GB2430635A

GB2430635A - An atomising apparatus

Info

Publication number: GB2430635A
Application number: GB0520006A
Authority: GB
Inventors: Jude Alexander Glynn Worthy; Daniel James Mannion
Original assignee: Pursuit Dynamics PLC
Current assignee: Pursuit Dynamics PLC
Priority date: 2005-10-01
Filing date: 2005-10-01
Publication date: 2007-04-04
Also published as: GB0520006D0

Abstract

An atomising apparatus for generating a mist or spray comprises a working fluid conduit (3) adapted to supply a working fluid, and a transport fluid conduit (8) adapted to supply a transport fluid. A mixing chamber (3A) is in fluid communication with the working fluid and transport fluid conduits (3,8) and a transport fluid nozzle (16) directs transport fluid into the mixing chamber (3A) from the transport fluid conduit (8). The transport fluid nozzle (16) directs the transport fluid into a flow of working fluid in the mixing chamber (3A) to atomise the working fluid and form a dispersed vapour/droplet flow regime of atomised working fluid droplets. The apparatus further comprises an electrostatic charging means (50,70,80,90) located adjacent at least one of the transport fluid nozzle (16) and mixing chamber (3A) and adapted to apply an electrostatic charge to the transport fluid flow and/or the atomised working fluid droplets.

Description

1 Atomising Apparatus for Generating a Mist or Spray 3 The present

invention relates to atomising apparatus 4 for generating a mist or spray. In particular, but not exclusively, the present invention relates to 6 electro-statically charging a mist or spray 7 generated by an atomising apparatus.

9 The present invention has numerous applications in

various fields. Most notably, atomising apparatus

11 for generating a mist or spray has particular 12 applications in fire suppression, decontamination 13 arid gas scrubbing, but not limited thereto.

In the particular field of fire suppression,

16 atomising apparatus is known to provide a water 17 spray or mist to suppress a fire, which has the 18 advantage of using a relatively small amount of 19 water compared with conventional water spray systems. However, such atomising apparatus requires 21 a relatively high pressure to force the water 22 through relatively small nozzles to form a water 1 mist. Typically these pressures are 20bar or 2 greater. As such, a gas-pressurised tank is required 3 to provide the pressurised water, thus limiting the 4 run time of known atomising apparatus.

6 Also, due to the droplet formation mechanism, and 7 the high tendency for droplet coalescence, known 8 atomising apparatus create a mist with a wide range 9 of water droplet sizes. It is known that atomised water droplets of approximately 40-5Opm in diameter 11 from conventional atomising apparatus provide the 12 optimum compromise for fire suppression for a number 13 of fire scenarios. This is because droplets in this 14 range from conventional atomising apparatus provide the greatest surface area for a given volume, whilst 16 also providing sufficient mass to project a 17 sufficient distance and to also penetrate into the 18 heat of a fire. The majority of conventional 19 atomising apparatus for fire suppression only manage to achieve a low percentage of atomised water 21 droplets in this key size range. Also, although 22 smaller droplets will tend to behave as a gas, the 23 larger droplets in the flow will themselves impact 24 with these smaller droplets so reducing their effectiveness.

27 A water mist comprised of droplets with a droplet 28 diameter size less than 40tm will improve the rate 29 of cooling the fire and also reduces damage to items in the vicinity of the fire. However, such droplets 31 from conventional atomising apparatus may not have 32 sufficient mass, and hence momentum, to project a 1 sufficient distance and to also penetrate into the 2 heat of a fire.

4 According to a first aspect of the present invention there is provided atomising apparatus for generating 6 a mist or spray comprising: 7 a working fluid conduit having a working fluid 8 inlet; 9 a transport fluid conduit having a transport fluid inlet in fluid communication with the 11 transport fluid conduit; 12 a transport fluid nozzle in fluid communication 13 with the transport fluid conduit, the transport 14 fluid nozzle having an angular orientation and configuration such that in use the transport fluid 16 is directed towards a working fluid from the working 17 fluid conduit to atomise the working fluid to form a 18 dispersed vapour/droplet flow regime which is 19 discharged as a mist comprising atomised working fluid droplets; and 21 charging means adapted to provide an electro- 22 statically charged mist.

24 Preferably the apparatus includes a mixing chamber, into which the working fluid and transport fluid are 26 introduced, and wherein the working fluid is 27 atomised by the transport fluid.

29 Preferably the apparatus includes a charging nozzle at or adjacent an exit of the apparatus, the 31 charging nozzle being adapted to either charge or 32 steer the discharged mist.

2 Preferably the charging means includes at least one 3 inductance coil to electro-statically charge the 4 working fluid, the transport fluid, the dispersed vapour/droplet flow regime or the mist.

7 Additionally or alternatively the charging means 8 includes an electrode to electro-statically charge 9 the working fluid, the transport fluid, the dispersed vapour/droplet flow regime or the mist by 11 corona charging.

13 Additionally or alternatively the charging means 14 includes a portion of the inner surface of the working fluid inlet, the working fluid conduit, the 16 mixing chamber, the exit, the transport fluid inlet, 17 the transport fluid conduit, the transport fluid 18 nozzle or the charging nozzle being made of a 19 suitable material to help generate a charge on the fluid passing therethrough due to friction.

22 Preferably any of the portions of the inner surfaces 23 have at least one projection or indentation to 24 increase the surface wall area to promote charging and/or turbulence.

27 Additionally or alternatively the charging means 28 includes a charging mesh disposed in the apparatus 29 to provide an electro-statically charged mist.

1 Preferably the charging mesh is located proximate 2 the working fluid conduit, the transport fluid 3 conduit, or the transport fluid nozzle.

More preferably the charging mesh is located 6 proximate the location where the dispersed 7 vapour/droplet flow regime is formed.

9 Additionally or alternatively the charging means is located proximate the working fluid inlet, the 11 transport fluid inlet, the mixing chamber or the 12 exit.

14 Preferably electra-static steering means is located around the circumference of the mixing chamber to 16 steer the charged atomised droplets therein.

18 Preferably the apparatus includes magnetic means.

Preferably the magnetic means is substantially 21 disposed at the locationd where the dispersed 22 vapour/droplet flow regime is formed.

24 In a preferred embodiment the apparatus further comprises a second working fluid conduit in fluid 26 communication with a second working fluid inlet and 27 a working fluid nozzle.

29 Preferably the working fluid nozzle is adapted to introduce working fluid into the mixing chamber.

1 Additionally or alternatively the charging means is 2 located at or adjacent to the second working fluid 3 inlet, second working fluid conduit or working fluid 4 nozzle.

6 According to a second aspect of the present 7 invention there is provided a method of generating a 8 mist or spray comprising the steps of: introducing a transport fluid via a transport 11 fluid nozzle into a stream of working fluid, the 12 transport fluid nozzle having an angular orientation 13 and configuration to atomise the working fluid by 14 interaction of the transport fluid to form a dispersed vapour/droplet flow regime; 16 electro-statically charging the working fluid, 17 transport fluid or the dispersed vapour/droplet flow 18 regime; and 19 discharging the dispersed vapour/droplet flow regime as a mist comprising atomised working fluid 21 droplets, wherein the atomised working fluid 22 droplets are provided with an electro-static charge.

24 Preferably the method includes the step of introducing the working fluid and transport fluid 26 into a mixing chamber, wherein the working fluid is 27 atomised by the transport fluid to form the 28 dispersed vapour/droplet flow regime.

Preferably the method includes the step of 31 introducing the working fluid via a working fluid 32 nozzle.

2 Preferably the method includes the step of electro- 3 statically charging the dispersed vapour/droplet 4 flow regime substantially at the location where it is formed.

7 Preferably the method includes the step of charging 8 or steering the discharged mist by virtue of a 9 charging nozzle.

11 Preferably the method includes the step of steering 12 the dispersed vapour/droplet flow regime in the 13 mixing chamber by virtue of electro-static steering 14 means.

16 Preferably the method includes the step of providing 17 an electro-static charge to the working fluid, the 18 transport fluid, the dispersed vapour/droplet flow 19 regime or the mist by virtue of at least one inductance coil disposed in the apparatus.

22 Preferably the method includes the step of providing 23 an electro-static charge to the working fluid, the 24 transport fluid, the dispersed vapour/droplet flow regime or the mist by virtue of at least one 26 electrode disposed in the apparatus.

28 Preferably the method includes the step of providing 29 an electro-static charge to the working fluid, the transport fluid, the dispersed vapour/droplet flow 31 regime or the mist by virtue of a charging mesh 32 disposed in the apparatus.

2 Preferably the method includes the step of providing 3 an electro-static charge to the working fluid, the 4 transport fluid, the dispersed vapour/droplet flow regime or the mist by virtue of the apparatus having 6 a portion of suitable material to help generate a 7 charge on the fluid passing therethrough due to 8 friction.

Preferably the method includes the step of providing 11 a magnetic field substantially at the location where 12 the dispersed vapour/droplet flow regime is formed.

14 Embodiments of the present invention will now be described, by way of example only, with reference to 16 the accompanying drawings in which: 18 Fig. 1 is a cross-sectional side view of a first 19 embodiment of an atomising apparatus for generating a mist or spray; 22 Fig. 2 is a cross-sectional side view of part of the 23 apparatus of Fig. 1, having modifications; Fig. 3 is a cross-sectional side view of a second 26 embodiment of an atomising apparatus for generating 27 a mist or spray; and 29 Fig. 4 is a cross-sectional side view of a third embodiment of an atomising apparatus for generating 31 a mist or spray.

1 Where appropriate, like reference numerals have been 2 used for substantially like parts throughout the

3 specification.

Referring to Fig. 1 there is shown an atomising 6 apparatus for generating a mist or spray, a mist 7 generator 1, comprising a conduit 2 having a working 8 fluid inlet 4, a working fluid conduit 3, a mixing 9 chamber 3A, and an exit 5.

11 The conduit 2 is substantially cylindrical, but 12 other shapes could equally well be used as desired.

13 By way of example only, the conduit 2 could be made 14 to fit a standard door letterbox to allow fire fighters to easily treat a fire without the need to 16 enter the building.

18 The working fluid conduit 3 is of substantially 19 constant circular cross-section. An introduction of working fluid to be atomised travels from the 21 working fluid inlet 4, through the working fluid 22 conduit 3, into the mixing chamber 3A. It is to be 23 appreciated that the working fluid inlet 4 and 24 working fluid conduit 3 may be of any convenient shape and length suitable for the particular 26 application of the mist generator 1. The working 27 fluid conduit 3 may be circular, rectilinear or 28 elliptical, or any intermediate shape, for example 29 curvilinear.

31 The geometry, i.e. length and cross-section, of the 32 mixing chamber 3A will have an effect on the 1 properties of the discharged mist, e.g. droplet 2 size, droplet density/distribution, projection angle 3 and projection distance. The geometry of the mixing 4 chamber 3A can therefore be thought of as a control parameter to control the properties of the mist.

6 The length and cross-section of the mixing chamber 7 3A is thus chosen to provide a mist with desired 8 properties. The mixing chamber 3A is also 9 configured to provide optimum performance regarding momentum transfer and mass transfer between a 11 transport fluid and a working fluid therein to 12 enhance turbulence, and hence, enhance the 13 atomisation of the working fluid.

In the illustrated embodiment of Fig. 1, the mixing 16 chamber 3A is slightly tapered to form a converging 17 mixing chamber 3A. However, the cross-sectional 18 area may vary along the mixing chamber's length with 19 differing degrees of reduction or expansion, i.e. the mixing chamber may taper at different 21 converging-diverging angles at different points 22 along its length. The mixing chamber may taper from 23 the location of transport fluid nozzle 16 and the 24 taper ratio may be selected such that the multi- phase flow velocity and trajectory of a working 26 fluid and transport fluid is optimised to enhance 27 turbulence, and hence enhance the atomisation of the 28 working fluid.

In one embodiment the length and/or cross-section of 31 the mixing chamber 3A may be adjustable in-situ, 32 rather than pre-designed, in order to provide a 1 measure of controllability over the properties of 2 the mist, e.g. droplet size, droplet 3 density/distribution, projection angle and 4 projection distance.

6 In another embodiment of the present invention, the 7 length of the mixing chamber 3A may be relatively 8 short, e.g. a few millimetres, or the mixing chamber 9 may actually be omitted. In these cases, the atomising process will take place substantially 11 outside of the mist generator 1 adjacent the exit 5.

13 The mist generator 1 further comprises a transport 14 fluid conduit 8, a transport fluid inlet 10, and a transport fluid nozzle 16.

17 The conduit 2 is adapted with a protrusion 6 which 18 on the one part defines part of the working fluid 19 conduit 3, and on the other part defines the transport fluid conduit 8 in the conduit 2. The 21 transport fluid conduit 8 is fed transport fluid 22 from transport fluid inlet 10. The transport fluid 23 conduit 8 is annular, but may be of other forms.

A distal end 12 of the protrusion 6 remote from the 26 working fluid inlet 4 has a tapered surface 14 that 27 defines an annular transport fluid nozzle 16 between 28 it and a correspondingly tapered surface 18 of the 29 internal wall of the conduit 2. The transport fluid nozzle 16 is in fluid communication with the 31 transport fluid conduit 8.

1 The transport fluid nozzle 16 is conveniently angled 2 towards the mixing chamber 3A to optimise 3 atomisation of a working fluid therein by the 4 transport fluid. The creation of turbulence is important to achieve optimum performance by 6 dispersal of the working fluid in order to increase 7 acceleration by momentum and mass transfer. Simply 8 put, the more turbulence there is generated, the 9 greater the intensity of atomisation and the smaller the droplet size achievable.

12 The transport fluid nozzle 16 is configured to cause 13 a transport fluid issuing therefrom to atomise a 14 working fluid in the mixing chamber 3A. The transport fluid nozzle 16 is configured to provide 16 supersonic flow of the transport fluid streaming 17 into the mixing chamber 3A from the transport fluid 18 nozzle 16. However, it is envisaged that the flow 19 of transport fluid into the mixing chamber 3A may alternatively be sub- sonic.

22 The configuration of the transport fluid nozzle 16 23 has an area ratio, which is defined as the ratio of 24 the exit area to the throat area of the nozzle, and an associated included angle, i.e. the angle between 26 the internal walls of the nozzle. It is appropriate 27 to define the area ratio with an associated included 28 angle as a relatively long nozzle with a shallow 29 included angle may have the same area ratio as a much shorter nozzle with a greater included angle.

31 The configuration and angle of the transport fluid 32 nozzle 16 can be manipulated to enhance the 1 atomisation mechanism, and hence, can be manipulated 2 to control the properties of the mist, i.e. droplet 3 size, droplet distribution, projection distance, 4 projection angle, etc., and as such, can be thought of as control parameters to control the properties 6 of the mist.

8 The transport fluid nozzle 16 is preferably 9 configured to provide the highest velocity jet, the lowest pressure drop and the highest enthaiLpy 11 between the transport fluid conduit 8 and the exit 12 of the transport fluid nozzle 16 for given fluid 13 properties of a transport fluid, e.g. dryness as far 14 as steam is concerned, quality, i.e. absence/presence of contaminants, pressure, 16 velocity, density, viscosity, temperature, etc. 18 It is anticipated that the transport fluid nozzle 16 19 may be a single point nozzle which is located at some point around the circumference of the mixing 21 chamber 3A to introduce transport fluid thereto.

22 There may even be a plurality of spaced single point 23 nozzles around the circumference of the mixing 24 chamber 3A. However, an annular configuration will be more effective compared with single point 26 nozzles.

28 The term "annular" as used herein is deemed to 29 embrace any configuration of nozzle or nozzles that define a radial pattern, and encompasses circular, 31 irregular, polygonal, elliptical and rectilinear 32 shapes of nozzle.

2 The mist generator 1 also comprises charging means 3 50, 60, 70, 80, 90 to provide an electro-statically 4 charged mist; this can be done by charging the working fluid and/or transport fluid, and/or the 6 dispersed vapour/droplet flow regime. Charging the 7 dispersed vapour/droplet flow regime at the location 8 where it is formed may advantageously enhance the 9 intensity of the atomisation mechanism, thus allowing for a relatively smaller droplet formation.

12 There are several types of charging. The most 13 common types of charging are inductance charging and 14 corona charging. Inductance charging involves supplying an inductance coil with a very high 16 voltage which generates an electric field to charge 17 the working fluid, transport fluid, or the dispersed 18 vapour/droplet flow regime with a polarity opposite 19 to that of the inductance coil. In corona charging, an electrode is supplied with a large voltage. When 21 the voltage is large enough, and there is enough 22 charge in a small area, the resultant electric field 23 associated with the electrode is strong enough to 24 break down surrounding molecules. This results in the formation of a region known as corona. In 26 comparison with corona charging, inductive charging 27 tends to require lower voltages, be relatively 28 cheaper to implement, and is safer as it reduces the 29 risk of arcing or other accidental discharge of the charge.

1 Whilst it is envisaged that a working and/or 2 transport fluid supply could be electro-statically 3 charged before entering the mist generator 1, an 4 inductance coil 50 may be located at various locations around the mist generator 1 to charge the 6 working fluid, transport fluid, or atomised working 7 fluid droplets. For instance, inductance coil 50 8 may be located adjacent the transport fluid inlet 9 10, the transport fluid conduit 8, the transport fluid nozzle 16, the working fluid conduit 3, the 11 working fluid inlet 4, the mixing chamber 3A, or 12 adjacent the exit 5.

14 Advantageously the inductance coil should be located at the location where the dispersed vapour/droplet 16 flow regime is formed, since this may aid the 17 atomisation mechanism.

19 The inductance coils 50 could equally well be one or more corona electrodes.

22 It is to be appreciated that the inductance coils or 23 corona electrodes 50 need to be electrically 24 insulated.

26 In use a working fluid to be atomised is introduced 27 into working fluid inlet 4, and transport fluid is 28 introduced into transport fluid inlet 10.

The working fluid can be any fluid or mixture of 31 fluids, including liquids, gases, powders, flowable 32 solids, and slurries, and will depend on the 1 particular use of the apparatus. By way of example 2 only, in the particular field of fire suppression, 3 the working fluid may be water or a non-flammable 4 liquid, inert gas or powder, which absorbs heat when vaporised to help suppress a fire; and in the fields 6 of decontamination and gas scrubbing, the working 7 fluid may be a chemical or a mixture of chemicals 8 and other fluids.

The transport fluid can be any compressible fluid or 11 a mixture of compressible fluids, such as air, 12 steam, nitrogen, helium, or other gasses or vapours.

14 The working fluid introduced into the working fluid inlet 4 will travel into the mixing chamber 3A via 16 the working fluid conduit 3. The transport fluid 17 introduced into the transport fluid inlet 10 will 18 travel through the transport fluid nozzle 16 via 19 transport fluid conduit 8.

21 A high velocity jet will exit the transport fluid 22 nozzle 16, impacting the working fluid in the mixing 23 chamber 3A with high shear forces, thus atomising 24 the working fluid and breaking it into fine droplets and producing a dispersed vapour/droplet flow regime 26 which is discharged as a mist out of the exit 5.

28 The atomisation mechanism of the present invention 29 has a primary and secondary break up mechanism which are fully described in the applicant's pending 31 applications, Nos PCT/GB2004/000720 and 32 PCT/GB2005/000708, and so will not be discussed 1 further herein. However, in simple terms, the 2 present invention uses the transport fluid to 3 "slice-up" the working fluid into small diameter 4 droplets. As already touched on, the more turbulence you have, the smaller the droplet size 6 achievable.

8 By virtue of the charging means 50, 60, 70, 80, 90, 9 an electro-static charge will be applied to the working fluid, transport fluid and/or dispersed 11 vapour/droplet flow regime to produce a discharged 12 mist comprising atomised working fluid droplets 13 having a charge. These charged atomised working 14 fluid droplets will have the advantages of being attracted to surfaces, allow for even spraying on 16 surfaces, and may help to increase atomisation thus 17 providing relatively smaller diameter atomised 18 droplets.

It is also to be appreciated that the fluid 21 properties of the working and transport fluid chosen 22 will have an effect on the atomisation mechanism, 23 and therefore on the mist's properties. The fluid 24 properties of the working and transport fluid can therefore be thought of as control parameters to 26 control the properties of the discharged mist.

28 For applications where steam is not readily 29 available, or where a quick start to the mist generator 1 is required, the transport fluid can 31 initially be air. Meanwhile, a rapid steam 32 generator or other means can be used to generate 1 steam. Once the steam is available, the transport 2 fluid can be switched over from the air supply to 3 the steam supply.

The mist generator 1 may include magnetic means (not 6 shown) . Advantageously, the magnetic means should 7 be disposed substantially at the location where the 8 dispersed vapour/droplet flow regime is formed to 9 aid the atomisation mechanism, although the magnetic means may be located elsewhere on the mist generator 11 1.

13 In a modification of the first embodiment, a 14 charging nozzle or ring 60 may be located at the exit 5 of the mist generator 1 and adapted to either 16 charge or steer the discharged mist as desired.

17 This will provide some controllability over the 18 properties of the mist. The charging nozzle 60 can 19 be adapted to form different spray or mist patterns, for example, sections of the charging nozzle 60 may 21 not be charged, or may be blocked, as desired.

23 Alternatively, the charging means may be of the form 24 of a charging mesh 90, as shown in Fig. 2, which can be disposed in the working fluid conduit 3, the 26 transport fluid conduit 8, the mixing chamber 3A, 27 the charging nozzle 60, or at the exit 5.

29 Advantageously the charging mesh should be located at the location where the dispersed vapour/droplet 31 flow regime is formed, since this may aid the 32 atomisation mechanism.

2 Furthermore, the charging means may be of the form 3 of inner surfaces of the working fluid conduit 3, 4 transport fluid conduit 8, transport fluid nozzle 16, mixing chamber 3A, charging nozzle 60, or the 6 exit 5 of the conduit 2 being made of a suitable 7 material or surface coating, such as nylon, to help 8 generate a charge on the fluid passing therethrough 9 due to friction. In this circumstance, the inner surfaces may have protrusions 70, 80 or indentations 11 (not shown) to increase the surface wall boundary 12 area to promote charging of the fluid passing 13 therethrough, and hence increase charging and 14 turbulence.

16 Electro-static steering means 100, suitably formed 17 to be located around the circumference of the mixing 18 chamber 3A, may be used to control, in effect, the 19 geometry of the mixing chamber 3A in situ by suitably steering the charged atomised droplets 21 therein away or towards the steering means 100 as 22 desired.

24 In accordance with a second embodiment of the present invention, as shown in Fig. 3, a second 26 working fluid inlet 30, a second working fluid 27 conduit 32 and a working fluid nozzle 34 are 28 provided.

This second embodiment allows for an inlet fluid to 31 be introduced into passage 3. This inlet fluid can 32 be any fluid or mixture of fluids, for example a 1 liquid, gas, flowable solid, powder or slurry. The 2 inlet fluid may be a second working fluid to be 3 atomised or dispersed along with the working fluid 4 introduced into working nozzle 34; the inlet fluid could also be a non- flammable liquid or inert gas to 6 be atomised to aid fire suppression; or the inlet 7 fluid could be smoke in a room, which, by virtue of 8 the suction and turbulence created by the mist 9 generator 1 in the mixing chamber 3A, will help suck-in and mix the smoke with the working and 11 transport fluids to wet and disperse the smoke.

13 It is to be appreciated that any feature of the 14 first embodiment, including the charging means 50, 60, 70, 80, 90, and steering means 100, can also be 16 disposed in the second embodiment shown in Fig. 3.

18 The protrusions 80 when applied to the working 19 nozzle 34 and transport 16 may be of the form of a lip located at the exit of the nozzles 16, 34 to aid 21 atomisation. The lip may be annularly formed around 22 the nozzles 16, 34, or may be discreet lips spaced 23 apart about the exit of the nozzles 16, 34.

This second embodiment works in substantially the 26 same way as the first embodiment in that transport 27 fluid is injected into the mixing chamber 3A via 28 transport fluid nozzle 16. Working fluid is 29 injected into the mixing chamber 3A via working fluid nozzle 34, and an inlet fluid is introduced 31 into the mixing chamber 3A via the inlet 4 and 32 passage 3. The transport fluid will atomise the 1 working fluid and the inlet fluid as hereinbefore 2 described, and the dispersed vapour/droplet flow 3 regime formed will be discharge as a mist with 4 charged atomised droplets, by virtue of the charging means 50, 60, 70, 80, 90 applied to Fig. 3.

7 A third embodiment of the present invention, as 8 shown in Fig. 4, is similar to the second embodiment 9 shown in Fig. 3, except that the inlet 4 and passage 3 are blind, i.e. closed off.

12 This third embodiment works in substantially the 13 same way as the previous embodiments in that 14 transport fluid is injected into the mixing chamber 3A via transport fluid nozzle 16, and working fluid 16 is injected into the mixing chamber 3A via working 17 fluid nozzle 34. The transport fluid will atomise 18 the working fluid as hereinbefore described, and the 19 dispersed vapour/droplet flow regime formed will be discharge as a mist with charged atomised droplets, 21 by virtue of the charging means 50, 60, 70, 80, 90 22 applied to Fig. 4.

24 It is to be appreciated that any features of one embodiment or modification thereof may be combined 26 with any features or modifications of the other 27 embodiments to form new embodiments. For example, 28 the charging means 50, 60, 70, 80, 90, and steering 29 means 100 of the first embodiment, can also be disposed in the second and third embodiments shown 31 in Figs. 3 and 4.

1 Modifications and improvements may be made to the 2 present invention without departing from the scope 3 of protection.

Claims

CLAIMS: 1. An atomising apparatus for generating a mist or spray, the

apparatus comprising: a working fluid conduit adapted to supply a a transport fluid conduit adapted to supply a transport fluid; a mixing chamber in fluid communication with the working fluid and transport fluid conduits; a transport fluid nozzle in fluid communication with the transport fluid conduit and adapted to direct transport fluid into the mixing chamber, the transport fluid nozzle further adapted such that in use the transport fluid is directed towards a flow of working fluid in the mixing chamber to atomise the working fluid to form a dispersed vapour/droplet flow regime of atomised working fluid droplets; and a first electrostatic charging means located adjacent at least one of the transport fluid nozzle and mixing chamber and adapted to apply an electrostatic charge to the transport fluid flow and/or the atomised
2. The apparatus of Claim 1, further comprising a discharge nozzle downstream of the mixing chamber, the discharge nozzle adapted to vary the direction of the stream of atomised working fluid droplets.
3. The apparatus of Claim 2, wherein the discharge nozzle includes a second electrostatic charging means adapted to apply an electrostatic charge to the stream of atomised working fluid droplets.
4. The apparatus of any preceding claim, wherein the first electrostatic charging means comprises at least one inductance coil surrounding the transport fluid nozzle and/or mixing chamber.
5. The apparatus of Claim 4, wherein the first electrostatic charging means further comprises at least one electrode located in the transport fluid nozzle and/or mixing chamber.
6. The apparatus of any of Claims 1 to 3, wherein the first electrostatic charging means comprises at least one electrode located in the transport fluid nozzle and/or mixing chamber.
7. The apparatus of either Claim 5 or Claim 6, wherein the electrode is a mesh electrode.
8. The apparatus of any of Claims 1 to 3, wherein the electrostatic charging means comprises an electrostatic generating material forming part of the transport fluid nozzle and/or mixing chamber.
9. The apparatus of Claim 8, wherein the electrostatic generating material is nylon.
10. The apparatus of any preceding claim, wherein at least one of the transport fluid nozzle and mixing chamber includes one or more projecting members adapted to project into the fluid stream.
11. A method of generating a mist or spray comprising the steps of: supplying working fluid to be atomised into a mixing chamber; introducing a transport fluid into the mixing chamber via a transport fluid nozzle; directing the transport fluid into the stream of working fluid such that the working fluid is atomised by the transport fluid and a dispersed vapour/droplet flow regime is formed; applying a first electrostatic charge to at least one of the transport fluid and atomised working fluid; and discharging the atomised working fluid from the mixing chamber.
12. The method of Claim 11, further comprising the step of varying the direction of the atomised working fluid as it is discharged.
13. The method of either Claim 11 or Claim 12, further comprising the step of applying a second electrostatic charge to the atomised working fluid as it is discharged.
14. An atomising apparatus for generating a mist or spray as hereinbefore described with reference to the accompanying drawings.
15. A method of generating a mist or spray as hereinbefore described with reference to the accompanying drawings.