Dynamic volume balance based gas chromatograph leak monitoring method and response system

Abstract

The application discloses a gas chromatograph leakage monitoring method and response system based on dynamic volume balance, comprising the following steps: obtaining the flow measurement value of the carrier gas on the secondary gas circuit, the total flow measurement value of the carrier gas at the sample inlet end of the gas chromatograph, the flow measurement value of the carrier gas at the detector end of the gas chromatograph, and the second correction value of the carrier gas in the pipeline between the secondary gas circuit and the gas chromatograph; obtaining the secondary volume imbalance term based on the dynamic volume balance method; obtaining the to-be-processed data of a frame of time length T flow signal, calculating the second average value based on the to-be-processed data; calculating the second leakage rate between the secondary gas circuit and the gas chromatograph according to the secondary volume imbalance term and the second average value, and judging the leakage condition between the secondary gas circuit and the gas chromatograph based on the second leakage rate. The application can solve the problem of poor sensitivity and accuracy of the leakage condition monitoring of the gas circuit system.

Description

Technical Field

[0001] This invention relates to the field of gas chromatography technology, and in particular to a gas chromatograph leakage monitoring method and response system based on dynamic volume balance. Background Technology

[0002] Currently, the carrier gas for gas chromatographs is supplied by high-pressure cylinders / gas generators and other gas sources, and is delivered to the gas chromatograph's inlet and detector via pipelines. A two-stage pressure reducing valve in the gas path reduces the carrier gas pressure to the pressure required by the gas chromatograph, and a gas purifier further purifies the carrier gas. The carrier gases used in gas chromatographs are helium, hydrogen, nitrogen, and argon. Carrier gases are colorless and odorless, and leaks are often difficult to detect, exhibiting a significant delay and causing serious consequences. For example, expensive helium leaks result in resource waste and property damage; hydrogen leaks can easily cause fires and explosions; and nitrogen leaks increase the frequency and cost of replacing gas purifiers and detectors.

[0003] A gas chromatograph is disclosed in the related technology. For excessive carrier gas flow rates exceeding a fixed flow rate caused by carrier gas leakage, a flow limiting valve is used to mechanically limit the carrier gas flow rate to a preset flow rate. However, the above technical solution limits the use of gas chromatographs for large-flow carrier gas in certain situations and cannot sensitively identify pipeline leakage problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a gas chromatograph leakage monitoring method and response system based on dynamic volume balance, thereby solving the technical problem of poor sensitivity and accuracy in monitoring leakage in gas circuit systems in the prior art.

[0005] To achieve the above-mentioned technical objectives, in a first aspect, the present invention provides a gas chromatograph leakage monitoring method based on dynamic volume balance, comprising the following steps:

[0006] The flow rate of the carrier gas in the secondary gas path, the total flow rate of the carrier gas at the gas chromatograph inlet, the flow rate of the carrier gas at the gas chromatograph detector, and the second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph are obtained.

[0007] The second-stage volume imbalance term is calculated based on the dynamic volume balance method using the measured flow rate of the carrier gas in the second-stage gas path, the measured total flow rate of the carrier gas at the inlet, the measured flow rate of the carrier gas at the detector, and the second correction value.

[0008] Obtain a frame of traffic signal data with a time length of T to be processed, and calculate the second mean value based on the data to be processed;

[0009] The second leakage rate between the secondary gas path and the gas chromatograph is calculated based on the secondary volume imbalance term and the second mean, and the leakage situation between the secondary gas path and the gas chromatograph is judged based on the second leakage rate.

[0010] Compared with existing technologies, the beneficial effects of the gas chromatograph leakage monitoring method based on dynamic volume balance provided by this invention include:

[0011] The present invention discloses a gas chromatograph leakage monitoring method based on dynamic volume balance. First, it acquires the flow rate measurements of the carrier gas in the secondary gas path, the total flow rate of the carrier gas at the gas chromatograph inlet, the flow rate of the carrier gas at the gas chromatograph detector, and a second correction value for the carrier gas in the pipeline between the secondary gas path and the gas chromatograph. Then, it calculates the secondary volume imbalance term based on the dynamic volume balance method. Next, it acquires a frame of flow signal data with a time length of T to be processed, and calculates a second mean value based on the data. Finally, it calculates a second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean value, and determines the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0012] This invention, without restricting the use of carrier gas at excessively high or low flow rates, allows the gas flow monitoring device, positioned upstream and downstream of the gas path, to monitor and display the flow characteristics of the carrier gas at different pipeline locations in real time. It utilizes the dynamic volume balance principle to monitor leaks between the secondary gas path and the gas chromatograph. The high-precision, rapid detection gas flow monitoring device, combined with comprehensive analysis and statistical decision-making methods, reduces the adverse effects of monitoring delays and errors on leak detection results and their potential consequences, thereby improving the sensitivity and accuracy of leak monitoring in the gas path system.

[0013] The pipeline from the gas source to the secondary pressure reducing valve is defined as the primary gas path. The primary gas path is divided into multiple secondary gas paths by the secondary pressure reducing valve. The secondary gas path is from the secondary pressure reducing valve to the gas chromatograph (GC).

[0014] According to some embodiments of the present invention, determining the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate includes the following steps:

[0015] If the second leakage rate is greater than the preset leakage threshold, the duration of the first abnormal signal is obtained;

[0016] If the duration of the first abnormal signal is greater than a preset time threshold, it is determined that there is a carrier gas delivery abnormality between the secondary gas path and the gas chromatograph.

[0017] According to some embodiments of the present invention, after determining that there is an abnormality in carrier gas delivery between the secondary gas path and the gas chromatograph, the method includes the following steps:

[0018] Determine whether the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend, and whether the volume consumption of carrier gas shows an upward trend.

[0019] When the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend and the volume consumption of carrier gas shows an upward trend, the duration of the second abnormal signal is obtained.

[0020] If the duration of the second abnormal signal is greater than a preset time threshold, it is determined that there is a leak between the secondary gas path and the gas chromatograph.

[0021] According to some embodiments of the present invention, obtaining a second calibration value for the carrier gas in the pipeline between the secondary gas path and the gas chromatograph includes the following steps:

[0022] Obtain the pressure P1 at the start point and P2 at the end point of the secondary gas pipeline, the pipeline inner diameter D, the hydraulic friction coefficient τ, the relative density ρ of the carrier gas, the carrier gas compressibility factor Z, the gas temperature T, and the pipeline length L. Calculate the corrected value v of the carrier gas volume per second in the secondary gas pipeline under standard conditions. 2标准 :

[0023]

[0024] The corrected value v for the carrier gas volume per second in the secondary gas pipeline under actual conditions is calculated based on the corrected value of the carrier gas volume per second in the secondary gas pipeline under standard conditions. 2实际 :

[0025]

[0026] According to v 2实际 The second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph is calculated within a preset time period.

[0027] According to some embodiments of the present invention, after determining that there is an abnormality in carrier gas delivery between the secondary gas path and the gas chromatograph, the method includes the following steps:

[0028] Compared with historical data, does the carrier gas volume consumption in the secondary gas path show an upward trend, and does the pressure show a downward trend? The method for judging the trend of carrier gas volume consumption is as follows:

[0029] Extract V 二级 Data, V 二级 Let V be the current volumetric consumption of carrier gas in the secondary gas path. 二级 The first curve changing over time;

[0030] Extract the method parameters of GC on the current secondary gas path. In the historical database, query all data on the same day that are consistent with the method parameters of GC on the current secondary gas path, and extract V values ​​with the same time length as those in the first curve. 二级f The data, and calculate V 二级f The second curve, which changes over time, is used to determine whether there is a leak between the secondary gas path and the gas chromatograph by comparing the difference between the first curve and the second curve.

[0031] According to some embodiments of the present invention, after calculating the secondary volume imbalance term of the secondary gas path carrier gas based on the dynamic volume balance method, the method includes the following steps:

[0032] Under normal gas path conditions, determine the secondary volume imbalance term V of the carrier gas in the secondary gas path. B The mean (θ0) and standard deviation (σ0) of (t);

[0033] Based on data from gas leak scenarios, alternative hypotheses θ were determined. x :

[0034]

[0035] In the formula, V 二级 a represents the current volumetric consumption of carrier gas in the secondary gas path. x For θ x The corresponding coefficients are calculated based on the prior distribution function of the carrier gas leakage.

[0036] Collect data for judgment and testing; after the y-th sample, the alternative hypothesis is θ. x The decision function is:

[0037]

[0038] Where n is the maximum value of a single sample, which is corrected using a function compensation method. The corrected decision function is R. x * (y), if R x (y)≥0, then R x * (y)=R x (y), if R x (y) < 0, R x * (y) = 0;

[0039] Leakage detection; α is the false alarm rate of the leakage monitoring system, β is the leakage alarm rate of the leakage monitoring system, and α and β are both 0.5%. Therefore, the threshold of the decision function is {0, ln[(1-β) / α]}; when R... x *When (y)≥ln[(1-β) / α], a leak occurs between the secondary gas path and the gas chromatograph.

[0040] Secondly, the technical solution of the present invention provides a gas chromatograph leakage monitoring method based on dynamic volume balance, comprising the following steps:

[0041] Obtain the flow rate measurement values ​​of the carrier gas in the primary gas path, the flow rate measurement values ​​of the carrier gas in the secondary gas path, and the first correction value in the pipeline between the primary and secondary gas paths;

[0042] Based on the dynamic volume balance method, the first-level volume imbalance term is calculated according to the measured flow rate of the carrier gas in the first-level gas path, the measured flow rate of the carrier gas in the second-level gas path, and the first correction value in the pipeline between the first-level and second-level gas paths.

[0043] Obtain a frame of traffic signal data with a time length of T to be processed, and calculate the first mean value based on the data to be processed;

[0044] The first leakage rate between the primary gas path and the secondary gas path is calculated based on the first-level volume imbalance term and the first mean value, and the leakage situation between the primary gas path and the secondary gas path is judged based on the first leakage rate.

[0045] According to some embodiments of the present invention, determining the leakage situation between the primary gas path and the secondary gas path based on the first leakage rate includes the following steps:

[0046] If the first leakage rate is greater than a preset leakage threshold, obtain the duration of the third abnormal signal;

[0047] If the duration of the third abnormal signal is greater than the preset time threshold, it is determined that there is a carrier gas delivery abnormality between the primary gas path and the secondary gas path.

[0048] Thirdly, the technical solution of the present invention provides a gas chromatograph leak monitoring and response system based on dynamic volume balance, comprising:

[0049] A gas flow monitoring device is used to acquire the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and the second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph.

[0050] The volume imbalance term calculation module is communicatively connected to the gas flow monitoring device. Based on the dynamic volume balance method, it calculates the secondary volume imbalance term according to the measured flow rate of the carrier gas in the secondary gas path, the measured total flow rate of the carrier gas at the inlet end, the measured flow rate of the carrier gas at the detector end, and the second correction value.

[0051] The mean calculation module is used to acquire the data to be processed of a flow signal with a time length of T, and calculate the second mean based on the data to be processed.

[0052] The leakage detection module is communicatively connected to the volume imbalance calculation module and the mean calculation module. It is used to calculate the second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean, and to determine the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0053] According to some embodiments of the present invention, the gas chromatograph leak monitoring and response system based on dynamic volume balance further includes: a response module, which is communicatively connected to the leak judgment module, and the response module is used to generate corresponding control commands according to the leak gas type and leak situation.

[0054] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0055] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein the abstract drawings are to be completely consistent with one of the drawings in the specification:

[0056] Figure 1 A flowchart of a gas chromatograph leakage monitoring method based on dynamic volume balance provided in one embodiment of the present invention;

[0057] Figure 2 A flowchart of a gas chromatograph leakage monitoring method based on dynamic volume balance provided in one embodiment of the present invention;

[0058] Figure 3 A flowchart of a gas chromatograph leakage monitoring method based on dynamic volume balance provided in one embodiment of the present invention;

[0059] Figure 4 A flowchart of a gas chromatograph leakage monitoring method based on dynamic volume balance provided in one embodiment of the present invention;

[0060] Figure 5 This is a schematic diagram of a gas chromatograph leak monitoring and response system based on dynamic volume balance, provided as an embodiment of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0062] It should be noted that although functional modules are divided in the system diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than the module division in the system or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the aforementioned figures are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0063] The carrier gas for a gas chromatograph is supplied by a high-pressure cylinder / gas generator and other gas sources, and delivered through pipelines to the gas chromatograph's inlet and detector. A two-stage pressure reducing valve in the gas path reduces the carrier gas pressure to the pressure required by the gas chromatograph. A gas purifier purifies the carrier gas. The carrier gas for a gas chromatograph is helium, hydrogen, nitrogen, or argon. Carrier gases are colorless and odorless, and leaks are often difficult to detect, exhibiting significant latency and causing serious consequences. For example, expensive helium leaks result in resource waste and property damage; hydrogen leaks can easily cause fires and explosions; and nitrogen leaks increase the frequency and cost of replacing gas purifiers and detectors. Internal leaks in a gas chromatograph, such as loose column connectors or broken columns, usually manifest as abnormal flow or pressure at the inlet and trigger an alarm. However, there is no corresponding monitoring and response mechanism for external leaks in a gas chromatograph.

[0064] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0065] Reference Figure 1 , Figure 1 The flowchart illustrates a gas chromatograph leakage monitoring method based on dynamic volume balance, as provided in one embodiment of the present invention. The gas chromatograph leakage monitoring method based on dynamic volume balance includes, but is not limited to, steps S110 to S140.

[0066] Step S110: Obtain the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the injection port of the gas chromatograph, the flow rate measurement value of the carrier gas at the detector end of the gas chromatograph, and the second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph.

[0067] Step S120: Based on the dynamic volume balance method, the secondary volume imbalance term is calculated according to the measured flow rate of the carrier gas in the secondary gas path, the measured total flow rate of the carrier gas at the injection port, the measured flow rate of the carrier gas at the detector, and the second correction value.

[0068] Step S130: Obtain a frame of traffic signal data to be processed with a time length of T, and calculate the second mean based on the data to be processed;

[0069] Step S140: Calculate the second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean, and determine the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0070] In one embodiment, a gas chromatograph leakage monitoring method based on dynamic volume balance includes the following steps: acquiring the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and a second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph; calculating a secondary volume imbalance term based on the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the inlet, the flow rate measurement value of the carrier gas at the detector, and the second correction value using the dynamic volume balance method; acquiring a frame of flow signal data to be processed with a time length of T, and calculating a second mean value based on the data to be processed; calculating a second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean value, and determining the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0071] This invention, without restricting the use of carrier gas at excessively high or low flow rates, allows gas flow monitoring devices positioned upstream and downstream of the gas path to monitor and display the flow characteristics of the carrier gas at different pipeline locations in real time. It utilizes the dynamic volume balance principle to monitor leaks in the primary and secondary gas paths. The high-precision, rapid-detection gas flow monitoring device, combined with comprehensive analysis and statistical decision-making methods, reduces the adverse effects of monitoring delays and errors on leak detection results and their potential consequences, thereby improving the sensitivity and accuracy of leak monitoring in the gas path system.

[0072] The gas flow monitoring device can be equipped with a response module, which can automatically take corresponding actions based on the leakage judgment results. In particular, in the case of hydrogen leakage, technicians do not need to manually shut off the gas source on-site, and the supply of hydrogen in the primary or secondary gas circuit can be automatically and timely stopped. This avoids putting the gas chromatograph and the technicians using the gas chromatograph in a dangerous environment, and also allows technicians to operate and control it remotely, making it safer, more reliable, efficient and convenient for technicians to work.

[0073] The control software of a gas chromatograph can handle leaks appropriately based on gas type, leak location, and leak severity. When dealing with carrier gas leaks, such as serious leaks of flammable and explosive hydrogen or expensive helium, the software can control the gas flow monitoring devices in the primary or secondary gas paths to stop the supply of hydrogen or helium to the gas chromatograph. This effectively prevents resource waste and economic losses caused by helium leaks, and also prevents accidents such as fires and explosions caused by hydrogen leaks. This provides safe and low-cost protection for gas chromatograph technicians, giving them greater peace of mind. When leaks of inexpensive and low-risk nitrogen or argon are possible, the software can prioritize stopping the gas chromatograph and shutting it down according to the normal operating procedure. This avoids damage to the chromatographic column, which is operating at high temperatures, caused by the sudden cessation of the carrier gas.

[0074] Furthermore, according to the present invention, the gas flow monitoring device has the function of accumulating the flow rate of the carrier gas. The gas flow monitoring device installed in the primary gas path can calculate the difference between the total amount of carrier gas that has flowed out and the preset total amount of the gas source, and compare it with the preset threshold. The result is used to remind the technicians using the gas chromatograph to replace the gas source in time. Moreover, the gas flow monitoring device installed in the secondary gas path can accumulate the total amount of carrier gas flowing through the gas purifier to guide the technicians to replace the gas purifier, so as to avoid the influence of unclean gas on the performance of components such as the chromatographic column and detector of the gas chromatograph, as well as the sensitivity.

[0075] The flow rate and pressure monitored by the gas flow monitoring device located in the secondary gas path can provide technicians with a reference for identifying flow rate and pressure problems at the gas chromatograph's inlet. For example, when the gas chromatograph experiences insufficient inlet flow rate and low pressure, checking the flow rate and pressure data monitored by the gas flow monitoring device located in the secondary gas path can clarify whether the gas supply in the secondary gas path is sufficient.

[0076] A comprehensive method for leak detection based on dynamic volume balance between the secondary gas path and the gas chromatograph:

[0077] The carrier gas leakage rate is calculated based on the dynamic volume balance formula. If the carrier gas leakage rate is greater than a preset leakage threshold, the duration of the first abnormal signal is obtained. If the duration of the first abnormal signal is greater than a preset time threshold, it is determined that there may be an abnormality in the carrier gas delivery in the secondary gas path. Further analysis is performed to determine whether the pressure in the secondary gas path has decreased or whether the volume consumption has increased; or, compared with historical data, whether the carrier gas volume consumption in the secondary gas path shows an upward trend or the pressure shows a downward trend. The formula for calculating the secondary volume imbalance term is as follows:

[0078] V B (t)=∫Q 二级 dt-(∫QGC进样口 dt+∫Q GC检测器 dt)-Δv2

[0079] Q GC进样口 =Q 柱流量 +Q 分流流量 +Q 隔垫吹扫 The total flow rate of the carrier gas at the gas chromatograph inlet is the sum of the column flow rate, the split flow rate, and the septum purge flow rate.

[0080] Among them, V B (t) represents the volume imbalance term of the carrier gas during time t, Q 二级 Q represents the instantaneous flow rate of the carrier gas in the secondary gas path corresponding to each gas chromatograph. GC进样口 Q represents the total flow rate of the carrier gas at the gas chromatograph inlet. GC检测器 Δv2 is the measured flow rate of the carrier gas at the detector end of the gas chromatograph, which depends on the type of carrier gas and detector. Δv2 is the second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph.

[0081] Q GC检测器 It depends on the type of carrier gas and the type of detector. When the carrier gas is helium and the detector is a flame ionization detector (FID):

[0082] Q GC检测器 =Q 检测器尾吹气

[0083] When the carrier gas is hydrogen and the detector is a thermal conductivity detector (TCD):

[0084] Q GC检测器 =Q 检测器尾吹气 +Q 检测器参比气

[0085] When the carrier gas is nitrogen and the detector is an electron capture detector (ECD);

[0086] Q GC检测器 =Q 检测器尾吹气 +Q 检测器阳离吹扫 .

[0087] In one embodiment, the signal acquisition frequency of the gas flow monitoring device is 100Hz, and the signal extraction frequency can be selected by technicians from 50Hz, 25Hz, 10Hz, 1Hz, etc. The data is transmitted to the control software of the gas chromatograph. The control software takes the flow signal within a set time length T (e.g., 5min, 8min, 10min, etc.) as a frame of data to be processed, and extracts Q from it. 二级 Q GC进样口 Q GC检测器Each frame of data to be processed with a time length of T is divided into intervals of equal time length j (e.g., 1s, 5s, 10s). Therefore, a frame of signal is divided into m (=T / j) intervals. The start time of each interval is stored in the Start array, and the end time position is stored in the End array.

[0088] For example, in the k-th (1≤k≤m) interval, the starting point of the interval is time i (in seconds), and the ending time is time i+j (in seconds). The starting position of the (k+1)-th interval is i+j+1, and so on.

[0089] The specific judgment process is as follows:

[0090] Judgment condition one: Calculate the interval carrier gas leakage rate. and the preset carrier gas leakage rate Comparison, if Greater than If the duration of the abnormal signal T(1) is greater than the set minimum duration of the signal T(s), then it is considered that there may be an abnormality in the secondary gas path carrier gas delivery from the starting time Start(k) corresponding to the kth interval.

[0091] (a) Calculate the second-order volume imbalance term V of the carrier gas in each interval using the following formula. B (i,i+j)

[0092]

[0093] Among them, Q 二级 Q represents the instantaneous flow rate of the carrier gas in the secondary gas path corresponding to each gas chromatograph. GC进样口 Q represents the total flow rate of the carrier gas at the gas chromatograph inlet. GC检测器 Δv2 is the measured flow rate of the carrier gas at the detector end of the gas chromatograph, which depends on the type of carrier gas and detector. Δv2 is a correction value for the carrier gas in the pipeline between the secondary gas path and the gas chromatograph. Δv2 includes a second correction value v for the volume of carrier gas per second in the secondary gas path pipeline. 2实际 And the measurement error v of the gas flow monitoring device 2测量误差 Considering the complexity of actual pipeline conditions, the calculated values ​​were corrected through experiments.

[0094]

[0095] v 2标准 P1 and P2 are the pressures (MPa) at the beginning and end of the secondary gas pipeline, respectively. D is the inner diameter of the pipeline (cm). τ is the hydraulic friction coefficient. ρ is the relative density of the carrier gas. Z is the carrier gas compressibility factor. T is the gas temperature (K). L is the pipeline length (m).

[0096]

[0097] v 2实际 This is the correction value for the volume of carrier gas per second in the secondary gas pipeline under actual conditions. P0 and T0 are the atmospheric pressure (101.3 kPa) and temperature (293 K) under standard conditions, while P and T are the atmospheric pressure (MPa) and temperature (K) under actual conditions.

[0098] (b) Calculate the mean volume V of the carrier gas in a frame of signal. B均值

[0099]

[0100]

[0101]

[0102] (c) Calculate the carrier gas leakage rate in different intervals. and signal duration T(1)

[0103]

[0104] Judgment condition two: Determine whether the changing trends of pressure and volume consumption in the secondary gas path meet the requirements. Specifically, starting from the k-e (0≤e<k) interval identified as an abnormality in the carrier gas delivery of the secondary gas path, determine whether the pressure of the gas flow monitoring device on the secondary gas path shows a decreasing trend, and whether the volume consumption of the carrier gas shows an increasing trend.

[0105] (a) Starting from the initial time Start(k-e) corresponding to the k-e interval, calculate using the formula ΔP 二级 (i)=P 二级 (i+1)-P 二级 (i) Calculate the pressure difference ΔP between adjacent time points 二级 (i) Whether <0 holds true, and the duration T(2) when the above formula holds true;

[0106] (b) Starting from the k-e interval, calculate using the formula ΔV 二级 (k)=V 二级 (k+1)-V 二级 (k) Calculate the difference ΔV in volume consumption between adjacent intervals. 二级 Whether (k)>0 holds true, and the duration T(3) when the above formula holds true;

[0107] If the pressure difference ΔP between adjacent time points 二级 The duration T(2) of <0 and the difference ΔV in the volume consumption of adjacent intervals 二级If the duration T(3) of >0 is greater than the set minimum signal duration T(s), then it is considered that there is a pressure decreasing trend and a volume consumption increasing trend in the secondary gas path.

[0108] In summary, only when both of the above two judgment conditions are met can it be determined that there is a leak between the secondary gas path and the gas chromatograph; otherwise, it can be judged as a suspected leak.

[0109] Furthermore, if the method parameters remain unchanged for an extended period during GC (gas chromatograph) use—for example, the injection port (column flow rate, split ratio), column parameters, and detector parameters all remain constant—the trend in volume consumption in the second judgment condition mentioned above is obtained by comparing data from different intervals within the same signal frame.

[0110] Judgment condition two can also be modified to: Compared with historical data, whether the carrier gas volume consumption in the secondary gas path shows an upward trend and whether the pressure shows a downward trend. The method for judging the trend of carrier gas volume consumption is as follows:

[0111] (a) Extract V from the start time of the k-th interval identified as an anomaly in carrier gas delivery to the end time of that frame of data. 二级 The data, and calculate V 二级 A curve that changes over time.

[0112] (b) Starting from the beginning of the k-th interval identified as an abnormal carrier gas delivery, extract the GC method parameters, including GC inlet parameters (such as total flow rate, column flow rate, split ratio, etc.), column parameters, and detector parameters (such as make-up flow rate, etc.).

[0113] (c) In the historical database, query all data for the day that matches the method parameters of GC in (b), and extract V data with the same time length as in (a'). 二级 (f) Data, plotting V 二级 (f) Curve changing over time;

[0114] (d) Determine V 二级 (f) Changes over time and V 二级 Does the change over time show significant differences?

[0115] Reference Figure 2 , Figure 2 The flowchart illustrates a gas chromatograph leakage monitoring method based on dynamic volume balance, as provided in one embodiment of the present invention. The gas chromatograph leakage monitoring method based on dynamic volume balance includes, but is not limited to, steps S210 to S220.

[0116] Step S210: If the second leakage rate is greater than the preset leakage threshold, obtain the duration of the first abnormal signal;

[0117] Step S220: If the duration of the first abnormal signal is greater than a preset time threshold, it is determined that there is an abnormality in the carrier gas delivery between the secondary gas path and the gas chromatograph.

[0118] In one embodiment, a gas chromatograph leakage monitoring method based on dynamic volume balance includes the following steps: acquiring the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and a second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph; calculating a secondary volume imbalance term based on the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the inlet, the flow rate measurement value of the carrier gas at the detector, and the second correction value using the dynamic volume balance method; acquiring a frame of flow signal data to be processed with a time length of T, and calculating a second mean value based on the data to be processed; calculating a second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean value, and determining the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0119] The method for determining the leakage between the secondary gas path and the gas chromatograph based on the second leakage rate includes the following steps: if the second leakage rate is greater than a preset leakage threshold, the duration of the first abnormal signal is obtained; if the duration of the first abnormal signal is greater than a preset time threshold, it is determined that there is an abnormality in the carrier gas delivery between the secondary gas path and the gas chromatograph.

[0120] Reference Figure 3 , Figure 3 The flowchart illustrates a gas chromatograph leakage monitoring method based on dynamic volume balance, as provided in one embodiment of the present invention. The gas chromatograph leakage monitoring method based on dynamic volume balance includes, but is not limited to, steps S310 to S330.

[0121] Step S310: Determine whether the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend and whether the volume consumption of carrier gas shows an upward trend.

[0122] Step S320: When the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend and the volume consumption of the carrier gas shows an upward trend, the duration of the second abnormal signal is obtained.

[0123] Step S330: If the duration of the second abnormal signal is greater than a preset time threshold, it is determined that there is a leak between the secondary gas path and the gas chromatograph.

[0124] In one embodiment, a gas chromatograph leakage monitoring method based on dynamic volume balance includes the following steps: acquiring the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and a second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph; calculating a secondary volume imbalance term based on the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the inlet, the flow rate measurement value of the carrier gas at the detector, and the second correction value using the dynamic volume balance method; acquiring a frame of flow signal data to be processed with a time length of T, and calculating a second mean value based on the data to be processed; calculating a second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean value, and determining the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0125] The method for determining the leakage between the secondary gas path and the gas chromatograph based on the second leakage rate includes the following steps: if the second leakage rate is greater than a preset leakage threshold, the duration of the first abnormal signal is obtained; if the duration of the first abnormal signal is greater than a preset time threshold, it is determined that there is an abnormality in the carrier gas delivery between the secondary gas path and the gas chromatograph.

[0126] After determining that there is an abnormality in carrier gas delivery between the secondary gas path and the gas chromatograph, the steps include: determining whether the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend and whether the volume consumption of carrier gas shows an upward trend; when the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend and the volume consumption of carrier gas shows an upward trend, obtaining the duration of the second abnormal signal; if the duration of the second abnormal signal is greater than a preset time threshold, determining that there is a leak between the secondary gas path and the gas chromatograph.

[0127] The system determines whether the trends in pressure and volume consumption of the secondary gas path meet the requirements. Specifically, starting from the k-th interval identified as an abnormality in the carrier gas delivery of the secondary gas path, it checks whether the pressure of the gas flow monitoring device on the secondary gas path shows a decreasing trend and whether the volume consumption of the carrier gas shows an increasing trend. If the pressure of the gas flow monitoring device on the secondary gas path shows a decreasing trend, the volume consumption of the carrier gas shows an increasing trend, and the duration of the second abnormal signal exceeds a preset time threshold, it is determined that there is a leak between the secondary gas path and the gas chromatograph.

[0128] In one embodiment, a gas chromatograph leakage monitoring method based on dynamic volume balance includes the following steps: acquiring the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and a second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph; calculating a secondary volume imbalance term based on the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the inlet, the flow rate measurement value of the carrier gas at the detector, and the second correction value using the dynamic volume balance method; acquiring a frame of flow signal data to be processed with a time length of T, and calculating a second mean value based on the data to be processed; calculating a second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean value, and determining the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0129] The method for determining the leakage between the secondary gas path and the gas chromatograph based on the second leakage rate includes the following steps: if the second leakage rate is greater than a preset leakage threshold, the duration of the first abnormal signal is obtained; if the duration of the first abnormal signal is greater than a preset time threshold, it is determined that there is an abnormality in the carrier gas delivery between the secondary gas path and the gas chromatograph.

[0130] After determining that there is an anomaly in carrier gas delivery between the secondary gas path and the gas chromatograph, the steps include: comparing with historical data to determine whether the carrier gas volume consumption in the secondary gas path shows an upward trend and whether the pressure shows a downward trend. The method for determining the trend of carrier gas volume consumption is as follows: extract V... 二级 Data, V 二级 Let V be the current volumetric consumption of carrier gas in the secondary gas path. 二级 The first curve changes over time; extract the method parameters of GC on the current secondary gas path; in the historical database, query all data on the same day that match the method parameters of GC on the current secondary gas path, and extract V values ​​with the same time length as the first curve. 二级f The data, and calculate V 二级f The second curve, which changes over time, is used to determine whether there is a leak between the secondary gas path and the gas chromatograph by comparing the difference between the first and second curves.

[0131] In one embodiment, the gas chromatograph leakage monitoring method based on dynamic volume balance includes the following steps: obtaining the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and a second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph; and calculating the secondary volume imbalance term based on the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the inlet, the flow rate measurement value of the carrier gas at the detector, and the second correction value using the dynamic volume balance method.

[0132] Under normal gas path conditions, determine the secondary volume imbalance term V of the carrier gas in the secondary gas path. B The mean (θ0) and standard deviation (σ0) of (t);

[0133] Based on data from gas leak scenarios, alternative hypotheses θ were determined. x :

[0134]

[0135] In the formula, V 二级 a represents the current volumetric consumption of carrier gas in the secondary gas path. x For θ x The corresponding coefficients are calculated based on the prior distribution function of the carrier gas leakage.

[0136] Collect data for judgment and testing; after the y-th sample, the alternative hypothesis is θ. x The decision function is:

[0137]

[0138] Where n is the maximum value of a single sample, which is corrected using a function compensation method. The corrected decision function is R. x * (y), if R x (y)≥0, then R x * (y)=R x (y), if R x (y) < 0, R x * (y) = 0;

[0139] Leakage detection; α is the false alarm rate of the leakage monitoring system, β is the leakage alarm rate of the leakage monitoring system, and α and β are both 0.5%. Therefore, the threshold of the decision function is {0, ln[(1-β) / α]}; when R... x * When (y)≥ln[(1-β) / α], a leak occurs between the secondary gas path and the gas chromatograph.

[0140] A statistical decision-making method for leak detection based on dynamic volume balance: Small leaks may occur at the gas line connection between the secondary gas path and the gas chromatograph due to aging of the gasket from prolonged use or improper installation. For these small leaks, a statistical decision-making method—multiple sequential probability ratio test—can be used to identify them, ensuring sufficiently low false alarm and false negative rates. However, when establishing or using this method for the first time, sufficient data should be used to determine certain parameters through statistical analysis, or some provided empirical values ​​can be used, as follows:

[0141] 1. Under normal gas path conditions, determine the volume imbalance term V of the carrier gas. BThe mean (θ0) and standard deviation (σ0) of (t);

[0142] (a) Under normal gas path conditions, different GC methods and secondary pressure reducing valve pressures are set to collect sufficient data. The GC methods mainly involve setting parameters such as carrier gas control mode, split mode (split / splitless), carrier gas saving settings, column type, and detector flow rate. The secondary pressure reducing valve pressure is mainly set between 0.3 and 0.5 MPa. Since the pipe length and inner diameter parameters used in different secondary gas paths differ only slightly, the influence of these pipe parameters can be ignored.

[0143] (b) Select an appropriate time length j, and calculate the secondary gas path in different intervals based on the collected data using the following formula.

[0144] The volume imbalance term V of the internal carrier gas B (t), where i starts from 0:

[0145]

[0146] (c) Refer to GB / T 4882-2001 for V B (t) Perform a normality test according to GB / T 4883-2008.

[0147] The stationarity test is performed by Q. GC进样口 Abnormal data and non-stationary signals caused by abnormal fluctuations are filtered and then processed. B (t) follows (θ0, σ0) 2 The data is first normalized to a normal distribution (0,1), and then normalized to generate a new data Z that follows a normal distribution (0,1). If there is a leak in the gas path, the normalized Z will follow a distribution (θ,1), where θ is a non-zero parameter value. The normality of the secondary gas path determines whether θ is 0 or a non-zero value.

[0148] 2. Determine alternative hypotheses θ based on data from gas leakage scenarios. x

[0149] For the standardized V B The (t) distribution proposes two hypotheses: the null hypothesis H0: θ = 0, the secondary gas path is normal; and the other alternative hypothesis H0. x θ=θ x The secondary gas circuit experienced leaks of varying degrees, θ x Here, θ represents a non-zero parameter value, and x represents the number of alternative hypotheses. Based on the prior distributions of different leakage levels and the average time required to test various leakage types, θ is determined. x The value of θ. x The calculation formula is simplified to:

[0150]

[0151] In the formula, V 二级 Therefore, the volumetric consumption of carrier gas in the secondary gas path, a x For θ x The corresponding coefficients are calculated based on the prior distribution function of the carrier gas leakage.

[0152] However, the minimum detectable volume of carrier gas (V) in the event of a leak must also be considered. min )

[0153]

[0154] In the formula, dv 2实际 This represents the estimation error of the carrier gas volume within the secondary gas path pipeline under actual conditions; dv 2测量误差 The overall error of the measurement results is represented by ; j represents the time interval.

[0155] To improve detection speed, two to three alternative hypotheses can be set for simultaneous detection for each level of leakage.

[0156] 3. Judgment and inspection process:

[0157] (a) Determine the parameters θ0, σ0, and θ x Afterwards, data can be collected for judgment and testing. Each alternative hypothesis corresponds to a decision function; the alternative hypothesis after the y-th sample is θ. x The decision function is:

[0158]

[0159] (b) To eliminate the detection delay caused by the accumulation of negative values ​​in the decision function under normal conditions, a function compensation method is used for correction. The corrected decision function is R. x * (y), if R x (y)≥0, then R x * (y)=R x (y), if R x (y) < 0, R x * (y) = 0.

[0160] (c) Leakage detection: α is the false alarm rate of the leak monitoring system, and β is the leakage alarm rate. α and β are typically 0.5%. Therefore, the threshold of the decision function is {0, ln[(1-β) / α]}. When R... x * If (y)≥ln[(1-β) / α], then a leak has occurred in the secondary gas path; otherwise, continue sampling to determine the cause.

[0161] Reference Figure 4 , Figure 4 The flowchart illustrates a gas chromatograph leakage monitoring method based on dynamic volume balance, as provided in one embodiment of the present invention. The gas chromatograph leakage monitoring method based on dynamic volume balance includes, but is not limited to, steps S410 to S440.

[0162] Step S410: Obtain the flow rate measurement value of the carrier gas in the primary gas path, the flow rate measurement value of the carrier gas in the secondary gas path, and the first correction value in the pipeline between the primary and secondary gas paths.

[0163] Step S420: Based on the dynamic volume balance method, the first-level volume imbalance term is calculated according to the measured flow rate of the carrier gas in the first-level gas path, the measured flow rate of the carrier gas in the second-level gas path, and the first correction value in the pipeline between the first-level and second-level gas paths.

[0164] Step S430: Obtain a frame of traffic signal data to be processed with a time length of T, and calculate the first mean value based on the data to be processed;

[0165] Step S440: Calculate the first leakage rate between the primary gas path and the secondary gas path based on the primary volume imbalance term and the first mean value, and determine the leakage situation between the primary gas path and the secondary gas path based on the first leakage rate.

[0166] In one embodiment, a gas chromatograph leakage monitoring method based on dynamic volume balance includes the following steps: acquiring the flow rate measurement values ​​of the carrier gas in the primary gas path, the flow rate measurement values ​​of the carrier gas in the secondary gas path, and a first correction value in the pipeline between the primary and secondary gas paths; calculating a primary volume imbalance term based on the flow rate measurement values ​​of the carrier gas in the primary gas path, the flow rate measurement values ​​of the carrier gas in the secondary gas path, and the first correction value in the pipeline between the primary and secondary gas paths using the dynamic volume balance method; acquiring a frame of flow signal data to be processed with a time length of T, and calculating a first mean value based on the data to be processed; calculating a first leakage rate between the primary and secondary gas paths based on the primary volume imbalance term and the first mean value, and judging the leakage situation between the primary and secondary gas paths based on the first leakage rate.

[0167] The comprehensive analysis and leakage judgment method based on dynamic volume balance is as follows:

[0168] The dynamic volume balance calculation formula between the primary and secondary gas paths is as follows:

[0169]

[0170] In the formula V A (t) represents the volume imbalance term of the carrier gas during time t, Q 一级 Q is the instantaneous flow rate of the carrier gas in the primary gas path. 二级Δv1 is the instantaneous flow rate measurement value of the carrier gas in the secondary gas path. Assuming there are N secondary gas paths, Δv1 is the first correction value of the carrier gas in the pipeline between the primary gas path and the secondary gas path.

[0171] The pipeline from the gas source to the secondary pressure reducing valve is defined as the primary gas path. The primary gas path is divided into multiple secondary gas paths by the secondary pressure reducing valve. The secondary gas path is from the secondary pressure reducing valve to the gas chromatograph (GC).

[0172] A comprehensive leak detection method based on dynamic volume balance between the primary and secondary gas paths:

[0173] The gas flow monitoring device acquires signals at a frequency of 100Hz, while extraction frequencies of 50Hz, 25Hz, 10Hz, and 1Hz are available for technicians to select. The data is transmitted to the gas chromatograph's control software. The software treats the flow signals within a set time period T (e.g., 5 min, 8 min, 10 min, etc.) as a frame of data to be processed, and extracts the Q signal from it. 一级 and Q 二级 Each frame of data with a duration of T is divided into intervals of equal duration j (e.g., 1s, 5s, 10s). Therefore, one frame of signal is divided into m (=T / j) intervals. The start time of each interval is stored in the Start array, and the end time position is stored in the End array. For example, in the k-th (1≤k≤m) interval, the start point of the interval is time i (in seconds), and the end time is time i+j (in seconds). The start position of the (k+1)-th interval is i+j+1, and so on.

[0174] The specific judgment process is as follows:

[0175] 1. Calculate the first-order volume imbalance term V of the carrier gas in each interval using the following formula. A (i,i+j)

[0176]

[0177] Among them, Q 一级 Q is the instantaneous flow rate of the carrier gas in the primary gas path. 二级 Δv1 is the instantaneous flow rate of the carrier gas in the secondary gas path, where N is the actual number of secondary gas paths in use (1≤N≤8), and Δv1 includes the correction value v for the volume of carrier gas per second in the primary gas path pipeline. 1实际 And the measurement error v of the gas flow monitoring device 1测量误差 Considering the complexity of actual pipeline conditions, the calculated values ​​need to be corrected through experiments.

[0178]

[0179] v 1实际 P0 and T0 are the corrected values ​​for the volume of carrier gas per second in the primary gas pipeline under actual conditions. P0 and T0 are the atmospheric pressure (101.3 kPa) and temperature (293 K) under standard conditions, while P and T are the atmospheric pressure (MPa) and temperature (K) under actual conditions.

[0180]

[0181] v 1标准 P1 and P2 are the corrected values ​​for the volume of carrier gas per second in the primary gas pipeline under standard conditions. P1 and P2 are the pressures (MPa) at the beginning and end of the primary gas pipeline, respectively. D is the inner diameter of the pipeline (cm). τ is the hydraulic friction coefficient. ρ is the relative density of the carrier gas. Z is the carrier gas compressibility factor. T is the gas temperature (K). L is the pipeline length (m).

[0182] The first mean value V of the carrier gas volume in a frame of signal is obtained by calculating the mean volume of the carrier gas in a frame of signal. A均值 :

[0183]

[0184]

[0185]

[0186] 2. Calculate the first leakage rate in different intervals. and signal duration T(4)

[0187]

[0188] Judgment condition 1: If the calculated first leakage rate of the interval Greater than the preset carrier gas leakage rate If the duration of the third abnormal signal T(4) is greater than the set minimum duration of the signal T(s), then it is considered that there is an abnormality in the primary gas path carrier gas delivery from the starting time Start(k) corresponding to the kth interval.

[0189] 3. Starting from the k-e (0≤e<k)th interval identified as an abnormality in the primary gas path carrier gas delivery, determine whether the pressure of the gas flow monitoring device 1 on the primary gas path shows a decreasing trend, and whether the volume consumption of the carrier gas shows an increasing trend.

[0190] (a) Starting from the initial time Start(k-e) corresponding to the k-e interval, calculate using the formula ΔP 一级 (i)=P 一级 (i+1)-P 一级 (i) Calculate the pressure difference ΔP between adjacent time points 一级 (i) Whether <0 holds true, and the duration T(5) when the above equation holds true.

[0191] (b) Starting from the k-e interval, calculate using the formula ΔV 一级 (k)=V 一级 (k+1)-V 一级 (k)

[0192] Calculate the difference ΔV in volume consumption between adjacent intervals. 一级 Whether (k)>0 holds true, and the duration T(6) when the above equation holds true.

[0193] If the pressure difference ΔP between adjacent time points 一级 The duration T(5) of <0 and the difference ΔV in the volume consumption of adjacent intervals 一级 If the duration T(6) of >0 is greater than the set minimum signal duration T(s), then it is considered that the pressure on the primary gas path decreases and the volume consumption increases.

[0194] 4. Starting from the k-e (0≤e<k) interval identified as an abnormality in the primary gas path carrier gas delivery, determine whether the pressure of the gas flow monitoring device (numbered 2-N) in the secondary gas path shows a decreasing trend, and whether the volume consumption of carrier gas shows a decreasing trend. Only the data from one monitoring device needs to meet the conditions after calculation.

[0195] (c) Starting from the initial time Start(k-e) corresponding to the k-e interval, calculate using the formula ΔP 二级 (i)=P 二级 (i+1)-P 二级 (i) Calculate the pressure difference ΔP between adjacent time points 二级 (i) Whether <0 holds true, and the duration T(7) when the above equation holds true.

[0196] (d) Starting from the k-e interval, calculate using the formula ΔV 二级 (k)=V 二级 (k+1)-V 二级 (k) Calculate the difference ΔV in volume consumption between adjacent intervals. 二级 Whether (k)<0 holds true, and the duration T(8) when the above equation holds true.

[0197] If the pressure difference ΔP between adjacent time points 二级 The duration T(7) of <0 and the difference ΔV in the volume consumption of adjacent intervals 二级 If the duration T(8) of <0 is greater than the set minimum signal duration T(s), then it is considered that there is a pressure decrease trend and a volume consumption decrease trend in the secondary gas path.

[0198] Judgment Condition 2: Determine whether the changing trends of pressure and volume consumption in the primary gas path and the changing trends of pressure and volume consumption in any gas flow monitoring device (numbered 2-N) in the secondary gas path meet the requirements.

[0199] In summary, only when both of the above two leakage characteristics are met can it be determined that a leak has occurred between the primary and secondary gas lines; otherwise, it can be considered a suspected leak.

[0200] In one embodiment, a gas chromatograph leakage monitoring method based on dynamic volume balance includes the following steps: acquiring the flow rate measurement values ​​of the carrier gas in the primary gas path, the flow rate measurement values ​​of the carrier gas in the secondary gas path, and a first correction value in the pipeline between the primary and secondary gas paths; calculating a primary volume imbalance term based on the flow rate measurement values ​​of the carrier gas in the primary gas path, the flow rate measurement values ​​of the carrier gas in the secondary gas path, and the first correction value in the pipeline between the primary and secondary gas paths using the dynamic volume balance method; acquiring a frame of flow signal data to be processed with a time length of T, and calculating a first mean value based on the data to be processed; calculating a first leakage rate between the primary and secondary gas paths based on the primary volume imbalance term and the first mean value, and judging the leakage situation between the primary and secondary gas paths based on the first leakage rate.

[0201] The method for determining the leakage between the primary and secondary gas paths based on the first leakage rate includes the following steps: if the first leakage rate is greater than a preset leakage threshold, the duration of the third abnormal signal is obtained; if the duration of the third abnormal signal is greater than a preset time threshold, it is determined that there is an abnormality in the carrier gas delivery between the primary and secondary gas paths.

[0202] Reference Figure 5 , Figure 5 This is a schematic diagram of a gas chromatograph leak monitoring and response system based on dynamic volume balance, provided as an embodiment of the present invention.

[0203] In one embodiment, a gas chromatograph leakage monitoring and response system based on dynamic volume balance includes: a gas flow monitoring device for acquiring the flow rate measurement values ​​of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and a second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph; a volume imbalance term calculation module, communicatively connected to the gas flow monitoring device, for calculating a secondary volume imbalance term based on the flow rate measurement values ​​of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the inlet, the flow rate measurement value of the carrier gas at the detector, and the second correction value using a dynamic volume balance method; a mean value calculation module for acquiring a frame of flow signal data to be processed with a time length of T, and calculating a second mean value based on the data to be processed; and a leakage judgment module, communicatively connected to the volume imbalance term calculation module and the mean value calculation module, for calculating a second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean value, and judging the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

[0204] Furthermore, the gas chromatograph leak monitoring and response system based on dynamic volume balance also includes a response module, which is communicatively connected to the leak judgment module. The response module is used to generate corresponding control commands based on the type of leaked gas and the leak situation.

[0205] The response module can automatically take appropriate action based on the leak assessment results. In the event of a hydrogen gas leak, it can automatically and promptly stop the supply of hydrogen in the primary or secondary gas circuits without requiring technicians to manually shut off the gas source on-site. This avoids placing the gas chromatograph and the technicians using it in a dangerous environment, and also allows technicians to operate and control it remotely, making it safer, more reliable, efficient and convenient for technicians to work.

[0206] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0207] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0208] Furthermore, one embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions that are executed by a processor or controller, for example, by a processor in the above-described terminal embodiment, such that the processor performs the gas chromatograph leak monitoring method based on dynamic volume balance in the above-described embodiment.

[0209] Those skilled in the art will understand that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information transmission medium.

[0210] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present invention.

[0211] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A gas chromatograph leak monitoring method based on dynamic volume balance, characterized in that, Includes the following steps: The flow rate of the carrier gas in the secondary gas path, the total flow rate of the carrier gas at the gas chromatograph inlet, the flow rate of the carrier gas at the gas chromatograph detector, and the second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph are obtained. The second-stage volume imbalance term is calculated based on the dynamic volume balance method using the measured flow rate of the carrier gas in the second-stage gas path, the measured total flow rate of the carrier gas at the inlet, the measured flow rate of the carrier gas at the detector, and the second correction value. Obtain a frame of traffic signal data with a time length of T to be processed, and calculate the second mean value based on the data to be processed; The second leakage rate between the secondary gas path and the gas chromatograph is calculated based on the secondary volume imbalance term and the second mean, and the leakage situation between the secondary gas path and the gas chromatograph is judged based on the second leakage rate. Obtaining the second calibration value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph includes the following steps: Obtain the pressure P1 at the start point and P2 at the end point of the secondary gas pipeline, the pipeline inner diameter D, the hydraulic friction coefficient τ, the relative density ρ of the carrier gas, the carrier gas compressibility factor Z, the gas temperature T, and the pipeline length L. Calculate the corrected value of the carrier gas volume per second in the secondary gas pipeline under standard conditions. : ； The corrected value for the carrier gas volume per second in the secondary gas pipeline under actual conditions is calculated based on the corrected value of the carrier gas volume per second in the secondary gas pipeline under standard conditions. : ； according to The second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph is calculated within a preset time period; After calculating the second-order volume imbalance term of the carrier gas in the second-order gas path based on the dynamic volume balance method, the following steps are included: Under normal gas path conditions, determine the secondary volume imbalance term V of the carrier gas in the secondary gas path. B The mean θ0 and the standard deviation σ0 of (t); Based on data from gas leak scenarios, alternative hypotheses θ were determined. x : ； In the formula, V 二级 a represents the current volumetric consumption of carrier gas in the secondary gas path. x For θ x The corresponding coefficients are calculated based on the prior distribution function of the carrier gas leakage. Collect data for judgment and testing; after the y-th sample, the alternative hypothesis is θ. x The decision function is: ； Where n is the maximum value of a single sample, which is corrected using a function compensation method. The corrected decision function is R. x * (y), if R x (y)≥0, then R x * (y)=R x (y), if R x (y) < 0, R x * (y)=0; Leakage detection; α is the false alarm rate of the leakage monitoring system, β is the leakage alarm rate of the leakage monitoring system, and α and β are both 0.5%. Therefore, the threshold of the decision function is {0, ln[(1-β) / α]}; when R... x * When (y) ≥ ln[(1-β) / α], a leak occurs between the secondary gas path and the gas chromatograph.

2. The gas chromatograph leakage monitoring method based on dynamic volume balance according to claim 1, characterized in that, Determining the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate includes the following steps: If the second leakage rate is greater than the preset leakage threshold, the duration of the first abnormal signal is obtained; If the duration of the first abnormal signal is greater than a preset time threshold, it is determined that there is a carrier gas delivery abnormality between the secondary gas path and the gas chromatograph.

3. The gas chromatograph leakage monitoring method based on dynamic volume balance according to claim 2, characterized in that, After determining that there is an abnormality in carrier gas delivery between the secondary gas path and the gas chromatograph, the steps include: Determine whether the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend, and whether the volume consumption of carrier gas shows an upward trend. When the pressure of the gas flow monitoring device on the secondary gas path shows a downward trend and the volume consumption of carrier gas shows an upward trend, the duration of the second abnormal signal is obtained. If the duration of the second abnormal signal is greater than a preset time threshold, it is determined that there is a leak between the secondary gas path and the gas chromatograph.

4. The gas chromatograph leakage monitoring method based on dynamic volume balance according to claim 2, characterized in that, After determining that there is an abnormality in carrier gas delivery between the secondary gas path and the gas chromatograph, the steps include: Compared with historical data, does the carrier gas volume consumption in the secondary gas path show an upward trend, and does the pressure show a downward trend? The method for judging the trend of carrier gas volume consumption is as follows: Extract V 二级 Data, V 二级 Let V be the current volumetric consumption of carrier gas in the secondary gas path. 二级 The first curve changing over time; Extract the method parameters of GC on the current secondary gas path. In the historical database, query all data on the same day that are consistent with the method parameters of GC on the current secondary gas path, and extract V values ​​with the same time length as those in the first curve. 二级f The data, and calculate V 二级f The second curve, which changes over time, is used to determine whether there is a leak between the secondary gas path and the gas chromatograph by comparing the difference between the first curve and the second curve.

5. The gas chromatograph leakage monitoring method based on dynamic volume balance according to claim 1, characterized in that, Includes the following steps: Obtain the flow rate measurement values ​​of the carrier gas in the primary gas path, the flow rate measurement values ​​of the carrier gas in the secondary gas path, and the first correction value in the pipeline between the primary and secondary gas paths; Based on the dynamic volume balance method, the first-level volume imbalance term is calculated according to the measured flow rate of the carrier gas in the first-level gas path, the measured flow rate of the carrier gas in the second-level gas path, and the first correction value in the pipeline between the first-level and second-level gas paths. Obtain a frame of traffic signal data to be processed with a time length of T, and calculate the first mean value based on the data to be processed; The first leakage rate between the primary gas path and the secondary gas path is calculated based on the first-level volume imbalance term and the first mean value, and the leakage situation between the primary gas path and the secondary gas path is judged based on the first leakage rate.

6. The gas chromatograph leakage monitoring method based on dynamic volume balance according to claim 5, characterized in that, Determining the leakage situation between the primary and secondary gas circuits based on the first leakage rate includes the following steps: If the first leakage rate is greater than a preset leakage threshold, obtain the duration of the third abnormal signal; If the duration of the third abnormal signal is greater than the preset time threshold, it is determined that there is an abnormality in the carrier gas delivery between the primary gas path and the secondary gas path.

7. A gas chromatograph leak monitoring and response system based on dynamic volume balance, characterized in that, The system employs the gas chromatograph leak monitoring method based on dynamic volume balance as described in any one of claims 1-6, and comprises: A gas flow monitoring device is used to acquire the flow rate measurement value of the carrier gas in the secondary gas path, the total flow rate measurement value of the carrier gas at the gas chromatograph inlet, the flow rate measurement value of the carrier gas at the gas chromatograph detector, and the second correction value of the carrier gas in the pipeline between the secondary gas path and the gas chromatograph. The volume imbalance term calculation module is communicatively connected to the gas flow monitoring device. Based on the dynamic volume balance method, it calculates the secondary volume imbalance term according to the measured flow rate of the carrier gas in the secondary gas path, the measured total flow rate of the carrier gas at the inlet end, the measured flow rate of the carrier gas at the detector end, and the second correction value. The mean calculation module is used to acquire the data to be processed of a flow signal with a time length of T, and calculate the second mean based on the data to be processed. The leakage detection module is communicatively connected to the volume imbalance calculation module and the mean calculation module. It is used to calculate the second leakage rate between the secondary gas path and the gas chromatograph based on the secondary volume imbalance term and the second mean, and to determine the leakage situation between the secondary gas path and the gas chromatograph based on the second leakage rate.

8. The gas chromatograph leak monitoring and response system based on dynamic volume balance according to claim 7, characterized in that, Also includes: The response module is communicatively connected to the leakage detection module, and the response module is used to generate corresponding control commands based on the type of leaked gas and the leakage situation.

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