JP2002126407A - Settling tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wear of an elastic seal member for sealing between the lower and part of a fixing type center well and the upper end part of a rotary center column in a settling tank, which is provided with the fixing type center well and the rotary center column and into which a liquid to be treated is introduced from a distributor provided at the lower part of the rotary center column through the fixing type center well and the rotary center column. SOLUTION: The settling tank is sealed by providing the elastic seal members 24 and 27 respectively on both of the fixing type center well 21 and the rotary center column 22 and bringing the elastic seal members 24 and 27 into sliding contact with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge blanket type sedimentation tank, and more particularly to a sludge blanket type sedimentation tank provided with a fixed center well and a rotary center column. In the sedimentation tank that is introduced into the tank from the distributor provided at the lower part of the rotary center column, wear of the elastic seal member that seals between the lower end of the fixed center well and the upper end of the rotary center column was prevented. It relates to a settling tank.

[0002]

2. Description of the Related Art Conventionally, in activated sludge treatment equipment and coagulation sedimentation treatment equipment, sedimentation using a solid-liquid separation tank (sedimentation tank) as means for separating a sludge mixture (coagulation treatment liquid) into treated water and sludge. Separation is commonly employed. In this sedimentation separation, a sludge zone (sludge blanket layer) is formed in the sedimentation tank, and an introduction pipe ( Feed well), the sludge mixture is allowed to flow in from the lower part of the sludge zone and pass through the sludge zone,
A sludge blanket filtration method for filtering and separating turbid and fine SS in a sludge mixture is employed. Conventionally, as a coagulating sedimentation device equipped with a sludge blanket type sedimentation tank used in this sludge blanket filtration method,
As shown in FIG. 4 (longitudinal sectional view), FIG. 5 (plan view of the sedimentation tank portion of FIG. 4), and FIG. 6 (sectional view along the line VI-VI of FIG. 4) are proposed.

In this coagulating sedimentation apparatus, a bottom surface 1A except for a central portion of a sedimentation tank (thickener) 1 has a conical shape having a downward slope toward the center of the bottom portion. A concave portion 1B for a bearing is provided at the center of the bottom portion, and a drain pipe (not shown) is connected to this portion. A mud collecting rake 2 is provided rotatably along the inclined bottom surface 1A of the sedimentation tank 1, and a distributor 3 is provided integrally with the rake 2. The distributor 3 is a member for uniformly dispersing and supplying raw water into the sedimentation tank 1, and the rake 2 is a member for discharging the settled sludge while concentrating it using the lake action effect.

The distributor 3 is composed of a tubular body extending radially from the lower end of a center column 4 vertically extending at the center of the sedimentation tank 1. However, the arrow R
The downstream side in the direction of rotation of the distributor 3 indicated by.
Is provided with a raw water outlet 3A. A rectifying plate is fixedly installed on the upper part of the distributor 3 by welding or the like so as to extend toward the downstream side in the rotational direction, but this rectifying plate is not shown in FIGS. It is.

[0005] The upper portion of the center column 4 is an enlarged diameter portion (center well) 4A as an agglutination treatment liquid receiving portion. The center column 4 has a shaft 5A of the motor 5
And the rake 2 and the distributor 3, together with the rake 2, are configured to rotate slowly and integrally by the motor 5.

In this coagulation sedimentation apparatus, the coagulation tank 11
Is supplied from the center well 4A into the center column 4, and the raw water outlet 3A on the side surface of the distributor 3 supplies the distributor 3 and the lake 2.
Flows into the sludge zone S toward the downstream side in the rotation direction, that is, in the direction opposite to the direction in which the sludge is raked by the rake 2.
The distributor 3 and the rake 2 are connected to the motor 5
By simultaneously rotating the sludge slowly, the sludge in the sedimentation tank 1 is slowly stirred, and the generation and growth of flocs are promoted, and at the same time, a stable sludge zone is generated. The sedimented flocs are collected at the center by the rake 2 and discharged out of the tank from a drain pipe (not shown), and the clarified water overflows the overflow 6 and is taken out from the outlet 7 as treated water.

In such a sludge blanket type sedimentation tank, since the distributor 3 and the rake 2 are integrally provided at the bottom of the sedimentation tank 1, the height of the sludge zone S can be reduced, and the sludge can be reduced. The stable operation can be performed by preventing the expansion of the zone S.

Further, since the sludge zone S can be lowered, the height of the sedimentation tank 1 can be lowered to reduce the size of the apparatus.

The rake 2 is the distributor 3
Since the rake 2 is integrated with the rake 2, the rake 2 need only be attached by suspending it below the distributor 3 or the like, and a turnbuckle and a rake rotating shaft for preventing the rake 2 from dropping are unnecessary.

Further, since the raw water outlet 3A of the distributor 3 is provided on the side surface on the downstream side in the rotation direction of the distributor 3, and a straightening plate (not shown) is provided above the distributor 3, the raw water flow is provided. Hardly fluidizes the sludge zone S, and prevents the expansion of the sludge zone S and the outflow of SS into the treated water, thereby enabling a stable operation.

In FIG. 5, reference numeral 8 denotes a support plate for the rotary shaft 5A of the motor 5, but the support plate 8 is not shown in FIG. In FIG. 5,
The illustration of the motor 5 is omitted.

In the sludge blanket type sedimentation tank 1, the center column 4, distributor 3 and rake 2 rotate integrally. Thus, in order to introduce the coagulation treatment liquid into the center well 4A of the rotating center column 4, the water level of the coagulation tank 11 is set higher than that of the sedimentation tank 1,
The aggregation treatment liquid is introduced into the upper part of the center well 4A by the inflow trough 12. In addition, in FIG. 4, 13 shows the stirring device of the coagulation tank 11, and 14 shows a baffle plate.

In such a coagulating sedimentation apparatus, in order to effectively perform solid-liquid separation in the sedimentation tank 1 and obtain high-clarity treated water, the coagulation floc generated in the coagulation tank 11 is not destroyed. An important requirement is introduction into the settling tank 1. That is, when the flocculated floc is broken down and miniaturized, its sedimentability is deteriorated, and it flows out to the treated water side to deteriorate the quality of the treated water.

For this reason, in the conventional coagulating sedimentation apparatus, the head of the coagulation treatment liquid flowing from the coagulation tank 11 to the sedimentation tank 1 and the destruction of the coagulation floc due to the turbulent flow in the inflow trough 12 are prevented. For this reason, a design is made to minimize the water level difference between the flocculation tank 11 and the sedimentation tank 1 as much as possible so that an accelerated flow due to a head when flowing into the sedimentation tank 1 does not occur.

However, in the conventional coagulating sedimentation apparatus,
As shown in FIG. 4, it is necessary to introduce the flocculation treatment liquid into the precipitation tank 1 through a long inflow trough 12 from the flocculation tank 11 to the center well 4A of the precipitation tank 1. In order for the flocculation treatment liquid to flow smoothly without stagnation in such a long inflow trough 12, the inflow trough 12 needs a gradient for moving water. There are also restrictions on reducing the water level difference. Also, when the flocculation treatment liquid flows through the long inflow trough 12 having such a gradient,
Acceleration due to the hydraulic gradient occurs in the inflow trough 12, and a turbulent flow occurs in the trough 12, and the falling speed to the center well 4A increases, and the drop impact also increases.
Because this turbulence and impact break the flocculated floc,
Fine flocs, which are difficult to settle and separate, were generated in the sedimentation tank 1, and the treated water tended to deteriorate.

In the case where the center well 4A, the center column 4, the distributor 3, and the rake 2 are integrally formed, the height of this portion is 4-6.
m, the weight is heavy, the structure is complicated, and there is also a disadvantage that a great deal of labor is required for the installation work and the transport out of the tank during maintenance and inspection.

FIG. 2 shows a solution to such a problem.
As shown in (1), a sedimentation tank in which a center well and a center column are separately provided has been proposed.

A sedimentation tank 20 shown in FIG. 2 is configured such that a center well 21 is fixed and a center column 22 rotates together with the distributor 3 and the rake 2. In such a sedimentation tank 20, the center well 2
1 does not need to be rotated, so that the flocculation tank 11 and the sedimentation tank 2
0 and the center well 21 with no gradient inflow trough 23
Alternatively, the flocculation treatment liquid can be introduced into the center well 21 and the center column 22 of the sedimentation tank 20 by connecting with an inflow pipe. Therefore, as in the sedimentation tank 1 shown in FIG. 4, the flocculated floc is not broken by turbulence in the inflow trough or impact when flowing down to the center well, and the quality of the treated water is improved. In addition, since the apparatus is divided, the work of installing the apparatus, carrying out, carrying in, and the like can be easily performed.

In the coagulation and sedimentation apparatus shown in FIG. 2, a center well 21 and a center column 22 are divided, and an inflow trough 23 for introducing the coagulation treatment liquid from the coagulation tank 11 to the sedimentation tank 20 is connected to the sedimentation tank 20. Except that there is no difference in water level, the apparatus has the same configuration as the coagulation-sedimentation apparatus shown in FIGS. Therefore, members having the same functions as those shown in FIGS. 4 to 6 are denoted by the same reference numerals, and description thereof will be omitted. 2, the support plate 8 of the shaft 5A is not shown as in FIG. Also, VI in FIG.
The cross-sectional view along the line VI is the same as FIG. 6 showing the conventional device.

However, in such a split type sedimentation tank, the sedimentation tank 20 is formed through a gap between the lower end of the fixed center well 21 and the upper end of the rotary center column 22.
It is important to securely seal this portion so that the coagulation solution introduced into the tank does not leak directly into the tank. That is, when the coagulation treatment liquid is not supplied from the distributor 3 into the tank, and leaks into the tank through this gap, the coagulation floc does not sufficiently settle and the treated water flows upward from the lower part of the tank together with the treatment water. It is discharged and the quality of treated water deteriorates.

In the conventional sedimentation tank, as shown in FIG. 3, which is an enlarged view of part III in FIG. 2, a rubber plate 24 for sealing is wound around the outer periphery of the upper end of the rotary center column 22. One end is fixed to the rotary center column 22 with a holding plate 25 and bolts 26, 26, and a free piece 24A at the other end of the rubber plate 24 is elastically slidably in contact with the lower end of the fixed center well 21. By doing so, this gap is sealed.

[0022]

However, in the above-mentioned conventional sealing structure, the rubber plate 24 which rotates together with the rotary center column 22 is in sliding contact with the lower end of the fixed center well 21 so that the base of the fixed center well 21 is formed. The rubber plate 24 wears due to friction with the material metal (iron), and
The rubber plate 24 is worn out in a short period of a month. As a result, the sealing performance cannot be obtained, and the quality of the treated water in the settling tank deteriorates due to the leakage of the coagulated treated water. Further, when the rubber plate is worn as described above, it is necessary to stop the operation to replace the rubber plate and attach a new rubber plate, so that the maintenance work is complicated and the operation efficiency is disadvantageous.

The present invention solves the above-mentioned conventional problems, and comprises a fixed center well and a rotary center column, and the liquid to be treated is passed through the fixed center well and the rotary center column to form a rotary center column. Provided is a sedimentation tank which prevents wear of an elastic seal member for sealing between a lower end of a fixed center well and an upper end of a rotary center column in a sedimentation tank introduced into a tank from a distributor provided at a lower part. The purpose is to:

[0024]

In the sedimentation tank of the present invention, a cylindrical center well is fixed at the center, and a cylindrical center column is installed below the center well coaxially with the center well. The center column is rotatable about its axis, and in a settling tank in which the lower end of the center well and the upper end of the center column are sealed by an elastic seal member, the elastic seal member is connected to the center well. And the center column, and these elastic seal members are brought into sliding contact with each other.

In the sedimentation tank of the present invention, the elastic seal member is provided on both the fixed center well and the rotary center column, and these elastic seal members are brought into sliding contact with each other. Compared to the conventional seal structure that directly slides, the wear of the elastic seal member is
It is significantly reduced.

In the sedimentation tank of the present invention, a distributor extends radially from a lower portion of the rotary center column, and a mud collecting member rotatable with the distributor is provided below the distributor. It is preferable that the distributor and the mud collecting member are provided integrally, as described above,
The height of the sludge zone S of the sedimentation tank can be reduced, and expansion of the sludge zone S can be prevented, and stable operation can be performed. In addition, since the sludge zone S can be reduced, the height of the settling tank can be reduced, and the size of the apparatus can be reduced. Furthermore, since the sludge collecting member is integrated with the distributor, the sludge collecting member only needs to be attached to the lower part of the distributor, for example, by hanging it, and a turnbuckle and a rake rotating shaft for preventing the sludge collecting member from falling are unnecessary. In addition, the effect that the device configuration is simplified is also exhibited.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sedimentation tank according to the present invention will be described below with reference to the drawings.

FIGS. 1 (a) and 1 (b) are enlarged sectional views of a seal portion between a fixed center well and a rotary center column showing an embodiment of a sedimentation tank of the present invention. The sedimentation tank of the present invention has the same structure as the conventional split-type coagulation tank shown in FIG. 2 except that the fixed center well and the rotary center column have different sealing structures.
(A) and (b) correspond to an enlarged view of part III in FIG.

1 (a) and 1 (b), the rubber plate 24 on the upper end side of the rotary center column 22 is fixed by a pressing plate 25 and bolts 26, 26 in the same manner as in the conventional apparatus shown in FIG. 22.

In the sealing structure shown in FIG. 1A, a rubber plate 27 is also attached to the lower end of the fixed center well 21 with a holding plate 28 and bolts 26. This rubber plate 27 is wound around the outer periphery of the lower end of the fixed center well 21, one end of which is fixed to the fixed center well 21 with a holding plate 28 and bolts 26, and the other end is a free piece 27 A.
It has been. And the lower rotary center column 2
The free piece 24A of the rubber plate 24 attached to the elastic plate 2 elastically and water-tightly slides on the outer peripheral surface of the free piece 27A of the rubber plate 27, so that the fixed center well 21 and the rotary center column 22 The gap between them is sealed.

In the sealing structure shown in FIG. 1B, a rubber plate 30 is attached to the lower surface of a flange 29 provided at the lower end of the fixed center well 21 with a holding plate 31 and bolts 26. The rubber plate 30 extends outward from the outer periphery of the flange 29 and is elastically deformable in the vertical direction. The deformable outer peripheral portion 30A of the rubber plate 30 is attached to the lower rotary center column 22. The gap between the fixed center well 21 and the rotary center column 22 is sealed by elastically and watertightly slidingly contacting the free piece 24A of the rubber plate 24 attached to the rubber plate 24.

As described above, in the sealing structure including the rubber plates 24 and 27 or 30 attached to each of the fixed center well 21 and the rotary center column 22, the thickness of the rubber plate 24 is about 5 to 10 mm. Is preferred.
The thickness of the rubber plate 27 or 30 is preferably smaller than the thickness of the rubber plate 24 by about 1 to 3 mm and about 3 to 7 mm.

That is, the two rubber plates are worn by sliding contact with each other.
By making the thickness of the rubber plate 30 thinner than that of the other rubber plate 24, the sliding contact portions of the thinner rubber plates 27 and 30 disappear due to abrasion, and thereafter, as shown in FIG. 21 and comes into sliding contact. After that, the sliding contact portion of the rubber plate 24 with the fixed center well 21 is worn, so that the rubber plate 24 eventually disappears and the sealing effect cannot be obtained. In this case, the rubber plate 24 and the rubber plates 27 and 30 are replaced with new rubber plates, or
The rubber plate is pulled out from under the holding plate to form a sliding portion.
In the present invention, by adjusting the thickness and length of the rubber plate, the duration of the sealing effect by the rubber plate is 3 to 3 times as compared with the case where the rubber plate is attached only to the rotary center column side as shown in FIG. It can be extended as much as five times.

[0034]

As described above in detail, according to the sedimentation tank of the present invention, a fixed center well and a rotary center column are provided, and the liquid to be treated is passed through the fixed center well and the rotary center column. In the sedimentation tank introduced into the tank from the distributor provided at the lower part of the rotary center column, wear of the elastic sealing member for sealing between the lower end of the fixed center well and the upper end of the rotary center column is prevented. be able to. Therefore, the operation can be stably continued for a long time without replacing the elastic seal member and without causing deterioration of the treated water.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a seal portion between a fixed center well and a rotary center column, showing an embodiment of a sedimentation tank of the present invention.

FIG. 2 is a longitudinal sectional view showing a conventional split type sedimentation tank.

FIG. 3 is an enlarged view of a part III in FIG. 2;

FIG. 4 is a longitudinal sectional view showing a conventional coagulation and sedimentation apparatus.

FIG. 5 is a plan view of a sedimentation tank part of FIG.

FIG. 6 is an enlarged view of a cross section taken along line VI-VI of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sedimentation tank 2 Rake 3 Distributor 4 Center column 4A Center well 5 Motor 5A shaft 6 Overflow part 7 Outflow part 11 Coagulation tank 12 Inflow trough 13 Stirrer 14 Baffle plate 20 Sedimentation tank 21 Fixed center well 22 Rotary center column 23 Inflow trough 24, 27, 30 Rubber plate 25, 28, 31 Holding plate 26 Bolt 29 Flange

Claims (2)

[Claims] 1. A cylindrical center well is fixed to a central portion, and a cylindrical center column is installed below the center well coaxially with the center well, and the center column is rotatable around its axis. In a sedimentation tank in which the lower end of the center well and the upper end of the center column are sealed by an elastic seal member, the elastic seal member is provided in both the center well and the center column. A sedimentation tank wherein the elastic seal members are brought into sliding contact with each other. 2. The method according to claim 1, wherein a distributor extends radially from a lower portion of the center column, and a mud collecting member rotatable with the distributor is provided below the distributor. Characterized sedimentation tank.