KR100477090B1 - Flow meter for open channel and thereof flow measuring method by using principle of electromagnetic induction - Google Patents

Abstract

The present invention relates to a flow meter in a channel using an electromagnetic induction principle and a method for measuring the flow rate thereof, comprising: a magnetic generator having a solenoid-type excitation coil embedded in a central portion of a width of a bottom surface of a channel; A pair of electromotive force sensing electrodes built around the excitation coil of the magnetic generator and spaced apart from each other so as to detect and measure the induced electromotive force induced by the flow rate of the fluid that flows through the magnetic field generated by the excitation coil; ; A microprocessor disposed near the channel so as to apply current to the excitation coil of the magnetic generator and to receive, store, calculate, and display the induced electromotive force measured by the electromotive force sensing electrode; It is electrically connected to the calculator and configured to include an ultrasonic level meter spaced apart from the water surface of the channel so as to measure the level of the fluid, and then the measured values such as the induced electromotive force and the level measured by each component are induced. Substitute the flow rate calculation formula using the principle to measure the flow rate of the fluid flowing through the water channel for a certain time.

According to the present invention, since the flow rate can be measured without having any correlation with the fluid flowing through the water channel, the energy efficiency is high, the response speed is fast, the measurement error is small, the reliability is high, and third, foreign matter present in the fluid As it is not influenced by, it is stable and its installation is simple, thus providing the advantage of low construction cost.

Description

Flow meter to the channel using the electromagnetic induction principle and its flow measurement method {FLOW METER FOR OPEN CHANNEL AND THEREOF FLOW MEASURING METHOD BY USING PRINCIPLE OF ELECTROMAGNETIC INDUCTION}

The present invention relates to a flow meter and a method for measuring the flow rate of the channel using the improved electromagnetic induction principle to easily measure the flow rate through the channel by applying the Faraday law.

In general, the channel refers to a channel, such as a ditch, in which a fluid such as water has a free surface and flows from a high place to a low place due to a position difference. It is roughly divided into open channels such as

The amount of fluid flowing while maintaining free water through these channels can be measured via a flow meter.

Conventionally, three types of flowmeters, such as weir type, flume type, and flow rate level calculation method, are commonly used according to the measurement method. By installing a plate to block the flow of fluid and measuring the height of the water flowing over the wear plate, Bernoulli's theorem is a method of measuring the flow rate, depending on the shape of the wear plate, such as the square, triangle, trapezoidal shape.

In the case of the prum type, if the cross section of the channel is narrowed so that the flow path is reduced, the flow velocity becomes faster at the reduced portion, and the level of the portion is lower than the upstream level. As a method of calculating the flow rate by using, there are Venturiprum, Partialprum, and Farmerborasprum depending on the shape.

In the case of the flow rate level calculation method, the average flow velocity and the cross-sectional area of a fluid flowing in a water channel are continuously measured according to the propagation time difference method of ultrasonic waves, and the flow rate is calculated by multiplying these two values.

However, in the case of ware type and prum type, the flow rate can be measured simply by measuring the water level, so the structure is simple, and there is an advantage in measurement, but it is difficult to construct the wear plate or the channel so that the construction is difficult and costly.

In addition, these methods have a disadvantage in that energy wasted due to water level loss during the measurement process because the flow rate was measured by changing the water surface by blocking the waterway with a wear plate or narrowing the waterway to give resistance to the waterway.

In addition, since the flow rate must be measured through a small change in water level, the measurement error is very large, and errors due to the water level change due to wind or other external factors cannot be corrected.

In addition, in the case of wear type, foreign substances are easily deposited in the upstream channel of the wear plate, and it is not possible to use it for factory wastewater and sewage containing a large amount of solids. When calculating the flow rate value, the error range is close to 20-30%, and there is a disadvantage that the measured value cannot be used as data.

In addition, in the case of the velocity level calculation method, the velocity is measured through the propagation time difference method using ultrasonic waves, so the surface and the velocity difference become very large due to the friction between the bottom and the wall in the channel, so that the average velocity is measured by a single receiver. This is impossible, and in order to compensate for this, it is necessary to install a plurality of sets of ultrasonic receiving and receiving devices, which is difficult and complicated to install.

The present invention has been created in view of the above-described problems of the prior art, to solve this problem, the construction is easy to reduce the construction cost and reduce the measurement error to increase the reliability of the measured value and at the same time there is no loss of water level The purpose of the present invention is to provide a flow meter and a method of measuring the flow rate of a channel using an electromagnetic induction principle, which can reduce energy waste and include errors in water level changes caused by wind or other external factors.

The above object of the present invention is a magnetic generator having a solenoid type excitation coil embedded in the center width of the bottom surface of the water channel; A pair of electromotive force sensing electrodes built around the excitation coil of the magnetic generator and spaced apart from each other so as to detect and measure the induced electromotive force induced by the flow rate of the fluid that flows through the magnetic field generated by the excitation coil; ; A microprocessor disposed near the channel so as to apply current to the excitation coil of the magnetic generator and to receive, store, calculate, and display the induced electromotive force measured by the electromotive force sensing electrode; It is achieved by providing a flow meter to the channel using the electromagnetic induction principle, characterized in that it is electrically connected to the calculator and comprises an ultrasonic level meter spaced apart from the water surface of the channel to measure the level of the fluid. .

In addition, the above object of the present invention is the process of obtaining an average flow rate for a certain time of the fluid flowing through the channel by the equations 2, 3 described in the configuration to be described later using Faraday's law of electromagnetic induction; Obtaining a cross-sectional area of the fluid flowing through the measurement time by using Equation 4, which will be described later, using an ultrasonic level meter installed on the fluid; Using the obtained average flow rate and cross-sectional area to provide a flow rate measuring method of the channel using the electromagnetic induction principle, characterized in that it comprises the process of obtaining a fluid flow rate for a certain time through the channel through the equation 5 to be described later. Is achieved.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

1 is a partial perspective view of an open waterway showing an exemplary installation of a flow meter in accordance with the present invention.

According to FIG. 1, in the present invention, a water channel 10 is provided, and a magnetic force generator 20 is installed on a bottom surface of the water channel 10, and an electromotive force sensing electrode 30 is built into the magnetic force generator 20. The magnetic force generator 20 and the electromotive force sensing electrode 30 are connected to the calculator 40 by conducting wires 62, respectively, and are spaced apart from the upper surface of the channel 10 so that the water level can be measured. 50 is installed, the ultrasonic level measuring device 50 is made of a configuration that is electrically connected to the calculator 40.

The water channel 10 is an open water channel with an open top, and can be applied to a water channel such as an agricultural water channel.

The material of the channel 10 may be concrete, wood, metal, synthetic resin (FRP) and the like.

The magnetic force generator 20 has a housing 22 made of a cylindrical synthetic resin and a solenoid-type excitation coil 24 wound and disposed inside the housing 22 and an insulating material filled in the housing 22 so as to properly insulate them. (Weapons).

The excitation coil 24 constituting the magnetic force generator 20 is electrically connected to the calculator 40 having a power supply means and the conducting wire 62 so that the current can be energized, the current to the excitation coil 24 When flowing through the magnetic field lines 64 as shown in the example is configured to form a magnetic field that is variable according to the strength of the current around the excitation coil 24.

Particularly, the magnetic force generator 20 cuts a portion of the bottom surface of the channel 10 so that the top surface thereof is exposed to form the same plane that is flush with the bottom surface of the channel 10 and at the same time the channel 10 is exposed. It is preferable to excrete at the center of the width.

The electromotive force sensing electrode 30 is embedded in the housing 22, and is usually disposed to face each other by a distance corresponding to the diameter of the housing 22, and is insulated by the insulating material.

In addition, a conductive line 62 is drawn out from the lower end of the electromotive force sensing electrode 30 and is electrically connected to the calculator 40 in the same manner as the excitation coil 24.

The calculator 40 has a power supply means for supplying current to the excitation coil 24, and at the same time, the conductor fluid flows through the magnetic field generated by the excitation coil 24, thereby changing the flow velocity in the fluid. Data such as the electromotive force sensing electrode 30 capable of detecting induced electromotive force, the detected value and magnetic flux density of the magnetic field, and the water level flowing through the channel 10 measured by the ultrasonic level gauge 50 to be described later. It can be something like a microprocessor that can store, operate on, and display it.

The calculator 40 may be installed in a protective box (not shown) spaced apart from the channel 10 by a certain distance for ease of measurement. Also, the calculator 40 may directly install a separate protective box on one side wall of the channel 10 and the inside thereof. It can also be placed in.

The ultrasonic level measuring unit 50 may be electrically connected to the calculator 40 and installed at a predetermined length on the upper surface of the center portion of the channel 10 by a separate support.

The ultrasonic water level measuring instrument 50 is a conventionally known device comprising a transmitter for oscillating ultrasonic waves, and a receiver for receiving each reflected wave reflected from the surface of the fluid flowing through the water channel 10 after being oscillated. Since the distance from 50 to the bottom surface of the channel 10 is determined, the distance between the water surface and the ultrasonic water level gauge 50 is measured from the reflected wave information reflected from the surface and the value is determined from the bottom surface of the channel 10. It is a device that can calculate the water level simply by subtracting from the distance value of.

The method for measuring the flow rate along the channel using the flow meter of the present invention having such a configuration will be described with reference to FIG. 2, which is a schematic diagram for explaining the method according to the present invention.

First, the principle of measuring the flow rate of the fluid flowing through the waterway 10 will be described in general. The flow rate of the fluid flowing through the waterway 10 having a predetermined width is multiplied by the cross-sectional area through which the fluid passes. It can be easily obtained by integrating over a certain period of time. The average flow rate is the electromotive force generated in the direction perpendicular to both the magnetic field direction and the movement direction when the conductor moves in the magnetic field. It can be calculated from Faraday's law that is proportional to the speed of movement of the conductor.

Therefore, by appropriately calculating these values, it is possible to easily measure the flow rate through the channel 10.

That is, as illustrated in FIGS. 1 and 2, the flow rate Q of the fluid flowing through the water channel 10 for a predetermined time t is

------------------------------------------------- ( Equation 1)

Can be defined as Is the average flow velocity of the fluid, A is the cross-sectional area and t is the measurement time.

In order to satisfy the above Equation 1, in the present invention, the average flow velocity through the channel 10 through Faraday's law of electromagnetic induction ( ) Process.

That is, the conductor fluid has an average flow velocity in the magnetic field formed by the excitation coil 24 of the magnetic force generator 20 along the channel 10. ), The electromotive force is generated by the flow in a direction perpendicular to the direction of the magnetic field and the direction of motion in the fluid, the magnitude of which is proportional to the magnetic flux density and speed.

Accordingly, electromotive force is induced in the electromotive force sensing electrode 30 disposed adjacent to the excitation coil 24 in proportion to the velocity of the fluid or the magnitude of the magnetic flux density generated from the excitation coil 24. 40).

Such induced electromotive force (E),

-------------------------------------------------- (Eq. 2)

Where K is a constant, B is the magnetic flux density, and D is the distance between the electromotive force sensing electrodes.

Accordingly, the average flow rate (Equation 2) ),

------------------------------ (Equation 3)

It can be expressed as

That is, these K, B, D, and E values are determined or can be known through measurement. ) Can be calculated easily.

Subsequently, a process of obtaining a cross-sectional area A through which the fluid flows through the measurement time t is performed.

Since the cross-sectional area (A) is the width (W) of the channel 10, the fluid level (H), that is, the distance from the bottom surface of the channel 10 to the water surface, the cross-sectional area (A),

-------------------------------------------------- ---- (Equation 4)

Can be expressed as

At this time, the water level (H), as described above, the water channel 10 from the ultrasonic level meter 50 that already knows the distance (L2) to the water surface of the fluid measured through the transmitter and receiver of the ultrasonic level meter 50 By subtracting from the distance (L1) to the bottom surface of the can be obtained easily.

If the values necessary for calculating the flow rate Q are calculated and determined through the above-described process, the calculator 40 uses these values to calculate the flow rate of the fluid flowing through the water channel 10 during the measurement time T by Equation 5 below. The flow rate Q is calculated and weighed.

That is, the flow rate Q is substituted by the values of the above formulas 1 to 4,

---------- (Eq. 5)

Finally, it is possible to calculate, for example, by integrating the measured value induced electromotive force (E) and the water level (H) by the time (t), and then multiply by a constant (K ") to the channel 10 for a predetermined time. The flow rate through the flow can be obtained.

The flow rate value measured through the above process may be displayed in real time through a display stored in or stored in the storage unit of the calculator 40, or may be stored and documented for a certain period of time and used as a statistical value.

According to the present invention, the measurement error commonly caused by the conventional method can be greatly reduced, and the flow rate can be measured without any influence on the change of the water level due to other external influences such as wind.

In addition, the flow meter and the flow measurement method according to the present invention can calculate a very desirable measurement value when the magnetic field is uniform, while minimizing the measurement error regardless of the uniformity and non-uniformity of the magnetic field when the fluid has an axisymmetric flow The flow rate of the fluid can be measured simply and easily.

As described in detail above, the present invention provides the following effects.

First, because the flow rate can be measured without having any correlation with the fluid flowing through the channel, the energy efficiency is high and the response speed is fast.

Second, since the average flow velocity is calculated directly to calculate the flow rate of the fluid, the measurement error is very small and the reliability is high.

Third, it is stable because it is not affected by foreign matter present in the fluid.

Fourth, the installation cost is simple because of the simple installation.

Fifth, in the case of the conductive fluid, the flow rate can be easily measured regardless of the temperature, pressure, density, viscosity, electrical conductivity, etc. of the fluid.

1 is a partial perspective view of an open water channel showing a typical installation example of the flow meter according to the present invention,

Figure 2 is a schematic diagram illustrating a method for measuring the flow rate of the channel using the electromagnetic induction principle according to the present invention.

Explanation of symbols on the main parts of the drawings

10: channel 20: magnetic generator

22: housing 24: female coil

30: electromotive force sensing electrode 40: calculator

50: Ultrasonic Water Level Meter

Claims (3)

A magnetic generator having a solenoid-type excitation coil wound and embedded in a housing of a central portion of the bottom width of the channel; In order to detect and measure the induced electromotive force induced by the flow rate of the fluid that flows through the magnetic field generated by the excitation coil, the insulation coil is installed separately from the excitation coil in the housing and spaced apart from each other. A pair of electromotive force sensing electrodes; A microprocessor disposed near the channel so as to apply current to the excitation coil of the magnetic generator and to receive, store, calculate, and display the induced electromotive force measured by the electromotive force sensing electrode; And an ultrasonic level meter electrically connected to the calculator and spaced apart from the water surface of the channel, having a transmitter and a receiver so as to measure the level of the fluid. delete A first step of obtaining an average flow velocity of a fluid flowing through the channel for a predetermined time by Equation 1 below using Faraday's law of electromagnetic induction; A second step of obtaining a cross-sectional area of the fluid flowing through the measurement time by using Equation 2 below using an ultrasonic level meter installed on the fluid; Using the average flow rate and the cross-sectional area obtained in the first process and the second process, the electromagnetic induction principle, characterized in that it comprises the process of obtaining a fluid flow rate for a certain time through the channel through the following equation (3) How to measure the flow rate to the used channel. (Equation 1) (E is the induced electromotive force, K is the constant, B is the magnetic flux density, D is the distance between the electromotive force sensing electrodes, Is the average flow rate) (Equation 2) , (A is the cross-sectional area, W is the width of the channel, and H is the water level) (Equation 3) (Q is the flow rate of the fluid)