CN116323874A - Use of diesel fuel compositions - Google Patents

Abstract

The present invention provides the use of a diesel fuel composition comprising (5) vol.% or more biodiesel for reducing deposit build-up in an Exhaust Gas Recirculation (EGR) system of a compression ignition internal combustion engine.

Description

Use of diesel fuel compositions

Technical Field

The present invention relates to the use of a diesel fuel composition comprising a biodiesel component for providing certain benefits in an Exhaust Gas Recirculation (EGR) system of a compression ignition engine. In particular, the invention relates to the use of the diesel fuel composition for reducing deposit accumulation in an exhaust gas recirculation system in a compression ignition engine.

Background

Exhaust Gas Recirculation (EGR) is a NOx emission control technology that is applicable to a variety of diesel engines ranging from light, medium and heavy duty diesel engine systems to two-stroke low speed marine engines. The configuration of the EGR system depends on the desired EGR rate and other requirements of the particular application. Most EGR systems include the following major hardware components: one or more EGR control valves, one or more EGR coolers, piping, flanges, and gaskets.

It has been found that EGR systems have a tendency to become contaminated with deposits that accumulate on various EGR hardware components. This is a particular problem with high pressure EGR systems. Deposits formed in the system can lead to increased NOx emissions and fuel consumption and in severe cases can lead to system failure by plugging the EGR valve or completely plugging the system. An oxidation catalyst and/or particulate filter may be installed prior to the EGR system to reduce EGR-fouling hydrocarbons and particulates from the exhaust gas, but this adds cost and complexity and is therefore not widely used by manufacturers. In the case of low pressure EGR, the DPF is located between the engine and the low pressure EGR system, so deposits are not such a problem in these constructions.

It is therefore desirable to provide a fuel-based solution that prevents the formation of deposits in the first place and is suitable for all EGR systems, regardless of the equipment employed by the manufacturer.

Biodiesel in the form of Fatty Acid Methyl Esters (FAME) is the most commonly used renewable fuel source in compression ignition (diesel) engines. FAME is typically derived from biological sources and is typically included to reduce the environmental impact of the fuel production and consumption process or to improve lubricity. Worldwide, there is a trend to increase the levels of FAME in diesel fuel, although this is limited in some markets due to concerns about the sustainability of FAME feedstock and due to engine/vehicle compatibility.

It has now been found that a surprising and heretofore unrecognized reduction in EGR deposit accumulation can be achieved by using a diesel fuel composition that contains an amount of a biodiesel component such as FAME.

Disclosure of Invention

According to the present invention there is provided the use of a diesel fuel composition comprising 5% by volume or more of biodiesel for reducing deposit build-up in an Exhaust Gas Recirculation (EGR) system of a compression ignition internal combustion engine.

According to another aspect of the present invention there is provided a method for reducing deposit build-up in an Exhaust Gas Recirculation (EGR) system of a compression ignition internal combustion engine, the method comprising the step of introducing into the engine a diesel fuel composition comprising 5% by volume or more biodiesel.

It has been found that the use of a diesel fuel composition comprising an amount of biodiesel component can provide reduced accumulation of deposits in the EGR system of a compression ignition internal combustion engine.

It has also been found that the use of a diesel fuel composition comprising an amount of biodiesel component can first prevent the formation of deposits in the EGR system and is applicable to all EGR systems, regardless of the equipment employed by the manufacturer.

Drawings

Fig. 1 is a graphical representation of EGR deposit mass results listed in table 2 below, wherein the circle marks represent individual test results and the diamond marks represent average results for each FAME fuel level tested in example 1.

Fig. 2 is a graphical representation of the average EGR deposit mass results listed in table 2 below for each FAME fuel level tested in example 1.

Fig. 3 is a graphical representation of the average percent reduction in EGR deposit mass relative to B0 listed in table 2 below for each FAME level tested in example 1.

Detailed Description

As used herein, there is provided the use of a diesel fuel composition comprising 5% by volume or more biodiesel for reducing deposit accumulation in an Exhaust Gas Recirculation (EGR) system of a compression ignition internal combustion engine.

In the context of this aspect of the invention, the term "reducing accumulation of deposits" includes any degree of reduction in accumulation of deposits. The reduction in deposit accumulation may be about 5% or more, preferably 10% or more, more preferably 20% or more, even more preferably 50% or more, in particular 70% or more, compared to the accumulation of deposits in an EGR system caused by a similar fuel formulation without the biodiesel component. As used herein, the term "reducing accumulation" also includes first preventing EGR deposit formation.

The present invention has been found to be particularly useful in the context of high pressure EGR systems, as these systems are more prone to deposit build-up than low pressure EGR systems.

It is also contemplated that the present invention may be used for the purpose of purging existing EGR deposits formed from conventional diesel fuel.

The first essential component herein is a biodiesel component. Biodiesel fuel is a fuel derived from biological materials.

The biodiesel component is present in the diesel fuel composition herein at a level of 5% v/v or greater, preferably 10% v/v or greater, more preferably in the range of 10% v/v to 50% v/v, even more preferably in the range of 10% v/v to 40% v/v and especially 20% v/v to 40% v/v. In a particularly preferred embodiment of the invention, the biodiesel component is present at a level in the range of 20% v/v to 30% v/v based on the total diesel fuel composition.

Biodiesel fuels suitable for use herein include any biologically derived oxygenate. There are processing routes to various types of oxygenates from biological materials, including alcohols, ketones, phenols, ethers, and esters, such as alkyl esters, including but not limited to methyl and ethyl esters.

A preferred biodiesel component for use herein is Fatty Acid Alkyl Esters (FAAE). It is known to include Fatty Acid Alkyl Esters (FAAE), particularly Fatty Acid Methyl Esters (FAME), in diesel fuel compositions, although not in the context of reducing deposit build-up in EGR systems. Examples of suitable FAAEs include rapeseed oil methyl ester (RME), palm Oil Methyl Ester (POME), soybean oil methyl ester (soy methyl ester), sunflower oil methyl ester, tallow methyl ester (tallow methyl ester) (TME), used edible oil methyl ester (UCOME), and the like. FAAEs are typically derived from biological sources and are typically included to reduce the environmental impact of fuel production and consumption processes or to improve lubricity.

FAAE (methyl esters, most commonly used in the context of diesel fuel) have been referred to as renewable diesel fuel (so-called "biodiesel" fuel). They contain long chain carboxylic acid molecules (typically 10 to 22 carbon atoms long),one end of each is connected with an alcohol molecule. Organically derived oils such as vegetable oils (including recovered vegetable oils) and animal fats (including fish oils) may be combined with alcohols (typically C ₁ To C ₅ Alcohols) are subjected to transesterification processes to form the corresponding fatty esters, typically mono-alkylated. The process is suitably acid or base catalysed, such as with base KOH, to convert the triglycerides contained in the oil from their glycerol backbone into the fatty acid component of the oil. FAAE can also be prepared from used edible oils and from fatty acids by standard esterification reactions.

In the present invention, the FAAE may be any alkylated fatty acid or mixture of fatty acids. The fatty acid component thereof is preferably derived from biological sources, more preferably from plant sources. They may be saturated or unsaturated. They may be linear or branched, cyclic or polycyclic. Suitably they will have from 6 to 30, preferably from 10 to 30, more suitably from 10 to 22 or from 12 to 24 or from 16 to 18 carbon atoms, including acid groups-CO ₂ H. Depending on its source, the FAAE will typically comprise a mixture of different fatty acid esters of different chain lengths.

The FAAE used in the present invention is preferably derived from natural fatty oils, such as tall oil, rapeseed oil, palm oil or soybean oil.

FAAE is preferably C ₁ To C ₅ Alkyl esters, more preferably methyl, ethyl, propyl (suitably isopropyl) or butyl esters, still more preferably methyl or ethyl esters, especially methyl esters. In one embodiment herein, the FAAE is selected from the group consisting of methyl esters of Palm Oil (POME) and rapeseed oil (RME) and mixtures thereof.

In general, it may be natural or synthetic, refined or unrefined ("crude").

FAAE may contain impurities or byproducts due to the manufacturing process.

FAAE suitably complies with specifications applied to the remainder of the fuel composition and/or to the base fuel to which it is added, while keeping in mind the intended use of the composition (e.g., in which geographic region and at what time of year). Specifically, the flash point (IP 34) of FAAE is preferably greater than 101 ℃; at 4A kinematic viscosity (IP 71) at 0℃of 1.9 to 6.0mm ² S, preferably 3.5 to 5.0mm ² S; density at 15℃of 845 to 910kg/m (IP 365, EN ISO 12185 or EN ISO 3675) ³ Preferably 860 to 900kg/m ³ The method comprises the steps of carrying out a first treatment on the surface of the A water content (IP 386) of less than 500ppm; t95 below 360 ℃ (temperature at which 95% of the fuel has evaporated, measured according to IP 123); an acid value (IP 139) of less than 0.8mgKOH/g, preferably less than 0.5mgKOH/g; and an iodine value (IP 84) of less than 125, preferably less than 120 or less than 115 grams of iodine (I) per 110 grams of fuel ₂ ). It also preferably contains less than 0.2% w/w free methanol, less than 0.02% w/w free glycerol and greater than 96.5% w/w esters (e.g. by Gas Chromatography (GC)). In general, for fatty methyl esters used as diesel fuel, FAAE may preferably comply with european specification EN14214.

Two or more FAAEs may be added to the diesel fuel composition according to the invention either alone or as a pre-prepared blend.

FAAEs are typically incorporated into diesel fuel compositions as a blend (i.e., a physical mixture) and optionally with one or more other fuel components (such as diesel base fuel) and optionally with one or more fuel additives. FAAE are conveniently incorporated into diesel fuel compositions prior to incorporation of the composition into diesel engines operated with the fuel composition.

In addition to FAAE, a preferred fuel component for use in the diesel fuel compositions herein is a paraffinic gas oil. The paraffinic gas oil suitable for use in the present invention may be derived from any suitable source as long as it is suitable for use in a diesel fuel composition.

Suitable paraffinic gas oils include, for example, fischer-Tropsch derived gas oils and gas oils derived from Hydrotreated Vegetable Oils (HVOs), and mixtures thereof.

The preferred paraffinic gas oil for use herein is a Fischer-Tropsch derived gas oil fuel. The paraffinic nature of a Fischer-Tropsch derived gas oil means that a diesel fuel composition containing it will have a high cetane number compared to conventional diesel.

While Fischer-Tropsch derived gas oils are the preferred paraffinic gas oils for use herein, the term "paraffinic gas oil" as used herein also includes those paraffinic gas oils derived from the Hydrotreatment (HVO) of vegetable oils. The HVO process is based on refinery technology. In this process, hydrogen is used to remove oxygen from triglyceride vegetable oil molecules and break down the triglycerides into three separate chains, thereby producing paraffins.

When present, the paraffinic gas oil (i.e. the Fischer-Tropsch derived gas oil, the hydrogenated vegetable oil derived gas oil) will preferably consist of at least 95% w/w, more preferably at least 98% w/w, even more preferably at least 99.5% w/w and most preferably at most 100% w/w of a paraffinic component, preferably isoparaffins and normal paraffins.

By "Fischer-Tropsch derived" is meant that the fuel or base oil is or is derived from the synthesis product of a Fischer-Tropsch condensation process. The term "non-Fischer-Tropsch derived" will be interpreted accordingly. Fischer-Tropsch derived fuels may also be referred to as GTL (gas to liquid) fuels.

The fischer-tropsch reaction converts carbon monoxide and hydrogen into longer chain hydrocarbons (typically paraffins):

n(CO+2H ₂ )＝(-CH ₂ -) _n +nH ₂ o+ heat, in the presence of a suitable catalyst and typically at elevated temperature (e.g. 125 ℃ to 300 ℃, preferably 175 ℃ to 250 ℃) and/or pressure (e.g. 5 bar to 100 bar, preferably 12 bar to 50 bar). If desired, a ratio of hydrogen to carbon monoxide other than 2:1 may be used.

The carbon monoxide and hydrogen may themselves be derived from organic or inorganic, natural or synthetic sources, typically from natural gas or organically derived methane. Recently, attempts are being made to obtain such routes for synthesis gas carbon monoxide from carbon dioxide in order to obtain greenhouse gas benefits.

The gas oil, kerosene fuel and base oil products may be obtained directly from the fischer-tropsch reaction or indirectly, for example by fractionation of the fischer-tropsch synthesis product or from a hydrotreated fischer-tropsch synthesis product. Hydrotreating may involve hydrocracking to adjust the boiling range (see for example GB2077289 and EP 0147873) and/or hydroisomerisation, which may improve cold flow properties by increasing the ratio of branched paraffins. EP0583836 describes a two-step hydroprocessing process in which a fischer-tropsch synthesis product is first hydroconverted under conditions in which substantially no isomerisation or hydrocracking occurs (which hydrogenates the olefins and oxygenates), and then at least part of the resulting product is hydroconverted under conditions in which hydrocracking and isomerisation occur, yielding a substantially paraffinic hydrocarbon fuel or oil. The desired diesel fuel fraction may then be separated, for example by distillation.

Other post-synthesis treatments, such as polymerization, alkylation, distillation, cracking-decarboxylation, isomerization and hydro-reforming, may be used to alter the properties of the Fischer-Tropsch condensation products, as described for example in US-A-4125566 and US-A-447955.

Typical catalysts for the Fischer-Tropsch synthesis of paraffinic hydrocarbons comprise a metal of group VIII of the periodic Table as the catalytically active component, in particular ruthenium, iron, cobalt or nickel. Suitable such catalysts are described, for example, in EP 0583836.

An example of a Fischer-Tropsch based process is SMDS (Shell middle distillate Synthesis (Shell Middle Distillate Synthesis)) described in van der Burgt et al, "The Shell Middle Distillate Synthesis Process" (see above). This process (sometimes also referred to as shell "gas-to-liquid" or "GTL" technology) produces diesel range products by converting natural gas (principally methane) derived synthesis gas into heavy long chain hydrocarbon (paraffin) waxes, which can then be hydroconverted and fractionated to produce liquid transportation fuels such as gas oil and kerosene. Several versions of the SMDS process using a fixed bed reactor for the catalytic conversion step are currently in use in Pearl GTL of both civil and cartalaska harbors in malaysia. Kerosene and (gas) oils prepared by the SMDS process are commercially available, for example, from Royal Dutch/Shell Group of Companies.

With the fischer-tropsch process, the fischer-tropsch derived gas oil is substantially free of sulphur and nitrogen or has undetectable levels of sulphur and nitrogen. Compounds containing these heteroatoms tend to act as poisons for fischer-tropsch catalysts and are therefore removed from the synthesis gas feed. In addition, the process generally operates to produce little or no aromatic components.

For example, the aromatic content of the Fischer-Tropsch gas oil will typically be less than 1% w/w, preferably less than 0.5% w/w, and more preferably less than 0.1% w/w, as determined for example by ASTM D4629.

Generally, fischer-tropsch derived fuels have relatively low levels of polar components, particularly polar surfactants, as compared to petroleum derived fuels, for example. It is believed that this may help improve defoaming and defogging properties. Such polar components may include, for example, oxygen-containing compounds and sulfur-and nitrogen-containing compounds. The low level of sulfur in the fischer-tropsch derived fuel generally represents a low level of both oxygenates and nitrogen containing compounds, as they are removed by the same treatment process.

The preferred Fischer-Tropsch derived gas oil fuel for use herein is a liquid hydrocarbon middle distillate fuel having a distillation range similar to that of petroleum derived diesel, typically in the range 160 ℃ to.400 ℃, preferably having a T95 of 360 ℃ or less. Also, the undesirable fuel components (such as sulfur, nitrogen, and aromatics) content of fischer-tropsch derived fuels tend to be low.

Preferred Fischer-Tropsch derived gas oil fuels will typically have a g/cm at 15℃of from 0.76 to 0.80, preferably from 0.77 to 0.79, more preferably from 0.775 to 0.785g/cm ³ As measured by EN ISO 12185.

Preferred Fischer-Tropsch derived gas oil fuels for use herein have a cetane number (ASTM D613) of greater than 70, suitably 70 to 85, most suitably 70 to 77.

The preferred Fischer-Tropsch derived gas oil fuel for use herein has a length of 2.0mm at 40 DEG C ² /s to 5.0mm ² /s, preferably 2.5mm ² /s to 4.0mm ² Kinematic viscosity in the range of/s (as measured according to ASTM D445).

Preferred Fischer-Tropsch derived gas oils for use herein have a sulphur content (ASTM D2622) of 5ppmw (parts per million by weight) or less, preferably 2ppmw or less.

The preferred Fischer-Tropsch derived gas oil fuel for use in the present invention is produced as a unique finished product which is suitable for sale and use in applications requiring the specific characteristics of the gas oil fuel. In particular, it exhibits a distillation range falling within the ranges typically associated with Fischer-Tropsch derived gas oil fuels, as described above.

The fuel composition for use in the present invention may comprise a mixture of two or more Fischer-Tropsch derived gas oil fuels.

When present, the Fischer-Tropsch derived component (i.e. the Fischer-Tropsch derived gas oil) as used herein will preferably comprise not more than 3% w/w, more preferably not more than 2% w/w, even more preferably not more than 1% w/w of naphthenes (naphthenes) based on the weight of the Fischer-Tropsch derived component.

When present, the Fischer-Tropsch derived component (i.e. Fischer-Tropsch derived gas oil) as used herein preferably comprises no more than 1% w/w, more preferably no more than 0.5% w/w olefin, based on the weight of the Fischer-Tropsch derived component.

The diesel fuel composition for use in the present invention described herein is particularly suitable for use as a diesel fuel and, due to excellent low temperature flow properties, may be used for arctic applications as winter grade diesel fuel.

For example, a cloud point of-10 ℃ or less (EN 23015) or a cold filter point (CFPP) of-20 ℃ or less (as measured by EN 116) is possible for the fuel compositions herein.

In addition to the biodiesel fuel component, the diesel fuel composition described herein may also comprise a diesel base fuel.

The diesel base fuel may be any petroleum derived diesel suitable for use in an internal combustion engine, such as petroleum derived low sulfur diesel containing < 50ppm sulfur, for example Ultra Low Sulfur Diesel (ULSD) or Zero Sulfur Diesel (ZSD). Preferably, the low sulfur diesel fuel contains < 10ppm sulfur.

The density of the petroleum derived low sulfur diesel fuel preferably used in the present invention is typically 0.78g/cm at 15℃ ³ To 0.865g/em ³ Preferably 0.80g/cm ³ To 0.845g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the A cetane number (ASTM D613) of at least 51; and a kinematic viscosity at 40℃of 1.5mm (ASTM D445) ² /s to 4.5mm ² S, preferably 2.0mm ² /s to 4.0mm ² /s, more preferably 2.2mm ² /s to 3.7mm ² /s。

In one embodiment, the diesel base fuel is conventional petroleum derived diesel.

In general, in the context of the present invention, the fuel composition may be supplemented with a fuel additive.

The inventors have found that it is particularly advantageous to include a Deposit Control Additive (DCA) package in the diesel fuel composition in addition to the biodiesel component from the standpoint of reducing the accumulation of deposits in the EGR system.

Unless otherwise indicated, the (active matter) concentration of each such additive in the fuel composition is preferably at most 10000ppmw, more preferably in the range of from 5ppmw to 1000ppmw, advantageously from 75ppmw to 300ppmw, such as from 95ppmw to 150ppmw. Such additives may be added at various stages in the production of the fuel composition; those added to the base fuel at the refinery may be selected, for example, from antistatic agents, pipeline drag reducers, middle Distillate Flow Improvers (MDFI) (e.g., ethylene/vinyl acetate copolymers or acrylate/maleic anhydride copolymers), lubricity enhancers, antioxidants, and wax anti-settling agents.

The fuel composition may comprise DCA, which refers to an agent (suitably a surfactant) that may be used to remove and/or prevent combustion related deposits from accumulating within the engine, particularly in the fuel injection system, such as in the injector nozzle. Such materials are sometimes referred to as dispersant additives. When the fuel composition comprises DCA, the preferred concentration is in the range of 20ppmw to 500ppmw active matter detergent, more preferably 40ppmw to 500ppmw, most preferably 40ppmw to 300ppmw or 100ppmw to 300ppmw or 150 to 300ppmw, based on the total fuel composition. DCA for diesel fuels is known and commercially available. Examples of suitable DCA additives include polyolefin substituted succinimides or succinamides of polyamines, such as polyisobutylene succinimides or polyisobutylene amine succinamides, aliphatic amines, mannich bases or amines, and polyolefin (e.g., polyisobutylene) maleic anhydrides. Particularly preferred are polyolefin substituted succinimides, such as polyisobutylene succinimides.

Other components that may be incorporated as fuel additives, for example in combination with detergents, including lubricity enhancers; demisting agents, such as alkoxylated phenol formaldehyde polymers; defoamers (e.g., commercially available polyether modified polysiloxanes); ignition promoters (cetane improvers) (e.g., 2-ethylhexyl nitrate (EHN), cyclohexyl nitrate, di-t-butyl peroxide, and those disclosed in US4208190, column 2, line 27 to column 3, line 21); rust inhibitors (e.g., propane-1, 2-diol half-ester of tetrapropenyl succinic acid, or polyol ester of succinic acid derivative having an unsubstituted or substituted aliphatic hydrocarbon group containing 20 to 500 carbon atoms on at least one alpha-carbon atom thereof, such as pentaerythritol diester of polyisobutylene-substituted succinic acid); a resist; a deodorant; an antiwear additive; antioxidants (e.g., phenols such as 2, 6-di-tert-butylphenol, or phenylenediamines such as N, N' -di-sec-butyl-p-phenylenediamine); a metal deactivator; a static dissipative additive; and mixtures thereof.

Preferably, the additive contains an antifoaming agent, more preferably in combination with a rust inhibitor and/or a corrosion inhibitor and/or a lubricating additive.

It is particularly preferred to include a lubricity enhancer in the fuel composition, especially when it has a low (e.g., 500ppmw or less) sulfur content. The lubricity enhancer is suitably present in a concentration of from 50ppmw to 1000ppmw, preferably from 100ppmw to 1000ppmw, based on the total fuel composition.

The (active matter) concentration of any defogger in the fuel composition will preferably be in the range of from 1ppmw to 20ppmw, more preferably from 1ppmw to 15ppmw, still more preferably from 1ppmw to 10ppmw and advantageously from 1ppmw to 5 ppmw. The (active matter) concentration of any ignition improver present will preferably be 600ppmw or less, more preferably 500ppmw or less, conveniently 300 to 500ppmw.

The invention may be particularly applicable where the fuel composition is used or intended for use in a direct injection diesel engine, such as a rotary pump, an in-line pump, a unit pump, an electronic unit injector or a common rail type, or for use in an indirect injection diesel engine. The fuel composition may be suitable for use in heavy and/or light duty diesel engines, as well as engines designed for either on-road or off-road use.

In order to be suitable for at least the above uses, the diesel fuel composition of the invention preferably has one or more of the following features:

-a kinematic viscosity at 40 ℃ of 1.9mm ² /s or greater, more preferably 1.9mm ² /s to 4.5mm ² Ranges of/s;

-density of 800kg/m ³ Or greater, more preferably at 800kg/m ³ To 860kg/m ³ Even more preferably 800kg/m ³ To 845kg/m ³ Is within the range of (2);

-T95 is 360 ℃ or less;

-cloud point in the range of 0 ℃ to-13 ℃, more preferably-5 ℃ to-8 ℃;

-CFPP in the range of-8 ℃ to-30 ℃, more preferably-15 ℃ to-20 ℃.

The invention is illustrated by the following non-limiting examples.

Examples

Example 1

Four different fuels were used in the examples herein.

One fuel is conventional diesel fuel, CEC RF79-07 (diesel B0). Physical properties of the conventional diesel fuel (diesel B0) used in the examples are shown in table 1 below. As used herein, "diesel B0" refers to a diesel base fuel containing zero biofuel components. The biofuel component is palm oil methyl ester-POME.

The second, third and fourth test fuels were diesel fuel compositions designed to contain 10%, 20% or 30% biofuel component. In fact, under normal experimental error, the actual biomass content of the fuel was 10.5%, 20.6% and 29.9%, respectively. The base diesel fuel to which the biofuel was added was a diesel fuel that meets the EN590 diesel fuel specification and was a reference fuel designated CEC RF 79-07. Likewise, the biofuel component is a POME FAME component. Analytical properties of the diesel and FAME blends B10, B20, B30 fuels used in the examples are shown in table 1 below.

Test square speed

The engine used in the examples was of a standard construction PSA DV 6.6 l Euro 5 engine, of one type of a plurality of light bus models installed in europe. The clean EGR system is weighed and then mounted to the engine.

The test was run continuously for 24 hours at 2500rpm and 5kW (19 Nm) test conditions. The engine coolant temperature was controlled at 37 ℃ throughout the test. When the test is complete, the engine is removed and all EGR components are weighed. All EGR components are then photographed and the entire EGR system is then cleaned using a solvent and sonic bath to remove deposits. The cleaned EGR system is then re-weighed and then fitted to the engine for the next test. In addition to performing two tests on B0 at the beginning of the sequence to ensure an acceptable level of repeatability, a series of tests designed to avoid repeated repetition of any fuel was performed. The remainder of each fuel was repeatedly distributed throughout the test sequence to create a balanced test sequence. Four tests were performed with B0 fuel, two tests were performed for each of B10, B20 and B30. The test sequence and EGR deposit mass results are given in table 2 below, and the results are shown in fig. 1 to 3.

Table 2: fuel test sequence and EGR deposit mass results

Discussion of the invention

As can be seen from the results in table 2 and the graphs in fig. 1 to 3, in the case of the FAME-containing fuel, the amount of deposit formed on the EGR component is significantly reduced as compared with the conventional diesel B0 fuel, and the reduction increases with an increase in the FAME level. In the case of B10 diesel fuel, the deposit mass formed on the EGR component is 22.0% lower than in the case of B0 diesel fuel. In the case of B20 fuel, the difference from B0 was 27.2%, whereas in the case of B30 fuel, the difference from B0 was 28.8%.

Claims (10)

1. Use of a diesel fuel composition comprising 5% by volume or more of biodiesel for reducing deposit accumulation in an Exhaust Gas Recirculation (EGR) system of a compression ignition internal combustion engine.

2. The use of claim 1, wherein the diesel fuel composition comprises 10 to 50% by volume biodiesel based on the diesel fuel composition.

3. The use according to claim 1 or 2, wherein the diesel fuel composition comprises 20 to 40% by volume biodiesel based on the diesel fuel composition.

4. A use according to any one of claims 1 to 3, wherein the biodiesel is selected from fatty acid alkyl esters.

5. The use according to any one of claims 1 to 4, wherein the biodiesel is fatty acid methyl ester.

6. Use according to any one of claims 1 to 5, wherein the biodiesel is rapeseed oil methyl ester (RME), palm Oil Methyl Ester (POME), soybean oil methyl ester, sunflower oil methyl ester, tallow Methyl Ester (TME), used edible oil methyl ester (UCOME) and mixtures thereof.

7. The use according to any one of claims 1 to 6, wherein the diesel fuel composition further comprises a Deposit Control Additive (DCA) additive package.

8. The use of any one of claims 1 to 7, wherein the diesel fuel composition further comprises a diesel base fuel.

9. The use according to any one of claims 1 to 8, wherein the diesel fuel composition further comprises a paraffinic base fuel selected from the group consisting of hydrotreated vegetable oils, fischer-tropsch derived base fuels and mixtures thereof.

10. A method for reducing deposit accumulation in an Exhaust Gas Recirculation (EGR) system of a compression ignition internal combustion engine, the method comprising the step of introducing into the engine a diesel fuel composition comprising 5% by volume or more biodiesel.

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