JPS61133132A - Perforated plate in fluidized bed granulator - Google Patents

Abstract

PURPOSE:To decrease dispersion of particles of a granulated product by increasing the diameter of perforations within a specified range at the peripheral part of a perforated plate or by enlarging the open area ratio at the peripheral part as compared to that of the inside part within a specified range by increasing the density of the perforation. CONSTITUTION:The open area ratio at the peripheral part 13 of a perforated plate 11 is increased by >=20-50% as compared to the open area ratio of the perforated plate at the inside part by enlarging the diameter of the perforation 12 within a range of the breadth corresponding to 5-15% of the diameter of the perforated plate 11, at the peripheral part 13, or by increasing the density of the perforation so as to increase the amt. of hot air blown up from the part to a fluidization chamber 1. In this case, distribution of the hot-air at the peripheral part 13 of the perforated plate 11 is not always necessary. It is preferred that the perforations 12 are opened toward somewhat outside direction to blow up the hot air toward the outside. It is also preferred that a part of the hot air is blown rather along the inside wall surface of a conical fluidized tank.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a perforated plate for a continuous flow granulator, and is particularly characterized in that the aperture ratio of the peripheral portion of the perforated plate is larger than that of the inside.

A continuous flow granulator uses a perforated plate attached to the bottom of a cone-shaped fluidized tank to form a fluidization chamber, and hot air is blown up from the perforated plate towards the flow chamber to fluidize the powder and granules in the flow chamber. After that, a binder liquid is sprayed onto it. The one shown in Fig. 3 is an example, and the reference numeral 1 in Fig. 1 indicates a flow chamber;
2 is a spray chamber, 3 is a dust collection chamber, and 4 is a hot air supply chamber. These are similar to ordinary continuous fluidized bed granulators of this type, and the fluid chamber 1 has a bulging middle part to form a so-called cone-shaped fluidized tank 14, and the bottom surface is formed by a perforated plate 6. In addition, a hot air supply duct 5 is connected to the hot air supply chamber 4 and blows hot air at an appropriate temperature into the flow chamber 1. The spray chamber 2 is an area for spraying a binder or a coating agent onto the powder and granules forming a fluidized bed in the fluidization chamber 1, and is equipped with a spray nozzle 7 facing the fluidized bed. supply duct IO
is installed. The dust collection chamber 3 is for collecting powder particles that fly up as fine powder, and a bag filter 8 is attached thereto. Although not shown, the exhaust duct 9 is equipped with a flow rate regulating damper as well as a temperature or humidity detector, which controls the temperature and humidity of the hot air supplied from the hot air supply duct 5. It looks like this. Reference numeral 15 denotes a take-out port through which the granules granulated or coated in the flow chamber 1 are continuously taken out of the machine. A continuous dryer 16 is connected to the outlet 15, and the granules discharged from the outlet I5 are supplied to the continuous dryer 16. Here, the continuous dryer 16 is not particularly limited. In short, any material that can dry the granules continuously is sufficient. The figure shows a horizontal continuous fluidized bed dryer as an example, and the outlet 15 is connected to the fluid chamber 18 of the continuous dryer 16 via a screw conveyor 17. After being discharged, it immediately enters the flow chamber 18 and is dried by the hot air blown up from the ventilation plate 19, and is discharged from the discharge port 20.

By the way, in a continuous flow granulator, it is important that the powder and granules flow uniformly within the flow chamber 1 in order to obtain a uniform product. However, in the conventional continuous flow granulator, as shown in Fig. 4, the powder P accumulates on the periphery of the bottom of the flow chamber 1 and loses fluidity, resulting in variations in the particle size of the product granules. As the size increases, the discharge amount by the continuous discharge device also fluctuates.

This is because conventionally, in order to uniformly fluidize the powder and granules in the fluidization chamber 1, it was necessary to make the upward flow of hot air in the fluidization chamber 1 uniform, and for this purpose, the perforated plate plate 6 was This is because it was thought that it was necessary to open the ventilation holes 12 uniformly.

However, in granulation work, when a binder liquid is sprayed onto a fluidized powder, the powder with the binder liquid attached becomes heavier and descends.
Even if the upward flow W in the fluidization chamber 1 becomes a uniform laminar flow (see Fig. 4 (a)) and the powder or granules in the chamber become completely fluid, if the binder liquid is sprayed onto this powder or granules, Powder P
More of the liquid will fall around the periphery of the flow chamber 1 (see FIG. 4 (b)). Therefore, a circulating flow of powder and granules from the center toward the periphery occurs.

In particular, in actual granulation work, the upward flow of hot air is small near the inner wall surface of the cone-shaped fluidized tank 14, so the descending powder and granules slide down along the inner wall surface. Moreover, because the conventional perforated plate 6 did not have ventilation holes in the peripheral part, or had ventilation holes in this part as well as the inside,
Since the upward flow around the periphery of the flow chamber 1 is smaller than that inside,
The powder slides down along the inner wall surface of the cone-shaped fluidized tank 14, reaches the perforated plate 6, and is gradually deposited (see FIG. 4(c)).

The present invention temporarily improves the perforated plate of the above-mentioned conventional continuous flow granulator, and increases the aperture ratio of the vents at the peripheral edge of the perforated plate compared to the inside, thereby reducing the upward flow of hot air around the periphery of the flow chamber. The amount is increased from the inside, thereby substantially uniformizing the fluidity of the powder and granules, thereby reducing the variation in particles of the product granules.

The present invention will be specifically described below based on illustrated embodiments.

In the figure, numeral 11 is a perforated plate, and 12 is a ventilation hole.
The perforated plate 11 itself is similar to a normal plate of this type, and is formed using a thin steel plate or the like, and constitutes the bottom surface of the flow chamber 1.

The ventilation hole 12 is also a hole for blowing up hot air toward the flow chamber 1, similar to the conventional one.

Therefore, there are no particular limitations on its shape, size, or aperture ratio, but the hole diameter may be increased or By increasing the density of the pores, the aperture ratio of that part is increased by 20 to 50% or more than that of the inner part, and the amount of hot air blown from this part towards the flow chamber 1 is increased. be.

In this case, the hot air does not necessarily need to be blown up vertically at the peripheral edge 13 of the perforated plate. For example, as shown in Fig. 2, it is desirable to open the vent hole 12 in this area slightly outward to blow the hot air outward, and rather, a part of it is directed toward the inner wall of the cone-shaped fluidized tank. It is desirable to have the air blow up along the same direction.

As detailed above, the present invention makes the aperture ratio of the peripheral part of the perforated plate of the continuous flow granulator larger than the aperture ratio of the inner part thereof, and the amount of hot air blown from this part toward the flow chamber 1. It is a large number of Therefore, in the flow chamber 1, an irregular upward flow occurs between the inside and the surrounding area, and this irregularity tends to eliminate the tendency for powder and granules that are sprayed with the binder liquid and descend to adhere to the bottom of the peripheral wall of the flow chamber and stagnate. However, in the end, the powder and granules are evenly stirred in the fluidization chamber 1, and the entire fluidization chamber 1 becomes almost uniformly fluidized, so that uniform product granules are always sent to the drying device for the next process. I can do it. That is, a uniform granular product can be obtained in high yield.

As mentioned above, the present invention has a remarkable effect when applied to a continuous flow granulator, but a considerable effect is also expected when applied to a perforated plate of a fluidized tank of a single-batch flow granulator. Because it is.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views showing one embodiment of the present invention,
FIG. 3 is a longitudinal sectional view showing a continuous flow granulator, and FIG. 4 is a longitudinal sectional view showing a conventional continuous flow granulator in use. 14; Cone-shaped fluidized tank 11; Perforated plate Plate 12;
Air opening 13; Peripheral part: i′, τ°”t゛′ −≧r Figure 4 (A) (B)

Claims (1)

[Scope of Claims] In a perforated plate for a continuous flow granulator, which is formed by extending a perforated plate on the bottom of a cone-shaped fluidized tank, at least 5 to 15 mm of the diameter of the perforated plate is formed at the peripheral edge of the perforated plate. % or increase the perforation density to make the aperture ratio of that part 20 to 20% higher than the internal aperture ratio.
A perforated plate for a continuous flow granulator, characterized in that it is made larger by 50% or more so that more hot air can be blown up around the periphery of the flow chamber.