A system and method for measuring pipeline flow based on scattered light

Abstract

The present invention provides a system and method for measuring pipeline flow based on scattered light, the system comprising a laser emitting mechanism, a transparent organic glass tube and a signal detection mechanism; the signal detection mechanism comprises a probe, a bracket for supporting the probe, a photometer and a computer; the central axes of the probe, the laser emitting mechanism and the transparent organic glass tube are all located in the same plane. The present invention completes the measurement of gas-liquid two-phase flow in a pipeline by measuring scattered light for the first time, and can provide auxiliary comparison and reference for near-infrared transmitted light measurement methods by studying the attenuation characteristics of scattered light, further promoting the development of near-infrared spectroscopy technology. The present invention provides a phase content auxiliary measurement system, which can combine scattered light and transmitted light for measurement, measure gas-liquid two-phase flow from different angles, and greatly improve the reliability of measurement.

Description

Technical Field

[0001] The invention relates to the technical field of gas-liquid two-phase flow detection, and in particular to a system and method for measuring pipeline flow based on scattered light. Background Art

[0002] There are many methods for measuring the phase content of gas-liquid two-phase flow. The first is to use the most common circular tube and place the probe radially for measurement; the second is to change the original radial placement of the probe on the horizontal circular pipe to measure along the fluid flow direction; the third is to change the horizontal circular pipe into a vertical square pipe so that the probe measures along the fluid flow direction; the fourth is to use multiple sets of transmitting probes and receiving probes to form a unified whole, and use near-infrared transceiver probes to detect the gas-liquid two-phase flow in the horizontal and vertical directions, so as to achieve more accurate measurement. The above structural designs all use near-infrared light measurement, and all measurements are transmitted light. Near-infrared laser measurement technology does not require sampling and sample pretreatment, and has the characteristics of non-contact and real-time online monitoring. It has been initially explored in the field of gas-liquid two-phase flow detection. However, it was found in the study that due to the complex and changeable interface of the gas-liquid two-phase flow medium and the invisibility of near-infrared light to the naked eye, the challenge of near-infrared detection of gas-liquid two-phase flow is further enhanced.

[0003] In order to reduce the uncertainty of near-infrared light and improve the accuracy of phase content measurement, the present invention designs a system and method for measuring pipeline flow based on scattered light to improve the accuracy of phase content measurement. Summary of the invention

[0004] The purpose of the present invention is to provide a system and method for measuring pipeline flow based on scattered light, so as to solve the problem of inaccurate measurement of various laser attenuation in the process of measuring gas-liquid two-phase flow in the existing system.

[0005] The technical solution adopted by the present invention is: a system for measuring pipeline flow based on scattered light, the system comprising a laser emitting mechanism, a transparent organic glass tube and a signal detection mechanism; the laser emitting mechanism comprises a laser and a filter, the laser is used to generate emission light with a wavelength range of 400 to 2400nm, and the emission light outputs monochromatic light of any wavelength band within 400 to 2400nm after passing through the filter;

[0006] The signal detection mechanism includes a probe, a bracket for supporting the probe, a photometer and a computer; the probe, the laser emitting mechanism and the central axis of the transparent organic glass tube are all located in the same plane, the monochromatic light emitted by the laser emitting mechanism is incident into the tube perpendicular to the central axis of the transparent organic glass tube, the monochromatic light is absorbed by the gas-liquid two-phase fluid in the tube and then emitted from the transparent organic glass tube, and scattered light is generated around the transparent organic glass tube at the same time; the probe is used to receive the scattered light and transmit the scattered light signal to the photometer, and the computer is used to process and analyze the signal transmitted by the photometer.

[0007] The probe and the laser emitting mechanism are located on the same side of the transparent organic glass tube, and the probe is located on a straight line which forms an angle of 45 degrees or 315 degrees with the incident direction of the monochromatic light.

[0008] The probe and the laser emitting mechanism are located on both sides of the transparent organic glass tube, and the probe is located on a straight line which forms an angle of 135 degrees or 225 degrees with the incident direction of the monochromatic light.

[0009] The laser is a SC400-4 supercontinuum laser, and the filter is a LLTF filter.

[0010] The photometer is a S470 UDT desktop photometer, and the probe is a 247 flat-panel radiation sensor probe.

[0011] The bracket is used to adjust the spatial position of the probe, and the transparent organic glass tube is a circular tube.

[0012] A method for measuring pipeline flow based on scattered light comprises the following steps:

[0013] (a) installing any of the above systems;

[0014] (b) generating a gas-liquid two-phase flow and allowing the fluid to flow in a transparent plexiglass tube;

[0015] (c) Turn on the laser so that the emitted monochromatic light enters the plexiglass tube vertically;

[0016] (d) Use a probe and photometer to detect scattered light around the plexiglass tube, and then use a computer to process and analyze the data.

[0017] The probe and the laser emitting mechanism are located on the same side of the transparent organic glass tube, and the probe is located on a straight line that forms an angle of 45 degrees or 315 degrees with the incident direction of the monochromatic light; or

[0018] The probe and the laser emitting mechanism are located on both sides of the transparent organic glass tube, and the probe is located on a straight line which forms an angle of 135 degrees or 225 degrees with the incident direction of the monochromatic light.

[0019] The beneficial effects and advantages of the present invention are: 1. For the first time, the measurement of the gas-liquid two-phase flow in the pipeline is completed by measuring the scattered light. By studying the attenuation characteristics of the scattered light, it can provide auxiliary comparison and reference for the near-infrared transmitted light measurement method, further promoting the development of near-infrared spectroscopy technology. 2. The present invention provides a phase content auxiliary measurement system, which can combine the scattered light and the transmitted light for measurement, measure the gas-liquid two-phase flow from different angles, and greatly improve the reliability of the measurement. 3. The device of the present invention has a simple structure, and the measuring pipeline does not have too much redundant design. The complex design of the measuring pipeline will not affect the measurement results, and real-time online detection can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The structure diagram of the system of the present invention includes: 1. laser, 2. filter, 3. probe, 4. photometer, 5. computer, 6. organic glass tube, 7. air pump, 8. water pump, and 9. frequency converter.

[0021] Figure 2 This is the measurement diagram of the probe position in the positive direction.

[0022] Figure 3 This is the measurement diagram of the probe position in the reverse direction.

[0023] Figure 4 It is the transmission power data and curve fitting diagram.

[0024] Figure 5 This is a comparison chart of laser scattering and refraction in various directions in the forward direction.

[0025] Figure 6 This is a comparison chart of laser backscattering and refraction in various directions. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with examples. The following examples are only for illustration and are not intended to limit the present invention in any way.

[0027] like Figure 1 As shown, the system of the present invention includes a laser emitting mechanism, a circular transparent organic glass tube and a signal detection mechanism; the laser emitting mechanism includes a laser 1 and a filter 2, the laser 1 is an SC400-4 supercontinuum laser, which is used to generate emission light with a wavelength range of 400 to 2400nm, and the filter 2 is an LLTF filter, which outputs monochromatic light of any wavelength band within 400 to 2400nm after the emission light passes through the filter.

[0028] The signal detection mechanism includes a probe 3, a bracket for supporting the probe 3, a photometer 4 and a computer 5; the photometer 4 is a UDT desktop photometer of GAMMA SCIENTIFIC (Gamma Science) S470 type, and the probe 3 is a 247 type flat-panel radiation sensor probe. The bracket is used to adjust the spatial position of the probe. The S470 type optical instrument is suitable for photometric measurement, radiation measurement, laser power and fiber optic measurement. The 247 type radiation sensor probe includes a precision radiation measurement filter for flat response from blue to near infrared. The sensor probe has high linearity and low noise performance. The probe 3, the laser emitting mechanism and the central axis of the transparent organic glass tube 6 are all located in the same plane. The monochromatic light emitted by the laser emitting mechanism is perpendicular to the central axis of the transparent organic glass tube 6 and is incident on the tube. The monochromatic light is absorbed by the gas-liquid two-phase fluid in the tube and then emitted from the transparent organic glass tube, and scattered light is generated around the transparent organic glass tube; the probe 3 is used to receive the scattered light and transmit the scattered light signal to the photometer, and the computer is used to process and analyze the signal transmitted by the photometer.

[0029] The probe and the laser emitting mechanism are located on the same side of the transparent organic glass tube, and the probe is located on a straight line with an angle of 45 degrees or 315 degrees to the incident direction of the monochromatic light. Alternatively, the probe and the laser emitting mechanism are located on both sides of the transparent organic glass tube, and the probe is located on a straight line with an angle of 135 degrees or 225 degrees to the incident direction of the monochromatic light.

[0030] A method for measuring pipeline flow based on scattered light comprises the following steps:

[0031] (a) installing any of the above systems;

[0032] (b) generating a gas-liquid two-phase flow and allowing the fluid to flow in a transparent plexiglass tube;

[0033] (c) Turn on the laser so that the emitted monochromatic light enters the plexiglass tube vertically;

[0034] (d) Use a probe and photometer to detect scattered light around the plexiglass tube, and then use a computer to process and analyze the data.

[0035] The probe and the laser emitting mechanism are located on the same side of the transparent organic glass tube, and the probe is located on a straight line that forms an angle of 45 degrees or 315 degrees with the incident direction of the monochromatic light; or the probe and the laser emitting mechanism are located on both sides of the transparent organic glass tube, and the probe is located on a straight line that forms an angle of 135 degrees or 225 degrees with the incident direction of the monochromatic light. Figure 2 and Figure 3As shown in the figure, when measuring the scattered refracted laser, the scattered laser power is detected from the directions of 45 degrees, 135 degrees, 225 degrees, and 315 degrees clockwise from the incident laser. The laser emission position and the detector detection position are on the same plane, and the plane passes through the center of the pipe cross section. After the measurement, the laser is replaced to detect the gas-liquid two-phase annular flow from the other side. This design can detect the light scattered when the visible laser enters and passes through the gas-liquid two-phase flow interface from different angles.

[0036] Detection Examples

[0037] like Figure 1 As shown, during the test, the organic glass tube is connected to the pipeline, and the pipeline is provided with two branches, one branch is connected to the air pump 7, and the other branch is connected to the water pump 8. The air pump and the water pump are both equipped with a frequency converter 9, and the rotation speed can be controlled by the computer 5 to adjust the content of the gas and liquid entering the organic glass tube. The SC400-4 supercontinuum laser is set to a visible green laser with a wavelength of 532nm, and the gas-liquid two-phase flow with different phase contents is measured.

[0038] When measuring the power of the laser-transmitted gas-liquid two-phase flow, measure the gas-liquid two-phase flow with a determined phase content for one minute, take 60 data, and take the average value. Take this average value as the power of the laser-transmitted gas-liquid two-phase flow with this phase content, and draw a graph based on the measured power and the volume gas content of the gas-liquid two-phase flow. Observe the relationship between the power and the volume gas content of the gas-liquid two-phase flow. Figure 4 As shown, the horizontal axis is the volume gas content in the gas-liquid two-phase flow, and the vertical axis is the transmitted laser power. It can be seen from the figure that the higher the volume gas content in the gas-liquid two-phase annular flow, the higher the power obtained by transmission, and the smaller the attenuation of the annular flow to the laser. The power obtained by the probe is positively correlated with the volume gas content. When the water content in the gas-liquid two-phase flow is higher, the attenuation of the laser is greater. Take 10 groups of data and use origin for fitting. The fitting equation is expressed as a quadratic equation as y=111142.39538x 2 -20564.65617x+9525.3445. Fitting coefficient R 2 =0.91517.

[0039] The scattered and refracted laser power in each direction is negatively correlated with the volumetric gas content; that is, the volumetric liquid content is positively correlated with the scattered and refracted laser power. By observing the measured data, it is found that the scattered and refracted laser power in each direction is different, so the power in each direction is combined for comparison. Figure 5It can be seen that when the laser is detecting the gas-liquid two-phase annular flow in the positive direction, the laser energy scattered and refracted in the direction 2 (135°) and direction 3 (225°) on the same plane is much greater than the laser energy scattered and refracted in the direction 1 (45°) and direction 4 (315°). Compared with the energy of laser scattering and refracting in the direction 3 (225°) and direction 2 (135°), the energy of laser scattering and refracting in the direction 3 (225°) is greater than that in the direction 2 (135°). Figure 6 It can be seen that when the laser detects the gas-liquid two-phase annular flow in the opposite direction, the laser energy scattered and refracted in direction 2 (135°) and direction 3 (225°) is much greater than the laser energy scattered and refracted in direction 1 (45°) and direction 4 (315°). Compared with the energy of laser scattering and refracting in direction 3 (225°) and direction 2 (135°), the energy of laser scattering and refracting in direction 2 (135°) is greater than the energy of laser scattering and refracting in direction 3 (225°). Therefore, it can be seen that on the same plane, the energy of laser scattering and refracting by entering the gas-liquid two-phase flow interface is less than the energy of laser scattering and refracting by passing through the gas-liquid two-phase flow interface, the energy scattered and refracted on one side of the laser is less than the energy scattered and refracted on one side of the probe, and on the other side, the energy of laser scattering and refracting in the direction of the gas-liquid two-phase flow is greater than the energy of laser scattering and refracting in the direction of the gas-liquid two-phase flow outflow.

Claims

1. A method for measuring pipeline flow based on scattered light, characterized in that: The following steps are involved: (a) A system for measuring pipeline flow based on scattered light is provided as follows; The system comprises a laser emitting mechanism, a transparent organic glass tube and a signal detection mechanism; the laser emitting mechanism comprises a laser and a filter, the laser is used to generate emission light with a wavelength range of 400 to 2400 nm, and the emission light outputs monochromatic light of any wavelength band within 400 to 2400 nm after passing through the filter; The signal detection mechanism includes a probe, a bracket for supporting the probe, a photometer and a computer; the probe, the laser emitting mechanism and the central axis of the transparent organic glass tube are all located in the same plane, the monochromatic light emitted by the laser emitting mechanism is incident into the tube perpendicular to the central axis of the transparent organic glass tube, the monochromatic light is absorbed by the gas-liquid two-phase fluid in the tube and then emitted from the transparent organic glass tube, and scattered light is generated around the transparent organic glass tube; the probe is used to receive the scattered light and transmit the scattered light signal to the photometer, and the computer is used to process and analyze the signal transmitted by the photometer; (b) generating a gas-liquid two-phase annular flow and allowing the fluid to flow in a transparent plexiglass tube; (c) Turn on the laser so that the emitted monochromatic light enters the plexiglass tube vertically; (d) Use a probe and a photometer to detect scattered light around the plexiglass tube, and then use a computer to process and analyze the data; When measuring scattered refracted laser, the scattered laser power is detected from the directions of 45 degrees, 135 degrees, 225 degrees, and 315 degrees clockwise to the incident laser. The laser emission position and the probe detection position are on the same plane, and the plane passes through the center of the circle of the pipe cross section. After the measurement, the laser is replaced to detect the gas-liquid two-phase annular flow from the other side. The computer is used to process and analyze the data and the results show that the scattered refracted laser power in each direction is negatively correlated with the volume gas content.

2. The method for measuring pipeline flow based on scattered light according to claim 1 is characterized in that: The probe and the laser emitting mechanism are located on the same side of the transparent organic glass tube, and the probe is located on a straight line that forms an angle of 45 degrees or 315 degrees with the incident direction of the monochromatic light; or The probe and the laser emitting mechanism are located on both sides of the transparent organic glass tube, and the probe is located on a straight line which forms an angle of 135 degrees or 225 degrees with the incident direction of the monochromatic light.

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