JP2651739B2 - Method and apparatus for sieving powders - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for sifting powders such as flour and spices,
That is, the present invention relates to a method and an apparatus for sieving.

[Conventional technology]

Powders and granules such as flour and spices are obtained by pulverizing raw materials with a roll machine or a high-speed pulverizer or the like, and the obtained powders and granules are appropriately sieved and classified with a shifter to obtain a product.

By the way, in the case of some spices such as flour and turmeric, the temperature of the raw material increases during the pulverization process, and the high-temperature powder obtained after the pulverization process has an increased binding property and a reduced fluidity. Conventionally, in order to classify the powders and granules, the powders and granules having reduced fluidity after the pulverization were directly applied to a shifter.

[Problems to be Solved by the Invention] In the above-mentioned sieving, problems such as sieving operation being unable to be performed due to poor flowability of the granular material clogging the eyes of the shifter frequently occurred. In this case, the eyes of the shifter must be replaced,
The procedure becomes complicated and the quality of the granular material deteriorates. Further, when sieving is performed after waiting for the temperature of the granular material to decrease, the productivity is low and the quality of the granular material is not preferable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for sieving powders and granules whose binding properties have been increased and flowability has been reduced by a pulverization process, without clogging of a shifter, etc. It is to provide a method and an apparatus.

[Means for solving the problem]

According to the present invention, due to a rise in the temperature of the powder during the pulverization, the powder after the pulverization, in which the binding property is increased and the fluidity is reduced, after cooling to a state where the fluidity is obtained, There is provided a method for sieving a powder, characterized by sieving.

Further, according to the present invention, a cooling device in which a rotary heat transfer tube provided with a cooling jacket is provided inside a hollow having a stirring member around a rotation axis at a bottom portion of a main body, and a cooling jacket is provided on a side wall and a bottom wall of the main body. And a sifter connected downstream of the sifter.

[Action]

ADVANTAGE OF THE INVENTION According to this invention, the granular material which fluidity fell by the temperature rise of the granular material by a pulverization process produces fluidity in a granular material by a cooling process and a stirring process, thereby increasing a heat transfer rate. Thus, efficient cooling can be achieved, and at the same time, the evaporated water can be quickly diffused. Therefore, the pulverized material whose binding property has been increased and the fluidity has been reduced by the pulverization treatment can be efficiently sieved without clogging of the shifter or the like.

〔Example〕

Hereinafter, an apparatus for sieving a granular material according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the cooling device 1 includes a rotary heat transfer tube 4 provided with a cooling jacket inside a hollow having a stirring member 5 around a rotary shaft 3 at the bottom of the main body 2. The main body 2 has a supply port 9 at one end, a discharge port 10 at the other end, and a bottom wall 21 having an arc approximately matching the shape of the heat transfer tube 4. Side walls 20, 20 'and bottom wall 21 of body 2
Is provided with a cooling jacket 8.

The cooling medium enters the heat transfer tube 4 via a rotary joint 6 attached to the end of the rotating shaft 3, conducts heat, and then exits the system again via the joint 6. Similarly, the cooling medium enters and exits the cooling jacket 8.

Downstream of the outlet 10 is a shifter 12 such as a plan shifter.
Is installed.

The pulverized particles are supplied from the supply port 9 into the cooling device 1 and gradually sent to the discharge side while being stirred and mixed by the rotary heat transfer tube 4. During this time, the powder is cooled by heat conduction from the heat transfer tube 4 and the cooling jacket 8, cooled until the fluidity is improved, and discharged from the outlet 10.

The above-mentioned cooling treatment is desirably performed under the condition that the granules after the pulverization treatment at a temperature of 50 to 70 ° C are cooled to a temperature of 25 to 35 ° C within 10 to 60 minutes. When the cooling device 1 is used, the conditions are as follows: the processing amount of the granular material is 100 to 600 kg / hr;
And a heat transfer area of about 1.5 to 17 m ^{2 including the} cooling jacket 8.

The powder or granular material after the cooling process is sent to the shifter 12. With the shifter 12, for example, a powder having a particle size of 150 to 250 μm can be suitably sieved and classified from a powder having a particle size of several μm to 500 μm.

The granular material to which the sieving method of the present invention is applied is a granular material after the pulverization processing in which the binding property is increased and the fluidity is reduced due to an increase in the temperature of the pulverized substance during the pulverization processing. Examples include spices such as turmeric and mustard.
For example, in the case of turmeric, when the temperature of the granular material becomes 40 to 70 ° C. by the pulverization process, the fluidity is significantly reduced, and this is cooled to a state where the fluidity is obtained by the stirring type indirect cooling device. Thereafter, by sieving, sieving can be performed very efficiently without clogging of the shifter or the like.

In the present invention, the particle size of the pulverized granules is several μm to 500 μm
This is particularly effective in classifying powders having a particle size of 150 to 250 μm from these. It is also effective for sieving powders having a bulk specific gravity of 0.2 to 0.8. In other words, these particles can be sieved extremely efficiently by increasing the efficiency of stirring and cooling by the stirring type indirect cooling device to make them highly fluid and have high classifying properties. INDUSTRIAL APPLICABILITY The present invention is effective for sieving a powdery material having a remarkable decrease in fluidity after pulverizing turmeric, mustard and the like.

The turmeric after the pulverization treatment was sieved using the sieving apparatus shown.

The cooling device 1 has a capacity of about 0.45 m ³ of the main body 2 and includes a heat transfer tube 4 (a heat transfer area of about 11.2 m ^{2 including the} heat transfer tube 4 and the cooling jacket 8) having twelve φ685 mm stirring members 5. did. Turmeric after grinding (particle size about 10-300μm,
The bulk specific gravity of 0.5 and the product temperature of about 61 ° C.) were sent from the supply port 9 to the cooling device 1 and cooled at 500 kg / hr. During this time, heat transfer tubes 4
Was driven at a rotation speed of 20 R / M, and cold water at 20 ° C. was sent to the cooling jacket and the cooling jacket 8 in the heat transfer tube 4 at about 50 / min. The turmeric discharged from the outlet 10 of the cooling device 1 was able to be sifted through a plan shifter 12 having an opening of 250 μm at a product temperature of about 29 ° C., and the sieved powder had a good aroma. .

(Effect)

According to the present invention, by cooling the granular material whose fluidity has decreased due to the temperature rise of the granular material by the pulverizing process by the stirring type indirect cooling device, by the stirring effect of the rotary heat transfer surface of the cooling device, Fluidity is generated in the granular material, thereby increasing the heat transfer rate to achieve efficient cooling, and at the same time, quickly diffuse the evaporated water. Therefore, the pulverized material whose binding property has been increased and the fluidity has been reduced by the pulverization treatment can be efficiently sieved without clogging of the shifter or the like.

[Brief description of the drawings]

Perspective view of an entire sieve means according to Figure 1 the present invention, Figure 2 is a cross sectional view taken along A ₁ -A ₂ side of the sieve means according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Cooling device, 2 ... Body, 3 ... Hollow rotating shaft, 4 ... Rotary heat transfer tube, 5 ... Stirring member, 6 ... Rotary joint, 8 ... Cooling jacket, 9 ... Supply port, 10 ... outlet, 12 ... shifter, 20, 20 '... side wall, 21 ... bottom wall.

Claims (4)

(57) [Claims] 1. A method comprising the steps of: cooling a powdery material having a reduced fluidity due to an increase in binding property due to a rise in the temperature of the powdery material during the pulverization process until the powdery material is cooled; A method for sieving a granular material, comprising: 2. The method according to claim 1, wherein the cooling treatment is performed by a stirring type indirect cooling device. 3. The turmeric powder according to claim 1, wherein the powder is turmeric.
Or the method of 2. 4. A rotary heat transfer tube (4) having a cooling jacket in a hollow interior having a stirring member (5) around a rotation axis (3) at the bottom of the main body (2), and A sieving apparatus for a granular material, comprising: a cooling device (1) provided with a cooling jacket (8) on a side wall (20, 20 ') and a bottom wall (21); and a shifter (12) connected downstream thereof.