JPH0518601U - Centrifugal sprayer sprayer - Google Patents

Abstract

(57) [Summary] [Structure] At least a lower disc 1 is rotated in a spray disc 9 in which a plurality of spray holes 5 are formed in an annular wall 3 provided on the peripheral portions of a lower disc 1 and an upper disc 2. It is inclined downward with respect to the normal direction of the shaft 4. [Effect] It is possible to reduce variations in particle diameter of sprayed droplets and narrow the particle size distribution of particles after drying.

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]

 Conventionally, this type of spraying disk has an annular wall 13 formed on the peripheral portions of a lower disk 11 and an upper disk 12 as shown in FIG. 5, and the annular wall 13 is provided with a plurality of spray holes 15 having a long hole shape. It was a thing. In addition, a Kessner type sprayer 20 having a structure as shown in FIG. 6 is also known (see Japanese Utility Model Publication No. 61-10767 and Japanese Utility Model Publication No. 62-179052).

A centrifugal spraying device using these spraying disks has a structure as shown in FIG. The undiluted solution supplied from the undiluted solution supply pipe 8 is sprayed into the spray drying chamber 10 as fine particles on the spray disk 9 which rotates at a high speed by the rotating shaft 4, and is dried by the hot air sent from the hot air inlet 11 to the spray drying room 10. As a result, it falls into a granular material and is taken out from the product take-out port 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. If a ceramic slurry is used as the stock solution, the ceramic raw material can be granulated and dried.

[0004]

[Problems of conventional technology]

 However, when spraying with the conventional sprayer shown in FIG. 5, the undiluted solution flows vertically on the flat surface of the lower disk 11 and reaches the spray hole 15 formed in the vertical direction. Therefore, the undiluted liquid film is thicker on the lower side of the spray hole 15 and thinner on the upper side of the spray hole 15. For this reason, the fine droplets sprayed from the lower side of the spray hole 15 have a large particle diameter, and the fine droplets sprayed from the upper side have a small particle diameter. There is a problem that the particles are large and have a wide particle size distribution after drying.

Of these dry particles, coarse particles having a particle size that is finally required or larger are cut by the sieve mesh and become useless. Therefore, as a means to reduce the coarse particles, it is necessary to reduce the amount of stock solution to be treated or increase the number of revolutions of the spraying machine.As a result, although the coarse particles are slightly reduced, the productivity is remarkably reduced. However, there were problems that the wear of the atomizer was accelerated and the particle distribution was biased in a finer direction than necessary.

[0006]

[Means for Solving the Problems]

 In view of the above problems, the present invention is one in which a lower plate circle constituting a spraying disc of a centrifugal spraying device is inclined downward with respect to a direction perpendicular to a rotation axis.

[0007]

[Action]

 The undiluted solution introduced into the spraying disc of the present invention first flows as a liquid film along the lower disc due to the rotation and tilt angle of the spraying disc, and is further separated from this lower disc by a centrifugal force to move horizontally. The particles are scattered in the same direction and are evenly supplied to the entire surface of the annular wall provided at the end edge of the lower disk, and atomized outward through this wall. Therefore, the particle size variation of the sprayed fine droplets is small, and the particle size distribution of the dry particles can be narrowed.

[0008]

【Example】

 Hereinafter, the present invention will be described in more detail based on the illustrated embodiments, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic cross-sectional view of a spraying disc 9 of the present invention. The spraying disc 9 comprises a lower disc 1, an upper disc 2 and an annular wall 3 provided around these discs. A plurality of spray holes 5 having a long hole shape are formed in 3. The lower disc 1 and the upper disc 2 are inclined downward with respect to the normal direction of the rotary shaft 4 by inclination angles θ1 and θ2, respectively, and the inclination angle θ1 of the lower disc 1 is 2 to 45. And preferably 2 to 30 °. Further, the upper disc 2 is also inclined at an angle θ2 which is substantially the same as that of the lower disc 1. In addition, although it is desirable to incline this upper disc 2, it is not always necessary to incline it.

Further, the cross-sectional shape of the annular wall 3 at the peripheral portion of the lower disc 1 is not particularly limited, and may be rectangular or trapezoidal as shown in FIGS. 2 (A) and 2 (B). The width W of the annular wall 3 may be 5 mm or more. Further, the height H of the spray port 5 is preferably 10 to 50% with respect to the radius R of the spray disk.

Further, as another embodiment, as shown in FIG. 3, the lower disc 1 and the upper disc 2 may each be curved and inclined downward. In this case, the angle formed by the straight line connecting the central portion and the peripheral portion of the lower disk 1 and the normal line of the rotation axis is the inclination angle θ1.

Next, the operation of the centrifugal spray dryer using the spray disc 9 of the present invention will be described. As shown in FIG. 7, the undiluted solution supplied from the undiluted solution supply pipe 8 is first atomized into fine particles from the spray disc 9 of the present invention into the spray drying chamber 10 through the liquid distributor, and is sprayed from the hot air inlet 11. The powder is dried by the hot air sent to the drying chamber 10, falls into a powder or granular material, and falls and is taken out from the product taking-out port 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.

At this time, as shown in FIG. 4, the undiluted solution G supplied to the spray disc 9 flows in the form of a liquid film along the lower disc 1, but the lower disc 1 is inclined downward. Therefore, due to the centrifugal force generated by the rotation of the spraying disc 9, the undiluted solution G gradually separates from the lower disc 1 and horizontally scatters, is uniformly supplied to the entire peripheral wall 3, and is sprayed from the spraying port 5 into the spray drying chamber 10. Be done. In this way, since the undiluted solution G is uniformly supplied and sprayed in the height direction of the peripheral wall 3, the particle diameters of the droplets sprayed from the lower side of the spray hole 5 and the droplets sprayed from the upper side are almost the same. In the same manner, it is possible to reduce the particle size variation of the sprayed droplets, so that the particle size distribution of the dried particles can be narrowed.

Experimental Example A spraying experiment was conducted using a stock solution G containing 60% by weight of alumina and having a specific gravity of 1.6 and a viscosity of 30 centipoise. As the sprayer 9 of the present invention, a sprayer having a shape shown in FIG. 1 and a diameter of 100 mm and an inclination angle θ1 of the lower disc 1 of 3 ° is prepared, and a conventional sprayer shown in FIG. 5 is used as a comparative example. Then, the above slurry was spray-dried under the same conditions, and the particle size distribution of the dried particles was compared. The results, as shown in FIG. 8, show that the particle size distribution of dry particles can be narrowed by using the spraying disk of the present invention.

Further, in the same manner as described above, an experiment was conducted by changing the inclination angle θ1 of the lower disc 1 in various ways. As a result, although it depends on the state of the slurry, when the tilt angle θ1 is smaller than 2 °, the effect of narrowing the particle size distribution of dry particles was poor. On the contrary, when the inclination angle θ1 is large, the stock solution G is supplied to the upper disc 2 side in a large amount, which tends to widen the particle size distribution of the dry particles, and the inclination angle θ1 is 45 ° or less, preferably Those of 30 ° or less were good.

[0016]

[Effect of the device]

 As described above, according to the present invention, in the spraying disc of the centrifugal spraying device, the lower disk is inclined downward with respect to the normal direction of the rotation axis, so that the variation in the particle size of the spray droplets can be reduced. The particle size distribution of the particles after spray drying can be narrowed. Therefore, the coarse particles contained in the raw material after drying are reduced, the waste of the raw material is reduced, and in particular, when it is used for spray drying of ceramic slurry, a high-quality granule having a uniform particle diameter can be obtained. You can

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a spraying disc of a centrifugal spraying device according to an embodiment of the present invention.

2 (A) and 2 (B) are cross-sectional views showing only part A in FIG.

FIG. 3 is a partial sectional view showing another embodiment of the present invention.

FIG. 4 is a view for explaining a usage state of the spraying disk shown in FIG.

FIG. 5 is a partial cross-sectional view showing a spraying disc of a conventional centrifugal spraying device.

FIG. 6 is a partial cross-sectional view showing a spraying disc of a conventional centrifugal spraying device.

FIG. 7 is a schematic view showing a centrifugal spray dryer.

FIG. 8 is a graph showing a particle size distribution of particles after spray drying.

[Explanation of symbols]

 1 ... Lower disc 2 ... Upper disc 3 ... Annular wall 4 ... Rotating shaft 5 ... Spraying hole 8 ... Stock solution supply pipe 9 ... Spraying disk 10 ... Spray drying Room 11 ... Hot air inlet 12 ... Product outlet 13 ... Exhaust pipe 14 ... Cyclone

Claims (1)

[Scope of utility model registration request] 1. A spraying disc comprising a plurality of spray holes formed in annular walls provided at peripheral portions of a lower disc and an upper disc, wherein at least the lower disc is placed downward with respect to a direction perpendicular to a rotation axis. A spraying plate for a centrifugal spraying device, which is inclined.