JP7616737B2 - Mixing and clarification equipment - Google Patents

Description

The present invention relates to a mixing and clarification device .

For example, water purification plants use water purification equipment that removes suspended solids (SS) contained in raw water (hereinafter also referred to as treated water) such as river water or well water. Specifically, such water purification equipment mixes a coagulant into the treated water to coagulate the suspended solids contained in the treated water, causing them to settle and be removed. This makes it possible for the water purification plant to produce safe water for daily use from the treated water, for example (see Patent Document 1).

JP 2012-185007 A

The water purification equipment described above, for example, has a tank (hereinafter also referred to as a mixing tank) for mixing the coagulant and the water to be treated, a tank (hereinafter also referred to as a flocculation tank) for forming flocs by coagulating suspended matter, and a tank (hereinafter also referred to as a sedimentation tank) for settling the formed flocs and separating them from the water to be treated, in the stage preceding the filtration device that performs filtration membrane treatment of the water to be treated. This makes it possible for the water purification equipment to reduce the turbidity of the water to be treated sent to the filtration device. Therefore, the water purification device can reduce the solid matter load on the filtration device and shorten the cleaning cycle of the filtration membrane.

However, in water purification facilities such as those described above, the mixing power (electricity) required in the mixing basin and flocculation basin can be large. In addition, the mixing and turbidity removal device described above requires a settling basin, which can require a large installation space. Therefore, there is a demand for power saving and reduction in installation space in water purification facilities such as those described above.

In order to achieve the above-mentioned power saving and space saving, the mixing and turbidity removal device of the present invention comprises a substantially cylindrical tank having a bottom, a substantially cylindrical tube with an open top and bottom and disposed inside the tank so that its axial direction is substantially aligned with that of the tank, an inflow pipe through which the water to be treated flows in, an outflow pipe through which the treated water flows out, and a partition that divides the flow path formed by the inner sidewall of the tank and the outer sidewall of the tube into an upper flow path and a lower flow path in the axial direction of the tank and the tube, and the inflow pipe is connected to the upper flow path, and the outflow pipe is connected to the lower flow path.

The mixing and turbidity removal device of the present invention makes it possible to reduce power consumption and installation space.

FIG. 1 is a vertical cross-sectional view of the mixing and clarification device 100 as viewed from the front. FIG. 2 is a cross-sectional view of the mixing and clarification device 100 taken along the line AA. FIG. 3 is a cross-sectional view of the mixing and clarification device 100 taken along the line BB. FIG. 4 is a cross-sectional view of the mixing and clarification device 100 taken along the line CC. FIG. 5 is a diagram illustrating the formation of flocs. FIG. 6 is a diagram illustrating the formation of flocs. FIG. 7 is a diagram illustrating the formation of flocs. FIG. 8 is a diagram illustrating the formation of flocs. FIG. 9 is a diagram illustrating the formation of flocs. FIG. 10 is a diagram illustrating the configuration of the pump and the control device. FIG. 11 is a vertical cross-sectional view of the mixing and clarification device 200 in the second embodiment as viewed from the front.

Below, an embodiment of the present invention will be described with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.

[Mixing and clarification device 100 in the first embodiment]
1 to 10 are configuration diagrams of the mixing and turbidity removal device 100 in the first embodiment. Specifically, Fig. 1 is a vertical cross-sectional view of the mixing and turbidity removal device 100 when viewed from the front. Fig. 2 is an A-A cross-sectional view of the mixing and turbidity removal device 100, Fig. 3 is a B-B cross-sectional view of the mixing and turbidity removal device 100, and Fig. 4 is a C-C cross-sectional view of the mixing and turbidity removal device 100.

As shown in FIG. 1, the mixing and turbidity removal device 100 has, for example, a substantially cylindrical tank 10 having a bottom 12, and a substantially cylindrical tube 20 that is provided inside the tank 10 so that its axial direction substantially coincides with that of the tank 10 and that has an open upper surface 21a and lower surface 21b. The axial direction of the tank 10 may coincide with the axial direction of the tube 20, or may be inclined at a predetermined angle (for example, an angle of less than 5 degrees) with respect to the axial direction of the tube 20.

As shown in Figures 1 and 3, the mixing and clarification device 100 has a partition 31 that is annular in top view between the inside of the wall 11 and the outside of the wall 21.

Furthermore, as shown in Figures 1, 2 and 4, the mixing and clarification device 100 has an inlet pipe 41 through which the treated water (treated water to which a coagulant has been added) flows in from a mixing basin (not shown), and an outlet pipe 42 through which the treated water (hereinafter also simply referred to as treated water) flows out after solid-liquid separation in the mixing and clarification device 100.

The tank 10 has, for example, a wall 11 having a circular horizontal cross section, a bottom 12 molded integrally with the wall 11 below the wall 11, and a floc discharge pipe 13 communicating with the lower end of the bottom 12. Note that the wall 11 may have, for example, an elliptical horizontal cross section.

The wall portion 11 has, for example, an inlet 11a that communicates with the inlet pipe 41 and an outlet 11b that communicates with the outlet pipe 42.

The bottom 12 has, for example, a tapered shape that narrows toward the bottom. And, for example, flocks formed on the inside of the wall 11 are deposited on the bottom 12.

The flock discharge pipe 13, for example, discharges flocks accumulated on the bottom 12 to the outside. Specifically, the flock discharge pipe 13 discharges flocks accumulated on the bottom 12 to the outside in response to the valve 32 being opened.

Here, it is preferable that the upper surface (not shown) of the wall portion 11 is sealed. That is, it is preferable that the tank 10 is sealed except for the inlet 11a and the outlet 11b. This makes it possible for the tank 10 to discharge the treated water that has flowed in from the inlet pipe 41 through the outlet pipe 42, as described below.

The cylinder 20 has a wall portion 21 that has, for example, a circular horizontal cross section and is open at the upper surface 21a and the lower surface 22b. Note that the wall portion 21 may have, for example, an elliptical horizontal cross section.

The wall portion 21 has, for example, a shorter length in the axial direction (vertical direction) than the wall portion 11. The vertical height of the upper end of the wall portion 21 is, for example, lower than the height of the upper end of the wall portion 11, and the vertical height of the lower end of the wall portion 21 is higher than the height of the lower end of the wall portion 11. Note that a portion of the upper end side of the wall portion 21 may have a tapered shape that tapers upward, and a portion of the lower end side of the wall portion 21 may have a tapered shape that tapers downward.

The partition portion 31, for example, fixes the tube 20 to the tank 10 and divides the flow path formed by the inside of the wall portion 11 and the outside of the wall portion 21 into an upper flow path R1 and a lower flow path R4 in the axial direction of the tank 10 and the tube 20.

That is, the upper flow path R1 is a flow path corresponding to the upper space of the space partitioned by the tank 10, the tube 20, and the partition 31, as shown in Figures 1 and 2. The lower flow path R4 is a flow path corresponding to the upper space of the space partitioned by the tank 10, the tube 20, and the partition 31, as shown in Figures 1 and 4. In the following, the flow path from the upper surface of the wall 21 to the lower surface (the flow path corresponding to the space inside the tube 20) is also referred to as the tube flow path R2, and the flow path below the tube flow path R2 (the flow path corresponding to the space below the lower end of the tube 20) is also referred to as the bottom flow path R3.

The inlet pipe 41 is connected to the upper flow path R1, for example, via the inlet 11a. The outlet pipe 42 is connected to the lower flow path R4, for example, via the outlet 11b. That is, although details will be described later, the water to be treated that flows into the tank 10 from the inlet pipe 41 passes through the upper flow path R1, the cylindrical flow path R2, the bottom flow path R3, and the lower flow path R4 in that order. Then, solid-liquid separation is performed during this process. Then, after solid-liquid separation, the treated water flows out from the lower flow path R4 to the outlet pipe 42. Note that points P1 and P2 shown in FIG. 1 will be described later.

Here, as shown in FIG. 2, the inlet pipe 41 may be installed, for example, so that its longitudinal direction is along the tangential direction in the horizontal cross section of the tank 10 (wall portion 11). This allows the inlet pipe 41 to allow the water to be treated to flow into the tank 10 while maintaining the flow rate.

[Floc formation]
Next, the formation of flocs in the mixing and turbidity device 100 will be described. Figures 5 to 8 are diagrams for explaining the formation of flocs 1. Specifically, Figures 5, 7, and 9 are vertical cross-sectional views (corresponding to Figure 1) of the mixing and turbidity device 100 as viewed from the front. Also, Figure 6 is an A-A cross-sectional view (corresponding to Figure 2) of the mixing and turbidity device 100, and Figure 8 is a CC cross-sectional view (corresponding to Figure 4) of the mixing and turbidity device 100. In the following, illustration of the upper surface 21a and the lower surface 21b of the tube 20 will be omitted.

First, the water to be treated flows from the inlet pipe 41 into the upper flow path R1, as shown by the solid arrow in Figure 5. Specifically, for example, as shown in Figure 6, when the longitudinal direction of the inlet pipe 41 is aligned with the tangent direction in the horizontal cross section of the wall portion 11, the water to be treated flows into the upper flow path R1 while maintaining the flow velocity in the inlet pipe 41.

Next, as shown by the solid arrows in Figures 5 and 6, the flow of the water to be treated in the upper flow passage R1 becomes an upward swirling flow. That is, because a partition 31 is provided at the bottom of the upper flow passage R1, the water to be treated that flows into the upper flow passage R1 from the inlet pipe 41 rises while swirling. Then, in the upper flow passage R1, as shown in Figure 5, minute flocs 1 (hereinafter also referred to as flocs 1a) with small particle sizes are formed by agitation caused by the swirling flow of the water to be treated.

Here, in the example shown in Figures 5 and 6, the width of the upper flow path R1 is narrower than the tubular flow path R2. Therefore, the residence time of the water to be treated in the upper flow path R1 (hereinafter also referred to as the T value) is shorter than the T value in the tubular flow path R2 described later. Furthermore, the water to be treated that flows from the inflow pipe 41 into the upper flow path R1 flows in while maintaining the flow velocity in the inflow pipe 41. Therefore, the stirring strength (hereinafter also referred to as the G value) caused by the flow of the water to be treated is greater than the G value in the tubular flow path R2 described later.

Here, the force of the water being treated in the horizontal direction (swirling, sideways flow) weakens while causing pressure loss. In other words, as the water being treated flows upward, the flow rate of the swirling flow decreases. On the other hand, the force of the water being treated in the vertical direction remains almost unchanged (since it is a push flow, the flow rate remains almost unchanged).

Next, the water to be treated (water to be treated containing flocs 1a) that has risen to the upper end of the upper flow path R1 due to the upward swirling flow in the upper flow path R1 flows sequentially into the tubular flow path R2, as shown by the solid arrows in Figure 7. Then, in the tubular flow path R2, the flow of the water to be treated becomes a downward swirling flow, as shown by the solid arrows in Figures 7 and 8. Furthermore, in the tubular flow path R2, as shown in Figure 7, flocs 1 (hereinafter also referred to as flocs 1b) that are larger in particle size than flocs 1a are formed by stirring caused by the swirling flow of the water to be treated.

Here, in the example shown in Figures 7 and 8, the width of the tubular flow path R2 is wider than the upper flow path R1. Therefore, the T value of the water to be treated in the tubular flow path R2 is longer than the T value in the upper flow path R1. In addition, the swirling flow of the water to be treated flowing from the upper flow path R1 into the tubular flow path R2 becomes smaller (the mixing strength becomes weaker) as it flows from the upper flow path R1 to the tubular flow path R2. Therefore, the G value due to the flow of the water to be treated is smaller than the G value in the upper flow path R1. In particular, the vertical flow direction of the water to be treated in the tubular flow path R2 (downward flow) is opposite to the flow direction in the upper flow path R1 (upward flow), so the G value due to the flow of the water to be treated is smaller in the tubular flow path R2.

Furthermore, when the water to be treated descends from the cylindrical flow path R2 to the bottom side flow path R3, the swirling flow becomes smaller, so the G value due to the flow of the water to be treated becomes even smaller. Then, in the bottom side flow path R3, floc 1 grows into floc 1 (hereinafter also referred to as floc 1c) which has a larger particle size than floc 1b. That is, the flocs of the water to be treated gradually grow larger in the process of gravity settling in the bottom side flow path R3. Then, the formed floc 1c is deposited at the bottom 12.

Then, the treated water that has descended to the bottom flow path R3 flows from the bottom flow path R3 into the lower flow path R4 by an upward flow, as shown in FIG. 9. Then, the treated water that has flowed into the lower flow path R4 flows out of the outflow pipe 42 via the outflow outlet 11b, as shown in FIG. 9.

Here, the flocs 1c deposited on the bottom 12 are flocs whose particle size is much larger than that of the flocs 1a and 1b. Therefore, the flocs 1c do not rise due to the upward flow from the bottom flow path R3 to the lower flow path R4, and do not flow into the lower flow path R4. In other words, flocs whose settling flow rate is faster than the outflow rate (upward flow rate) of the treated water are separated. Therefore, the mixing and clarification device 100 is able to separate the flocs 1c from the treated water.

In this way, the mixing and turbidity removal device 100 in this embodiment includes a substantially cylindrical tank 10 having a bottom 12, a substantially cylindrical tube 20 that is provided inside the tank 10 so that its axial direction is substantially aligned with that of the tank 10 and has an open upper surface 21a and lower surface 21b, an inlet pipe 41 through which the water to be treated flows in, an outlet pipe 42 through which the treated water flows out, and a partition 31 that divides the flow path formed by the inside of the wall portion 11 and the outside of the wall portion 21 into an upper flow path R1 and a lower flow path R4 in the axial direction of the tank 10 and the tube 20. The inlet pipe 41 is connected to the upper flow path R1, and the longitudinal direction of the inlet pipe 41 is aligned with the tangential direction in the horizontal cross section of the tank 10, and the outlet pipe 42 is connected to the lower flow path R4.

In other words, in the mixing and turbidity removal device 100 of this embodiment, for example, the longitudinal direction of the inlet pipe 41 is aligned along the tangential direction in the horizontal cross section of the tank 10, so that the water to be treated flows into the upper flow path R1 while maintaining the flow velocity in the inlet pipe 41. Therefore, in the mixing and turbidity removal device 100, it is possible to stir the water to be treated without using stirring power. Therefore, in the mixing and turbidity removal device 100, it is possible to achieve power saving.

To form good quality flocs 1, the GT value, which is the product of the G value and the T value in the treated water, must generally be set to a predetermined threshold value or higher. Furthermore, to prevent the flocs 1 from being destroyed by the shearing action of the water flow, it is preferable to employ a so-called tapered flocculation method. This tapered flocculation method is a method in which the coagulant is sufficiently stirred with strong stirring intensity (large G value) when the particle size of the flocs 1 is small, and the stirring intensity is weakened (small G value) after the particle size of the flocs 1 has increased.

In this regard, in the mixing and turbidity removal device 100 of this embodiment, it is possible to increase the G value in the upper flow path R1 and also to decrease the G value in the tubular flow path R2. Therefore, in the mixing and turbidity removal device 100, it is possible to increase the G value when the particle size of the flocs 1 is small and decrease the G value after the particle size of the flocs 1 has increased. In addition, in the mixing and turbidity removal device 100, it is possible to increase the T value in the tubular flow path R2 greater than the T value in the upper flow path R1, so it is possible to ensure the GT value in each of the upper flow path R1 and the tubular flow path R2.

In the mixing and turbidity removal device 100 of this embodiment, the G value near the bottom of the upper flow path R1 (near the partition 31) is greater than the G value near the upper end of the upper flow path R1. Therefore, in the mixing and turbidity removal device 100, even when focusing only on the upper flow path R1, it is possible to form flocs according to the tapered flocculation method.

In addition, the mixing and clarification device 100 in this embodiment has a structure that accumulates floc 1 (floc 1c) at the bottom 12 of the tank 10, eliminating the need to provide a separate settling tank. Therefore, the mixing and clarification device 100 makes it possible to reduce the installation space.

[Control of flow of treated water when using a pump]
Next, the control of the flow of the water to be treated when a pump is used will be described below. Fig. 10 is a diagram illustrating the configuration of the pump and the control device.

As shown in FIG. 10, the inlet pipe 41 may be provided with, for example, a first pump P11 that discharges the water to be treated toward the tank 10 (upper flow path R1). The outlet pipe 42 may be provided with, for example, a second pump P12 that draws the water to be treated from the tank 10 (lower flow path R4). That is, at least one of the first pump P11 and the second pump P12 may be provided.

Furthermore, a control device 60 may be installed outside the mixing and clarification device 100, for example, to control the operation of at least one of the first pump P11 and the second pump P12. The control device 60 is, for example, a computer device having a CPU (Central Processing Unit) and memory. Specifically, the control device 60 controls at least one of the first pump P11 and the second pump P12, for example, so that the G value caused by the flow of the treated water in the upper flow path R1 is greater than the G value caused by the flow of the treated water in the cylindrical flow path R2.

This allows the mixing and clarification device 100 to more precisely control the formation of high-quality flocs. In particular, the mixing and clarification device 100 can increase the G value in the upper flow path R1 by, for example, installing the first pump P11 downstream of the position where the coagulant is supplied to the water to be treated.

In general, when the concentration of flocs in the water to be treated (hereinafter also referred to as C0) is high, it is possible to form good quality flocs even when the GT value is small. Therefore, the control device 60 may control the G value due to the flow of the water to be treated in the upper flow path R1, for example, when the C0 in the water to be treated is high, so that the GT value becomes small. The control device 60 may also control the G value due to the flow of the water to be treated in the upper flow path R1, for example, when the C0 in the water to be treated is small, so that the GT value becomes large.

[Mixing and clarification device 200 in the second embodiment]
Fig. 11 is a configuration diagram of the mixing and turbidity removal device 200 in the second embodiment. Specifically, Fig. 11 is a vertical cross-sectional view of the mixing and turbidity removal device 200 in the second embodiment as viewed from the front.

In the mixing and clarification device 100 shown in FIG. 1, points P1 and P2 each indicate the position where the treated water flows into the lower flow path R4. Specifically, point P1 indicates the position where the treated water flows into the lower flow path R4 that is the furthest from the outlet 11b. Point P2 indicates the position where the treated water flows into the lower flow path R4 that is the closest from the outlet 11b.

Here, the treated water that flows into the lower flow path R4 at point P1 reaches the outlet 11b (outlet pipe 42) via a flow path that runs along the outer periphery of the tube 20. In contrast, the treated water that flows into the lower flow path R4 at point P2 reaches the outlet 11b only via a flow path that runs upward, without passing through a flow path that runs along the outer periphery of the tube 20. Therefore, the treated water that flows into the lower flow path R4 at point P1 must pass through a longer flow path to reach the outlet 11b than the treated water that flows into the lower flow path R4 at point P2.

Therefore, in the mixing and clarification device 100 shown in FIG. 1, the flow rate of the treated water flowing from the bottom flow path R3 to the lower flow path R4 may differ depending on the position where the treated water flows into the lower flow path R4. Therefore, in the mixing and clarification device 100 shown in FIG. 1, for example, in a position where the flow rate of the treated water from the bottom flow path R3 to the lower flow path R4 is high, suction of flocs 1c accumulated on the bottom 12 may occur.

Therefore, in the second embodiment, the mixing and turbidity removal device 200 has a tube 50 (wall portion 51) whose lower edge is inclined relative to the horizontal direction, as shown in FIG. 11, instead of the tube 20 described in FIG. 1, etc.

As a result, as shown in FIG. 11, the mixing and turbidity device 200 can reduce the difference between the distance of the lower flow path R4 from point P3, which is the position where the treated water flows into the lower flow path R4 that is farthest from the outlet 11b, to the outlet 11b, and the distance of the lower flow path R4 from point P2, which is the position where the treated water flows into the lower flow path R4 that is closest from the outlet 11b, to the outlet 11b. Therefore, the mixing and turbidity device 200 can reduce the difference in the flow rate of the treated water at each position where it flows into the lower flow path R4, and can suppress the suction of flocs 1c accumulated at the bottom 12.

Furthermore, it is preferable that the shape of the lower edge of the tube 50 is such that, for example, the distance from each position where the treated water flows into the lower flow path R4 to the outlet 11b is constant.

Specifically, in the example shown in FIG. 11, the distance of the lower flow path R4 from point P3 to the outlet 11b is, for example, half the circumference of the horizontal cross section of the tube 50. Therefore, in this case, it is preferable that the distance of the lower flow path R4 from point P2 to the outlet 11b (i.e., the vertical distance from point P2 to the outlet 11b) is half the circumference of the horizontal cross section of the tube 50.

This enables the mixing and clarification device 200 to better reduce the difference in flow rate of the treated water at each point where it flows into the lower flow path R4, and to better prevent the suction of flocs 1c accumulated at the bottom 12.

1: Floc 1a: Floc 1b: Floc 1c: Floc 10: Tank 11: Wall 11a: Inlet 11b: Outlet 12: Bottom 13: Floc discharge pipe 20: Cylinder 21: Wall 21a: Upper surface 21b: Lower surface 31: Partition 32: Valve 41: Inlet pipe 42: Outlet pipe 50: Cylinder 51: Wall 60: Control device 100: Mixing and turbidity removal device 200: Mixing and turbidity removal device R1: Upper flow path R2: Cylinder flow path R3: Bottom flow path R4: Lower flow path P11: First pump P12: Second pump

Claims (2)

A generally cylindrical vessel having a bottom;
a substantially cylindrical tube that is provided inside the tank so that its axial direction substantially coincides with that of the tank and that has an open upper and lower surfaces;
an inflow pipe into which the water to be treated flows;
an outflow pipe through which the treated water flows out;
a partition portion that partitions a flow path formed by an inner side wall of the tank and an outer side wall of the cylinder into an upper flow path and a lower flow path in an axial direction of the tank and the cylinder,
The inlet pipe is in communication with the upper flow passage,
The outlet pipe is in communication with the lower flow path,
A mixing and clarification device , wherein the lower edge of the tube has a shape that is inclined with respect to the horizontal cross section of the tank . A mixing and clarification device,
A generally cylindrical vessel having a bottom;
a substantially cylindrical tube that is provided inside the tank so that its axial direction substantially coincides with that of the tank and that has an open upper and lower surfaces;
an inflow pipe into which the water to be treated flows;
an outflow pipe through which the treated water flows out;
a partition portion that partitions a flow path formed by an inner side wall of the tank and an outer side wall of the cylinder into an upper flow path and a lower flow path in an axial direction of the tank and the cylinder,
The inlet pipe is in communication with the upper flow passage,
The outlet pipe is in communication with the lower flow path,
Further, at least one of a pump provided on the inflow pipe side for discharging the water to be treated to the mixing and clarification device and a pump provided on the outflow pipe for sucking the treated water from the mixing and clarification device;
A control device that controls the operation of the pump,
The control device controls the pump so that the stirring strength caused by the flow of the water to be treated in the upper flow path is greater than the stirring strength caused by the flow of the water to be treated inside the side wall of the tube.

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