JPH0570658U - Centrifugal sprayer sprayer - Google Patents

Abstract

(57) [Summary] [Structure] Multiple spray holes 5 along the upper and lower disks 1 and 2
In the sprayer provided with the above, each spray hole 5 is a long hole shape including a long side portion 5b extending vertically and short side portions 5a at both ends thereof, and the short side portion 5a is continuous with the long side portion 5b. The shape. [Effect] It is possible to reduce the particle size variation of the sprayed droplets, and to narrow the particle size distribution of the particles after spray drying. Therefore, reduce the coarse particles contained in the raw material after drying,
It is possible to reduce waste of raw materials and obtain a high-quality granulated product having a uniform particle shape, particularly when it is used for spray-drying a ceramic slurry.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a spraying plate of a centrifugal sprayer in a spray-drying device for a drug solution, an undiluted solution of foodstuffs, and a slurry of ceramics.

[0002]

[Prior Art]

 As shown in the schematic view of one embodiment of the centrifugal spray-drying apparatus in FIG. 8, a stock solution G such as a ceramic slurry supplied from a stock solution supply pipe 8 is sent to a spray disk 9 which rotates at a high speed by a rotating shaft 4. The particles are sprayed as fine particles from the spraying disk 9 into the spray drying chamber 10, dried by the hot air sent from the hot air inlet 11 to the spray drying chamber 10 and fall into powder particles, and then from the product outlet 12 Taken out. On the other hand, the exhaust gas passes through the exhaust pipe 13 and is separated and collected by the cyclone 14 to be discharged.

As a conventional spraying disc 9 of this type, it is generally known that an annular wall 3 is provided around the upper and lower discs 1 and 2 as shown in FIG. 6, and a spray hole 5 is formed in the annular wall 3. ing. In addition, a Kessner type sprayer 9'having a structure as shown in FIG. 7 is also known (see, for example, Japanese Utility Model Publication No. 61-10767 and Japanese Utility Model Publication No. 62-179052).

[0004]

[Problems of conventional technology]

 When centrifugal spraying is performed by the conventional spraying disc 9 as shown in FIG. 6, the stock solution G flows outward in the form of a liquid film on the flat surface of the lower disk 2, and when it reaches the spray holes 5, it becomes longer than the flat surface. It spreads in the direction and is sprayed from the tip.

However, since the shape of the spray holes 5 in the conventional spraying disc 9 is rectangular as shown in FIG. 6, the liquid film of the raw material G is difficult to spread in the vertical direction during spraying. Therefore, the state of the liquid film of the stock solution G at the time of spraying becomes thicker on the lower side and thinner on the upper side, and the droplets sprayed from the lower side are large and the droplets sprayed from the upper side are small. As a result, there is a problem in that there is a large variation in particle size after the sprayed droplets are dried by a dryer such as a spray dryer.

[0006] Of the obtained dry particles, coarse particles having a particle size equal to or larger than the finally required particle size are cut by a sieve mesh, resulting in raw material loss. Therefore, as a means for reducing the coarse particles, there are means such as reducing the amount of the undiluted solution treatment or increasing the rotation speed of the sprayer 9, but as a result, although the coarse particles are slightly reduced, the productivity is remarkably increased. However, there was a problem in that the wear of the spraying device was accelerated, and the particle distribution became finer than necessary.

[0007]

[Means for Solving the Problems]

 In view of the above, the present invention is a spraying machine having spray holes at the peripheral edges of the upper and lower disks, and each spray hole has a long hole shape composed of a long side portion extending vertically and short side portions at both ends thereof. Moreover, the short side portion is formed into a guide shape which is continuous with the long side portion.

Here, the guide shape continuous with the long side portion is a shape in which the short side portion gradually becomes higher toward the long side portion, and as will be described later in a specific example, the short side portion is formed. It is an arc shape that is continuous with the long side portion, or a shape in which the short side portion is an oblique side and the angle formed with the long side portion is larger than 90 °. Further, in the present invention, it is not necessary to form all the boundary portions between the short side portion and the long side portion forming the spray hole into the guide shape, and at least one boundary portion may be smoothly continuous.

[0009]

[Action]

 The undiluted solution introduced from the undiluted solution supply port of the spray disk flows as a liquid film along the lower disk by the rotation of the spray disk, and reaches the vertical spray holes formed in the peripheral edge of the lower disk, changing vertically from the plane. Becomes At this point, the sprayer of the present invention has a guide shape in which the short side of the lower side of the spray hole is continuous with the long side, so that a uniform liquid film is supplied to the entire spray hole in the vertical direction. Sprayed outward. Therefore, the particle size variation of the sprayed microdroplets is small, and the particle size distribution of dry particles can be narrowed.

[0010]

【Example】

 Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments (the same parts as those in the conventional example use the same reference numerals), but the present invention is not limited to these embodiments.

As shown in the schematic view of one embodiment of the centrifugal spray drying device in FIG. 8, the undiluted solution G supplied from the undiluted solution supply pipe 8 is sent to the spray disc 9 that rotates at a high speed by the rotating shaft 4, Fine particles are sprayed from the sprayer 9 into the spray drying chamber 10 and are dried by the hot air sent from the hot air inlet 11 to the spray drying chamber 10 to fall into powder and granules. Taken from 12. On the other hand, the exhaust gas passes through the exhaust pipe 13 and is separated and collected by the cyclone 14 to be discharged.

As shown in FIG. 1, the spray disk 9 is composed of an upper disk 1, a lower disk 2 and an annular wall 3 at the peripheral portion thereof, and a plurality of spray holes 5 are formed in the annular wall 3. When spraying is performed using this spray plate 9, the undiluted solution G supplied from the upper part flows outward in the form of a liquid film on the flat surface of the lower disk 2 and reaches the spray hole 5 from the flat surface. It spreads vertically and is sprayed from the tip.

Further, as shown in an enlarged view of the spray hole 5 in FIG. 2, the spray hole 5 has a long hole shape including an arc-shaped short side portion 5a at two upper and lower portions and an intermediate long side portion 5b. is there. According to such a spraying disc 9 of the present invention, the short side 5a of the spray hole 5 has a guide shape which is continuous with the long side 5b. Therefore, as shown in FIG. It is easy to be transmitted from the portion 5a to the long side portion 5b, and the spread in the vertical direction can be increased to perform uniform spraying.

The radius of curvature R of the arc-shaped short side portion 5 a starting from the center line of the spray hole 5 is in the range of 3 to 10 mm and is 1/2 of the length H of the spray hole 5. It is as below. This is because, as shown in FIG. 3, the spray hole 5 having an arc-shaped short side 5a with various curvature radii R, when the curvature radius R is smaller than 3 mm, the stock solution G flows to the upper side of the spray hole 5. If the radius of curvature R is larger than 10 mm, the liquid film of the raw material G reaches the upper arc portion, and the uniform spraying cannot be performed.

In this embodiment, the case where the undiluted solution G flows on the lower disc 2 is shown, but depending on the shape of the spray disc 9, it may flow on the lower side of the upper disc 2. It is desirable that the short side portion 5a on the upper side of 5 also has an arc shape with a similar radius of curvature R. Further, in this embodiment, since the spray hole 5 has a bilaterally symmetrical shape, the rotating direction of the spray disk 9 may be either direction.

Next, another embodiment of the shape of the spray hole 5 will be described. As shown in FIG. 4 (A), the short side portion 5a on the lower side of the spray hole 5 has an arc-shaped guide shape which is continuous with only one long side portion 5b. That is, when the direction of rotation of the spray disc 9 is fixed and the stock solution G flows only on the lower disc 2, only one place may be formed into the guide shape. In addition, in FIGS. 4B and 4C, the short side portion 5a is an oblique side and the angle α with the long side portion 5b is larger than 90 °. Even with such a shape, the short side portion 5a is a guide shape in which the long side portion 5b is continuous, and the size of the atomized droplet can be made uniform.

Further, in these embodiments, the sectional shape of the annular wall 3 at the peripheral portion of the lower disk 2 is not particularly limited, and may be rectangular or trapezoidal as shown in FIG. The width W of the annular wall 3 may be 5 mm or more. Further, the length H of the spray hole 5 is preferably 10 to 50% with respect to the radius of the spray disc 9.

Experimental Example A spraying plate 9 of the present invention shown in FIG. 1 was prototyped, and a spraying experiment of ceramic raw material powder was carried out by changing the radius of curvature R of the short side portion 5a of the spraying hole 5 variously.

As a stock solution, a slurry containing 60% by weight of alumina and having a specific gravity of 1.6 and a viscosity of 30 centipoise was used. Further, as the spraying disc 9, an object having a diameter of 100 mm is prepared, and the slurry is spray-dried under the same conditions by using the spraying disc 9 in which the curvature radius R of the short side 5a of the spraying hole 5 is different, and the particles after drying are sprayed. The particle size distributions were compared.

As shown in FIG. 9, when the radius of curvature R of the short side portion 5a is smaller than 3 mm, the state of the liquid film flowing through the spray holes 5 becomes thicker on the lower side and becomes thinner on the upper side. However, the effect of narrowing the particle size distribution of dry particles was poor. On the contrary, when the radius of curvature R is larger than 10 mm, the upper side of the state of the liquid film flowing through the spray holes 5 becomes thicker, and the particle size distribution of the dry particles tends to become wider. On the other hand, it was found that when the radius of curvature R of the short side portion 5a was 3 to 10 mm, the dry particle size distribution was narrow and dry particles having a uniform particle size could be obtained.

[0021]

[Effect of the device]

 As described above, according to the present invention, in a spraying disc having a plurality of spraying holes along the periphery of the upper and lower disks, each spraying hole has a long side extending vertically and short side portions at both ends thereof. The long hole and the guide shape in which the short side is continuous with the long side can reduce the particle size variation of the droplets to be sprayed and narrow the particle size distribution of the particles after spray drying. it can. Therefore, it is possible to obtain high-quality granules with uniform grain shape, by reducing the amount of coarse particles contained in the raw material after drying, reducing the waste of raw material, and especially when using it for spray drying of ceramic slurry. it can. Further, since the spray disk of the present invention can supply the undiluted solution as a thin liquid film, it is possible to reduce the rotation speed of the spray disk by about 6% to obtain the same dry particle size under the same slurry processing amount. Becomes

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing a spraying disc of a centrifugal spraying device of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a view for explaining a spraying state of a liquid film from a spraying hole by the spraying disk of the present invention.

4 (A) to (C) are views showing various examples of spray holes in the spray disk of the present invention.

5 (A) and 5 (B) are cross-sectional views showing various embodiments of a B part in FIG. 1, respectively.

FIG. 6 is a partially cutaway side view showing a spraying disc of a conventional centrifugal spraying device.

FIG. 7 is a partially cutaway side view showing a spraying disc of a conventional centrifugal spraying device.

FIG. 8 is a schematic view of an embodiment of a centrifugal spray dryer.

FIG. 9 is a graph showing the particle size distribution of dry particles after centrifugal spraying.

[Explanation of symbols]

 1 ... Upper disc 2 ... Lower disc 3 ... Annular wall 4 ... Rotating shaft 5 ... Spray hole 5a ... Short side 5b ... Long side R ... Short side Radius of curvature 8 ... Undiluted solution supply pipe 9 ... Spraying machine 10 ... Spray drying chamber 11 ... Hot air inlet 12 ... Product outlet 13 ... Exhaust pipe 14 ... Cyclone

Claims (1)

[Scope of utility model registration request] 1. A spraying disc having a plurality of spraying holes provided along the periphery of upper and lower disks, wherein each spraying hole has a long hole shape consisting of a long side extending vertically and short sides at both ends thereof. A spraying disc for a centrifugal spraying device, characterized in that the short side portion has a guide shape continuous with the long side portion.