JP2002350057A - Drier and method for producing dried tofu refuse using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drier which enables production of dried tofu refuse having a given water content irrespective of water contents of raw tofu refuse obtained from different tofu factories or the like, and to provide a method for producing such dried tofu refuse. SOLUTION: The drier comprises a drying oven 2 having a puddle conveyor screw 11 which extends in the axial direction, and a hot air blower 3. The drying oven 2 is provided, at its entrance part 21, with a supply port for wet raw materials and a hot blast port 4a which communicates with the hot air blower 3. An exit part 23 is provided with an outlet 6a for discharging dried materials with hot blast. At least a part of blades of the puddle screw 11 comprises return blades 13b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying apparatus capable of producing dried okara having a predetermined moisture content irrespective of the moisture content of raw okara obtained from different tofu plants and the like, and a method for using such a drying apparatus. To a method for producing dried okara.

[0002]

2. Description of the Related Art Okara discharged from a tofu factory or the like is generally treated as industrial waste and is usually in a raw state (water content 70 to 90).
%) Is used as fertilizer, feed, etc. Okara is rich in vegetable fiber, has no environmental problems such as disposal as synthetic fiber, and is low in cost. Therefore, it is expected to be widely used, including industrial raw materials. As an example of using okara, an absorbent for toilets of pets such as dogs and cats is known. When okara is used as a toilet absorbent, it is porous and fibrous, so that it has excellent shape retention and water absorption, and has a unique deodorizing effect due to its unique action.

Since raw okara has a high moisture content and rots quickly, it must be once dried even if processed into a toilet absorbent at a factory. However, the raw okara discharged from various tofu factories has a different moisture content,
There is a problem that heating conditions must be changed for each raw material. For example, if the heating temperature of the raw okara is too high, the okara is burnt, and when used as a toilet absorbent, an unpleasant odor is caused, so that not only the commercial value is reduced but also pets may not be used. On the other hand, if the drying is insufficient, the okara rots and becomes unusable as a toilet absorbent.
Therefore, it is desired to produce dried okara having a predetermined moisture content regardless of the moisture content of raw okara obtained from different factories or the like.

[0004]

Accordingly, an object of the present invention is to provide a drying apparatus capable of producing dried okara having a predetermined moisture content regardless of the moisture content of raw okara obtained from different tofu factories and the like, and An object of the present invention is to provide a method for producing such dried okara.

[0005]

Means for Solving the Problems As a result of intensive studies in view of the above object, the present inventor has developed a short drying oven by using a paddle screw type hot air drying oven and combining return blades with paddle screw feed blades. The present inventors have found that the residence time of the okara can be made sufficiently long and that the raw okara with different moisture contents can be always dried to a predetermined moisture content.

That is, a drying apparatus of the present invention for hot-wet raw material drying includes a drying furnace having a paddle screw extending in an axial direction, and a hot air blower, and the drying furnace is provided at an inlet portion with the drying furnace. A supply port for the wet raw material and a hot air inlet communicating with the hot air blower are provided, and an outlet for discharging the dried raw material together with the hot air is provided at an outlet portion, and a blade of the paddle screw is provided. At least a part is a return blade.

In a preferred embodiment of the present invention, the drying furnace includes an inlet, an intermediate portion, and an outlet. The paddle screw has at least a feed blade at the inlet.
The intermediate portion has at least a return blade, and the outlet portion has at least a feed blade and a return blade in order. The blades of the paddle screw include a feed blade and a blade substantially parallel to an axial direction of the paddle screw (hereinafter, referred to as a “parallel blade”) at the inlet portion, and a return blade and a parallel blade at the intermediate portion. It is preferable that a front portion of the outlet portion includes a feed blade and a parallel blade, and a rear portion of the outlet portion includes only a return blade or a return blade and a parallel blade.

The inclination angle of the feed blade at the inlet with respect to the axial direction is 5 ° to 30 °, the inclination angle of the return blade at the intermediate portion is 3 ° to 15 °, and the inclination angle of the feed blade at the outlet portion is Preferably, the angle is 5 to 20 °, and the inclination angle of the return blade is 10 to 30 °.

Preferably, all the blades of the paddle screw at the rear of the outlet are return blades.

[0010] The rotation speed of the paddle screw and the traveling speed of the hot air in the drying furnace are determined so that the raw material stays in the intermediate portion for a time sufficient to substantially dry to a desired moisture content. , Is preferably set.

The method for producing dried okara according to the present invention is characterized in that the hot air is fed into the inlet of the drying furnace from the hot air blower and discharged from the outlet of the outlet using the drying device. Raw okara is sent to the entrance of the drying oven,
The raw okara is dried by hot air while stirring the raw okara with the blades of the paddle screw, and a force for returning to the hot air by the rotation of the return blade is applied, so that the okara is sufficiently retained in the intermediate portion. .

The hot air is applied to the entrance of the drying oven by 400
Preferably, the feed is at a temperature of ~ 420 ° C. Further, it is preferable to set the rotation speed of the paddle screw and the blowing speed of the hot air so that dried okara having a predetermined moisture content is obtained regardless of the moisture content of the raw okara.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [1] Drying Device An example of a drying device of the present invention will be described with reference to FIGS. Hereinafter, raw okara will be described as an example of a wet raw material, but the drying apparatus of the present invention is not limited to raw okara.

[0014] As shown in FIG.
And a hot air blower 3 that communicates with the drying furnace 2 via a blower tube 4. A transfer device 5 having a hopper 1 is attached to an inlet of the drying furnace 2, and a cyclone 7 communicates with an outlet through a discharge pipe 6. The dried okara is separated in the cyclone 7 by centrifugal action. Cyclone 7
Is connected to a cooling hopper 8, where the dried dried okara is collected in a collecting container 30.

As shown in FIG. 2, a stirring blade 18 is provided in the hopper 1, and the raw sashimi 10 is fed to the transfer device 5. The rear end of the transfer device 5 is open to the drying furnace 2.
It has a twin-screw conveyor 15 that transports raw okara fed from the hopper 1 to the drying furnace 2. As shown in FIG. 3, a gutter 17 is provided around the twin-screw conveyor 15 so that the drying oven 2 can be used without dropping raw okara.
It can be transported to

The size and shape of the drying oven 2 can be appropriately set according to the amount of raw okara, but as an example, the diameter and the
m and a cylindrical shape having a length (longitudinal direction) of about 7 m. As shown in FIGS. 2 and 4, the drying furnace 2 is provided with a paddle screw 11 having a shaft 14 extending longitudinally at the center of its circular cross section, and the shaft 14 is provided on both side walls of the drying furnace 2 through bearings. It is rotatably supported. A sprocket provided at one end of the shaft 14 is engaged with a motor 16 by a chain and is driven to rotate. Rods 19 are fixed to the shaft 14 at substantially equal intervals,
The blade 13 is attached to the tip of each rod 19.

In the example shown in FIG. 2, eight rods 19 are attached at one position in the axial direction of the shaft 14 at equal angles, and fifteen units of the rods 19 are provided at equal intervals in the axial direction. . The number of rods 19 in each unit is not limited to eight, and can be set as appropriate. Also rod on shaft 14
The number of 19 units is not limited to 15.

As shown in FIG. 2, the drying furnace 2 has an inlet portion 21, an intermediate portion 22, and an outlet portion 23 in this order from the raw okara supply port. There are three, nine in the middle part 22 and three in the outlet part. An important feature of the present invention is that at least some of the blades 13 of the paddle screw 11 are return blades. The hot air forms an eddy flow by the rotation of the blades 13 of the paddle screw 11, and gradually advances to the outlet while staying in the drying furnace 2 by the action of the return blades 13b.
As a result, the okara stays sufficiently in the drying furnace 2 and is sufficiently dried.

As shown in FIG. 5 (b), the term "return vane" means that the axial component force Fb of the force pushing the hot air by the rotation of the shaft 14 is moved in the backward direction of the hot air (toward the entrance of the drying furnace 2). ). On the other hand, as shown in FIG. 5A, the "feed blade" means that the axial component force Ff of the force pushing the hot air by the rotation of the shaft 14 is the forward direction of the hot air (toward the outlet of the drying furnace 2). The blades are inclined to face. It is preferable to set the rotation speed of the blades to, for example, several tens to several hundreds of rpm, and significantly higher than the traveling speed of the hot air.
In that case, the rotation of the return blade 13b or the feed blade 13a exerts a large force in the backward direction or the forward direction on the hot air, respectively,
This has a significant effect on the residence time of hot air.

FIG. 6 shows an example of the direction of the blade 13 of the paddle screw 11 in each part of the drying furnace 2. At the inlet 21, the feed blades 13a and the parallel blades 13c are alternately arranged, and at the intermediate portion 22, the return blades 13b and the parallel blades 13c are alternately arranged. The inclination of the blade 13 at the outlet 23 is different between the front part 23a and the rear part 23b. The front part 23a is composed of the feed blade 13a and the parallel blade 13c, and the rear part 23b is all composed of the return blade 13b. Note that the parallel blade 13c is a blade that is substantially parallel to the shaft 14 and does not substantially generate a component in the axial direction in the force for pressing the hot air by the rotation of the shaft 14.

Of course, the number and arrangement of the feed blades 13a or return blades 13b in each section are not limited to the above examples, and the size and shape of the drying furnace 2, the blowing speed of hot air, the paddle screw 11
It can be variously changed according to the rotation speed of the raw rice, the supply speed of raw okara, and the like. For example, at the inlet 21, instead of alternately arranging the feed blades 13a and the parallel blades 13c, the number of the feed blades 13a is increased by increasing the inclination angle θ, and conversely, the inclination angle θ is reduced to increase the number. May be. Further, the inclination angle θ of each feed blade 13a may be different.

In the intermediate portion 22, the parallel blades 13c and the return blades 13b are alternately arranged, but they may be arranged randomly. In one unit, the parallel blade 13c and the return blade 1
Each unit may be arranged so that only one of the units 3b is configured and the other unit is configured only by the other unit. Further, return blades 13b having different inclination angles θ may be attached to each unit. The important thing in the middle part 22 is that at least the return blade 13
is to have b.

In the example shown in FIG.
23a comprises a feed blade 13a and a parallel blade 13c, and a rear portion 23b
In this case, all the return blades 13b are used, but this is not a limitation. At the front part 23a of the outlet part 23, the feed blade 13a and the parallel blade 13c
May be alternately arranged, may be random, and may be all the feed blades 13a. Also rear 2
In FIG. 3b, all return blades 13b are used, but a part of the return blades 13b may be parallel blades 13c. The return blade 13b and the feed blade 13a may be configured by blades having different inclination angles θ.

In the preferred embodiment of the present invention, the inclination angle θ of the feed blade 13a at the inlet 21 is preferably 5 to 30 °, and
0 to 20 ° is more preferable. The inclination angle θ of the feed blade 13a is 5 °
If it is less than this, the raw okara transport at the entrance 21 is insufficient even if all of the feed blades 13a are used. If the inclination angle θ of the feed blade 13a is more than 30 °, the transport speed of raw okara is too high, and the action of the return blade 13b in the intermediate portion 22 is reduced. In the inlet section 21 having the feed blade 13a having such an inclination angle θ, the ratio of the feed blade 13a to the entire blade is preferably about 30 to 70%.

In a preferred embodiment of the present invention, the inclination angle θ of the return blade 13b in the intermediate portion 22 is preferably 3 to 15 °,
5 to 10 ° is more preferable. The tilt angle θ of the return blade 13b is 3
If the angle is less than 0 °, the force of returning the okara is insufficient even if it is entirely constituted by the return blades 13b, and the residence time of the okara in the intermediate portion 22 is insufficient. If the inclination angle θ of the return blade 13b is more than 15 °, the ratio of the return blade 13b must be extremely low in order to obtain an appropriate return force, and the okara stays in the intermediate portion 22. Becomes uneven. In the intermediate portion 22 having the return blades 13b having such an inclination angle θ, the ratio of the return blades 13b to the entire blade is preferably about 30 to 70%.

In the preferred embodiment of the present invention, the inclination angle θ of the feed blade 13a at the front part 23a of the outlet part 23 is preferably 5 to 20 °, more preferably 10 to 15 °. If the inclination angle θ of the feed blade 13a is less than 5 °, the force for discharging the okara is insufficient even if the feed blade 13a is entirely constituted by the feed blade 13a. If the inclination angle θ of the feed blade 13a is more than 20 °, the force for discharging okara becomes too large, and the action of the return blade 13b in the intermediate portion 22 is reduced. The feed blade 13a having such an inclination angle θ
In the front part 23a of the outlet part 23 having the above, the ratio of the feed blade 13a to the whole blade is preferably about 30 to 70%.

The return blade 1 at the rear portion 23b of the outlet portion 23
3b is preferably 10 to 30 °, more preferably 15 to 25 °. When the inclination angle θ of the return blade 13b is less than 10 °,
Even if all of them are constituted by the return blades 13b, the force for guiding the okara to the discharge port 6a is insufficient. Also, the inclination angle θ of the return blade 13b is 3
If it exceeds 0 °, the flow of hot air at the outlet 23 will be too turbulent. In the rear portion 23b of the outlet 23 having the return blade 13b having such an inclination angle θ, the ratio of the return blade 13b to the entire blade is preferably about 30% or more, and particularly preferably 100%.

[2] Production method of dried okara (A) Raw okara The raw water content of raw okara is usually 70 to 70% depending on the tofu factory or the like.
Although the drying apparatus of the present invention can be dried to a predetermined moisture content at any moisture content, the method of the present invention can be applied to any raw moisture of any moisture content. can do.

(B) Drying Raw okara 10 put into the hopper 1 is put into the supply port of the drying furnace 2 through the transfer device 5. Blower tube 4 from hot air blower 3
The hot air sent through the oven is 400 to 420 ° C at the entrance 21 of the drying furnace.
It is preferred that Below 400 ° C, the drying efficiency is low,
The drying oven 2 must be lengthened. On the other hand, when the temperature exceeds 420 ° C., the dried okara may be scorched.

The rotation of the paddle screw 11 causes the entrance
The raw okara supplied to 21 is immediately sent to the intermediate section 22. In the intermediate portion 22 having the return blades 13b, the progress of the hot air is blocked, so that the residence time of okara can be lengthened. It is preferable to appropriately set the rotation speed of the paddle screw 11 and the blowing speed of hot air so that dried okara having a predetermined moisture content is obtained irrespective of the moisture content of raw okara.

By adjusting the residence time of the okara in the drying furnace 2 in this way, it is possible to produce dried okara having a sufficiently low moisture content from any raw okara. Further, since a sufficient residence time can be obtained, it is not necessary to increase the temperature of the hot air, so that the occurrence of scorch can be prevented.

(C) Separation It is preferable that the dried okara is discharged by suction from the outlet 6a at the upper part of the outlet 23 of the drying furnace 2 and centrifuged by the cyclone 7. By using the cyclone 7, dried okara can be efficiently separated from the heat medium.

(D) Cooling The dried okara separated by the cyclone 7 is sent to the cooling hopper 8 and cooled by air. If necessary, the particle size may be adjusted by grinding the dried okara.

[0034]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 100 kg of raw okara with a water content of 80% was put into the hopper 1 of the drying apparatus shown in FIG. 2 and fed into the drying furnace 2 by the screw conveyor 15. The blade 13 of the paddle screw 11 in the drying furnace 2 has eight blades in one unit, three units in the inlet 21,
The intermediate part 22 had 9 units, the front part 23a of the outlet part 23 had two units, and the rear part 23b had one unit. The feed blades 13a at the inlet 21 had an inclination angle θ of 20 °, and four blades were alternately provided for each unit. The return blades 13b in the intermediate portion 22 had an inclination angle θ of 8 °, and four return blades were alternately provided for each unit. The feed blade 13a at the front part 23a of the outlet part 23 has an inclination angle θ of 10 °.
In two units, there were ten. Also the rear part 23 of the exit part 23
The blades 13 in b were all return blades 13b having an inclination angle θ of 20 °. All other blades 13 were parallel blades 13c.

Hot air having an inlet temperature of 420 ° C. was sent into the drying furnace 2 by the hot air blower 3, and was heated and dried while stirring the okara by the paddle screw 11. The rotation speed of the paddle screw 11 was 144 rpm. The dried okara discharged from the outlet 6a of the drying furnace 2 was sent to the cyclone 7 through the discharge pipe 6, where it was centrifuged. The obtained dried okara is sent to the cooling hopper 7, where it is allowed to cool for about 12 hours.
Particle size 15 mesh, density 0.380 g / cm ³ , moisture content 8%
The dried okara was obtained.

REFERENCE EXAMPLE 1 90 kg of dried okara and 10 kg of corn starch as a binder prepared in Example 1 were put into a twin screw extruder from a hopper.
The mixture was heated and kneaded at a revolution / minute. Next, it was discharged from the outlet at an extrusion speed of 600 kg / hour, cut into a length of 4 to 10 mm, and dried with warm air at 200 ° C. to produce a toilet absorbent.

The toilet absorbent prepared using the dried okara manufactured according to Example 1 has a finer surface texture, absorbs water, and forms a lump than when directly dried okara is used as a raw material by the conventional technique. An absorbent for toilets having high properties and deodorant properties was obtained.

In the above embodiment, the case where a plurality of blades of the paddle screw are attached to each unit has been described. However, the present invention is not limited to this example. For example, each blade is attached to the shaft in a spiral shape. May be.
Even in that case, at least some of the blades need to be return blades, and it is preferable that the arrangement of the blades at the inlet, the middle, and the outlet be as described above. The shape of the blade need not be square as described above, but can be changed as appropriate.

[0040]

As described above, the drying apparatus of the present invention is a drying apparatus using a paddle screw type hot air drying furnace, and is a short drying furnace by combining return blades with paddle screw feed blades. Even so, the residence time of the okara can be made sufficiently long. Therefore, it is possible to always dry to a predetermined moisture content even from raw okara having different moisture contents.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an entire apparatus for producing dried okara.

FIG. 2 is a partial longitudinal sectional view showing a drying apparatus of the present invention.

FIG. 3 is a cross-sectional view showing a transport device attached to the drying device of the present invention.

FIG. 4 is a cross-sectional view showing a drying furnace included in the drying apparatus of the present invention.

FIG. 5 is a schematic view showing an inclination angle of a blade of a paddle screw.

FIG. 6 is a schematic development view showing blades of a paddle screw in a drying furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hopper 2 ... Drying furnace 3 ... Hot air blower 4 ... Blower tube 4a ... Hot air inlet 5 ... Conveying device 6 ... Discharge pipe 6a ... Discharge port 7.・ ・ Cyclone 8 ・ ・ ・ Cooling hopper 10 ・ ・ ・ Raw okara 11 ・ ・ ・ Paddle screw 13 ・ ・ ・ Blade 13a ・ ・ ・ Feed blade 13b ・ ・ ・ Return blade 13c ・ ・ ・ Parallel blade 14 ・ ・ ・ Paddle Screw shaft 15 ・ ・ ・ Screw conveyor 16 ・ ・ ・ Motor 17 ・ ・ ・ Gutter 18 ・ ・ ・ Stirrer 19 ・ ・ ・ Rod 21 ・ ・ ・ Inlet 22 ・ ・ ・ Intermediate 23 ・ ・ ・ Outlet 23a ················································································································· • Fr ・ ・ ・ Component of vertical direction of blade axis

Claims (9)

[Claims] 1. A drying apparatus for hot-humidity drying of a wet raw material, comprising: a drying furnace having a paddle screw extending in an axial direction; and a hot air blower, wherein the drying furnace has the wet A supply port for the raw material and a hot air inlet communicating with the hot air blower are provided, and an outlet for discharging the dried raw material together with the hot air is provided at an outlet portion, and at least the blades of the paddle screw are provided. A drying device characterized in that a part is a return blade. 2. The drying apparatus according to claim 1, wherein the drying furnace includes an inlet portion, an intermediate portion, and an outlet portion, and the paddle screw has at least a feed blade at the inlet portion, and has a feed blade at the intermediate portion. A drying apparatus comprising at least a return blade, and at least at the outlet portion, at least a feed blade and a return blade. 3. The drying apparatus according to claim 2, wherein the blade of the paddle screw is a blade substantially parallel to an axial direction of the feed blade and the paddle screw at the inlet portion (hereinafter, referred to as a “parallel blade”). The intermediate part is composed of return blades and parallel blades, the front part of the outlet part is composed of feed blades and parallel blades, and the rear part of the outlet part is only return blades or return blades and parallel blades. A drying device, comprising: 4. The drying device according to claim 2, wherein an inclination angle of the inlet portion with respect to an axial direction of the feed blade is 5 to 30 °, and an inclination angle of the return blade of the intermediate portion is 3 to 30 °.
15 °, and the inclination angle of the feed blade at the outlet is 5 to 20 °
And a return blade having an inclination angle of 10 to 30 °. 5. The drying apparatus according to claim 2, wherein all the blades of the paddle screw at the rear of the outlet are return blades. 6. The drying apparatus according to claim 2, wherein a rotation speed of the paddle screw and a traveling speed of the hot air in the drying furnace are such that the raw material contains substantially desired water. A drying device set to stay in said intermediate portion for a time sufficient to dry to a rate. 7. A method for producing dried okara using the drying apparatus according to any one of claims 1 to 6, wherein hot air is supplied from the hot air blower to an inlet of the drying furnace and the outlet is heated. While the raw okara is being discharged from the discharge port, the raw okara is fed into the inlet of the drying furnace, and the raw okara is dried by hot air while stirring the raw okara with the blades of the paddle screw, and the rotation of the return blade is performed. A method of applying a force to return to hot air by the above method, whereby the okara is sufficiently retained in the intermediate portion. 8. The method for producing a dried okara according to claim 7, wherein the hot air is supplied to the inlet of the drying oven by 400 to 4 times.
A method characterized by feeding at a temperature of 20 ° C. 9. The method for producing dried okara according to claim 7 or 8, wherein the rotation of the paddle screw is performed so as to obtain a dried okara having a predetermined moisture content regardless of the moisture content of the raw okara. A method comprising setting a speed and a blowing speed of the hot air.