JP2003088896A - Screw press type sludge dewatering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leak, clogging, etc., of sludge in a filtering area by effectively using the filtering area of a screw press type sludge dewatering apparatus in dehydration, setting the optimal filtration pressure of the filtering area, and thereby improving dehydration efficiency. SOLUTION: In the screw press type sludge dewatering apparatus, a sludge feeding port 19 is disposed above a dewatered material discharge port 30 in a height direction. A filtrate container which houses the filtering area is filled with a filtrate, and the filtering area is submerged in the filtrate. The dewatering apparatus is provided with a filtrate discharge port 26 at the lower part of the filtrate container 24, and a height-adjustable filtrate discharge part 28 which is arranged successively at the filtrate discharge port and discharges the filtrate upwards. Adjusting the height of the filtrate discharge part optimizes filtration pressure in the filtering area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw press which is particularly excellent in dewatering efficiency and prevents sludge from adhering to the filtration surface or clogging, thereby eliminating the need for cleaning the filtration surface. Type sludge dewatering device.

[0002]

2. Description of the Related Art Sludge dewatering is performed prior to the disposal or incineration of various sludges. As a sludge dewatering device used for such sludge dewatering, there is a screw press type sludge dewatering device. This type of screw press type sludge dewatering device, for example, as described in Japanese Patent No. 2512683, throws in (annular supply) from an input port into an annular space between a cylindrical body and an inner cylinder which are concentric with each other. Dehydration is performed by transferring the mixture of sludge (suspension and solid components) and water (clarified water) (substance to be dehydrated, hereinafter referred to as “sludge mixture”) toward the outlet by the rotation of the spiral screw. It is a thing. That is, the screw press type sludge dewatering device squeezes and dewaters the sludge mixture by rotationally driving a spiral screw provided on the outer peripheral surface of the inner cylinder, and the dehydrated water (filtrate) is drained on the drain screen ( The sludge (dehydrated product) that has been dehydrated is discharged from the sludge discharge port.

Such a conventional screw press type sludge dewatering device is often arranged horizontally as shown in FIG. 4, and the sludge mixture 2 charged from the charging port 1 has a cylindrical body 3.
Gather under the annular space 5 between the shaft body 4 and the shaft body 4, and above the annular space 5, the sludge mixture 2 moves away from the filtration surface 6.
Then, since the filtration surface 6 is not effectively used, the dehydration efficiency is reduced. Further, since the sludge mixture 2 transferred to the discharge port gradually increases the sludge concentration and becomes a cake-shaped dehydrated product, the water content decreases near the cake discharge port 7 (cake outlet), Accumulates on the filtration surface to easily cause clogging. When sludge is accumulated or clogging occurs, the dewatering efficiency of the dewatering device is reduced. Therefore, in order to maintain the dewatering efficiency, for example, it is necessary to wash the deposit on the filtration surface with washing water.

By the way, the discharge of the filtrate in the screw press type sludge dewatering device is carried out by the filtration pressure which is the difference between the pressure of the sludge mixture near the filtration surface and the pressure of the dehydrated filtrate. And the higher this filtration pressure is,
The water content of the sludge mixture is quickly dehydrated. However, if the filtration pressure becomes too high, even sludge will adhere (accumulate) or become clogged to the filtration surface in order to pass through the filtration surface, and will further pass (leak). On the other hand, the higher the sludge concentration of the sludge mixture, the higher the filtration pressure must be set.

Therefore, as shown in FIG. 5, the cylindrical body 3 and the shaft body 4 which are concentric with each other are arranged vertically, and the charging port 1 is positioned above the cake discharging port 7 in the height direction of the dehydrator. A screw press type dewatering device arranged in a position is conceivable. In such a screw press type dehydrator, the sludge mixture 2 is evenly distributed in the circumferential direction in the annular space 5 between the cylindrical body 3 and the shaft body 4 to fill the annular space 5 with the filtrate. Since the surface 6 flows down toward the filtrate discharge port 8, the filtration surface 6 of the cylindrical body 3 is effectively used for dehydration, and the dehydration efficiency is improved.

On the side of the inlet 1, the annular space 5
Since the water depth of the sludge mixture 2 filled in is low, the filtration pressure applied to the filtration surface 6 is low. On the other hand, on the cake outlet 7 side, the water depth is deep and the filtration pressure is high.
Therefore, the filtering pressure is low on the side of the inlet 1 where the sludge concentration is low, and the filtering pressure is high on the side of the cake outlet 7 where the sludge concentration is high, and the filtering pressure becomes the sludge concentration of the sludge mixture 2 filling the annular space 5. It will be compliant. Therefore, it is possible to prevent the filter surface 6 from being clogged.

[0007]

By the way, the sludge mixture is optimized by optimizing the filtration pressure so that the sludge does not adhere to the filtration surface or is not clogged and does not leak the filtration surface, and only water is efficiently discharged from the sludge mixture. Is performed by setting the difference between the pressure inside the filtration surface and the pressure outside the filtration surface. In the screw press type sludge dewatering device shown in FIG. 5, the pressure inside the filtration surface 6 can be set by the pressure depending on the water depth of the sludge mixture 2 in the annular space 5 and the pressing of the sludge mixture by the spiral screw 9. However, since the filtrate dehydrated on the filtration surface 6 flows down toward the filtrate discharge port 8, the pressure outside the filtration surface 6 cannot be set. Therefore, it is difficult to set the optimum filtration pressure according to the sludge concentration.

The present invention has been made in order to solve the above problems, and effectively utilizes the filtration surface of the cylindrical body for dehydration to improve the dehydration efficiency, and facilitates setting of the optimum filtration pressure. , Adhesion of sludge on the filtration surface, clogging,
Furthermore, it aims at providing the screw press type | formula sludge dewatering apparatus which can improve dewatering efficiency, preventing a leak.

[0009]

In order to achieve the above object, according to the present invention, in claim 1, a cylindrical body having a shaft body arranged concentrically inside is provided substantially vertically. And a filtration surface provided as a peripheral wall of the tubular body and an upper end portion of the tubular body, and the sludge mixture is put into an annular space formed between the tubular body and the shaft body. An input port, a screw provided in a spiral shape on the outer peripheral surface of the shaft body and driven to rotate, and a screw for transferring the sludge mixture introduced into the annular space downward, and to the outside of the cylindrical body via the filtration surface. A filtrate container containing the filtered filtrate, a filtrate outlet provided at the lower end of the filtrate container, and a filtrate outlet connected to the filtrate outlet to discharge the filtrate to the outside, and a discharge height position of the filtrate. Is adjusted so that the filtrate can be filtered by the filtrate contained in the filtrate container. A filtrate discharge section for submerged surfaces, the cylindrical body a screw press sludge dewatering apparatus and a dehydrated product discharge outlet for discharging are provided at the lower end dehydrate from said annular space is provided.

In the screw press type sludge dewatering apparatus thus constructed, the filtration surface is submerged in the filtrate container containing the filtrate. Therefore, the entire surface of the filtration surface can be effectively used to improve the dehydration efficiency, and by adjusting the height of the filtrate discharge port for discharging the filtrate of the filtrate container, the filtration surface provided as the peripheral wall of the cylindrical body. The pressure difference between the inner side (annular space side) and the outer side of the filtration surface (filtrate container side) can be adjusted.

That is, the filtration pressure can be optimized by adjusting the height of the filtrate discharge port in consideration of the pressure (for example, the pressure on the natural downstream side) for introducing the sludge mixture into the annular space. By thus optimizing the filtration pressure, it is possible to improve the dehydration efficiency while preventing the sludge from adhering to the filtration surface, clogging, and further leaking. Even if the filtration pressure is optimized, a very small amount of sludge may leak on the filtration surface, but such a small amount of leaked sludge will settle toward the lower end of the filtrate container, and this lower end It is discharged together with the liquid flow of the filtrate from the filtrate outlet provided in the.

According to a second aspect of the present invention, further, partition walls are provided to divide the space between the filtrate container and the cylindrical body into a plurality of spaces in the height direction, and the partition walls are provided at the lower ends of the respective spaces. Provided is a screw press-type sludge dewatering device comprising: a filtrate discharge port, and a filtrate discharge unit that is connected to each of these filtrate discharge ports and discharges the filtrate to the outside while filling each space with the filtrate. To be done.

In the screw press type sludge dewatering device thus constructed, the space between the filtrate container for containing the filtrate discharged from the filtration surface and the cylindrical body is divided into a plurality of parts in the height direction. Then, by adjusting the height of the filtrate discharge portion for each of the plurality of divided spaces, it is possible to adjust the filtration pressure on the filtration surface facing the plurality of divided spaces. Therefore, the sludge mixture thrown into the annular space corresponds to the sludge concentration increasing while being transferred downward from the upper end of the annular space, that is, the position of the filtration surface in the water depth (water depth in the annular space) direction. Corresponding to the change in the optimum filtration pressure due to, the filtration pressure can be optimized over the entire filtration surface, and compared with the case where the space between the filtrate container and the cylinder is not divided, the sludge on the filtration surface It is possible to further improve the dehydration efficiency while further preventing adhesion, clogging and leak.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A screw press type sludge dewatering device (hereinafter referred to as "sludge dewatering device") according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a sludge dewatering device according to the present invention. The sludge dewatering device 10 includes a cylindrical body 11 vertically arranged on a base (not shown).
And a shaft body 12 arranged concentrically with the cylindrical body 11. The upper rotary shaft 13 of the shaft body 12 has its upper end coupled to a motor 14 via a speed reducer (not shown), and
A lower end rotary shaft 15 of the shaft body 12 is rotatably supported by a bearing 16. A spiral screw 17 is provided on the outer peripheral surface 12 a of the shaft body 12. The spiral screw 17 is arranged in an annular space 18 between the cylinder body 11 and the shaft body 12, and the shaft body 12 is driven by the motor 14. When driven to rotate, it rotates together with the shaft body 12.

At the upper end of the cylindrical body 11, there is provided a charging port 19 which communicates with the annular space 18, and the charging port 19 communicates with the aggregating tank 21 via a pipe 20. Flocculation tank 21
A stirring blade 23 that is rotationally driven by a stirring motor 22
Is arranged so that the concentrated sludge supplied to the coagulation tank 21 and the coagulant are mixed by stirring. The sludge mixture in the flocculation tank 21 has the height (h1) of the water surface thereof, and is naturally fed downstream into the annular space 18 as a substance to be dehydrated via the inlet 19 of the sludge dehydrator 10.

The sludge dewatering apparatus 10 also has a filtrate container 24 arranged around the cylindrical body 11 so as to be concentric therewith, and the filtrate container 24 is provided with a drain screen 11d of the cylindrical body 11. A filtrate passage 25 (annular passage) is formed between them and accommodates the filtrate filtered by the discharge screen 11d. A filtrate discharge port 26 is provided on the peripheral wall of the lower end portion of the filtrate container 24, and a filtrate pipe 27 is connected to the filtrate discharge port 26. This filtrate pipe 27 is
After slightly extending in a substantially horizontal direction from the filtrate discharge port 26, it rises upward, and a substantially tubular filtrate discharge portion 28 is vertically adjusted with respect to the filtrate pipe 27 at the rising tip portion. It is provided as possible. Further, the upper end of the filtrate discharge part 28 is open, and the drain 29 extends horizontally from slightly below the upper end of the filtrate discharge part 28 to discharge the filtrate to the outside of the sludge dewatering device 10. It is like this. Here, the water level on the discharge surface of the filtrate in the drain 29 is the height (h2).

The lower end of the shaft body 12 has a lower wall 11 of the cylindrical body 11.
A blocking plate 12b that extends downward through the central opening of c is fixed to the lower end surface of the shaft body 12 to substantially close the lower end surface of the annular space 18. A gap 30 is formed between the blocking plate 12b and the lower wall 11c of the tubular body 11. Then, the sludge dehydrated in the annular space 18 is discharged from the gap 30 to the outside of the sludge dewatering device through the central opening of the lower wall 11c. As described above, the gap 30 has a role of a sludge discharge port (cake discharge port).

Here, the appearance of the cylindrical body 11 is shown in FIG. The cylindrical body 11 includes a peripheral wall 11a and an upper wall 11 through which the shaft body 12 is inserted.
b and an annular lower wall 11c extending inward in the radial direction from the lower end of the peripheral wall 11a. Here, the upper wall 11b closes the upper side of the tubular body 11 together with the shaft body 12. Further, the peripheral wall 11a is made of, for example, punching metal except its upper end portion and lower end portion, and this punching metal has a large number of holes to form a drainage screen 11d (filtering surface).

The sludge dewatering device 10 having the above-described structure
Then, the sludge mixture is put into the annular space 18 from the coagulation tank 21. Then, the sludge dewatering device 10 and thus the annular space 18 are vertically arranged, and the inlet 19 is provided at the uppermost position of the annular space 18. Therefore, the sludge mixture is rotated by the spiral screw rotating together with the shaft 12. 17
Is transferred downward in the annular space 18. And
The sludge mixture is uniformly distributed in the circumferential direction and filled in the annular space 18 by the action of gravity.

When the annular space 18 is filled with the sludge mixture, the filtrate is discharged from the discharge screen 11d of the cylindrical body 11 and stored in the filtrate container 24. This filtrate container 2
The filtrate stored in 4 is the filtrate outlet 26 and the filtrate pipe 2.
7 and the filtrate discharge part 28, and flows to the drain 29, and is discharged from the drain 29 to the outside of the sludge dewatering device 10. Here, the water level (h2) of the discharge surface of the filtrate in the drain 29 is at a height at which the discharge screen 11d is submerged in the filtrate.

As described above, the filtration pressure of the discharge screen 11d submerged in the filtrate is determined by the pressure difference between the inside and the outside of the discharge screen 11d. And the annular space 1
The water level (h1) of the flocculation tank 21 for introducing the sludge mixture into 8 through the input port 19 at the natural downstream is higher than the water level (h2) of the discharge surface of the filtrate. Then, the filtration pressure in the discharge screen 11d is the difference (d) between the water level (h1) in the coagulation tank 21 and the water level (h2) on the discharge surface of the filtrate.
h = h1−h2). That is, by adjusting the height of the filtrate discharge part 28 with respect to the filtrate pipe 27, the filtration pressure in the discharge screen 11d can be set to the optimum filtration pressure.

Thus, when the optimum filtration pressure of the discharge screen 11d is set, the dewatering efficiency of the discharge screen 11d can be improved, and at the same time, sludge can be prevented from adhering to the filtration surface, clogging, and leakage. . The optimum filtration pressure depends on the strength (flock strength) of sludge contained in the sludge mixture and the sludge concentration, but the water level (h1) of the flocculation tank 21 and the discharge of the filtrate in the drain 29 are set for setting the optimum filtration pressure. The water level difference (dh) from the surface water level (h2) is usually within the range of 20 mm to 100 mm.

FIG. 3 shows a second embodiment of the sludge dewatering device according to the present invention. The constituent elements having the same functions as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the sludge dewatering device 40 shown in FIG. 3, in addition to the sludge dewatering device 10 according to the first embodiment, the filtrate passage formed between the filtrate container 24 and the tubular body 11 is filtered by the partition walls 24a and 24b. It is divided into approximately three equal parts in the axial direction of the container 24. A filtrate passage 25a is provided between the upper end of the filtrate container 24 and the partition wall 24a, a filtrate passage 25b is provided between the partition wall 24a and the partition wall 24b, and a filtrate passage 25c is provided between the partition wall 24b and the lower end of the filtrate container 24. , Respectively formed.

Further, a filtrate outlet 26a is provided on the peripheral wall of the filtrate container 24 at the lower end of the filtrate passage 25a, and a filtrate pipe 27a is connected to the filtrate outlet 26a. The filtrate pipe 27a extends slightly horizontally from the filtrate discharge port 27a and then rises upward. The filtrate discharge portion 28 is provided at the rising tip end portion.
a is connected. The filtrate discharge part 28a has a substantially tubular shape and is vertically adjustable in height with respect to the filtrate pipe 27a. The upper end of the filtrate discharge part 28a is open, and a drain 29a having an open front end extends horizontally from slightly below the upper end of the filtrate discharge part 28a.

Similarly, a filtrate discharge port 26b is provided on the peripheral wall of the filtrate container 24 at the lower end of the filtrate passage 25b, a filtrate pipe 27b is connected thereto, and a filtrate discharge portion 28b having a drain 29b is connected thereto. Further, a filtrate discharge port 26c is provided on the peripheral wall of the filtrate container 24 at the lower end of the filtrate passage 25c, a filtrate pipe 27c is connected thereto, and a filtrate discharge portion 28c having a drain 29c is connected thereto.

Then, by adjusting the height of the filtrate discharge portion 28a, the water level (h2a) of the filtrate discharge surface in the drain 29a is adjusted so that the filtrate passage 25a is filled with the filtrate and the filtrate passage 25a is faced. Discharge screen 1
Allow 1d to submerge in the filtrate. In addition, the drain 29a
The water level (h2a) on the discharge surface of the filtrate in
The position is lower than the water level (h1) in the height direction. Also,
Water level (h2b) of the discharge surface of the filtrate in the drain 29b
Is lower than the water level (h2a), and the water level (h2c) on the discharge surface of the filtrate in the drain 29c is the water level (h2a).
The heights of the filtrate discharge portions 28b and 28c are set so as to be lower than those in b), and the filtrate passages 25b and 25c are filled with the filtrate, respectively, and the discharge screen 11d facing the filtrate passage 25b and the filtrate passage 25c are covered. The discharged screen 11d is soaked in the filtrate.

Then, the filtration pressure (Pa) at the portion where the discharge screen 11d faces the filtrate passage 25a, the difference (dha) between the water level (h1) in the coagulation tank 21 and the water level (h2a) at the drainage surface of the filtrate in the drain 29a. = H1-h2a)
Depends on Similarly, the filtration pressure (Pb) of the portion where the discharge screen 11d faces the filtrate passage 25b is the difference (dhb = h1) between the water level (h1) of the flocculation tank 21 and the water level (h2b) of the drainage surface of the filtrate in the drain 29b. -H2b)
Depends on

Similarly, the filtration pressure (Pc) of the portion of the discharge screen 11d facing the filtrate passage 25c is the aggregation tank 21.
(H1) and the water level (h2c) of the drainage surface of the filtrate in the drain 29c (dhc = h1-h2c). Here, since h2a>h2b> h2c, dhc>dhb> dha, and then Pc
The relationship of>Pb> Pa is established.

On the other hand, the sludge concentration of the sludge mixture transferred downward in the annular space 18 by the spiral screw 17 becomes smaller as it is transferred downward in the discharge screen 11d.
It is dehydrated to a high concentration. Therefore, the discharge screen 11
The lower the d, the higher the optimum filtration pressure should be.
In the sludge dewatering device 40, as described above, each filtrate passage 25
The filtration pressure can be adjusted corresponding to the respective discharge screen 11d portions facing a to 25c. That is, in the sludge dewatering device 40, the filtration pressure can be made higher toward the lower side of the discharge screen 11d where the sludge concentration becomes higher, and the filtration pressure can be optimized over the entire surface of the discharge screen 11d.

Although the filtrate passage is divided into three in the second embodiment, it may be divided into two or four or more. Sludge mixture to be dehydrated,
This is because the number of divisions of the filtrate passage that can further optimize the filtration pressure over the entire surface in the height direction of the discharge screen changes depending on the shape and size of the sludge dewatering device. Also,
Assuming that the sludge is put into the sludge dewatering device in the natural downstream from the coagulation tank, the water level on the discharge surface of the filtrate at the drain was set lower than the water level in the coagulation tank. When the sludge is discharged into the sludge dewatering device, the water level on the discharge surface of the filtrate at the drain is set in consideration of the pressure generated inside the discharge screen by this pump.

As described above, the present invention is not limited to the first and second embodiments described above, and can be carried out by appropriately modifying it without departing from the spirit of the present invention.

[0032]

As described above, according to the screw press type sludge dewatering device of the present invention, the entire filtration surface for dehydrating water from the sludge mixture is submerged in the filtrate, so that the filtration surface is effectively used for dehydration. In addition to improving the dewatering efficiency, it is possible to easily set the optimum filtering pressure on the filtering surface and prevent the sludge from adhering to the filtering surface, clogging, and leaks while further improving the dewatering efficiency. It is possible for the screw press type sludge dewatering device that
It can exert a very important effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a main part of a first embodiment of a screw press type sludge dewatering device according to the present invention.

FIG. 2 is an external view of a cylinder having a filtration surface (exhaust screen) of the screw press type sludge dewatering device of FIG.

FIG. 3 is a sectional view showing a schematic configuration of a main part of a second embodiment of a screw press type sludge dewatering device according to the present invention.

FIG. 4 is a schematic diagram showing a filling state of a sludge mixture in a conventional screw press type sludge dewatering device arranged horizontally.

FIG. 5 is a schematic diagram showing a filled state of a sludge mixture in a screw press type sludge dewatering device arranged vertically.

[Explanation of symbols]

10, 40 Screw type sludge dewatering device 11 Cylindrical body 11d Discharge screen 12 Shaft body 12a Shaft body outer peripheral surface 17 Helical screw 18 Annular space 19 Input port 24 Filtrate container 24a, 24b Partition walls 25, 25a, 25b, 25c Filtrate passage 26, 26a, 26b, 26c Filtrate discharge port 28, 28a, 28b, 28c Filtrate discharge part 30 Gap

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B30B 9/14

Claims (2)

[Claims] 1. A cylindrical body having a shaft body arranged coaxially inside thereof and provided substantially vertically, a filtering surface provided as a peripheral wall of the cylindrical body, and an upper end of the cylindrical body. And a charging port for charging the sludge mixture into an annular space formed between the cylindrical body and the shaft body, which is spirally provided on the outer peripheral surface of the shaft body and is driven to rotate.
A screw for transporting the sludge mixture introduced into the annular space downward, a filtrate container for storing the filtrate filtrated to the outside of the cylinder through the filtration surface, and a lower end portion of the filtrate container. The filtrate outlet is connected to the filtrate outlet to discharge the filtrate to the outside, and the filtrate height is adjustable so that the filtrate is stored in the filtrate container to submerge the filtration surface. A screw press type sludge dewatering device, comprising: a filtrate discharging part for allowing the dewatering part to discharge; 2. The screw press type sludge dewatering device according to claim 1, further comprising a partition wall that divides a space between the filtrate container and the cylindrical body into a plurality of spaces in a height direction, and the partition wall. A filtrate outlet provided at the lower end of each of the spaces, and a filtrate outlet connected to each of the filtrate outlets to discharge the filtrate to the outside while filling the space with the filtrate. A screw press-type sludge dewatering device comprising: