JP2011245385A - Method and apparatus for removing sand in settling basin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sand removing method which can reduce the frequency of start and stop of a sand pump and enables use of an ordinary low-cost pump.SOLUTION: In the sand removing method where water is jetted from nozzles for sand collection provided in a settling basin in a state where water is discharged, to collect deposited earth and sand into a sand collecting pit, and when the water surface of the pit is equal to or higher than a predetermined high water level, a sand pump is operated and when it becomes a predetermined low water level, the sand pump is stopped, thereby pumping up the earth and sand, the control of switching valves for switching between supply and stopping supply to nozzle headers comprises a first process for opening switching valves of nozzles for troughs and the sand collecting pit for a predetermined time, a second process for specifying the order of blocks to which water is jetted from the nozzle headers, a third process for opening the nozzles of the specified block for a predetermined time, a fourth process for waiting until the water surface in the sand collecting pit decreases to a predetermined water level, a fifth process for determining whether the order of the block at completing the fourth process is the last order or not, a sixth process for returning to the first process when the order of the block is not the last order, and a seventh process for waiting until the water surface in the sand collecting pit decreases to a predetermined low water level when the order of the block is the last order.

Description

  The present invention relates to a sand removal method and a sand removal apparatus that collects earth and sand deposited in a sand basin of a sewage treatment facility in a sand collecting pit, and removes the collected sand by pumping up with a pump.

  Sand collected at the bottom of the sand basin by discharging low pressure water from the nozzle to the bottom of the sand basin while draining the water in the sand basin with a drain pump (draining state) Patent Document 1 discloses a low pressure sand collection type sand removal device that collects sand and sand in the pit, pumps the collected earth and sand together with water by a sand pump installed in the sand collection pit, and transfers it to a sewage settling basin.

  A sand basin that performs low-pressure sand collection by the sand removal device has the following structure. That is, the bottom surface of the sand basin is inclined so that a part thereof, for example, the center is deepest, and a sand collecting pit is formed in a part of the bottom surface, and the bottom part of the sand basin is formed between the side walls on both sides of the sand basin. The trough parallel to the water flow direction in the sand basin (hereinafter referred to as the main trough) is formed so that the sand collecting pit side is deep, and the bottom surface of the sand basin is parallel to the direction perpendicular to the water flow direction in the sand basin. A number of extending troughs (hereinafter referred to as small troughs) are formed.

  In order to perform low-pressure sand collection, a number of nozzles are installed as follows. That is, nozzles are installed at the upper end of the main trough, the upper end of the inclined surface of the sand collection pit, and the upper end of the block (area) that divides the bottom of the sand basin into the direction of water flow in the sand basin. Yes. Hereinafter, the nozzle installed at the upper end of the main trough may be referred to as a trough nozzle. A plurality of nozzles of the block are installed at equal intervals on nozzle headers installed along the side walls of the sand basin in each block. In some cases, a sediment mixing nozzle is installed in the sand collection pit.

  In order to perform low-pressure sand collection, water from the water supply pump installed in the pump well connected downstream of the sand basin is supplied to the nozzle and nozzle header (water flow), A switching valve group for stopping (water stopping), that is, a trough nozzle switching valve, a switching valve for each nozzle header, or a switching valve for a stirring nozzle is further provided. For example, when the bottom surface of the sand basin is divided into four blocks, there are four nozzle header switching valves. The sand removal apparatus has switching valve control means for switching these nozzle header switching valves in a predetermined order.

  In preparation for the sand removal operation, the dam device installed on the upstream side of the sand basin is kept open and rainwater, sewage and other sewage is flowing into the sand basin and installed in the pump well. The drainage pump is operated and the supernatant water is transferred to the final treatment plant. Then, the dam device is closed to prevent sewage from entering the sand basin. As a result, when the amount of water in the pump well is reduced and the water surface becomes the same height as the upper surface of the weir provided between the sand basin and the pump well, the operation of the drainage pump is stopped. Thereby, the preparation for the sand removal operation is completed.

  Subsequently, when a sand removal operation start command is input to the sand removal device, the automatic operation mode of the sand pump is started. In the automatic operation mode, the water level sensor installed in the sand collection pit is collected in the sand pump. When it is detected that the water level in the sand pit has exceeded the predetermined high water level, it automatically starts operation, and when the water level sensor detects that the water level in the sand collection pit has reached the predetermined low water level. Is configured to automatically stop operation. That is, the sand pump operates so as to maintain the drainage state in which the water surface in the sand basin is located in the sand collection pit.

  Further, based on the sand removal operation start command input, the switching valve is controlled by the switching valve control means. However, conventionally, the control of the sand pump and the control of the switching valve have been performed independently.

  More specifically, when the automatic operation mode of the sand pump is started, the water pump in the sand collection pit starts operation because the water level in the sand collection pit is higher than the high water level. Since the water level drops to a predetermined low water level, the sand pump stops operation. Following this, the switching valve control means controls the switching valve as follows. Below, the case where the bottom face of a sand basin is divided into 4 blocks is demonstrated to an example.

a) The switching valve control means first opens the trough nozzle switching valve and supplies water from the water supply pump to the main trough nozzle and the nozzles on the inclined surface of the sand collecting pit, so that water is jetted from these nozzles. b) After the time Tx required for the earth and sand in the main trough to flow into the sand collecting pit has elapsed, the nozzle header switching valve of the first block on the bottom of the sand basin is opened. c) After the lapse of the predetermined time T1, the nozzle header switching valve of the first block is closed and the nozzle header switching valve of the second block is opened. d) After the fixed time T2 has elapsed, the nozzle header switching valve of the second block is closed and the nozzle header switching valve of the third block is opened. e) After the predetermined time T3 has elapsed, the nozzle header switching valve of the third block is closed and the nozzle header switching valve of the fourth block is opened. f) After the lapse of the predetermined time T4, the nozzle header switching valve of the fourth block is closed and the trough nozzle switching valve is closed.
The fixed times T1 to T4 are times necessary for flowing the sediment accumulation amount of the block.

  After closing the nozzle header switching valve in the 4th block, the water in the sand basin flows into the sand collecting pit and the sand basin is drained, that is, when the water level sensor detects a low water level. The sand pump stops operating. Thereby, a series of sand removal operations is completed. When this series of sand removal operations is completed, the automatic operation mode of the sand pump is canceled.

Japanese Patent No. 3315489

  The opening operation of the nozzle header switching valve in the subsequent block performed after each of the predetermined times T1 to T4 has a slight difference depending on the type of the switching valve, but it is relatively long as 30 seconds to 1 minute. It takes time. For this reason, the water level in the sand collecting pit may be lowered to a predetermined low water level each time the switching valve is switched. Therefore, each time, the sand pump was automatically operated and stopped repeatedly. That is, when the water level in the sand collection pit is at a predetermined high water level, the operation of the sand pump is automatically started, and when the water level is at a predetermined low level, the operation of the sand pump is automatically stopped. In the sand method, since the frequency of start and stop of the sand pump is high, there is a problem that a normal pump has a large load and a short service life. Although it is conceivable to use a pump that takes into account the high frequency of starting and stopping operations, there is a problem that such a pump is expensive.

  The present invention has been made in view of the above circumstances, and a first object is to reduce the frequency of starting and stopping the operation of the sand pump as much as possible and to use a normal inexpensive pump. Is to provide a simple sand removal method.

  A second object of the present invention is to provide a sand removal apparatus for using the above method.

  In order to achieve the first object, the present invention ejects water from the main trough of the sand basin and the nozzles installed on the inclined surfaces of the sand collecting pit in the state where the sand basin is drained, and the bottom surface of the sand basin. The nozzles of the nozzle header provided in the block divided into a plurality of blocks are sprayed with water for a predetermined time in a predetermined order for each block, the earth and sand accumulated in the block is caused to flow to the main trough, and further sand collecting When the water level in the sand collection pit installed in the sand collection pit is higher than the predetermined high water level, the operation is automatically started, and the water level in the sand collection pit is set to the predetermined low water level. Nozzle and nozzle header installed on the inclined surface of the main trough and sand collection pit in the sand removal method that removes the sediment by pumping up and removing the sand with a sand pump that automatically stops operation The control of the switching valve for supplying or stopping the supply is performed by the first step of opening the switching valve of the nozzle installed on the inclined surface of the main trough and the sand collecting pit for a predetermined time, and the water from the nozzle header following the first step. A second step of sequentially designating the order of blocks to be sprayed, a third step of opening the nozzle header switching valve of the designated order of blocks for a predetermined time, and a water surface in the sand collecting pit after the third step A fourth step of waiting until the pressure drops to a predetermined intermediate water level between the predetermined high water level and the predetermined low water level, and a step of determining whether the order of the blocks at the end of the fourth step is the last order When the determination result is not the last order, the sixth process returns to the first process, and when the determination result is the last order, the process waits until the water level in the sand collecting pit drops to the predetermined low water level. Characterized by the seventh process Are (claim 1).

In order to achieve the second object, the present invention provides a sand basin, (in this case, the sand basin is inclined so that a part of the bottom of the sand basin is deep, and a part of the bottom And a main trough formed so that the sand collecting pit side becomes deep between the formed sand collecting pit and the side wall on both sides of the sand settling basin in parallel with the water flow direction in the sand settling basin), Drainage pump installed in the continuous pump well, sand pump installed in the sand collection pit, sand pump control means for controlling the sand pump, and detecting and outputting the water level in the sand collection pit A water level detecting means, a nozzle installed at the upper end of the main trough and the upper end of the inclined surface of the sand collecting pit, and a block formed by dividing the bottom surface of the sand basin into a plurality of water flow directions in the sand basin. For each, the side of the sand basin Nozzle header installed above the bottom surface in the vicinity, to which a large number of nozzles are attached, the main trough of water from the water supply pump and the nozzles on the inclined surface of the sand collection pit, and water flow / stop water to each nozzle header In a sand removal apparatus comprising a switching valve group that performs the switching valve control means for controlling the switching operation of the switching valve group in a predetermined order,
The water level detection means detects whether the position of the water surface in the sand collection pit is a predetermined high water level or higher, a predetermined intermediate water level in the sand collection pit and a predetermined low water level,
The sand pump control means starts an automatic operation mode based on an input of a sand removal operation start command, starts operation of the sand pump based on a detection signal above the high water level from the water level detection means, and detects the water level. The operation of the sand pump is stopped based on a low water level detection signal from the means, and the switching valve control means is configured to switch the nozzle switching valve for the main trough and the sand collecting pit inclined surface when sand collecting is performed for the last block. After closing, the automatic operation mode is canceled.
The switching valve control means each time a block order designating part for sequentially designating the order of blocks to which water should be jetted from the nozzle header and an intermediate water level detection signal from the water level detecting means are input at that time. The rank determination unit for determining whether or not the rank of the block designated by the rank designation unit is the last order, and the rank when the intermediate water level detection signal is input after the sand removal operation start command is input or from the water level detection means A first switching valve control unit for closing a nozzle switching valve on the inclined surface of the main trough and the sand collecting pit for a predetermined time when the determination unit determines that the order is not in order; The header switching valve includes a second switching valve control unit that opens and closes the header switching valve after a predetermined time (claim 2).
With the above configuration, the automatic operation mode is started based on the sand removal operation start command input, the operation of the sand pump is started based on the detection signal above the high water level from the water level detection means, and the first switching valve of the switching valve control means. After the control unit opens and closes the nozzle switching valve on the main trough and sand collecting pit slant surface for a predetermined time, the second switching valve control unit switches the nozzle header for the first order block designated by the block order designation unit. Open and close the valve for a predetermined time. Each time an intermediate water level detection signal is input from the water level detection means, the rank determination unit determines whether or not the block rank specified at that time is in the last order. After the nozzle switching valve on the main trough and the sand collecting pit inclined surface is opened and closed for a predetermined time, the second switching valve control unit sets the nozzle header switching valve for the next block designated by the block order designation unit for a predetermined time. Open and close. The opening of the nozzle switching valve on the inclined surface of the main trough and the sand collecting pit for a predetermined time and the opening of the nozzle header switching valve of the block in the predetermined order are repeated until the last block. If the block order specified when the intermediate water level detection signal is input from the water level detection means is the last order, the operation of the sand pump is stopped when the low water level detection signal is input from the water level detection means, Automatic operation mode is canceled.

  According to the method of the first aspect of the present invention, since the earth and sand in the trough is first flowed into the sand collecting pit before flowing the earth and sand from the respective blocks on the bottom surface of the sand basin, the earth and sand flowing from the bottom to the trough is then smoothed. It can be moved to the sand collecting pit. In addition, when the water level in the sand collection pit falls below a predetermined intermediate water level between a predetermined high water level and a predetermined low water level, the nozzle header switching valve corresponding to the preceding block is closed and the subsequent block Therefore, the water level in the sand collecting pit cannot be lowered to a predetermined low level during the switching operation of the switching valve, and therefore the start and stop of the operation of the sand pump is stopped. The frequency can be reduced. Therefore, a normal inexpensive pump can be used for the sand pump.

  According to the invention of the apparatus of claim 2, the invention of the above method for reducing the frequency of starting and stopping the operation of the sanding pump by slightly improving the water level detecting means, the sanding pump control means and the switching valve control means is inexpensive. Can be implemented.

It is a longitudinal cross-sectional view of the rainwater treatment facility including a sand basin. FIG. 2 is a partially omitted plan view of a range of XX in FIG. 1. FIG. 3 is a cross-sectional view taken along line Y1-Y1 of FIG. FIG. 3 is a sectional view taken along line Y2-Y2 of FIG. FIG. 3 is a cross-sectional view taken along line Y3-Y3 of FIG. It is a water supply system diagram. It is a control system diagram which illustrates the control device in one embodiment. It is sectional drawing which shows the detection water level by the water level sensor of a sand collection pit. It is a flowchart of a sand pump control means. It is a flowchart of a switching valve control means.

Next, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a rainwater treatment facility, which has a sand basin 2 and a pump well 3 formed between side walls Wa and Wb (see FIG. 2). The settling basin 2 is connected to an inflow trough 4 from which sewage such as rainwater and sewage is collected from a sewage pipe not shown. A dam device 5 for allowing or preventing the inflow of sewage from the inflow trough 4 to the sand basin 2 is installed at the downstream end of the inflow trough 4. A contaminant capturing screen 6 is installed immediately before the upstream end of the screen.

  In order to perform low-pressure sand collection, the bottom surface 2a of the sand basin 2 is inclined so that a part thereof, for example, the center becomes the deepest as described above, and the sand collection pit 7 is formed at the bottom center of the sand basin 2. A main trough 8a is formed in the center of the bottom of the sand basin in the width direction so that the sand collecting pit side is deeper. Further, the bottom of the sand basin is parallel to the main trough 8a from the vicinity of the side walls Wa and Wb. A number of extending small troughs 8c are formed. When the width of the bottom of the sand basin is small, the main trough 8a may be formed not at the center in the width direction but at a position closer to either one of the side walls Wa and Wb. Reference numeral 8b denotes an inclined surface that is inclined downward from the side walls Wa and Wb to the bottom surface of the sand collecting pit 7 (also referred to as a sand collecting pit inclined surface in this specification).

  In the pump well 3, a drainage pump P <b> 1 described later and a water supply pump P <b> 2 serving also as a staying water pump are installed, and a sand pump P <b> 3 described later is installed in the sand collecting pit 7. F of FIG. 1 is a filter installed at the downstream end of the sand basin 2.

  In addition, a nozzle 9a is installed at the upper end of the main trough 8a and the upper end of the sand collecting pit inclined surface 8b, and the bottom surface of the sand basin is divided into a plurality of sides on both sides of the main trough 8a (in FIG. 2 and FIG. 6, 8 sections). A nozzle 9b is installed at the upper end of the block (area) B. A plurality of nozzles 9b installed in the block B are installed at equal intervals on the nozzle header NH installed in each block in the vicinity of the side walls Wa and Wb. FIG. 5 shows an example in which nozzle headers NH1, NH2,... Formed by attaching a plurality of water supply nozzles 9b to the mother pipe 10 at a predetermined interval are shown. Preferably, a sediment agitation nozzle 9 c is installed in the sand collection pit 7.

  Then, as illustrated in FIG. 6, the water from the water supply pump P <b> 2 of the pump well 3 is supplied to the nozzles 9 a, 9 b, and 9 c (water passing), or the supply is stopped (water stopping). There are provided switching valve groups VG1, VG2 constituted by automatic valves, that is, a trough nozzle switching valve Va, each nozzle header switching valve Vb, and a sediment agitation nozzle switching valve Vc. As illustrated in FIG. 6, when the bottom surface of the sand basin is divided into eight blocks, eight nozzle header switching valves Vb (Vb1 to Vb8) are used.

  A relief circuit 11 is provided via a switching valve Vd in a pipeline connecting the water supply pump P2 and the switching valve groups VG1 and VG2, and the water supply pump when all the switching valves Va, Vb, and Vc are closed. The water from P2 is configured to escape to the sand basin 2. Thus, when all the switching valves Va, Vb, and Vc are closed, the water level in the sand basin can be maintained by supplying water from the water supply pump P2 to the sand basin 13.

  In addition, the soil-mixed water pumped up from the sand collection pit 7 by the sand pump P3 is transferred to the sewage sedimentation basin 13 after the sediment is separated by a known sedimentation separator 12.

As illustrated in FIG. 7, an operation panel 101 having a sand removal start button (not shown) is added to the control device 100 provided in the sand removal device for carrying out the method of the present invention, and a drain pump control circuit PCON1, A feed water pump control circuit PCON2 and a sand pump control circuit PCON3 are incorporated, and a switching valve control circuit VCON is incorporated.
As illustrated in FIG. 7 and as will be described later, the switching valve control circuit VCON includes a block order designating unit 102 for sequentially designating the order of blocks to which water should be injected from the nozzle header, and a water level sensor 14 described later. Each time an intermediate water level detection signal is input, a rank determination unit 103 that determines whether or not the block rank designated by the block rank designation unit 102 is in the last order, and the switching valve Vd of the relief circuit are opened and closed. When the determination result of the rank determination unit 103 is not in the last order after the first switching valve control unit 104 that controls the sand removal operation start command or the intermediate water level detection signal from the water level sensor 14 is input, And a second switching valve control unit 105 that opens the nozzle switching valves Va and Vc on the sand collecting pit inclined surface for a predetermined time, and a nozzle header switching valve of a block in which the order is designated and a third switching valve control unit 106 that opens each of b1 to Vb8 for a predetermined time, and gives a control signal for driving the opening or closing operation in a predetermined order to the group of switching valves Va, Vb, Vc, Vd. Is.

  Further, the control device 100 detects and outputs whether the water level at the installation position of the sand collecting pit 7 is higher than the predetermined high water level HWL conceptually shown in FIG. 8, the intermediate water level MWL, or the low water level LWL. A water level sensor 14 (see FIGS. 7 and 8) is electrically connected.

  When the sand pump P3 is operated, it draws water from the sand basin, lowers the height of the water surface in the sand basin, and exposes the bottom surface of the sand basin from the surface of each nozzle 9a, 9b, 9c. It is used for spraying water and pouring the sediment on the bottom into the sand collecting pit. Based on the signal output when the water level sensor 14 detects the high water level HWL, the sand pump control circuit PCON3 Starts operation of the sand pump P3.

  Where the water level at the position of the sand collecting pit 7 is set as the high water level HWL depends on the water absorption capacity of the sand pump P3 and the size of the sand basin, that is, the volume of the sand basin. . In order to prevent the water level from reaching the low water level LWL within a short time from the start of operation of the sand pump P3 when the volume of the sand basin is small compared to the water absorption capacity of the sand pump P3, the main trough It is desirable to set the highest point H1 of 8a (see FIGS. 2 and 8) to the high water level HWL. In addition, when the volume of the sedimentation basin is larger than the water absorption capacity of the sand pump P3, the time from the start of operation of the sand pump P3 until the water level reaches the low water level LWL is long, so the lowest point of the main trough 8a When H3 (see FIGS. 2 and 8) can be set to the high water level HWL and the relationship between the water absorption capacity of the sand pump P3 and the volume of the sedimentation basin is in the middle of the above example, the highest point H1 and the lowest During the point H3, for example, the lowest point H2 (see FIGS. 2 and 8) on the bottom of the sand basin can be set to the high water level HWL. FIG. 8 shows an example in which a high water level HWL is set at the lowest point H3 of the main trough 8a.

  Then, the effect | action by the said structure is demonstrated. When the dam device 5 is opened, the sewage flows into the sand basin 2 and further into the pump well 3, and when the water level reaches a predetermined height, the drain pump control circuit of the control device 100 of the sand removal device. The drain pump P1 provided in the pump well 3 is operated by PCON1, and the water in the pump well 3 is pumped up and transferred to a terminal treatment plant or the like outside the figure.

  During the transfer, earth and sand are precipitated from the sewage mixed with the earth and sand flowing into the sand basin 2 and deposited on the bottom surface 2a of the sand basin. When the accumulation amount reaches a predetermined value, the dam device 5 is closed and the sewage flow into the sand basin 2 is prevented. And if the water surface of the sand basin 2 and the pump well 3 falls by the drainage by the drainage pump P1 and reaches a predetermined water level (WL in FIG. 1), the drainage pump control circuit PCON1 stops the operation of the drainage pump P1.

  When it is detected that the water level of the pump well 3 has reached a predetermined water level (WL in FIG. 1), the control device 100 activates the feed water pump control circuit PCON2, the sand pump control circuit PCON3, and the switching valve control circuit VCON.

  As shown in FIG. 9, the sand pump control circuit PCON3 starts the automatic operation mode of the sand pump P3 (S11), and the water level in the sand collecting pit 7 is set to a predetermined high water level by the detection signal from the water level sensor 14. It is checked whether or not it is equal to or higher than HWL (S12), and when it is equal to or higher than the high water level HWL, the operation of the sand pump P3 is started (S13).

  Further, as shown in FIG. 10, the switching valve control circuit VCON starts a control program based on a sand removal operation start command input from the operation panel 101, and the first switching valve control unit 104 first switches the relief circuit. The valve Vd is opened to prepare for driving the water supply pump P2 (step S21 in FIG. 10). Subsequently, after the second switching valve controller 105 opens the trough nozzle switching valve Va and the earth and sand agitation nozzle switching valve Vc (S22), the first timer (not shown) is started (S23), and The one switching valve control unit 104 closes the switching valve Vd of the relief circuit 11 (S23 ′). When the first timer expires, that is, when water from the water supply pump P2 is sprayed from the nozzle 9a to the main trough 8a and the sand collecting pit inclined surface 8b for a predetermined time (Y in S24), the trough nozzle switching valve Va and The switching valve Vc for the earth and sand stirring nozzle is closed (S25). Subsequently, since the block order specifying unit 102 of the switching valve control circuit VCON increments (i + 1) the order (i) (S26), the third switching valve control unit 106 has the order specified by the block order specifying unit 102. In order to open the nozzle header switching valve Vb1 of the block, that is, the first block B1 in this case (S27), water is injected from each nozzle of the nozzle header NH1, and the sediment accumulated in the first block B1 is removed. It flows toward the main trough 8a and further flows into the sand collecting pit 7. Thus, the sewage mixed with the earth and sand collected and stirred in the sand collecting pit 7 is pumped up by the sand pump P3 and transferred to the sewage sand settling basin 13 through the sand settling separator 11.

  When the nozzle header switching valve Vb1 of the first block B1 is opened, a second timer (not shown) is started, and when the time is up by the elapse of a predetermined time set in advance (Y in S29), the first The nozzle header switching valve Vb1 of the block B1 is closed.

  Since the discharge amount of the sand pump P3 is designed to be larger than the discharge amount of the water supply pump P2, the water surface in the sand collecting pit 7 rises temporarily due to the inflow of water and earth and sand, but eventually decreases. After that, when the water level sensor 14 detects that the water level in the sand collection pit has reached a predetermined intermediate water level (Y in S211), the rank determining unit 103 of the switching valve control circuit VCON then blocks. It is determined whether or not the order specified in the order specifying unit 102 is the last order (S212).

  If it is not the last order, the process returns to S22, and the second switching valve controller 105 discharges water to the main trough 8a and the sand collecting pit inclined surface 8b for a predetermined time (S22-S25), and then the block order designation unit 102 The next block is designated (S26), and the switching valve control circuit VCON opens the nozzle header switching valve Vb2 of the second block B2 for a predetermined time and then closes it. When it is detected again by the water level sensor 14 that the water level in the sand collecting pit has reached the predetermined intermediate water level, it is then determined whether or not the block order is the last order (S212). That is, until the water injection target block is in the last order, water discharge for a predetermined time (S22 to S25) from the nozzle 9a to the main trough 8a and the sand collecting pit inclined surface 8b for the block and water discharge for a predetermined time from the nozzle header ( S27-S210) are repeated. As a result, the earth and sand of all the blocks on the bottom surface of the sand basin are caused to flow along with the water to the main trough 8 a and flow toward the sand collecting pit 7.

  When the rank determination unit 103 determines the last order, that is, the fourth block B4 (Y in S212), the water level sensor 14 detects that the water level in the sand collection pit has become a predetermined low water level. At (when Y in S213), the first switching valve control unit 104 of the switching valve control circuit VCON performs control to open the switching valve Vd of the relief circuit, and the series of switching valve control is completed. Further, the feed water pump control circuit PCON2 also stops the operation of the feed water pump P2.

  On the other hand, the sand pump control circuit PCON3 constantly monitors the detection state of the water level sensor 14 from the start of the operation of the sand pump P3, and by closing the nozzle header switching valve Vb4 of the fourth block B4, Since the water level in the sand pit 7 falls to the low water level LWL (when S14 is Y), the operation of the sand pump P3 is stopped (S15). Thereafter, the sand pump control circuit PCON3 checks whether or not the control of the switching valve has been completed (S16). If not completed, the process returns to step S12, and if the water level becomes high (Y in S12). The operation of the sand pump P3 is started again, but after confirming the completion of the switching valve control (Y in S16), the automatic operation mode of the sand pump is canceled (S17).

  As described above, when the sand pump P3 starts the automatic operation mode, the sand collecting pit 7 is automatically drained when the water level at the sand collecting pit installation position is higher than a predetermined high water level HWL in order to maintain the inside of the sand collecting pit 7 in a drained state. When the water level drops to a predetermined low water level LWL, the operation is automatically stopped. In the method of the present invention, water is discharged from the trough nozzle and the sediment stirring nozzle for a predetermined time, and After discharging water from the nozzle header of the block for a predetermined time, every time the water level of the sand collection pit is lowered to the predetermined intermediate water level by pumping up by the sand pump, the predetermined time from the trough nozzle and the earth agitation nozzle until the last block is reached. Since water discharge and water discharge from the nozzle header of the block are repeated for a predetermined time, the switching operation of the switching valve with respect to the preceding block and the subsequent block are repeated. During the switching operation of the switching valve, the water surface at the sand collecting pit installation position is stopped by the closing operation of the switching valve for the preceding block, pumping of the sand pump, and opening of the switching valve for the subsequent block. The water level sensor may detect the intermediate water level between the time when the switching valve is closed for the preceding block and the time when the switching valve is opened for the subsequent block. However, the opening times of the switching valves Va, Vc, Vb by the second switching valve control unit 105 and the third switching valve control unit 106 may be set so that the low water level is not detected. Further, the height position of the intermediate water level may be set based on the injection amount of each nozzle and each nozzle header, the volume of the sand basin, the discharge amount of the sand pump, and the like.

  If an automatic solenoid valve with a fast switching operation is used as the nozzle header switching valve, the water level in the sand collecting pit from the end of water injection to the previous block to the start of water injection to the next block is reduced. Since the amount of decrease can be reduced, the accuracy in setting the intermediate water level is relaxed. Moreover, since the load of the sand pump is stabilized, the life is extended.

DESCRIPTION OF SYMBOLS 1 Rainwater treatment equipment 2 Settling basin 2a Bottom surface of settling basin 3 Pump well 7 Sand collection pit P1 Drainage pump P2 Water supply pump P3 Sand pump 8a Main trough 8b Inclined surface of sand collection pit 8c Small trough 9a, 9b, 9c Nozzle NH1 NH8 Nozzle header 14 Water level sensor HWL High water level MWL Intermediate water level LWL Low water level Va, Vb, Vc, Vd selector valve

Claims (2)

While draining the sand basin, water is injected from the main trough of the sand basin and the nozzles installed on the inclined surface of the sand collection pit, and the nozzle header of the nozzle header provided on the block formed by dividing the bottom surface of the sand basin into multiple sections Water is ejected from the nozzle for a predetermined time in a predetermined order for each block, and the earth and sand accumulated in the block is flowed to the main trough, and further collected in the sand collection pit, and collected in the sand collection pit. A sand pump that automatically starts operation when the water level in the sand pit is above a predetermined high water level and automatically stops when the water level in the sand collection pit reaches a predetermined low water level. In the sand removal method that pumps up and removes earth and sand by
Control of the switching valve for supplying or stopping the supply of water from the water supply pump to the main trough and the inclined surface of the sand collecting pit and the nozzle header,
A first step of opening a switching valve of a nozzle installed on the inclined surface of the main trough and sand collecting pit for a predetermined time;
A second step of sequentially specifying the order of blocks to be sprayed with water from the nozzle header following the first step;
A third step of opening the nozzle header switching valve of the block in the designated order for a predetermined time;
A fourth step of waiting until the water level in the sand collecting pit drops to a predetermined intermediate water level between the predetermined high water level and the predetermined low water level after the third step;
A fifth step of determining whether or not the order of the blocks at the end of the fourth step is the last order;
A sixth step that returns to the first step when the determination result is not in the last order; and
When the determination result is the last order, the seventh step of waiting until the water surface in the sand collecting pit is lowered to the predetermined low water level;
A sand removal method for a sand basin characterized by comprising A settling basin, in this case, the settling basin is a bottom surface inclined so that a part of the bottom of the settling basin is deep, a sand collecting pit formed in a part of the bottom, and a side wall on both sides of the settling basin A main trough formed so that the sand collecting pit side is deep in parallel with the water flow direction in the sand basin, and a drainage pump installed in a pump well connected to the sand basin, and in the sand collecting pit An installed sand pump, sand pump control means for controlling the sand pump, water level detecting means for detecting and outputting the water level in the sand collecting pit, upper end of the main trough and sand collecting pit A nozzle installed at the upper end of the inclined surface and a block formed by dividing the bottom surface of the sand basin into a plurality of water flow directions in the sand basin above the bottom surface near the side wall of the sand basin. Installed, numerous Nozzle header with attached nozzles, nozzles on the inclined surface of the main trough and sand collecting pit of water from the water supply pump, switching valve group for passing water to and stopping water from each nozzle header, and switching of the switching valve group In a sand removal apparatus comprising switching valve control means for controlling the operation in a predetermined order,
The water level detection means detects whether the position of the water surface in the sand collection pit is a predetermined high water level or higher, a predetermined intermediate water level in the sand collection pit and a predetermined low water level,
The sand pump control means starts an automatic operation mode based on an input of a sand removal operation start command, starts operation of the sand pump based on a detection signal above the high water level from the water level detection means, and detects the water level. The operation of the sand pump is stopped based on a low water level detection signal from the means, and the switching valve control means is configured to switch the nozzle switching valve for the main trough and the sand collecting pit inclined surface when sand collecting is performed for the last block. After closing, the automatic operation mode is canceled.
The switching valve control means each time a block order designating part for sequentially designating the order of blocks to which water should be jetted from the nozzle header and an intermediate water level detection signal from the water level detecting means are input at that time. The rank determination unit for determining whether or not the rank of the block designated by the rank designation unit is the last order, and the rank when the intermediate water level detection signal is input after the sand removal operation start command is input or from the water level detection means A first switching valve control unit for closing a nozzle switching valve on the inclined surface of the main trough and the sand collecting pit for a predetermined time when the determination unit determines that the order is not in order; A sand removal apparatus for a sand basin, comprising: a second switching valve control unit that opens a switching valve for a header for a predetermined time and then closes it.

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