JP2024032818A - stirring tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stirring tank configured so that sludge or the like deposited on a bottom part can be stirred.

SOLUTION: A stirring tank 2, which is configured so that received sludge is stirred by circulation flow while the received sludge flows in a flowing direction, is provided with a hollow space forming member 7 extending along a bottom surface 6i formed on a bottom part of the stirring tank 2 and having an ejection port 7b formed at an end part in an extending direction, and a discharge port 81 through which fluid is discharged to an internal space S1 defined by an inner surface 7i of the space forming member 7. The space forming member 7, in which a lower opening 7d separated from the bottom surface 6i is formed at a lower portion thereof, is extended in a direction in which an angle with respect to the flowing direction is 30 degrees or more and 150 degrees or less in a planar view. The lower opening 7d suctions liquid around the port into the internal space S1 when fluid is ejected from the ejection port 7b. The ejection port 7b forms circulation flow by ejecting fluid discharged from the discharging port 81 as well as liquid suctioned through the lower opening 7d.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a stirring tank for stirring a received liquid.

In sewage treatment facilities that treat wastewater such as sewage and rainwater, aerobic biological treatment is performed to remove nitrogen, phosphorus, etc. from the wastewater. In addition, in recent years, advanced treatment has been carried out to efficiently remove nitrogen, phosphorus, etc. by performing anaerobic biological treatment or biological treatment in anoxic conditions with the addition of nitric acid, etc., before aerobic biological treatment. ing. Each biological treatment is performed in a stirring tank that has the function of stirring the contained wastewater so that the garbage and sludge contained in the wastewater do not accumulate in the same position and rot. Some of these stirring tanks agitate the collected wastewater by discharging fluid from a discharge port disposed in the collected wastewater to form a circulating flow of the wastewater. In addition, some stirring tanks that perform aerobic biological treatment mix air and wastewater by discharging wastewater while supplying air to form a circulating flow of wastewater. As a stirring tank for performing such aerobic biological treatment, a cylindrical body having a discharge port for discharging air and wastewater and openings at both ends in the discharge direction is installed near the bottom of the stirring tank, and the interior of the cylinder is A stirring tank has been proposed that mixes air and sewage and circulates the sewage by the flow of air and sewage discharged from a discharge port (see, for example, Patent Document 1 and Patent Document 2). In addition, stirring tanks are sometimes used for purposes other than biological treatment, such as for mixing two or more types of fluids, or uniformly dispersing various powders, chemicals, etc. in fluids.

Japanese Unexamined Patent Publication No. 50-98158 Japanese Unexamined Patent Publication No. 50-107769

However, in a stirring tank in which a cylindrical body is installed, there is a problem in that it is difficult for a fluid flow to enter the gap between the bottom surface of the stirring tank and the cylindrical body, and therefore it is difficult to form a circulating flow in the gap. In particular, when sewage and air are discharged from the discharge port, the mixed fluid of air and sewage that has passed through the cylindrical body tends to move upward due to the buoyancy of the air contained in the mixed fluid. However, even if a circulating flow is formed, there is a problem in that it is difficult to form a circulating flow below the cylindrical body. If a circulation flow is not formed below the cylinder, or even if it is formed, if the circulation flow is weak, the sludge, etc. that has settled below the cylinder will remain without being stirred, and there is a risk that it will rot. there were.

In view of the above circumstances, an object of the present invention is to provide a stirring tank capable of stirring sludge and the like settled at the bottom.

The stirring tank of the present invention that solves the above object is a stirring tank that stirs the received liquid by circulating flow while the liquid is flowing in the flow direction,
A hollow space forming member that extends along the bottom surface formed at the bottom of the stirring tank and has a discharge port provided at an end in the extending direction;
a discharge port configured to discharge fluid toward the extending direction into an internal space defined by the inner surface of the space forming member;
The space forming member has a lower opening spaced apart from the bottom surface formed in a lower portion thereof, and extends in a direction at an angle of 30 degrees or more and 150 degrees or less in plan view with respect to the flow direction,
The lower opening sucks surrounding liquid into the internal space when fluid is discharged from the discharge port,
The discharge port is characterized in that the circulating flow is formed by discharging the fluid discharged from the discharge port and the liquid sucked in from the lower opening.

Further, the stirring tank of the present invention that solves the above object is a stirring tank that stirs the received liquid by circulating flow while the liquid is flowing in the flow direction,
A hollow space forming member that extends along the bottom surface formed at the bottom of the stirring tank and has a discharge port provided at an end in the extending direction;
a discharge port configured to discharge fluid toward the extending direction into an internal space defined by the inner surface of the space forming member;
The space forming member has a lower opening spaced apart from the bottom surface formed in a lower portion thereof, and extends in a direction perpendicular to the flow direction in plan view;
The lower opening sucks surrounding liquid into the internal space when fluid is discharged from the discharge port,
The discharge port is characterized in that the circulating flow is formed by discharging the fluid discharged from the discharge port and the liquid sucked in from the lower opening.

The space forming member may be arranged in an area partitioned by a partition wall.

According to the present invention, it is possible to provide a stirring tank capable of stirring sludge or the like that has settled at the bottom.

FIG. 1 is a plan view of advanced treatment equipment equipped with a stirring tank according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA of the advanced treatment facility shown in FIG. 1. (a) is an enlarged view showing section C in FIG. 1, and (b) is a sectional view taken along line EE in FIG. 1(a). (a) is an enlarged view showing section D in FIG. 1, and (b) is a sectional view taken along line FF in (a) of the same figure. FIG. 3 is a BB cross-sectional view of the anaerobic tank shown in FIG. 2. FIG. 3 is a sectional view showing a mode corresponding to FIG. 2 in the advanced processing equipment 1 of the second embodiment. (a) is a sectional view showing a modification of one end portion of the space forming member shown in FIG. 3(b), and (b) is a sectional view showing a modification example of the other end portion of the space forming member shown in FIG. 4(b). FIG.

Embodiments of the present invention will be described below with reference to the drawings. A stirring tank, which is an embodiment of the present invention, is placed in a wastewater treatment facility and performs biological treatment to remove nitrogen, phosphorus, and the like from wastewater.

FIG. 1 is a plan view of advanced treatment equipment equipped with a stirring tank according to an embodiment of the present invention. In FIG. 1, the advanced processing equipment is shown with the upper part including the ceiling omitted. Further, FIG. 2 is a sectional view taken along the line AA of the advanced processing equipment shown in FIG. Note that FIG. 2 shows a simplified intermediate portion of the fluid supply pipe, which will be described later.

As shown in FIG. 1, the advanced treatment equipment 1 is a rectangular equipment in plan view, and has an anaerobic tank 2 for performing anaerobic biological treatment and an aerobic biological treatment between the left side wall 11 and the right side wall 12. A plurality of aeration tanks 3 are provided. Hereinafter, the lateral direction (vertical direction in FIG. 1) of the advanced processing equipment 1 will be referred to as the width direction. This advanced treatment facility 1 is a facility that performs biological treatment on sewage from which contaminants such as sand have been removed in a sewage treatment facility. The advanced treatment facility 1 receives wastewater such as sewage and rainwater that has been treated in a settling tank and a primary settling tank (not shown). This wastewater corresponds to an example of a liquid. The advanced treatment facility 1 receives wastewater from the left side in FIG. The wastewater received by the advanced treatment facility 1 contains fine garbage that cannot be completely removed by a settling basin or the like. Furthermore, in order to perform biological treatment, activated sludge containing many microorganisms is supplied to the anaerobic tank 2 from a final settling tank (not shown) provided downstream of the advanced treatment facility 1. Hereinafter, the above-mentioned waste and activated sludge will be collectively referred to as sludge. The wastewater received by the advanced treatment facility 1 slowly flows toward the right side in FIG. 1 in the anaerobic tank 2 and the aeration tank 3 (see the straight arrows shown in FIG. 1). Hereinafter, the upstream side of the flow of received wastewater will be simply referred to as the upstream side, and the downstream side of the flow of the received wastewater will be simply referred to as the downstream side.

On the upstream side of the advanced treatment facility 1, a total of eight anaerobic tanks 2 are provided, two rows in parallel with respect to the flow direction of wastewater, four in each row. Each of these anaerobic tanks 2 corresponds to an example of a stirring tank. Furthermore, on the downstream side of the advanced treatment facility 1, a total of four aeration tanks 3 are provided, two rows in parallel with respect to the flow direction of wastewater, two in each row. A central wall 13 is formed between each row, and the central wall 13 allows wastewater received by the anaerobic tanks 2 and aeration tanks 3 in one row to flow into the anaerobic tanks 2 and aeration tanks 3 in the other row. This is prevented. Partition walls 14 are provided between anaerobic tanks 2, between aeration tanks 3, and between anaerobic tanks 2 and aeration tanks 3 in the same row. This partition wall 14 partitions off the anaerobic tanks 2, the aeration tanks 3, and the anaerobic tanks 2 and aeration tanks 3 in the same row. However, an inflow opening 14a (see FIG. 2) is formed in the widthwise central portion of the lower end of the partition wall 14. The wastewater received by the most upstream anaerobic tank 2 in each row passes through these inflow openings 14a and flows downstream. The anaerobic tanks 2 and aeration tanks 3 in each row are formed symmetrically around the center wall 13, so in the following explanation, the anaerobic tanks 2 and aeration tanks 3 in the upper row in FIG. 1 will be explained. A description of the anaerobic tank 2 and the aeration tank 3 in the lower row in FIG. 1 will be omitted.

Each aeration tank 3 is equipped with a large number of aeration devices 31 at its bottom. A support 33 is fixed to the bottom surface 32 of the aeration tank 3, and an air pipe 34 is attached to the support 33. Each air diffuser 31 is fixed to its air pipe 34, and air is supplied through this air pipe 34. The air diffuser 31 of this embodiment is a membrane type air diffuser. However, other types of air diffusers may be used. The air diffuser 31 is arranged closer to the left side wall 11 side. In this aeration tank 3, air sent from a blower (not shown) is turned into fine bubbles by an aeration device 31 and blown into the wastewater from the bottom of the aeration tank 3. Since the blown air bubbles rise toward the water surface, the air lift effect at this time generates a force that moves the wastewater upward, and an upward flow of the wastewater is generated on the left side wall 11 of the aeration tank 3. On the other hand, a downward flow is generated on the center wall 13 side. As a result, a circulating flow is formed within the aeration tank 3.

Each anaerobic tank 2 includes, at its bottom, a bottom inclined surface 5, a trough 6, a space forming member 7, and a nozzle 8 (see FIG. 3). This nozzle 8 corresponds to an example of a discharge member. The third anaerobic tanks 2 from the most upstream are each equipped with two troughs 6. Further, the anaerobic tank 2 located on the most downstream side is provided with three troughs 6. The trough 6 is a gutter-shaped member that extends in the width direction of the advanced treatment facility 1 from near the left side wall 11 to near the center wall 13 at the bottom of the anaerobic tank 2 . That is, each trough 6 extends in a direction perpendicular to the flow direction of wastewater in the advanced treatment facility 1. Therefore, the width direction of each trough 6 coincides with the flow direction of wastewater in the advanced treatment facility 1. Hereinafter, the width direction of the trough 6 will be referred to as the groove width direction. One space forming member 7 and one nozzle 8 are arranged in each trough 6. The trough 6, the space forming member 7, and the nozzle 8 will be detailed later.

As shown in FIG. 2, the bottom inclined surface 5 is disposed on the upstream side of the trough 6 and on the downstream side of the trough 6 so as to sandwich the trough 6 therebetween. The bottom inclined surface 5 is connected to the edge of a groove 61 (see FIG. 3(b)) formed by the trough 6. The bottom inclined surface 5 is inclined downward toward the edge of the groove 61. As a result, a ridgeline 51, which is the top of the bottom inclined surface 5, is formed between adjacent troughs 6. The angle of inclination of the bottom inclined surface 5 is 30 degrees with respect to the horizontal. This inclination angle may be 15 degrees or more. If the slope angle of the bottom slope 5 is 15 degrees or more, the sludge and the like that have settled toward the bottom slope 5 slide down the bottom slope 5 and settle in the groove 61. Furthermore, if this angle of inclination is 30 degrees or more, sludge and the like that settle toward the bottom slope 5 will more easily slide down the bottom slope 5 and will accumulate on the bottom slope 5. This is more preferable because it can reliably prevent this. Note that the bottom inclined surface 5 in contact with the partition wall 14 is cut at the center in the width direction so as not to block the inflow opening 14a. An inflow path surface 52 formed by a horizontal surface extending between the inflow opening 14a and the groove 61 is provided in this cutout portion.

Next, the configuration of the trough 6, the space forming member 7, and the nozzle 8 (hereinafter, the space forming member 7 and the nozzle 8 are collectively referred to as a stirring device) will be described using FIGS. 3 and 4. The trough 6 and stirring device provided in each anaerobic tank 2 have the same configuration, so in the following explanation, the trough 6 and stirring device provided in the most downstream side of the trough 6 and stirring device shown in FIG. A description will be given of the trough 6 and the stirring device, and other explanations of the trough 6 and the stirring device will be omitted.

FIG. 3(a) is an enlarged view of section C in FIG. 1. FIG.

As shown in FIG. 3(a), the space forming member 7 includes a main body portion 70 and one end portion 71. As shown in FIG. The space forming member 7 is hollow, and one end of the space forming member 7 in the extending direction is open toward the extending direction. This open portion becomes the suction port 7a. An internal space S1 (see FIG. 3(b)) is defined by the inner surface 7i of the space forming member 7. The one end portion 71 has a significantly shorter length in the extending direction (vertical direction in FIG. 3(a)) than the main body portion 70. The main body 70 is supported together with the trough 6 by a support 65. This support body 65 is fixed to concrete, which is the frame of the anaerobic tank 2, with anchor bolts 21. One end portion 71 of the space forming member 7 is detachably attached to the main body portion 70 with a bolt (not shown). The one end portion 71 has a portion that protrudes further toward one end than one end of the trough 6 . One end portion 71 of the space forming member 7 has a one end small diameter portion 711 connected to the main body portion 70, one end enlarged diameter portion 712, and one end large diameter portion 713. The one end side small diameter portion 711 has the same cross-sectional shape as the main body small diameter portion 701 described later, and extends along the extension direction so as to be continuous with the main body portion 70 (main body small diameter portion 701). The one end enlarged diameter portion 712 has a shape that gradually widens in a radial direction perpendicular to the extending direction of the space forming member 7 as it approaches the suction port 7a. The one-end large-diameter portion 713 is located closer to the suction port 7a than the one-end enlarged-diameter portion 712, and extends in parallel along the extending direction. The suction port 7a is defined by the large diameter portion 713 on the one end side. Note that the suction port 7a may be defined by one end of the one end enlarged diameter portion 712 without providing the one end large diameter portion 713. A pair of support pieces 77 that protrude toward the center in the groove width direction are provided inside the large diameter portion 713 on the one end side.

The nozzle 8 is formed by flattening the tip of a round pipe. A discharge port 81 is formed at the tip of the nozzle 8 . Dirty water supplied from the fluid supply pipe 9 is discharged from the discharge port 81. The wastewater discharged from the discharge port 81 corresponds to an example of a fluid. As described above, since the nozzle 8 is formed by crushing a round pipe into a flat shape, the discharge pressure of the wastewater that passes through the nozzle 8 and is discharged from the discharge port 81 can be increased. Further, the nozzle 8 can be manufactured simply by crushing a round pipe, so it is easy to manufacture. A nozzle flange 8a is welded to the rear end of the nozzle 8. Further, a pipe flange 9a is welded to the tip of the fluid supply pipe 9. The nozzle flange 8a and the pipe flange 9a are connected by bolts (not shown). Thereby, the nozzle 8 is detachably attached to the fluid supply pipe 9. Two placement pieces 83 are fixed to the nozzle 8, each protruding outward in the groove width direction. The mounting piece 83 is coupled to the support piece 77 of the space forming member 7 with a bolt 95 (see FIG. 3(b)), so that the nozzle 8 is detachably attached to the space forming member 7. If the connection between the nozzle flange 8a and the pipe flange 9a is released, and the connection between the one end portion 71 of the space forming member 7 and the main body portion 70 is released, the nozzle 8 is removed from the main body portion 70 and the fluid supply pipe 9 together with the one end portion 71. can be removed. Thereafter, by removing the bolt 95 connecting the one end portion 71 and the nozzle 8, the nozzle 8 alone can be taken out. With these, for example, when the nozzle 8 is clogged with water scale, sludge, etc., maintenance work such as removing the water scale, sludge, etc. can be easily carried out.

The nozzle 8 is held by a support piece 77 formed on the space forming member 7 such that the discharge direction of the waste water discharged from the discharge port 81 and the extending direction of the space forming member 7 are substantially the same. Further, the tip side of the nozzle 8 enters into the internal space S1 (see FIG. 3(b)) formed by the space forming member 7 through the suction port 7a. Therefore, the discharge port 81 is arranged within the internal space S1. That is, the discharge port 81 is formed at the tip of the nozzle 8 whose tip end enters the internal space S1 from the suction port 7a of the space forming member 7. Thereby, all of the waste water discharged from the discharge port 81 can be discharged into the internal space S1. However, the discharge port 81 does not need to enter the internal space S1 as long as it can discharge wastewater into the internal space S1, for example, on the surface formed by one end of the space forming member, that is, the same as the suction port 7a. It may be placed at any position. Note that if the discharge port 81 is located outside the internal space S1 and far away from the internal space S1, there is a risk that part of the wastewater discharged toward the internal space S1 may not flow into the internal space S1. It is desirable that the discharge port 81 be disposed within the internal space S1 or close to the suction port 7a.

FIG. 3(b) is a sectional view taken along line EE in FIG. 3(a). In FIG. 3(b), the large diameter portion on the one end side is shown smaller in order to make the drawing easier to read. Further, in FIG. 3(b), the nozzle flange and the pipe flange are not shown.

As shown in FIG. 3(b), the trough 6 is formed by bending a stainless steel plate material so that the cross section has an arc shape with the trough center 6c as the center point. This trough 6 forms a groove 61 at the bottom of the anaerobic tank 2. In other words, the groove 61 is defined by the inner surface 6i of the trough 6. Note that the trough 6 may be made of concrete or may be made of other materials such as resin. Further, the cross-sectional shape of the trough 6 is not limited to a circular arc shape, but may be U-shaped, V-shaped, or the like. The trough 6 of this embodiment has a shape in which the upper third of a cylindrical body having an inner diameter of 300 mm is cut out, and is open upward. The upper end side of the groove 61 connected to the opening of the trough 6 becomes narrower as it approaches the opening.

The space forming member 7 extends along the inner surface 6i of the trough 6. Therefore, the space forming member 7 extends in a direction perpendicular to the flow direction of wastewater in the advanced treatment facility 1. If the extending direction of the space forming member 7 is made parallel to the flow direction of sewage, when the sewage is discharged from the discharge port 81, a circulation flow will be formed in the flow direction of the sewage in the advanced treatment equipment 1. There is a risk that the water may be moved to the anaerobic tank 2 or the aeration tank 3 on the downstream side more than necessary. In the extending direction of the space forming member 7 in a plan view, it is desirable that the angle with respect to the flow of wastewater be 30 degrees or more and 150 degrees or less. The main body portion 70 and one end portion 71 of the space forming member 7 are formed by bending a stainless steel plate material so that the cross section thereof has an arc shape. A lower opening 7d that opens downward is formed in the lower part of the space forming member 7. The radial center of the cross section of the space forming member 7 coincides with the trough center 6c, which is the radial center of the trough 6. Hereinafter, the radial center of the cross section of the space forming member 7 will be simply referred to as the center of the space forming member 7. Although the center of the space forming member 7 may be arranged at a different position from the trough center 6c, it is preferable to arrange the space forming member 7 so that the lower opening 7d is at a position below the opening of the trough 6. Further, the center of the discharge port 81 also coincides with the trough center 6c. By aligning the center of the space forming member 7 with the center of the discharge port 81, it is possible to prevent the wastewater discharged from the discharge port 81 from colliding with the inner surface 7i of the space forming member 7 and weakening the flow. can. However, the center of the space forming member 7 and the center of the discharge port 81 may be arranged at different positions. For example, the center of the discharge port 81 may be arranged below the center of the space forming member 7 and above the lower opening 7d. With this arrangement, it is possible to increase the force for sucking sewage, precipitated sludge, etc. into the internal space S1 from the lower opening 7d, which will be described later. That is, it is desirable that the center of the discharge port 81 be disposed between the center of the space forming member 7 and the lower opening 7d of the space forming member 7.

The space forming member 7 partitions the inside of the groove 61 and forms an internal space S1. The internal space S1 is a space whose portion above the lower end is closed. The main body portion 70 of the space forming member 7 is composed of a main body small diameter portion 701 and an enlarged diameter portion 702 at the other end (see FIG. 4), which will be described later. The main body small diameter portion 701 and the one end side small diameter portion 711 have a cross-sectional shape of a 5/6 arc with the lower end portion of a cylindrical body having an inner diameter of 150 mm cut. Furthermore, the positions in the height direction of the lower end of the one end side small diameter portion 711, the lower end of the one end side enlarged diameter portion 712, and the lower end of the one end side large diameter portion 713 are the same. That is, the one end portion 71 has a shape in which the entire lower end is cut horizontally. As a result, the one-end large diameter portion 713 has a cross-sectional shape of about ⅔ arc with the lower end portion of a cylindrical body having an inner diameter of 300 mm cut off. The suction port 7a (see FIG. 3(a)) is formed in a portion surrounded by one end of the one-end large diameter portion 713, and has a circular shape with a diameter of 300 mm with the lower end portion missing. The lower opening 7d formed at the lower end portion of the space forming member 7 acts as a suction port for sucking the sewage, precipitated sludge, etc. in the groove 61 into the internal space S1. The lower opening 7d is formed in the entire area of the space forming member 7 in the extending direction. Therefore, the lower opening 7d is also formed in the one end enlarged diameter portion 712 and the one end large diameter portion 713. There may be a part in the extending direction of the space forming member 7 in which the lower opening 7d is not formed, but in that part, sewage, precipitated sludge, etc. cannot be sucked into the internal space S1, and the precipitated sludge, etc. Since there is a possibility that the lower opening 7d may remain, it is desirable to form the lower opening 7d in the entire area in the extending direction. The lower opening 7d formed in the main body small diameter portion 701 and the one end portion 71 is formed to have a length of 80 mm in the groove width direction. The lower opening 7d of the one end side large diameter portion 713 is formed to have a length of about 270 mm in the groove width direction. The lower opening 7d is arranged within the groove 61, except for both end portions where the space forming member 7 protrudes from the groove 61 in plan view. Therefore, the lower opening 7d is arranged below the upper edge of the groove 61. Further, the lower opening 7d is spaced apart from the inner surface 6i of the trough 6. Specifically, the lower opening 7d is disposed at a position where the distance in the height direction from the lowermost portion 6b of the inner surface 6i of the trough 6 is 84 mm. The distance in the height direction from the lowest part 6b to the lower opening 7d is preferably 40 mm or more and 200 mm or less. If it is less than 40 mm, the gap between the edge of the lower opening 7d and the trough 6 will be too narrow, and there is a risk that larger debris that has passed through the settling basin or the like for some reason may become clogged in the gap. Moreover, if it is 200 mm or more, the lowest part 6b and the lower opening 7d are too far apart, so that the sludge etc. that have settled near the lowermost part 6b cannot be sucked into the internal space S1 from the lower opening 7d. Note that the relative position of the space forming member 7 in the height direction with respect to the trough 6 may be made adjustable. By making the heightwise position of the space forming member 7 freely adjustable, the space forming member 7 can be placed at an optimal position corresponding to the sewage treatment facility. The inner surface 6i of the trough 6, the inflow path surface 52, and the bottom inclined surface 5 (see FIG. 2) correspond to an example of the bottom surface. Since the outer surface of the space forming member 7 is arc-shaped, the portion above the center of the circle having this arc as part of the circumference is inclined downward as it goes outward in the groove width direction. Therefore, the sludge and the like that have settled toward the outer surface of the space forming member 7 tend to slide down the outer surface of the upper portion of the space forming member 7 toward the bottom of the groove 61 . By this. It is possible to prevent sludge and the like from accumulating on the upper portion of the space forming member 7. Further, due to the lower portion of the space forming member 7, the inner space S1 becomes narrower as the lower end portion connected to the lower opening 7d approaches the lower opening 7d. For this reason, sludge and the like once sucked into the internal space S1 are less likely to leak out from the internal space S1.

FIG. 4(a) is an enlarged view showing section D in FIG. 1, and FIG. 4(b) is a sectional view taken along line FF in FIG. 4(a). In FIG. 4(b), the outer diameter of the discharge port is shown to be smaller in order to make the drawing easier to read.

As shown in FIG. 4(a), the other end portion of the space forming member 7 further protrudes from the other end of the trough 6 toward the other end. The other end of the space forming member 7 in the extending direction is open toward the extending direction. This open portion becomes the discharge port 7b. The other end portion of the space forming member 7 is formed with an enlarged diameter portion 702 having a shape that gradually widens in a radial direction perpendicular to the extending direction of the space forming member 7 toward the discharge port 7b. The other end enlarged diameter portion 702 is formed symmetrically with the one end enlarged diameter portion 712 with respect to a plane of symmetry that is perpendicular to the extending direction of the space forming member 7 . Therefore, as shown in FIG. 4(b), the discharge port 7b has a circular shape with a diameter of 300 mm with the lower end portion notched, which is formed in a portion surrounded by the other end of the other end side enlarged diameter portion 702. There is. That is, the discharge port 7b has the same shape as the suction port 7a.

FIG. 5 is a BB sectional view of the anaerobic tank shown in FIG. 2. In FIG. 5, the intermediate portion of the fluid supply pipe is shown in a simplified manner.

As shown in FIG. 5, the suction port 7a faces the lower end portion of the left wall surface 111, which is the inner surface of the left wall 11. As shown in FIG. This left wall surface 111 corresponds to an example of a first wall surface. Further, the discharge port 7b faces the lower end portion of the center wall surface 131, which is the left side surface of the center wall 13. This central wall surface 131 corresponds to an example of a second wall surface. A first inclined surface 111a that approaches the suction port 7a as it goes downward is formed at the lower end portion of the left wall surface 111. The sludge and the like that have settled toward the first inclined surface 111a slide down the first inclined surface 111a due to the inclination and settle in the vicinity of the suction port 7a. Furthermore, when wastewater is discharged from the discharge port 81, a portion near the first inclined surface 111a is located along the inclination of the first inclined surface 111a toward the suction port 7a, as shown by an arcuate arrow at the lower right of FIG. A flow of sewage towards the Due to this flow of sewage, sludge and the like that have settled near the suction port 7a move toward the suction port 7a side. Due to this flow and the ejector effect of the space forming member 7, the settled sludge, etc. is sucked into the internal space S1 (see FIG. 3(b)) in the space forming member 7, so that the sludge, etc. is deposited near the lower end of the left wall surface 111. Precipitation and stagnation can be prevented. Although the first inclined surface 111a in this embodiment has an arcuate shape concave downward, it may have a planar shape.

A second inclined surface 131a is formed at the lower end of the central wall surface 131 and approaches the discharge port 7b as it goes downward. When the waste water is discharged from the discharge port 81, the waste water is discharged from the discharge port 7b. The sewage discharged from the discharge port 7b rises smoothly upward along the second inclined surface 131a, as shown by the arcuate arrow at the lower left of FIG. A strong circulating flow is formed above the member 7. The second inclined surface 131a may be planar. However, by forming the second inclined surface 131a in a downwardly concave arc shape, the flow of wastewater discharged from the discharge port 7b in a generally horizontal direction can be made smoother than in the case where the second inclined surface 131a is formed in a flat shape. Since it can be converted upward, it has the effect of reducing flow loss compared to a planar shape.

The fluid supply pipe 9 extends upward from the bottom of the anaerobic tank 2 along the left wall surface 111. A flow rate adjustment valve 91 and an electric valve 92 are installed on the upper end side of the fluid supply pipe 9. In addition, in FIG. 5, the fluid supply pipe 9 located above the flow rate adjustment valve 91 is not shown. This fluid supply pipe 9 is connected to a pump (not shown) disposed within the advanced treatment facility 1 . By opening the electric valve 92, sewage sucked up by a pump (not shown) is supplied to the nozzle 8 through the fluid supply pipe 9, and the sewage is discharged from the discharge port 81 provided in the nozzle 8. In addition, two upper inflow ports 14b through which dirty water can pass are provided at the upper part of the partition wall 14, similar to the inflow openings 14a.

Next, the effect when wastewater is discharged from the discharge port 81 will be explained using mainly FIGS. 3 and 5. In the anaerobic tank 2, wastewater is always discharged from the discharge port 81, except in special situations such as during maintenance. In this embodiment, the discharge pressure of the waste water discharged from the discharge port 81 is 0.09 MPa, and the discharge water amount is 1.5 m3/min. However, as will be described later, the discharge pressure may be 0.001 MPa or more, and the discharge water amount may be 0.3 m3/min or more. In addition, the discharge flow rate of wastewater is preferably 2 m/sec or more and 32 m/sec or less. If the discharge flow rate is less than 2 m/sec, the circulating flow within the anaerobic tank 2 formed by the wastewater discharged from the discharge port 7b will be weak, and there is a possibility that sludge and the like will not be able to be circulated. When the discharge flow velocity exceeds 32 m/sec, the circulation flow becomes too strong, and air is drawn in at the water surface and air is supplied to the wastewater. By discharging wastewater from the discharge port 81 into the internal space S1, a flow of wastewater is generated in the internal space S1. At this time, the flow of wastewater inside the interior space S1 causes a pressure difference between the inside of the interior space S1 and the outside of the interior space S1. That is, negative pressure is generated in the internal space S1 where the flow of wastewater is occurring. The sludge and the like that have settled in the groove 61 are sucked into the internal space S1 from the lower opening 7d by the negative pressure, as shown by the curved arrow shown in FIG. 3(b), together with the surrounding sewage. In order to obtain the negative pressure necessary to suck in sludge and the like, it is preferable that the flow rate of the sewage flowing in the internal space S1 is set to 0.1 m/sec or more. In addition, since the wastewater discharged from the discharge port 81 is prevented from spreading in the radial direction perpendicular to the extending direction of the space forming member 7 by the space forming member 7, the flow is maintained within the internal space S1 over a long distance. be done. The sewage, sludge, etc. sucked into the internal space S1 move toward the discharge port 7b while being mixed with the sewage due to the flow of sewage generated within the internal space S1, and are discharged from the discharge port 7b. If the discharge pressure is less than 0.001 MPa, sludge and the like moving within the internal space S1 will easily leak down from the lower opening 7d. Similarly, when the amount of discharged water is less than 0.3 m3/min, sludge and the like moving within the internal space S1 tend to leak from the lower opening 7d. In addition, in consideration of pump capacity and power consumption, the discharge pressure is preferably 0.3 MPa or less, and the discharge water amount is preferably 3.0 m3/min or less. As described above, the wastewater discharged from the discharge port 7b smoothly rises upward along the second inclined surface 131a, forming a strong circulating flow above the space forming member 7.

According to this embodiment, by discharging sewage from the discharge port 81 into the internal space S1, sludge, etc. that have settled in the groove 61 are sucked into the internal space S1, moved while being stirred, and discharged from the discharge port 7b. Can be done. Then, the wastewater mixed with sludge and the like discharged from the discharge port 7b can be circulated in the anaerobic tank 2 in a circulating flow. Therefore, the sludge or the like that has settled in the groove 61 can be stirred.

Next, the anaerobic tank 2 of the second embodiment will be explained. In the explanation that follows, constituent elements having the same names as those explained so far will be explained using the same reference numerals, and redundant explanations may be omitted.

FIG. 6 is a sectional view similar to FIG. 2 of the advanced processing equipment 1 of the second embodiment. In FIG. 6, the left side of the figure is the upstream side and the right side is the downstream side.

The advanced treatment equipment 1 shown in FIG. 6 differs from the advanced treatment equipment 1 shown in the previous embodiment in the shape of the bottom of the anaerobic tank 2. As shown in FIG. 6, in this anaerobic tank 2, a bottom inclined surface 5 and a trough 6 are not formed at the bottom, and a bottom surface 50 that is a flat surface is formed at the bottom. Furthermore, in this embodiment, more space forming members 7 are arranged than in the previous embodiment. Specifically, the three anaerobic tanks 2 from the most upstream are each provided with three space forming members 7. The anaerobic tank 2 located on the most downstream side includes five space forming members 7. The lower opening 7d of the space forming member 7 is spaced apart from the bottom surface 50. Specifically, the lower opening 7d is arranged at a position where the distance in the height direction from the bottom surface 50 is 84 mm. Note that, for the same reason as in the previous embodiment, the distance in the height direction between the lower opening 7d and the bottom surface 50 is preferably 40 mm or more and 200 mm or less. Discharge ports 81 for discharging fluid into the internal space S1 are arranged in each of the space forming members 7.

Also in the anaerobic tank 2 of this embodiment, by discharging wastewater from the discharge port 81, a circulating flow is formed above the space forming member 7. The sludge, etc. that has accumulated below the space forming member 7 and near the space forming member 7, together with the surrounding sewage, is discharged from the lower opening 7d into the internal space S1 by negative pressure, as shown by the curved arrow in FIG. be sucked into. The sucked sludge and the like are then circulated along the circulation flow formed above. However, if the distance between the adjacent space forming members 7 is wide, there is a risk that the sludge or the like that has settled on the bottom surface 50 located at the intermediate position between the adjacent space forming members 7 may remain accumulated. As a countermeasure against this, by arranging a large number of space forming members 7 as described above, the spaces between adjacent space forming members 7 are narrowed, and sludge etc. that have settled on the bottom surface 50 located in the middle position are not left to accumulate. This prevents this from happening. Note that instead of increasing the number of space-forming members 7 arranged, a linear motion mechanism may be provided that moves the space-forming members 7 and the discharge ports 81 in the flow direction of wastewater using an electric motor such as a motor. When this linear motion mechanism is provided, it is preferable to move the space forming member 7 together with the discharge port 81 from the vicinity of the upstream end of the anaerobic tank 2 to the vicinity of the downstream end while discharging wastewater from the discharge port 81. Further, a rotation mechanism may be provided in which the space forming member 7 is rotated by an electric motor along the bottom surface 50, centering on the central portion in the extending direction of the space forming member 7. When this rotation mechanism is provided, it is preferable to rotate the space forming member 7 parallel to the bottom surface 50 while discharging wastewater from the discharge port 81. In this operation, it is desirable that the space forming member 7 be rotated by an angle of less than 150 degrees clockwise and counterclockwise, respectively. If it is rotated by more than 150 degrees, a circulation flow will be formed in the flow direction of the wastewater, and there is a possibility that the wastewater will be moved to the anaerobic tank 2 or the aeration tank 3 on the downstream side more than necessary. According to the aspect in which these linear motion mechanisms or rotation mechanisms are provided, the entire bottom surface 50 of the anaerobic tank 2 can be covered by a single space forming member 7, so that one space forming member 7 is provided for each anaerobic tank 2. All the sludge etc. deposited on the bottom surface 50 can be sucked up and stirred just by placing it. According to this embodiment, the sludge or the like that has settled on the bottom surface 50 can be stirred without forming the bottom inclined surface 5 or the trough 6 in the anaerobic tank 2.

Next, a modification of the anaerobic tank 2 that has been described so far will be described, focusing on the differences from the configuration that has been described so far.

FIG. 7(a) is a sectional view showing a modification of one end portion of the space forming member shown in FIG. 3(b).

As shown in FIG. 7(a), in the space forming member 7 of this modification, the one end side enlarged diameter part 712 and the one end side large diameter part 713 have grooves compared to the space forming member 7 shown in FIG. The difference is that it does not expand in the width direction and the positions where the support piece 77 and the mounting piece 83 are provided. That is, the one end enlarged diameter portion 712 and the one end large diameter portion 713 have a shape that expands only upward relative to the one end small diameter portion 711. A support piece 77 that protrudes downward from the upper end portion is provided inside the large diameter portion 713 on the one end side. Furthermore, a placement piece 83 that protrudes upward from the upper end portion is fixed to the nozzle 8 . The mounting piece 83 is coupled to the support piece 77 with the bolt 95, so that the nozzle 8 is detachably attached to the one end portion 71 of the space forming member 7.

FIG. 7(b) is a sectional view showing a modification of the other end portion of the space forming member shown in FIG. 4(b).

As shown in FIG. 7(b), in the space forming member 7 of this modification, the enlarged diameter portion 702 on the other end side is not expanded in the width direction compared to the space forming member 7 shown in FIG. are different. That is, the other end side enlarged diameter portion 702 has a shape that expands only upward with respect to the main body small diameter portion 701. In this modification, the large diameter portion 713 on the one end side expands only upward, so that when waste water is discharged from the discharge port 81, a stronger circulating flow is likely to be formed above the space forming member 7.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, in this embodiment, the stirring tank of the present invention is applied to the anaerobic tank 2, but it may also be applied to the aeration tank 3 or an anoxic tank. When applied to the aeration tank 3, another outlet for supplying wastewater containing air or bubbles may be provided around or near the outlet 81, or air or bubbles may be added to the wastewater in the middle of the fluid supply pipe 9. It is sufficient if the liquid is discharged from the discharge port 81. In this case, the bubbles are preferably nanobubbles with a diameter of 1 μm or less. Nanobubbles can efficiently supply oxygen to aerobic bacteria because they have a larger total surface area than larger diameter bubbles of the same volume. Moreover, since nanobubbles have almost no buoyancy, they can circulate within the aeration tank 3 for a long time. When applied to the aeration tank 3, the flow rate of sewage flowing through the internal space S1 in the aeration tank 3 may be faster than the flow rate of sewage flowing through the internal space S1 in the anaerobic tank 2. When the flow rate of sewage flowing through the internal space S1 becomes faster, the circulation flow becomes stronger and air may be drawn in at the water surface and air may be supplied to the sewage, but it is preferable that air be supplied to the aeration tank 3. It is from. In other words, the flow rate of sewage flowing through the internal space S1 in the anaerobic tank 2 is preferably equal to or lower than the flow rate of the sewage flowing through the internal space S1 in the aeration tank 3. When applied to an anoxic tank, a device for adding nitric acid or the like may be placed in the tank. Furthermore, the stirring tank of the present invention may be used in facilities other than sewage treatment facilities, such as a tank for mixing two or more types of fluids and a tank for uniformly dispersing various powders, chemicals, etc. in the fluid. .

According to the embodiments and modifications described above, the sludge and the like that have settled at the bottom are sucked up and moved together with the sewage into the internal space S1, thereby making it possible to stir the sludge and the sewage.

Note that even if the constituent features are included only in the descriptions of the embodiment and each modification described above, the constituent features may be applied to other embodiments and other modifications.

The stirring tank described so far is a stirring tank that stirs the received liquid,
Formation of a hollow space extending along the bottom surface formed at the bottom of the stirring tank and having an inlet provided at one end in the extending direction and an outlet provided at the other end in the extending direction. parts and
and a discharge port for discharging fluid into the internal space defined by the inner surface of the space forming member,
The space forming member may be characterized in that a lower opening spaced apart from the bottom surface is formed in a lower portion.

The stirring tank described so far is a stirring tank that stirs the received liquid by circulating flow,
Formation of a hollow space extending along the bottom surface formed at the bottom of the stirring tank and having an inlet provided at one end in the extending direction and an outlet provided at the other end in the extending direction. parts and
a discharge port for discharging fluid substantially in the extending direction into the internal space defined by the inner surface of the space forming member;
The space forming member has a lower opening provided along the extending direction in a lower portion thereof and spaced apart from the bottom surface,
The suction port and the lower opening suck surrounding liquid into the internal space when fluid is discharged from the discharge port,
The discharge port is characterized in that the circulating flow is formed by discharging the fluid discharged from the discharge port and the liquid sucked in from the suction port and the lower opening.

Here, the discharge port may be arranged within the internal space, or may be arranged outside the internal space. Further, the lower opening may be formed along the extending direction. Furthermore, the lower opening may be formed over the entire length of the space forming member in the extending direction, or may be formed in multiple locations along the extending direction. good. In addition, the ejection port may eject only liquid or may eject liquid containing bubbles. Further, a second discharge port for discharging bubbles or a liquid containing bubbles into the internal space may be provided separately from the discharge port. Furthermore, these bubbles may be nanobubbles with a diameter of 1 μm or less. Further, the space forming member may have an arcuate cross-sectional shape. Further, the inner space may have a lower end portion connected to the lower opening that becomes narrower as it approaches the lower opening.

According to this stirring tank, the fluid discharged from the discharge port into the internal space is diffused in the radial direction perpendicular to the predetermined direction except for the portion where the lower opening is formed. , creating a strong flow of fluid in the interior space. This flow creates a pressure difference between the inside and outside of the space forming member, and the sludge and the like that have settled at the bottom of the stirring tank are sucked into the internal space through the lower opening together with the liquid around the lower opening. The sucked sludge and the like move through the inner space while being mixed with the sucked liquid and fluid due to the flow of fluid in the inner space, and are discharged from the discharge port together with the liquid and the like. A circulating flow is formed in the stirring tank by the discharged liquid containing the sludge, etc., and the sludge, etc. circulates within the stirring tank along with the circulating flow. Therefore, the sludge and the like that have settled at the bottom of the stirring tank can be reliably stirred.

In this stirring tank, a groove provided in the bottom and extending in the same direction as the extending direction;
a bottom inclined surface provided on the bottom, connected to the edge of the groove, and directed downward toward the edge of the groove;
The lower opening may be disposed within the groove.

According to this aspect, sludge or the like that is about to settle on the bottom slope is likely to slide down the bottom slope and settle into the groove, so that It can be sucked into the internal space. Therefore, it is possible to prevent sludge and the like from settling and remaining on the bottom inclined surface.

Furthermore, in this stirring tank, the space forming member may have a shape in the one end portion that gradually expands in a radial direction perpendicular to the extending direction toward the suction port.

By doing so, more liquid can be sucked through the suction port, thereby creating a stronger circulating flow. Note that the one end portion does not have to have a shape that spreads in all directions in the radial direction, such as a shape that spreads only in the upward direction.

Further, in this stirring tank, the space forming member may have a shape at the other end that gradually expands in a radial direction perpendicular to the extending direction toward the discharge port.

By doing so, the liquid that has reached the other end portion is emitted from the outlet while spreading in the radial direction, so that a circulation flow can be formed over a wider range. Note that the other end portion does not have to have a shape that spreads in all directions in the radial direction, such as a shape that spreads only in the upward direction.

Further, in this stirring tank, the suction port is arranged to face a lower end portion of the first wall surface of the stirring tank,
The lower end portion of the first wall surface may have a first inclined surface that approaches the suction port as it goes downward.

Sludge and the like that are about to settle on the first inclined surface tend to slide down the first inclined surface and settle near the suction port. Further, since the flow of liquid generated near the first slope when the fluid is discharged from the discharge port heads toward the suction port along the slope of the first slope, precipitation occurs near the suction port. The collected sludge and the like are easily sucked in toward the suction port along the flow of the liquid. Therefore, it is possible to prevent sludge and the like from settling and remaining in the vicinity of the lower end portion of the first wall surface.

Further, in this stirring tank, the discharge port is arranged opposite to the lower end portion of the second wall surface of the stirring tank,
The lower end portion of the second wall surface may have a second inclined surface that approaches the discharge port as it goes downward.

Since the liquid discharged from the discharge port smoothly rises upward along the second inclined surface, flow loss is reduced and a stronger circulating flow can be formed above the space forming member. can.

In addition, the stirring tank described so far is a stirring tank that stirs the received liquid by circulating flow,
A hollow space forming member that extends along the bottom surface formed at the bottom of the stirring tank and has a discharge port provided at an end in the extending direction;
a discharge port configured to discharge fluid toward the extending direction into an internal space defined by the inner surface of the space forming member;
The space forming member has a lower opening provided along the extending direction in a lower portion thereof and spaced apart from the bottom surface, and is formed throughout the entire area in the extending direction;
The lower opening sucks surrounding liquid into the internal space when fluid is discharged from the discharge port,
The discharge port is characterized in that the circulating flow is formed by discharging the fluid discharged from the discharge port and the liquid sucked in from the lower opening.

Also, a stirring tank that stirs the received liquid by circulating flow,
A hollow space forming member that extends along the bottom surface formed at the bottom of the stirring tank and has a discharge port provided at an end in the extending direction;
a discharge port for discharging fluid substantially in the extending direction into the internal space defined by the inner surface of the space forming member;
The space forming member has a lower opening provided along the extending direction in a lower portion and spaced apart from the bottom surface,
The lower opening sucks surrounding liquid into the internal space when fluid is discharged from the discharge port,
The discharge port may form the circulating flow by discharging the fluid discharged from the discharge port and the liquid sucked in from the lower opening.

Further, in this stirring tank, a groove provided at the bottom and extending in the same direction as the extending direction;
a bottom inclined surface provided on the bottom, connected to the edge of the groove, and directed downward toward the edge of the groove;
The lower opening may be disposed within the groove.

1 Advanced treatment equipment 2 Anaerobic tank 6 Trough 6i Inner surface 7 Space forming member 7a Inlet 7b Discharge port 7d Lower opening 50 Bottom surface 81 Discharge port S1 Internal space

Claims (3)

A stirring tank that stirs the received liquid by a circulating flow while the liquid flows in the flow direction,
A hollow space forming member that extends along the bottom surface formed at the bottom of the stirring tank and has a discharge port provided at an end in the extending direction;
a discharge port configured to discharge fluid toward the extending direction into an internal space defined by the inner surface of the space forming member;
The space forming member has a lower opening spaced apart from the bottom surface formed in a lower portion thereof, and extends in a direction at an angle of 30 degrees or more and 150 degrees or less in plan view with respect to the flow direction,
The lower opening sucks surrounding liquid into the internal space when fluid is discharged from the discharge port,
The stirring tank is characterized in that the discharge port forms the circulation flow by discharging the fluid discharged from the discharge port and the liquid sucked in from the lower opening. A stirring tank that stirs the received liquid by a circulating flow while the liquid flows in the flow direction,
A hollow space forming member that extends along the bottom surface formed at the bottom of the stirring tank and has a discharge port provided at an end in the extending direction;
a discharge port configured to discharge fluid toward the extending direction into an internal space defined by the inner surface of the space forming member;
The space forming member has a lower opening spaced apart from the bottom surface formed in a lower portion thereof, and extends in a direction perpendicular to the flow direction in plan view;
The lower opening sucks surrounding liquid into the internal space when fluid is discharged from the discharge port,
The stirring tank is characterized in that the discharge port forms the circulation flow by discharging the fluid discharged from the discharge port and the liquid sucked in from the lower opening. The stirring tank according to claim 1 or 2, wherein the space forming member is arranged in an area partitioned by a partition wall.