JP2011122318A - Control method and control system of water storage tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method and a control system of a water storage tank allowing a worker to grasp accumulation in the water storage tank simply and accurately and prevent the occurrence of the accumulation. <P>SOLUTION: In this control method of the water storage tank connected with a water service pipeline for supplying water into each house from a city water source, the water flowing in through an inlet formed on one side passes through the tank at a certain flow velocity and is drained through an outlet formed on the other side, water temperature in an upper layer and water temperature in a lower layer in the water storage tank are measured, and whether opening of a valve installed on an inlet side of the water storage tank must be adjusted or not is determined based on a difference between the water temperature in the upper layer and the water temperature in the lower layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a management method and a management system for a water tank that is buried underground and connected to a water pipe that supplies water to each house from a city water source.

Conventionally, in order to secure water supply in preparation for disasters such as earthquakes, water tanks have been provided in the water pipe network that supplies water to each house from a city water source. The water tank is buried underground and is directly connected to the water main and used as part of the water pipeline network. Furthermore, the water tank is buried in the basement of an emergency evacuation site at the time of a disaster, and is installed so that it can be used in the event of a disaster.
FIG. 8 is a side sectional view of a general concept water tank. The water storage tank 50 includes a tank main body 51 formed in a horizontal cylindrical shape, an inlet 52 provided on one side of the tank main body 51, and an outlet 55 provided on the other side. The inflow port 52 is connected to an inflow pipe 53 provided with a valve 54, and the outflow port 55 is connected to an outflow pipe 56.

  In such a water storage tank 50, if water stays in the tank, it will rot and become unusable in an emergency. Therefore, water quality maintenance management in the water tank is important, and various methods have been proposed and put into practical use. In general, water flowing in from the inflow port 52 is discharged from the outflow port 55, and water is always flowing in the tank so that no water stays.

  However, the flow rate of water passing through the water storage tank 50 is very small, and only a very low flow rate can be obtained. Then, the structure of the water storage tank is devised and the structure of the water storage tank which forms a stirring flow in the tank is proposed. For example, Patent Document 1 (Japanese Patent No. 3546106) discloses a configuration in which a disk-shaped shielding plate is installed in a water storage tank so as to cover the outlet of the water storage tank. Patent Document 2 (Japanese Patent Laid-Open No. 10-25776) discloses a configuration in which a plurality of sparger pipes having a large number of small holes are disposed in a water storage tank and water is injected from the small holes. .

Japanese Patent No. 3546106 Japanese Patent Laid-Open No. 10-25776

However, as in Patent Document 1 and Patent Document 2, even if a configuration in which a shielding plate is installed or a configuration in which a perforated tube is installed is provided, only a partial stirring effect can be obtained only by structural ingenuity. As a result, water retention could not be completely prevented.
Therefore, water was extracted from the water test tubes installed in the water tanks and the chlorine concentration was measured, but it was necessary to go to the site, and monitoring multiple water tanks took time and effort. It was.

  Therefore, in view of the problems of the prior art, the present invention aims to provide a water tank management method and management system that can easily and accurately grasp the stay in the water tank and prevent the stay. .

In order to solve the above-mentioned problems, the present inventors have conducted a detailed investigation on the cause of the retention of the water tank. As a result, the following knowledge was obtained.
Since the water tank is buried underground, temperature changes are small throughout the season. On the other hand, since the water flowing into the water tank is supplied from the above-ground reservoir, the seasonal variation is large. Therefore, there is a difference in temperature between the water stored in the water tank and the inflow water. For example, taking summer as an example, the water tank is cooled by geothermal heat, and the water in the tank is also cooled. The cooled water stagnates at the bottom, and the slightly hot water flowing from the outside may pass through the upper layer of the water storage tank without mixing with the cooled water at the bottom. This is thought to be the cause of stagnation in summer. On the contrary, in winter, water with a slightly low temperature flowing in from outside passes through the lower layer of the water storage tank and stays in the upper layer. From this, it is considered that the temperature difference between the stored water and the inflowing water is one of the major factors that cause the stagnation in the water storage tank where water from the ground flows into the water storage tank buried underground.

Here, the quantitative evaluation of the occurrence of stagnation will be described.
As described above, when the water temperature is different between the upper layer and the lower layer, the water in the water storage tank exists in the tank as a two-layer density flow. The two-layer density flow has a peculiar flow due to the density difference compared to a single fluid. Reference 1 ("Basic Civil Engineering Complete Book 7 Hydrology II", Toichiro Taki, Morikita Publishing Co., Ltd. 1978 April).

The mixing of this two-layer density flow can be quantitatively evaluated by the Keulegan number. The Keulegan number is defined as follows:
ρ1: Upper layer water density ρ2: Lower layer water density ε: (ρ1-ρ2) / ρ1
ν: Kinematic viscosity coefficient of water g: Gravity acceleration U1: Relative velocity of upper and lower layer flows Θ: Keulegan number = (νεg) ^ (1/3) / U1

  When the relative velocity of the upper and lower flows increases and the value of the Keulegan number Θ falls below a certain limit value, the internal wave generated at the boundary surface of the two-layer density flow is broken and mixing of the upper and lower fluids occurs. The limit value of laminar flow is 0.127, and upper and lower mixing occurs at a large flow rate where Θ <0.127, but upper and lower mixing does not occur at a small flow rate where Θ ≧ 0.127. According to the definition of the Keulegan number, the factors affecting the mixing of a two-layer density flow are the flow velocity, the density of the upper water and the density of the lower water. Since the density of water is a temperature function, the flow rate and the temperature difference between the upper layer water temperature and the lower layer water temperature are factors that determine the mixing of the two-layer density flow.

As a result of intensive studies from the above findings, the present inventors have found that the temperature difference between the upper layer water temperature and the lower layer water temperature can be detected, and that the retention of the water storage tank can be prevented using this temperature difference.
That is, the water tank management method of the present invention is a water tank connected to a water pipe (water main) supplying water to each house from a city water source, and water flowing in from an inflow port provided on one side. In the management method of the water tank that passes through the tank at a flow rate and is discharged from the outlet provided on the other side, the upper water temperature and the lower water temperature in the water tank are measured, and the upper water temperature and the lower water temperature are Based on the temperature difference, it is determined whether or not it is necessary to adjust the opening of a valve provided on the inlet side of the water tank.

  As described above, the temperature difference between the upper water temperature and the lower water temperature of the water tank is one of the factors that determine the mixing of the two-layer density flow in the water tank. Therefore, by measuring the upper layer water temperature and the lower layer water temperature and obtaining the temperature difference, it can be easily predicted whether or not the water tank is stagnant. Further, by determining whether or not the valve opening degree needs to be adjusted according to the predicted result, it is possible to take measures to prevent staying in the water tank.

Moreover, it is preferable to adjust the opening degree of the valve when the temperature difference between the upper layer water temperature and the lower layer water temperature of the water storage tank is equal to or higher than a preset threshold value.
Thus, when the temperature difference between the upper water temperature and the lower water temperature of the water storage tank is equal to or greater than the threshold value, the water storage tank is highly likely to stay. By increasing the flow velocity passing through the inside, it is possible to prevent stagnation in the water storage tank.

Furthermore, it is preferable to obtain the opening amount of the valve based on a retention judgment formula using the temperature difference between the upper layer water temperature and the lower layer water temperature of the water storage tank, and thereby the valve opening amount can be set appropriately. it can.
Furthermore, the retention judgment formula is preferably a Keulegan number calculation formula for obtaining a mixing condition in the two-layer density flow of the upper and lower layers of the reservoir, and thereby, in the reservoir due to the two-layer density flow. It is possible to reliably prevent stagnation.

Further, a plurality of water storage tanks are connected to a water pipe network including a plurality of the water pipes, and the upper layer water temperature and the lower layer water temperature respectively detected in the plurality of water storage tanks are acquired via a network, It is preferable to adjust the opening degree in cooperation with the valves provided for each of the plurality of water storage tanks based on the water supply distribution of the water pipe network.
In this way, by detecting the upper water temperature and lower water temperature of a plurality of water tanks, and adjusting the opening of each valve based on the water distribution of the water pipe network, The stagnation of the tank can be prevented.

  In addition, the storage tank management system according to the present invention is connected to a water pipe supplying water to each house from a city water source, an inlet provided on one side, an outlet provided on the other side, and the inlet A storage tank management system in which water flowing in from the inflow port passes through the tank with a flow velocity and is discharged from the outflow port, and the upper water temperature and the lower water temperature in the water storage tank And a calculation means having a necessity determination unit for determining whether or not the valve opening needs to be adjusted based on a temperature difference between the upper layer water temperature and the lower layer water temperature measured by the temperature measurement unit. It is characterized by comprising.

Further, the necessity determination unit of the calculating means adjusts the opening of the valve when a temperature difference between the upper layer water temperature and the lower layer water temperature of the water storage tank is equal to or higher than a preset threshold value. It is preferable to judge that it is necessary.
Moreover, it is preferable that the said calculating means has a valve opening calculation part which calculates | requires the opening amount of the said valve based on a residence judgment formula using the temperature difference of the said upper-layer water temperature of the said water tank, and the said lower-layer water temperature.

Furthermore, it is preferable to include a wireless communication unit that transmits the upper layer water temperature and the lower layer water temperature measured by the temperature measuring unit to the arithmetic unit via wireless communication.
Thus, the temperature of the water tank buried underground can be easily acquired by transmitting the upper layer water temperature measured by the temperature measuring means and the lower layer water temperature via wireless communication.

  Furthermore, a plurality of water storage tanks are connected to a water pipe network including a plurality of water pipes, and the calculation means includes position information of the water storage tanks in the water pipe network and opening information of each valve. And the upper layer water temperature and the lower layer water temperature detected respectively in the plurality of water storage tanks via a network, and the plurality of water storage tanks based on the water supply distribution of the water pipe network It is preferable to have a valve cooperation opening degree calculation unit that obtains an opening degree of the valve that is provided for each of them.

  As described above, according to the present invention, the temperature difference between the upper water temperature and the lower water temperature of the water tank is one of the factors that determine the mixing of the two-layer density flow in the water tank. Therefore, by measuring the upper layer water temperature and the lower layer water temperature and obtaining the temperature difference, it can be easily predicted whether or not the water tank is stagnant. Moreover, the measure which prevents the stay in a water tank can be taken by determining the necessity of valve opening degree adjustment according to the estimated result.

It is a basic lineblock diagram of a storage tank management system concerning an embodiment of the present invention. (A)-(C) are sectional side views which show the other structural example of a water storage tank. It is a flowchart of the management method of the water tank which concerns on embodiment of this invention. It is a schematic diagram which shows the water supply system containing a some water tank. It is a block diagram of the management system corresponding to a some water tank. It is a figure which shows the water temperature database which a management computer holds. It is a figure which shows the flow volume database which a management computer holds. It is side sectional drawing of the water tank of a general concept.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
FIG. 1 is a basic configuration diagram of a water tank management system according to an embodiment of the present invention.
The water tank management system according to the present embodiment mainly includes a temperature measuring device 20 installed in the water tank 10 and a calculation means to which a measurement result of the temperature measuring device 20 is input. In the present embodiment, an example using the management computer 30 is shown as the calculation means.

The water storage tank 10 (10A, 10B, 10C) which is a management target of the embodiment of the present invention is used for securing water supply such as water for daily life such as drinking water and water for fire extinguishing in preparation for a disaster.
As shown in FIG. 4, it connects to the water supply line 42 which supplies water to each house of the water supply target area 41 from city water sources 40, such as a reservoir.

  As shown in FIG. 1, the water storage tank 10 includes a horizontal cylindrical tank body 11, an inlet 12 provided on one side of the tank body 11, and an inlet pipe 13 connected to the inlet 12. And an outlet 14 provided on the other side, an outlet pipe 15 connected to the outlet 14, and a valve 16 provided in the outlet pipe 13 on the inlet 12 side. The inflow pipe 13 is directly connected to a water pipe 42 (water main) and supplied with water from the city water source 40. The outflow pipe 15 is directly connected to the water pipe 42 and supplies water to the water supply target area 41. In the water storage tank 10, water flowing in from the inlet 12 passes through the tank with a flow velocity and is discharged from the outlet 14. Furthermore, the water storage tank 10 has an emergency water intake 17 at the top and a water test tube (not shown) for inspecting the chlorine concentration and the like in the tank.

Here, as an example, the inlet 12 of the water storage tank 10 is provided at three locations, the upper part, the central part, and the lower part of the cross section of the tank body 11, and the outlet 14 is opposed to the upper part, the central part, and the lower part. The structure provided in the place is shown.
2A to 2C are side cross-sectional views illustrating other configuration examples of the water storage tank 10. FIG. 2A has five inflow ports 12a provided in the vertical direction and five outflow ports 14a in the same manner, all of which are directed to the end side of the tank body 11. . In FIG. 2B, the inflow port 12 b is formed by a porous tube provided along the side wall of the tank body 11, and the outflow port 14 b is formed by a porous tube provided along the other side wall. In FIG. 2C, an inlet 12c and an outlet 14c are provided in the axial direction of the tank body 11, and a swirling flow is generated by the inlet 12d.

Returning to FIG. 1, the temperature measuring device 20 includes at least a measuring unit 21 that measures the upper water temperature of the water storage tank 10 and a measuring unit 23 that measures the lower water temperature. Preferably, it may include a measuring unit 22 that measures the middle layer water temperature or a measuring unit that measures other portions having different heights in the vertical direction, and may measure the temperature distribution in the vertical direction.
The temperature measuring device 20 is preferably connected to a wireless communication device 25 that transmits the measured temperature data to the management computer 30 via wireless communication. Thus, the temperature of the water storage tank 10 buried underground can be easily sent by transmitting the upper layer water temperature and the lower layer water temperature measured by the temperature measuring device 20 via wireless communication.

  The management computer 30 determines whether or not the opening degree of the valve 16 needs to be adjusted based on the temperature difference between the upper water temperature and the lower water temperature measured by the temperature measuring device 20. Specifically, the management computer 30 includes an input unit 31 that inputs temperature data of the temperature measuring device 20, a storage unit 32 that stores a valve opening, a vertical temperature difference, and a threshold value, and a valve control necessity determination unit. 35, a calculation unit 33 including a Keulegan number calculation unit 35 and a valve opening amount calculation unit 36, and an output unit 37 that outputs a calculation result.

The valve control necessity determination unit 34 determines whether it is necessary to adjust the opening degree of the valve 16 of the water tank 10 based on the temperature difference between the upper water temperature and the lower water temperature of the water tank 10.
The Keulegan number calculation unit 35 calculates the Keulegan number based on the above-described arithmetic expression for the Keulegan number.
The valve opening amount calculation unit 36 calculates the opening amount of the valve 16 when the temperature difference between the upper layer water temperature and the lower layer water temperature of the water storage tank 10 is equal to or greater than a preset threshold value. The threshold value may be obtained experimentally or set based on the Keulegan number.

FIG. 3 is a flowchart showing an example of a water tank management method according to the embodiment of the present invention.
First, the upper water temperature and lower water temperature of the water storage tank 10 are measured by the temperature measuring device 20 (S1). The measured temperature data is transmitted to the management computer 30 by the wireless communication device 25 connected to the temperature measuring device 20.
In the management computer 30, first, the valve control necessity determination unit 34 makes a stay prediction (S2). The residence prediction compares the temperature difference between the upper layer water temperature and the lower layer water temperature with a preset threshold value (S3), and predicts that there is a possibility of residence if the temperature difference is larger than the threshold value. Then, the necessity of adjusting the valve opening is determined. Next, the number of Keulegan is calculated by the Keulegan calculating unit 35 (S4).
When the Keulegan number is larger than the limit value 0.127 (S6), it is determined that the risk of stagnation is large (S5), and the valve opening amount calculation unit 36 calculates the valve opening amount (S7). When the temperature difference between the upper layer water temperature and the lower layer water temperature is equal to or less than the threshold value (S3), and when the Keulegan number is equal to or less than the threshold value 0.127, it is determined that the water tank 10 is not retained ( S8).

As a modification of the present embodiment, as shown in FIG. 4, a water tank management system when water tanks 10A to 10C are connected to a water pipe network including a plurality of water pipes 42 will be described. The water storage tanks 10A to 10C are provided with valves 16A to 16C on the inlet side, respectively. Further, the water pipe network is provided with valves 43A to 43C for selecting a water supply distribution.
FIG. 5 is a configuration diagram of a management system corresponding to a plurality of water storage tanks 10.
In this system, temperature data measured in the plurality of water storage tanks 10 </ b> A to 10 </ b> C is sent to the management computer 30 via the wireless communication means 25 </ b> A to 25 </ b> C and the network 29. Moreover, the valve opening amount calculated | required with the management computer 30 is sent to the terminal 28A-28C near each valve 16A-16C, and the opening degree of a valve is adjusted.

In addition to the configuration shown in FIG. 1, the management computer 30 is provided for each of the plurality of water storage tanks 10 </ b> A to 10 </ b> C based on the upper layer water temperature and the lower layer water temperature measured by the temperature measuring device 20 and the water supply distribution of the water pipe network. It further has a valve cooperation opening degree calculation unit 38 for obtaining an opening degree in which the valves 16A to 16C provided respectively are linked.
Moreover, as shown in FIG.6 and FIG.7, in the memory | storage part 32, the flow volume database in which the water tank number for recognizing a water tank, the water tank passage flow rate, and the related valve opening degree were each linked | related, and water tank A water temperature database in which numbers, upper water temperature, and lower water temperature are associated with each other is stored.

In the above system, each time the valves 16A to 16C provided in the water storage tanks 10A to 10C are changed, the related valve opening data in the flow rate database is updated. At the same time, the storage tank passage flow rate (corresponding to the flow velocity) data obtained from the valve opening degree data is also updated. Further, in each of the water tanks 10A to 10C, the upper layer water temperature and the lower layer water temperature are measured intermittently or continuously by the temperature measuring device 20, and these water temperatures are transmitted by the wireless communication means 25A to 25C and managed via the network 29. Input from the input unit 35 of the computer 30. The previous water temperature data stored in the water temperature database is updated with the water temperature data of the input water tanks 10A to 10C. Then, based on the latest water tank passage flow velocity stored in the flow rate database and the latest upper layer water temperature and lower layer water temperature stored in the water temperature database, each of the valves 16A to 16C is based on the flow shown in FIG. The valve opening amount is calculated, and the valve opening amounts of the valves 16A to 16C and 43A to 43C satisfying the calculated valve opening amount and the distribution of the water supply to the water supply target area 41 are calculated. 38 is calculated. Based on the calculated valve opening, the opening of each of the valves 16A to 16C and 43A to 43C is adjusted. In addition, the opening degree adjustment of a valve here includes the case where an opening degree is not changed.
In this way, by detecting the upper water temperature and lower water temperature of a plurality of water tanks, and adjusting the opening of each valve based on the water distribution of the water pipe network, The stagnation of the tank can be prevented.

10, 10A, 10B, 10C Water storage tank 11 Tank body 12, 12a, 12b, 12c, 12d Inlet 13 Inlet pipes 14, 14a, 14b, 14c Outlet 15 Outlet pipes 16, 16A, 16B, 16C Valve 20 Temperature measuring device 21, 22, 23 Measuring unit 30 Management computer 32 Storage unit 33 Calculation unit 34 Valve control necessity determination unit 35 Keulegan number calculation unit 36 Valve opening amount calculation unit

Claims (10)

A water tank connected to a water supply line that supplies water to each house from a city water source, and water that flows in from an inlet provided on one side passes through the tank with a flow velocity, and is discharged from an outlet provided on the other side. In the water tank management method,
The necessity of adjusting the opening degree of the valve provided on the inlet side of the water storage tank based on the temperature difference between the water temperature of the upper water layer and the water temperature of the lower water layer based on the temperature difference between the upper water temperature and the lower water temperature. A method for managing a water tank, characterized in that   2. The water storage according to claim 1, wherein when the temperature difference between the upper water temperature and the lower water temperature of the water storage tank is equal to or higher than a preset threshold value, the opening degree of the valve is adjusted. Tank management method.   3. The water tank management method according to claim 1, wherein an opening amount of the valve is obtained based on a retention judgment formula using a temperature difference between the upper layer water temperature and the lower layer water temperature of the water tank.   4. The water tank management method according to claim 3, wherein the retention judgment formula is an arithmetic expression of a Keulegan number for obtaining a mixing condition in a two-layer density flow of an upper layer and a lower layer of the water tank. A plurality of the water storage tanks are connected to a water pipe network including a plurality of the water pipes;
Obtaining the upper layer water temperature and the lower layer water temperature respectively detected in the plurality of water storage tanks via a network;
4. The opening degree is adjusted in cooperation with each of the valves provided for each of the plurality of water storage tanks based on the distribution of water supply in the water pipe network. 5. Water tank management method. It is connected to a water pipe that supplies water to each house from a city water source, and has an inlet provided on one side, an outlet provided on the other side, and a valve provided on the inlet side. In the storage tank management system in which water flowing in from the inlet passes through the tank at a flow velocity and is discharged from the outlet,
Temperature measuring means for measuring the upper water temperature and the lower water temperature in the water tank;
And an arithmetic means having a necessity judging unit for judging whether or not the valve opening degree is necessary based on a temperature difference between the upper water temperature and the lower water temperature measured by the temperature measuring means. Water tank management system.   The necessity determination unit of the calculating means needs to adjust the opening of the valve when a temperature difference between the upper water temperature and the lower water temperature of the water storage tank is equal to or higher than a preset threshold value. The storage tank management system according to claim 6, wherein the storage tank management system is determined.   The said calculating means has a valve opening calculation part which calculates the amount of opening of the said valve based on a residence judgment formula using the temperature difference of the upper-layer water temperature and the lower-layer water temperature of the water tank. 8. The storage tank management system according to 7.   The wireless communication means for transmitting the upper layer water temperature and the lower layer water temperature measured by the temperature measuring means to the arithmetic means via wireless communication is provided. Water tank management system. A plurality of the water storage tanks are connected to a water pipe network including a plurality of the water pipes;
The calculation means includes a storage unit storing position information of the water tank in the water pipe network and opening information of each valve, and the upper layer water temperature and the lower layer water temperature respectively detected in the plurality of water tanks. And a valve cooperation opening degree calculation unit that obtains the opening degree of the valves provided for each of the plurality of water storage tanks based on the water distribution of the water pipe network. The water tank management system according to any one of claims 6 to 9.

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