EP1051464A1

EP1051464A1 - Ef

Info

Publication number: EP1051464A1
Application number: EP99958271A
Authority: EP
Inventors: César Magnin; Jean-Bernard Prudhomme; Philippe Schulz
Original assignee: Elf Antar France
Current assignee: Elf Antar France
Priority date: 1998-12-08
Filing date: 1999-12-08
Publication date: 2000-11-15
Anticipated expiration: 2019-12-08
Also published as: JP2002531685A; PL190169B1; PT1051464E; CN1224680C; ATE269892T1; PL343118A1; DK1051464T3; FR2786780A1; HUP0103523A2; ES2224721T3; BR9907726A; TR200002295T1; HUP0103523A3; AU1567500A; MXPA00007747A; EP1051464B1; DE69918269T2; CA2320342A1; KR20010040739A; RU2227155C2

Abstract

The invention concerns a method for preparing an emulsified fuel, such as for example a water-in-diesel oil or a water-in-gasoline emulsion, to be used for powering spark ignition engines or in energy-producing appliances. The invention aims at enabling the production on an industrial scale of emulsions stable for at least four months, wherein the external phase is organic and the internal phase aqueous. Said aim is achieved by the inventive method which consists in mixing the organic phase, the aqueous phase and additives to homogenise into a volume V of liquid comprising the organic phase and the additives by circulating the latter at a homogenising capacity at a flow rate Qc such that the ratio Qc/V ≥ 100h-1, in circulating the homogenised liquid in an external branch loop comprising an emulsifier system with a flow rate Qcirc such that the ratio V/Qcirc ranges between 0 and 2 h, and in supplying the branch loop with water upstream of the emulsifier system, until the desired characteristics of storage stability for the emulsion are obtained. The invention also concerns the device for implementing said method.

Description

PROCESS FOR PREPARING AN EMULSIFIED FUEL AND ITS IMPLEMENTING DEVICE

TECHNICAL AREA :

The present invention relates to a process for preparing an emulsified fuel, that is to say an emulsified mixture of water and at least one organic compound, with a view to distributing it like other liquid fuels, in particular fuels tankers and domestic fuels. In these fuels, the organic phase is a petroleum product, a vegetable or animal oil or any other fuel used in particular in motor vehicles and domestic boilers and more generally for supplying internal combustion or other engines and for supplying energy production apparatus. The invention also relates to its industrial implementation device in the form of fixed or transportable industrial units.

PRIOR ART:

The use of emulsified fuel is well known to those skilled in the art, but difficult to implement due to the lack of stability of the combustible emulsions used. The storage stability of these emulsions was the subject of a definition by the Hydrocarbons Department of the French Ministry of Industry. According to this administration, a water-in-diesel emulsion is considered to be stable on storage at room temperature, if no phase shift is observed after at least four months.

Thus, the patents DE 19 704 874, DD 216 863 and WO 95/33023 describe in particular methods and devices for obtaining combustible emulsions on board of land vehicles, of the Diesel type. Such fuels are obtained by mixing the components and emulsifying this mixture on the vehicle itself. The emulsions described are emulsions in which the external phase can be aqueous, which can be subsequently reversed by dilution in an organic phase, as in patent DE 19 704 874. The emulsion described in patent WO 95/33023 contains less than 20% by volume of water, the aqueous phase constituting the external phase.

Similarly, in patent application WO 92/11927, it is a question of preparing a concentrated emulsion containing from 40 to 80% by volume of water, this preparation consisting in separately preparing a fuel / emulsifier mixture and a water / alcohol, to introduce these two mixtures at two separate locations in a circulation loop comprising an emulsion pump also having the function of circulating the assembly in said loop. The concentrated emulsion formed is collected at another level on the loop. In patent application WO 95/27021, an emulsified aqueous fuel is claimed, a hydrocarbon in water containing 20 to 80% by volume of water, water constituting the external phase of the emulsion, 2 to 20% by volume of an alcohol, the balance being formed of hydrocarbons and a nonionic emulsifier. In this application, the hydrocarbon is gasoline, kerosene, gas oils, synthetic fuels or derivatives of vegetable or animal oils. This application also claims a process for the bulk preparation of this emulsified fuel, stable for at least three months and consisting, on the one hand, of a mixture of the hydrocarbon and the emulsifier and, on the other hand, 'a mixture of water and alcohol.

In none of these patent applications is described a method for the industrial preparation of stable emulsified fuels in which the external phase of the emulsion consists of the organic phase. However, for obvious reasons of compatibility of the fuel with the equipment present from the tank to the system for introduction into the engine, it is preferred to use a fuel whose external phase is identical to that of the fuel for which this equipment has been sized. In the case of emulsified fuels whose external phase is aqueous, phenomena of corrosion of metal surfaces and / or premature wear of elastomeric materials can occur. In addition, the combustion of a water in oil emulsion is improved compared to that of an oil in water emulsion because the sudden vaporization of the water droplets, dispersed in the oil, significantly improves the dispersion of the hydrocarbons in the chamber. combustion (SAE 89 0449 and SAE 92 0464 from M. Tsukuhara et al., SAE 92 0198 from N. Sawa et al.). The Applicant has proposed in patent application WO 97/34 969 such a fuel.

The present invention relates to the preparation of such emulsified fuels whose external phase is an organic compound and which can be stable for a sufficiently long period, for example greater than 4 months, to allow their storage in industrial quantities and subsequently their distribution as fuels. or fuel at the pump.

DEFINITION OF THE INVENTION:

The present invention therefore relates to a process for the preparation, on an industrial scale, of an emulsified fuel water / organic compound (s), of organic external phase, and containing less than 20% by volume of water and at least one additive necessary to form the emulsion, this process being characterized in that it essentially consists:

A 1 A to introduce the additive (s) into a capacity equipped with at least one agitator with axial pumping flow rate containing at least the organic compound (s),

A 2 A to homogenize the volume V of liquid, organic compounds / additives, obtained using the agitator, so that the ratio Qc / V, corresponds to

Qc / V ≥ 100 h ^"1 preferably Qc / V> 250 h ^{" 1} and more preferably 1000 h ^"1 > Qc / V> 300 h ^{" 1} , Qc corresponding to the circulation rate of the liquid inside the capacity .

A 3 A to circulate the liquid, homogenized by means of the stirrer, in the bypass loop opening into the tank, and through at least one foam concentrate system arranged on said loop at a rate such that the ratio

V / Qcirc corresponds to: 0 h <V / Qcirc <2 h preferably 0 h <V / Qcirc <1,8 h and more preferably 0 h <V / Qcirc <1,5 h. with Qcirc corresponding to the flow rate of the liquid in the bypass loop.

A 4 A to supply the bypass loop upstream of the emulsifier system, with the aqueous phase necessary for the formation of the emulsion,

A 5 A and finally to maintain the homogenization in the tank, and the circulation of the liquid in the bypass loop until the desired characteristics of storage stability of the emulsion are obtained.

This preparation process of the present invention allows the preparation of emulsions of industrial volume, the water / liquid ratio homogenized in the capacity, being adjusted during manufacture in order to obtain the desired water content in the final combustible emulsion .

To obtain a good quality and stable emulsion over time, the stages of preparation of the homogenized liquid, organic compound (s) / additives, and of emulsification of the liquid with water are very important or even essential. Thus, it will be possible during the stages of homogenization and emulsification to heat and cool the liquid contained in the homogenization capacity.

BEST WAY TO IMPLEMENT THE INVENTION:

According to a preferred embodiment, the method according to the invention comprises a step lp prior to step 1, during which the additives necessary for the emulsion are mixed with at least one solvent.

The mixture of additives from step lp is advantageously obtained by diluting the additives in at least one solvent, starting with the most viscous additive and ending with the least viscous additive, each of these dilutions being preferably carried out in a capacity equipped with at least one flow agitator axial pumping for good homogeneity and possibly heating and cooling means of its capacity in order to improve their dilution and their homogenization.

During the stages of introduction and homogenization of the additives, and of the organic compounds in the homogenization capacity, it is imperative that the additives be dispersed throughout the entire volume of liquid obtained in a homogeneous manner, so that at the time of adding water all the additives necessary for the formation of the emulsion and for its maintenance, are present in sufficient and identical amounts throughout the organic compound. It is not excluded that additives capable of improving one or more properties required of the fuel according to the invention are introduced into the emulsion formed, either in the organic phase or in the aqueous phase.

In the context of the present invention, the solvent used in step lp is chosen from the group comprising at least one of the organic compounds used to form the emulsion, a solvent of alcohol, ketone, ester or ether type, or one of the additives of the emulsion whose solvent properties with respect to the other additives are sufficient.

The organic compound (s) according to the present invention is (are) chosen from petroleum fuels, gasoline, gas oils, kerosene, household fuels, these products possibly being supplemented with oxygenated compounds of TAME type (methyltertioamylether) or MTBE (methyltertiobutylether) for gasolines, of type DME (dimethylether), DMM (dimethoxymethane), or TEP (triethoxypropane) for gas oils, or vegetable or animal oils, refined or not, or their esterified derivatives .

According to a preferred characteristic of the invention, the foam concentrate system will comprise at least one device allowing the circulation of the liquid in the bypass loop.

The aqueous phase is injected into the homogenized liquid, organic compound (s) / additives, at a flow rate Qe proportional to the flow rate Qc of circulation of the volume V of liquid in said capacity, the ratio Qe / Qc varying from 0 to 1 Preferably, the Qe / Qc ratio varies from 0.05 to 0.20. This aqueous phase may also contain specific additives aimed at avoiding contamination of the water such as biocides or even antifreezes, especially in winter to avoid the crystallization of the water and the breaking of the emulsion.

The present process is particularly suitable for the preparation of water-in-oil emulsified fuels, in particular water / diesel or water / gasoline emulsions for combustion in internal combustion engines installed on motorized vehicles, in particular urban vehicles for which a Reducing pollutant emissions from the exhaust by immediate action on the fuel is particularly desirable. Likewise, the use of such a fuel can be envisaged for railway or marine applications or even in stationary boilers or diesel engines of thermal power plants.

A second object of the invention is the device for implementing the method, characterized in that it comprises a closed capacity (1) equipped with an axial flow agitator (2) comprising three fluid inlet pipes (3 ) (4), and (5), respectively for the organic compound (s), the additives and the emulsion, a fluid outlet pipe (6), and optionally a heating system and / or cooling, the pipes (5) and (6) being connected to a circulation pipe (7) defining a bypass loop, comprising a water supply pipe (9), an emulsifier system (8 ) and finally a discharge line (10) of the emulsified fuel. This pipe (10) could be placed either on the tank (1) or on the bypass loop (7), upstream or downstream of the foam concentrate system (8).

In the device according to the present invention, the line (4) allows the injection of the mixture of additives, initially prepared and homogenized in a second capacity (11) provided with an axial flow agitator (12) to ensure homogenization of said mixture of additives, and comprising inlet (13) and outlet (4) pipes for the mixture, and optionally a heating and / or cooling system for said capacity (11). It is possible to use any type of thermal insulation, heating and / or cooling adapted to an industrial size capacity. The lines (3) and (4) could be combined into one for the entry of organic compounds and / or additives into the capacity (1). In the capacities (1) and (11) the agitators (2) and (12) must allow homogenization of all the liquid contained and promote the circulation of the liquid in the capacity, without creating a shear gradient from point to point. 'other, that is to say by homogenizing at a defined and adjustable shear rate. As agitators (2) and (12), preference is given to agitators with axial flow allowing longitudinal agitation relative to the axis of rotation and with high pumping capacity.

The emulsifier system (8) according to the present invention comprises at least one emulsifier pump and / or one or more dynamic mixers equipped with rotor / stator with narrow gap (fixed or variable) and rotating at high speed, that is to say at more than 2000 revolutions per minute.

Downstream or upstream of this foaming system or as a replacement thereof, one or more static mixers and / or one or more other foaming agents operating in a mechanical mode can be placed on the bypass loop (5, 6, 7). , using ultrasound and / or microwaves helping to form the emulsion.

In order to favor the dispersion of water droplets in the oil, it is possible to adapt to the water injection pipe at least one dispersing system of droplets such as for example a cartridge or a distributor made of sintered metal or of stainless steel fiber comprising very fine pores of one to several tens of microns.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached single Figure is a simplified diagram of an example of the preferred embodiment of the device of the invention. In the remainder of this description, examples are given to illustrate the problems encountered and the manufacturing constraints making it possible to obtain fuels which are suitably emulsified and stable, but cannot be used to limit their scope. EXAMPLE I

The present example describes the procedure followed in the laboratory for preparing a water / diesel emulsion according to the method of the invention. In a 1.5 liter cylindrical beaker, 22.9 g of the mixture of additives as described in application WO 97/34969 are then poured, followed by 673J g of diesel fuel meeting the European specifications of standard EN 590. In a second beaker, introduced 104 g of water.

An Ultra-Turrax turbine fitted with a T50 engine and an S50 N-G45FF rotor-stator is introduced into the first beaker, which is then rotated at maximum speed, that is to say 10,000 revolutions per minute to homogenize the mixture in seconds. The water from the second beaker is then very quickly introduced into the stirred mixture, and stirring is continued for a further 5 minutes without the temperature of the emulsion thus formed exceeding 50 ° C. The emulsion thus obtained in the laboratory has a storage stability at room temperature between 15 and 25 ° C greater than four months without the appearance of signs of demixing or sedimentation.

EXAMPLE H

The purpose of this example is to describe the optimal conditions for obtaining on an industrial scale an emulsion as stable as in the laboratory according to example I.

Different emulsions have been prepared in an industrial unit as described in the single figure. Their compositions are identical to that described in Example I.

The agitator (2) is a multistage MIXEL type MM agitator equipped with three-bladed mobiles.

Two foam systems (8) were tested: ^* - => a BF 150 finisher, hereinafter called A, sold by Pierre GUERIN TECHNOLOGIES. It is a colloid mill with rotor / stator and variable air gap, = a dynamic homogenizer of MS type sold by Silverson, hereinafter called B, with fixed air gap. In Table I are grouped the characteristics of circulation of the fluids inside the capacity (1) and in the bypass loop (7) returning the emulsion in the capacity (1).

TABLE I

With Qc the circulation flow inside the tank, generally equal

Qc = 1.5Nqp x N x D ³ x 60 Nqp being the number of pumping, N the speed of rotation of the agitator of the tank and D the diameter of this tank.

With V the volume of liquid contained in the homogenization capacity (2) during the manufacture of the emulsion, and Qcirc the flow of liquid circulating outside the capacity (1) downstream of the emulsifier system (8) in the single figure bypass loop.

The meaning of these acronyms is given in "Engineering Techniques", A-5900 and A-5902 in the articles by M.Roustand and J.C Pharamond.

It can be seen from Table I that without stirring in the tank, it is not possible to obtain a stable emulsion. In addition, whatever the foaming system used, what matters is that the Qc / V ratio is greater than 100 and that the time for emulsification or circulation outside the capacity is less than 1.5 hours to improve stability. of emulsion and emulsion productivity in the industrial manufacturing unit.

Claims

CLAIMS:

1 - Process for the preparation, on an industrial scale, of an emulsified fuel water / organic compound (s), of organic external phase, and containing less than 20% by volume of water, and at least one additive necessary to form the emulsion, this process being characterized in that it essentially consists:

Qc / V ≥ 100 h ^"1 preferably Qc / V> 250 h ^{" 1} and more preferably 1000 h ^"1 > Qc / V> 300 h ^'1 , Qc corresponding to the flow rate of circulation of the liquid inside the capacity .

A 3 A to circulate the homogenized liquid by means of the agitator, in the bypass loop opening into the tank, and through at least one foam concentrate system arranged on said loop, at a rate such that the ratio

V / Qcirc corresponds to:

0 h <V / Qcirc <2 h preferably 0 h <V / Qcirc <1,8 h and more preferably 0 h <V / Qcirc <1,5 h. with Qcirc corresponding to the flow rate of the liquid in the bypass loop. A 4 A to supply the bypass loop upstream of the emulsifier system, with the aqueous phase necessary for the formation of the emulsion, A 5 A and finally to maintain the homogenization in the capacity, and the circulation of the liquid in the bypass loop until the desired characteristics of storage stability of the emulsion are obtained. 2 - Process according to claim 1, characterized in that it comprises a step lp prior to step 1, during which the additives are diluted in at least one solvent, in order of decreasing viscosity of the additives, these dilutions being pipes in a capacity equipped with at least one agitator, preferably with an axial pumping rate, and optionally with heating and / or cooling means.

3 - Method according to claim 1 or 2 characterized in that the solvent used in step lp is selected from the group consisting of (s) compound (s) organic (s) used to form the emulsion, a solvent of such as alcohol, ketone, ester or ether, or one of the additives whose solvent properties vis-à-vis the other additives are sufficient.

4 - Process according to any one of claims 1 to 3 characterized in that the organic fuel is chosen from petroleum fuels, gasoline, gas oils, kerosene, household fuels, these products being optionally added with oxygenated compounds of TAME type (methyltertioamylether) or MTBE (methyltertiobutyl ether) for gasolines, of DME (dimethylether), DMM (dimethoxymethane) or TEP (triethoxypropane) type for gas oils, or vegetable or animal oils, refined or not, or their esterified derivatives.

5 - Process according to any one of claims 1 to 4 characterized in that the aqueous phase is injected into the homogenized liquid at a flow rate Qe proportional to the flow rate Qc of liquid circulation, in said capacity, the ratio Qe / Qc varying from 0 to 1.

6 - Method according to claim 5 characterized in that the aqueous phase is injected into the homogenized liquid at a rate Qe such that Qe / Qc varies from 0.05 to 0.20. 7 - Device for implementing the method according to any one of claims 1 to 6, characterized in that it comprises a closed capacity (1) equipped an axial flow agitator (2) comprising three fluid inlet pipes (3), (4), and (5), respectively for organic compounds, additives and emulsion, and an outlet pipe for fluid (6), and possibly a heating and / or cooling system, the conduits (5) and (6) being connected to a circulation conduit (7) defining a bypass loop, comprising an inlet conduit (9) water, an emulsifier system (8) and finally a discharge line (10) of the emulsified fuel, disposed either on the tank (1) or, on the loop (5, 6, 7) upstream or downstream of the foam concentrate system (8).

8 - Device according to claim 7, characterized in that the line (4) allows the injection of the additive mixture, initially prepared and homogenized in a second capacity (11) provided with an axial flow agitator (12) for ensuring the homogenization of said mixture of additives, and comprising inlet (13) and outlet (4) pipes for the mixture, and optionally a heating and / or cooling system for said capacity. 9 - Device according to claims 7 and 8 characterized in that the capacities (1) and (11) are respectively equipped with agitators (2) and (12) producing longitudinal agitation with respect to their axis of rotation generating a rate of defined and modular shear.

10 - Device according to any one of claims 7 to 9 characterized in that the emulsifier system (8) comprises at least one emulsifier pump and / or possibly one or more dynamic mixers equipped with rotor / stator with fixed or variable air gap, and rotating at high speed, preferably greater than or equal to 2000 rpm.

11 - Device according to any one of claims 7 to 10, characterized in that as a replacement, upstream or downstream of the foam concentrate system, are arranged one or more static mixers and / or one or more other foam concentrate (s) ) operating in a mechanical mode (s), using ultrasound and / or microwave.

12 - Device according to any one of claims 7 to 1 1 characterized in that the water injection pipe in the loop (7) is equipped with at least one dispersing system of droplets. 13 - Application of the method according to claims 1 to 6 for the preparation of fuels emulsified water in oil, in particular emulsions water in diesel or water in gasoline for combustion in fixed or transported internal combustion engines.