TWI426934B - Assembly for diffusing a composition in air - Google Patents

Description

An assembly for spreading the composition to the air

The present invention relates to a field in which a composition to be dispersed, such as a perfume composition, is dispersed in the air.

More precisely, the invention relates to an assembly suitable for dispersing a composition to be dispersed in ambient air. The assembly includes a central portion for containing a mixture of a flammable liquid and a composition to be dispersed. It further comprises a region for evaporating the flammable liquid and the composition to be dispersed, the evaporation region being adapted to be supplied through the middle portion with a mixture of the flammable liquid and the composition to be dispersed, the evaporation region comprising at least An outer wall in contact with ambient air, at least one of the outer walls forming an area for spreading the composition to the air. The assembly also includes a combustible combustion zone comprising a catalyst and having at least one outer wall in contact with ambient air, the evaporation zone being intended to be heated by the burner zone.

Background of the invention

Catalytic burners as described in the patent applications or patents disclosed in the publications of WO 2008/023112, WO 2008/023113, EP 1491819, EP 1491818, WO 99/63267, and EP 0 277 875 are specifically known.

These burners have been found to be defective.

In particular, the use of such burners in the prior art would encounter ignition difficulties. Ignition means that catalytic combustion begins with a heat source that is a flame in this case.

On the one hand, such conventional burners require a large flame for ignition, which is unsatisfactory in terms of user safety. This is because, depending on the saturation of the burner containing the fuel, the burner requires a flame size of between 10 and 15 cm depending on the degree of filling of the vessel containing the burner and containing the flammable liquid.

On the other hand, it has been found that depending on the size of the container containing the burner, it may be full of fuel, thereby preventing the next ignition, or at least making the next ignition difficult. This is because the saturation of the burner at a time t depends on the form of the container, which can sometimes cause a re-ignition failure of the burner.

In addition, current burners have a disadvantage in that they require ignition time, so it takes time to maintain the flame between 1 and 2 minutes, which is too long for the user.

There is therefore a need for a burner apparatus that overcomes the above limitations and that is particularly improved, safer and more efficient ignition conditions.

In this context, the object of the invention is to propose a device for solving this need.

The subject matter of the present invention is therefore an assembly suitable for dispersing a composition to be dispersed in the air, the assembly comprising:

a central portion for containing a mixture of a flammable liquid and a composition to be dispersed;

a region for evaporating the flammable liquid and the composition to be dispersed, the evaporation zone being adapted to be supplied through the middle portion with a mixture of the flammable liquid and the composition to be dispersed, the evaporation zone comprising at least An outer wall in contact with ambient air, at least one of the outer walls forming an area for dispersing the composition in the air, and

a combustible combustion zone comprising a catalyst and having at least one outer wall in contact with ambient air, the evaporation intended to be heated by the burner zone, and

An internal separating element that conducts heat and does not penetrate any liquid, the element forming a space between the burner zone and the evaporation zone, the evaporation zone being adapted to release flammable liquid vapor to the surrounding air at its outer wall, and The burner zone is adapted to receive such steam on its outer wall and to combust the steam by catalytic combustion, the assembly being characterized by at least the central portion and the evaporation zone, and optionally the burner zone being Made of a porous material having a porosity of at least 35%.

The use of steam combustion principles eliminates problems with the form and volume of the container and thus eliminates the fuel output and supply problems of the assembly.

This is because when one of the prior art burners is full of fuel, for example because it has not been used for a certain amount of time, it cannot be re-ignited because it is submerged, and the flame temperature is not enough to dry it, so it is not enough to start. Catalysis. In the case of using the assembly using steam combustion according to the present invention, the catalytic or burner zone is never filled with flammable liquid, even if it is not used for a certain amount of time, regardless of the time, which allows ignition every time. The excitation is not stopped.

In addition, the assembly according to the present invention has the advantage of requiring a shorter flame time than prior art burners, since the catalytic action begins to play. In the present invention, the flame must be for a period of 5 to 20 seconds, whereas in the prior art, the period is between 1 and 2 minutes. The necessary flame size for assembly ignition in accordance with the present invention is also reduced as compared to prior art devices. The flame is between 2 and 5 cm. In addition, it may be predetermined depending on the height of the evaporation zone.

At least the middle portion of the assembly and the evaporation zone must be porous in accordance with the present invention. This is because, in order to distribute the perfume, it is absolutely necessary that the support of the assembly (i.e., the middle portion and the evaporation zone) can allow the liquid perfume to pass through, which necessarily includes a porous support.

The porosity must necessarily be at least 35%, otherwise, in the case of steam combustion, it will be observed in the evaporation zone that the assembly according to the invention is difficult to function. In particular, it has been found that when the porosity of evaporation is low, particularly below 35%, steam is difficult to supply to the burner zone, the consequences of which are as follows:

- The catalytic action cannot be started or stopped quickly because the amount of steam from the combustible gas is insufficient.

- the evaporation zone is fouled due to insufficient evaporation of the perfume and still bound in the structure, and

- Perfume has insufficient evaporation in the evaporation zone and limited olfactory quality.

However, the porosity of the central and/or evaporation zone must be maintained below 80%. This is because, if the porosity is above 80%, a system failure is also observed, which can be manifested, for example, as the supply of flammable liquid is excessive, so that the liquid is consumed excessively. The consequence is a high degree of evaporation which leads to an endothermic phenomenon. The liquid itself cools the evaporation zone due to its presence. The evaporation zone temperature is too low and the perfume evaporation is difficult.

The role of the separation element is twofold:

- First, it effectively conducts heat,

- Secondly, it must provide the total impermeability of the liquid between the evaporation zone and the burner zone: the burner zone cannot be in contact with the flammable liquid, otherwise it will be difficult to ignite in the catalytic zone activated by steam. This is because, when the supply is too large, the flammable liquid fills the burner zone and thus extinguishes it.

Thus, it comprises a liquid impermeable material, and preferably a non-porous material, i.e., does not penetrate any fluid.

Non-porous materials can be selected from glass, tantalum or a metal or plastic material.

For example, the inner separating element is made of metal, and more specifically aluminum (which has a thermal conductivity of 237 w ‧ k ^-1 ‧ k ^-1 at a temperature of 20 ° C). This is because aluminum has the advantage of being sufficiently conductive and thus capable of heating the spread zone, which allows the perfume to fully evaporate and prevent fouling. However, aluminum is not an excessively conductive material, and excessively conductive materials have the risk of transferring too much heat to the distribution zone and weakening the dispersion of the perfume. The aluminum separating element may specifically have a thickness of less than 1 mm, preferably between 0.2 and 1 mm, and particularly preferably equal to 0.4 mm.

The separation element may additionally comprise a portion of the pore material, such as present in the polyoxane, which is permeable to gases but impermeable to liquids.

Advantageously, the middle and evaporation zones, and optionally the burner zone, consist of a porous material having a porosity of from 35% to 80%, or even from 40% to 70%, and preferably from 50% to 60%. production.

The porous material comprises at least one of a material selected from the group consisting of kaolin, cordierite, and a refractory compound, a uniform pore former, a binder, and optionally a mixture of thermally conductive compounds having a thermal conductivity greater than 60 watts per meter-gram. By.

Preferably, a refractory compound, a uniform pore former, a binder, and optionally a mixture of thermally conductive compounds having a thermal conductivity greater than 60 watts per meter-gram is used.

A composition for obtaining a porous material for producing a catalytic combustion burner or a catalytic combustion burner element, comprising at least one refractory compound, at least one binder, at least a uniform pore agent, and at least one thermal conductivity A thermally conductive compound of greater than 60 watts per meter-gram, which is described in the published International Patent Application No. WO 2008/023111.

This composition has an easy to control property and a quality, and thus can be used in any form of burner. Thus, the burners or the burner elements made from the composition have physical, chemical and mechanical properties that are homogeneous over their entire volume, as well as from one burner, or burner element, to the other. nature.

At least one of the thermally conductive compounds is, for example, tantalum carbide.

Preferably, the thermal conductivity of each refractory compound is less than the thermal conductivity of each thermally conductive compound. Each refractory compound may be selected in particular from one of alumina, yttria, mullite, zirconia, cordierite, syenite or a mixture thereof. The refractory compound is preferably mullite.

Advantageously, each binder is selected from any inorganic compound that can be sintered at a temperature of less than or equal to 1000 degrees Celsius. The binder is, for example, glass, preferably borosilicate glass.

Each uniform porogen is advantageously selected from any of the porogens that are controlled and controlled by granulometry. The porogen is, for example, graphite.

According to a particular aspect of the invention, the compound comprises from 1% to 30% by weight of at least one thermally conductive compound, from 30% to 70% of at least one refractory compound, from 2% to 30% by weight of the total weight. A binder, and 5% to 40% of at least a consistent pore.

According to a more specific aspect of the invention, the composition comprises from 5% to 25% of at least one thermally conductive compound, from 40% to 65% of at least one refractory compound, from 5% to 25% by weight of the total weight. At least one binder, and at least 8% to 35% of the uniform pores.

The burner zone can be made of a porous material as described above or a non-porous material. This porous or non-porous material must be thermally conductive and is, for example, a ceramic or a metal.

In accordance with the present invention, the assembly can include three detachable workpieces, a first workpiece including an evaporation zone and a middle portion, a second workpiece including a burner zone, and a third workpiece including internal separation elements.

Another embodiment of the invention consists of the addition of a single piece of internal separation element comprising an evaporation zone, a middle zone and a burner zone. The inner separating element can thus be placed within this single piece to form an interval between the burner zones of the evaporation zone.

In accordance with one aspect of the invention, the combustor zone occupies a top peripheral portion of the assembly in accordance with the present invention, and the dispersing zone occupies one of the top center portions of the assembly, which is separated from the combustor zone by internal separation elements. In other words, the spreading zone is placed at the top of the assembly and is surrounded by the burner zone and heated by the separating element.

In accordance with a preferred embodiment of the present invention, the central portion includes a substantially axial chamber at one of the bottom ends of the assembly, the chamber being adapted to receive a core and containing a mixture of flammable liquid and composition, the composition The core soaked in the mixture is dispersed by contact.

The core is advantageously made of a porous material. However, any material that enables the central portion to be supplied with liquid fuel by capillary action can constitute a core useful in the present invention. Thus the core is any conventional core, such as a cotton core. It may additionally be a core made of mineral material, such as a core made of mineral fibers or ceramics.

The assembly according to the invention may include a passage between the top of the chamber and the surrounding air at its top end. This passage specifically allows the unburned gas in the evaporation zone to be properly vented, and thus its fouling is reduced.

The chamber may have a diameter of 5 to 6 mm, preferably 5.5 mm, a distance of up to 2 mm from the top end of the evaporation zone. The passage may have a diameter of 1.5 to 3 mm, preferably 2 mm.

For example, the first workpiece shape may be cylindrical, with a cylindrical chamber at the bottom end of the first workpiece at its center. The first workpiece can include a support device for receiving and supporting the second and third workpieces. A support device can be formed by an L-shaped edge around the first workpiece. The third workpiece can have a shape adapted to be placed around the first workpiece at its top. The second workpiece may have a shape adapted to be placed on top of the first workpiece about the first workpiece such that the third workpiece forms an internal separation element between the first workpiece and the second workpiece. The second workpiece and the third workpiece are, for example, in the form of a ring having at least one L-shaped edge. The third workpiece may have a frustoconical outer periphery that promotes catalytic combustion of the vapor contained in its outer wall.

Preferably, the catalyst is deposited at least on an outer peripheral portion of the burner zone. Thus, for example, the catalyst is deposited on the outside and around the second workpiece at the frustoconical edge. The catalyst can also be deposited on top of one of the burner zones, which enables the evaporation zone to be better heated and thus limits the accumulation of unburned residues.

The catalyst is preferably a metal and may be selected in particular from aluminum, palladium and rhodium. Platinum is preferably used.

The amount of deposited platinum in the range of 0.5 mg to 3 mg is sufficient to ensure that the assembly according to the present invention functions. However, a larger amount, advantageously from 30 mg to 200 mg, and preferably from 50 mg to 160 mg, prevents fouling of the evaporation zone.

According to the invention, the composition to be dispersed in the surrounding air may in particular be a perfume composition. It may additionally be a mosquito repellent composition, an anti-caries composition or an antibacterial composition.

The flammable liquid used in accordance with the present invention may be monoethanol, such as isopropanol, or any other suitable liquid fuel that meets current regulations. Its evaporation and catalytic combustion must not emit a bad odor that is unfavorable to the perfume.

For example, the assembly according to the invention is adapted to function as a mixture of a flammable liquid and a composition to be dispersed, the composition comprising isopropanol, optionally acetone, optionally water, and perfume. More specifically, this mixture may comprise 70% to 99% isopropanol, 0% to 18 acetone, 0% to 10% water, and up to 2% perfume by mass. The percentage is provided for the total mass of the mixture.

The assembly according to the invention is suitable for functioning as isopropanol which is normally used as a flammable liquid, and also as a compound which is more volatile than isopropanol, such as acetone. However, currently known burners cannot use this flammable liquid because the burners are not wicked by the liquid. This is because the catalytic reaction that usually occurs can not be excited due to too much input of this flammable liquid.

The vapor tension (24.7 kPa) of acetone at ambient temperature of 20 ° C is greater than that of isopropanol (4.4 kPa). Thus acetone evaporates faster than isopropanol. Evaporation of acetone is endothermic. It carries away heat in the burner, which has the effect of cooling and promoting the cessation of catalytic excitation. The consumption per hour of acetone (greater than 30 g/h) is much higher than that of isopropyl alcohol (about 20-25 g/h). The viscosity of acetone (0.32 mPaS at 20 ° C) is lower than isopropanol (2.37 mPaS at 20 ° C). For these reasons, a monoacetone based mixture cannot be used in conventional burners. The assembly according to the present invention can function as a mixture of this type by solving the problem of excessive supply of flammable liquid and excessive evaporation of flammable liquid.

According to a particularly advantageous embodiment, the assembly according to the invention also comprises a second catalyst, referred to as a liquid combustion catalyst, which is placed in a region around the evaporation zone 3 and in the middle portion, and more precisely, In a so-called liquid combustion zone (on top of the zone containing the second catalyst).

Therefore, in the case of using this second catalyst, the combustion of the assembly according to the present invention is a mixture of the following:

- a steam burning zone in the burner zone, and

- a liquid combustion zone in the dispersion zone of the evaporation zone.

The liquid combustion catalyst is preferably a metal and may be selected in particular from platinum, palladium and rhodium.

Preferably, from 30 mg to 200 mg, more preferably from 50 to 160 mg, of platinum is used to limit or even prevent buildup fouling.

Simple illustration

Other features and advantages of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings A perspective view of a first embodiment; - Figure 1B shows a cross-sectional view of the assembly of Figure 1A; - Figure 2A shows a perspective view of the first workpiece of the assembly of Figure 1A; - 2B Figure 2 is a cross-sectional view of the first workpiece of Figure 2A; - Figure 3 is a perspective view of the second workpiece of the assembly of Figure 1A; - Figure 4 is a third workpiece of the assembly of Figure 1A BRIEF DESCRIPTION OF THE DRAWINGS - Figure 5 is a cross-sectional view of a flask equipped with an assembly according to the present invention; - Figure 6 is shown in Figure 1A after being used under extreme conditions leading to complete emptying of the assembly. a black-and-white photograph of the assembly according to the present invention; - Figure 7 is an infrared thermographic image of the assembly shown in Figure 6 after 20 minutes of action; - Figure 8 is an extreme condition that results in complete emptying of the assembly. After use, a black-and-white photograph according to a second embodiment of one of the assemblies of the present invention; - Figure 9 is a total of Figure 6 Infrared thermography in FIG effect after 20 minutes.

The same elements shown in Figures 1 through 5 are denoted by the same reference numerals.

The basis shown in Figures 1A and 1B The assembly 1 of the present invention comprises a central portion 2, an evaporation zone 3 for evaporating the combustible liquid and the composition to be dispersed, a combustor zone 5 for catalytic combustion, and an internal separation element 7.

The burner zone 5 occupies a top peripheral portion of the assembly 1 and has at least one outer wall 6 in contact with ambient air.

The evaporation zone 3 comprises a distribution zone 4 in which the composition to be dispersed, for example perfume, is dispersed in the surrounding air after evaporation.

The flammable liquid vapor is liberated in a zone 17 around the bottom and bottom or middle of the evaporation zone 3, i.e., below the burner zone 5 where the steam is combusted and its outer wall 6.

The middle portion 2 includes a chamber 9 adapted to receive a core (not shown).

The assembly 1 contains a passage 10 between the top of one of the chambers 9 and the surrounding air at a top end.

Assembly 1 can include three detachable workpieces, which are shown in Figures 2A, 2B, 3, and 4, respectively.

A first workpiece 8 includes an evaporation zone 3 and a middle section 2. This first workpiece 8 also includes a barrel 11. The cartridge 11 is intended to receive and clamp the core and is also intended to be contained in a container containing a mixture of a flammable liquid and a perfume composition, the core being immersed in the mixture. More precisely, the cartridge 11 can be mounted to an outlet of a container, for example in the form of a flask.

In the drawings, the barrel 11 forms an integral part of the first workpiece 8. However, in accordance with the present invention, the cartridge can be another workpiece that can be detached from the first workpiece. In this case, the combination of the barrel and the first workpiece must enable a mixture of flammable liquid and perfume composition to circulate between the two workpieces.

In FIGS. 2A and 2B, the first workpiece 8 includes an L-shaped edge 12 for receiving a third workpiece shown in the fourth figure, and the third workpiece includes an internal separation member 7. The middle portion 2 and the evaporation zone 3 are made of a porous material having a porosity of at least 35%.

As shown in FIG. 3, a second workpiece includes a burner zone 5.

The inner separating element 7 is in the form of an L-ring for first being placed on the L-shaped edge 12 of the first workpiece 8, and secondly accommodating the second workpiece, as shown in Fig. 1B, the inner peripheral wall of the second workpiece also has a L-shaped edge 12.

For example, the height of the assembly 1 is 16.5 mm, including the height of the drum 11, the height of the burner zone 5 is 3 to 3.5 mm, and the height of the combustible vapor emission zone 17 is 6 to 10 mm. In particular, for propanol, the height of zone 17 is approximately 7 mm, and for isopropanol is approximately 9 mm.

However, such heights may be any height that enables the device according to the invention to function. A level sufficient to allow the catalysis to occur and maintain, and sufficient heat to release the zone to be conducted to the evaporator zone as far as the evaporation zone is necessary. This burner zone height determines the size of the flame, which increases with the height of the burner zone. In addition, the height of the combustible vapor emission zone 17 must be sufficient to provide sufficient evaporation and to enable the catalytic portion to function. The initiation of the catalysis can be carried out by the top of the assembly and/or by the portion below the burner zone, zone 17. It is best to implement this part below the burner zone as it is supplied with more fuel.

A ratio of the height between the burner and the evaporation zone to be compliant can be provided to properly ignite and limit the flame height. For example, for the use of acetone as a fuel, the ratio of the height of the burner zone to the height of the evaporation zone is approximately 1:2; for the use of isopropanol as a fuel, this ratio is approximately 1:3.

Figure 5 depicts a catalytic combustion flask 13 adapted to contain a mixture 14 of a flammable liquid and a composition to be dispersed. This flask 13 is also adapted to contain on its top a assembly according to the invention which accommodates a core 15 soaked in the mixture 14.

The flask 13 can be any container capable of accommodating the shape of an assembly having a core according to one of the present invention, the core being immersed in a mixture contained in the container. The flask 13 has a first-rate outlet 16 to which the assembly 1 is fixed.

Figures 6 and 8 illustrate the effect of a second so-called liquid combustion catalyst placed in the region 17 around and in the middle of the evaporation zone 3, and more precisely in a so-called liquid combustion zone 18, liquid combustion Zone 18 is at the top of zone 17. To this end, the following comparative tests were carried out: 1. Combustion was carried out until the assembly according to the invention shown in Figure 1A was completely empty, the assembly containing only one catalyst in the burner zone 5: - at the end of this combustion, Photographing one of the assemblies (Fig. 6), and - generating an infrared thermography after 20 minutes of action (Fig. 7); 2. Combustion is also performed until one of the assemblies according to one of the inventions is second The embodiment is emptied, the assembly comprising the same flammable liquid as the assembly of Figure 6 and a mixture of the composition to be dispersed, the second embodiment of the assembly according to the invention also comprising a second so-called liquid combustion catalyst Placed in zone 17: - at the end of this combustion, photographs one of the photographs of the assembly (Fig. 8), and - after 20 minutes of action, an infrared thermographic image is produced (Fig. 9); in Fig. 7 and ninth In the thermographic image of the figure, the temperature is indicated at ±20 °C.

"Combustion until completely empty" means within the meaning of the invention that combustion is allowed to continue until the mixture of flammable liquid and the composition to be dispersed completely disappears.

After complete combustion, the hybrid combustion assembly as shown in Fig. 8 has a central dispersion zone (4) that maintains cleanliness from ignition to light. The highest part is the steam combustion zone (6) with the catalytic ring (5). The gray zone just below the steam combustion ring (6) corresponds to the (liquid) combustion zone (18), and the zone below the liquid combustion zone (18) corresponds to the vapor emission zone (17).

Figure 9 shows that the assembly 1 is completely dirty after being completely emptied, at the central dispersion zone (4) and below the steam combustion ring (6), as shown in Figure 8.

In Fig. 8, it can be seen that the liquid combustion zone 18 is at a temperature of 412 ° C, which is higher than the temperature of zone 18 in Fig. 6 of only 150 ° C. In addition, the temperature in the steam combustion zone 6 is increased overall: this is 537 ° C in Figure 9 and only 489 ° C in Figure 7. This means that zones 17 and 18 of the assembly of Figure 8 are hotter than the assembly of Figure 6, with greater heat dissipation in the evaporation zone. In addition, the zone 6 of the assembly of Fig. 8 is also hotter than that of Fig. 6, with better heat conduction by the separating element 7.

In summary, the presence of liquid catalysis in zone 18 causes a modification in the distribution of the map of the burner and thus causes it to be free of fouling.

1. . . Assembly

2. . . Central

3. . . Evaporation zone

4. . . Dispersion area

5. . . Burner zone

6. . . Outer wall

7. . . Internal separation element

8. . . First workpiece

9. . . Chamber

10. . . aisle

11. . . cylinder

12. . . L-shaped edge

13. . . Flask

14. . . mixture

15. . . core

16. . . Outflow

17. . . Combustible vapor emission area

18. . . Liquid burning zone

1A is a schematic perspective view showing a first embodiment of an assembly according to the present invention;

Figure 1B is a cross-sectional view showing the assembly of Figure 1A;

2A is a schematic perspective view showing the first workpiece of the assembly of FIG. 1A;

2B is a cross-sectional view showing the first workpiece of FIG. 2A;

Figure 3 is a perspective view showing the second workpiece of the assembly of Figure 1A;

Figure 4 is a perspective view showing the third workpiece of the assembly of Figure 1A;

Figure 5 is a cross-sectional view of a flask equipped with an assembly according to the present invention;

Figure 6 is a black and white photograph of the assembly according to the invention shown in Figure 1A after being used under extreme conditions leading to complete emptying of the assembly;

Figure 7 is an infrared thermographic image of the assembly shown in Figure 6 after 20 minutes of action;

Figure 8 is a black and white photograph of a second embodiment of one of the assemblies according to the present invention after use under extreme conditions resulting in complete emptying of the assembly;

Figure 9 is an infrared thermographic image of the assembly shown in Figure 6 after 20 minutes of action.

1. . . Assembly

2. . . Central

3. . . Evaporation zone

4. . . Dispersion area

5. . . Burner zone

6. . . Outer wall

7. . . Internal separation element

8. . . First workpiece

9. . . Chamber

10. . . aisle

11. . . cylinder

12. . . L-shaped edge

17. . . Combustible vapor emission area

Claims (11)

An assembly adapted to disperse a composition to be dispersed in ambient air, the assembly comprising: - a central portion for containing a mixture of a flammable liquid and the composition to be dispersed, - an evaporation a region for evaporating the flammable liquid and the composition to be dispersed, the evaporation zone being adapted to be supplied through the middle portion with a mixture of the flammable liquid and the composition to be dispersed, the evaporation zone comprising at least one An outer wall in contact with ambient air, at least one of the outer walls forming a region for dispersing the composition in the air, and a combustor region for catalytic combustion comprising a catalyst and having at least one outer wall and the periphery Air contact, the evaporation is intended to be heated by the burner zone, and - an internal separation element that conducts heat and does not penetrate any liquid, the element forming a space between the burner zone and the evaporation zone, The evaporation zone is adapted to release combustible liquid vapor into the ambient air at its outer wall, and the burner zone is adapted to receive such steam at its outer wall and to combust the steam by catalytic combustion, the assembly Characterized in that at least the central portion and the evaporation zone are made of a porous material having a porosity of at least 35%. The assembly of claim 1, wherein the porous material constituting the middle portion and the evaporation region has a porosity of from 35% to 80%. The assembly of claim 1, wherein the assembly is characterized by The separation element comprises a non-porous material selected from the group consisting of glass, tantalum or a metal or plastic material. The assembly of claim 3, wherein the internal separation is made of aluminum. The assembly of claim 1, characterized in that it comprises three detachable workpieces, a first workpiece comprising the evaporation zone and the middle portion, a second workpiece comprising the burner zone, and a first The three workpieces include the internal separation element. The assembly of claim 1, wherein the burner zone occupies a top peripheral part of the assembly. The assembly of claim 6 wherein the scatter zone occupies a top intermediate portion of the assembly and is separated from the burner zone by the internal separation element. The assembly of claim 1, wherein the central portion comprises a substantially axial chamber at one of the bottom ends of the assembly, the chamber being adapted to receive a core and containing the A flammable liquid and a mixture of the composition to be dispersed by contacting the core soaked in the mixture. The assembly of claim 8 wherein the top end comprises a passage between the top of one of the chambers and the ambient air. The assembly of claim 1, wherein the catalyst is placed in an outer peripheral portion of the burner zone. The assembly of claim 1, further comprising a second catalyst disposed in a zone at a periphery and a middle of the evaporation zone.