CN100409004C - Monofilament capacitive probe measurement system for phase holdup and phase interface in multiphase pipe flow - Google Patents

Abstract

A monofilament capacitive probe measurement system for phase holdup and phase interface in multiphase pipe flow, including a monofilament capacitive probe device and a capacitive voltage conversion circuit and signal processing device connected to the monofilament capacitive probe device, capacitive voltage conversion The circuit converts the capacitance value of the single-wire capacitance probe in the single-wire capacitance probe device into a DC voltage, and transmits the voltage value to the signal processing device, and the signal processing device controls the opening and closing of the capacitance-voltage conversion circuit and realizes Data processing, display, storage and printing functions. The invention adopts a monofilament capacitive probe, which only requires the measured phase in the multiphase pipe flow to be a conductive medium, and the measurement result is not affected by the fluid temperature and impurity components, and fundamentally eliminates the influence of the random change of the fluid electrical property on the measurement result. The continuous real-time on-line measurement of phase holdup and phase interface structure of multiphase pipe flow has been realized, and the measurement accuracy is very high.

Description

Monofilament capacitive probe measurement system for phase holdup and phase interface in multiphase pipe flow

technical field

The invention relates to a continuous real-time on-line measurement system for phase holdup and phase interface in multiphase pipe flow, in particular to a single-wire capacitance probe measurement system for phase holdup and phase interface in multiphase pipe flow.

Background technique

Gas-liquid, liquid-liquid, oil-gas-water multiphase pipe flow is widely used in energy, power and petroleum, chemical and other industrial fields. The cross-sectional phase holdup that changes in real time is one of the most basic and important characteristic parameters in multiphase pipe flow. In stratified flow, annular flow and slug flow, there is a continuous phase interface structure, which has a significant impact on the heat transfer, mass transfer and resistance characteristics of multiphase pipe flow. The real-time and accurate measurement of cross-sectional phase holdup and phase interface structure of multiphase pipe flow is one of the key technologies in experimental research, technology development and industrial application involving multiphase pipe flow.

At present, there are mainly methods for measuring phase holdup and phase interface structure of multiphase pipe flow section: quick-closing valve method, ray method, optical method, electrical method, etc. The quick-closing valve method is a mechanical method, which is only suitable for laboratory use; the accuracy of the ray method is better, but it is affected by factors such as huge equipment and radiation safety, and the optical method is affected by factors such as expensive equipment and strict requirements on the measurement object. influence, its use is subject to great constraints.

The electrical method has the characteristics of simple structure, fast and sensitive response, stable and reliable operation, and has become a hot technology in the field of multiphase flow measurement in the past 20 years. Electrical methods can be divided into conductometric and capacitive methods. A kind of instrument that is used to measure the water content in the transfusion outside the oilfield as disclosed in the Chinese patent application text "ground conductance water content analyzer" (disclosure date March 30, 2005, publication number CN1601265, application date October 26, 2004) The ground conductivity water content analyzer, the patent uses the conductivity method to measure the liquid content in the multiphase pipe flow, but the measurement result of the conductivity method changes with the change of the liquid phase conductivity, and the liquid phase temperature, the impurity composition in the liquid phase, etc. All factors significantly affect the conductivity of the liquid phase. In order to ensure the accuracy of the measurement, the measurement results must be continuously corrected, so that continuous on-line measurement cannot be realized. As disclosed in the Chinese patent application text "Adopting a Gas-Liquid Two-Flow Cavitation Fraction Measuring Instrument with a Built-in 12-pole Capacitance Sensor" (disclosure date August 17, 2005, publication number CN1654940A, application date December 29, 2004) A measuring instrument for the proportion of voids in gas-liquid two-phase flow, the patent uses the capacitance method to measure the proportion of voids in gas-liquid two-phase flow. The principle of this type of capacitance method is that the electrode pair arranged on the two-phase flow pipeline is regarded as a capacitor, and the capacitance value is related to the dielectric constant ε of the two-phase mixture, and ε is the gas phase dielectric constant ε _G , the liquid phase Function of permittivity ε _L and void fraction α. The void fraction of the mixture is obtained by measuring the capacitance value between the electrodes. However, the measurement results of this type of capacitance method also change with the change of the dielectric constant of the liquid phase, and factors such as the temperature of the liquid phase and the impurity components in the liquid phase significantly affect the dielectric constant of the liquid phase. In order to measure accurately, it must be The measurement results are constantly corrected. In experimental research or actual industrial multiphase pipe flow, the fluid conductivity and permittivity are often changing, so the current conductivity and capacitance methods cannot achieve continuous analysis of the phase holdup and phase interface structure of multiphase pipe flow. real-time online measurement.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art above, to provide a measurement result that is not affected by fluid temperature and impurity components and has high measurement accuracy, which can fundamentally eliminate the influence of random changes in fluid electrical properties on measurement results, and realize A single-wire capacitive probe measurement system for continuous real-time online measurement of phase holdup and phase interface in multiphase pipe flow.

In order to achieve the above object, the technical solution adopted in the present invention is: comprising a monofilament capacitance probe device and a capacitance voltage conversion circuit and a signal processing device connected with the monofilament capacitance probe device, it is characterized in that said monofilament capacitance The probe device includes a monofilament capacitive probe arranged in the measuring pipeline, an upper bracket and a lower bracket are arranged symmetrically on the outside of the measuring pipeline, sealing sleeves are arranged in the upper bracket and the lower bracket, and a casing and an upper end are arranged on the upper bracket. The upper end cover is connected with the upper bracket by bolts, and an electrode terminal connected with one end of the single-wire capacitance probe is also arranged on the upper end cover, and a locking bolt is arranged on the lower bracket and connected with the single-wire capacitance probe. The other end connected to the lower end cover; said capacitance voltage conversion circuit adopts CAV424 chip, and the external first, second and third tube angles of CAV424 chip are respectively connected with the reference oscillation circuit resistance Rosc, the first integrator current adjustment resistance Rcx _1. The second integrator current adjustment resistor Rcx ₂ is connected, and the reference oscillator circuit resistance Rosc, the first integrator current adjustment resistor Rcx ₁ , the second integrator current adjustment resistor Rcx ₂ and the external tenth tube angle of the CAV424 chip are grounded ; The external fourth tube angle of the CAV424 chip is connected to the output voltage amplifying resistor R _L1 , the other end of the output voltage amplifying resistor R _L1 is led to the external voltage output terminal V ₀ , and the wire is drawn from the external fourth tube angle of the CAV424 chip to connect with Another output voltage amplifying resistor R _L2 is connected, and the other end of the output voltage amplifying resistor R _L2 is connected to the sixth external tube angle of the CAV424 chip; the external sixth tube angle of the CAV424 chip is connected to the load capacitor C _VM , and the load capacitor C _VM The other end of the CAV424 chip is connected to the ground; at the same time, the sixth tube corner of the CAV424 chip is directly connected to another voltage output terminal V ₁ ; the lead wire of the eleventh tube corner of the CAV424 chip is connected to the external terminal V _cc of the DC voltage power supply; The twelfth, thirteenth, fifteenth and sixteenth tube corners are respectively connected to the oscillation circuit capacitor C _OSC , the low-pass circuit capacitor C _L2 , another low-pass circuit capacitor C _L1 and the reference capacitor C _X1 , and the other ends of these capacitors are Grounding; Lead wires from the fourteenth tube corner of the CAV424 chip to one end C ₀ of the external single-wire capacitance probe device, and at the same time lead from the ground wire to the other end C ₁ of the external single-wire capacitance probe device, from DC The external terminal V _cc of the voltage power supply is connected to a 5 volt DC power supply; the two external terminals C ₀ and C ₁ of the external monofilament capacitance probe device are respectively connected to the two ends of the monofilament capacitance probe, and the signal processing device adopts C8051F000 The single-chip microcomputer and the input terminal of the signal processing device are connected with the voltage output terminal V ₁ and the voltage output terminal V ₀ of the capacitor-voltage conversion circuit.

The monofilament capacitive probe of the present invention comprises a stainless steel wire and a polytetrafluoroethylene layer coated on the outside of the stainless steel wire; a first insulating gasket and a second insulating gasket are also arranged between the measuring pipeline, the upper bracket and the lower bracket; A spring is also arranged between the locking bolt and the lower end cover.

Since the present invention adopts the monofilament capacitive probe, only the phase to be measured in the multiphase pipe flow is required to be a conductive medium, and the measurement results are not affected by the fluid temperature and impurity components, which fundamentally eliminates the influence of random changes in the electrical properties of the fluid on the measurement results. The continuous real-time on-line measurement of phase holdup and phase interface structure of multiphase pipe flow is realized, and the measurement accuracy is very high.

Description of drawings

Fig. 1 is the overall schematic diagram of the present invention;

Fig. 2 is the assembly diagram of monofilament capacitive probe device 18 of the present invention;

Fig. 3 is the structural representation of monofilament capacitive probe 9 of the present invention;

FIG. 4 is a schematic diagram of the capacitive voltage conversion circuit 19 of the present invention;

Fig. 5 is the measuring figure of the present invention to layered interface, and wherein abscissa is the liquid level height of measureless steel, and ordinate is the measured value of the present invention;

Fig. 6 is a measurement diagram of the liquid phase holdup of bubbly flow according to the present invention, wherein the abscissa is the liquid phase holdup, and the ordinate is the measured value.

Detailed ways

The structural principle and working principle of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Referring to Fig. 1, the present invention comprises monofilament capacitive probe device 18 and the capacitive voltage conversion circuit 19 and the signal processing device 20 that are connected with monofilament capacitive probe device 18, capacitive voltage conversion circuit 19 converts monofilament capacitive probe device 18 The capacitance value of the monofilament capacitive probe in the circuit is converted into a DC voltage, and the voltage value is passed to the signal processing device 20, and the signal processing device 20 realizes the control of opening and closing of the capacitance voltage conversion circuit 19 and realizes data processing, display, functions such as storage and printing.

Referring to Fig. 2, the monofilament capacitive probe device 18 of the present invention comprises the monofilament capacitive probe 9 that is arranged in the measuring pipe 8, mills out two symmetrical conical grooves on the radially symmetrical direction of the outer wall surface of the measuring pipe 8 A cylindrical monofilament capacitance probe 9 with an outer diameter of 0.3 mm passes through two conical notches, see Fig. 3, the cylindrical monofilament capacitance probe 9 adopts a stainless steel wire 16 with a diameter of 0.1 cm in the center, and the stainless steel wire An enameled wire coated with a polytetrafluoroethylene layer 17 with a thickness of 0.1 mm, one end of the monofilament capacitance probe 9 passes through the silicone resin sealing sleeve 5, and the sealing sleeve 5 is made into a conical shape to match the conical notch, and the monofilament capacitance probe is removed. The polytetrafluoroethylene layer 17 at the end of the needle 9 is finally fixed on the electrode terminal 1, and the electrode terminal 1 is fixed on the upper end cover 3, and the upper end cover 3 is fixed on the copper upper bracket through the bolt 2 on the upper end cover 3 6, and during the downward movement of the upper end cover 3, the sleeve 4 squeezes the silicone resin sealing sleeve 5 to the conical notch on the wall of the measuring pipe 8 to play a sealing role. If the measuring pipe 8 is made of a non-conductive material, the upper bracket 6 is directly fixed on the outer wall of the measuring pipe 8 with fixing glue; if the measuring pipe 8 is made of a conductive material, an insulating gasket 7 is added between the upper bracket 6 and the outer wall of the measuring pipe 8 And fix it with glue. In the process of locking the copper lower bracket 11 through the locking bolt 13, the silicone resin sealing sleeve 12 is squeezed to seal the other end of the monofilament capacitive probe 9, and the fixing method of the lower bracket 11 and the measuring pipe 8 is the same as that of the upper bracket. 6 is the same, adjust the length of the monofilament capacitor probe 9 and fix the end of the monofilament capacitor probe 9 on the lower end cover 15, and the lower end cover 15 compresses the spring 14 arranged in the groove of the locking bolt 13, so that the monofilament capacitor The probe 9 maintains a certain tension so as to eliminate the vibration generated by the fluid flow impacting the probe. The single-wire capacitance probe 9 in the single-wire capacitance probe device 18 passes through the testing pipeline vertically along the radial direction of the pipeline, and the two ends of the probe are respectively connected with the end caps and the electrode wiring bolts. The locking bolt structure fixes the probe, and the spring is used to tension the probe to eliminate the vibration caused by the flow impact, and the silicone resin sealing sleeve is used to achieve a good seal at the position where the probe passes out of the pipeline.

Referring to Fig. 3, the monofilament capacitive probe 9 adopts the stainless steel wire 16 of diameter 0.1 centimeter in the center, and the enamelled wire of 0.1mm polytetrafluoroethylene layer 17 is coated with thickness outside the stainless steel wire, and the present invention adopts the cylindrical monolithic wire that outer diameter is 0.3mm The measurement principle of the wire capacitance probe and the single wire capacitance probe is as follows: the center of the probe is a stainless steel wire with a diameter of 0.1mm, and the stainless steel wire 16 has good strength and good conductivity, and the stainless steel wire 16 is used as a single wire One electrode of the capacitive probe 9. The stainless steel wire 16 is evenly sprayed with a polytetrafluoroethylene layer 17 with a thickness of 0.1 mm, and the annular polytetrafluoroethylene layer 17 becomes the electrolyte of the monofilament capacitive probe 9 . PTFE has stable electrical properties, and its electrical insulation and dielectric constant are not affected by ambient temperature and excitation frequency in a wide range. When the conductive fluid contacts the monofilament capacitive probe 9 , the conductive fluid constitutes another electrode of the monofilament capacitive probe 9 . At this time, the internal stainless steel wire 16, the polytetrafluoroethylene layer 17 and the conductive fluid in contact with the polytetrafluoroethylene layer 17 together form a columnar capacitor. PTFE has the smallest surface tension among solid materials, and the measured fluid will not adhere to it, so the signal response hysteresis is very weak during the measurement. When the length of the contact between the conductive fluid and the monofilament capacitance probe 9 is h at a certain place, the columnar capacitance _C1 formed at this place is:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="C"\; filenames="C20061004279200132.png,C20061004279200142.png"\; state="\{\{state\}\}">C</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&epsiv;h</span>}}{\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Where ε is the dielectric constant of polytetrafluoroethylene, D and d are the outer diameter of the single-wire capacitive probe and the diameter of the stainless steel wire at the center, respectively. When the monofilament capacitance probe 9 is placed in the multiphase pipe flow, the conductive fluid contacts it to form one or a series of parallel capacitors. According to the calculation formula of parallel capacitance, the total capacitance C on the monofilament capacitance probe is :

$\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&epsiv;</span>}}{\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&epsiv;</span>}}{\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the above formula, h _l is the total length of the conductive fluid in contact with the single-wire capacitive probe placed in the pipeline. In formula (2), ε, D, d are all definite constants, so the capacitance value detected from the monofilament capacitive probe 9 at any moment is only related to the length of the conductive fluid contacted with the monofilament capacitive probe 9 and becomes Proportional. Therefore, by detecting the capacitance of the monofilament capacitive probe 9, the phase holdup and interface structure of the pipeline interface in the multiphase pipeline flow can be obtained.

Referring to Fig. 4, capacitance-to-voltage conversion circuit 19 of the present invention adopts CAV424 chip, and this chip has the high detection sensitivity of capacitance and can overcome the influence of parasitic capacitance and environment change, realizes the detection to the capacitance value of monofilament capacitance probe 9 and changes capacitance The signal is converted to a DC voltage signal. The first, second and third tube corners of the CAV424 chip are respectively connected to the reference oscillating circuit resistance Rosc, the first integrator current adjusting resistor Rcx ₁ , and the second integrator current adjusting resistor Rcx ₂ , and the reference oscillating circuit resistance Rosc, The first integrator current adjustment resistor Rcx ₁ , the second integrator current adjustment resistor Rcx ₂ and the external tenth tube corner of the CAV424 chip are grounded; the external fourth tube corner of the CAV424 chip is connected to the output voltage amplification resistor _RL1 , and the voltage amplifies The other end of the resistor R _L1 is connected to the external voltage output terminal V ₀ , and at the same time, the wire connected to the fourth tube corner of the CAV424 chip is connected to another output voltage amplifying resistor R _L2 , and the other end of the resistor R _L2 is connected to the external fourth tube corner of the CAV424 chip. The six tube corners are connected; the external sixth tube corner of the CAV424 chip is connected to the load capacitor C _VM , and the other end of the load capacitor C _VM is grounded; at the same time, the external sixth tube corner of the CAV424 chip is directly connected to another voltage output terminal _V1 ; The lead wire of the eleventh tube corner of the CAV424 chip is connected to the external terminal V _cc of the DC voltage power supply; the twelfth, thirteenth, fifteenth and sixteenth tube corners of the CAV424 chip are respectively connected to the oscillation circuit capacitor C _OSC and the low-pass circuit Capacitor C _L2 , another low-pass circuit capacitor C _L1 and reference capacitor C _X1 are connected, and the other ends of these capacitors are all grounded; lead wires from the fourteenth tube corner of the CAV424 chip to one end of the external monofilament capacitance probe device C ₀ , lead out from the ground wire to the other end C ₁ of the external single-wire capacitance probe device, and connect a 5-volt DC power supply from the external terminal V _cc of the DC voltage power supply; The external terminals C ₀ and C ₁ are respectively connected to the two ends of the monofilament capacitance probe 9. When the pipe material is conductive, C ₁ is directly connected to the outer wall of the pipe. When the single pipe material is non-conductive, the downstream end of the monofilament capacitance probe The pipe wall at 10mm is drilled and an electrode is drawn from the pipe to connect with _C1 (the electrode is connected with the measured fluid); the output from the _V0 and _V1 external terminals is transformed by the circuit to obtain a DC voltage. When the measured liquid holdup in the test pipeline is zero, the CV circuit is zeroed by adjusting the resistors Rcx ₁ and Rcx ₂ ; the output differential voltage is adjusted by adjusting the resistors R _L1 and R _L2 , so that it is at When the monofilament capacitive probes in the pipeline are immersed in the conductive fluid, the maximum output voltage is less than the maximum range.

The signal processing device 20 takes a single-chip microcomputer as the core, and adopts a C8051F000 single-chip microcomputer. The input terminal of the signal processing device 20 is connected with the external terminals V ₁ and V ₀ of the capacitor voltage conversion circuit. The acquisition and processing frequency is 2000kH. Realize the on and off control of the capacitance-voltage (CV) conversion circuit, and realize the functions of real-time processing, display, storage and printing of data.

Before using the system, firstly when the monofilament capacitance probe device has no fluid, the extra capacitance introduced in the process of making the capacitance voltage conversion circuit 19 is zeroed to eliminate the device, and then the monofilament capacitance is measured when the monofilament capacitance probe device 18 is filled with conductive fluid. The maximum capacitance of the probe 9 is transformed into the maximum voltage, thus completing the initial setting of the measurement system. Because the measured value of the present invention is not affected by the dielectric constant of the measured fluid, there is no need to set up the measurement system or correct the measurement results during the measurement process. Holdup and phase interface structure, continuous real-time online measurement and display.

The monofilament capacitive probe measurement system provided by the invention has a simple and compact structure and low cost, and realizes real-time on-line measurement and display of the phase holdup and phase interface of the multiphase pipe flow; only the measured phase is required to have conductivity, and the measurement results are not Affected by the temperature and random changes of the electrical properties of the multiphase fluid, it has strong applicability, and continuous online measurement can be realized without correction of the measurement results during the measurement process; the detected capacitance signal has a good linear relationship with the measured physical quantity , the accuracy of the measurement results is very high; the measurement system of the present invention shows through experiments that the absolute error of the measurement of the thickness of the stratified flow interface is less than 1.0%, while the absolute error of the measurement of the cross-sectional phase holdup of the bubbly flow is less than 2.5%. It shows that the present invention can well meet the accuracy requirements of experimental research and industrial field for phase holdup and interface structure measurement in multiphase pipe flow.

Before using the measurement system, complete the initial setting of the system, and do not make any changes to the measurement system settings and measurement results during the measurement process. Figures 5 and 6 show the measurement results of the phase interface structure of water with different salinity in stratification and the phase holdup of air-bubble flow at different temperatures using the measurement system of the present invention.

Fig. 5 provides the measurement system of the present invention to the comparison of the measured value and the experimental value of the interface characteristics of three groups of water with different salinity in the case of layering, the experimental value of the dimensionless height is obtained by known liquid volume and geometric relationship out. It can be seen from the figure that the measurement result of the measurement system is less than 1% in both the absolute error and the repeatability error of the experiment compared with the experimental result.

The measurement system of the invention is used to measure the liquid phase holdup of the air-bubble flow in the vertical pipe at different temperatures, and the temperature of the water automatically heats the working medium water through the operation of the pump. Fig. 6 shows the comparison of the measurement results of the measurement system of the present invention and the experimental results, and the experimental results are given by the quick-closing valve method. It can be seen from the figure that the measurement result of the measurement system is less than 2.5% in absolute error and experimental repeatability error compared with the experimental result.

From the above two experimental results, it can be seen that the monofilament capacitive probe measurement system of the present invention can realize continuous online real-time measurement of phase holdup and phase interface in multiphase pipe flow, without the need to correct the measurement results and has a high measurement accuracy.

Claims (4)

1. the monofilament capacitance Probe Measurement System for Fluid of phase content and phase interface in the multiphase pipe flow, comprise monofilament capacitance probe device (18) and capacitance voltage change-over circuit (19) that is connected with monofilament capacitance probe device (18) and signal processing apparatus (20), it is characterized in that: said monofilament capacitance probe device (18) comprises the monofilament capacitance probe (9) that is arranged in the measuring channel (8), be symmetrically arranged with upper bracket (6) and lower carriage (11) in the outside of measuring channel (8), in upper bracket (6) and the lower carriage (11) sealing shroud (5 is set all, 12), upper bracket (6) is provided with sleeve pipe (4) and upper end cover (3), upper end cover (3) is connected with upper bracket (6) by bolt (2), and also be provided with the electrode terminal (1) that is connected with an end of monofilament capacitance probe (9) on upper end cover (2), lower carriage (11) is provided with the bottom end cover (15) that clamping screw (13) is connected with the other end with monofilament capacitance probe (9);

Said capacitance voltage change-over circuit (19) adopts the CAV424 chip, and external first, second of CAV424 chip adjusted resistance R cx with reference oscillation circuitous resistance Rosc, first integrator electric current respectively with the 3rd limb ₁, second integral device electric current adjusts resistance R cx ₂Be connected, and reference oscillation circuitous resistance Rosc, first integrator electric current adjustment resistance R cx ₁, second integral device electric current adjusts resistance R cx ₂External the tenth limb ground connection together with the CAV424 chip; External the 4th limb of CAV424 chip and output voltage amplify resistance R _L1Connect, this output voltage amplifies resistance R _L1The other end guide to external voltage output terminal V ₀, draw lead and another one output voltage amplification resistance R from external the 4th limb of CAV424 chip simultaneously _L2Connect, output voltage amplifies resistance R _L2An other end be connected with external the 6th limb of CAV424 chip; External the 6th limb and the load capacitance C of CAV424 chip _VMConnect this load capacitance C _VMAn other end ground connection; Direct and the another one voltage output end V of external the 6th limb of while CAV424 chip ₁Connect; External the 11 limb of CAV424 chip is drawn lead and dc voltage power supply external connection end V _CcConnect; External the 12,13,15 and 16 limbs of CAV424 chip respectively with the oscillatory circuit capacitor C _OSC, the low pass circuit capacitor C _L2, another low pass circuit capacitor C _L1And reference capacitance C _X1Connect the equal ground connection of an other end of these electric capacity; Draw the end C of lead from external the 14 limb of CAV424 chip to external monofilament capacitance probe device ₀, be drawn out to the other end C of external monofilament capacitance probe device simultaneously from ground wire ₁, from dc voltage power supply external connection end V _CcInsert 5 volts direct supply; Two external connection end C of order silk capacitance probe device outside ₀, C ₁Two ends with monofilament capacitance probe (9) are connected respectively,

Signal processing apparatus (20) adopts C8051F000 single-chip microcomputer, the voltage output end V of the input end of signal processing apparatus (20) and capacitance voltage change-over circuit (19) ₁With voltage output end V ₀Connect.

2. the monofilament capacitance Probe Measurement System for Fluid of phase content and phase interface in the multiphase pipe flow according to claim 1 is characterized in that: said monofilament capacitance probe (9) comprises stainless steel wire (16) and is coated in the polytetrafluoroethylene floor (17) in stainless steel wire (16) outside.

3. the monofilament capacitance Probe Measurement System for Fluid of phase content and phase interface in the multiphase pipe flow according to claim 1 is characterized in that: also be provided with first insulation spacer (7) and second insulation spacer (10) between said measuring channel (8) and upper bracket (6) and the lower carriage (11).

4. the monofilament capacitance Probe Measurement System for Fluid of phase content and phase interface in the multiphase pipe flow according to claim 1 is characterized in that: also be provided with spring (14) between said clamping screw (13) and the bottom end cover (15).

Images