Solid-liquid separation system

Abstract

To provide a solid-liquid separation system having cost reduced.SOLUTION: This solid-liquid separation system comprises: a screen member 13 that is provided on the upstream side of a sedimentation region 2 and that blocks passage of a solid larger than a scale space among solids contained in a received liquid; grooves 21 and 25 extending toward an accumulation part 4 on a bottom 1a and opened upward; space forming members 3 and 35 provided along the grooves 21 and 25, forming spaces 3S and 35S closed at the upper ends, and provided with suction ports 31 separated from the bottoms of the grooves 21 and 25 below the upper ends; an outlet 711 through which fluids in the spaces 3S and 35S are discharged downstream in a transfer direction of the solid; and a vortex pump 5 that sucks the solid transferred to the accumulation part 4 together with the liquid from a suction port 52a by driving an impeller 522 housed in a casing 52. THe vortex pump 5 has a distance 52h between the suction port 52a and the impeller 522 set to be the scale space or more and 1.5 times the scale space or lower.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a solid-liquid separation system that causes solids contained in the received liquid to settle to the bottom in a settling region, transfers the settled solids to an accumulation section, and removes the solids from the accumulation section.

Background Art

[0002] Whether it is a grit chamber or a sedimentation tank provided in a sewage treatment facility, it is one of the solid-liquid separation systems that separates solids contained in a liquid from the liquid. The grit chamber receives sewage such as sewage or rainwater, causes the sand contained in the sewage to settle to the bottom of the tank, transfers the settled sand to a sand collection pit, and removes the sand collected in the sand collection pit by a sand lifting pump. Further, the sedimentation tank receives the water from which sand has been removed in the grit chamber, causes the sludge contained in the received water to settle to the bottom of the tank, transfers the settled sludge to a sludge pit, and removes the sludge collected in the sludge pit by a sludge pump. Furthermore, various solid-liquid separation systems are also used outside sewage treatment facilities. For example, there are modes in which metal powder or the like contained in industrial wastewater is transferred to a predetermined accumulation section and the collected metal powder is removed by a pump or the like, and modes in which sediment or the like that has flowed into a reservoir such as a dam lake is transferred to a predetermined accumulation section and the collected sediment or the like is removed by a pump or the like. There are various types of solids separated from a liquid by a solid-liquid separation system, such as sand and sludge contained in sewage or the like, metal powder contained in industrial wastewater, or sediment that flows into a reservoir together with water.

[0003] Regarding the solid-liquid separation system, the applicant of the present application has hitherto proposed a number of systems including a space forming member provided along a groove opening upward and forming a space with its upper end portion closed and a draw-in port provided below the upper end portion thereof, and a discharge port for discharging a fluid in the space toward the downstream side in the transfer direction of the solid (for example, Patent Document 1, etc.).

[0004] In the solid-liquid separation system proposed by the applicant of the present application so far, the settled solids can be transferred very well, the number of actual achievements has increased, and the reliability has also been improved.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the next problem is to reduce the cost of the system.

[0007] In view of the above circumstances, an object of the present invention is to provide a solid-liquid separation system in which cost reduction is achieved.

Means for Solving the Problems

[0008] The solid-liquid separation system of the present invention for solving the above object is a solid-liquid separation system that settles solids contained in the received liquid to the bottom in a settling region, transfers the settled solids to an accumulation part, and removes the solids from the accumulation part, a screen member provided upstream of the settling region to block the passage of solids larger than the mesh width among the solids contained in the received liquid; a groove extending toward the accumulation part at the bottom and opening upward; a space forming member provided along the groove, forming a space with the upper end portion closed and having a draw-in port spaced from the bottom of the groove below the upper end portion; a discharge port that discharges fluid in the space toward the downstream side in the transfer direction of the solids; and a vortex pump that sucks the solids transferred to the accumulation part together with the liquid from a suction port by driving an impeller housed in a casing. The vortex pump is characterized in that the distance between the suction port and the impeller is equal to or greater than the mesh width and equal to or less than 1.5 times the mesh width.

[0009] Previously, a submersible pump has been used as a removing means for removing the solid from the accumulating portion, but no particular ingenuity has been made in the structure of the pump itself. In the solid-liquid separation system of the present invention, by using a vortex pump and ensuring a distance between the suction port and the impeller that is equal to or greater than the mesh width, it becomes possible to suck in the solid that has passed through the screen member. On the other hand, the longer the distance, the larger the pump becomes, leading to an increase in cost. The vortex pump sucks in the liquid together with the solid, and even if the distance is increased, as long as the magnitude of the driving force for rotating the impeller is the same, the amount of solid sucked in does not increase, but only the amount of liquid sucked in increases, which is meaningless for solid removal. However, since long and slender rod-shaped solids may pass through the screen member, it is preferable to ensure a length of 1.5 times.

[0010] Also, The vortex pump has a conveying pipe connected to the space between the suction port and the impeller, The conveying pipe may be characterized in that it is a pipe having an inner diameter equal to the length of the distance.

[0011] That is, in the vortex pump, the impeller is retracted and arranged on the side opposite to the side where the suction port is provided (upper side), a space with the distance as the height is secured, and the conveying pipe extends from that space without being constricted. By structuring the vortex pump in such a manner, the pump can be miniaturized and cost reduction can be achieved.

[0012] Also, The inlet is located within the groove, The space forming member is arranged at least partially within the groove, When the opening width in the lateral direction perpendicular to the transfer direction of the inlet is L1, and the shortest distance between the outer peripheral surface of the space forming member and the inner peripheral surface of the groove is L2, 1.1 ≧ L1 / L2 ≧ 1.0 It may be characterized in that they are in the relationship of.

[0013] When the solid that is slightly shorter than the length of the shortest distance (L2) enters between the outer peripheral surface of the space forming member and the inner peripheral surface of the groove, if the opening width (L1) of the inlet is less than the shortest distance (L2), the solid may not be sucked in from the inlet. On the other hand, if the opening width (L1) is made too large, not only will it be difficult to suck in the solid from the inlet, but also on the downstream side away from the discharge port, the solid that has moved will easily come out of the inlet, so it is necessary to keep it at 1.1 or less.

Advantages of the Invention

[0014] According to the solid-liquid separation system of the present invention, a solid-liquid separation system with cost reduction can be provided.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The solid-liquid separation system of the present invention can be adopted in a grit chamber or a sedimentation tank in a sewage treatment facility, or a device for removing metal powder or the like contained in factory wastewater, and further, a device for removing sediment or the like that has flowed into a reservoir such as a dam lake. In the present embodiment, an example in which the present invention is adopted in a grit chamber will be described. This grit chamber is arranged on the upstream side of the sewage treatment facility, and after sedimenting the sand contained in sewage such as sewage or rainwater, the sedimented sand is moved to a grit sump and removed from the sewage.

[0017] FIG. 1 is a plan view of a grit chamber provided with the solid-liquid separation system of the present embodiment as viewed from above, and FIG. 2 is a cross-sectional view taken along line A-A of the grit chamber shown in FIG. 1.

[0018] The solid-liquid separation system 1 of the present embodiment includes a dust collector 10, an outer trough 21 and an auxiliary outer trough 25, an inner trough 3 and an auxiliary inner trough 35, a discharge member 71, and a sand-lifting pump 5. Further, among the solid-liquid separation system 1 of the present embodiment, the outer trough 21 and the auxiliary outer trough 25, the inner trough 3 and the auxiliary inner trough 35, and the discharge member 71 constitute a transfer system.

[0019] The grit chamber G is a rectangular pool in plan view provided with an upstream sedimentation region 2a, a grit sump 4, a downstream sedimentation region 2b, and a pump well 6 from the left side to the right side of the figure as shown in FIG. 1. Note that when it is not necessary to distinguish between the upstream sedimentation region 2a and the downstream sedimentation region 2b, they may be collectively referred to as the sedimentation region 2.

[0020] The dust remover 10 is for removing stones, slag, etc. with a size equal to or larger than a predetermined size among the solids mixed in the sewage flowing into the sedimentation pond G, and is installed on the upstream side of the sedimentation area 2. The dust remover 10 has an endless chain 11, a plurality of rakes 12 attached to the endless chain 11 at intervals, and a filtration screen 13 submerged in water. The endless chain 11 is provided in a state of standing obliquely on both sides in the width direction of the sedimentation pond G, and as shown in FIG. 2, it is wound around a ground-side sprocket 111 and a bottom-side sprocket 112 of the pond. When the endless chain 11 is driven, the rake 12 enters and exits the water. The filtration screen 13 is arranged on the downstream side of the endless chain 11. This filtration screen 13 has bars extending in the vertical direction arranged at a predetermined interval (for example, 25 mm to 75 mm), and blocks the passage of solids with a size larger than the predetermined interval. In this embodiment, the bars extending in the vertical direction are arranged at intervals of 75 mm. That is, the mesh width of the filtration screen 13 is 75 mm. This filtration screen 13 corresponds to an example of a screen member. The solids blocked by the filtration screen 13 are scraped up by the rake 12, and the scraped-up solids are placed on conveying means such as a belt conveyor (not shown) on the ground side.

[0021] As shown in FIGS. 1 and 2, a sand-lifting pump 5 is arranged in the sand collection pit 4, and a discharge water pump 61 and a water-lifting pump 62 are arranged in the pump well 6. Note that the discharge water pump 61 is provided at a predetermined height (for example, a height of about 1 m) from the bottom of the pump well 6, and a device is provided to suppress the suction of impurities and the like that tend to accumulate at the bottom of the pump well 6. Hereinafter, the long side direction of the sedimentation pond G may be referred to as the longitudinal direction, and the short side direction may be referred to as the pond width direction. The sedimentation pond G shown in FIGS. 1 and 2 receives sewage from the left side of the figure, and the received sewage slowly flows toward the pump well 6 on the right side of the figure (see the white arrows shown in FIGS. 1 and 2). In FIGS. 1 and 2, the left side of the figure is the upstream side and the right side is the downstream side.

[0022] The solids mixed in the sewage flowing into the grit chamber G contain sand. GW shown in Fig. 2 represents the water surface of the sewage. The sand contained in the sewage settles to the bottom Ga of the chamber and the grit pit 4 while the sewage slowly flows towards the pump well 6. The sewage passing through the downstream sedimentation region 2b flows into the pump well 6 and is discharged by the pumping pump 62 installed in the pump well 6.

[0023] The sand settled at the bottom Ga of the chamber moves to the grit pit 4 by the water discharged from the discharge member 71 described in detail later. As a result, the sand in the sewage flowing into the grit chamber G is collected in the grit pit 4. Specifically, in the upstream sedimentation region 2a, the direction from the upstream towards the grit pit 4 (see the thin right arrow shown in Figs. 1 and 2) is the moving direction of the sand, and in the downstream sedimentation region 2b, the direction from the downstream towards the grit pit 4 (see the thin left arrow shown in Figs. 1 and 2) is the moving direction of the sand. Therefore, in the upstream sedimentation region 2a, the flowing-down direction (the white arrow in the figure) and the moving direction (the thin arrow in the figure) coincide, but in the downstream sedimentation region 2b, the flowing-down direction (the white arrow in the figure) and the moving direction (the thin arrow in the figure) are opposite.

[0024] As shown in Fig. 1, two outer troughs 21, 21 extending in the longitudinal direction and arranged in the tank width direction are provided at the bottom Ga of the upstream sedimentation region 2a, and two outer troughs 21, 21 extending in the longitudinal direction and arranged in the tank width direction are also provided at the bottom Ga of the downstream sedimentation region 2b. As will be described later, the outer trough 21 corresponds to a part of the groove in the present invention. Among the four outer troughs 21, in the following description, the outer trough 21 provided at the bottom Ga of the upstream sedimentation region 2a is referred to as the upstream outer trough 21a, and the outer trough 21 provided at the bottom Ga of the downstream sedimentation region 2b may be referred to as the downstream outer trough 21b for distinction. In the present embodiment, the total length of each of these outer troughs 21 is set to about 10 m. At the bottom Ga of the tank, a pair of inclined surfaces 22, 22 inclined downward from both sides in the tank width direction toward each of the outer troughs 21 are provided. Also, the portion connecting the outer trough 21 and the outer trough 21 in the tank width direction is also composed of the inclined surface 22. In the present embodiment, the inclined surface 22 is formed by placing concrete. The length in the tank width direction of a single sedimentation region composed of one outer trough 21 and the inclined surfaces 22 on both sides thereof is 3.0 m or less. Also, the inclination angle of the inclined surface 22 is 20 degrees or more and 30 degrees or less. If it is less than 20 degrees, it becomes difficult for sand to enter the outer trough 21, and if it exceeds 30 degrees, it becomes difficult to walk on the inclined surface 22 during maintenance.

[0025] As shown in Fig. 1, a discharge member 71 is provided in each of the plurality of outer troughs 21. These discharge members 71 are connected to the discharge water pump 61 by a water supply pipe (not shown), and the water in the pump well 6 supplied from the discharge water pump 61 is discharged from the discharge port 711. The downstream sides of the upstream outer troughs 21a, 21a are connected to the sand collection pit 4, and the upstream sides of the downstream outer troughs 21b, 21b are also connected to the sand collection pit 4. An inner trough 3 is provided in the outer trough 21. As will be described later, the inner trough 3 corresponds to a part of the space forming member in the present invention.

[0026] As shown in Fig. 1, the sand collecting pit 4 has a flat surface portion 41 provided at the central portion in the pond width direction, and a pair of inclined surface portions 42, 42 provided on both sides in the pond width direction of the flat surface portion 41, respectively. The flat surface portion 41 is constituted by a flat surface having a rectangular shape in plan view, and a sand lifting pump 5 is installed at the central portion of the flat surface portion 41. The sand lifting pump 5 is provided with a suction port 52a (see Fig. 2), which will be described in detail later. The sand lifting pump 5 sucks the sand collected in the sand collecting pit 4 from the suction port 52a, and discharges the sucked sand into the sand lifting pipe 81 and sends it to the sand separation device 9 shown in Fig. 2.

[0027] In the sand collecting pit 4, the inclined surface portion 42 is constituted by an inclined surface inclined downward toward the flat surface portion 41. As a result, the sand sedimented on the inclined surface portion 42 travels along the inclined surface portion 42 toward the sand lifting pump 5 installed on the flat surface portion 41. Also, as shown in Fig. 1, a pair of pit sand collecting nozzles 72, 72 are provided inside the sand collecting pit 4 along the respective inclined surface portions 42, 42. Each of the pit sand collecting nozzles 72 has two discharge ports 721 arranged at intervals in the longitudinal direction. The pit sand collecting nozzles 72 are also connected to the water discharge pump 61 by a water supply pipe (not shown), and the water in the pump well 6 is discharged from the discharge ports 721 toward the sand lifting pump 5 arranged at the center in the width direction of the sand collecting pit 4. Thus, the sand collected in the sand collecting pit 4 is collected around the sand lifting pump 5.

[0028] Also, as shown in Fig. 1, a pair of stirring nozzles 73, 73 are further provided inside the sand collecting pit 4. The stirring nozzles 73 are also connected to the water discharge pump 61 by a water supply pipe (not shown), and have two discharge ports 731. That is, the discharge ports 731 of the stirring nozzles 73 are arranged at four positions. The suction port 52a (see Fig. 2) of the sand lifting pump 5 is circular, and the discharge ports 731 of the stirring nozzles 73 discharge water from four directions tangential to the circular suction port 52a, thereby disturbing the sand and preventing the suction port 52a from being blocked, and preventing the lock at the start of the pump due to so-called sand biting or the like. In Fig. 2, the pit sand collecting nozzles 72 and the stirring nozzles 73 are omitted for simplicity of the drawing.

[0029] Figure 3 is a cross-sectional view taken along line B-B of the grit chamber G shown in Figure 2. In this Figure 3, it shows the state of looking at the downstream sedimentation region 2b from inside the grit pit 4. The left-right direction in the figure is the direction of the tank width, and the direction from the front side of the paper surface to the back side of the paper surface is the direction of the sewage flow. Note that in Figure 3, similar to Figure 2, the pit grit nozzles 72 and the agitation nozzles 73 are omitted. First, the configuration of the sedimentation region 2 will be described. Since the upstream sedimentation region 2a and the downstream sedimentation region 2b are symmetrically configured with the grit pit 4 in between, here, the downstream sedimentation region 2b will be taken as an example for explanation.

[0030] As shown in Figure 3, each of the downstream outer troughs 21b has a pair of upper edges 211, 211 that define an opening, and inclined surfaces 22 extending obliquely upward from each of these pair of upper edges 211, 211 are provided. The sand sedimented in the downstream sedimentation region 2b flows down along the inclined surfaces 22 and enters the downstream outer trough 21b through the opening 210 defined by the pair of upper edges 211, 211. The downstream outer trough 21b of the present embodiment has a shape in which approximately the upper 1 / 3 of a stainless steel cylindrical body is cut out over the entire extension direction and is open upward. Also, a space 21S defined by the inner peripheral surface is formed in the downstream outer trough 21b. The inner trough 3 partitions the space 21S in the downstream outer trough 21b and forms a space with the part above the lower end closed. Also, the inner trough 3 of the present embodiment has a shape in which approximately the lower 1 / 6 of a stainless steel cylindrical body is cut out over the entire extension direction and is open downward. Hereinafter, this open part will be referred to as the inlet 31. The inner trough 3 is supported by the downstream outer trough 21b by support members (not shown) at each of its longitudinal ends.

[0031] The discharge member 71 has a water supply pipe 70 connected to its rear end portion and a discharge port 711 provided at its front end portion. When the water stored in the pump well 6 shown in FIGS. 1 and 2 is supplied to the discharge member 71 by the discharge water pump 61, the water supplied to the discharge member 71 is discharged from the discharge port 711. When water is discharged from the discharge port 711 of the discharge member 71 into the inner trough 3, the sand deposited in the outer trough 21 (space 21S) is drawn into the inner trough 3 from the inlet 31 as shown by the curved arrow in FIG. 3. Further, in the inner trough 3, the drawn sand moves toward the sand collection pit 4 by the flow of the water discharged from the discharge port 711 and is eventually collected in the sand collection pit 4. These phenomena are considered to be the phenomena in which the sand is drawn in due to the viscosity of the discharged water and the sand moves together with the water.

[0032] Next, with reference to FIG. 4, the discharge member 71 and the surrounding configuration in which the discharge member 71 is arranged will be described. In the description here, the configuration provided at the bottom Ga of the upstream sedimentation region 2a will be described as an example, but the configuration provided at the bottom Ga of the downstream sedimentation region 2b is the same.

[0033] FIG. 4(a) is a C-C cross-sectional view of the grit chamber G shown in FIG. 2. FIG. 4(b) is a D-D cross-sectional view of FIG. 4(a). In FIG. 4(a), the left-right direction of the figure is the width direction, and the direction from the back side to the front side of the figure is the transfer direction. Note that the width direction is the lateral direction orthogonal to the transfer direction. Also, in FIG. 4(b), the right direction of the figure is the transfer direction.

[0034] As shown in Fig. 4(a), a water supply pipe 70 is connected to the rear end portion of the discharge member 71, and the tip portion thereof forms a discharge port 711. The water supplied from the water supply pipe 70 to the discharge member 71 is discharged from the discharge port 711 in the transfer direction. In the present embodiment, the discharge flow rate of the water discharged from the discharge port 711 is set to 8 m / sec or more, and the discharge pressure is set to 0.05 MPa or more and 0.3 MPa or less. Further, in the present embodiment where the total length of the outer trough 21 is set to about 10 m, the flow rate of the water discharged from the discharge port 711 is adjusted to about 2000 liters per minute. Here, when the total length of the outer trough 21 is set to about 5 m, the flow rate of the water discharged from the discharge port 711 is adjusted to about 1500 liters per minute. Thus, the flow rate of the water discharged from the discharge port 711 may be appropriately adjusted according to the total length of the outer trough 21 and the like.

[0035] Note that, from one discharge port 731 of the agitation nozzle 73 disposed in the sand collecting pit 4, water is discharged at a significantly lower flow rate than from the discharge port 711 of the discharge member 71. For example, the flow rate of the water discharged from one discharge port of the agitation nozzle 73 is about 200 liters per minute.

[0036] Also, as shown in FIGS. 4(a) and 4(b), an auxiliary outer trough 25, an auxiliary inner trough 35, and a support plate 36 are provided in the region where the discharge member 71 is disposed. The auxiliary outer trough 25 has the same cross-sectional shape in the width direction as the outer trough 21 and is open upward, but is significantly shorter in the transfer direction than the outer trough 21 (see FIGS. 1 and 2). The combination of the outer trough 21 and the auxiliary outer trough 25 corresponds to an example of the groove in the present invention. Further, the auxiliary inner trough 35 also has the same cross-sectional shape in the width direction as the inner trough 3. That is, the auxiliary inner trough 35 also has a shape in which approximately the lower 1 / 6 is cut out and has an inlet 350 that opens downward. The inlet 350 of the auxiliary inner trough 35 is connected to the inlet 31 of the inner trough 3 and forms a continuous opening. The auxiliary inner trough 35 is significantly shorter in the transfer direction than the inner trough 3 (see FIGS. 1 and 2), and is further about half the length in the transfer direction compared to the auxiliary outer trough 25. The combination of the inner trough 3 and the auxiliary inner trough 35 corresponds to an example of the space forming member in the present invention. The auxiliary outer trough 25 and the auxiliary inner trough 35 are fixed to the upstream side in the transfer direction of the support plate 36 by a fastening member 360 composed of a bolt and a nut. Note that the outer trough 21 and the inner trough 3 are fixed to the downstream side in the transfer direction of the support plate 36 by welding.

[0037] The discharge member 71 is configured by connecting two L-shaped pipes 712, 713, a linear pipe 714, and a nozzle portion 715. The two L-shaped pipes 712, 713 and the linear pipe 714 correspond to an example of a fluid supply pipe. The nozzle portion 715 is formed by flattening a round pipe, and a discharge port 711 is formed at its tip. By adopting such a mode of forming the nozzle portion 715 by flattening a round pipe, its production becomes easy. Note that the linear pipe 714 is provided with mounting pieces 7141, 7141 extending outward in the width direction, respectively.

[0038] FIG. 4(a) shows the opening width L1 in the width direction (lateral direction) of the inlet 31 of the inner trough 3, and also shows the shortest distance L2 between the outer peripheral surface of the inner trough 3 and the inner peripheral surface of the outer trough 21. The shortest distance L2 referred to here is the shortest distance on a plane orthogonal to the transfer direction. When both the inner trough 3 and the outer trough 21 are arc-shaped, it is the radial length. The relationship between the opening width L1 of the inlet 31 and the shortest distance L2 between the outer peripheral surface of the inner trough 3 and the inner peripheral surface of the outer trough 21 is in the relationship of 1.1≧L1 / L2≧1.0. It is possible that contaminants slightly shorter than the length of the shortest distance L2 may enter between the outer peripheral surface of the inner trough 3 and the inner peripheral surface of the outer trough 21. In this case, if the opening width L1 of the inlet 31 is less than the shortest distance L2, it may not be possible to draw in the contaminants from the inlet 31. On the other hand, if the opening width L1 of the inlet 31 is made too large, not only is it difficult to draw in sand from the inlet 31, but also on the downstream side away from the discharge port 711, the sand that has moved is likely to come out from the inlet 31. Therefore, the opening width L1 of the inlet 31 should be kept to a certain extent, and it is necessary to make L1 / L2 a value of 1.1 or less. Further, FIG. 4(a) also shows the opening width L3 of the discharge port 711. The opening width L3 of this discharge port 711 is equal to or greater than the opening width L1 of the inlet 31 (L3≧L1) in order to ensure a sufficient discharge volume.

[0039] Also, when the cross-sectional area of the inner trough 3 with a shape obtained by cutting out approximately the lower 1 / 6 in the extending direction of the cylindrical body over the entire extending direction is 3C, and the cross-sectional area of the outer trough 21 with a shape obtained by cutting out approximately the upper 1 / 3 in the extending direction of the cylindrical body over the entire extending direction is 21C, the cross-sectional area ratio such as "3C:21C" is preferably 1:2.5 or more and 1:8 or less. First, determine the shortest distance L2 between the outer peripheral surface of the inner trough 3 and the inner peripheral surface of the outer trough 21, and the mesh width L4 of the filter screen 13 in the dust collector 10 shown in FIGS. 1 and 2 may be made the same as the shortest distance L2. In this case, the diameters of the inner trough 3 and the outer trough 21 can be given degrees of freedom. However, if the outer trough 21 is too small with respect to the inner trough 3 (the shortest distance L2 is too short, and less than 1:2.5 in terms of the cross-sectional area ratio), sand cannot be sufficiently stored inside the outer trough 21, and the amount of sand drawn from the inlet 31 of the inner trough 3 will decrease. On the other hand, if the outer trough 21 is too large with respect to the inner trough 3 (the shortest distance L2 is too long, and more than 1:8 in terms of the cross-sectional area ratio), the distance between the inner peripheral surface of the outer trough 21 and the inlet 31 of the inner trough 3 will be too far, and it is likely to cause a situation where it becomes difficult to draw sand from the inlet 31.

[0040] Also, when the above cross-sectional area ratio is 1:2.5 or more and 1:8 or less, if the discharge water pump 61 is suppressed to an inexpensive size, the discharge amount from the discharge port 711 is 1.0 m 3 / min or more and 3.0 m 3 / min or less, and the average flow velocity in the inner trough 3 is preferably 0.9 m / s or more and 2.8 m / s or less.

[0041] The auxiliary outer trough 25 is fixed to the support plate 36 by four fastening members 360 in the present embodiment in a state where its flange portion 251 is joined to the surface on the downstream side in the transfer direction of the support plate 36. Further, the auxiliary inner trough 35 is fixed to the support plate 36 by five fastening members 360 in the present embodiment in a state where its flange portion 351 is joined to the surface on the downstream side in the transfer direction of the support plate 36. By these means, a measure is taken so that no gap is inadvertently formed between the auxiliary outer trough 25 and the auxiliary inner trough 35 and the support plate 36. Furthermore, as described above, the outer trough 21 is fixed to the surface on the upstream side in the transfer direction of the support plate 36, and the auxiliary outer trough 25 and the outer trough 21 are connected in a state of being continuous in the transfer direction with the support plate 36 interposed therebetween. Also, the inner trough 3 is fixed to the surface on the upstream side in the transfer direction of the support plate 36, and the auxiliary inner trough 35 and the inner trough 3 are also connected in a state of being continuous in the transfer direction with the support plate 36 interposed therebetween.

[0042] The discharge member 71 is fixed to the auxiliary outer trough 25 by a fastening member 7142 in a state where the placement piece 7141 is placed on the support piece 252 of the auxiliary outer trough 25. As a result, as shown in Fig. 4(b), the discharge port 711 is arranged at a position where it enters the auxiliary inner trough 35, and in the present embodiment, as shown by the solid arrow, the discharge member 71 is supported in a posture in which water is discharged substantially horizontally in the transfer direction from the discharge port 711. If the auxiliary inner trough 35 is removed from the support plate 36 and the discharge member 71 is removed from the auxiliary outer trough 25 and the water supply pipe 70, the discharge port 711 that has entered the auxiliary inner trough 35 can be taken out from the state of having entered the auxiliary inner trough 35. Thereby, for example, maintenance such as removing contaminants that have clogged the discharge port 711 can be performed.

[0043] As shown in Fig. 4(a), the support plate 36 is a plate material having a rectangular lower part and a trapezoidal upper part in terms of outer shape. In the figure, the part 36a embedded in the placed concrete is indicated by cross-hatching. Further, in the support plate 36, in the region where the space 35S in the auxiliary inner trough 35 (see Fig. 4(b)) and the space 3S in the inner trough 3 are continuous among the space 25S in the auxiliary outer trough 25 (see Fig. 4(b)) and the space 21S in the outer trough 21, a first opening 361 is formed, and further, a second opening 362 is formed in a donut shape of about 1 / 3 in the lower part. Thereby, among the space 21S in the outer trough 21 and the space 25S in the auxiliary outer trough 25, the parts other than the first opening 361 and the second opening 362 are partitioned in the transfer direction by the support plate 36. This partitioned part is indicated by hatching with a large interval in the figure, and may be hereinafter referred to as a first partition part 36b. The auxiliary inner trough 35 is supported by the support plate 36 by fixing the auxiliary inner trough 35 to the upstream side surface in the transfer direction of the first partition part 36b with a fastening member 360. Further, the inner trough 3 is supported by the support plate 36 by fixing the inner trough 3 to the downstream side surface in the transfer direction of the first partition part 36b by welding. The support plate 36 is a plate material having a thickness of about 3 mm provided along a direction (vertical direction in this embodiment) intersecting the extending direction of the inner trough 3, and the length in the thickness direction is shorter than the length in the direction (height direction) orthogonal to the thickness direction. Thereby, on the support plate 36, it is difficult for contaminants such as sand to accumulate, and it is difficult for string-shaped contaminants to wrap around.

[0044] The support plate 36 is arranged at a position close to the discharge port 711 in the transfer direction, and the water discharged from the discharge port 711 passes through the first opening 361 of the support plate 36 in a strong state. In this embodiment, emphasis is placed on the support of the inner trough 3 and the auxiliary inner trough 35, and the second opening 362 of the support plate 36 is formed as a donut-shaped opening of about 1 / 3, and an aspect is adopted to sufficiently secure a portion for fixing the inner trough 3 and the auxiliary inner trough 35.

[0045] Further, the first partition portion 36b has a portion located above the inner trough 3 and the auxiliary inner trough 35. Hereinafter, a portion of the first partition portion 36b that is located above the inner trough 3 and the auxiliary inner trough 35 may be referred to as a partition portion 36b1. In Fig. 4(a), the partition portion 36b1 is distinguished from other portions by using a dashed-dotted line.

[0046] Furthermore, a closing plate 352 is provided at the upstream edge in the transfer direction of the auxiliary inner trough 35. In FIG. 4, this closing plate 352 is shown in gray. As shown in FIG. 4(b), the nozzle portion 715 is located within the space 35S in the auxiliary inner trough 35, and the discharge port 711 is also located within that space 35S. More specifically, the discharge port 711 is arranged at the central position of the space 35S in the auxiliary inner trough 35 such that the center 711a of the discharge port 711 (see FIG. 4(a)) coincides. The closing plate 352 closes the portion above the discharge port 711. The closing plate 352 shown in FIG. 4 closes the portion above the center 711a of the discharge port 711 and closes all of the upper half portion of the space 35S in the auxiliary inner trough 35 except for the linear pipe 714. The thick dotted arrow shown in FIG. 4(b) indicates how the sand deposited on the bottom of the pond Ga is drawn into the space 35S in the auxiliary inner trough 35 and the space 3S of the inner trough 3 due to the viscosity of the water discharged from the discharge port 711. Also, the thick dashed arrow indicates how, if the closing plate 352 were not provided, the sewage upstream of the auxiliary inner trough 35 would be drawn into the space 35S of the auxiliary inner trough 35 due to the viscosity of the water discharged from the discharge port 711, virtually showing the situation. At the portion that is open at the upstream end face of the auxiliary inner trough 35, sewage flows into the space 35S from the upstream side of the auxiliary inner trough 35. In the inflow of sewage from the upstream side, the amount of liquid moving is overwhelmingly larger than that of solids. For the amount of sewage flowing in, the amount of sand drawn in as indicated by the thick dotted arrow decreases, leading to a transfer loss of the sedimented sand. Enlarging the discharge water pump 61 to suppress the transfer loss of the sedimented sand causes a cost increase. In this embodiment, by providing the closing plate 352, the occurrence of sewage flowing in from the upstream side can be prevented, the amount of sand drawn in as indicated by the thick dotted arrow can be ensured without enlarging the discharge water pump 61, and as a result, cost reduction is achieved.

[0047] FIG. 5 is a diagram showing a modified example of the closing plate. In this FIG. 5, components having the same names as the components described so far are denoted by the same reference numerals as those used so far for explanation.

[0048] The closing plate 352 shown in FIG. 4 was provided at the upstream edge of the auxiliary inner trough 35, but the closing plate 352 may be provided at any position between the upstream edge of the auxiliary inner trough 35 and the discharge port 711.

[0049] FIG. 5(a) is a view showing the downstream end side to the upstream side of the auxiliary inner trough 35, the horizontal direction of the figure is the width direction, and the direction from the back side to the front side of the figure is the transfer direction. Further, FIG. 5(b) is a cross-sectional view taken along the line E-E of FIG. 5(a), and the right direction of the figure is the transfer direction. The closing plate 352 shown in FIG. 5(b) is provided at the position of the discharge port 711. As shown in FIG. 5(a), this closing plate 352 closes all of the upper half portion of the space 35S in the auxiliary inner trough 35 except for the discharge port 711.

[0050] FIG. 5(c) is also a view showing the downstream end side to the upstream side of the auxiliary inner trough 35, the same as FIG. 5(a), the horizontal direction of the figure is the width direction, and the direction from the back side to the front side of the figure is the transfer direction. Further, FIG. 5(d) is a cross-sectional view taken along the line F-F of FIG. 5(c), and the right direction of the figure is the transfer direction. The closing plate 352 shown in FIG. 5(c) is provided at the connection position of the linear pipe 714 and the nozzle portion 715 and is fixed to the upstream end of the inner peripheral surface of the auxiliary inner trough 35. As shown in FIG. 5(d), this closing plate 352 closes only the upper portion above the linear pipe 714 in the upper half portion of the space 35S in the auxiliary inner trough 35.

[0051] In addition, when the auxiliary inner trough 35 is not provided, the discharge port 711 is located at the upstream end portion of the inner trough 3. In this case, the closing plate 352 may be provided at any position between the upstream edge of the inner trough 3 and the discharge port 711.

[0052] Even when the modified example shown in FIG. 5 or the auxiliary inner trough 35 is not provided, by providing the closing plate 352, it is possible to prevent the inflow of sewage into the space 35S from the upstream side of the auxiliary inner trough 35, and without increasing the size of the discharge water pump 61, it is possible to secure the amount of sand drawn into the space 35S. As a result, cost reduction is achieved here as well.

[0053] Note that the portion below the closing plate 352 functions as an opening for drawing in sand. However, even if a part or all of this lower portion is blocked, the upstream end of the inlet 31 functions and it is possible to draw in sand.

[0054] The descriptions so far are summarized and appended below.

[0055] (Appendix 1) A transfer system that sinks the solids contained in the received liquid to the bottom and transfers the settled solids to the accumulation part, a groove extending toward the accumulation part at the bottom and opening upward, a space forming member provided along the groove, forming a space with the upper end portion closed, and having an inlet spaced from the bottom of the groove below the upper end portion, a discharge port disposed at the upstream end in the transfer direction of the solid in the space, discharging the fluid toward the downstream side in the transfer direction, and a closing member disposed at the position of the discharge port or at a position upstream of the discharge port in the transfer direction, closing at least a predetermined portion of the space above the discharge port. The transfer system is characterized by this.

[0056] Note that the inlet may be located in the groove or outside the groove. Also, the predetermined portion may be the entire portion or a part of the portion of the space above the discharge port.

[0057] (Appendix 2) It is provided with a fluid supply pipe that leads to the discharge port through the space from the upstream side in the transfer direction. The transfer system according to appended claim 1, wherein the closing member closes at least an upper portion of the space above the fluid supply pipe.

[0058] (Appended claim 3) The discharge port is arranged at the central portion of the space. The transfer system according to appended claim 2, wherein the closing member closes the entire portion of the upper half portion of the space excluding the fluid supply pipe.

[0059] Note that an opening through which the solid sedimented on the bottom passes may be formed in the portion of the space below the closing member, or this lower portion may also be closed.

[0060] Next, the sand-lifting pump 5 will be described in detail. As shown in Fig. 3, the sand-lifting pump 5 is fixed to a pump fixing mechanism 82 provided in the sand collecting pit 4. The pump fixing mechanism 82 has a support portion 821 installed on the flat surface portion 41 of the sand collecting pit 4, an elbow-shaped fixed sand-lifting pipe 822 supported by this support portion 821, and a guide member 823 erected from the fixed sand-lifting pipe 822. One end side of the fixed sand-lifting pipe 822 is connected to the sand-lifting pipe 81, and a fixed flange 8221 is provided on the other end side. An electric valve V2 is provided in the sand-lifting pipe 81. The sand-lifting pump 5 has a motor housing portion 51 in which a motor M (see Fig. 6) is housed, and a pump casing 52 disposed below the motor housing portion 51. The pump casing 52 has a horizontally directed pump discharge port 521, and a locking claw 5211 and a gripping portion 5212 are provided at the pump discharge port 521. The sand-lifting pump 5 is detachable from the pump fixing mechanism 82. To fix the sand-lifting pump 5 to the pump fixing mechanism 82, with the gripping portion 5212 being gripped by the guide member 823, the sand-lifting pump 5 is lowered into the sand collecting pit 4. Then, the pump discharge port 521 and the fixed sand-lifting pipe 822 communicate and are joined, and the locking claw 5211 engages with the fixed flange 8221 of the fixed sand-lifting pipe 822 due to the self-weight of the sand-lifting pump 5. Thereby, the sand-lifting pump 5 is fixed to the pump fixing mechanism 82. In a state where the sand-lifting pump 5 is fixed to the pump fixing mechanism 82, a gap (about 300 mm in this embodiment) is provided between the flat surface portion 41 of the sand collecting pit 4 and a suction port 52a described later.

[0061] Fig. 6 is a diagram schematically showing the internal structure of the sand-lifting pump 5 shown in Fig. 3.

[0062] As shown in FIG. 6, a motor housing portion 51 of the sand pumping pump 5 houses a motor M, and this motor M is driven and controlled by a control unit (not shown). The motor M is submerged in water. The pump casing 52 houses an impeller 522 attached to the drive shaft of the motor M and rotated by the driving of the motor M, and a suction space 52S is provided between the impeller 522 to form a suction port 52a. The sand pumping pump 5 of the present embodiment is a vortex pump, and the impeller 522 is disposed retracted on the side opposite to the side (upper side) where the suction port 52a is provided, ensuring a sufficient suction space 52S. The height 52h of this suction space 52S (the distance between the impeller 522 and the suction port 52a) coincides with the inner diameter 521Φ of the pump discharge port 521, and further coincides with the inner diameter of the sand pumping pipe 81 shown in FIG. 3. That is, the height 52h of the suction space 52S is ensured as the inner diameter without being throttled even once up to at least the position of the solenoid valve V2. Note that the height 52h of the suction space 52S may coincide with the inner diameter over the entire length of the sand pumping pipe 81. By configuring the sand pumping pump 5 with such a structure in which the impeller 522 is retracted, the pump can be miniaturized. Cost reduction can be achieved.

[0063] Also, the height 52h of the suction space 52S is equal to or greater than the mesh width of the filter screen 13 in the dust collector 10 shown in FIGS. 1 and 2 and equal to or less than 1.5 times the mesh width. By ensuring a height equal to or greater than the mesh width of the filter screen 13, it becomes possible to suck in, in addition to sand, contaminants that have passed through the filter screen 13. On the other hand, the higher the height 52h of the suction space 52S, the larger the pump becomes, leading to a cost increase. The sand pumping pump 5 sucks in sewage together with sand, and even if the height 52h of the suction space 52S is increased, if the magnitude of the driving force of the motor M is the same, the amount of sand sucked in does not increase, but only the amount of sewage sucked in increases, which is meaningless for sand removal. However, since long and thin rod-shaped contaminants may pass through the filter screen 13, it is preferable to ensure a length of 1.5 times.

[0064] The sand collected in the sand sump 4 is sucked in together with water (sewage) from the suction port 52a by driving the motor M by the control unit to rotate the impeller 522 of the sand lift pump 5, and is discharged as contaminated water containing sand from the pump discharge port 521. The contaminated water contains impurities in addition to sand. The contaminated water discharged from the pump discharge port 521 flows through the fixed sand lift pipe 822 and the sand lift pipe 81 shown in FIG. 3 and is sent to the sand separator 9 shown in FIG. 2.

[0065] As shown in Fig. 2, the sand separation device 9 includes a container 91, a storage tank 92, a conveying device 93, and a delivery pipe 94. The container 91, the storage tank 92, and the conveying device 93 are arranged on the ground near the grit chamber G. The lower part of the container 91 is arranged inside the tank of the storage tank 92, and the upper part of the container 91 protrudes above the storage tank 92. The container 91 is a so-called liquid cyclone that removes a certain amount of sewage and contaminants from the inflowing mixed water and sends it to the delivery pipe 94. In addition, the container 91 discharges the concentrated water with an increased sand concentration into the storage tank 92 after removing a certain amount of sewage and contaminants. The sewage and contaminants directly sent from inside the container 91 to the delivery pipe 94 are returned to the grit chamber G through the delivery pipe 94 together with the contaminants and liquid components sucked up from inside the storage tank 92 described later. Hereinafter, the sewage and contaminants directly sent from inside the container 91 to the delivery pipe 94, and the contaminants and liquid components sucked up from inside the storage tank 92 and sent to the delivery pipe 94 are collectively referred to as the discharged water. Also, hereinafter, the sand, contaminants, and liquid components stored in the storage tank 92 are collectively referred to as the stored liquid. The delivery pipe 94 has one end portion 941 connected to the container lid 911 of the container 91, a horizontal portion extending horizontally above the container 91, and a vertical portion extending downward after bending from the horizontal portion. And the other end 942, which is the lower end of the vertical portion, is arranged on the upstream side portion of the grit chamber G below the container 91 and outside the storage tank 92. The other end 942 of the delivery pipe 94 is arranged upstream of the discharge member 71 provided at the bottom of the pool of the upstream sedimentation region 2a. By doing so, even if sand is sent out from the sand separation device 9 through the delivery pipe 94 by any chance, it can be drawn into the inner trough 3 and re-sent to the sand collection pit 4. Note that the other end 942 side of the delivery pipe 94 may be extended below the water surface GW of the grit chamber G so that the other end 942 is submerged in the water. Further, the other end 942 may be arranged near the bottom of the pool of the grit chamber G. The container 91 and the storage tank 92 will be described in detail later.

[0066] The discharging device 93 is connected to the lower end of the storage tank 92 and extends obliquely upward. The discharging device 93 has a screw conveyor 931 and a dropping port 932. The screw conveyor 931 is disposed within the discharging device 93. The axial direction of the screw conveyor 931 coincides with the extending direction of the discharging device 93. A motor 933 and a drive transmission mechanism 934 are fixed to the upper end portion of the discharging device 93. By driving this motor 933, the screw conveyor 931 rotates via the drive transmission mechanism 934. Note that the motor 933 and the screw conveyor 931 may be directly connected without providing the drive transmission mechanism 934. The sand contained in the concentrated water discharged into the storage tank 92 settles within the storage tank 92 and flows into the discharging device 93 connected to the storage tank 92. As the screw conveyor 931 rotates, the sand is conveyed obliquely upward while being drained of water. The dropping port 932 is disposed near the upper end of the screw conveyor 931. The sand drained of water by the screw conveyor 931 is dropped downward from the dropping port 932. That is, the discharging device 93 discharges the sand contained in the stored liquid stored in the storage tank 92 to the outside of the storage tank 92. Note that instead of the screw conveyor 931, another discharging mechanism such as a belt conveyor may be used.

[0067] FIG. 7(a) is a plan view of the container shown in FIG. 2, and FIG. 7(b) is a cross-sectional view taken along line G-G in FIG. 7(a). FIG. 7(a) and FIG. 7(b) also show one end portion 941 of the delivery pipe 94 and a part of the sand lifting pipe 81.

[0068] As shown in Fig. 7(b), the container 91 includes a liquid introduction part 910, a throttle part 915, a discharge part 917, and a liquid inlet pipe 919. The liquid introduction part 910 is provided in the upper part of the container 91. The upper end of the throttle part 915 is connected to the lower end of the liquid introduction part 910. Also, the upper end of the discharge part 917 is connected to the lower end of the throttle part 915. The inner peripheral surface 91a of the container 91 is constituted by the inner peripheral surface 912a of the cylindrical part 912, the inner peripheral surface 915a of the throttle part 915, and the inner peripheral surface 917a of the discharge part 917. The inner space X1 is defined by the inner peripheral surface 91a of this container 91. That is, these liquid introduction part 910, throttle part 915, and discharge part 917 constitute a hollow tank having an inner space X1.

[0069] The liquid introduction part 910 includes a cylindrical part 912 with an inner peripheral surface 912a having a cylindrical shape, and a container lid 911 that closes the upper end of the cylindrical part 912. The cylindrical part 912 is formed by processing a steel plate with a thickness of 3.2 mm into a cylindrical shape with an inner diameter of 500 mm. Also, the container lid 911 is formed by processing a steel plate with a thickness of 6.0 mm into an annular shape with an outer diameter of 586 mm and an inner diameter of 216 mm. An inspection door (not shown) is provided on the container lid 911, and air can flow into and out of the container 91 through the inspection door. Note that the shape, material, and thickness of the cylindrical part 912 and the container lid 911 may be appropriately selected according to the size of the inner space X1 and the like.

[0070] A liquid inlet pipe 919 is connected to the upper part of the cylindrical portion 912. The sand lifting pump 5 shown in Fig. 1 etc. and the liquid inlet pipe 919 are connected via a sand lifting pipe 81. The sand lifting pipe 81 and the liquid inlet pipe 919 are detachably coupled by bolts fastening the flanges provided at the connection ends. The liquid inlet pipe 919 is a pipe with an inner diameter of 100 mm. As shown in Fig. 7(b), an inlet 9191 is formed at the connection portion between this liquid inlet pipe 919 and the cylindrical portion 912. As shown by the rightward straight-line arrows in Fig. 7(a) and Fig. 7(b), the contaminated water sucked up by the sand lifting pump 5 is introduced into the internal space X1 through the inlet 9191 from the tangential direction of the inner peripheral surface 912a of the cylindrical portion 912. Thereby, a swirling flow of the contaminated water is formed in the internal space X1.

[0071] The throttle portion 915 is disposed between the inlet 9191 and the discharge portion 917. In this throttle portion 915, the cross-sectional area of the internal space X1 decreases as it approaches the discharge portion 917. In other words, the throttle portion 915 has an inverted conical inner peripheral surface 915a that gradually decreases in diameter as it moves away from the cylindrical portion 915. This throttle portion 915 is formed by processing a steel plate with a thickness of 3.2 mm into a conical shape, with an inner diameter of 500 mm at the upper end and an inner diameter of 100 mm at the lower end. Note that the material and thickness of the throttle portion 915 may be appropriately selected according to the size of the internal space X1, the throttling amount, etc. Also, the throttle portion 915 may be formed such that the cross-sectional area of the internal space X1 decreases stepwise as it moves away from the cylindrical portion 915. That is, the throttle portion 915 only needs to have a smaller cross-sectional area on the discharge portion 917 side than on the inlet 9191 side of the internal space X1. The cross-sectional area of the lower end of the throttle portion 915 is equal to the opening area of the discharge port 9171. In this embodiment, the cross-sectional area of the lower end of the throttle portion 915, that is, the opening area (cross-sectional area) of the discharge port 9171, is made to coincide with the opening area (cross-sectional area) of the inlet 9191. However, the opening area of the discharge port 9171 may be equal to or greater than the opening area of the inlet 9191, or may be equal to or less than the opening area of the inlet 9191. However, if the opening area of the discharge port 9171 is made too small, the pressure loss in the container 91 increases. Therefore, it is preferable that the opening area of the discharge port 9171 is equal to or greater than the opening area of the inlet 9191. In addition, if the opening area of the discharge port 9171 is made too small or too large, the suction action from the storage tank 92 to the container 91 described later decreases. Therefore, it is desirable to set it to be 50% or more and 150% or less of the opening area of the inlet 9191. A container flange 9151 protruding toward the outside of the container 91 is formed at the upper end of the throttle portion 915.

[0072] The discharge portion 917 is coupled to the side of the throttle portion 915 opposite to the side to which the liquid introduction portion 910 is coupled. That is, the discharge portion 917 is coupled to the lower end of the throttle portion 915. The discharge portion 917 has a cylindrical shape with a flange 9172 formed at the lower end. The opening at the lower end of this discharge portion 917 becomes the discharge port 9171. Note that the discharge portion 917 may be omitted. In the case of omission, the opening at the lower end of the throttle portion 915 becomes the discharge port. The flange 9172 has an annular shape with an outer diameter of 200 mm.

[0073] The delivery pipe 94 is a pipe with an inner diameter of 200 mm. One end portion 941 of the delivery pipe 94 is watertightly connected to the container lid 911 by welding. Note that the one end portion 941 may protrude into the internal space X1. The lower end of this one end portion 941 becomes one end of the delivery pipe 94, and the opening at that one end becomes the delivery port 940. Therefore, the one end portion 941 and the delivery port 940 are connected to the container 91. The delivery port 940 is arranged at the central portion of the container 91 in a plan view. The delivered water is sent out from the delivery port 940 to the outside of the container 91. The delivered water sent out from this delivery port 940 is returned to the grit chamber G through the delivery pipe 94. In FIGS. 7(a) and 7(b), the flowing direction of the delivered water is indicated by a leftward straight arrow. The opening area of the delivery port 940 is preferably equal to or larger than the opening area of the discharge port 9171. By doing so, the amount of the delivered water sent out from the delivery port 940 can be increased, and the pressure loss in the container 91 can be reduced. Also, the opening area of the delivery port 940 is preferably an area equal to or larger than the opening area of the inflow port 9191. By doing so, a larger amount of fluid can be sent out from the delivery port 940 than the contaminated water flowing in from the inflow port 9191. The opening area of the delivery port 940 in this embodiment is four times the opening areas of the discharge port 9171 and the inflow port 9191.

[0074] FIG. 8 is a front view showing the container, the storage tank, and the lower part of the carrying device shown in FIG. 2. Further, FIG. 9 is a right side view showing the container, the storage tank, and the lower part of the carrying device shown in FIG. 2.

[0075] As shown in FIG. 8, the storage tank 92 includes a side wall 921 disposed outside the container 91 and extending upward from the discharge port 9171, a tank lid 922 closing the upper end of the side wall 921, and legs 923 supporting the storage tank. In this embodiment, the side wall 921 extends from below the discharge port 9171 to the height of the joint portion between the throttle portion 915 and the liquid introduction portion 910. A hole having the same diameter as the outer periphery of the liquid introduction portion 910 of the container 91 is formed in the central portion of the tank lid 922 in plan view. The container 91 is coupled to the storage tank 92 by welding the container flange 9151 to the tank lid 922 with the upper end portion of the throttle portion 915 inserted into the hole. A deodorizing pipe 9221 is provided on the tank lid 922. The legs 923 are respectively disposed at the four corners of the storage tank 92 in plan view. In FIG. 8, the intermediate portion of the leg 923 is omitted and only the upper end portion and the lower end portion are shown. By grounding the lower end portion of the leg 923, the storage tank 92 is disposed on the ground. Although a support member for supporting the carry-out device 93 is also provided at an intermediate portion in the extending direction of the carry-out device 93, the support member is not shown in the figure.

[0076] The upper portion of the storage tank 92 is formed into a square-cornered cylinder in plan view. As shown in FIG. 9, a tank inclined surface 921a is formed in the lower portion of the storage tank 92. The lower end of the tank inclined surface 921a is connected to the carry-out device 93. Also, as shown in FIG. 8, the lower end of the storage tank 92 has a shape that is cut obliquely upward at the same angle as the inclination angle of the carry-out device 93. The sand contained in the concentrated water discharged from the discharge port 9171 of the container 91 slides down the tank inclined surface 921a or directly accumulates on the lower portion of the carry-out device 93 connected to the lower end of the storage tank 92. As described above, the sand accumulated on the carry-out device 93 is carried out of the sand separation device 9 by the screw conveyor 931. A discharge pipe 935 for discharging the liquid and sand remaining in the storage tank 92 and the carry-out device 93 during inspection or the like is connected to the lower end of the carry-out device 93. A valve (not shown) that is opened when discharging the liquid and sand during inspection or the like and is normally closed is provided in the discharge pipe 935. FIGS. 8 and 9 also show a tank liquid level TW formed at the height position facing the discharge port 9171 by the storage liquid discharged from the discharge port 9171.

[0077] When sand is collected in the sand collecting pit 4, the sand separation device 9 starts the separation operation.

[0078] In the separation operation, first, the driving of the carry-out device 93 is started. While the carry-out device 93 is being driven, the sand deposited on the lower part of the carry-out device 93 is conveyed obliquely upward along the carry-out path of the carry-out device 93. The sand being conveyed by the screw conveyor 931 is conveyed while being drained in the latter half of the carry-out path that is higher than the tank liquid level TW. Then, the sand that has reached the upper end portion of the carry-out path of the carry-out device 93 is discharged by being dropped downward from the dropping port 932. After starting the driving of the carry-out device 93, next, the driving of the sand lifting pump 5 is started. By starting this driving, the inflow of the mixed water into the container 91 is started. The mixed water flows in from the tangential direction of the inner peripheral surface 912a of the cylindrical portion 912, and in the internal space X1, a swirling flow of the mixed water is formed in the vicinity of the inner peripheral surface 91a of the container 91. Since the sand contained in the mixed water has a higher specific gravity than the impurities and the sewage, it is pressed against the inner peripheral surface 91a of the container 91 by the centrifugal force and gradually falls downward while swirling along the inner peripheral surface 91a. On the other hand, in the central portion in the radial direction of the container 91, the impurities and the sewage from which the sand has been removed from the mixed water gather and an upward flow is generated. Due to this upward flow, the impurities and the sewage gathered in the central portion are sent out from the delivery port 940 at the upper end of the container 91. The sent-out impurities and sewage are discharged into the grit chamber G from the other end 942 of the delivery pipe 94 through the delivery pipe 94. Since the other end 942 of this delivery pipe 94 is arranged below the delivery port 940 formed at one end of the delivery pipe 94, when the inside of the delivery pipe 94 is filled with liquid, a force is generated to suck up the mixed water etc. in the internal space X1 from the delivery port 940 and flow out to the grit chamber G according to the principle of the siphon. As a result, the amount of the delivered water increases, and the suction action at the discharge port 9171 described later is further enhanced.

[0079] In the internal space X1, the sand that gradually falls downward while swirling along the inner peripheral surface 91a starts to be discharged as concentrated water from the discharge port 9171 together with a certain amount of impurities and sewage. The concentrated water is discharged from the discharge port 9171 in the tangential direction of the discharge port 9171 by the centrifugal force of the swirling flow. In FIGS. 8 and 9, the discharge direction of the concentrated water is indicated by a curved arrow. When the storage tank 92 is empty when the discharge of the concentrated water starts, the liquid level TW in the storage tank 92 gradually rises. Also, the sand contained in the stored liquid in the storage tank 92 settles toward the bottom of the storage tank 92 due to its own weight and accumulates in the lower part of the carry-out device 93. Note that as the amount of the accumulated sand increases, the sand that cannot fit into the lower part of the carry-out device 93 also accumulates in the lower part of the storage tank 92. Among the impurities contained in the stored liquid, those with a small specific gravity float in the sewage, which is the supernatant liquid of the stored liquid, and those with a large specific gravity slowly settle in the sewage.

[0080] When the liquid level TW in the tank rises and reaches the height position facing the discharge port 9171 as shown in FIGS. 8 and 9, the sewage, which is the supernatant of the stored liquid in the portion facing the discharge port 9171, is sucked into the discharge port 9171 together with the floating impurities. Hereinafter, the impurities and sewage sucked into the discharge port 9171 are collectively referred to as the impurity-containing liquid component. In FIG. 9, in the enlarged view surrounded by a circle, the state of the concentrated water discharged from the discharge port 9171 is shown with cross-hatching. In this enlarged view, the container 91, the liquid level TW in the tank, and the concentrated water are shown by solid lines. As shown in this enlarged view, the concentrated water is discharged toward the outer peripheral side of the discharge port 9171 by the kinetic energy of the swirling flow. At the height position where the liquid level TW in the tank faces the discharge port 9171 with a slight gap, the discharge port 9171 is in a state of being connected to the liquid level TW in the tank because the discharged concentrated liquid is continuous with the stored liquid. In this state, the discharge port 9171 is covered by the discharged concentrated water and the liquid level TW in the tank. A negative pressure is generated in the central portion in the radial direction of the discharge port 9171 due to the upward flow generated in the container 91. Due to this negative pressure, the supernatant of the stored liquid in the vicinity of the central portion in the radial direction of the discharge port 9171 and the impurities floating in the vicinity thereof are sucked into the discharge port 9171 as the impurity-containing liquid component. In other words, it can be said that the state in which the impurity-containing liquid component is sucked into the container 91 from the discharge port 9171 due to the above-described negative pressure is one aspect of the state in which the discharge port 9171 is connected to the stored liquid. In FIGS. 8 and 9, the suction direction of the impurity-containing liquid component is indicated by a straight arrow. When this impurity-containing liquid component is sucked into the discharge port 9171, the air around the discharge port 9171 is also sucked into the discharge port 9171. That is, an amount of impurity-containing liquid component and air greater than the amount of concentrated water discharged is sucked into the discharge port 9171. In the present embodiment, since the delivery port 940 having an opening area larger than that of the discharge port 9171 is formed, it is configured to be able to send out a large amount of fluid from the delivery port 940. As a result, it is easier to suck the impurity-containing liquid component and air from the discharge port 9171. Further, even if an amount of impurity-containing liquid component and air greater than the amount of concentrated water discharged is sucked from the discharge port 9171, it can be sent out from the delivery port 940.When the liquid component containing impurities and air are being sucked in from the discharge port 9171, a balanced state is formed in which the amount of concentrated water discharged from the discharge port 9171 into the storage tank 92 and the amount of the liquid component containing impurities sucked into the internal space X1 from the discharge port 9171 are substantially the same. The volume of air sucked into the discharge port 9171 is 1 / 5 or less of the volume of the liquid component containing impurities. In this embodiment, since a flange 9172 extending horizontally is formed around the discharge port 9171, air above the discharge port 9171 is less likely to be sucked into the discharge port 9171. Also, the ripples of the tank liquid level TW near the discharge port 9171 are suppressed by the flange 9172. As a result, air is less likely to be sucked into the discharge port 9171, and the ratio of the liquid component containing impurities being sucked into the discharge port 9171 relative to air is increased. Furthermore, the concentrated water discharged from the discharge port 9171 is more likely to be discharged neatly by the flange 9172. As a result, it is suppressed that the sand contained in the concentrated water discharged from the discharge port 9171 is mixed into the liquid component containing impurities sucked from the central portion in the radial direction of the discharge port 9171. Note that at the height position where the tank liquid level TW faces the discharge port 9171, the average distance between the tank liquid level TW and the discharge port 9171 is 0 mm or more and 20 mm or less. Here, as described above, since the concentrated water is discharged from the discharge port 9171 toward the outer peripheral side of the discharge port 9171, the possibility that the sand contained in the concentrated water is sucked from the central portion of the discharge port 9171 is low. In addition, sand has a large specific gravity and is likely to settle early below the storage tank 92. For this reason, even if a strong upward flow is formed in the container 91 and the suction force generated at the discharge port 9171 is strong, the amount of sand sucked into the container 91 is limited to a very small amount. Since that very small amount of sand also has a larger specific gravity compared to the liquid component containing impurities, most of it is repelled from the upward flow toward the outer peripheral side in the container 91 and is only caught in the swirling flow and is discharged again from the discharge port 9171 into the storage tank 92. Since air is also sucked in from the discharge port 9171 as described above, the upward flow generated in the central portion of the container 91 is a flow of a fluid with a small specific gravity in which the sucked air is mixed. Therefore, the specific gravity difference between the fluid mainly constituting the upward flow and the sand becomes larger, and the sand with a large specific gravity is more likely to be repelled toward the outer peripheral side.In addition, the stored liquid stored in the storage tank 92 is stirred by the discharged concentrated water. Due to this stirring, among the impurities contained in the stored liquid, those with a specific gravity greater than that of the liquid component of the stored liquid also rise up in the stored liquid and are more likely to float.

[0081] Note that the amount of contaminated water flowing into the container 91 is 2.0 m 3If it is less than / minute, the amount of the impurity-containing liquid component sucked into the discharge port 9171 becomes less than the concentrated water discharged from the discharge port 9171, and the tank liquid level TW may rise beyond the discharge port 9171. However, when the tank liquid level TW reaches the discharge port 9171, the discharge port 9171 is blocked by the stored liquid, so the amount of concentrated water discharged from the discharge port 9171 decreases. That is, due to the combined effect of the resistance caused by the reduction in the cross-sectional area of the internal space X1 in the throttle portion 915 and the water pressure of the stored liquid applied to the discharge port 9171, it becomes difficult for the concentrated water to be discharged from the discharge port 9171. And as the tank liquid level TW rises, the water pressure of the stored liquid applied to the discharge port 9171 increases, so the amount of concentrated water discharged from the discharge port 9171 decreases, and the amount of the water sent out from the delivery port 940 increases. Also, as described above, when the inside of the delivery pipe 94 is filled with liquid, an action to flow out from the delivery port 940 to the grit chamber G occurs in the water sent out due to the principle of the siphon, so the amount of the water sent out from the delivery port 940 further increases. As a result, the amount of the impurity-containing liquid component sucked into the discharge port 9171 increases, and the tank liquid level TW drops to a position facing the discharge port 9171. That is, during the period when the tank liquid level TW is decreasing, an amount of the impurity-containing liquid component greater than the amount of concentrated water discharged from the discharge port 9171 is being sucked in. In this way, when the amount of the mixed water flowing into the container 91 is reduced, and the inexpensive sand-lifting pump 5 can be used, the amount of electric power used by the sand-lifting pump 5 can be reduced. Note that when the tank liquid level TW is above the discharge port 9171, the discharge port 9171 is in a state of being submerged in the liquid of the stored liquid stored in the storage tank, but even in this state, the stored liquid is stored facing the discharge port 9171. That is, when the discharge port 9171 is submerged in the liquid of the stored liquid stored in the storage tank 92, the stored liquid in the portion covering the discharge port 9171 faces the discharge port 9171. Note that depending on the amount of the mixed water flowing into the container 91 and the strength of the swirling flow in the container 91, even if the above-described water pressure of the stored liquid applied to the discharge port 9171 and the action based on the principle of the siphon occur, the tank liquid level TW may stagnate above the discharge port 9171.

[0082] When the first predetermined time has elapsed since the start of driving the sand pumping pump 5, the driving of the sand pumping pump 5 is stopped. This first predetermined time is the time during which most of the sand collected in the sand collecting pit 4 can be sucked up by the sand pumping pump 5, and is a time appropriately set according to the capacity of the sand pumping pump 5 and the amount of sand that can be collected in the sand collecting pit 4. By stopping the sand pumping pump 5, the inflow of contaminated water into the container 91, the discharge of concentrated water into the storage tank 92, the suction of the impurity-containing liquid component, and the discharge of the pumped water are also stopped.

[0083] When the second predetermined time has elapsed since the driving of the sand pumping pump 5 was stopped, the driving of the unloading device 93 is stopped. This second predetermined time is the total time of the time during which the sand contained in the concentrated liquid discharged from the discharge port 9171 settles to the lower part of the unloading device 93 and the time of transporting the sand from the lower part of the unloading device 93 to the dropping port 932. Instead of determining whether the second predetermined time has elapsed, a sand presence / absence sensor for detecting the presence or absence of sand in the lower part of the unloading device 93 may be provided in the unloading device 93, and it may be determined whether the sand in that part has disappeared. Thus, the separation operation of the sand separation device 9 is completed. During the driving of the unloading device 93, since the tank liquid level TW is at a position substantially coinciding with the discharge port 9171, even if the unloading path is short, the sand can be transported while draining the water. Since the unloading path extends obliquely upward, shortening the unloading path reduces the lateral width and height of the unloading device 93. As a result, the sand separation device 9 can be miniaturized. According to the sand separation device 9 of this embodiment, not only are the sewage and impurities separated from the contaminated water flowing into the container 91 into sand, and the impurities and sewage are sent out from the outlet 940, but also while the impurities and sewage are being sent out from the outlet 940, the impurities and liquid components are sucked up from the stored liquid stored in the storage tank 92 and sent out from the outlet 940, so that clean sand without impurities can be left in the storage tank 92. Also, since the sand in the container 91 is prevented from reaching the outlet 940, it is also possible to prevent the sand from being sent out from the outlet 940. Thus, a high cleaning effect can be obtained while suppressing the outflow of sand.

[0084] As described above, in the sand separation device 9 adopted in this embodiment, the side wall 921 of the storage tank 92 extends only up to the height of the joint portion between the throttle portion 915 and the liquid introduction portion 910, and the storage tank 92 is designed to be low. Also, as described above, during the operation of the unloading device 93, the tank liquid level TW is at a position substantially coinciding with the discharge port 9171. Therefore, even if the unloading path is short, it is possible to convey the sand while draining the water, and the height of the unloading device 93 can be reduced. From these facts, the lift by the sand lift pump 5 can be suppressed, the sand lift pump 5 can be made inexpensive, and cost reduction is achieved.

[0085] The present invention is not limited to the above-described embodiments and can be variously modified within the scope described in the claims. For example, the liquid is not limited to sewage. Also, the solid is not limited to sand and impurities. Further, as the screen member, various known ones can be adopted.

[0086] Note that even the constituent elements included only in each of the above-described embodiments and each modification can be applied to the embodiments and other modifications.

Explanation of Reference Numerals

[0087] 1 Solid-liquid separation system 10 Dust collector 13 Filter screen 2 Sedimentation region 21 Outer trough 21 Opening 22 Inclined surface 25 Auxiliary outer trough 3 Inner trough 35 Auxiliary inner trough 31, 35 Inlet 4 Sand collection pit 5 Sand lift pump 52 Pump casing 52a Suction port 522 Impeller 52S Suction space 52h Height 6 Pump well 71 Discharge member 711 discharge port 9 sand separation device G grit chamber Ga bottom of the tank L1 opening width of the inlet L2 shortest distance

Claims

1. A solid-liquid separation system that settles solids contained in the received liquid to the bottom in a settling region, transfers the settled solids to an accumulation section, and removes the solids from the accumulation section, comprising: a screen member provided upstream of the settling region to block the passage of solids larger than the mesh width among the solids contained in the received liquid; a groove extending toward the accumulation section at the bottom and opening upward; a space forming member provided along the groove, forming a space with a closed upper end portion and having a draw-in port spaced from the bottom of the groove below the upper end portion; a discharge port for discharging fluid in the space toward the downstream side in the transfer direction of the solids; a vortex pump that sucks the solids transferred to the accumulation section together with liquid from a suction port by driving an impeller housed in a casing; The vortex pump is characterized in that the distance between the suction port and the impeller is not less than the mesh width and not more than 1.5 times the mesh width.

2. The vortex pump has a transfer pipe connected to the space between the suction port and the impeller, The transfer pipe is a pipe having an inner diameter equal to the length of the distance, according to the solid-liquid separation system of Claim 1.

3. The draw-in port is located in the groove, At least a part of the space forming member is disposed in the groove, When the opening width in the lateral direction orthogonal to the transfer direction of the draw-in port is L1 and the shortest distance between the outer peripheral surface of the space forming member and the inner peripheral surface of the groove is L2, 1.1 ≥ L1 / L2 ≥ 1.0 The solid-liquid separation system according to Claim 1 or 2, characterized in that it has the relationship of.

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