Apparatus and method for producing aerosol and a focusing part

Abstract

The present invention relates to an apparatus and method for producing aerosol. The apparatus comprising a first atomizer for producing a first aerosol jet and a second atomizer for producing a second aerosol jet, each atomizer comprising an atomizing head in which the liquid is atomized into an atomized aerosol jet. Said atomizers further comprise a focusing part arranged to restrain the atomized aerosol jet for providing a punctual aerosol jet, said focusing part extending directly from the atomizing head. The first and second atomizer form an atomizer pair such that the atomizers are aligned towards each other for colliding the aerosol jets to each other.

Claims

1. An apparatus for producing aerosol, the apparatus comprising: a first atomizer for producing a first aerosol jet and a second atomizer for producing a second aerosol jet, said aerosol jets are produced from one or more liquid precursors and discharged from a respective atomizer through a discharge opening in the atomizer, wherein each atomizer comprises an atomizing head in which the liquid is atomized into an atomized aerosol jet, each atomizing head is directly connected to a tubular focusing part arranged to restrain the atomized aerosol jet for providing a punctual aerosol jet, wherein said tubular focusing part is formed of a choked flow part in which one or more flow restraints project from the inner surface of the tubular focusing part to change the hydrodynamic properties of the atomized aerosol jet discharged from the atomizing head into the choked flow part in a manner that reduces the average drop size of the aerosol jet, and a levelling part without projecting flow restraints on the inner surface of the tubular focusing part, and said levelling part has a length of at least ten times the inner diameter of the focusing part in the levelling part, said first and second atomizer form an atomizer pair such that the atomizers are aligned towards each other for colliding the aerosol jets to each other, the first and the second atomizer are arranged in a substantially vertical direction such that the aerosol formed in the collection of the aerosol jets forms a substantially horizontal aerosol plane when escaping from the collision point.

2. The apparatus according to claim 1, wherein the focusing part has means for restraining the atomized aerosol jet such that a total opening angle of the punctual aerosol jet is less than 10.

3. The apparatus according to claim 1, wherein distance between the discharge openings in the opposing atomizers is in a range of 0.5-15 mm.

4. The apparatus according to claim 1, wherein distance between the discharge openings in the opposing atomizers is in a range of 1-10 mm.

5. The apparatus according to claim 1, wherein one or more flow restraints are arranged in the choked flow part such that they are placed in succession, adjacently or in a corresponding manner with respect to each other.

6. The apparatus according to claim 1, wherein the first and the second atomizer are arranged coaxially.

7. The apparatus according to claim 1, wherein the first and the second atomizer are arranged in the vertical direction such that the discharge openings of the atomizers are arranged substantially coaxially in a deposition chamber.

8. The apparatus according to claim 1, wherein the atomizer is a gas-dispersing atomizer for atomizing liquid into aerosol by means of gas at the atomizing head of the atomizer and comprises at least one liquid conduit for feeding at least one liquid to be atomized into the atomizing head and at least one gas conduit for feeding at least one gas into the atomizing head for atomizing the liquid.

9. The apparatus according to claim 1, wherein the first and the second atomizer are in a deposition chamber.

10. The apparatus according to claim 7, wherein the first and the second atomizer are in a central region of said deposition chamber such that there is free space around said first and said second atomizer.

11. A method for producing aerosol, said method comprising the steps of: arranging a first atomizer and a second atomizer opposite to each other such that a discharge opening of the first atomizer is opposite to a discharge opening of the second atomizer, said first and second atomizer comprising an atomizing head for atomizing an aerosol jet, atomizing at least one liquid precursor into a first atomized aerosol jet in the first atomizing head and into a second atomized aerosol jet in the second atomizing head, restraining the first atomized aerosol jet and the second atomized aerosol jet respectively into a first punctual aerosol jet and a second punctual aerosol jet in a tubular focusing part that extends directly from the atomizing head, the focusing part being formed of a choked flow part in which one or more flow restraints project from the inner surface of the tubular focusing part to change the hydrodynamic properties of the atomized aerosol jet discharged from the atomizing head into the choked flow part in a manner that reduces the average drop size of the aerosol jet, and a levelling part without projecting flow restraints on the inner surface of the tubular focusing part, wherein said levelling part has a length of at least ten times the inner diameter of the focusing part in the levelling part, discharging said punctual aerosol jets from the discharge openings of the atomizers such that the punctual aerosol jets coming out from the discharge openings are directed substantially directly towards each other in such a manner that the first and the second punctual aerosol jets collide directly into each other in a collision point, bringing said at least one liquid into the first and the second atomizer in such a pressure that the first and the second punctual aerosol jets when colliding each other in the collision point form aerosol which escapes horizontally from the collision point.

12. The method according to claim 11, wherein the method further comprising the step of arranging the first and the second atomizer in a substantially vertical direction such that the aerosol formed in the collision of the aerosol jets forms a substantially horizontal aerosol plane when escaping from the collision point.

13. The method according to claim 12, wherein the method further comprising the step of arranging a substrate to be coated parallel to the substantially horizontal aerosol plane such that the substrate is coated by said aerosol plane falling under gravity.

14. The method according to claim 11, wherein the method further comprises a step of arranging the atomizers and the substrate to be coated in the same deposition chamber.

15. A focusing part for an atomizer, which said atomizer comprises an atomizing head for producing an atomized aerosol jet from one or more liquid precursors, wherein the focusing part: is a tube formed of a choked flow part in which one or more flow restraints project from the inner surface of the tubular focusing part to change the hydrodynamic properties of the atomized aerosol jet discharged from the atomizing head into the choked flow part in a manner that reduces the average drop size of the aerosol jet, and a levelling part without projecting flow restraints on the inner surface of the tubular focusing part, wherein said levelling part has a length of at least ten times the inner diameter of the focusing part in the levelling part, is arranged to extend directly from the atomizing head and is arranged to restrain the atomized aerosol jet for providing a punctual aerosol jet, comprises a discharge opening for discharging the punctual aerosol jet.

16. The focusing part according to claim 15, wherein the levelling part comprises a section having a smaller inner diameter than the inner diameter of the rest of the levelling part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

(2) FIG. 1 shows a schematic side view of the apparatus according to the invention, in which two atomizers are oriented substantially directly against each other in a vertical direction;

(3) FIG. 2 shows a detail of FIG. 1;

(4) FIG. 3a shows one embodiment of the focusing part according to the invention;

(5) FIG. 3b shows another embodiment of the focusing part according to the invention; and

(6) FIG. 3c shows yet another embodiment of the focusing part according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows an apparatus according to the invention for producing aerosol. Side view of the apparatus shows two atomizers 1, 2, which are oriented substantially towards one another and fixed to a body of the apparatus. The first and the second atomizer 1, 2 are preferably arranged substantially coaxially opposite one another in such a manner that aerosol jets 6a, 6b (shown in FIG. 2) thereof collide substantially directly against each other. The FIG. 1 shows one pair of atomizers 1, 2 but the apparatus may comprise more atomizers as well. The atomizers 1, 2 are preferably arranged in pairs for constituting one or more atomizer pairs in such a manner that the atomizers 1, 2 of each atomizer pair are oriented substantially directly, preferably coaxially, towards each other, whereby the aerosol jets 6a, 6b of each atomizer pair collide directly into each other. The atomizers 1, 2 are arranged in a deposition chamber 10 such that the atomizer pair is arranged preferably in the central region of said chamber 10. The first and the second atomizer 1, 2 are arranged in a vertical direction such that the discharge openings 8a, 8b (shown in FIG. 2) of the atomizers 1, 2 are arranged substantially coaxially in a deposition chamber such that the discharge openings are toward each other. So the first atomizer 1 has a discharge opening toward to the bottom of the deposition chamber 10 and the second atomizer 2 has an opening toward the top of the deposition chamber 10. The discharge openings of the first and the second atomizer 1, 2 are close to each other, the distance between the discharge openings in the opposing atomizers 1, 2 is in a range of 0.5-15 mm, and more preferably in a range of 1-10 mm. The most preferable distance between the discharge openings of the opposing atomizers is from 2-5 mm. The closer the discharge openings are to each other the flatter is the aerosol plane escaping from the collision point C (shown in FIG. 2) in which the aerosol jets discharged from the atomizers 1, 2 collide to each other. Respectively the further away the discharge openings are from each other the more fan-like is the aerosol plane. Liquid to be atomized and atomizing gas are fed to the atomizers 1, 2. The liquid is atomized in the atomizing head of the atomizer 1, 2 and aerosol jets are discharged from the first and the second atomizer 1, 2. The aerosol jets 6a, 6b from opposite atomizers 1, 2 collide with each other, whereby aerosol, composed of very small droplets is produced. In the method of producing aerosol the at least one liquid is brought into the first and the second atomizer 1, 2 in such a pressure that the first and the second aerosol jets 6a, 6b when colliding each other in the collision point C (in FIG. 2) form aerosol which escapes from the collision point. The aerosol formed in the collision point C (in FIG. 2) escapes from the collision point C (in FIG. 2) such that it forms a plane which is substantially horizontal. The horizontal aerosol spreads out uniformly in the radial direction on a plane which is perpendicular to the direction of the aerosol jets inside the deposition chamber 10. In other words after collision of the opposite aerosol jets 6a, 6b a disc-like aerosol flux is formed which escapes from the collision point C (in FIG. 2) radially. The aerosol does not therefore have a specific direction but it spreads out radially along a plane near the collision point of the aerosol jets 6a, 6b. When said atomization is observed visually the aerosol generated in the collision resembles a round thin disc consisting of aerosol and having a centre between the two atomizers. The aerosol is moved toward the substrate 11 to be coated in the bottom part of the deposition chamber 10 by the help of gravity. So the main movement of the aerosol is caused by the gravity outside the vicinity of the atomizers. Aerosol mainly spreads out in the deposition chamber 10 toward the substrate 11 to be coated which is in the bottom part of the chamber 10 but some of the aerosol may also spread on the upper part of the deposition chamber 10 so preferably a suction or similar arrangement is arranged in the upper part of the chamber 10 to collect the excess of the aerosol so as to recycle the precursor material to be used again in the coating process. Another embodiment of the invention is to arrange suction or other similar arrangement to remove excess of the aerosol in the bottom part of the deposition chamber. The precursor liquid that is deposited as part of the aerosol on the bottom of the deposition chamber or on the walls is transferred by gravity on the bottom of the deposition chamber wherefrom it can be removed as a liquid. It is very advantageous to collect said liquid because the precursors may be expensive. Excess aerosol can be collected also in the bottom part of the chamber 10 if the substrate 11 is arranged such that it does not cover all of the bottom part of the chamber 10 and that some of the aerosol moves beyond the substrate 11. The location that is shown in more detail in FIG. 2 is presented with letter A in FIG. 1.

(8) In FIG. 2 a detail of FIG. 1 is shown in which the first and the second atomizer 1, 2 are arranged coaxially in a vertical direction such that the discharge openings 8a, 8b of the atomizers 1, 2 are arranged coaxially along an imaginary vertical line in a deposition chamber. The atomizer 1, 2 is a gas-dispersing atomizer for atomizing liquid into aerosol by means of gas at the atomizing head 3 of the atomizer 1, 2 and comprises at least one liquid conduit for feeding at least one liquid to be atomized into the atomizing head 3 and at least one gas conduit for feeding at least one gas into the atomizing head 3 for atomizing the liquid (these are not shown in figure). The apparatus may be accomplished in a manner allowing the same or a different liquid to be fed to two or more atomizers 1, 2. In other words, the same or a different liquid may be fed to the atomizers 1, 2 of each atomizer pair, when desired.

(9) The atomizers 1, 2 further comprise a focusing part 9 arranged to restrain the atomized aerosol jet for providing a punctual aerosol jet, said focusing part extending directly from the atomizing head 3 and having the discharge opening 8a, 8b. According to one embodiment of the invention the focusing part 9 is a choked flow part 4 in which one or more flow restraints 5 are arranged to change the hydrodynamic properties of the aerosol jet being discharged from the atomizing head 3 into the focusing part 9 which is the choked flow part 4 in a manner reducing the average drop size of the aerosol jet, the choked flow part 4 extending directly from the atomizing head 3. The choked flow part 4 extends from the atomizing head 3 directly such that when the aerosol jet 6a, 6b is discharged from the atomizing head 3 to the choked flow part 4 it instantly arrives to the choked flow part 4 after leaving the atomizing head 3. The FIG. 2 shows an embodiment in which both of the atomizers 1, 2 comprise a choked flow part 4 although it is possible that only one of the atomizers comprise the choked flow part 4 or none of the atomizers 1, 2 comprise it. In the choked flow part 4 one or more flow restraints 5 are arranged such that they are placed in succession, adjacently or in a corresponding manner with respect to each other. So an average drop size of the aerosol jet is reduced by arranging a choked flow part 4 to at least one of the atomizers 1, 2 such that before being discharged through the discharge opening 8a, 8b the atomized liquid is arranged to go through said choked flow part 4. A detail in FIG. 2 shows a total opening angle of the aerosol jet discharged from the atomizing head 3. The total opening angle is less than 10.

(10) FIG. 3a shows an embodiment of the focusing part 9 according to the invention in which the focusing part 9 is a choked flow part 4 which comprises a levelling area 13 between the discharge opening 8a, 8b and the nearest flow restraint to the discharge opening 8a, 8b for levelling the punctual aerosol jet. Although the focusing part 9 has a minimum length of at least ten times the inner diameter of the focusing part a preferable length for the levelling area 13 is at least ten times the inner diameter of the focusing part 9 in the levelling area 13. This means that in this embodiment the choked flow part 4 may be short or at least shorter than the levelling area 13 or the length of the total focusing part 9 is more. The preferable length of the levelling area 13 applies also to other embodiments of the focusing part 9.

(11) FIG. 3b shows a focusing part 9 according to another embodiment of the invention in which the focusing part 9 is substantially a tubular, round part after the atomizing head 3 in the direction of the aerosol flow. The length of the focusing part 9 is at least 10, preferably 15 the inner diameter of the focusing part 9. In the embodiment of the invention shown in FIG. 3b the focusing part 9 comprises a choked flow part 4 in which one or more flow restraints 5 are arranged to change the hydrodynamic properties of the aerosol jet being discharged from the atomizing head 3 into the choked flow part 4 in a manner reducing the average drop size of the aerosol jet. The choked flow part 4 comprises after the flow restraints 5 in the direction of the aerosol flow a tubular levelling area 13 between the discharge opening 8a, 8b and the nearest flow restraint to the discharge opening 8a, 8b for levelling the punctual aerosol jet, the levelling area 13 comprising a section 12 having a smaller inner diameter than the inner diameter of the rest of the levelling area 13. The section having a smaller inner diameter than the inner diameter of the rest of the levelling area 13 is preferably arranged nearer to the flow restraints 5 than to the discharge opening 8a, 8b.

(12) FIG. 3c shows another embodiment of the focusing part 9 according to the invention in which the focusing part 9 is a tubular part comprising a section 12 for restraining the atomized aerosol jet. The section 12 has a smaller inner diameter than the inner diameter of the rest of the tubular part. The tubular part comprises after the section 12 for restraining the atomized aerosol jet a levelling area 13 before the aerosol jet is discharged through the discharge opening 8a, 8b. In the method of the present invention for producing aerosol, one or more liquids are atomized into two or more aerosol jets 6a, 6b. The aerosol jet 6a, 6b itself may constitute aerosol. In accordance with the invention, at least two aerosol jets 6a, 6b are directed substantially directly towards each other in a manner making the aerosol jets 6a, 6b collide directly into each other. Two aerosol jets 6a, 6b are preferably directed substantially coaxially towards one another in a manner making the aerosol jets 6a, 6b collide substantially directly against one another. Coaxial means that the aerosol jets 6a, 6b move substantially coaxially directly towards one another, and thus the angle of collision between the aerosol jets 6a, 6b is about 180 degrees.

(13) The first and the second atomizer 1, 2 are arranged in a vertical direction such that the aerosol formed from the collision of the aerosol jets 6a, 6b forms a horizontal aerosol plane when escaping from the collision point C. The substrate 11 to be coated is arranged in the deposition chamber 10 such that the surface to be coated is parallel to the aerosol plane which is substantially horizontal such that the substrate 11 is coated by said aerosol plane falling under gravity.

(14) It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.