JP6674743B2 - Seal pit for drainage - Google Patents

Description

  The present invention relates to a seal pit for drainage.

  For example, in a thermal power plant, wastewater generated during operation is purified by a wastewater treatment facility, and then discharged to rivers and the ocean through pipes installed toward the water surface. At this time, if there is a large separation between the pipe and the water surface, foam is formed on the water surface by entraining the surrounding air while the drainage reaches the water surface. In particular, foams formed on the surface of seawater may stay on the surface of water for a long time and sometimes fly around due to wind waves. The occurrence of such foam is not only unfavorable in appearance but also considered to be an event that should be avoided from the viewpoint of environmental protection of rivers and oceans.

  As a technique for suppressing the generation of foam as described above, for example, a technique described in Patent Document 1 below is known. The seal pit for drainage described in Patent Literature 1 has a barrier wall for blocking drainage, a water inlet through which drainage is guided from one side of the barrier, and a water outlet through which the drainage is discharged toward the other side. And a plurality of communication tubes having The water outlet is disposed so as to be immersed in the water below the lower limit water level of the downstream water surface from which drainage is discharged. Further, an overflow pipe is provided at a further upper portion of the plurality of connecting pipes for discharging the drainage stored by the dam wall to the downstream side when the water level exceeds the upper limit. Thereby, since the area where the wastewater contacts the air is limited, generation of foam can be suppressed.

JP 2003-268749 A

However, in the seal pit for drainage described in Patent Literature 1, an outlet of an overflow pipe for discharging the drainage stored by the dam wall when the drainage exceeds the upper limit water level is provided above the water surface. I have. Therefore, the waste water discharged from the overflow pipe comes into contact with air while reaching the water surface. This may cause foam to form on the water surface.
Furthermore, the provision of a plurality of communication tubes may complicate the configuration, which may lead to an increase in cost.

  The present invention has been made in view of such circumstances, and has as its object to provide a drainage seal pit that is inexpensive and has a sufficient defoaming effect.

In order to solve the above problems, the present invention employs the following means.
A drainage seal pit according to one embodiment of the present invention includes a drainage pipe having a drainage outlet for discharging drainage, a water storage area for storing wastewater discharged by the drainage pipe, and a discharge area where the wastewater in the water storage area is discharged. And a weir formed with a through-hole communicating the water storage area and the discharge area below the lowest water level of the discharge area, and the cross-sectional area of the flow path of the through-hole is The drain port is set to be lower than the water level of the drainage stored in the water storage area, and the water level of the stored drainage is set so as not to exceed the height of the weir even at the time of maximum drainage. An inflow port, which is an end of the through hole on the storage area side, and an outflow port, which is an end on the opposite side, are located below the lowest water level in the discharge area , and the water bottom of the storage area and the discharge port The water bottom of the basin extends at the same height as And a buffer weir provided in the area for partitioning the water storage area into a first section and a second section, wherein the first section stores drainage discharged by the drain pipe, and has a height of the buffer weir. The dimension in the height direction is smaller than the dimension in the height direction of the weir, and the upper end of the buffer weir is located above the position in the height direction of the drain port .

According to the above configuration, since the drain port of the drain pipe is located below the water level of the drain water in the water storage area, the drain water discharged from the drain port does not involve outside air. In addition, the drainage does not collide with the water surface of the reservoir. Thereby, the possibility that a foam will be generated on the water surface of the water storage area can be reduced.
Further, when the water level of the discharge area is equal to or higher than the lowest water level and lower than the maximum water level of the discharge area, the entire amount of the drainage water from the water storage area can be discharged to the discharge area through the through hole. Accordingly, when the drainage flows into the discharge area, the outside air is not involved. Therefore, generation of foam on the water surface can be suppressed.
In addition, even if the water level of the discharge area is at the highest level, most of the drainage is discharged from the reservoir area to the discharge area through the through hole. On the other hand, even if the drainage gets over (overflow) at the upper part of the weir, the water level difference between the reservoir area and the discharge area is small because the discharge area is at the highest water level. Therefore, the drainage overflowing the weir does not strongly collide with the water surface. That is, generation of foam on the water surface can be reduced.
Furthermore, according to the above-described configuration, by providing the buffer weir, the water level of the wastewater in the first section is maintained at substantially the same height as the height of the buffer weir throughout the discharge of the wastewater. In other words, by providing the buffer weir, it is possible to reduce the possibility that the outlet of the drain pipe is exposed above the water surface.
In addition, by providing this buffer weir, it is possible to reduce the possibility that a change in the water level of the discharge area directly reaches the water storage area through the through hole.

  In the seal pit for drainage according to one aspect of the present invention, the weir may include an adjustment valve that is provided inside the through-hole and that changes the cross-sectional area of the flow path by adjusting an opening degree. .

  According to the above-described configuration, by adjusting the opening degree of the adjustment valve, the flow path cross-sectional area of the through hole can be changed. That is, by adjusting the opening of the regulating valve according to the water level of the wastewater in the water storage area, the water level of the wastewater in the water storage area can be appropriately maintained.

  In the seal pit for drainage according to one aspect of the present invention, the weir protrudes inward from the inner peripheral surface of the through-hole, thereby narrowing the cross-sectional area of the flow passage at a part of the through-hole. A region of the through hole closer to the water storage area than the constricted portion forms a bell mouth portion by gradually decreasing the cross-sectional area of the flow path from the water storage region toward the constricted portion. You may.

  According to the configuration as described above, the bell mouth portion can reduce the inflow resistance to the drainage flowing into the through hole from the water storage area side.

  In the drainage seal pit according to one aspect of the present invention, the area of the through hole closer to the discharge area than the constricted portion has a linear opening dimension of the through hole from the constricted portion toward the discharge area. The diffuser portion may be formed by increasing the number of times.

  According to the above-described configuration, the provision of the diffuser increases the static pressure of the drainage on the discharge area side of the through hole. Along with this, the static pressure of the drainage in the constriction also increases. Thereby, the static pressure difference of the drainage between the water storage area side of the through hole and the constricted portion is reduced. Therefore, more wastewater can be made to flow into the through-hole as compared with the case where the diffuser portion is not provided. In other words, by providing the diffuser portion, the flow passage cross-sectional area of the through hole can be further reduced.

  The drainage seal pit according to one aspect of the present invention, on the discharge area side, extends along the weir, and has an opposing wall facing the through-hole at an interval in the penetrating direction of the through-hole from the weir. May have.

According to the above configuration, when an external flow including a tidal current on the discharge area side flows toward the weir, the influence of the flow on the drainage performance of the through hole can be reduced. That is, when an external flow toward the weir (through-hole) occurs, pressure is applied from the discharge area side of the through-hole toward the water storage area, so that the flow of drainage may be obstructed.
However, by providing the above-mentioned opposed wall, the possibility that a tidal current or the like directly flows into the through hole can be reduced. That is, the drainage can be stably discharged from the through hole.

  In the drainage seal pit according to one aspect of the present invention, a surface of the opposed wall facing the through hole may be curved toward the through hole in a plan view.

  According to the above configuration, when the flow of the drainage discharged from the through hole toward the discharge area collides with the opposing wall, the flow can be dispersed along the curved shape of the opposing wall. Thereby, the possibility that the flow of the drainage that has collided with the opposing wall flows backward toward the through-hole can be reduced.

  In the drainage seal pit according to one aspect of the present invention, a surface of the opposite wall opposite to the through hole may be curved in a direction away from the through hole in plan view.

According to the above-described configuration, when an external flow flowing from the direction opposite to the weir toward the opposing wall collides with the opposing wall, the flow can be dispersed along the curved shape of the opposing wall.
In the seal pit according to one aspect of the present invention, the through hole may be formed only in the weir among the weir and the buffer weir.

  According to the present invention, it is possible to provide a drainage seal pit which is inexpensive and has a sufficient defoaming effect.

It is a figure showing the seal pit for drainage concerning a first embodiment of the present invention. It is a figure showing the operation state of the seal pit for drainage concerning a first embodiment of the present invention. It is a figure showing the operation state of the seal pit for drainage concerning a first embodiment of the present invention. It is a figure showing the modification of the seal pit for drainage concerning a first embodiment of the present invention. It is an important section enlarged view of a seal pit for drainage concerning a second embodiment of the present invention. It is a principal part enlarged view which shows the modification of the seal pit for drainage which concerns on 2nd embodiment of this invention. It is a top view showing the seal pit for drainage concerning a third embodiment of the present invention. It is a top view showing the modification of the seal pit for drainage concerning a third embodiment of the present invention. It is a top view showing other modifications of a seal pit for drainage concerning a third embodiment of the present invention. It is a figure showing static pressure distribution of the drainage which flows through a penetration hole concerning a second embodiment of the present invention.

[First embodiment]
A first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the seal pit 100 for drainage includes a drainage pipe 1 for discharging drainage generated in a plant or the like to an external drainage area A, and dams the drainage and divides the drainage area A into two sections. There is provided a weir 2 and a buffer weir 3 provided between the weir 2 and the drain pipe 1.

  For example, in a thermal power plant, a large amount of water is used for supplying water to a steam turbine facility for driving a generator and for cooling each part of the facility. Of such water, unnecessary water is purified by a purification facility and then discharged to the outside. The above drain pipe 1 is laid inside and outside the plant in order to discharge such waste water.

  In the present embodiment, the drainage pipe 1 extends toward the outside ocean or river (drainage area A), which extends across the plant quay 4. One end of the drain pipe 1 is connected to plant equipment (not shown), and the other end is bent toward the water surface of the drain area A. Thus, the drain pipe 1 has a substantially L-shape. The height H from the water bottom B to the drain port 11 is set lower than the above-mentioned storage water level RWL. That is, the drain port 11 is immersed below the surface of the water storage area A1. In addition, the inside of the drain pipe 1 is almost completely filled with water (drain). As a result, a difference (pressure difference) is generated in the static pressure of the drain water between the drain port 11 side and the plant side. The drainage is discharged from the drainage port 11 below the surface of the water storage area A1 by the siphon effect based on the pressure difference.

A weir 2 is provided at a position on the water bottom B of the drainage area A, which is separated from the plant quay 4 by a certain distance. In the drainage area A, an area surrounded by the weir 2 and the plant quay 4 is a water storage area A1, and an outer area adjacent to the weir 2 is a discharge area A2. That is, the water storage area A1 is closed by being surrounded by the plant quay 4 and one surface of the weir 2. On the other hand, the discharge area A2 is a remaining area excluding the water storage area A1 from the drainage area A.
In the following description, a direction from the water storage area A1 toward the discharge area A2 with respect to the weir 2 is referred to as a discharge direction, and a direction opposite to the discharge direction is referred to as an inflow direction.

  The buffer weir 3 is provided between the above-mentioned weir 2 and the plant quay 4, that is, in the water storage area A1. With this buffer weir 3, the water storage area A1 is partitioned into a first section A11 and a second section A12. More specifically, a section located on the plant quay 4 side is referred to as a first section A11, and a section opposite to the buffer dam 3 is referred to as a second section A12.

  The dimension in the height direction of the buffer weir 3 is set smaller than the dimension in the height direction of the weir 2 described above. Further, the upper end 3T of the buffer weir 3 is located above the position in the height direction of the drain port 11 in the drain pipe 1.

  Drainage discharged from the drain pipe 1 is stored in the first section A11. Throughout the operation period of the plant, the water level of the drainage water in the first section A11 is maintained substantially equal to the height position of the upper end 3T of the buffer weir 3. That is, during operation of the plant, the first section A11 is almost always filled. In the following description, the water level of the drainage in the first section A11 is referred to as a drainage water level EWL.

  If the drainage from the drain pipe 1 is continued in the above state, the drainage overflows from the first section A11. The overflowed drainage gets over (overflows) the buffer weir 3 and flows into the second section A12. The water level of the wastewater in the second section A12 at this time is referred to as a stored water level RWL. As will be described later in detail, the stored water level RWL changes according to the amount of wastewater from the plant and the amount of water discharged to the discharge area A2.

  In the ocean or river including the discharge area A2, the water level changes with time according to natural conditions such as ebb and flow. In the present embodiment, the water level when the water level is the highest is called the highest water level HWL, and the water level when the water level is the lowest is called the lowest water level LWL. Note that the highest water level HWL and the lowest water level LWL indicate the average water level of the distance from the water bottom B to the water surface excluding the influence of waves and the like. It is desirable that these values are obtained in advance through actual observations and the like.

  The weir 2 extends generally vertically upward from the water bottom B (base 21) of the drainage area A to the upper end 2T. The cross section of the weir 2 has a shape that gradually tapers from the water bottom B upward. That is, the base 21 of the weir 2 has a larger thickness (dimension in the discharge direction) than the upper end 2T. As a result, the greater the pressure applied to the base 21, the greater the resistance to this water pressure.

  The dimension (height) from the base 21 to the upper end 2T of the weir 2 is set larger than the above-mentioned maximum water level HWL. In other words, the water surface on the discharge area A2 side does not flow over the upper end 2T of the weir 2 to the water storage area A1 side.

  Further, in the middle of the extension of the weir 2, a through-hole 23 that opens the water storage area A1 (second section A12) and the discharge area A2 is opened. This through hole 23 penetrates both sides of the weir 2 in the above-mentioned discharge direction. Of both ends of the through hole 23, an end on the second section A12 side is an inlet 24, and an end on the opposite side is an outlet 25. The space between the inlet 24 and the outlet 25 is a drain passage 26. Further, the inner peripheral surface of the drain passage 26 is an inner peripheral surface 27 of the passage. In the present embodiment, the through hole 23 has a substantially circular cross section when viewed from the discharge direction.

  The drainage temporarily stored in the second section A12 flows into the drainage channel 26 through the inflow port 24, and is then drained to the discharge area A2 through the outflow port 25. Here, in the present embodiment, the opening size (flow path cross-sectional area S) of the through hole 23 is set so as to satisfy the following condition. That is, by adjusting the flow path cross-sectional area S of the through hole 23, the resistance to the drainage flowing through the through hole 23 is adjusted. By adjusting this resistance, the water surface (reserved water level RWL) of the second section A12 is located above the drain port 11 of the drain pipe 1 as a result, and does not exceed the height of the upper end 2T of the weir 2. Maintained in position. In other words, the drain port 11 of the drain pipe 1 is located below the stored water level RWL in the second section A12, and is maintained at a position where the stored water level RWL does not exceed the height of the upper end 2T of the weir 2. .

  Next, the operation of the drainage seal pit 100 of the present embodiment will be described with reference to FIGS. FIG. 2 is a diagram illustrating the drainage seal pit 100 when the water level in the discharge area A2 is equal to or higher than the lowest water level LWL and lower than the highest water level HWL. As described above, based on the setting of the flow path cross-sectional area S of the through hole 23 provided in the weir 2, the stored water level RWL in the second section A12 is located at a position lower than the height of the upper end 2T of the weir 2. , At a position higher than the lowest water level LWL. In the following, a case where the amount of drainage from the plant is the maximum rated value (during maximum drainage) will be described.

  According to the above-described configuration, by appropriately setting the flow path cross-sectional area S of the through hole 23, the stored water level RWL of the second section A12 exceeds the water level (lowest water level LWL) in the discharge area. That is, the water level difference Δh between the drain water level EWL in the first section A11 and the stored water level RWL in the second section A12 can be reduced. By maintaining the water level difference Δh relatively small, the head when the drainage in the first section A11 flows over the buffer weir 3 and flows into the second section A12 can be reduced. Thereby, the formation of foam when the drainage of the first section A11 falls (flows) into the second section A12 can be suppressed.

  Further, since the drain port 11 of the drain pipe 1 is also located below the drain water level EWL of the first section A11, the drain water discharged from the drain port 11 does not involve outside air. Further, the drainage does not collide with the water surface of the water storage area A1. Thereby, the possibility that a foam will be generated on the water surface of the water storage area A1 can be reduced. In other words, the provision of the buffer weir 3 can reduce the possibility that a change in the water level of the discharge area A2 directly affects the first section A11. That is, the second section A12 functions as a buffer area between the first section A11 and the discharge area A2.

  In addition, according to the above-described configuration, the entire amount of drainage from the water storage area A1 can be discharged to the discharge area A2 through the through hole 23 regardless of the water level of the discharge area A2. Thereby, when the drainage flows into the discharge area A2, the outside air is not involved. Therefore, generation of foam on the water surface can be suppressed.

  Further, the above-described drain seal pit 100 can be configured only by providing the through hole 23 in the weir 2. Therefore, for example, the above operation and effect can be obtained by adding the through hole 23 to the seal pit including the existing weir 2. This can avoid complication of the configuration and prolong the construction period, and can reduce the cost associated therewith.

  As described above, the first embodiment of the present invention has been described, but various changes can be made to the above-described configuration without departing from the gist of the present invention. For example, in the above embodiment, the description has been given of wastewater from a thermal power plant or the like. However, the application target of the seal pit 100 for drainage is not limited to the above, and the drainage seal pit 100 can be applied to any equipment as long as a large amount of drainage is generated during operation.

  Further, as an example of a configuration for changing the flow path cross-sectional area S of the through hole 23 described above, an adjustment valve 50 as shown in FIG. 4 can be considered. The adjustment valve 50 has a valve body 51 that rotates around a rotation axis O that extends in the width direction that intersects the direction in which the through hole 23 penetrates. By appropriately adjusting the angle of the valve body 51 with respect to the penetration direction (that is, the opening degree of the valve body 51 in the penetration direction of the through hole 23), the flow path cross-sectional area S of the through hole 23 can be appropriately adjusted. . Thereby, the same effect as described above can be obtained.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. In the seal pit 100 for drainage according to the present embodiment, the shape of the through hole 23 of the weir 2 is different from that of the first embodiment. Specifically, as shown in FIG. 5, in the through hole 23, a part of the flow path inner peripheral surface 27, which is an inner peripheral surface thereof, protrudes inward (inward in the radial direction), so that the flow path cross-sectional area is The stenosis portion 28 that reduces S is used.

  The area on the water storage area A1 side as viewed from the constricted portion 28 is formed such that its opening size (flow path cross-sectional area S) gradually increases from the constricted portion 28 toward the inflow port 24. In particular, the flow path cross-sectional area S is formed such that the rate of increase increases as the flow path approaches the inflow port 24 from the constricted portion 28. In the present embodiment, the bell mouth portion 29 is formed by forming the inflow port 24 of the through hole 23 as described above.

  According to the above-described configuration, by providing the bell mouth portion 29, it is possible to reduce inflow resistance to drainage flowing into the through hole 23 from the water storage area A1 side. Here, when the flow passage cross-sectional area S of the through hole 23 (the flow passage inner peripheral surface 27) is uniform over the entire area in the discharge direction, the corner portion between the inlet 24 and the drainage contacting the inlet 24 is formed. Is formed, a relatively large inflow resistance occurs.

  However, in the present embodiment, since the above-described bell mouth portion 29 is formed in the through hole 23, the inflow resistance when drainage flows in can be sufficiently reduced. In other words, the drainage can be stably discharged through the through holes 23.

  In the above embodiment, the example in which the stenosis portion 28 and the bell mouth portion 29 are formed integrally with the weir 2 has been described. However, the constriction portion 28 and the bellmouth portion 29 may be formed of members different from the weir 2. Specifically, after forming a stenosis portion 28 and a cylindrical member having a bell-mouth-like inner peripheral surface shape with a metal tube or the like, the member is fitted into the through-hole 23 opened in advance. It is also possible to obtain the configuration described above.

  In particular, the weir 2 is generally completed by civil engineering using a material mainly composed of concrete. In consideration of the difficulty of processing based on the fluidity of the concrete, it is advantageous to form the constricted portion 28 and the bellmouth portion 29 by different members as described above.

  Further, in the above-described second embodiment, in the constricted portion 28 in the through hole 23, the flow path cross-sectional area S is substantially constant over the entire extension area. However, the shape of the constricted portion 28 is not limited to this, and may be, for example, a shape as shown in FIG.

In the modified example of the present embodiment shown in FIG. 6, in the region on the discharge area A2 side of the narrowed portion 28 in the through hole 23 (that is, the area near the outlet 25), the flow path cross-sectional area S is gradually increased. Is formed. More specifically, in this region, the opening size (inner diameter size) of the through-hole 23 linearly increases from the constricted portion 28 toward the outflow port 25, thereby forming the diffuser portion 30. In other words, in the diffuser portion 30, the inner peripheral surface extends linearly in a cross-sectional view from a direction intersecting with the penetration direction of the through hole 23.
Further, in this state, the position where the bell mouth portion 29 and the diffuser portion 30 are connected, in other words, the portion having the smallest flow path cross-sectional area S inside the through hole 23 is the top portion 31.

  When the above configuration is adopted, the static pressure of drainage inside the through hole 23 changes as shown in FIG. 10 along the penetration direction. The vertical axis in the graph of FIG. 10 represents the static pressure of the drainage flowing through the inside of the through hole 23, and the horizontal axis represents the position coordinates from the inflow port 24 of the through hole 23 in the discharge direction. Further, La on the horizontal axis represents the position coordinates of the top 31 inside the through hole 23. Similarly, Lb on the horizontal axis represents the position coordinates of the outlet 25 of the through hole 23.

  In the above-described graph, the curve shown by the solid line represents the static pressure distribution of the drainage when the above-described diffuser portion 30 is provided in the through hole 23. On the other hand, a curve shown by a broken line represents a static pressure distribution of the drainage in the through-hole 23 not having the diffuser portion 30. As shown by the solid line graph and the broken line graph, after the static pressure decreases from the inlet 24 to the top 31, the static pressure starts to increase again in the region from the top 31 to the outlet 25. That is, according to this graph, the force (pressure difference Δp1) for pushing the drainage from the inflow port 24 toward the inside of the through hole 23 is represented by the difference between the static pressure pr at the inflow port 24 and the static pressure p1 at the top 31. Is done.

  Here, comparing the solid line graph and the broken line graph, in the through hole 23 (solid line graph) provided with the diffuser portion 30, the static pressure p1 at the position coordinate La of the top portion 31 is reduced by the through hole 23 (dashed line) not provided with the diffuser portion 30. The value is larger than the static pressure p2 at the same position La in the graph). That is, in the through hole 23 having the diffuser portion 30, the pressure difference (Δp1) required to push the drainage from the inflow port 24 into the through hole 23 is larger than the pressure difference (Δp2) in the through hole 23 having no diffuser portion 30. It turns out to be small.

  The above phenomenon is explained as follows. First, by providing the above-mentioned diffuser part 30, the flow velocity of the drainage passing through the top part 31 increases. That is, the dynamic pressure of the drainage at the top 31 increases. Since the total pressure per unit flow rate of the wastewater is constant, the static pressure (total pressure-dynamic pressure) decreases by the above-mentioned increase in the dynamic pressure.

  As described above, by providing the diffuser portion 30 in the region including the outlet 25 of the through hole 23, the pressure required to push the drainage from the inlet 24 becomes smaller. Therefore, when comparing two through-holes 23 having the same opening size (flow path cross-sectional area S), the through-hole 23 having the diffuser portion 30 has a larger opening than the through-hole 23 having no diffuser portion 30. The hole size can be reduced. By reducing the opening size (flow path cross-sectional area S) of the through hole 23 in this way, the influence of the formation of the through hole 23 on the structural strength of the weir 2 can be reduced.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 7, the drainage seal pit 100 according to the present embodiment includes an opposing wall 40 provided along the weir 2 in the discharge area A2. The opposing wall 40 is formed by a plate-like wall that extends in substantially the same direction as the extending direction of the weir 2 in plan view (that is, when viewed vertically upward). Further, the facing wall 40 is provided at a position facing the through hole 23 provided in the weir 2 and is arranged at a distance from the through hole 23 (the weir 2) in the penetrating direction.

  Of the two surfaces of the opposing wall 40 in the above-mentioned discharge direction, the surface facing the weir 2 is the opposite surface 41, and the surface opposite to the opposite surface 41 is the discharge surface 42. In the example of FIG. 6, the facing surface 41 and the discharge surface 42 are all curved toward the weir 2 (through hole 23). In other words, the opposing wall 40 has a C shape in plan view.

  By providing such an opposing wall 40, when a tide or the like on the discharge area A2 flows toward the weir 2, the influence of the flow on the drainage performance of the through hole 23 can be reduced. For example, when an external flow toward the weir 2 (through-hole 23) occurs, pressure is applied from the discharge area A2 side of the through-hole 23 toward the water storage area A1, so that the flow of drainage may be obstructed. There is.

  However, by providing the above-described facing wall 40, the possibility that a tide or the like directly flows toward the through hole 23 can be reduced. Thereby, as described in the second embodiment, the possibility that the static pressure distribution of the drainage in the vicinity of the outlet 25 of the through hole 23 is disturbed can be reduced.

  On the other hand, the facing wall 40 can be shaped as shown in FIG. In the example shown in the drawing, opposite to the above-described opposing wall 40, the opposing surface 41 has a concave shape, and the discharge surface 42 has a convex shape and is curved. According to such a configuration, when an external flow flowing toward the opposing wall 40 collides with the opposing wall 40, the flow can be dispersed along the curved shape of the opposing wall 40. Thereby, similarly to the above, it is possible to reduce a possibility that a tide or the like directly flows into the through-hole 23. At the same time, the possibility that the static pressure distribution of the drainage near the outlet 25 of the through hole 23 is disturbed can be reduced.

  Further, as shown in FIG. 9, it is conceivable that both the facing surface 41 and the discharge surface 42 of the facing wall 40 are curved in a convex shape. According to such a configuration, the drainage from the through-hole 23 and the external flow such as the tidal current can be dispersed along the respective curved surfaces.

100: Seal pit for drainage A: Drainage area 1: Drainage pipe 11: Drainage port 2: Weir 3, Buffer damper 4: Plant quay A1: Storage area A2: Discharge area EWL: Drainage water level RWL: Storage water level H: Height dimension HWL: Highest water level LWL: Lowest water level B: Water bottom 21: Base 2T: Upper end of weir 23 ... Through hole 24: Inlet 25 ... Outlet 26: Drainage channel 27: Channel inner peripheral surface 3T: Upper end of buffer dam Part S: Channel cross-sectional area A11: First section A12 ... Second section 28 ... Stenosis part 29 ... Bell mouth part 30 ... Diffuser part 31 ... Top part 40 ... Opposing wall 41 ... Opposing surface 42 ... Discharge surface 50 ... Regulator valve O … Rotation axis Δh… Water level difference

Claims (8)

A drain pipe having a drain for discharging waste water;
Along with partitioning into a storage area for storing wastewater discharged by the drainage pipe and a discharge area from which the drainage of the storage area is discharged, the storage area and the discharge area below the lowest water level of the discharge area A weir formed with a through hole to communicate with,
With
The flow path cross-sectional area of the through hole is such that the drain port is located below the water level of the drainage stored in the water storage area, and the water level of the stored drainage is at the maximum drainage time. It is set not to exceed the height of the weir,
An inflow port, which is an end of the through hole on the water storage area side, and an outflow port, which is an opposite end, are located below the lowest water level in the discharge area ,
The water bottom of the storage area and the water bottom of the discharge area are spread at the same height from each other,
Further provided is a buffer weir provided in the water storage area to partition the water storage area into a first section and a second section,
The first compartment stores wastewater discharged by the drainpipe,
The dimension in the height direction of the buffer weir is smaller than the dimension in the height direction of the weir, and the upper end of the buffer weir is located above the drain port in the height direction for drainage. Seal pit . The weir is
2. The drainage seal pit according to claim 1, further comprising an adjustment valve provided inside the through hole to change an opening degree of the flow passage so as to change the cross-sectional area of the flow passage. 3. The weir is
By protruding inward from the inner peripheral surface of the through-hole, a narrow portion that reduces the flow path cross-sectional area at a part of the through-hole,
The region of the reservoir area side than the narrowed portion of the through hole, toward from the reservoir area to the stenosis to claim 1 or 2 forming the bellmouth portion by the flow path cross-sectional area decreases gradually The seal pit for drainage described. In a region of the through hole closer to the discharge region than the constricted portion, a diffuser portion is formed by linearly increasing an opening size of the through hole from the constricted portion toward the discharge region. 3. The seal pit for drainage according to 3 . In the discharge zone, which extends along the weir, according to any one of claims 1 to 4 having opposed walls that faces the through hole with a gap in the through direction of the through hole from the weir Seal pit for drainage. The drainage seal pit according to claim 5 , wherein a surface of the opposed wall facing the through hole is curved toward the through hole in a plan view. Said opposite side surface and the through hole in the opposite wall, drainage seal pit according to claim 5 or 6 is curved in a direction away from the through-hole in a plan view. The drainage seal pit according to any one of claims 1 to 7 , wherein the through-hole is formed only in the weir of the weir and the buffer weir.

Images