CN105675256A - Gas-liquid two-phase flow identification system and method based on fluctuation signal in check valve - Google Patents

Abstract

The invention discloses a gas-liquid two-phase flow identification system and method based on fluctuation signals in a check valve, comprising: a pickup is directly fixed on the check valve to collect audio signals generated by the check valve; Describe the audio signal, and transmit the collected audio signal to the computer; the pressure difference sensor is connected to the check valve to measure the change of the pressure difference between the two points of the check valve, and the differential pressure signal acquisition card collects the change signal of the pressure difference , and transmit the collected signal to the computer; the computer identifies the flow state of the fluid in the pipeline according to the received audio signal and the change signal of the pressure difference; Using sound and differential pressure signals to identify the fluid flow state in the pipeline.

Description

Gas-liquid two-phase flow identification system and method based on fluctuation signal in check valve

technical field

The invention relates to the technical field of multiphase flow measurement, in particular to a gas-liquid two-phase flow identification system and method based on fluctuation signals in a check valve.

Background technique

Two-phase flow widely exists in industrial sectors such as energy, chemical industry, and metallurgy. Different flow states of fluids are of great significance to the operation mode, operation stability and product quality control in the production process. Therefore, the research on two-phase flow patterns And analysis has always been a very important and widely concerned topic. Traditional flow pattern identification methods are expensive and have harsh application conditions. Moreover, in order to obtain signals, most of them are intrusive measurements, which are not suitable for special occasions that are flammable and explosive.

Check valve, also known as one-way valve or check valve, is used to prevent the medium in the pipeline from flowing backward. Check valves are widely used in industrial production and daily life. The study found that the sound and pressure fluctuation signals generated in the check valve are closely related to the flow state of the fluid. The application of this method not only has low cost and wide application range, but also non-invasive sound signal extraction, and can be applied to special occasions such as oil and gas, which are flammable and explosive.

Contents of the invention

The purpose of the present invention is to solve the above-mentioned problems and provide a gas-liquid two-phase flow identification system and method based on the fluctuation signal in the check valve. Taking the check valve as the research object, the sound and differential pressure signals are used to analyze the fluid in the pipeline. The state of the flow can be identified, which can be applied to special occasions such as oil and gas transportation, which are flammable and explosive.

To achieve the above object, the specific scheme of the present invention is as follows:

A gas-liquid two-phase flow identification system based on fluctuating signals in a check valve, including: a pickup, a differential pressure sensor, a differential pressure signal acquisition card, an audio signal acquisition card, and a computer;

The pickup is directly fixed on the check valve to collect the audio signal generated by the check valve, the audio signal acquisition card collects the audio signal, and transmits the collected audio signal to the computer;

The differential pressure sensor is connected to the check valve to measure the change of the pressure difference between two points of the check valve, and the differential pressure signal acquisition card collects the change signal of the pressure difference, and transmits the collected signal to the computer;

The computer recognizes the flow state of the fluid in the pipeline according to the received audio signal and the change signal of the pressure difference.

A gas-liquid two-phase flow identification method based on fluctuation signals in a check valve, comprising the following steps:

(1) Set the sampling time and sampling frequency, respectively collect the audio signal on the check valve and the pressure difference change signal at two points on the check valve;

(2) Carry out empirical mode decomposition to above-mentioned two kinds of signals respectively, obtain multiple eigenmode function components of the signal;

(3) According to each eigenmode function component of the original signal, calculate the Hilbert marginal spectrum corresponding to each eigenmode function component;

(4) Calculate the energy value of each eigenmode function component and its corresponding Hilbert marginal spectrum respectively; The energy value represents the energy characteristics of different flow patterns;

(5) Calibrate the energy characteristics of different flow patterns in the coordinate map, divide the distribution areas of different flow patterns on the coordinate map, obtain the flow pattern map, and realize the identification of different flow patterns.

Further, in the step (2), the method for performing empirical mode decomposition on the signal is:

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; R</span>}$

Among them, C _i is the component of the intrinsic mode function, and R is the trend item.

Further, in the step (3), the Hilbert-Huang transformation is performed on each eigenmode function component of each signal to obtain the Hilbert Pu of each eigenmode function component, Hilbert Integrate over time to get the Hilbert marginal spectrum.

Further, in the step (4), the square of the amplitude of each eigenmode function component of the original signal is integrated over time to obtain the energy value of each eigenmode function component;

The squares of the amplitudes of the Hilbert marginal spectrum corresponding to each eigenmode function component are summed to obtain the energy value of the Hilbert marginal spectrum of the original signal.

Further, in the step (5), the method for dividing the distribution areas of different flow patterns on the coordinate map is specifically:

Measure the energy values of different flow patterns according to the actual situation, determine the distribution area of the energy values on the coordinate map, and divide the coordinate map into different flow patterns.

Beneficial effects of the present invention:

The invention collects the audio signal and the differential pressure signal respectively, analyzes and processes them, extracts the features representing different flow types in the signal, and calibrates them in the coordinate system. Taking the check valve as the research object, the identification of the fluid flow state in the pipeline is realized by using sound and pressure difference signals. This method provides an effective way for flow pattern identification. The corresponding device has the advantages of simple structure, low cost, high accuracy and the like. Moreover, the use of audio models is non-invasive measurement, which can be applied to special occasions such as oil and gas transportation, which are flammable and explosive.

Description of drawings

Figure 1 is a schematic diagram of the gas-liquid two-phase flow identification system based on the sound signal in the check valve;

Figure 2 is a schematic diagram of the gas-liquid two-phase flow identification system based on the differential pressure signal in the check valve;

Fig. 3 is the flow diagram that the present invention obtains;

Fig. 4 is a schematic diagram of energy values of different flow patterns;

Among them, 1. Check valve, 2. Pipeline, 3. Pickup, 4. Audio acquisition card, 5. Computer, 6. Differential pressure sensor, 7. Differential pressure signal acquisition card.

detailed description:

The present invention is described in detail below in conjunction with accompanying drawing:

As shown in Figure 1 and Figure 2, a gas-liquid two-phase flow identification system based on the fluctuation signal in the check valve, including: a pickup, a differential pressure sensor, a differential pressure signal acquisition card, an audio signal acquisition card and a computer;

The pickup is directly fixed on the check valve to collect the audio signal generated by the check valve. The audio signal acquisition card collects the audio signal and transmits the collected audio signal to the computer;

The differential pressure sensor is connected to the check valve to measure the change of the pressure difference between two points of the check valve, and the differential pressure signal acquisition card collects the change signal of the pressure difference, and transmits the collected signal to the computer;

The computer identifies the flow state of the fluid in the pipeline according to the received audio signal and the change signal of the pressure difference.

The gas-liquid two-phase flow identification method based on the fluctuation signal in the check valve includes the following steps:

1) As shown in Figures 1 and 2, the audio signal and differential pressure signal are obtained by installing a pickup and a differential pressure sensor on the check valve.

2) The audio signal and differential pressure signal are transmitted to the computer through the signal acquisition card.

In the computer, the above two kinds of signals S(t) are subjected to empirical mode decomposition to obtain multiple intrinsic mode function (IMF) components C ₁ ... Cn and a trend item R of the signal.

3) Do the Hilbert-Huang transform for each eigenmode function component of each signal to get its Hilbert Puru formula ②, and integrate the Hilbert Pu to get its Hilbert marginal Spectrum such as formula ③.

Among them, Re means to take the real part, a _i and ω _i represent the amplitude and frequency of the i-th eigenmode function component, and t represents time.

4) The square of the amplitude of each eigenmode function component of the original signal is integrated over time to obtain the energy value of each eigenmode function component;

Sum the squares of the Hilbert marginal spectrum amplitudes corresponding to each eigenmode function component to obtain the energy value of the original signal Hilbert marginal spectrum;

The energy values of the intrinsic mode function components and the Hilbert marginal spectrum are calculated, and the analysis can represent the energy characteristics of different flow patterns.

5) Calibrate the energy of different flow patterns in the coordinate diagram, divide the distribution areas of different flow patterns on the coordinate diagram, and obtain the flow pattern diagram.

Measure the energy values of different flow patterns according to the actual situation, see which area it is distributed in the coordinate map, and then divide the coordinate map. As shown in Figure 4, the accuracy reaches more than 90%.

During the experiment, when the fluid flows through the check valve to achieve a stable flow pattern, the pickup and the differential pressure sensor start to collect signals, and the obtained signals are transmitted to the computer through the signal acquisition card.

Set the sampling time and frequency in the computer, and sample the obtained signal. Then the empirical mode decomposition is performed on the sampled signal to obtain multiple eigenmode function components of the signal. The Hilbert marginal spectrum of the signal can be obtained by doing Hilbert-Huang transform and correlation calculation for each eigenmode function component.

Integrating the eigenmode function components and the squares of the Hilbert marginal spectral amplitudes yields their corresponding energy values. It is found that the energy of the marginal spectrum of the signal and the energy of the sixth intrinsic mode function component in this experiment can characterize the characteristics of different flow patterns. It should be noted that, in different situations, the selection of the intrinsic mode function components may be different.

Therefore, these two energy features were selected in this experiment, and different flow patterns were calibrated in the coordinate system, and the flow pattern diagram was obtained, as shown in Figure 3, which realized the identification of different flow patterns.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (6)

1. A gas-liquid two-phase flow identification system based on fluctuating signals in a check valve, characterized in that it includes: a pickup, a differential pressure sensor, a differential pressure signal acquisition card, an audio signal acquisition card and a computer; The pickup is directly fixed on the check valve to collect the audio signal generated by the check valve, the audio signal acquisition card collects the audio signal, and transmits the collected audio signal to the computer; The differential pressure sensor is connected to the check valve to measure the change of the pressure difference between two points of the check valve, and the differential pressure signal acquisition card collects the change signal of the pressure difference, and transmits the collected signal to the computer; The computer recognizes the flow state of the fluid in the pipeline according to the received audio signal and the change signal of the pressure difference. 2. A gas-liquid two-phase flow identification method based on a fluctuating signal in a check valve, characterized in that it comprises the following steps: (1) Set the sampling time and sampling frequency, respectively collect the audio signal on the check valve and the pressure difference change signal at two points on the check valve; (2) Carry out empirical mode decomposition to above-mentioned two kinds of signals respectively, obtain multiple eigenmode function components of the signal; (3) According to each eigenmode function component of the original signal, calculate the Hilbert marginal spectrum corresponding to each eigenmode function component; (4) Calculate the energy value of each eigenmode function component and the original signal Hilbert marginal spectrum respectively; The energy value represents the energy characteristics of different flow patterns; (5) Calibrate the energy characteristics of different flow patterns in the coordinate map, divide the distribution areas of different flow patterns on the coordinate map, obtain the flow pattern map, and realize the identification of different flow patterns. 3. A kind of gas-liquid two-phase flow identification method based on fluctuating signal in check valve as claimed in claim 2, it is characterized in that, in described step (2), the method for carrying out empirical mode decomposition to signal is: $\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; ;</span>$ Among them, C _i is the component of the intrinsic mode function, and R is the trend item. 4. A kind of gas-liquid two-phase flow identification method based on fluctuation signal in check valve as claimed in claim 2, it is characterized in that, in described step (3), for each intrinsic mode function of each signal The Hilbert Pu is obtained by the Hilbert-Huang transform of the components, and the Hilbert marginal spectrum of the signal is obtained by integrating the Hilbert Pu. 5. a kind of gas-liquid two-phase flow identification method based on the wave signal in the check valve as claimed in claim 2, it is characterized in that, in the described step (4), each eigenmode function component amplitude of the original signal The square of the time is integrated to obtain the energy value of each eigenmode function component; The sum of the squares of the Hilbert marginal spectrum corresponding to each eigenmode function component is obtained to obtain the energy value of the Hilbert marginal spectrum of the original signal. 6. A kind of gas-liquid two-phase flow identification method based on the fluctuation signal in the check valve as claimed in claim 2, characterized in that, in the step (5), the distribution areas of different flow patterns on the coordinate map are divided The specific method is: Measure the energy values of different flow patterns according to the actual situation, determine the distribution area of the energy values on the coordinate map, and divide the coordinate map into different flow patterns.