JPS63142219A - Flowmeter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to non-intrusive electromagnetic flowmeters for conductive or dielectric fluids.

[Conventional technology]

There are very few, if any, sensors that can non-intrusively determine the flow rate of a fluid with high precision under high pressure (100 MPa). Problems often arise in the field of oil extraction because the fluids are highly corrosive or abrasive.

In particular, acid flushing in oil-bearing rock formations involves pumping hydrochloric acid under pressure, often exceeding 100 MPa, through special steel diameter 5-10 c+n pipes at flow rates giving linear flow velocities in the range 0-25 m/s. The operation known as acidf'rack1ng is one example.

In other fracturing operations, the fluid pressurized by this pump is gelled diesel oil, which is relatively viscous and contains significant sand.

[Problem that the invention seeks to solve]

In such cases, it is essential to ensure that the sensor does not obstruct fluid flow. Of the various devices used to date, electromagnetic flowmeters are almost the only system that provides answers to a significant portion of the problems encountered in measuring flow in such cases. However, such flowmeters are effective only with conductive fluids, whereas most of their use is with insulating fluids.

[Means for solving problems]

The present invention provides a flowmeter that combines the advantages of electromagnetic flowmeters with a device that uses a principle called triboelectric noise cross-correlation, and combines these two systems for use under difficult conditions. Based on the method.

[For production]

When a dielectric fluid is pumped through an electromagnetic flowmeter with electrodes in contact with the fluid, a single signal is usually detected because these electrodes act as antennas sensitive to electromagnetic noise that is not dissipated by the conductivity of the fluid. Ru. In such a case, each of the element sensors of the system of the invention generates a signal. In order to screen out the signals of interest (in this case the signals from the cross-correlation device), the present invention includes an electronic device that measures conductive dust in the fluid. Signal sorting is another important feature of the invention.

〔Example〕

In FIG. 1, the electromagnetic flowmeter consists of two coils 1.2, a device for generating a magnetic field B perpendicular to the direction of flow in the conduit, and an electrode 4.5 through the conduit wall in contact with the fluid. This configuration corresponds to an electromagnetic flowmeter with an electrode of small cross-sectional area (point electrode) in contact with the fluid. An electromagnetic flowmeter equipped with an electrode (capacitive type) having a large cross-sectional area can also be expressed in the same way, and its principle is well known and will not be described here.

The flow meter shown in the figure comprises an electronic unit 6 which controls the current in the coil 1.2 as a function of time and measures the voltage across the electrodes 4.5.

The triboelectric noise cross-correlation device shown in the figure also comprises two signal detection antennas 7.8, each connected to an electronic current amplifier 9, 10 and separated by a distance a in the flow direction. .

These two units allow continuous monitoring of the detection antenna so that the signal loss between the antenna and its surroundings is zero and guarantee an amplification of approximately unity gain.

A similar cross-correlation device is shown in a French patent application of the same date as this application by the applicant, the contents of which are incorporated herein. The output of amplifier 9.10 is connected to two signals at the time taken in the fluid to cover the distance between the antennas.

A further electronic device 12 connected between the one antenna 8 and the output of the signal amplifier 10 of the other antenna determines a quantity n1 directly related to the conductive dust of the fluid.

Further electronic equipment 13 receives information from the two sensors: the signal 15 from the electromagnetic flowmeter, the signal 17 from the triboelectric noise cross-correlation flowmeter and the conductance 16 between the antennas. The unit then tests the value of this conductance and the result determines the correct flow.
Or select 17.

The electrodes of the electromagnetic flowmeter and the antenna of the cross-correlation device may be formed using well-known techniques for flexible multilayer printed circuits, such as photoetching.

FIG. 2 shows the operating principle of the antenna conductance measuring device 12. As shown in FIG.

This unit has a sinusoidal oscillator that generates a current of known frequency F, which is applied via a large resistor R to one of the antennas 8. This unit also receives the same frequency F from an amplifier 10 connected to the other antenna 7.
and a device for measuring the amplitude of the output signal.

The frequency F is chosen such that the measurement of the conductance can be carried out simultaneously with the calculation of the cross-correlation function within the device 11, and without significantly affecting the result of that calculation. In practice, F is between 5 and 20 KI (Z), the maximum value being the practical limit for detecting the component of frequency F in the output of amplifier 10.

FIG. 3 shows an electromagnetic flowmeter with electrodes 4, 5 of small cross-section in contact with the fluid and an antenna 7.8 fixed on the inner surface of the conduit 3.
FIG. 3 is a cross-sectional view of a fluid conduit 3 for a system comprising a combination of triboelectric noise cross-correlation devices.

The inside of the conduit is lined with a dielectric of uniform thickness, such as polyurethane, which insulates the antenna 7.8 from the fluid and exposes the electrodes 4, 5 coplanar with its surface. This configuration is particularly used when fluid pressures can be very high, in which case the conduit may be metal. However, it should be non-magnetic so that the magnetic field B can act on the fluid.

The metal may be aluminum or its alloys, or stainless steel, or especially if the fluid pressure is 10
If the pressure exceeds 0 MPa, titanium may be used.

In the case of very high pressures, the electrode passage and the antenna connection have a special configuration that is able to support this pressure, not shown here but as explained in the above-mentioned French patent application.

In some cases, this conduit is made of glass fiber, carbon fiber, aramid fiber, or ceramic material.
In particular, it is best to make it from a composite material mainly composed of alumina.

Figure 4 shows one application of the invention, in which the conduit is made of dielectric material, and outside it is a large cross-section square electrode 4.5 of an electromagnetic flowmeter functioning in capacitive mode and a triboelectric noise cross-correlation. The antenna of the device is attached.

The entire assembly is protected against interference from external electromagnetic fields by a grounded conductive housing.

This configuration has the advantage of being completely non-intrusive.

Furthermore, if the liquid is under very high pressure, it is sufficient to select a ceramic such as alumina or a composite material of glass, carbon or aramid fiber as the conductive material.

The part of the flowmeter that uses triboelectric noise cross-correlation will be described below.

This portion of the invention relates to non-intrusive measurements of the volumetric flow rate of dielectric fluid flowing through a tube. a) The principle often used for J determination is based on correlation techniques.

This method consists of fixing a turbulent flow structure, such as a vortex, at two points separated by a suitable distance along the tube. The time interval between fixations of the same structure opposite these points is inversely proportional to the average velocity of that structure, which is itself related to the volumetric flow rate.

Appropriate fixation methods are well known. It finds the value on the X-axis of a point corresponding to the maximum of the cross-correlation function of a signal (generally an electrical signal) by two identical main sensors placed on the tube and axially separated by a certain distance. It consists of things. Several physical principles may be used to construct these primary sensors. In all, their output signals represent flow turbulence conditions. Particular preference is given to ultrasonic, acoustic wave, optical, pressure, capacitive or resistive sensors.

Most of these sensors have the disadvantage that the measurements do not completely represent the fluid flow across the entire cross section of the tube. For example, ultrasonic sensors measure across a string, while capacitive sensors target a specific plane of symmetry. There is therefore often a need, especially in the petroleum industry, for rigid flow meters that are accurate, reliable and easy to use.

The flow meter of the present invention consists in the use of primary sensors based on the detection of electrostatic charges naturally generated by triboelectric effects in the dielectric fluid flowing in the tube and in combination of these primary sensors with techniques of signal cross-correlation. This combination meets the specific requirements of the industry in question.

FIG. 5 is a diagram illustrating the present invention. The flowmeter has a tube 1 made of a dielectric material such as polyurethane, Teflon, plexiglass, ceramic, etc.

The main sensors 2a and 2b are axially separated by a distance d and are preferably arranged in mechanical contact with the tube 1 over its entire circumference. These main sensors lie in parallel planes perpendicular to the axis of the tube 1. The main sensor is completely symmetrical, like the tube, and is sensitive to the cross section of the fluid.

The sensors 2a and 2b are connected to two electronic devices 3a, 3b, respectively, whose main purpose is to generate an electrical output signal that is identical to the input signal when the source impedance is low. The output signals of the electronic devices 3a, 3b are sent to a measurement and cross-correlation function calculation device 4.

FIG. 6 is a sectional view of one of the main sensors 2a and 2b. It consists of two antennas 2 and 5 of conductive material. The inner antenna, or detection antenna, is sensitive to electrostatic charges and becomes the detection element.

It is surrounded all around by antenna 5, which is a shielded antenna with a slightly larger diameter. The detection antenna is insulated from the shield antenna by a dielectric layer 6. The detection antenna 2 is connected to the non-inverting input of a high input impedance operational amplifier 14. The shielded antenna 5 is connected to a conductive casing 12, inside which this amplifier is located. Antennas 2a and 2b and electronic devices 3a and 3b are connected by a coaxial cable 7.

The center of this cable is connected to the detection antenna and the non-inverting input of amplifier 14. The outer conductor of this cable is connected to the shield electrode 5 and to the casing.

The output of amplifier 14 is fed back to the inverting input so that the gain is unity. The output of amplifier 14 is also connected by the outer conductor of cable 7 to casing 12 which is connected to shielded antenna 5 . This uses the principle of active shielding, and the output signal loss of the detection antenna 2 due to parasitic coupling is
This is significantly reduced because this antenna is completely surrounded by conductive surfaces at the same potential.

High resistance 13 (500MΩ or more) is the reference power supply and amplifier 1
It is connected between the non-inverting input of 4. This resistor allows polarized current from amplifier 14 to escape, thereby eliminating saturation of the amplifier.

FIG. 7 shows the structure of a sensor consisting of detection antennas 2a and 2b and shield antennas 5a and 5b.

FIG. 8 is a cross-sectional view of a portion of FIG. 7. The method of construction of this sensor is based on photoetching, which is well known in the field of printed circuits.

Flexible multilayer printed circuit technology is particularly advantageous. The thickness and/or type of dielectric layer 6 should be chosen so that the sensor has the necessary flexibility for mounting on tube 1.

According to this sensor configuration method, the detection surfaces are parallel and the distance #d
becomes constant.

FIG. 9 shows a form of the invention designed for flow measurement of pressurized fluids. The tube 8 is made of non-magnetic material, in particular titanium or stainless steel. Each antenna 2 consists of a flexible multilayer printed circuit and is placed flat inside the tube 8 and fixed with adhesive. This printed circuit has a tab 7 which constitutes the antenna output connection and avoids connecting the coaxial cable by soldering. This tab is partially filled with a hard dielectric material such as polyamide in an exit hole 10 drilled tangentially to the tube.

Hole 10 is threaded. A metal plug 11 made hollow to accommodate the tab 7 is screwed into this hole. The plug 11 is adapted to absorb the forces exerted on the tub filling machine by the high pressures (up to and above 100 MPa) that may exist in the tube.

A wear-resistant dielectric material 9 of uniform thickness lines the tube and insulates the antenna 2 from the fluid.

The dielectric material 9 should have a low Shore hardness so that pressure is transferred hydrostatically. In this example this material is polyurethane. The structure of this tube is also part of the invention.

FIG. 10 shows an example in which the antenna 2 is arranged flat against the outside of the tube 8. This tube is made of dielectric material.

In order to withstand high pressures, the tube material is based on composite materials, especially glass, carbon or aramid fibers, or ceramics, especially alumina.

〔Effect of the invention〕

FIG. 11 is an example of a calibration curve for the flowmeter of the present invention. The working fluid is l5OHVE32 oil with a dielectric constant of 2.30. The reference flow rate is from a turbine flow meter. This curve shows the maximum cross-correlation function (
The linearity indicating the average time corresponding to the horizontal axis (horizontal axis) is extremely excellent. The measurement range becomes wider than that shown in FIG. 11 when the flow velocity is higher than 15 m/s.

[Brief explanation of the drawing]

1 is a general block diagram of the present invention showing the position of the sensor and the block of the electronic unit; FIG. 2 is a diagram showing the electronic unit for measuring the conductance of a fluid; FIGS. 3 and 4 are cross-sections of the conduit; Fig. 5 shows an embodiment of the present invention, Fig. 6 shows a cross section of the main sensor, Fig. 7 shows details of the main sensor, Fig. 8 shows a cross section of the main sensor, and Fig. 9 shows an embodiment for pressurized fluid. Figure 10 is the fifth
The cross section of the figure, FIG. 11, is a calibration curve of the flowmeter of the present invention. 1.2... Coil, 4.5... Electrode, 6... Electronic unit, 7, 8... Antenna, 9.10... Current amplifier, 12.13... Electronic device, 15 ... Electromagnetic flowmeter, 16 ... Antenna, 17 ... Cross-correlation flowmeter. Applicant's representative Mr. Sato Figure 3 Figure 4 rxcmx frzw 5 Figure 9 MQIRE 10

Claims (1)

[Claims] 1. An electromagnetic flow measurement device for a conductive fluid and a triboelectric noise cross-correlation measurement device designed for measuring the flow rate of a dielectric fluid and including two antennas separated from the fluid. In combination, both of the measuring devices are connected to an electronic flow amplifier and to an electronic device that measures the conductance between the antennas, and further the fluid is detected from the signals input by the measuring devices according to the conductance value. including an electronic device that selects a signal corresponding to the flow measurement;
A flow meter for measuring the flow rate of a conductive or insulating fluid through a conduit. 2. The electronic device for measuring the conductance between the two antennas generates a frequency F between 5KHZ and 20KHZ and feeds a sinusoidal current of frequency F to one of the antennas through a high resistance element. A patent comprising a wave oscillator and a sensing device for measuring the amplitude of a current of frequency F at the output of said current amplifier connected to the other antenna, such that said current amplitude directly represents the conductance between both antennas. Flowmeter according to claim 1. 3. The flowmeter according to claim 1 or 2, wherein the electromagnetic flow rate measuring device is of a type in which the cross section of the electrode in contact with the fluid is small. 4. The conduit is a non-magnetic metal cylinder made of stainless steel, titanium, aluminum or an alloy thereof, and the antenna of the triboelectric noise cross-correlation device is flat against the inner wall of the cylinder, and the antenna is flat against the inner wall of the cylinder. 4. The flowmeter according to claim 1, wherein the flowmeter is separated from the fluid by a dielectric layer having a uniform thickness and having the same level as the covering electrode surface of the electromagnetic sensing device. 5. The flow meter according to claim 1 or 2, wherein the electromagnetic flow measuring device is a capacitive type having a large cross-sectional electrode separated from the flow rate. 6. The capacitive electrode of the electromagnetic flow measuring device and the antenna of the triboelectric noise cross-correlation device are assembled flat against the outside of the conduit made of a dielectric material, as claimed in claims 1 and 2. Flowmeter according to paragraph 5 or paragraph 5. 7. A flowmeter according to claim 6, wherein the conduit is made of a composite material containing fibers, the fibers being of glass, carbon or aramid. 8. The flowmeter of claim 6, wherein said conduit is made of alumina. 9. The flowmeter according to any one of claims 5 to 8, wherein the capacitive electrode and the antenna are formed on a single flexible multilayer printed circuit. 10. Two antennas of identical geometric dimensions (2
a) and (2b), wherein the position of one of the antennas differs from the other by a non-zero distance in a direction parallel to the average fluid flow occurring in the vicinity of both antennas, and both Each of the antennas is equipped with charge amplification electronics (3a
) (3b), and the output signals of both said amplifying electronics are connected to an electronic device (4) which correlates them with each other and generates an output signal giving the flow rate. Flowmeter. 11. Each of the antennas consists of two conductors (2) and (5) insulated from each other by a dielectric 6, and the first conductor (2) (detection antenna) of these conductors faces the fluid. a second conductor (5) (shielded antenna) surrounds said first conductor so as not to come between it and the fluid, and each double antenna is connected to a coaxial connector (7).
) to the amplifying electronics, the center conductor of this coaxial connector is connected to the detection antenna, and the outer conductor of the connector is connected to the shield antenna (5) and the conductive housing (12) of the casing of the electronics. 11. The flow meter according to claim 10, wherein the flow meter is connected.