JP2570530B2 - Large-diameter pipe without dead water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-diameter pipeline which is used as a water supply in a deep underground space and does not generate dead water.

[0002]

2. Description of the Related Art A large-diameter pipeline for water supply pipes for supplying water is installed underground at shallow and medium depths, and has conventionally been used as existing equipment. Although there is no particular rule regarding the size of the large-diameter pipeline, the diameter that a person can enter and work on is 800 mm or more in diameter. It is intended to refer to a pipeline having the above diameter. Large-diameter pipelines installed underground at shallow and medium depths have, in principle, a diameter that matches the planned water transmission and distribution volumes, and basically do not consider the water storage function. For this reason, water does not accumulate in large-diameter pipelines installed underground at shallow and medium depths.

On the other hand, a concept of supplying drinking water and other drinking water using a large-diameter pipeline installed underground at a large depth has recently been announced by the Ministry of Health and Welfare and the Water Pipe Technology Center. ing. Under these plans, large-diameter pipelines installed underground at a large depth are expected to contribute to the block piping network of water distribution pipes, and need to have a water storage function (stock function). Have been.

[0004] Such a large-diameter pipeline installed underground at a large depth is required to have a storage function as described above, and is therefore used as a normal water supply pipe and a water distribution pipe. In comparison with large-diameter pipelines installed underground at shallow and medium depths, it is predicted that the ratio of water usage to storage capacity will be smaller, and the water retention time in pipelines will be relatively longer. Therefore, it is considered that there is a high possibility that the residual chlorine concentration in the tap water decreases. as a result,
There is a danger of dead water coming out of water taps (such as faucets in each household).

[0005] The Water Supply Law enforcement regulations stipulate that the water in the hydrant should be disinfected with chlorinated water so as to maintain the free residual chlorine at 0.1 ppm or more. Water is called "dead water".

[0006]

SUMMARY OF THE INVENTION
For large-diameter pipelines installed underground at deep depths, measures to prevent dead water, that is, the water at the hydrant must meet the above rules (free residual chlorine should be 0.1 ppm or more) It is. As a countermeasure, it is conceivable to inject a chemical for chlorine disinfection (hereinafter referred to as "chlorine agent") into tap water and disinfect it in the middle of a large-diameter pipeline installed underground at a large depth. . However, in the usual injection method, since the residual chlorine concentration is supplied while being non-uniform, there is a problem that the residual chlorine concentration is insufficient or an odor is generated due to an excessive amount. In addition, there is a problem that the amount of the chlorine agent used is generally large.

As described above, disinfection using a chlorine agent is performed by providing a disinfection facility in the middle of a large-diameter pipeline water distribution pipe and additionally injecting a chlorine agent. By the way, various techniques have been conventionally used for disinfecting and disinfecting equipment by injecting a chlorine agent, mixing and stirring of chlorine.
Hereinafter, these will be described. First, disinfection and disinfection equipment will be described. (1) Purpose of disinfection: Pathogens in raw water are usually largely removed by sedimentation and filtration at water treatment plants, but a small number may remain, so disinfection is performed to kill them. .

(2) Disinfection method: Disinfection of water is supposed to use chlorine (Ministry of Health and Welfare notification). Therefore, use other than chlorine is not allowed.

(3) There are the following three disinfection methods using chlorine. Use liquefied chlorine: Liquefied chlorine is liquefied chlorine gas at low temperature and high pressure. Use sodium hypochlorite: sodium hypochlorite is obtained by brine (fresh water) electrolysis. Use calcium hypochlorite (bleach). Among the above three methods, liquefied chlorine is overwhelmingly used. However, the method using sodium hypochlorite is increasing from the viewpoint of handling safety.

(4) The principle of chlorination. The method of chlorination in a water treatment plant is performed by a discontinuous point chlorination method. Hereinafter, the discontinuous point chlorination will be described. When a chlorinating agent is introduced into water containing ammonia and organic nitrogen compounds, the chlorine first reacts with the contents thereof to form combined residual chlorine. The combined residual chlorine increases as the chlorine injection rate increases, but when the chlorine injection rate reaches a certain amount, chloramine is oxidized to nitrogen gas and the residual chlorine concentration decreases. However, if the chlorine injection rate is further increased beyond that, the free residual chlorine concentration increases proportionately. This series of changes is shown in FIG.
FIG. 3 is a graph showing the relationship between the chlorine injection rate and the residual chlorine concentration. The minimum point of the residual chlorine concentration that occurs during this series of changes is called a discontinuous point (BREAK POINT). The method of injecting chlorine beyond this point to generate free residual chlorine and treat it is called the discontinuous point chlorine. Processing. Discontinuous point chlorination provides a sufficient disinfecting effect and is also effective as a method for removing iron and manganese.

(5) Chlorine disinfection equipment. Storage equipment. Since disinfection is indispensable for water purification treatment, it is necessary to provide sufficient room for the storage of disinfectants such as chlorine, and to always secure more than 10 days of usage. Liquefied chlorine containers include portable 50Kg or 1-ton iron containers and storage tanks installed at water treatment plants. In each case, prevent chlorine gas from leaking, prevent direct sunlight, and prevent moisture. Must be stored with great care. Since sodium hypochlorite is highly alkaline and corrosive, a corrosion-resistant material must be used for the storage tank. In addition, in order to prevent the available chlorine content from decreasing, it is necessary to store it while avoiding solar radiation and temperature rise, and to periodically measure the available chlorine content. Injection equipment. The chlorinator includes a dry type and a wet type. Commonly used is a wet injector. Wet injectors include pressure injectors and vacuum injectors. A pressure-type injector is a type in which chlorine gas is dissolved from the surface of water in a mixing bottle to produce chlorine water.A vacuum-type injector uses a vacuum force generated in an injector by pressurized water to generate chlorine gas. Is dissolved in pressurized water while sucking water to produce chlorine water. Piping for chlorine injection must be subjected to a pressure test and a leak test to prevent chlorine gas from leaking. Excluded equipment. Regarding chlorine gas, the Labor Standards Act stipulates a maximum allowable limit of 1 ppm during work. For liquefied chlorine, exclusion facilities such as a leak detector and a neutralizer during storage are to be provided according to general high-pressure gas safety regulations.

(6) Control of chlorine injection. The chlorine injection control includes constant value control, flow rate proportional control, and residual chlorine control. Hereinafter, the three injection controls will be described. Constant value control. It is used when the amount of treated water and the required amount of chlorine are small and a predetermined amount of chlorine can be maintained by injecting a substantially constant amount of chlorine. Flow proportional control. The amount of treated water is controlled. However, when the change in water quality is small and the required amount of chlorine is almost constant, it is used when a predetermined amount of residual chlorine can be retained by injecting a chlorine amount according to the change in the treated water amount. Residual chlorine control. A method of controlling residual chlorine as a target value when the amount of treated water changes and the required amount of chlorine changes.

Next, the mixing and stirring equipment will be described. As a mixing and stirring equipment for chlorination, there is a chlorine mixing well "Seki". As other mixing and stirring equipment, there is a method used for an emergency drinking water storage tank (an emergency water supply tank apparatus). Conventionally, there are a mixing chamber system and a perforated tube system.

As a technique of the mixing chamber system, Japanese Utility Model Publication No. Sho 62-29431
In the official gazette, an emergency drinking water storage tank is disclosed (hereinafter, referred to as “
"Prior art 1"). FIG. 4 is a sectional view of a water storage tank showing the prior art 1. The mixing chamber method of Prior Art 1 is a water tank
14, which is fixed by a diametrically extending support shaft which is substantially engaged with a circumferential cross-sectional position inside the main body of the water storage tank 14 and is disposed at a predetermined interval with respect to a longitudinal direction of the water storage tank 7. For example, it is composed of a plurality of partition plates 15 (partition walls) formed of a square plate, and a plurality of mixing chambers 16 are formed by the partition plates 15. The water flowing into the water storage tank 14 is
The process proceeds to the next mixing chamber 16 sequentially while repeating the mixing via, whereby the water is replaced. This prior art 1 has the following features. Water circulation characteristics in the water tank vary depending on the number of mixing chambers. As shown in FIG. 5, the number of mixing chambers and the replacement time of fresh water have a relationship in which the replacement time becomes shorter as the number of mixing chambers increases, but the effect does not increase when the number of mixing chambers is a certain number or more. Note that the replacement time is represented by elapsed time (flow rate / water tank capacity = how many times the water tank capacity allows the water to be completely replaced). Aspect ratio of one mixing chamber (width / length) even for long pipes
When it is set to about 1.6, good mixing characteristics are exhibited. More importantly, the average flow velocity in the tank. It should exhibit good mixing properties even at low flow rates of 1.5 to 5.9 mm / sec.

As a technique of a perforated pipe system, Japanese Patent Publication No. 58-39710
Japanese Patent Application Laid-Open Publication No. H10-209,897 discloses a water tank device for emergency water supply (hereinafter, referred to as “prior art 2”). 6 is a horizontal sectional view of a water storage tank showing prior art 2, FIG. 7 is a vertical vertical sectional view, and FIG.
FIG. 7 is a sectional view taken along line BB of FIG. Both ends of the water storage tank 9 are concave, the inflow pipe 10 is connected to a perforated pipe section 11 having a closed end at the lower part of the water storage tank 9, and the outflow pipe 12 is a perforated upper part of the water storage tank 9. It is connected to the tube 13. A number of small holes are drilled upward in one row over the entire length of the perforated tube portion 11, and a number of small holes are drilled downward in one line also over the entire length of the perforated tube portion 13. In the water reservoir 9 under normal conditions, water spouted from a number of small holes of the inflow-side perforated pipe 11 flows in a circular shape and is constantly stirred, and the water is kept in the water reservoir 9.
The water sequentially flows into and out of the outflow-side perforated pipe portion 13 without stagnation in any part of the inside. This prior art 2
It has the following features. It has good mixing characteristics at a relatively high speed with an average flow velocity in the tank of 0.5 to 2.5 m / sec. When the average flow velocity in the tank is in the range of 0.5 to 2.5 m / sec, the ratio of the amount of water required for replacement to the capacity of the storage tank is almost constant, so that chlorine injection control is easy. In other words, when the flow rate is low, it naturally takes much time,
The flow rate for replacing water once is the same, and chlorine corresponding to the same is injected by flow rate proportional control, so that it is not necessary to control the residual chlorine concentration.

In addition, good control is easy by additional injection of chlorine in the distribution reservoir, and control is difficult in post-chlorination treatment in the water treatment plant, and additional injection of chlorine is necessary. , Already known.

Next, aeration will be described.
Aeration is the volatilization of volatile substances dissolved in water by sufficient contact between water and air,
This is a treatment method for promoting oxidation of a substance to be oxidized in water by oxygen in the air, and includes a fountain type, an air blowing type, a waterfall type, and a contact type. The effects of this aeration are as follows. Removal of erodible free carbonic acid: Erosive free carbonic acid is often included in groundwater and stagnation bottom water such as lakes (reservoirs) in natural waters, and when chlorine or coagulant is injected during water purification treatment Also occurs. Water containing a large amount of erodible free carbonic acid easily promotes deterioration of concrete structures, asbestos cement pipes, mortar lining pipes, etc.
Further, it is easy to elute metal of each material from iron pipe, copper pipe, galvanized steel pipe and the like. In general, water having free carbonic acid of 20 mg / l or more often contains erodible free carbonic acid, and therefore, it may be necessary to remove erodible free carbonic acid depending on the degree of damage. Although it is difficult to completely remove erodable free carbonic acid by aeration, it is effective in reducing erodibility. Odor removal: Effective for removing volatile odor-causing substances such as hydrogen sulfide. Removal of iron and manganese: Ferrous hydrogen carbonate [Fe (HCO ₃ ) ₂ ], which is often found as dissolved iron, is removed by insoluble ferric iron by aeration and then by ordinary water purification treatment. be able to. However, the effect on iron other than ferrous hydrogen carbonate and soluble manganese is low. Removal of trichlorethylene, tetrachlorethylene and 1,1,1 • trichloroethane: Contamination by these three substances is mainly detected in groundwater,
Groundwater has relatively stable water quality, including its temperature.
By using aeration, a stable effect can be obtained in removing these three substances. The ease of removal of each of the three substances is roughly in the order of trichloroethylene>tetrachloroethylene> 1,1,1.trichloroethane. In Japan, there are many cases where a counter-current packed type aeration tower is adopted.

An object of the present invention is to provide a disinfection facility in the middle of a large-diameter pipe installed in a deep underground where the water storage time is long due to the storage function, based on the above-mentioned conventional technology. An object of the present invention is to provide a large-diameter pipeline in which dead water does not occur by performing additional injection of an agent.

[0019]

As described above, we have made it possible to prevent dead water from occurring in a large-diameter pipeline installed underground at a large depth where the water storage time is long due to the storage function. Intensive research into the development of technologies for this purpose. As a result, it has been found that a large-diameter pipeline free of dead water can be obtained by providing a disinfecting facility using a combination of the above-described conventional techniques and additionally injecting a chlorine agent in the middle of the large-diameter pipeline.

The present invention has been made based on the above findings, and has a large-diameter pipe having a circular cross-section, which is provided underground at a large depth and through which water flows, and the large-diameter pipe. Between the inner peripheral surface of the large-diameter pipeline, which is fixed in the pipe-axis orthogonal direction of the large-diameter pipeline inside, and is provided at a predetermined interval in the pipe-axis direction of the large-diameter pipeline. And two inflow pipes having a predetermined gap therebetween, and an inflow pipe having a plurality of holes in an insertion portion inserted in the large-diameter pipe between the bulkheads, and the air containing chlorine is introduced into the inflow pipe. It is characterized in that it is injected into the large-diameter pipe through the hole of the pipe.

[0021]

In the inside of the large-diameter pipe, two partitions are provided at predetermined intervals in the direction perpendicular to the pipe axis of the large-diameter pipe, and an inflow pipe is inserted between the partitions, and the inserted inflow pipe is inserted. By inserting a hole in the insertion part of the hole and injecting air mixed with chlorine through the hole, even if the ratio of the amount of water used to the amount of water stored is relatively small, dead water does not occur and water can be easily replaced. . Further, by injecting chlorine mixed with air from the hole under pressure, the replacement time (water storage amount / used water amount) can be shortened, and the inside of the large-diameter pipeline is uniformly stirred and mixed. Further, free carbonic acid, iron, manganese and the like are removed by the aeration effect of the pressurized mixed air.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a vertical longitudinal sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. 1 inside a large-diameter pipeline 1 with a circular cross section installed in a deep underground space
In the section, two partition walls 2a and 2b are provided at predetermined intervals in the pipe axis direction of the large diameter pipe line 1 in the pipe axis orthogonal direction. Each of the partition walls 2a and 2b is formed of a square plate whose four corners are in contact with the inner peripheral surface of the large-diameter pipeline 1. Partition
On the downstream side near 2a, an inflow pipe 4 is inserted into the large-diameter pipeline 1 from above. The insertion portion 3 of the inflow pipe 4 is bent downstream in the vicinity of the bottom inner peripheral surface of the large-diameter pipe 1, and is provided in the pipe axis direction of the large-diameter pipe 1 along the bottom inner peripheral surface to the partition 2 b. ing. The distal end of the insertion portion 3 of the inflow pipe 4 is closed, and a plurality of holes 7 are provided at predetermined intervals in the longitudinal direction in a portion provided along the inner peripheral surface at the bottom of the large diameter pipeline 1. It is provided upward. The diameter of the hole 7 gradually increases from the upstream side to the downstream side. The reason that the hole diameter gradually increases from the upstream side to the downstream side is to make the amount of air blown out from each hole 7 constant. This is because the diameter of the downstream side hole 7 having a low pressure is made smaller than that of the upstream side. Is also achieved by making it larger. From each of the holes 7, air (compressed air) 18 mixed with gaseous chlorine 17 is provided.
Is pressurized and injected into the large-diameter pipeline 1. further,
An outflow pipe 6 is inserted into the large-diameter pipe line 1 on the upstream side near the partition 2b, and a sensor 5 for measuring the residual chlorine concentration is provided in the middle of the outflow pipe 6.

Between the partition walls 2a and 2b, air (compressed air) 18 containing chlorine 17 mixed through the hole 7 of the insertion portion 3 of the inflow pipe 4.
Is injected and flows in a circle in the water in the large-diameter pipeline 1, and the water is constantly stirred and mixed without stagnation in any part of the large-diameter pipeline 1. The agitated and mixed water in the large-diameter pipeline 1 is sequentially discharged downstream of the partition 2b through the partition 2b, and the water is replaced.

As described above, two partitions are provided in one section of the large-diameter pipeline 1, and chlorine 17 is introduced from the hole 7 of the insertion portion 3 of the inflow pipe 4.
By injecting pressurized mixed air consisting of air and pressurized air 18, the residual chlorine concentration in the
The shortage disappears and the residual chlorine concentration becomes uniform. further,
The amount of chlorine 17 used can be reduced, and the production of trihalomethane and the like can be reduced. Further, free carbonic acid, iron, manganese and the like are removed by the aeration effect of the pressurized mixed air.

The optimum aspect ratio (width / length) of the mixing chamber 19 of the large-diameter pipeline constituted by the partition walls 2a and 2b is 1.64. That is, the space (width) between the partition walls 2a and 2b is optimally 1.64 times the diameter (length) of the large diameter pipeline 1.

The chlorine injected from the insertion portion 3 is preferably gaseous (chlorine gas) as described above because it is mixed with pressurized air. Further, the position for injecting chlorine and the position of the device for generating hypochlorous acid may be on the ground or in a tunnel 8 provided with the large-diameter pipeline 1. Alternatively, the residual chlorine concentration may be measured by a sensor 5 provided in the middle of the outflow pipe 6, and the amount of chlorine injection may be controlled based on the measured value.

[0027]

As described above, according to the present invention, drinking water suitable for drinking can be supplied to a water tap without generating dead water by making the concentration of chlorine injected into a pipe uniform. A large-diameter pipeline is obtained, thus providing an industrially useful effect.

[Brief description of the drawings]

FIG. 1 is a vertical longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a graph showing a relationship between a chlorine injection rate and a residual chlorine concentration.

FIG. 4 is a cross-sectional view of a water storage tank showing prior art 1.

FIG. 5 is a graph showing the relationship between the number of mixing chambers and fresh water replacement time.

FIG. 6 is a horizontal sectional view of a water storage tank showing prior art 2.

FIG. 7 is a vertical longitudinal sectional view of a water storage tank showing prior art 2.

FIG. 8 is a sectional view taken along the line BB of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Large diameter pipe 2a 2b Partition wall 3 Insertion part 4 Inflow pipe 5 Sensor 6 Outflow pipe 7 Hole 8 Tunnel 9 Water storage tank 10 Inflow pipe 11 Perforated pipe section 12 Outflow pipe 13 Perforated pipe section 14 Water storage tank 15 Partition plate 16 Mixing Chamber 17 Chlorine 18 Pressurized air 19 Mixing chamber.

Claims (2)

(57) [Claims] 1. A large-diameter pipe having a circular cross-section, which is provided underground at a large depth and through which water flows, and is fixed in a direction perpendicular to a pipe axis of the large-diameter pipe inside the large-diameter pipe. ,and,
Two bulkheads, which are provided at predetermined intervals in the pipe axis direction of the large-diameter pipeline and have a predetermined gap with the inner peripheral surface of the large-diameter pipeline; An inlet pipe having a plurality of holes at an insertion portion inserted into the bore pipe, wherein air containing chlorine is injected into the large-diameter pipe from the hole of the inlet pipe. Large-diameter pipeline that does not generate dead water. 2. The large-diameter pipeline without dead water according to claim 1, wherein the partition has a square plate body whose four corners contact the inner peripheral surface of the large-diameter pipeline. .