High-precision non-full pipe electromagnetic flowmeter

Abstract

High-precision non-full pipe electromagnetic flowmeter. It is provided with a non-metallic pipe. Upper and lower excitation coils are fixed on the vertical Z center line of the outer wall of the pipe, and a silicon steel sheet enclosure is arranged outside the pipe. A pair of induction electrodes with an included angle A = 0.1° - 90° are installed on the left and right in the Y direction of the pipe. A thermometer and a grounding electrode are installed at the bottom of the pipe. Close to the inner wall of the pipe is the electrode plate layer: Two groups of arc-shaped metal electrode plate assemblies are symmetrically arranged circumferentially with the vertical center line as the axis. The arc included angle B of each group is 180° - A°, and it is formed by the optimized configuration of multiple main electrode plates and auxiliary electrode plates inside. There is a large insulation distance for anti-interference between the electrodes and the electrode plates. A cylindrical insulation lining is laid on the inner wall of the electrode plate layer, and the fluid flows axially along the inner wall of the lining in the X direction. The top converter collects the induced electromotive force and the dielectric constant of the electrode plates, and processes the signals to determine and display the flow rate. The non-metallic pipe is connected to the external measured pipe through the flanges at both ends. Through the optimized design and configuration of the electrode plates, the present invention obtains accurate dielectric constants, greatly improving the detection accuracy. It solves the problem of low detection accuracy of existing methods such as ultrasonic waves. It is used for measuring the water volume of sewage pipes.

Description

(1) Technical Field

[0001] The high-precision non-full pipe electromagnetic flowmeter of the present invention relates to flow measurement and belongs to the category of G01F for fluid flow and liquid level measurement. (2) Background Art

[0002] An ordinary electromagnetic flowmeter measures the flow rate by measuring the average flow velocity with a constant cross-sectional area of the measured pipeline. The cross-sectional area of the fluid in the non-full pipe changes with time. The flow rate measurement not only needs to measure the average flow velocity through the pipeline, but also needs to measure the cross-sectional area of the fluid flowing through the pipeline. That is to say, the flow rate measurement of the non-full pipe electromagnetic flowmeter requires at least two variables: the flow velocity V and the liquid level H. It consists of a flow velocity measurement part and a liquid level measurement part.

[0003] For the non-full pipe electromagnetic flowmeters disclosed in the existing Chinese patents, in order to improve the measurement accuracy, various different structures and methods are generally provided to solve the problems caused by various restrictive factors such as the conductivity of the fluid in the measured pipeline, the fluid characteristics, the flow pattern distribution, the resistance of the measuring pipe material, and the pipeline diameter size, so as to make improvements.

[0004] In the existing publicly used domestic sewage treatment pipelines, in order to measure the non-full pipe flow velocity and liquid level, the non-full pipe flowmeter structures and existing manufacturing methods adopted (for example, the ultrasonic method) have inaccurate measured flow rates and low accuracy. (3) Summary of the Invention

[0005] The high-precision non-full pipe electromagnetic flowmeter provided by the present invention solves the problem of extremely low accuracy in measuring the sewage liquid level and flow rate, etc. in the current sewage pipelines by using ultrasonic waves, etc.

[0006] Technical Solution

[0007] The high-precision non-full pipe electromagnetic flowmeter includes: a converter, and its characteristics are

[0008] I. Provide a non-metallic pipeline 1, and set the following on the central section XO with an axial length of X1: 1) On the outer surface of the non-metallic pipeline wall, a upper excitation coil 2a is fixed above in the vertical direction Z, and a lower excitation coil 2b is fixed below; a multi-faceted silicon steel sheet enclosure 3 surrounding the outer circumference of the non-metallic pipeline is provided in the excitation magnetic circuit. 2) Two induction electrodes 4a and 4b are symmetrically fixed in the Y direction to the left and right below the non-metallic pipeline with the vertical center line Zo, and the circumferential angle A between the two induction electrodes is 0.1 - 90°; one end of each induction electrode passes through the pipeline wall hole to contact the fluid, and the other end is connected to the socket 4.1 outside the pipeline wall hole and led to the converter 11 with a lead wire 4.2; a shielded and enclosed outer shell 7 is installed in the outer peripheral space of the non-metallic pipeline. II. Metal pipes 9 extend out from both outer ends of the non-metallic pipeline 1 axially, and are provided with flange plates 10; used to connect to the flange plates 12 of the measured pipelines at both external ends; the axial length between the two flange plates 10 is X10. III. A plate layer 5 is provided closely attached to the inner wall of the non-metallic pipeline 1: Two groups of arc-shaped metal plate assemblies 5A and 5B are symmetrically arranged in the Y direction along the vertical center line Zo, and the inner arc angle B of each group is 180° - A; the number of main plates NX fixed axially in each group of arc-shaped metal plate assemblies is 1 or 2; the number of main plates NZ fixed vertically along the inner wall arc is 1; there is an insulating gap 5Δ between adjacent main plates; the axial length X5 of each group of arc-shaped metal plate assemblies is less than the length X1 of the non-metallic pipeline 1. IV. A cylindrical insulating lining 6 is laid closely attached to the inner wall of the inner plate layer 5 of the non-metallic pipeline; its length X6 is the axial length X10 between the two flange plates 10; the fluid flows axially along the inner wall of the cylindrical insulating lining 6. V. A thermometer 8 for measuring the fluid temperature is installed on the axial center line at the bottom of the non-metallic pipeline 1. VI. An earthing resistance 4o is fixed on the axial center line outside the bottom pipe wall of the non-metallic pipeline 1.

[0009] The measurement principle and method of the present invention are as follows:

[0010] 1) Known data obtained by the flowmeter: ① The inner diameter D of the pipeline through which the fluid flows (see Figure 1 ). ② The induced electromotive force E of the induction electrode collected by the converter. ③ The surface or space dielectric constant K of the main plate collected by the converter. ④ The fluid temperature T detected by the thermometer 8 collected by the converter. ⑤ The flow velocity coefficient K1 obtained from the flowmeter test.

[0011] 2) Establish a mathematical model of the liquid level height h varying with the dielectric constant k and the fluid temperature t, that is, the function h = f(k, t).

[0012] 3) Obtain the corresponding liquid level height H at this moment from the known collected dielectric constant K, fluid temperature T, and the mathematical model.

[0013] 4) From the known inner diameter D of the pipeline and the liquid level height H obtained from the mathematical model, determine the cross-sectional area S of the conductive fluid at this moment by the following formula <1>:

[0014]

[0015] 5) Determine the average flow velocity V = K1E at this moment on the cross-section. ……<2>

[0016] In the above formula <2>, the flow velocity coefficient K1 and the induced electromotive force E are known data that have been obtained.

[0017] 6) Determine the fluid flow rate Q = S V at this moment. ……<3>

[0018] In the above formula <3>, S is the cross-sectional area of the conductive fluid, and V is the average flow velocity of the fluid (the average value of the flow velocities at various positions on the cross-section).

[0019] According to the description of the above technical solution, principle and method, it can be obtained that: in the flow velocity measurement part of the present invention, according to Faraday's law of electromagnetic induction, the conductive fluid moves in the magnetic field, and an induced electromotive force E is generated in the direction perpendicular to the magnetic field direction and the fluid movement direction, so as to measure the flow velocity V of the fluid. The liquid level measurement part uses the dielectric constant method for measurement. The flowmeter adopts different structures, especially different configurations of the main and auxiliary electrodes. The corresponding dielectric constant K of the fluid medium is different. The liquid level is measured by measuring the change of the dielectric constant; and then the cross-sectional area S of the fluid is obtained through the change of the obtained liquid level H. It is a measuring instrument for measuring the fluid flow rate in the pipeline by using the flow velocity - area method.

[0020] Advantages of the present invention:

[0021] 1) A pair of upper and lower exciting coils 2a, 2b are designed to generate an alternating magnetic field. Through a silicon steel sheet enclosure 3, the alternating magnetic flux is enclosed, so that the non-metallic pipeline 1 is filled with a vertical Z alternating magnetic field. When the fluid is introduced axially along the X direction through the inner hole of the flange in the non-metallic pipeline, and the liquid level submerges the two induction electrodes 4a, 4b on both sides of the radial Y at the midpoint position of the axial X, the connection line of the two induction electrodes is the radial Y, which is perpendicular to the magnetic field direction Z and the fluid movement direction X. According to Faraday's law of electromagnetic induction, the two induction electrodes 4a, 4b generate an induced electromotive force E, thus realizing the measurement of the fluid flow velocity.

[0022] 2) The electrode layer 5 closely attached to the inner wall of the non-metallic pipeline 1 is used to measure the dielectric constant K in the non-metallic pipeline 1. The two sets of arc-shaped metal electrode assemblies are composed of 2 - 4 main electrodes or 2 additional auxiliary electrodes. Selecting this optimized configuration of the electrode assembly can make the measurement of the dielectric constant K more accurate.

[0023] 3) The methods for measuring the dielectric constant are divided into the surface dielectric constant method and the space dielectric constant method. The surface dielectric constant is measured by collecting data and connecting two main plates, namely the left front main plate 5A1 and the left rear main plate 5A2, or the right front main plate 5B1 and the right rear main plate 5B2. The space dielectric constant method is measured by collecting data and connecting the left front main plate 5A1 and the right front main plate 5B1, or by connecting the left rear main plate 5A2 and the right rear main plate 5B2. Providing such a plate system with multiple connection combinations is beneficial for the flowmeter to establish a mathematical model when determining the liquid level, that is, the function h = f(k, t).

[0024] 4) The included angle A between the two induction electrodes 4a and 4b is 0.1 - 90°. For each group of arc-shaped metal plate assemblies 5, the arc included angle B is 180 - A. At the midpoint of the axial direction X, the two groups of arc-shaped plate assemblies and the two induction electrodes do not intersect vertically, and the measurement of the flow rate and the liquid level does not affect each other. There is a sufficient anti-interference distance between the main plate below the plate layer and the induction electrodes 4a and 4b. All these designs ensure high measurement accuracy.

[0025] 4) The arc surfaces of the main plate and the auxiliary plate are embedded and fixed in the concave grooves on the inner wall of the non-metallic pipeline in contact, making it convenient to install and position multiple plates without displacement; a convex insulation gap 5Δ is naturally formed between adjacent plates.

[0026] 5) The axial lengths of the two groups of arc-shaped metal plate assemblies 5A and 5B are both less than the axial length X1 of the non-metallic pipeline. The axial length of the cylindrical insulation lining 6 is equal to the axial length X10 between the two flanges 10, which can prevent fluid from entering the plate layer. (IV) Description of the Drawings

[0027] Figure 1 Axial front sectional view (Z - X plane) of the present invention.

[0028] Figure 2 For Figure 1 A - A sectional view (Z - Y plane) of

[0029] Figure 3 For Figure 1 B - B sectional view (Y - X plane) of

[0030] Figure 4 Stereogram of the plate layer 5 on the inner wall of the non-metallic pipeline within the closed body of silicon steel sheets. (The cylindrical insulation lining 6 inside the pipeline is removed to show the layout of all components of the plate layer inside the pipeline)

[0031] Figure 5 Stereogram of the non-metallic pipeline inner wall with a cylindrical insulation lining 6 within the closed body of silicon steel sheets. (V) Specific Embodiment

[0032] The high-precision non-full pipe electromagnetic flowmeter, this embodiment includes the following parts:

[0033] 1. See Figure 1 , Let there be a non - metallic pipe 1. On the central section XO of the axial length X1 of the non - metallic pipe 1, the following components are arranged: 1) See Figure 2 , On the outer surface of the wall of the non - metallic pipe 1, an upper excitation coil 2a is fixed above in the vertical direction Z, and a lower excitation coil 2b is fixed below; in the excitation magnetic circuit, there is a multi - faceted silicon steel sheet enclosure 3 surrounding the outer circumference of the non - metallic pipe. 2) See Figure 2 , On the vertical center line Zo of the non - metallic pipe 1 below, two induction electrodes 4a and 4b are fixed symmetrically left and right in the Y - direction. The circumferential angle A between the two induction electrodes is 60°. One end of each induction electrode passes through the wall hole of the pipe to contact the fluid, and the other end is connected to the electrode socket 4.1 outside the wall hole of the pipe, and is connected to the converter 11 along the surface of the non - metallic pipe by an electrode lead 4.2.

[0034] See Figure 1 , The outer shell 7 is composed of metal rings 7a and 7b at both ends of the non - metallic shaft 1 and a metal cylinder 7c at the outermost radial position, which are welded and fixed. A shielding space is formed to protect the silicon steel sheet enclosure and the upper and lower excitation coils from being damaged by sewage and pollutants.

[0035] 2. See Figure 1 , Metal pipes 9 extend outwards from both outer ends of the non - metallic pipe 1 axially and are provided with flange plates 10; used to connect to the outer flange plates 12 of the measured pipes at both external ends; the axial length between the two flange plates is X10.

[0036] 3. See Figure 2 , Close to the inner wall plate layer 5 of the non - metallic pipe 1, two groups of arc - shaped metal plate assemblies 5A and 5B are arranged symmetrically left and right in the Y - direction along the vertical center line Zo. The arc angle B of each group is 120°. See Figure 2 , Figure 4 , The inner plates of the left and right groups of arc - shaped metal plate assemblies are configured as follows: The number of plates arranged vertically along the inner wall arc is n Z = 1, and the number of plates arranged axially along the X - direction is n X = 2: Forming a left front main plate 5A1 and a left rear main plate 5A2; a right front main plate 5B1 and a right rear main plate 5B2. Beside the bottom of the inner wall of the non - metallic pipe 1, a long - shaped left auxiliary plate 5A3 and a right auxiliary plate 5B3 are added on the left and right respectively. Between the left and right front main plates 5A1, 5B1; the left and right rear main plates 5A2, 5B2, the induction electrodes 4a, 4b and the left and right auxiliary plates 5A3, 5B3 circumferentially, two maximum anti - interference left and right insulation intervals 5Amax and 5Bmax are left, which are formed by the convex strips on the inner wall of the non - metallic pipe 1.

[0037] See Figure 1 , Figure 2 The axial X - length X5 of the two groups of arc - shaped metal plate assemblies 5A and 5B in the plate layer 5 is less than the length X1 of the non - metallic pipe 1.

[0038] IV. See Figure 1 , Figure 2 , Figure 3 and Figure 5 , closely attach a cylindrical insulating lining 6 to the inner walls of two sets of arc-shaped metal plate assemblies 5A and 5B (5A and 5B are shown in Figure 2 ). See Figure 1 , Figure 3 , the axial length X6 of the cylindrical insulating lining 6 (X6 is within Figure 3 ) is basically equal to the axial length X10 between the two flange plates 10. The fluid flows axially along the inner wall of the cylindrical insulating lining 6. The cylindrical insulating lining 6 is made of insulating materials such as polytetrafluoroethylene, polyurethane, wear-resistant plastics, etc., and can provide insulation and prevent sewage corrosion.

[0039] V. See Figure 3 , install a thermometer 8 for measuring the fluid temperature along the axial center line at the bottom of the non-metallic pipe 1.

[0040] VI. See Figure 3 , fix a grounding resistor 4o at the outer center line of the bottom pipe wall of the non-metallic pipe 1.

[0041] VII. Composition and function description of the converter 11:

[0042] 1) Set the power supply: Convert the commercial power into a low-voltage DC power supply to supply power to the converter, and the converter generates an alternating power supply through the control signal to supply power to the excitation coils 2a and 2b.

[0043] 2) Set a signal processor CPU (using a single-chip microcomputer or a dedicated chip).

[0044] 3) Collect the induced electromotive force E: See Figure 2 , connect the rear ends of the induction electrodes 4a and 4b to the socket 4.1 outside the pipe wall hole, and connect them to the acquisition port of the signal processor in the converter 11 along the surface of the non-metallic pipe with a lead wire 4.2.

[0045] 4) Collect the dielectric constant on the plate: See Figure 4 , drill holes in the wall of the non-metallic pipe 1 at three positions corresponding to the left front main plate 5A1, the left rear main plate 5A2, and the left auxiliary plate 5A3, and respectively pass through the left front main pole wire 5A1n, the left rear main pole wire 5A 2n , the left auxiliary pole wire 5A 3n The front ends are electrically connected to the three left plates, and then the three plate wires are led up along the surface of the non-metallic pipe 1 and connected to the plate dielectric constant acquisition port of the signal processor in the converter 11. Similarly, see Figure 2 , Figure 4, on the right side, within a set of arc-shaped metal plate assemblies 5B, three plate connection wires, namely the right front main pole wire 5B1n, the right rear main pole wire 5B 2n , and the right auxiliary pole wire 5B 3n are connected to the plate dielectric constant acquisition ports of the signal processor.

[0046] 5) The signal processor processes the acquired signals, calculates and determines the fluid flow rate Q, which can be determined according to the aforementioned formulas <1>, <2>, and <3>. This will not be repeated here.

[0047] For the high-precision non-full pipe electromagnetic flowmeter in this embodiment, its manufacturing method is briefly described as follows: (in chronological order)

[0048] 1) See Figure 1 , make a cylindrical pipe 1 from non-metallic material, with the pipe diameter and wall thickness equal to those of the pipeline to be measured, and its length is X1. 2) Prepare two metal pipes 9 with flanges 10. Prepare the exchanger by making or purchasing. 3) See Figure 2 , Figure 4 , on the inner wall of the non-metallic pipe 1, recessed grooves corresponding to various plates are opened, and the left and right front main plates 5A1, 5B1; the left and right rear main plates 5A2, 5B2; and the left and right auxiliary plates 5A3, 5B3, a total of six plates, are embedded in the respective recessed grooves and fixed with bolts to form a plate layer 5. 4) Line and fix a cylindrical insulating lining 6 on the inner wall of the non-metallic pipe plate layer 5. 5) See Figure 2 , Figure 4 , install the following components on the outer surface of the non-metallic pipe wall: ① Fix the upper and lower excitation coils 2a, 2b. ② Drill radial holes from the surface inward to install two induction electrodes 4a, 4b and the electrode socket 4.1 and electrode leads 4.2. ③ Drill radial holes from the surface inward to install two groups of left and right front main pole leads 5A 1n , 5B 1n ; the left and right rear main pole leads 5A 2n , 5B 2n ; the left and right auxiliary pole leads 5A 3n , 5B 3n . ④ See Figure 3 , drill a radial hole from the surface of the pipeline bottom to install the thermometer 8 and the grounding electrode 4o. 6) Install the silicon steel sheet enclosure 3 tightly on the top of the upper and lower excitation coils 2a, 2b. 7) See Figure 1 , make metal rings 7a, 7b and the outermost radial metal cylinder 7c, and after welding, form the outer shell 7, which is fixed at both ends of the non-metallic shaft 1. 8) Install the converter 11 above the metal outer shell. 9) See Figure 1, Fix two metal pipes 9 with flanges 10 respectively on both end faces of the non-metal pipe 1, and lay the cylindrical insulating lining 6 in the inner holes of the two end metal pipes 9 and the flanges 10. 10) Finally, connect and fix the two flanges 10 with the gasket to the flange 12 of the pipeline to be measured. 11) Install the electromagnetic flowmeter programming software on the converter 11, and the liquid crystal display shows the flow rate and related monitoring information in the pipeline to be measured in real time.

Claims

1. High-precision non-full pipe electromagnetic flowmeter, including: a converter, characterized in that I. Provide a non-metallic pipe (1), and set on the XO section of the axial length X1 center line: 1) On the outer surface of the non-metallic pipe wall, an upper excitation coil (2a) is fixed above in the vertical direction Z, and a lower excitation coil (2b) is fixed below; a multi-sided silicon steel sheet enclosure (3) surrounding the outer circumference of the non-metallic pipe is provided in the excitation magnetic circuit; 2) Two induction electrodes (4a, 4b) are symmetrically fixed in the Y direction to the left and right below the non-metallic pipe with the vertical center line Zo, and the circumferential angle A between the two induction electrodes is 0.1 - 90°; one end of each induction electrode passes through the pipe wall hole to contact the fluid, and the other end is connected to the socket (4.1) outside the pipe wall hole and led to the converter (11) with a lead wire (4.2); an outer shell (7) for shielding is installed in the outer space of the non-metallic pipe; II. Metal pipes (9) extend out from the two outer ends of the non-metallic pipe axially and are provided with flange plates (10); used to connect with the flange plates (12) of the measured pipes at both external ends; the axial length between the two flange plates (10) is X10; III. A plate layer (5) is provided closely attached to the inner wall of the non-metallic pipe: Two groups of arc-shaped metal plate assemblies (5A, 5B) are symmetrically arranged in the Y direction along the vertical Z center line Zo, and the inner arc angle B of each group is 180° - A; the inner plates of the left and right groups of arc-shaped metal plate assemblies are configured as follows: The number of plates arranged vertically along the inner wall arc is N Z = 1, and the number of plates arranged axially along the X direction is N X = 2: Form a left front main plate (5A1) and a left rear main plate (5A2); a right front main plate (5B1) and a right rear main plate (5B2); there is an edge insulation gap (5Δ) between adjacent main plates; the axial length X5 of each group of arc-shaped metal plate assemblies is less than the length X1 of the non-metallic pipe; IV. A cylindrical insulating lining (6) is laid closely attached to the inner wall of the inner plate layer (5) of the non-metallic pipe; its length X6 is the axial length X10 between the two flange plates (10); the fluid flows axially along the inner wall of the cylindrical insulating lining; V. A thermometer (8) for measuring the fluid temperature is installed on the axial X center line at the bottom of the non-metallic pipe; VI. A grounding resistor (4o) is fixed on the axial X center line outside the pipe wall at the bottom of the non-metallic pipe; Establish a mathematical model from the known collected dielectric constant k and fluid temperature T to obtain the liquid level height H corresponding to this moment; The methods for measuring the dielectric constant are divided into the surface dielectric constant method and the space dielectric constant method. The surface dielectric constant is measured by collecting data and connecting two electrodes, namely the left front main electrode plate (5A1) and the left rear main electrode plate (5A2), or the right front main electrode plate (5B1) and the right rear main electrode plate (5B2). The space dielectric constant method is measured by collecting data and connecting the left front main electrode plate (5A1) and the right front main electrode plate (5B1), or the left rear main electrode plate (5A2) and the right rear main electrode plate (5B2).

2. The non-full pipe electromagnetic flowmeter according to claim 1, characterized in that The included angle A between the two induction electrodes is 60°; the arc included angle B of the arc-shaped metal plate assembly is 120°.

3. The non-full pipe electromagnetic flowmeter according to claim 1, characterized in that In the plate layer (5), two auxiliary plates are added on the left and right in the Y direction symmetrically with respect to the vertical center line Zo beside the tube bottom position; the main plate and the induction electrodes (4a, 4b) are in the same area, and there is a large insulation distance for anti-interference.

4. The non-full pipe electromagnetic flowmeter according to claim 1 or 3, characterized in that In the plate layer, the inner wall of the non-metal pipe in arc surface contact with the main plate or the auxiliary plate is a concave groove, and the convex strip on the inner wall of the non-metal pipe formed between adjacent plates becomes the insulation gap (5Δ).

5. The non-full pipe electromagnetic flowmeter according to claim 1, characterized in that The cylindrical insulating lining (6) is made of insulating materials such as polytetrafluoroethylene, polyurethane, and wear-resistant plastics.

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