JP2003251496A - Screw dehydrater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To clean the whole circumference of a cylindrical filter screen thoroughly and simply by using ultrasonic vibration in a screw dehydrater, and also to facilitate the inspection and repair operation of an ultrasonic wave generator. <P>SOLUTION: A compression screw 8, a filter screen 9 and an outer case 2 are arranged each in a vertical posture, a draining port 21 is provided on the upper part of the outer case 2. In a plurality of places on the circumference of the outer case 2, there are arranged an ultrasonic wave generators 40 producing an ultrasonic vibration below the compression liquid level L prescribed by the draining port 21. <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 screw dehydrator equipped with a mechanism for cleaning a screen to eliminate clogging, and more particularly to a screw dehydrator for cleaning using ultrasonic vibration. The screw dehydrator squeezes a water-containing material at a civil engineering construction site, a chemical factory, a food factory, a paper manufacturing factory, etc. to separate the water-containing material into cake-like solids and liquids.

[0002]

2. Description of the Related Art In a general screw dehydrator,
The hydrated material to be squeezed is conveyed by the spiral blade, and the hydrated material is squeezed by the spiral blade and the filtration screen during that time to separate into cake-like solid and liquid. For example, when solid-liquid separation of a sludge stock solution containing fine particles generated at a civil engineering construction site is performed, a polymer flocculant is added to the sludge stock solution to agglomerate the fine particles, and the flocculated solution is squeezed with a screw dehydrator. By doing so, the filtrate containing no fine particles and the dehydrated cake are separated. When the water-containing material is squeezed continuously in this way, the solid matter is clogged in the filtration gap of the screen,
Compressing efficiency may drop rapidly.

As a means for eliminating the clogging of the screen as described above, it is known in Japanese Patent No. 2637390 to spray pressurized cleaning water to clean the screen, and the screen is driven to rotate. It is possible to spray compressed air onto the surface of the cleaning machine.
It is known from Japanese Patent Publication No. In the former, a group of cleaning nozzles is arranged along the spiral blade. In the latter, by rotating the screen with respect to the rod-shaped cleaning nozzle, the entire peripheral surface of the screen can be cleaned. According to the screw dehydrator in which the pressurized fluid is sprayed on the screen for cleaning as described above, the clogging of the screen can be surely removed, but it is necessary to separately provide a cleaning nozzle, and further the screen needs to be rotationally driven. However, the whole structure becomes complicated. In the former device in which a group of cleaning nozzles are arranged along a spiral blade, it takes a lot of time to repair and replace the cleaning nozzles.

In the screw dehydrator of the present invention, the screen is cleaned by utilizing ultrasonic vibration, and a cleaning mechanism of this type is known from Japanese Patent Laid-Open No. 2001-149709. There, an ultrasonic wave generator is arranged inside an outer cylinder that covers the periphery of the screen. At the time of cleaning, drive the ultrasonic vibrator while the outer cylinder is filled with compressed water, vibrate the compressed water with ultrasonic waves, and remove sludge from the screen surface.
Further, it is said that air bubbles are generated by cavitation caused by ultrasonic vibration in the compressed water, and the air bubbles hit the screen to remove sludge on the screen surface. In the screw dehydrator of the present invention, the screws are arranged in a vertically long state, and this type of dehydrator is disclosed in, for example, JP-A-9-8.
It is known from Japanese Patent No. 4545.

[0005]

In the above-mentioned screw dehydrator, during normal dehydration operation, the valve provided at the drain port of the outer cylinder is opened to allow the compressed water to naturally flow out of the cylinder. When cleaning the screen, it is necessary to close the valve to fill the outer cylinder with compressed water, or to separately supply the wash water to fill the outer cylinder with water. for that reason,
Cleaning work cannot be started until it is filled with compressed water or washing water, and the responsiveness is poor. Since the ultrasonic generator is arranged only at one place inside the outer cylinder, sludge and the like adhering to the screen can be removed in the vicinity of the ultrasonic generator,
Ultrasonic waves are attenuated at locations far from the ultrasonic generator,
Since the vibration energy is extremely small, it is difficult to obtain a sufficient cleaning effect. Since the ultrasonic generator is located inside the outer cylinder, it is necessary to disassemble the screw, outer cylinder, etc. when performing the inspection or repair work, and it takes a lot of time and labor for the inspection and repair work of the ultrasonic generator. It costs. Since it is necessary to completely waterproof the ultrasonic generator, there is also a disadvantage that the structure is complicated by the amount adopted in the waterproof structure.

An object of the present invention is to provide a screw dehydrator for cleaning a filtration screen using ultrasonic vibration,
It is to clean the entire circumference of the cylindrical screen uniformly and easily. An object of the present invention is to provide a screw dehydrator that can perform screen cleaning at any time according to the clogging condition of the screen, can easily perform inspection and repair work of the ultrasonic generator, and requires less space for installation. Especially.

[0007]

As shown in FIG. 1, a screw dehydrator of the present invention comprises a squeezing screw 8, a cylindrical filter screen 9, an outer shell case 2 surrounding the filter screen 9, and a filter. The screen 9 is provided with the gate mechanism 4 arranged at the outlet 30 of the dehydrated cake. Compressing screw 8, filtration screen 9 and shell case 2
Are arranged in a vertically long position, and a drainage port 21 for the squeezed liquid is provided in the upper part of the outer shell case 2. Drainage port 21
The ultrasonic generators 40 for oscillating ultrasonic vibrations are arranged at a plurality of positions on the peripheral surface of the outer shell case 2 below the liquid level L of the squeezed liquid defined by.

Specifically, a large number of ultrasonic wave generators 40
Are arranged at regular intervals along the circumferential direction and the longitudinal direction of the outer shell case 2. The oscillating section 41 of each ultrasonic generator 40 faces the inner surface of the outer shell case 2 through the mounting port 42 provided in the outer shell case 2.

The outer shell case 2 is composed of an upper case 6 and a main case 7 which can be attached to and detached from the upper case 6. The water-containing material inlet 14 is provided in the upper case 6, and the squeezing liquid drainage port 21 is provided in the upper part of the main case 7, and the liquid level L of the squeezing liquid is set in the upper part of the main case 6. Inside the upper case 6, a protective cylinder 13 that covers the outer periphery of the connecting shaft 8a of the compression screw 8 can be arranged, and a seal body 12 that seals the connecting shaft 8a can be arranged above the inner surface of the protective cylinder 13. .

[0010]

According to the present invention, the squeezing screw 8, the filtering screen 9 and the outer shell case 2 are arranged in a vertically long position, and the drainage port 21 is provided on the upper portion of the outer shell case 2 to provide the outer shell case 2. The dewatering treatment was performed in a state where the compressed liquid was filled in the inside, and most of the compression screw 8 and the filtering screen 9 were immersed in the compressed liquid. Then, the ultrasonic generators 40 are provided at a plurality of positions on the peripheral surface of the outer shell case 2 below the liquid level L of the squeezed liquid defined by the drainage port 21.
The filter is arranged so that ultrasonic vibrations can uniformly reach the entire peripheral surface of the filtration screen 9. Therefore, according to the present invention, when the filtration screen 9 is clogged, the solid matter that closes the filtration gap is removed only by driving the ultrasonic generator 40 after interrupting the squeezing work, and the dehydration function is properly adjusted. Can be restored to a state.

That is, there is no need to wait for the filling of the squeezed liquid,
The filtration gap can be cleaned easily and immediately, and the plurality of ultrasonic wave generators 40 arranged on the peripheral surface of the outer shell case 2 are used to uniformly and evenly clean the periphery of the filtration screen 9 to effectively remove water. Can be recovered. In addition, each ultrasonic generator 4
Since 0 is arranged on the peripheral surface of the outer shell case 2, there is no need to disassemble the outer shell case 2, the filtration screen 9 and the like, and the repair work such as inspection and replacement of the ultrasonic generator 40 is easy with little labor. You can do it. Since the screw dehydrator is vertically long, it also has the advantage of requiring less space for its installation.

A large number of ultrasonic generators 40 are included in the outer shell case 2.
According to the screw dehydrator arranged at regular intervals along the circumferential direction and the longitudinal direction of the filter, the vibration wave generated by the ultrasonic generator 40 is made to act evenly on the periphery of the filtration screen 9 to perform filtration. The gap can be reliably cleaned in a short time. The oscillator 41 of the ultrasonic generator 40 is
The outer shell case 2 is attached through the mounting port 42 provided in the outer shell case 2.
Since the vibration wave generated by the ultrasonic generator 40 can be directly oscillated in the compressed liquid when facing the inner surface of the filter, there is no loss of vibration energy and a stronger vibration wave is applied to the filtration screen 9 for filtration. The gap can be cleaned more effectively. Since only the oscillating portion 41 of the ultrasonic wave generator 40 needs to be waterproofed, the structure of the ultrasonic wave generator 40 is simplified as compared with the case where the entire ultrasonic wave generator 40 is immersed in the squeezed liquid. Cost can be reduced.

The upper case 6 and the main case 7 compose the outer shell case 2, the upper case 6 is provided with an inlet 14 for water, and the upper part of the main case 7 is provided with an outlet 21 for the compressed liquid. ,
When the liquid level L of the squeezing liquid is set to the upper part of the main case 6, the seal body 12 for the connecting shaft 8a of the squeezing screw 8 is located in the gas layer part in the upper case 6 and is fed into the filtration screen 9. It is possible to prevent an object from directly adhering to the seal body 12, and to cover the periphery of the seal body 12 with a protective cylinder 13,
Since it is possible to prevent the water-containing substance fed from the inlet 14 from adhering to the seal body 12, it is possible to prevent the seal body 12 from being worn out at an early stage and to extend the life thereof.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings show an embodiment of a screw dehydrator according to the present invention. As shown in FIG. 2, a vertically elongated outer shell case 2 vertically supported by a stand 1 and an upper end of the outer shell case 2 are provided. A motor 3 with a speed reducer to be arranged, a gate mechanism 4 provided at the other end of the outer shell case 2, and a pump 5 for pressure-feeding the water-containing material are provided.

The outer shell case 2 is divided into an upper case 6 which is fixedly supported by the stand 1 and a main case 7 which is continuous with the upper case 6 under the upper case 6 and which has a squeeze screw 8 therein. A filter screen 9 is housed.

In FIG. 1, the upper case 6 is a cylindrical case that opens downward, and the motor 3 is mounted on the bearing case 10 fixed to the upper surface of the case.
A coupling shaft 8a at the upper end of the compression screw 8 is pivotally supported by a pair of bearings 11 provided inside the 0. The connecting shaft 8a is fixed to the output shaft 3a of the motor 3 via a key, and the outer periphery thereof is covered with the protective cylinder 13.
The bearing 11 with the seal body 12 mounted on the upper part of the inner surface of
The space between and is sealed in a watertight manner.

An inlet 14 for supplying a water-containing substance is provided on the outer peripheral wall of the upper case 6. A flange 15 for connecting the main case 7 is provided around the opening on the lower surface of the upper case 6.
Is fixed, and a pin 16 for positioning the main case 7 and the filtration screen 9 is projectingly provided on the lower surface side of the flange 15. The water-containing substance is pressure-fed by the pump 5 into the upper case 6 through the inlet 14. However, in order to prevent the water-containing substance ejected from the inlet 14 from directly adhering to the seal body 12, the protection tube 13 having a vertically long end is used. Is provided, and most of the upper portion of the connecting shaft 8a is covered with the protective cylinder 13.

The main case 7 is made up of a cylindrical case having the same diameter as the upper case 6 and open at both upper and lower ends, and flanges 17 and 18 are fixed to the upper and lower ends, respectively. The main case 7 can be integrated with the upper case 6 by joining the upper end flange 17 to the flange 15 of the upper case 6 and fastening both 15 and 17 with the bolt 19, and by removing the bolt 19, the main case 7 And the upper case 6 can be separated. A drainage port 2 for collecting the squeezed liquid is provided on one side of the upper end of the cylinder wall of the main case 7.
1 is provided. As described above, when the drainage port 21 is provided in the upper portion of the outer shell case 2, the inside of the outer shell case 2 is constantly filled with the squeezed liquid and is positioned below the liquid level indicated by the symbol L in FIG. Most of the squeezing screw 8 and the filtering screen 9 can be immersed in the squeezing liquid.

The squeezing screw 8 comprises a hollow main shaft 23, a spiral blade 24 fixed to the outer periphery thereof, and a connecting shaft 8a fixed to the upper end of the main shaft 23. The connecting shaft 8a is cantilevered by a bearing 11. It is suspended vertically by supporting it. If the distance between the main shaft 23 and the filtration screen 9 is large, only the water-containing substance on the side closer to the filtration screen 9 is squeezed, and the water-containing substance on the side closer to the main shaft 23 is less likely to be squeezed.
Therefore, in this embodiment, the distance between the outer peripheral surface of the main shaft 23 and the inner peripheral surface of the filtration screen 9 is set to 30 mm so that the water-containing substance can be uniformly dehydrated. The spiral blade 24 is formed to have the same diameter and the same pitch from one end to the other end.

In FIG. 4, the filter screen 9 is formed in a cylindrical shape using a wedge wire 9a having excellent pressure resistance as a filter element, and an upper flange 27 and a lower flange 28 are fixed to both upper and lower ends thereof. The filtration screen 9 is inserted into the main case 7, the upper flange 27 thereof is engaged with the pin 16 on the upper case 6 side, and the lower flange 28 is further fastened to the flange 18 of the main case 6 with bolts 29 (see FIG. 2). As a result, the main screen 6 and the filtration screen 9
Are fixed concentrically. When the main case 7 is attached to the upper case 6, the inner surface of the filtration screen 9 is in contact with the peripheral surface of the protruding end of the spiral blade 24. At the center of the lower flange 28, a dehydrated cake outlet 30 is opened in the shape of a circular hole.

In FIG. 3, the gate mechanism 4 is the outlet 3
A disk-shaped gate body 32 for closing 0, a pair of adjusting bolts 34 inserted into the gate body 32 and the flange 18, a nut 36 and a spring receiving piece 35 screwed into each adjusting bolt 34, a spring receiving piece 35 and a flange. And a compression coil type spring 37 disposed between the spring 37 and the spring 18. Gate body 32
Is normally urged by the spring 37 toward the outlet 30 to close the outlet 30, and the dehydration state can be adjusted by adjusting the tightening amount of the nut 36.

In the screw dehydrator having the above construction, in order to recover the dehydration function by cleaning the filtration gap of the filtration screen 9 which has been clogged, a large number (10) are provided on the peripheral surface of the outer shell case 2. An ultrasonic generator 40 is provided. This ultrasonic wave generator 40 is a commercially available product, and its oscillating portion 41 faces the inside of the main case 7 through a mounting opening 42 formed through the wall surface of the main case 7 as shown in FIG.
It is attached so as to face the peripheral surface of.

The ultrasonic wave generators 40 are arranged at regular intervals along the vertical direction of the main case 7 and at 90 in the circumferential direction.
They are distributed and arranged so that the phases are shifted by degrees. In this way, when the ultrasonic generators 40 are dispersed and arranged so as to surround the periphery of the filtration screen 9, the ultrasonic generators 4 are
Since the ultrasonic vibration oscillated from 0 can be made to act evenly and surely on the peripheral surface of the filtration screen 9, the solid matter blocking the filtration gap of the filtration screen 9 can be reliably peeled off and removed. . When the oscillation energy of the ultrasonic generator 40 is increased, steam bubbles are generated in the compressed liquid filled in the main case 7 due to cavitation, and the filtration gap is closed by the collision pressure of the compressed liquid when the steam bubbles burst. The solid matter that has come out can be stripped off and removed. In FIG. 5, reference numeral 43 is a control device for the ultrasonic generator 40.

The screw dewatering machine of the present invention is used when solid-liquid separation of a sludge stock solution containing fine particles generated in a civil engineering construction site is performed. At that time, conventionally, after adding a polymer coagulant to the sludge stock solution to agglomerate the microparticles, the agglomerate was squeezed with a screw dehydrator to separate the water containing no microparticles and the dehydrated cake. In the screw dehydrator of the present invention, pretreatment with a polymer flocculant is omitted and the sludge stock solution is directly squeezed. Specifically, as shown in FIG. 5, the sludge stock solution stored in the sludge tank 44 is pressure-fed by the pump 5 to the inlet 14 of the upper case 6, and the compression screw 8 is rotationally driven by the motor 3 to perform compression.

The sludge stock solution in the filtration screen 9 is pushed toward the outlet 30 by the spiral blade 24,
It is squeezed and dehydrated before reaching. The dewatered solids or dewatered cake is forced down the outlet 30.
The gate body 32 is pushed into the side and pushed open the gate body 32 against the biasing force of the spring 37 to fall from the outlet 30.
It is housed in 5. The squeezed liquid that has passed through the filtration screen 9 is discharged from the drainage port 21 and collected in the drainage tank 46.

For example, when the flow rate of the squeezed liquid from the drainage port 21 becomes less than a certain amount, the flow rate sensor 48 detects this and determines that the filtration screen 9 is in a clogged state. In that case, the filtration screen 9 is cleaned. For this purpose, first, the feed of the undiluted sludge solution by the pump 5 is stopped, and the motor 3 is reversely driven to loosen the dehydrated cake to contain water and soften it.

When the ultrasonic generator 40 is driven in this state and a vibration wave is caused to act through the compressed water filled in the main case 6, the dehydrated cake attached to the filtration gap of the filtration screen 9 vibrates. Received and peeled off. By vibrating the wedge wire 9a itself which has received the vibration wave,
The dehydrated cake attached to the filtration gap can be shaken off. At this time, the ultrasonic wave generators 40 may be driven all at once, or the pairs of ultrasonic wave generators 40 facing each other on the peripheral surface of the main case 7 are alternately driven so that the vibration wave is applied to the filtration screen 9. You may make it arrive from a horizontal direction or a vertical direction by turns. After that, the sludge source liquid is fed into the filter screen 9 by the pump 5, and the pressing by the pressing screw 8 is restarted.

In addition to the above, the outer shell case 2 may be arranged such that the central axis of the squeezing screw 8 is inclined, and in that case, the drainage port 21 is provided on the upper part of the main case 7 and the squeezing screw is provided. 8 and most of the filter screen 9 is immersed in the squeezing liquid. The arrangement form of the ultrasonic generator 40 may be different from the arrangement form described in the embodiment, and may be arranged spirally on the peripheral surface of the main case 7, for example. The ultrasonic generator 40 may be arranged in a state where the oscillating portion 41 thereof is in close contact with the outer peripheral surface of the main case 7.

The pressing screw 8 may have a tapered shape or a flared shape. The spiral blade 24 may have a pitch that decreases as it approaches the outlet 30. The outer shell case 2 described in the embodiment is turned upside down, the outlet 30 is provided at the upper end, and the drainage port 2 is further provided.
1 may be provided in the vicinity of the outlet 30. The support target of the stand 1 may be the main case 7, or both the upper case 6 and the main case 7. The gate mechanism 4 includes a spring 3
7 may be omitted, and the gate body 32 may be closed and urged by a fluid pressure cylinder. The filter screen 9 does not necessarily need to use a wedge wire as a filter element, and may be formed by stacking punching metal or plural kinds of filter elements inside and outside.

[Brief description of drawings]

1 is a vertical front view of the upper part.

[Figure 2] Side view

[Fig. 3] Vertical side view

FIG. 4 is a sectional view taken along line AA in FIG.

FIG. 5 is a front view illustrating a usage example.

[Explanation of symbols]

2 outer shell case 6 upper case 7 main case 8 squeeze screw 9 Filtration screen 12 Seal body 13 Protective tube 14 entrance 21 Drainage port 30 exit 40 ultrasonic generator 41 Oscillator 42 mounting mouth L level

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01D 29/94 B01D 29/38 580C

Claims (3)

[Claims] 1. A squeeze screw 8, a tubular filtration screen 9, and an outer shell case 2 surrounding the perimeter of the filtration screen 9.
And a gate mechanism 4 arranged at the outlet 30 of the dehydrated cake in the filtration screen 9, the squeezing screw 8, the filtration screen 9 and the outer shell case 2 are respectively arranged in a vertically long position, and the outer shell case 2 Is provided with a drainage port 21 for the squeezed liquid and oscillates ultrasonic vibrations at a plurality of peripheral surfaces of the outer shell case 2 below the liquid level L of the squeezed liquid defined by the drainage port 21. A screw dehydrator, which is provided with an ultrasonic generator 40. 2. A large number of ultrasonic wave generators 40 are arranged at regular intervals along the circumferential direction and the longitudinal direction of the outer shell case 2, and the oscillating section 41 of each ultrasonic wave generator 40 is The screw dehydrator according to claim 1, which faces the inner surface of the outer shell case 2 through a mounting port 42 provided in the shell case 2. 3. The outer shell case 2 is composed of an upper case 6 and a main case 7 that can be attached to and detached from the upper case 6, wherein the water-containing material inlet 14 is in the upper case 6, and the squeezed liquid is discharged. Mouth 21
Are provided in the upper part of the main case 7, respectively, and the liquid level L of the squeezing liquid is set in the upper part of the main case 6, and the inside of the upper case 6 is protected to cover the outer periphery of the connecting shaft 8a of the squeezing screw 8. The screw dehydrator according to claim 1 or 2, wherein a cylinder (13) is arranged, and a seal body (12) for sealing the connecting shaft (8a) is arranged on an upper portion of an inner surface of the protection cylinder (13).