A three-light-source-based in-situ oil-in-water detection device, method and use

Abstract

The application belongs to the technical field of environmental monitoring and optical detection, and provides a water oil in-situ detection device, method and application based on three light sources, which integrates ultraviolet light with a wavelength of 254nm, visible light with a wavelength of 430nm, infrared light with a wave number of 2930cm ‑1 and a detection unit, and synchronously obtains fluorescence, visible light absorption and infrared absorption signals.Analysis and processing module combines visible light absorption and an empirical correction coefficient to correct the baseline drift of ultraviolet fluorescence and infrared signals in real time, fuses multi-dimensional optical information to identify the type of oil and calculate the concentration.Through the three-waveband cooperative mechanism, the turbidity interference is effectively eliminated, the mineral oil and the animal and plant oil are accurately distinguished, and the self-cleaning unit and the three-dimensional light path adjusting structure are matched, so that the precision, stability and efficiency of in-situ detection in a complex water body environment are significantly improved, and the device is suitable for the field of water quality online monitoring.

Description

Technical Field

[0001] This invention belongs to the field of environmental monitoring and optical detection technology, and relates to an in-situ oil detection device, method and application based on three light sources in water. Background Technology

[0002] In the fields of petrochemicals, marine engineering, and environmental monitoring, real-time in-situ detection of oil pollutants in water bodies is of great significance for production safety and ecological protection. The presence of oil in water not only pollutes the aquatic environment but can also adversely affect equipment operation, process flows, and product quality. Therefore, developing efficient, accurate, and online monitoring methods for oil detection in water has become an important requirement.

[0003] Currently, common methods for oil detection in water include ultraviolet fluorescence, infrared absorption, and laser scattering. However, these methods still have certain limitations in practical applications. For example, detection systems based on a single light source or optical mode often suffer from low sensitivity, poor stability, or insufficient adaptability due to factors such as the complexity of oil composition, background interference from water, and uneven oil droplet size distribution. Furthermore, traditional methods largely rely on offline sampling and laboratory analysis, making it difficult to achieve truly in-situ, real-time, and continuous monitoring, and thus failing to meet the demands of modern industry for rapid response and intelligent management.

[0004] Currently, improved solutions to the above-mentioned problems have emerged in existing technologies, but significant shortcomings still exist. For example, existing technologies use ultraviolet and infrared light sources to measure the fluorescence of insulating oil and the turbidity of seawater, respectively, and correct the fluorescence signal intensity using turbidity information. However, this approach still has the following substantial defects: First, its turbidity correction uses infrared scattering light to measure turbidity. For water bodies containing colored dissolved organic matter (CDOM), the colored substances absorb both ultraviolet and visible light, causing the infrared scattering method to be unable to correct the fluorescence attenuation caused by the colored substances. Second, this approach can only detect a single type of insulating oil (alkylbenzene) and cannot distinguish between mineral oil and animal / vegetable oil. Third, this prior art does not have a time-sequence alternation control mechanism, resulting in spectral crosstalk when multiple light sources are operating simultaneously.

[0005] Therefore, there is a greater need to develop an in-situ optical detection technology for oil and water that can adapt to complex aquatic environments, acquire multiple parameters simultaneously, and operate stably under actual working conditions. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of incomplete background interference elimination, weak oil differentiation ability, and poor long-term stability in existing technologies. It provides a three-light source-based in-situ oil detection device, method, and application in water. This method integrates 254nm ultraviolet light, 430nm visible light, and 2930nm light... -1The system utilizes three different wavelengths and characteristics of infrared light sources, combined with collaborative strategies such as three-dimensional optical path fine-tuning, turbidity adaptive timing control, real-time baseline correction, and window self-cleaning, to achieve high-precision and high-reliability identification and quantitative analysis of oil pollutants in water. It can also effectively distinguish between mineral oil and animal and vegetable oils, meeting the engineering requirements for in-situ, real-time, and long-term stable monitoring.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In one aspect, a three-source in-situ oil-water detection device is provided, comprising an optical module, a sample flow and reaction module, a mechanical structure and integration module, and an analysis and processing module.

[0009] Specifically, the optical module is used to generate detection light and receive optical signals after being acted upon by the water sample being tested, including a light-emitting unit and a detection unit; The sample flow and reaction module is used to guide the flow of the water sample to be tested and provide a space for the interaction between light and the sample. It includes a detection chamber and a sealing cover. The detection chamber is used to form a defined optical path channel and sample flow channel. The sealing cover is used to seal the detection chamber to form a closed optical reaction environment. The mechanical structure and integrated module are used to support, fix and integrate various functional modules, including a main support structure and a top mounting leveling interface. The main support structure is used to fix the optical module and the sample flow and reaction module, and the top mounting leveling interface is used to connect the entire device to an external support. The analysis and processing module is electrically connected to the optical module and is used to correct the baseline drift of the ultraviolet fluorescence signal and the infrared absorption signal in real time based on the visible light absorbance according to the electrical signal converted by the detection unit, and to analyze and obtain information on the type and concentration of oil in the water. The light-emitting unit includes an ultraviolet light source unit, a visible light source unit, and an infrared light source unit, which are used to emit ultraviolet light, visible light, and infrared light to the water sample being tested in the detection chamber, respectively. The detection unit is used to receive the fluorescence signal generated by the oily substances in the water sample being tested in the detection chamber excited by the ultraviolet light, the transmitted light signal after the visible light is absorbed by the water sample being tested in the detection chamber, and the transmitted light signal after the infrared light is absorbed by the water sample being tested in the detection chamber, and convert them into electrical signals.

[0010] Furthermore, the wavelength of the ultraviolet light is 254 nm, the wavelength of the visible light is 430 nm, and the wavenumber of the infrared light is 2930 cm⁻¹. -1 .

[0011] Furthermore, the analysis and processing module calls the pre-stored spectral database based on the electrical signal converted by the detection unit, and compares the received fluorescence spectral features, visible light absorbance and infrared absorption peak features with the standard spectral features of different oils in the database to identify the type of oil. Based on the fluorescence intensity, visible light absorbance and infrared light absorption intensity, combined with the pre-calibrated concentration curve, the concentration of the corresponding oil is calculated.

[0012] Furthermore, the ultraviolet light source unit, the visible light source unit, and the infrared light source unit are turned on alternately according to a preset time sequence to avoid mutual interference between the three detection light bands. The analysis and processing module is also used to extract the fluorescence signal, visible light absorption signal, and infrared absorption signal of the corresponding time sequence based on the electrical signals collected by the detection unit at different time sequences, as the basic data for the fitting comparison and concentration calculation.

[0013] Furthermore, the detection unit includes a photodiode mounting plate, a photodetector, and a converging lens. The photodiode mounting plate is used to fix the photodetector. The converging lens is disposed in the optical path between the detection cavity and the photodetector, and is used to converge the light after the water sample in the detection cavity is reacted to onto the photosensitive surface of the photodetector. The focal length of the converging lens is matched with the optical path length of the detection cavity, so that the light is accurately converged to the center of the photosensitive surface of the photodetector. The photodiode mounting plate is also provided with a light shield, which is sleeved on the outer periphery of the detection unit to shield the interference of ambient stray light on the detection signal.

[0014] Furthermore, the detection chamber is made of a chemically inert material, and its internal flow channel surface has a low-adsorption fluorocarbon coating, and the flow channel adopts a curved surface design to reduce sample residue; a sealing ring is provided between the sealing cover and the detection chamber to achieve pressure sealing.

[0015] Furthermore, it also includes a self-cleaning unit, which is disposed outside the optical window of the detection cavity and is used to remove contaminants adhering to the optical window; the self-cleaning unit includes a piezoelectric ceramic sheet and a polytetrafluoroethylene scraper, wherein the vibration frequency of the piezoelectric ceramic sheet is 40kHz to 100kHz.

[0016] Furthermore, the ultraviolet light source unit, the visible light source unit, and the infrared light source unit each have a corresponding adjustment device. The adjustment device is installed on the main support structure and is used to adjust at least one of the pitch angle, horizontal position, and vertical position of each light source unit so that the detection light emitted by each light source unit passes through the center of the optical path channel of the detection cavity.

[0017] Furthermore, the main support structure is an integrated metal frame with a positioning reference surface inside, through which the optical module and the sample flow and reaction module are aligned and installed; the device also includes a protective shell, which is used to house the optical module, the sample flow and reaction module and the analysis and processing module.

[0018] Secondly, a method for in-situ detection of oil in water based on three light sources is provided, applied to the aforementioned device. The method includes the following steps: S1: Fix the detection device in the water body to be tested through the top mounting leveling interface, so that the sample flow and reaction module is connected to the water body to be tested, so that the water body to be tested flows into the detection chamber as the water sample to be tested. S2: Control the light-emitting units of the optical module to turn on alternately according to a preset time sequence, and emit ultraviolet light, visible light and infrared light to the water sample to be tested in the detection cavity in sequence; S3: The detection unit receives light after it has been affected by oily substances in the water sample being tested, and transmits the converted electrical signal to the analysis and processing module. S4: The analysis and processing module corrects the baseline drift of the ultraviolet fluorescence signal and the infrared absorption signal in real time based on the received electrical signal and analyzes to obtain information on the type and concentration of oil in the water.

[0019] Further, in step S2, ultraviolet light, visible light, and infrared light are sequentially emitted into the water sample to be tested in the detection chamber, including: S21: Turn on the ultraviolet light source unit and emit ultraviolet light of the first wavelength into the water sample to be tested in the detection chamber to excite the oily substances in the water sample to produce fluorescence. The first wavelength is configured to be a wavelength that easily excites the oily substances in the water to produce fluorescence. S22: After turning off the ultraviolet light source unit, turn on the visible light source unit to emit visible light of the second wavelength into the water sample to be tested in the detection chamber, so as to measure the absorbance of the water sample to the second wavelength of visible light. The second wavelength is configured to be easily absorbed by oil in the water. S23: After turning off the visible light source unit, turn on the infrared light source unit and emit infrared light of the third wavelength into the water sample to be tested in the detection cavity to measure the absorbance of the water sample to the third wavelength infrared light. The third wavelength is configured to correspond to the wavelength of the characteristic absorption peak of oil in the water.

[0020] Furthermore, step S2 also includes: Before turning on the light-emitting unit, the optical path is adjusted. At least one of the pitch angle, horizontal position and vertical position of the ultraviolet light source unit, the visible light source unit and the infrared light source unit is adjusted by the adjustment device so that the optical path of each wavelength light passes through the center of the optical path channel of the detection cavity.

[0021] Further, in step S4, the analysis and processing module analyzes the received electrical signal to obtain information on the type and concentration of oil in the water, including: S41: The analysis and processing module calls the pre-stored spectral database, and compares the received fluorescence spectral features, visible light absorbance and infrared absorption peak features with the standard spectral features of different oils in the database to identify the type of oil. S42: Based on the identified oil type, retrieve the pre-calibrated concentration-signal intensity standard curve of the corresponding oil type, calculate the initial concentration value based on ultraviolet fluorescence intensity, visible light absorbance and infrared characteristic absorption peak intensity, and then fuse them through a weighted average algorithm to obtain the final oil concentration value.

[0022] Furthermore, the above method also includes: S5: During the continuous operation of the detection device, the self-cleaning unit is activated once at preset intervals to remove contaminants attached to the optical window of the detection cavity.

[0023] Thirdly, the above-mentioned device is provided for distinguishing between mineral oil and animal and vegetable oils. Based on the real-time measurement of the background absorbance of the water sample under visible light to correct turbidity interference, and combined with the synergistic analysis of ultraviolet light-excited fluorescence signal and infrared light absorption signal, the classification and identification of mineral oil and animal and vegetable oils are realized. The identification criteria for mineral oil are that a fluorescence signal is generated under ultraviolet light excitation and an infrared absorption peak is present at the infrared light location. The identification criteria for animal and vegetable oils are that the ratio of the absorbance of visible light to the absorbance of infrared light is greater than a preset threshold.

[0024] The three-source in-situ oil-water detection device of the present invention integrates ultraviolet, visible and infrared light sources to form a light-emitting unit, and is equipped with a corresponding detection unit. Compared with the prior art, it has at least the following advantages: 1. Significantly improves detection accuracy and stability in complex aquatic environments: By using visible light absorbance as a real-time turbidity correction benchmark, background noise caused by high turbidity, color changes, and suspended matter scattering is eliminated from the physical level, ensuring that the detection signal does not saturate or become distorted during long-term operation in harsh conditions such as industrial circulating water and nearshore sea areas.

[0025] 2. Achieve accurate differentiation between mineral oil and animal and vegetable oils: By constructing a multidimensional signal ratio classification model, the technical bottleneck of a single optical mode being unable to simultaneously identify aromatic and non-aromatic hydrocarbons is effectively solved, significantly reducing the risk of false positives or false negatives caused by the complexity of oil composition.

[0026] 3. Enhanced environmental adaptability and long-term maintenance-free capability of the device: The composite self-cleaning unit, which integrates piezoelectric ceramic ultrasonic vibration and polytetrafluoroethylene mechanical scraping, combined with the chemically inert fluorocarbon coating curved flow channel design, inhibits biofilm adhesion, sediment deposition and sample residue from two dimensions: active cleaning and passive anti-fouling, achieving long-term unattended and stable operation.

[0027] 4. Optimize detection efficiency and energy consumption management: The strategy of sequential alternating excitation and adaptive duty cycle control avoids spectral crosstalk when multiple light sources work simultaneously, and can dynamically adjust the integration time and light source priority according to real-time turbidity feedback, shortening the single complete detection cycle to the second level.

[0028] 5. Enables intelligent monitoring and analysis of mixed oils: Combining data storage and remote communication functions, it supports long-term recording and real-time uploading of detection data, meeting the needs of intelligent environmental monitoring management. Experimental verification shows that within a concentration range of 0.1 mg / L to 100 mg / L, the measurement error can be controlled within ±5%. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a simplified front view of the mechanical structure of the in-situ oil-water detection device based on three light sources according to the present invention. Figure 2 This is the main flowchart of the in-situ oil detection method in water based on three light sources of the present invention; Figure 3 This is a detailed flowchart illustrating the continuous online monitoring process using an in-situ oil-water detection device according to the present invention. Among them, 1. Top mounting leveling interface; 2. First stainless steel conversion joint; 3. Sealing cover plate; 4. Main support structure; 5. Photodiode detection cavity; 6. Second stainless steel conversion joint; 7. Third stainless steel conversion joint; 8. LED detection cavity; 32. First partition limiting groove; 33. Light source positioning through hole; 34. Second partition limiting groove. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] It should be noted that: Appendix Figure 1 This is a simplified front view of the mechanical structure of the in-situ oil-water detection device of the present invention, focusing on the spatial layout of the main support structure, the light source mounting base, and the detection cavity. Some optical and functional modules (such as the infrared light source unit, converging lens, light shield, self-cleaning unit, and sealing cover) are not shown separately in the figure due to their small size or integration inside the cavity, but their structure and connection relationships have been described in detail in this embodiment and conform to the conventional design understanding of those skilled in the art. This simplified illustration does not affect the full disclosure of the technical solution of the present invention.

[0034] This invention provides an in-situ oil-water detection device based on three light sources, which mainly includes an optical module, a sample flow and reaction module, a mechanical structure and integration module, and an analysis and processing module, as well as a protective shell, a sealing cover, etc.

[0035] 1. Optical module The optical module is used to generate detection light and receive optical signals after being processed by the water sample being tested. It includes a light-emitting unit and a detection unit.

[0036] In an optional embodiment, the light-emitting unit includes an ultraviolet light source unit, a visible light source unit, and an infrared light source unit, which are used to emit ultraviolet light, visible light, and infrared light to the water sample being tested in the detection chamber, respectively. The detection unit is used to receive the fluorescence signal generated by the oily substances in the water sample being tested in the detection chamber excited by the ultraviolet light, the transmitted light signal after the visible light is absorbed by the water sample being tested in the detection chamber, and the transmitted light signal after the infrared light is absorbed by the water sample being tested in the detection chamber, and convert them into electrical signals.

[0037] Specifically, the ultraviolet light source unit uses a 254nm low-pressure mercury lamp to excite the fluorescence signal of mineral oil in the water. The visible light source unit uses a 430nm blue LED to measure the background absorbance of the water sample in real time to correct for turbidity interference. The infrared light source unit uses a 2930cm² LED. -1 A quantum cascade laser of a specific wavelength is used to detect the characteristic absorption peaks of CH bonds in oily substances. It is arranged symmetrically at 120° with the ultraviolet light source unit and the visible light source unit on the same mounting plane of the main support structure 4.

[0038] Three light source units are mounted on the main support structure 4 via adjustment devices. Each adjustment device includes a pitch adjustment screw and a horizontal displacement slider. The pitch adjustment screw passes through the lug of the light source unit and engages with a threaded hole in the main support structure 4 to adjust the pitch angle of the light source. The horizontal displacement slider is embedded in a limiting groove in the main support structure 4 to adjust the horizontal position of the light source. Each light source unit also has a corresponding adjustment device to ensure that the detection light emitted by each light source unit can be precisely focused at the center of the optical path channel of the detection cavity by adjusting at least one of the pitch angle, horizontal position, and vertical position, thus ensuring effective transmission of the optical signal.

[0039] Each light source unit is equipped with a light stabilization circuit, which monitors and adjusts the luminous power of the light source unit in real time to compensate for light intensity drift caused by voltage fluctuations or changes in ambient temperature, thereby improving the repeatability and long-term stability of the detection. Furthermore, each light source unit can select different power levels based on the transparency of the water sample and the expected detection concentration range: in low-concentration oil detection scenarios, the power of the ultraviolet light source unit is increased to enhance the fluorescence signal; in high-turbidity water sample detection scenarios, the power of the visible light and infrared light source units is increased to ensure sufficient transmitted light signal.

[0040] The ultraviolet light source unit, the visible light source unit, and the infrared light source unit are turned on alternately according to a preset time sequence to avoid mutual interference between the three detection light bands. The analysis and processing module is also used to extract the fluorescence signal, visible light absorption signal, and infrared absorption signal of the corresponding time sequence based on the electrical signals collected by the detection unit at different time sequences, as the basic data for the fitting comparison and concentration calculation.

[0041] In an optional embodiment, the detection unit is fixed to the rear side of the detection cavity and includes a photodiode mounting plate, a photodetector, and a converging lens. The photodiode mounting plate is used to fix the photodetector. The converging lens is disposed in the optical path between the detection cavity and the photodetector, and is used to converge the light emitted by the water sample in the detection cavity onto the photosensitive surface of the photodetector. The focal length of the converging lens matches the optical path length of the detection cavity, so that the light is precisely converged to the center of the photosensitive surface of the photodetector. The converging lens is made of high-transmittance optical glass, and its focal length can be adjusted according to the length of the detection cavity and the position of the light source unit. A light shield is also provided on the photodiode mounting plate, which is fitted around the periphery of the detection unit to shield the detection signal from interference by ambient stray light.

[0042] 2. Sample flow and reaction module The sample flow and reaction module guides the flow of the water sample and provides space for the interaction between light and the sample. It includes a detection chamber and a sealing cover 3. The detection chamber forms a defined optical path and sample flow channel. Made of chemically inert materials such as polytetrafluoroethylene (PTFE), it avoids reaction with chemicals in the water sample, ensuring the accuracy of the test results. Its internal flow channel surface is coated with a low-adsorption fluorocarbon coating, reducing the adsorption of oily substances on the flow channel surface, preventing cross-contamination, and improving the repeatability of the test. The flow channel also features a curved surface design to reduce sample residue. The sealing cover 3 seals the detection chamber to create a closed optical reaction environment. A sealing ring (such as an O-ring) is installed between the cover and the detection chamber, and the cover is secured with bolts to achieve a pressure seal. This allows for in-situ testing at different water depths and prevents water sample leakage and interference from external light.

[0043] In this embodiment, as Figure 1 As shown, the detection cavity can be structurally divided into a photodiode detection cavity 5 and an LED detection cavity 8, which are sealed and connected by a first stainless steel adapter 2, a second stainless steel adapter 6, and a third stainless steel adapter 7 to allow fluid flow. The photodiode detection cavity 5 is used to install components of the detection unit, while the LED detection cavity 8 is used to accommodate the detection light emitted by the light-emitting unit. Furthermore, the main support structure 4 is also provided with a first separating limiting groove 32, a light source positioning through hole 33, and a second separating limiting groove 34, which are used to limit the installation position of the light source unit, provide a precise channel for the light path, and separate different functional areas, ensuring the repeatability of the light path positioning and the consistency of assembly.

[0044] 3. Mechanical Structure and Integrated Modules The mechanical structure and integrated module are used to support, fix and integrate various functional modules, including the main support structure 4 and the top mounting leveling interface 1. The main support structure 4 is used to fix the optical module and the sample flow and reaction module, and the top mounting leveling interface 1 is used to connect the entire device to the external support.

[0045] In an optional embodiment, the main support structure 4 is an integrated metal frame fixed inside the protective shell. It is provided with a limiting groove and threaded holes, and has a positioning reference surface inside. The optical module and the sample flow and reaction module are aligned and installed through the positioning reference surface to ensure that the detection light emitted by the light-emitting unit can accurately pass through the optical path channel of the detection cavity, thereby improving the utilization rate of the optical signal and the detection accuracy.

[0046] 4. Analysis and Processing Module The analysis and processing module is electrically connected to the optical module and has a built-in embedded processor and storage unit. It stores a pre-calibrated spectral database, classification threshold matrix and concentration curve. It is used to correct the baseline drift of ultraviolet fluorescence signal and infrared absorption signal in real time based on visible light absorbance according to the electrical signal converted by the detection unit, and analyze the type and concentration information of oil in water.

[0047] The analysis and processing module calls the pre-stored spectral database based on the electrical signal converted by the detection unit, and compares the received fluorescence spectral features, visible light absorbance and infrared absorption peak features with the standard spectral features of different oils in the database to identify the type of oil. Based on the fluorescence intensity, visible light absorbance and infrared light absorption intensity, combined with the pre-calibrated concentration curve, the concentration of the corresponding oil is calculated.

[0048] 4.1 Signal Preprocessing After receiving the electrical signal converted by the detection unit, the ultraviolet fluorescence electrical signal, visible light absorption electrical signal and infrared characteristic absorption electrical signal are first preprocessed. The preprocessing includes noise reduction processing, baseline correction and signal normalization processing to filter out environmental electromagnetic interference, light source fluctuation noise and instrument background signal, so as to ensure the stability and authenticity of the original signal.

[0049] 4.2 Baseline Drift Correction The baseline drift of the ultraviolet fluorescence signal and the infrared absorption signal is corrected in real time based on the 430nm visible light absorbance to eliminate background interference such as turbidity and chromaticity. The baseline drift correction algorithm is as follows: First, let the original intensity of the ultraviolet fluorescence signal be... The absorbance of visible light at 430nm is The corrected ultraviolet fluorescence intensity Calculate using the following formula (1): Equation (1); in, This is the first empirical correction factor, with a value ranging from 0.5 to 2.0, which can be obtained by pre-testing standard solutions of different turbidities.

[0050] Similarly, let the original intensity of the infrared absorbed signal be... Corrected infrared absorption intensity Calculate using the following formula (2): Equation (2); in, The second empirical correction factor has a value range of 0.3 to 1.5 and is obtained by pre-testing standard solutions of different turbidities.

[0051] For water bodies containing colored dissolved organic matter, the absorbance at 430 nm visible light is... The algorithm can simultaneously characterize the combined extinction effect of turbidity particles and colored substances, thus the above correction algorithm has better correction accuracy than turbidity measurement methods based solely on infrared scattering.

[0052] 4.3 Oil Type Identification The analysis and processing module calls the pre-stored spectral database, and compares the received fluorescence spectral features, visible light absorbance and infrared absorption peak features with the standard spectral features of different oils in the database to identify the type of oil.

[0053] In an optional embodiment, the analysis and processing module calls a pre-stored standard spectral database containing feature spectral datasets for at least 10 common oil types (such as gasoline, diesel, lubricating oil, and animal and vegetable oils), with each oil type corresponding to a unique feature spectral label. The analysis and processing module performs multi-dimensional fitting and comparison between the received three-band signal features and the standard spectral features in the database, calculates feature similarity using the Euclidean distance algorithm, and combines the three-band signal weighting coefficients to achieve accurate identification of oil types.

[0054] In an optional embodiment, the analysis and processing module incorporates a multi-peak matching algorithm and an independent component analysis algorithm to perform characteristic peak decomposition on the three-band signals of the mixed oil sample, identify the characteristic peak positions and intensities of different oils, separate the signal contribution values ​​of each oil through the independent component analysis algorithm, and then calculate the concentration of each oil separately.

[0055] 4.4 Quantitative Calculation of Concentration Based on the identified oil type, retrieve the corresponding pre-calibrated concentration-signal intensity standard curve (which needs to be generated through a series of standard oil solutions with varying concentration gradients before the device leaves the factory or during periodic calibration to ensure that the concentration calculation error is controlled within ±5%), and calculate the initial concentration value based on ultraviolet fluorescence intensity, visible light absorbance, and infrared characteristic absorption peak intensity, respectively. , , Then, the oil concentration values ​​are obtained by merging them using a weighted average algorithm.

[0056] Specifically, the final oil concentration value C can be obtained by using the weighted average algorithm of the following formula (3): Equation (3); Among them, weight , , satisfy The values ​​of each weight are dynamically adjusted based on the currently identified oil type, for example: 1) When identified as mineral oil (mainly composed of aromatic hydrocarbons), the fluorescence signal has a high signal-to-noise ratio, with three weights... , , The values ​​can be 0.6, 0.2, and 0.2 respectively; 2) When identified as animal or vegetable oil (with triglycerides as the main component), the visible light absorption characteristics are obvious, with three weighted values. , , The values ​​can be 0.1, 0.6, and 0.3 respectively; 3) When the oil is identified as a mixed oil, equal weighting can be used.

[0057] The aforementioned weight values ​​are determined in advance through principal component analysis and signal-to-noise ratio evaluation of multiple sets of experimental data of various standard oils, and can also be adaptively optimized based on historical test results during actual use.

[0058] 4.5 Construction and Adaptive Update of the Classification Threshold Matrix Specifically, the classification threshold matrix is ​​constructed as follows: Standard samples of 10 kinds of mineral oil (such as diesel, lubricating oil, and crude oil) and 10 kinds of animal and vegetable oil (such as soybean oil, rapeseed oil, and lard) are collected, and standard solutions with concentrations of 1 mg / L, 5 mg / L, 10 mg / L, and 20 mg / L are prepared respectively. The three-band signal characteristics of each solution are measured using this device. A scatter plot is drawn with R1 as the abscissa and R2 as the ordinate. Mineral oil samples are concentrated in the region where R1 > 2.0 and R2 < 0.5, while animal and vegetable oil samples are concentrated in the region where R1 < 0.8 and R2 > 1.2. The decision boundary between the two types of oil is divided using the radial basis function through the support vector machine algorithm, and the decision boundary equation is obtained as 0.8 × R1 + 1.2 × R2 = 1.6. The parameters of this equation are stored in the analysis and processing module as the classification threshold matrix. When the R1 and R2 of the sample to be tested are substituted into the equation and the result is greater than 1.6, it is judged as mineral oil; when it is less than 1.6, it is judged as animal or vegetable oil.

[0059] In actual long-term operation, the analysis and processing module is also configured to dynamically update the classification threshold matrix based on historical detection data. Specifically, after collecting N sets (N≥50) of detection data verified manually or by a third-party method, the system automatically re-executes support vector machine classification training, updates the coefficients of the decision boundary equation, and stores the updated threshold matrix in the storage unit. This adaptive update mechanism can overcome signal drift caused by factors such as seasonal changes in the water environment and aging of the optical window, maintaining classification accuracy.

[0060] 4.6 Timing and Turbidity Adaptive Control In an optional embodiment, the analysis and processing module is also used to dynamically adjust the turn-on timing and duty cycle of the light-emitting unit according to the turbidity signal: when the turbidity is higher than a preset threshold (e.g., 50 NTU), the 430 nm visible light is turned on first for background correction, and then the ultraviolet light source unit and the infrared light source unit are turned on in sequence, and the light source integration time is shortened to 50% of the normal value to avoid signal saturation; when the turbidity is lower than the preset threshold, the default timing and integration time are restored.

[0061] 4.7 Data Storage and Remote Communication In an optional embodiment, the analysis and processing module integrates a data storage unit and a remote communication unit. The data storage unit uses an industrial-grade SD card, configured to continuously store no fewer than 100,000 data points, including detection time, oil type, concentration value, and raw signal data. The remote communication unit supports at least one of 4G, 5G, or LoRa wireless communication protocols, configured to transmit detection results to a host computer monitoring platform in real time, enabling remote data viewing, anomaly alarms, and historical data tracing, thus meeting the intelligent management needs of environmental monitoring.

[0062] Experiments have verified that, using the device and method provided in this embodiment, the concentration measurement error can be controlled within ±5% in the oil concentration range of 0.1 mg / L to 100 mg / L.

[0063] 5. Self-cleaning unit The self-cleaning unit is located outside the optical window of the detection cavity and is used to remove contaminants adhering to the optical window. The self-cleaning unit includes a piezoelectric ceramic plate and a polytetrafluoroethylene (PTFE) brush. The vibration frequency of the piezoelectric ceramic plate is 40kHz to 100kHz, preferably 40kHz. The self-cleaning unit can employ high-pressure water spray, ultrasonic cleaning, or scraper cleaning methods, which can be selected based on the degree of contamination in the detection environment.

[0064] 6. Protective outer casing The protective housing consists of a top cover and a base, made of 316L stainless steel with an anti-corrosion coating. It houses and protects the internal optical modules, sample flow and reaction modules, and analytical processing modules, effectively resisting water impact, corrosion, and impurity adhesion, and is suitable for long-term underwater operation. A leveling interface 1 is located on the top of the protective housing cover, used to connect to an external support and achieve horizontal leveling of the device.

[0065] like Figure 2 As shown, this embodiment of the invention provides a method for in-situ detection of oil in water based on three light sources, applied to the above-mentioned device. The method includes the following steps: S1: Fix the detection device in the water body to be tested through the top mounting leveling interface 1, so that the sample flow and reaction module is connected to the water body to be tested, so that the water body to be tested flows into the detection chamber as the water sample to be tested. S2: Control the light-emitting units of the optical module to turn on alternately according to a preset time sequence, and emit ultraviolet light, visible light and infrared light to the water sample to be tested in the detection cavity in sequence; S3: The detection unit receives light after it has been affected by oily substances in the water sample being tested, and transmits the converted electrical signal to the analysis and processing module. S4: The analysis and processing module corrects the baseline drift of the ultraviolet fluorescence signal and the infrared absorption signal in real time based on the received electrical signal and analyzes to obtain information on the type and concentration of oil in the water.

[0066] In an optional embodiment of step S2, ultraviolet light, visible light, and infrared light are sequentially emitted into the water sample to be tested in the detection chamber, including: S21: Turn on the ultraviolet light source unit and emit ultraviolet light of the first wavelength into the water sample to be tested in the detection chamber to excite the oily substances in the water sample to produce fluorescence. The first wavelength is configured to be a wavelength that easily excites the oily substances in the water to produce fluorescence. S22: After turning off the ultraviolet light source unit, turn on the visible light source unit to emit visible light of the second wavelength into the water sample to be tested in the detection chamber, so as to measure the absorbance of the water sample to the second wavelength of visible light. The second wavelength is configured to be easily absorbed by oil in the water. S23: After turning off the visible light source unit, turn on the infrared light source unit and emit infrared light of the third wavelength into the water sample to be tested in the detection cavity to measure the absorbance of the water sample to the third wavelength infrared light. The third wavelength is configured to correspond to the wavelength of the characteristic absorption peak of oil in the water.

[0067] Preferably, in step S2, before turning on the light-emitting unit, the optical path is adjusted. At least one of the pitch angle, horizontal position, and vertical position of the ultraviolet light source unit, the visible light source unit, and the infrared light source unit is adjusted by the adjustment device so that the optical paths of each wavelength light pass through the center of the optical path channel of the detection cavity.

[0068] In addition, before step S2, a self-cleaning pretreatment step may be included: controlling the self-cleaning unit to start, pre-cleaning the optical window, and ensuring that the optical path is unobstructed.

[0069] In an optional embodiment of step S4, the analysis and processing module analyzes the received electrical signal to obtain information on the type and concentration of oil in the water, including: S41: The analysis and processing module calls the pre-stored spectral database, and compares the received fluorescence spectral features, visible light absorbance and infrared absorption peak features with the standard spectral features of different oils in the database to identify the type of oil. S42: Based on the identified oil type, retrieve the pre-calibrated concentration-signal intensity standard curve of the corresponding oil type, calculate the initial concentration value based on ultraviolet fluorescence intensity, visible light absorbance and infrared characteristic absorption peak intensity, and then fuse them through a weighted average algorithm to obtain the final oil concentration value.

[0070] In an optional embodiment, the above method further includes: S5: During the continuous operation of the detection device, the self-cleaning unit is activated once at preset intervals to remove contaminants attached to the optical window of the detection cavity.

[0071] like Figure 3 As shown, the present invention will illustrate the above method through the following examples: Step 1: Fix the detection device at the specified depth of the water body to be tested through the top mounting leveling interface 1, so that the inlet and outlet of the detection chamber are naturally connected to the water body to be tested, and the device deployment is completed; Step 2: Adjust the pitch angle and horizontal position of the ultraviolet light source unit, visible light source unit, and infrared light source unit respectively using the adjustment device, so that the optical paths of each wavelength light pass through the center of the optical path channel of the detection cavity, and complete the optical path calibration; Step 3: Control the self-cleaning unit to start, using 40kHz frequency vibration for 30 seconds to clean the optical window; then control the light-emitting unit to alternately turn on according to a preset sequence, emitting 254nm ultraviolet light, 430nm visible light, and 2930nm light in sequence. -1 The infrared light is applied to the water sample being tested, with an integration time of 100ms for each light source and an interval time of 50ms. Step 4: The detection unit receives the light after it has passed through the water sample, converts it into an electrical signal, and transmits it to the analysis and processing module; Step 5: The analysis and processing module corrects the baseline drift of the ultraviolet fluorescence signal and the infrared absorption signal in real time based on the 430nm visible light absorbance. Then, it calls the pre-stored spectral database to calculate the ratio of ultraviolet fluorescence intensity to infrared absorption intensity R1 and the ratio of visible light absorbance to infrared absorption intensity R2. Substitute R1 and R2 into the pre-stored classification threshold matrix to determine the type of oil and calculate the concentration of the corresponding oil based on the pre-calibrated concentration curve. Step 6: Control the self-cleaning unit to start. The piezoelectric ceramic sheet vibrates at a frequency of 40kHz for 30 seconds, while the polytetrafluoroethylene scraper reciprocates 3 times to remove contaminants attached to the optical window of the detection cavity, completing a single detection cycle.

[0072] In practice, the duty cycle of the preset timing sequence can be adaptively optimized based on historical detection data: when the analysis and processing module detects mineral oil three times consecutively, it automatically switches between 254nm ultraviolet light and 2930cm² light. -1 The integration time for infrared light is extended to 150ms, and the integration time for 430nm visible light is shortened to 80ms. When animal or vegetable oil is detected three times consecutively, the integration time for 430nm visible light is automatically extended to 150ms, and the integration time for 254nm ultraviolet light and 2930cm² light is shortened. -1 The integration time of infrared light is shortened to 80ms, which reduces the power consumption of the device and extends the battery life while ensuring recognition accuracy.

[0073] This invention also provides the application of the above-mentioned device in distinguishing between mineral oil and animal and vegetable oils. This application utilizes real-time visible light measurement of the background absorbance of a water sample to correct for turbidity interference, and combines this with the synergistic analysis of ultraviolet light-excited fluorescence signals and infrared light absorption signals to achieve the classification and identification of mineral oil and animal and vegetable oils.

[0074] The specific identification criteria are as follows: mineral oil contains a large amount of aromatic hydrocarbon compounds, which will produce a strong fluorescence signal under 254nm ultraviolet light excitation, and its CH bonds are located at 2930cm. -1There is a significant infrared absorption peak at [location missing], therefore, the identification basis for mineral oil is the fluorescence signal generated under ultraviolet light excitation and the presence of an infrared absorption peak at [location missing]; the main component of animal and vegetable oils is triglycerides, which do not contain aromatic hydrocarbons, and their ultraviolet fluorescence signal is weak, but the unsaturated fatty acids in their molecules exhibit specific absorption in the 430nm visible light band, and this absorbance is similar to that at 2930cm[location missing]. -1 The ratio of infrared light absorbance to a preset threshold (e.g., 1.2) is used as the basis for identifying animal and vegetable oils. Through the coordinated analysis of three-band signals, misjudgments caused by single-band detection can be effectively avoided, enabling accurate differentiation between mineral oils and animal and vegetable oils.

[0075] The apparatus and method provided in the embodiments of the present invention achieve the following technical effects compared with the prior art: 1. Significantly improves detection accuracy and stability in complex aquatic environments. This invention innovatively uses visible light absorbance as a real-time turbidity correction benchmark and employs a three-band collaborative mechanism to dynamically compensate for baseline drift in ultraviolet fluorescence and infrared absorption signals. Compared to existing anti-interference methods that rely solely on differential algorithms or offline modeling, this solution can physically eliminate background noise caused by high turbidity, color variations, and suspended matter scattering. This ensures that the detection signal does not saturate or become distorted during long-term operation in harsh conditions such as industrial circulating water and nearshore marine environments, significantly improving the reliability and repeatability of in-situ monitoring data.

[0076] 2. To achieve accurate differentiation between mineral oil and animal / vegetable oils, avoiding misjudgment and missed detection. By simultaneously acquiring three-dimensional optical information—UV-excited fluorescence, visible light specific absorption, and infrared CH bond characteristic absorption—and constructing a multi-dimensional signal ratio classification model, this approach effectively overcomes the technical bottleneck of a single optical mode being unable to simultaneously identify aromatic and non-aromatic hydrocarbons. This multi-parameter fusion strategy can not only accurately identify mineral oils containing aromatic hydrocarbons but also reliably identify animal and vegetable oils that do not exhibit fluorescence but possess specific visible-infrared absorption ratio characteristics. This significantly reduces the risk of false positives or false negatives due to the complexity of oil composition, meeting the refined requirements of environmental regulation and process safety for oil traceability.

[0077] 3. Enhance the environmental adaptability and long-term maintenance-free capability of the device. This composite self-cleaning unit integrates piezoelectric ceramic ultrasonic vibration with PTFE mechanical scraping, along with a chemically inert fluorocarbon coated curved flow channel design. It inhibits biofilm adhesion, sediment deposition, and sample residue from both active cleaning and passive antifouling perspectives. Combined with a three-dimensional optical path fine-tuning structure, on-site optical path calibration can be completed without disassembling the device. This overcomes the engineering pain points of traditional equipment, such as frequent factory calibrations and easy window contamination leading to failure, truly achieving long-term unattended stable operation in enclosed spaces like underwater or pipelines.

[0078] 4. Optimize detection efficiency and energy consumption management to adapt to in-situ real-time monitoring scenarios. Employing a time-sequential excitation and adaptive duty cycle control strategy, this approach avoids spectral crosstalk when multiple light sources operate simultaneously and dynamically adjusts the integration time and light source priority based on real-time turbidity feedback. While ensuring recognition accuracy, it intelligently reduces invalid sampling power consumption during low-interference periods, extending the battery life of battery-powered devices. Simultaneously, the time-division acquisition mechanism shortens the single complete detection cycle to the second level, meeting the dual timeliness requirements of emergency response to sudden leaks and continuous online monitoring.

[0079] 5. It can achieve mixed oil analysis and intelligent monitoring capabilities. By incorporating built-in independent component analysis and multi-peak matching algorithms, this device can decompose characteristic peaks in mixed oil samples, separating the signal contribution values ​​of each oil type and enabling simultaneous detection of multiple oils. Combined with industrial-grade data storage and remote communication capabilities, it supports long-term recording and real-time uploading of detection data, meeting the needs of intelligent environmental monitoring management. Experimental verification shows that within a concentration range of 0.1 mg / L to 100 mg / L, the measurement error can be controlled within ±5%, demonstrating significant engineering practical value.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for in-situ oil detection in water based on three light sources, characterized in that, include: The optical module is used to generate detection light and receive optical signals after being acted upon by the water sample being tested, including a light-emitting unit and a detection unit; The sample flow and reaction module is used to guide the flow of the water sample to be tested and provide a space for the interaction between light and the sample. It includes a detection chamber and a sealing cover (3). The detection chamber is used to form a defined optical path channel and sample flow channel. The sealing cover (3) is used to seal the detection chamber to form a closed optical reaction environment. Mechanical structure and integrated module, used to support, fix and integrate various functional modules, including main support structure (4) and top mounting leveling interface (1), the main support structure (4) is used to fix the optical module and the sample flow and reaction module, and the top mounting leveling interface (1) is used to connect the entire device to the external support; The analysis and processing module is electrically connected to the optical module and is used to correct the baseline drift of the ultraviolet fluorescence signal and the infrared absorption signal in real time based on the visible light absorbance according to the electrical signal converted by the detection unit, and to analyze and obtain information on the type and concentration of oil in the water. The light-emitting unit includes an ultraviolet light source unit, a visible light source unit, and an infrared light source unit, which are used to emit ultraviolet light, visible light, and infrared light to the water sample being tested in the detection chamber, respectively. The detection unit is used to receive the fluorescence signal generated by the oily substances in the water sample being tested in the detection chamber excited by the ultraviolet light, the transmitted light signal after the visible light is absorbed by the water sample being tested in the detection chamber, and the transmitted light signal after the infrared light is absorbed by the water sample being tested in the detection chamber, and convert them into electrical signals.

2. The in-situ oil-water detection device based on three light sources according to claim 1, characterized in that, The analysis and processing module calls the pre-stored spectral database based on the electrical signal converted by the detection unit, and compares the received fluorescence spectral features, visible light absorbance and infrared absorption peak features with the standard spectral features of different oils in the database to identify the type of oil. Based on the fluorescence intensity, visible light absorbance and infrared light absorption intensity, combined with the pre-calibrated concentration curve, the concentration of the corresponding oil is calculated.

3. The in-situ oil-water detection device based on three light sources according to claim 1 or 2, characterized in that, The ultraviolet light source unit, the visible light source unit, and the infrared light source unit are turned on alternately according to a preset timing sequence; The analysis and processing module is also used to extract the fluorescence signal, visible light absorption signal and infrared absorption signal of the corresponding time segment according to the electrical signals collected by the detection unit in different time segments, as the basic data for the fitting comparison and concentration calculation.

4. The in-situ oil-water detection device based on three light sources according to claim 1, characterized in that, The detection unit includes a photodiode mounting plate, a photodetector, and a converging lens. The photodiode mounting plate is used to fix the photodetector. The converging lens is disposed in the optical path between the detection cavity and the photodetector, and is used to converge the light after the water sample in the detection cavity is reacted to onto the photosensitive surface of the photodetector. The focal length of the converging lens is matched with the optical path length of the detection cavity, so that the light is accurately converged to the center of the photosensitive surface of the photodetector. The photodiode mounting plate is also provided with a light shield, which is sleeved on the outer periphery of the detection unit to shield the interference of ambient stray light on the detection signal.

5. The in-situ oil-water detection device based on three light sources according to claim 1, characterized in that, The ultraviolet light source unit, the visible light source unit, and the infrared light source unit each have a corresponding adjustment device. The adjustment device is installed on the main support structure (4) and is used to adjust at least one of the pitch angle, horizontal position, and vertical position of each light source unit so that the detection light emitted by each light source unit passes through the center of the optical path channel of the detection cavity.

6. The in-situ oil-water detection device based on three light sources according to claim 1, characterized in that, The main support structure (4) is an integrated metal frame with a positioning reference surface inside. The optical module and the sample flow and reaction module are aligned and installed through the positioning reference surface. The device also includes a protective shell, which is used to house the optical module, the sample flow and reaction module and the analysis and processing module.

7. A method for in-situ detection of oil in water based on three light sources, characterized in that, The method applied to the in-situ oil-water detection device based on three light sources according to any one of claims 1-6, the method comprising: The detection device is fixed in the water body to be tested through the top mounting leveling interface (1), so that the sample flow and reaction module is connected to the water body to be tested, so that the water body to be tested flows into the detection chamber as the water sample to be tested; The light-emitting units of the optical module are controlled to turn on alternately according to a preset time sequence, emitting ultraviolet light, visible light and infrared light to the water sample to be tested in the detection cavity in sequence; The detection unit receives light after it has been affected by oily substances in the water sample being tested, and transmits the converted electrical signal to the analysis and processing module. The analysis and processing module corrects the baseline drift of the ultraviolet fluorescence signal and the infrared absorption signal in real time based on the received electrical signal and analyzes to obtain information on the type and concentration of oil in the water.

8. The method for in-situ oil detection in water based on three light sources according to claim 7, characterized in that, The test involves sequentially emitting ultraviolet light, visible light, and infrared light into the water sample within the detection chamber, including: The ultraviolet light source unit is turned on to emit ultraviolet light of the first wavelength into the water sample to be tested in the detection chamber, so as to excite the oily substances in the water sample to produce fluorescence. The first wavelength is configured to be a wavelength that easily excites the oily substances in the water to produce fluorescence. After turning off the ultraviolet light source unit, the visible light source unit is turned on to emit visible light of a second wavelength into the water sample to be tested in the detection chamber, so as to measure the absorbance of the water sample to the second wavelength of visible light. The second wavelength is configured to be easily absorbed by oil in the water. After the visible light source unit is turned off, the infrared light source unit is turned on to emit infrared light of a third wavelength into the water sample to be tested in the detection chamber, so as to measure the absorbance of the water sample to the third wavelength infrared light. The third wavelength is configured to correspond to the wavelength of the characteristic absorption peak of oil in the water.

9. The method for in-situ oil detection in water based on three light sources according to claim 7, characterized in that, The analysis and processing module analyzes the received electrical signal to obtain information on the type and concentration of oil in the water, including: The analysis and processing module calls the pre-stored spectral database, and compares the received fluorescence spectral features, visible light absorbance and infrared absorption peak features with the standard spectral features of different oils in the database to identify the type of oil. Based on the identified oil type, the pre-calibrated concentration-signal intensity standard curve of the corresponding oil type is retrieved. The initial concentration value is calculated based on the ultraviolet fluorescence intensity, visible light absorbance and infrared characteristic absorption peak intensity, respectively. The final oil concentration value is then obtained by fusion through a weighted average algorithm.

10. The application of a three-light source-based in-situ oil-water detection device, characterized in that, To distinguish between mineral oil and animal / vegetable oil in the tested water, the device utilizes a three-source in-situ oil detection apparatus as described in any one of claims 1-6 to measure the background absorbance of the water sample in real time using visible light to correct for turbidity interference. Combined with the synergistic analysis of ultraviolet-excited fluorescence signals and infrared absorption signals, the device achieves classification and identification of mineral oil and animal / vegetable oil. The identification criteria for mineral oil are that it generates a fluorescence signal under ultraviolet excitation and has an infrared absorption peak at the infrared light source; the identification criteria for animal / vegetable oil are that the ratio of the absorbance of visible light to the absorbance of infrared light is greater than a preset threshold.

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