WO2003006879A1

WO2003006879A1 - Spray device and use method

Info

Publication number: WO2003006879A1
Application number: PCT/FR2002/002224
Authority: WO
Inventors: Olivier Delabroy; Pierre Bodelin; Patrick Recourt; Jacques Mulon; François Lacas
Original assignee: L'air Liquide, Societe Anonyme A Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation Des Procedes
Priority date: 2001-07-10
Filing date: 2002-06-27
Publication date: 2003-01-23
Also published as: FR2827198A1; FR2827198B1; JP2004534196A; JP4382477B2

Abstract

The invention concerns a spray device for spraying a liquid with a spraying fluid, comprising: a conduit (32) for injecting a liquid to be sprayed; a spraying zone or conduit (46), at least a conduit for injecting (34, 36) a spraying fluid; at least two conduits (40, 60) for circulating the spraying fluid starting from said injection conduit and reaching the spraying zone or conduit (46), the spraying fluid being divided into several parts between the circulation conduits.

Description

Spraying device and implementation method

Technical field and prior art

The invention relates to the field of liquid spraying, assisted with the aid of a spraying fluid or gas, in particular oxygen.

It also relates to the field of assisted combustion by spraying.

It also relates to a sprayer and a spraying method, as well as a spraying line using a sprayer according to the invention.

The fluids traditionally used as spraying fluid for combustion are water vapor or air. The drawback of water vapor is that it injects a non-reactive gas into the heart of the flame, which will pump energy from the flame and possibly harm the stabilization of said flame. The nitrogen contained in the air is a source of pollutants produced during combustion and in particular of nitrogen oxide (NOx). Pure oxygen is therefore used more and more as a spraying fluid to overcome on the one hand pollution, in the case of the use of air, or modifications of the characteristics of the flame, in the case of water vapor.

The invention allows the spraying of light or heavy fuel oil, but also the spraying of other liquids, for example liquids composed of liquid waste (ensuring the role of fuel). It also allows the spraying of liquid oxygen, ensuring the role of oxidizer, while the spraying gas is a gaseous hydrocarbon, ensuring the role of fuel. It also applies to a liquid consisting of sludge, embers or any fuel with high viscosity.

Oxygen combustion is used in many applications (glass melting, non-ferrous melting, heating of steels, etc.). Among the fuels used, there are liquid fuels, for example light fuel oil or heavy fuel oil. This liquid is sprayed so that it can then burn.

One of the most common methods of spraying (dispersing the liquid) and making droplets is to serve as a second fluid, generally a gas; this is assisted spraying.

In combustion, these droplets will directly govern the characteristics of the flame (flame length, stability, etc.) as well as the emissions produced (NOx, soot). Spraying is therefore a critical step in the combustion of liquids.

It is sought to have a sufficient number of small diameter drops to ensure the stability of combustion. In particular, the quality of a sprayer is measured by the size of the drops it generates. The generally used parameter is the Sauter Mean Diameter (SMD), which is preferably less than 50 μ.

The mechanisms responsible for spraying can schematically be divided into two distinct groups: impact spraying mechanisms (Figure 1A) or destabilization spraying mechanisms (Figure 1B).

These mechanisms differ in the way the spray fluid is used in sprayer 2.

In the first case (FIG. 1A), the spraying is linked to the impact between the liquid 4 and the spraying fluid 6 or the liquid 4 and a wall or even between the liquid and itself. It is then the kinetic energy of the spray fluid which contributes to fractionating the liquid jet into drops.

In the second case (FIG. 1B), the spraying depends on the interactions at the interface of the liquid 4 and the spraying fluid 6. These interactions will generate instabilities which, once amplified, lead to the rupture of the liquid jet and to making drops. This destabilization is all the more amplified and effective the greater the speed differential at the interface, and the thinner the interface. State-of-the-art sprayers use only one of these two mechanisms.

Some sprayers only use the impact mechanism. This is, for example, the case of the sprayers described in documents US Pat. No. 5,393,220 and US Pat. No. 5,681,162. In document US Pat. No. 5,681,162, the spraying is carried out using two independent and very distinct spraying fluids. The control of their flow is done independently.

In the case of document US Pat. No. 5,393,220, there is a single spraying fluid, the second gaseous fluid in play, on the outer ring, ensuring complete combustion. It therefore does not participate in the spraying. Only impact mechanisms are used in this document.

Some sprayers only use the destabilization mechanism. This is for example the case of document EP 755 720 where all the fluids flow in parallel in order to promote the destabilization processes of the interface. In this document, the typical operating pressure is 1 to 5 bar relative.

Document US Pat. No. 3,733,165 uses a central flow of oxygen which sucks up part of the liquid fuel. The mixture thus obtained is then sprayed by the destabilization mechanism using a second fluid distinct from the first which is air or water vapor.

Known liquid sprayers, using a spray fluid, fall into two main categories: sprayers called "airblast 'and sprayers called" air-assisted ".

On this subject, one can refer to the work of A. Lefebvre, Atomization and Sprays, 1989, Taylor & Francis.

In the first case, the pressure level used for the spraying fluid is between ("airblast plainjet") 1 and 7 bar (relative) or ("airblast prefilming") 1 and 10 bar (relative). It is between 1 and 6 bar (relative) in the second case ("air assisted").

In addition, to have a correct spraying, that is to say a drop diameter (SMD for example) of the order of 50 μm, it is then necessary to work with a relative pressure greater than 5 bar on the fluid. spray.

In general, the minimum pressure to have an SMD of the order of 50 to 100 μ is 1.5 barg (some applications indeed allow drops of diameter greater than 50 μm). This has a consequence on the structure of the spray lines of an oxygen distribution system. Such a distribution system according to the prior art is illustrated in FIG. 2.

Such a system makes it possible to supply oxygen, with a purity of between 88% and 100% using adsorption technology, and in particular the VSA (“Vacuum Swing Adsorption”), or VPSA (“Vacuum Pressure”) technique. Swing Adsorption ") or PSA (" Pressure Swing Adsorption "). These different techniques generally all have in common that the complement to oxygen is argon (in general from 2 to 5%), the molecule of which is very close to the oxygen molecule, and nitrogen, that we cannot totally eliminate but whose concentration can drop to less than 1%. In general, it is hardly possible, with these techniques, to obtain an oxygen purity greater than 97%.

In FIG. 2, the means making it possible to obtain oxygen in this way are designated by the reference 12.

However, the relative pressure of the oxygen thus obtained is low, less than 1 bar relative.

With the help of a low-cost booster, this pressure can be slightly increased, which nevertheless remains insufficient for conventional fuel injectors.

A compressor 14 is therefore mounted at the outlet of these means 12.

The spray line 10 further comprises a main line 16 which is divided, for example, into several burner supply lines. In Figure 2 only one spray line is shown. Each burner supply line is divided into a combustion line 17 and a spray line 18 which leads to a sprayer 2. The whole is then brought to the burner 19 to which is also connected an oil supply 21. The pressure drops in the main line 16 and the spray line 18 are respectively of the order of 150 mbarg and 250 mbarg.

These losses are in addition to the 1,500 mbarg necessary for the use of the sprayer 2, as already explained above. The installation therefore requires oxygen production with a pressure of approximately 1,900 mbarg. However, in the case of VSA oxygen production, the pressure available at the outlet of compressor 14 is 700 mbarg for a "Roots" compressor and 1600 mbarg for a "Piston low pressure" type compressor. In the case of PSA type oxygen production, these values, at the outlet of compressor 14, are 1100 and 2000 mbarg respectively.

In particular, in the case of a PSA production with a compressor of the "Piston low pressure" type, 2000 mbarg is reached, which is theoretically satisfactory, but which offers too little margin compared to the lower limit imposed for the pressure.

The pressures at the compressor outlet are therefore not sufficient to provide the 1,900 mbarg required by an oxygen spray line. There is therefore a need to add a booster 20 which will raise the pressure to the level sufficient to allow the spraying of oxygen.

Such a booster also obviously has a cost.

The problem therefore arises of finding a sprayer capable of operating with a reduced spray fluid pressure in order to be able to spray combustible liquid, for example light fuel oil or heavy fuel oil.

There is also the problem of finding a sprayer making it possible to suppress the booster 20 in a spraying line such as that illustrated in FIG. 2. There is also the problem of finding a new device and a new spraying process making it possible to generate the drops with a satisfactory average diameter, and preferably with reduced pressure.

Statement of the invention

The invention aims to solve these problems. It first relates to a spraying device for spraying a liquid using a spraying fluid, comprising: - a pipe for injecting a liquid to be sprayed,

- an area or a spray duct, - at least one pipe for injecting a spraying fluid,

- At least two pipes for circulation of the spray fluid leaving this injection pipe and joining the zone, or the spray pipe, the spray fluid being divided into several parts between the circulation pipes.

The presence of at least two conduits for circulation of the spraying fluid makes it possible to reduce the injection pressure of this fluid.

According to another aspect, the invention relates to a spraying device for spraying a liquid using a spraying fluid, comprising:

- a pipe for injecting a liquid to be sprayed,

- at least one pipe for injecting a spraying fluid,

means for forming a film of said liquid to be sprayed,

means for producing an impact between a first part of the spraying fluid and said film,

- Means for achieving destabilization by interactions at the interface between said film of liquid to be sprayed and a second part of the spraying fluid.

The spraying using two spraying phenomena makes it possible to produce drops with a correct diameter (of the order of 50 μ or less), with a reduced relative pressure for the spraying fluid.

The means for forming a film of liquid to be sprayed (of thickness less than 1 mm but greater than 0.25 mm), comprise, according to one embodiment, a first and a second wall parallel to each other, for example formed respectively by the outer wall of a central duct of a distributor, and through the inner wall of an injector.

The invention also relates to a system for spraying a liquid, comprising means for producing a spraying fluid, and a spraying device according to the invention.

The invention also relates to a method of spraying a liquid using a spraying fluid, using a device or a system according to the invention. The invention makes it possible to use only one spraying fluid, and with a reduced pressure, between 100 mbarg and 1 barg. Only two flow rates are therefore to be managed, the flow rate of the liquid to be sprayed and the flow rate of the spraying fluid.

Brief description of the figures - Figures 1 A and 1 B schematically represent the principles of two known spraying mechanisms,

FIG. 2 represents a known spray line according to the prior art,

FIG. 3 represents an embodiment of a sprayer according to the invention,

FIGS. 4 and 5 illustrate the determination of the parameters of a sprayer according to the invention,

- Figure 6 shows a spray line according to the invention, using a sprayer according to the invention.

Detailed description of embodiments of the invention

An embodiment of a sprayer 22 according to the invention will be described in connection with FIG. 3.

In this figure, a dispenser 31 has a central duct 32 through which a liquid to be sprayed arrives.

It also comprises two lateral conduits 34, 36, through which a spray fluid arrives.

These conduits move towards the central axis of the injector, in the direction of flow of the liquid. In practice, these two lateral conduits 34, 36 can be identical by producing a single cylindrical conduit around the distributor 31.

A central zone 46 constitutes a zone or a chamber or a spray duct, in which or in which the liquid to be sprayed ends up on the one hand, and the spraying fluid on the other hand.

The spraying fluid is injected into the zone 46, on the one hand by a central spraying duct 38 (of internal diameter Dj _nt ) to which one (or more, for example between one and four) leads transverse duct 40, which starts from the lateral duct 36, and on the other hand by one or more (for example between one and eight) lateral orifice (s) / aux 42 made in the injector 44. Thus, the spraying fluid is injected by several routes, which makes it possible to reduce the pressure necessary for correct operation of the sprayer.

The liquid to be sprayed flows, from the central injection duct 32, into one or more (for example between one and four) channels 37, then into a channel 48 formed between the outer wall of the central spray duct 38 and the inner wall of the injector 44. If these two walls are cylindrical with relative diameters D ^" κ _q and D ⁺ ij _q , a film of liquid produced by flow in the channel 48 has a thickness equal to (D ⁺ π _q - D ^" ι _iq ) / 2.

The film of spray liquid thus produced meets the spray liquid injected through the side ports 42, with which impact spraying occurs. It also enters into surface interaction (or destabilization) with the spraying fluid injected into the zone 46 via the conduit 38, directed in a direction parallel or tangential to the film of liquid to be sprayed and which also contributes to the spraying of the film. liquid to spray.

The two spraying mechanisms occur simultaneously and contribute to a good spraying of the liquid, as well as to the reduction of the pressure necessary for the sprayer to function correctly, that is to say by producing a drop diameter (SMD) on the order of 50 μm or less.

The assembly made up of parts 31 and 44 is housed in a nozzle 50. This contains a conical part 52 and ends in an end piece 54 of constant section. The nozzle draws the contours of, or guide, the flow of the spraying fluid which will be distributed between the passage or transverse conduit 40 and the part 60 of the lateral conduit 36 which will approach the axis of the injector.

In this latter part 60, it is possible to add a tangential component to the spraying fluid injected by the lateral orifices 42. This part of the spraying fluid therefore has on the one hand a spraying effect and on the other hand a destabilizing effect . The destabilization phenomena are then amplified by the speed differential at the interface. Adding a tangential component ("swiri") plays an important role: by a centrifugal effect, the axial speed component is increased in the vicinity of the interface. Thus, the speed differential is locally increased. Adding a swiri angle is therefore also beneficial for the quality of the spray.

The device according to the invention makes it possible to reduce the injection pressure of the spraying fluid, while requiring only the management of two flow rates: the liquid flow rate and that of a single spraying fluid.

With the sprayer according to the invention, the upstream pressure of the spraying fluid is between 100 mbarg and 1 barg for spraying combustible liquid, for example light fuel oil or heavy fuel oil (for example: 300 mbarg for heavy fuel oil).

This reduced pressure makes it possible to produce a spraying line without a booster.

The state of the art uses two spray fluids (for example US 5,681,162 or US 3,733,165). According to the invention, the two spraying mechanisms (impact and destabilization) take place almost simultaneously. The liquid film is both faced with an impact (the kinetic energy of the fluid coming from the channel (s) / at 32 will disintegrate the liquid film) and by a destabilization (the speed of the spraying fluid coming from conduit 38 will destabilize 'liquid interface). The coexistence of these two phenomena makes it possible to reduce by three the pressures of use compared to the state of the art. For example, the pressure recommended in EP 755 720 is between 1 bar and 5 bar relative, the pressure recommended in US 3,733,165 is between 0.3 and 2 kg / cm ² G (or 0.29 and 1.96 bar relative). According to the invention, the pressure necessary to obtain a correct spraying is between 0.1 and 0.9 or 1 relative bar.

The generic advantages linked to the use of oxygen (of a purity of between 88% and 100%) as spraying fluid are in particular the reduction in the amount of NO _x , linked to the elimination of all or part nitrogen contained in the air usually used as spraying fluid (air is for example used as spraying fluid in US 3,733,165, EP 755,720).

The NO _x reductions are even greater for applications where the oxidant used for combustion is also oxygen (with a purity between 88% and 100%). In addition to these generic advantages, the use, according to the invention, of oxygen at low pressure provides the following additional advantages. Low pressure oxygen has a low speed.

The pulse of the spray of liquid spray is therefore reduced, as is that of the flame. The result is:

- lower flame temperatures,

- a more uniform distribution of heat flow,

- lower vault and refractory temperatures,

- less NO _x and SO _x produced in the flame, - less volatilization.

Let K be the ratio between the mass flow rate of the spraying fluid and the mass flow rate of liquid. One can take, for the injector according to the invention: 0.1 <K <1.

Let λ be the fraction of the spray fluid flow rate which passes through the central circuit 40-38. We can take, for an injector according to the invention 0.1 <λ <0.5.

The spray fluid flow rate which passes through the central circuit 40-38 is therefore equal to λ. K times the mass flow rate of liquid (Qliq). The minimum therefore corresponds to λ. K = 0.01, and the maximum corresponds to λ. K = 0.5.

The following figures detail the relationships which exist in the proposed injector, in the case where the liquid to be sprayed is heavy fuel oil No. 2 (F02), with a flow rate approximately equal to 100 kg / h

FIG. 4 describes the choice of the central diameter Dj _nt : for a given liquid flow, the field of choice of D | _n t is described by the area between:

• A minimum diameter of 1 mm (for reasons of feasibility),

• the two lines Vmini = 20 m / s and Vmaxi = 250 m / s (minimum and maximum speeds in an atomizer for a central jet), • the two curves corresponding to the minimum central spray fluid flow rates: (0.01 * Qliq) and maximum: (0.5 * Qliq).

It can be seen that, preferably, D _int is between 2 mm and 7 mm, or is equal to, or close to, 3 mm.

A diameter between 3 mm and 7 mm allows operation over the entire speed range desired. A diameter of the order of 3 mm also makes it possible to limit the size of the injector. FIG. 5 describes the choice of the screen for the liquid flow (or thickness of the film of liquid to be sprayed). The dimensions D ⁺ ιι _q and D ^~ π _q have been defined above. Preferably, one seeks to satisfy two main criteria: "the weft (D ^" ij _q -D ⁺ π _q ) / 2 is greater than 0.25 mm to avoid any risk of clogging,

• the speed of the liquid within the frame is greater than 1 m / s and less than 10 m / s.

For Q | j _q = 100 kg / h, we will preferentially choose for (D ⁺ ij _q -D ^" | _iq ) a value between 0.8 mm or 0.9 mm and 1, 1 mm, or 1, 2 mm especially the value of 1 mm.

As regards the conical nozzle, it ends with a nozzle 54 of length L _n and internal diameter D _n .

These two dimensions are chosen so that the gas-liquid mixture exiting through the channel 46 does not impact on the internal rim of this end piece 54.

The angle of a jet being 11 °, the previous condition implies:

0 <L _n / (D _n -D ⁺ | _iq ) <2.6

The sprayer according to the invention uses only one spraying fluid, distributed between several passages or conduits (at least two, one being designated by the reference 40 in FIG. 2, the other by the reference 60 ). Only two flow rates are to be managed: the flow rate of the liquid to be sprayed and the flow rate of the spraying fluid.

A liquid film is also produced, which is subjected simultaneously to two sputtering phenomena, by impact and by destabilization. The number of lateral orifices 42 used in a spraying device according to the invention is at least equal to one. Several orifices 42 can be distributed, symmetrically or not, around the combustion zone 46.

A sprayer according to the invention can be used in a spray line or an oxygen distribution system similar to that or that illustrated in FIG. 2 above. Such a line of spraying is represented in FIG. 6, in which the references identical to those of FIG. 2 designate therein identical or similar elements.

In particular, the means 12 make it possible to produce impure oxygen by adsorption, the outlet pressure of which is less than approximately 3 bar relative.

The main line 16 comprises for example (is indicated in brackets, for each component, the pressure drop induced by this component): - a silencer 161 (20 mbarg),

- a heat exchanger 162 (20 mbarg),

- control valves 164, 166 (5 mbarg for each valve),

- quarter-turn valves 163, 165 (5 mbarg for each valve),

- a flowmeter 167 (30 mbarg),

- a non-return valve (20 mbarg),

- various elements such as pipes, elbows, etc. (40 mbarg). In total, the pressure drop in main line 16 is around 150 mbarg.

Reference 168 designates a high pressure oxygen reserve (not used during normal operation of the installation).

Each spray line 18 is associated with an oven 19 and comprises, according to an example: - a quarter-turn valve 181 (10 mbarg),

- a flow meter 182 (30 mbarg),

- a 190 regulator (150 mbarg),

- a flexible 192 (20 mbarg),

- various elements such as pipes, elbows, etc. (25 mbarg). The pressure of the furnace 19 is typically 15 mbar, which brings the total pressure drop in the spray line 18 to about 250 mbarg.

The combustion oxygen is directed to the burner 19 via a regulating valve 183, a quarter-turn valve 184 and a hose 185. The pressure required at the outlet of the compressor 14 is therefore 700 mbarg, in the case of a sprayer 22 according to the invention operating with an injection pressure of 300 mbarg (with a screen of 1 mm and Dj _nt equal to 3 mm).

The pressure levels available at compressor outlet 14 and already indicated above (VSA installation: 700 mbarg for a "Roots" compressor and 1600 mbarg for a "Piston low pressure" type compressor; PSA installation: 1100 mbarg respectively and 2,000 mbarg) are therefore now sufficient to provide the 700 mbarg necessary for spraying, which makes it possible to remove the booster 20 from the installation. The installation of FIG. 6 therefore does not include a booster.

The implementation of the invention allows the use of oxygen supplied by an in situ oxygen supply system (VSA / VPSA / PSA), the oxygen being supplied, in particular by adsorption, at a purity of between 88 % and 100%, the impurities being essentially argon and / or nitrogen, and the oxygen being supplied at a relative pressure of between 500 and 1,900 mbarg, preferably between 700 and 1,400 mbarg.

Variants can be implemented for producing a spray line or a distribution system with a sprayer according to the invention.

However, it is preferable, as illustrated in Figure 6, to use a regulator 184 on the spray line. Preferably, a regulator with a low pressure drop of between 100 and 200 mbar (preferably 150 mbar) will be chosen. The use of this regulator makes it possible to completely overcome pressure fluctuations from the compressor (typically 25 mbar around the nominal pressure). By thus maintaining a constant pressure at the level of the sprayer, constant flame characteristics are obtained whatever the pressure variations coming from the compressor, the stoichiometry of the burner and the power of the burner.

Claims

1. Spraying device for spraying a liquid using a spraying fluid, comprising: - a pipe (32) for injecting a liquid to be sprayed,

- a spraying zone or duct (46),

- at least one injection pipe (34, 36) of a spraying fluid,

- At least two conduits (40, 60) for circulation of the spraying fluid leaving this injection conduit and joining the zone, or the spraying conduit (46), the spraying fluid being divided into several parts between the circulation.

2. Device according to claim 1 comprising: - means (48) for forming a film of the liquid to be sprayed;

- means (42) for making an impact between a first part of the spraying fluid and the film of liquid to be sprayed,

- Means (38) for achieving destabilization by interaction at the interface between said film of the liquid to be sprayed and a second part of the spraying fluid.

3. Spray device for spraying a liquid using a spray fluid, comprising:

- a pipe (32) for injecting a liquid to be sprayed, - a spraying area or pipe (46),

- at least one injection pipe (34, 36) of a spraying fluid,

- means (48) for forming a film of said liquid to be sprayed,

- means (42) for making an impact between a first part of the spraying fluid and said film,

- Means (38) for achieving destabilization by interaction at the interface between said film of liquid to be sprayed and a second part of the spraying fluid.

4. Device according to claim 2 or 3, the means for forming a film of liquid to be sprayed comprising a first and a second wall (38, 44) parallel to each other.

5. Device according to one of claims 2 to 4, the thickness of the liquid film being greater than 0.25 mm.

6. Device according to claim 5, the thickness of the liquid film being between 0.4 mm and 0.6 mm.

7. Device according to claim 6, the thickness of the liquid film being equal to 0.5 mm.

8. Device according to one of claims 2 to 7, the means (42) for making an impact between a first part of the spraying fluid and the film of liquid to be sprayed comprising means for directing a first part of the spraying fluid towards the, or towards the film of liquid to be sprayed.

9. Device according to claim 8, the means for directing a first part of the spray fluid towards, or in the direction of, the film of liquid to be sprayed comprising at least one orifice (42), produced in the spray duct (46) , or which directs said first portion of the spray fluid to said spray area (46).

10. Device according to one of claims 2 to 9, the means for achieving destabilization by interaction at the interface between said film of liquid to be sprayed and a second part of the spraying fluid comprising means (38) for directing said second part of the spraying fluid in a direction parallel or tangential to said film of liquid to be sprayed.

11. Device according to claim 10, the area or the spray duct (46), having the shape of a first cylinder of revolution, of internal diameter D ⁺ π _q , the means (38) for directing said second part of the fluid spraying in a parallel direction or tangential to said film of liquid to be sprayed comprising a central spray duct (38), having the shape of a second cylinder of revolution, of outside diameter (D ^" ι _iq ) smaller than the inside diameter of the first cylinder.

12. Device according to claim 11, the central spray duct (38) having an internal diameter (Dj _n t) of between 2 mm and 7 mm.

13. Device according to claim 12, the central duct (38) for spraying having an internal diameter (Dι _nt ) equal to, or close to, 3 mm.

14. Device according to one of claims 1 to 13, one of the conduits (60) for circulation of the spraying fluid further comprising means for giving the spraying fluid a velocity component tangential to the zone or conduit (46 ) spraying.

15. Device according to one of claims 1 to 14, comprising a conical outer casing, extended by a nozzle whose internal shape is that of a cylinder of revolution of diameter D _n and length L _n , D _n and L _n being such that the mixture of liquid and spraying fluid leaving the zone (46) flows without impact against the interior of the nozzle.

16. Device according to claim 15, the zone, or the duct (46), of spraying having the shape of a cylinder of revolution, of internal diameter D ⁺ π _q , D _n , L _n and D ⁺ π _q being such than :

0 <Ln / (D _n - D ⁺ _Iiq ) <2.6.

17. A system for spraying a liquid comprising means (12) for producing a spraying fluid, and a spraying device according to one of claims 1 to 16.

18. The system of claim 17, further comprising a spray line (18) for injecting the spray fluid. produced by the means (12) in the, or the, injection fluid injection pipe (34, 36).

19. The system of claim 17 or 18, the means (12) being means for producing oxygen by adsorption.

20. The system of claim 19, the means (12) producing oxygen at a pressure less than 3 bar relative.

21. System according to one of claims 17 to 20, the line

(18) of spraying being provided with a low pressure drop regulator.

22. Method for spraying a liquid using a spray fluid, in which the liquid and the spray fluid are injected into a spray device according to one of claims 1 to 16 or a spray system according to one of claims 17 to 21.

23. The method of claim 22, the spray fluid being oxygen.

24. The method of claim 23, the oxygen being of purity between 90% and 100%.

25. Method according to one of claims 22 to 24, the spraying fluid being injected into the spraying device with a pressure between 100 mbarg and 1 barg.

26. Method according to one of claims 22 to 25, the liquid to be sprayed being fuel oil, light or heavy, or consisting of liquid waste, or comprising a mixture of liquid oxygen and gaseous hydrocarbon, or comprising sludges , or embers, or a high viscosity fuel.