fuel use of polybutene at a level above about 1% by weight is disadvantageous.

Description of the Preferred Embodiments

In the production of non-emulsified fuels in accordance with the invention, the selected polyolefin additive is simply mixed with the hydrocarbon base fuel material at the desired level of addition. The most preferred hydrocarbon bases are the gasolines and diesel fuels (particularly #2 diesel fuel), whereas the poleolefin additive is most preferably polybutene. In the latter connection, the polybutene should be dispersible in the hydrocarbon fuel being used, and advantageously has an average molecular weight of from about 500 to 2,000, and includes recurring isobutane monomers and a terminal olefinic group. One particular commercially available polybutene used to good effect in the invention is commercialized by the Chevron Chemical Co. as "Polybutene Grade 24." This material is a pale colored, chemically inert oily liquid of moderate to high viscosity and tackiness. The chemical and physical properties of this product are set forth in a publication from the manufacturer entitled "Technical Data Sheet Chevron Polybutenes" dated November 13, 1981. This data sheet is expressly incorporated by reference herein. Briefly, however, the polybutene Grade 24 material has a specific gravity at 15/15° C. of 0.898 (ASTM D 287), a density at 15/15° C. of 7.48 pounds per gallon and an average molecular weight (Mechrolab Osmometer) of 950. The presently most preferred non-emulsified fuel composition consists essentially of about 99.5% of base hydrocarbon fuel, particularly gasoline or #2 diesel oil, along with 0.5% of polybutene admixed therein.

In the context of emulsified fuels, the most preferred fuels include the polybutene Grade 24 additive described above, along with a substantial fraction of water in order to form a water- in-fuel emulsion. Here again, a wide variety of fuels can be employed, but the presently preferred hydrocarbon base fuels include members taken from the group consisting of the gasolines, diesel fuels and heavy fuel oils.

In terms of surfactants, the most preferred combination includes respective minor amounts of three eraulsifiers, namely: "TOXIMUL D", an anionic/nonionic blend emulsifier sold by the Stepan Chemical Co. and identified as calcium dodecyl benzene sulfonate/alkyl phenoxy polyoxy- ethylene ethanol blend, "Ammonyx LO" , sold by Onyx Chemical Co. and identified as dodecyldimethyl- amine oxide; and "Atpet-200" sold by ICI Americas and identifed as a sorbitan tallate. In addition however, various other kinds of surfactants can be used to good effect in the invention, such as "Z-MAZ 90" sold by Mazer Chemical Co. and identified as sorbitan monotallate. As those skilled in the art will readily perceive, however, an extremely large number of specific surfactants and combinations thereof can be used in the invention, as long as the aims thereof are achieved. In addition, the preferred emulsifier blend may have applicability in other types of emulsified fuels which do not contain the olefinic additive hereof. The following table sets forth the constituents of the especially preferred emulsified fuels in accordance with the invention, along with the most preferred levels of use thereof and appropriate ranges:

1 All data in % by weight In order to produce emulsions in accordance with the invention, it is preferred to first mix the surfactants to be employed, whereupon these surfactants are added to the hydrocarbon base material, with sufficient mixing to ensure homogeneity. At this point, the water is added, again with mixing to assure a relatively even dispersion. The preferred surfactant package described above greatly facilitates the mixing procedure, and no special equipment or the like is required. In the case of gasoline-based emulsions, it is estimated that the average particle diameter of the water in the emulsion is up to about 1/2 micron.

The following examples will illustrate specific fuels in accordance with the invention, as well as salient desirable properties thereof. It is to be understood, however, that these examples are provided for purposes of illustration only.

EXAMPLE I

In order to determine the degree of combustion enhancement using polyolefin-supplemented distillate hydrocarbon fuels having a major proportion of a hydrocarbon base fuel distilling within the gasoline distillation range, engine tests under load simulated by dynamometer were conducted in the laboratories of the University of California at Los Angeles, Los Angeles, California. A Ford, 132-Horsepower (3600 RPM), 6 cylinder engine with a bore of 4.0 inches, a stroke of 3.98 inches, a displacement of 300 cubic inches, compression ratio of 7.9, and torque of 241 ft- 1bs. at 1800 RPM was used with a dynamometer equipped with constant speed or constant load modes of automatic control throughout tests. Reference fuel was 91 Octane Indoline test fuel purchased from Amoco Oil Company.

The test program included addition of polybutene (Polybutene grade 24 purchased from the Chevron Chemicals Co. of San Francisco, California) at levels ranging from 0.25% to 2% by weight, to the Indoline test fuel to obtain ratios of work output/fuel consumed at standard engine RPM and torque load levels. Engine RPM was measured and monitored by digital pulse counter from about 700 RPM to maximum of 3,000 RPM. Torque load was held at 52.5 ft-lbs. In one test, a level of 0.3% by weight polybutene was selected for testing at three RPM levels (1,500, 2,000, 2,500) and 52.5 ft-lbs. of torque. As a comparison, straight Indoline was also run at these same RPM and torque levels to give the following results: at 1500 RPM and 52.5 ft-lbs., a work output/pound of straight indoline fuel of 91.5 HP/pound was recorded; at 2000 RPM, 52.5 ft-lbs., 91.1 HP/pound; at 2500 RPM, 52.5 ft-lbs., 89.3 HP/pound. Table II sets forth the results of this test.

As can be seen, in all instances the presence of polybutene increased the work output per pound of fuel, as compared with the straight Indoline test fuel. The percentage increases in combustion enhancement are significant, thereby confirming the value of polyolefin supplementation.

In a second series of tests, polybutene was added to the indoline test fuel at varying

levels ranging from 0.25 to 2.0% by weight. These additive-supplemented fuels were tested as outlined above to determine work output per pound of fuel. In all instances the engine test was performed at 2,000 RPM and 52.5 ft-1bs. torque.

The results of this series of tests are graphically depicted in the accompanying drawing. As can be seen, the work output per pound of fuel increases rapidly (as compared with the unsupplemented indoline) until an additive level of about 1.0% by weight is reached. Between 1.0 and 1.25% by weight, however, the work output per pound of fuel is dramatically decreased, to a point below the unsuppleraented indoline. This was an extremely surprising result, and demonstrates that, at least in connection with the specific indoline test fuel used and at the specified conditions, a relatively critical level of polybutene supplementation is required to achieve optimum results.

EXAMPLE 2

In order to quantitatively confirm the results obtained in Example 1 and to more fully establish the viability of additive-supplemented distillate hydrocarbon fuels having a major proportion of a hydrocarbon base fuel distilling within the gasoline distillation range, consumption tests were conducted at Jarama Race Track in Madrid, Spain. Tests were conducted by, and all drivers certified by, the Real Automobil Club de Espana.

Test A was conducted by driving a 1978

Daimler Jaguar with a six cylinder engine (engine was recently installed new and has less than six months usage) having a bore of 92.07 mm, a stroke of 106 mm, and displacement of 4.2 liters, for a duration of approximately ten liters fuel consumption. The Jaguar was first tested using straight 98 octane gasoline and then compared against additive-supplemented 90 octane gasoline containing 0.5% polybutene. Data is listed in Table III and, in the opinion of the test driver, results obtained with the additive-supplemented fuels were "spectacular."

Test B was conducted by driving a 1982 Datsun, model 280ZX, with an engine having a bore of 3.386 mm, a stroke of 79 mm, and displacement of 2.8 liters, and equipped with 5-speed transmission and electronically controlled fuel injection.. The auto was driven at the top speed possible for a duration of approximately ten liters fuel consumption. The Datsun was first tested on standard 98 octane gasoline and then compared against additive-supplemented (0.5% by weight polybutene) 90 octane gasoline. The data is set forth in Table III. It should be noted that both cars will not operate on standard 90 octane gasoline without additive supplementation due to detonation ("knocking" or "pinging").

Another test involved a qualitative comparison of detonation effects between 98 octane and additive-supplemented (0.5% by weight polybutene) 90 octane gasolines using a new Honda, model VF-1000, 1.0 liter, four cycle test motorcycle at Jarama Race Track in Madrid, Spain. The motorcycle was found to detonate using 98 octane gasoline at high temperatures whereas no detonation occurred at high temperatures with the additive-supplemented, 90 octane gasoline.

EXAMPLE 3

In order to demonstrate the advantages of emulsions of the invention containing water and distillate hydrocarbon fuels having a major proportion of a hydrocarbon base fuel distilling within the diesel fuel distillation range, two engine tests were conducted in the Andalucia Province of Spain. The comparative tests were conducted using straight GAS-OIL A, a known reference fuel, and alternately an emulsion, produced as outlined above and including 77.5% by weight standard GAS-OIL A, 0.75% by weight Atpet-200, 0.50% by weight Ammonyx-LO, 0.50% by weight Polybutene 24 purchased from Ashland Chemical Company and 20% by weight water. During each test, observations without quantitative measurements were made for soot reduction, else of hot and cold starting and stopping, along with general running characteristics. In all cases, the emulsions were deemed superior to the straight fuel.

Engine Test 1 measured comparative fuel consumption of straight GAS-OIL A and the emulsified GAS-OIL A during operation of a Diter, D302.1, 16 HP, one cylinder diesel engine with a displacement of 745 cc used to power constant load water pump at 2,300 RPM. Test 2 compared fuel consumption of straight GAS-OIL A and emulsified GAS-OIL A while operating a four cylinder, Mercedes 200D diesel engine. It was evident during Test 2 that the Mercedes produced more power while consuming emulsified GAS-OIL A as opposed to GAS-OIL A without emulsion although the amount was not quantitatively measured. Consumption results are set forth below:

1 Corrected for presence of water in emulsified fuels to give comparable results in terms of amounts of hydrocarbon present in both the straight and emulsified fuels.

EXAMPLE 4

Tests were conducted to determine the general characteristics of emulsified distillate fuels in a conventional fuel handling system such as a boiler or furnace. Factors considered were pumpability, filterability, ignitability and flare stability. Equipment used was a Century Type Jl oil burner assembly with a Sundstrand fuel pump and Marathon Model T2742 motor. The assembly was modified by the addition of a horizontal, 3 foot long, 5 inch diameter pipe equipped with 2 foot long, 8 inch diameter vertical chamber, and a 5 foot long, 5 inch diameter chimney at the outlet end of the horizontal pipe. A 1/2 inch diameter, horizontal water pipe was installed through the vertical chamber to permit water to be introduced through the pipe without direct flame impingement against the water pipe, and to measure water inlet and outlet temperatures.

Various emulsified fuel formulations were tested under identical conditions and compared against the #2 diesel fuel as a reference. Fuel flow was measured on a weight/time basis (simulated load cell) to obtain calorific input, as was water condensate to measure work output. No consideration was given to efficiency, as the objective was determination of the relative enhancement in combustion chemistry.

All emulsified fuel formulations (up to

40% water) performed satisfactorily. There was no evidence of water separation or filter clogging. The emulsions burned well at all pumping pressures where #2 diesel would burn. Atomization appeared good and no corrosion tendencies were noted. The following Table V sets forth the results of these tests wherein: fuel (1) is an emulsion containing 20%. by weight water, 0.5% by weight polybutene 24

(Ashland Chemical), 0.75% by weight TOXIMUL D

(Stephan Chemical Co.), 0.75% by weight Atpet-200

(I.C.I. Americas), 0.50% Ammoyx-LO (Onyx Chemical

Co.) and 77.5% #2 diesel fuel; fuel (2) is an emulsion containing 15% by weight water, 0.5% by weight polybutene, the same emulsifiers and amounts as fuel (1), and 82.5% #2 diesel fuel; fuel (3) is straight #2 diesel fuel; and fuel (4) is identical with fuel (1) except that the polybutene is eliminated and 78% by weight #2 diesel fuel is present.

As can be seen from a comparison of fuels (1) and (4), the presence of polybutene gives a very significant enhancement in work output per pound of fuel. Furthermore, results ¹

demonstrate that in most instances the emulsified fuels are advantageous over straight #2 diesel fuel.

In addition to the foregoing, limited comparative performance testing was conducted in a small boiler in Kansas City, Missouri. The boiler was a 75 HP Kewanee steam boiler set to 7 1/2 psig high pressure cut-off, 4.0 psig low pressure cut-off. The load consisted of 5 fan driven space heaters (fans approximately 20 inch diameter). Fuel samples contained in drums of 21 5/16 inch diameter were measured volumetrically. Water measurement was accomplished by passing the boiler fill line run through a Signet MK 515 Flosensor with MK575R Flowmeter.

The boiler was brought up to pressure on minimum fire with the fuel bypass modulator valve locked in the minimum position. Approximately six minutes after high pressure shut down, the boiler was filled with water until the pump was shut off by the high level switch. The water flowmeter was then reset to zero and the fuel level measured. The boiler was allowed to fire automatically by the high and low steam pressure switches through four complete cycles. At approximately six minutes after high pressure shut down on the fourth firing cycle, the boiler was again filled and final measurements taken of the fuel level and water meter reading.

CO₂ increased from 11%, firing #2 diesel fuel (reference fuel), to 12.5%, firing emulsified diesel fuel (same as fuel (1), Table IV) indicating increased combustion efficiency. The fire became unstable when switched to emulsified fuel because, according to the Testing Engineer, there was insufficient excess air (oxygen) to support combustion. Excess air was opened to approximately maximum (supporting more than 3MM BTU/hour combustion), and fuel flow rate was reduced to minimum (approximately 1.2MM BTU/hour) and there was still insufficient air to support combustion. This indicates that the emulsified fuel of the invention had a combustion efficiency greatly in excess of straight #2 diesel fuel.

EXAMPLE 5

Various tests were conducted and certified under the direction of the Ministerio de Defensa at the Instituto Nacional de Tecnica Aeroespacial in Madrid, Spain. Results were recorded in certification number 40180 as follows with respect to 4 emulsions produced in accordance with the present invention:

Emulsion #1 - 20% by weight water, 0.5% by weight polybutene, 2.0% by weight emulsifiers (0.75% by weight T-MULZ-D,

0.75% by weight Atpet-200 and 0.5% by weight Ammonyx-LO) and 77.5% by weight GAS-OIL A - pH - 7.8

Viscosity at 37.8°C - 6.2 cSt (centistokes)

Filtration - Passes unencumbered

Stability - Stable

Emulsion #2 - 20% by weight water, 0.5% by weight polybutene, 2.0% by weight emulsification agents (same makeup as Emulsion #1) and 77.5% by wegiht GAS-OIL B - pH - 7.5 Viscosity at 37.8°C - 5.4 cSt

Filtration - Passes unencumbered Stability - Stable

Emulsion #3 - 20% by weight water, 0.5% by weight polybutene, 2.0% by weight emulsifica- tion agents (same makeup as Emulsion # 1) and 77.5% by weight GAS-OIL C - pH - 7.7

Viscosity at 37.8°C - 5.7 cSt Filtration - Passes unencumbered Stability - Stable

Emulsion #4 - 20% by weight water, 0.5% by weight polybutene, 2.0% by weight emulsification agents (same makeup as Emulsion #1) and 77.5% by weight residual fuel oil - Viscosity at 37.8°C - 580.4 cSt Viscosity at 50.0°C - 331E

These emulsions were stable and remained so over more than two months shelf life.

EXAMPLE 6

In order to determine the ability of emulsified distillate fuels in accordance with the invention to pass through a coalescing filter without separation of water, various emulsified distillate fuel formulations were pumped through a Caterpillar #6M7617 water separator element. Emulsions were pumped by air pressure at 5 psig through the coalescing filter which was mounted in a glass bowl. No free water has been observed in more than five months of testing.

A qualitative comparison of the quantity of sulphur in combustion gases of emulsified and non-emulsified fuel oils was made by sequentially burning various grades of fuel oils in a dish. A 5 inch diameter tube, 1 1/2 foot long was placed over the flame to act as flue stock. Porous filter papers soaked with potassium permanganate solution were placed over the tub^ for one minute. A bleaching of these papers would indicate the presence of sulphur in the combistior. gases.

Both distillate and residual fuel oil samples burned showed marked color change (bleaching). Emulsified residual fuel oil samples not incorporating polyolefins or emulsifiers shewed similar color change to the non-emulsified samples of the same fuels although somewhat darker. Fuel oil samples emulsified with water and the preferred emulsifiers and supplemented with polybutene showed no color change when using distillate fuel (#2 diesel) and only a slight color change with residual fuels (#5 and #6).

While the inventors do not wish to be bound to any specific theory as to why the polyolefinic additives of the invention give such outstanding results, it is hypothesized that such additives in some way initiate or promote reactions analogous to cracking during the combustion of the polyolefin supplemented fuel compositions hereof. Under this line of reasoning, such reactions would produce smaller, lower molecular weight hydrocarbons, which are known to be more readily combustible. Moreover, the exothermic heats of reaction would theoretically add substantially to the caloric value obtained from the fuels.

While the foregoing disclosure has been primarily directed to the use of liquid hydrocarbon base materials, it is also believed that the combustibility of solid hydrocarbon material such as coal can be enhanced through the use of polyolefinic agents of the invention. In such a context, the polyolefinic material could be simply sprayed upon crushed coal in order to give enhanced combustion characteristics or, alternatively, the polyolefinic agents could be added to coal/liquid suspensions.

Claims

1. An improved engine fuel essentially free of lubricating oil and comprising a combustible hydrocarbon material, and from about 0.1 to 2.5% byt weight of an additive, the type and amount of said additive serving to increase the work output per unit of fuel obtained using said improved fuel, as compared with the work output per unit of fuel obtained under the same conditions using a fuel identical with said improved fuel except for the absence of said additive, said additive comprising a polyolefinic substance having recurring C₂-C1₀ monomers therein.

2. The improved fuel of Calim 1, said improved fuel consisting essentially of said hydrocarbon material and said additive.

3. The improved fuel of Claim 1, said material being selected from the group consisting of liquid hydrocarbons.

4. The improved fuel of Claim 3, said liquid hydrocarbons being selected from the group consisting of the gasolines, diesel fuels and heavy fuel oils.

5. The improved fuel of Claim 1, said additive being present at a level of from about 0.1 to 2% by weight.

6. The improved fuel of Claim 5, said level being from about 0.3 to 0.8% by weight.

7. The improved fuel of Claim 1, said additive being selected from the group consisting of polyolefins having recurring C₃-C₆ monomers therein.

8. The improved fuel of Claim 6, said additive being polybutene.

9. The improved fuel of Claim 1, including a minor amount of an aromatic compound admixed withs aid fuel.

10. The improved fuel of Claim 1, including a minor amount of another fuel different than said combustible hydrocarbon material.

11. An improved four-cycle engine fule essentially free to lubricating oil and comprising gasoline and from about 0.1 to 1 % by weight of polybutene.

12. The improved fuel of Claim 11, said engine fuel consisting essentially of gasoline and polybutene.

13. An improved liquid emulsified fuel comprising respective quantities of a liquiid hydrocarbon combustible fuel, water, at least one surfactant, and an additive selected from the group consisting of polyolefins having recurring C₂-C₁₀ monomers therein.

14. The emulsified fuel of Claim 13, said combustible fuel being selected from the group consisting of the gasolines, diesel fuels and heavy fuel oils.

15. The emulsified fuel of Claim 13, said combustible fuel being present at a level of from about 5 to 99% by weight.

16. The emulsified fuel of Claim 13, said water being present at a level of from about 1 to 9055 by weight.

17. The emulsified fuel of Claim 13, said additive being present at a level of up to about 2.5% by weight.

18. The emulsified fuel of Claim 17, said level being from about 0.1 to 2% by weight.

19. The emulsified fuel of Claim 13, said surfactant being present at a level of up to about 5% by weight.

20. The emulsified fuel of Claim 13, including a plurality of surfactants.

21. An emulsified fuel comprising respective quantities of a liquid hydrocarbon combustible fuel, water, and a surfactant system comprising (1) alkaline earth dodecyl benzene sulfonate/alkyl phenoxy polyoxyethylene ethanol blend; (2) dodecyldimethylamine oxide; and (3) sorbitan tallate.