DE3634081C2 - - Google Patents

Description

The invention relates to an improved fuel or fuel oil based on petroleum distillates.

Mineral oils containing waxy paraffin such as fuel or fuel oils of distillates in particular Middle distillates, such as diesel oil or fuel oil, are added decreasing temperature of the oil less fluid. The reduction the flowability is based on the crystallization the paraffins to plate-shaped crystals, the one form spongy mass and enclose the oil in this; the temperature at which the paraffin crystals increase begin, is called the cloud point (cloud point) and the temperature at which the paraffin deposits prevent a flow of oil are considered Designated pour point.

It is known that numerous additives are used as pour point depressants act when mixed with paraffinic mineral oils be mixed. Modify these compounds the size and shape of paraffin crystals and reduce the cohesive forces between the crystals and between the paraffin and the oil so that the oil remains fluid at lower temperatures and through coarse filter passes.

They are the most diverse pour point depressants in literature and commercially available. For example, US-PS 30 48 479 teaches the use of copolymers of ethylene and C₁ to C₅ vinyl esters such as vinyl acetate as pour point depressants for fuels and in particular for heating oils, diesel and jet fuel. Further, polymeric hydrocarbons based on ethylene and higher alpha olefins z. As propylene known as pour point depressants.  

In the 60s to 70s you put more value on the improvement of the filterability. For example, z. B. US-PS 39 61 916 the use of a mixture of copolymers, to control the size of the wax crystals, and according to GB-PS 12 63 152, the size of the paraffin crystals by using a copolymer with a small chain branching are controlled. Both systems improve the properties of the fuel, to go through filters as they are after Cold Filter Clogging Point (CFPP) test are intended instead of the plate-like formed without derarige additives Crystals now acicular paraffin crystals which do not clog the pores of the filters, but form a porous filter cake on the filter and a passage of the remaining liquid components allow.

Other additives are, for example, according to GB-PS 14 69 016 Mixed polymers of di-n-alkylfumarates and vinyl acetate, the so far as pour point depressants for lubricating oils were used and now as additional additives with ethylene / vinyl acetate copolymers in the treatment middle distillate fuels with a high final boiling point to improve the flow properties at low Temperature can be used.

US-PS 32 52 771 discloses the use of polymers of C₁₆ to C₁₈ alpha-olefins derived from olefin mixtures, in which normal C₁₆ to C₁₈ alpha-olefins predominate, by polymerization with aluminum trichloride / alkyl halide catalysts can be obtained as pour point depressants in distillate fuels with a broad Boiling range of easy to treat and in the early sixties in USA existing fuels.  

It is also known to use olefin-based additives. To use maleic anhydride copolymers. For example become according to US-PS 25 42 542 mixed polymers olefins such as octadecene with maleic anhydride, that is esterified with an alcohol like lauryl alcohol, used as pour point depressant; Furthermore, according to GB-PS 14 68 588 copolymers of C₂₂ to C₂₈ olefins with maleic anhydride, which is esterified with behenyl alcohol is used as a co-additive for distillate fuels.

Similarly, according to JP-PS 56 54 037 olefin / maleic anhydride copolymers, which are reacted with amines, used as pour point depressants. It will be according to JA-PS 56 54 038 derivatives of olefin / maleic anhydride Mischpolymeren together with conventional middle distillate Flow improvers such as ethylene / vinyl acetate copolymers used.

JA-PS 55 40 640 discloses the use of olefin / maleic anhydride Mischpolymeren, which are not esterified, and requires that the olefins used exceed 20 Carbon atoms should contain CFPP activity to show.

According to GB-PS 21 92 012 mixtures of esterified Olefin / maleic anhydride copolymers and low molecular polyethylenes used while the esterified Copolymers as sole or sole additives ineffective are. According to this reference, the olefin 10 to 30 carbon atoms and the alcohol 6 to 28 Contain carbon atoms, with the longest chain in which alcohol contains 22 to 40 carbon atoms.

The improvement in CFPP efficacy by the Installation of these known additives is achieved on a modification of the size and shape of the formed  Paraffin crystals, called needle-like crystals with a general particle size of 10 μm or larger and generally from 30 to 100 μm. When operating diesel engines or heating systems lower temperatures generally go these crystals not through the filters, but form one permeable filter cake on the filter, so that the liquid fuel can pass through, with the Paraffin crystals subsequently dissolve when the diesel engine or the heating system has warmed up and the Main part of fuel by recirculated fuel is heated. However, this can lead to the Paraffin crystals block the filters, causing difficulties when starting or starting and also to problems when starting in cold weather or in case of failure of the preheating system for the fuel can lead.

Surprisingly, it was found that paraffinic Fuel or fuel oils especially small paraffin crystals can contain through the paper filter usual diesel engines and heating systems pass through can if they receive certain additives.

The present invention has the object a very specific improved fuel or fuel oil propose.  

To solve this problem is a fuel or fuel oil based of petroleum distillates having a boiling range from 120 to 385 ° C a content of paraffins, that through a filter of the type Cummins FF 105 with at least a flow rate of 60% of the original Flow rate (based on a throughput of 18 to 20 liters of fuel) is proposed, which thereby It is characterized in that it paraffin crystals with an average Particle size of less than 4000 nm at a Temperature of 10 ° C below the paraffin forming temperature has and is obtainable by mixing a propellant or Fuel oil, which at a temperature of 10 ° C below the Paraffin forming temperature has a paraffin content of at least 0.3 wt%, with an N, N-dialkylammonium salt of 2-dialkylamidobenzenesulfonate with nC₁₆- to C₁₈-alkyl radicals in one Amount of 0.001 to 0.5 wt .-%.  

The wax or paraffin forming temperature (WAT) of the fuel is determined by means of differential scanning Calorimetry (DSC) determined. This test will be a small sample of a fuel of 25 μl with a Speed of 2 ° C / min. together with a comparative sample cooled the same thermal capacity, which but no paraffin precipitates in the temperature range in question shows, such as kerosene. It an exothermic effect is observed when crystallization begins in the sample. For example, the WAT value of the fuel by extrapolation at one Mettler TA 2000 B device.

The paraffin content of the fuel or fuel oil or diesel fuel or fuel oil is absorbed by the DSC record by integration of the area derived from the baseline and the exothermic curve up to the specified Temperature is enclosed. The calibration will be done in advance with a known amount of crystallizing paraffin carried out.

The average particle size of the paraffin crystals is determined by analysis of an electronically scanned photomicrograph a fuel sample at a magnification determined from 4000 to 8000, with the longitudinal axis of 50 crystals measured in a predetermined grid becomes. It was found that the paraffin crystals with an average size of less than 4000 nm through conventional paper filters, as in diesel engines be used, go through with the fuel oil, although it is preferred, the size below 3000 nm and preferably below 2000 nm and in particular below 1000 nm, the actually achievable Size of the origin of the fuel and the Type and amount of additive used depends, however, it has been found that these sizes and  even smaller can be achieved.

The possibility of such small paraffin crystals in Obtaining the fuel or fuel, results in significant Advantages of operating diesel engines, what you get thereby can show that before that for removal fuel stirred by settled paraffin crystals through a diesel filter with 8 to 15 ml / sec. and 1.0 up to 2.4 liters per minute per m² of filter surface at one Temperature of at least 5 ° C below the paraffin forming temperature with at least 0.5% by weight of the fuel in the form of solid paraffin particles. Either Fuel and paraffin run successfully through the filter if one or more of the following Criteria are met:

• (i) if 18 to 20 liters of fuel through the Filter gone through and the pressure drop on the filter not more than 50 kPa, preferably 25 kPa and especially 10 kPa and at best 5 kPa;
• (ii) if at least 60% and preferably at least 80% and in particular at least 90 Wt .-% of the paraffin present in the fuel after the DSC test in the fuel is determined, which emerges from the filter;
• (iii) when you pump through from 18 to 20 liters Fuel through the filter a flow rate that always has over 60% of the original Flow rate and preferably over 80% of this remains.

The proportion of crystals passing through the filter of the motor vehicle go through and the benefits are based on operation  on the small crystals and hang heavily from the crystal length, although the crystal form is important. It was found that cube-like Crystals are much easier through the filters go through as flat crystals and that if they are not pass through the filter, a lower volume resistance for the fuel. Nevertheless, that is preferred crystal form a flat shape, in general it allows more paraffin to be deposited can when the temperature drops and that more Paraffin deposits before the critical crystal length is reached, as it is with equal length crystals in cubic shape would be the case.

The fuels according to the invention show excellent Advantages over previous middle distillate fuels, by adding conventional additives in their Cold flow properties have been improved. For example are the fuels at temperatures in the neighborhood of the pour point and will not limited in that they do not meet the CFPP test. As a result, these fuels or fuels meet the CFPP test at significantly lower temperatures or these experimental conditions do not have to be at all be fulfilled. The fuels also have an improved Cold start behavior at lower temperatures, since they are not on the circulation of warm fuel to dissolve the unwanted paraffin deposits are reliant.  

Distillate fuels with a general boiling range from 120 to 385 ° C vary significantly in their boiling properties and their paraffin content, the extent, with which extremely small crystals are obtained can depends on the type and origin of the fuel itself off and it is not with some middle distillates possible to produce extremely small crystals, like them be required according to the invention. The flow properties however, can be multiplied so that such small ones Crystals are obtained by, for example, that changes the working conditions at the refinery, so that you can use appropriate additives.

The additives to be used according to the invention are N, N-dialkylammonium salts of 2-dialkylamidobenzenesulfonates with n-C₁₆-C₁₈ alkyl radicals.  

The additives can be made from the aromatic compound with the following formula are produced:

This connection is implemented to the Hemi-amides / half-salts too which are used as additives and Half amides / half salts of secondary amines are which a group containing hydrogen and carbon with 16 to 18 carbon atoms contain. Such amides or salts can be prepared thereby be that you have the acid or anhydride with a secondary amine or alternatively an amine derivative with the carboxylic acid or anhydride of these converts. The removal of water and heating are in general required to remove the amides from the acids receive.  

The additives according to the invention can generally in combination with other additives be used. Examples of such other additives are the compounds known as comb polymers of the following general formula used.

in which
D = R, CO-OR, OCO.R, R'CO.OR or OR
E = H or CH₃ or D or R '
G = H or D
m = 1.0 (homopolymer) to 0.4 (molar ratio)
J = H, R ', aryl radical or a heterocyclic radical, R'CO.OR
K = H, CO.OR ', OCO.R', OR ', CO₂H
L = H, R ', CO .OR, OCO. R', aryl, CO₂H
n = 0, 0 to 0.6 (molar ratio)
R C₁₀
R 'C₁

is.

Other monomers may also be terpolymerized if necessary his.

If these other additives are mixed polymers of alpha-olefin and maleic anhydride, then they can be simple Way by polymerization of the monomers without solvent or in a solution of a hydrocarbon solvent, such as heptane, benzene, cyclohexane or white oil at temperatures in the general range of 20 to 150 ° C. usually using a peroxide or an azo catalyst, such as benzoyl peroxide or azo-di-isobutyronitrile under an inert gas blanket of nitrogen or carbon dioxide made to prevent oxygen access become.

The copolymers of olefins and maleic anhydride can be esterified in the usual way, preferably  but not essential, the maleic anhydride at least 50% is esterified. Examples of Alcohols that can be used are n-decan-1-ol, n-dodecan-1-ol, n-tetradecan-1-ol, n-hexadecan-1-ol, n-octadecan-1-ol.

The choice of alcohol Of course, this depends on the choice of maleic anhydride to be polymerized from olefin.

The comb polymers are also fumarate / vinyl acetate and in particular those described in the European patent applications 01 53 176, 01 53 177 and 85 301 047 and 85 301 048 and esterified olefin / maleic anhydride copolymers and the polymers and copolymers of alpha-olefins and esterified copolymers of styrene and maleic anhydride.

Examples of other additives used together with the invention Compounds can be used  Polyoxyalkylene esters, ethers, esters / ethers and their Mixtures, in particular those containing at least 1 and preferably 2 linear saturated C₁₀ to C₃₀ alkyl radicals and a polyoxyalkylene glycol moiety having a molecular weight from 100 to 5000, preferably 200 to 5000 contain, wherein the alkyl radical in the polyoxyalkylene glycol Contains 1 to 4 carbon atoms. These connections are in the European patent application 00 61 895 B described. Other such additives are disclosed in US Pat 44 91 455 described.  

The additives can also be used with ethylenically unsaturated Ester copolymers which are flow improvers used become. The unsaturated monomers that react with ethylene can be copolymerized, inter alia, unsaturated Mono- and diesters of the following general formula:

in the R₆ is hydrogen or a methyl radical, R₅ a -OOCR₈ group and R₈ a hydrogen form or a C₁ to C₂₈ radical and usually a C₁ to C₁₇- and preferably a C₁ to C₈-alkyl radical with straight or branched chain is; or R₅ is a -COOR₈ group, in which R₈ has the above-mentioned meaning, but not Is hydrogen, and R ¼ is hydrogen or -COOR₈ in the above meaning. The monomer closes, if R₆ and R₇ are hydrogen and R₅-OOCR₈ are, vinyl alcohol esters from C₁ to C₂₉- and usually C₁ to C₁₈- and preferably C₂ to C₅ monocarboxylic acids. Examples of vinyl esters copolymerized with ethylene are vinyl acetate, vinyl propionate and Vinyl butyrate or isobutyrate, with vinyl acetate being preferred becomes. Preferably, the copolymers contain 5 to 40 and preferably 10 to 35% by weight of vinyl ester. You can also mixtures of two copolymers, as for example in US-PS 39 61 916 is described. Preferably These copolymers have an average Molecular weight determined by the vapor phase osmometry from 1000 to 10,000, and preferably 1000 to 5000.

The additives can also polar nitrogenous compounds  contain. These nitrogen compounds are described in US Pat 42 11 534 described. Suitable amines are in general long-chain primary, secondary, tertiary or quaternary C₁₂ to C₄₀ amines or mixtures thereof, but may shorter-chain amines may also be used, provided that that the resulting nitrogen compound is oil-soluble and thus generally about 30 to 300 carbon atoms total contains. The nitrogen compound preferably contains at least one straight chain C₈- to C₂₄-alkyl portions.  

Hydrocarbon polymers can also be used as part of Additive combination of the following general formula be used:

in which
T = H or R '
U = H, T or an aryl radical
v = 1.0 to 0.0 (molar ratio)
w = 0.0 to 1.0 (molar ratio)
and wherein R 'is an alkyl radical.

These polymers can be directly derived from ethylenically unsaturated Monomers or indirectly by hydrogenation of monomers, such as isoprene, butadiene, etc. obtained polymers become.

Particularly preferred hydrocarbon polymers are Mixed polymers of ethylene and propylene with an ethylene content preferably from 20 to 60% by weight, in general be prepared by homogeneous catalysis.

The amount of additive used to produce the invention Distillate fuel or fuel oil required depends on the type of fuel oil, but is in a range of 0.001 to 0.5% by weight and for example from 0.01 to 0.1% by weight of active substance, based on the weight of the fuel. The Additive is usually in a suitable solvent to a concentrate with 20 to 90 z. B. 30 to 80 wt .-% dissolved. Suitable solvents are kerosene, aromatic Naphtha compounds, mineral lubricating oils and the like.

The invention is illustrated by the following examples, the size of the wax crystals in the fuel was determined by injecting fuel samples into Bottles of 57 cc in refrigerated containers at about 8 ° C above the cloud point of the fuel stored for about 1 hour, to stabilize the fuel temperature. The container was then kept at 1 ° C per hour except for Test temperature cooled and then at this temperature leave. A previously prepared filter holder from a sintered ring with a diameter of 10 mm, the surrounded by a 1 mm wide circular metal ring was holding a 200 nm sized membrane filter made of silver, fastened by two vertical pins  was and was placed in a vacuum device. A vacuum of at least 30 kPa was applied and the cooled fuel from a clean dropper pipette dripped onto the membrane until the membrane of a small Pool was covered. The fuel was slowly added dropwise, to maintain this oil thing. After application from about 10 to 20 drops of fuel, left the pool drain off a thin non-glossy layer of Moist paraffin cake on the membrane left behind. A too thick a paraffin layer does not give acceptable washing and too thin a layer can be washed away. The optimal layer thickness depends on the crystal form, where leaf-like crystals are a thinner layer than need nodular crystals. It is essential that the final filter cake has a dull appearance. A shimmering filter cake shows too much on residual oil and smearing of the crystals, so that this cake should be discarded.

The cake is then mixed with a few drops of methyl ethyl ketone washed, which is allowed to drain completely. This is done several times. When washing ends, it disappears the methyl ethyl ketone very quickly and leaves a shiny matt white surface back when applied of another drop of methyl ethyl ketone becomes gray.

The washed sample is then placed in a cold desiccator given and left there until the coating in the SEM can be done. It may be necessary, this sample leave under cooling to protect the crystals; You can put them in a cooling chamber before the Transition to the SEM with a suitable transport container store to a formation of ice crystals on the surface to avoid the sample.

During coating, the sample must be as cool as possible held to a destruction of the crystals too  to decrease. The electrical contact with the stage becomes best with a locking screw that allows the circular ring against the side of a recess pressed, which is provided so that the surface of the Probe located on the focal plane of the instrument. you can also use electrically conductive paint.

If the sample is coated, the photomicrographs can similarly with an electronic scanning microscope to be obtained. The microphotographs are analyzed to determine the average crystal size, by putting a transparent film with 88 marks in the form of points at the interfaces of a uniform Grid of 8 rows and 11 rows provides. The Magnification should be chosen so that only some of largest crystals are touched by more than one point, where a 4000- to 8000-fold magnification is suitable. At each grid point, the crystal can be measured when the point touches a crystal dimension whose Form can be clearly defined. It is called distribution scatter the Gaussian standard deviation of the crystal length provided with a correction to Bessel.

The wax content before and after the filter comes with a Differential scanning calorimeter DSC (eg du Pont device 9900), wherein an area having a range of about 100 cm² / 1% fuel in the form of paraffin with an instrument with a noise-induced output change with a standard deviation of less than 2% of the main output signal is sampled.

The DSC device is calibrated with an additive which Large crystals are generated safely from the filter too are removed using this for calibration Fuel at the test temperature in the device  run through and the WAT value of the dewaxed so Fuel oil with the DSC measures. The samples of the fuel from the tank and after the filter Fuel is then analyzed by the DSC device; for each fuel, the range is above the baseline up to the WAT value of the calibration used Fuel determined.

The percentage of paraffin remaining after the filter results from the ratio of:

The cloud point of the distillate fuel was after a standard method (IP-219 or ASTM-D 2500) determined; the further provisions for the onset of crystallization are the Paraffin Make Point (WAT) test after ASTM D. 3117-72 and Wax Forming Temperature (WAT), by differential scanning calorimetry with a Mettler TA 2000B device, namely a differential scanning calorimeter was measured.

The ability of the fuel through a main filter to go through a diesel engine, was in a device determined, that from a usual main filter of a diesel engine which was in a standard housing in the fuel supply line was attached. Suitable for this are Bosch filters, as used in the VW Golf diesel car (1980) and in a Cummins FF105 series from Cummins NTC be used. A storage tank and a feed system, with the one half of the fuel of a normal Diesel fuel tank, was fed to a Injection pump, as used in the car Golf VW is used to filter the fuel through the filter the tank at a constant flow rate  how to promote in the vehicle. There were also instruments attached to the pressure drop across the filter, the flow rate from the injection pump and the temperatures to measure in unity. There were also receptacles provided to the pumped fuel, namely both the fuel injected and the fuel surplus take.

In the experiment, the tank was filled with 19 kg of fuel and checked for leaks. Then the temperature became at an air temperature of about 8 ° C above stabilizes the cloud point of the fuel. The Unit was then at 3 ° C per hour to the desired Test temperature cooled and at least 3 hours so held to stabilize the fuel temperature. The tank was shaken vigorously to the existing one Completely disperse wax. It became a rehearsal taken from the tank and 1 liter of fuel at one Test point on the outlet line immediately after removed from the tank and returned to the tank. The pump was then started, with the circulation rate was adjusted so that they are in terms of their pumping power per minute, the driving speed of 110 km / h. corresponded. This value was in the VW Golf in an area from 1900 rpm corresponding to a number of revolutions of the Motors of 3800 rpm. The pressure drop at the filter and the flow rate of fuel from the injection pump were recorded until the last fuel was consumed was what was generally the case after 30 to 35 minutes.  

If the fuel supply for injection at 2 ml / s can be held and the additionally supplied fuel at a level of 6.5 to 7 ml / s the test is "passed". A waste in the Fuel supply to the injector is called a "borderline case" assessed, while no fuel at all as "failed" is called.

Usually is at a designated "passed" Test to also detect an increasing pressure drop across the filter which can be up to 60 kPa. In general need considerable amounts of crystallized paraffin pass the filter before reaching such a result becomes. The rating "well passed" exists, if in the course of the experiment, the pressure drop across the filter does not rise above 10 kPa, which is the first sign of this It should be noted that the majority of paraffins are the filter has gone, giving an excellent result is achieved when the pressure drop is below 5 kPa.

In addition, fuel samples from the excess fuel and from the fuel supplied to the injector taken, preferably every 4 minutes in the course of the entire experiment. These samples together with the Samples taken from the tank before the test are passed through DSC compared to the proportion of added paraffin determine which has gone through the filter. Samples of the fuel taken before the test also taken and there are SEM samples after the Test taken to the crystal size of the paraffin and its nature under actual conditions of use determine.

The following additives were used:  

Additive 1

The N, N-dialkylammonium salt of 2-dialkylamidobenzenesulfonate having alkyl groups of nC₁₆-C₁₈H _{33-37 was} prepared by reacting one mole of the cyclic anhydride of orthosulfobenzoic acid with 2 moles of di (hydrogenated) tallowamine in xylene as a solvent having a 50 wt. -% concentration was implemented. The reaction mixture was stirred between 100 ° C and reflux temperature keeping the solvent and the compounds as dry as possible to suppress hydrolysis of the anhydride.

The reaction product was analyzed by NMR at 500 MHz to give a spectrum as shown in FIG. 1, which confirmed the following structure.

Additive 2

A mixed polymer of ethylene and 17% by weight of vinyl acetate with a molecular weight of 3500 and a side chain branching of 8 methyl radicals per 100 methyl groups, which were determined by NMR at 500 MHz.  

Additive 3

This was prepared by esterification of a 1: 1 molar styrene / maleic anhydride copolymers of a 1: 1 molar mixture of C₁₂H₂₅OH and C₁₄H₂₉OH per mole Anhydride groups, with a slight excess of about 5% of alcohol was present. The esterification took place with p-toluenesulfonic acid as catalyst (1/10 mol) in Xylene as a solvent, wherein a product with a Molecular weight (Mn) of 50,000 was obtained, which Contains 3 wt .-% untreated alcohol.

Additive 4

A dialkylammonium salt of 2-N, N-dialkylamidobenzoic acid, by mixing 1 mole of phthalic anhydride with 2 mol of dihydrogenated tallow amine was obtained at 60 ° C.

example 1

The fuel used had the following properties:

Cloud Point | -14 ° C CFPP, untreated -16 ° C Crystal formation point -18.6 ° C initial boiling point 178 ° C 20% Sdp 230 ° C 90% Sdp 318 ° C Final Boiling Point 355 ° C Paraffin content at -25 ° C 1.1% by weight

It was an additive combination of 250 ppm each of the Additives 1, 2 and 3 added to the fuels and at -25 ° C tested. The crystal size of the paraffin was at 1200 nm in length, and more than 90 wt .-% of the paraffin went through the Cummins FF105 filter.  

During the experiment, the passage of paraffin further demonstrated by the pressure drop at the filter, which only increased by 2.2 kPa.

Example 2

Example 1 was repeated, the crystal size of the paraffin at 1300 nm and the maximum pressure drop at the filter was determined at 3.4 kPa.

Example 3

An oil with the following properties was used:

Cloud point | 0 ° C CFPP, untreated -5 ° C Crystal formation point -2.5 ° C initial boiling point 182 ° C 20% Sdp 220 ° C 90% 354 ° C Final Boiling Point 385 ° C Paraffin content at -25 ° C 1.1% by weight

250 ppm of each of the additive 1, 2 and 3 were the Fuel added and the paraffin crystal size with 1500 nm, and found to be 75% by weight. of paraffin through a Bosch filter 145434106 at a Test temperature of -8.5 ° C went through. The maximum pressure drop at the filter was 6.5 kPa.

Example 4

Example 3 was repeated, with a paraffin crystal size of 2000 nm in length, of which about 50% by weight through the filter at a maximum pressure drop of 35.3 kPa occurred.  

Example 5

The fuel according to Example 3 was used with 400 ppm of Product of Example 1 and 100 ppm of A1, wherein the fuel as in Example 5 at -8 ° C examined and at this temperature the paraffin content was 1.4 Wt .-% was. The paraffin crystal size was 2500 nm and 50% by weight of the paraffin entered through the filter a pressure drop of 67.1 kPa.

Example 6 (Comparative Experiment)

The fuel according to Example 3 was 500 ppm Mixture of 4 parts of the additive 4 and 1 part of the additive 2 treated; this fuel was tested at -8 ° C, wherein it was determined that the paraffin crystal size at 6300 nm and 13 wt .-% of the paraffin by went the filter.

This example is based on one of the best examples of the prior art, in which excellent results were detected without passage of the crystals.

A scanning electron micrograph of the wax crystals which form in the fuels according to Examples 1 to 6 are reproduced in FIGS. 1 to 6.

Examples 1 to 4 show that the crystals are reliable go through the filter that the excellent cold temperature behavior to higher paraffin content than before can be extended and also at temperatures that far below the paraffin forming temperature,  as it was previously feasible. This is possible without having to consider the fuel system, such as the possibility of heating fuel from the engine the fuel supplied from the fuel tank is taken back, as well as the ratio supplied fuel to the recirculated fuel, the ratio of the main filter surface to the supplied fuel and the size and position of the Pre-filter and sieves.

Examples 1-3 show that the investigated Filter crystal lengths below about 1800 nanometers to one significantly better fuel performance.

Claims (5)

A petroleum distillate fuel oil having a boiling range of from 120 to 500 ° C and containing paraffins, which is passed through a filter of the Cummins FF 105 type with at least a flow rate of 60% of the original flow rate (in terms of throughput from 18 to 20 liters of fuel), characterized in that the fuel oil has paraffinic crystals having an average particle size of less than 4000 nm at a temperature of 10 ° C below the paraffin forming temperature and is obtainable by mixing a fuel or fuel oil, which has a paraffin content of at least 0.3% by weight at a temperature of 10 ° C. below the paraffin-forming temperature, with an N, N-dialkylammonium salt of 2-dialkylamidobenzenesulfonate having nC₁₆ to C₁₈-alkyl radicals in an amount of 0.001 to 0, 5% by weight. 2. Fuel or fuel oil according to claim 1, characterized characterized in that the paraffin crystals have an average Particle size of less than 3000 nm to have. 3. Fuel or fuel oil according to claim 1, characterized characterized in that the paraffin crystals have an average Particle size less than 2000 nm to have. 4. Fuel or fuel oil according to claim 1, characterized characterized in that the paraffin crystals have an average Particle size of less than 1500 nm to have.   5. Fuel or fuel oil according to claim 1, characterized characterized in that the paraffin crystals have a particle size of less than 1000 nm.