JP2004239559A - Reduced-pressure dryer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduced-pressure dryer having superior ability to uniformly stir and dry a treating object in a drum. <P>SOLUTION: The drum 3 has a charging port at an upper part of a side wall and a discharging port at a lower part of one end. A rotating shaft 22 of a stirring device 6 is positioned on a center shaft of the drum 3. First arms 23 are radially extended from the rotating shaft 22, and axially arranged at constant intervals while changing their positions in the circumferential direction. Similarly, the second arms 24 are radially extended from the rotating shaft 22, and arranged with a phases shifted with respect to the first arms 23. The second arms 24 have a length shorter than the first arms 23. First stirring blades 25 are mounted on tips of the first arms 23, and their inclination angle is determined to send the treated object to a discharging side when the rotating shaft 22 is rotated forward. A second stirring blades 26 are mounted on tips of the second arms 24, and their inclination angle is set in the direction opposite to that of the first stirring blades 25. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reduced-pressure dryer, and more particularly to a reduced-pressure dryer suitable for drying foods such as okara, garbage, sludge, waste liquid, livestock manure, and the like.
[0002]
[Prior art]
In a reduced-pressure drier, an object to be treated is indirectly heated using steam or hot water under reduced pressure, and the water is evaporated and dried, utilizing the phenomenon that the boiling point of water is reduced under reduced pressure.
[0003]
FIG. 2 shows an outline of a conventional vacuum dryer. The main part of the vacuum dryer is a horizontal cylindrical drum 3, a stirring device 6 incorporated in the drum 3, a vacuum pump 17 for reducing the pressure in the drum 3, a steam for heating the drum 3, and the like. It is composed of a boiler 11 to be manufactured.
[0004]
A charging port 1 is provided in the upper portion of the side wall near one end face (right side in the figure) of the drum 3. The inlet 1 is connected to the side wall of the drum 3 via an on-off valve 2, and by closing the on-off valve 2, airtightness in the drum 3 is ensured. A discharge port 13 is provided at a lower portion of the other end surface (the left side in the figure) of the drum 3. The discharge port 13 is connected to the end face of the drum 3 via a discharge valve 13a, and by closing the open / close valve 13a, airtightness in the drum 3 is ensured.
[0005]
A stirring device 6 is incorporated in the drum 3. The stirring device 6 includes a rotating shaft 6c parallel to the axial direction of the drum 3, a plurality of arms 6b extending in a radial direction perpendicular to the rotating shaft 6c, and a stirring blade 6a attached to a tip of each arm 6b. Have been. Left and right ends of the rotating shaft 6c penetrate the end surface of the drum 3 via bearings 5a and 5b, respectively. In addition, in order to maintain the airtightness in the drum 3, these bearings 5a and 5b have a shaft sealing mechanism (not shown). One end (the right side in this example) of the rotating shaft 6c is connected to a motor 9 with a speed reducer via a sprocket 7a, a chain 8, and a sprocket 7b.
[0006]
The outer circumference of the drum 3 is covered with a jacket 4. Steam is supplied into the jacket 4 from the boiler 11 through the introduction pipes 10a and 10b. The water condensed in the jacket 4 is discharged outside through the discharge pipes 12a and 12b. Part of the steam from the boiler 11 is introduced from the end on the discharge side of the rotating shaft 6c to the inside of the rotating shaft 6c via the introduction pipe 20b, and is supplied to the inside of the arm 6b and the stirring blade 6a. After flowing in the passage and heating them, the flow returns to the inside of the rotating shaft 6c, and is discharged to the outside from the end on the non-discharge side through the discharge pipe 20a.
[0007]
A decompression exhaust pipe 15 is connected to the upper part of the side wall near the end face (left side in the figure) of the drum 3 on the discharge side. The vacuum exhaust pipe 15 is connected to a vacuum pump 17 via a heat exchanger 16. Cooling water is supplied to the heat exchanger 16 from a cooling tower 19.
[0008]
Next, an operation method of the vacuum dryer will be described.
[0009]
After the stirring device 6 is driven and a predetermined amount of the object to be processed is charged into the drum 3 from the charging port 1, the on-off valve 2 is closed. At the same time, the inside of the drum 3 is depressurized by the vacuum pump 17, and steam is supplied from the boiler 11 into the jacket 4 and the stirring device 6. The thrown object is stirred by the stirring device 6 and moves in the rotation direction while being pressed against the inner wall of the drum 3. The object to be processed is heated under a reduced pressure atmosphere, and the moisture contained therein evaporates. The vapor released from the object is discharged through the vacuum exhaust pipe 15, condensed in the heat exchanger 16, and discharged to the outside by the vacuum pump 17.
[0010]
When the amount of water contained in the workpiece decreases to a predetermined amount or less, the vacuum pump 17 is stopped, and the supply of steam from the boiler 11 is stopped. Next, the discharge valve 13a is opened, the stirring device 6 is rotated, and the object to be processed is discharged from the discharge port 13 to the container 14.
[0011]
Here, the stirring blade 6 a of the stirring device 6 is formed in a box shape so that steam flows therein, and is disposed so as to have a small gap between the stirring blade 6 a and the inner wall of the drum 3. A plurality of agitating blades 6a are arranged in the axial direction, each having a phase difference of 90 ° in the rotational direction. When one rotation is made, the entire circumference of the inner wall of the drum 3 is scraped off by the agitating blades 6a, and the adherence of the object to be processed is performed. Is configured to be prevented.
[0012]
In such a reduced-pressure drier, it is required to knead the object to be processed in the entire inside of the drum 3 without generating a stagnation point in order to increase the drying efficiency. This is important for uniformly mixing and drying, particularly when processing a plurality of types of workpieces. It is also important to increase the chances of contact between the workpiece and the stirring blade 6a and the inner wall of the drum 3 to promote heat exchange. Further, in order to discharge the object after the drying is completed, the stirring device 6 is also required to have a function of transferring the object to the outlet 13.
[0013]
However, in the conventional vacuum dryer, the stirring blade 6a is located near the inner wall of the drum 3, so that stirring is difficult to be performed near the center, and contact between the object to be processed and the inner wall of the drum 3 and the stirring blade 6a is poor. There was a problem that it was easy enough. In addition, there is a problem that the function of dispersing the workpieces in the axial direction is insufficient, and therefore, when a plurality of types of workpieces are sequentially introduced, they are difficult to be uniformly mixed.
[0014]
Further, in the vacuum dryer, it is necessary to switch the function so that the object to be processed is agitated when the stirring device 6 rotates in the normal direction and the object is discharged when the stirring device 6 is rotated in the reverse direction. It is necessary to devise the shape of the device.
[0015]
For example, Japanese Patent No. 3099269 describes the structure of a reduced-pressure drying type composting apparatus, in which the cross-sectional shape of a stirring blade is described as follows. That is, the stirring blade is constituted by a blade having a parallelogram cross section and a blade having a triangle cross section. Thus, when the stirring shaft rotates in one direction, the object to be processed is stirred while being transferred to the discharge port side, and when the stirring shaft rotates in the other direction, it is stirred without being moved to the discharge port side. That is, when rotating in one direction, the processing object is discharged, and when rotating in the other direction, the processing object is kneaded.
[0016]
However, this device has a problem that the stirring ability near the center is insufficient and the ability to disperse in the axial direction is also insufficient. Furthermore, since two types of stirring blades having different cross-sectional shapes are combined, there is a problem that the configuration is complicated.
[0017]
[Patent Document 1]
Japanese Patent No. 3099269
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the conventional vacuum dryer as described above, and an object of the present invention is to provide a vacuum dryer having an excellent ability to uniformly stir and dry an object to be processed. It is in.
[0019]
[Means to solve the problem]
The reduced pressure dryer of the present invention,
A drum with a horizontal cylindrical shape, with an inlet at the top of the side wall and a discharge at the bottom of one end,
A stirring device arranged in the drum;
A heating device for heating the drum inner wall and the stirring device,
A pressure reducing device for reducing the pressure inside the drum,
In a vacuum dryer equipped with
The stirring device,
A rotation axis parallel to the axial direction of the drum,
A plurality of first arms extending radially from the rotation axis and arranged in the axial and circumferential directions,
A plurality of second arms, which extend in the radial direction from the rotation axis, are arranged in the axial direction and the circumferential direction with the radial or axial position shifted with respect to the first arm, and are shorter than the first arm,
At the tip of the first arm, a first stirring blade having a quadrangular cross section attached at an angle inclined with respect to the axial direction,
At the tip of the second arm, a cross section attached at an angle inclined with respect to the axial direction includes a quadrilateral second stirring blade,
The first stirring blade has an inclination angle so that the object to be processed is sent to the discharge side when the rotation shaft rotates in the forward direction, and the object to be processed is sent to the non-discharge side when rotated in the reverse direction.
The second stirring blade is provided with an inclination angle so as to send the object to the discharge side when the rotating shaft rotates in the forward direction and to send the object to the discharge side when rotating in the reverse direction. It is characterized by having.
[0020]
The operation method of the vacuum dryer of the present invention will be described below. When the object to be processed is dried, the inner wall of the drum and the stirring device are heated and the pressure in the drum is reduced while the stirring device is rotated in the forward direction. On the inner wall side of the drum, the object to be processed is stirred by the first stirring blade arranged on the inner wall side and sent to the discharge side, and on the center side of the drum, the object is treated by the second stirring blade arranged on the center side. The material is stirred and returned to the non-discharge side. As a result, an axial circulating flow is formed inside the drum, and as a result, the workpiece is agitated in the circumferential direction, the axial direction, and the radial direction, and uniform mixing is realized.
[0021]
On the other hand, when discharging the processed material after drying, the discharge port provided on the discharge side is opened, and the stirring device is rotated in the forward direction. The dried workpiece is sent to the discharge side by the first stirring blades arranged on the outer peripheral side, and is sequentially discharged to the outside of the drum through the discharge port provided on the discharge side.
[0022]
If necessary, if the rotating direction of the stirring device is temporarily reversed during the drying of the object, the moving direction is reversed, and the effect of stirring and mixing of the object is further enhanced. be able to.
[0023]
ADVANTAGE OF THE INVENTION According to the reduced pressure dryer of this invention, at the time of drying, the to-be-processed object is efficiently stirred in the axial direction in addition to the circumferential direction and the radial direction in the whole inside of the drum, The material is also heated and dried by contact with the second stirring blade and the rotating shaft. As a result, uniform mixing and drying in the drum is realized.
[0024]
In addition, when a part of the first stirring blade and the second stirring blade are attached so that their inclination angles are opposite to those of other stirring blades of the same kind, the stirring ability in the axial direction can be further enhanced.
[0025]
In that case, preferably, one of the first stirring blades, one of the stirring blades located at the end on the counter discharge side, sends the workpiece to the counter discharge side when the rotating shaft rotates in the forward direction, When rotating in the direction, the processing object is sent to the discharge side, an inclination angle is provided, and among the second stirring blades, one of the stirring blades located at the end on the discharge side is rotated in the forward direction. An inclination angle is set so that the object to be processed is sent to the discharge side when rotated and the object to be processed is sent to the opposite side when rotated in the opposite direction.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a vacuum dryer according to the present invention. Note that this vacuum dryer has the same configuration as the conventional apparatus shown in FIG. 2 except for the stirrer portion, and thus, here, only a perspective view of the stirrer portion is shown, and other components are not shown. Please refer to FIG.
[0027]
In the figure, 3 is a drum (indicated by a two-dot chain line), 22 is a rotating shaft, 23 is a first arm, 24 is a second arm, 25 is a first stirring blade, and 26 is a second stirring blade. In this example, the left side is the discharge side, as in the apparatus shown in FIG.
[0028]
The drum 3 has a horizontal cylindrical shape, and has an inlet at an upper portion near a right end of a side wall and an outlet at a lower portion of an end surface on a discharge side (see FIG. 2). The inlet may be located at the upper part of the side wall of the drum 3 and need not necessarily be near the right end of the side wall, and the outlet may be located at the lower left end of the side wall. A stirring device 6 is arranged in the drum 3. 2, a heating device (not shown) for heating the inner wall of the drum 3 and the stirring device 6 and a decompression device (not shown) for depressurizing the inside of the drum 3 are provided. Have.
[0029]
The stirring device 6 includes a rotating shaft 22, a first arm 23, a second arm 24, a first stirring blade 25, a second stirring blade 26, and the like. The rotation shaft 22 is arranged on the center axis of the drum 3.
[0030]
Each first arm 23 is mounted perpendicular to the peripheral surface of the rotating shaft 22 and extends in the radial direction. The first arms 23 are arranged at regular intervals in the axial direction while changing the mounting position by 90 degrees in the circumferential direction so as to spirally surround the rotation shaft 22. Similarly, each second arm 24 is mounted perpendicular to the rotation shaft 22 and extends in the radial direction. The length of the second arm 24 is shorter than the first arm. The second arm 24 is shifted in the circumferential direction by 90 degrees in a circumferential direction so as to spirally surround the rotation shaft 22 with the phase shifted by 180 degrees with respect to the first arm 23. They are arranged at regular intervals.
[0031]
The first stirring blade 25 is attached to the tip of the first arm 23. The first stirring blade 25 has a quadrangular cross section, and is attached to the first arm 23 at an angle inclined with respect to the axial direction. The first stirring blade 25 is arranged with a slight gap between the first stirring blade 25 and the inner wall of the drum 3, and scrapes off the processing object adhered to the inner wall.
[0032]
Similarly, a second stirring blade 26 is attached to the tip of the second arm 24. The second stirring blade 26 has a quadrangular cross section, and is attached to the second arm 24 at an angle inclined with respect to the axial direction. The second stirring blade 26 is disposed so as to be located substantially in the middle of the rotating shaft 22 and the first stirring blade 25 in the radial direction of the drum. That is, relatively, the first stirring blade 25 is disposed on the inner wall side of the drum 3, and the second stirring blade 26 is disposed on the center side of the drum 3.
[0033]
Here, except for the stirring blade 25R located at the end of the rotating shaft 22 on the side opposite to the discharge side, the first stirring blade 25 is covered when the rotating shaft 22 rotates in the forward direction (the direction of arrow Z in the drawing). The inclination angle is set so that the processing object is sent to the discharge side (left direction in the figure), and the object to be processed is sent to the opposite discharge side (right direction in the figure) when rotated in the opposite direction. On the other hand, except for the stirring blade 26L located at the discharge-side end of the rotating shaft 22, the second stirring blade 26 sends the workpiece to the non-discharging side when the rotating shaft 22 rotates in the forward direction, and in the reverse direction. The inclined angle is set so that the object to be processed is sent to the discharge side when rotated.
[0034]
Also, of the first stirring blades, one stirring blade 25R located at the end on the opposite discharge side sends the workpiece to the opposite discharge side when the rotating shaft 22 rotates in the forward direction, and rotates in the reverse direction. The inclination angle is set so that the object to be processed is sent to the discharge side when it is done. On the other hand, among the second stirring blades, one stirring blade 25L located at the end on the discharge side sends the object to the discharge side when the rotating shaft 22 rotates in the forward direction, and when the rotating shaft 22 rotates in the reverse direction. The inclination angle is set so that the object to be processed is sent to the non-discharge side.
[0035]
Next, a method of operating the above-described vacuum dryer will be described. When the object to be processed is dried, the stirring device 6 is rotated in the forward direction. At the same time, the inside of the drum 3 is depressurized by the vacuum pump 17 (FIG. 2), and steam is supplied from the boiler 11 (FIG. 2) to heat the drum 3 and the stirring blades 25 and 26. On the inner wall side of the drum 3, the workpiece is agitated by the first stirring blade 25 and sent to the discharge side. On the center side of the drum 3, the workpiece is agitated by the second stirring blade 26 and is discharged. Returned to the side. As a result, the object to be processed is stirred in the circumferential direction, the axial direction, and the radial direction, and uniform mixing is realized.
[0036]
If the rotation direction of the stirring device 6 is temporarily reversed during the drying of the object, the moving direction is reversed, and the effects of stirring and mixing of the object can be further enhanced.
[0037]
The first stirring blade 25L and the second stirring blade 26R at the discharge-side end and the first stirring blade 25R and the second stirring blade 26R at the non-discharge-side end rotate the stirring device in the forward direction. At this time, each of them operates so as to send out the object to be processed toward the end face of the drum 21. However, the processing object sent out in this way is sent out toward the center of the drum 21 by another adjacent stirring blade. In this way, by making the inclination angle of some of the stirring blades disposed near the end face of the drum 21 opposite to that of the other stirring blades, it is possible to enhance the stirring near the end face.
[0038]
When discharging the dried workpiece, the discharge valve 13a (FIG. 2) provided on the discharge side is opened, and the stirring device is rotated in the forward direction. Since most of the dried workpieces are collected on the bottom side of the drum 3, they are sent to the discharge side by the first stirring blades 26 arranged on the outer peripheral side, and pass through the discharge port 13 (FIG. 2). It is sequentially discharged out of the drum 2.
[0039]
As described above, the stirring blade is arranged near the inner wall of the drum 3 in addition to the vicinity thereof, and the inclination angle of the stirring blade is opposite between the inner wall side and the center side. In the drum, stirring is performed in the circumferential direction, the axial direction, and the radial direction, and uniform mixing and drying are realized.
[0040]
Note that, in the above example, the phase of the first stirring blade 25 and the second stirring blade 26 is shifted by 180 degrees, and each of them is arranged at intervals of 90 degrees in the circumferential direction. It can be set appropriately.
[0041]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the reduced pressure drier of this invention, at the time of drying, the to-be-processed object is efficiently stirred in the axial direction in addition to the circumferential direction and the radial direction in the whole inside of a drum, and the to-be-processed object in the center side The material is also heated and dried by contact with the second stirring blade and the rotating shaft. As a result, uniform mixing and drying in the drum is realized.
[0042]
Further, according to the reduced pressure dryer of the present invention, parts having the same shape can be used for the first stirring blade and the second stirring blade. Further, both the drying operation and the discharging operation can be performed while the rotation direction of the drying device is fixed in the forward direction.
[Brief description of the drawings]
FIG. 1 is a perspective view of a stirring device which is a main part of a reduced-pressure dryer according to the present invention.
FIG. 2 is a diagram showing a schematic configuration of a conventional vacuum dryer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inlet, 2 ... On-off valve, 3 ... Drum, 4 ... Jacket, 5a, 5b ... Bearing, 6 ... Stirring device, 6a ... Stirring blade, 6b ... Arm, 6c ... Rotating shaft, 7a, 7b ... Sprocket, 8 ... Chain, 9 ... Motor with reduction gear, 10a, 10b ... Introduction pipe, 11 ... Boiler, 12a, 12b ... Discharge pipe, 13 ... Discharge port, 13a ... Discharge valve, 14 ... Container, 15 ... Decompression exhaust pipe, 16 ... Heat exchanger, 17 ... Vacuum pump, 19 ... Cooling tower, 20a ... Discharge pipe, 20b ... Introduction pipe, 22 ... Rotary shaft, 23 ... First arm, 24 ... Second arm, 25, 25R, 25L ... First stirring blade , 26, 26R, 26L: Second stirring blade.

Claims (3)

A drum with a horizontal cylindrical shape, with an inlet at the top of the side wall and a discharge at the bottom of one end,
A stirring device arranged in the drum;
A heating device for heating the drum inner wall and the stirring device,
A pressure reducing device for reducing the pressure inside the drum,
In a vacuum dryer equipped with
The stirring device,
A rotation axis parallel to the axial direction of the drum,
A plurality of first arms extending radially from the rotation axis and arranged in the axial and circumferential directions,
A plurality of second arms, which extend in the radial direction from the rotation axis, are arranged in the axial direction and the circumferential direction with the radial or axial position shifted with respect to the first arm, and are shorter than the first arm,
At the tip of the first arm, a first stirring blade having a quadrangular cross section attached at an angle inclined with respect to the axial direction,
At the tip of the second arm, a cross section attached at an angle inclined with respect to the axial direction includes a quadrilateral second stirring blade,
The first stirring blade has an inclination angle so that the object to be processed is sent to the discharge side when the rotation shaft rotates in the forward direction, and the object to be processed is sent to the non-discharge side when rotated in the reverse direction.
The second stirring blade is provided with an inclination angle so as to send the object to the discharge side when the rotating shaft rotates in the forward direction and to send the object to the discharge side when rotating in the reverse direction. A vacuum dryer. Of the first stirring blades, some blades are attached such that the inclination angle is opposite to that of the other blades,
2. The reduced pressure dryer according to claim 1, wherein a part of the second stirring blades is mounted so that an inclination angle of the other blades is opposite to that of the other blades. 3. One of the first stirring blades, which is located at the end opposite to the discharge side, sends the object to the discharge side when the rotating shaft rotates in the forward direction, and receives the object when rotated in the reverse direction. The slant angle is set so that the processed material is sent to the discharge side,
Of the second stirring blades, one of the stirring blades located at the end on the discharge side sends the processing target to the discharge side when the rotation shaft rotates in the forward direction, and the processing target when rotated in the reverse direction. 3. The vacuum dryer according to claim 2, wherein the inclination angle is set so that is sent to a side opposite to the discharge side.

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