JP4548216B2 - Spray board, spray device and spray dryer - Google Patents

Description

  The present invention relates to a spray plate used in a centrifugal spray device, a spray device using the spray plate, and a spray dryer using the spray device.

  Conventionally, fluids such as medicines and foodstuffs, and stock solutions such as ceramic slurries are sprayed into high-temperature gas in the form of droplets using a spray disc or pressurized nozzle, and instantly dried and solidified to form particles. Spray dryers are generally known. Such a spray dryer has a feature that the processing such as filtration and separation of the stock solution and mechanical concentration can be omitted when the stock solution is granulated, and in many cases, spherical particles can be obtained.

Among such spray dryers, a spray dryer having a spray disc is disclosed in, for example, Patent Document 1 below. As shown in FIGS. 7A and 7B, the spray disc 80 described in this document has a conical shape between an upper mounting disc 82 and a lower mounting disc 83 that constitute the upper and lower mounting discs 81. The spraying roller 84 having a shape is arranged. A through hole 82a having a circular cross section in which a stock solution supply pipe 86 for supplying a stock solution is disposed is formed in the central portion of the upper mounting disc 82.
When spraying the stock solution using this spray plate 80, the stock solution is supplied from the top mounting disc 82 side to the top and bottom mounting disc 81 rotating at high speed through the through hole 82a through the stock solution supply pipe 86. Do it. Then, the undiluted solution flows in the peripheral direction of the upper and lower mounting disk 81 by centrifugal force. When the stock solution reaches the spraying roller 84 disposed on the periphery of the upper and lower mounting disk 81, the stock solution rises along the peripheral surface 84a of the spraying roller 84 and is sprayed in the form of droplets.
JP 9-131550 A

  Here, the internal atmospheric pressure of the upper and lower mounting disk 81 rotated at a high speed is lower than the atmospheric air pressure (that is, a negative pressure state). Therefore, a large amount of air containing fine particles floating around the spray disk 80 (hereinafter referred to as floating particles) is passed through the through holes 82a of the upper mounting disk 82 to the upper and lower mounting disks 81 from FIG. It flows in through the inflow path of the arrow R in (a). When the suspended particles are combined with the droplets sprayed from the spray board 80, particles having the adhered suspended particles are formed as shown in the photograph of FIG. As a result, when particles having a desired particle diameter are to be produced, a situation may occur in which the particle diameter of each particle is measured to be larger than the actual particle diameter.

  Accordingly, the present invention has been made to solve the above-described problems, and provides a spray disc, a spray device, and a spray dryer that are capable of suppressing adhesion of suspended particles to droplets to be sprayed. Objective.

  The spray disk according to the present invention comprises an upper and lower mounting disk having an upper mounting disk and a lower mounting disk, and a plurality of substantially conical spraying rollers arranged along a substantially peripheral edge between the upper and lower mounting disks. A through hole is formed in the central portion of the upper mounting disk of the upper and lower mounting disks, and a wall portion standing up to surround the through hole is formed on the upper surface of the upper mounting disk. It is characterized by.

  In this spray disc, when the stock solution is supplied to the upper and lower mounting discs through the through holes formed in the upper mounting disc, the stock solution flows in the peripheral direction of the upper and lower mounting discs and is applied to the peripheral surface of the spray roller. It rises along and becomes a film. After becoming a film, the stock solution becomes droplets and leaves the peripheral surface of the spraying roller, and is sprayed outward from the upper and lower mounting disks. When the inside of the upper and lower mounting disks is in a negative pressure state, the air around the spraying plate flows into the upper and lower mounting disks from the through hole of the upper mounting disk. Since the wall portion is erected so as to surround the through hole, the flow of air toward the through hole is blocked by the wall portion. Thereby, the amount of air flowing into the upper and lower mounting disks is suppressed. Therefore, when airborne particles are present around the spraying plate, the suction of the airborne particles into the upper and lower mounting discs is suppressed, and there is a situation where the airborne particles adhere to droplets sprayed from the spraying plate. It is suppressed.

  The spray device according to the present invention includes an upper and lower mounting disk having an upper mounting disk and a lower mounting disk, and a plurality of substantially conical spraying rollers disposed along a substantially peripheral edge between the upper and lower mounting disks. The spray plate, the rotary shaft that is located above the spray plate and rotates the upper and lower mounting discs of the spray disc, and the stock solution supply means for supplying the stock solution from the upper mounting disc side to the upper and lower mounting discs are accommodated. And a through hole in which the stock solution supplying means is disposed is formed in the central portion of the upper mounting disk of the upper and lower mounting disks of the spray disk, and the upper surface of the upper mounting disk has a through hole. A wall portion erected so as to surround the hole and along the outer surface of the casing is formed.

  In this spraying device, when the stock solution is supplied to the upper and lower mounting discs through the through holes formed in the upper mounting disc, the stock solution flows in the peripheral direction of the upper and lower mounting discs and is applied to the peripheral surface of the spray roller. It rises along and becomes a film. After becoming a film, the stock solution becomes droplets and leaves the peripheral surface of the spraying roller, and is sprayed outward from the upper and lower mounting disks. When the inside of the upper and lower mounting disks is in a negative pressure state by being rotated by the rotating shaft, the air around the spraying plate flows into the upper and lower mounting disks from the through hole of the upper mounting disk. Since the wall portion is erected on the upper surface of the mounting disk so as to surround the through hole and along the outer surface of the casing, the flow of air toward the through hole is blocked by the wall portion. Thereby, the amount of air flowing into the upper and lower mounting disks is suppressed. Therefore, when airborne particles are present around the spraying plate, the suction of the airborne particles into the upper and lower mounting discs is suppressed, and there is a situation where the airborne particles adhere to droplets sprayed from the spraying plate. It is suppressed.

  The spray dryer according to the present invention includes an upper and lower mounting disk having an upper mounting disk and a lower mounting disk, and a plurality of substantially conical spray rollers disposed along a substantially peripheral edge between the upper and lower mounting disks. A spray plate having a position above the spray plate, rotating a rotary shaft for rotating the upper and lower mounting discs of the spray disc, and a raw solution supply means for supplying the stock solution to the upper and lower mounting discs from the upper mounting disc side. And a gas supply means for supplying high-temperature gas for heating and drying the stock solution sprayed from the spraying plate to the spray drying chamber. A through hole in which the stock solution supplying means is arranged is formed at the center of the upper mounting disk of the plate, and the upper surface of the upper mounting disk surrounds the through hole and follows the outer surface of the casing. An upright wall portion is formed.

  In this spray dryer, when the stock solution is supplied to the upper and lower mounting discs through the through holes formed in the upper mounting disc, the stock solution flows in the peripheral direction of the upper and lower mounting discs, and the peripheral surface of the spray roller It rises along and becomes a film shape. After becoming a film, the stock solution becomes droplets and leaves the peripheral surface of the spraying roller, and is sprayed outward from the upper and lower mounting disks. When the inside of the upper and lower mounting disks is in a negative pressure state by being rotated by the rotating shaft, the air around the spraying plate flows into the upper and lower mounting disks from the through hole of the upper mounting disk. Since the wall portion is erected on the upper surface of the mounting disk so as to surround the through hole and along the outer surface of the casing, the flow of air toward the through hole is blocked by the wall portion. Thereby, the amount of air flowing into the upper and lower mounting disks is suppressed. Therefore, when airborne particles are present around the spraying plate, the suction of the airborne particles into the upper and lower mounting discs is suppressed, and there is a situation where the airborne particles adhere to droplets sprayed from the spraying plate. It is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the spray disc | board, the spray apparatus, and the spray dryer in which suppression of attachment of the floating particle to the droplet to be sprayed was achieved is provided.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that are considered to be best for carrying out a spray disc, a spray device, and a spray dryer according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

  In FIG. 1, the schematic block diagram of the spray dryer 10 which concerns on embodiment of this invention is shown. The spray dryer 10 is for obtaining fine spherical particles from a raw liquid by spraying the raw liquid, which is a ceramic slurry or the like, in the form of liquid droplets and drying and solidifying the liquid liquid in the form of liquid droplets. Also called spray dryer. The spray dryer 10 supplies hot air (that is, high-temperature gas) into the spray drying chamber 12 from the periphery of the spray drying chamber 12, the spray device 14 provided at the top of the spray drying chamber 12, and the periphery of the spray device 14. Gas supply means 16.

  The spraying device 14 further includes a housing 42 having two bearings 40A and 40B and holding the rotating shaft 32, and integrally accommodates the housing 42 and the stock solution supply pipe 36, and gradually decreases in diameter toward the lower side. A funnel-shaped casing 44 and a motor cover 46 for covering the motor 30 and catching the entire spraying device 14. The casing 44 has a variable diameter portion 48 on the upper end side that is gradually reduced in diameter, and a uniform diameter portion 49 on the lower end side that has a cylindrical shape, and the uniform diameter portion 49 is in the axial direction of the rotary shaft 32. It extends to.

  In the spray device 14 having such a configuration, by driving the motor 30, the rotating shaft 32 rotates and the spray disc 34 attached to the rotating shaft 32 rotates. Then, when the stock solution is supplied from the stock solution supply pipe 36 to the rotating spray plate 34, the liquid droplets of the stock solution from the spray plate 34 are aligned along the horizontal direction due to the centrifugal force accompanying the rotation of the spray plate 34 (FIG. 3). In the direction of arrow A). The sprayed droplets are instantly dried and solidified in the spray drying chamber 12 shown in FIG. 1 to become particles, most of which sinks and is collected in the collection pocket 18 at the bottom of the spray drying chamber 12, A part of it is conveyed to hot air, passes through the exhaust port 20 and is collected by the cyclone 24.

  Next, the structure of the spray board 34 mentioned above is demonstrated in detail, referring FIG.3 and FIG.4. As shown in FIG. 3, the spray disc 34 has an upper and lower mounting disk 50 that is orthogonal to the rotation shaft 32. The upper and lower mounting disks 50 are constituted by an upper mounting disk 52 and a lower mounting disk 54 arranged in parallel, and a plurality of connecting shafts 56 that connect the upper mounting disk 52 and the lower mounting disk 54. ing.

  A nut portion 58 for screwing with the rotary shaft 32 is formed at the center of the lower mounting disc 54, and the lower mounting disc 54 and the rotary shaft 32 are coupled to each other at the nut portion 58 to form a cap nut. By fastening at 60, the upper and lower mounting disks 50 and the rotary shaft 32 rotate integrally.

  The upper mounting disk 52 is an annular disk in which a through hole 52a (diameter 46 mm) having a circular cross section is formed at the center, and the stock solution supply pipe 36 is inserted into the through hole 52a. The outer diameter (75 mm in this embodiment) of the upper mounting disc 52 is substantially the same as the outer diameter of the lower mounting disc 54.

  On the upper surface 52b of the upper mounting disc 52, a tubular wall portion 55 (thickness 2 mm) is erected so as to surround the through hole 52a. The wall portion 55 is provided on the outer edge portion 52 c of the upper mounting disc 52 over the entire circumference thereof, and is provided integrally with the upper mounting disc 52. The wall portion 55 extends in a direction orthogonal to the upper mounting disc 52, that is, in the axial direction of the rotation shaft 32. Here, the inner diameter (the diameter of the inner peripheral surface 55a) of the wall portion 55 is larger by a minute length (for example, 2 mm) than the outer diameter (the diameter of the outer peripheral surface 49a) of the uniform diameter portion 49 of the casing 44. . Therefore, the wall portion 55 provided on the upper mounting disc 52 has a minute separation distance along the outer peripheral surface 49 a of the uniform diameter portion 49 of the casing 44 disposed close to the upper mounting disc 52. It extends to be kept. Further, the wall portion 55 of the upper mounting disc 52 extends to a height (23.5 mm in this embodiment) that can accommodate the entire uniform diameter portion 49 of the casing 44.

  A plurality (12 in this embodiment) of connecting shafts 56 that connect the upper mounting disk 52 and the lower mounting disk 54 are concentric along the periphery of the upper and lower mounting disks 50 as shown in FIG. Are arranged at equiangular intervals. A spray roller 62 is rotatably provided around each connecting shaft 56. That is, this spraying roller 62 is also disposed along the periphery of the lower mounting disk 54 (that is, the peripheral edge of the upper and lower mounting disk 50), like the connecting shaft 56. The spraying roller 62 has a substantially conical shape that gradually decreases in diameter from the lower mounting disk 54 toward the upper mounting disk. The spraying roller 62 may be fixed to the connecting shaft 56 so as not to rotate appropriately.

  When spraying droplets with the spray disc 34 having the above-described configuration, the upper / lower mounting disc 50 is viewed from the upper mounting disc 52 side while the upper / lower mounting disc 50 is rotated by the rotating shaft 32. The stock solution is supplied by the stock solution supply pipe 36 through the through hole 52a. Then, the undiluted solution supplied to the upper / lower mounting disk 50 flows in the peripheral direction of the upper / lower mounting disk 50 on the upper surface 54a of the lower mounting disk 54 by centrifugal force. When the undiluted solution reaches the spraying roller 62, it rises so as to be scooped up along the peripheral surface 62a of the spraying roller 62 to form a film. At this time, the thickness of the film-shaped stock solution is substantially uniform in the height direction of the spraying roller 62. The stock solution is formed into a film shape in the spraying roller 62 and then drops into the shape of a droplet, which is detached from the peripheral surface 62a of the spraying roller 62 and outward from the upper and lower mounting disks 50 as shown by the arrow A in FIG. Sprayed on. As described above, the stock solution is once formed into a film having a uniform thickness by the spraying roller 62, whereby the diameters of the sprayed droplets are made uniform to some extent.

  Next, the flow of air around the spraying plate 34 when the spraying by the spraying plate 34 is performed will be described with reference to FIG.

  As described above, the droplets sprayed by the spray board 34 are instantaneously dried and solidified in the spray drying chamber 12 to become particles, which are collected by the collection pocket 18 and the cyclone 24. However, the particles formed in the spray-drying chamber 12 include standard particle diameter particles in addition to particles having a standard particle diameter substantially matching the desired particle diameter (hereinafter referred to as standard particle diameter particles). In some cases, fine particles (hereinafter referred to as fine particles) having a remarkably small particle size as compared with the particle size of these particles may also be formed. The standard particle size drops in the spray drying chamber 12 due to its own weight and is collected in the collection pocket 18 or the cyclone 24. However, the fine particles are not dropped in the spray drying chamber 12 because of their small weight. Will be in a floating state.

Therefore, when the inside of the upper and lower mounting disk 50 is negatively rotated by the rotating shaft 32, air containing fine particles floating around the spray plate 34 (hereinafter also referred to as floating particles) is transferred to the upper mounting circle. An attempt is made to flow into the upper and lower mounting disk 50 from the through hole 52 a of the plate 52. The air flow path at this time is as shown by the arrow _RA in FIG. That is, the air around the spray platen 34 passes through the gap between the uniform diameter portion 49 of the casing 44 and the wall portion 55 of the upper mounting disc 52 toward the through hole 52a. Arrows R _B of FIG. 5 shows a hypothetical air distribution channel in the absence of wall portion 55.

As is apparent from FIG. 5, when the wall portion 55 is provided on the upper mounting disc 52 (the flow path indicated by the arrow _RA ), the wall portion 55 directly passes from the periphery of the spray disc 34 to the through hole 52a. since the flow of air (circulation path of arrow R _B) is blocked towards the inflow of air into the upper and lower mounting disc 50 is inhibited. In addition, by providing the wall portion 55 of the upper mounting disc 52, the air flow path extending from the periphery of the spray disc 34 to the inside of the upper and lower mounting disc 50 through the through hole 52a can be extended. In addition, the distribution path is complicated due to the bending at the S portion in FIG.

  That is, the air around the spraying plate 34 is in a state where it is difficult to flow into the upper and lower mounting disks 50, and the amount of air containing suspended particles flowing into the upper and lower mounting disks 50 is reduced. As a result, the number of suspended particles sucked into the upper and lower mounting disks 50 is reduced, and the situation where suspended particles adhere to the droplets sprayed from the spraying plate 34 is suppressed. Therefore, by using the above-described spray disc 34, spray device 14, and spray dryer 10 in which the upper mounting disc 52 is provided with the wall portion 55, suppression of adhesion of floating particles to the sprayed droplets is realized. ing.

  Thereby, the formation of standard particle size particles (see FIG. 8) around which suspended particles, which are thought to be generated as a result of adhering suspended particles to the droplets, is suppressed. Therefore, the situation where the particle diameter of the particle | grains formed using the spray board 34, the spray apparatus 14, and the spray dryer 10 is measured larger than an actual particle diameter is also suppressed significantly.

In addition, the ratio (floating particle content rate) in which the above-mentioned suspended particles are contained in a predetermined amount of air gradually decreases toward the upper side of the spray board 34. Therefore, the wall portion 55 provided in the upper mounting disc 52, it increased the inflow position of the air from the conventional position P _B to the position P _A, as shown in FIG. 5, upper and lower mounting of more effectively airborne particles Reduction of the amount of inflow into the disk 50 is realized. In order to reduce the amount of suspended particles sucked more effectively, the wall portion 55 can be extended so as to be along the variable diameter portion 48 of the casing 44. As another method for reducing the amount of suspended particles sucked into the upper and lower mounting disks 50, for example, the outer peripheral surface 49a of the casing 44 and the inner peripheral surface 55a of the wall 55 are made as close as possible to narrow the air flow path. And the like.

  In order to clarify the effect of the spray board according to the present invention, the following description will be made using Examples and Comparative Examples.

  The inventors have the same spraying plate (hereinafter referred to as spraying plate A) as the spraying plate 34 according to the above-described embodiment and the same spraying plate (hereinafter referred to as spraying plate B) as the spraying plate 80 according to the prior art. And a ceramic slurry was made into particles using each spray plate. And in order to compare both spray board A and B, the particle size distribution of the particle | grains formed by each spray board was measured. The experiments were conducted with the spraying plates A and B having the same conditions such as the peripheral speed (25 m / sec) of the spraying plate that affect the particle size.

  The measurement result of the particle size distribution was as shown in the graph of FIG. The horizontal axis of the graph in FIG. 6 indicates the particle size (μm), and the vertical axis indicates the cumulative fraction (%). In this graph, the particle size distribution (cumulative frequency curve) of particles atomized by the spray disc A is indicated by a solid line, and the particle size distribution (cumulative frequency curve) of particles atomized by the atomizer B is indicated by a broken line. ing.

  As is apparent from this graph, when the spray plate A is used, the reduction of particles having a large particle size is achieved as compared with the case where the spray plate B is used. This is because, when the spray plate A is used, the situation that the floating particles adhere to the standard particle size particles is suppressed. However, when the spray plate B is used, the floating particles include many standard particle sizes. This is considered to be because the measured value was larger than the actual particle size because of the adhesion.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, the wall part may be a separate body from the upper mounting disk. Further, the wall portion is not necessarily provided along the outer edge of the upper mounting disk, and may be provided along the inner edge (that is, the edge of the through hole) of the upper mounting disk, and between the outer edge and the inner edge. You may provide in arbitrary positions. Furthermore, the wall portion does not necessarily have a complete annular cross section, and a slit, a cutout, or the like may be formed in a part thereof. The spray dryer described above may be used when producing particles other than ceramic particles.

1 is a schematic configuration diagram of a spray dryer according to an embodiment of the present invention. It is the principal part expanded sectional view which showed the spraying apparatus of the spray dryer of FIG. It is the principal part expanded sectional view which showed the spraying board of the spraying apparatus of FIG. It is a top view of the spraying board of FIG. It is the principal part enlarged view which showed the spraying board of FIG. It is the graph which showed the measurement result which concerns on the Example of this invention. It is the figure which showed the spraying board concerning a prior art, (a) is sectional drawing, (b) has shown the top view. It is the photograph which showed the state of the particle | grains to which the airborne particle adhered.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Spray dryer, 12 ... Spray-drying chamber, 14 ... Spraying device, 16 ... Gas supply means, 32 ... Rotating shaft, 34 ... Spraying plate, 36 ... Stock solution supply pipe, 50 ... Vertical mounting disk, 52 ... Top mounting Disc, 52a ... through hole, 54 ... lower mounting disc, 55 ... wall, 62 ... spraying roller.

Claims (3)

Vertically and mounting disk, a said vertical mounting circle plates spraying machine that substantially Ru and a conical roller for the plurality of spray disposed substantially along the periphery of which has an upper mounting disc and lower mounting disc ,
A through hole is formed in the central portion of the upper mounting disk of the upper and lower mounting disks, and the upper surface of the upper mounting disk surrounds the through hole and is disposed above the spray plate. The spraying board in which the wall part standingly arranged along the outer surface of the casing which should be formed is formed. An upper and lower mounting disk having an upper mounting disk and a lower mounting disk, and a spraying plate having a plurality of substantially conical spraying rollers disposed along a substantially peripheral edge between the upper and lower mounting disks;
A rotating shaft that rotates above and below the spray disc and rotates the upper and lower mounting discs of the spray disc, and a stock solution supplying means that supplies the stock solution from the upper mounting disc side to the upper and lower mounting discs are housed. A casing and
In the central part of the upper mounting disk of the upper and lower mounting disk of the spray disc, a through hole in which the stock solution supplying means is disposed is formed, and on the upper surface of the upper mounting disk, A spraying device, wherein a wall portion is formed so as to surround the through-hole and to extend along the outer surface of the casing. An upper and lower mounting disk having an upper mounting disk and a lower mounting disk, and a spraying plate having a plurality of substantially conical spraying rollers disposed along a substantially peripheral edge between the upper and lower mounting disks;
A rotating shaft that rotates above and below the spray disc and rotates the upper and lower mounting discs of the spray disc, and a stock solution supplying means that supplies the stock solution from the upper mounting disc side to the upper and lower mounting discs are housed. A casing,
A spray drying chamber for accommodating the spray plate;
Gas supply means for supplying a high-temperature gas for heating and drying the stock solution sprayed from the spray disc in the spray drying chamber,
In the central part of the upper mounting disk of the upper and lower mounting disk of the spray disc, a through hole in which the stock solution supplying means is disposed is formed, and on the upper surface of the upper mounting disk, A spray dryer in which a wall portion is formed so as to surround the through-hole and to extend along the outer surface of the casing.

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