JP6617635B2 - Sedimentation tank - Google Patents

Description

  The present invention relates to a sedimentation tank for settling and separating sludge, and in particular, includes a fixed center well and a rotating center column, and the liquid to be treated is rotated through the fixed center well and the rotating center column. The present invention relates to a precipitation tank that is introduced into a tank from a distributor provided at the bottom of the center column.

  Conventionally, in activated sludge treatment equipment, coagulation sedimentation treatment equipment, etc., sedimentation separation using a solid-liquid separation tank (precipitation tank) is generally used as a means for separating a sludge mixed liquid (coagulation treatment liquid) into treated water and sludge. It has been adopted. In this sedimentation separation, a sludge zone (sludge blanket layer) is formed in the settling tank in order to efficiently remove turbidity and fine SS in the sludge mixture and obtain good treated water. The sludge blanket filtration method is adopted to filter and separate turbidity and fine SS in the sludge mixture by passing the sludge mixture through the sludge zone through the feed well) Yes.

  In the center well type sedimentation tank, in order to increase the flow rate of treated water, it is necessary to increase the inner diameter of the center well, and it is also necessary to increase the number of troughs installed. Was a problem.

  As measures against this, it is conceivable to reduce the diameter of the center well and the center column. However, since the flow velocity in the center well and the center column increases, the junction of the center column and the plurality of outlets provided in the distributor. The flow rate at the outlet far from the joint is larger than the flow rate at the nearby outlet, and the upward flow velocity in the vicinity of the inner wall of the settling tank increases locally after discharging from the distributor. There was concern to make it worse.

  Patent Document 1 describes a sedimentation tank in which an upper center well and a lower center column are separated and an elastic seal portion is provided between the center well and the center column.

JP 2002-126407 A

  An object of the present invention is to provide a sedimentation tank in which the flow rate of treated water can be increased, the upward flow rate is prevented from locally increasing, and the quality of treated water is prevented from deteriorating.

  In the sedimentation tank of the present invention, a cylindrical center well is fixed at the center, and a cylindrical center column that is coaxial with the center well and is rotatable about an axis is installed below the center well. In the precipitation tank in which the space between the lower part of the well and the upper part of the center column is sealed by an elastic seal part, the center column has a larger diameter than the center well.

  In one embodiment of the present invention, the inner diameter of the center column is 1.4 to 2 times the inner diameter of the center well.

  In one aspect of the present invention, a tapered portion having a smaller diameter toward the upper side is provided at the connecting portion between the center well and the center column.

  In one aspect of the present invention, a cover is provided that surrounds the upper side and the outer periphery of the connecting portion between the center column and the center well.

  In the present invention, since the center column has a larger diameter than the center well, the flow velocity in the center column can be reduced, and the upward flow velocity in the vicinity of the inner wall of the precipitation tank can be locally increased after discharging from the distributor. Can be prevented.

  In this invention, when it is set as the structure which provided the taper part which diameter-reduces the upper part in the connection part of a center well and a center column, gas does not stay in this connection part. Therefore, gas does not leak from the elastic seal portion, bubbles do not rise in the blanket, and solid-liquid separation is not hindered.

  Since the cover surrounding the upper and outer periphery of the connecting portion between the center column and the center well is provided, even if the gas leaks from the elastic seal portion, the gas stops in the cover. The bubbles do not rise and the solid-liquid separation is not hindered.

(A) is a longitudinal cross-sectional view of the settling tank which concerns on embodiment, (b) is an enlarged view and perspective view of the elastic seal part vicinity of the settling tank of (a). It is an enlarged view near the elastic seal part of the sedimentation tank concerning another embodiment. It is an enlarged view near the elastic seal part of the sedimentation tank concerning another embodiment. It is an enlarged view near the elastic seal part of the sedimentation tank concerning another embodiment. It is an enlarged view near the elastic seal part of the sedimentation tank concerning another embodiment. It is an enlarged view near the elastic seal part of the sedimentation tank concerning another embodiment. It is an enlarged view near the elastic seal part of the sedimentation tank concerning another embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 shows a coagulation sedimentation apparatus having a sedimentation tank according to an embodiment.

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

  The distributor 3 is formed of a tubular body extending radially from the lower end of the center column 4 extending in the vertical direction at the center of the sedimentation tank 1, and the side surface of the distributor 3 (distributor 3 of the distributor 3). A raw water outlet 3A is provided on the side of the downstream side in the direction of rotation. In addition, although illustration is abbreviate | omitted, a baffle plate may be installed above this distributor 3. FIG.

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

  A center well 5 is fixedly installed above the center column 4 coaxially with the center column 4. The center well 5 and the center column 4 are separated. 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, particularly about 1.5 to 1.8 times the inner diameter of the center well 5.

  As shown in an enlarged view in FIG. 1B, an outwardly flanged 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 a fixing means such as a bolt.

  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. Although the conditions are slightly different depending on the material of the rubber plate 6, the thickness, the outer diameter of the center well 5, 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, the diameter of the inner hole 6 a of the rubber plate 6 Is designed to be 30 to 100 mm smaller than the outer diameter of the center well 5, so that the outer wall surface of the center well 5 is slidably in contact with the upper surface of the peripheral edge of the inner hole 6 a of the rubber plate 6. By pushing the center well 5 downward from the rubber plate 6, the small diameter portion that is not fixed to the flange 4 a of the rubber plate 6 is bent, whereby the center well 5 and the center column 4 are sealed.

  The aggregating 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 distributor 3 and the rake 2 in the rotation direction downstream side from the raw water outlet 3 A on the side surface of the distributor 3. To the sludge blanket S. Then, the distributor 3 and the rake 2 are slowly rotated simultaneously by the motor 5 so that the sludge in the settling tank 1 is slowly stirred to promote the generation and growth of flocs and at the same time, the stable sludge blanket S is generated. . The settled flocs are collected in the central recess 1B by the rake 2 and discharged out of the tank through a drain pipe (not shown), and the clarified water overflows the overflow portion 16 and is taken out from the outflow portion 17 as treated water.

  In this embodiment, since the center column 4 has a larger diameter than 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 precipitation tank after the discharge from the distributor 3 is locally Can be prevented.

  In FIG. 1, the rubber plate 6 is attached to the flange portion 4a of the center column 4. However, as shown in FIG. 2, a flange portion 5a is provided at the lower end of the center well 5, and the rubber plate 6 is provided at the lower end of the flange portion 5a. May be fixed by a fixing means, and the inner wall surface of the center column 4 may be slidably brought into contact with the rubber plate 6. By pushing the center column 4 upward from the rubber plate 6, the outer peripheral side not fixed to the flange 5 a of the rubber plate 6 bends, whereby the center well 5 and the center column 4 are sealed. In the case of FIG. 2, 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 (for example, about 30 to 100 mm larger) than the inner diameter of the center column 4. In addition, you may use together the rubber plate of FIG.1 (b), and the rubber plate of FIG.

  In the present invention, the connecting portion between the center well 5 and the center column 4 may have a tapered shape with a smaller diameter toward the top. An example is shown in FIGS.

  In FIG. 3, the taper part 5b is provided in the lower end of the center well 5 in FIG.1 (b). The tapered portion 5b has a diameter that increases toward the bottom, and the outer peripheral edge is slidably in contact with the upper surface of the outer peripheral edge of the rubber plate 6. The rubber plate 6 has a bent portion that is not fixed to the flange 4 a, and the taper portion 5 b of the center well 5 pushes the bent portion of the rubber plate 6, so that the rubber plate 6 is bent and seals the center well 5 and the center column 4. . Other configurations are the same as those in FIG. 1B, and the same reference numerals denote the same parts.

  The taper angle θ of the taper portion 5b is preferably about 20 to 80 °, particularly about 30 to 60 °. The same applies to the embodiments described later.

  In FIG. 4, the taper portion 4 b is provided at the upper end of the center column 4 in FIG. 2. The taper portion 4 b is reduced in diameter toward the upper side, and the inner peripheral edge is slidably in contact with the lower surface near the inner peripheral edge of the rubber plate 6. By pushing the taper portion 4b of the center column 4 into a bent portion of the rubber plate 6 that is not fixed to the flange 5a, the rubber plate 6 is bent and the center well 5 and the center column 4 are sealed. However, the tapered portion 4b is made to have a smaller diameter than the inner hole 6a of the rubber plate 6. If the tapered portion 4b has a larger diameter, it is unsuitable because water leakage resistance easily causes water leakage from the gap between the rubber plate 6 and the tapered portion 4b. Other configurations are the same as those in FIG. 2, and the same reference numerals denote the same parts.

  FIG. 5 is a view in which the flange 4 a is omitted in FIG. 3 and a rubber plate 7 is provided so as to surround the upper outer periphery of the center column 4. The rubber plate 7 makes one round of the center column 4, but may be provided in two or more rounds. The upper edge of the rubber plate 7 extends upward from the upper end of the center column 4. The upper edge of the rubber plate 7 is slidably in contact with the lower surface in the vicinity of the outer peripheral edge of the tapered portion 5b.

  A belt-like rubber plate 7 is wound around the upper end of the center column 4 and fixed. The center well 5 and the center column 4 are sealed by pushing the taper portion 5b of the center well 5 into the upper portion not fixed.

  In the form in which the rubber plate 7 is wound around the center well 5 or the center column 4 as shown in FIG. 5, a cover portion 8 surrounding the outer periphery and the upper side of the rubber plate 7 may be provided as shown in FIG.

  FIG. 6 shows an embodiment in which a cover portion 8 is provided instead of the flange portion 5b in the embodiment of FIG. The cover portion 8 has a flange portion 8a that expands radially from the lower end of the center well 5, and a hanging wall portion 8b that hangs down from the outer peripheral edge of the flange portion 8a. This hanging wall portion 8 b surrounds the outer periphery of the rubber plate 7 and extends downward from the rubber plate 7. The upper end surface of the rubber plate 7 is slidably in contact with the lower surface of the flange portion 8a. In FIG. 6, the center well 5 is pushed in and sealed. The play portion of the rubber plate 7 bends to the outside gradually due to the water pressure caused by the water flow. The other configurations in FIG. 6 are the same as those in FIG. 5, and the same reference numerals indicate the same parts.

  In FIG. 6, the rubber plate is fixed to the lower center column, but as shown in FIG. 7, the ring-shaped rubber plate 7 ′ is fixed to the inward flange portion 8c of the lower center well cover portion. Also good. The other configurations in FIG. 7 are the same as those in FIG. 6, and the same reference numerals indicate the same parts. Note that the rubber plate 7 in FIG. 6 and the rubber plate 7 ′ in FIG. 7 may be used in combination.

  When the agglomerated water flows into the center well 5, air is entrained and mixed from the atmosphere, leaks into the tank from the contact portion between the center well 5, the center column 4, and the rubber plate, and rises as bubbles to form a sludge blanket. There is a concern that the quality of the treated water may deteriorate.

  However, the provision of the tapered portions 4b and 5b as shown in FIGS. 3 to 5 prevents gas from accumulating at the connecting portion between the center well 5 and the center column 4, and the sliding surface between the rubber plates 6 and 7 Is prevented from leaking into the sedimentation tank 1. Therefore, the structures of FIGS. 3 to 5 are more preferable than those of FIGS. Further, according to the configuration of FIG. 5, even if gas leaks from the contact surface between the rubber plate 7 and the taper portion 5b of the center well 5, it accumulates in the taper portion 5b. According to the configuration of FIG. Even if gas leaks from the contact surface with the portion 8a, it accumulates in the cover portion 8. Therefore, the structure of FIGS. 5 and 6 is preferable to FIGS. 1B and 2-4. In addition, also in FIG. 3, the same effect can be acquired by making the taper part 5b larger diameter than the outer periphery of a rubber plate. Moreover, in FIGS. 3 and 4, by providing a hanging wall portion that hangs from the outer peripheral edge of the taper portion, it is possible to prevent air bubble leakage more reliably.

  In addition, the diameter of the plurality of raw water outlets 3A of the distributor may be reduced as the distance from the center column joint portion toward the tank wall increases, and instead of the plurality of raw water outlets 3A, 3A,. A slit-shaped raw water outlet extending from the vicinity of the joint portion toward the tank wall may be provided, and the slit width may be reduced as the distance from the axial center toward the tank wall increases. However, also in this case, the rubber plate of the present invention can prevent leakage from the connecting portion between the center well and the center column into the precipitation tank.

  The above embodiment is an example of the present invention, and the present invention may have a configuration other than that illustrated. For example, the sedimentation tank may have a polygonal shape such as a rectangular horizontal section, the bottom surface of the sedimentation tank may be a flat surface without a recess, a sludge discharge port is provided on at least a part of the inner wall of the precipitation tank, and the sludge blanket interface is the sludge discharge port. The sludge interface may be maintained within a certain range by discharging the sludge from the sludge outlet to the outside of the tank (for example, the sludge storage tank) when the height of the sludge is exceeded.

1 Settling tank 2 Rake 4 Center column 5 Center well 6, 7 Rubber plate 8 Cover

Claims (4)

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 and rotatable about an axis.
In the precipitation tank in which the space between the lower part of the center well and the upper part of the center column is sealed by an elastic seal part,
The sedimentation tank, wherein the center column has a larger diameter than the center well.   2. The sedimentation tank according to claim 1, wherein the inner diameter of the center column is 1.4 to 2 times the inner diameter of the center well.   3. The sedimentation tank according to claim 1, wherein a tapered portion having a smaller diameter toward the upper side is provided at a portion where the center well and the center column are connected.   The sedimentation tank according to any one of claims 1 to 3, further comprising a cover surrounding an upper side and an outer periphery of a connecting portion between the center column and the center well.

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