JP2012040564A - Sand pumping-up method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sand pumping-up method which enables to draw in smoothly without closing the suction opening of a sand pumping-up pump with sand in a sand collecting pit.SOLUTION: The sand pumping-up method is characterized as follows. A disturbing unit which injects pressure water near the suction opening of the sand pumping up pump prepared at the sand collecting pit of a sand sedimentation pond, and disturbs the sand deposited near the suction opening; after stopping the indraft of sewage to the sand sedimentation pond, the pump prepared at a pumping well connection-prepared at the sand sedimentation pond through a connection-prepared part is made to drain the stagnant water of the sand sedimentation pond and the pumping well; when the water level of the sand sedimentation pond is set to the same level as the top part of the connection-prepared part by the draining water by the pump, the jetting of pressure water by the disturbing means is made to start; then the sand pumping up pump is worked, and when the water level of the sand sedimentation pond fell to the water level below the level of the bottom of a central trough of the sand sedimentation pond, the operation of the sand pumping up pump is made to stop.

Description

  The present invention relates to a sand-carrying method in which sand (sediment) that has settled on the bottom surface of a sand basin in a sewage treatment facility is collected in a sand collection pit by jet water, and the sand is transferred by a sand-carrying pump.

  Conventionally, a storm water settling basin of a storm water pumping station in a sewage treatment facility has been provided with a sand raising device comprising a jet pump for transferring sand deposited on the bottom surface of the storm water settling basin to a predetermined location. The suction port of the jet pump in this sand pumping device is provided so as to be located above the sand collecting pit provided at the lowest position on the bottom surface of the rainwater settling basin. Therefore, when the jet pump is driven, the sand in the sand collection pit is sucked from the suction port and transferred to a predetermined place via the pipe.

  In addition, since the sand pumping apparatus using the jet pump uses high-pressure water as a driving source, the power cost is high. Therefore, there is a sand pumping apparatus using a spiral blade type sand pump with low power cost.

  In the sand pumping apparatus using this sand pump, the suction port of the sand pump is provided above the sand collecting pit. Therefore, when the sand pump is driven, the sand in the sand collecting pit is sucked from the suction port and transferred to a predetermined place via the pipe (there is no particular prior art document).

  However, in the conventional sand raising device, even if sand is present in the sand collecting pit, even if the jet pump or the sand raising pump starts driving, the sand cannot be sufficiently sucked. There was an inconvenience that the sand could not be moved sufficiently.

  This is because when the jet pump or the sand pump starts driving, the suction port is blocked by the sand that has accumulated in the sand collecting pit, so that neither water nor sand can be sucked.

  Accordingly, the present invention has been made to solve the above-described drawbacks, and the purpose thereof is to enable smooth suction without the suction port of the sand pump being blocked by the sand in the sand collecting pit. The purpose is to provide a sanding method.

In order to achieve the above object, the present invention provides a sand basin in which sand deposited on the bottom surface of a sand basin in a sewage treatment facility is collected in a sand collection pit by jet water and transferred by a sand pump. Disturbing means for disturbing the sand accumulated near the suction port by injecting pressure water near the suction port of the sand pump provided in the sand collecting pit of the sand collecting pit, After stopping, let the pump installed in the pump well connected to the sand basin through the connecting part drain the accumulated water in the sand basin and the pump well, and the water level of the sand basin is set by the drainage by the pump When the level of the top of the section reaches the same level, the injection of pressure water by the disturbing means is started, and then the sand pump is operated, and the water level of the sand basin is below the level of the bottom of the central trough of the sand basin When the sand pump is lowered to the water level It is characterized by stopping the movement (claim 1).
The water level at which the operation of the sand pump is stopped may be a level at the end connected to the opening of the sand collecting pit at the bottom of the central trough of the sand basin (Claim 2).

According to the present invention, when the water level of the sand basin reaches the same level as the top of the continuous portion due to drainage, since the injection of pressure water by the disturbing means is started, the disturbed suspended sand does not move to the pump well. Since the suspended sand is not involved in the drainage pump, the life of the pump can be extended.
In addition, when the water level of the sand basin reaches the same level as the top of the continuous section due to drainage, the pressure water is jetted by the disturbing means to disturb the sand accumulated near the suction port of the sand pump. Subsequently, since the sand pump is operated, the sand is better disturbed and the sand is efficiently sucked into the suction port. Therefore, the sand pump can exhibit a high suction capability without the suction port being blocked by the sand in the sand collecting pit.
According to invention of Claim 2, the load of a sand-pumping pump can be suppressed and sanding can be performed efficiently.

1 shows a rainwater settling basin (hereinafter referred to as “sedimentation basin”) of a sewage treatment facility to which the sand lifting method of the present invention is applied, wherein (a) is a sectional view thereof, and (b) is a cross-sectional view of (a) FIG. FIG. 2 is a cross-sectional view taken along the line II in FIG. It is a flowchart which shows control operation. It is a schematic sectional drawing of a sand basin and a pump well. It is a top view of the left side part of FIG.

  In the settling basin 1, rainwater flows from one of the settling basins 1, and the rainwater settling and separating the sand is connected to the settling basin 1 from the other settling basin 1 as shown in FIG. 4. The pump well 30 is configured to flow out. Further explanation will be made with reference to the plan view of FIG. 1 (b). If rainwater flows in from the upper side of the paper of FIG. 1 (b), the rainwater that has settled and separated from the sand is taken from the lower side of the paper of FIG. 1 (b). It will be leaked.

  The form of the bottom surface 1a of the sand basin 1 is that sand collection (not shown) on the bottom surface 1a is gathered together in a sand collecting pit 2 having a flat bottom that is lower than the bottom surface 1a provided at a substantially central position of the bottom surface 1a. It is formed so that it can be. That is, as shown in FIG. 1A, the bottom surface 1a is inclined so that the central line in the rainwater inflow direction is the lowest, and as shown in FIG. The pit 2 is inclined so as to be the lowest. Therefore, when the water flows out from a sand collecting nozzle (not shown) on the bottom surface 1a, the sand settling on the bottom surface 1a is collected in the sand collecting pit 2 as indicated by an arrow in FIG. 1 (b).

  The sand pump 10 is a known submersible pump having spiral blades, and a pump that has been used as a submersible sludge pump in a sewage treatment facility can be used. The sand pump 10 is provided in the sand basin 1 via a discharge pipe 12 and a support 13 with the suction port 11 facing downward, that is, with the suction port 11 facing the bottom surface of the sand collecting pit 2.

  The disturbance nozzles 20a and 20b are disposed between the suction port 11 of the sand pump 10 and the bottom 2a of the sand collection pit 2 on the opposite sides of the suction port 11 to the sand flowing into the sand collection pit 2 from the central trough described later. It is installed at a position that does not obstruct the flow (see FIG. 1B). Further, the disturbance nozzles 20 a and 20 b are arranged so that the injection directions thereof are substantially opposed with the suction port 11 of the sand pump 10 as the center. Accordingly, since the jetting directions give vectors opposite to each other at positions opposite to each other on the circle centered on the center of the suction port 11, sand precipitated near the suction port by jetting from the disturbance nozzles 20a and 20b is good. It is disturbed and efficiently sucked into the suction port.

As shown in FIG. 4, the pump well 30 connected to the sand basin 1 is provided with a drain pump 31 and a stagnant water pump 32 separately. The sewage such as rainwater pumped up by the stagnant water pump 32 spouts pressure water so that the sand accumulated on the bottom surface 1a of the settling basin 1 flows out toward the sand collecting pit 2 via a switching valve (not shown). It is supplied to the sand collecting nozzles 40, 41, 42 to be caused.
Although not shown, they are provided in the sand pump 10, the pump (not shown) for supplying pressure water to the disturbance nozzles 20a and 20b, and the supply pipes 21a and 21b for supplying pressure water to the disturbance nozzles 20a and 20b, respectively. The valves and the like are configured to be driven and controlled by a controller (not shown) formed around a programmable controller that controls the sand basin 1 in an integrated manner.

  Based on FIG. 3, the procedure of sand collection and sand lifting will be described in detail.

  First, the gate 50 is closed to stop the inflow of sewage into the sand basin 1 (step 1. Hereinafter, the step is referred to as “S”). Next, the staying water pump 32 drains the wastewater to a sewage settling basin, an inflow trough, etc. (not shown) through the switching valve (S2).

  Since the settling basin 1 is connected to the pump well 30 via the continuous portion 60, if it is described with reference to FIG. 4, it is drained by the stagnant water pump 32 to the level L that is the top level of the continuous portion 60. However, the staying water below the level L of the sand basin 1 is not drained. In other words, in the present invention, the stagnant water pump 32 drains the stagnant water of the pump well 30 and the sand basin 1 to the level L (S2 to S4).

  As described above, when the inflow of rainwater into the sand basin 1 is stopped (S1) and the process of discharging the sediment deposited on the bottom surface of the sand basin 1 has arrived (S2 to S4), the supply pipes 21a and 21b The valves (not shown) provided in FIG. 1 are opened to start the injection of pressure water from the disturbance nozzles 20a and 20b, and the counting of the first timer T1 (not shown) is started (S5). After the time-up of the first timer T1, the sand pump 10 is driven and the counting of the second timer T2 is started (S6, S7).

  When pressure water is ejected from the disturbance nozzles 20a and 20b, the injection direction gives vectors opposite to each other at positions opposite to each other in a circle centered on the center of the suction port 11, so that the injection force from the disturbance nozzle is Since it is used effectively without being offset, the sand that has settled near the suction port is better disturbed. Sand accumulated in the vicinity of the suction port 11 is disturbed, and the disturbance gradually spreads throughout the sand collecting pit 2. Therefore, the sand is efficiently sucked from the suction port 11 by being accompanied by water and transferred to a predetermined place via the discharge pipe 12.

  After the time-up of the second timer T2, for example, the valves of the disturbance nozzles 20a and 20b are closed one minute after the start of the second timer T2. That is, the injection of pressure water is stopped (Y in S8, S9). Even if the disturbance nozzles 20a and 20b are closed and the water ejected from the disturbance nozzles 20a and 20b disappears, the sand is turned into the water to be sucked because the vicinity of the suction port 11 is fluidized by driving the sand pump 10. Accompanied with effective discharge.

  As described above, the injection of the pressure water from the disturbance nozzles 20a and 20b only needs to destroy and disturb the accumulated sand in the vicinity of the suction port 11 of the sand pump 10, so before the operation of the sand pump 10 is started. A short time from is enough. Therefore, it is not necessary to always continue the injection of the pressure water from the disturbance nozzles 20a and 20b during the operation of the sand pump 10, so that the operation cost can be reduced.

  When the sand discharge from the sand collection pit 2 is finished (Y in S10), that is, when a water level meter (not shown) provided in the sand collection pit 2 detects a predetermined lower limit water level, the sand pump 10 is driven. Stopped (S11).

  Following the stoppage of driving of the sand pump 10, the valves of the sand collecting nozzles 40, 41 and 42 are sequentially opened to collect sand. More specifically, the settling sand accumulated in the central trough 1b is guided into the sand collecting pit 2 and sprayed by the sand collecting nozzle 40 from which pressure fluid is ejected in the extending direction of the central trough 1b in order to clean the central trough 1b. . The central trough 1b is the final and main trough connected to the sand collecting pit 2, and is therefore intended to prevent burial due to sedimentation when rainwater is received.

  And thereafter, sand collecting nozzles 41, 41,... For ejecting pressure fluid in a direction orthogonal to the extending direction of the central trough 1b provided between the plurality of small troughs 1c orthogonal to the central trough 1b. By alternately ejecting the sand collecting nozzles 40, 40, sand collection to the sand collecting pit 2 is performed via the small trough 1c and the central trough 1b. The sand basin is appropriately divided into a plurality of areas depending on its size, and a plurality of sand collecting nozzles 41, 41... Corresponding to the areas are grouped together as a sand collecting nozzle group. Pressure water is ejected in order from the side closer to the sand collection pit 2.

Finally, sand accumulated in the pond width direction of the sand basin near the sand collection pit 2 is collected in the sand collection pit 2 by the sand collection nozzles 42, 42. When the water level meter in the sand collecting pit 2 detects a predetermined upper limit water level by sequentially opening the valves of the sand collecting nozzles 40, 41, 42, the driving of the sand pump 10 is resumed, and as the driving resumes, When the water level gauge detects a predetermined lower limit water level, the sand pump 10 is stopped. After the ejection from the sand collecting nozzles 42, 42, when the water level gauge detects a predetermined lower limit water level, the sand pump 10 is stopped driving and the state continues. Thereby, the sanding by the sand pump 10 is completed.
That is, the sand pump 10 detects the upper limit water level of the water level gauge according to the fluctuation of the water level in the sand collecting pit 2 from the start of driving (S10) to the stop of driving when the sanding is completed. Control is performed so that the drive is resumed and the drive is stopped when the lower limit water level is detected.

  In the above-described example, a known submersible pump having a spiral blade is shown as the sand pump 10, but it is needless to say that it may be a jet pump. Moreover, although the number of the disturbing nozzles in the sand collecting pit 2 is two, it may be three or more.

  In the above example, the disturbance nozzles 20a and 20b are provided with two timers T1 and T2 and driven before and after the sand pump 10 is driven. However, the timer is one and the sand pump 10 is driven. You may make it drive for the predetermined time before a start. However, as described above, when the disturbance nozzles 20a and 20b are driven before and after the sand pump 10 is driven, due to the synergistic effect of fluidization by the sand pump 10 and fluidization by the disturbance nozzles 20a and 20b. , Can further enhance the disturbing effect.

  In the state where the stagnant water below the level L of the sedimentation basin 1 is not drained by the drainage by the stagnant water pump 32, the transfer amount of the pumped water by the sandpump increases, which is uneconomical. It is necessary to perform sand collection by high pressure, in which pressure water from the sand collection nozzles 40, 41 and 42 is ejected at high pressure. Sand collection by high pressure not only requires a running cost to generate high pressure, but also increases the number of components. Moreover, when sand collection by high pressure is performed, a part of the sand sinks and floats in the water, and then sinks and accumulates again. Furthermore, the generation of sewage mist due to high-pressure water is also a big problem from a hygienic point of view. Therefore, in the present invention, in order to solve these problems, sand collection in a dry (drainage) state, that is, low-pressure sand collection in which pressure water from a sand collection nozzle is ejected at a low pressure is performed.

  Therefore, as described above, after the pressure water is jetted from the disturbance nozzles 20a and 20b to the sand that has settled near the suction port 11 of the sand pump 10 of the present invention and disturbed for a certain period of time, the sand pump 10 is operated. And let the accumulated water below level L drain. At this time, it is preferable to use water pumped up by the staying water pump 32 for the disturbance nozzles 20a and 20b. And if it drains to the predetermined water level in the sand collection pit 2, the operation of the sand pump 10 is stopped. Here, the predetermined water level is a water level that realizes a dry (drainage) state in the sand basin 1 and is ideally the level of the suction port 11. However, a slight amount of rainwater is allowed to remain within the range where high load or high pressure sand collection of the sand pump 10 is not required, and it extends through the sand collection pit 2 in the inflow-outflow direction of the sand basin 1. The bottom level of the central trough 1b may be used as the predetermined water level. Further, for example, the bottom level X (see FIGS. 1B and 4) of the opening end to the sand collecting pit 2 may be set to a predetermined water level.

1 rainwater settling basin (sedimentation basin)
DESCRIPTION OF SYMBOLS 2 Sand collection pit 2a Bottom 2b Sand collection pit sloping surface 3 Rotating axis of sand pump 10 Sand pump 11 Suction port 12 Discharge pipe 20a, 20b Disturbing nozzle 21a, 21b Supply pipe

Claims (2)

In the sand-carrying method, sand collected at the bottom of the sand basin of the sewage treatment facility is collected in a sand collection pit by jet water, and the sand is transferred by a sand pump.
Providing a disturbance means for disturbing sand accumulated near the suction port by injecting pressure water near the suction port of the sand pump provided in the sand collecting pit of the sand basin;
After stopping the inflow of sewage into the sand basin, let the pump provided in the pump well connected to the sand basin through the connecting part drain the accumulated water in the sand basin and the pump well,
When the water level of the sedimentation basin becomes the same level as the top of the continuous portion by drainage by the pump, the injection of pressure water by the disturbing means is started,
Subsequently, the sand pump is operated, and the operation of the sand pump is stopped when the water level of the sand basin falls to a level below the level of the bottom of the central trough of the sand basin.
A sanding method characterized by that.   2. The sand pumping method according to claim 1, wherein the water level at which the operation of the sand pump is stopped is at a level at the end connected to the opening of the sand collecting pit at the bottom of the central trough of the sand basin.

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