On-line analysis method and system for heavy water concentration based on infrared spectroscopy

Abstract

The present application provides an online analysis method and system for heavy water concentration based on infrared spectroscopy, which relates to the technical field of heavy water concentration measurement. The method includes: obtaining an absorption spectral line formed after an infrared light beam passes through a target solution, and determining the concentration information of the liquid to be measured based on the absorption spectral line; by selecting four adjacent spectral segments from the absorption spectrum, and determining four adjacent spectral regions based on the four spectral segments, namely the first spectral region, the second spectral region, the third spectral region and the fourth spectral region, if the corresponding concentration values in the concentration information respectively belong to high-range, medium-range and low-range concentration monitoring, each range corresponds to each spectral region and each model function; determining the concentration of the liquid to be measured according to the corresponding model function and the absorbance intensity of the corresponding spectral region. This method adapts to high, medium and low range concentrations by selecting different spectral regions and model functions, increasing the accuracy of concentration monitoring.

Description

Technical Field

[0001] The present application relates to the technical field of heavy water concentration measurement, and in particular to an online analysis method and system for heavy water concentration based on infrared spectroscopy. Background Art

[0002] Heavy water, as a moderator in nuclear reactors, is crucial to ensure reactor performance and safety. However, traditional heavy water concentration detection methods, including density method, mass spectrometry and infrared spectroscopy, mainly use offline sampling analysis, which has shortcomings such as analysis lag and inability to monitor in real time, which seriously restricts the development of nuclear industry automation. In particular, infrared spectroscopy requires calibration of specific range segments in practical applications, which limits its application in full-range concentration measurement and increases the possibility of human error. In addition, the presence of H in the mixture of heavy water and ordinary water can cause the concentration of heavy water to be less than 100%. 2 O、HDO、D 2 O three forms, resulting in large errors in conventional online calibration methods. Changes in temperature and pressure will also affect the measurement results, and existing technologies have failed to provide effective solutions.

[0003] Therefore, developing an online analysis system for heavy water concentration that can monitor online in real time, automatically calibrate, and eliminate the influence of environmental factors is of great significance to improving the safety and efficiency of the nuclear industry. Summary of the invention

[0004] Based on this, it is necessary to provide an online analysis method and system for heavy water concentration based on infrared spectroscopy to address the above technical problems.

[0005] In a first aspect, the present application provides an online analysis method for heavy water concentration based on infrared spectroscopy. The method comprises:

[0006] Obtain the absorption spectrum formed after the infrared beam passes through the target solution, and determine the concentration information of the measured liquid based on the absorption spectrum, wherein the target solution contains at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O;

[0007] According to the concentration information of the measured liquid, a spectral line region and a model function corresponding to the concentration information are selected; wherein, four adjacent spectral line segments are selected from the absorption spectrum, and four adjacent spectral line regions are determined based on the four spectral line segments, namely, a first spectral line region, a second spectral line region, a third spectral line region and a fourth spectral line region, and the absorbance intensity peak value of the fourth spectral line region is greater than that of the first, second and third spectral line regions; if the corresponding concentration value in the concentration information belongs to high-range concentration monitoring, the first spectral line region and the first model function related to the absorbance intensity of the spectral line region are selected; if it belongs to mid-range concentration monitoring, the second and third spectral line regions and the second model function related to the absorbance intensity ratio of the two spectral line regions are selected; if it belongs to low-range concentration monitoring, the fourth spectral line region and the third model function related to the absorbance intensity of the spectral line region are selected;

[0008] The concentration of the measured liquid is determined based on the corresponding model function and the absorbance intensity of the corresponding spectral line area.

[0009] In one embodiment, determining the concentration information of the measured liquid based on the absorption spectrum includes: determining the concentration change trend of the measured liquid and the concentration interval in which it is located based on the absorption spectrum; wherein the concentration change trend includes rising and falling, if the concentration change trend is rising, the concentration interval is a concentration interval in a first interval set, the first interval set includes a first concentration interval, a second concentration interval and a third concentration interval, and any value in the second concentration interval is greater than a value in the first concentration interval and less than a value in the third concentration interval; if the concentration change trend is falling, the concentration interval is a concentration interval in the second interval set, the second interval set includes a fourth concentration interval, a fifth concentration interval and a sixth concentration interval, and any value in the fifth concentration interval is less than a value in the fourth concentration interval and greater than a value in the sixth concentration interval;

[0010] According to the monitoring range of the measured liquid, a model function and a spectral line area corresponding to the monitoring range are selected, including: according to the concentration change trend and the concentration range of the measured liquid, a model function and a spectral line area corresponding to the concentration change trend and the concentration range are selected.

[0011] In one embodiment, according to the concentration variation trend and the concentration interval of the measured liquid, a model function and a spectral line region corresponding to the concentration variation trend and the concentration interval are selected, including:

[0012] When the concentration of the measured liquid is rising, if the concentration is in the first concentration interval, the fourth spectral line area and the third model function are selected; if the concentration is in the second concentration interval, the second and third spectral line areas and the second model function are selected; if the concentration is in the third concentration interval, the first spectral line area and the first model function are selected;

[0013] When the concentration of the measured liquid is decreasing, if the concentration is in the fourth concentration interval, select the first spectral line area and the first model function; if the concentration is in the fifth concentration interval, select the second and third spectral line areas and the second model function; if the concentration is in the sixth concentration interval, select the fourth spectral line area and the third model function.

[0014] In one embodiment, the first model function is: ;

[0015] The second model function is: ;

[0016] The third model function is: ;

[0017] in, 、 、 is the concentration of the measured liquid, 、 、 、 、 is the calibration factor, 、 、 is the intercept coefficient, 、 、 、 The absorbance intensity integrals for the first, second, third and fourth spectral line regions respectively.

[0018] In one embodiment, the first spectral line region is: , the second spectral line region is: , the third spectral line region is: , the fourth spectral line region is: ,in, , , , are the wave numbers corresponding to the absorption peaks of the four spectral line regions, , , , , , , , It is related to the half-height width of the corresponding infrared spectrum line segment, specifically 3 / 5~3 / 4 of the corresponding half-height width;

[0019] The integral calculation method of the absorbance intensity of the first, second, third and fourth spectral line regions is:

[0020] ,

[0021] in, is the system spectral response coefficient, is the original absorption intensity of the infrared beam, is the absorption intensity of the infrared beam passing through the target liquid; is the corresponding infrared spectrum segment, The value range is 1~4; It is the interference function of the target liquid temperature T and the pressure P in the object through which the target liquid flows on the measurement result.

[0022] In one embodiment, determining the first set of intervals and the second set of intervals includes:

[0023] The upper limit of the first target interval is α times the maximum concentration of the measured liquid that can be measured in the fourth spectral line area, and the lower limit of the first target interval is the minimum concentration of the measured liquid that can be measured in the second and third spectral line areas;

[0024] The maximum concentration of the measured liquid that can be measured in the second and third spectral line regions is taken as the upper limit of the second target interval, and β times the maximum concentration of the measured liquid that can be measured in the first spectral line region is taken as the lower limit of the second target interval;

[0025] According to the upper and lower limits of the first target interval and the upper and lower limits of the second target interval, each concentration interval in the first interval set and the second interval set is determined; wherein the upper and lower limits of the first target interval are used for switching between low-range concentration monitoring and mid-range concentration monitoring of the measured liquid, and the upper and lower limits of the second target interval are used for switching between mid-range concentration monitoring and high-range concentration monitoring of the measured liquid.

[0026] In one embodiment, determining each concentration interval in the first interval set and the second interval set according to the upper and lower limits of the first target interval and the upper and lower limits of the second target interval includes:

[0027] Determine the sixth concentration interval according to the upper limit of the first target interval, and determine the first concentration interval according to the lower limit of the first target interval;

[0028] Determine the fourth concentration interval according to the upper limit of the second target interval, and determine the third concentration interval according to the lower limit of the second target interval;

[0029] The second concentration interval is determined according to the first target interval lower limit and the second target interval lower limit, and the fifth concentration interval is determined according to the first target interval upper limit and the second target interval upper limit.

[0030] In a second aspect, the present application provides an online analysis system for heavy water concentration based on infrared spectroscopy, the system comprising an infrared emission device, an interferometer, a first reflector, a second reflector, a circulation cell, a detection device, and a control module;

[0031] The infrared emitting device is configured to emit an infrared beam. A target solution flows in the circulation pool, and the target solution contains at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O; wherein, the infrared light beam passes through the interferometer to form interference light and is emitted, converged by the first reflector and passes through the circulation cell, the infrared light beam passing through the circulation cell passes through the second reflector, and the intensity signal is detected by the detection device, so that an absorption spectrum is formed based on the intensity signal, and the control module is configured to perform the above-mentioned heavy water concentration online analysis method based on the absorption spectrum.

[0032] In one embodiment, the system includes an infrared emitting device, a first reflector, a second reflector, a flow cell, a beam splitter, a first filtering device, a second filtering device, a first detection device, a second detection device, and a control module;

[0033] The infrared emitting device is configured to emit an infrared beam, and a target solution flows in the flow cell, and the target solution contains at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O; the infrared light beam is converged by the first reflector and passes through the circulation pool, and after the infrared light beam is converged, the direction is adjusted by the second reflector to become a parallel light beam, and passes through the beam splitter; wherein the first band and the second band obtained after vertical transmission through the beam splitter are time-division multiplexed by the first filtering device, and the intensity signals of the first band and the second band are detected by the first detection device; the third band and the fourth band obtained after reflection by the beam splitter are time-division multiplexed by the second filtering device, and the intensity signals of the third band and the fourth band are detected by the second detection device, so that an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands, and the control module is configured to perform the above-mentioned heavy water concentration online analysis method based on the absorption spectrum.

[0034] In one embodiment, the system includes an infrared emitting device, an attenuated total reflection device, a beam splitter, a first filtering device, a second filtering device, a first detection device, a second detection device, and a control module;

[0035] The infrared emitting device is configured to emit an infrared beam, and a target solution flows through the attenuated total reflection device, and the target solution contains at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O; the infrared light beam enters the attenuated total reflection device, forms total reflection with the target solution and then is emitted and passes through the beam splitter; wherein the first band and the second band obtained after vertical transmission through the beam splitter are time-division multiplexed by the first filtering device, and the intensity signals of the first band and the second band are detected by the first detection device; the third band and the fourth band obtained after reflection from the beam splitter are time-division multiplexed by the second filtering device, and the intensity signals of the third band and the fourth band are detected by the second detection device, so that an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands, and the control module is configured to perform the above-mentioned heavy water concentration online analysis method based on the absorption spectrum.

[0036] The above-mentioned method for online analysis of heavy water concentration based on infrared spectroscopy obtains the absorption spectrum formed after the infrared beam passes through the target solution, determines the concentration information of the measured liquid based on the absorption spectrum, selects four adjacent spectrum segments from the absorption spectrum, and determines four adjacent spectrum areas based on the four spectrum segments, which are the first spectrum area, the second spectrum area, the third spectrum area and the fourth spectrum area. Different spectrum areas also have model functions related to the absorbance intensity of the spectrum area. By selecting different spectrum areas and their corresponding model functions to adapt to high, medium and low range concentration monitoring, the concentration of the measured liquid is determined according to the corresponding model function and the absorbance intensity of the corresponding spectrum area. This method can cover a wide range of concentrations by selecting different spectrum areas and model functions to adapt to high, medium and low range concentration monitoring, and increases the flexibility of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure is a schematic flow chart of a method for online analysis of heavy water concentration based on infrared spectroscopy in one embodiment;

[0038] Figure 2 It is a schematic diagram of a process of determining the concentration information of the measured liquid based on the absorption spectrum in one embodiment;

[0039] Figure 3 A schematic diagram of a flow chart of selecting a model function and a spectral line region for a concentration variation trend and a concentration interval of a measured liquid in one embodiment;

[0040] Figure 4 is a graph showing a linear relationship between the ratio of the absorbance of two spectral lines and the concentration of heavy water in one embodiment;

[0041] Figure 5A schematic diagram of four measurement spectral lines in one embodiment;

[0042] Figure 6 A schematic diagram of a process of determining a first interval set and a second interval set in one embodiment;

[0043] Figure 7 A schematic diagram of a process for determining each concentration interval in a first interval set and a second interval set based on the upper limit and the lower limit of the first target interval and the upper limit and the lower limit of the second target interval in one embodiment;

[0044] Figure 8 is a structural diagram of a first system for online analysis of heavy water concentration based on infrared spectroscopy in one embodiment;

[0045] Fig. 9 is a structural diagram of a second system for online analysis of heavy water concentration based on infrared spectroscopy in one embodiment;

[0046] Fig.10 is a structural diagram of a third system for online analysis of heavy water concentration based on infrared spectroscopy in one embodiment;

[0047] Fig.11 4 is a structural diagram of an attenuated total reflection device in one embodiment. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application 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 application and are not used to limit the present application.

[0049] In one embodiment, Figure 1 As shown, a method for online analysis of heavy water concentration based on infrared spectroscopy is provided, comprising the following steps:

[0050] Step 101: Obtain the absorption spectrum formed after the infrared beam passes through the target solution, and determine the concentration information of the measured liquid based on the absorption spectrum, wherein the target solution contains at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O;

[0051] Specifically, the target solution is a mixed solution of heavy water and water. There are three forms of reaction, namely H 2 O、HDO、D 2O three forms. The infrared emitting device emits an infrared beam, which passes through the target solution, and the detection device obtains the absorption spectrum formed by the infrared beam after passing through the target solution. The liquid D to be tested is determined based on the absorption spectrum obtained by the detection device. 2 O concentration information, etc.

[0052] Step 102: According to the concentration information of the measured liquid, select a spectral line region and a model function corresponding to the concentration information; wherein, by selecting four adjacent spectral line segments from the absorption spectrum, and determining four adjacent spectral line regions based on the four spectral line segments, namely a first spectral line region, a second spectral line region, a third spectral line region and a fourth spectral line region, the absorbance intensity peak value of the fourth spectral line region is greater than that of the first, second and third spectral line regions; if the corresponding concentration value in the concentration information belongs to high-range concentration monitoring, select the first spectral line region and the first model function related to the absorbance intensity of the spectral line region; if it belongs to mid-range concentration monitoring, select the second and third spectral line regions and the second model function related to the absorbance intensity ratio of the two spectral line regions; if it belongs to low-range concentration monitoring, select the fourth spectral line region and the third model function related to the absorbance intensity of the spectral line region;

[0053] Specifically, four adjacent spectral line segments are selected from the absorption spectrum, and four adjacent spectral line regions are determined based on the four spectral line segments, namely the first spectral line region, the second spectral line region, the third spectral line region and the fourth spectral line region, and the absorbance intensity peak of the fourth spectral line region is greater than that of the first, second and third spectral line regions. According to the concentration information of the measured liquid obtained in step 101, it is determined whether the concentration belongs to the high-range, medium-range or low-range concentration monitoring range. If the corresponding concentration value in the concentration information belongs to the high-range concentration monitoring, the first spectral line region and the first model function related to the absorption intensity of the spectral line region are selected. Usually, the first model function is a linear equation or a univariate multi-time equation, which can be , where C is the concentration, A 1 is the absorbance intensity of the first spectral line region, a 1 and b 1 is the calibration coefficient; if it is a mid-range concentration monitoring, select the second and third spectral line regions and the second model function related to the absorbance intensity ratio of the two spectral line regions. Usually the second model function can be , C is the concentration, A 2 and A 3 are the absorbance intensities of the second and third spectral line regions, a 2 and b 2 is the calibration coefficient; if it is low-range concentration monitoring, select the fourth spectral line region and the third model function related to the absorbance intensity of the spectral line region. Usually the third model function can be , C is the concentration, A4 is the absorbance intensity of the fourth spectral line region, a 3 and b 3 is the calibration factor.

[0054] Step 103: Determine the concentration of the liquid being measured according to the corresponding model function and the absorbance intensity of the corresponding spectral line area.

[0055] Specifically, if the corresponding concentration value in the concentration information of the measured liquid belongs to the high-range concentration monitoring range, the first spectral line area and the first model function related to the absorbance intensity of the spectral line area are selected. If it belongs to the medium-range concentration monitoring range, the second and third spectral line areas and the second model function related to the absorbance intensity ratio of the two spectral line areas are selected. If it belongs to the low-range concentration monitoring range, the fourth spectral line area and the third model function related to the absorbance intensity of the spectral line area are selected. According to the concentration detection range of different ranges, the corresponding spectral line area and the model function related to the absorbance intensity of the spectral line area are selected to determine the concentration of the measured liquid.

[0056] In this embodiment, the absorption spectrum formed after the infrared light beam passes through the target solution is obtained, and the concentration information of the measured liquid is determined based on the absorption spectrum. Four adjacent spectrum segments are selected from the absorption spectrum, and four adjacent spectrum areas are determined based on the four spectrum segments, which are the first spectrum area, the second spectrum area, the third spectrum area and the fourth spectrum area. Different spectrum areas also have model functions related to the absorbance intensity of the spectrum area. By selecting different spectrum areas and their corresponding model functions to adapt to high, medium and low range concentration monitoring, the concentration of the measured liquid is determined according to the corresponding model function and the absorbance intensity of the corresponding spectrum area. This method can cover a wide range of concentrations by selecting different spectrum areas and model functions to adapt to high, medium and low range concentration monitoring, increase the flexibility of application, and the infrared beam emitting equipment is relatively low in cost, with good cost-effectiveness.

[0057] In one embodiment, Figure 2 As shown, determining the concentration information of the measured liquid based on the absorption spectrum includes the following steps:

[0058] Step 201: Determine the concentration change trend of the measured liquid and the concentration interval in which it is located based on the absorption spectrum; wherein the concentration change trend includes rising and falling, if the concentration change trend is rising, the concentration interval is a concentration interval in the first interval set, the first interval set includes the first concentration interval, the second concentration interval and the third concentration interval, and any value in the second concentration interval is greater than the value in the first concentration interval and less than the value in the third concentration interval; if the concentration change trend is falling, the concentration interval is a concentration interval in the second interval set, the second interval set includes the fourth concentration interval, the fifth concentration interval and the sixth concentration interval, and any value in the fifth concentration interval is less than the value in the fourth concentration interval and greater than the value in the sixth concentration interval.

[0059] Specifically, if the concentration change trend of the measured liquid is rising, the measured liquid concentration value is compared with a preset first interval set, which includes a first concentration interval, a second concentration interval, and a third concentration interval, to determine in which concentration interval the measured liquid concentration is located. Any numerical value in the second concentration interval is greater than the numerical value in the first concentration interval and less than the numerical value in the third concentration interval. For example, if the measured liquid concentration value is greater than the first concentration interval and less than the third concentration interval, it is determined that the measured liquid concentration is located in the second concentration interval. If the measured liquid concentration trend is falling, the measured liquid concentration value is compared with a preset second interval set, which includes a fourth concentration interval, a fifth concentration interval, and a sixth concentration interval, to determine in which concentration interval the measured liquid concentration is located. Any numerical value in the fifth concentration interval is less than the numerical value in the fourth concentration interval and greater than the numerical value in the sixth concentration interval. For example, if the measured liquid concentration value is less than the fourth concentration interval and greater than the sixth concentration interval, it is determined that the measured liquid concentration is located in the fifth concentration interval.

[0060] Step 202: According to the monitoring range of the measured liquid, select the model function and spectral line area corresponding to the monitoring range, including: according to the concentration change trend and concentration range of the measured liquid, select the model function and spectral line area corresponding to the concentration change trend and concentration range.

[0061] Specifically, if the concentration change trend of the measured liquid is rising, according to the concentration value of the measured liquid, determine in which concentration interval of the first interval set including the first, second, and third concentration intervals the concentration of the measured liquid is located. In the case of determining that the concentration change trend of the measured liquid is rising, determine in which range concentration monitoring range of the high, medium, and low ranges the concentration value of the measured liquid is located, and select the spectral line area corresponding to the range concentration monitoring range and the model function related to the absorbance intensity of the spectral line area. If the concentration change trend of the measured liquid is falling, according to the concentration value of the measured liquid, determine in which concentration interval of the second interval set including the fourth, fifth, and sixth concentration intervals the concentration of the measured liquid is located. In the case of determining that the concentration change trend of the measured liquid is falling, determine in which range concentration monitoring range of the high, medium, and low ranges the concentration value of the measured liquid is located, and select the spectral line area corresponding to the range concentration monitoring range and the model function related to the absorbance intensity of the spectral line area.

[0062] In this embodiment, the rising or falling trend of the concentration of the measured liquid can be monitored and determined by analyzing the absorption spectrum, and the first and second interval sets are defined. The corresponding spectral line area and model function are selected according to the concentration change trend and the interval corresponding to the concentration. This optimizes the allocation of measurement resources, improves the analysis efficiency, and can adapt to monitoring needs under different concentrations. Accurate analysis results can be provided regardless of high, medium or low ranges.

[0063] In one embodiment, Figure 3 As shown, according to the concentration variation trend of the measured liquid and the concentration interval in which it is located, a model function and a spectral line area corresponding to the concentration variation trend and the concentration interval are selected, including the following steps:

[0064] Step 301: When the concentration of the measured liquid is rising, if the concentration is in the first concentration range, select the fourth spectral line area and the third model function; if the concentration is in the second concentration range, select the second and third spectral line areas and the second model function; if the concentration is in the third concentration range, select the first spectral line area and the first model function.

[0065] Specifically, if the concentration of the measured liquid has an increasing trend and the concentration of the measured liquid is in the first concentration interval, a third model function related to the fourth spectral line region and the absorbance intensity of the spectral line region is selected. The third model function may be: , C is the concentration, A 4 is the absorbance intensity of the fourth spectral line region, a 3 and b 3 is the calibration coefficient; if the concentration of the measured liquid is in the second concentration interval, a second model function related to the second and third spectral line regions and the absorbance intensity ratio of the two spectral line regions is selected. The second model function can be , C is the concentration, A 2 and A 3 are the absorbance intensities of the second and third spectral line regions, a 2 and b 2 is the calibration coefficient; if the concentration of the measured liquid is in the third concentration interval, a first model function related to the first spectral line region and the absorbance intensity of the spectral line region is selected, and the first model function can be , where C is the concentration, A 1 is the absorbance intensity of the first spectral line region, a 1 and b 1 is the calibration factor.

[0066] Step 302: When the concentration of the measured liquid is decreasing, if the concentration is in the fourth concentration interval, select the first spectral line area and the first model function; if the concentration is in the fifth concentration interval, select the second and third spectral line areas and the second model function; if the concentration is in the sixth concentration interval, select the fourth spectral line area and the third model function.

[0067] Specifically, if the concentration of the measured liquid has a decreasing trend and the concentration of the measured liquid is in the fourth concentration interval, a first model function related to the first spectral line region and the absorbance intensity of the spectral line region is selected. The first model function may be: , where C is the concentration, A 1 is the absorbance intensity of the first spectral line region, a 1 and b 1 is the calibration coefficient; if the concentration of the measured liquid is in the fifth concentration interval, a second model function related to the second and third spectral line regions and the absorbance intensity ratio of the two spectral line regions is selected. The second model function can be , C is the concentration, A 2 and A 3 are the absorbance intensities of the second and third spectral line regions, a 2 and b 2 is the calibration coefficient; if the concentration of the measured liquid is in the sixth concentration interval, the fourth spectral line region and the third model function related to the absorbance intensity of the spectral line region are selected, and the third model function can be , C is the concentration, A 4 is the absorbance intensity of the fourth spectral line region, a 3 and b 3 is the calibration factor.

[0068] In this embodiment, the most suitable spectral line area and the model function corresponding to the spectral line area are selected according to the concentration change trend and the concentration interval, which can improve the accuracy of concentration monitoring, make monitoring more flexible, optimize the use of resources, and improve analysis efficiency.

[0069] In one embodiment, the first model function is: ; The second model function is: ; The third model function is: ;

[0070] in, 、 、 is the concentration of the measured liquid, 、 、 、 、 is the calibration factor, 、 、 is the intercept coefficient, 、 、 、 The absorbance intensity integrals for the first, second, third and fourth spectral line regions respectively.

[0071] Specifically, if the concentration value of the measured liquid is within the low-range concentration monitoring range, the fourth spectral line region and the third model function related to the absorbance intensity of the spectral line region are selected: If the concentration of the liquid to be measured is within the mid-range concentration monitoring range, select the second model function related to the second and third spectral line regions and the absorbance intensity ratio of the two spectral line regions: If the concentration value of the measured liquid is within the high-range concentration monitoring range, the first spectral line region and the first model function related to the absorbance intensity of the spectral line region are selected: ;in, 、 、 is the concentration of the measured liquid, 、 、 、 、 is the calibration factor, 、 、 is the intercept coefficient, 、 、 、 The absorbance intensity integrals for the first, second, third and fourth spectral line regions respectively.

[0072] For example, in practical applications, 1 ,υ 2 ,υ 3 and 4 1206.6cm -1 、1441.23cm -1 、1639.41cm -1 、2478.85cm -1 , where υ 1 and 4 Heavy water (D 2 O) absorption line, υ 2 H 2 The absorption line of O, υ 3 is the absorption line of HDO. The mixture of heavy water and water has three forms due to the reaction of H2O+D2O↔2HDO, namely H 2 O、HDO、D 2 O, when the optical path length of the absorption cell is fixed, for low-range and high-range heavy water monitoring, since the HDO interference in the steady state is relatively small, υ 1 and 4 ; However, for mid-range heavy water, the error caused by HDO in the steady state is large, which affects both measurement and calibration, because the ratio of the absorbance of the two spectral lines is linearly related to the heavy water concentration ( Figure 4 As shown, R2=0.998), so the medium-range heavy water is measured with υ 2 and 3 As the selected spectral line region, the ratio of the absorbance of the two spectral lines is used as the absorbance intensity as the calibration curve. Figure 4 The horizontal axis is υ 2 and 3 The ratio of the absorbance of the spectral lines, the ordinate is D 2 The initial concentration of O.

[0073] In this embodiment, by having a corresponding model function for each high, medium and low range concentration monitoring range, and determining the corresponding calibration coefficient and intercept coefficient in each model function according to the corresponding range concentration detection range, it can cover the concentration detection range from low range to high range, thereby improving the adaptability of different concentrations, and each model function is determined according to its specific range, so that the result generation is more efficient and accurate.

[0074] In one embodiment, the schematic diagram of four measurement spectral lines is as follows: Figure 5 As shown, the horizontal axis is the wave number and the vertical axis is the absorbance intensity. The first spectral line area is: , the second spectral line region is: , the third spectral line region is: , the fourth spectral line region is: ,in, , , , are the wave numbers corresponding to the absorption peaks of the four spectral line regions, , , , , , , , It is related to the half-width at half-maximum of the corresponding infrared spectrum segment, specifically 3 / 5~3 / 4 of the corresponding half-width at half-maximum.

[0075] The integral calculation method of the absorbance intensity of the first, second, third and fourth spectral line regions is:

[0076] ,

[0077] in, is the system spectral response coefficient, is the original absorption intensity of the infrared beam, is the absorption intensity of the infrared beam passing through the target liquid; is the corresponding infrared spectrum segment, The value range is 1~4; It is the interference function of the target liquid temperature T and the pressure P in the object through which the target liquid flows on the measurement result.

[0078] Specifically, according to the given wave number , , , , and the half-width of the corresponding infrared line segment and Define four spectral line regions, namely: The first spectral line region is: , the second spectral line region is: , the third spectral line region is: , the fourth spectral line region is: .in, , , , are the wave numbers corresponding to the absorption peaks of the four spectral line regions, , , , , , , , It is related to the half-width at half-maximum of the corresponding infrared spectrum segment, specifically 3 / 5~3 / 4 of the corresponding half-width at half-maximum.

[0079] The integral calculation method of the absorbance intensity of the first, second, third and fourth spectral line regions is:

[0080] ,

[0081] in, is the system spectral response coefficient, which describes the spectrometer's ability to respond to different wave numbers. This coefficient affects the sensitivity and accuracy of the measurement; is the original absorption intensity of the infrared beam, that is, the intensity of the light emitted by the infrared light source without absorption by the target liquid; It is the absorption intensity of the infrared beam through the target liquid, that is, the intensity of the light that passes through the liquid after being absorbed by the target liquid; is the corresponding infrared spectrum segment, The value range is 1~4; is the interference function of the target liquid temperature T and the pressure P in the object through which the target liquid flows on the measurement result; , natural logarithm function, used to calculate the logarithm of the ratio of the original light intensity to the light intensity after passing through the liquid. This ratio reflects the attenuation of light when passing through the liquid and is the key to calculating absorbance; It means i The absorbance intensity integral of the spectral line region is i The value ranges from 1 to 4, corresponding to the first, second, third, and fourth spectral line regions respectively.

[0082] According to the concentration change trend and concentration range, select the corresponding model function: If the concentration value of the measured liquid is within the low-range concentration monitoring range, select the third model function related to the fourth spectral line area and the absorbance intensity of the spectral line area: If the concentration of the liquid to be measured is within the mid-range concentration monitoring range, select the second model function related to the second and third spectral line regions and the absorbance intensity ratio of the two spectral line regions: If the concentration value of the measured liquid is within the high-range concentration monitoring range, the first spectral line region and the first model function related to the absorbance intensity of the spectral line region are selected: The calculated absorption intensity is integrated Substitute i In the model function corresponding to the spectral line area, the concentration of the measured liquid in the corresponding range concentration detection range is calculated.

[0083] In this embodiment, by a given wave number , , , , and the half-width of the corresponding infrared spectral line segment and Defining four spectral line regions can more accurately capture the absorption characteristics within a specific wavenumber range and improve the accuracy of concentration monitoring. The calculation of absorbance intensity is standardized by integral calculation to make the data more comparable. System spectral response coefficient The introduction of the interference function enables the system to be optimized according to the spectral characteristics of different wave numbers, thus improving the sensitivity and accuracy of the analysis. The effects of temperature and pressure on the measurement results are taken into account, so that the system can provide accurate measurement results under different environmental conditions.

[0084] In one embodiment, Figure 6 As shown, determining the first interval set and the second interval set includes the following steps:

[0085] Step 601: Taking α times of the maximum concentration of the measured liquid that can be measured in the fourth spectral line region as the upper limit of the first target interval, and taking the minimum concentration of the measured liquid that can be measured in the second and third spectral line regions as the lower limit of the first target interval.

[0086] Specifically, two target intervals are set, and both target intervals are related to the optical path length L of the circulation cell, the instrument response coefficient η, the sample temperature T, and the pressure P in the circulation cell.

[0087] In the first target interval, the fourth spectral line region (with )Can measure the maximum measured liquid concentration C max,v4 α times of the first target interval as the upper limit; the second and third spectral line regions (with Calculation) can measure the minimum measured liquid concentration C min,v2 / v3 As the lower limit of the first target interval. That is, the first target interval is [C min,v2 / v3 , α C max,v4 ), where α is 0.65~0.75.

[0088] Step 602: The maximum concentration of the measured liquid that can be measured in the second and third spectral line regions is used as the upper limit of the second target interval, and β times the maximum concentration of the measured liquid that can be measured in the first spectral line region is used as the lower limit of the second target interval.

[0089] Specifically, in the second target interval, the second and third spectral line regions (with Calculation) can measure the maximum liquid concentration C max,v2 / v3 As the upper limit of the second target interval; the first spectral line area (with )Can measure the maximum measured liquid concentration C max,v1 β times of is taken as the lower limit of the second target interval. That is, the second target interval is [β C max,v1 , C max,v2 / v3 ), where β is 0.85~0.9.

[0090] Step 603: Determine each concentration interval in the first interval set and the second interval set according to the upper and lower limits of the first target interval and the upper and lower limits of the second target interval; wherein the upper and lower limits of the first target interval are used for switching between low-range concentration monitoring and mid-range concentration monitoring of the measured liquid, and the upper and lower limits of the second target interval are used for switching between mid-range concentration monitoring and high-range concentration monitoring of the measured liquid.

[0091] Specifically, the first target interval is related to the second, third, and fourth measurement selection spectral line areas; the second target interval is related to the first, second, and third measurement selection spectral line areas. Therefore, the upper and lower limits of the first target area are used for switching between low-range concentration detection and mid-range concentration monitoring of the measured liquid; the upper and lower limits of the second target interval are used for switching between mid-range concentration and high-range concentration monitoring of the measured liquid.

[0092] In this embodiment, by defining the upper and lower limits of the first target interval and the second target interval, it is possible to switch between low-range, medium-range and high-range concentration detection, ensuring accurate monitoring within each range of concentration detection. By defining intervals of α times and β times the maximum measured concentration, the measurement range is expanded to adapt to wider concentration changes.

[0093] In one embodiment, Figure 7 As shown, according to the upper and lower limits of the first target interval and the upper and lower limits of the second target interval, determining each concentration interval in the first interval set and the second interval set includes the following steps:

[0094] Step 701: determining a sixth concentration interval according to an upper limit of a first target interval, and determining a first concentration interval according to a lower limit of a first target interval;

[0095] Specifically, when the concentration of the measured liquid is in a downward trend, according to the upper limit α C of the first target interval max,v4 Determine the sixth concentration interval, and the range of the sixth concentration interval is [0, α C max,v4 ]. When the concentration of the measured liquid is on an upward trend, according to the lower limit of the first target interval C min,v2 / v3 Determine the first concentration interval, then the range of the first concentration interval is [0, C min,v2 / v3 ].

[0096] Step 702: determining a fourth concentration interval according to an upper limit of the second target interval, and determining a third concentration interval according to a lower limit of the second target interval;

[0097] Specifically, when the concentration of the measured liquid is in a downward trend, according to the upper limit C of the second target interval max,v2 / v3 Determine the fourth concentration interval, then the range of the fourth concentration interval is [C max,v2 / v3， 1]. When the concentration of the measured liquid is on an upward trend, according to the lower limit of the second target interval β C max,v1 Determine the third concentration interval, then the range of the third concentration interval is [β C max,v1 , 1].

[0098] Step 703: Determine a second concentration interval according to the first target interval lower limit and the second target interval lower limit, and determine a fifth concentration interval according to the first target interval upper limit and the second target interval upper limit.

[0099] Specifically, when the concentration of the measured liquid is on an upward trend, according to the lower limit C of the first target interval min,v2 / v3 and the lower limit of the second target interval β C max,v1 Determine the second concentration interval (C min,v2 / v3 , β C max,v1 ). When the concentration of the measured liquid is on a downward trend, according to the upper limit of the first target interval α C max,v4 and the upper limit of the second target interval C max,v2 / v3 Determine the fifth concentration interval (αC max,v4 , C max,v2 / v3 ).

[0100] In this embodiment, by clearly defining the boundaries of each concentration interval, different concentration ranges can be accurately distinguished, thereby achieving more sophisticated concentration monitoring and management. Through accurate interval division, the most appropriate analysis method can be selected for each interval, avoiding waste of resources and improving analysis efficiency. Each concentration interval corresponds to a specific model function and spectral line area, which can reduce measurement errors and improve the accuracy of measurement results.

[0101] Based on the same inventive concept, the present application embodiment also provides a first system for online analysis of heavy water concentration based on infrared spectroscopy, such as Figure 8 As shown, specifically, the first system for online analysis of heavy water concentration based on infrared spectroscopy includes: an infrared emitting device 81, an interferometer 82, a first reflector 83, a second reflector 84, a circulation pool 85, a detection device 86 and a control module.

[0102] The infrared emitting device 81 is configured to emit an infrared beam. A target solution flows in the circulation pool 85. The target solution contains at least H 2 O, D 2 O and HDO, the tested liquid is D 2O; wherein, the infrared light beam passes through the interferometer 82 to form interference light and is emitted, and is converged by the first reflector 83 and passes through the circulation cell. The infrared light beam passing through the circulation cell passes through the second reflector 84, and the intensity signal is detected by the detection device 86, so that an absorption spectrum is formed based on the intensity signal, and the control module is configured to execute the online analysis method of heavy water concentration in any of the above embodiments based on the absorption spectrum.

[0103] Specifically, the infrared emitting device 81 is used to emit an infrared beam, and the beam covers H 2 O, D 2 The infrared light beam is transmitted through the flow cell 85, and the target solution is circulated in the flow cell 85. The target solution includes at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O; a detection device 86, which detects the intensity signal of the infrared light beam after passing through the circulation cell, and these signals are used to form absorption spectra; a control module, which is used to control the operation of the entire system and execute the online analysis method of heavy water concentration in any of the above embodiments based on the absorption spectra. Wherein, the optical path of the circulation cell does not exceed 2mm, and is formed by crimping two infrared windows (such as calcium fluoride or zinc selenide), and has a liquid inlet and a liquid outlet.

[0104] In this embodiment, the interference light formed by the interferometer can provide high-resolution spectral data, thereby achieving D 2 High-precision measurement of O concentration. The control module automatically executes the concentration analysis method, reducing manual operations and improving the efficiency and accuracy of the analysis process. The absorption spectrum formed by the intensity signal detected by the detection device can provide rich spectral information, which is helpful for more accurate analysis of D 2 O concentration. The integrated system design makes operation easier, maintenance and calibration.

[0105] Based on the same inventive concept, the present application embodiment also provides a second system for online analysis of heavy water concentration based on infrared spectroscopy, such as Fig. 9 As shown, specifically, the second system for online analysis of heavy water concentration based on infrared spectroscopy includes: an infrared emitting device 91, a first reflector 92, a second reflector 93, a circulation pool 94, a beam splitter 95, a first filtering device 96, a second filtering device 97, a first detection device 98, a second detection device 99 and a control module.

[0106] The infrared emitting device 91 is configured to emit an infrared beam. A target solution flows in the circulation pool, and the target solution contains at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O; the infrared light beam is converged by the first reflector 92 and passes through the circulation pool 94. After the infrared light beam is converged, the direction is adjusted by the second reflector 93 to become a parallel light beam, and passes through the beam splitter 95; wherein, the first band and the second band obtained after vertical transmission through the beam splitter are time-division multiplexed by the first filtering device 96, and the intensity signals of the first band and the second band are detected by the first detection device 98; the third band and the fourth band obtained after reflection by the beam splitter are time-division multiplexed by the second filtering device 97, and the intensity signals of the third band and the fourth band are detected by the second detection device 99, so that an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands, and the control module is configured to perform the online analysis method of heavy water concentration in any of the above embodiments based on the absorption spectrum.

[0107] Specifically, the infrared emitting device 91 is used to emit an infrared beam, and the beam covers H 2 O, D 2 The first reflector 92 converges the infrared beam to ensure that the beam passes through the center of the flow cell; the second reflector 93 adjusts the direction of the infrared beam after passing through the flow cell to make it a parallel beam; the flow cell 94 has a target solution flowing therein, which includes at least H 2 O, D 2 O and HDO, the tested liquid is D 2 O; a beam splitter 95, which splits the parallel light beam passing through the second reflector into different bands, wherein the first band and the second band are obtained after vertical transmission through the beam splitter, and the third band and the fourth band are obtained after reflection from the beam splitter; a first filtering device 96, which is used for time-division multiplexing of the light beams of the first band and the second band; a second filtering device 97, which is used for time-division multiplexing of the light beams of the third band and the fourth band; a first detection device 98, which detects the intensity signals of the first band and the second band; a second detection device 99, which detects the intensity signals of the third band and the fourth band; an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands; and the control module is configured to execute the online analysis method for the heavy water concentration of any of the above-mentioned embodiments based on the absorption spectrum.

[0108] It should be noted that time division multiplexing is a communication technology that allows multiple signals to share the same communication channel in different time intervals, and each signal is transmitted in its own time "time slot", thereby improving channel utilization. In this embodiment, the time division multiplexing technology enables the first and second filtering devices to respectively detect light beam intensity signals of different bands in different time slices, so that the first and second detection devices can sequentially receive and measure signals of different bands to form absorption spectra and analyze the concentration of heavy water, thereby improving the efficiency and accuracy of spectral analysis.

[0109] In this embodiment, the system divides the infrared beam into four bands through a beam splitter, so that the spectral information of multiple bands can be analyzed simultaneously, which improves the comprehensiveness and depth of the analysis. Through the time-sharing multiplexing of different bands by the first filtering device and the second filtering device, the system can provide higher-resolution spectral data, thereby improving D 2 The first detection device and the second detection device detect the intensity signals of different bands respectively, so that the system can more accurately capture the absorption characteristics of the target solution. The optical path design of the first reflector and the second reflector ensures that the infrared light beam can effectively pass through the flow cell and be received by the detection device, thereby improving the light efficiency of the system. The control module automatically performs the online analysis method of heavy water concentration, reducing manual operations and improving the efficiency and accuracy of the analysis process.

[0110] Based on the same inventive concept, the present application embodiment also provides a third system for online analysis of heavy water concentration based on infrared spectroscopy, such as Fig.10 As shown, specifically, the third system for online analysis of heavy water concentration based on infrared spectroscopy includes: an infrared emitting device 101, an attenuated total reflection device 102, a beam splitter 103, a first filtering device 104, a second filtering device 105, a first detection device 106, a second detection device 107 and a control module.

[0111] The infrared emitting device 101 is configured to emit an infrared beam. A target solution flows through the attenuated total reflection device 102. The target solution contains at least H 2 O, D 2O and HDO, the measured liquid is D2O; the infrared light beam enters the attenuated total reflection device, forms total reflection with the target solution and then emits, and passes through the beam splitter 103; wherein, the first band and the second band obtained after vertical transmission through the beam splitter are time-division multiplexed by the first filtering device 104, and the intensity signals of the first band and the second band are detected by the first detection device 106; the third band and the fourth band obtained after reflection from the beam splitter are time-division multiplexed by the second filtering device 105, and the intensity signals of the third band and the fourth band are detected by the second detection device 107, so that an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands, and the control module is configured to execute the online analysis method for heavy water concentration of any of the above embodiments based on the absorption spectrum.

[0112] Specifically, the infrared emitting device 101 is used to emit an infrared beam, and the beam covers H 2 O, D 2 O and HDO absorption lines; attenuated total reflection device 102, such as Fig.11 As shown, a special optical device comprises a liquid inlet and a liquid outlet, wherein a target solution flows therein, and is used to realize total reflection interaction between a light beam and the target solution, wherein the incident light is an infrared light beam, and the outgoing light is a light beam emitted after total reflection with the target solution; a beam splitter 103 divides the light beam emitted from the attenuated total reflection device into different bands, wherein the first band and the second band are obtained after vertical transmission through the beam splitter, and the third band and the fourth band are obtained after reflection from the beam splitter; a first filtering device 104 is used for time-division multiplexing of the light beams of the first band and the second band; a second filtering device 105 is used for time-division multiplexing of the light beams of the third band and the fourth band; a first detection device 106 is used for detecting intensity signals of the first band and the second band; a second detection device 107 is used for detecting intensity signals of the third band and the fourth band; an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands; and a control module is configured to execute the online analysis method for the concentration of heavy water of any of the above embodiments based on the absorption spectrum.

[0113] In this embodiment, the system can realize the detection of D in the target solution by using the attenuated total reflection technology. 2 High-sensitivity detection of O, because total reflection enhances the interaction between light and solution. The system divides the infrared beam into four bands through a beam splitter, making it possible to analyze the spectral information of multiple bands at the same time, improving the comprehensiveness and depth of the analysis. Through the time-sharing multiplexing of different bands by the first filtering device and the second filtering device, the system can provide higher-resolution spectral data, thereby improving D 2The first detection device and the second detection device detect the intensity signals of different bands respectively, so that the system can more accurately capture the absorption characteristics of the target solution. After the infrared beam passes through the attenuated total reflection device, it is divided into different bands by the beam splitter. Such an optical path design ensures the effective use and detection of the beam. The control module automatically executes the online analysis method of heavy water concentration, which reduces manual operation and improves the efficiency and accuracy of the analysis process.

[0114] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. An on-line analysis method for heavy water concentration based on infrared spectroscopy, characterized in that: The method comprises: Acquire an absorption spectrum formed after the infrared light beam passes through a target solution, and determine the concentration information of the measured liquid based on the absorption spectrum, wherein the target solution contains at least three forms of H2O, D2O and HDO, and the measured liquid is D2O; According to the concentration information of the measured liquid, a spectral line region and a model function corresponding to the concentration information are selected; wherein, by selecting four adjacent spectral line segments from the absorption spectrum, and determining four adjacent spectral line regions based on the four spectral line segments, namely a first spectral line region, a second spectral line region, a third spectral line region and a fourth spectral line region, the absorbance intensity peak value of the fourth spectral line region is greater than the first, second and third spectral line regions; if the corresponding concentration value in the concentration information belongs to high-range concentration monitoring, the first spectral line region and the first model function related to the absorbance intensity of the spectral line region are selected; if it belongs to mid-range concentration monitoring, the second and third spectral line regions and the second model function related to the ratio of the absorbance intensities of the two spectral line regions are selected; if it belongs to low-range concentration monitoring, the fourth spectral line region and the third model function related to the absorbance intensity of the spectral line region are selected; The concentration of the measured liquid is determined according to the corresponding model function and the absorbance intensity of the corresponding spectral line area; the first model function is: ; The second model function is: ; The third model function is: ; 、 、 is the concentration of the measured liquid, 、 、 、 、 is the calibration factor, 、 、 is the intercept coefficient, 、 、 、 The absorbance intensity integrals for the first, second, third and fourth spectral line regions respectively.

2. The method for online analysis of heavy water concentration according to claim 1, characterized in that: Determining the concentration information of the measured liquid based on the absorption spectrum includes: determining the concentration change trend and the concentration interval of the measured liquid based on the absorption spectrum; wherein the concentration change trend includes rising and falling, if the concentration change trend is rising and the concentration interval is a concentration interval in a first interval set, the first interval set includes a first concentration interval, a second concentration interval and a third concentration interval, and any value in the second concentration interval is greater than a value in the first concentration interval and less than a value in the third concentration interval; if the concentration change trend is falling and the concentration interval is a concentration interval in the second interval set, the second interval set includes a fourth concentration interval, a fifth concentration interval and a sixth concentration interval, and any value in the fifth concentration interval is less than a value in the fourth concentration interval and greater than a value in the sixth concentration interval; According to the monitoring range of the measured liquid, a model function and a spectral line area corresponding to the monitoring range are selected, including: according to the concentration change trend and the concentration range of the measured liquid, a model function and a spectral line area corresponding to the concentration change trend and the concentration range are selected.

3. The method for online analysis of heavy water concentration according to claim 2, characterized in that: According to the concentration variation trend and the concentration interval of the measured liquid, a model function and a spectral line region corresponding to the concentration variation trend and the concentration interval are selected, including: When the concentration of the measured liquid is rising, if the concentration is in the first concentration interval, the fourth spectral line area and the third model function are selected; if the concentration is in the second concentration interval, the second and third spectral line areas and the second model function are selected; if the concentration is in the third concentration interval, the first spectral line area and the first model function are selected; When the concentration of the measured liquid is decreasing, if the concentration is in the fourth concentration interval, the first spectral line area and the first model function are selected; if the concentration is in the fifth concentration interval, the second and third spectral line areas and the second model function are selected; if the concentration is in the sixth concentration interval, the fourth spectral line area and the third model function are selected.

4. The method for online analysis of heavy water concentration according to claim 1, characterized in that: The first spectral line region is: , the second spectral line region is: , the third spectral line region is: , the fourth spectral line region is: ,in, , , , are the wave numbers corresponding to the absorption peaks of the four spectral line regions, , , , , , , , It is related to the half-height width of the corresponding infrared spectrum line segment, specifically 3 / 5~3 / 4 of the corresponding half-height width; The absorbance intensity integral calculation method of the first, second, third and fourth spectral line regions is: ， in, is the system spectral response coefficient, is the original absorbance intensity of the infrared beam, is the absorption intensity of the infrared light beam passing through the target liquid; is the corresponding infrared spectrum segment, The value range is 1~4; It is the interference function of the target liquid temperature T and the pressure P in the object through which the target liquid flows on the measurement result.

5. The method for online analysis of heavy water concentration according to claim 2, characterized in that: Determining the first interval set and the second interval set includes: The upper limit of the first target interval is α times the maximum concentration of the measured liquid that can be measured by the fourth spectral line area, and the lower limit of the first target interval is the minimum concentration of the measured liquid that can be measured by the second and third spectral line areas; The maximum concentration of the measured liquid that can be measured by the second and third spectral line regions is used as the upper limit of the second target interval, and β times the maximum concentration of the measured liquid that can be measured by the first spectral line region is used as the lower limit of the second target interval; According to the upper and lower limits of the first target interval and the upper and lower limits of the second target interval, each concentration interval in the first interval set and the second interval set is determined; wherein the upper and lower limits of the first target interval are used for switching between low-range concentration monitoring and mid-range concentration monitoring of the measured liquid, and the upper and lower limits of the second target interval are used for switching between mid-range concentration monitoring and high-range concentration monitoring of the measured liquid.

6. The method for online analysis of heavy water concentration according to claim 5, characterized in that: Determining each concentration interval in the first interval set and the second interval set according to the upper limit and the lower limit of the first target interval and the upper limit and the lower limit of the second target interval, including: Determine the sixth concentration interval according to the upper limit of the first target interval, and determine the first concentration interval according to the lower limit of the first target interval; Determine the fourth concentration interval according to the upper limit of the second target interval, and determine the third concentration interval according to the lower limit of the second target interval; The second concentration interval is determined according to the first target interval lower limit and the second target interval lower limit, and the fifth concentration interval is determined according to the first target interval upper limit and the second target interval upper limit.

7. An online analysis system for heavy water concentration based on infrared spectroscopy, characterized in that: The system includes an infrared emitting device, an interferometer, a first reflector, a second reflector, a circulation cell, a detection device and a control module; The infrared emitting device is configured to emit an infrared beam, a target solution flows in the circulation cell, the target solution contains at least three forms of H2O, D2O and HDO, and the measured liquid is D2O; wherein the infrared beam passes through the interferometer to form interference light and is emitted, and is converged by the first reflector and passes through the circulation cell, the infrared beam passing through the circulation cell passes through the second reflector, and an intensity signal is detected by the detection device, so that an absorption spectrum is formed based on the intensity signal, and the control module is configured to perform the online analysis method for heavy water concentration according to any one of claims 1 to 6 based on the absorption spectrum.

8. An online analysis system for heavy water concentration based on infrared spectroscopy, characterized in that: The system comprises an infrared emitting device, a first reflector, a second reflector, a circulation pool, a beam splitter, a first filtering device, a second filtering device, a first detection device, a second detection device and a control module; The infrared emitting device is configured to emit an infrared beam, a target solution flows in the circulation pool, the target solution contains at least three forms of H2O, D2O and HDO, and the measured liquid is D2O; the infrared beam is converged by the first reflector and passes through the circulation pool, and the direction of the infrared beam is adjusted by the second reflector after convergence to become a parallel beam, and passes through the beam splitter; wherein the first band and the second band obtained after vertical transmission through the beam splitter are time-division multiplexed by the first filtering device, and the intensity signals of the first band and the second band are detected by the first detection device; the third band and the fourth band obtained after reflection by the beam splitter are time-division multiplexed by the second filtering device, and the intensity signals of the third band and the fourth band are detected by the second detection device, so that an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands, and the control module is configured to perform the online analysis method of heavy water concentration according to any one of claims 1 to 6 based on the absorption spectrum.

9. An online analysis system for heavy water concentration based on infrared spectroscopy, characterized in that: The system includes an infrared emitting device, an attenuated total reflection device, a beam splitter, a first filtering device, a second filtering device, a first detection device, a second detection device and a control module; The infrared emitting device is configured to emit an infrared beam, a target solution flows in the attenuated total reflection device, the target solution contains at least three forms of H2O, D2O and HDO, and the measured liquid is D2O; the infrared beam enters the attenuated total reflection device, forms total reflection with the target solution, and then is emitted and passes through a beam splitter; wherein the first band and the second band obtained after vertical transmission through the beam splitter are time-division multiplexed by the first filtering device, and the intensity signals of the first band and the second band are detected by the first detection device; the third band and the fourth band obtained after reflection from the beam splitter are time-division multiplexed by the second filtering device, and the intensity signals of the third band and the fourth band are detected by the second detection device, so that an absorption spectrum is formed based on the intensity signals of the first, second, third and fourth bands, and the control module is configured to perform the online analysis method for heavy water concentration according to any one of claims 1 to 6 based on the absorption spectrum.

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