JPS6329580B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for jet granulation or coating of bodies.

It is known that the jet method is an excellent method for coating or granulating granules. For example, special public service in 1977
-13896 and Japanese Patent Publication No. 42-24281 disclose a granule coating method in which granules to be coated are placed in a jet state and a coating liquid is sprayed into the jet. In Japanese Patent Publication No. 38-2294, a guide pipe was installed in a tower with an inverted conical lower part, and a coating liquid was supplied from a spray pipe installed in the guide pipe to coat the granules or powder passing through the guide pipe in a suspended state. Discloses a device for doing so. Special Publication No. 53-47230, Special Publication No. 1973
-92715 discloses or suggests that a granulation device using a jet method is superior.

The present inventors have repeatedly developed particle coating and granulation methods that take advantage of these jet flow methods;
It has been found that it is extremely difficult to process large quantities using known knowledge. For example, the above-mentioned special public service
13896 and Japanese Patent Publication No. 42-24281, stable jet flow is possible in small-scale test equipment, but stable jet flow cannot be obtained in large-scale practical equipment, and coating and granulation are practically impossible. It turned out that it was impossible to operate. However, it was recognized that the use of a guide tube is useful for increasing the size of the jet method. In other words, as mentioned above, it is difficult to stabilize the jet stream due to the increase in size, but as a result of studies using a guide tube under a wide range of conditions, we found that even under conditions where no jet stream is formed when there is no guide tube, if there is a guide tube, it is difficult to stabilize the jet stream. The particles were blown upward through the guide tube from the lower part of the annular fixed layer around the guide tube, and it was possible to easily create a state similar to a so-called jet flow. As a result, it became possible to perform coating and granulation operations using large columns. However, despite these efforts, it has been found that the following problems occur when the diameter of the column is further increased or particles with adhesive properties are used. First, the amount of granules sent from the lower part of the jet tower to the guide pipe fluctuates, causing a so-called pulsation phenomenon, resulting in unstable operation. Otherwise, it may cause damage to the coating. The second problem was that a part of the annular fixed bed became stuck, making it impossible to circulate the particles uniformly, making it impossible to operate effectively. These problems can be solved by the method shown in Japanese Patent Publication No. 50-1355, that is, by feeding gas appropriately into the surrounding annular fixed bed and turning the fixed bed into a fluidized bed, or until the particles in the annular part become substantially weightless. Pulsation and sticking can be avoided by maintaining the gas flow rate, but the equipment is complicated and requires power to send a large amount of gas, and if a solvent is used in the coating liquid to recover it, It was found that there is a drawback that recovery is not easy because the concentration is diluted. Furthermore, in the case of continuous granulation while circulating the granules as shown in JP-A No. 53-92715, or in the case of batchwise coating operation, it is necessary to change the shape and particle size of the particles for each batch. It has been found that the flow rate adjustment of the gas sent to the peripheral annular portion is complicated and is therefore unsuitable for purposes of mass treatment.

An object of the present invention is to provide a coating or granulation device that prevents jet pulsation and solidification of the stationary phase and allows stable operation when coating or granulating a large amount using a jet method using a guide tube.

In the present invention, a tank having an inverted conical lower part is provided with a gas spout (hereinafter sometimes referred to as an orifice) into the tank at the lowest part thereof, and above the gas spout, the gas flows into the tank from the spout. A guide pipe is provided to conduct the gas blown up into the tank and the coating or granules to be granulated and grown in the tank. In an apparatus for coating or granulation in which a spray nozzle is provided near the center of or above the gas outlet, the spray nozzle is located in a fixed layer of the granules between the guide tube and the tank. , the gist of the device is that a member (hereinafter referred to as an obstacle member) is installed that obstructs the propagation of the pressure of the particles in the fixing tank but does not substantially prevent the particles from descending.

The fixed layer of granules is defined as a fixed layer of particles that accumulates outside the guide tube and in the tank and directs the particles that rise at a considerable speed together with the gas in the guide tube between the lower end of the guide tube and the tank. A layer of particles that used to gradually descend.

Although the tank having an inverted conical lower part is not particularly limited, a tank having an inverted conical lower part and a cylindrical upper part is preferable.

Although the shape of the guide tube is not particularly limited, it is preferably cylindrical, and examples thereof include a cylindrical tube, a hole formed therein, and a cylindrical wire mesh.

The obstruction member may take various forms. For example, a vertically arranged plate-like body (hereinafter referred to as a "buttful"), preferably arranged radially from the guide tube or concentrically with the guide tube on a horizontal section; a rod-like body, preferably one of the fixed layer located at the middle depth of the fixing tank, preferably arranged concentrically (in horizontal section) with the guide tube or radially from the guide tube; Examples include a guide tube or a plate-like body projecting from the inner wall of the tank into the fixed layer in the form of a skirt; a combination of individual examples of these; and the like.

The number, length, surface area, etc. of these obstruction members need to be selected appropriately depending on the size of the tank and the properties of the particles. If this is severe, as shown in FIG. 1, it is advisable to attach as many radially arranged buffles 3a as possible to the inverted conical portion of the tank as long as they do not impede the descent of the particles. In the case of granules that are sticky and have poor fluidity in the granule fixed layer, it is preferable that the buffle reaches the upper part of the granule fixed layer.

Next, a specific example of the device of the present invention will be shown with reference to the drawings.
FIG. 1 is a longitudinal sectional view of an example of the device of the present invention, FIG. 2 is a sectional view taken from FIG. 1, FIG. 3 is a longitudinal sectional view of another example of the device of the invention, and FIG. - sectional view, FIG. 5 is a longitudinal sectional view of another example of the device of the present invention, FIG. 6 is a - sectional view in FIG. 5,
FIG. 5A is a longitudinal cross-sectional view of another example of the device of the present invention;
Figure A is a cross-sectional view taken along the line AA in Figure 5A, Figure 7 is a longitudinal cross-sectional view of another example of the apparatus of the present invention, Figure 8 is a cross-sectional view taken from - in Figure 7, and Figure 7A is a cross-sectional view of another example of the apparatus of the present invention. FIG. 8A is a cross-sectional view taken along the line A-A in FIG. 7A, FIG. 9 is a schematic diagram of the entire equipment when granule coating or granulation is performed using the apparatus of the present invention, and FIG. 10 is a vertical cross-sectional view of the device of the present invention used in Example 2 shown below, and FIG.
FIG. In Figures 1 to 11, 1 is a tank with an inverted conical lower part, 2 is a guide tube whose central axis is common to the central axis of the tank, and 3a, 3b, and 3i.
3d, 3f, 3g and 3h are other obstruction members, 3 is an obstruction member in a comprehensive sense, 3c
3e is a support member for the obstacle member, 4 is an orifice, and 5 is a spray nozzle. In Figure 1, the inner diameter of the tank upper cylinder is 1500 mm, the guide tube inner diameter is 375 mm,
a is 562mm, b is 500mm, c is 1083mm, d is 450mm,
e is 230 mm, f is 250 mm, and g is 200 mm, and the buttfuls 3a are arranged radially in eight directions from the center of the tank so as to form equal angles to each other. In Fig. 3, the inner diameter of the upper cylinder of the tank, the inner diameter of the guide tube, a, b, f, and g are the same as those in Fig. 1, h is 150 mm, and i is 250 mm.
mm, j is 250mm, k is 100mm, l is 1150mm, m is
450 mm, and the center axis of Batsuful 3b is the same as the center axis of the tank. In Fig. 5, the inner diameter of the tank upper cylinder, the inner diameter of the guide tube, a, f, g, l, and m.
is the same as that in Figure 3, 3d is a circularly wound steel pipe with a circular cross section and an outer diameter of 50 mm, and is arranged so as to form a concentric circle with the tank upper cross section, and 3e is a circular cross section and its Steel pipes with an outer diameter of 50 mm are arranged radially in all directions from the center of the tank at equal angles to each other.
n is the distance between the centers of each tube, which is 100 mm, and p is the distance between the center of the outermost tube and the inner wall of the upper cylindrical portion of the tank, which is 150 mm. In Figure 5A, the tank upper cylinder inner diameter, guide tube inner diameter, a, f, g, l, and m are the same as those in Figure 3, and 3f is a steel pipe with an outer diameter of 25 mm with a center-to-center distance of 100 mm. Twelve pieces of metal plate-like plates are arranged vertically in a radial direction in eight directions from the center axis of tank 1, and are arranged at equal angles to each other. The distance q to the center of the steel pipe is 500 mm, and the distance r to the center of the steel pipe at the bottom end is 600 mm.
It is. In FIG. 7, the inner diameter of the upper cylinder of the tank, the inner diameter of the guide tube, a, f, g, l, and m are the same as those in FIG. , s is 700mm, angle θ is
30°, t is 160mm. In Figure 7A, the inner diameter of the upper part of the tank, the inner diameter of the guide tube, a, f, g, l and m.
is the same as that in Fig. 3, and 3h is a plate-shaped body projecting like a skirt from the cylindrical inner wall of the upper part of the tank.
u is 350mm and the angle is 45°. FIG. 9 is a schematic diagram of the overall equipment for granule coating or granulation using the apparatus of the present invention, in which 6 is a granule feed pipe, 7 is a granule input valve, 8 is an exhaust pipe, and 9 is the air supply pipe, 1
0 is an air heater, 11 is a flow meter, 12 is an air blower, 13 is an adjustment tank for coating liquid or granulation raw material liquid,
14 is a supply pump for coating liquid or granulation raw material liquid; 1
5 is a supply pipe for coating liquid or granulation raw material liquid, 16 is a granule discharge port, 17 is a granule extraction pipe, and 18 is a granule extraction valve. In Figure 10, the inner diameter of the tank upper cylinder is 200 mm, the guide tube inner diameter is 375 mm, v is 807 mm,
w is 1515mm, x is 615mm, y is 287mm, f is 250mm,
g is 200 mm, and the buttfuls 3i are arranged radially in eight directions from the central axis of the tank so as to make equal angles to each other.

The apparatus for coating or granulation of the present invention includes a top plate and a gas outlet in the upper part of the tank, a granule input pipe and a granule input valve provided therein on the tank wall above the granule fixing layer, and a granule input valve provided therein, It may have a gas supply pipe leading to the jet nozzle, a granule discharge port provided below the gas jet nozzle of the gas supply pipe, and the like. Further, for continuous operation, a granule extraction pipe and a granule extraction valve provided therein may be provided on the tank wall at the height of the upper end of the granule fixed bed.

Although the reason why the device of the present invention is so effective is not clear, it is assumed to be as follows. In other words, when the jet device is made larger, the amount of granules packed increases, and the load pressure applied to the granules increases, so when there is no guide tube, the jet air column formed on the orifice is crushed, and as a result, It starts bubbling. If a guide tube is installed above the orifice, the guide tube can support the load caused by the particles and prevent the jet air column from being crushed, but it cannot reduce the load applied to the fixed layer of particles between the guide tube and the tank. As a result, pressurization or cross-linking of the granules occurs, causing the granules to stick and impair fluidity, and the supply to the jet section becomes irregular and pulsates. It is presumed that the obstruction member of the apparatus of the present invention reduces the load pressure applied to the granule fixing layer, prevents granules from sticking, and improves the circulation of the granules.

By using the apparatus of the present invention, pulsation and caking in granule circulation can be prevented, and the jet flow method facilitates granulation and coating in large quantities. The device of the present invention is particularly necessary for large-scale mass production equipment with a diameter of 1 m or more, but it is also effective for granulation or coating of small particles of about 1 mm, or for coating where adhesion is a problem, even when the diameter is less than 1 m. be.

Examples of the present invention are shown below, but the present invention is not limited thereto.

Example 1 Coating was carried out using the overall equipment for granule coating shown in FIG. 9 as described below. However, as the coating device 20 in the figure, the granule extraction pipe 1
7 and the extraction valve 18 (indicated by dotted lines) were used, and the shape and dimensions shown in FIGS. 1 and 2 were used. 1500kg of granular urea with a diameter of 2.5mm
The granules were placed in a tank and circulated while passing hot air at 4000Nm ³ /hr, and after the temperature of the granules reached 70℃, 2 parts of polyethylene (by weight) and 3 parts of ethylene-vinyl acetate copolymer (by weight) were added. , 2500 kg of a hot solution of 100℃ consisting of 95 parts of tetrachlorethylene (same) in 110 minutes.
supplied. During this time, the hot air temperature was controlled so that the particle temperature was maintained at 70°C. During the coating operation, the circulation of granules was constant and stable operation was possible. After the supply of the hot solution was finished, the jet flow was continued for about 5 minutes, and then the hot air was stopped and the coated granular urea was extracted.

The uniformity of the coating of the obtained coated urea was examined as follows. That is, 100 coated grains were arbitrarily selected, the weight of each grain and the weight of its coating were determined, and the average coverage ( ) and its standard deviation (σ) were determined, and the results were 8.25% and σ = 1.05. Another 3 days
The dissolution rate in water at 25°C was 2.8%.
These results are excellent values for coated fertilizers.

Comparative Example 1 A coating operation was carried out under the same conditions as in Example 1, except that the baffle in the coating apparatus used in Example 1 was removed.

A slight pulsation phenomenon (a phenomenon in which particles were blown up intermittently) was observed in the circulation when the particles were introduced, but this decreased once coating started. Coating liquid supply started 20
After a few minutes, the circulation rate gradually decreased, and by the time the coating was finished, it had decreased to about half of its original value. The hot air was stopped and the gas was extracted from the outlet, but only about 1/3 of the amount had leaked out. An examination of the inside of the tank revealed that about half of the liquid had become stuck and had lost its fluidity. The fixation was such that when the particles were taken out and a weak force was applied, they separated into single particles, but since they had lost their fluidity, the necessary coating was not applied. The one that leaked had more coverage than necessary. As a result of uniformly mixing both and measuring various properties in the same manner as in Example 1, the average coverage was 7.9%.
The standard deviation was 4.8%, and the dissolution rate in water over 3 days was 56%. This is poor as a coated fertilizer.

Example 2 Urea melt was granulated as described below using the overall granulation equipment as shown in FIG. However, the granulation device 20 in the figure is equipped with a granule extraction pipe 17 and an extraction valve (shown by dotted lines), and has the shape shown in FIGS. 10 and 11.
(with dimensions) was used. Furthermore, a sieve is connected to the granule extraction pipe 17, and the undersized particles coming out of the sieve are passed through the granule input pipe 6, and the oversized particles are coarsely crushed and particularly fine particles are removed and passed through the granule input pipe. 6 and returned to the tank.

In order to obtain a product size of 7 to 9 mesh, the wire mesh of the sieve was set to 7 to 9 mesh, and 600 kg of 9 to 12 mesh urea granules, which will become the core in the tank, was put into the tank, and the product was sieved from the orifice.
Blow out air at 4000Nm ³ /hr to circulate the particles,
Urea melt is supplied at 1400Kg/hr from the spray nozzle, and 5000Kg/hr of granules are extracted from the tank through overflow and sieved using a sieve. Undersize particles are left as they are, and oversize particles are returned to the tank after coarse crushing. Granulation was continued.

The operation is extremely smooth and we are producing good quality granular urea.
I was able to make it at 1300Kg/hr.

Comparative Example 2 A granulation operation was carried out under the same conditions as in Example 2, except that the baffle of the granulation device 20 used in Example 2 was removed.

As a result, the circulation inside the tank was not uniform, and due to the pulsation phenomenon, cracking and powdering of the granules were noticeable.
In the tower, Batsuful was found to be extremely effective.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an example of the device of the present invention, FIG. 2 is a sectional view taken from FIG. 1, FIG. 3 is a longitudinal sectional view of another example of the device of the invention, and FIG. 5 is a vertical sectional view of another example of the device of the present invention, and FIG. 6 is a sectional view of FIG.
Figure A is a longitudinal cross-sectional view of another example of the device of the present invention, Figure 6A is a cross-sectional view taken along line AA in Figure 5A, Figure 7 is a vertical cross-sectional view of another example of the device of the present invention, and Figure 8 is a cross-sectional view of another example of the device of the present invention. 7A is a vertical sectional view of another example of the device of the present invention, FIG. 8A is a sectional view taken along line A-A in FIG. 7A, and FIG. Or a schematic diagram of the overall equipment when performing granulation, No. 10
The figure is a longitudinal sectional view of the device of the present invention used in Example 2, and FIG. 11 is a sectional view taken along line XI-XI in FIG. 1st~
In FIG. 8, support members for guide tubes, buttholes, and other obstruction members (excluding support members for obstruction members in FIGS. 3, 4, 5, and 6) are omitted from illustration. In these figures, the numbers indicate the following: 1: Tank with inverted conical bottom, 2: Guide tube, 3
a, 3b, 3i: Batsuful, 3d, 3f, 3g,
3h: Obstacle member other than the buttful, 3: Obstruction member in a comprehensive sense, 3c, 3d: Support member for the obstacle member, 4: Orifice, 5: Spray nozzle, 6: Granule input pipe, 7: Granule input valve , 8: Exhaust pipe, 9:
Air supply pipe, 10: Air heater, 11: Flow meter,
12: Air blower, 13: Coating liquid (or granulation raw material liquid) preparation tank, 14: Coating liquid (or granulation raw material liquid) supply pump, 15: Coating liquid (or granulation raw material liquid) supply pipe, 16: Granules body discharge port, 17: granule extraction pipe, 18: granule extraction valve.

Claims (1)

[Scope of Claims] 1 The present invention provides a tank having an inverted conical lower part, and a gas outlet (hereinafter sometimes referred to as an orifice) into the tank is provided at the lowest part of the tank, and a gas outlet is provided above the gas outlet. ,
A guide pipe is provided to conduct the gas spouted into the tank from the jet port and the coating or granules to be granulated and grown in the tank blown up by the gas, and a guide pipe for making the coating liquid or the granules grow. A fixed layer of the granules between the guide pipe and the tank in a coating or granulation device in which a spray nozzle for spraying the material is provided near the center of or above the gas outlet. In the middle of the
The device as described above is provided with a member (hereinafter referred to as an obstacle member) that obstructs the propagation of the pressure of the particles in the fixing tank but does not substantially prevent the particles from descending. 2. The device according to item 1, wherein the obstacle member is a plate-shaped body arranged vertically. 3. The device according to item 2, wherein the plate-like body is arranged radially from the guide tube. 4. The device according to item 2, wherein the plate-shaped body is arranged concentrically with the guide tube on a horizontal cross section. 5. The device according to item 1, wherein the obstacle member is a rod-shaped body. 6. The device according to claim 5, wherein the rod-shaped body is arranged radially from the guide tube. 7. The device according to item 5, wherein the rod-shaped body is arranged concentrically with the guide tube in a horizontal section. 8. The device according to claim 1, wherein the obstruction member is a plate-like member extending in a skirt shape from the guide tube. 9. The device according to claim 1, wherein the obstruction member is a plate-like member projecting like a skirt from the inner wall of the tank.