Pit sludge discharge device for sedimentation basin

Abstract

To provide a pit sludge discharge device for a sedimentation basin that can prevent a water passage from being formed in a sludge discharge pit and improve sludge discharge efficiency.SOLUTION: A pit sludge discharge device for a sedimentation basin includes: a punching plate 36 installed to a sludge discharge pit 22 that is provided in a basin bottom of a sedimentation basin; a loop-like sludge discharge promoting pipe 38 provided under the punching plate 36; and a plurality of injection nozzles 42 provided in the sludge discharge promoting pipe 38 so that nozzle ports 40 are oriented downward.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a pit drainage device for a sedimentation tank provided in a water purification facility. [Background technology]

[0002] In a settling tank installed in a water purification facility, a sludge discharge pit of a specified depth is provided on one side or in the center of the bottom of the tank in order to discharge sludge that has settled at the bottom of the tank. For example, Patent Document 1 discloses a configuration in which the entire bottom of the settling tank is divided lengthwise and widthwise to form a lattice-shaped sludge discharge pit, the suction ports of the sludge discharge pipes installed in each sludge discharge pit are provided facing the bottom of each pit, and each sludge discharge pipe is connected to a sludge collecting pipe via a control valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3947310 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the sludge accumulated in the sludge pit, a waterway may form near the sludge discharge pipe. When this waterway is formed, a large amount of water flows out of the waterway together with the sludge, which causes the sludge to be sent to the sludge tank to be diluted, lowering the concentration of the sludge.

[0005] This requires the capacity of the sludge basin to be large, which makes it costly to thicken the sludge. Furthermore, once a waterway is formed, the next time sludge is discharged, only the sludge that has collected in that waterway is discharged, which reduces the volumetric efficiency of the sludge discharge pit.

[0006] In some cases, the residual sludge in the sludge discharge pit is broken down and discharged using water jets through sludge discharge pipes, etc. However, even when water jets are used, it is necessary to install sludge discharge pipes over the entire sludge discharge pit, which causes a problem of reduced sludge concentration.

[0007] The present invention has been made in consideration of the above-mentioned points, and aims to provide a pit drainage device for a sedimentation tank that can prevent the formation of waterways in the drainage pit and improve the efficiency of sludge drainage. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention is characterized by comprising a porous plate installed in a sludge discharge pit provided at the bottom of a sedimentation tank, a loop-shaped pipe provided below the porous plate, and a plurality of injection nozzles provided on the pipe, the nozzle openings of which are directed downward. Effect of the Invention

[0009] According to the present invention, by disposing a porous plate in the sludge discharge pit, a flow resistance that acts as a resistance to the formation of a waterway can be generated, and the generation of a waterway can be prevented. Also, according to the present invention, a loop-shaped pipe disposed under the porous plate is provided with a plurality of jet nozzles whose nozzle openings are oriented downward. A swirling flow toward the sludge discharge pipe can be generated by the jet water jetted from the nozzle openings of the jet nozzles. As a result, in the present invention, the accumulation of sludge in the sludge discharge pit under the porous plate can be broken down, the remaining amount of accumulated sludge under the porous plate can be eliminated, and the amount of accumulated sludge remaining in the sludge discharge pit can be reduced. Furthermore, in the present invention, the amount of jet water jetted from the nozzle openings of the jet nozzles is small when viewed from the entire sludge discharge pit, so that a decrease in the concentration of the discharged sludge can be prevented. [Brief description of the drawings]

[0010] [Figure 1] 1 is a plan structural view of a water purification facility to which a pit mud drainage device according to an embodiment of the present invention is applied. [Diagram 2]FIG. 2 is a longitudinal sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a longitudinal sectional view taken along line III-III in FIG. [Figure 4] FIG. 2 is a partially transparent perspective view of a pit mud drainage device according to an embodiment of the present invention. [Diagram 5] 5 is a partially see-through side view seen from the direction of arrow V in FIG. 4. [Figure 6] FIG. 2 is a partially transparent perspective view of a pit mud drainage device according to another embodiment of the present invention. [Figure 7] 7 is a partially see-through side view seen from the direction of arrow VII in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

[0012] 1 and 2, a water purification facility 10 to which a pit sludge removal device according to an embodiment of the present invention is applied includes a grit basin (not shown), a receiving well (also called a raw water tank depending on the facility), a rapid mixing tank (mixing tank), a flocculation basin 12, a sedimentation basin 14, a filtration area, etc. The sedimentation basin 14 is disposed downstream of the flocculation basin 12. The flocculation basin 12 is a facility in which small flocs produced in the rapid mixing basin (not shown) are slowly stirred by flocculators 16a, 16b, and 16c to turn them into large flocs that are easy to settle.

[0013] The settling tank 14 has a side wall 18 and a plurality of partition walls that divide the bottom of the side wall 18 (settling tank 14) to form a plurality of areas. As shown in FIG. 1 and FIG. 2, in this embodiment, the tank is divided into a plurality of areas by two partition walls 20, 20 extending in a direction perpendicular to the water flow direction. In this embodiment, two partition walls 20 are installed, but the number of partition walls 20 may be set appropriately. In addition, when an inclined plate settling device is installed in the settling tank 14, it is preferable to position the partition wall 20 below the upstream end of the inclined plate settling device. This can prevent short-circuiting flow that flows below the inclined plate settling device and does not flow into the inclined plate settling device, thereby improving the settling efficiency. Furthermore, the settling tank 14 of this embodiment does not have a scraper that scrapes sludge with a movable mechanical part, and the sludge is deposited in a sludge discharge pit 22 described later at the bottom of the tank, and the sludge is accumulated by gravity flow. In order to regulate the flow of water that flows from the flocculation basin 12 into the settling basin 14, a flow regulation wall 21 (see Figs. 1 and 2) having a plurality of outflow holes is provided.

[0014] A number of pit drainage devices 24 are provided at the bottom of the settling basin 14, arranged vertically and horizontally in a grid pattern. Since each of the pit drainage devices 24 has the same structure, only one of them will be described in detail and the others will be omitted.

[0015] 4 and 5, the pit mud drainage device 24 has a generally inverted square cone shape formed by the four inclined surfaces 26a to 26d. The pit mud drainage device 24 is also configured to include an inclined surface portion 28 having the four inclined surfaces 26a to 26d, a square opening 30 formed by the upper ends of the four inclined surfaces 26a to 26d, and a bottom surface portion 32 (see FIG. 3) that closes the lower ends of the four inclined surfaces 26a to 26d to form a bottom surface.

[0016] A sludge discharge pit (sludge discharge chamber) 22 is provided on the inside of the inclined surface portion 28, and is formed so that its cross-sectional area increases from the bottom surface portion 32 toward the opening 30. A punched plate (perforated plate) 36, which is substantially square in plan view and has a plurality of through holes 34 formed therein, is attached to the upper portion of the sludge discharge pit 22. In the punched plate 36, the inner diameter and installation intervals of the through holes 34 are appropriately selected according to the properties of the sludge in the settling basin 14.

[0017] 4 and 5, a sludge discharge promotion pipe (piping) 38 having a loop shape in plan view is joined to the lower surface of the punching plate 36. The sludge discharge promotion pipe 38 is provided with a plurality of injection nozzles 42 with nozzle openings 40 facing downward. Four of the injection nozzles 42 are arranged at intervals of 90 degrees corresponding to the four inclined surfaces 26a to 26d constituting the inclined surface portion 28. As shown in FIG. 5, the nozzle openings 40 of the injection nozzles 42 are provided so as to be capable of jetting toward the respective inclined surfaces 26a (26b to 26d) constituting the inclined surface portion 28.

[0018] The sludge discharge promoting pipe 38 may be directly joined to the lower surface of the punching plate 36, or may be attached to the underside of the punching plate 36 via a mounting bracket (not shown).

[0019] Specifically, in Fig. 5, the intersection angle θ between the imaginary line L passing through the nozzle port 40 of the injection nozzle 42 and the inner inclined surface 26d is set to a predetermined angle in a side view. Also, the nozzle port 40 of each injection nozzle 42 is arranged to be inclined to one side of either the clockwise direction or the counterclockwise direction in a plan view. By arranging the nozzles to be inclined to one side of the clockwise direction or the counterclockwise direction, a swirling flow that swirls toward the sludge discharge pipe 44 described later can be generated. In other words, the intersection angle θ, injection direction, installation number, etc. of the injection nozzles 42 are set so as to generate a swirling flow that swirls toward the sludge discharge pipe 44 described later.

[0020] A sludge discharge pipe 44 is disposed below the punching plate 36 and above the upper surface of the bottom surface portion 32. This sludge discharge pipe 44 has a trumpet-shaped portion 46 that faces the bottom surface portion 32 and expands downward, a flange portion 48 that is located above the trumpet-shaped portion 46 and expands outward, a bent portion 50 that bends from above the flange portion 48 so as to be substantially perpendicular, and a pipe body 52 that extends from the bent portion 50 through one of the inclined surfaces 26b of the inclined surface portion 28 to the outside of the sludge discharge pit 22.

[0021] This pipe 52 is designed so that sludge accumulated in the sludge pit 22 is transported to a sludge pond (not shown) by a suction pump (not shown) or by gravity flow due to the difference in elevation.

[0022] The water purification facility 10 to which the pit mud drainage device 24 according to this embodiment is applied is basically configured as described above. Next, its function and effect will be described.

[0023] In this embodiment, a punching plate 36 is installed in the sludge discharge pit 22, and a loop-shaped sludge discharge promotion pipe 38 is provided below this punching plate 36, and four downward-facing injection nozzles 42 are arranged in this sludge discharge promotion pipe 38.

[0024] In this embodiment, by arranging a punching plate 36 inside the sludge pit 22, a flow resistance that acts as a resistance to the formation of a waterway can be generated, thereby making it possible to prevent the formation of a waterway.

[0025] In this embodiment, a swirling flow toward the sludge discharge pipe 44 can be generated by the water jetted from the nozzle ports 40 of the multiple jet nozzles 42 arranged below the punching plate 36. As a result, in this embodiment, the accumulation of sludge in the sludge discharge pit 22 below the punching plate 36 can be broken up, the remaining amount of accumulated sludge below the punching plate 36 can be eliminated, and the amount of accumulated sludge remaining in the sludge discharge pit 22 can be reduced.

[0026] Furthermore, in this embodiment, only four injection nozzles 42 are installed corresponding to the number of inclined surfaces 26a to 26d of the inclined surface portion 28, and the amount of water injected from the nozzle port 40 is small when viewed from the entire sludge pit 22, so that a decrease in the sludge concentration can be prevented.

[0027] As a result, in this embodiment, it is possible to obtain a pit drainage device 24 for the settling basin 14 that can prevent the formation of waterways in the drainage pit 22 and improve the efficiency of draining sludge.

[0028] Next, a pit mud drainage device 24a according to another embodiment of the present invention will be described. The same components as those in the embodiment shown in Figures 1 to 5 are given the same reference numerals and detailed description thereof will be omitted. Figure 6 is a perspective view of the pit mud drainage device according to the other embodiment, and Figure 7 is a partially see-through side view seen from the direction of the arrow VII in Figure 6.

[0029] As shown in Figures 6 and 7, this other embodiment differs from the above embodiment in that the sludge pit 22 is configured with an outer inclined surface portion 60 having four inclined surfaces 26a to 26d, and an inner inclined surface portion 64 provided inside the outer inclined surface portion 60 and having four inclined surfaces 62a to 62d that slope from the upper side of the four inclined surfaces 26a to 26d of the outer inclined surface portion 60 toward the center.

[0030] A circular opening 66 having a circular shape in plan view is provided in the center of the inner inclined surface portion 64. A cylinder 68 that reaches the bottom surface portion 32 of the sludge pit 22 is connected to this circular opening 66. A pipe 70 that penetrates one of the inclined surfaces 26b of the outer inclined surface portion 60 and extends to the outside of the sludge pit 22 is connected to the side of the cylinder 68. The pipe 70 is adapted to send the sludge accumulated in the sludge pit 22 to a sludge tank (not shown) by a suction pump (not shown) or by gravity flow due to a difference in elevation.

[0031] In another embodiment, an inner inclined surface portion 64 which slopes further toward the center of the sludge pit 22 is arranged inside the outer inclined surface portion 60, thereby further improving the suction effect of the sludge accumulated in the sludge pit 22. [Explanation of symbols]

[0032] 10. Water Purification Plant 14 Sedimentation tank 22 Sludge disposal pit 24, 24a Pit sludge drainage device 26a~26d Slope 34 Through hole 36 Punching plate (perforated plate) 38 Sludge removal promotion pipe 40 Nozzle mouth 42 Injection nozzle 60 Outer slope section 62a~62d Slope 64 Inner slope section 66 Circular opening

Claims

1. A perforated plate is installed in a sludge discharge pit provided at the bottom of the sedimentation tank; A loop-shaped pipe provided under the porous plate; A plurality of injection nozzles are provided in the pipe, the nozzle nozzles being oriented downward; A pit drainage device for a sedimentation tank, comprising:

2. In the pit drainage device for a sedimentation pond according to claim 1, A pit sludge drainage device for a sedimentation tank, characterized in that the sludge drainage pit has an outer inclined surface portion having a plurality of inclined surfaces, and an inner inclined surface portion provided inside the outer inclined surface portion and sloping from the outer inclined surface portion toward the center.

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