Method and system for adsorbing and separating Kr by activated carbon for TCD gas chromatography

Abstract

The invention relates to the technical field of chromatographic analysis, in particular to a TCD gas chromatography activated carbon adsorption separation method and system for Kr. The method comprises the steps that the difference between a first characteristic value of current gas at all temperatures and the maximum value in the first characteristic values of the current gas at all temperatures is compared; determining a second characteristic value according to the difference between the spectrum peak area of the current gas chromatography at each temperature and the maximum spectrum peak area; and determining a likelihood function when the krypton proportion in the current gas is equal to the krypton proportion in each gas sample by analyzing the similarity of the chromatography between the current gas and each gas sample at each temperature and the difference of the second characteristic values, so as to obtain the related krypton content for evaluating the adsorption separation effect of the active carbon in the current gas. The interference of xenon to krypton separation detection is solved, and the precision of krypton separation detection for TCD gas chromatography is improved.

Description

Technical Field

[0001] The present application relates to the technical field of chromatography analysis, and in particular to a method and system for separating Kr by activated carbon adsorption using TCD gas chromatography. Background Art

[0002] During the normal operation of nuclear power plants, the concentration detection of inert gases (such as krypton, xenon, etc.) in gaseous effluents is an important part of determining their annual emissions. Although these inert gases are chemically stable, they may pose a potential threat to human health and the environment due to their radioactive characteristics. Long-term accumulation of radioactive substances may even pollute the surrounding environment and destroy the ecological balance. Therefore, the detection of inert gas concentration is necessary to ensure that nuclear power plant emissions meet international and national safety standards.

[0003] Among the inert gas nuclides emitted by nuclear power plants, the half-life of 85Kr is as long as 10.756 years, which is significantly higher than other nuclides. Accurately detecting the concentration of 85Kr and counting the emission of 85Kr are crucial for dose estimation in nuclear power plant operation. At present, TCD gas chromatography is a commonly used inert gas detection method in nuclear power plants. It separates and quantitatively analyzes the target gas through the difference in thermal conductivity of different gases. However, this method has limitations. Among the inert gases emitted by nuclear power plants, krypton (Kr) and xenon (Xe) have similar properties and often appear mixed, making it difficult to separate them effectively, thereby reducing the accuracy of krypton separation detection. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a method and system for TCD gas chromatography activated carbon adsorption separation of Kr. The technical solutions adopted are as follows: In a first aspect, the present application provides a method for separating Kr by TCD gas chromatography activated carbon adsorption, the method comprising the following steps: Obtaining the TCD gas chromatogram and its peak area after the current gas chromatogram separation at different preset temperatures, and recording the TCD gas chromatogram as chromatogram; Determine the first characteristic value of the current gas at each temperature by analyzing the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the average level of all chromatographic data in its neighborhood; determine the second characteristic value of the current gas at each temperature by comparing the difference between the first characteristic value of the current gas at each temperature and the maximum value of the first characteristic value of the current gas at all temperatures, and the difference between the spectral peak area of ​​the chromatogram of the current gas at each temperature and the maximum value of the spectral peak area at all temperatures; A preset number of gas samples containing different proportions of krypton are prepared at each temperature, and a first similarity index between the current gas and the various gas samples at each temperature is determined by analyzing the similarity of the chromatograms between the current gas and the various gas samples at each temperature; a second similarity index between the current gas and the various gas samples at each temperature is determined based on the difference in the second characteristic value between the current gas and the various gas samples at each temperature, and the likelihood probability when the proportion of krypton in the current gas is equal to the proportion of krypton in the various gas samples at each temperature is determined in combination with the first similarity index, so as to determine the likelihood function when the proportion of krypton in the current gas is equal to the proportion of krypton in the various gas samples; Based on the likelihood function, the relevant krypton content for evaluating the adsorption and separation effect of activated carbon in the current gas is obtained.

[0005] Preferably, the method for determining the first characteristic value of the current gas at each temperature is: The square value of the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the mean value of all chromatographic data in its neighborhood is calculated, and the square value of all chromatographic data in the chromatogram of the current gas is averaged as the first characteristic value of the current gas at each temperature.

[0006] Preferably, the expression of the second characteristic value of the current gas at each temperature is: ; In the formula, Indicates the second characteristic value of the current gas at temperature t; , Respectively represent the first characteristic value of the current gas at temperature t and the spectral peak area of ​​the chromatogram of the current gas; , They respectively represent the maximum value of the first characteristic value of the current gas at all temperatures and the maximum value of the spectral peak area of ​​the current gas chromatogram.

[0007] Preferably, the step of preparing a preset number of gas samples containing krypton in different proportions at various temperatures comprises: At each temperature, the ratio of krypton in the initial gas sample is prepared to be a preset value, and the preset ratio of krypton is successively increased based on the preset value to obtain gas samples with different krypton ratios until a preset number of gas samples with different krypton ratios are reached.

[0008] Preferably, the first similarity index between the current gas and various gas samples at each temperature is a normalized result of the cosine similarity of the chromatograms between the current gas and various gas samples at each temperature.

[0009] Preferably, the second similarity index between the current gas and various gas samples at each temperature is an exponential function value with a natural constant as the base and the inverse of the second eigenvalue difference between the current gas and various gas samples at each temperature as the independent variable.

[0010] Preferably, the likelihood probability when the krypton ratio in the current gas at each temperature is equal to the krypton ratio in various gas samples is: the normalized value of the product of the first similarity index and the second similarity index between the current gas and various gas samples at each temperature.

[0011] Preferably, the expression of the likelihood function when the krypton ratio in the current gas is equal to the krypton ratio in various gas samples is: ; Indicates that the krypton ratio in the current gas is equal to The likelihood function of the krypton ratio in the gas sample; Indicates that the proportion of krypton in the current gas at temperature t is equal to The likelihood function of the krypton ratio in the gas sample is given by: T represents the total number of preset different temperatures.

[0012] Preferably, the obtaining of the relevant krypton content for evaluating the activated carbon adsorption and separation effect in the current gas includes: The total volume of the current gas and the content of 85Kr in krypton are obtained, the proportion of krypton when the likelihood function takes the maximum value is taken as the proportion of krypton in the current gas, the product of the proportion of krypton and the total volume is taken as the total krypton gas volume, the total krypton gas volume in the current gas is multiplied by the content of 85Kr in krypton and divided by the total gas volume to obtain the concentration of 85Kr in the current gas, which is used to evaluate the activated carbon adsorption and separation effect in the current gas.

[0013] In the second aspect, an embodiment of the present application also provides a system for TCD gas chromatography activated carbon adsorption separation of Kr, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned methods for TCD gas chromatography activated carbon adsorption separation of Kr are implemented.

[0014] This application has at least the following beneficial effects: This application constructs a first eigenvalue by performing chromatographic analysis at different temperatures and comparing the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the average level of all chromatographic data in its neighborhood, accurately reflecting the degree of fluctuation of the chromatographic data at different temperatures, and helping to identify and analyze small changes in chromatographic peaks, thereby reducing detection errors caused by data instability and improving data reliability; further, by analyzing the similarity of the chromatogram between the current gas and various gas samples at each temperature and the difference in the second eigenvalue, the first similarity index and the second similarity index are constructed respectively, improving the accuracy and reliability of the maximum likelihood estimation, thereby improving the accuracy of krypton separation detection. This application uses a maximum likelihood estimation algorithm for krypton separation detection based on the separation characteristics of krypton and xenon at different temperatures, reducing the influence of xenon on krypton separation detection, and thereby improving the accuracy of krypton separation detection for TCD gas chromatography. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A flowchart of the steps of a method for separating Kr by TCD gas chromatography activated carbon adsorption provided in one embodiment of the present application; Figure 2 A likelihood function construction framework diagram provided for one embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of the method and system for TCD gas chromatography activated carbon adsorption separation of Kr proposed in the present application, its specific implementation method, structure, characteristics and effects in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0019] The specific scheme of the method and system for TCD gas chromatography activated carbon adsorption separation of Kr provided by the present application is described in detail below with reference to the accompanying drawings.

[0020] See also Figure 1 , which shows a flow chart of the steps of a method for TCD gas chromatography activated carbon adsorption separation of Kr provided in one embodiment of the present application, the method comprising the following steps: Step S1: obtaining a thermal conductivity detector gas chromatogram and its spectral peak area after the current gas chromatogram separation at different preset temperatures, and recording the thermal conductivity detector gas chromatogram as a chromatogram.

[0021] (1) Adsorption separation process During the normal operation of a nuclear power plant, the gaseous effluent discharged from the nuclear power plant is collected in a sampling tank, and the sampling volume of the gas in the sampling tank is obtained by a high-precision gas flow meter.

[0022] Pre-removal of impurities is an important step in the process of separating krypton. Water and carbon dioxide will freeze at low temperatures, affecting the subsequent krypton enrichment and separation effect. In addition, carbon dioxide will interfere with the adsorption of krypton by activated carbon, reducing the enrichment efficiency.

[0023] The pre-impurity removal unit of this embodiment uses an impurity removal tank composed of silica gel and alumina to remove moisture and carbon dioxide from the gas in the sampling tank to prevent ice from clogging the pipeline at ultra-low temperatures.

[0024] This embodiment uses a vacuum sampling method to send the gas from the pre-impurity removal unit into the enrichment unit. Compared with positive pressure sampling, vacuum sampling saves time and does not introduce additional helium, thereby reducing the interference of impurity gases.

[0025] When using a liquid scintillation spectrometer to detect the beta rays emitted by 85Kr decay in the air, because its radioactivity concentration is too low, it is necessary to enrich and separate the 85Kr in the air before measuring. At the same time, the detection limit of the TCD detector is high, and the krypton in the gas also needs to be enriched.

[0026] In this embodiment, the krypton enrichment unit consists of a primary enrichment unit and a secondary enrichment unit. Considering that low-temperature activated carbon adsorption has the advantages of simple operation, high safety, and small size, the primary enrichment unit and the secondary enrichment unit of this embodiment both use low-temperature activated carbon adsorption to enrich krypton in the gas.

[0027] The adsorption temperature of the primary enrichment unit is -196 degrees Celsius, and the primary adsorption column delivers the gas to the enrichment unit through the activated carbon adsorption pre-impurity removal unit. Activated carbon has a strong adsorption capacity for krypton, but it also has a certain adsorption capacity for oxygen and nitrogen at low temperatures, so a low-temperature separation step is required to remove these impurities. The separation temperature of the primary enrichment unit is -100 degrees Celsius, and the primary adsorption column is heated to -100 degrees Celsius to remove the oxygen and nitrogen adsorbed by the primary adsorption column. The desorption temperature of the primary enrichment unit is 0 degrees Celsius, and the primary adsorption column is heated to 0 degrees Celsius to desorb the adsorbed krypton, and the desorbed gas is purged to the secondary enrichment unit. The activation temperature of the primary enrichment unit is 300 degrees Celsius, and the primary adsorption column is heated to 300 degrees Celsius under the protective atmosphere of helium to improve the adsorption performance of the activated carbon to ensure the subsequent enrichment efficiency of krypton in the gas.

[0028] In order to improve the purity and enrichment efficiency of krypton, the present embodiment sets a secondary enrichment unit to perform low-temperature adsorption on the gas. Compared with single-stage enrichment, multi-stage enrichment can more effectively remove impurity gases, reduce the total volume of gas entering the chromatographic column, and avoid the gas processing volume being too large, resulting in a decrease in the separation ability of the subsequent chromatographic column for krypton. The adsorption temperature of the secondary enrichment unit is -196 degrees Celsius, and the secondary adsorption column adsorbs the gas desorbed from the primary enrichment unit through activated carbon adsorption. The separation temperature of the secondary enrichment unit is -100 degrees Celsius, and the secondary adsorption column is heated to -100 degrees Celsius to further remove the oxygen and nitrogen adsorbed by the secondary adsorption column. The desorption temperature of the secondary enrichment unit is 0 degrees Celsius, and the secondary adsorption column is heated to 0 degrees Celsius to desorb the adsorbed krypton, and the desorbed gas is purged to the separation unit, and the activation temperature of the secondary enrichment unit is 300 degrees Celsius.

[0029] In this embodiment, both the primary adsorption column and the secondary adsorption column use activated carbon with a mesh size of 80-100, and the purge gas uses 99.99% helium.

[0030] (2) Data collection Since Kr and Xe have similar properties, it is difficult to effectively separate the two by activated carbon adsorption, and xenon is still mixed in the gas treated by the enrichment unit. Therefore, this embodiment uses chromatographic separation to separate krypton and xenon.

[0031] On the one hand, the specific activity of 133Xe in the inert gas discharged from nuclear power plants accounts for a relatively high proportion, which cannot be ignored when measuring 85Kr by liquid scintillation spectrometry. On the other hand, the thermal conductivity of xenon mixed in the gas is different from that of krypton, which will introduce additional errors when the TCD detector separates and detects krypton, thus affecting the accuracy of calculating the 85Kr content in the sampled gas.

[0032] Taking into account the difference in boiling points between krypton and xenon, krypton and xenon are separated at different column temperatures, and the TCD gas chromatogram and its spectral peak area after the current gas chromatographic separation at different preset temperatures are obtained. In order to simplify the representation, the TCD gas chromatogram is recorded as a chromatogram. By analyzing the chromatographic information separated at different temperatures, the reliability of subsequent krypton separation detection can be improved.

[0033] In this embodiment, the chromatographic separation column temperature, that is, the preset different temperatures are set to: -90°C, -100°C, -110°C, -120°C, -130°C. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0034] Step S2: By comparing the similarities and differences of the current gas chromatograms at different temperatures, the krypton content in the current gas is detected using maximum likelihood estimation.

[0035] The difference in thermal conductivity between residual xenon and krypton introduces errors in the process of krypton separation detection by comparing the TCD detector with the standard krypton chromatogram, reducing the accuracy of krypton separation detection. This embodiment uses the chromatographic data under 5 column temperature separations as the comparison information for krypton separation detection based on the separation characteristics of krypton and xenon at different column temperatures, and uses the maximum likelihood estimation algorithm to separate and detect krypton in the gas sent to the separation unit, thereby reducing the influence of mixed xenon on the krypton separation detection of the TCD detector. The specific process is as follows: S201: Determine the first characteristic value of the current gas at each temperature by analyzing the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the average level of all chromatographic data in its neighborhood; determine the second characteristic value of the current gas at each temperature by comparing the difference between the first characteristic value of the current gas at each temperature and the maximum value of the first characteristic value of the current gas at all temperatures, as well as the difference between the spectral peak area of ​​the chromatogram of the current gas at each temperature and the maximum value of the spectral peak area at all temperatures.

[0036] In chromatographic analysis, the fluctuation of chromatographic data will increase due to the presence of xenon. The density difference between krypton and xenon is significant. At the same time, due to the difference in thermal conductivity, the interference of xenon will cause the shape and area of ​​the chromatographic peak to change, thereby affecting the separation and detection accuracy of krypton. Therefore, this embodiment determines the first characteristic value of the current gas at each temperature by analyzing the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the average level of all chromatographic data in its neighborhood; compares the difference between the first characteristic value of the current gas at each temperature and the maximum value of the first characteristic value of the current gas at all temperatures, as well as the difference between the spectral peak area of ​​the chromatogram of the current gas at each temperature and the maximum value of the spectral peak area at all temperatures, to determine the second characteristic value of the current gas at each temperature, so as to quantify the degree of fluctuation of the chromatographic data. The specific process is as follows: (1) In order to reduce the influence of random noise and retain the information of neighboring chromatographic data to reflect the interference of xenon on krypton separation detection, the first characteristic value of the current gas at each temperature is determined by analyzing the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the average level of all chromatographic data in its neighborhood, specifically: A neighborhood W is divided with each chromatographic data in the chromatogram as the center, and the square value of the deviation between each chromatographic data in the chromatogram of the current gas and the mean value of all chromatographic data in its neighborhood is calculated at each temperature. The square value of all chromatographic data in the chromatogram of the current gas is averaged as the first eigenvalue of the current gas at each temperature, which is used to characterize the fluctuation degree of the chromatographic data. The larger the first eigenvalue, the greater the deviation between the chromatographic data and the mean value of the chromatographic data in its neighborhood, indicating that the greater the fluctuation degree of the chromatographic data in the local range, the greater the possibility that the chromatographic data is interfered by noise.

[0037] It should be noted that the value of the radius of the neighborhood W is artificially set. In this embodiment, the value of the radius of the neighborhood W is 1. In actual application, the implementer can also set it by himself according to the specific situation. This embodiment does not impose any special restrictions.

[0038] In addition, it should be understood that there are many methods for measuring the deviation between data. In this embodiment, the difference between each chromatographic data in the chromatogram of the current gas at each temperature and the mean of all chromatographic data in its neighborhood is used as the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the mean of all chromatographic data in its neighborhood. In actual application, the implementer may also adopt other methods for measuring the deviation between data, such as ratio, according to specific circumstances. This embodiment does not impose any special restrictions on the selection of methods for measuring the deviation between data.

[0039] (2) Further, the difference between the first characteristic value of the current gas at each temperature and the maximum value of the first characteristic value of the current gas at all temperatures, as well as the difference between the spectral peak area of ​​the chromatogram of the current gas at each temperature and the maximum value of the spectral peak area at all temperatures are compared to determine the second characteristic value of the current gas at each temperature, specifically: The presence of residual xenon will increase the interference of the TCD detector in detecting the krypton content. The greater the residual xenon content, the greater the interference, and the greater the fluctuation characteristics of the corresponding chromatogram. Due to the additional thermal conductivity of xenon, the presence of residual xenon will not only increase the interference, but also affect the chromatogram peak area. The larger the spectral peak area, the greater the residual xenon content. Therefore, by analyzing the difference between the first characteristic value and the maximum first characteristic value at each temperature, and the difference between the spectral peak area and the maximum spectral peak area, the second characteristic value is determined, specifically: The second characteristic value of the current gas at temperature t The expression is: ; In the formula, , Respectively represent the first characteristic value of the current gas at temperature t and the spectral peak area of ​​the chromatogram of the current gas; , They respectively represent the maximum value of the first characteristic value of the current gas at all temperatures and the maximum value of the spectral peak area of ​​the current gas chromatogram.

[0040] According to the second characteristic value of the current gas at each temperature, it can be understood that the second characteristic value is used to characterize the degree of fluctuation of the chromatogram. The greater the content of residual xenon, the greater the interference caused to the chromatogram data, and the greater the fluctuation degree of the corresponding chromatogram. If the ratio between the first characteristic value of the current gas at temperature t and the maximum value of the first characteristic value of the current gas at all temperatures is larger, it means that the chromatogram fluctuation is more serious and the interference is greater. Moreover, the greater the ratio between the peak area of ​​the chromatogram of the current gas at temperature t and the maximum value of the peak area of ​​the chromatogram of the current gas, it means that the content of residual xenon is greater, the chromatogram is more interfered by the residual xenon, and the second characteristic value finally obtained is larger. On the contrary, if the ratio between the first characteristic value of the current gas at temperature t and the maximum value of the first characteristic value of the current gas at all temperatures is smaller, it means that the chromatogram has not fluctuated or fluctuated slightly, and the interference is smaller, and the ratio between the peak area of ​​the chromatogram of the current gas at temperature t and the maximum value of the peak area of ​​the chromatogram of the current gas is smaller, it means that the content of residual xenon is smaller, the chromatogram is less interfered by residual xenon, and the final second characteristic value is smaller, indicating that the degree of chromatographic fluctuation is smaller. At this time, it means that the purity of the krypton separated at this time is higher.

[0041] S202: Prepare a preset number of gas samples containing different proportions of krypton at each temperature, and determine a first similarity index between the current gas and the various gas samples at each temperature by analyzing the similarity of the chromatography between the current gas and the various gas samples at each temperature; determine a second similarity index between the current gas and the various gas samples at each temperature based on the difference in second eigenvalues ​​between the current gas and the various gas samples at each temperature, and determine the likelihood probability when the krypton proportion in the current gas is equal to the krypton proportion in the various gas samples at each temperature in combination with the first similarity index, so as to determine a likelihood function when the krypton proportion in the current gas is equal to the krypton proportion in the various gas samples.

[0042] (1) Preset numbers of gas samples containing different proportions of krypton are prepared at various temperatures. Specifically, at various temperatures, the proportion of krypton in the initial gas sample is a preset value, and the proportion of krypton is increased sequentially based on the preset value to obtain gas samples with different proportions of krypton, until a preset number of gas samples with different proportions of krypton are obtained.

[0043] It should be noted that the preset value, preset ratio and preset quantity are all manually set. In this embodiment, the preset value is 70%, the preset ratio is 1%, and the preset value is 30. The implementer can also set them according to the specific situation. This embodiment does not impose any special restrictions.

[0044] (2) Further, by analyzing the similarity of the chromatograms between the current gas and various gas samples at various temperatures, a first similarity index between the current gas and various gas samples at various temperatures is determined, specifically: The normalized result of the cosine similarity of the chromatograms between the current gas and various gas samples at each temperature is used as the first similarity index between the current gas and various gas samples at each temperature, which is used to characterize the similarity of the krypton concentration between the current gas and the gas samples. The larger the first similarity index, the greater the possibility that the krypton concentration values ​​between the current gas and the gas samples are the same.

[0045] The calculation method of cosine similarity is a well-known technology, and its specific calculation process will not be described in detail.

[0046] (3) Further, based on the difference in the second characteristic value between the current gas and the various gas samples at each temperature, the second similarity index between the current gas and the various gas samples at each temperature is determined, specifically: An exponential function value with natural constants as base and the opposite of the second eigenvalue difference between the current gas and various gas samples at each temperature as independent variable is used as the second similarity index between the current gas and various gas samples at each temperature, which is used to characterize the similarity of the krypton concentration between the current gas and the gas samples. The larger the second similarity index, the smaller the second eigenvalue difference between the current gas and various gas samples, that is, the greater the possibility that the krypton concentration values ​​between the current gas and the gas samples are the same.

[0047] It should be noted that there are many methods for measuring the difference between data. In this embodiment, the absolute value of the difference between the second eigenvalues ​​of the current gas and various gas samples at each temperature is used as the difference between the second eigenvalues ​​of the current gas and various gas samples at each temperature. In actual application, as other implementation methods, the implementer may also use other methods for measuring the difference between data, such as the square or ratio of the difference. This embodiment does not impose any special restrictions on the selection of methods for measuring the difference between data.

[0048] It should be noted that the method for obtaining the second similarity index of the gas sample is the same as the method for obtaining the second similarity index of the current gas, and the specific process will not be repeated here.

[0049] (4) The second similarity index between the current gas and various gas samples at each temperature is combined with the first similarity index to determine the likelihood probability when the krypton ratio in the current gas is equal to the krypton ratio in various gas samples at each temperature, so as to determine the likelihood function when the krypton ratio in the current gas is equal to the krypton ratio in various gas samples, specifically: In this embodiment, the normalized value of the multiplication result of the first similarity index and the second similarity index between the current gas and various gas samples at each temperature is used as the likelihood probability when the krypton ratio in the current gas is equal to the krypton ratio in various gas samples at each temperature.

[0050] The current krypton ratio in the gas is equal to The likelihood function of the krypton ratio in the gas sample The expression is: ; Indicates that the proportion of krypton in the current gas at temperature t is equal to The likelihood function of the krypton ratio in the gas sample is given by: T represents the total number of preset different temperatures.

[0051] So far, this embodiment has obtained a likelihood function through temperature chromatography analysis and maximum likelihood estimation, which is used to detect the krypton content in the gas. The separation characteristics of krypton and xenon at different temperatures are used to analyze the fluctuation of chromatographic data to reduce the interference of xenon on krypton content detection and improve the accuracy of krypton separation detection.

[0052] Preferably, the likelihood function construction framework diagram provided in this embodiment is as follows Figure 2 shown.

[0053] Step S3: Based on the likelihood function when the krypton ratio in the current gas is equal to the krypton ratio in various gas samples, the effect of activated carbon on adsorption and separation of krypton in the current gas is evaluated.

[0054] Due to the high boiling point of xenon, krypton is more likely to remain in gaseous state at -130°C, while xenon is more likely to condense or adsorb on the stationary phase. At the same time, the molecular weight of xenon is greater than that of krypton, and the diffusion rate of krypton is higher than that of xenon at the same temperature. At -130°C, this difference in diffusion rate is maximized, allowing krypton to flow out of the chromatographic column faster, while xenon is retained in the column, so that the separation effect is the best at the five column temperatures, and the residual xenon in krypton is the least.

[0055] Therefore, in this embodiment, krypton separated at a column temperature of -130°C is used as a sample. Specifically, the separated krypton is mixed with scintillation liquid to prepare a liquid scintillation sample. The specific formula of the scintillation liquid is 5g of polyphenylene ether (PPO) and 0.3g of 1,4-bis-(5-phenyloxazol-2-yl)benzene (POPOP) dissolved in 1L of toluene. The prepared liquid scintillation sample is placed in a liquid scintillation spectrometer to measure its radioactivity.

[0056] Furthermore, using a standard 85Kr sample of known concentration as a reference, the content of 85Kr in krypton is calculated based on the radioactivity measured by the liquid scintillation spectrometer and combined with the data of the standard sample, as the content of 85Kr in krypton in the current gas.

[0057] The above-mentioned processes of separation, preparation of liquid scintillation samples, determination of radioactivity and calculation of the content of 85Kr in krypton are all well-known technologies, and the specific principles thereof will not be described in detail.

[0058] At this point, the content of 85Kr in krypton in the current gas is obtained. Furthermore, the proportion of krypton when the likelihood function obtained in step S2 takes the maximum value is used as the proportion of krypton in the current gas, and a TCD detector is used to obtain the total volume of the current gas. The product of the proportion of krypton and the total volume is used as the total krypton gas volume. The total krypton gas volume in the current gas is multiplied by the content of 85Kr in krypton and divided by the total gas volume to obtain the concentration of 85Kr in the current gas, which is used to evaluate the activated carbon adsorption and separation effect in the current gas.

[0059] Based on the same inventive concept as the above method, an embodiment of the present application also provides a system for TCD gas chromatography activated carbon adsorption separation of Kr, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above methods for TCD gas chromatography activated carbon adsorption separation of Kr are implemented.

[0060] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0061] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0062] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for separating Kr by activated carbon adsorption using TCD gas chromatography, characterized in that: The method comprises the following steps: Obtaining the TCD gas chromatogram and its peak area after the current gas chromatogram separation at different preset temperatures, and recording the TCD gas chromatogram as chromatogram; Determine the first characteristic value of the current gas at each temperature by analyzing the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the average level of all chromatographic data in its neighborhood; determine the second characteristic value of the current gas at each temperature by comparing the difference between the first characteristic value of the current gas at each temperature and the maximum value of the first characteristic value of the current gas at all temperatures, and the difference between the spectral peak area of ​​the chromatogram of the current gas at each temperature and the maximum value of the spectral peak area at all temperatures; A preset number of gas samples containing different proportions of krypton are prepared at each temperature, and a first similarity index between the current gas and the various gas samples at each temperature is determined by analyzing the similarity of the chromatograms between the current gas and the various gas samples at each temperature; a second similarity index between the current gas and the various gas samples at each temperature is determined based on the difference in the second characteristic value between the current gas and the various gas samples at each temperature, and the likelihood probability when the proportion of krypton in the current gas is equal to the proportion of krypton in the various gas samples at each temperature is determined in combination with the first similarity index, so as to determine the likelihood function when the proportion of krypton in the current gas is equal to the proportion of krypton in the various gas samples; Based on the likelihood function, the relevant krypton content for evaluating the adsorption and separation effect of activated carbon in the current gas is obtained.

2. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The method for determining the first characteristic value of the current gas at each temperature is: The square value of the deviation between each chromatographic data in the chromatogram of the current gas at each temperature and the mean value of all chromatographic data in its neighborhood is calculated, and the square value of all chromatographic data in the chromatogram of the current gas is averaged as the first characteristic value of the current gas at each temperature.

3. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The expression of the second characteristic value of the current gas at each temperature is: ; In the formula, Indicates the second characteristic value of the current gas at temperature t; , Respectively represent the first characteristic value of the current gas at temperature t and the spectral peak area of ​​the chromatogram of the current gas; , They respectively represent the maximum value of the first characteristic value of the current gas at all temperatures and the maximum value of the spectral peak area of ​​the current gas chromatogram.

4. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The step of preparing a preset number of gas samples containing krypton in different proportions at various temperatures comprises: At each temperature, the ratio of krypton in the initial gas sample is prepared to be a preset value, and the preset ratio of krypton is successively increased based on the preset value to obtain gas samples with different krypton ratios until a preset number of gas samples with different krypton ratios are reached.

5. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The first similarity index between the current gas and various gas samples at each temperature is a normalized result of the cosine similarity of the chromatograms between the current gas and various gas samples at each temperature.

6. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The second similarity index between the current gas and various gas samples at each temperature is: an exponential function value with a natural constant as the base and the inverse of the second eigenvalue difference between the current gas and various gas samples at each temperature as the independent variable.

7. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The likelihood probability when the krypton ratio in the current gas at each temperature is equal to the krypton ratio in various gas samples is: the normalized value of the product of the first similarity index and the second similarity index between the current gas and various gas samples at each temperature.

8. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The expression of the likelihood function when the krypton ratio in the current gas is equal to the krypton ratio in various gas samples is: ; Indicates that the krypton ratio in the current gas is equal to The likelihood function of the krypton ratio in the gas sample; Indicates that the proportion of krypton in the current gas at temperature t is equal to The likelihood function of the krypton ratio in the gas sample is given by: T represents the total number of preset different temperatures.

9. The method for separating Kr by TCD gas chromatography activated carbon adsorption according to claim 1, characterized in that: The acquisition of relevant krypton content for evaluating the activated carbon adsorption and separation effect in the current gas includes: The total volume of the current gas and the content of 85Kr in krypton are obtained, the proportion of krypton when the likelihood function takes the maximum value is taken as the proportion of krypton in the current gas, the product of the proportion of krypton and the total volume is taken as the total krypton gas volume, the total krypton gas volume in the current gas is multiplied by the content of 85Kr in krypton and divided by the total gas volume to obtain the concentration of 85Kr in the current gas, which is used to evaluate the activated carbon adsorption and separation effect in the current gas.

10. A system for TCD gas chromatography activated carbon adsorption separation of Kr, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method for TCD gas chromatography activated carbon adsorption separation of Kr as described in any one of claims 1 to 9 are implemented.

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