Online measurement method and device for petroleum in water

Abstract

The invention belongs to the field of water pollution monitoring, and particularly relates to an online measurement method for petroleum in water, which comprises the following steps: step 1, water sampling: a trigger unit transmits the detected fluorescence intensity of the water surface to a control unit, and the control unit controls the water sampling frequency of a sampling pump in the water sampling unit according to the fluorescence intensity detected by the trigger unit; step 2, extraction: sending the water sample extracted by the sampling pump into a sample storage container, and extracting oil substances into an extraction reagent; step 3, separation: conveying into a separation container through a conveying pump; and 4, measuring, namely feeding the extraction reagent into a cuvette of a measuring unit for measuring the content of the oil substances. According to the design, a method of combining water surface early warning measurement and underwater quantitative measurement is adopted, pollution occurrence can be judged in time, and the content of underwater oil substances can be measured online, so that pollution sources can be conveniently fed back and controlled in time, and the timeliness of online water environment monitoring is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of water pollution monitoring, and specifically relates to an online measurement method and device for petroleum in water. Background Technology

[0002] Petroleum pollution is the most frequent type of pollution in aquatic environments, making online measurement of petroleum pollution crucial. However, currently there are no online measurement devices or methods for petroleum-related water pollution. For rivers, lakes, and seas, existing methods for detecting this type of pollution involve personnel traveling to the site of oil pollution, collecting underwater water samples, extracting them with organic reagents, and then measuring them using infrared, ultraviolet, or fluorescence methods. This approach results in very low timeliness, often failing to provide timely feedback and control the source of pollution.

[0003] Specifically, petroleum hydrocarbons are not uniformly distributed in water. Current standard measurement methods involve sampling water at a depth of 0.5 meters, while most oily substances float on the surface. This makes it difficult to determine the time, location, and degree of pollution in the subsurface, increasing the difficulty of on-site water sampling and compromising the accuracy of measurement results. Furthermore, the detection process requires the use of organic reagents to extract the oily substances from the water, and then separating the extracted organic reagents before sending them to the measuring equipment. Without human intervention, steps such as sampling and cleaning are difficult to implement. For example, determining the sampling time and frequency, cleaning the measuring equipment, and replenishing the consumed organic reagents are all problematic. Summary of the Invention

[0004] To address the above problems, this invention provides an online measurement method and device for petroleum in water.

[0005] An online measurement method for petroleum-related substances in water, characterized by the following steps: Step 1, water sampling: A trigger unit transmits the detected fluorescence intensity of the water surface to a control unit, which controls the sampling frequency of the sampling pump in the water sampling unit based on the fluorescence intensity detected by the trigger unit; Step 2, extraction: The water sample extracted by the sampling pump is sent to a sample storage container, and an extraction reagent is drawn into the extraction reagent storage tank by an injection pump through a multi-port valve and injected into the sample storage container. The mixer is turned on to mix the water sample and extraction reagent in the sample storage container, extracting the oily substances into the extraction reagent; Step 3, separation: The mixture of water sample and extraction reagent in the sample storage container is drawn into a separation container by a transfer pump and sent to a separation container; Step 4, measurement: The extraction reagent is drawn into the separation container by an injection pump through a multi-port valve and sent to a cuvette in the measurement unit for measuring the oily substance content.

[0006] Furthermore, in step one, when the detected fluorescence intensity does not exceed the set fluorescence threshold, the control unit enters the timed detection mode and controls the sampling pump of the water intake unit to extract water samples at regular intervals through the water intake pipeline; when the detected fluorescence intensity exceeds the set fluorescence threshold, the control unit enters the high-frequency detection mode and controls the sampling pump of the water intake unit to extract water samples at high frequency through the water intake pipeline.

[0007] Furthermore, in step four, when the oil content measured by the measuring unit is lower than the set detection threshold, the injection pump sends the extraction reagent in the cuvette to the extraction reagent storage tank through the multi-port valve; when the oil content measured by the measuring unit is higher than the set detection threshold, the injection pump sends the extraction reagent in the cuvette to the waste liquid storage tank through the multi-port valve.

[0008] Furthermore, when the oil content measured by the measuring unit is lower than the set detection threshold, and the extraction reagent in the cuvette is delivered to the extraction reagent storage tank by the injection pump through the multi-port valve, the measuring unit performs a zeroing operation based on the oil content of the extraction reagent in the extraction reagent storage tank.

[0009] Furthermore, the process includes step five, cleaning. After the measuring unit completes the measurement of oil content, and the oil content measured by the measuring unit is higher than the set detection threshold, the sample storage container, separation container, and cuvette are cleaned using the extraction reagent in the reagent storage tank. The control unit determines the number of times the extraction reagent is cleaned based on the oil content measured by the measuring unit. In the next oil content measurement, the extraction reagent that has already extracted oil from the separation container is first extracted and used to clean the cuvette, and then the extraction reagent that has already extracted oil from the separation container is extracted again to measure the oil content.

[0010] An online measurement device for petroleum-based substances in water includes a triggering unit, a water sampling unit, an extraction unit, a separation unit, a measurement unit, and a control unit. The triggering unit includes an oil sensor for qualitatively detecting oily substances on the water surface using ultraviolet fluorescence. The water sampling unit includes an underwater sampling pipe connected to a sampling pump. The extraction unit includes a sample storage container connected to the sampling pump, used to receive extracted underwater water samples, and a mixer is located on one side of the sample storage container. The separation unit includes a separation container connected to the sample storage container via a transfer pump. The measurement unit is connected to the separation container via a multi-port valve, used to receive and measure the extracted oily substances from the separation container using extraction reagent. The multi-port valve connects the sample storage container, a syringe pump, an extraction reagent storage tank, and a waste liquid storage tank. The control unit receives the water surface fluorescence intensity collected by the oil sensor and controls the connection between the sampling pump, mixer, transfer pump, multi-port valve, syringe pump, and measurement unit.

[0011] Furthermore, the separation container uses vertically arranged separation tubes, and the diameter of the separation tubes is smaller than the diameter of the sample storage container.

[0012] Furthermore, the measuring unit employs an optical measuring instrument, which is connected to the control unit, and the multi-way valve is connected to a cuvette in the optical measuring instrument used to receive the extraction reagent.

[0013] Furthermore, the measuring unit is an ultraviolet spectrophotometer or a fluorescence spectrophotometer, the extraction reagent is n-hexane reagent with a specific gravity less than water, and the upper part of the separation container is connected to a multi-port valve through a liquid extraction tube.

[0014] Furthermore, the measuring unit is an infrared photometer, the extraction reagent is tetrachloroethylene reagent with a specific gravity greater than water, and the lower part of the separation container is connected to a multi-way valve through a liquid extraction tube.

[0015] The beneficial effects of this invention are: (1) It can achieve fully automated unmanned operation measurement. From qualitative early warning to quantitative sampling of representative water samples, addition of extraction reagents, mixing and extraction, separation, measurement, recovery, and cleaning, it can all be completed automatically, and reliable data can be obtained in real time to monitor the pollution status of water quality. (2) By cooperating with the triggering unit, water intake unit, extraction unit, separation unit, measurement unit and control unit, the problem of online oil pollution monitoring is solved and the timeliness is guaranteed. The method of combining water surface early warning measurement and underwater quantitative measurement is of great significance for online water environment monitoring. (3) The early warning measurement of the trigger unit does not require extraction reagents, while the control unit has two modes: timed detection and high-frequency detection. The long-term timed detection requires a large amount of extraction reagents. Reagent recovery can effectively extend the online monitoring time of the online measurement device, save reagents in the absence of oil pollution in the water environment, reduce reagent consumption and replenishment frequency, reduce reagent input costs, and effectively ensure the measurement accuracy of oil content in water samples. The short-term high-frequency detection ensures timely measurement of oil pollution in the water environment. (4) The signal transmission module connected to the control unit can provide an early warning function and provide timely feedback on the measurement results of online water environment monitoring.

[0016] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flow path diagram of the measurement unit of the present invention using ultraviolet photometry is shown; Figure 2 A partial structural schematic diagram of the measurement unit of the present invention using ultraviolet photometry is shown; Figure 3 A schematic diagram of the flow path of the measurement unit of the present invention using infrared photometry is shown; Figure 4 A partial structural schematic diagram of the measurement unit of the present invention using infrared photometry is shown; Figure 5 A schematic diagram of the process of the present invention is shown.

[0019] In the diagram: 1. Sample storage container; 2. Paddle stirrer; 3. Separation container; 4. Multi-way valve; 5. Injection pump; 6. Ultraviolet spectrophotometer; 7. Infrared spectrophotometer; 8. Extraction reagent storage tank; 9. Waste liquid storage tank; 10. Sampling pump; 11. Transfer pump; 12. Trigger unit; 13. Water intake pipeline; 14. Control unit. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 like Figure 1-5As shown, an online measurement method for petroleum in water includes the following steps: Step 1: Water sampling. The trigger unit 12 transmits the detected fluorescence intensity of the water surface to the control unit 14. The control unit 14 controls the water sampling frequency of the water sampling unit based on the fluorescence intensity detected by the trigger unit 12. Step 2: Extraction. The water sample extracted by the sampling pump 10 is sent to the sample storage container 1. The injection pump 5 extracts the extraction reagent into the extraction reagent storage tank 8 through the multi-port valve 4 and injects the extraction reagent into the sample storage container 1. The mixer is turned on to mix the water sample and the extraction reagent in the sample storage container 1, and the oil substances are extracted into the extraction reagent. Step 3: Separation. The mixture of water sample and extraction reagent is sent to the separation container 3 by the transfer pump 11. The water sample and extraction reagent are separated into layers in the separation container 3 due to their different specific gravities. Step 4: Measurement. The injection pump 5 extracts the extraction reagent into the separation container 3 through the multi-port valve 4 and sends the extraction reagent to the cuvette of the measurement unit for oil content measurement. This method automates the operation of online measurement devices, obtains reliable data in real time, and monitors the pollution status of water.

[0022] In step one, the trigger unit 12 employs an oil-in-water sensor that qualitatively detects oily substances on the water surface using ultraviolet fluorescence. Ultraviolet fluorescence utilizes the characteristic fluorescence emitted by the aromatic hydrocarbon / conjugated double bond structure in petroleum products under ultraviolet light excitation. The fluorescence intensity is proportional to the oil concentration within a certain range, thus allowing for quantitative detection. The oil-in-water sensor irradiates the water surface with a built-in ultraviolet light source. The aromatic hydrocarbon / conjugated double bonds in the oil absorb energy, causing electrons to transition from the ground state to an excited state. The excited-state electrons quickly return to the ground state, releasing longer-wavelength fluorescence. The fluorescence signal is then received by the built-in fluorescence detector of the oil-in-water sensor and fed back to the control unit for conversion into oil concentration. When the detected fluorescence intensity does not exceed the set fluorescence threshold, the control unit 14 enters a timed detection mode and controls the sampling pump 10 of the water intake unit to extract water samples at regular intervals through the water intake pipeline 13. When the detected fluorescence intensity exceeds the set fluorescence threshold, the control unit 14 enters a high-frequency detection mode and controls the sampling pump 10 of the water intake unit to extract water samples at high frequency through the water intake pipeline 13. Specifically, in the timed detection mode, the control unit 14 controls the water sampling unit to extract water samples according to a set first water sampling frequency; in the high-frequency detection mode, the control unit 14 controls the water sampling unit to extract water samples according to a set second water sampling frequency; and the second water sampling frequency is greater than the first water sampling frequency, for example: the first water sampling frequency can be 1 time / day, and the second water sampling frequency can be 24 times / day. After the trigger unit 12 detects oil pollution on the water surface, it feeds back to the control unit 14, causing the online measuring device to switch from the timed detection mode to the high-frequency detection mode, and the sampling pump 10 performs high-frequency water sampling until manual intervention.

[0023] In step two, after the water sample and extraction reagent are mixed, they will separate into layers in the sample storage container 1 due to their different specific gravities. However, because the diameter of the sample storage container 1 is relatively large, the liquid layer formed inside is relatively thin, which is not conducive to directly extracting the extraction reagent for measurement. Therefore, in step three, during the pumping process of the transfer pump 11 sending the mixture of water sample and extraction reagent from the bottom of the sample storage container 1 to the separation container 3, when the extraction reagent is less dense than water, the control unit 14 controls the solenoid valve at the bottom of the separation container 3 to be in the open state at the initial stage of the pumping process and to close after a period of time. When the solenoid valve is in the open state, the mixture containing a large proportion of water sample is directly discharged into the separation container 3. After the solenoid valve is in the closed state, the separation container 3 can retain the mixture containing a large proportion of extraction reagent. The control unit 14 controls the opening time of the solenoid valve during the pumping process of the transfer pump 11 based on the amount of water sample extracted, the amount of extraction reagent added, and the flow rate of the transfer pump 11. This facilitates the extraction of sufficient extraction reagent from separation container 3 for oil content measurement. After the measurement unit completes the oil content measurement, the residual liquid in separation container 3 is discharged into waste liquid storage tank 9 through the residual liquid discharge port at the bottom of separation container 3. Alternatively, when an extraction reagent with a specific gravity greater than water is used, the mixture of water sample and extraction reagent can be directly pumped from the bottom of sample storage container 1 to separation container 3 via transfer pump 11, allowing direct extraction of the mixture containing a higher proportion of extraction reagent. After the measurement unit completes the oil content measurement, the solenoid valve at the bottom of separation container is opened, and in conjunction with the operation of the transfer pump, the residual liquid in sample storage container 1 and separation container 3 is discharged into waste liquid storage tank 9.

[0024] In step four, when the oil content measured by the measuring unit is lower than the set detection threshold, the injection pump 5 delivers the extraction reagent from the cuvette to the extraction reagent storage tank 8 via the multi-way valve 4; when the oil content measured by the measuring unit is higher than the set detection threshold, the injection pump 5 delivers the extraction reagent from the cuvette to the waste liquid storage tank 9 via the multi-way valve 4. When the oil content measured by the measuring unit is lower than the set detection threshold, the extraction reagent in the cuvette can be recovered. In most cases, oil contamination of the aquatic environment is rare. This design reduces the loss of extraction reagent due to periodic testing, effectively extends the online monitoring time of the online measuring device, reduces the frequency of extraction reagent loss and replenishment, and lowers the cost of extraction reagent input. Specifically, the detection threshold can be 0.01 mg / L. Furthermore, after the measuring unit completes the measurement of the oil content using the extraction reagent, the residual water sample in the separation container 3 is discharged into the waste liquid storage tank 9 through the residual liquid discharge port at the bottom of the separation container 3.

[0025] When the oil content measured by the measuring unit is lower than the set detection threshold, and after the injection pump 5 delivers the extraction reagent from the cuvette to the extraction reagent storage tank 8 through the multi-way valve 4, the measuring unit performs a zeroing operation based on the oil content of the extraction reagent in the extraction reagent storage tank 8. The zeroing operation involves the injection pump 5 drawing extraction reagent into the extraction reagent storage tank 8 through the multi-way valve 4 and delivering the extraction reagent to the cuvette of the measuring unit for oil content measurement to obtain an additional value of oil content. The measuring unit uses the negative additional value of oil content as zero. This design avoids the impact of oil accumulation caused by long-term timed detection, thereby ensuring the accuracy of the measurement results.

[0026] The measurement method also includes step five, cleaning. After the measuring unit completes the measurement of oil content, and the measured oil content is higher than the set detection threshold, the sample storage container 1, separation container 3, and cuvette are cleaned using the extraction reagent in the reagent storage tank. The entire cleaning process is controlled by the control unit 14, which controls the injection pump 5 to draw extraction reagent into the extraction reagent storage tank 8 through the multi-way valve 4 and injects the extraction reagent into the sample storage container 1 where the water sample has been extracted. The extraction reagent is then transferred to the separation container 3 by the delivery pump 11, and then the injection pump 5 draws extraction reagent into the separation container 3 through the multi-way valve 4 and delivers the extraction reagent to the measuring unit. The cuvette undergoes a complete cleaning process. After cleaning, the extraction reagent in the cuvette is drawn back by the syringe pump 5 through the multi-port valve 4 and sent to the waste liquid storage tank 9. The control unit 14 determines the number of cleaning cycles for the extraction reagent based on the oil content measured by the measuring unit. Before the next oil content measurement, the extraction reagent that has already extracted the oil from the separation container 3 is first drawn back into the cuvette for cleaning. The extraction reagent that was previously added to the cuvette is then drawn back into the cuvette by the syringe pump 5 through the multi-port valve 4 and sent to the waste liquid storage tank 9. The extraction reagent that has already extracted the oil from the separation container 3 is then drawn back into the separation container 3 again for oil content measurement. This cleaning process ensures the purity of the sample storage container 1, the separation container 3, and the cuvette, preventing any impact on the oil content measurement results.

[0027] Specifically, when the oil content measured by the current measurement unit is higher than the detection threshold but lower than the first content threshold, the sample storage container 1, separation container 3, and cuvette are thoroughly cleaned using the extraction reagent in the reagent storage tank. In the next oil content measurement, the cuvette is first cleaned separately using the extraction reagent already extracted from the oil in separation container 3, and then the oil content is measured. When the oil content measured by the current measurement unit is higher than the first content threshold but lower than the second content threshold, the sample storage container 1, separation container 3, and cuvette are thoroughly cleaned using the extraction reagent in the reagent storage tank. The cuvettes undergo two full-process cleanings. Before each subsequent oil content measurement, the cuvettes are cleaned separately using the extraction reagent already extracted from the oil in separation container 3, followed by the oil content measurement. If the oil content measured in the previous measurement unit exceeds the second content threshold, the sample storage container 1, separation container 3, and cuvettes are cleaned three times using the extraction reagent in the reagent storage tank. Before each subsequent oil content measurement, the cuvettes are cleaned separately using the extraction reagent already extracted from the oil in separation container 3, followed by the oil content measurement. The first content threshold can be 1 mg / L, and the second content threshold can be 10 mg / L.

[0028] Example 2 like Figure 1-2 As shown, an online measurement method for petroleum in water includes the following steps: Step 1: Water sampling. The oil sensor in the water transmits the fluorescence intensity detected on the water surface to the control unit 14. When the detected fluorescence intensity exceeds the set fluorescence threshold, the control unit 14 controls the sampling pump 10 of the water sampling unit to extract water samples through the water sampling pipeline 13; Step 2: Extraction. The water sample extracted by the sampling pump 10 is sent to the sample storage container 1. The injection pump 5 extracts n-hexane reagent with a specific gravity less than water into the extraction reagent storage tank 8 through the multi-port valve 4, and injects the n-hexane reagent into the water. In sample storage container 1, the paddle stirrer 2 is turned on to mix the water sample and n-hexane reagent, extracting oily substances into the n-hexane reagent. Step three, separation: the mixture of water sample and n-hexane reagent is sent to separation container 3 via transfer pump 11. The water sample and n-hexane reagent separate into layers within separation container 3 due to their different specific gravities. Step four, measurement: n-hexane reagent is extracted from the top of separation container 3 by syringe pump 5 through multi-port valve 4 and sent to the cuvette of ultraviolet spectrophotometer 6 or fluorophotometer for oil content measurement. This method is applicable to surface water, seawater, and other water samples with low oil content. It automates the operation of the online measurement device, using ultraviolet spectrophotometer 6 or fluorophotometer to detect the oil content in the n-hexane reagent, obtaining reliable data in real time, and monitoring water pollution status.

[0029] Example 3 like Figure 3-4 As shown, an online measurement method for petroleum in water includes the following steps: Step 1, water sampling: The oil sensor in the water transmits the detected fluorescence intensity of the water surface to the control unit 14. When the detected fluorescence intensity exceeds the set fluorescence threshold, the control unit 14 controls the sampling pump 10 of the water sampling unit to extract water samples through the water sampling pipeline 13; Step 2, extraction: The water sample extracted by the sampling pump 10 is sent to the sample storage container 1. The injection pump 5 extracts tetrachloroethylene reagent with a specific gravity greater than water into the extraction reagent storage tank 8 through the multi-port valve 4, and the tetrachloroethylene reagent is then... The water sample is injected into the sample storage container 1, and the paddle stirrer 2 is turned on to mix the water sample and tetrachloroethylene reagent in the sample storage container 1, extracting oily substances into the tetrachloroethylene reagent. Step three, separation: the mixture of water sample and tetrachloroethylene reagent is sent to the separation container 3 via the transfer pump 11. The water sample and tetrachloroethylene reagent separate into layers in the separation container 3 due to their different specific gravities. Step four, measurement: tetrachloroethylene reagent is extracted into the separation container 3 by the syringe pump 5 through the multi-port valve 4, and the tetrachloroethylene reagent is sent to the cuvette of the infrared spectrophotometer 7 for measuring the oily substance content. This method is applicable to sewage or industrial wastewater, achieving automated operation of the online measurement device. The infrared spectrophotometer 7 detects the oily substance content in the tetrachloroethylene reagent, obtaining reliable data in real time and monitoring the pollution status of the water.

[0030] Example 4 like Figure 1-5 As shown, an online measurement device for petroleum in water includes a triggering unit 12, a water intake unit, an extraction unit, a separation unit, a measurement unit, and a control unit 14. The triggering unit 12 includes an oil sensor for qualitative detection of oily substances on the water surface by ultraviolet fluorescence method. The water intake unit includes a water intake pipe 13 extending underwater, and the water intake pipe 13 is connected to a sampling pump 10. The extraction unit includes a sample storage container 1, which is connected to the sampling pump 10. The sample storage container 1 is used to receive the extracted underwater water sample, and a mixer is provided on one side of the sample storage container. The separation unit includes a separation container 3, which is connected to a sample storage container 1 via a transfer pump 11. A measurement unit is connected to the separation container 3 via a multi-port valve 4. The measurement unit receives and measures the extraction reagent containing extracted oil substances from the separation container 3. The multi-port valve 4 connects to the sample storage container 1, a syringe pump 5, an extraction reagent storage tank 8, and a waste liquid storage tank 9. A control unit 14 receives the water surface fluorescence intensity collected by an underwater oil sensor and is electrically connected to a sampling pump 10, a mixer, a transfer pump 11, a multi-port valve 4, a syringe pump 5, and the measurement unit. This design combines surface early warning measurement with underwater quantitative measurement, enabling timely detection of pollution occurrence and online measurement of underwater oil content. This facilitates timely feedback, control of pollution sources, and ensures the timeliness of online water environment monitoring.

[0031] The multi-way valve in the above-mentioned online measurement device can be replaced by a combination of multiple pipelines and multiple single-way valves.

[0032] To facilitate the setup of the trigger unit 12, the water intake pipe 13 includes a vertically arranged water intake pipe section. A movable sleeve is slidably connected to the water intake pipe section, and a float is connected to the movable sleeve. A mounting bracket for fixing the oil sensor in the water is provided on one side of the float, so that the oil sensor in the water is stably positioned above the water surface and detects oily substances on the water surface by ultraviolet fluorescence method. For collecting underwater water samples, the length of the water intake pipe section extending below the water surface is not less than 0.5 meters.

[0033] The sample storage container 1 is equipped with an overflow pipe to facilitate the discharge of excess water sample from the sample storage container 1. The overflow pipe is connected to a waste liquid storage tank 9.

[0034] The mixer is used to mix the water sample and extraction reagent in the sample storage container, and the mixer is connected to the control unit. Specifically, the mixer can be one of a stirrer or a shaker. Preferably, the mixer is a paddle stirrer 2, which includes a stirring motor. The output shaft of the stirring motor is connected to a stirring shaft, and stirring blades are provided on the stirring shaft. The stirring blades are located inside the sample storage container. The paddle stirrer 2 mixes the water sample and extraction reagent in the sample storage container 1, and extracts oily substances into the reagent.

[0035] The separation container 3 uses vertically arranged separation tubes, and the diameter of the separation tubes is smaller than that of the sample storage container 1. Because the diameter of the sample storage container 1 is larger, the liquid layer formed by the mixture of water sample and extraction reagent inside it is relatively thin, which is not conducive to direct extraction and measurement after separation by specific gravity. The mixture containing water sample and extraction reagent is pumped into the smaller diameter separation tube by the transfer pump 11, so that the liquid layer is raised. After the water sample and extraction reagent are separated by specific gravity, the extraction reagent for the extracted oil substances can be easily extracted. In addition, the bottom of the separation container 3 is equipped with a residual liquid discharge port, which is connected to the waste liquid storage tank 9. The residual liquid discharge port is equipped with a solenoid valve to facilitate the discharge of residual water sample and extraction reagent in the separation container 3. Specifically, the separation container 3 can use 25ml capacity separation tubes. Generally, the cuvettes in UV spectrophotometer 6, fluorophotometer, or infrared spectrophotometer 7 have a capacity of 3-4ml. Using 25ml capacity separation tubes can easily extract a sufficient amount of extraction reagent for subsequent measurement or cleaning.

[0036] The measuring unit employs an optical measuring instrument, which is connected to the control unit 14. The multi-way valve 4 is connected to the cuvette in the optical measuring instrument used to receive the extraction reagent. The optical measuring instrument is either a spectrometer or a photometer. Specifically, the measuring unit is a UV photometer 6 or a fluorescence photometer, and the extraction reagent is hexane, which has a specific gravity less than water. The upper part of the separation container 3 is connected to the multi-way valve 4 via a suction pipe. Alternatively, the measuring unit is an infrared photometer 7, and the extraction reagent is tetrachloroethylene, which has a specific gravity greater than water. The lower part of the separation container 3 is connected to the multi-way valve 4 via a suction pipe. Different measuring units and extraction reagents can be selected for different water samples. For example, for surface water with low oil content, a UV photometer 6 is used; for some seawater, a fluorescence photometer can also be used; and for sewage or industrial wastewater, an infrared photometer 7 is generally used.

[0037] The control unit 14 can be a programmable logic controller or a microprocessor. The oil sensor in the water, sampling pump 10, mixer, delivery pump 11, solenoid valve, multi-way valve 4, syringe pump 5, and measuring unit are all electrically connected to the control unit 14, thereby ensuring the effective operation of the online measuring device. Furthermore, the control unit 14 is connected to a signal transmission module to facilitate timely feedback of the online water environment monitoring measurement results and provide early warning functionality. Specifically, the signal transmission module uses an RS-485 interface and transmits the measurement results of the oil content in the water sample using the Modbus protocol.

[0038] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An online measurement method for petroleum-based substances in water, characterized in that, Includes the following steps: Step 1: Take a water sample. The triggering unit transmits the detected fluorescence intensity on the water surface to the control unit. The control unit controls the water sampling frequency of the sampling pump in the water taking unit based on the fluorescence intensity detected by the triggering unit. Step 2, extraction: The water sample extracted by the sampling pump is sent to the sample storage container. The injection pump draws the extraction reagent into the extraction reagent storage tank through the multi-port valve and injects the extraction reagent into the sample storage container. The mixer is turned on to mix the water sample and extraction reagent in the sample storage container, and the oil substances are extracted into the extraction reagent. Step 3: Separation. The mixture of water sample and extraction reagent in the sample storage container is extracted by a transfer pump and sent to the separation container. Step 4: Measurement. The extraction reagent is drawn into the separation container by the syringe pump through the multi-port valve, and then sent to the cuvette of the measurement unit for measurement of the oil content.

2. The online measurement method for petroleum in water as described in claim 1, characterized in that, In step one, when the detected fluorescence intensity does not exceed the set fluorescence threshold, the control unit enters the timed detection mode and controls the sampling pump of the water intake unit to extract water samples at regular intervals through the water intake pipeline. When the detected fluorescence intensity exceeds the set fluorescence threshold, the control unit enters the high-frequency detection mode and controls the sampling pump of the water intake unit to extract high-frequency water samples through the water intake pipeline.

3. The online measurement method for petroleum in water as described in claim 1, characterized in that, In step four, when the oil content measured by the measuring unit is lower than the set detection threshold, the injection pump sends the extraction reagent in the cuvette to the extraction reagent storage tank through the multi-port valve. When the oil content measured by the measuring unit is higher than the set detection threshold, the extraction reagent in the cuvette is sent to the waste liquid storage tank by the injection pump through the multi-port valve.

4. The online measurement method for petroleum in water as described in claim 3, characterized in that, When the oil content measured by the measuring unit is lower than the set detection threshold, and the extraction reagent in the cuvette is delivered to the extraction reagent storage tank by the injection pump through the multi-port valve, the measuring unit performs a zeroing operation based on the oil content of the extraction reagent in the extraction reagent storage tank.

5. The online measurement method for petroleum in water as described in claim 1, characterized in that, It also includes step five, cleaning, which occurs when the measuring unit completes the measurement of oil content and the oil content measured by the measuring unit is higher than the set detection threshold. The extraction reagent in the reagent storage tank is used to clean the sample storage container, separation container and cuvette throughout the process, and the control unit determines the number of times the extraction reagent is used to clean the sample storage container, separation container and cuvette through the entire process. During the next oil content measurement, the extraction reagent that has already extracted the oil from the separation container is first removed and used to clean the cuvette. Then, the extraction reagent that has already extracted the oil from the separation container is removed again to measure the oil content.

6. An online measuring device for petroleum-containing substances in water, characterized in that, A method for online measurement of petroleum in water as described in any one of claims 1-5, comprising a triggering unit, a water intake unit, an extraction unit, a separation unit, a measurement unit, and a control unit; The triggering unit includes an oil sensor in water, used to qualitatively detect oily substances on the water surface by ultraviolet fluorescence method; The water intake unit includes a water intake pipe that extends underwater, and the water intake pipe is connected to a sampling pump. The extraction unit includes a sample storage container connected to a sampling pump. The sample storage container is used to receive the extracted underwater water sample, and a mixer is provided on one side of the sample storage container. The separation unit includes a separation container, which is connected to a sample storage container via a delivery pump; The measuring unit is connected to the separation container via a multi-port valve. The measuring unit is used to receive the extraction reagent of the extracted oil substances in the separation container and to perform measurements. The multi-way valve is connected to a sample storage container, an injection pump, an extraction reagent storage tank, and a waste liquid storage tank; The control unit is used to receive the water surface fluorescence intensity collected by the oil sensor in the water, and to control the connection of the sampling pump, mixer, delivery pump, multi-way valve, injection pump and measurement unit.

7. The online measuring device for petroleum in water as described in claim 6, characterized in that, The separation container uses vertically arranged separation tubes, and the diameter of the separation tubes is smaller than the diameter of the sample storage container.

8. The online measuring device for petroleum in water as described in claim 6, characterized in that, The measuring unit employs an optical measuring instrument, which is connected to the control unit, and the multi-way valve is connected to the cuvette in the optical measuring instrument used to receive the extraction reagent.

9. The online measuring device for petroleum in water as described in claim 8, characterized in that, The measuring unit is an ultraviolet spectrophotometer or a fluorescence spectrophotometer, the extraction reagent is n-hexane reagent with a specific gravity less than water, and the upper part of the separation container is connected to a multi-port valve through a liquid extraction tube.

10. The online measuring device for petroleum in water as described in claim 8, characterized in that, The measuring unit is an infrared photometer, the extraction reagent is tetrachloroethylene reagent with a specific gravity greater than water, and the lower part of the separation container is connected to a multi-way valve through a liquid extraction tube.

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