JP5179700B2 - Diesel fuel composition - Google Patents

Description

  The present invention relates to a diesel fuel composition, a process for its production and its use in diesel engines, and the use of certain types of fuels in diesel fuel compositions.

  A typical diesel fuel composition contains a liquid hydrocarbon middle distillate fuel oil having a boiling range of about 150-400 ° C. Examples of these fuels include the Fischer-Tropsch methane condensation process, such as the process known as shell middle distillate synthesis (van der Burgt et al., “The Shell Middle Distilate Synthesis Process”, Washington, 5th November 1985. The product distributed in the Synfuels Worldwide Symposium; and also see the November 1989 publication of the same title from Shell International Petroleum Company Ltd., London, UK). These Fischer-Tropsch derived gas oils are low in undesirable fuel components such as sulfur, nitrogen and aromatics and tend to reduce automotive emissions. This derived gas oil is usually blended with other diesel base fuels such as petroleum derived gas oils at a concentration of, for example, 10-30% w / w to modify the properties of the base fuel.

Compression ignition (diesel) engines running on conventional diesel fuel can suffer from deposition of combustion-related deposits in fuel injection systems, particularly injector nozzles. Such injector contamination may impair engine performance. To reduce contamination, the fuel may contain detergent-containing additives or may be adjusted so that the proportion of heavy components in the fuel is reduced to the end point.
GB-B-2077289 EP-A-0147873 EP-A-0583836 EP-A-1101813 WO-A-97 / 14768 WO-A-97 / 14769 WO-A-00 / 20534 WO-A-00 / 20535 WO-A-00 / 11116 WO-A-00 / 11117 WO-A-01 / 83406 WO-A-01 / 83641 WO-A-01 / 83647 WO-A-01 / 83648 US-A-6204426 GB-A-960493 EP-A-0147240 EP-A-0482253 EP-A-0613938 EP-A-0557561 WO-A-98 / 42808 Van der Burg et al., “The Shell Middle Distillate Synthesis Process”, Washington, November 1985, paper distributed at the 5th Synfuels World Symposium.

  It has now been found that Fischer-Tropsch derived fuel can itself contribute to the reduction and / or reversal of injector contamination. Accordingly, fuel compositions containing such components can be used to help maintain and / or improve engine cleanliness.

In a first aspect of the present invention, diesel fuel is used for the purpose of reducing combustion-related deposits in a diesel engine after introduction of a fuel composition and / or for the purpose of removing previously formed combustion-related deposits. A method of using Fischer-Tropsch gas oil in the composition is provided.
Fischer-Tropsch derived gas oil may alternatively or additionally be used for the purpose of removing previously formed combustion-related deposits (ie, to “clean” the engine).

  In the present invention, “reducing or reducing” includes complete prevention, and “removing” includes both complete removal and partial removal. “Using” a Fischer-Tropsch derived gas oil in a fuel composition conveniently blends fuel into the composition, usually along with one or more other fuels, prior to introducing the composition into the engine. (Ie, a physical mixture).

  Fischer-Tropsch derived gas oil must be suitable for diesel fuel. Thus, the components of this gas oil (or most of the gas oil, eg 95% w / w or more) have boiling points in the range of normal diesel fuel (“gas oil”), about 150-400 ° C. or 170-370 ° C. Must have a boiling point. Preferably, the 90% w / w distillation temperature is 300-370 ° C.

“Fischer-Tropsch induction” means that the fuel is a synthetic product of the Fischer-Tropsch condensation process or a derivative thereof. The Fischer-Tropsch reaction is usually carried out in the presence of a suitable catalyst at elevated temperatures (eg 125 to 300 ° C., preferably 175 to 250 ° C.) and / or high pressures (eg 5 to 100 bar, preferably 12 to 50 bar). Carbon oxide and hydrogen are converted to long chain, usually paraffinic hydrocarbons. If desired, hydrogen: carbon monoxide ratios other than 2: 1 may be employed.
n (CO + 2H ₂ ) = (— CH ₂ —) _n + nH ₂ O + heat

  The gas oil product can be obtained directly in this reaction, or it can be obtained indirectly, for example, by rectification of a Fischer-Tropsch synthesis product or from a hydrogenated Fischer-Tropsch synthesis product. Hydrotreating can be accomplished by hydrocracking to adjust the boiling range (eg GB-B-20207289 and EP-A-0147873) and / or by increasing the proportion of branched paraffins and improving the cold flow characteristics. Includes In EP-A-0583836, a Fischer-Tropsch synthesis product is first subjected to hydroconversion under conditions that do not substantially undergo isomerization or hydrocracking (olefinic and oxygen-containing components are converted to hydrogen. And then hydroconverting at least a portion of the resulting product under conditions such that hydrocracking and isomerization occurs to obtain a substantially baraffinic hydrocarbon fuel. A method of chemical conversion is described. The desired gas oil fraction can be substantially separated, for example, by distillation.

To modify the properties of the Fischer-Tropsch condensation product, polymerization, alkylation, distillation, cracking-decarboxylation, isomerization and hydrogenation, for example as described in US Pat. No. 4,125,566 and US Pat. No. 4,478,955 Other post-synthesis treatments such as modification may be employed.
A catalyst for Fischer-Tropsch synthesis of a paraffinic hydrocarbon usually contains a metal of Group VIII of the periodic table, particularly ruthenium, iron, cobalt or nickel, as a catalytically active component. Such suitable catalysts are described, for example, in EP-A-0583836 (pages 3, 4).

  The basis of the Fischer-Tropsch method is SMDS (Shell Middle Distillation Synthesis) described in the above-mentioned van der Burgt et al., “The Shell Middle Distillate Synthesis Process”. This process produces a middle distillate range product by converting natural gas (primarily methane) derived syngas to heavy long chain hydrocarbon (paraffin) wax, which is then hydroconverted, The rectification is to obtain a liquid fuel for transportation such as gas oil that can be used in a diesel fuel composition. The revised SMDS process, which uses a fixed bed reactor for the catalytic conversion process, is currently used in Bintulu, Malaysia, and its products are used in petroleum-derived gas oil blends in commercial automotive fuels.

  Gas oil produced by the SMDS method is commercially available from, for example, Royal Dutch / Shell group companies. Other examples of Fischer-Tropsch derived gas oils are EP-A-0583836, EP-A-1101813, WO-A-97 / 14768, WO-A-97 / 14769, WO-A-00 / 20534, WO- A-00 / 20535, WO-A-00 / 11116, WO-A-00 / 11117, WO-A-01 / 83406, WO-A-01 / 83641, WO-A-01 / 83647, WO-A- 01/83648 and US-A-6204426.

  The Fischer-Tropsch derived gas oil according to the invention is suitably at least 70% w / w, preferably at least 80% w / w, more preferably at least 90% w / w, most preferably at least 95% w / w. Consisting of an isomeric and linear paraffin. The weight ratio of isoparaffin to normal paraffin is preferably greater than 0.3 and may be 12 or less, preferably 2-6. The actual value of this ratio is measured in part by the hydroconversion process used for the production of gas oil from Fischer-Tropsch products. Some cyclic paraffin may also be present.

  According to the Fischer-Tropsch process, Fischer-Tropsch derived gas oil is essentially free of sulfur and nitrogen or at undetectable levels. These compounds containing heteroatoms tend to act as poisons for Fischer-Tropsch catalysts and are therefore removed from the synthesis gas feed. Furthermore, this process does not produce or substantially does not produce aromatic components in normal operation. The aromatic content in Fischer-Tropsch gas oil is usually less than 1% w / w, preferably less than 0.5% w / w, more preferably 0.1% w / w as measured by ASTM D4629. Is less than.

The Fischer-Tropsch derived gas oil used in the present invention usually has a density of 0.76 to 0.79 g / cm ³ at 15 ° C. and a cetane number (ASTM D613) of more than 70, preferably 74 to 85, the kinematic viscosity is 2.0 to 4.5 cSt at 40 ° C., preferably 2.5 to 4.0 cSt, more preferably 2.9 to 3.7 cSt, and the sulfur content is 5 ppmw (1 million parts) Per weight part) or less.

  Preferred products are those that use a hydrogen / carbon monoxide ratio of less than 2.5, preferably less than 1.75, more preferably 0.4 to 1.5, and ideally a Fischer It is produced by a Tropsch methane condensation reaction. Preferably, those obtained from hydrocracked Fischer-Tropsch synthesis products (for example described in GB-B-2077289 and / or EP-A-0147873), more preferably EP-A-0583836 (supra The product of the two-stage hydroconversion process as described in In the latter case, preferred features of the hydroconversion process are those disclosed in EP-A-0583836, pages 4-6 and in the examples.

  The level of combustion related deposits in a diesel engine may be measured in a fuel injection system with reference to the extent of injector nozzle contamination. The degree of contamination of the nozzle can be evaluated in many ways, for example by measuring the mass of deposits in the contamination nozzle or measuring the fluid flow rate of the contamination nozzle relative to the clean nozzle. It's okay.

  Appropriate testing is the extent of nozzle contamination (injector) under steady state conditions of the engine, for example as a result of using the fuel composition in a suitable diesel engine, relative to changes in the flow rate of air in one or more nozzles. The pollution index% shape is convenient). These results are conveniently averaged over all of the engine injector nozzles. A suitable test protocol using an indirect injection diesel engine for the experimental example is described below. Again, the CBC reference test method F-23-T00, which includes an injector nozzle airflow measurement method, may also be used for engine contamination assessment.

The present invention uses or is intended for use in direct injection diesel engines such as rotary pumps, in-line pumps, unit pumps, electronic unit injectors or ordinary rail type, or indirect injection diesel engines. If available. This fuel composition may be suitable for heavy and / or light diesel engines.
The amount of Fischer-Tropsch derived gas oil used is 0.5-100% w / w, suitably 1-60% w / w, preferably 5-50% w / w, based on the total diesel fuel composition. Preferably it may be 10-30% w / w. It may be desirable for the composition to contain Fischer-Tropsch gas oil of 8% w / w or more, more preferably 10% w / w or more, most preferably 20% w / w or more.

  The other fuel component in the composition may typically be a conventional diesel fuel including a liquid hydrocarbon middle distillate fuel oil, such as petroleum derived gas oil. The boiling range of such fuel components is within a normal diesel range of 150 to 400 ° C., depending on the grade and application.

  In order to achieve reduction and / or removal of engine deposits, the diesel fuel composition comprises Fischer-Tropsch derived gas oil as an essential component. In other words, the composition is a large percentage (preferably 99% w / w or more, preferably 99.5% w / w or more, most preferably 99.8% w / w or more, preferably to the fuel composition, Furthermore, Fischer-Tropsch derived gas oil (which means 100% w / w or less) is optionally added to one or more diesel fuels known in the art but not found in other diesel fuels It may be included with the product.

The sulfur content in the overall fuel composition is low or very low, for example 1000 ppmw (parts per million) or less, preferably 500 ppmw or less, most preferably 100, 50 or even 10 ppmw or less. The cetane number (ASTM D613) is 40 to 85, more preferably 45 to 75. The density is usually 0.75 to 0.9 g / cm ³ at 15 ° C., preferably 0.8 to 0.85 g / cm ³ .

  Fischer-Tropsch derived gas oils are particularly fuels or fuel blends that produce a relatively high level of combustion-related deposits, such as a fuel with a relatively high end point and / or a relatively high level of aromatic content. And / or a fuel or blend that causes an achievable air flow rate at one or more engine nozzles to decrease by more than 35, 40, or 45%, as measured using, for example, the following test protocol after 3 hours of engine running It may be used to improve performance.

  In general, diesel fuel compositions may or may not contain additives, but preferably contain detergents. This is because the detergent improves the purification effect of the Fischer-Tropsch derived gas oil. Accordingly, the first aspect of the present invention is for the purpose of reducing combustion related deposits in a diesel engine after introduction of a fuel composition and / or for the purpose of removing previously formed combustion related deposits. Including the use of Fischer-Tropsch derived gas oil and detergents in the diesel fuel composition.

  “Detergent” means an agent (preferably a surfactant) that can act to remove and / or prevent deposition of combustion related deposits in the engine, particularly in fuel injection systems such as injector nozzles. . Such materials are sometimes referred to as dispersible additives.

  Fischer-Tropsch derived gas oil, or a combination of Fischer-Tropsch derived gas oil and detergent, preferably contains engine contamination (as outlined above), Fischer-Tropsch derived gas oil, Others not included are contained in a concentration sufficient to reduce by at least 5%, preferably at least 8%, more preferably at least 10%, most preferably at least 20% compared to the same fuel composition. Alternatively, this reduction may include a fuel composition that contains no Fischer-Tropsch derived fuel or less than 1% w / w and does not contain detergent or less than 50 or even 20 ppmw (same or equivalent conditions) It may be compared to the degree of engine contamination obtained using (below).

  Fischer-Tropsch derived gas oil, or a combination of Fischer-Tropsch derived gas oil and detergent may contain other diesel fuels (usually containing no Fischer-Tropsch derived fuel or less than 1% w / w or detergent When running with a Fischer-Tropsch fuel-containing composition, followed by a Fischer-Tropsch fuel-containing composition, particularly during the previous run More preferably, it contains a concentration sufficient to remove at least a portion of the combustion-related deposits deposited therein. This concentration is preferably at least 5%, more preferably at least 10%, most preferably at least 15, 20, 25 or 30% removal of previously formed injector deposits (eg, measured as described above). The concentration is sufficient to

  The removal of combustion-related deposits may be achieved with a Fischer-Tropsch fuel-containing composition, for example, at the same time as the deposit accumulation time, more preferably 75% of the deposit accumulation time, even more preferably 50% or even more. Can be achieved by running for 40% or 30% time, conveniently under equivalent conditions. Ideally, removal of at least a portion of the combustion-related deposits is accomplished by running the engine with a Fischer-Tropsch fuel-containing composition within 5 hours, preferably within 3 hours, more preferably within 2 hours. .

  When the fuel composition contains a detergent, the detergent concentration is preferably from 20 to 500 ppmw, more preferably from 40 to 500 ppmw, most preferably from 40 to 300 ppmw or from 100 to 300 ppmw as active detergent, based on the total fuel composition. It is in the range of 150 to 300 ppmw. In the case of the most commercially available detergent-containing diesel fuel additive, the additive is at a level higher than the recommended standard single treatment rate, for example 1.2 to 3 times the standard single treatment rate, preferably 1.5. Up to 2.5 times, for example about 2 times, is taken up. To help reduce or prevent further engine contamination and / or power loss, at a low detergent level (eg 0.5-1.2 times the standard single treatment rate, preferably the same rate as the standard single treatment rate) May be used.

  Examples of detergents suitable for use in the present invention include polyolefin substituted succinimides or polyamine succinamides such as polyisobutylene succinimide or polyisobutylene amine succinamide, aliphatic amines, Mannich bases or amines and polyolefins (eg polyisobutylene) anhydrous Maleic acid is mentioned. Succinimide dispersible additives are described, for example, in GB-A-960493, EP-A-0147240, EP-A-0482253, EP-A-0613938, EP-A-0557561 and WO-A-98 / 42808. . Particularly preferred are polyolefin substituted succinimides such as polyisobutylene succinimide.

  Detergent-containing diesel fuel additives are commercially available from, for example, Infineum (eg F7661 and F7685) and Octel (eg OMA 4130D).

  In addition to the Fischer-Tropsch derived gas oil, the fuel composition may contain other components if a detergent is available. These components are usually incorporated into the fuel additive, for example in combination with a detergent. Lubricant enhancers such as, for example, EC 832 and PARADYNE ™ (from Infineum), HITEC ™ E580 (from Ethyl Corporation) and VEKTRON ™ 6010 (from Infineum), and as obtained from Lubrizol Chemical Company Amide-based additives such as LZ 539C; dehazers such as alkoxylated phenol formaldehyde polymers such as NALCO ™ EC5462A (formerly 7D07) (from Nalco), and TOLAD ™ 2683 (from Petrolite) Commercial products such as antifoams (eg TEGOPREN ™ 5851 and Q 25 as commercial products of polyether-modified polysiloxanes) 07 (from Dow Corning), SAG ™ TP-325 (from OSi) or RHODORSIL ™ (from Rhone Poulenc); ignition modifiers (cetane modifiers) (eg 2-ethylhexyl nitrate (EHN), cyclohexylnite Rate, di-tert-butyl peroxide and those disclosed, for example, in US Pat. No. 4,208,190, column 2, line 27 to column 3, line 21; rust inhibitors (for example, “RC 4801” from Rhein Chemie, Mannheim, Germany) Of a propene-1,2-diol half ester of tetrapropenyl succinic acid, or a succinic acid derivative having a substituted or unsubstituted aliphatic hydrocarbon group having 20 to 500 carbon atoms in one or more α-carbon atoms Polyhydric alcohol esters such as polyisobutane A pentaerythritol diester of a tyrene-substituted succinic acid); a corrosion inhibitor; a reodorant; an anti-wear additive; an antioxidant (eg, phenols such as 2,6-di-tert-butylphenol or N, N′-di) -Phenylene-diamines such as -sec-butyl-p-phenylenediamine); and metal deactivators.

  Unless otherwise stated, the concentration of (active matter) of each of these additive components in the entire fuel composition is preferably 1% w / w or less, more preferably in the range of 5 to 1000 ppmw, advantageously 75 to 300 ppmw, for example 95 It is in the range of ˜150 ppmw.

In particular, when the sulfur content in the composition is low (for example, 500 ppmw or less), it is particularly preferable that the fuel composition contains a lubricity enhancer. The lubricity enhancer is conveniently present at a concentration of 50 to 1000 ppmw, preferably 100 to 1000 ppmw, based on the total fuel composition.
If there is a stagnation inhibitor in the fuel composition, its (active matter) concentration is preferably in the range of 1-20 ppmw, more preferably 1-15 ppmw, even more preferably 1-10 ppmw, advantageously 1-5 ppmw. is there. If there is an ignition improver, its (active component) concentration is preferably 600 ppmw or less, more preferably 500 ppmw or less, conveniently 300 to 500 ppmw.

  The second aspect of the present invention is for the purpose of reducing combustion-related deposits in the diesel engine after introduction of the diesel fuel composition and / or for removing previously formed combustion-related deposits from the diesel engine. A method for operating a diesel engine and / or a diesel engine driven vehicle is provided, wherein a diesel fuel composition including a Fischer-Tropsch derived gas oil and optionally a detergent is introduced into the combustion chamber of the diesel engine. .

  Features of the second aspect of the invention, for example, the type of engine, the nature and concentration of the diesel fuel composition, the presence of detergents, other components of the fuel composition, and the method by which engine contamination can be assessed are: All as described above in relation to the first aspect.

  In a third aspect of the invention, the Fischer-Tropsch derived gas oil is at least 30% w / w, preferably at least 40% w / w, more preferably at least 50% w / w, most preferably at least 60% w / w. There is provided a diesel fuel composition comprising a major proportion of a compression ignition internal combustion engine fuel or fuel blend. The fuel or fuel blend comprises a Fischer-Tropsch derived gas oil of 100% w / w or less, preferably 95% w / w or less, more preferably 90% w / w or less, most preferably 80% w / w or less or 70 % W / w or less may be contained.

  The fuel composition preferably contains a small percentage of detergent-containing additives. “Minor proportion” is preferably less than 1% w / w, more preferably less than 0.5% w / w (5000 ppmw), most preferably less than 0.2% w / w (2000 ppmw) for the fuel composition. Means. “Large percentage” is interpreted according to this small percentage.

  As mentioned above, the present invention may or may not contain additives in the fuel or fuel blend. If it contains additives, it contains a small proportion of one or more additives, especially detergent-containing additives. These additives can be added at various stages during the production of the fuel composition. Additives added at refineries include antistatic agents, pipeline drag reducers, flow improvers (eg, ethylene / vinyl acetate copolymers or acrylate / maleic anhydride copolymers) and wax settling prevention. Agents (eg, commercially available under the trademarks “PARAFLOW ™” (from PARAFLOW ™, Infineum), “OCTEL” (eg, from OCTEL ™ W5000, Octel) and “DODIFLOW” (eg, from DODIFLOW ™ v3958, Hoechst) You can choose from.

According to a fourth aspect of the present invention, there is provided a method for operating a diesel engine and / or a diesel engine driven vehicle, wherein the diesel fuel composition of the third aspect is introduced into a combustion chamber of a diesel engine.
A fifth aspect of the present invention is a diesel fuel, such as the composition of the third aspect, characterized by blending a Fischer-Tropsch derived gas oil with a non-Fischer-Tropsch derived diesel fuel, optionally with a detergent. A method for producing the composition is provided. Again, the blend ideally reduces the combustion related deposits in the diesel engine after the introduction of the diesel fuel composition and / or removes the combustion related deposits in the previously formed diesel engine. This is done for the purpose of removal.

  The discovery that Fischer-Tropsch gas oil can at least partially remove existing engine deposits is that it can be used to "clean up" dirty engines. Thus, in a sixth aspect of the present invention, a Fischer-Tropsch derived gas oil and / or a Fischer-Tropsch derived gas oil is used to purify a fuel injection system of a diesel engine (ie, to remove combustion related deposits from the system). Using an oil-containing fuel composition. “Use” in this manner is a gas oil or fuel composition that runs in the engine or a portion of an engine, such as a fuel injection system, for a time sufficient to remove at least a portion of the combustion-related deposits. It means that It is not always necessary to include driving of an automobile.

Thus, in the present invention, a Fischer-Tropsch derived gas oil or a fuel composition containing such a gas oil may be packaged together with guidelines for use in diesel engine purification in the manner described above.
The sixth aspect of the present invention also includes a method for purifying a diesel engine fuel injection system by introducing a Fischer-Tropsch derived gas oil or a Fischer-Tropsch derived gas oil-containing fuel composition into a combustion chamber of a diesel engine. .

  The characteristics and concentration of, for example, Fischer-Tropsch derived gas oil from the third aspect to the sixth aspect of the present invention, the characteristics in the presence of a detergent and the presence of other fuel components are the first aspect of the present invention and As described above in relation to the second aspect.

In the seventh aspect, the present invention provides:
1) measuring combustion-related deposit levels in a diesel engine running with a “reference” diesel fuel composition that does not contain Fischer-Tropsch derived gas oil or contains less than 1% w / w;
2) performing a first test cycle on the engine running with a reference fuel composition;
3) measuring the combustion-related deposit level in the engine after the first test cycle;
4) calculating the increase in deposits during the first test cycle;
5) performing a second test cycle on the engine running with a diesel fuel composition candidate;
6) measuring the combustion-related deposit level in the engine after the second test cycle;
7) calculating if there is an increase in deposits in the engine during the second test cycle; and 8) calculating the extent of deposit removal during the second test cycle, if applicable.
A method for evaluating the performance of a diesel fuel composition candidate is provided.

The “reference” fuel composition is preferably free of active detergents or contains less than 50 or even 20 ppmw. Preferred is a diesel fuel with a low or very low sulfur content, as described above, and preferably contains no additives.
The level of combustion-related deposits can be measured by evaluating the degree of contamination of the injector nozzle of the engine's injection system, as described above.

  The test cycle includes running the engine for a predetermined time and / or a predetermined number of miles with the associated fuel composition. This test may be performed by the engine alone or by driving the car. In the latter case, the test may be performed under simulated drive conditions (eg using a chassis dynamometer) or may include regular road drives (preferably under urban conditions as opposed to highways). Good. Engine running and / or drive conditions must be the same or equivalent for the first and second test cycles.

As an example, the first test cycle time should be sufficient to produce a significant, at least detectable deposit of combustion-related deposits as compared to the combustion-related deposits measured in step 1 of the test. . A normal first test cycle may last from 1 to 5 hours, preferably 2 hours or more, more preferably 3 hours or more.
An appropriate time for the second test cycle is usually 10 to 100%, preferably 50 to 100%, and most preferably 100% with respect to the first test cycle time. In some cases, it may be 80% or less, 75% or less, or even 50% or less with respect to the first test cycle time. The reduction of combustion-related deposits (as opposed to removal) may be 120% or less, 150% or less, or even 200% or less, relative to the first test cycle time.

The engine used for the test may be, for example, an indirect injection diesel engine such as a Volkswagen ™ Passat ™ engine, eg a Passat ™ AAZ 1.9 TD engine. The test may be performed on only a portion of the engine (eg, a fuel injection system), a pseudo engine, or an engine component.
The evaluation method of the present invention can be used for diesel fuel composition candidates including Fischer-Tropsch derived gas oil, and more particularly candidates including detergents. This method can therefore be used for the identification and / or evaluation of a fuel composition according to the third aspect of the invention.

This method can also be used for performance evaluation of diesel engines and / or performance evaluation of fuel injection systems for diesel engines and / or performance evaluation of diesel engine powered vehicles.
In the eighth aspect of the present invention, when the diesel fuel composition is used as a fuel composition candidate in the evaluation method of the seventh aspect, the second test cycle time is equal to or less than the first test cycle time, More preferably 80% or less, 75% or less, and even 50% or less, and if the first test cycle time is preferably at least 2 hours, more preferably 3 hours or more, the engine before test step 5 The diesel fuel composition provides for removal of at least 5%, preferably at least 10%, at least 15%, at least 20%, or at least 30% of combustion-related deposits accumulated therein.

Such fuel compositions of the present invention ideally contain a Fischer-Tropsch derived gas oil, preferably together with a detergent.
The invention will be further understood from the following examples. These examples illustrate the effect of using Fischer-Tropsch derived gas oil on a diesel engine on the degree of fuel injector contamination.

Overview The two fuels used in the tests were petroleum derived low sulfur diesel fuel F1 and Fischer-Tropsch (SMDS) derived gas oil F2, used alone and in blends containing these two in various proportions. Table A shows the characteristics of these fuels.

Gas oil F2 is obtained from a Fischer-Tropsch (SMDS) synthesis product by a similar two-stage hydroconversion process described in EP-A-0583836.
In the test of Example 3, a commercial detergent-containing additive A was added to these fuels and fuel blends. Additive A is a detergency additive obtained from Infineum that has passed the Cummins L10 heavy detergency test and contains in particular detergents, lubricity additives, antifoams and corrosion inhibitors. Additive A was added at a concentration of 842 ppmw (twice the standard treatment rate). As a result, the active detergent concentration in the additive-containing fuel / blend was over 100 ppmw.
Fuel and blend performance in indirect injection (IDI) diesel engines was tested according to the following protocol. This protocol evaluates the extent of injector nozzle contamination under steady state conditions.

Injector Contamination Test Protocol The engine used was a Volkswagen ™ Passat ™ AAZ 1.9 TD engine with the following specifications:
Bore x stroke: 79.5 x 95.5mm
Number of cylinders: Inline 4 cylinders Stroke volume: 1.896 liters Maximum output: 75 kW @ 4200 rev / min Maximum torque: 140 Nm @ 2400-3400 rev / min
Engine features: Turbocharger with electronic control and
EGR; oxidation catalyst EGR system: Blank off at turbo outlet

The specifications of the engine fuel injection device [Bosch (trademark)] are as follows.
Injector body: 2FH KCA 275 77
Nozzle type: DNO SD 308
Nozzle needle lift: 0.81mm (+/- 0.02)
Nozzle prelift: 0.010 mm (+/- 0.001)
Nozzle opening pressure (1): 150 bar (+ 8 / -0)
Nozzle opening pressure (2): 235 bar (+ / 10 / -0)
Nozzle nut torque: 70 Nm
Leakback test (new nozzle) with pressure drop from 100 bar to 70 bar within 10-35 seconds
Injection pump: VE No. 0 460 494 314.

The injector blank plug used is also Bosch ™ 133-9802. A high-pressure injection pipe was used between the injection pump and the injector.
Prior to the start of each test, four clean nozzles were aired at a needle lift of 0.05 mm and 0.1 mm steps at 0.1 mm steps and the results were recorded. The fuel filter was also changed and bleed before each test and the system was then returned with 9 liters of test fuel or blend.

In order to limit flow variation between tests, multiple steps were taken to ensure that each nozzle needle remained in its own nozzle and that the nozzle body and needle were reliably aligned on the same path in each test.
Each test began with a 20 minute engine warm-up cycle and the same injector was used in a later deposit accumulation phase. During the warm-up operation, the engine speed was 1500 revolutions / minute (+/− 25 revolutions / minute) and the applied torque was 25 Nm (+/− 2.5 Nm).

When the water temperature reached 90 ° C., the engine was tilted for 15 seconds until the deposit accumulation stage. The conditions at this time are as follows.
Engine speed: 2000 rpm (+/- 20 rpm)
Torque: 90 Nm (+/- 1.25 Nm)
Duration: 3 hours (+/- 3 minutes)
Oil temperature (to cooler): 90 ° C (+/- 4 ° C)
Coolant temperature: 90 ° C (+/- 4 ° C)
Fuel pressure to the injector pump: 0.35 bar (gauge pressure) (+/-
0.05 bar)
Nominal fuel flow: 5.1 kg / hour (85 g / min)
Nominal fuel supply: 35 liters

The engine was allowed to stabilize for 5-7 minutes at these test conditions. A series of readings, including Bosch smoke measurements, were made manually. After reaching the test conditions, but before starting the test, the engine was returned to idle and the blow-by was measured. The test conditions were then reset.
During the test, the parameters shown in Table B below were recorded.

Table B
Nominal end point of parameter test value Engine speed 2000 rev / min Engine torque 90 Nm
Period 3 hours Water inlet temperature 90 ℃
Oil inlet temperature 90 ° C
Fuel flow 85-88 g / min Fuel pressure 0.4 bar Fuel temperature 30-32 ° C
Ambient air temperature 25-30 ° C
Air filter temperature 23 ~ 27 ℃
Inlet manifold temperature 84 to 88 ° C
Inlet manifold pressure 1480-1510 mbar Exhaust temperature (before catalyst) 325-340 ° C
Exhaust back pressure from 1770 to 1800 mbar

At the end of each test, the injector was removed, taking care not to disturb or contaminate the deposits on the nozzle surface. The injector was disassembled and the nozzle was removed. The nozzle body and needle are immersed separately in clean n-heptane or other suitable solvent, taking care not to disturb the deposits, to remove excess fuel, then drain and then oven It was dried at 50 ° C. for 1 hour.
The drying nozzle was cooled to ambient temperature for a minimum of 1 hour. The nozzle airflow was then measured with a needle lift of 0.05 mm and further 0.1-0.8 mm in 0.1 mm increments, and the results were recorded.

In order to ensure the continuity between the nozzle flows, before the test nozzles were cleaned and dirt was made to flow, air was also supplied to the reference nozzles with nozzle lifts of 0.1 mm, 0.2 mm and 0.3 mm.
The level of contamination in each test was evaluated by calculating a “contamination index” from the airflow data of each test. Needle lift From the flow rates measured at 0.1 mm, 0.2 mm, and 0.3 mm, the cleanliness of each nozzle and the number of contaminations Fn for dirt were calculated.
Fn = [(clean flow−dirt flow) / clean flow] × 100%
Next, the average contamination number for each nozzle was calculated from the three Fn values. The average soil index for the test is the average of the number of contaminations obtained from all four nozzles.

Example 1
This example illustrates the reduction of engine contamination due to the use of Fischer-Tropsch gas oil in a petroleum derived diesel fuel composition.
Using the injector contamination test described above, petroleum derived fuel F1 was compared to a Fischer-Tropsch derived fuel F2 and also a blend containing these two fuels in a range of proportions. The results are shown in Table 1.

  From these data it can be seen that as the level of Fischer-Tropsch gas oil is increased, pollution tends to decrease clearly. Gas oil alone significantly reduces engine deposits compared to petroleum derived fuel alone. However, a blend of Fischer-Tropsch oil and fuel F1 was associated with a significant pollution reduction even at just 10% w / w level.

Example 2
This example illustrates that a Fischer-Tropsch derived fuel can be used to "clean up" a dirty injector, i.e., remove deposits deposited by the use of other fuels.
Following Experiment 1.1, where the average pollution index of fuel F1 alone was 42.4%, further airflow measurements were made on the same injector to check the nozzle condition (this reflow caused average pollution The index was 39.6%) and then retested with Fischer-Tropsch fuel F2 alone.
The average pollution index after retesting was unexpectedly reduced to 28.5%, and using fuel F2, in addition to the reduction in pollution level as opposed to F1, the engine previously accumulated during the use of F2 It was found that the degree of deposit purification was significant.

Example 3
This example illustrates the cumulative benefit when using Fischer-Tropsch derived diesel fuel and detergent-containing additives.
Example 1 was repeated, except that additive A (twice the standard treatment rate) was added to each fuel or blend. The results are shown in Table 2.

Comparing these results with those in Table 1, the inclusion of detergent-containing additives clearly reduces nozzle contamination for each test fuel or blend. Again, increased Fischer-Tropsch fuel levels are associated with lower pollution levels.
Thus, in the present invention, the Fischer-Tropsch derived fuel can be combined with a detergent to further improve diesel engine fouling as a diesel fuel composition or as part of a diesel fuel composition.

Claims (6)

  Fischer is added to the diesel fuel composition for the purpose of reducing combustion related deposits in the diesel engine after introduction of the diesel fuel composition and / or for removing previously formed combustion related deposits from the diesel engine.・ Method using Tropsch derived gas oil.   The method according to claim 1, wherein the amount of Fischer-Tropsch derived gas oil used in the fuel composition is 10% w / w or more.   The use according to claim 1 or 2, wherein the fuel composition contains a detergent.   Fischer-Tropsch derived gas for the purpose of reducing combustion-related deposits in the diesel engine after introduction of the diesel fuel composition and / or for removing previously-formed combustion-related deposits in the diesel engine A method for operating a diesel engine and / or a diesel engine driven vehicle, characterized in that a diesel fuel composition comprising oil and optionally also a detergent is introduced into the combustion chamber of the diesel engine.   A method of using a Fischer-Tropsch derived gas oil and / or a Fischer-Tropsch derived gas oil-containing fuel composition to remove combustion-related deposits from a diesel engine.   6. Use according to claim 5, wherein the Fischer-Tropsch derived gas oil and / or fuel composition is used together with a detergent.