Boric acid detector based on ultra-narrow band filter-photomultiplier

Abstract

The invention provides a boric acid detector based on an ultra-narrow band filter-photomultiplier, and belongs to the technical field of nuclear power. According to the invention, the laser generation unit is turned on to sequentially pass through the first concave lens element and the sample cell filled with the solution to be detected, and the laser is reflected back to the sample cell through the second concave lens element, so that the laser power level in the sample cell is improved, and the first photoelectric detection element and the second photoelectric detection element are used for collecting boric acid and water molecule Raman scattering signals; and converting the optical signal into an electric signal, inputting the electric signal into a data acquisition and processing system, processing data by using related software, deducting the bottom noise of the previously measured laser power, and deducting the water peak spectrum signal acquired by the second photoelectric detection element, thereby obtaining the Raman spectrum peak height value of the final boric acid ion concentration. And finally obtaining an accurate numerical value of the boric acid ion concentration in the to-be-detected solution after normalization processing.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power, and in particular relates to a boric acid detector based on an ultra-narrow band filter-photomultiplier tube. Background Art

[0002] Boric acid needs to be added to the primary coolant of a nuclear power plant to control the reaction of the core and achieve smooth operation of the nuclear power plant. Therefore, accurate measurement of the concentration of borate ions is crucial to the safe operation of the nuclear power plant.

[0003] Compared with the common gas and liquid chromatography or mass spectrometry methods for detecting compounds, Raman spectroscopy analysis technology is based on the Raman scattering phenomenon and can directly obtain the molecular vibration information of each material group in the sample. Raman spectroscopy has rich and sharp characteristic peaks. When the experimental conditions such as the frequency and intensity of the incident light are determined, the test sample can be qualitatively and quantitatively analyzed based on the data such as the number, position and intensity of the spectrum peaks. In addition, due to its principle characteristics, it can realize real-time monitoring of the reaction process, monitor the changes in the reaction materials and the level of the reaction system parameters, and avoid the problems of long measurement cycle, sampling lag and complex sample pretreatment of traditional analysis methods. It plays an important role in optimizing process operations, improving product quality and economic benefits, reducing production losses and environmental pollution, and is widely used in chemical, material, petrochemical and biomedicine fields. Therefore, online Raman spectroscopy detection technology will become an important development direction.

[0004] At present, the common Raman spectrum detection system needs to add a spectroscopic grating and a CCD camera to the system to build a spectrometer before the Raman spectrum can be analyzed and processed. Its advantage is that it can detect a wider spectral range, but this method is expensive and difficult to operate. For testing the concentration of borate ions in the primary circuit of a nuclear power plant, the use of the above-mentioned spectrum analysis system is obviously overkill, so it faces the problem of not being able to be widely promoted and applied. Summary of the invention

[0005] The embodiment of the present invention provides a boric acid detector based on an ultra-narrow band filter-photomultiplier tube, aiming to solve the technical problems in the prior art of high cost, high operation difficulty and inability to be widely promoted and applied.

[0006] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, an embodiment of the present invention provides a boric acid detector based on an ultra-narrow band filter-photomultiplier tube, comprising an automatic sampling system, an online Raman detection system and a data acquisition and processing system.

[0007] An automatic sampling system comprises a sample pool and a reflective unit, wherein the reflective unit is arranged on the sample pool; An online Raman detection system comprises a laser generating unit, two groups of Raman detection units and two groups of photoelectric detection units, wherein the two groups of Raman detection units and the two groups of photoelectric detection units are arranged in a one-to-one correspondence, and the photoelectric detection units are arranged behind the optical path extension of the Raman detection units, and the two groups of Raman detection units are respectively a first Raman detection unit and a second Raman detection unit, wherein the first Raman detection unit is used to separate the Raman signal peak of borate ions, and the second Raman detection unit is used to separate the Raman signal peak of water molecules; A data acquisition and processing system is signal-connected to the photoelectric detection unit.

[0008] In combination with the first aspect, in a possible implementation, the two groups of photoelectric detection units are respectively a first photoelectric detection unit and a second photoelectric detection unit, the first photoelectric detection unit is arranged behind the extension of the optical path of the first Raman detection unit, and the second photoelectric detection unit is arranged behind the extension of the optical path of the second Raman detection unit; the first Raman detection unit includes a first long-pass filter and an ultra-narrow band filter, and the second Raman detection unit includes a second long-pass filter and a band-pass filter; the first long-pass filter is arranged on the rear side of the sample cell, and the ultra-narrow band filter is arranged between the first long-pass filter and the first photoelectric detection unit; the second long-pass filter is arranged on the front side of the sample cell, and the band-pass filter is arranged between the second long-pass filter and the second photoelectric detection unit; Wherein, the first photoelectric detection unit and the second photoelectric detection unit are both connected to the data acquisition and processing system by signal.

[0009] In combination with the first aspect, in a possible implementation, the first photodetection unit includes a first convex mirror element and a first photodetection element, and the first photodetection element is arranged behind the extension of the optical path of the first convex mirror element; the second photodetection unit includes a second convex mirror element and a second photodetection element, and the second photodetection element is arranged behind the extension of the optical path of the second convex mirror element; The first photoelectric detection element and the second photoelectric detection element are used to convert optical signals into electrical signals.

[0010] In combination with the first aspect, in a possible implementation, the reflective unit includes four window pieces and a first concave mirror element and a second concave mirror element, the four window pieces are respectively arranged on four side elevations of the sample pool, the first concave mirror element is arranged on the left side of the sample pool, and the second concave mirror element is arranged on the right side of the sample pool; Wherein, the first concave mirror element is arranged in front of the light path of the sample cell, and the second concave mirror element is arranged behind the light path of the sample cell.

[0011] In combination with the first aspect, in a possible implementation, the four window pieces are respectively arranged on the four side facades of the sample pool, and the four window pieces are respectively a first window piece, a second window piece, a third window piece and a fourth window piece; the first window piece and the second window piece are correspondingly arranged on the left side and the right side of the sample pool, the third window piece and the fourth window piece are correspondingly arranged on the front side and the rear side of the sample pool, the first concave mirror element is arranged in front of the light path of the first window piece, and the second concave mirror element is arranged behind the light path of the second window piece; the third window piece is arranged in front of the light path of the first long-pass filter, and the fourth window piece is arranged in front of the light path of the second long-pass filter.

[0012] In combination with the first aspect, in a possible implementation, the online Raman detection system is further provided with a beam splitter prism and a power meter. The beam splitter prism is used to divide the laser power emitted by the laser generating unit into a first part and a second part. The ratio of the first part to the second part is 9:1. The laser of the second part is reflected by the beam splitter prism into the power meter to monitor the laser power in real time.

[0013] In combination with the first aspect, in a possible implementation, the first convex mirror element and the corresponding second convex mirror element both use convex lenses, the first concave mirror element and the second concave mirror element both use concave reflectors, and the first photoelectric detection element and the second photoelectric detection element both use photomultiplier tubes.

[0014] In combination with the first aspect, the sample pool is further provided with a liquid inlet pipe, a liquid outlet pipe and a liquid level detection device, the liquid inlet pipe is arranged at the bottom of the sample pool, the liquid outlet pipe is arranged at the bottom of the sample pool, and the liquid level detection device is arranged on the sample pool; Wherein, valves are provided on the liquid inlet pipe and the liquid outlet pipe.

[0015] In combination with the first aspect, in a possible implementation manner, both the first long-pass filter and the second long-pass filter are long-pass filters with a laser central emission wavelength as a cut-off wavelength.

[0016] In a second aspect, an embodiment of the present invention further provides a method for detecting boric acid based on an ultra-narrow band filter-photomultiplier tube, comprising the boric acid detector based on an ultra-narrow band filter-photomultiplier tube involved in the first aspect above, and further comprising the following steps: Step 1: Inject the liquid to be tested into the sample cell.

[0017] Step 2: Turn on the laser generating unit and let it shoot into the beam splitter. Use a power meter to monitor the laser output power at the same time to determine the background noise generated by the total laser power.

[0018] Step 3: The laser enters the sample cell filled with the solution to be tested, and the laser power level in the sample cell is increased by the reflective element.

[0019] Step 4: Use the first photoelectric detection unit and the second photoelectric detection unit to collect the Raman scattering signals of boric acid and water molecules respectively, and convert the optical signals into electrical signals and input them into the data acquisition and processing system. Use relevant software to process the data, subtract the previously measured laser power background noise, and subtract the water peak spectrum signal collected by the second photoelectric detection unit to obtain the final Raman spectrum peak height value of the borate ion concentration. After normalization, the accurate value of the borate ion concentration in the test solution is finally obtained.

[0020] Step 5: After the test is completed, turn off the laser generating unit and empty the sample pool.

[0021] The solution shown in the embodiment of the present application, compared with the prior art, is to turn on the laser generating unit, and the laser enters the sample pool and passes through the reflective unit to increase the laser power level in the sample pool, and then the Raman scattered light is divided into two groups and passes through the first Raman detection unit and the second Raman detection unit respectively, the first Raman detection unit is used to separate the Raman signal peak of the borate ion, and the second Raman detection unit is used to separate the Raman signal peak of the water molecule. Two groups of photoelectric detection units are used to collect the Raman scattering signals of boric acid and water molecules respectively, and the optical signals are converted into electrical signals and input into the data acquisition and processing system, and the data is processed by the relevant software, and the previously measured laser power background noise is deducted, and the collected water peak spectrum signal is deducted at the same time, so that the Raman spectrum peak height value of the final borate ion concentration can be obtained, and the accurate value of the borate ion concentration in the solution to be tested can be finally obtained after normalization.

[0022] The present application provides two groups of Raman detection units and two groups of photoelectric detection units in the sample pool. This solution not only improves the sensitivity of weak light detection in a large range and enhances the specificity of borate ion detection, but also greatly reduces the cost of the Raman spectroscopy detection system and reduces the difficulty of operation, thus solving the technical problems of the prior art that the cost is high, the operation is difficult, and the large-scale promotion and application are impossible. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a boric acid detector of an ultra-narrow band filter-photomultiplier tube provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a sample pool provided in an embodiment of the present invention; Description of reference numerals: 1. Laser generating unit; 2. Spectroscopic prism; 3. Power meter; 4. First concave mirror element; 5. Sample cell; 6. Second concave mirror element; 7. First long-pass filter; 8. Ultra-narrow-band filter; 9. First convex mirror element; 10. First photoelectric detection element; 11. Second long-pass filter; 12. Band-pass filter; 13. Second convex mirror element; 14. Second photoelectric detection element; 15. Data acquisition and processing system; 501. Liquid inlet pipe; 502. Liquid outlet pipe; 503. Liquid level detection device; 504. First window piece; 505. Second window piece; 506. Third window piece; 507. Fourth window piece. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] It should be further explained that the drawings and implementation modes of the present invention mainly describe the concept of the present invention. On the basis of this concept, the specific forms and settings of some connection relationships, positional relationships, power mechanisms, power supply systems, hydraulic systems and control systems may not be fully described. However, on the premise that those skilled in the art understand the concept of the present invention, those skilled in the art can implement the above-mentioned specific forms and settings in a well-known manner.

[0026] When an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

[0027] The directions or positional relationships indicated by terms such as “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0028] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, and "several" means one or more, unless otherwise clearly and specifically defined.

[0029] Please also read Figure 1 and Figure 2 , the boric acid detector based on ultra-narrow band filter-photomultiplier tube provided by the present invention is now described. (The front side, rear side, left side and right side mentioned in this application are all referred to as Figure 1 The sample pool in the sample pool is used as the reference, the horizontal left direction is the left side, the horizontal right direction is the right side, the vertical upward direction is the front side, and the vertical downward direction is the rear side) The boric acid detector based on ultra-narrow band filter-photomultiplier tube includes an automatic sampling system, an online Raman detection system and a data acquisition and processing system 15. The automatic sampling system includes a sample pool 5 and a reflective unit, and the reflective unit is arranged on the sample pool 5; An online Raman detection system comprises a laser generating unit 1, two groups of Raman detection units and two groups of photoelectric detection units, wherein the two groups of Raman detection units and the two groups of photoelectric detection units are arranged in a one-to-one correspondence, and the photoelectric detection units are arranged behind the optical path extension of the Raman detection units, the two groups of Raman detection units are respectively a first Raman detection unit and a second Raman detection unit, the first Raman detection unit is used to separate the Raman signal peak of borate ions, and the second Raman detection unit is used to separate the Raman signal peak of water molecules; The data acquisition and processing system 15 is connected to the photoelectric detection unit signal.

[0030] The laser generating unit 1 is turned on, and the laser enters the sample pool 5 and passes through the reflective unit to increase the laser power level in the sample pool 5. Then the Raman scattered light is divided into two groups and passes through the first Raman detection unit and the second Raman detection unit respectively. The first Raman detection unit is used to separate the Raman signal peak of the borate ion, and the second Raman detection unit is used to separate the Raman signal peak of the water molecule. The two groups of photoelectric detection units are used to collect the Raman scattering signals of boric acid and water molecules respectively, and the optical signals are converted into electrical signals and input into the data acquisition and processing system 15. The data is processed by the relevant software, and the laser power background noise measured before is subtracted, and the collected water peak spectrum signal is subtracted at the same time, so that the Raman spectrum peak height value of the final borate ion concentration can be obtained. After normalization, the accurate value of the borate ion concentration in the solution to be tested is finally obtained.

[0031] Compared with the prior art, the solution shown in the embodiment of the present application, by providing two groups of Raman detection units and two groups of photoelectric detection units in the sample pool 5, can greatly improve the sensitivity of weak light detection in a large range and enhance the specificity of borate ion detection, while also greatly reducing the cost of the Raman spectrum detection system and reducing the difficulty of operation, thereby solving the technical problems of the prior art that the cost is high, the operation is difficult, and the large-scale promotion and application are impossible.

[0032] The two groups of photoelectric detection units are respectively a first photoelectric detection unit and a second photoelectric detection unit. The first photoelectric detection unit is arranged behind the optical path extension of the first Raman detection unit, and the second photoelectric detection unit is arranged behind the optical path extension of the second Raman detection unit. The first Raman detection unit includes a first long-pass filter 7 and an ultra-narrow-band filter 8, and the second Raman detection unit includes a second long-pass filter 11 and a band-pass filter 12. The first long-pass filter 7 is arranged on the rear side of the sample pool 5, and the ultra-narrow-band filter 8 is arranged between the first long-pass filter 7 and the first photoelectric detection unit. The second long-pass filter 11 is arranged on the front side of the sample pool 5, and the band-pass filter 12 is arranged between the second long-pass filter 11 and the second photoelectric detection unit. The first photoelectric detection unit and the second photoelectric detection unit are both connected to the data acquisition and processing system 15 by signals.

[0033] The reflective unit reflects the laser back to the sample pool 5 to increase the laser intensity. The excited Raman scattered light first passes through the first long-pass filter 7 to shield the excitation light source, and then passes through the ultra-narrow band filter 8 to completely separate the Raman signal peak of the borate ion. At the same time, on the front side of the sample pool 5, the Raman scattered light will also first pass through the second long-pass filter 11 to shield the laser source, and then pass through the band-pass filter 12 to separate the Raman scattered light of the water molecules. After the Raman peaks of borate ions and water molecules are completely separated by the first long-pass filter 7 and the second long-pass filter 11 in front, the Raman scattered signal light enters the first photoelectric detection unit, and the first photoelectric detection unit converges the Raman signal scattered light and finally converts it into an electrical signal. The first photoelectric detection unit converts the weak Raman scattered light signal into an electrical signal and inputs it into the data acquisition and processing system 15 for processing related data such as borate ion concentration; at the same time, on the other side of the sample pool 5, the Raman spectrum signal of water molecules is screened out by the second long-pass filter 11 and the bandpass filter 12 and enters the second photoelectric detection unit, and the weak light signal is converted into an electrical signal by entering the second photoelectric detection unit and input into the data acquisition and processing system 15 for Raman spectrum signal analysis and processing of the water peak.

[0034] This embodiment can greatly improve the sensitivity of weak light detection and enhance the specificity of borate ion detection by using an ultra-narrow bandwidth filter; at the same time, it can greatly reduce the cost of the Raman spectroscopy detection system and reduce the difficulty of operation, thus solving the technical problems of the prior art that the cost is high, the operation is difficult, and the large-scale promotion and application are impossible.

[0035] In other embodiments, the first photodetection unit includes a first convex mirror element 9 and a first photodetection element 10, and the first photodetection element 10 is arranged behind the extension of the optical path of the first convex mirror element 9; the second photodetection unit includes a second convex mirror element 13 and a second photodetection element 14, and the second photodetection element 14 is arranged behind the extension of the optical path of the second convex mirror element 13; The first photodetection element 10 and the second photodetection element 14 are used to convert the optical signal into an electrical signal.

[0036] The first convex mirror element 9 and the second convex mirror element 13 can converge weak light and transmit it to the correspondingly arranged first photodetection element 10 and second photodetection element 14, so that the first photodetection element 10 and the second photodetection element 14 respectively convert the received light signals into electrical signals.

[0037] The reflective unit includes four windows and a first concave mirror element 4 and a second concave mirror element 6. The four windows are respectively arranged on four side elevations of the sample pool 5. The first concave mirror element 4 is arranged on the left side of the sample pool 5, and the second concave mirror element 6 is arranged on the right side of the sample pool 5. The first concave mirror element 4 is arranged in front of the optical path of the sample pool 5 , and the second concave mirror element 6 is arranged in the rear of the optical path of the sample pool 5 .

[0038] Four windows are respectively arranged on the four side elevations of the sample pool 5, and the four windows are respectively a first window 504, a second window 505, a third window 506 and a fourth window 507; the first window 504 and the second window 505 are correspondingly arranged on the left and right sides of the sample pool 5, the third window 506 and the fourth window 507 are correspondingly arranged on the front and rear sides of the sample pool 5, the first concave mirror element 4 is arranged in front of the optical path of the first window 504, and the second concave mirror element 6 is arranged behind the optical path of the second window 505; the third window 506 is arranged in front of the optical path of the first long-pass filter 7, and the fourth window 507 is arranged in front of the optical path of the second long-pass filter 11.

[0039] After the laser generating unit 1 emits the laser, it enters the first concave mirror element 4, and then passes through the sample pool 5. The laser enters the sample pool 5 from the first window 504, passes through the second window 505, and is reflected back to the sample pool 5 by the second concave reflector, thereby increasing the number of times the laser passes through the sample and enhancing the intensity of the excitation light. The generated Raman scattered light signal is transmitted through the third window 506 and the fourth window 507, and enters the subsequent filter to separate the Raman scattered light peak.

[0040] Furthermore, the online Raman detection system is also provided with a beam splitter prism 2 and a power meter 3. The beam splitter prism 2 is used to split the laser power emitted by the laser generating unit 1 into two parts at a ratio of 9:1, of which the small part is reflected by the beam splitter prism 2 into the power meter 3, thereby playing the role of real-time monitoring of the laser power.

[0041] Based on the above embodiments, the first convex mirror element 9 and the second convex mirror element 13 both adopt convex lenses or devices that can focus light, the first concave mirror element 4 and the second concave mirror element 6 both adopt concave reflectors or devices that can have the same effect as concave reflectors, and the first photoelectric detection element 10 and the second photoelectric detection element 14 both adopt photomultiplier tubes or devices that have the same effect as photomultiplier tubes.

[0042] In some embodiments, the sample pool 5 is further provided with a liquid inlet pipe 501, a liquid outlet pipe 502 and a liquid level detection device 503, the liquid inlet pipe 501 is arranged at the bottom of the sample pool 5, the liquid outlet pipe 502 is arranged at the bottom of the sample pool 5, and the liquid level detection device 503 is arranged on the sample pool 5; Wherein, valves are provided on the liquid inlet pipe 501 and the liquid outlet pipe 502.

[0043] When the sample pool 5 needs to be filled with the test liquid, the valve on the liquid outlet pipe 502 is closed and the valve on the liquid inlet pipe 501 is opened. When the test liquid in the sample pool 5 is filled to the experimental requirements, the liquid level detection device 503 detects the test liquid and issues an alarm to remind the experimenter to close the valve on the liquid inlet pipe 501. When the sample pool 5 needs to be emptied of the test liquid, the valve on the liquid outlet pipe 502 is opened.

[0044] Specifically, the laser generating unit 1 is a laser. Furthermore, the power of the laser is automatically controlled by a computer.

[0045] Specifically, the laser generating unit 1 emits energy of 50 mW-500 mW.

[0046] Specifically, the cutoff wavelengths of the first long-pass filter 7 and the second long-pass filter 11 are the central emission wavelengths of the lasers.

[0047] Specifically, the emission wavelength range of the laser generating unit 1 is 266-1064 nm, including but not limited to 532 nm, 633 nm, 660 nm, 785 nm, 1064 nm, etc.

[0048] The liquid level detection device 503 includes a liquid level meter and an alarm. The liquid level meter is vertically arranged above the sample pool 5, and the bottom of the liquid level meter is flush with the upper plane of the sample pool. The alarm is connected to the liquid level meter. When the liquid level meter detects that the liquid level in the sample pool 5 reaches the standard, it transmits the liquid level signal to the alarm device, so that the alarm device sounds an alarm.

[0049] In some embodiments, the sample pool 5 adopts a pressurized design.

[0050] Based on the same inventive concept, the embodiment of the present application also provides a method for detecting boric acid based on an ultra-narrow band filter-photomultiplier tube, including the boric acid detector based on an ultra-narrow band filter-photomultiplier tube involved in the first aspect, and further including the following steps: Step 1: Inject the liquid to be tested into the sample pool 5.

[0051] Step 2: Turn on the laser generating unit 1, let it irradiate into the beam splitter prism 2, and use the power meter 3 to monitor the laser output power at the same time to determine the background noise generated by the total laser power.

[0052] Step 3: The laser enters the sample pool 5 filled with the solution to be tested, and the laser power level in the sample pool 5 is increased by the reflective element.

[0053] Step 4: Use the first photoelectric detection unit and the second photoelectric detection unit to collect the Raman scattering signals of boric acid and water molecules respectively, and convert the optical signals into electrical signals and input them into the data acquisition and processing system 15, use relevant software to process the data, subtract the previously measured laser power background noise, and subtract the water peak spectrum signal collected by the second photoelectric detection unit, so as to obtain the final Raman spectrum peak height value of the borate ion concentration, and finally obtain the accurate value of the borate ion concentration in the test solution after normalization.

[0054] Step 5: After the detection is completed, turn off the laser generating unit 1 and empty the sample pool 5.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Boric acid detector based on ultra-narrow band filter-photomultiplier tube, characterized in that: include: An automatic sampling system comprises a sample pool (5) and a reflective unit, wherein the reflective unit is arranged on the sample pool (5); An online Raman detection system comprises a laser generating unit (1), two groups of Raman detection units and two groups of photoelectric detection units, wherein the two groups of Raman detection units and the two groups of photoelectric detection units are arranged in a one-to-one correspondence, and the photoelectric detection units are arranged behind the optical paths of the Raman detection units, the two groups of Raman detection units are respectively a first Raman detection unit and a second Raman detection unit, the first Raman detection unit is used to separate the Raman signal peak of borate ions, and the second Raman detection unit is used to separate the Raman signal peak of water molecules; A data acquisition and processing system (15) is signal-connected to the photoelectric detection unit.

2. The boric acid detector based on ultra-narrow band filter-photomultiplier tube as claimed in claim 1, characterized in that: The two groups of photoelectric detection units are respectively a first photoelectric detection unit and a second photoelectric detection unit, the first photoelectric detection unit is arranged behind the optical path of the first Raman detection unit, and the second photoelectric detection unit is arranged behind the optical path of the second Raman detection unit; the first Raman detection unit comprises a first long-pass filter (7) and an ultra-narrow-band filter (8), and the second Raman detection unit comprises a second long-pass filter (11) and a band-pass filter (12); the first long-pass filter (7) is arranged on the rear side of the sample pool (5), and the ultra-narrow-band filter (8) is arranged between the first long-pass filter (7) and the first photoelectric detection unit; the second long-pass filter (11) is arranged on the front side of the sample pool (5), and the band-pass filter (12) is arranged between the second long-pass filter (11) and the second photoelectric detection unit; The first photoelectric detection unit and the second photoelectric detection unit are both connected to the data acquisition and processing system (15) by signal.

3. The boric acid detector based on ultra-narrow band filter-photomultiplier tube as claimed in claim 2, characterized in that: The first photoelectric detection unit comprises a first convex mirror element (9) and a first photoelectric detection element (10), wherein the first photoelectric detection element (10) is arranged behind the extension of the optical path of the first convex mirror element (9); the second photoelectric detection unit comprises a second convex mirror element (13) and a second photoelectric detection element (14), wherein the second photoelectric detection element (14) is arranged behind the extension of the optical path of the second convex mirror element (13); The first photoelectric detection element (10) and the second photoelectric detection element (14) are used to convert optical signals into electrical signals.

4. The boric acid detector based on ultra-narrow band filter-photomultiplier tube as claimed in claim 3, characterized in that: The reflective unit comprises four window pieces and a first concave mirror element (4) and a second concave mirror element (6); the four window pieces are respectively arranged on four side elevations of the sample pool (5); the first concave mirror element (4) is arranged on the left side of the sample pool (5); and the second concave mirror element (6) is arranged on the right side of the sample pool (5); The first concave mirror element (4) is arranged in front of the light path of the sample pool (5), and the second concave mirror element (6) is arranged behind the light path of the sample pool (5).

5. The boric acid detector based on ultra-narrow band filter-photomultiplier tube as claimed in claim 4, characterized in that: The four window pieces are respectively arranged on four side elevations of the sample pool (5), and the four window pieces are respectively a first window piece (504), a second window piece (505), a third window piece (506) and a fourth window piece (507); the first window piece (504) and the second window piece (505) are respectively arranged on the left side and the right side of the sample pool (5), the third window piece (506) and the fourth window piece (507) are respectively arranged on the front side and the rear side of the sample pool (5); the first concave mirror element (4) is arranged in front of the optical path of the first window piece (504), and the second concave mirror element (6) is arranged behind the optical path of the second window piece (505); the third window piece (506) is arranged in front of the optical path of the first long-pass filter (7), and the fourth window piece (507) is arranged in front of the optical path of the second long-pass filter (11).

6. The boric acid detector based on ultra-narrow band filter-photomultiplier tube as claimed in claim 4, characterized in that: The online Raman detection system is further provided with a beam splitter prism (2) and a power meter (3). The beam splitter prism (2) is used to split the laser power emitted by the laser generating unit (1) into a first part and a second part. The ratio of the first part to the second part is 9:

1. The laser of the second part is reflected by the beam splitter prism (2) and enters the power meter (3) to monitor the laser power in real time.

7. The boric acid detector based on ultra-narrow band filter-photomultiplier tube as claimed in claim 4, characterized in that: The first convex mirror element (9) and the corresponding second convex mirror element (13) both adopt convex lenses, the first concave mirror element (4) and the second concave mirror element (6) both adopt concave reflectors, and the first photoelectric detection element (10) and the second photoelectric detection element (14) both adopt photomultiplier tubes.

8. The ultra-narrow band filter-photomultiplier tube-based boric acid detector according to claim 1, characterized in that: The sample pool (5) is further provided with a liquid inlet pipe (501), a liquid outlet pipe (502) and a liquid level detection device (503); the liquid inlet pipe (501) is arranged at the bottom of the sample pool (5); the liquid outlet pipe (502) is arranged at the bottom of the sample pool (5); and the liquid level detection device (503) is arranged on the sample pool (5); Wherein, valves are provided on the liquid inlet pipe (501) and the liquid outlet pipe (502).

9. The ultra-narrow band filter-photomultiplier tube-based boric acid detector according to claim 2, characterized in that: The first long-pass filter (7) and the second long-pass filter (11) are both long-pass filters with the laser central emission wavelength as the cut-off wavelength.

10. A method for detecting boric acid based on an ultra-narrow band filter-photomultiplier tube, comprising the boric acid detector based on an ultra-narrow band filter-photomultiplier tube as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: inject the liquid to be tested into the sample pool (5); Step 2: Turn on the laser generating unit (1) to allow it to enter the beam splitter (2), and use a power meter (3) to simultaneously monitor the laser output power to determine the background noise generated by the total laser power; Step 3: The laser continues to pass through the first concave mirror element (4), the sample pool (5) filled with the solution to be tested, and is reflected back into the sample pool (5) through the second concave mirror element (6), thereby increasing the laser power level in the sample pool (5); Step 4: using the first photoelectric detection element (10) and the second photoelectric detection element (14) to respectively collect the Raman scattering signals of boric acid and water molecules, and converting the optical signals into electrical signals and inputting them into the data acquisition and processing system (15), using relevant software to process the data, subtracting the previously measured laser power background noise, and at the same time subtracting the water peak spectrum signal collected by the second photoelectric detection element (14), the final Raman spectrum peak height value of the borate ion concentration can be obtained, and after normalization processing, the accurate value of the borate ion concentration in the test solution can be finally obtained; Step 5: After the test is completed, open the liquid outlet pipe (502) of the sample pool (5) to discharge the waste liquid and empty the sample pool (5).

Images