WO2004007085A1

WO2004007085A1 - Atomisation nozzle with rotating annular gap

Info

Publication number: WO2004007085A1
Application number: PCT/EP2003/007715
Authority: WO
Inventors: Herbert Hüttlin
Original assignee: Huettlin Herbert
Priority date: 2002-07-16
Filing date: 2003-07-16
Publication date: 2004-01-22
Also published as: ES2252697T3; DE50301819D1; EP1521639B1; CN100441310C; ATE311257T1; DE10232863A1; AU2003250968A1; JP2006501048A; DK1521639T3; CA2492299A1; EP1521639A1; CN1668383A

Abstract

An atomisation nozzle (10) comprises a flow channel (16) which is annular in cross-section, for the supply of a medium for atomisation, enclosed by two radially-separated walls (18, 30) and which opens out in an annular nozzle opening (40). Furthermore, a second flow channel (50), enclosing the first flow channel, is provided for supply of a gaseous spraying medium (65), which also opens out in an annular nozzle opening (54). According to the invention, the walls (18, 30) enclosing the first flow channel (16) may rotate relative to each other about a nozzle longitudinal axis (70).

Description

Atomizing nozzle with a rotating annular gap

The invention relates to an atomizing nozzle with a first flow channel with an annular cross section for guiding a medium to be atomized, which is delimited by two radially spaced walls and which opens into an annular nozzle opening, and with a second flow channel surrounding the first one for guiding one gaseous spray medium, which also opens into an annular nozzle opening.

BESTATIGUNGSKOPIE Such an atomizing nozzle is known for example from DE 197 49 071 AI. Such atomizing nozzles are used to spray a medium to be atomized, usually a liquid, sometimes also a powder, using a gaseous spray medium.

The medium to be atomized is transported under pressure through the annular or gap-shaped flow channel to an annular gap-shaped nozzle opening.

This first annular flow channel is surrounded by a second also annular flow channel and this also opens adjacent to the first flow channel in an annular or gap-shaped nozzle opening.

Depending on how the muzzle head of the nozzle is designed, such nozzles spray axially or more or less laterally out of the axial axis with an ever increasing spray angle, with spray angles of up to 180 ° and a wrap angle of 360 ° around the muzzle head.

Such nozzles are widely used in devices for treating particulate material, for example for granulating or coating these particles. When granulating, a sticky liquid is sprayed, which serves to glue the particles into larger agglomerates, i.e. the desired granules.

When coating a coating layer ^¬ is sprayed onto the surface. Such apparatuses are used primarily in the pharmaceutical industry, where tablet ingredients that are produced as fine dust powders are granulated into manageable powders, for example tablets that can be compressed into tablets.

When coating, pellets or finished granules or even whole tablets are provided with an outer coating layer.

Depending on the design of the device, the nozzles spray vertically upwards, that is to say they are designed as standing nozzles, spray at an angle, horizontally or, in some cases, vertically from top to bottom.

Such atomizing nozzles are used to spray suspensions, dispersions or solutions and these are also to be used in so-called "hot-melt" processes in which wax melts or hard fat are processed under the influence of heat.

In order to achieve the finest possible spraying, the annular flow channels work with liquid cross sections that are in the range of <0.25 mm.

In practical use of such spray nozzles, it has now been found that difficult suspensions or dispersions, due to undissolved solids content, can lead to partial blockages of the small liquid cross section.

This is particularly noticeable when these solids have a fibrous or crystalline character. If you take the example of the aforementioned nozzle with a spray angle of 180 ° or a wrap angle of 360 °, a spray cone in the form of a flat spray cake is sprayed from the nozzle head. If blockages now occur, no medium to be atomized escapes in certain circumferential areas of the annular gap. This has extremely negative effects on the treatment result which is to be achieved with an apparatus in which such an atomizing nozzle is arranged.

In a fluidized bed coater, for example, the material to be treated is swirled or moved around the nozzle, so that an irregular treatment result is then achieved in the case of a nozzle spraying unevenly due to blockages.

However, it is precisely the aim of this technology to achieve a treatment result that is as uniform as possible, for example to obtain granules in a very narrow grain size range or coating layers with the same possible coating thickness.

It is therefore an object of the present invention to further develop an atomizing nozzle of the type mentioned at the outset in such a way that media to be sprayed which tend to become blocked can be atomized uniformly.

According to the invention the object is achieved in that the walls surrounding the first flow channel are rotatable relative to one another about a longitudinal axis of the nozzle. are. It was found that with such a configuration of the gap-forming walls, a centrifugal and radial, ie toroidal movement occurs in the annular gap. The medium to be atomized, which is conveyed in the axial direction through the annular gap, is also set into a rotating movement by the walls rotating relative to one another, which results in the aforementioned toroidal movement. If media are now passed through such a flow channel, which tend to become blocked or which also carry small solid clumps, the rotary design of the liquid gap achieves a certain size reduction of such solid clumps, which would otherwise lead to a blockage of the liquid gap with standing walls. A kind of self-cleaning effect is achieved through the rotary configuration, so that ultimately the medium to be atomized leaves the annular nozzle opening in a uniformly distributed manner.

In a further embodiment of the invention, the two walls are also axially displaceable relative to one another, as a result of which the gap width of the nozzle opening of the first annular flow channel can be changed.

This measure now has the considerable advantage that it is possible to vary the gap width of the nozzle opening of this first flow channel and, in particular, also to close it due to the axial mobility. If the nozzle is not in use or is temporarily not in use, the nozzle opening is closed so that no contamination occurs or blockages occur in the region of the nozzle opening due to drying out or the like. A significant, considerable advantage of this axial displaceability is that the width of the annular gap is self-regulated over a certain bandwidth.

Conventional annular gaps in such atomizing nozzles have a width of 0.1 to about 0.25 mm, and it is desirable to be able to drive out 1 to 5 grams of medium to be sprayed per millimeter of length of the gap.

The axial mobility makes it possible, depending on the nature of the medium to be sprayed, that the gap height adjusts itself. If a certain medium is carried through the first flow channel at a certain pressure, intrinsic properties, for example in the case of a liquid, its viscosity, in the case of emulsions, its flowability and viscosity, exert a considerable influence on the amount that can pass through per millimeter of a gap. In other words, there are liquids that are relatively easy to drive out through such a gap, but others require a slightly wider gap for the same amount of discharge.

It has been found in practical use that, of course within a certain predetermined range, the gap width adjusts itself to an optimal value under given boundary conditions, that is to say the nozzle regulates itself.

The possibility mentioned at the beginning of closing the nozzle mouth of the first flow channel in the idle state can be achieved, for example, when the nozzle is at a standstill by that the at least one movable wall sags due to gravity and thereby the closing movement takes place.

In the case of angled, horizontal or even hanging nozzles, this movement can take place by means of a spring force or other mechanisms.

In a further embodiment of the invention, conveyor elements are arranged at least on one of the walls which can be rotated relative to one another and which control a movement of the medium to be atomized which is transported to the nozzle opening.

The provision of these conveying elements has the considerable advantage that the toroidal movement formed by the axial transport direction and the rotating walls is guided in a targeted manner by the conveying elements and is additionally conveyed.

In addition, these conveying elements can also serve as mechanical means in order to transport any lumps of solid that are carried along in a targeted manner and to crush them if necessary.

In one embodiment of the invention, one wall is stationary and the other wall is rotatable.

In terms of design, this measure has the advantage that only one of the two walls has to be moved, and accordingly only drive elements corresponding to these walls have to be present. In a further embodiment of the invention, one wall is stationary and the other wall is axially displaceable.

Here, too, there is the advantage of the simple structural design of the additional axial displaceability of the walls relative to one another.

In a further embodiment, the wall that is rotatable is also axially movable at the same time.

In terms of design, this measure has the advantage that the precautions of both the rotatability and the axial

Movability in connection with a single wall.

In a further embodiment of the invention, the axial mobility is controlled by the conveyed medium to be atomized itself.

This measure allows the aforementioned self-regulating effect of the gap width of the nozzle opening of the first flow channel.

In a further embodiment of the invention, the axial displaceability is designed such that the nozzle opening of the first flow channel is closed in the idle state.

This measure allows an extremely simple constructive manner the previously mentioned closing of the nozzle opening of the ^'first flow channel, and this just takes place when no to atomizing medium is passed through the first flow channel.

In a further embodiment of the invention, the axial displaceability takes place against a restoring force which moves the displaceable wall (s) into the closed position of the nozzle opening.

As already mentioned, gravity can be used as the restoring force, so that when the nozzles are stationary, the one movable wall is moved into the closed position by gravity relative to the other.

If the force of gravity is insufficient or is unable to carry out this movement, this can be done by other control elements, for example by springs or other elements.

In a further embodiment of the invention, the axially displaceability of the walls is designed such that the nozzle opening of the second flow channel is also closed in the idle state.

This measure has the advantage that both nozzle openings are closed in the idle state.

This measure not only has the advantage already mentioned that no contaminants can enter the nozzle, but also has the advantage that any residual medium quantities still present in the flow channels do not escape, so that such residues leak during transport or disassembly and cause contamination.

In a further embodiment of the invention, the rotatable wall carries a fan on the outside of a head of the atomizing nozzle, by means of which the head can be freed from any buildup in the region of the nozzle openings.

A problem that crops up again and again is the contamination of the muzzle head due to mostly uncontrolled secondary air movement, which occurs in the vicinity of the liquid or spray gap. Due to the high blow-out speed, negative pressure areas are formed, which attract vagabonded, sprayed liquid droplets and deposit them on the muzzle head. Therefore, there is an agglomeration or gradually build-up of dried solid from the sprayed liquid.

The provision of the fan now allows these critical areas to be kept free of such buildup. Thus, the rotatability of the wall according to the invention can not only be used to create optimal conditions inside the nozzle, but this rotating movement can at the same time be used to avoid buildup on the outside of the head.

In a preferred embodiment of the invention, the one wall is designed as the outside of a central spindle, which is rotatable. This measure has the constructive advantage that the rotating wall is created by a structurally simple means, namely the central spindle.

In a further embodiment of the invention, the conveyor elements are designed as impeller sections.

This measure has the advantage that a particularly uniform promotion of the movement of the medium to be sprayed is possible.

If the impeller sections are formed on the outside of the above-mentioned central spindle, on the one hand, it is extremely simple to construct and it is possible to achieve particularly favorable and targeted conveyance. The length and number of the impeller sections, that is the number of conveying wheels and their cross-sectional shape, can also be varied so that media which are particularly problematic to be sprayed can also be dealt with.

In a further embodiment of the. Invention, the spindle is driven by a pneumatically operated motor.

In terms of design, this measure has the advantage that a gaseous medium for spraying the medium to be sprayed will be passed through such a spray nozzle, that is to say it is connected to a source of spray air, usually compressed air. This means that parts of this air can also be used at the same time to operate the motor, which ensures the rotary movement between the walls. In a further preferred embodiment, the spindle is plugged onto a drive pin, which allows the spindle to move to a certain extent.

In terms of design, this measure has the particular advantage that both the spindle can be rotated and, to a certain extent, axially movable due to these dimensions.

The degree of mobility can be limited, for example, by a connecting cross pin that runs in an elongated hole in the drive pin.

In a further preferred embodiment of the invention, the fan sits on the head of the spindle.

This measure has the advantage that this advantageous embodiment is also realized on the central central spindle.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the specified combinations but also in other combinations or on their own without departing from the scope of the invention.

The invention is described and explained in more detail below on the basis of a few selected exemplary embodiments in conjunction with the accompanying drawings. Show it: 1 partially in longitudinal section a side view of a first embodiment of an atomizing nozzle according to the invention,

1 a is an enlarged view of the area delimited by a circle at the top right in FIG. 1,

2 is a side view of the atomizing nozzle of FIG. 2 rotated by 90 °,

Fig. 3 is a sectional view of Fig. 1 corresponding representation of another embodiment of an atomizing nozzle with a fan attached to the head, and

FIG. 4 shows an end view of the head of the atomizing nozzle from FIG. 3.

A spray nozzle shown in FIGS. 1 and 2 is designated in its entirety by reference number 10.

The atomizing nozzle 10 has an approximately rod-shaped nozzle body 12, on the one end of which, in the illustration of FIGS. 1 and 2, a motor 14 is flanged.

A first annular or annular flow channel 16 is formed in the nozzle body 12. This first flow channel 16 is delimited on the inside by an inner wall 18, which is the outside 20 of a central spindle 22.

The spindle 22 is attached to an upright square drive pin 24 of the motor 24 and has a corresponding slot 26 at its lower end.

This firstly provides a rotational connection between the motor 14 and the spindle 22, i.e. When the motor 14 is operating, the spindle 22 rotates about its central longitudinal axis 70, which also represents the central longitudinal axis of the atomizing nozzle 10.

The plug connection is such that there is also a certain axial mobility of the spindle 22, the meaning and purpose of which will be described later in connection with the mode of operation.

The axial mobility or the limitation of the amount of axial movement can be created in that an upstanding elongated hole is recessed in the drive pin, in which a transverse bolt is received, which is inserted in a radial bore of the spindle 22 in the region of the slot 26.

The first flow channel 16 is delimited on the outside by an outer wall 30, which is formed by an inside of a central, continuous central bore or opening 34 in the nozzle body 12. Both the spindle 22 and the nozzle body 12 expand opposite to the motor 14 like in a widening 36 or in a widening 38, as can be seen in particular from Fig. La.

An approximately horizontally oriented nozzle opening 40 is therefore formed in the form of an annular gap 42 which extends around 360 °.

The width of the annular gap 42 can be changed due to the axial mobility of the spindle 22, the change being in the range between 0.1 mm and 0.25 mm.

The first flow channel 16, as can be seen in particular from FIG. 2, is connected to a lateral connector 44, so that a medium to be atomized, for example a liquid 45, is fed through the first flow channel 16 into the first flow channel 16 via this connector 44 transported through and can exit through the annular gap 42. The transport and conveyance of this liquid 45 is additionally promoted by conveying elements 48 in the form of two impeller sections 46 and 46 'on the outside 22 of the spindle 22, the height of an impeller being such that it is approximately the gap width of the first flow channel 16 inside the atomizing nozzle 10 corresponds.

In the illustrated embodiment, the profile of the impeller 46 is such that it lies approximately flat against the inside 32 of the central opening 34, other profiles are of course also possible, for example rounded or pointed impeller profiles. In order to finely atomize the liquid emerging through the annular gap 42 or the medium to be atomized, which can also be a powder. a second flow channel 50 is provided.

This second flow channel 50 surrounds the first inner flow channel 16 and opens in a widening 52 in the same direction in a nozzle opening 54, which likewise has the shape of an annular gap 56. The annular gap 56 is arranged such that it lies directly adjacent to the annular gap 42, in the illustrated embodiment of the standing atomizing nozzle 10 directly below the first annular gap 42. The second flow channel 50 is delimited on the inside by the nozzle body 12 and on the outside by a rotatable sleeve 58 The sleeve 58 is screwed into the nozzle body 12 via a thread 60.

The sleeve 58 is provided on its outside, as can be seen in particular in FIG. 2, with a scale 62.

The gap width of the annular gap 54 can consequently be changed by rotating the sleeve 58.

The second flow channel 52 is connected to the outside world via a radially projecting connection piece 64, via which a gaseous medium in the form of spray air 65 is introduced into the nozzle body 12.

The motor 14 is designed as a pneumatically operated motor, ie compressed air 67 is introduced through an inlet 66 and this compressed air 67 is discharged again through an outlet 68. In operation, the motor 14 is controlled and driven by the aforementioned compressed air so that the spindle 22 rotates. The speed depends on the respective application of the medium to be sprayed and can be in the range of 1 to 1000 revolutions per minute. A medium to be sprayed, for example a sticky liquid to be sprayed for granulation, is conveyed via the nozzle 44 and pressed out via the annular gap 42. The liquid can also consist of an externally melted substance.

This squeezed-out liquid is sprayed into a fine mist by the spray air 65 emerging from the second flow channel 50 or from its nozzle opening 54, the spray air usually being under a pressure of 0.5 to 5.0 bai.

This results in a correspondingly horizontally oriented spray cake or a corresponding spray cone, as is indicated in FIG. 2 by the reference number 75.

As previously mentioned, the gap width of the annular gap 56 from which the spray air emerges can be changed by the rotatable sleeve 58.

The gap width of the annular gap 42, from which the liquid 45 to be sprayed emerges, regulates itself due to the axial mobility of the spindle 22, on the one hand through the predetermined liquid pressure of the liquid to be sprayed and to a certain extent through the intrinsic properties of the liquid, that is, their viscosity or their nature as an emulsion, slurry or powder mixture. If the atomizing nozzle 10, as shown in FIG. 1, is designed as a standing nozzle and no more medium to be sprayed is supplied, the spindle 22 sinks downward due to the force of gravity and automatically closes the annular gap 42 or the first flow channel 46, as indicated by the double arrow in FIG.

From Fig. 1 it can be seen that the spindle 22 is closed on its outside by an approximately mushroom-shaped head 80.

In practical use, it was found, as is indicated in FIG. 2, that an area 88 of the outer edge of the head 80 has certain problem areas, in which gradually sprayed particles or else solid particles floating around in a fluidized bed apparatus accumulate. This area is indicated in FIG. 2 with the reference number 88.

3 and 4, an embodiment variant is shown which, as far as the design of the atomizing nozzle as such is concerned, is the same as the exemplary embodiment described in connection with FIGS. 1 and 2.

A fan 82 is additionally mounted on the outside of the head 80.

This fan 82 has a plurality of centrifugal fan blades 84 which are curved backwards and which suck in air from an axial tube 86 and, as can be seen in particular from the arrow 89 in the top view of FIG. 4, blow out this air radially. As a result, the critical region designated by reference number 88 in FIG. 2 is continuously blown free, so that none undesirable build-up or accumulation of solid or liquid particles.

This air additionally blown out by the fan 82 can additionally be used to accompany the spray cone 75 shown in FIG. 2 on its upper side, that is to say to either control it, to swirl it or to use it for other purposes.

Depending on where the air drawn in through the axial tube 86 comes from, it can also be used as a "microclimate", for example in the form of hot air, in order to keep the liquid droplets supplied as a melt in the molten state for as long as possible, so that those particles which to be sprayed through the spray nozzle, are still fogged with liquid particles even at a certain distance from the nozzle.

In the exemplary embodiment described above, one, namely the outer wall 30, of the first flow channel 16 was standing, the inner wall 18, namely the outer side 20 of the spindle 22, was rotatable.

It is also conceivable to carry out this kinematically in reverse or, if necessary, to set both walls in rotary motion.

Claims

claims

1. atomizing nozzle, with a first, in cross-section annular flow channel (16) for guiding a medium to be atomized (45) through two of them radially

• spaced walls (18, 30) and which opens into an annular nozzle opening (40), and with a second, the first (16) surrounding flow channel (50) for guiding a gaseous spray medium (65), which also in an annular Nozzle opening (54) opens, characterized in that the walls (18, 30) delimiting the first flow channel (16) can be rotated relative to one another about a longitudinal axis (70) of the nozzle.

2. Atomizing nozzle according to claim 1, characterized in that the two walls (18, 30) are also axially displaceable relative to one another, so that the gap width of the nozzle opening (40) is variable.

3. Atomizing nozzle according to claim 1 or 2, characterized in that on at least one of the relatively rotatable walls (30) conveying elements (48) are arranged which control a movement of the medium to be atomized (45) transported to the nozzle opening (40).

4. Atomizing nozzle according to one of claims 1 to 3, characterized in that the one wall (30) is stationary and that the other wall (18) is rotatable.

5. atomizing nozzle according to one of claims 2 to 4, characterized in that the one wall (30) is stationary and that the other wall (18) is axially displaceable.

6. Atomizing nozzle according to one of claims 2 to 5, characterized in that that wall (30) which is rotatable is also axially movable at the same time.

7. atomizing nozzle according to one of claims 2 to 4, characterized in that the control of the axial mobility is carried out by the conveyed medium to be atomized (45).

8. Atomizing nozzle according to one of claims 2 to 7, characterized in that the axial displacement is designed such that the nozzle opening (40) of the first flow channel (16) is closed in the idle state.

9. Atomizing nozzle according to one of claims 2 to 8, characterized in that the axial displacement takes place against a restoring force which moves the displaceable wall (s) into the closed position of the nozzle opening.

10. Atomizing nozzle according to one of claims 2 to 9, characterized in that the axial displaceability is designed such that in the idle state also the nozzle opening (54) of the second flow channel (50) is closed.

11. Atomizing nozzle according to one of claims 1 to 10, characterized in that the rotatable wall on the outside of a head (80) of the atomizing nozzle (10) one Fan (82) carries through which the head (80) in the area of the nozzle openings (40, 54) can be freed from any buildup.

12. Atomizing nozzle according to one of claims 1 to 11, characterized in that the one wall (18) as the outside (20) of a central spindle (22) is formed, which is rotatable.

13. Atomizing nozzle according to one of claims 3 to 12, characterized in that the conveying elements (48) are designed as impeller sections (46, 46 ').

14. Atomizing nozzle according to claim 12 or 13, characterized in that the spindle (22) is driven by a pneumatically operable motor (40).

15. Atomizing nozzle according to claim 14, characterized in that the spindle (22) on a drive pin (24) of the motor (14) is plugged, which allows a certain axial mobility of the spindle (22).

16. Atomizing nozzle according to one of claims 11 to 15, characterized in that the fan (82) sits on a head (80) of the spindle (22).