JP4310142B2 - Medium stirring type pulverizer and sludge treatment apparatus using medium stirring type pulverizer - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a sludge treatment apparatus using a medium agitation type pulverizer and a medium agitation type pulverizer suitable for use in a sludge treatment apparatus.
[0002]
[Prior art]
A cylindrical vessel having a crushing chamber formed therein, and a stirring shaft provided with a stirring member are arranged in the vessel, and the grinding shaft is filled with a grinding medium such as glass beads or steel beads. Many media-stirring type pulverizers are known in which a slurry containing solid content is circulated through a pulverization chamber while rotating to finely pulverize the solid content. This type of pulverizer has a slurry inlet at one end of the vessel, and the slurry is introduced into the pulverization chamber from the inlet and passes between the pulverizing media that is agitated by a stirring member and rotates. It is discharged from the slurry discharge port formed at the end. The solid particles contained in the slurry are crushed into fine particles by receiving a strong shearing action due to contact between the media while the slurry passes between the pulverizing media.
[0003]
In order to separate the slurry that has reached the slurry discharge port side end of the pulverization chamber from the pulverization medium and discharge only the slurry from the discharge port, is a separation screen provided at the slurry discharge port (for example, Patent Document 1)? And 2), or a separation slit having a size that does not allow the grinding medium to pass therethrough (see, for example, Patent Document 3).
[0004]
The medium stirring type pulverizer configured as described above is used for pulverizing ink, paint pigments, magnetic powder, ceramic materials, and the like. There are attempts to use this type of grinder for sludge treatment in sewage treatment facilities. That is, in sewage treatment, the sludge discharged from the sewage treatment facility is concentrated in the adjustment tank, then digested by anaerobic bacteria in the digestion tank, and the generated methane gas is guided to the gas storage tank and recycled as various heat sources. To do. Then, the remaining surplus sludge is sent to the final treatment. Here, when surplus sludge is guided to a medium agitation type pulverizer by a pump and pulverized, the cell membrane contained in the sludge is destroyed by pulverization, and the amount of methane gas generated in the digestion process by anaerobic bacteria is several tens. %, And at the same time, the amount of sludge that is sent to the final treatment is remarkably reduced (for example, Non-Patent Documents 1 and 2).
[0005]
[Patent Document 1]
JP2001-219087
[Patent Document 2]
German Patent No. 1109988 [Patent Document 3]
German Patent No. 2312109 [Non-Patent Document 1]
Japan Agricultural Village Drainage Association “2001 Agricultural Village Drainage Technology Research Presentation” “Adaptation of Mill Crushing Sludge Reduction System to Agricultural Village Drainage Treatment Facility” Unitika Co., Ltd. Mikio Ide, November 29, 2001 [Non-Patent Document 2]
25th Sewerage Research Conference Lecture Meeting “Sludge Pretreatment—Effect of Wet Mill Pretreatment for Anaerobic Digestion Method” sponsored by Japan Sewerage Association, Fujita Industry Co., Ltd. Teruo Nakagawa et al. May 9-11, 1988.
[0006]
[Problems to be solved by the invention]
As described above, it is expected that a great effect can be achieved when the medium stirring type pulverizer is used for the treatment of surplus sludge generated in the sewage treatment facility. However, the excess sludge generated in the sewage treatment has a high concentration, and includes microbial cells, undigested organic matter, hard-to-digest hair, and pulp fibers. Of these inclusions, hair and pulp fibers are not easily pulverized by the medium stirring type pulverizer, and most of them are directly directed to the slurry discharge port. However, in the conventional medium agitating type pulverizer, a screen or a separation gap for separating the slurry and the pulverization medium is provided at the slurry discharge port. This causes the problem of clogging and inability to drive.
[0007]
Therefore, eliminating the screen or separation gap of the slurry discharge port and providing a large opening at the discharge port eliminates the clogging problem, but the pulverization medium filled in the pulverization chamber is discharged together with the slurry from the pulverizer. become.
[0008]
The present invention has been obtained in order to cope with such a problem of the prior art, and does not cause clogging even when used for pulverizing excess sludge generated in sewage treatment, and the pulverizing medium is combined with the slurry. It is an object of the present invention to provide a medium agitation type pulverizer that can substantially prevent discharge.
[0009]
The present invention also provides a sludge treatment apparatus using such a pulverizer.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, a medium agitation type pulverizer according to the present invention includes a cylindrical vessel having a pulverization chamber therein, a slurry inlet provided at one end of the pulverization chamber, and the other end of the pulverization chamber. A slurry discharge port provided in the lid plate to be closed, a stirring shaft rotatably disposed in the vessel, and extending radially outward from the stirring shaft at a position spaced in the axial direction of the stirring shaft. A plurality of stirring members provided, filling the grinding chamber with a grinding medium, introducing the slurry from the slurry introduction port while rotating the stirring shaft, and discharging the slurry from the slurry discharge port into the slurry. It has a configuration in which the contained solid content is crushed. Further, as a feature of the present invention, the slurry discharge port is an opening formed in a cover plate having a size through which a pulverizing medium, hair, pulp fiber, etc. can pass, and the cover plate surrounds the slurry discharge port and is stirred. A cylindrical sleeve is provided so as to extend substantially in the axial direction of the shaft. The slurry that has reached the vicinity of the vessel end on the slurry discharge port side of the pulverization chamber is reversed in the direction of the slurry introduction port by the sleeve and separated from the pulverization medium under the rotational motion by the stirring action of the stirring member. Passes through the inside of the sleeve, passes through a slurry passage near the discharge port, and is discharged from an opening constituting the slurry discharge port.
[0011]
In a preferred aspect of the present invention, the stirring member closest to the slurry discharge port is provided with a stirring bar extending substantially in the axial direction of the stirring shaft at a position radially outside the sleeve, and the stirring bar provides a sleeve. A rotating motion is applied to the surrounding slurry. The stirring bar preferably has a cross-sectional shape that imparts radially outward motion to the slurry and grinding media. Furthermore, the stirring bar preferably has an airfoil cross-sectional shape.
[0012]
In another preferred embodiment of the present invention, the stirring member closest to the slurry discharge port is a disk-shaped member, and the slurry discharge port is disposed between the disk-shaped member and the end of the sleeve adjacent to the member. A slurry passage leading to is formed.
[0013]
Furthermore, the present invention provides a sludge treatment apparatus, which comprises a sedimentation tank that receives sludge discharged from a sewage treatment plant and precipitates and separates solids, and any of the above-described configurations. A medium stirring pulverizer, a conduit connecting a slurry take-out port for removing excess sludge slurry provided at the bottom of the settling tank, and a slurry introducing port of the medium stirring pulverizer, and disposed in the conduit A sludge pump and a slurry return circuit for returning the slurry from the slurry discharge port of the above-described medium agitation type pulverizer to the precipitation tank, and circulating the slurry between the precipitation tank and the medium agitation type pulverizer Configured to grind excess sludge solids. In this case, the sludge treatment apparatus is preferably provided with a digester tank that digests sludge with anaerobic bacteria in the slurry return circuit, and the sludge from the sewage treatment plant is introduced into the digester tank.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a schematic system diagram showing an example of a sludge treatment apparatus using the medium agitation pulverizer of the present invention for treating surplus sludge discharged from a sewage treatment facility. The sludge treatment apparatus includes an adjustment tank 1 that receives sludge from a sewage treatment facility, a digestion tank 2 connected to the adjustment tank 1, and a sedimentation tank 3 connected to the digestion tank 2.
[0016]
The sludge received by the adjustment tank 1 contains a large amount of water, but the adjustment tank 1 concentrates this sludge into a concentrated sludge. A digestion tank 2 is connected to the adjustment tank 1. The digester 2 has a sealed structure and has a stirring blade 2a inside. The digestion tank 2 is a tank for digesting sludge with anaerobic bacteria, and a large amount of methane gas is generated as a result of digestion. Methane gas is sent to a gas storage tank (not shown) and used as a heat source.
[0017]
The slurry portion in the digester 2 is sent from the digester 2 to the settling tank 3. In the sedimentation tank 3, the surplus sludge portion of the slurry sent from the digestion tank 2 is precipitated, and the supernatant portion is sent to a sterilization tank (not shown) and discharged outside through a sterilization treatment.
[0018]
One end of a conduit 5 having a sludge pump 4 is connected to the bottom of the settling tank 3. The other end of the conduit 5 is connected to the slurry inlet of the medium agitating crusher 6 according to one embodiment of the present invention. The slurry discharge port of the pulverizer 6 is connected to the digester 2 via a return circuit 7.
[0019]
FIG. 2 is a longitudinal sectional view showing the structure of the medium agitating pulverizer 6 embodying the present invention. The pulverizer 6 includes a cylindrical hollow vessel 10. A crushing chamber 11 is formed inside the vessel 10. In the illustrated embodiment, the grinder 6 is a vertical type, and the vessel 10 is held substantially vertically. A lower lid 12 is attached to one end of the vessel 10, that is, the lower end in the illustrated example. A slurry inlet 13 is formed in the cover plate 12, and the aforementioned conduit 5 is connected to the slurry inlet 13. An upper lid 14 is attached to the other end of the vessel 10, that is, the upper end in the illustrated example. A slurry discharge port 15 having a circular opening shape is formed at the center of the upper lid plate 14.
[0020]
A stirring shaft 16 is inserted into the vessel 10 in the axial direction of the vessel 10 through a slurry discharge port 15 formed in the center of the upper lid plate 14. A box-shaped outlet cover 17 is provided outside the upper cover plate 14 so as to surround the slurry discharge port 15. Although not shown, the cover 17 and the stirring shaft 16 are sealed with an appropriate seal member. ing. A slurry outlet chamber 18 is formed inside the box-shaped outlet cover 17.
[0021]
The stirring shaft 16 is provided with a plurality of stirring members 19 at intervals in the axial direction. The stirring member 19 is a disc shape in the illustrated embodiment, but may have another shape. As is well known in the technical field of medium agitating crushers, the crushing chamber 11 is filled with crushing media 20 such as glass beads and steel beads. The slurry inlet 13 of the lower lid 12 is connected to the conduit 5 from the settling tank 3, and the slurry outlet chamber 18 is connected to the return circuit 7 that returns to the digester 2. The stirring shaft 16 is rotationally driven by a power drive device (not shown).
[0022]
Surplus sludge slurry pumped from the sedimentation tank 3 by the sludge pump 4 is introduced into the pulverization chamber 11 from the slurry inlet 13 of the lower lid 12. In the grinding chamber 11, the grinding medium 20 is stirred by the stirring member 19 of the stirring shaft 16 that is rotationally driven, and the slurry is subjected to a strong shearing action while passing between the grinding media 20 and is contained in the slurry. The cell membrane of the fungus is destroyed. However, the hair, pulp fibers, and the like contained in the excess sewage sludge are not destroyed and go directly to the slurry discharge port 15. Therefore, when a screen for separating the medium and a separation slit are provided at the slurry outlet as in the conventional medium stirring type pulverizer, the screen or the slit is clogged by hair or pulp fibers.
[0023]
In the illustrated embodiment of the present invention, in order to cope with this problem, the slurry discharge port 15 is not provided with a screen or a slit for separating the medium, and the slurry discharge port 15 remains an opening formed in the upper cover plate 14. To do. This opening is large enough to allow the grinding medium 20 to pass through, and also allows hair and pulp fibers to pass through without clogging. Specifically, the radial dimension of the slurry discharge port 15 formed between the stirring shaft 16 and the opening edge of the cover plate 14 is a width of 10 mm or more. This size needs to be a size that allows the hair and pulp fibers contained in the excess sludge slurry to pass through without clogging, and in this embodiment, the slurry outlet 15 has an annular shape around the stirring shaft 16. However, it is not limited to this shape, and it can be an opening of an arbitrary shape formed in the cover plate 14 away from the stirring shaft 16. However, from the viewpoint of preventing clogging of hair and pulp fibers contained in the slurry, it is most preferable to form an annular opening having a sufficient width so as to surround the stirring shaft 16 as in the structure of the illustrated embodiment.
[0024]
In order to prevent the pulverizing medium 20 from coming out of the pulverizer during operation of the pulverizer, the upper cover plate 14 has a cylindrical sleeve 21 so as to surround the slurry discharge port 15 and extend into the pulverization chamber 11. Is provided. Among the stirring members 19 provided on the stirring shaft 16, the disk-shaped stirring member 19 a closest to the slurry discharge port 15 includes a plurality of pieces so as to extend in the direction of the upper cover plate 14 substantially parallel to the stirring shaft 16. Stirring bars 22 are attached at intervals in the circumferential direction. Between the inner end portion in the axial direction of the sleeve 21 and the stirring member 19a, a slurry passage 23 through which the slurry is directed toward the slurry discharge port 15 is formed. The slurry passage 23 is also sized so that hair and pulp fibers can pass through without clogging.
[0025]
FIG. 3 is an enlarged sectional view showing the vicinity of the slurry discharge port 15 of the pulverizer. The slurry containing excess sludge introduced into the pulverization chamber 11 in the vessel 10 from the slurry inlet 13 moves upward in the vessel 10 by the pressure of the sludge pump 4. During this time, the slurry undergoes a shearing action between the pulverization media 20 being stirred by the stirring member 19, and the cell membrane of the bacterial cells contained in the sludge is destroyed. The slurry that has reached the vicinity of the upper cover plate 14 having the slurry discharge port 15 is subjected to a strong stirring action by the stirring member 19a and the stirring bar 22 at the end together with the grinding medium 20, and swirls at a high speed. The specific gravity of the grinding media 20 is about 2.5 times that of the slurry in the case of glass beads, and about 8 times that of the slurry in the case of steel beads. Since the centrifugal force generated by the swirling motion is about 100 G, the grinding medium receives a far greater radial outward force than the slurry. Therefore, the grinding medium 20 performs a circulation operation that flows outward in the radial direction as indicated by an arrow A. Along with this, the slurry flows in the inlet direction along the outer side of the cylindrical sleeve 21 as shown by the arrow B, and is formed between the stirring member 19a at the end and the inner end in the axial direction of the sleeve 21. Through the slurry passage 23, the flow direction is reversed in the axial direction and enters the cylindrical sleeve 21, enters the return circuit 7 from the outlet chamber 18 through the slurry discharge port 15, and circulates again in the sludge treatment apparatus.
[0026]
Since the flow path of the slurry does not have a portion that is clogged by hair or pulp fibers, the clogging problem does not occur as in a conventional medium agitating pulverizer. Further, since the grinding medium 20 receives a high centrifugal force based on the swirling action by stirring, the grinding medium 20 is pushed outward in the radial direction, and the possibility of entering the cylindrical sleeve 21 becomes extremely low. In addition, when this medium agitation type pulverizer is used for the treatment of excess sewage sludge, there is no adverse effect even if a small amount of pulverization medium is mixed in the slurry exiting the pulverizer.
[0027]
FIG. 4 is a cross-sectional view showing an example of a configuration for increasing a radially outward force acting on the mixture of the grinding medium and the slurry in the vicinity of the slurry outlet of the vessel. As shown in the figure, the plurality of stirring bars 22 provided on the stirring member 19a at the end have an airfoil cross-sectional shape. The stirring bar 22 is arranged so that the suction side of the airfoil having a large curvature faces the radially outer side of the vessel 10. The rotation direction is the direction indicated by arrow C in FIG. With this arrangement, the mixture of slurry and grinding media is subjected to a strong radial outward force. Therefore, in this arrangement, the possibility of the grinding medium 22 entering the inside of the cylindrical sleeve 21 is further reduced.
[0028]
The slurry processed by the medium agitation type pulverizer 6 is returned to the digester 2 of the processing apparatus by the return circuit 7 shown in FIG. 1, digested again, and sent to the sedimentation tank 3. . Such circulation is performed as many times as necessary, and the excess sludge accumulated at the bottom of the settling tank 3 is taken out by opening the valve 8 of the conduit 9 and incinerated by the incinerator 24 or the like. According to the present invention, the amount of excess sludge that is finally treated in this way is greatly reduced. Further, the amount of methane gas generated in the digestion tank 2 increases dramatically.
[0029]
As mentioned above, although embodiment of this invention was described about the specific structure, this invention can be implemented also with a different form from embodiment shown in figure. For example, in the illustrated embodiment, the pulverizer is a vertical type, but the present invention can be implemented without any trouble even with a horizontal type pulverizer.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an arrangement of an excess sludge treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an example of a medium agitating pulverizer used in the excess sludge treatment apparatus of FIG.
3 is an enlarged cross-sectional view showing a structure in the vicinity of a slurry outlet of the pulverizer shown in FIG.
4 is a cross-sectional view taken along line IV-IV in FIG.
[Explanation of symbols]
1 ... adjustment tank, 2 ... digestion tank, 3 ... sedimentation tank, 4 ... sludge pump,
5 ... conduit, 6 ... medium agitating crusher, 10 ... vessel,
11 ... grinding chamber, 13 ... slurry inlet, 15 ... slurry outlet,
16 ... stirring shaft, 18 ... outlet chamber, 19 ... stirring member,
20 ... grinding media, 21 ... cylindrical sleeve, 22 ... stirring bar,
23 ... Slurry passage

Claims (9)

A cylindrical vessel having a crushing chamber inside;
A slurry inlet provided at one end of the grinding chamber;
A slurry outlet provided in a cover plate for closing the other end of the grinding chamber;
An agitation shaft rotatably disposed in the vessel;
A plurality of stirring members provided to extend radially outward from the stirring shaft at positions spaced in the axial direction of the stirring shaft;
With
The pulverizing chamber is filled with a pulverizing medium, the slurry is introduced from the slurry introduction port while rotating the stirring shaft, and the slurry is discharged from the slurry discharge port, thereby pulverizing solids contained in the slurry. It is a medium stirring type pulverizer that has come to perform,
The slurry discharge port is an opening formed in the lid plate and having a size through which the grinding medium can pass.
The lid plate is provided with a cylindrical sleeve so as to surround the slurry discharge port and extend substantially in the axial direction of the stirring shaft, and there is no hole on the side wall of the sleeve so that the slurry can pass therethrough. It is configured to flow along the outer side, the end opposite to the cover plate is open, and the slurry that reaches the vicinity of the vessel end on the slurry discharge port side of the grinding chamber is caused by the sleeve. The direction is reversed toward the slurry inlet and flows along the sleeve, during which the slurry is separated from the pulverizing medium under the rotational motion by the stirring action of the stirring member, and the slurry portion of the sleeve It enters the said sleeve from the opening the said end portion and adapted to be discharged from the opening through the interior of said sleeve constituting said slurry outlet port,
A medium stirring type pulverizer characterized by the above.   2. The medium agitation type pulverizer according to claim 1, wherein the opening forming the slurry discharge port has a width of at least 10 mm.   3. The medium agitation type pulverizer according to claim 1 or 2, wherein the agitation member closest to the slurry discharge port extends substantially in the axial direction of the agitation shaft at a position radially outward of the sleeve. The medium stirring type pulverizer is characterized in that the stirring bar is provided with a stirring bar and rotational motion is given to the slurry around the sleeve by the stirring bar.   4. The medium agitation type pulverizer according to claim 3, wherein the agitation bar has a cross-sectional shape that imparts a radially outward motion to the slurry and the pulverization medium.   5. The medium agitation type pulverizer according to claim 4, wherein the agitation bar has an airfoil cross-sectional shape.   The medium stirring type pulverizer according to any one of claims 1 to 5, wherein the stirring member closest to the slurry discharge port is a disk-type member, and the disk-type member and the disk-type member A medium agitation type pulverizer, wherein a slurry passage leading to the slurry discharge port is formed between an end portion of the sleeve adjacent to a member and the inside of the sleeve.   The medium stirring type pulverizer according to any one of claims 1 to 6, wherein the slurry discharge port passes through an edge of an opening formed in a central member of the lid plate and the opening. A medium agitation type pulverizer characterized by being an annular passage formed between the agitation shaft and the agitation shaft. A sedimentation tank that receives sludge discharged from a sewage treatment plant and precipitates and separates solids;
A medium stirring type pulverizer according to any one of claims 1 to 7,
A conduit connecting a slurry outlet for taking out the excess sludge slurry provided in the lower part of the settling tank and a slurry inlet of the medium agitating crusher;
A sludge pump disposed in the conduit;
A slurry return circuit for returning the slurry from the slurry discharge port of the medium agitating crusher to the settling tank;
The slurry is circulated between the settling tank and the medium agitating crusher to pulverize excess sludge solids in the slurry.
A sludge treatment apparatus characterized by that.   The sludge treatment apparatus according to claim 8, wherein a digestion tank for digesting sludge with anaerobic bacteria is provided in the slurry return circuit, and sludge from a sewage treatment plant is introduced into the digestion tank. Sludge treatment equipment.

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