A pipeline medium monitoring system and a method for monitoring concentration of a pipeline medium

Abstract

The embodiment of the application provides a pipeline medium monitoring system and a pipeline medium concentration monitoring method, and belongs to the technical field of pipeline transportation, which is used for realizing the identification of the concentration of one kind of medium when a conveying pipeline conveys multiple media. The system comprises: a transparent pipe section used for allowing laser to penetrate and excite the medium in the pipe; a laser sheet light excitation unit used for emitting sheet laser and shooting into the transparent pipe section, so that a first fluorescent indicator previously added in the first medium generates a first fluorescent signal; a conveying pipeline used for sequentially conveying the first medium and the second medium; a first fluorescent detection unit used for capturing the first fluorescent signal and converting the first fluorescent signal into a digital image signal; a data acquisition and analysis unit used for determining the fluorescent intensity in the transparent pipe section based on the digital image signal; determining the corresponding first medium concentration based on the fluorescent intensity, identifying the start and end positions of a tailing area formed by the first medium in the conveying process, and calculating the tailing length.

Description

Technical Field

[0001] This application relates to the field of pipeline transportation technology, and in particular to a pipeline medium monitoring system and a method for monitoring the concentration of pipeline media. Background Technology

[0002] In the field of long-distance pipelines, multiple media (such as gasoline or diesel of different grades) are often transported sequentially through the same pipeline. During sequential transportation, the two media mix at the interface due to factors such as molecular diffusion and flow field disturbance, forming a continuous mixing section. As the transportation distance increases, the degree of mixing intensifies, and the length of the mixing section continues to grow. Especially in the tail region of the mixing section, a mixing tail region appears where the concentration of the first medium gradually transitions from high to zero. Accurately identifying the start and end positions of this tail region and calculating its length is of great significance for reducing oil blending losses and optimizing cutting schemes. Summary of the Invention

[0003] This application provides a pipeline medium monitoring system and a method for monitoring pipeline medium concentration, which can improve the accuracy of identifying the tail position and length of the mixing section formed during transportation.

[0004] In a first aspect, embodiments of this application provide a pipeline medium monitoring system, comprising: a transparent pipe section, a laser sheet excitation unit, a fluorescence detection unit, and a data acquisition and analysis unit. The transparent pipe section is installed on a conveying pipeline for laser penetration to excite the medium within the pipe; the laser sheet excitation unit emits a sheet-like laser beam shaped by beam shaping and directs it into the transparent pipe section to excite a first fluorescent indicator pre-added to a first medium to generate a first fluorescence signal; the conveying pipeline sequentially conveys the first medium and a second medium; the first fluorescence detection unit captures the first fluorescence signal and converts it into a digital image signal; the data acquisition and analysis unit determines the fluorescence intensity within the transparent pipe section based on the digital image signal; determines the corresponding first medium concentration based on the fluorescence intensity; identifies the start and end positions of the tail region formed by the first medium during conveyance according to a preset concentration threshold; and calculates the tail length.

[0005] The pipeline medium monitoring system provided in this application involves installing a transparent pipe section on the pipeline and pre-adding a first fluorescent indicator with good chemical stability, anti-interference properties, and safety to the first medium. A laser sheet excitation unit emits a sheet-like laser, shaped by beam shaping, into the transparent pipe section to generate a first fluorescent signal. This signal is captured by a first fluorescence detection unit and converted into a digital image signal. A data acquisition and analysis unit then determines the fluorescence intensity and inverts the concentration of the first medium based on the digital image signal. Furthermore, it identifies the start and end positions of the trailing region and calculates the trailing length according to a preset concentration threshold. As can be seen, the solution provided in this application employs a non-invasive optical detection method, enabling high-precision identification and quantitative analysis of the trailing region formed by the slight density difference between the first and second media without contact with the medium. This accurately obtains the trailing boundary and length, providing reliable data support for reducing oil blending losses and optimizing cutting schemes. Simultaneously, it avoids the adverse effects of introducing foreign substances on the chemical stability of the medium and its subsequent use. Moreover, the transparent pipe section has a simple structure, eliminating the need for complex seals and high-pressure customized sensors, effectively reducing equipment costs and maintenance difficulty.

[0006] In one possible implementation, the transparent pipe section of the pipeline medium monitoring system is made of plexiglass, with a black anti-light and anti-scratch protective layer covering its outer non-optical surface, and a light-shielding sealing ring is provided at the flange connection.

[0007] In one possible implementation, the pipeline medium monitoring system further includes a second fluorescence detection unit for capturing the second fluorescence signal generated after the second fluorescent substance is excited; the data acquisition and analysis unit is specifically used to: calculate the intensity ratio of the first fluorescence signal to the second fluorescence signal, and determine the concentration of the first medium based on the intensity ratio; wherein the second fluorescent substance is added to the first medium, and the emission spectrum of the first fluorescent substance and the absorption spectrum of the second fluorescent substance at least partially overlap.

[0008] In one possible implementation, the laser sheet excitation unit and the first fluorescence detection unit in the pipeline medium monitoring system are arranged in a horizontal excitation-vertical reception optical path layout.

[0009] In one possible implementation, the data acquisition and analysis unit in the pipeline medium monitoring system is specifically used to: determine the concentration of the first medium corresponding to the fluorescence intensity based on a pre-established calibration curve between fluorescence intensity and the concentration of the first medium.

[0010] In one possible implementation, the first medium in the pipeline medium monitoring system is methanol; the fluorescent indicator is disodium fluorescein, the effective excitation wavelength of which is 465-490 nm, and the concentration added to the first medium is 3-5 mg / L.

[0011] In one possible implementation, the pipeline medium monitoring system further includes a temperature compensation patch installed on the outside of the transparent pipe section for monitoring the pipe wall temperature; the data acquisition and analysis unit is also used to determine the light intensity correction coefficient corresponding to the pipe wall temperature based on the pre-calibrated temperature-light intensity correction coefficient, and to correct the first fluorescence intensity inside the transparent pipe section based on the light intensity correction coefficient.

[0012] In one possible implementation, the preset concentration thresholds in the pipeline medium monitoring system include a first concentration threshold and a second concentration threshold, wherein the first concentration threshold is greater than the second concentration threshold; the first concentration threshold is used to determine the starting position of the trailing region, and the second concentration threshold is used to determine the ending position of the trailing region.

[0013] Secondly, embodiments of this application provide a method for monitoring the concentration of a pipeline medium, comprising: determining the fluorescence intensity within a transparent pipe section based on a digital image signal detected by a first fluorescence detection unit; determining the corresponding concentration of a first medium based on the fluorescence intensity; identifying the start and end positions of a trailing region formed by the first medium during transportation according to a preset concentration threshold; and calculating the length of the trailing region.

[0014] In one possible implementation, in conjunction with the second aspect of the implementation method, the pipeline medium monitoring system further includes: a second fluorescence detection unit for capturing the second fluorescence signal generated after the second fluorescent substance is excited; determining the corresponding first medium concentration based on the fluorescence intensity, including: calculating the intensity ratio of the first fluorescence signal to the second fluorescence signal, and determining the first medium concentration according to the intensity ratio; wherein, the second fluorescent substance is added to the first medium, and the emission spectrum of the first fluorescent substance and the absorption spectrum of the second fluorescent substance at least partially overlap.

[0015] The beneficial effects described in the second aspect can be referred to the analysis of the beneficial effects in the first aspect, and will not be repeated here. Attached Figure Description

[0016] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0017] Figure 1 A schematic diagram of a pipeline medium monitoring system provided as an example of this application; Figure 2 A schematic diagram of the cross-sectional optical path layout of a pipeline medium monitoring system provided in this application example; Figure 3 A flowchart of a pipeline medium monitoring system provided as an example of this application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that in the embodiments of this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design scheme described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0020] To facilitate a clear description of the technical solutions of the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish the same or similar items with essentially the same function and effect. Those skilled in the art can understand that the terms "first" and "second" are not intended to limit the quantity or execution order.

[0021] In the sequential transport mode of long-distance pipelines, when the first and second media are transported alternately, mixing inevitably occurs at their interface due to molecular diffusion and turbulent disturbances, forming a continuous mixing section. The longer the transport distance, the more severe the mixing and the longer the mixing section. It is particularly noteworthy that a trailing region is formed at the end of the mixing section, where the concentration of the first media gradually decreases from high to zero.

[0022] Currently, conventional detection methods struggle to identify minute density differences between the first and second media, resulting in low measurement accuracy and an inability to accurately capture the concentration distribution and boundaries of the tailing region. Furthermore, to meet the pressure requirements of oil transportation, customized high-pressure resistant sensors are often required, significantly increasing equipment costs and complicating installation and maintenance, leading to poor overall economic efficiency. In addition, some detection technologies, such as chemical methods, may introduce foreign substances, affecting the chemical stability of the medium and consequently adversely impacting the subsequent use of the oil.

[0023] Based on this, embodiments of this application provide a pipeline medium monitoring system, including: a transparent pipe section, a laser sheet excitation unit, a fluorescence detection unit, and a data acquisition and analysis unit. By installing a transparent pipe section on the transport pipeline and pre-adding a first fluorescent indicator with good chemical stability, anti-interference, and safety to a first medium, the laser sheet excitation unit emits a sheet-like laser, shaped by beam shaping, into the transparent pipe section to excite and generate a first fluorescence signal. The first fluorescence detection unit captures this signal and converts it into a digital image signal. The data acquisition and analysis unit then determines the fluorescence intensity and inverts the concentration of the first medium based on the digital image signal, and identifies the start and end positions of the trailing region and calculates the trailing length according to a preset concentration threshold.

[0024] As can be seen, the solution provided in this application adopts a non-invasive optical detection method, which can achieve high-precision identification and quantitative analysis of the trailing area formed by the slight density difference between the first and second media without contact with the medium. This allows for accurate acquisition of the trailing boundary and length, providing reliable data support for reducing oil blending losses and optimizing cutting schemes. At the same time, it avoids the adverse effects of introducing foreign substances on the chemical stability of the medium and its subsequent use. Furthermore, the transparent pipe section has a simple structure and does not require complex sealing or high-pressure customized sensors, effectively reducing equipment costs and maintenance difficulty.

[0025] The pipeline medium monitoring system provided in the embodiments of this application is described below with reference to the accompanying drawings.

[0026] Please see Figure 1 , Figure 1 This application provides a pipeline medium monitoring system as an embodiment. For example... Figure 1 As shown, the pipeline medium monitoring system 100 includes: a transparent pipe section 11, a laser sheet light excitation unit 12, a fluorescence detection unit 13, and a data acquisition and analysis unit 14.

[0027] In the embodiments of this application, such as Figure 1 As shown, the transparent pipe section 11 is installed on the conveying pipeline, which is used to sequentially convey the first medium and the second medium. The first medium and the second medium are two different liquid media that are sequentially conveyed in the field of long-distance pipelines. They differ in physicochemical properties. During the sequential conveying process, they mix at the contact interface due to factors such as molecular diffusion and flow field disturbance, forming a mixing section. In particular, a tailing region appears at the end of the mixing section where the concentration of the first medium gradually transitions from high to zero.

[0028] In this embodiment, the medium refers to a fluid substance transported through a pipeline. Its form can be liquid, gas, or a gas-liquid mixture, and its composition can be a single component or a mixture of multiple components. In a sequential transport scenario, the first medium and the second medium represent two different types of media transported alternately.

[0029] As a feasible implementation method, the pipeline is a sequential transport pipeline for refined oil and methanol, with methanol as the first medium and refined oil as the second medium, including but not limited to gasoline and diesel. During the sequential transport of methanol and refined oil, due to factors such as molecular diffusion and flow field disturbance, a continuous mixed oil section will form at the interface between the two, and a low-concentration methanol tail oil will appear at the end of the mixed oil section. Accurately identifying the start and end positions of this tailing region and calculating the tail length is of great significance for reducing oil blending losses and optimizing the cutting scheme.

[0030] In this embodiment, a fluorescent indicator is added to the first medium, while the second medium contains little or no concentration of the indicator. The fluorescent indicator possesses good chemical stability, anti-interference properties, and safety; it is completely miscible with the first medium and almost insoluble or has extremely low solubility in the second medium, and it has no adverse effect on the subsequent transportation and use of the medium. Based on this addition method, when the sheet laser emitted by the laser sheet excitation unit 12 enters the transparent tube segment 11, only the fluorescent indicator in the first medium is excited to generate a fluorescent signal, while the second medium produces almost no or only a very weak fluorescent signal. Thus, the concentration of the first medium is detected by the intensity of the fluorescent signal.

[0031] It should be understood that this application does not limit the composition of the first medium and the fluorescent indicator. As one feasible implementation, the laser wavelength is matched with the excitation wavelength of the fluorescent indicator to maximize the absorption cross-section of the fluorescent indicator, achieving wavelength-selective excitation, maximizing excitation efficiency, reducing stray light interference, and improving the fluorescence signal intensity. Matching the concentration range with the laser excitation efficiency enables precise positioning of the trailing boundary. As one feasible implementation, the first medium is methanol; the fluorescent indicator is disodium fluorescein, with an effective excitation wavelength of 465-490 nm, and an addition concentration of 3-5 mg / L in the first medium.

[0032] The effective excitation wavelength range of disodium fluorescein is 465-490 nm, the addition concentration range is 3-5 mg / L, and the applicable temperature range is 15-35 °C. During use, care should be taken to avoid temperatures exceeding 60 °C to prevent the fluorescent agent from becoming ineffective. This fluorescent indicator is completely miscible with methanol and almost insoluble in refined oil, meeting the monitoring needs of tailing oil in methanol-refined oil sequential transportation scenarios.

[0033] In this embodiment, the transparent pipe section 11 serves as an optical detection window, installed on the conveying pipeline to allow the laser to penetrate and excite the medium inside the pipe. It possesses excellent light transmittance and pressure-bearing capacity, ensuring smooth optical detection while meeting the pipeline's conveying pressure requirements. The inner diameter of the transparent pipe section 11 is consistent with the inner diameter of the conveying pipeline, and concentric installation ensures that their central axes coincide. This maintains a stable flow state within the pipe section, preventing disturbances such as eddies and secondary flows caused by sudden changes in pipe diameter or axis misalignment, thus preventing any impact on fluorescence signal acquisition and concentration inversion. Since the laser needs to irradiate the medium inside the pipe from the outside, and the fluorescence signal also needs to penetrate from the inside of the pipe to the outside to be captured by the fluorescence detection unit, the pipe wall of the detection section must be optically transparent to both the excitation laser and the captured fluorescence. That is, the pipe wall material must have high light transmittance within both the excitation wavelength and fluorescence emission wavelength ranges to ensure that the excitation light energy effectively reaches the medium inside the pipe, while the fluorescence signal can penetrate the pipe wall with sufficient intensity to be received by the detection unit.

[0034] This application does not limit the material used for the transparent pipe section 11 or the method of its installation on the pipeline. Those skilled in the art can select appropriate transparent materials and connection methods based on factors such as the physicochemical properties of the actual transported medium, pipeline operating pressure, environmental conditions, and cost budget. As a feasible implementation, the transparent pipe section 11 is made of plexiglass. Plexiglass overcomes a series of defects inherent in acrylic materials. For example, acrylic is not resistant to organic solvents and easily swells or even dissolves when in prolonged contact with media such as refined oil and methanol; acrylic has low pressure resistance, making it difficult to meet the high-pressure operation requirements of long-distance pipelines; acrylic has low surface hardness, is easily scratched, ages and yellows, resulting in a short service life; furthermore, acrylic itself has strong fluorescent properties, which generate background fluorescence signals under laser excitation, interfering with the detection unit's capture of the target fluorescence signal, reducing the signal-to-noise ratio and measurement accuracy. In comparison, acrylic glass has significant advantages in all the aforementioned aspects: its pressure resistance is superior to ordinary glass, meeting the pressure requirements of oil transportation; it exhibits good chemical stability to common media such as methanol and refined oil, and is not prone to swelling or corrosion; its own fluorescence characteristics are weak, resulting in less interference with the target fluorescence signal; and compared to quartz glass, acrylic glass has a lower overall cost and is more convenient to process and shape. Therefore, using acrylic glass as the material for transparent pipe sections can simultaneously meet the requirements of monitoring accuracy, safety, and economy.

[0035] In some embodiments, to further improve monitoring reliability and avoid interference from stray ambient light on weak fluorescence signals, as a feasible implementation, the outer non-optical surface of the transparent pipe section 11 is covered with a black anti-light and scratch-resistant protective layer. Strong ambient light is typically present at pipeline sites, such as natural light, illumination light, and indicator lights from surrounding equipment. If the non-optical surface of the transparent pipe section 11 is not shielded, ambient light will enter the transparent pipe wall from the side, and after refraction and reflection, enter the laser irradiation area and fluorescence receiving area, forming stray light interference. This may drown out the weak fluorescence signal, causing a sharp drop in the signal-to-noise ratio, or even rendering the system ineffective. The black anti-light and scratch-resistant protective layer can effectively absorb leaked laser energy, preventing the laser from exiting the pipe from unexpected directions and avoiding safety hazards to operators. Simultaneously, this protective layer solves the stray light problem in one step through physical covering, eliminating the need for additional complex optical path shielding structures, reducing the requirements for laser alignment accuracy, and making on-site installation and commissioning simpler and faster. In addition, the protective layer also has a scratch-resistant function, which can protect the surface of the transparent pipe section 11 from accidental scratches during on-site construction and maintenance, and extend the service life of the pipe section.

[0036] Regarding the connection between the transparent pipe section 11 and the conveying pipeline, as a feasible approach, flanges are welded to both ends of the transparent pipe section 11. This flange connection allows for precise alignment and installation of the transparent pipe section 11 and the conveying pipeline, ensuring that their central axes coincide. Flange connections offer advantages such as easy installation and disassembly, reliable sealing, and strong adaptability, facilitating regular maintenance and replacement of the transparent pipe section 11. The flange sealing surface is perpendicular to the pipeline axis, ensuring the stability of the medium flow within the pipe section and preventing flow field disturbances caused by structural abrupt changes at the connection point, thereby reducing interference with fluorescence signal acquisition. A light-shielding sealing ring is also provided at the flange connection. This sealing ring not only seals the pipeline and prevents medium leakage but also isolates stray light from the environment, effectively blocking light from entering the transparent pipe section 11 from the flange joint and preventing stray light from interfering with the fluorescence signal. The light-shielding sealing ring can be made of black rubber or silicone, possessing both good elasticity and sealing performance as well as excellent light-shielding effect.

[0037] In the embodiments of this application, such as Figure 1 As shown, the laser sheet excitation unit 12 controls the laser source 121 to emit a laser beam. The laser beam is converted into sheet light by the beam shaper 122 and directed into the transparent tube section 11 to excite the first fluorescent indicator contained in the first medium in the tube, thereby inducing it to emit fluorescence and obtain the first fluorescent signal.

[0038] This application does not limit the type of laser source 121. As a feasible implementation, the laser source 121 can be a continuous-wave laser or a pulsed laser. Continuous-wave lasers have stable output and are suitable for scenarios requiring long-term continuous monitoring; pulsed lasers have high peak power and can excite strong fluorescence signals in a very short time, which is beneficial for suppressing background light interference. The wavelength emitted by the laser source 121 should match the excitation wavelength of the selected fluorescent indicator to obtain the best excitation efficiency.

[0039] In some embodiments, the beam shaper may consist of a collimating lens, a beam expander, and a cylindrical mirror. The collimating lens converts the diverging beam emitted from the laser source 121 into a parallel beam; the beam expander adjusts the beam diameter to meet sheet light size requirements; and the cylindrical mirror expands the beam in one direction while maintaining focus in another, thereby converting the point laser into sheet-like light. Through the combination of these optical elements, planar excitation along the pipe cross-section can be achieved, effectively improving spatial resolution.

[0040] As a feasible implementation, a correction lens group can also be set between the beam shaper and the transparent tube segment 11. The correction lens group can consist of two custom achromatic correction lenses whose refractive index matches the material of the transparent tube segment (such as plexiglass). This ensures that the sheet laser penetrates the medium perpendicularly, avoids excitation area shift caused by light path refraction, and ensures that the excitation light accurately illuminates the target detection area.

[0041] It should be understood that this application does not limit the location of the laser sheet excitation unit 12, but rather considers it as one feasible implementation method. Figure 2 As shown, the laser sheet excitation unit 12 and the first fluorescence detection unit 13 are arranged in a horizontal excitation-vertical reception optical path layout, which can reduce tube wall reflection and reduce background noise, so as to facilitate the reception of fluorescence signals by the first fluorescence detection unit 13, maximize the reception of fluorescence signals, and improve detection sensitivity.

[0042] During the process of the sheet laser passing through the transparent tube segment 11 and the medium inside the tube, the excitation light energy may attenuate along the propagation direction due to the absorption effect of the medium. As a feasible solution, the parameters of the beam shaper can be adjusted to ensure a uniform energy distribution of the sheet laser within the detection area, or the fluorescence intensity can be compensated for by attenuation using the Beer-Lambert law during the data processing stage.

[0043] In the embodiments of this application, such as Figure 1As shown, the first fluorescence detection unit 13 is used to capture the first fluorescence signal and convert it into a digital image signal. The digital image signal is a two-dimensional digital image data containing spatial location information and fluorescence intensity information, generated by photoelectric conversion, analog-to-digital conversion, and signal preprocessing of the light signal captured by the fluorescence detection unit. The grayscale value or color value of each pixel represents the fluorescence signal intensity at the corresponding spatial location.

[0044] This application does not limit the type of core device in the first fluorescence detection unit 13. As a feasible implementation, a CCD camera or a CMOS camera can be used. CCD cameras have the advantages of low noise, wide dynamic range, and high sensitivity, making them suitable for capturing weak fluorescence signals; CMOS cameras have the characteristics of low power consumption, fast readout speed, and high integration, making them suitable for monitoring scenarios with high time resolution requirements. The resolution and dynamic range of the detection unit directly affect the spatial positioning accuracy and the ability to capture weak fluorescence signals. Higher resolution enables precise positioning of the tail region boundary, while a wider dynamic range can simultaneously cover strong signals in high-concentration areas and weak signals in low-concentration areas, avoiding signal saturation or obliteration.

[0045] As a feasible implementation, a narrow-band filter is also provided between the first fluorescence detection unit 13 and the transparent tube section 11. The passband range of this narrow-band filter matches the emission spectrum of the selected fluorescent indicator, and is used to filter out stray light of non-target wavelengths such as excitation stray light, ambient light, and light scattered from the plexiglass tube wall, allowing only the target fluorescence signal to pass through, thereby significantly improving the signal-to-noise ratio of the fluorescence signal and ensuring that the signal captured by the detection unit mainly comes from the emission of the target fluorescent indicator.

[0046] In this embodiment, a fluorescent indicator is added to the first medium, while the second medium contains little or no concentration of the indicator. When the two media are mixed, the lower the concentration of the first medium in the trailing region, the weaker the fluorescence intensity generated by laser excitation. Therefore, the digital image signal generated by the first fluorescence detection unit 13 is essentially a spatial distribution map of fluorescence intensity. Bright areas in the image correspond to high concentrations of the first medium, dark areas correspond to low concentrations of the first medium, and the boundaries show a grayscale gradient from bright to dark. In other words, the fluorescence signal intensity captured by the first fluorescence detection unit 13 is positively correlated with the concentration of the first medium in the mixed region: the higher the concentration of the first medium, the stronger the fluorescence signal; the lower the concentration of the first medium, the weaker the fluorescence signal; when the concentration of the first medium approaches zero, the fluorescence signal also approaches the background noise level. Based on this characteristic, by analyzing the spatial distribution of the fluorescence signal, the accurate identification of the concentration distribution and boundary position of the first medium in the trailing region can be achieved. Compared to an analog signal that only outputs a total light intensity value or a simple digital voltage value, converting it into a digital image signal can accurately locate the spatial position and shape of the trailing region and accurately identify the boundary from the presence to absence of the first medium concentration.

[0047] In some embodiments, after capturing the first fluorescence signal, the first fluorescence detection unit 13 first converts it into an analog electrical signal, and then performs signal preprocessing, including amplification, filtering, and noise reduction, which can effectively eliminate high-frequency noise interference and significantly improve the signal-to-noise ratio and stability of the signal. Based on this, it is converted into a digital image signal to generate two-dimensional digital image data containing spatial location information and fluorescence intensity information. The grayscale value or color value of each pixel represents the fluorescence signal intensity at the corresponding spatial location. Clear and accurate image data can be obtained, facilitating subsequent image recognition and concentration calculation, thereby improving the monitoring accuracy and reliability of the tailing region boundary and concentration distribution.

[0048] In this embodiment, the first fluorescence detection unit 13 sends the acquired digital image signal to the data acquisition and analysis unit 14, which processes the signal to determine the start and end positions of the trailing region and calculate the trailing length.

[0049] The data acquisition and analysis unit 14 can be a personal computer (PC), laptop computer, mobile device, tablet computer, or other similar device. Alternatively, the data acquisition and analysis unit 14 can be a single server or a server cluster consisting of multiple servers. In some implementations, the server cluster can be a distributed cluster server. This application does not limit the specific form of the computing device 100.

[0050] It should be noted that the system architecture and application scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. Those skilled in the art will understand that, with the evolution of system architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0051] In the embodiments of this application, such as Figure 3 As shown, the data acquisition and analysis unit 14 is used to determine the start and end positions of the trailing area and calculate the trailing length through the following steps: S101. Determine the fluorescence intensity within the transparent tube segment 11 based on the digital image signal.

[0052] The data acquisition and analysis unit 14 determines the fluorescence intensity within the transparent pipe section 11 based on digital image signals. Determining fluorescence intensity based on digital image signals is essentially a process of extracting light intensity information from a two-dimensional pixel matrix. First, the data acquisition and analysis unit 14 delineates a rectangular region of interest in the digital image. This region covers the entire image range corresponding to the pipe's inner diameter, ensuring that all extracted fluorescence information originates from the internal medium of the pipe and eliminating interference from the pipe wall, flanges, and other non-medium areas on the light intensity analysis. The size and location of the region of interest can be preset according to the actual imaging position of the transparent pipe section 11, or it can be dynamically generated after automatically identifying the pipe boundaries using an image edge detection algorithm to adapt to image shifts under different installation conditions.

[0053] After defining the region of interest, the data acquisition and analysis unit 14 calculates the average grayscale value of all pixels within that region, using this average value as the fluorescence intensity value at the current moment. The average grayscale value can be calculated using an arithmetic mean or a weighted average. The weighted average assigns different weight coefficients to pixels at different locations based on the energy distribution characteristics of the excitation light on the pipe cross-section, correcting for measurement deviations caused by uneven excitation light energy. Through this processing, each frame of digital image signal can output a corresponding fluorescence intensity value for subsequent concentration inversion calculations.

[0054] As a specific implementation method, to further improve the accuracy of fluorescence intensity extraction, image data within the region of interest can be preprocessed before calculating the average grayscale value. This preprocessing includes, but is not limited to, background noise subtraction, outlier removal, and Gaussian filtering smoothing. Background noise subtraction can use a background image acquired when a non-fluorescent medium flows through a transparent tube section as a reference, subtracting the background grayscale value pixel by pixel from the current image to eliminate the influence of ambient stray light and detector dark current. Outlier removal is used to remove abnormal grayscale values ​​caused by factors such as tube wall scratches, stains, or detector defects, avoiding significant disturbances to the average value calculation results. Gaussian filtering smoothing effectively suppresses random noise, making the grayscale distribution more uniform and stable, thereby improving the repeatability and reliability of fluorescence intensity values.

[0055] S102. Determine the corresponding first medium concentration based on fluorescence intensity.

[0056] In some embodiments, the first medium concentration corresponding to the fluorescence intensity can be determined based on a pre-established calibration curve between fluorescence intensity and first medium concentration.

[0057] In establishing the calibration curve, a set of standard solutions of the first medium with known concentrations is first prepared. The concentration range of this set of standard solutions should cover the concentration range that may occur during actual monitoring, including the high concentration region of pure first medium to the low concentration tail region where the concentration approaches zero. To ensure the accuracy and representativeness of the calibration curve, the concentration points should be evenly distributed throughout the entire concentration range. In particular, the concentration points can be appropriately increased in the low concentration region to improve the resolution of concentration changes in the tail region.

[0058] Then, under the premise of maintaining completely consistent laser irradiation conditions, standard solutions of various concentrations are sequentially introduced into the transparent tube section 11 or an equivalent optical measurement cell. The laser sheet excitation unit 12 emits a sheet laser for excitation, and the first fluorescence detection unit 13 captures the fluorescence signals at each concentration. The corresponding fluorescence intensity values ​​are then processed by the data acquisition and analysis unit 14. During this process, key parameters such as laser power, detector gain, filter parameters, and exposure time should remain constant to ensure that changes in fluorescence intensity are entirely caused by differences in medium concentration, rather than by system parameter drift.

[0059] After obtaining a set of concentration-intensity data points, the data acquisition and analysis unit 14 performs fitting processing on this set of data. When the concentration of the fluorescent indicator is low and there is no significant self-absorption effect, the fluorescence intensity and concentration are usually linearly related, and the least squares method can be used to fit a linear curve. If the concentration range is wide or there is a self-absorption effect causing linear deviation, polynomial fitting or piecewise fitting can be used to improve the fitting accuracy. After the fitting is completed, the mathematical relationship between fluorescence intensity and the concentration of the first medium is obtained, i.e., the calibration curve.

[0060] For example, the calibration curve can be represented by the following formula:

[0061] Where If is the fluorescence intensity, C is the concentration of the first medium, and k and b are constants obtained from the fitting.

[0062] During on-site online detection, the data acquisition and analysis unit 14 inputs the real-time measured fluorescence intensity into the calibration curve to invert the concentration of the first medium in the transparent tube segment 11 at the current moment. The calibration curve can be pre-stored in the data acquisition and analysis unit 14 and can be periodically verified and calibrated using standard solutions to eliminate system response changes caused by factors such as laser aging, optical component contamination, and temperature drift, ensuring the long-term stability and accuracy of concentration inversion.

[0063] By pre-establishing a fitting curve, complex online calibration or real-time calculations are unnecessary during actual monitoring. Results can be quickly obtained simply by substituting measured values ​​into the curve, significantly improving the monitoring system's response speed. On-site monitoring eliminates the need to rely on unstable or easily disturbed real-time errors, thus eliminating additional errors introduced by online calibration and random errors from single monitoring sessions. This ensures consistency between monitoring results from different batches, improving the accuracy and reliability of monitoring the tailing region boundary and concentration distribution.

[0064] S103. Identify the start and end positions of the tail region formed by the first medium during transportation based on the preset concentration threshold, and calculate the tail length.

[0065] Because the fluorescent indicator is added only to the first medium, a one-to-one quantitative relationship is established between the fluorescence intensity and the concentration of the first medium. This allows for the precise capture and quantification of concentration changes, transforming the previously invisible molecular diffusion and mixing process into a measurable concentration gradient distribution, thus enabling objective and quantitative determination of the tailing region boundary. The tailing region is essentially a continuous range where the concentration of the first medium gradually transitions from high to zero. Two key concentration nodes exist: when the concentration drops to a relatively high threshold (e.g., 1%), it signifies the end of the high-concentration main mixing segment and the beginning of the low-concentration tailing region; when the concentration further drops to a relatively low threshold (e.g., 0.05%), it signifies that the concentration of the first medium has approached a negligible level, and the tailing region has essentially ended. Therefore, by acquiring continuous concentration distribution data along the transport direction and setting a concentration threshold, the starting and ending positions of the tailing region can be determined sequentially from upstream to downstream, and the tail length can then be calculated.

[0066] As a feasible implementation method, the preset concentration thresholds include a first concentration threshold and a second concentration threshold, with the first concentration threshold being greater than the second concentration threshold; the first concentration threshold is used to determine the starting position of the trailing region, and the second concentration threshold is used to determine the ending position of the trailing region.

[0067] The essence of the tailing region is a continuous range of change in the concentration of the first medium, gradually transitioning from high to zero. There are two key concentration nodes: when the concentration drops to the first concentration threshold, it signifies the end of the high-concentration main mixing section and the beginning of the low-concentration tailing region; when the concentration further drops to the second concentration threshold, it signifies that the concentration of the first medium has approached a negligible level and the tailing region has essentially ended. Therefore, by acquiring continuous concentration distribution data along the conveying direction and presetting the first and second concentration thresholds, a sequential scan can be performed from upstream to downstream: the position where the concentration first drops below the first concentration threshold is identified as the tailing start position; the scan continues to find the position where the concentration first drops below the second concentration threshold, which is identified as the tailing end position; finally, the difference between the end position and the start position is calculated, which is the tail length.

[0068] In this application embodiment, no specific limitation is made on the first concentration threshold and the second concentration threshold. For example, the first concentration threshold can be 1; the second concentration threshold can be 0.05%. That is, when the concentration of the first medium is less than or equal to 1%, the tailing area is determined to start, and when the concentration of the first medium drops to less than 0.05%, the tailing area is determined to end. Based on this, the location of the tailing area is identified and the length of the tailing oil is calculated.

[0069] As can be seen, the pipeline medium monitoring system 100 provided in this application adopts a non-invasive optical detection method, which can achieve high-precision identification and quantitative analysis of the trailing area formed by the slight density difference between the first medium and the second medium without contacting the medium. This allows for accurate acquisition of the trailing boundary and length, providing reliable data support for reducing oil mixing losses and optimizing cutting schemes. At the same time, it avoids the adverse effects of introducing foreign substances on the chemical stability of the medium and its subsequent use. Furthermore, the transparent pipe section has a simple structure and does not require complex sealing or high-pressure customized sensors, effectively reducing equipment costs and maintenance difficulty.

[0070] In some embodiments, the absorption of excitation light in the medium is not uniform, resulting in uneven energy distribution of the excitation light, i.e., uneven fluorescence intensity signals, which leads to errors. Specifically, when the sheet laser passes through the transparent tube segment 11 and the medium inside the tube, the laser energy is gradually absorbed along the propagation path by the fluorescent indicator and other light-absorbing substances in the medium. This causes the excitation light intensity on the side away from the laser incident point to be significantly weaker than that on the side closer to the incident point. This energy attenuation causes the first medium of the same concentration to produce fluorescence signals of different intensities at different spatial locations, thus causing deviations in concentration inversion. In addition, the fluorescence signal may also be absorbed by the medium itself during the process of passing through the medium and the tube wall, i.e., the self-absorption effect, which further exacerbates the nonlinear relationship between fluorescence intensity and concentration, affecting measurement accuracy.

[0071] Based on this, as a feasible implementation method, the pipeline medium monitoring system 100 provided in this application embodiment further includes a second fluorescence detection unit for capturing the second fluorescence signal generated after the second fluorescent substance is excited. The first medium contains both a first fluorescent substance and a second fluorescent substance, with the first fluorescent substance acting as a fluorescence donor and the second fluorescent substance acting as a fluorescence acceptor. The emission spectrum of the first fluorescent substance and the absorption spectrum of the second fluorescent substance at least partially overlap, allowing the fluorescence emitted by the first fluorescent substance after laser excitation to be absorbed by the second fluorescent substance, thereby exciting the second fluorescent substance to generate a second fluorescence signal. Through this fluorescence resonance energy transfer or cascade excitation mechanism, two fluorescence signals related to the concentration of the first medium can be obtained.

[0072] The data acquisition and analysis unit 14 is specifically used to: calculate the intensity ratio of the first fluorescence signal to the second fluorescence signal, and determine the concentration of the first medium based on the intensity ratio. The core advantage of using the intensity ratio instead of a single fluorescence intensity for concentration inversion is that the ratio calculation can simultaneously eliminate multiple common-mode errors. First, the uneven spatial distribution of excitation light energy across the pipe cross-section has an equal impact on both fluorescence signals; this impact can be offset by dividing the ratio. Second, the self-absorption attenuation effect of the fluorescence signal propagating in the medium can also be effectively compensated for by the ratio calculation, since the attenuation characteristics of the two fluorescence signals are similar. Therefore, compared to detection methods using only a single fluorescence signal, the dual-fluorescence ratio method significantly improves the robustness and accuracy of concentration measurement.

[0073] For example, the formula for fluorescence excitation intensity is as follows:

[0074] Where I0 is the excitation light intensity, ε is the absorption coefficient, C is the phosphor concentration, φ is the quantum yield, and η is the collection efficiency of the optical system. According to Beer-Lambert's law, the intensity of the excitation light decreases exponentially with the propagation distance as it passes through a medium containing a phosphor.

[0075] Among them, I e (x) represents the intensity of the emitted light (i.e., the transmitted light intensity) after the light has traveled a distance x through the medium, I0 is the excitation light intensity, ε is the absorption coefficient, C is the concentration of the phosphor, and x is the optical path length of the light propagating in the medium. The negative sign in the exponent indicates that the light intensity decreases exponentially with increasing optical path length and concentration. As shown in the above formula, the excitation light intensity decreases exponentially with propagation distance, and the fluorescence signal undergoes a similar attenuation process as it propagates outward after generation. This makes it difficult for a single fluorescence intensity value to directly and accurately reflect the medium concentration. However, by introducing a second fluorescent substance and calculating the intensity ratio of the first fluorescence signal to the second fluorescence signal, the excitation light intensity and the exponential terms related to medium absorption cancel each other out in the ratio calculation, thereby simultaneously eliminating two sources of error: uneven spatial distribution of the excitation light and self-absorption attenuation within the medium.

[0076] As a feasible approach, the fields of view of the two fluorescence detection units should precisely correspond to the same detection area, and the optical parameters of the two cameras (such as gain, exposure time, etc.) should be consistent or rigorously calibrated to ensure the accuracy of the ratio calculation. A beam splitter can be added to the optical path as needed to separate the composite fluorescence signal containing two fluorescence wavelengths according to wavelength, guiding them to the two cameras or different areas of the same camera for capture.

[0077] As can be seen, the pipeline medium monitoring system 100 provided in this embodiment, by introducing dual fluorescent indicators and dual fluorescent detection units, and using the fluorescence intensity ratio for concentration inversion, can effectively eliminate measurement errors caused by uneven distribution of excitation light energy and self-absorption of the medium, achieve high-precision identification of minute density differences between the first medium and the second medium, accurately capture the concentration distribution and boundary of the trailing area, and significantly improve measurement accuracy and system robustness.

[0078] In some embodiments, to achieve high-precision identification, fluorescent indicators have an optimal operating temperature range, and exceeding this range can lead to indicator failure. Specifically, key performance indicators of fluorescent indicators, such as fluorescence quantum yield, solubility, and miscibility with the medium, are all temperature-sensitive. When the temperature deviates from its optimal operating range (e.g., 15-35°C), the fluorescence efficiency will significantly decrease, and irreversible decomposition or failure may even occur, resulting in weakened or completely absent fluorescence signals. This can lead to severely underestimated concentration measurements or complete system failure. Therefore, real-time temperature monitoring and compensation are crucial for ensuring the long-term stable operation of the system.

[0079] As a feasible way to achieve this, such as Figure 1 As shown, the pipeline medium monitoring system 100 provided in this embodiment also includes a temperature compensation patch 111. During sequential transport, the physicochemical properties of the medium, such as density, viscosity, and fluorescence quantum yield of the fluorescent indicator, change significantly with temperature. Furthermore, the refractive index of the transparent pipe section 11 material (such as plexiglass) also changes with temperature, causing a shift in the optical path and affecting the transmission efficiency of the excitation light and fluorescence signal. Simultaneously, the temperature of the medium also affects the molecular diffusion rate and mixing characteristics, thereby altering the spatial distribution characteristics of the fluorescence signal.

[0080] To compensate for the impact of temperature changes on detection accuracy and ensure stable and accurate concentration measurement results under different seasons and pipe section temperature conditions, this application embodiment introduces a temperature compensation patch 111 into the monitoring system, and establishes a temperature correction coefficient and correction formula based on its measurement data. The temperature compensation patch 111 is installed on the outside of the transparent pipe section 11 to monitor the pipe wall temperature.

[0081] As a feasible implementation method, the temperature compensation patch 111 can use a platinum resistance temperature sensor or a thermocouple temperature sensor, with a temperature measurement accuracy within ±0.1℃ to provide a sufficiently accurate temperature reference. Thermally conductive silicone grease should be filled between the temperature compensation patch and the pipe wall to ensure good thermal contact, while direct contact with the medium inside the pipe should be avoided to prevent corrosion or contamination of the sensor.

[0082] The data acquisition and analysis unit 14 is also used to determine the light intensity correction coefficient corresponding to the tube wall temperature based on the pre-calibrated temperature-light intensity correction coefficient, and to correct the first fluorescence intensity within the determined transparent tube segment 11 based on the light intensity correction coefficient. The specific correction method is as follows: multiply or divide the measured fluorescence intensity by the correction coefficient at the current temperature to obtain the equivalent fluorescence intensity corrected to the reference temperature, and then substitute this equivalent fluorescence intensity into the calibration curve for concentration inversion. The pre-calibration process of the correction coefficient is as follows: at each temperature point, a standard solution of fluorescent medium of a fixed concentration is introduced, keeping parameters such as excitation power, detector gain, and flow rate constant, and the fluorescence intensity acquisition value at each temperature point is recorded. Using 25℃ as the reference temperature, the light intensity correction coefficient K(T) at that temperature is calculated, and a "temperature T - correction coefficient K(T)" correspondence table is established. During actual monitoring, the system reads the temperature value of the temperature compensation patch in real time, and quickly obtains the correction coefficient corresponding to the current temperature through table lookup or interpolation to correct the fluorescence intensity in real time.

[0083] Through the aforementioned temperature compensation mechanism, this system can meet the measurement needs of pipeline transportation in different seasons and regions, uniformly correcting data measured at different temperatures to equivalent values ​​at the standard temperature. This effectively eliminates measurement errors caused by fluctuations in medium temperature, significantly improving measurement accuracy. Simultaneously, the temperature data itself can also serve as an auxiliary monitoring parameter for analyzing changes in the thermodynamic state during pipeline transportation, providing reference information for process optimization and operation management.

[0084] This application also provides a method for monitoring the concentration of a pipeline medium, which can be applied to the pipeline medium monitoring system provided in the above embodiments. The method for monitoring the concentration of a pipeline medium includes: determining the fluorescence intensity in a transparent pipe section based on the digital image signal detected by the first fluorescence detection unit; determining the corresponding concentration of a first medium based on the fluorescence intensity; identifying the start and end positions of the tail region formed by the first medium during transportation according to a preset concentration threshold, and calculating the tail length.

[0085] As a feasible implementation method, the pipeline medium concentration monitoring system further includes a second fluorescence detection unit to capture the second fluorescence signal generated after the second fluorescent substance is excited. Determining the corresponding first medium concentration based on the fluorescence intensity includes: calculating the intensity ratio of the first fluorescence signal to the second fluorescence signal, and determining the first medium concentration based on this intensity ratio. The second fluorescent substance is added to the first medium, and the emission spectrum of the first fluorescent substance at least partially overlaps with the absorption spectrum of the second fluorescent substance.

[0086] In one possible implementation, the pipeline medium monitoring system further includes a temperature compensation patch installed on the outside of the transparent pipe section for monitoring the pipe wall temperature. The pipeline medium concentration monitoring method provided in this application further includes: determining a light intensity correction coefficient corresponding to the pipe wall temperature based on a pre-calibrated temperature-light intensity correction coefficient; and correcting the determined first fluorescence intensity within the transparent pipe section based on the light intensity correction coefficient.

[0087] In one possible implementation, the preset concentration thresholds in the pipeline medium monitoring system include a first concentration threshold and a second concentration threshold, wherein the first concentration threshold is greater than the second concentration threshold; the first concentration threshold is used to determine the starting position of the trailing region, and the second concentration threshold is used to determine the ending position of the trailing region.

[0088] For a detailed description of the above-mentioned optional methods, please refer to the foregoing method embodiments, which will not be repeated here. Furthermore, the explanation of any of the above-provided devices and the description of their beneficial effects can be found in the corresponding method embodiments, which will not be repeated here.

[0089] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional units is used as an example. In practical applications, the above functions can be assigned to different functional units as needed, that is, the internal structure of the device can be divided into different functional units to complete all or part of the functions described above.

[0090] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another apparatus, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0091] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0092] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0093] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A pipeline medium monitoring system, characterized in that, include: Transparent tube segment, laser sheet excitation unit, first fluorescence detection unit, and data acquisition and analysis unit; The transparent tube segment is installed on the delivery pipeline to allow the laser to penetrate and excite the medium inside the tube; The laser sheet excitation unit is used to emit a sheet-shaped laser after beam shaping and inject it into the transparent tube segment to excite a first fluorescent indicator pre-added to the first medium to generate a first fluorescent signal; the delivery pipe is used to sequentially deliver the first medium and the second medium. The first fluorescence detection unit is used to capture the first fluorescence signal and convert it into a digital image signal; The data acquisition and analysis unit is used to determine the fluorescence intensity within the transparent tube segment based on the digital image signal; The concentration of the first medium is determined based on the fluorescence intensity, and the start and end positions of the tail region formed by the first medium during the transportation process are identified according to the preset concentration threshold, and the tail length is calculated.

2. The pipeline medium monitoring system according to claim 1, characterized in that, The transparent pipe section is made of plexiglass, and its outer non-optical surface is covered with a black anti-light and anti-scratch protective layer, and a light-shielding sealing ring is provided at the flange connection.

3. The pipeline medium monitoring system according to claim 1, characterized in that, The system also includes: The second fluorescence detection unit is used to capture the second fluorescence signal generated after the second fluorescent substance is excited; The data acquisition and analysis unit is specifically used to: calculate the intensity ratio of the first fluorescence signal to the second fluorescence signal, and determine the concentration of the first medium based on the intensity ratio; The second fluorescent substance is added to the first medium, and the emission spectrum of the first fluorescent substance and the absorption spectrum of the second fluorescent substance at least partially overlap.

4. The pipeline medium monitoring system according to claim 1, characterized in that, The laser sheet photoexcitation unit and the first fluorescence detection unit are arranged in a horizontal excitation-vertical reception optical path layout.

5. The pipeline medium monitoring system according to claim 1, characterized in that, The data acquisition and analysis unit is specifically used to: determine the concentration of the first medium corresponding to the fluorescence intensity based on a pre-established calibration curve between fluorescence intensity and the concentration of the first medium.

6. The pipeline medium monitoring system according to claim 1, characterized in that, The first medium is methanol; the fluorescent indicator is disodium fluorescein, the effective excitation wavelength of which is 465-490 nm, and the concentration added to the first medium is 3-5 mg / L.

7. The pipeline medium monitoring system according to claim 1, characterized in that, The system also includes a temperature compensation patch, which is installed on the outside of the transparent pipe section to monitor the pipe wall temperature; The data acquisition and analysis unit is also used to determine the light intensity correction coefficient corresponding to the tube wall temperature based on the pre-calibrated temperature-light intensity correction coefficient, and to correct the first fluorescence intensity in the transparent tube segment based on the light intensity correction coefficient.

8. The pipeline medium monitoring system according to claim 1, characterized in that, The preset concentration threshold includes a first concentration threshold and a second concentration threshold, wherein the first concentration threshold is greater than the second concentration threshold; The first concentration threshold is used to determine the starting position of the trailing region, and the second concentration threshold is used to determine the ending position of the trailing region.

9. A method for monitoring the concentration of a pipeline medium, characterized in that, The method, applied to the pipeline medium monitoring system according to any one of claims 1-8, comprises: The fluorescence intensity within the transparent tube segment is determined based on the digital image signal detected by the first fluorescence detection unit. The corresponding first medium concentration is determined based on the fluorescence intensity; The starting and ending positions of the tail region formed by the first medium during transportation are identified based on a preset concentration threshold, and the tail length is calculated.

10. The monitoring method according to claim 9, characterized in that, The pipeline medium monitoring system further includes: a second fluorescence detection unit, used to capture the second fluorescence signal generated after the second fluorescent substance is excited; The step of determining the corresponding first medium concentration based on the fluorescence intensity includes: Calculate the intensity ratio of the first fluorescence signal to the second fluorescence signal, and determine the concentration of the first medium based on the intensity ratio; The second fluorescent substance is added to the first medium, and the emission spectrum of the first fluorescent substance and the absorption spectrum of the second fluorescent substance at least partially overlap.

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