CN102169101A - Conductive probe liquid holdup gauge - Google Patents

Abstract

The invention relates to a conductivity probe liquid holdup measuring instrument, which is characterized in that it includes a signal generator, a probe and a signal processor; the signal generating integrated circuit in the signal generator outputs a high-frequency sine wave signal, The amplifier amplifies its power to provide a high-frequency signal for the probe; the signal processor is connected in series in the loop composed of the signal generator and the probe, and the probe transmits the detected high-frequency AC current signal to the signal processor, which is passed through The high-speed operational amplifier in the signal processor converts the AC current signal into an AC voltage signal proportionally, and then converts the AC voltage signal into a DC voltage signal with the same value as its effective value through the AC voltage to DC effective value converter in the signal processor. , transmitted to the data acquisition card for acquisition and analysis. The invention can suppress the interference of the capacitive reactance components of the probe, and improve the stable accuracy of the liquid holdup measurement. The invention can be widely used in the gas-liquid ratio measurement application in the two-phase flow pipeline.

Description

A Conductivity Probe Liquid Holdup Measuring Instrument

technical field

The invention relates to a liquid holdup measuring device, in particular to a conductivity probe liquid holdup measuring instrument for indicating the gas-liquid ratio in a two-phase flow pipeline.

Background technique

At present, the probe method liquid holdup measurement equipment that has been used locally is mainly composed of a signal generator, a pipe section containing a probe, a signal processing circuit and then connected to a data acquisition card. All the signal generators mentioned in the literature use off-the-shelf function generators available on the market, which are expensive, large in size, and low in load capacity. It is often necessary to reduce the operating frequency to increase the impedance of the probe and reduce the load. . However, the conductivity of water determines that after the frequency decreases, the capacitive reactance component increases. At this time, forcibly treating it as pure resistance will increase the measurement error of liquid holdup. Moreover, the current signal processing circuit part also adopts traditional bridge diode rectification, filtering and other processes to obtain DC signals for data acquisition cards to collect. However, the traditional processing method has relatively strict requirements on the frequency of the signal source. The change and instability of the frequency will affect the rectifier circuit that has been debugged. The anti-interference ability to the signal source and the line is relatively poor, and the output DC signal is unstable. The disturbance is large. In addition, the low frequency is too close to the changing frequency of multiphase flow, coupled with a signal processing circuit with poor anti-interference, it is difficult to balance stable output and fast response speed with traditional filtering methods.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a conductivity probe liquid holdup measuring instrument with high measurement accuracy, which can take into account the stability of the output signal and the dynamic response speed, and has a simple structure.

To achieve the above object, the present invention adopts the following technical solutions: a conductivity probe liquid holdup measuring instrument, characterized in that: it includes a signal generator, a probe and a signal processor, the signal generator contains There is a signal generation integrator and an audio power amplifier; the signal processor contains a high-speed operational amplifier and an AC voltage to DC effective value converter; the signal generation integrated circuit in the signal generator outputs a high-frequency sine wave signal , the sine wave signal is amplified by the audio power amplifier to provide a high-frequency signal for the probe; the signal processor is connected in series in the circuit consisting of the signal generator and the probe, and the The probe transmits the detected high-frequency AC current signals at various liquid holdups to the signal processor, and the high-speed operational amplifier converts the AC current signal into an AC voltage signal proportionally, and then passes the AC voltage The DC-to-DC RMS converter converts the AC voltage signal into a DC voltage signal with the same RMS value, and then transmits it to the data acquisition card for acquisition and analysis.

The signal generating integrator in the signal generator adopts the signal generating integrator whose model is ICL8038; the audio power amplifier adopts the audio power amplifier whose model is SSM2211.

The high-speed operational amplifier in the signal processor adopts the high-speed operational amplifier model CA3140; the AC voltage-to-DC RMS converter adopts the AC voltage-to-DC RMS converter model AD536.

The probe uses conductive medium stainless steel wire as the probe.

The present invention has the following advantages due to the adoption of the above technical scheme: 1. The present invention is composed of a signal generation integrator and an audio power amplifier because the signal generator is used. After the high-frequency sine wave signal of its output is amplified by the audio power amplifier, it not only improves The load capacity of the signal generator is increased, and at the same time, the output frequency of the signal generator is increased. Therefore, the interference of the capacitive reactance component of the probe is suppressed to a greater extent, and the accuracy of the liquid holdup measurement stability is improved, so that the probe can work at higher frequencies. 2. Due to the stronger load capacity of the signal generator in the present invention, it can work at a higher signal frequency, better suppress the capacitive reactance component in the probe, have stronger anti-interference ability, and better take into account The stability and dynamic response speed of the output DC signal. 3. The present invention uses a signal processor consisting of a high-speed operational amplifier and an AC voltage-to-DC RMS converter, which simplifies the signal processor circuit and greatly enhances the applicability to different frequencies without changing any circuits. Under certain circumstances, it is possible to process different frequency signals to deal with various types of conductivity probes under different frequency conditions. 4. The present invention realizes the measurement of the gas-liquid ratio in the two-phase flow pipeline due to the use of a measuring instrument composed of a signal generator, a signal processor and a probe. It has a simple structure, greatly simplifies the signal source and signal processing circuit, and reduces the The volume of the circuit enables the miniaturization of the probe liquid holdup measuring equipment. 5. Since the present invention uses the AD536 AC voltage-to-DC RMS converter to process the output AC voltage signal, it can provide a more ideal DC voltage signal to the digital acquisition card for collection. The invention can be widely used in the gas-liquid ratio measurement application in the two-phase flow pipeline.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, the present invention comprises a signal generator 1, a probe 2 and a signal processor 3, wherein, contains a signal generation integrator 4 and an audio frequency power amplifier 5 in the signal generator 1; 3 contains a high-speed operational amplifier 6 and an RMS-DC (AC voltage to DC effective value) converter 7.

The signal generating integrated circuit 4 in the signal generator 1 outputs a high-frequency sine wave signal, which is amplified by the audio power amplifier 5 and used as the output signal source of the signal generator 1 to provide a high-frequency signal for the probe 2 Signal. In this way, the sine wave signal amplified by the audio power amplifier 5 can not only increase the load capacity of the signal generator 1 , but also increase the output frequency of the signal generator 1 . The signal processor 3 is connected in series in the circuit composed of the signal generator 1 and the probe 2, and the probe 2 transmits the detected high-frequency AC current signals under various liquid holdups to the signal processor 3, and the high-speed calculation The amplifier 6 converts the AC current signal into an AC voltage signal proportionally, and then converts the AC voltage signal into a DC voltage signal with the same effective value through the RMS-DC converter 7, and transmits the more ideal DC voltage signal to the existing technology The data acquisition card in the system is used for acquisition and analysis.

In the above embodiment, the signal generation integrator 4 in the signal generator 1 can adopt the signal generation integrator whose model is ICL8038; the audio power amplifier 5 can adopt the audio power amplifier whose model is SSM2211.

In the above-mentioned embodiments, the high-speed operational amplifier 6 in the signal processor 3 can use a high-speed operational amplifier modeled as CA3140; the RMS-DC converter 7 can use an RMS-DC converter modeled as AD536.

In the above-mentioned embodiments, the probe 2 uses a conductive medium stainless steel wire as the probe. Under the high-frequency AC signal, the capacitive reactance component of the probe 2 is basically negligible, and the probe 2 can be approximated as a pure resistance. The resistance decreases with the increase of liquid holdup, and the effective value of AC current increases with it.

The above-mentioned embodiments are only used to illustrate the present invention, and the structure, size, location and shape of each component can be changed. On the basis of the technical solution of the present invention, all improvements to individual components according to the principles of the present invention and equivalent transformations shall not be excluded from the protection scope of the present invention.

Claims (5)

1. conducting probe liquid holdup measuring instrument, it is characterized in that: it comprises a signal generator, a probe and a signal processor, described signal generator contains a signal generation integrator and an audio-frequency power amplifier; Described signal processor contains a high speed operation amplifier and an alternating voltage changes direct current effective value converter;

Signal generation integrated circuit output high_frequency sine wave signal in the described signal generator, this sine wave signal is after described audio-frequency power amplifier is with its power amplification, for described probe provides high-frequency signal; Described signal processor is connected in the loop of being made up of described signal generator and probe, high-frequency ac current signal under the various liquid holdups that described probe will detect transfers in the described signal processor, through described high speed operation amplifier the ac current signal direct proportion is converted into ac voltage signal, after described alternating voltage commentaries on classics direct current effective value converter changes into ac voltage signal the d. c. voltage signal identical with its effective value size, transfer to data collecting card and carry out collection analysis again.

2. a kind of conducting probe liquid holdup measuring instrument as claimed in claim 1 is characterized in that: it is the signal generation integrator of ICL8038 that the signal generation integrator in the described signal generator adopts model; It is the audio-frequency power amplifier of SSM2211 that described audio-frequency power amplifier adopts model.

3. a kind of conducting probe liquid holdup measuring instrument as claimed in claim 1 is characterized in that: it is the high speed operation amplifier of CA3140 that the high speed operation amplifier in the described signal processor adopts model; Described alternating voltage changes the alternating voltage commentaries on classics direct current effective value converter that direct current effective value converter employing model is AD536.

4. a kind of conducting probe liquid holdup measuring instrument as claimed in claim 2 is characterized in that: it is the high speed operation amplifier of CA3140 that the high speed operation amplifier in the described signal processor adopts model; Described alternating voltage changes the alternating voltage commentaries on classics direct current effective value converter that direct current effective value converter employing model is AD536.

5. as claim 1 or 2 or 3 or 4 described a kind of conducting probe liquid holdup measuring instruments, it is characterized in that: described probe adopts the conducting medium stainless steel wire as probe.

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