JPH05287791A - Drainage system for city - Google Patents

Abstract

PURPOSE:To reduce the cost of construction for pipeline by a method in which in case of abnomally heavy rain, the water from drains and river is introduced to the underdrainage pipeline through vertical pits and the flow rate of the water is increased by an accelerating pump set in the pipe line. CONSTITUTION:In case of heavy rain, the water from a river 3, diversion channels 4, and drains 6 is directed through vertical pits 8a-8c to an underdrainage pipeline l. When the pipeline 1 is filled with water, an accelerating pump 9 such as axial flow pump is actuated to increase the flow rate of the water in the pipeline. The water so moved is pumped up by a drain pump 10 to discharge it to seal 7. The cross section of the drainage pipeline can thus be reduced, the cost of construction can be cut down, and the flow of the water in the pipeline can also be easily controlled because the pipeline can be filled with water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drainage system mainly composed of a drainage pipe, a drainage pump and the like for draining outflow of water during abnormal rainfall in a city.

[0002]

2. Description of the Related Art A conventional drainage system for rainwater in a large city, as shown in FIG. 7, has a drainage channel 6, a small and medium river 3, a discharge channel 4, and a drainage channel 1 connecting them underground via a shaft 8.
And the drainage pump facility 2 at the end of the pipeline.
Rain that has fallen on the ground surface 5 flows into the vertical shaft 8 through the drainage channel 6,
In addition, the water overflowed due to the increase in water in the river 3 and the discharge channel 4 flows into the drainage channel 1 through the vertical shaft 8. The drainage pipeline 1 is provided with a downward slope, and water is transferred by natural flow and discharged to the river or the sea 7 by the pump of the pump facility 2 provided at the end of the pipeline.

[0003]

DISCLOSURE OF THE INVENTION Drainage channels and drainage pipes connecting small and medium-sized rivers are installed underground, and it is necessary to have a large flow passage cross-sectional area in order to process a large amount of wastewater. Therefore,
Although it is necessary to reduce the cross-sectional area of the flow path to reduce the construction cost,
In natural flow using a downward slope, it is difficult to significantly reduce the flow passage area because the flow velocity is limited. Further, since the flow velocity is slow, it is difficult to switch the flow in the pipeline and control the operation of the entire drainage pipeline such as controlling the operation of the pump at the pumping station at the end.

An object of the present invention is to reduce the flow passage cross-sectional area of a drainage pipe installed underground, to reduce the construction cost, and to improve the operation controllability of the entire drainage pipe.

[0005]

[Means for solving the problem] A pump is installed in the drainage pipe, the flow velocity of the pipe is accelerated by the pump, and the flow rate per unit flow passage area is increased to be larger than the flow velocity due to natural flow to reduce the flow passage cross-sectional area The operation control of the drainage pipeline is facilitated.

[0006]

[Function] The pump installed in the drainage flow path accelerates the water flow flowing into the pump from the upstream side, and discharges it to the downstream side. As a result, the flow velocity in the pipeline becomes higher than the flow velocity due to the natural flow due to the downward slope, the flow rate per unit flow area increases, and the cross-sectional area of the pipeline should be reduced compared to the conventional drainage pipeline for the same designed drainage volume. You can

[0007]

FIG. 1 is a sectional view showing an embodiment of the drainage system of the present invention. There are a river 3 and a discharge channel 4 on the ground. Rainwater that has landed on the surface 5 flows into the drainage ditch 6. The overflow channels of the river 3, the discharge channel 4, and the drainage channel 6 are vertical shafts 8a, 8 respectively.
It is connected to the drainage pipe 1 installed underground through b and 8c. The drainage pipe 1 is provided with a pump 9 for accelerating the drainage flow. The pump 9 is, for example, an axial flow pump as shown in FIG. 2, and the entire pump is installed in a cylindrical pipe line. The impeller 10 is a hub 12a of the guide blade 12.
It is driven by a prime mover such as a motor or engine built in. A drainage pump facility 2 is provided at the end of the drainage pipeline 1, and the water transferred in the drainage pipeline 1 is pumped up by a drainage pump 10 and discharged into a river or the sea 7.

When a large amount of rainfall occurs in such a city drainage system, the overflow of the river 3, the water discharge channel 4, and the drainage channel 6 which has been increased due to the rainfall flows into the drainage channel 1 through the vertical shaft 8. Since many vertical shafts 8 are connected to the drainage pipe 1, a large amount of rainwater flows in, and there is no free surface in the pipe, resulting in a full pipe state. At this time, when the acceleration pump 9 installed in the drainage pipeline 1 is driven, the flow in the pipe becomes faster than the natural downflow speed determined by the pipeline gradient. Therefore, when the flow passage cross-sectional area of the drainage pipeline 1 is constant, the flow rate that can flow through the drainage pipeline 1 is significantly increased. On the contrary, the cross section of the pipeline can be reduced when the flow rate through the pipeline is constant. Since the drainage pipeline 1 is installed underground and the construction work cost thereof increases in proportion to the pipeline cross-sectional area, the reduction of the pipeline cross-sectional area is effective in reducing the construction cost.

On the other hand, if the cross-sectional area of the drainage pipe 1 is small, it is easy to always fill the inside of the pipe. It is relatively easy to predict the flow in the pipeline with respect to a sudden change in the amount of inflow into the pipeline in the full state, as compared with the non-full state. Further, with respect to the change of the flow state in the pipe, only the flow by natural flow can perform only passive control such as valve switching. However, the accelerating pump 9 enables active control, enhances the controllability of the flow state of the entire pipeline, and improves the responsiveness of the entire drainage system to rainfall.

FIG. 3 shows another embodiment of the present invention. By installing a plurality of acceleration pumps in the drainage pipe, it is possible to further enhance the control response to changes in the flow rate. In addition, since the distance between the pumps is shortened, the pipeline resistance that one pump must share is reduced, and the total lift of the pumps can be reduced.

FIG. 4 shows a drain pipe having a relatively large capacity according to a third embodiment of the present invention. Three small outer diameter pumps 9d, 9e, 9f are provided in a cross section of the pipe having a large diameter. Is installed so as to be inscribed. When the amount of rainfall is small, the drainage pipe 1 is in a non-full state in which the water surface 13 exists. In such a state, only the pump 9e submerged in the water surface is driven to accelerate the water flow. In a full pipe state where the amount of rainfall is large and the water surface disappears, all three pumps are driven and the same operation as in the case of FIG. 2 is performed. Therefore, even a large-capacity drainage system can be operated efficiently even with a small capacity, without impairing the original function.

A fourth embodiment is shown in FIG. Drainage line 1
Is installed in the lower part of the small and medium river 3 in parallel with the river 3, and has a configuration (not shown) in which the flow of the river 3 is branched at the upstream part and flows into the drainage channel 1 through the floodgate. In this case, the drainage pipe 1 functions as a bypass passage for the river 3. In flood protection of rivers, river slopes are usually gentle in large cities, so the river width must be widened rather than increased in depth. However, it is extremely difficult to take measures to widen rivers in large cities due to soaring land prices. According to the present embodiment, it is possible to implement a flood control with a drain pipe having a small diameter and a relatively low construction cost without widening.

FIG. 6 shows a fifth embodiment. Water level detection devices 13a, 13b, 13 are provided in the river 3, the discharge channel 4, and the drainage channel 5.
c is installed in each. The output of the water level detection device 13 is guided to the acceleration pump control device 14, and a setting signal of the operating conditions (rotation speed, pump operation, turbine operation, etc.) of the pump set in advance according to the water level is output, and the signal is output to that signal. Based on this, the acceleration pump is controlled. With such a configuration,
When a transient phenomenon such as a rapid increase in the pressure of the vertical shaft 8 due to a sudden stop of the drainage pump 10 occurs, it appears as a change in the water level of the river. The change in the water level is detected by the water level detection device 13, and then the water level signal is guided to the acceleration pump control device 14, and the operation of the acceleration pump is controlled so that the internal pressure of the pipeline does not rise abnormally. Therefore, even if a hydraulic transient phenomenon such as a sudden stop of the drainage pump occurs, the drainage system can maintain the pipeline without damage.

[0014]

According to the present invention, the flow velocity in the drainage pipe can be increased, and as a result, the cross-sectional area of the drainage pipe can be reduced and the construction cost can be reduced. Further, the inside of the pipeline can be filled with a full state, and the flow of the pipeline can be controlled more easily.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a drainage system of the present invention.

2 is a cross-sectional view of an acceleration pump of a detail A in FIG.

FIG. 3 is a sectional view showing another embodiment of the drainage system of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the acceleration pump in the detail of the part A in FIG.

FIG. 5 is a sectional view showing another embodiment of the drainage system of the present invention.

FIG. 6 is a sectional view showing an embodiment of the drainage system of the present invention.

FIG. 7 is a cross-sectional view showing an example of a conventional drainage system.

[Explanation of symbols]

1 ... Drainage pipeline, 2 ... Drainage pump facility, 3 ... River, 4 ... Drainage channel, 5 ... Ground surface, 6 ... Drainage channel, 7 ... River or sea, 8 ...
Vertical shaft, 9 ... acceleration pump, 10 ... drainage pump.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Takada, 603 Kitsudachi, Tsuchiura-shi, Ibaraki Hitate Works, Ltd., Tsuchiura Plant (72) Kenji Otani, 603, Jinmachi, Tsuchiura, Ibaraki Tsuchiura factory

Claims (1)

[Claims] 1. A drainage system for a city, wherein an acceleration pump is installed in a horizontal or downward slope drainage pipe.