Sheet electrode resistance type aeration concentration measuring instrument

Abstract

The utility model discloses a sheet electrode resistance-type aeration concentration measuring instrument, which comprises a water tank for accommodating an aeration solution to be measured; the first pole piece and the second pole piece are vertically and fixedly arranged on the inner wall of the same side of the pool at the same height, serve as resistance sensors and are in direct contact with the gas-liquid two-phase flow for measuring the resistance change of the gas-liquid two-phase flow; the data acquisition device is electrically connected with the first pole piece and the second pole piece and is used for measuring and recording air entrainment concentration data; the stirring mechanism is rotatably arranged in the water tank and is used for generating more uniform and dispersed bubbles in the measurement process and simulating an environment which is closer to the assumption of a Maxwell formula; according to the utility model, the simulation is closer to the environment assumed by the formula, and the accuracy of the aeration concentration measured value calculated by the Maxwell formula within the range of 0-80% is verified.

Description

Technical Field

[0001] The utility model relates to the technical field of aeration concentration measuring instruments, in particular to a sheet electrode resistive aeration concentration measuring instrument. Background Art

[0002] In water conservancy projects, aeration and erosion reduction is an important technical means, and the accurate measurement of aeration concentration is crucial for evaluating the erosion reduction effect.

[0003] The basic measurement principle of the resistive aeration concentration measuring instrument is the Maxwell model. The Maxwell model shows that several small spheres of material 2 are distributed inside a large sphere of material 1. The resistivity of material 1 is k1, and the resistivity of material 2 is k2. Assuming that there is no mutual influence between each small sphere, the distance between the small spheres needs to be much larger than the diameter of the small spheres.

[0004] Based on this assumption, Maxwell proposed an expression formula for the resistivity of the entire sphere, which can be expressed by the resistivity k1 of the large sphere of material 1 and the resistivity k2 of the small spheres of material 2. The expression formula is shown as follows.

[0005]

[0006] In formula (2-1), k1 is the resistivity of material 1; k2 is the resistivity of material 2; p is the volume percentage of the small spheres of material 2 in the entire sphere; K is the resistivity of the entire sphere.

[0007] Applying the above resistivity calculation formula to aerated water flow, material 1 is water and material 2 is air bubbles. Generally, air is an insulator and does not conduct electricity. Therefore, the resistivity k2 of the air bubbles is taken as positive infinity. Substituting it into the resistivity calculation formula can be simplified to obtain the volume percentage of air bubbles in the aerated water flow. The expression formula is shown as formula (2-2) below.

[0008]

[0009] In the formula, R0 is the static water resistance; RC is the gas-liquid two-phase flow resistance, that is, the aeration resistance.

[0010] In the paper "Exploration on the Reasons for the Unstable Measurement Results of the Sheet Electrode Resistive Aeration Concentration Meter" by Zhao Yibo, the unstable phenomena and reasons of traditional aeration concentration measuring instruments in gas-liquid two-phase flow measurement are discussed. It is pointed out that when the aeration concentration is less than 20%, the calculation results of the Maxwell formula are in good agreement with the true concentration; when the aeration concentration is greater than 20%, the calculated value of the Maxwell formula is smaller than the true value. And the reason for the deviation is analyzed. The bubbles in the gas-liquid two-phase flow often do not meet the basic assumptions of the Maxwell formula, and the distance between the bubbles is much larger than the diameter, resulting in unstable measurement results. And a new aeration concentration calculation formula is derived to solve this technical problem.

[0011] Obviously, the above solution is rather cumbersome. Therefore, it is an urgent technical problem to be solved to design a new resistive air-entrainment concentration measuring instrument to meet the environmental requirements of Maxwell's formula and ensure the accuracy of air-entrainment concentration measurement based on Maxwell's formula. Summary of the Invention

[0012] The purpose of the present invention is to provide a sheet electrode resistive air-entrainment concentration measuring instrument aiming at the problems existing in the prior art, which simulates an environment closer to the formula assumption and ensures the accuracy of the measured value of air-entrainment concentration calculated by Maxwell's formula in the range of 0-80%.

[0013] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0014] A sheet electrode resistive air-entrainment concentration measuring instrument includes: a water tank for containing the air-entrained solution to be measured; a first electrode plate and a second electrode plate, which are vertically and equally fixed on the inner wall of the same side of the water tank and directly contact the gas-liquid two-phase flow as a resistance sensor for measuring its resistance change; a data acquisition device electrically connected to the first electrode plate and the second electrode plate for measuring and recording the air-entrainment concentration data; a stirring mechanism rotatably arranged in the water tank for generating more uniform and dispersed bubbles during the measurement process to simulate an environment closer to the assumption of Maxwell's formula.

[0015] The long sides of the first electrode plate and the second electrode plate are vertically arranged, and both the first electrode plate and the second electrode plate are rectangular and have equal widths.

[0016] The stirring mechanism includes a stirring blade and a transmission rod, the stirring blade is fixed to the transmission rod, and the transmission rod is rotatably arranged inside the water tank.

[0017] The transmission rod is horizontally arranged in the water tank, and both ends of the transmission rod are rotatably connected to the opposite side walls of the water tank.

[0018] One end of the transmission rod passes through the side wall of the water tank and is connected to a driving motor, and the driving motor is fixed to the outer wall of the water tank.

[0019] The stirring mechanism includes a plurality of stirring blades, and the plurality of stirring blades are evenly spaced on the transmission rod.

[0020] The data acquisition device includes a millivoltmeter, an AC power supply and a data processing device. The millivoltmeter is used to measure the voltage across the electrode plate to reflect the resistance change; the AC power supply is used to provide a high-frequency AC signal to reduce the influence of electrode polarization on the measurement; the data processing device is used to receive the voltage measurement data and calculate the air-entrainment concentration according to a preset air-entrainment concentration calculation formula.

[0021] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0022] Compared with the traditional static aeration concentration measurement scheme, a stirring mechanism is added to the aeration concentration measuring instrument in this application, which can generate more uniform and dispersed bubbles to simulate an environment closer to the formula assumption, realizing dynamic measurement and ensuring the accuracy of the aeration concentration measurement value calculated by the Maxwell formula in the range of 0-80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic structural diagram of an aeration concentration measuring instrument in an embodiment of this application;

[0025] Figure 2 It is a comparison curve graph of the measured value and the true value of the two-phase flow aeration concentration in an embodiment of this application;

[0026] In the figure: 1, water tank; 2, first pole piece; 3, second pole piece; 4, stirring blade; 5, stirring rod; 6, driving motor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following will clearly and completely describe the technical solutions of the present utility model in conjunction with the drawings in the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present utility model belong to the scope of protection of the present utility model.

[0028] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this utility model is usually placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present utility model. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0029] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0030] In the description of the present utility model, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0031] The basic measurement principle of the resistive aeration concentration measuring instrument is the Maxwell model. The Maxwell model shows that several small spheres of material 2 are distributed inside a large sphere of material 1. The resistivity of material 1 is k1, and the resistivity of material 2 is k2. Assuming that there is no mutual influence between each small sphere, then the distance between the small spheres needs to be much larger than the diameter of the small spheres.

[0032] Based on this assumption, Maxwell proposed an expression formula for the resistivity of the entire sphere, which can be expressed by the resistivity k1 of the large sphere of material 1 and the resistivity k2 of the small spheres of material 2. The expression formula is shown as follows.

[0033]

[0034] In formula (2-1), k1 is the resistivity of material 1; k2 is the resistivity of material 2; p is the volume percentage of the small spheres of material 2 in the entire sphere; K is the resistivity of the entire sphere.

[0035] Applying the above resistivity calculation formula to aerated water flow, material 1 is water and material 2 is air bubbles. Generally, air is an insulator and does not conduct electricity. Therefore, the resistivity k2 of the air bubbles is taken as positive infinity. Substituting it into the resistivity calculation formula can be simplified to obtain the volume percentage of the air bubbles in the aerated water flow. The expression formula is shown as formula (2-2) below.

[0036]

[0037] In the formula, R0 is the static water resistance; RC is the resistance of the gas-liquid two-phase flow, that is, the aeration resistance. According to formulas (2-1) and (2-2), it can be seen that the aeration concentration is jointly determined by the static water resistance and the aeration resistance after the gas-liquid two-phase flow, and the distance between the air bubbles needs to be much larger than the diameter of the air bubbles.

[0038] In the paper "Investigating the Causes of Unstable Measurement Results of Sheet Electrode Resistive Aeration Concentration Meters," Zhao Yibo discusses the instability of traditional aeration concentration meters in gas-liquid two-phase flow measurements and their causes. He points out that when the aeration concentration is less than 20%, the results calculated using Maxwell's equations agree well with the true concentration; when the aeration concentration is greater than 20%, the calculated values are slightly lower than the true values. The paper also analyzes the reasons for this discrepancy: bubbles in gas-liquid two-phase flow often fail to meet the basic assumptions of Maxwell's equations; the distance between bubbles is much greater than their diameter, leading to unstable measurement results.

[0039] Therefore, it is necessary to design a new resistance-type aeration concentration measuring instrument to verify the accuracy of aeration concentration measurement based on Maxwell's formula when the aeration concentration is greater than 20%.

[0040] In response to the above problems, such as Figure 1 As shown, the present application provides a sheet electrode resistance type aeration concentration measuring instrument, comprising: a water pool 1, for accommodating the aerated solution to be measured; a first electrode 2 and a second electrode 3, which are fixed vertically and at the same height on the inner wall of the same side of the water pool 1, and are used as resistance sensors, directly contacting the gas-liquid two-phase flow to measure its resistance change; a data acquisition device, electrically connected to the first electrode 2 and the second electrode 3, to measure the aeration concentration; a stirring mechanism, rotatably arranged in the water pool 1, for generating more uniform and dispersed bubbles during the measurement process, simulating an environment that is closer to the assumptions of Maxwell's formula.

[0041] Specifically, the measurement process of the aeration concentration measuring instrument in this embodiment is as follows:

[0042] Add a certain height of clean water into the water tank until the water level stabilizes, and record the water level H at this time.

[0043] Use a high-frequency AC power supply, measure the voltage on the first electrode 2 and the second electrode 3 with a millivoltmeter, obtain the two-phase flow voltage reading U, and calculate the clear water resistance R0;

[0044] Gradually add gas into clean water to simulate gas-liquid two-phase flow;

[0045] Also use high-frequency AC power supply to drive the stirring mechanism to rotate, and set the speed of the stirring rod 5. The stirring blade 4 drives the water flow, and measures and records the two-phase flow resistance Rc at different speeds;

[0046] The aeration concentration Cm is calculated using Maxwell's formula and the known clean water resistance R and two-phase flow resistance Rc.

[0047] Repeat the above steps to obtain the aeration concentration Cm under different submergence depths. The submergence depth is defined as the percentage of the height of the electrode in contact with water to the entire electrode height. The data is plotted into a graph as shown in the figure below. Figure 2As shown, the abscissa represents the submergence depth, and the ordinate represents the measured value of the aeration concentration.

[0048] In Figure 2 when the rotational speed is 40 r / s and the aeration concentration value is in the range of 0 - 80%, the difference between the curve representing 40 r / s and the standard curve is small. That is, the aeration concentration value calculated based on the Maxwell formula is relatively consistent with the aeration concentration reflected by the relative submergence depth of the electrode plate, indicating that in this case, the aeration concentration value calculated based on the Maxwell formula is relatively accurate.

[0049] Compared with the traditional static aeration concentration measurement scheme, in this embodiment, a stirring mechanism is added to the aeration concentration measuring instrument, which can generate more uniform and dispersed bubbles to simulate an environment closer to the formula assumption, realizing dynamic measurement and ensuring the accuracy of the measured value of the aeration concentration calculated by the Maxwell formula in the range of 0 - 80%. That is, through the adjustment and improvement of the device and the power mode, the accurate range of the pole piece measurement reaches 0 - 80%, which is much wider than the measurement range of the existing device.

[0050] It should be noted that the aeration concentration reflected by the relative submergence depth of the electrode plate can be regarded as the true aeration concentration, and its principle has been described in detail in the third part of the paper "Research on the Reasons for the Unstable Measurement Results of the Sheet Electrode Resistance Type Aeration Concentration Meter", which is prior art and will not be elaborated in this application.

[0051] In some embodiments, the long sides of the first pole piece 2 and the second pole piece 3 are vertically arranged, and both the first pole piece 2 and the second pole piece 3 are rectangular and have the same width. This arrangement makes the two pole pieces form a relatively stable spherical electric field in the gas-liquid two-phase flow to meet the requirements of the Maxwell model, making the measurement of the resistance more accurate.

[0052] In some embodiments, the stirring mechanism includes a stirring blade 4 and a transmission rod 5. The stirring blade 4 is fixed to the transmission rod 5, and the transmission rod 5 is rotatably arranged inside the water tank 5. Ensure that the stirring blade 4 can rotate in the water tank to generate a uniform bubble distribution.

[0053] In some embodiments, the transmission rod 5 is horizontally arranged inside the water tank 1, and both ends of the transmission rod 5 are rotatably connected to the opposite side walls of the water tank 1. Reduce rotation vibration and offset, and improve the stirring effect.

[0054] In some embodiments, one end of the transmission rod 5 passes through the side wall of the water tank 1 and is connected to a driving motor 6, and the driving motor 6 is fixed to the outer wall of the water tank 1. The driving motor 6 provides rotational power, enabling the transmission rod 5 and the stirring blade 4 to work at a set rotational speed and rotation direction.

[0055] In some embodiments, the stirring mechanism includes a plurality of stirring blades 4, and the plurality of stirring blades 4 are evenly spaced on the transmission rod 5. The evenly spaced stirring blades 4 can make the bubbles in the aerated solution more evenly distributed during rotation, thereby improving the accuracy of aeration concentration measurement.

[0056] In some embodiments, the data acquisition device includes a millivoltmeter, an AC power supply, and a data processing device. The millivoltmeter is used to measure the voltage across the electrode plate to reflect the resistance change; the AC power supply is used to provide a high-frequency AC signal to reduce the influence of electrode polarization on the measurement; the data processing device is used to receive the voltage measurement data and calculate the aeration concentration according to a preset aeration concentration calculation formula.

[0057] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A sheet electrode resistive air entrainment concentration measuring instrument, characterized in that, Comprising: A water tank (1) for containing the aerated solution to be measured; A first electrode plate (2) and a second electrode plate (3), vertically and equally high, are fixedly arranged on the inner walls on the same side of the water tank (1), serving as a resistance sensor to directly contact the gas-liquid two-phase flow for measuring its resistance change; A data acquisition device, electrically connected to the first electrode plate (2) and the second electrode plate (3), for measuring and recording the aeration concentration data; A stirring mechanism, rotatably arranged in the water tank (1), for generating more uniform and dispersed bubbles during the measurement process to simulate an environment closer to the assumptions of Maxwell's formula.

2. The sheet electrode resistive aeration concentration measuring instrument according to claim 1, characterized in that The long sides of the first electrode plate (2) and the second electrode plate (3) are vertically arranged, and both the first electrode plate (2) and the second electrode plate (3) are rectangular and have equal widths.

3. A sheet electrode resistive aeration concentration measuring instrument according to claim 1, characterized in that The stirring mechanism includes a stirring blade (4) and a transmission rod (5), the stirring blade (4) is fixed to the transmission rod (5), and the transmission rod (5) is rotatably arranged inside the water tank (1).

4. The sheet electrode resistive aeration concentration measuring instrument according to claim 3, characterized in that, The transmission rod (5) is horizontally arranged in the water tank (1), and both ends of the transmission rod (5) are rotatably connected to the opposite side walls of the water tank (1).

5. A sheet electrode resistive aeration concentration measuring instrument according to claim 4, characterized in that, One end of the transmission rod (5) passes through the side wall of the water tank (1) and is connected to a driving motor (6), and the driving motor (6) is fixed to the outer wall of the water tank (1).

6. A sheet electrode resistive aeration concentration measuring instrument according to claim 4, characterized in that, The stirring mechanism includes a plurality of stirring blades (4), and the plurality of stirring blades (4) are evenly spaced on the transmission rod (5).

7. A sheet electrode resistive aeration concentration measuring instrument according to claim 1, characterized in that, The data acquisition device includes a millivoltmeter, an AC power supply, and a data processing device. The millivoltmeter is used to measure the voltage across the electrode plates to reflect the resistance change; the AC power supply is used to provide a high-frequency AC signal to reduce the influence of electrode polarization on the measurement; the data processing device is used to receive the voltage measurement data and calculate the aeration concentration according to a preset aeration concentration calculation formula.

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