JP2014161837A - Spray device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spray device capable of making a uniform distribution direction of particles and making particle size distribution sharp.SOLUTION: A distribution pin 36 includes a first part 50 formed adjacent to a lower rotation plate and a second part 52 formed continuous to the first part 50 and adjacent to an upper rotation plate. The second part 52 is columnar. The first part 50 has a shape in which a cross section area S1 of a boundary between the lower rotation plate and the first part 50 is larger than a cross section area S2 of a boundary between the first part 50 and the second part 52.

Description

  The present invention relates to a spraying device for spraying slurry.

  The spraying device is a device for spraying a slurry composed of raw material powder, a solvent, a binder, and the like by a spraying unit such as a nozzle and a rotating disk, and instantly drying with hot air. Such a spraying device is conventionally used for obtaining granules in pharmaceuticals, fine ceramics and the like.

  As a spraying device, a pressure nozzle, a rotating disk, etc. are mainly used. When a rotating disk is used, finer granules can be obtained as compared with the case where a pressure nozzle is used. Therefore, a rotating disk is preferably used as the spray section.

  The rotating disk generally has a disk shape, and is formed on a lower rotating plate supported by a rotating shaft, a dispersion pin for spraying droplets (also referred to as a spray roller), and a dispersion pin. It is comprised from an upper rotating board (for example, refer patent document 1).

  In the conventional spraying device, the dispersion pin is generally formed in a conical shape as a whole. However, according to experiments by the present inventors, the conventional dispersion pin shape has the problem that the dispersion direction of the fine particles is not uniform, and it is difficult to sharpen the particle size distribution of the obtained particles. Turned out to be.

JP 9-131550 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a spraying device in which the dispersion direction of fine particles is uniform and the particle size distribution of the obtained particles can be sharpened.

  The present inventors have found that the shape of the dispersion pin of the spraying device has a great influence on the dispersion direction of the fine particles and the particle size distribution of the resulting granules, and have completed the present invention.

That is, the spray device according to the present invention is
A spraying device having a rotating disk for spraying slurry radially,
The rotating disk is
A lower rotating plate fixed to the rotating shaft;
An upper rotating plate having an upper opening, fixed substantially parallel to the lower rotating plate with a predetermined gap, and positioned on the upper side along the axial direction of the rotating shaft;
Along with the outer periphery of the lower rotating plate and the upper rotating plate, with the dispersion pins arranged at predetermined intervals in the outer peripheral direction so as to connect the lower rotating plate and the upper rotating plate,
The dispersion pin is
A first portion formed adjacent to the lower rotating plate;
A second portion formed continuously with the first portion and formed in proximity to the upper rotating plate;
The second part is cylindrical,
The first portion has a shape in which a cross-sectional area of a boundary portion between the lower rotating plate and the first portion is larger than a cross-sectional area of a boundary portion between the first portion and the second portion. .

  In the spray device according to the present invention, since the dispersion pin having the above-described configuration is provided, the dispersion direction of the particles from the rotating disk becomes uniform, and the force acting on the fine particles at the time of collision dispersion is homogenized for each individual particle. As a result of experiments by the present inventors, it was found that the particle size variation of the obtained particles becomes smaller and sharper. Further, in the present invention, since the dispersion pin having the above-described configuration is provided, it is found that particles are ejected in the horizontal direction with respect to the lower rotating plate and the upper rotating plate, and the solidified product of the slurry adhering to the rotating disk is reduced. did.

  Preferably, the first portion has a truncated cone shape. The ridge line is not limited to a linear truncated cone shape, but may be a truncated cone shape in which the ridge line is a concave curved surface on the inside.

  Preferably, when the height of the first portion is h1 and the height of the second portion is h2, h1 / h2 is 0.82 to 1.22.

  Preferably, when the cross-sectional area at the boundary between the lower rotating plate and the first part is S1, and the cross-sectional area at the boundary between the first part and the second part is S2, S2 / S1 is 0.33 to 0.67.

FIG. 1 is an overall configuration diagram of a spray drying apparatus including a spray apparatus according to an embodiment of the present invention. FIG. 2 is a side view of an essential part of the spray unit of the spray device shown in FIG. FIG. 3A is an enlarged schematic view of the main part of the spray unit of the spray drying apparatus shown in FIG. 2, and FIG. 3B is a partial sectional plan view taken along the line IIIB-IIIB shown in FIG. FIG. 4 is an image diagram of particles dispersed from the rotating disk shown in FIGS. 3 (A) and 3 (B). FIG. 5A and FIG. 5B are perspective views of main parts showing examples of the shape of the dispersion pins. FIG. 6 is a conceptual diagram for evaluating the adhering state of the adherent to the rotating disk.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
First embodiment

  As shown in FIG. 1, the spray-drying system which concerns on one Embodiment of this invention has the spray-drying apparatus 2, a cyclone, a bag filter, and the blower for collection machines. The spray drying apparatus 2 has a drying cylinder 4, and a spray unit 20 as a spraying apparatus is attached to the upper center of the drying cylinder 4, and the rotating disk 30 of the spray unit 20 is located above the interior of the drying cylinder 4. It is supposed to be located in.

  A supply nozzle (not shown) for supplying hot air for drying to the inside of the drying cylinder 4 is installed on the upper part of the drying cylinder 4. The gas supplied from the supply nozzle is not particularly limited and may be appropriately selected according to the raw material to be dried. For example, air or nitrogen can be used. The temperature of the gas is not particularly limited, but is preferably in the range of 100 to 350 ° C, more preferably 150 to 250 ° C.

  In the spray drying system of the present embodiment, a slurry composed of raw material powder, a solvent, a binder, and the like is supplied to the spray unit 20 via a slurry pump or the like, and the inner wall of the drying cylinder 4 from the rotating disk 30 by centrifugal force. Spray radially toward. The sprayed slurry is dried in the drying cylinder 4 by hot air for drying sent from a hot air supply nozzle, and granular raw material particles (granules) are taken out from the discharge port 8. Note that the granules are recovered from the discharge port 8 together with the solvent evaporated by spray drying, using a cyclone, a bag filter, and a recovery machine blower as exhaust means.

  As shown in FIGS. 2 and 3, the spray unit 20 has a protective casing 22, in which a rotary shaft 24 is rotatably mounted by a bearing 26, and the lower end of the rotary shaft 24 is It protrudes from the lower end 22 a of the protective casing 22. A rotating disk 30 is fixed to the lower end of the rotating shaft 24, and can be rotated around the axis of the rotating shaft 24 by the rotation of the rotating shaft 24.

  As shown in FIGS. 2 and 3A, the protective casing 22 has a shape in which the outer diameter decreases toward the lower end 22a of the protective casing 22. That is, the protective casing 22 has a small-diameter portion 22c below a casing body 22b having a relatively large outer diameter, and these are connected by a tapered portion 22d.

  The outer diameter of the small diameter portion 22 c is larger than the inner diameter of the upper opening 35 of the rotating disk 30 and smaller than the outer diameter of the rotating disk 30. As a result, as shown in FIG. 1, when the protective casing 22 is attached to the upper portion of the drying cylinder 4, the outer periphery of the lower end of the casing 22 guides the drying hot air flowing inside the drying cylinder 4 to the rotating disk 30. Therefore, it has a convenient shape. The outer periphery of the lower end of the casing 22 has a shape excellent in rectification characteristics.

  As shown in FIG. 3A, a plurality (two in the figure) of slurry tubes 44 are arranged around the rotating shaft 24 at a predetermined interval (180 degree symmetrical position in the figure) inside the protective casing 22. The lower end opening of each tube 44 constitutes the discharge port 42 of the discharge nozzle 40.

  The discharge nozzle 40, which is the lower end opening of the tube 44, is held by the holding member 23 attached to the lower end 22 a of the protective casing 22. At the lower end 22 a of the protective casing 22, the inside of the protective casing 22 is sealed by the holding member 23 except that the lower end of the rotating shaft 24 and the lower end of the discharge nozzle 40 are exposed to the outside of the casing 22.

  The tube 44 is made of, for example, a metal tube such as stainless steel, copper, aluminum, iron, or brass, or a synthetic resin tube such as fluororesin, vinyl resin, nylon, silicone, fluororesin, or polypropylene. The inner diameter of the tube 44 is preferably 2 to 12 mm, and the thickness of the tube 44 is preferably 0.3 to 3 mm.

  As shown in FIGS. 3A and 3B, the rotating disk 30 includes a lower rotating plate 32, an upper rotating plate 34, and a dispersion pin 36. The lower rotating plate 32 has a disk shape, and a boss portion 33 protrudes in the axial direction and is integrally formed at the center thereof. The boss portion 33 is detachably fixed to the rotating shaft 24 with a nut or the like.

  The upper rotating plate 34 has a thin ring shape, and an upper opening 35 having an inner diameter sufficiently larger than the rotating shaft 24 is formed at the center. A plurality of dispersion pins 36 positioned between the upper rotating plate 34 and the lower rotating plate 32 are arranged at substantially equal intervals along the outer periphery of the disk 30, and connect the upper rotating plate 34 and the lower rotating plate 32. doing.

  The plurality of distribution pins 36 may be arranged at unequal intervals along the outer periphery of the disk 30, but are preferably arranged at substantially equal intervals. In the present embodiment, each dispersion pin is fixed to the upper rotation plate 34 and the lower rotation plate 32 and does not rotate itself, but may be configured to rotate around the axis of each dispersion pin. . The shape of the dispersion pin will be described later.

  As will be described later, the slurry discharged from the discharge port 42 of the discharge nozzle 40 is a gap between the dispersion pins 36 between the upper rotating plate 34 and the lower rotating plate 32 due to the centrifugal force of the rotating rotating disk 30. Are discharged (sprayed) radially. The rotational speed of the rotating disk 30 is not particularly limited, but is preferably a rotational speed of 2000 to 7000 rpm.

  As shown in FIG. 3 (A), the pair of discharge nozzles 40 held by the holding member 23 provided at the lower end 22a of the protective casing 22 has a discharge port 42 at the upper opening of the upper rotating plate 34. 35 is located within a predetermined gap 38 between the upper rotating plate 34 and the lower rotating plate 32. Further, in the present embodiment, the boss portion 33 protrudes from the upper surface of the upper rotating plate 34 along the rotation axis 24 from the upper opening 35 of the upper rotating plate 34.

  As shown in FIG. 4, the gap between the upper rotary plate 34 and the lower rotary plate 32, that is, the dispersion gap α corresponds to the total height h0 of the dispersion pin 36 shown in FIG. Is not particularly limited, but is preferably 1.50 to 3.50 mm when producing ferrite granules and the like.

  In the present embodiment, as shown in FIGS. 4 and 5A, each dispersion pin 36 is formed in contact with the lower rotating plate 32 and continuously with the first portion 50. And a second portion 34 formed in contact with the upper rotating plate 34. In the present embodiment, the second portion 52 has a cylindrical shape, and the first portion 50 has a lower rotary plate 32 and the first portion 50 than the cross-sectional area S2 of the boundary portion between the first portion 50 and the second portion 52. It has a shape with a large cross-sectional area S1 at the boundary between the two.

  In the present embodiment, as shown in FIG. 5A, the first portion 50 has a truncated cone shape in which the ridge line is linear, but as shown in FIG. 5B, the ridge line of the first portion 50a is A truncated cone shape having a concave curved surface inside may be used. In the present embodiment, a truncated cone shape in which the ridge line of the first portion 50 is an outwardly convex curved surface is not preferable.

  In the present embodiment, when the height of the first portion 50 or 50a in each dispersion pin 36 is h1, and the height of the second portion 52 is h2, h0 = h1 + h2, and h1 / h2 is preferably It is 0.82-1.22, More preferably, it is 1.00-1.16.

  Further, when the cross-sectional area of the boundary between the lower rotary plate 32 and the first part 50, 50a is S1, and the cross-sectional area of the boundary between the first part 50, 50a and the second part is S2, S2 / S1 is preferably 0.33 to 0.67, more preferably 0.38 to 0.40. The cross-sectional area S2 of the boundary between the first part 50, 50a and the second part is the same as the cross-sectional area S3 of the boundary between the second part 52 and the upper rotating plate 34.

  Furthermore, as shown in FIG. 3B, the circumferential clearance β between the adjacent dispersion pins 36 (see FIG. 3B) is not particularly limited, but is preferably 120 to 155 mm.

  The concrete spraying method of the slurry by the spraying unit 20 is shown next. First, slurry is dropped in the form of droplets from the discharge port 42 of the discharge nozzle 40 shown in FIG. 3A to the inner bottom surface 32a of the lower rotating plate 32 of the rotating disk 30. Next, the slurry droplets move on the inner bottom surface 32 a of the lower rotating plate 32 to the outer peripheral side by the centrifugal force generated by the rotation of the rotating disk 30, and adhere to the lower peripheral surface of the dispersion pin 36. And it is thought that the slurry droplet adhering to the dispersion | distribution pin 36 raises on the surface of the dispersion | distribution pin 36 with a centrifugal force, and leaves the dispersion | distribution pin 36 in the meantime and is sprayed.

  The upper rotating plate 34 formed above the dispersion pins 36 is considered to have a function of stabilizing the spraying of the slurry droplets. By forming the upper rotating plate 34, the particle size of the granules obtained The distribution can be sharpened.

  The droplets of the slurry sprayed from the spray unit 20 are suspended and rotated, for example, spirally inside the drying cylinder 4 shown in FIG. 1, and in the meantime, they are dried by the gas supplied from the supply nozzle into granules, Finally, it is taken out from the dry material discharge port 8.

  According to this embodiment, it is possible to obtain a granule having a good particle size distribution and containing very little impurities. In addition, by using the spray drying apparatus 2 according to the present embodiment to produce granules, for example, it is possible to produce granules with a sharp particle size distribution and little variation.

  The reason is considered to be as follows. That is, in this embodiment, since the dispersion pin 36 having the above-described configuration is provided, the dispersion direction of the particles 60 dispersed in the centrifugal force direction (dispersion direction) from the rotating disk 30 becomes uniform as shown in FIG. The force acting on the fine particles during collision dispersion is homogenized for each individual particle, and the particle size variation of the obtained particle is reduced and sharpened. Further, in the present embodiment, since the dispersion pins 36 having the above-described configuration are provided, the particles 60 are ejected in the horizontal direction with respect to the lower rotating plate 32 and the upper rotating plate 34 as shown in FIG. The solidified product of the slurry adhering to is also reduced.

  In addition, as a granule used for this embodiment, a ceramic granule, a ferrite granule, foodstuffs, pharmaceuticals, organic compounds, etc. are used preferably. Further, the viscosity of the slurry is not particularly limited, but in the present embodiment, a slurry having a relatively high viscosity such as 0.1 to 5 poise can be handled. Further, the concentration of solid matter (ceramic or the like) in the slurry is not particularly limited, but it can be applied to a relatively high concentration slurry containing 50 to 70% solid matter.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.
Example 1

  First, a ceramic raw material was prepared as a starting raw material, the ceramic raw material, a binder, and pure water were stirred and mixed, and then mixed and pulverized using a compounding pulverizer to produce a ceramic slurry. The viscosity of the slurry was 2 poise. The concentration of the slurry was 70%.

  Next, the obtained ceramic slurry was spray dried using the spray drying apparatus 2 having the spray unit 20 shown in FIGS. The spray drying conditions were such that the rotational speed of the rotating disk 30 was 3500 rpm, and the temperature of the drying hot air was 190 ° C.

  Further, in this embodiment, the dispersion gap α shown in FIG. 3A is set constant at 2.00 mm and the circumferential gap β is set constant at 140 mm, and the height of the first portion 50 and the second portion 52 in the dispersion pin 36 is set. Table 1 shows the results of examining the particle size distribution (dispersibility) of the granules obtained from the discharge port 8 shown in FIG. 1 when the lengths h1 and h2 and the areas S1 and S2 of the respective boundary portions are changed.

  In Table 1, 60 μm, 75 μm, 103 μm, and 150 μm in the frequency (%) according to each mesh opening indicate the particle size mesh, and the numerical value for each particle size mesh indicates the powder that has passed through each mesh opening mesh. Indicates body weight%.

  In Table 1, one peak of the distribution curve type indicates that the peak of the particle size distribution measured by the frequency (%) according to the mesh opening is single, and two peaks indicate the peak of the particle size distribution. Indicates two. Further, in the dispersibility, ◎ indicates that the particle size distribution is sharp and has a particularly sharp distribution, ○ indicates that the particle size distribution is sharp in a mountain, and Δ indicates that the particle size distribution is sharp. It means that the particle size distribution is broad and the particle size distribution is broad, and there are many fine particles of 60 μm or less, or even if there is one mountain, the particle size distribution peak exists at 60 μm or less. Indicates that The presence of a particle size distribution peak at 60 μm or less means that the proportion of particles having a particle size of 60 μm or less is large. Fine particles having a particle size of 60 μm or less may cause agglomeration when individual particles are attracted to each other by an electrostatic action, which may cause a decrease in yield. Moreover, it may cause clogging by aggregating in the filter.

  Further, in Table 1, the evaluation of the disc adhesion was performed based on the evaluation criteria shown in FIG. That is, the rotating state of the rotating disk having the dispersion pins of the respective sample numbers shown in Table 1 was photographed with a camera, and the disk adhesion was visually confirmed.

  For example, when adhesion of slurry solidified material was not observed, it was evaluated as ◎, and when adhesion of slurry solidified material (adhesive material) that did not affect dispersion was observed as ○, Is repeated. However, when dropping and growth are repeated, Δ is evaluated, and when there is a possibility that the fixing material is considerably fixed and the dispersion of the slurry may be obstructed, the evaluation is ×.

Evaluation 1

  As shown in Table 1, when h1 / h2 is preferably 0.82 to 1.22, and more preferably 0.95 to 1.00, there is little disc adhesion and excellent dispersibility. confirmed. Further, when S2 / S1 is preferably 0.33 to 0.67, and more preferably 0.40 to 0.56, it was confirmed that there is little disc adhesion and excellent dispersibility.

2 ... Spray drying device 4 ... Drying cylinder 20 ... Spraying unit (spraying device)
22 ... Protective casing 22a ... Lower end 22b ... Casing body 22c ... Small diameter part 22d ... Tapered part 23 ... Holding member 24 ... Rotating shaft 30 ... Rotating disk 32 ... Lower rotating plate 33 ... Boss part 34 ... Upper rotating plate 35 ... Upper opening 36 ... Dispersion pin 38 ... Predetermined gap 40 ... Discharge nozzle 42 ... Discharge port 44 ... Slurry tubes 50, 50a ... First part 52 ... Second part 60 ... Particles

Claims (4)

A spraying device having a rotating disk for spraying slurry radially,
The rotating disk is
A lower rotating plate fixed to the rotating shaft;
An upper rotating plate having an upper opening, fixed substantially parallel to the lower rotating plate with a predetermined gap, and positioned on the upper side along the axial direction of the rotating shaft;
Along with the outer periphery of the lower rotating plate and the upper rotating plate, with the dispersion pins arranged at predetermined intervals in the outer peripheral direction so as to connect the lower rotating plate and the upper rotating plate,
The dispersion pin is
A first portion formed adjacent to the lower rotating plate;
A second portion formed continuously with the first portion and formed in proximity to the upper rotating plate;
The second part is cylindrical,
The first portion has a shape in which a cross-sectional area of a boundary portion between the lower rotating plate and the first portion is larger than a cross-sectional area of a boundary portion between the first portion and the second portion. Spraying equipment.   The spray device according to claim 1, wherein the first portion has a truncated cone shape. When the height of the first part is h1, and the height of the second part is h2,
The spraying device according to claim 1 or 2, wherein h1 / h2 is 0.82 to 1.22. When the cross-sectional area of the boundary between the lower rotating plate and the first part is S1, and the cross-sectional area of the boundary between the first part and the second part is S2,
S2 / S1 is 0.33-0.67, The spraying apparatus in any one of Claims 1-3.

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