JPH0975997A - Granulation method for dehydrated cake, etc. and granulation apparatus used therefor - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To effectively utilize an object to be treated such as a dehydrated cake, to make it possible to produce agricultural and horticultural soil with high quality and high product yield. SOLUTION: A kneading step of kneading an object to be treated such as a dehydrated cake with a kneader 2, a granulation step of granulating the kneaded object to be treated with a granulator 7, and a dryer of the granulated object to be treated. twenty four
And a drying step of drying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for granulating a dehydrated cake or the like, by which an object to be treated such as a dehydrated cake or the like can be effectively used to obtain high-quality agricultural and horticultural soil, and a granulating apparatus used therefor. .

[0002]

2. Description of the Related Art Conventionally, for example, most of the sludge generated from a water purification plant is mechanically dehydrated to form a cake, or is sun-dried before being landfilled, but it is becoming difficult to secure the landfill site year by year. In addition, since the transportation cost thereof has been soaring, in recent years, for example, agricultural and horticultural soil has been produced by granulating dehydrated cake, and its effective use has been achieved.

As such a granulating means, there is a conventional one using, for example, a kneader, which kneads the dehydrated cake that has been put in, and then sends it out by a screw conveyor and a perforated plate or the like provided at its discharge port. It is extruded from a wire mesh and granulated. In addition, as another means, there is one that granulates while drying the dehydrated cake with a dryer.

[0004]

However, since the former means is granulation by crushing and extrusion, the granulated product cannot be rounded and is used as agricultural and horticultural soil. Then, there is a problem that the roots are damaged, and an aggregate structure having a desired particle size cannot be obtained,
There is a problem that the product yield cannot be secured. Here, the aggregate structure refers to a state in which some particles are fused to form a lump of particles. In addition, the porous plate or the wire mesh is likely to be clogged, so that the workability is poor.

Further, in the latter method, since the dehydrated cake is easily pulverized, the product yield is low as in the former method,
In addition, a large amount of dust is generated due to pulverization, and therefore a treatment facility such as a dust collector is required. Further, it is difficult to reuse it as agricultural and horticultural soil as it is, and a device for sieving is additionally required for reuse, and there is a problem that it is not practical.

[0006] Therefore, the present invention has been made to solve the above-mentioned conventional problems, and in order to effectively utilize an object to be treated such as a dehydrated cake, the agricultural and horticultural soil having a high quality and a high product yield. It is an issue to be able to manufacture such products.

[0007]

[Means for Solving the Problems] That is, the means adopted by the present invention for solving the above-mentioned problems are as follows: a kneading step of kneading an object to be processed such as a dehydrated cake by a kneader 2 and a kneading object to be processed. The point is that the granulation step of granulating by the granulator 7 and the drying step of drying the granulated object to be treated by the dryer 24 are separate steps.

The granulating apparatus according to the present invention is characterized by a kneading machine 2 for kneading an object to be processed such as a dehydrated cake and a granulating object to be processed kneaded by the kneading machine 2. It is composed of a granulator 7 and a dryer 24 for drying an object to be treated granulated by the granulator 7.

Therefore, in the granulating method and the granulating apparatus having the above-mentioned constitution, the dehydrated cake or the like to be treated is first put into the kneading machine 2 and finely crushed and simultaneously kneaded. It is inserted and softened, and is sent to the granulator 7 in a state where it is easy to granulate. Then, the granulator 7 granulates particles having an agglomerate structure having a desired particle diameter and sends them to the dryer 24, and the particles are dried to a predetermined water content by the dryer 24 while maintaining their shape. Agricultural and horticultural soil will be manufactured.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a dehydrator such as an electroosmotic dehydrator capable of dehydrating sludge generated from a water purification plant. Reference numeral 2 denotes a kneader in which a trough 4 communicating with the hopper 3 is horizontally arranged as shown in FIG. 2. The trough 4 is internally provided with a screw 6 which is rotationally driven by an electric motor 5.

Reference numeral 7 denotes a roller 8 having a plurality of outer peripheral surfaces as shown in FIG.
A horizontal cylindrical drum 9 rotatably supported by a V-pulley 1 by a motor 10 arranged in the axial center of the drum 9.
Granulation consisting of a rotary shaft 14 that can be driven to rotate in both forward and reverse directions via 1, 12 and a V-belt 13, and blades 15 protruding in a cross shape on the outer peripheral surface of the rotary shaft 14 at a predetermined interval. It is a machine. A predetermined gap is provided between the tip of the blade 15 and the inner wall surface of the drum 9.
The size of the particles to be granulated is adjusted by appropriately changing the width of the gap 16. The blade 15 of the present embodiment
Is a paddle blade, but the applicant of the present invention has confirmed that if a scraper (scraping blade) is installed, even if the blade 15 that is not a paddle type stirring blade is used, some granulation effect can be obtained.

Reference numeral 17 denotes a jacket provided on the outer peripheral surface of the drum 9, and a pipe 18 capable of introducing steam is connected to the jacket 17 so that the inner wall surface of the drum 9 can be indirectly heated. Has been done. Reference numeral 19 is a sprocket externally fitted to the outer peripheral surface of the drum 9, and a chain 21 is stretched between the sprocket 19 and the motor 20 to rotate the drum 9. 22 is a hopper provided on the drum 9, and 23 is a chute from which the granulated particles are discharged.

Reference numeral 24 denotes a horizontal cylindrical rotary type dryer which is rotationally driven by a motor 23. As shown in FIG. 4, a plurality of tubes 25 into which steam is introduced along the axial direction are arranged on the inner wall surface of the dryer. It is configured to indirectly heat the inside,
The dryer 24 includes a hopper 26 and a chute 27, respectively. In FIG. 1, 28 is a steam heater for introducing steam into the tube 25 of the dryer 24, and the steam introduced into the steam heater 28 is raised to a constant temperature and blown by the blower 29 into the tube.
Sent to 25. Incidentally, the dryer 24 in the present invention is not limited to this, and the point is that the dryer 24 does not have a structure for crushing or crushing particles, as long as it can dry solid matter. Good.

This embodiment has the above-described configuration.
Next, a case of using this to produce agricultural and horticultural soil from sludge will be described.

First, after the sludge is dehydrated by the dehydrator 1, the dehydrated cake is put into the hopper 3 of the kneader 2 by the conveyor 30 as shown in FIGS. 1 and 2, and the dehydrated cake is rotated by the screw 6 in the trough 4. Is sent to the discharge side while being kneaded. At that time, the plate-shaped dehydrated cake is finely crushed and, at the same time, it is kneaded and softened due to the thixotropy phenomenon (a phenomenon in which water appears on the surface when pressure is applied), and kneaded in a particle state suitable for granulation It will be discharged from the machine 2.

Since the kneading machine 2 does not have a perforated plate or a wire net, it does not have a problem that particles are clogged, and the overall structure is simple.

Then, the discharged particulate dehydrated cake is put into the drum 9 of the granulator 7 from the hopper 22 as shown in FIG. The drum 9 and the blade 15 of the granulator 7
The rotating shafts 14 having the above are driven to rotate by motors 20 and 10, respectively, and steam is introduced into the jacket 17 to heat the inner wall surface of the drum 9 to a constant temperature.

The particles of the dehydrated cake charged into the drum 9 are agitated by the rotating blades 15 while being indirectly heated while rolling on the inner peripheral wall of the drum 9 by the rotation of the drum 9 and granulated. According to the test conducted by the applicant of the present invention under various granulation conditions, the granulation conditions and the particle size and particle size distribution of the granulated particles are as follows. It was confirmed that they have a good relationship.

First, by rotating the drum 9, moisture floats on the surface of the particles to facilitate the growth of the particles, and an aggregate structure is formed. In this case, since the particles grow as the number of rotations of the drum 9 increases, the particles become larger and the particle size distribution diffuses. Further, when this number of rotations reaches the critical number of rotations, the particles go around with the drum 9, so that the particles do not grow.

Here, when steam is introduced into the jacket 17 of the drum 9 to heat the inner wall surface of the drum 9, the viscosity of the particles becomes lower and becomes softer due to the temperature rise, so that the granulation is easy and the residence time is long. Since the processing capacity is higher than that of an ordinary drum granulator that does not have a heating function,
The granulator 7 can also be small. Further, due to the temperature rise in the drum 9, the moisture on the surface of the particles evaporates, and the moisture evaporates into a saturated vapor state in the drum 9. Therefore, the particles easily adhere to each other, promoting the growth of the particles and pulverizing The number of fine particles that cause is very small. Further, since the water on the surface of the particles in contact with the inner wall surface of the drum 9 evaporates, the particles do not adhere to the inner wall surface and the critical rotation speed of the drum 9 increases, so that the high speed rotation causes the blade 15 to rotate. The effect of stirring and granulation due to rotation is easily obtained, granulation can be performed in a short residence time, and the granulator 7 can be downsized.

That is, by increasing the number of rotations of the drum 9 and heating the inner wall surface of the drum 9, the viscosity of the particles is lowered, the particles are easily granulated by the blades 15, and the evaporation of water on the particle surface is increased. The particle growth is suppressed and the particle size distribution is concentrated. On the other hand, when the rotation speed is reduced, the particle size distribution diffuses.

As described above, when the rotation speed of the drum 9 is increased and the heating temperature of the drum 9 is increased, the growth of particles is small and the particle size distribution is concentrated. On the contrary, when the heating temperature is decreased, or When the number of rotations of the drum 9 is reduced, it is possible to suppress the particle size to a certain degree without enlarging the particles, and to promote the agglomeration having a proper particle size distribution.

Further, when the drum 9 and the blades 15 are rotated in the same direction (normal rotation), the rolling distance of the particles in the drum 9 becomes large, so that the growth of the particles is promoted and the particle size becomes large. Then, the particle size distribution tends to diffuse, and when the particles are rotated in the opposite direction (reverse direction), the crushing effect by the blades 15 is promoted, so the particle growth is suppressed and the particle size becomes smaller. The distribution will be concentrated.

Further, the residence time of the particles in the drum 9 affects the growth of the particles, but if the residence time is excessively long, the particles grow too much. Therefore, granulation should be performed with an appropriate residence time. Is desirable.

From the above results, when it is desired to diffuse the particle size distribution of the particles, for example, the blade 15 and the drum 9 are rotated in the same direction (forward rotation) at a low rotation speed of about 30 rpm, and the steam pressure is adjusted. It can be seen that the formation of the aggregate structure is promoted by lowering the temperature of the inner wall surface of the drum 9 to be slightly lower and performing granulation.

On the other hand, when it is desired to obtain particles having a concentrated particle size distribution, for example, the blade 15 and the drum 9 are rotated in the opposite directions (reverse rotation) at a rotation speed of about 60 rpm, and the steam pressure is increased. The temperature of the inner wall surface of the drum 9 may be set to a slightly higher temperature for granulation.

By performing the granulation and the kneading in separate steps in this way, it is possible to promote the spheroidization of the particles, and at the same time, in the granulation step, the rotational speeds and rotational directions of the drum 9 and the blades 15, the gap 16 By appropriately changing the width, the vapor pressure, the residence time, etc., it is possible to obtain particles having an aggregate structure having a particle size according to the purpose of use with a desired particle size distribution.

Further, since the particles are indirectly heated by the steam in the jacket 17, the amount of the particles adhering to the inner wall surface of the drum 9 is small, and the hot air is directly supplied into the drum 9. Compared with, the thermal efficiency is good and the amount of heat used is small.

The particles having the aggregate structure granulated to the desired particle size by the granulator 7 are rotatably driven from the chute 23 of the hopper 26 of the dryer 24 as shown in FIGS. 1 and 4. Is loaded into the container via the conveyor 31. After that, the particles roll in the dryer 24 while being indirectly heated, and when the water content reaches a predetermined content, the particles are discharged from the chute 27 to the conveyor 32, and the production of agricultural and horticultural soil is completed.

Thus, by performing the drying as a separate step from the granulation, the powdering rate of the particles is greatly reduced and the product yield is also improved.

Further, since the dryer 24 adopts the indirect heating system, it has the advantages that the thermal efficiency is better than the direct heating system and the running cost can be reduced.

The agricultural and horticultural soil produced in this manner is excellent in water permeability and water retention because it has an aggregated structure with a particle size distribution peaking at a particle size of 0.5 to 3 mm. Since the holding power of the soil is also good, microorganisms can easily inhabit and the soil can be organized. Further, such an aggregate structure has an advantage that it is difficult to be pulverized even if it breaks, and therefore the air permeability is maintained and root rot hardly occurs, which is the most suitable as agricultural and horticultural soil. The particle size distribution generally required for agricultural and horticultural soil is as follows. That is, 0.5 to 3 mm for culture soil, 1 to 3 mm for soil, 1 to 7 for gardening.
mm. The particle size distribution of the present embodiment was 0.5 to 3 mm, but by adjusting the gap 16 between the inner wall surface of the granulator 7 and the blade 15, other particle size distributions, for example, according to the above-mentioned application can be obtained. It is also possible to obtain agricultural and horticultural soil having a desired particle size distribution.

In the above embodiment, the case of producing agricultural and horticultural soil by using the cake dehydrated by the dehydrator 1 as the object to be processed has been described, but the present invention is not limited to this, and other It is also possible to treat the object to be treated according to the present invention to produce something other than agricultural and horticultural soil.

Further, the kneading machine 2 and the granulating machine 7 are not limited to those in the above-mentioned embodiment, and their specific configurations can be arbitrarily changed within the scope intended by the present invention.

[0036]

As described above, according to the present invention, kneading and granulation are performed in separate steps, so that the particles can be spheroidized as compared with the case of extrusion granulation by a conventional kneader. In addition, since granulation and drying are performed in separate steps, the powdering rate of the particles can be greatly reduced and the product yield can be improved compared with the conventional one in which both steps were performed by the dryer. It has come to obtain a special effect that can be done.

Further, in the granulating step, when the material to be treated is rolled in the drum of the granulator and agitated by the blades rotating in the drum to perform the granulation, the rotation of the drum and the blades is prevented. By properly changing the number, the direction of rotation, the gap between them, the residence time, etc., the unique effect of being able to granulate particles with an aggregate structure having a particle size according to the intended purpose with a desired particle size distribution is obtained. If granulation is performed while the obtained object is further indirectly heated, the particle size and particle size distribution can be adjusted more easily by appropriately changing the heating temperature.

Further, as described above, the granulating apparatus according to the present invention has the following advantages as compared with the conventional apparatus in which the kneading machine granulates or the dryer granulates.

That is, since a sieving device for pulverized particles and dust is not required, the dust collector can be downsized, and the amount of water for rinsing the dust collected is small and the amount of drainage is small. , The drainage system can be downsized.

Further, according to the present invention, since heating is performed by the granulator, the dryer does not require large heating, and the dryer can be small in size.

Therefore, the structure of the entire apparatus is very simple, and the practical effect that the manufacturing cost can be reduced can be obtained.

[Brief description of drawings]

FIG. 1 is an overall explanatory view showing an embodiment of the present invention.

FIG. 2 is a front view of the kneading machine including a partial cutout.

FIG. 3 is a front view of the granulator including a partial cutout.

FIG. 4 is a front view of the dryer including a partial cutout.

[Explanation of symbols] 2 ... Kneader 7 ... Granulator 9 ... Drum 14 ... Rotating shaft 15 ... Blade 16 ... Gap 17 ... Jacket 24 ... Dryer

Claims (8)

[Claims] 1. A kneading step of kneading an object to be treated such as a dehydrated cake with a kneader (2) and a granulator for the object to be kneaded.
(7) A granulating method for a dehydrated cake or the like, which comprises a granulating step of granulating and a drying step of drying the granulated object by a dryer (24). 2. In the granulating step, the material to be processed is indirectly heated in the drum (9) of the rotating granulator (7) while being rolled, and while the material is being rolled in the drum (9). The method for granulating a dehydrated cake or the like according to claim 1, wherein granulation is carried out by stirring with a rotating blade (15). 3. The method for granulating a dehydrated cake or the like according to claim 1, wherein in the drying step, the object to be treated is indirectly heated while being dried. 4. A kneading machine (2) for kneading a processed material such as a dehydrated cake, and a granulating machine (7) for granulating the processed material kneaded by the kneading machine (2). And a dryer (24) for drying an object to be treated which has been granulated by the granulator (7). 5. A horizontal cylindrical drum (9) in which the granulator (7) has an indirect heating means for indirectly heating the inside and is rotationally drivable, and a shaft in the drum (9). The rotary shaft (14) which is arranged in the direction of rotation and is driven to rotate, and the blade which is provided on the rotary shaft (14) and whose tip has a gap (16) between the inner peripheral walls of the drum (9). (15) The granulating apparatus for dehydrated cake and the like according to claim 4, comprising: 6. The granulating apparatus for dehydrated cake or the like according to claim 5, wherein the rotary shaft (14) is configured to be rotatable both in forward and reverse directions. 7. The dehydrated cake or the like according to claim 5, wherein the indirect heating means of the drum (9) is steam introduced into a jacket (17) provided on an outer peripheral surface of the drum (9). Granulator. 8. A granulating apparatus for dehydrated cake or the like according to claim 4, wherein said dryer (24) is provided with an indirect heating means.