JP6662251B2 - Settling tank - Google Patents

Description

  The present invention relates to a sedimentation tank for separating and separating sludge, and in particular, includes a fixed center well and a rotary center column, and rotates a liquid to be treated through the fixed center well and the rotary center column. The present invention relates to a sedimentation tank which is introduced into a tank from a distributor provided at a lower part of a formula center column.

  Conventionally, in activated sludge treatment equipment and coagulation sedimentation treatment equipment, sedimentation using a solid-liquid separation tank (sedimentation tank) as a means for separating a sludge mixture (coagulation treatment liquid) into treated water and sludge is generally performed. Has been adopted. In this sedimentation separation, a sludge zone (sludge blanket layer) is formed in the sedimentation tank, and an introduction pipe ( Feed sludge), the sludge mixed solution is introduced from the lower part of the sludge zone and passed through the sludge zone, whereby a sludge blanket filtration method for filtering and separating turbidity and fine SS in the sludge mixed solution is adopted. I have.

  In a center well type sedimentation tank, the inner diameter of the center well needs to be increased to increase the flow rate of treated water, and the number of troughs needs to be increased.The center well occupies a considerable area of the water surface Was a problem.

As a countermeasure, it is conceivable to reduce the diameter of the center well and the center column near the water surface. The flow rate at the outlet far from the junction is larger than the flow rate at the outlet near the outlet. There was concern that it would worsen.
It is also known that the diameter of the plurality of outlets of the distributor is reduced as the distance from the center column junction to the tank wall increases, but this problem is still a concern. In some cases, a slit-shaped outlet extending from the vicinity of the center column junction to the tank wall is provided instead of the plurality of outlets, and the width decreases as the distance from the center column junction toward the tank wall increases. This problem was also a concern.

  In order to solve this problem, the diameter of the center column is made larger than that of the center well, the flow rate in the center column is reduced, and the space between the center column and the center well is sealed with an elastic seal portion having a rubber plate. It is possible. (Patent Document 1 describes a sedimentation tank in which a center well and a center column are separated from each other and an elastic seal portion is provided between the center well and the center column.) However, in this case, the coagulated water is used. When air flows into the center well, air entrained from the atmosphere leaks from the gap between the elastic seal portion and the center well or the center column, and rises as bubbles in the sedimentation tank. In some cases, the sludge blanket was rolled up and disturbed, resulting in deterioration of treated water quality.

JP-A-2002-126407

  An object of the present invention is to provide a sedimentation tank capable of increasing the flow rate of treated water and preventing the quality of treated water from being deteriorated by gas leaking into the tank from a gap between the center well and the center column. .

  In the sedimentation tank of the present invention, a cylindrical center well is fixed at a central portion, and a cylindrical center column rotatable around an axis is installed below the center well and coaxially with the center well. In a sedimentation tank in which the lower end of the well and the upper end of the center column are sealed by an elastic seal portion, the center column has a larger diameter than the center well, and the elastic seal is provided on the outer peripheral side of the center well. A leak gas collecting member surrounding the portion, and an exhaust pipe for discharging gas in the leak gas collecting member above the water surface of the sedimentation tank.

  According to one aspect of the present invention, a canopy portion that is continuous with the lower periphery of the center well and that expands in the radial direction has a hanging wall that hangs down from the entire periphery of the outer periphery of the canopy portion. The tubing is connected.

  In the present invention, since the diameter of the center column is larger than that of the center well, the flow rate in the center column can be reduced. In addition, when there is a distributor, it is possible to prevent the upward flow velocity near the inner wall of the sedimentation tank from locally increasing after discharge from the distributor.

  Further, in the present invention, a leaked gas collecting member for collecting gas leaking from the elastic seal portion sealing the center well and the center column, and a discharge pipe for discharging the collected gas onto the water surface are provided. I have. Therefore, even if gas leaks from the gap between the elastic seal portion and the center well or the center column, bubbles do not rise in the blanket and solid-liquid separation is not hindered.

It is a longitudinal section of a sedimentation tank concerning an embodiment. FIG. 2 is an enlarged view and a perspective view of the vicinity of an elastic seal portion of the settling tank of FIG. It is an enlarged view near the elastic seal part of the sedimentation tank which concerns on another embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. 1 and 2 show a coagulation settling apparatus having a settling tank according to an embodiment.

  In this coagulation sedimentation apparatus, the bottom surface 1A except for the central part of the sedimentation tank (thickener) 1 has a conical shape having a downward slope toward the center of the bottom part. 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, and a side face of the distributor 3 formed of the tubular body (the side of the distributor 3). A raw water outlet 3A is provided on the downstream side in the direction of rotation. Although not shown, a rectifying plate may be provided above the distributor 3.

  The center column 4 is connected to a shaft 9A of a motor 9, and is configured to rotate slowly and integrally with the rake 2 and the distributor 3 by the motor 9.

  Above the center column 4, a center well 5 is fixedly installed coaxially with the center column 4. The center well 5 and the center column 4 are separate bodies. The center column 4 has a larger diameter than the center well 5 and is configured such that the descending flow rate is smaller than that in the center well 5. The inner diameter of the center column 4 is preferably about 1.4 to 2 times, especially about 1.5 to 1.8 times the inner diameter of the center well 5.

  As shown in an enlarged manner in FIG. 2A, an inward flange-shaped flange portion 4 a is provided at the upper end of the center column 4. A ring-shaped rubber plate 6 constituting an elastic seal portion is disposed on the flange portion 4a, and is fixed to the flange portion 4a by fixing means such as bolts.

  The diameter of the inner hole 6 a of the rubber plate 6 is slightly smaller than the outer diameter of the center well 5. The conditions are slightly different depending on the material and thickness of the rubber plate 6, the outer diameter of the center well, and the width in the center direction of the small diameter portion not fixed to the flange portion 4 a of the rubber plate 9. By designing the outer diameter of the center well 5 to be smaller than the outer diameter of the center well 5 by about 30 to 100 mm, the outer wall surface of the center well 5 slidably contacts the upper surface of the peripheral portion of the inner hole 6a of the rubber plate 6. By pushing the center well 5 below the rubber plate 6, the small diameter portion of the rubber plate 6 not fixed to the center column 4 bends, so that the center well 5 and the center column 4 are sealed.

  As shown in FIG. 2B in an enlarged manner, a leaked gas collecting member 7 is provided so as to surround the lower end of the center well 5 and the outer periphery of the rubber plate 6. The leaked gas collecting member 7 has a disc-shaped canopy part 7a and a hanging wall 7b hanging from an outer peripheral edge of the canopy part 7a.

  A circular opening is provided at the center of the canopy 7a, and the center well 5 is fitted into the circular opening, and is fixed by welding or the like over the entire circumference. The canopy part 7a is expanded in the radial direction from the center well 5. The hanging wall 7b is of a short cylindrical shape that goes around the entire circumference of the canopy 7a.

  A plurality of (two in this embodiment, but one or three or more) exhaust ports 7c are provided in the canopy part 7a, and an exhaust pipe 8 is erected from the exhaust ports 7c. ing. The exhaust pipe 8 is fixed to the canopy 7a by welding or the like. The exhaust pipe 8 extends upward, and its upper end is open to the atmosphere above the water surface of the sedimentation tank 1.

  The coagulation tank 11 is provided with a stirring device 12 and a baffle plate 13. The coagulation treatment liquid from the coagulation tank 11 is supplied into the center column 4 from the center well 5 through the inflow trough 14, and the raw water outlet 3A on the side surface of the distributor 3 is located on the downstream side in the rotation direction of the distributor 3 and the rake 2. Flows out into the sludge blanket S. When the distributor 3 and the rake 2 are simultaneously rotated slowly by the motor 9, the sludge in the sedimentation tank 1 is slowly stirred, and the generation and growth of flocs are promoted, and the stable sludge blanket S is generated. . The sedimented flocs are collected by the rake 2 in the central concave portion 1B and discharged out of the tank from a drain pipe (not shown), and the clarified water overflows the overflow 16 and is taken out from the outlet 17 as treated water.

  In this embodiment, since the diameter of the center column 4 is larger than that of the center well 5, the flow velocity in the center column 4 can be reduced, and the upward flow velocity in the vicinity of the inner wall of the settling tank after discharging from the distributor 3 is locally increased. Can be prevented from becoming large. Further, since the leaked gas collecting member 7 is provided so as to surround the upper side and the side circumference of the elastic seal portion (rubber plate 6) between the center well 5 and the center column 4, for example, the rubber plate 6 and the center well 5 are provided. Even if the gas leaks from the contact portion with the air, the gas is collected by the leaked gas collecting member 7 and discharged to the atmosphere via the discharge pipe 8. Therefore, this gas does not form bubbles and rise in the precipitation tank 1. As a result, bubbles are prevented from rolling up and disturbing the sludge blanket in the tank, and the quality of the treated water is improved.

  In FIGS. 1 and 2, the rubber plate 6 is attached to the flange 4a of the center column 4. As shown in FIG. 3, a flange 5a is provided at the lower end of the center well 5, and the rubber 5 is attached to the lower end of the flange 5a. The plate 6 may be fixed by fixing means, and the inner wall surface of the center column 4 may be slidably contacted with the rubber plate 6. By pushing the center column 4 above the rubber plate 6, the large-diameter portion not fixed to the center well 5 of the rubber plate 6 bends, whereby the center well 5 and the center column 4 are sealed. In the case of FIG. 3, the outer diameter of the rubber plate 6 (the outer diameter when the rubber plate 6 is not deformed) is designed to be slightly larger than the inner diameter of the center column 4 (for example, about 30 to 100 mm larger).

  Also in FIG. 3, a leaked gas collecting member 7 is provided so as to surround the elastic seal portion (rubber plate 6). Therefore, even if gas leaks from the contact portion between the rubber plate 6 and the upper end surface of the center column 4, the gas enters the leaked gas collecting member 7 and is discharged to the atmosphere via the exhaust pipe 8. As a result, bubbles are prevented from rolling up and disturbing the sludge blanket in the tank, and the quality of the treated water is improved. 3 are the same as those in FIG. 2, and the same reference numerals indicate the same parts. The rubber plate shown in FIG. 2 and the rubber plate shown in FIG. 3 may be used in combination.

  The above embodiment is an example of the present invention, and the present invention may have a configuration other than that illustrated.

DESCRIPTION OF SYMBOLS 1 Sedimentation tank 2 Rake 4 Center column 5 Center well 6 Rubber plate 7 Leaked gas collecting member 7a Canopy part 7b Hanging wall 7c Opening 8 Exhaust pipe

Claims (3)

A cylindrical center well is fixed at the center, and a cylindrical center column rotatable around the axis is installed coaxially with the center well below the center well,
In a sedimentation tank in which the space between the lower end of the center well and the upper end of the center column is sealed by an elastic seal portion,
The center column is larger in diameter than the center well,
A leaked gas collecting member surrounding the elastic seal portion on the outer peripheral side of the center well;
An exhaust pipe for discharging gas in the leaked gas collecting member above the water surface of the sedimentation tank. In claim 1, the leaked gas collecting member is
A canopy part which is continuous with the lower periphery of the center well and which is expanded in the radial direction,
Having a hanging wall hanging down from the entire periphery of the outer peripheral edge of the canopy portion,
A sedimentation tank, wherein the exhaust pipe is connected to the canopy.   The distributor according to claim 1 or 2, wherein a distributor extends radially from a lower portion of the center column, and a mud collecting member rotatable together with the distributor is provided below the distributor. Settling tank.

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