EP0228311A1 - Lowered viscosity heavy hydrocarbons composition in the form of a multiple emulsion and process for its preparation - Google Patents

Abstract

Composition of heavy hydrocarbons and water, with a viscosity much lower than that of the hydrocarbons contained therein. It is constituted by a multiple emulsion, the internal phase of which is constituted by primary emulsion of water in hydrocarbons, and the external phase, of water containing at least one surfactant, in which this primary emulsion is dispersed, thus forming a secondary emulsion, freestanding, or stabilized by adding stabilizing agents to its external phase.

Description

The present invention relates to a new composition based on heavy hydrocarbons, with a viscosity significantly lower than that of these hydrocarbons themselves. It comprises a process for placing viscous hydrocarbons in the form of such a composition: this process constitutes an industrial means with a view to appreciably lowering the viscosity of various hydrocarbon products or residues, thus making their handling easier and uses.

A particularly advantageous application of the invention relates to heavy residues from the distillation of oils, very viscous, therefore difficult to transport and to use as fuels or even as a coating.

According to the current technique, such viscous products are used in mixtures with lighter hydrocarbons. This is the case of fuels known under the name of heavy fuels, whose viscosity, and also the S content, are lowered to values accepted by the specifications, in particular 40cSt at 100 ° C and 4% sulfur. However, in fact, the consumption of lighter fractions, such as diesel, for diluting excessively viscous residues, is disadvantageous for the petroleum economy, especially when the proportion of diluent reaches approximately 10 to 20%. It was therefore very desirable to find another means of lowering the viscosity of very heavy hydrocarbons. However, the dispersion of water in the hydrocarbon, a well-known practice which improves combustion, is not suitable, because it causes - on the contrary - to increase the viscosity. As for the emulsion of hydrocarbons in water even if this technique allows a significant lowering of viscosity, combustion is more difficult because of the presence of water outside, which must be evaporated.

The present invention provides this technique with a new, highly efficient and extremely economical means which makes it possible to lower the viscosity of heavy hydrocarbons in large proportions, without the addition of other fuels. It also makes it possible to improve the combustion of hydrocarbons and the elimination of the sulfur present; then it makes it possible to considerably improve combustion, by lowering unburnt materials to less than a tenth, compared to the combustion of heavy fuel oil.

The process according to the invention consists in putting the viscous hydrocarbons in the form of a multiple emulsion with water, the latter constituting the minor part of the total weight. Thus, in particular, the composition according to the invention is an emulsion of the W / O / W 'type, that is to say a secondary emulsion, in water (W'), of a first emulsion of the 'water (W) in the hydrocarbon (O).

The application of such a multiple emulsion, according to the invention, to lowering the viscosity results from the unexpected fact that, despite the increase in viscosity as a result of the dispersion of water in the hydrocarbons, W / O, the assembly undergoes a sharp drop in viscosity, when this W / O system is in turn dispersed in an aqueous, external phase, giving W / O / W ', even for relatively small proportions of W'.

As mentioned above, the invention makes it possible to provide, in addition to the fluidification of the product, two other advantages. Thus, the presence of the water particles W in the primary emulsion W / O, results in an improvement of the combustion. On the other hand, reagents capable of reacting Gir with sulfur of the hydrocarbons used, in particular hydroxides or carbonates, alkali or alkaline earth, can bring the sulfur to the state of sulfate, for example CaSO₄, Na₂SO₄, etc.

Since the dispersion of water in hydrocarbon materials is known, the primary W / O emulsion of the compositions according to the invention can be prepared according to the old technique. It requires very good agitation of approximately 3 to 10% of water, and preferably 5 to 6% by weight of the hydrocarbons, so that the water droplets have dimensions of less than 10 microns, with a preferential margin of 0 , 1 to 5 microns, and the best close to 1 µm. As known, such a degree of dispersion can be obtained for example with a centrifugal pump, a colloid mill or with the help of ultrasound.

When the treated hydrocarbon material contains surfactant molecules, which is notably the case for residues from the distillation of oils, the primary W / O emulsion can be prepared without the addition of an emulsifier; in other cases, a small addition, in general of 0.1 to 2%, of surfactant compound should be carried out, according to the usual technique.

Since the invention is generally applied above all to materials which, at ambient temperature, are too viscous to be able to be handled, it is most often necessary to heat them so that it becomes possible to emulsify them with water. Depending on their viscosity, the temperature of this operation varies, in general from 30 ° to 100 ° C and, particularly between 50 ° and 70 ° C for heavy fuels n ° 2 and heavy residues from the distillation of oils. It is possible to exceed 100 ° C, using a pressure emulsification technique, allows both the use of the heaviest residues.

The secondary emulsion W / O / W 'of the previous W / O, in water W', is carried out by stirring the primary emulsion with water (W ') having dissolved an appropriate proportion d surfactant, generally from 0.5 to 5% by weight and most often 1 to 3%. There is a surfactant concentration threshold, below which obtaining the multiple W / O / W 'emulsion is random. With heavy petroleum products, mentioned above, this threshold is around 0.3%: this is the reason why the process of the invention is preferably practiced with contents clearly exceeding this value in secondary water. (W ').

As regards the nature of the surfactant (s), it can be of any known type, anionic, cationic or nonionic. Very good results are obtained with sulfonates, especially lignosulfonates, or those of petroleum, or with fatty amines salified by a mineral or organic acid.

In the external phase of the composition according to the invention, that is to say in the secondary water W ′, the surfactant can optionally be replaced by a very fine powder, suspended in this water, wetted by it . The use of coal dust for this purpose is very interesting, because it increases the calorific value of the whole.

The multiple emulsions produced can be self-supporting due to the judicious use of suitable surfactants. In certain cases, it may be necessary to add, to the external aqueous phase, one or more stabilizing agents, such as for example: xanthan gums, agar-agar, guar, alginates, carrageenans; alkoxy-, carboxy-, hydroxy-alkyl celluloses; polyacrylates, polyacrylamides, and polyacrylate-polyacrylamide; metallic salts, water-soluble, flocculants, such as chlorides, sulfates, nitrates, bicarbonates, sulfites, carboxylates or others of Ca, Mg, Al, Fe. These agents being cited only by way of nonlimiting examples.

For certain stabilizers, it is necessary to also add a biocidal product in the aqueous, external phase, in order to avoid any bacterial or fungal proliferation, during long-term storage, at room temperature, of the multiple emulsion, stabilized.

Whereas the multiple emulsions between water and hydrocarbons, described in the technical literature, generally contain only about 15 to 20% of hydrocarbon for a total of 85 to 80% of water, including 60 to 70% of 'external water (N. GARTI et al. J. Dispersion Sci. and Techn. vol. 4, n ° 3, p.237-252, 1983); S. MATSUMOTO et al. J. Colloid and Int. Sci. flight. 77, n ° 2, p. 555-563, 1980), the present invention provides the advantage of having up to approximately 70 to 80% of hydrocarbon with 20% to 30% of total water, of which 15 to 27% in the external phase. To achieve this result, unforeseen in relation to the prior art, the methods and composition according to the invention must satisfy the conditions indicated above and - in addition - the droplets of the primary emulsion W / O in the secondary emulsion W / O / W 'must be 2 to 50 times larger than the water droplets W in the primary emulsion. Preferably, they are 5 to 10 times, or better 8 to 12 times, larger. In other words, when the internal water droplets (primary emulsion) have dimensions of the order of 1 to 5 microns, the water / hydrocarbon droplets in the secondary water / hydrocarbon / water emulsion must measure for example approximately 10 to 100 microns.

Regarding the temperatures at which is produced the secondary emulsion, they are the same as for the primary emulsion, as described above.

If the preparation conditions according to the invention are respected, the primary emulsion is not broken when it is stirred, with a view to the formation of the secondary emulsion, under strong shears. This drawback, indicated in the prior art (FLORENCE and WHITEHILL, J. Colloid and Int. Sci., Vol. 79, n ° 1, p.243-256, 1981), does not occur with suitable agitations in the process of the invention.

Note that there is interest in shaking the medium well, with a view to the formation of the secondary emulsion, to obtain a heterogeneous particle size which provides better filling of the dispersed system.

To the observations on the nature of the surfactants, given above, the following nonlimiting list of agents readily available on the market can be added.
Non-ionic agents: "TWEEN 80" - polyoxyethylene sorbitan mono-oleate;
"TWEEN 20" - mono-laurate of the same sorbitan;
"SPAN 80" - sorbitan mono-oleate;
"BRIJ 35" - lauryl polyethoxylated alcohol.
Anionic agents: lignosulfonates, in particular of sodium or ammonium, in particular the products of the company AVEBENE designated by codes N7, T5P, NCA or the products of the company BORREGAARD designated under the name of Vanisperse CB or Borresperse CB.
Cationic agents:
"DINORAM S" hydrochloride - N-alkyl propylene diamine hydrochloride (C₁₂-C₁₈ alkyls);
"POLYRAM S" hydrochloride - N-alkyl polypropylene polyamine hydrochloride (C₁₂-C₁₈ alkyls)

Although the relative proportions of the constituents of the composition according to the invention may vary within the limits indicated in the preceding description, the preferable proportions are, by weight: 5 to 6% for internal water, dispersed in the hydrocarbon; 33 to 82% of primary emulsion in the external water phase; surfactants in the external water phase 1 to 2.5% or 0.2 to 0.9% of the total.

The best compositions contain 75 to 80% of primary emulsion and 0.3 to 0.8% of surfactants, the contents of approximately 0.4% being suitable.

Since the pH influences the preparation conditions or the stability of the emulsions, the invention is preferably carried out with a medium of pH limited between 5 and 10; the best results are obtained in the vicinity of 7, in particular between 6 and 8. With too low pH the emulsification is difficult, while for too high pH there is a risk of inversion of the emulsion and the viscosity is not not lowered enough.

The invention is illustrated without limitation by the following examples.

EXAMPLE 1 Preparation of a primary emulsion

2 kg of a heavy fuel oil n ° 2 exRSV, with a density 0.994 at 20 ° C and a viscosity of 425 cP measured at 50 ° C, are placed in a tank in which an emulsifier is immersed. The fuel oil is heated to 55 ° ± 5 ° C until it can be transported by a pump, the suction of which is connected to the bottom of the tank and the discharge to the top of the latter. The temperature is maintained throughout the fuel circulation time.

0.105 kg of water is then added and the fuel is continued to circulate in the round at 55 ° ± 5 ° C for 8 minutes. The primary emulsion, thus formed, contains 4.98% water and the average size of its water droplets is approximately 2 microns, most of them having diameters of 1 to 5 μm.

EXAMPLE 2 Preparation of a secondary emulsion

In a container of 1 liter capacity, fitted with a magnetic stirrer and a heating device with thermostat, 73.5 g of water are introduced, holding 1.5 g in solution, ie 2.04% of agent. surfactant known commercially under the name of "VANISPERSE CB '(Na ligno-sulfonate). This water is stirred at 2815 rpm, while 282 g of l are added slowly over about 10 minutes primary emulsion of Example 1, the whole being maintained at a temperature of 60 ° ± 5 ° C.

Le pH de ce produit est de 6,8.After the introduction of the primary emulsion, in order to improve its stability, the secondary emulsion obtained is passed through a small centrifugal pump delivering 0.6 liters / min. After 10 minutes of this circulation, there is a multiple emulsion having the following characteristics:

The pH of this product is 6.8.

Measured at 50 ° C, the viscosity of the multiple emulsion obtained is 28 cP against 425 cP for the starting fuel, ie only 1 / 15th of it, therefore considerably reduced.

On the other hand, at 25 ° C, the apparent viscosity of the multiple emulsion is 260 cP at 100 s⁻¹, against about 6500 cP for the starting fuel: the drop by emulsification according to the invention has therefore been d '' about 25 times at room temperature.

The droplets of the secondary emulsion, in the multiple emulsion formed, have an average size of approximately 20 microns, or 10 times that of the primary emulsion.

EXAMPLE 3

The operations of Example 2 are repeated in a 14-liter tank, in which 1350 g of water containing 1.12% of the same surfactant are loaded, then 4027 g of primary emulsion according to Example 1.

Stirring is carried out with a variable speed between 0 and 2500 revolutions instead of 2815 rpm in Example 2.

It then takes about 25 minutes to obtain the multiple emulsion. This had an apparent viscosity of 325 cP at 25 ° C for 50 s⁻¹, which is 20 times less than that of the treated heavy fuel.

EXAMPLE 4 Preparation of a secondary emulsion from a heavy residue

The operations are similar to those of Example 2, but the primary emulsion used comes from a heavy residue from the distillation of crude oil, of the DJENO type. This first emulsion, prepared at 75 ± 5 ° C, comprises 95% of this heavy residue and 5% water in droplets of 1 to 6 microns; it has a viscosity of 4015 cP at 50 ° C. In a tank, fitted with a magnetic stirrer as an emul 64.7 g of water mixed with 1.3 g, or 2%, of the same VANISPERSE CB surfactant as in the previous examples; the temperature being adjusted to 75 ° ± 5 ° C, the agitator is continuously rotated at 2800 rpm and, then, 211 g of primary emulsion are introduced slowly, over 10 minutes.

Unlike Example 2, the stability of the secondary emulsion obtained is not increased by passing through a small centrifugal pump.

Le pH de ce produit est de 7,4.The emulsion has the following overall composition:

The pH of this product is 7.4.

Its apparent viscosity at 50 ° C is 200 cP against 3500 cP for the heavy starting residue: it has therefore been reduced 17.5 times, thus making the residue easily usable, especially for combustion in conventional burners.

EXAMPLE 5

The operations of Example 4 are repeated, but at the end of the 10 minutes of stirring in the tank, the secondary emulsion obtained is passed through a small centrifugal pump delivering 0.45 kg / min; this pumping lasts 8 minutes and results in an improvement in the stability of the multiple emulsion.

EXAMPLE 6

In the procedure of Example 2, the anionic surfactant, based on lignosulfonate, was replaced by a non-ionic agent, known commercially under the name TWEEN 20 (polyoxyethylene sorbitan mono-oleate).

The same results are obtained, but the mixture had to be stirred for 15 minutes, instead of 10 minutes in the case of Example 2.

EXAMPLE 7

The operations of Examples 4 and 5 are repeated with DINORAM S hydrochloride (N-alkyl propylene diamine hydrochloride with C₁₂ to C₁₈ alkyls) in place of VANISPERSE CB (ligno-sulfonate). Things work the same way, but we have to operate the magnetic stirrer for 17 minutes instead of 10, to obtain a multiple, equivalent emulsion.

EXAMPLE 8

The operations of Example 4 are repeated, but 7.10 g of a 2% aqueous solution of RHODOPOL 23 (500 ppm of RHODOPOL 23 relative to all of the multiple emulsion), xanthan gum, sold by the company RHONE-POULENC. The operation then continues as indicated in Example 4. The multiple emulsion obtained did not show any sign of instability over a period of three months.

EXAMPLE 9

The operations of Example 4 are repeated, but 7.10 g of a 2% aqueous solution of RHODOPOL 23, also containing 0.142 g, are added to the multiple emulsion obtained, with moderate stirring (stirring with magnetic bar). pure formalin (0.384 g of 37% aqueous formalin solution) (500 ppm of RHODOPOL 23 and 500 ppm of formaldehyde relative to the whole of the multiple emulsion). The emul Multiple results obtained showed no signs of bacterial or fungal instability, evolution or proliferation for three months at room temperature.

EXAMPLE 10

400 kg of multiple emulsion were manufactured in a pilot installation with a colloid mill and the equipment necessary for dosing and incorporating the constituents of the mixture. The characteristics of the installation are: maximum total flow of the installation 300 l / h; water supply by piston dosing pump (90 l / h max); additive supply by piston dosing pump (15 to 16 l / h max); supply of hydrocarbons by centrifugal group (300 l / h max).

The multiple emulsion was produced in two stages.

The 50 liter feed tank was filled with heavy fuel oil with a viscosity of 425 cP at 50 ° C. Heated to 50 ° C, this fuel was introduced into the colloid mill at a flow rate of 140 l / h. Water was added at a flow rate of 8 l / h creating a primary water-in-oil (W / O) emulsion at 5.4% water.

The adjustment of the colloid mill was carried out so as to have the minimum clearance between rotor and stator, namely 0.2 mm. The 300 kg of primary emulsion thus produced was stored in barrels; the colloid mill was then adjusted to have a gap of 0.5 mm between rotor and stator, during the formation of a second emulsion, in order to obtain a fineness different from that of the first.

The additive, DINORAM S hydrochloride (cationic, n-alkyl propylene diamine hydrochloride with C₁₂ to C₁₈ alkyls), was prepared in solution in water at a concentration of 5%.

The additive supply was carried out at a rate of 15 l / h, that of water at a flow rate of 30 l / h, while the emulsion flow rate was 105 l / h.

This resulted in a multiple emulsion of the following composition:
fuel RSV 66.22%
water 33.28%
surfactant 0.5%
The viscosity of this emulsion was:
87 cP at 23 ° C
35 cP at 40 ° C
25 cP at 60 ° C
against 425 cP at 50 ° C for the starting fuel.

The particle size of the primary emulsion was around that of Example 1. The second emulsion had the following particle size distribution:
77.8% <80 µm, average diameter 32.5 microns with 20% of particles <14.5 microns and 5.3% of particles <2 microns.

EXAMPLE 11

400 kg of the multiple emulsion, prepared according to Example 10, were burned in a Guillot Totaltub boiler of 1500 th / h, equipped with a Cuenod PCS 300 burner with mechanical spraying by Monarch nozzle.

The multiple emulsion was stored in a separate tank. The burner was first lit with domestic fuel; the emulsion supply was carried out gradually, the ignition then proceeded without difficulty. The flame appeared visually more radiant. It was possible to burn the product with a preheating temperature below 90 ° C. The most striking result was the very low level of unburnt compared to the combus classic heavy fuel oil. Thus we found only 50 mg / th, while unburnt exceeded 500 mg / th, in the same installation, when heavy fuel oil was burned which requires preheating from 140 ° to 150 ° C. The multiple emulsion according to the invention therefore makes it possible to have less than one tenth of the unburnt products emitted in the combustion of heavy fuel oil.

Claims (16)

1. Composition comprising heavy hydrocarbons and water, with a viscosity much lower than that of these hydrocarbons, characterized in that it is constituted by a multiple emulsion the internal phase of which is constituted by a primary emulsion of water in hydrocarbons, and the external phase, with water containing at least one surfactant, in which this primary emulsion is dispersed, thus forming a secondary emulsion. 2. Composition according to Claim 1, characterized in that the primary emulsion forms 33 to 82% by weight of the total and that it contains 3 to 10%, and preferably 5 to 6% of water relative to the weight of the hydrocarbons. 3. Composition according to claim 1 or 2, characterized in that it contains approximately 70 to 80% by weight of hydrocarbons. 4. Composition according to one of claims 1 to 3, characterized in that its water content forming the external phase is about 20 to 30% by weight. 5. Composition according to one of the preceding claims, characterized in that the water of the external phase has a pH of 5 to 10, and preferably of 6 to 8. 6. Composition according to one of the preceding claims, characterized in that the water droplets in the primary emulsion have dimensions less than 10 microns, preferably from 0.1 to 5 microns. 7. Composition according to one of the preceding claims, characterized in that the droplets of the secondary emulsion have dimensions 5 to 20 times greater than those of the water droplets in the primary emulsion, and measure in particular 10 to 100 microns. 8. Composition according to one of the preceding claims, characterized in that it contains 0.3 to 0.8% of at least one surfactant. 9. Composition according to one of the preceding claims, characterized in that it contains at least one stabilizing product. 10. Composition according to one of the preceding claims, characterized in that it contains at least one biocidal product. 11. Composition according to one of the preceding claims, characterized in that it has at 25 ° C a viscosity of the order of 1 / 25th of that of the hydrocarbons it contains. 12. Composition according to one of the preceding claims, characterized in that its external aqueous phase holds in solution a basic, alkaline or alkaline-earth compound, or / and in suspension a fine powder, in particular carbon powder. 13. Process for putting heavy hydrocarbons in a form with a viscosity considerably reduced by their dispersion in water, characterized in that a primary emulsion of 3 to 10%, and preferably 5 to 6, is first prepared % water in hydrocarbons, and this primary emulsion is dispersed, at a rate of 33 to 82%, in water containing sufficient surfactant to form a secondary emulsion. 14. Method according to claim 13, characterized in that that the stirring, with a view to the formation of emulsions, is such that the size of the water droplets in the primary emulsion is approximately 0.1 to 5 microns, and that the dimensions of the droplets of the latter, in outside water, that is 10 to 100 times larger. 15. Method according to one of claims 13 and 14, characterized in that it is applied to hydrocarbons from the distillation of petroleum, in particular to heavy fuels and heavy residues. 16. The method of claim 13, applied to the combustion of heavy fuels and heavy residues from the distillation of petroleum.