JP2003245574A - Decanter type centrifugal dewatering apparatus and centrifugal dewatering method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress power consumption, to prevent enlargement and impossible plan of a decanter type centrifugal dewatering apparatus, and to achieve high dewatering efficiency. <P>SOLUTION: The decanter type centrifugal dewatering apparatus is provided with a rotary bowl 1 having an approximately cylindrical outer shape and a tapered and slanted inner circumferential part in one end side and made rotatable around an axial line O and a screw conveyer 7 concentrically installed in the rotary bowl 1 and made rotatable in the same direction with a differential speed. In the circular space C between the screw conveyer 7 and the rotary bowl 1, an object P to be treated that is supplied from the center part in the axial line O direction is subjected to solid-liquid separation by centrifugal force and the solid matter S is discharged through a solid matter discharge port 4 equipped with a valve body 14 in one end side of the circular space C, while the separated liquid L is discharged out of a separated liquid flow route 11 in the circumferential side of the circular space C in the other end side in the axial line O direction. In one end side of a screw shaft 7a in the circular space C, a conical part 7C with a truncated conical shape whose center is conformed to the axial line O and having an outer diameter gradually narrowed toward the one end side is formed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decanter type centrifugal dewatering apparatus for dewatering an object to be treated such as sewage sludge and a centrifugal dewatering method using the apparatus.

[0002]

2. Description of the Related Art A decanter type centrifugal dehydrator is a rotating bowl having a cylindrical shape and rotatably supported around a central axis, and is coaxially arranged in the rotating bowl at the same speed as the rotating bowl. With a screw conveyor rotatably supported in a direction, solid-liquid separation by a centrifugal force of the rotating bowl the object to be treated supplied to the annular space between these screw conveyor and the rotating bowl, of which the solid content Is conveyed and discharged in the axial direction by the screw conveyor, and the separated liquid separated from the solid content is separately discharged through the separated liquid discharge passage. As such a decanter type centrifugal dehydrator, for example, Japanese Patent No. 2720373 or Japanese Patent No. 303228.
No. 3, Japanese Utility Model Publication No. 5-20445 and Japanese Patent Application Laid-Open No. 1-127063 have been conventionally proposed.

[0003]

However, among them, in the devices described in Japanese Patent No. 3032283 and Japanese Patent Application Laid-Open No. 1-127063, the drainage passage of the separated liquid is a rotating bowl whose radial direction is separated from the axis. Since the kinetic energy given to the separated liquid by the centrifugal force due to the rotation of the rotating bowl is lost with the discharge of the separated liquid, the energy loss is large and the device is driven. Power consumption for this will increase. On the other hand, the device disclosed in Japanese Patent No. 2720373 is
A device for concentrating a substance to be processed and separating it into a concentrated liquid and a separated liquid, wherein a concentrated liquid discharge port is provided on the above-mentioned axis through a shaft of a screw conveyor, and from the inner circumference of a rotating bowl to this discharge port. The concentrated liquid discharge passage extends in a direction perpendicular to the above-mentioned axis, and although a concentrated liquid with a large amount of liquid can be transported, such a device dehydrates sewage sludge with a large specific gravity to reduce the solid content with a small amount of water. If you separate
It is difficult to convey this to the inner peripheral side perpendicular to the axis through the discharge path while resisting centrifugal force, and if the inner diameter of the discharge port is not increased, clogging occurs, so that the shaft of the screw conveyor The diameter and the like must be increased, and accordingly, a bearing for rotatably supporting the shaft and the like also become large, which may lead to an increase in size of the device and an unreasonable design. Further, the device disclosed in Japanese Utility Model Publication No. 5-20445 is also a concentrating device, and solid-liquid separation is performed while an object to be treated is supplied to the annular space from one end side in the axial direction and conveyed to the other end side. And then
The concentrated liquid and the separated liquid thus separated are respectively discharged through the discharge passages of the double pipe structure provided along the axis on the other end side. Then, in order to discharge the solid content, it is unavoidable that the diameter of this double pipe becomes large, and since the solid content and the separated liquid are in a turbid state until reaching the respective discharge paths, it is sufficient. You will not be able to dehydrate properly.

The present invention has been made under such a background, and the decanter type centrifugal dehydrator for dehydrating an object to be processed to separate solid and liquid into a solid content and a separation liquid is intended to suppress power consumption. Needless to say, it is possible to obtain high dehydration efficiency without enlarging the size of the device or forcibly designing it, and it is possible to efficiently dehydrate the object to be treated using such a device. The purpose is to provide a simple dehydration method.

[0005]

In order to solve the above-mentioned problems and to achieve such an object, a decanter type centrifugal dehydrator of the present invention has an outer shape in which one end side inner peripheral portion is tapered. A rotating bowl which is substantially cylindrical and is rotatably supported around a central axis, and a screw conveyor which is coaxially arranged in the rotating bowl and is rotatably supported in the same direction at a speed difference with the rotating bowl. Equipped with, while solid-liquid separation by the centrifugal force of the rotating bowl the workpiece supplied from the axial center in the annular space between the screw conveyor and the rotating bowl, the separated solid content is the screw conveyor. It is possible to convey to the one end side by means of the solid content discharge port opened to the one end side of the annular space, and to adjust the discharge amount of the solid content to the solid content discharge port. While the body is provided, the separated liquid separated from the object to be processed is configured to be discharged from the separated liquid flow path opened to the inner peripheral side of the annular space at the other end side in the axial direction, and further in the annular space. The screw shaft is characterized in that a conical portion having a truncated cone shape centered on the axis line whose outer diameter is gradually reduced toward the one end side is formed in the portion on the one end side. Therefore, in the decanter type centrifugal dehydrator having such a configuration, first, the object to be treated is supplied to the annular space from the central part in the axial direction, and the separated solid content is conveyed to one end side and discharged,
Since the separated liquid is discharged from the other end side, it is possible to efficiently perform solid-liquid separation of the object to be treated, and at this one end side, since the inner peripheral portion of the rotating bowl is tapered, the solid content is Can be smoothly conveyed to the inner peripheral side and discharged from the solid content discharge port, and this solid content discharge port is open to one end side of the annular space, that is, because it is the outer peripheral side of the screw conveyor, There is no need to increase the diameter of the shaft. Further, by further forming a cone-shaped portion having a truncated cone shape around the axis, the outer diameter of which is gradually reduced toward the one end side, in the portion on the one end side of the screw shaft in the annular space. Since the cross-sectional area of the annular space on the one end side where the solid content is discharged can be further reduced, the solid content separated from the object to be solid-liquid separated can be more reliably compressed to achieve more efficient dehydration. be able to. On the other hand, since the flow path through which the separated liquid is discharged is open to the inner peripheral side of the annular space, it is possible to prevent the separated liquid from being discharged while having a large kinetic energy due to the centrifugal force.

Further, since the solid content discharge port is provided with a valve body capable of adjusting the solid matter discharge quantity, by adjusting the solid content discharge quantity by this valve body, for example, the annular space The solid content is retained on one end side and compressed,
It is possible to further improve the dehydration efficiency. Further, the centrifugal dewatering method of the present invention uses a decanter type centrifugal dewatering apparatus having such a configuration, in which the solid content separated after the object to be treated is supplied to the annular space is the one end side. The solid content discharge port is closed by the valve body until the solid content is accumulated in the valve body, and then the solid content discharge port is opened while adjusting the discharge amount by the valve body to discharge the solid content. By accumulating the solid content on one end side of the space and compressing it as described above, a solid retention layer is always formed on one end side of the annular space during the operation of the apparatus, which is efficient. It can be dehydrated.
In addition, considering disassembly and maintenance at the time of maintenance,
The valve body is preferably provided outside the rotating bowl. Further, the separation liquid flow path may be provided with an adjusting means capable of adjusting the discharge amount of the separation liquid discharged from the flow path to control the dehydration efficiency.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a reference example for explaining an embodiment of the present invention. In this reference example, the rotating bowl 1 has a substantially cylindrical shape centered on an axis O that is horizontally arranged, but the one end side (left side in FIG. 1) of the rotary bowl 1 is gradually reduced in diameter toward the one end side. It has a conical shape (conical shape), so that the inner peripheral portion of the rotary bowl 1 on one end side is formed as a tapered diameter-reduced portion 1a. In this reference example, the length of the reduced diameter portion 1a on the one end side of the rotating bowl 1 in the direction of the axis O is the straight body portion 1 on the other end side where the rotating bowl 1 has a cylindrical shape.
It is made shorter than the length of b. Further, both ends of the cylinder formed by the rotating bowl 1 are closed by annular plate-shaped end wall portions 1c and 1d centering on the axis O, and
From the inner peripheral portions of these end wall portions 1c and 1d, substantially cylindrical shaft ends 2 and 3 centered on the axis O are provided so as to extend outward in the direction of the axis O, respectively. A solid content discharge port 4 is formed on the outer peripheral side of the shaft end portion 2 in the end wall portion 2 on the one end side. And these shaft end portions 2, 3
Is attached to bearings 5 and 5 such as bearings, and a pulley 3a is provided on a shaft end portion 3 on the other end side (right side in FIG. 1) of the pulleys 3a. The rotary bowl 1 is rotatably supported around the axis O by being connected by 6a or the like.

A screw conveyor 7 is arranged in the rotary bowl 1 with the central axis coaxial with the axis O. This screw conveyor 7 is a rotating bowl 1.
The screw shaft 7a is liquid-tightly inserted into the inner circumference of the cylindrical shaft ends 2 and 3 through bearings 8 such as bearings and is rotatable relative to the rotary bowl 1.
And the axis O above the outer peripheral portion of the screw shaft 7a.
The screw shaft 7a is provided with a screw blade 7b that is spirally twisted around, and both ends of the screw shaft 7a project outward from the shaft ends 2 and 3 in the direction of the axis O, and the other end The screw conveyor 7 is rotatably supported around the axis O in the same rotation direction as the rotary bowl 1, but with a slight speed difference, by connecting the part to the rotation means 9 such as a motor. Furthermore, the outer diameter of the screw blade 7b is such that a slight gap is formed between the screw blade 7b and the inner peripheral portion of the rotary bowl 1, and the inner peripheral portion of the rotary bowl 1 and the screw conveyor 7 are formed.
And a cylindrical portion having a substantially thick wall except for the screw blade 7b, and the reduced diameter portion 1a at the one end side.
Thus, the annular space C whose outer diameter is reduced is defined so as to extend around the axis O in the direction of the axis O. The direction of twist of the screw blade 7b is such that when the screw conveyor 7 is rotated, the solid content S that is solid-liquid separated from the object P to be processed supplied to the annular space is directed to the one end side. Has been done. Further, in this reference example, the outer diameter of the portion of the screw shaft 7a that defines the inner peripheral portion of the annular space C and is disposed in the rotating bowl 1 is constant along the axis O direction.

Furthermore, the screw shaft 7a of the screw conveyor 7 is hollow at the other end side, and the hollow portion serves as a supply path 10 for the object P to be treated such as sewage sludge. The passage 10 is bent to the outer peripheral side at a substantially central portion in the direction of the axis O of the annular space C and is opened to the outer periphery of the screw shaft 7a. On the other end side of the screw shaft 7a, a separation liquid flow passage 11 for discharging the separation liquid L separated from the object to be treated is provided, and the flow passage 11 is the outer periphery of the screw shaft 7a, that is, After being opened to the inner peripheral side of the annular space C and extending to the inner peripheral side, it is bent into an L-shape where it does not reach the supply path 10 and extends to the other end side parallel to the axis O. In the O direction, a step portion of the screw shaft 7 formed between the shaft end portion 3 of the rotating bowl 1 and the rotating means 9 is opened toward the other end side. The cover 12 is provided around the opening end on the other end side of the flow path 11.
On the outer periphery of the screw shaft 7a on the other end side of the stepped portion, which is covered with, a ring-shaped valve body 13 having a triangular shape whose cross section along the axis O tapers toward one end side, It is installed so as to face the opening end of the flow path 11 so as to be able to advance and retreat in the direction of the axis O by a driving means (not shown), and serves as a means for adjusting the discharge amount of the separated liquid L in this reference example.

On the other hand, on the outer circumference of the shaft end portion 2 on the one end side of the rotating bowl 1, a flange portion 2a is provided in an annular shape so as to be spaced apart from the end wall portion 1c on the one end side. Around this flange portion 2a, a "U" -shaped ring-shaped valve body 14 having a cross section along the axis O, which opens to the inner peripheral side so as to surround the flange portion 2a, is formed around the inner peripheral portion. Liquid-tightly adhere to the outer periphery of the shaft end portion 2 and also the inner peripheral surface of the concave portion defined by this "U" -shaped cross section to the outer peripheral portion of the flange portion 2a. Installed. Therefore, the valve body 14 is arranged outside the rotary bowl 1. Here, the width of the concave portion of the valve body 14 in the direction of the axis O is larger than the thickness of the flange portion 2a, so that the valve body 14 is kept in liquid tight contact with the shaft end portion 2. Of the pressure chamber 14a, which can be moved back and forth in the direction of the axis O while keeping the flange portion 2a in the concave portion between the one end side and the other end side.
14a is defined.

In the flange portion 2a, pressure fluid passages 15 and 15 are opened at both end faces of the pressure chambers 14a and 14a, and the pressure fluid passages 15 and 15 are formed into flanges. After extending from the portion 2a to the inner peripheral side of the shaft end portion 2 and reaching the inside of the screw shaft 7a, the screw shaft 7a extends to one end side and is connected to a pressure fluid supply source (not shown). Therefore, the pressure fluid such as hydraulic oil is supplied from one of the supply sources to the one pressure chamber 14a through the fluid paths 15 and 15, and the other pressure chamber 14a is also supplied.
By extracting the pressure fluid from the valve body 14, the valve body 14 can be moved forward and backward to the one end side and the other end side in the axis O direction. In the state where the valve body 14 is advanced to the other end side, the valve body 14 is rotated. By closely contacting with the end wall portion 1c, the solid content outlet 4 formed in the end wall portion 1c can be closed, while the valve body 14 is retracted to the other end side. The discharge port 4 is opened so that the solid content S can be discharged, and the discharge amount thereof can be adjusted by adjusting the supply amount of the pressure fluid to the pressure chambers 14a, 14a by the supply source. . A cover 16 is provided so as to be located between the bearings 5 and 5 between the one end side of the valve body 14 that can be advanced and retracted in this way and the other end side of the end wall portion 1d on the other end side. The rotating bowl 1 is covered so as not to interfere with the rotation of the rotating bowl 1.

In the decanter type centrifugal dehydrator having the above-mentioned structure, the object to be treated P supplied through the supply passage 10 is first supplied to the annular space C from the substantially central portion in the direction of the axis O of the annular space C. Then, the solid content S is separated by the centrifugal force due to the rotation of the rotating bowl 1 and the solid content S is conveyed to one end side by the screw conveyor 7, while the separated liquid L separated from the solid content S is driven to the other end side. Will be done. Therefore, in the annular space C, there are few portions where the solid content S and the separated liquid L are turbid, and efficient solid-liquid separation can be achieved. Further, since the separated liquid L thus driven to the other end side is discharged from the separated liquid flow path 11 provided on the outer circumference of the screw shaft 7a and opening to the inner peripheral side of the annular space C, the discharged separated liquid is discharged. The kinetic energy of the liquid L due to the centrifugal force is small, and the kinetic energy given to the separated liquid L by the rotation of the rotary bowl 1 is reduced to the rotary energy of the rotary bowl 1 and the screw conveyor 7, so that these It is possible to reduce power consumption for rotationally driving.

On the other hand, the solid content S conveyed to the one end side by the screw conveyer 7 is directed toward the one end side along the inner peripheral part of the reduced diameter portion 1a which is tapered at the one end side toward the one end side. And is discharged from the solid content discharge port 4 formed in the end wall portion 1c. Therefore, on this one end side, the cross-sectional area orthogonal to the axis O of the annular space C gradually decreases toward the one end side, whereby the solid content S is compressed as it is conveyed to the one end side, and high dehydration efficiency is obtained. The solid content S can be obtained, and the solid content S can be easily discharged as compared with the case where the solid content S is conveyed to the inner peripheral side perpendicular to the axis O against the centrifugal force and discharged.
Moreover, since the solid content discharge port 4 is formed in the end wall portion 1c of the rotating bowl 1 which is located on the outer periphery of the screw shaft 7a of the screw conveyor 7, it is possible to discharge the solid content S through the inside of the screw shaft 7a. Compared with this, it is not necessary to increase the diameter of the screw shaft 7a, so that it is possible to prevent the bearing 5 supporting the screw shaft 7a from increasing in size, which leads to an increase in the size of the device or an unreasonable design. There is no need to be strong.

Further, a valve body 14 is provided on one end side of the solid content discharge port 4. In the present reference example, the valve body 14 is provided.
As described above, the space between the valve body 14 and the one end wall portion 1c of the rotary bowl 1 is adjusted by advancing and retracting by the supply of the pressure fluid, and thereby the above-mentioned formed on the end wall portion 1c. The discharge amount of the solid content S from the solid content discharge port 4 can be adjusted. Therefore, when the dehydration rate of the solid content S discharged from the discharge port 4 is low, that is, when the solid content S having a water content higher than the desired water content is discharged, the valve body 14 is directed toward the discharge port 4. And advancing to narrow the interval to suppress the discharge of the solid content S, and the solid content S is retained and compressed at one end side in the rotating bowl 1 to further promote solid-liquid separation, and the water content of the solid content S. On the other hand, when the water content of the discharged solid content S is lower than the desired water content, on the other hand, the valve body 14 is retracted to expand the interval to compress the solid content S. The water content can be increased by loosening, and the solid content S having a desired water content can be obtained. Moreover, the valve element 14 is provided on the one end side of the end wall portion 1c on the one end side of the rotary bowl 1 as described above, that is, is arranged outside the rotary bowl 1, and therefore the maintenance Even when the valve body 14 is to be disassembled for maintenance, it is possible to easily perform maintenance without disassembling the rotary bowl 1 from the screw conveyor 7 or the like.

Further, in this reference example, the valve element 1 is also provided in the flow path 11 for discharging the separated liquid L separated from the object P to be treated.
3 is provided so as to be able to move forward and backward in the direction of the axis O, and the amount of the separated liquid L discharged from the flow channel 11 is adjusted by moving the valve element 13 forward and backward to adjust the distance from the open end of the flow channel 11. A water content of the solid content S discharged from one end side of the rotating bowl 1 is provided by adjusting means, and by advancing the valve body 13 toward the open end side of the flow path 11 to suppress the discharge amount of the separated liquid L. On the other hand, if the valve body 13 is retracted from the opening end to increase the discharge amount of the separated liquid L, the water content of the solid content S can be reduced. Together with this, the solid content S is further increased to the desired water content.
Can be dehydrated. In addition, in the means for adjusting the discharge amount of the separated liquid L, instead of providing the valve body 13 that can advance and retreat in the direction of the axis O in this way, for example, the flow path 1 described above is used.
The discharge amount of the separated liquid L may be adjusted by fixedly providing a baffle plate or the like so as to face the opening end of No. 1 and face the opening end.

Further, according to the centrifugal dehydrator provided with the valve body 14 for adjusting the discharge amount of the solid content S in this manner, for example, the object P to be treated is supplied to the annular space C at the beginning of the operation of the dehydrator. Until the solid content S that has been solid-liquid separated is accumulated on one end side in the rotary bowl 1.
4, the solid content outlet 4 is closed, the solid content S accumulated in this way is sufficiently compressed to be dehydrated to a desired water content, and then the valve body 14 is retracted to adjust the discharge amount. At the same time, the solid content discharge port 4 can be opened to discharge the solid content S. Therefore, according to such a centrifugal dehydration method, it is possible to prevent the solid content S that is not sufficiently dehydrated at the beginning of the operation of the dehydrator from being discharged, and also during the subsequent operation, the annular space C It is possible to always form an appropriately dehydrated retention layer of the solid content S on one end side, and it is possible to achieve more reliable and efficient dehydration of the object P to be treated.

FIG. 2 shows an embodiment of the centrifugal dehydrator of the present invention, in which parts common to those of the reference example shown in FIG. 1 are designated by the same reference numerals. In the reference example, the outer diameter of the screw shaft 7a of the portion disposed in the annular space C is constant along the axis O. The screw shaft 7a is characterized in that a cone-shaped portion 7c having a truncated cone shape centering on an axis O whose outer diameter is gradually reduced toward the one end is formed in the portion on the one end side. Therefore, according to the centrifugal dehydrator of the present embodiment having such a configuration, the cross-sectional area of the annular space C can be further reduced on the one end side where the solid content S is discharged, so that the object P to be treated is solidified. It is possible to more reliably compress the liquid-separated solid content S to achieve more efficient dehydration.

[0018]

As described above, according to the present invention,
The object to be processed is supplied from substantially the center in the axial direction of the annular space,
The solid content is conveyed to one end side of this annular space, and the separated liquid is conveyed to the other end side and discharged, so that it is possible to achieve efficient solid-liquid separation and a channel for discharging the separated liquid. Since it is opened to the inner peripheral side of this annular space,
The separated liquid can be discharged without losing the kinetic energy due to the centrifugal force, and the rotational driving force of the rotating bowl or screw conveyor can be reduced. Further, since the inner peripheral portion of the one end side of the rotary bowl to which the solid content is conveyed is inclined in a tapered shape, the conveyed solid content can be smoothly guided to the inner peripheral side, and the solid content discharge port is It is formed at one end side of the annular space, and it is not necessary to provide a solid content discharge path in the screw conveyor, so that the device does not become large and unreasonable design is required. Since a valve body for adjusting the discharge amount is provided at the outlet, efficient dehydration can be achieved by retaining and compressing the solid content at one end side in the annular space.
And, in the portion on the one end side of the screw shaft in the annular space, a cone-shaped portion having a circular truncated cone centering on the axis line whose outer diameter is gradually reduced toward the one end side is formed, and solid content Since the cross-sectional area of the annular space can be made smaller on the one end side from which the liquid is discharged, it is possible to more reliably compress the solid content solid-liquid separated from the object to be processed, and to achieve more efficient dehydration. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a reference example for explaining an embodiment of a decanter type centrifugal dehydrator of the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of a decanter type centrifugal dehydrator of the present invention.

[Explanation of symbols]

1 rotating bowl 4 Solid content outlet 7 Screw conveyor 10 Supply path for processing object P 11 Separation liquid L flow path 13 Valve body (means for adjusting the discharge amount of the separated liquid L) 14 valve body O Central axis of rotating bowl 1 C annular space P Processing object S solid content L separation liquid

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuo Yoshida             Tsukishima Machine, 2-17-15 Tsukuda, Chuo-ku, Tokyo             Within the corporation F-term (reference) 4D057 AA11 AB01 AC01 AC06 AD01                       AE03 AF05 BA11 BC12 BC16                       CB01                 4D059 AA03 BE38 EB02 EB14

Claims (3)

[Claims] 1. A rotary bowl, which has a substantially cylindrical outer shape in which one end side inner peripheral portion is inclined in a tapered shape, is supported rotatably around a central axis, and is coaxially arranged in the rotary bowl. The rotating bowl and a screw conveyor rotatably supported in the same direction with a differential speed are provided, and the object to be processed supplied from the central portion in the axial direction is rotated in the annular space between the screw conveyor and the rotating bowl. While performing solid-liquid separation by the centrifugal force of the bowl, the separated solid content is conveyed to the one end side by the screw conveyor and can be discharged from the solid content discharge port opened to the one end side of the annular space, and A valve body capable of adjusting the discharge amount of the solid content is provided at the solid content discharge port, while the separated liquid separated from the object to be processed is in the annular space at the other end side in the axial direction. It is configured to be discharged from the separated liquid flow path that opens to the inner peripheral side, and further, in the portion on the one end side of the screw shaft in the annular space, the outer diameter gradually decreases toward the one end side. A decanter type centrifugal dewatering device, wherein a cone-shaped portion having a truncated cone shape centering on an axis is formed. 2. The decanter-type centrifuge according to claim 1, wherein the separation liquid channel is provided with an adjusting means capable of adjusting the discharge amount of the separation liquid discharged from the channel. Dehydrator. 3. A centrifugal dehydration method using the decanter type centrifugal dehydrator according to claim 1 or 2, wherein the solid content separated after supplying the object to be treated to the annular space is the above-mentioned. The solid content discharge port is closed by the valve body until the solid content is accumulated at one end, and then the solid content discharge port is opened to discharge the solid content while adjusting the discharge amount by the valve body. Centrifugal dehydration method.