Conductivity of middle distillate fuels with a combination of detergent and cold flow improver
The disclosure provides conductivity improving concentrates and methods for improving conductivity and reducing risks associated with static discharge in middle distillate fuel compositions, particularly diesel fuels. The conductivity improvement is provided by the combination of a detergent and a cold flow improver, which are preferably and advantageously pre-blended in an additive concentrate. The disclosure is particularly beneficial for ultra-low sulfur fuel compositions in that it provides a conductivity benefit without adding sulfur into the fuel composition.
The disclosure relates to compositions and methods for improving the conductivity of middle distillate fuel compositions, particularly diesel fuels and most particularly low sulfur and ultra-low sulfur diesel fuels.
BACKGROUND OF THE DISCLOSURECertain middle distillate fuel compositions, particularly diesel fuels, are capable of generating static electricity, particularly when moving rapidly, such as when the fuel is being dispensed into a tanker or other bulk container or vessel. While diesel fuels are not very volatile, the tankers used to transport diesel fuels are also used to transport gasoline, kerosene and other more volatile and flammable liquids. Even after the more volatile fuel is dispensed from the tanker, the vapors may still be present and pose a risk of fire or explosion from a spark generated by the discharge of static electricity from the fuel composition.
These risks have become more acute in recent years with the increased popularity and use of low sulfur fuels and even more acute in recent months with the introduction of ultra-low sulfur diesel fuels. The process used to remove the sulfur from the fuels also decreases the concentration of other polar compounds in the fuel, which in turn reduces the ability of the fuel to dissipate a static charge.
To mitigate the risks of fire or explosion with low and ultra-low sulfur fuels, it has become desirable to add a conductivity improver to the fuel at or prior to the point of dispensing the fuel into a bulk container. The conductivity improver, as the name suggests, improves the conductivity of the fuel, thus permitting any static charge that might otherwise build up during high volume transport of the fuel to safely dissipate the static charge without generating a spark. Conductivity improvers are also known as antistatic agents.
The most common type of conductivity improver or antistatic agent used in fuels, particularly diesel fuels, has been the Stadis® brand of antistatic agents sold by Innospec Fuel Specialties, LLC, Newark, Del. However, the Stadis® brand of antistatic agents contains sulfur. Because sulfur is known to have an adverse effect on the equipment used to remove or reduce emissions from a combustion process, adding the Stadis® antistatic agents to the diesel fuel tends to be counterproductive and shorten the life of the equipment.
Therefore, there is a need for compositions and methods that address the build-up and discharge of static electricity in middle distillate fuel compositions.
SUMMARY OF THE EMBODIMENTSIn an embodiment, the disclosure provides an additive concentrate for a middle distillate fuel composition comprising an antistatic agent, the antistatic agent comprising, in combination, a detergent and a cold flow improver.
In an embodiment, the disclosure provides a middle distillate fuel composition comprising a conductivity-improving amount of an antistatic agent, the antistatic agent comprising a detergent and a cold flow improver.
In an embodiment, the disclosure provides a method for improving the conductivity of a middle distillate fuel composition, the method comprising the step of adding an antistatic agent to a fuel, wherein the antistatic agent comprises, in combination, a detergent and a cold flow improver.
In an embodiment, the disclosure provides a method of dispensing a middle distillate fuel composition, the method comprising the step of adding an antistatic agent to a fuel in an amount sufficient to provide a conductivity of at least 25 pS/m at the time and temperature of delivery of said fuel, wherein the antistatic agent comprises, in combination, a detergent and a cold flow improver.
Another embodiment of the present disclosure provides a method of reducing a risk of explosion from static discharge, comprising the steps of adding an antistatic agent to a middle distillate fuel composition in an amount sufficient to provide a conductivity of at least 25 pS/m at the time and temperature of the fuel, wherein the antistatic agent comprises, in combination, a detergent and a cold flow improver.
Additional objects and advantages of the disclosure will be set forth in part in the description which follows, and/or can be learned by practice of the disclosure. The objects and advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure or the appended claims.
DETAILED DESCRIPTION OF THE EMBODIMENTSBy improving the conductivity of the fuel, the fuel is better able to dissipate a static charge that might be generated by high volume transportation of the fuel, such as when the fuel is dispensed into a tanker truck or rail car. Because the fuel is better able to dissipate a static charge, the fuel is less likely to generate a spark, which may ignite volatile fumes that might be present in the area, either from the fuel itself or from previous fuels that may have been transported in the tanker.
The combination of detergent and cold flow improver has been used in the past in a multi-functional additive concentrate for diesel fuels. Such a combination is particularly useful in additive concentrates used for diesel fuels in colder climates and/or during the winter months. As the temperature of diesel fuels is lowered, wax crystals or gels begin to develop in the fuel. Not only does the development of these crystals and gels make the fuel more difficult to pore, but they also tend to accumulate and plug filters used to remove particulates and impurities from the fuel.
Cold flow improvers are of two general types: those that depress the pour point of the diesel fuel (known as pour point depressants) and those that act to improve the flow of the fuel through a filter in the presence of the wax crystals and gels (known as operability improvers). These operability improvers do not reduce the formation of the crystals or gels, but rather alter the way in which they form, thus permitting the fuel to flow through the filter despite the presence of these undesired consequences of the lower temperature until such time as the fuel warms up and the crystals and gels dissolve.
To ensure that the fuels flow smoothly through the pipelines, the refineries need to meet certain specifications for pour point in the fuels. However, the refiners do not need to meet specifications for operability (i.e., filter flow). Thus, while refineries may add pour point depressants, they do not always include operability additives. In addition, because they have different mechanisms of action, the pour point additives incorporated into the fuel at the refinery may not have any effect on filter flow of the fuel. Accordingly, it is common to incorporate operability-type cold flow improvers into the diesel fuel at the point of distribution, along with other beneficial additives.
One problem with common antistatic agents, like the Stadis® antistatic agents, is that the conductivity benefit dissipates relatively quickly once introduced into a composition containing a basic nitrogen component. Such components are typically present in fuels and/or additive concentrates in the form of detergents, dispersants, cetane improvers or other ingredients. Thus, these types of antistatic agents must be kept in a separate tank at the depot and added separately to the fuel at or near the time of dispensing the fuel into a tanker, for example, to ensure that the conductivity benefit from such antistatic agents is in fact obtained. Accordingly, these types of antistatic agent, apart from their inherent additional cost, require additional costs and complexity in terms of storage, handling and dispensing.
The present embodiments are based on the surprising discovery by Applicants that the combination of detergent and operability-type cold flow improver can be used to provide a conductivity benefit to a diesel fuel. Applicants have also discovered that the conductivity benefit provided by such a combination is a sustained benefit, such that the detergent and cold flow improver can be pre-mixed into an additive concentrate and provide a conductivity benefit to the fuel months of even years afterward when the additive concentrate is added to the fuel. This conductivity benefit has heretofore gone undiscovered in the prior art.
The present embodiments enable an improvement in conductivity of a middle distillate fuel composition using only components that provide other functional attributes and are otherwise beneficial to the fuel. This is in contrast to prior art teachings and the conventional wisdom of adding antistatic compounds that provide no other benefit to the fuel and are added solely for their antistatic properties. The present embodiments also provide conductivity benefits without adding sulfur-containing compounds like the Stadis® antistatic agents to an ultra-low sulfur fuel, and thus provide that benefit as well.
The present embodiments are particularly suited for middle distillate fuel compositions. Middle distillate fuel compositions include, but are not limited to, jet fuels, diesel fuels, and kerosene. In one embodiment, the fuel is a low-sulfur fuel having less than about 500 ppm sulfur, more preferably having less than about 350 ppm sulfur. In another embodiment, the fuel is an ultra-low sulfur diesel fuel or ultra-low sulfur kerosene. Ultra-low sulfur fuels are generally considered to have no more than about 15 ppm of sulfur, more preferably no more than 10 ppm of sulfur. The term “diesel fuel” is generally considered to be a generic term encompassing diesel, biodiesel, biodiesel-derived fuel, synthetic diesel and mixtures thereof. All disclosures herein of parts per million (“ppm”) are by mass unless otherwise indicated
The present disclosure encompasses jet fuels, although these are conventionally not regarded as “low-sulfur” or “ultra-low sulfur” fuels since their sulfur levels can be comparatively quite high. Nevertheless, jet fuels may also benefit from the conductivity improvement of the present embodiments regardless of their sulfur content.
The terms “combustion system” and “apparatus” used in the disclosure connote any apparatus, machine or motor that utilize, in whole or in part, a combustible fuel to generate power. The terms include, for example, diesel-electric hybrid vehicle, a gasoline-electric hybrid vehicle, a two-stroke engine, any and all burners or combustion units, including for example, stationary burners, waste incinerators, diesel fuel burners, diesel fuel engines, automotive diesel engines, gasoline fuel burners, gasoline fuel engines, power plant generators, and the like. The hydrocarbonaceous fuel combustion systems that may benefit from the present disclosure include all combustion units, systems, devices, and/or engines that burn fuels. The term “combustion system” also encompasses internal and external combustion devices, machines, engines, turbine engines, jet engines, boilers, incinerators, evaporative burners, plasma burner systems, plasma arc, stationary burners, and the like which can combust or in which can be combusted a hydrocarbonaceous fuel.
The middle distillate fuel compositions contemplated by the present disclosure can contain other additives. Such additives may be added directly to the fuel or may comprise an additive concentrate which is, in turn, added to the fuel. Examples of conventional fuel additives which may be used include antioxidants, fuel stabilizers, dispersants, antihaze agents, antifoams, cetane number improvers, ignition and combustion improvers, corrosion inhibitors, biocides, dyes, smoke reducers, catalyst life enhancers and demulsifiers, lubricity agents and other standard or useful fuel additives.
Examples of common additives for middle distillate fuel compositions include non polar organic solvents such as aromatic and aliphatic hydrocarbons, including toluene, xylene and white spirit, e.g. those sold under the Trade Mark “SHELLSOL” by the Royal Dutch/Shell Group, or those sold as AROMATIC 100 and AROMATIC 150 sold by ExxonMobil; polar organic solvents, in particular, alcohols generally aliphatic alcohols e.g. 2 ethylhexanol, decanol and isotridecanol, dehazers, e.g. alkoxylated phenol formaldehyde polymers such as those commercially available as NALCO™ 7D07 (ex Nalco), and TOLAD™ 2683 (ex Petrolite), anti-foaming agents e.g. the polyether-modified polysiloxanes commercially available as TEGOPREN™ 5851 (ex Th. Goldschmidt) Q 25907 (ex Dow Corning) or RHODORSIL™ (ex Rhone Poulenc); ignition improvers such as aliphatic nitrates e.g. 2-ethylhexyl nitrate and cyclohexyl nitrate; anti-rust agents such as polyhydric alcohol esters of succinic acid derivatives (e.g. commercially sold by Rhein Chemie, Mannheim, Germany as RC 4801™, or by Afton Chemical as HiTEC® 536; anti-oxidants e.g. phenolics such as 2,6-di-tert-butylphenol, or phenylenediamines such as N,N′-di-sec-butyl-p-phenylenediamine; metal deactivators such as salicylic acid derivatives, e.g. N,N′-disalicylidene-1,2-propane diamine and; lubricity agents such as fatty acids and esters, (e.g. those commercially available as EC831, P631, P633 or P639 (ex Infinium) or HITEC® 580 (ex Afton Chemical), Lubrizols™ 539A (ex Lubrizol), VECTRON™ 6010 (ex Shell Additives), OLI9000 (ex Associated Octel).
Some of these additives are more commonly added directly at the refinery while the others form part of a diesel fuel additive, typically added at the point of loading into the tanker.
Particularly preferred lubricity additives are derived by the reaction, combination, mixture, or admixture of a hydrocarbyl-substituted succinic anhydride and a hydroxyamine. These additives enhance the lubricating properties of the fuel without degrading other performance features of the fuel, such as detergency, ignition quality, stability, and so on. In addition, non-acidic lubricity additives posing less risk of corrosion to parts contacted by middle distillate fuel compositions and of reaction with basic components of fuel additive formulations
In one aspect, the term “hydrocarbyl” group is an alkenyl or alkyl group. The term “hydroxyamine” has general meaning encompassing either monohydroxyamine or polyhydroxyamine, such as dihydroxyamine, or mixtures thereof. Examples of useful hydrocarbyl succinic anhydride compounds include tridecylsuccinic anhydride, pentadecylsuccinic anhydride, tetradecenylsuccinic anhydride, hexadecenylsuccinic anhydride, dodecylsuccinic anhydride, tetradecylsuccinic anhydride, hexadecylsuccinic anhydride, octadecenylsuccinic anhydride, tetrapropylene-substituted succinic anhydride, docosenylsuccinic anhydride, and mixtures thereof.
Examples of hydroxyamines include ethanolamine, diethanolamine, N-alkylethanolamines, N-alkenylethanolamines, N-alkylisopropanolamines, N-alkenylisopropanolamines, isopropanolamine, diisopropanolamine, tris(hydroxymethyl)aminomethane, 3-amino-1,2-propanediol, 2-amino-1,3-propanediol, and mixtures thereof, where the alkyl and alkenyl groups, when present, contain 1 to 12 carbon atoms. Other useful hydroxyamines include 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol, 4-aminophenol, their isomers, and mixtures thereof. Still another group of hydroxyamines have the hydroxyl group directly bonded to the nitrogen, such as hydroxylamine, and N-alkylhydroxyamines or N-alkenylhydroxyamines where the alkyl or alkenyl group may contain up to 12 carbon atoms.
Also useful are HSA-hydroxyamine compounds in which the free hydroxyl group has been allowed to react with epoxides such as ethylene oxide, propylene oxide, butylene oxide, glycidol, and the like. The molar ratio of hydrocarbyl-substituted succinic anhydride acylating agent to hydroxyamine can be from about 1:4 to about 4:1, and more preferably is from about 1:2 to about 2:1.
Typically, the concentration of the lubricity enhancing additive used in a middle distillate fuel composition falls in the range 10 to 1000 ppm, preferably 10 to 500 ppm, and more preferably from 25 to 250 ppm. When mixtures of additives are used the overall additive concentration falls within the typical range noted.
For the sake of convenience, the additives may be provided as a concentrate for dilution with fuel. Such a concentrate typically comprises from 99 to 1% by weight additive and from 1 to 99% by weight of solvent or diluent for the additive which solvent or diluent is miscible and/or capable of dissolving in the fuel in which the concentrate is to be used. The solvent or diluent may, of course, be the low sulfur fuel itself. However, examples of other solvents or diluents include white spirit, kerosene, alcohols (e.g., 2-ethyl hexanol, isopropanol and isodecanol), high boiling point aromatic solvents (e.g., toluene, xylene) and cetane improvers (e.g., 2-ethyl hexylnitrate). Of course, these may be used alone or as mixtures.
The compositions and methods of the present embodiments are capable of providing conductivity to a fuel of at least 25 pS/m at the time and temperature of delivery. This conductivity is sufficient to meet the proposed new ASTM standard for conductivity in diesel fuels (ASTM D975 and amendments and appendices thereto) measured according to any appropriate test procedure, including but not limited to ASTM D2624. The conductivity benefit is obtained by adding to a middle distillate fuel composition the combination of a detergent and an operability-type cold flow improver.
The term “sulfur-containing compounds” used herein connotes organo-sulfur compounds; including sulfone, polysulfone, linear and branched aliphatic or aromatic sulfonates, sulfates, sulfides, sulfurized alkenes, polyalkenes, sulfurized polyphenols, sulfonic acids, and salts thereof.
The term “substantially free” when used to in connection with a reference to “sulfur” indicates that the relevant compounds contribute no more than 15 ppm of sulfur to the composition when measured according to for example, ASTM D2622 or ASTM D4951, preferably no more than 10 ppm of sulfur and most preferably no more than about 5 ppm of sulfur.
Suitable ashless detergents/dispersants include amides, amines, polyetheramines, Mannich bases, succinimides (which are preferred). Metal-containing detergents are also effective. Mixtures and combinations of detergents may also be used, if desired.
These detergents/dispersants are well known in the patent literature, mainly as additives for use in lubricant compositions, but their use in hydrocarbon fuels has also been described. Ashless dispersants leave little or no metal-containing residue on combustion. They generally contain only carbon, hydrogen, oxygen and in most cases nitrogen, but sometimes contain in addition other non-metallic elements such as phosphorus, sulphur or boron. A particularly useful ashless dispersant/detergent herein is derived from “high reactive” polyisobutylene (HR-PIB) substituted on a maleic anhydride reacted with a polyamine to achieve a level of about 5.4% nitrogen to achieve enhanced dispersancy. Such a material is available from Afton Chemical Corporation as HiTEC® 9651; HiTEC® 4247 or HiTEC® 4249. The detergent/dispersant can be used in the fuel additive concentrates at levels of from about 5 to about 50% by weight, more preferably 10-30%.
In one preferred embodiment, the detergent is a succinimide, which has an average of at least 3 nitrogen atoms per molecule. The succinimide is preferably aliphatic and may be saturated or unsaturated, especially ethylenically unsaturated, e.g. an alkyl or alkenyl succinimide. Typically the detergent is formed from an alkyl or alkenyl succinic acylating agent, generally having at least 35 carbon atoms in the alkyl or alkenyl group, and an alkylene polyamine mixture having an average of at least 3 nitrogen atoms per molecule. In another embodiment the polyamine has 4 to 6 nitrogen atoms per molecule. Preferably it can be formed from a polyisobutenyl succinic acylating agent derived from polyisobutene having a number average molecular weight of 500 to 10,000 and an ethylene polyamine which can include cyclic and acyclic parts, having an average composition from triethylene tetramine to pentaethylene hexamine. Thus the chain will typically have a molecular weight from 500 to 2500, especially 750 to 1500 with those having molecular weights around 900 and 1300 being particularly useful although a succinimide with an aliphatic chain with a molecular weight of about 2100 is also useful. Further details can be found in U.S. Pat. Nos. 5,932,525 and 6048373 and EP-A•432,941, 460309 and 1,237,373.
Examples of suitable metal-containing detergents useful herein include, but are not limited to, such substances as lithium phenates, sodium phenates, potassium phenates, calcium phenates, magnesium phenates, sulphurised lithium phenates, sulphurised sodium phenates, sulphurised potassium phenates, sulphurised calcium phenates, and sulphurised magnesium phenates wherein each aromatic group has one or more aliphatic groups to impart hydrocarbon solubility; the basic salts of any of the foregoing phenols or sulphurised phenols (often referred to as “overbased” phenates or “overbased sulphurised phenates”); lithium sulfonates, sodium sulfonates, potassium sulfonates, calcium sulfonates, and magnesium sulfonates wherein each sulphonic acid moiety is attached to an aromatic nucleus which in turn usually contains one or more aliphatic substituents to impart hydrocarbon solubility; the basic salts of any of the foregoing sulfonates (often referred to as “overbased sulfonates”; lithium salicylates, sodium salicylates, potassium salicylates, calcium salicylates, and magnesium salicylates wherein the aromatic moiety is usually substituted by one or more aliphatic substituents to impart hydrocarbon solubility; the basic salts of any of the foregoing salicylates (often referred to as “overbased salicylates”); the lithium, sodium, potassium, calcium and magnesium salts of hydrolysed phosphosulphurised olefins having 10 to 2000 carbon atoms or of hydrolysed phosphosulphurised alcohols and/or aliphatic-substituted phenolic compounds having 10 to 2000 carbon atoms; lithium, sodium, potassium, calcium and magnesium salts of aliphatic carboxylic acids and aliphatic-substituted cycloaliphatic carboxylic acids; the basic salts of the foregoing carboxylic acids (often referred to as “overbased carboxylates” and many other similar alkali and alkaline earth metal salts of oil-soluble organic acids. Mixtures of salts of two or more different alkali and/or alkaline earth metals can be used. Likewise, salts of mixtures of two or more different acids or two or more different types of acids (e.g., one or more calcium phenates with one or more calcium sulfonates) can also be used. While rubidium, cesium and strontium salts are feasible, their expense renders them impractical for most uses.
Particularly preferred cold flow improvers for the present embodiments include the operability-type of cold flow improver mentioned previously. This type of cold flow improver improves the ability of the fuel to flow through a filter, as determined according to the Cold Filter Plugging Point Test (ASTM D6371) or the Low Temperature Flow Test (ASTM D4539). Particularly preferred cold flow improvers include acrylates, methacrylates, ethylene vinyl acetate copolymers, chlorinated hydrocarbons and polyolefins, and alkyl phenols. A most preferred cold flow improver is Altra™ 205 available from Allegheny Petroleum Products Corporation. Combinations of cold flow improvers may also be used to advantage. The cold flow improver is generally present in an amount of from about 25 to about 100 ppm.
EXAMPLESThe following examples illustrate but do not limit the present embodiments.
The following components were used in the Examples:
HiTEC® 4130S is a multi-functional fuel additive concentrate available from Afton Chemical. It comprises a succinimide detergent, an ester based lubricity additive, a corrosion inhibitor, a demulsifier, aromatic solvents and alcohol cosolvent.
HiTEC® 4130W is a multi-functional fuel additive concentrate available from Afton Chemical having the same essential ingredients as HiTEC® 4130S, except that it also includes HiTEC® 4566 cold flow improver from Afton Chemical.
HiTEC® 4130E is a multi-functional fuel additive concentrate that was a predecessor to HiTEC® 4130W from Afton Chemical. It had the same detergent and cold flow improver as HiTEC® 4130W, but differed in some of the other ingredients. The samples using HiTEC® 4130E are at least 18 months old at the time of testing.
In each example, the additive concentrate was added to an ultralow diesel fuel available from ExxonMobil at a concentration specified in Table 1. The units “ptb” indicate a concentration in pounds per thousand barrels.
Conductivity in the samples was determined at room temperature and after storing the sample in a freezer until the temperature of the sample reached approximately −20° C. Results are reported in Table 1.
These data demonstrate that a conductivity benefit can be obtained in a low sulfur diesel fuel by the combination of a detergent and a cold flow improver, without the addition of any specialized antistatic agents. Controls 1-3 demonstrate that the addition of the cold flow improver alone to the fuel does not improve conductivity. Control 4 demonstrates that the detergent alone (in the form of an additive concentrate) also does not improve the conductivity of the fuel. Example 1-5, however, show that a conductivity improvement is seen when the detergent and cold flow improver are combined in a diesel fuel, regardless of whether they are added separately or as part of a pre-blended additive concentrate. In addition, as noted above, Applicants have discovered that this benefit is observed even if the detergent and cold flow improver have been mixed together for extended periods of time as in Examples 6-8.
Unlike the special antistatic agents like the Stadis® compounds, the present embodiments permit a conductivity benefit to be obtained using a single additive concentrate if desired, without requiring additional storage of handling procedures for the antistatic agents. In addition, the conductivity improvement is obtained without increasing the sulfur content of the additive concentrate or the fuel composition.
While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or can be presently unforeseen can arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they can be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.
Claims
1. An additive concentrate for a middle distillate fuel composition comprising an antistatic agent, said antistatic agent comprising, in combination, detergent and a cold flow improver.
2. The additive concentrate of claim 1, wherein said additive concentrate is substantially free of sulfur compounds.
3. The additive concentrate of claim 1, wherein said additive concentrate is substantially free of sulfur-containing antistatic agents.
4. The additive concentrate of claim 1, wherein said additive concentrate contains no more than 15 ppm of sulfur.
5. The additive concentrate of claim 1, wherein said fuel comprises a diesel fuel.
6. The additive of claim 1, wherein said detergent comprises a succinimide.
7. The additive concentrate of claim 1, wherein the cold flow improver comprises a alkyl phenol.
8. Use of the additive concentrate of claim 1 to provide a conductivity measure of at least 25 pS/m in a middle distillate fuel composition at the time and temperature of delivery of said fuel.
9. A middle distillate fuel composition comprising an antistatic agent, said antistatic agent comprising, in combination, a detergent and a cold flow improver.
10. The fuel composition of claim 9, wherein said fuel comprises a diesel fuel.
11. The fuel composition of claim 10, wherein said fuel contains no more than 15 ppm of sulfur.
12. The fuel composition of claim 11, wherein said diesel fuel is substantially free of sulfur-containing antistatic agents.
13. The fuel composition of claim 9, wherein said middle distillate fuel composition is substantially free of sulfur-containing conductivity improvers.
14. The fuel composition of claim 9, wherein said fuel has a conductivity of at least 25 pS/m at the time and temperature of delivery of said fuel.
15. The fuel composition of claim 9, wherein said detergent comprises a succinimide.
16. The fuel composition of claim 9, wherein said cold flow improver comprises a alkyl phenol.
17. Use of the fuel of claim 1 in a combustion apparatus.
18. A method for improving the conductivity of a middle distillate fuel composition comprising the step of adding an antistatic agent to said fuel in an amount sufficient to provide a conductivity of at least 25 pS/m at the time and temperature of delivery of said fuel, wherein said antistatic agent comprises, in combination, a detergent and a cold flow improver.
19. The method of claim 18, wherein said fuel composition comprises a diesel fuel.
20. The method of claim 19, wherein said diesel fuel is substantially free of sulfur-containing antistatic agents.
21. The method of claim 19, wherein said diesel fuel, after addition of said antistatic agent, contains no more than 15 ppm of sulfur.
22. The method of claim 18, wherein said detergent and said cold flow improver are part of a multifunctional additive concentrate.
23. A method of dispensing a middle distillate fuel composition comprising the steps of adding to a middle distillate fuel composition an antistatic agent in an amount sufficient to provide a conductivity of at least 25 pS/m at the time and temperature of delivery of said fuel, wherein said antistatic agent comprises, in combination, a detergent and a cold flow improver.
24. The method of claim 23, further comprising the step of dispensing said fuel prior to the conductivity dropping below 25 pS/m.
25. The method of claim 24, wherein said dispensing step comprises dispensing said middle distillate fuel composition into a bulk container.
26. The method of claim 23, wherein said detergent and said cold flow improver are pre-blended in an additive concentrate prior to addition to said fuel.
27. The method of claim 23, wherein said middle distillate fuel composition comprises a diesel fuel.
28. The method of claim 23, wherein said diesel fuel, after the addition of said antistatic agent, contains no more than 15 ppm of sulfur.
29. A method of reducing a risk of explosion from static discharge, comprising the steps of adding an antistatic agent to a middle distillate fuel composition in an amount sufficient to provide a conductivity of at least 25 pS/m at the time and temperature of delivery of said fuel, wherein said antistatic agent comprises, in combination, a detergent and a cold flow improver.
30. The method of claim 29, further comprising the step of dispensing said fuel prior to said conductivity dropping below 25 pS/m.
31. The method of claim 30, wherein said dispensing step comprises dispensing said middle distillate fuel composition into a bulk container.
32. The method of claim 29, wherein said detergent and said cold flow improver are pre-blended in an additive concentrate prior to addition to said fuel.
33. The method of claim 29, wherein said fuel composition comprises a diesel fuel.
34. The method of claim 33, wherein said diesel fuel is substantially free of sulfur-containing antistatic agents.
35. The method of claim 33, wherein said diesel fuel, after addition of the antistatic agent, contains no more than 15 ppm of sulfur.
Type: Application
Filed: Apr 19, 2007
Publication Date: Oct 23, 2008
Inventors: Alexander M. Kulinowski (Mechanicsville, VA), Timothy J. Brennan (Glenn Allen, VA)
Application Number: 11/788,200
International Classification: C10L 1/224 (20060101);
