HK1019614B - Emulsified fuel and one method for preparing same - Google Patents

Description

Emulsified fuel and preparation method thereof

The field of the invention is fuel compositions, in particular for heating machines, more precisely fuels within the scope of the invention which contain predominantly liquid hydrocarbons and in particular:

petroleum derivatives from mineral oil sources, such as oils including gasoline, diesel fuel, kerosene and heating oil, and/or hydrocarbons derived, for example, from coal or gas (synthetic motor fuels);

hydrocarbons from vegetable oil sources, such as esterified or unesterified vegetable oils;

-and mixtures thereof.

More particularly, the invention relates to novel fuel compositions comprising an emulsion of water in at least one hydrocarbon and typically in a mixture of hydrocarbons, for example a mixture constituting diesel fuel. The present invention therefore relates to stable water/hydrocarbon emulsions containing surfactants capable of emulsifying and stabilizing the emulsion.

The present invention also relates to a process for the preparation of an emulsified water/hydrocarbon fuel (e.g. motor fuel) in combination with one or more surfactants.

The present invention is in the field of developing fuel compositions, especially motor fuel compositions, which have long been gaining widespread interest, including alternative products to petroleum derivatives, for the purpose of reducing cost and pollution.

Water is soon found to be a valuable additive or a partial replacement for gasoline or diesel fuel. Water is in fact an inexpensive and non-toxic liquid, and has been shown to reduce fuel consumption and the emission of visible or invisible pollutants.

While all of these concepts are advantageous, water/hydrocarbon motor fuels have not been used on a large scale in industry in particular applications because of the prohibitively expensive difficulties in their processing and use.

According to a first method, it has been envisaged to store water and fuel separately and mix them at the time of use on board the vehicle. This method requires complex and improved equipment to be installed on the vehicle for the specific mixing and metering operations. The cost, volume and precision of the equipment has proven to be prohibitive in developing the method.

A second conceivable approach involves the use of ready-to-formulate mixtures of water and oil, but this approach does not take into account the considerable problems of storage stability of the mixture at temperatures of-20 ℃ to-70 ℃ and emulsion stability in the tank under the conditions of use.

Therefore, there are many technical proposals that are unproductive and that provide water-containing emulsified motor fuels without value, and more generally, new pollution-free motor fuels with low consumption.

As an example of one such prior art, mention may be made of french patent application 2470153, which discloses an emulsified motor fuel containing a hydrocarbon, water and an alcohol (methanol, ethanol) and an emulsifying system formed from sorbitan monooleate and ethoxylated nonylphenol. The concentration of the emulsifying system in the emulsion is 3-10% by volume. The alcohol present predominantly in the emulsion constitutes a very disadvantageous factor, in particular in terms of economy and engine performance characteristics obtainable with the emulsion. Furthermore, it should be noted that the stability of such water-alcohol/hydrocarbon emulsions is somewhat insufficient. In fact, after 72 hours of storage of the emulsion (corresponding to the actual non-use time of the vehicle using this fuel), an initial phase separation (phase separation/demixing) between the hydrocarbon and aqueous alcohol mixture occurs. The hydrocarbon phase separated (separated) at the end of this time may be up to 3% by volume of the emulsion. It is easy to imagine that the phase separation of the emulsion according to patent application 2470153 after a few days of storage is sufficient to prevent the vehicle from operating under normal use conditions.

US4877414 also discloses an emulsified motor fuel containing a number of additives including an emulsifying system formed from sorbitan sesquioleate, sorbitan monooleate and polyoxyethylene ether of dodecanol (6 EO). Preferably, the total concentration of all additives according to this patent is about 2.1%. Other additives that may be used in addition to the emulsifying system are mono-alpha-olefin (1-decene), methoxy methanol, toluene, alkyl benzene and calcium hydroxide. The formulation is extremely complex, but only with this amount of additive. The formulation is also quite expensive. Finally, the emulsion fuel of this patent also has the disadvantage of lacking stability, particularly at low temperatures. In addition, the applicant can clearly show this drawback by reproducing the preferred embodiment of the emulsion fuel of this us patent. We have found that the emulsion separates (phase separates) within 1 hour, which is further exacerbated at temperatures below 5 ℃. It is therefore difficult to imagine what happens in a vehicle tank containing the emulsion when in winter use conditions.

Chemical abstracts 87: 138513x, the abstract of japanese patent 77-69909, relates to emulsified motor fuels (kerosene/water) containing sorbitan sesquioleate and polyethylene glycol ethers of nonylphenol as emulsifiers. The aqueous dispersion has a droplet size of 20 mu or less and an average of about 10 mu. The technical proposal still cannot properly achieve the purposes of physicochemical stability, pollution reduction, cost reduction and fuel consumption reduction. This technique as described therefore does not provide any assistance to the person skilled in the art working in the field of the invention described.

Another summary of the chemical abstracts 101 of brazilian patent 824947: 57568z relates to an emulsion fuel containing hydrocarbons including very viscous and heavy petroleum derivatives, water, ethanol, and emulsifiers including ethoxylated nonylphenols, which emulsion fuel is intended for use in conventional furnaces and heavy oil-fired furnaces. The fuel does not meet the expected combustion performance specifications, reduction of pollutants and low consumption. In addition, the emulsion has poor physicochemical stability.

The applicant's PCT international patent application WO-93/18117 describes an emulsion fuel, and the present invention proposes an improvement to this fuel.

These emulsified fuels, which may be motor fuels, contain a specific amount of a hydrocarbon and a small amount of a group of additives including in particular an emulsifying system containing sorbitan oleate, polyethylene glycol and alkylphenol ethoxylates. The water content of the dispersed phase of these emulsion fuels is from 5 to 35% by weight, and the amount of additive is from 0.1 to 1.5% by weight.

The concentrations of sorbitan oleate, polyethylene glycol and alkylphenol ethoxylate are in the range of 0.20-0.26/0.20-0.25/0.20-0.27, respectively. The entire patent application indicates that these three main additives are present in equal amounts: 1/1/1 is used.

The performance characteristics of these known emulsion fuels in terms of stability, reduction of visible and invisible pollutants, reduction of consumption and reduction of costs are completely improvable. In particular, research and development of these emulsified motor fuels has enabled to show that improvements in the cost and stability of the emulsion are desirable, especially under practical application conditions of vehicles.

The review of the prior art shows that the need for such emulsion fuels that are physico-chemically stable (no phase separation), produce low pollution and are economical and reduce consumption has not been met.

The applicant is confident in the opinion that several objects have been set for this purpose, which will be listed below.

A main object of the present invention is to remedy the above-mentioned drawbacks by providing an emulsified fuel, in particular a motor fuel, formed by a stable water/hydrocarbon emulsion which remains sufficiently homogeneous over a long period of time in the tank and in the components constituting the circuit of the combustion plant in which said fuel can be used.

It is another principal object of the present invention to provide a new and improved emulsified motor fuel which reduces fuel consumption and reduces the emission of visible pollutants, i.e., fumes, solid particles and gaseous invisible pollutants such as CO, NO_xAnd/or SO₂Unburned hydrocarbons and CO₂With good results on emissions.

Another main object of the present invention is to provide a new emulsified fuel which has a low cost price, but provided that the advantages obtained by partial replacement of expensive hydrocarbons with water are not eliminated.

It is another object of the present invention to provide a process for preparing a stable, non-polluting and economical emulsion fuel, which process is also necessarily inexpensive and moreover easy to carry out without the need for complex operating schemes or equipment.

For the above reasons, the applicant has made creative efforts and developed new and improved emulsion fuels, the creative features of which are as follows:

in one aspect, the fuel contains an aqueous dispersed phase comprised of reduced size droplets having an interfacial film to account for the occurrence of coalescence phenomena. In order to provide stability to the emulsion, it is important to have the size distribution of the water droplets as narrow as possible.

On the other hand, the composition chosen for the emulsifying system is an influential factor in achieving the technical requirements of stability, droplet size and size distribution of the aqueous phase in the kerosene fuel phase.

From the above, the present invention relates to an improved emulsified fuel comprising an aqueous emulsion in at least one hydrocarbon, the fuel being characterized in that:

→ the emulsion contains an emulsifying system containing:

delta (I) at least one sorbitol ester having the formulaWherein: the radicals X are identical or different from one another and are each OH or R¹COO-wherein R¹Is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical, optionally substituted by hydroxyl groups, containing from 7 to 22 carbon atoms, R¹Preferably a fatty acid residue without a carboxyl end group, the ester (I) having an HLB of from 1 to 9;

delta (II) at least one fatty acid ester of the formulaWherein: -R²Is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical, optionally substituted by hydroxyl groups, containing from 7 to 22 carbon atoms, R²Preferably a fatty acid residue without a carboxyl end group, -R³Is straight or branched C₁-C₁₀Alkylene, preferably C₂-C₃Alkylene, -n is an integer greater than or equal to 6, preferably from 6 to 30, and-R⁴Is H straight or branched chain C₁-C₁₀Alkyl orWherein R is⁵And the above-mentioned R²The HLB of the ester (II), defined as being the same, is preferably greater than or equal to 9; and

delta (III) at least one polyalkoxylated alkylphenol of the general formulaWherein: -R⁶Is straight or branched C₁-C₂₀Alkyl, preferably C₅-C₂₀Alkyl, -m is an integer greater than or equal to 8, preferably from 8 to 15, and-R⁷And R⁸Are respectively reacted with R in the formula (II)³And R⁴The polyalkoxylated alkylphenol (III) preferably has an HLB of from 10 to 15;

→ the total HLB of the emulsifying system is 6 to 8, preferably 6.5 to 7.5;

→ the emulsion is prepared in such a way that the mean droplet size of the aqueous disperse phase is less than or equal to 3 μm, preferably 2 μm, particularly preferably 1 μm, with a standard deviation of less than 1 μm.

These advantageous and improved properties relate to:

size distribution of the droplets of the aqueous phase

The inventive selection of the appropriate components of the emulsifying system, these characteristics being clearly different from the invention according to WO9318117, which improves the invention of WO 9318117.

Improved emulsified motor fuels have these characteristics benefited by long term high storage stability. These fuels do not phase separate (undergo phase separation) in the canister or in the various components that make up the feed circuit of the device that can serve as a combustion site, i.e., an internal combustion engine, burner, etc.

Since the emulsion of the invention remains perfectly homogeneous, the risk of undesired conditions in the combustion equipment is greatly reduced. No phase separation (phase separation) and coalescence, whether by gravity or by any other separation means (filtration, centrifugation, etc.), is produced, which is an important technological advance that enables practical industrial and commercial applications.

These properties are indeed improved compared to the emulsified motor fuel of WO 9318117.

According to the invention, it is understood that the stability of the emulsion means that the emulsion maintains its initial homogeneous physicochemical state (without phase separation, without coalescence of the droplets of the dispersed phase) during storage at room temperature for a period of at least 3 months.

Furthermore, the emulsion fuel of the present invention has both excellent value and satisfactory performance characteristics in terms of reduced pollutant emissions and consumption, and can achieve this effect at a reasonable cost price.

It should be noted that these effects are obtained without compromising the combustion performance characteristics (high level of thermal and thermo-mechanical efficiency).

In addition, the absence of large droplets enables the problems of clogging, pressure loss and/or water separation in filtration devices such as those in the feed circuit of the emulsified fuel to be minimized. Furthermore, in very cold conditions, these problems aggravate the freezing of the droplets that cause the aqueous phase; this forms a pellet which has a greater blocking capacity than the droplet. Damage caused by droplet freezing can be minimized by the addition of antifreeze.

The mean particle size of the droplets of the aqueous phase chosen, of 3 μm, preferably 1 μm, and particularly preferably 1 μm, with a maximum standard deviation of 1 μm, is considered to be a decisive factor in ensuring the stability of the emulsion, in particular in limiting coalescence and phase separation phenomena. Thus, according to the invention it is provided that in practice the "monodisperse" particle size distribution is about 1 μm (cf. the curve of FIG. 5). This means that the size of the majority of droplets is uniform and in addition the size is small enough to be a factor in stability.

According to the invention, the abbreviation HLB denotes "hydrophilic-lipophilic-balance". It is a well-known parameter characterizing emulsifiers. References in the field of emulsions, namely "emulsions: theory and practice, Paulbecher-REINHOLD Press ACS Monograph-ed.1965 ", where HLB is defined in detail in the section" emulsifier chemistry "from page 232 onwards. This definition is incorporated herein by reference.

The qualitative and quantitative composition of the emulsifying system, which provides the results obtained, in particular in terms of stability, is also an essential feature of the present invention.

Advantageously, the emulsion contains at least 5% by weight of water, the concentration of the emulsifying system being less than or equal to 3% by weight, preferably less than or equal to 2% by weight, relative to the total weight of the fuel.

In a preferred embodiment of the invention, the emulsifying system contains 3 compounds (I), (II) and (III) in the following proportions:

(I)2.5 to 3.5 parts by weight, preferably 3 parts by weight,

(II)1.5 to 2.5 parts by weight, preferably 1.5 to 2 parts by weight,

(III)0.5 to 1.9 parts by weight, preferably 0.5 to 1.5 parts by weight.

The fatty acid esters of sorbitan (I) preferably consist essentially of one or more C18 sorbitan oleates, optionally in combination with one or more C18 (linoleic, stearic) and C16 (palmitic) fatty acid esters. Of course, the ester (I) is not limited to the fatty acid monoester of sorbitan, but also includes diesters and/or triesters and mixtures thereof. Whatever the case, it is advantageous for one of the selection criteria of the ester (I) to be that of an HLB of between 1 and 9, which confers on the ester (I) a pronounced lipophilicity. More particularly, the HLB of the ester (I) is preferably 2.5 to 5.5.

Thus, in practice it is preferred to have a mixture of predominantly sorbitan oleate and small amounts of sorbitan palmitate, sorbitan stearate and sorbitan linoleate. Thus, one possible example is the trademark SPAN83^*Or ARLACEL83^*Sorbitan sesquioleate sold by (ICI).

Another example of sorbitan (I) which may be mentioned is that under the trademark SPAN20^*Or ARLACEL20^*Sorbitan laurate sold by (ICI) or ALKAMULS SML (RHENE POULENC) and ARLACEL60^*Sorbitan stearates sold by (ICI) or ALKAMULSSMS (RHENE POLYULENC), but the species are not exhaustive.

It is clear that, according to the invention, the esters (I) also include all analogues and derivatives of sorbitan fatty acid esters.

As far as compound (II) is concerned, it is chosen from polyalkylene glycols, preferably polyethylene glycol (PEG) oleate and/or stearate and/or ricinoleate, preferably those in which the PEG has a molecular weight of less than or equal to 450, preferably of about 300.

Thus, one possible example is the trademark TILOL 163^*(UNION DERIVANSA) or EMULSOGEN A^*PEG300 monooleate sold by (HOECHST). Further examples of compounds (II) which may be mentioned are PEG400 monooleate of the type sold under the trade marks SECOSTER MO 400(STEPAN) or REMCOPAL (CECA), SIMULSOL M45^*(SEPPIC) or MYRJ 45^*Ethoxylated stearic acid with 8 ethoxy units (PEG 350 stearate), sold (ICI), and under the trademark CEREXEL4929^*(AUSCHEM SpA) or MARLOSOL R70^*PEG ricinoleate sold by (H * LS AG, STEPAN).

The alkylphenol alkoxylates (III) are preferably selected from polyethoxylated nonylphenols and/or octylphenols, polyethoxylated nonylphenols being particularly preferred.

In practice, it is, for example, a nonylphenol ethoxylate, which may advantageously be replaced or combined with one or more other alkylphenol alkoxylates. Thus, it may be advantageous to select from alkylphenol alkoxylates in which the alkyl group of the substituted phenol contains from about 1 to 20 carbon atoms, preferably from 5 to 20 carbon atoms. Furthermore, they can preferably also be selected from alkylphenol alkoxylates (e.g. ethoxylates) in which the alkoxy chain preferably contains 8 to 20, particularly preferably 8 to 15, alkylene oxide (e.g. ethylene oxide) groups per molecule.

In practice, polyethoxylated nonylphenol C is preferred₉H₁₉-C₆H₄-(OCH₂CH₂)_m-OH, wherein 8 < m < 15. In fact, it is important within the scope of the present invention to use polyethoxylated nonylphenols which are characterized not only by their hydrophilicity but also by their cloud point of greater than 30 ℃ (as determined according to standard DIN53917 using a 1% by weight aqueous solution). The combination of these characteristics in fact makes it possible to obtain not only a high-performance emulsifying system for preparing the water/fuel emulsion of the invention, but also a very pronounced temperature resistance capable of stabilizing the emulsion over a wide temperature range.

Further examples of compounds (III) which may be mentioned are polyethoxylated octylphenols, in particular those under the trademark OCTAROX^*(SEPPIC) or Sinopal OP_n ^*(SIDOBRE-SINNOVA).

In a preferred variant of the invention, compound (III) of the emulsifying system is a mixture of polyethoxylated nonylphenols, preferably 2 polyethoxylated nonylphenols having 9 and 12 ethylene oxide residues, respectively.

Without being limited thereto, the fuel to which the invention relates more particularly is a fuel in which the hydrocarbon or mixture of hydrocarbons forming part of its composition is selected from the group consisting of: diesel fuel, gasoline, kerosene, heavy oil, synthetic motor fuel, esterified or unesterified vegetable oil, and mixtures thereof.

More preferably, the invention relates to a particular group of fuels comprising motor fuels (diesel fuel, gasoline, kerosene, synthetic motor fuels, esterified or unesterified vegetable or animal oils) which are used as fuels in internal combustion engines or thermal engines.

In addition to hydrocarbons, water and emulsifying systems, and products for various purposes, may be added to the motor fuel or other fuel of the present invention.

For this reason, a major advantage of the hydrocarbon/water emulsions of the invention is that they provide a carrier for 2 different types of additives, namely a lipophilic carrier consisting of a hydrocarbon continuous phase and a hydrophilic carrier consisting of an aqueous phase. This greatly widens the possibility of adding reactive additive compounds. In fact, only oil soluble compounds have previously been readily added to motor fuels and other fuels. This constraint is currently eliminated by the present invention, especially when the amount of product soluble in water is much greater than the amount of product soluble in fuel according to the present invention.

Thus, it is contemplated in accordance with the present invention that octane enhancement of emulsified motor fuels or other fuels may be achieved by using additives that are soluble or miscible in water or hydrocarbons. Thus, these additives may comprise one or more octane enhancing products preferably selected from peroxides and/or nitrates and mixtures thereof. Alkyl nitrates, which are examples of cetane improvers, can be introduced into the emulsion via the hydrocarbon phase. The nitrate is the hydrophilic counterpart of the alkyl nitrate. Their salt properties allow it to be carried out via the aqueous phase.

The soot-inhibiting effect is another effect that the emulsion fuel of the present invention can give. The promoters acting are advantageously additives consisting of at least one metal or alkaline earth metal catalyst, preferably based on magnesium, calcium, barium, cerium, copper, iron or mixtures thereof, and capable of contributing to the post-combustion reaction of the carbon black. These catalytic promoters for decomposing soot are relatively easy to add, since they are generally compounds whose salts are water-soluble, which makes them compatible with the aqueous phase of the emulsion of the invention. These are not suitable for the conventional fuels of the prior art because they consist only of hydrophobic hydrocarbons.

In one variant of the invention, it is advantageous to impart antimicrobial or even bactericidal properties to the emulsified fuel, so that the emulsified fuel may optionally contain at least one antimicrobial agent, preferably a bactericide.

It may also prove valuable to the emulsions of the present invention for the wash function, and it is therefore appropriate to consider the case where the emulsion contains one or more detergents or detergent additives.

Nitric Oxide (NO) provided by ammoniated compounds (urea or ammonia)_x) The inhibiting function may also be obtained in fuels, in particular engine fuels.

The emulsion fuel may also be provided with an anti-freezing function by an anti-icing additive such as a glycol or salt solution.

More specifically, practical examples of the emulsion fuel composition of the present invention are as follows:

hydrocarbons 50 to 99%, preferably 65 to 99%,

water 0.1 to 50%, preferably 1 to 35%,

an emulsifying system of 0.05 to 5%, preferably 0.1 to 3%,

additives 0.01 to 5%, preferably 0.05 to 2%.

Furthermore, the present invention is in full agreement with the current trend of using "green gasoline" as a partial replacement for motor fuels, especially diesel. It is therefore advantageous to add at least one esterified or unesterified vegetable or animal oil and/or at least one extract thereof, preferably in an amount of from 1 to 60% by weight.

Possible examples are rapeseed oil, soybean oil or sunflower oil, esterified or not, which can be added to the fuel composition in an amount of, for example, 5%, 30% or even 50% by weight.

The invention also relates to an additive composition for motor fuels, essentially comprising:

-the above-mentioned emulsifying system

-and optionally at least one further additive, preferably chosen from the following products, namely: cetane improvers, catalytic promoters for soot combustion, biocides, detergents, ammoniated compounds, anti-freeze agents, esterified or unesterified vegetable oils, and mixtures thereof.

According to another aspect, the present invention relates to a process for the preparation of an emulsified fuel, characterized in that it essentially comprises the following steps, carried out in a simultaneous or non-simultaneous manner:

-a-taking at least one hydrocarbon, water and an emulsifying system comprising:

delta (I) at least one sorbitol ester having the formulaWherein: the radicals X being identical or different from one another, andand are each OH or R¹COO-wherein R¹Is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical, optionally substituted by hydroxyl groups, containing from 7 to 22 carbon atoms, R¹Preferably a fatty acid residue without a carboxyl end group, the ester (I) having an HLB of from 1 to 9;

delta (II) at least one fatty acid ester of the formulaWherein: -R²Is a linear or branched, saturated or unsaturated aliphatic hydrocarbon radical, optionally substituted by hydroxyl groups, containing from 7 to 22 carbon atoms, R²Preferably a fatty acid residue without a carboxyl end group, -R³Is straight or branched C₁-C₁₀Alkylene, preferably C₂-C₃Alkylene, -n is an integer greater than or equal to 6, preferably from 6 to 30, and-R⁴Is H, straight-chain or branched C₁-C₁₀Alkyl orWherein R is⁵And the above-mentioned R²The HLB of the ester (II), defined as being the same, is preferably greater than or equal to 9; and

delta (III) and/or at least one polyalkoxylated alkylphenol of the general formulaWherein: -R⁶Is straight or branched C₁-C₂₀Alkyl, preferably C₅-C₂₀Alkyl, -m is an integer greater than or equal to 8, preferably from 8 to 15, and-R⁷And R⁸Are respectively reacted with R in the formula (II)³And R⁴The polyalkoxylated alkylphenol (III) preferably has an HLB of from 10 to 15;

the HLB of the emulsifying system is 6-8, preferably 6.5-7.5;

Δ and other additives, as the case may be;

-b-mixing the components to form a water-in-oil emulsion;

c-and separating the emulsion to reduce the size of the droplets of the aqueous dispersed phase to an average size of less than or equal to 3 μm, preferably 2 μm, particularly preferably 1 μm, with a standard deviation of less than 1 μm.

Thus, the method of the invention can be summarized as: preparing an emulsion and separating the emulsion to reduce the droplet size of the aqueous dispersion to a monodisperse particle size of 1 μm, maintaining the particle size with a standard deviation of less than 1 μm.

The emulsification depends mainly on the emulsifying system. The emulsifying system preferably contains the following components:

(I)2.5 to 3.5 parts by weight, preferably 3 parts by weight,

(II)1.5 to 2.5 parts by weight, preferably 1.5 to 2 parts by weight,

(III)0.5 to 1.9 parts by weight, preferably 0.5 to 1.5 parts by weight.

The process of the present invention may be one of those used to prepare the above-described improved emulsion fuels (e.g., motor fuels). The features and observations given in the above section on the description of the products used in the emulsions can then be incorporated in their entirety as an extension to the disclosure of this section relating to the process.

The separation of the emulsion is a mechanical or thermodynamic treatment aimed at breaking the adhesive forces between the droplets in order to promote their subdivision. Preferred separation equipment for use in step (c) is of the type comprising a static mixer, a centrifugal or other type of pump, a colloid or other type of mill, a rotary mixer, an ultrasonic mixer and other equipment for breaking one liquid in another immiscible liquid.

In practice, static mixers, which are devices through which the emulsion passes at high speed and in which it undergoes a sudden change in direction and/or a sudden change in the diameter of the channels installed inside the mixer, can be used as separation devices. This results in a pressure loss which constitutes a factor in obtaining an emulsion suitable in terms of fineness and stability.

As a further example of equipment for preparing the emulsion, according to the design scale of the production, the equipment known under the trademark ULTRA-TURRAX can be used^*A rotary mixer sold as APV-BAKER, a high pressure homogenizer sold as APV-BAKER, or any equipment known to the person skilled in the art, which is easily inferred in scale.

In one variant of the invention, the mixing/separating steps b and c are carried out, for example, sequentially, i.e. the process comprises mixing the hydrocarbon, the emulsifying system and, if appropriate, the additives in a first stage, mixing the premix in a second stage and emulsifying with water.

In another variant of the invention, steps-a-to-c-are carried out in a continuous manner.

Steps-a-to-c-of the process of the invention are carried out at room temperature, which is also the temperature of the fluid and the feedstock used.

The emulsion fuel according to the invention and/or obtained according to the process of the invention is destined to have many industrial and commercial uses, thanks to the advantages in terms of stability, low pollution, low consumption and low price.

The main object of the present invention, although not the only one, is engine fuel, in particular diesel fuel. It is therefore possible to supply the possession of a vehicle or other machine with a thermal engine (for example a diesel engine) with an emulsified fuel containing 5-15% by weight of water without having to change the settings of the engine.

In addition, the engine can be operated efficiently and economically with low pollution using an emulsion fuel containing 35-45% by weight water with minor corresponding modifications.

This is an important advance in the field of engine fuels.

Side effects can also be expected in the fuel field for heating machines such as boilers, furnaces, gas turbines, generators, etc. The fuel of interest in this case may be heavy oil.

The invention will be more clearly understood by the following examples describing the preparation and composition and functional characteristics of the emulsified motor fuels of the invention, and the superiority of the emulsions of the invention in comparison with the closest prior art as demonstrated by comparative tests. These examples also highlight all the advantages and variants of these hydrocarbon/water emulsions.

The embodiments are illustrated in figures 1-4.

FIG. 1 shows an optical micrograph, at a given magnification, of a water/diesel fuel emulsion according to the invention, the droplet size of the aqueous dispersed phase being less than or equal to 1 μm.

FIG. 2 is an optical micrograph of the closest prior art water/diesel fuel emulsion at the same magnification as FIG. 1, the droplet size of the aqueous dispersed phase being greater than or equal to 10 μm.

FIG. 3 is a schematic diagram of an example of an emulsion separation apparatus used in the method of the present invention.

Fig. 4 shows a graph of engine speed cycles (rpm) as a function of time t (seconds) for a functional characterization test of the emulsified motor fuels of the present invention and of the prior art on a vehicle equipped with a diesel engine. (example II)

FIG. 5 shows a graph of the monodisperse particle size distribution of an emulsified motor fuel according to the invention, in which the mean diameter d of the droplets in the aqueous phase is plotted on the abscissa and Δ N/N is plotted on the ordinate, N being the total number of droplets and Δ N being the number of droplets having a given d.

Fig. 6 shows the variation periods of temperature and stirring applied to the summer formula (fig. 6.1) and the winter formula (fig. 6.2) in order to determine the stability of the emulsion fuel in use.

Examples

Example I

Several emulsions were prepared with different compositions of the emulsifying system using the above-described method comprising steps a), b) and c). For comparison, the total amount of surfactant was constant at 1.86% by weight (based on the total weight of the emulsion). The total amount of aqueous solution (water + optionally water-soluble additives such as biocides or anti-icing agents) is constant at 13% by weight of the total formulation.

The standard formulation is detailed in table 1. Table 1: formulation for comparative example

Compound (I)	Standard (provider)	Composition content (% by weight)
			Cetane improver	RV100(ELF ANTARFRANCE)	0.87
Emulsifying system	This example	1.86
			Water (W)	This example	13*
Diesel fuel	CEC RF 0387	84.27
			By usingAntimicrobial agents for diesel fuels	EB7301(ELF ANTARFRANCE)	A**
Antimicrobial agent for water	EB301W(ELF ANTARFRANCE)	B***

^*In the winter formulation 10% by weight of MEG (monoethylene glycol) was added to the water.^**A: 1 part/1000, based on the volume of diesel fuel^***B: 2 parts per 1000, based on the volume of water

The compositions of the emulsified systems tested are given in Table 2, which are given in Table 2 as the weight ratio of each component of the emulsified system and indicate that the emulsified system is 1.86% by weight of the final emulsion formulation.

Table 2 is explained in detail below:

@ compositions A-F are compositions of the present invention,

@ composition G is a composition as described in WO-93/18117,

@ compositions H-L serve as comparative examples to illustrate the advantages of the compositions of the present invention compared to those containing only 2 components or those compositions whose HLB is outside the claimed range. Table 2:

composition surfactant	A	B	C	D	E	F	G	H	I	J	K	L
													Sorbitan sesquioleate	3	3		1.5	1.5	1.5	1				1.5	1
Sorbitan monooleate			3			1.5		1.5	1.5	1.5
													Sorbitan laurate				1							1.5
Sorbitan stearate					1.5
													PEG300							1
PEG30 monooleate	2		2	2	2	1					2	2
													PEG60 monooleate								1
PEG300 ricinoleate		2				1
													Ethoxylated nonyl phenol with 9 EO	1	1.5	1	1	1	1.5	1					3
Ethoxylated nonyl phenol with 12 EO	0.5		0.5						1
													Ethoxylated nonyl phenol with 30 EO										1	1.5
Ethoxylated octylphenols with 9 EO					0.5
													HLB of the emulsifying System	7.5	7.7	7.6	6.5	7.8	7.9	8.2	10.1	8.1	9.2	9.6	10.1

The quality of the emulsion obtained is characterized by the following criteria. Standard of particle size

This is obtained from water droplets homogeneously dispersed in the continuous phase of the diesel fuel, which have a low polydispersity and an average particle size of less than 1 μm, with a standard deviation of less than 1 μm, as obtained by image analysis of micrographs. Stability criteria

This is a dual criterion which relates to stability under the conditions of use (dynamic behavior) and storage stability at different temperatures. Stability in use

Stability in use is demonstrated by observing the absence of creaming/sedimentation or other changes in a 1 liter sample placed in a flat bottom glass container (beaker type) and subjected to a period similar to the temperature change of the motor fuel in the tank, when the volume of the upper layer is greater than 5% of the total volume of the sample, or water is present at the bottom of the beaker, it is considered that creaming is occurring, corresponding to separation of the diesel fuel.

The case of temperature variation cycles for each formula ("summer formula" and "winter formula") is illustrated in fig. 6. It should be noted that the formulation must be stirred (mild mechanical stirring, about 60rpm) or left to stand, depending on the conditions of the cycle. Fig. 6.1 illustrates the period of the summer formulation and fig. 6.2 illustrates the period of the winter formulation. Storage stability

Storage stability is demonstrated by the absence of delamination/precipitation after 3 samples were stored in erlenmeyer flasks at0 ℃, 20 ℃ and 40 ℃ for 3 months at rest, respectively. As shown in Table 3, these criteria apply to the formulations obtained from compositions A-L. The results are shown in Table 3. Solutions of methanol (MeOH) in water, or rapeseed oil methyl ester (CME) in diesel fuel, were also added to certain formulations, in each case expressed as a volume percentage relative to the total formulation volume.

Table 3:

composition comprising a metal oxide and a metal oxide	A	A	A	B	C	D	E	F	G	H	I	J	K	L
															Formulation of	Summer season	Winter season	Summer season	Summer season	Summer season	Summer season	Summer season	Summer season	Summer season	Summer season	Summer season	Summer season	Summer season	Summer season
Special additives	-	-	5％CME	-	-	-	-	-	-	7％MeOH	7％MeOH	7％MeOH	-	-
															Dispersed particle diameter of ( d)	1 μm in size	1 μm in size	1 μm in size	1 μm in size	1 μm in size	1 μm in size	1 μm in size	1 μm in size	1-10 μm in length	1-20 μm in length	1-20 μm in length	1-20 μm in length	1-20 μm in length	1-20 μm in length
Stability in use	Stabilization	Stabilization	Stabilization	Stabilization	Stabilization	Stabilization	Stabilization	Stabilization	Instability of the film	Instability of the film	Instability of the film	Instability of the film	Instability of the film	Instability of the film
															Storage stability at0 deg.C at20 deg.C at40 deg.C	4w3m3m	3m3m4w	3w3m3m	4w3m6w	4w3m3m	3.5w6w4w	4w3m3m	4w3m6w	1h2w1d	1h1d1h	1h1d1h	1h1d1h	1h2h1h	1h2h1h

The following abbreviations are used in table 3:

h is hour

d is day

w is equal to week

m is equal to month

Storage stability was assessed by the length of time it took for the formulation to delaminate. Example II: preparation of Diesel Fuel/Water/emulsified System emulsion (according to the invention and according to the closest prior art) II.1. emulsion of the invention (3: 2: 1 emulsion) step-a-II.1.1. preparation of 200 kg of emulsion using the following starting materials:

-164 kg of diesel fuel,

4 kg of an Emulsifying System (ES),

2 kg of a cetane booster of the alkyl nitrate type sold by OCTEL under the reference CI0801,

30 kg of water. Ii.1.2. preparation of emulsification system:

a 4 kg emulsifying system was obtained by mixing the following components in a propeller mixer at several hundred revolutions per minute for several minutes:

3 parts by weight, i.e. 2 kg of SORBITHOM sold by UNION DERIVAN SA^*S06，

2 parts by weight, i.e. 1.333 kg sold by UNION DERIVAN SA under the trade name TILOL^*163 of a polyethylene glycol monooleate ester of formula (I),

1 part by weight, i.e. 0.666 kg, of UNION DERIVAN SA under the trademark NONILFENOL^*Such nonylphenol ethoxylates are marketed by 9M OXIETHIL.

The HLB of the emulsified system was 7.2. Step-b-and-c-: premixing, emulsion formation and separation

4 kg of the emulsifying system are added to 164 kg of diesel fuel, the mixture is stirred with a propeller stirrer rotating at several hundred revolutions per minute, 2 kg of cetane improver are added during stirring, and 30 kg of water are added before the separation.

The apparatus used is shown in fig. 3, and comprises:

a container 1 for containing a liquid 2, the liquid 2 consisting of all the components of the emulsion except water before separation or of an emulsion stable at the end of separation,

a separation device 3 in a strict sense,

and a water feed line 4.

Vessel 1 is a conventional vessel to which a diesel fuel/emulsifying system/additive premix is added, either continuously or discontinuously.

The separation device 3 comprises a static mixer 5 of the type SMV-4DM20 (5 mixing elements in series) marketed by SULZER, which mixer comprises a hollow cylinder with an inlet and an outlet for the fluid, inside which there is a tortuous passage for the fluid, which passage is constituted by several transverse partitions equipped with inclined grooves forming the passage for the fluid. The outlet of the static mixer 5 is connected to a line 6 extending from the inside of the vessel 1 (line 6 carries the effluent into the vessel 1), while its inlet is connected to a line 7 equipped with a pump 8, the free end 9 of the line 7 being immersed in the bath of the premix of the emulsion 2 contained in the vessel 1. The pump 8 is also connected to a water feed pipe 10 having a valve 11, forming the above-mentioned line 4 upstream and in the vicinity of the inlet of the pump 8. The apparatus can ensure a large pressure loss at a normal flow rate to produce dispersion of the emulsion.

The separation carried out with this apparatus was carried out in the following manner:

after the vessel 1 is filled with the diesel fuel/ES/additive pre-mixture, the pump 8 is turned on to circulate the fluid through the static mixer 5. The electronic valve 11 is then opened to ensure that water enters and is mixed with the DF/ES/a pre-mix in pump 8, and the mixture is then sent to a static mixer where the required separation takes place. The pressure of the fluid at the outlet of the pump 8 was 5 Mpa.

In this example, 30 kg of water are added over about 1 minute. The system was operated in a loop to ensure separation for 30 minutes. 200 kg of an emulsion having the characteristics of the invention are obtained. The emulsion was white and had a kinematic viscosity at20 ℃ of 6.2 mm 2/s. II.2 emulsions according to the prior art ratio (1: 1 emulsion)

200 kg of emulsion are prepared with 164 kg of diesel fuel, 4 kg of an emulsifying system, 2 kg of an additive containing magnesium oxide and toluene and 30 kg of water.

SORBITHOM^* S06：TILOL 163^*：NONILFENOL^* 9MOXIETHIL^*In a ratio of 1: 1 instead of 3: 2: 1 as described in section II.1 above, the HLB of the emulsifying system is 8.7.

The procedure used is described in PCT patent application WO 93/18117.

200 kg of emulsion thus obtained are white. Example III: structural and functional Properties of the emulsions I.1. and I.2. of example I A-stability 1-microscopic Observation

The differences in the size distribution of the droplets in the aqueous dispersed phase are clearly shown in figures 1 and 2. In the case of emulsion ii.1. a uniformity of the droplet diameter with a maximum of about 1 μm can be observed, which establishes the monodispersity of the droplets. In contrast, the water droplets of the known emulsion II.2. show a large size inhomogeneity, the majority of which have a droplet size of more than 5 μm, a significant amount of which have a droplet size of more than 10 μm. 2-stability test for practical application on public transport vehicles

The vehicle used for these tests was a Reynolds Industrial vehicle of the R312 type^*The lowest point of the diesel fuel tank of the automobile is provided with a water drainage channel to avoid the stop of the injection pump when the automobile brakes, turns or climbs.

The first vehicle contained 300 liters of the II.1. emulsion and the second comparative vehicle contained 300 liters of the II.2. emulsion.

The 2 vehicles run around the city for 100 kilometers.

Then parked for 48 hours.

Then 2 vehicles were started successfully, but after idling for 15-30 seconds, the control vehicle was stopped, but the fuel of the vehicle was not made from the emulsion of the present invention.

The stoppage of the control car can be explained by the lack of stability of the emulsion ii.2, due to the phase separation of the fuel due to gravity settling during the 48 hours of parking. Thus, when fuel is withdrawn at the bottom of the tank, a large amount of separated phase water has been pumped into the combustion chamber by the injection pump. These very large amounts of water irreversibly stop the engine.

In addition, attention must be paid to the phenomenon of turbulence caused by the emulsion II.2 (unstable, compared to the emulsion II.1. according to the invention) in all the injection line components of diesel engines. These lines are equipped with filters with 1-2 μm cut-off holes corresponding to the operating clearances of the syringe pumps and syringes.

In this case, when a water droplet having a diameter greater than or equal to the filter cut-off hole comes into contact with the filter, the water will not pass through or will hardly pass through the filter hole, and then the water will be caught and accumulated in the filter, which is particularly harmful. In addition, undesirable clogging and clogging of the filter can occur.

This phenomenon can be illustrated by incorporating an emulsion loop in the filter with a 1-2 μm cut-off. Operating at constant pressure, the blockage can be evaluated:

by measuring the pressure loss and the reduction in flow rate,

and collecting the water or water-rich emulsion in the form of large droplets at the bottom of the filter.

It should be noted that the risk and probability of clogging is increased by the phenomenon of icing of water which may occur under winter driving conditions if prior art emulsions containing water droplets with a d greater than 5 μm are used instead of the emulsions according to the invention. B. Water/Diesel Fuel emulsion II.1 of the invention Performance in Diesel Engine operation 1 RVI312 vehicle with direct injection Diesel Engine

The RVI312 vehicle described above was subjected to a series of tests as shown in fig. 4 by passing it through a work cycle comprising an idle phase R, an acceleration phase a, a full speed phase P (steady state) and a deceleration phase D. The speed was varied from 500rpm for the R phase to 2200rpm for the P phase. The duration of the RAPD phase of the duty cycle is given in the figure. This cycle was repeated several tens of times on RVI312 vehicles under test conditions. 1.1. Determination of maximum opacity of the Smoke in stage A

The measurement was performed with a Technotest model 490 (on-line) full flow darkness meter.

5 measurements were carried out with the emulsion II.1 according to the invention and with pure diesel fuel as control. It should be noted that the diesel fuel used to prepare the emulsion used was the same as the control diesel fuel.

The maximum opacity (expressed in m-1) averaged 3.51 for pure diesel fuel and 1.22 for the emulsion of the invention.

This indicates a 65% reduction in opacity with the emulsions of the present invention. 1.2. Average content of invisible pollutants (NO and CO) and visible pollutants (smog)(i)NO_x：

Measuring the NO of the pollutant by chemiluminescence method with COSMA analyzer_x。

As described above, 5 determinations were made for pure diesel fuel and emulsions prepared from diesel fuel, and the source of diesel fuel used to prepare the diesel fuel emulsions was the same as the pure diesel fuel used as a control. The following results were obtained:

-pure diesel fuel: 266vpm (parts per million volume)

-an emulsion: 224vpm was reduced by 16%. (ii) CO 2

The exhaust gas was analyzed for this contaminant using infrared absorption with a COSMA analyzer. The conditions used are identical to those of (i).

The following results were obtained:

-diesel fuel: 475vpm

-an emulsion: 216vpm means a 33% reduction in CO. (iii) Solid particles:

the solid particles were determined according to the standardised method ISO8178 using a small dilution tunnel.

The conditions used were the same as above.

The following results were obtained:

-pure diesel fuel: 45.6 mg/m³

-an emulsion: 29.6 mg/m³Namely, the solid particles of the emulsion are reduced by 35 percent by adopting the emulsion. 2. Model 106-TU D5 Indirect injection Diesel Engine, atmospheric type

Using the above logo 106 automobile, the standardized method for automobile approval by the european union, namely: ECE (urban loop) and EUDC (suburban loop-engine hot), these tests were performed.

The average level of contaminants was determined under these test conditions. (i) NO:

-diesel fuel: 0.64 g/km

Inventive emulsion ii.1.: a reduction of 16% at 0.54 g/km. (ii) Unburned hydrocarbons;

these measurements were carried out using a heated flame ionization analyzer under standard conditions defined by the ECE/EUDC standard.

The following results were obtained:

-pure diesel fuel: 0.08 g/km

-an emulsion: the reduction is 8.8% at 0.07 g/km. (iii) Solid particles:

-diesel fuel: 0.04 g/km

Emulsion ii.1.: a reduction of 46% is obtained at 0.02 g/km. Example IV: preparation and description of a Water/Diesel Fuel emulsion containing 35% by weight of Water IV.1 preparation

The emulsion composition was prepared as follows:

-122 kg of diesel fuel,

4 kg of an emulsion system of type 3: 2: 1 from example II.1 (2% emulsion system), based on the total weight of the emulsion,

4 kg of a CI0801 cetane improver from OCTEL,

70 kg of water (35%).

The preparation process is the same as in example ii.1. Description of the invention IV.2

For volume of about 500 cm³The direct injection type single cylinder engine of (1) was subjected to an effect test.

The emulsion prepared in iv.1. is stable and has substantially the same size distribution of aqueous droplets as the emulsion of example ii.1.

The engine speed during the test was 2250rpm and the mean effective pressure was 8.4MPa (full load).

Measurement of pollutant gases in exhaust gases: (I) no recirculation of exhaust gases to the gas inlet

The measurement method is the same as described above.^*NO_x：

-pure diesel fuel: 23.7 mg/sec

-emulsion iv.1.: a 54% reduction at 11.0 mg/sec.^*Smoke-BOSCH Point

-pure diesel fuel: 1.1

-emulsion iv.1.: a reduction of 82% is obtained at 0.2. (ii) 16.5% of the exhaust gas is recirculated to the gas inlet^*NO_x：

-pure diesel fuel: 7.95 mg/sec

-emulsion iv.1.: a reduction of 38% was obtained at 4.98 mg/sec.^*smoke-BOSCH point-pure diesel fuel: 3.6-emulsion iv.1.: 1.6 the smoke is reduced by 55%.

It is well known that a value of 3.6 is unacceptable, while a value of 1.6 is fully permissible.

Claims (41)

1. An improved emulsified fuel comprising an aqueous emulsion in at least one hydrocarbon characterized in that: → the emulsion contains an emulsifying system containing: delta (I) at least one sorbitol ester having the formula

Wherein:

the radicals X, equal to or different from each other, are each OH or R¹COO-and at least one group X is R¹COO-form, wherein R¹Is optionally substituted by hydroxy and containsA straight or branched, saturated or unsaturated aliphatic hydrocarbon group of 7 to 22 carbon atoms,

the ester (I) has an HLB of from 1 to 9;

delta (II) at least one fatty acid ester of the formula

Wherein:

-R²is a straight-chain or branched, saturated or unsaturated aliphatic hydrocarbon group which is optionally substituted by a hydroxyl group and has 7 to 22 carbon atoms,

-R³is straight or branched C₁-C₁₀An alkylene group or a substituted alkylene group,

-n is an integer greater than or equal to 6, and

-R⁴is H, straight-chain or branched C₁-C₁₀Alkyl or

Wherein R is⁵And the above-mentioned R²The definition is the same as that of the prior art,

the ester (II) has an HLB greater than or equal to 9; and

delta (III) at least one polyalkoxylated alkylphenol of the general formula

Wherein:

-R⁶is straight or branched C₁-C₂₀An alkyl group, a carboxyl group,

-m is an integer greater than or equal to 8, and

-R⁷and R⁸Are respectively reacted with R in the formula (II)³And R⁴The definitions of (A) and (B) are the same,

the polyalkoxylated alkylphenol (III) has an HLB of 10 to 15;

the proportions of compounds (I), (II) and (III) in the emulsifying system are as follows:

(I)2.5 to 3.5 parts by weight of,

(II)1.5 to 2.5 parts by weight,

(III)0.5 to 1.9 parts by weight,

→ the total HLB of the emulsifying system is 6-8;

→ concentration of the emulsifying system less than or equal to 3% by weight relative to the total weight of the fuel

→ the emulsion is prepared in such a way: the average droplet size of the aqueous dispersed phase is less than or equal to 3 μm with a standard deviation of less than 1 μm;

→ the emulsion contains at least 5% by weight water.

2. Fuel according to claim 1, characterized in that in the compound (I) or (I') contained in the emulsifying system, R¹Is a fatty acid residue without a carboxyl end group.

3. Fuel according to claim 1, characterized in that in the compound (II) contained in the emulsifying system, R²Is a fatty acid residue without a carboxyl end group.

4. Fuel according to claim 1, characterized in that in the compound (II) contained in the emulsifying system, R³Is straight or branched C₂～C₃An alkylene group.

5. A fuel according to claim 1, characterized in that in the compound (II) contained in the emulsifying system, n is an integer from 6 to 30.

6. Fuel according to claim 1, characterized in that in the compound (III) contained in the emulsifying system, R⁶Is C_5-20Straight or branched chain alkyl.

7. A fuel according to claim 1, characterized in that in the compound (III) contained in the emulsifying system, m is an integer from 8 to 15.

8. A fuel according to claim 1, characterised in that the proportions of compounds (I), (III) and (III) in the emulsifying system are:

(I)3 parts by weight of a reaction product of (B),

(II)1.5 to 2 parts by weight,

(III)0.5-1.5 parts by weight.

9. A fuel according to claim 1 characterised in that the total HLB of the emulsifying system is from 6.5 to 7.5.

10. A fuel according to claim 1, characterised in that the average droplet size of the aqueous dispersed phase in the emulsion is less than or equal to 2 μm.

11. A fuel according to claim 10, characterised in that the average droplet size of the aqueous dispersed phase in the emulsion is less than or equal to 1 μm.

12. A fuel according to claim 1, characterized in that the concentration of said emulsifying system is less than or equal to 2% by weight relative to the total weight of the fuel.

13. A fuel according to any one of claims 1 to 12, characterised in that the compound (I) is selected from sorbitan oleate, the compound (II) is selected from polyethylene glycol oleate and/or stearate and/or ricinoleate, and the compound (III) is selected from polyethoxylated nonylphenol and/or octylphenol.

14. A fuel according to claim 13, characterized in that said compound (I) is selected from sorbitan sesquioleate, said compound (II) is selected from polyethylene glycol oleates and/or stearates and/or ricinoleates in which the polyethylene glycol has a molecular weight of less than or equal to 450, and said compound (III) is selected from polyethoxylated torr-based phenols.

15. A fuel according to claim 13, characterised in that the compound II is selected from polyethylene glycol oleates and/or stearates and/or ricinoleates in which the polyethylene glycol has a molecular weight of 300.

16. A fuel according to any one of claims 13 to 15, characterised in that the compound (III) in the emulsifying system is a mixture of polyethoxylated nonylphenols.

17. A fuel according to claim 16, characterised in that the compound (III) in the emulsifying system is a mixture of 2 polyethoxylated nonylphenols having 9 and 12 ethylene oxide residues respectively.

18. A fuel according to any one of claims 1 to 17, characterised in that the hydrocarbon is selected from the following products: diesel fuel, gasoline, kerosene, heavy oil, synthetic motor fuel, esterified or unesterified vegetable or animal oil, and mixtures thereof.

19. A fuel according to any one of claims 1 to 18, characterised in that it contains, in addition to the emulsifying system, an additive consisting of one or more octane enhancing compounds.

20. A fuel according to claim 19, characterised in that the octane enhancing compound is selected from peroxides and/or nitrates and mixtures thereof.

21. A fuel according to any one of claims 1 to 20, characterised in that it comprises in addition 0.01 to 5% of the following additives:

-at least one metal or alkaline earth metal catalyst for the post-combustion reaction of carbon black;

-optionally at least one antimicrobial agent;

-and optionally at least one antifreeze agent selected from glycols;

besides, it also contains 50-99% of hydrocarbon, 0.1-50% of water and 0.05-5% of emulsifying system.

22. A fuel according to claim 21, characterized in that the catalyst is based on magnesium, calcium, barium, cerium, copper, iron or mixtures thereof.

23. A fuel according to claim 21, characterised in that said anti-microbial agent is a bactericide.

A fuel according to any one of claims 21 to 23, characterised in that it comprises 65 to 99% hydrocarbon, 1 to 35% water, 0.1 to 3% emulsifying system and 0.05 to 2% additive.

25. A fuel according to any one of claims 1 to 24, characterised in that it further comprises at least one esterified or unesterified vegetable oil and/or at least one extract thereof.

26. A fuel according to claim 25, characterized in that said at least one esterified or unesterified vegetable oil and/or at least one extract thereof is present in an amount of 1-60% by weight.

27. Additive composition for fuels, in particular motor fuels, characterized in that it essentially comprises:

-an emulsifying system as defined in any one of claims 1 to 26,

-optionally at least one further additive.

28. Additive composition according to claim 27, characterized in that the additive is selected from the group consisting of cetane improvers, catalytic promoters for the combustion of carbon black, biocides, detergents, ammoniated compounds, antifreeze agents, esterified or unesterified vegetable and animal oils, and mixtures thereof.

28. The preparation method of the improved emulsified fuel is characterized by mainly comprising the following steps which are carried out in a simultaneous or non-simultaneous mode:

-a-taking at least one hydrocarbon, water and an emulsifying system comprising:

delta (I) at least one sorbitol ester having the formula

Wherein:

the radicals X, equal to or different from each other, are each OH or R¹COO-and at least one group X is R¹COO-form, wherein R¹Is a straight-chain or branched, saturated or unsaturated aliphatic hydrocarbon group which is optionally substituted by a hydroxyl group and has 7 to 22 carbon atoms,

the ester (I) has an HLB of from 1 to 9;

delta (II) at least one fatty acid ester of the formula

Wherein:

-R²is a straight-chain or branched, saturated or unsaturated aliphatic hydrocarbon group which is optionally substituted by a hydroxyl group and has 7 to 22 carbon atoms,

-R³is straight or branched C₁-C₁₀An alkylene group or a substituted alkylene group,

-n is an integer greater than or equal to 6, and

-R⁴is H, straight-chain or branched C₁-C₁₀Alkyl or

Wherein R is⁵And the above-mentioned R²The definition is the same as that of the prior art,

the ester (II) has an HLB greater than or equal to 9;

delta (III) at least one polyalkoxylated alkylphenol of the general formula

Wherein:

-R⁶is straight or branched C₁-C₂₀An alkyl group, a carboxyl group,

-m is an integer greater than or equal to 8, and

-R⁷and R⁸Are respectively reacted with R in the formula (II)³And R⁴The definitions of (A) and (B) are the same,

the polyalkoxylated alkylphenol (III) has an HLB of 10 to 15,

the proportions of compounds (I), (II) and (III) in the emulsifying system are as follows:

(I)2.5 to 3.5 parts by weight of,

(II)1.5 to 2.5 parts by weight,

(III)0.5 to 1.9 parts by weight,

the HLB of the emulsifying system is 6-8;

Δ and optionally other additives;

-b-mixing the components to form a water-in-oil emulsion;

-c-and separating the emulsion to reduce the droplet size of the aqueous dispersed phase to an average size of less than or equal to 3 μm with a standard deviation of less than 1 μm.

29. The process according to claim 28, characterized in that in the compound (I) or (Γ) comprised in the emulsifying system, R¹Is a fatty acid residue without a carboxyl end group.

30. The process according to claim 28, characterized in that in the compound (II) contained in the emulsifying system, R²Is a fatty acid residue without a carboxyl end group.

31. The process according to claim 28, characterized in that in the compound (II) contained in the emulsifying system, R³Is straight or branched C₂～C₃An alkylene group.

32. The process according to claim 28, characterized in that in the compound (II) contained in the emulsifying system, n is an integer from 6 to 30.

33. The method of claim 28, characterized in that in being comprised in said emulsifying systemIn the compound (III), R⁶Is C_5-20Straight or branched chain alkyl.

34. The process according to claim 28, characterized in that in the compound (III) contained in the emulsifying system, m is an integer from 8 to 15.

35. The method of claim 28, characterized in that the total HLB of the emulsifying system is 6.5 to 7.5.

36. A method according to claim 28, characterised in that the droplet size of the aqueous dispersed phase in the emulsion is less than or equal to 2 μm.

37. A method according to claim 28, characterised in that the droplet size of the aqueous dispersed phase in the emulsion is less than or equal to 1 μm.

38. The process according to claim 28, characterized in that the proportions of compounds (I), (II) and (III) in the emulsifying system are:

(I)3 parts by weight of a reaction product of (B),

(II)1.5 to 2 parts by weight,

(III)0.5-1.5 parts by weight.

39. The method according to any of claims 28-38, characterized in that the separation equipment used in step-c-is equipment comprising sieves, static mixers, rotating mixers and ultrasonic mixers.

40. Apparatus for implementing the method of any one of claims 28 to 39, characterized in that it essentially comprises:

-at least one container (1) able to contain a hydrocarbon/emulsifying system/additive pre-mix (2) and/or an emulsion containing all or part of the water that forms part of it,

-a device (3) for separating the emulsion, comprising at least one static mixer (5) whose inlet is connected to a line (7), the line (7) being equipped with at least one pump (8), the free end (9) of the line (7) being immersed in the premix or emulsion bath (2) of the vessel (1), the outlet of the mixer (5) being connected to a device (6), the device (6) carrying the effluent into the vessel (1),

-and a water feed circuit (4) comprising at least one line (10), the line (10) being equipped with a valve (11) and being connected to the line (7) upstream of the pump (8).