JP6715408B2 - Sand collecting device for sand basin - Google Patents

Description

The present invention relates to a sand collecting device that collects sediment deposited in a sand basin of a sewage treatment facility into a sand pit provided in the sand basin by a low pressure sand collecting method.

Patent Document 1 discloses a sand collecting device that collects sediment deposited in a sand basin in a sand pit provided in the sand basin by a low-pressure sand collecting method.
This sand collecting device discharges low pressure water of less than 3 kg/cm ^{2 to} the bottom surface of the sand basin from a large number of nozzles provided along the side wall of the sand basin while discharging the water in the sand basin (drainage state). It collects the accumulated sediment in the sand collecting pit.
The sediment collected in the sand collecting pit is pumped up with water by the sand pump installed in the sand collecting pit and transferred to the wastewater sedimentation basin.

Reduces the load on the water supply pump that supplies water to the nozzles along the side wall of the sand basin and the lift pump that pumps sediment from the sand collecting pit, enabling the use of small pumps for the water supply pump and sand pump Therefore, the bottom of the sand basin is divided into multiple areas, and a nozzle header is installed along the side wall of the sand basin with a large number of nozzles attached to the mother pipe in each area at specified intervals. Through the control of the sand collecting valve, each nozzle header is sequentially supplied for a predetermined time. The sand collecting valve is configured by directly connecting a flow rate adjusting valve that manually adjusts the flow rate and a switching valve that is an automatic valve that switches between water passage and water stoppage.

In order to reduce the manufacturing cost and the mounting cost of the nozzle header, equal-length nozzle headers having an equal number of nozzles are installed in regions of equal area.

A water supply pump with a discharge rate of 2 m ³ /min is used. When using a nozzle having a discharge rate of 0.15 m ³ /min, the maximum number of nozzles that can be attached to one nozzle header is 13. However, in order to discharge water evenly from all the nozzles attached to the nozzle header, the number of nozzles must be even, so the maximum number that can be attached is 12. On the other hand, in order to increase the efficiency of removing the sediment by discharging the sand to the bottom of the sand basin, it is appropriate that the nozzle headers have a nozzle mounting interval of 500 mm. Therefore, the maximum total length of the nozzle header is 6 m.

For example, when dividing the bottom of a sand basin having a total length of 18000 mm into a plurality of areas of equal area and installing a nozzle header of as long as 6 m or less in each area, as shown in FIG. Assuming that the width dimension of the surface 8b that slopes downward from the side walls Wa and Wb on both sides of the bottom surface of the sand collecting pit 7 provided at the center of the bottom of the sand basin 1 (hereinafter referred to as the sand collecting pit inclined surface) to be 1200 mm, Since the remaining lengths of the bottom surfaces of the upstream and downstream sides of the sand collecting pit inclined surface 8b are 8400 mm, respectively, conventionally, the entire bottom surface of the sand basin is located on both the upstream and downstream sides of the sand collecting pit inclined surface 8b. Each two regions were divided into eight regions B1 to B8 having the same area, and the length of one region was 4200 mm.

Therefore, the length of the nozzle header NH that can be installed in one area is 4200 mm, and the maximum number of installed nozzles in the nozzle header is eight. That is, conventionally, a sand basin having a total length of 18 m is divided into eight areas, and a nozzle header having a length of 4,200 mm and eight nozzles is installed in eight nozzles (NH1 to NH8).

Japanese Patent No. 3315489

As described above, in the settling basin of the prior art, the bottom surface is divided so that the entire area is equal on both sides of the sand collecting pit inclined surface 8b (that is, the portion excluding the sand collecting pit inclined surface 8b). Therefore, since the number of nozzle headers installed, and hence the number of sand collecting valves used, increases, there is a problem that equipment cost and maintenance cost increase. Moreover, since the number of nozzles in one nozzle header is small, there is a problem that the capacity of the water supply pump is not fully utilized.

The present invention has been made in view of the above circumstances, and in a sand collecting device that collects sediment deposited in a sand basin in a sand collecting pit by a low-pressure sand collecting method, it is possible to reduce equipment costs and maintenance costs. To aim.

In order to achieve the above object, the present invention has a sand collecting pit at the deepest part of the bottom of the sand basin, and at the bottom of the sand basin, a trough extending parallel to the water flow direction in the sand basin and leading to the sand collecting pit. In addition, it has an inclined surface of the sand collecting pit leading from the side wall of the sand collecting basin to the sand collecting pit in the direction orthogonal to the water flow direction in the sand basin, and the bottom of the sand basin is divided into multiple areas in the water flow direction in the sand basin. , A nozzle header having a plurality of nozzles in the area is installed along the side wall of the sand basin, by supplying low pressure water from the water supply pump to the nozzle header in the drainage state of the sand basin and jetting from the nozzle, flowing the deposited sediment in the trough, the collecting sand device sand basin for collecting the condensed sand pit through the trough, the one area, only setting the Atsumarisuna pit inclined surface, the nozzle headers Atsumarisuna pit inclined surface In addition to straddling, a part of the nozzle of the nozzle header is installed so as to face the inclined surface of the sand collecting pit .

According to the present invention, since the sand collecting pit inclined surface is provided in one of the regions, the number of regions in the sand basin having the same area is smaller than in the conventional case, and thus the total number of nozzle headers used can be reduced as compared with the conventional case. Therefore, manufacturing cost, installation cost, and maintenance cost can be reduced.

In the region where the sand collecting pit inclined surface is provided, a part of the nozzle of the nozzle header faces the sand collecting pit inclined surface, so that the sand collecting efficiency is improved. It is also possible to reduce the number of nozzles dedicated to the inclined surface of the sand collecting pit.

It is a longitudinal cross-sectional view of a rainwater treatment facility including a sand basin. FIG. 2 is a partially omitted plan view of a range X-X in FIG. 1. FIG. 3 is a sectional view taken along line Y1-Y1 of FIG. 2. It is the Y2-Y2 sectional view taken on the line of FIG. It is a top view which mainly shows the distribution of the area|region of a sand basin of FIG. 2, and the installation state of a nozzle header. FIG. 3 is a sectional view taken along line Y3-Y3 of FIG. 2 of FIG. 2. It is a front view which shows an example of a nozzle header. It is a water supply system diagram which concerns on embodiment. It is a flow chart explaining the procedure of sand collection valve control. It is a top view which shows the distribution of the area|region of the conventional sand basin, and the installation state of a nozzle header.

Next, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, 1 is a sewage treatment facility, which has a sand basin 2 and a pump well 3 formed between the side walls Wa and Wb (see FIG. 2). The sand basin 2 is connected to an inflow channel 4 where sewage such as rainwater and sewage is collected from a sewer pipe not shown. A dam device 5 for permitting or blocking the inflow of sewage from the inflow conduit 4 into the sand basin 2 is installed at the downstream end of the inflow basin 4, and the sand basin 2 is provided downstream of the dam device 5. The foreign matter trapping screen 6 is installed immediately in front of the upstream end of the.

The bottom surface 2a of the sand basin 2 is inclined so that the center becomes the deepest as described above for performing low pressure sand collection, and the sand collection pit 7 is formed in the center thereof, and the width of the bottom of the sand basin is formed. A main trough (corresponding to the trough referred to in the present invention) 8a that descends from the upstream and downstream ends of the sand basin to the sand collecting pit 7 is formed in the center of the direction, and from the lower ends of the side walls Wa and Wb. A surface 8b that slopes down to the sand collecting pit 7 (hereinafter referred to as a sand collecting pit slope) is formed, and at the bottom of the sand basin, from the vicinity of the side walls Wa and Wb to the main trough 8a, at a right angle to the water flow direction in the sand basin. A large number of small troughs 8c (see FIG. 2) extending parallel to the horizontal direction are formed.

In addition, the bottom surface of the sand basin 2 is divided into odd areas of approximately equal area by equally dividing the total length of the sand basin on both sides of the main trough 8a, and is divided into even areas in the entire sand basin. There is. In the example of FIGS. 2 and 5, the entire length is divided into three equal parts, and the entire sand basin is divided into six regions B1 to B6.
However, depending on the scale or width of the sand basin 2, the main trough 8a may be formed at a position closer to one side wall, in which case the area of the entire sand basin is odd. In any case, the central region (B1, B2) in the longitudinal direction of the sand basin exists in the center of the sand basin 2 across the sand collecting pit inclined surface 8b.

Nozzles 9a and 9a' are installed at the upper end of the main trough 8a and the upper end of the sand collecting pit inclined surface 8b, and a large number of nozzles 9b are provided along the side walls Wa and Wb of each of the areas B1 to B6 (see FIG. 6). Is installed. Further, a nozzle 9c (see FIGS. 2 and 6) for stirring the earth and sand collected in the sand collecting pit 7 is installed.

A plurality of nozzles 9b installed in the areas B1 to B6 are installed in the nozzle headers NH1 to NH6 installed near the sidewalls Wa and Wb of the areas B1 to B6. As shown in detail in FIG. 7, the nozzle headers NH1 to NH6 shown in FIGS. 2 and 5 are configured by attaching a plurality of nozzles 9b to a mother pipe 11 having a branch pipe 10 at equal intervals. Since the length of the sand basin 2 is 18 m and the length of the area of one section is 6 m, each of the nozzle headers NH1 to NH6 has a length of 6 m and has 12 nozzles (6000 mm/nozzle mounting interval 500 mm). 9b are attached at equal intervals. In the preferred embodiment, as shown in FIGS. 2 and 8, the intervals of all the nozzle headers NH3, NH1, NH5, NH4, NH2, NH6 arranged in parallel along each side wall are equal. It is an interval.

In the example shown in FIG. 5, nozzle headers NH1 to NH6 of equal length are installed near the respective side walls of the six regions B1 to B6. The central areas B1 and B2 exist on both sides of the sand collecting pit inclined surface 8b, but the length thereof is the same as that of the other areas B3 to B6. Therefore, the same nozzle header NH illustrated in FIGS. 6 and 7 is installed in all areas B1 to B6.

In that case, some of the nozzles 9b existing in the center of the nozzle headers NH1 and NH2 in the areas B1 and B2 are installed so as to face the inclined surface 8b of the sand collecting pit. When the amount of accumulated sediment is particularly large, a large amount of sediment may flow into the sand collecting pit inclined surface 8b from the areas B1 and B2. Therefore, the water sprayed from the several nozzles 9b in the center is discharged from the nozzle 9a′. This water is preferable because it promotes the collection of the earth and sand flowing on the inclined surface 8b of the sand collecting pit to the sand collecting pit.

A drainage pump P1 and a water supply pump P2 that also functions as a accumulated water pump are installed in the pump well 3, and a sand pump P3 is installed in the sand collecting pit 7. F in FIG. 1 is a filter installed at the downstream end of the sand basin 2.

As illustrated in FIG. 6, low pressure water from the water supply pump P2 is supplied to the nozzles 9a, 9a′, 9b, 9c, or the sand collecting valve groups VG1 and VG2 for stopping the supply, that is, , Trough sand collecting valves Va1, Va2, Va3, nozzle header sand collecting valves Vb1 to Vb6, and sand stirring nozzle sand collecting valve Vc. When the bottom surface of the sand basin is divided into 6 areas (B1 to B6), six nozzle header sand collecting valves Vb (Vb1 to Vb6) are used as illustrated in FIG. Each sand collecting valve, like the conventional sand collecting valve, is directly connected to the flow rate adjusting valve and the switching valve.

The sand collecting valve groups VG1 and VG2, that is, the trough sand collecting valves Va1, Va2 and Va3, the sand collecting valves Vb1 to Vb6 for each nozzle header, and the sand collecting valve Vc for the earth and sand stirring nozzles will be described later in the sand collecting device. The sand collecting valve control circuit of the controller drives the opening operation or the closing operation in a predetermined order.

FIG. 8 is a diagram showing an arrangement of the sand collecting valve groups VG1 and VG2 and a water supply system corresponding to the nozzle arrangement of FIG. In the figure, the sand-mixed water pumped from the sand pump P3 is transferred to the wastewater settling basin 14 after the sand is separated in the settling separator 13. The relief circuit 12 connected to the water supply pump P2 is connected to the sand basin 2 via the sand collecting valve Vd.

The control device of the sand collecting device includes a water supply pump control circuit, a sand pump control circuit, and a sand collecting valve control circuit.

In the sand collecting pit 7, a high water level sensor for detecting that the height of the water surface in the sand collecting pit is equal to or higher than a predetermined high water level, and a height of the water surface in the sand collecting pit becomes a predetermined low water level. And a low water level sensor for detecting the fact.

When activated, the lift pump control circuit starts the automatic operation mode of the lift pump P3, and when the high water level sensor detects that the water level is higher than or equal to the high water level, starts the operation of the lift pump P3. When the low water level sensor detects that the water level is low, the operation of the sand pump P3 is stopped, and when a series of sand collecting valve control by the sand collecting valve control circuit is completed, the sand pump P3 is automatically operated. The operation mode is released.

The sand collecting valve control circuit opens the sand collecting valves VG1, VG2, that is, the trough sand collecting valve Va, the nozzle header sand collecting valve Vb, and the sand stirring nozzle sand collecting valve Vc in a predetermined order. Alternatively, the closing operation is performed.

Next, the operation of the above configuration will be described. As shown in FIG. 1, when the dam device 5 is opened, the sewage W flows into the sand basin 2 and further into the pump well 3, and when the water level reaches a predetermined height L1, the drainage pump P1. Is operated to pump up the water in the pump well 3 and transfer it to a terminal treatment plant (not shown).

During the transfer, sediment is deposited from the sewage mixed with sediment that has flowed into the sand basin 2, and is deposited on the bottom 2a of the sand basin. When the accumulated amount reaches a predetermined value, the dam device 5 is closed. Then, when the water level of the sand basin 2 and the pump well 3 is lowered by the drainage of the drainage pump P1 to reach a predetermined water level L2 equal to the upper surface of the weir provided between the sand basin 2 and the pump well 3, the operation of the drainage pump P1 is performed. Can be stopped.

The control device activates the water supply pump control circuit, the sand pump control circuit, and the sand collecting valve control circuit when the water surface of the pump well 3 reaches a predetermined water level L2.

At the beginning of activation, the height of the water surface in the sand collecting pit of the sedimentation basin is higher than the high water level, so the activated sand pump control circuit starts the automatic operation mode of the sand pump P3. , Start operation of the sand lifting pump P3. Therefore, since the sediment in the sand collecting pit is sucked up by the sand pump P3, the water level in the sand collecting pit starts to decrease.

On the other hand, the activated sand collecting valve control circuit first opens the sand collecting valve Vd of the relief circuit 12 to prepare to drive the water supply pump P2 (step S21 in FIG. 9). Then, after opening the trough sand collecting valve Va (Va1 to Va3) (S22), the sand collecting valve Vd of the relief circuit 12 is closed (S23), so that the water from the water supply pump P2 is discharged from the nozzles 9a and 9a'. It is jetted to the main trough 8a and the sand collecting pit inclined surface 8b. As a result, the earth and sand in the main trough and on the inclined surface of the sand collecting pit are washed away with the water toward the sand collecting pit 7. Therefore, the water level in the sand collecting pit, which has begun to drop, temporarily rises, but since the sand pump P3 continues to operate, it begins to drop again.

When the water level in the sand collecting pit drops to a predetermined water level (Y in S24), that is, when the water level falls between the predetermined high water level and the predetermined low water level, the sand collecting valve control circuit determines that the nozzle Of the header sand collecting valves Vb, the order x of the nozzle header sand collecting valve Vb to be opened is set to "1", and first, the nozzle header sand collecting valve Vb1 of the first region B1 on the bottom of the sand basin is set. Open it (S25).

At this time, jetting from the nozzles 9a and 9a' to the main trough 8a and the sand collecting pit inclined surface 8b continues. Therefore, also in this case, the water level in the sand collecting pit, which has begun to drop, temporarily rises, but since the sand pump P3 continues to operate, it begins to drop again.

When a preset constant time T has elapsed from that point (when Y in S26), the nozzle header sand collecting valve Vbx, that is, the nozzle header sand collecting valve Vb1 in the first region B1 is closed, The order x is set to "x+1", and the nozzle header sand collecting valve in the area of the next order, that is, the nozzle header sand collecting valve Vb2 in the second area B1 is opened (S27).

At that time, it is checked whether or not "x+1" is the last rank of the area, that is, 6 (S28), and if it is not the last rank, the process returns to step S26 and the sand collecting valve for the nozzle header of the area of the rank at that time is set. At the same time as closing, the sand collecting valve for the nozzle header in the next-ranked area is opened (S27).
Each time the nozzle header sand collecting valve Vb in each region is sequentially opened, the temporary rising of the water level in the sand collecting pit which has started to decrease and the subsequent re-lowering are repeated.

Then, in step S27, when the nozzle header sand collecting valve in the last ranked area, that is, the nozzle header sand collecting valve Vb6 in the sixth area B6 is opened (when Y in S28), the constant time T has elapsed. When (YES in S29), the sand collecting valve Vd of the relief circuit 13 is opened, and the nozzle header sand collecting valve of the last rank area, that is, the nozzle header sand collecting valve Vb6 of the sixth area B6 is opened. Then, the sand collecting valve Va for the nozzle is closed (S210).

After that, the water level in the sand collecting pit drops to a predetermined low water level, so that the sand pump is stopped. As a result, a series of sand collecting operations and sand removing operations are completed. When the series of sand collecting operations and sand removing operations are completed, the automatic operation mode of the sand pump is released.

In the example shown in FIG. 6 and FIG. 8, it is installed in the region existing in the center of the sand basin in the longitudinal direction, that is, in the first region B1 and the second region B2 existing across both sides of the sand collecting pit inclined surface 8b. The nozzle 9b existing in the central portion of the nozzle headers NH1 and NH2 faces the sand collecting pit inclined surface 8b. Since the sand collecting pit inclined surface 8b is adjacent to the deepest position of the inclined bottom surface of the sand basin, a relatively large amount of sediment flows from the bottom surface into the sand collecting pit inclined surface 8b. Therefore, the water jetted from the central nozzle accelerates the flow of the earth and sand on the sand collecting pit inclined surface 8b toward the sand collecting pit by the nozzle 9a'. Further, in the case of a sand basin in which the amount of sediment flowing into the sand collecting pit inclined surface 8b is small, the nozzle 9a' of the sand collecting pit inclined surface 8b can be omitted. Therefore, in that case, the sand collecting valve for the nozzle 9a' can be eliminated.

1 Rainwater treatment facility 2 Sand basin 2a Bottom of sand basin 3 Pump well 7 Sand collecting pit 8a Main trough 8b Sand collecting pit slope 8c Small trough B1 to B6 area 9a Main trough nozzle 9a' Sand collecting pit slope nozzle 9b Nozzle of nozzle header NH1 to NH6 Nozzle header P1 Drainage pump P2 Water supply pump P3 Sand pump

Claims (1)

Having a sand collecting pit at the deepest part of the bottom of the sand basin, at the bottom of the sand basin, having a trough extending parallel to the water flow direction in the sand basin and leading to the sand pit, from the sidewall of the sand basin It has a sand collecting pit inclined surface leading to the sand collecting pit in a direction orthogonal to the water flow direction in the sand basin, the bottom of the sand basin is divided into a plurality of regions in the water flow direction in the sand basin, the region Nozzle header having a plurality of nozzles is installed along the side wall of the sand basin, by supplying low pressure water from the water supply pump to the nozzle header in the drainage state of the sand basin and jetting from the nozzle, In the sand collecting device of the sand basin, which collects the sediment deposited in the area on the trough, and collects in the sand collecting pit through the trough,
One of the regions, set the current sand pit inclined surface,
While straddling the nozzle header over the sand collecting pit inclined surface, a part of the nozzle of the nozzle header is installed to face the sand collecting pit inclined surface,
A sand collecting device for a settling basin.

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