A continuous monitoring system and method for non-methane hydrocarbon emissions from exhaust gas

Abstract

The application discloses a kind of waste gas non-methane total hydrocarbon emission continuous monitoring system and method, it is related to environmental monitoring related technical field, the system includes: connection acquisition device, from waste gas source extraction obtains the gas to be measured;Gas chromatography separation is carried out, and the separated component is determined;Detection is carried out by hydrogen flame ionization detector, generates ion flow, and converts to obtain current signal;Weak current analysis is carried out, and concentration-signal relationship is fitted to be established;Real-time gas to be measured is extracted and is passed through processing, and concentration-signal relationship is combined, and real-time concentration is generated;Real-time concentration is output by monitoring interface.It is difficult to carry out continuous monitoring to effectively extract and separate different pollutant components in the prior art, which leads to the technical problems of insufficient accuracy and timeliness of the emission monitoring results, and achieves the technical effects of improving the accuracy and timeliness of the emission monitoring results.

Description

Technical Field

[0001] This application relates to the field of environmental monitoring technology, specifically to a continuous monitoring system and method for non-methane total hydrocarbon emissions from exhaust gas. Background Technology

[0002] Waste gas emission monitoring is a crucial component of environmental protection and pollution control. Non-methane hydrocarbons (NMHCs) are a significant pollutant in industrial production and energy consumption. NMHCs, primarily including hydrocarbons such as alkenes, aromatics, and alkanes, pose a potential hazard to ambient air quality and human health. They are highly volatile and flammable, thus requiring precise and real-time monitoring. Currently, monitoring methods for NMHCs in waste gas mainly include gas chromatography, infrared absorption, and chemiluminescence. These methods typically rely on complex equipment and time-consuming analytical processes, and suffer from limitations such as insufficient real-time performance, difficult equipment maintenance, and poor environmental adaptability. With increasingly stringent environmental requirements and higher demands for monitoring accuracy, traditional monitoring methods cannot achieve real-time online monitoring and rapid response, making them ill-suited to the demands for efficient and continuous monitoring in industrial waste gas emissions.

[0003] Therefore, current technologies face the challenge of continuous monitoring to effectively extract and separate different pollutant components, resulting in insufficient accuracy and timeliness of emission monitoring results. Summary of the Invention

[0004] This application provides a continuous monitoring system and method for non-methane total hydrocarbon emissions from exhaust gas, which solves the technical problem in the prior art that it is difficult to conduct continuous monitoring to effectively extract and separate different pollutant components, resulting in insufficient accuracy and timeliness of emission monitoring results, and achieves the technical effect of improving the accuracy and timeliness of emission monitoring results.

[0005] This application provides a continuous monitoring system for non-methane total hydrocarbon emissions from waste gas. The system includes: a gas extraction module for connecting to a data acquisition device to extract the gas to be tested from a waste gas source; a component separation module for injecting the gas to be tested into a gas chromatograph for gas chromatographic separation to determine the separated components; a current signal acquisition module for detecting the separated components as they exit the gas chromatograph using a flame ionization detector to generate an ion flow and convert it into a current signal; a weak current analysis module for performing weak current analysis based on the current signal, comparing it with the standard gas concentration-standard gas response signal relationship, and fitting to establish a concentration-signal relationship; a real-time concentration generation module for extracting the real-time gas to be tested and processing it through the gas chromatograph and the flame ionization detector, and combining it with the concentration-signal relationship to generate a real-time concentration; and a real-time concentration output module for outputting the real-time concentration through a monitoring interface.

[0006] In a possible implementation, the component separation determination module further performs the following processing: identifying the components of the gas to be tested through the air inlet; heating and evaporating the non-gaseous components according to a preset heating temperature until the non-gaseous components are completely converted into gaseous components to obtain a sample gas, wherein the air inlet is connected to the gas chromatograph; calculating the amount of separated components per unit time based on the column capacity of the chromatographic column in the gas chromatograph to obtain the injection volume; and injecting the sample gas into the gas chromatograph with the injection volume.

[0007] In a possible implementation, the separation component determination module further performs the following processing: calculating the retention time by means of the interaction between the chromatographic column and the sample gas; identifying the gas components in the sample gas based on the retention time to obtain the separated components, wherein the gas components are quantified based on the detector response signal to obtain the component concentration, and correlated with the separated components.

[0008] In a possible implementation, the weak current analysis module further performs the following processing: identifying the current signal based on a weak current signal threshold to obtain a weak current signal; extracting a first weak current signal based on the weak current signal; performing signal enhancement and noise suppression on the first weak current signal to obtain a first gain current signal; calculating the ratio of the first gain current signal to the standard gas concentration-standard gas response signal relationship to generate a first weak concentration; calculating the concentration by iterating through the weak current signals using the first weak concentration until the Nth weak concentration, obtaining N weak concentrations; and establishing the concentration-signal relationship by performing polynomial fitting based on the proportional coefficients of the N weak current signals and the N weak concentrations.

[0009] In a possible implementation, the weak current analysis module further performs the following processing: dividing the scaling factor into a training set and a validation set, wherein the training set is used to train the model architecture of the concentration-signal relationship, and the validation set is used to validate the model architecture of the concentration-signal relationship and output predicted values; calculating the mean absolute error between the predicted values ​​and the true values ​​in the training set; evaluating the prediction accuracy of the model architecture of the concentration-signal relationship based on the error range using the mean absolute error; and adjusting the scaling factor through the evaluation coefficient to obtain the concentration-signal relationship.

[0010] In a possible implementation, the weak current analysis module further performs the following processing: introducing an online standard gas through the hydrogen flame ionization detector and performing a real-time calibration response; based on the triggering of the real-time calibration response, calculating the offset between the online standard gas and the standard gas concentration-standard gas response signal relationship; performing incremental calibration on the concentration-signal relationship with the offset to obtain a locally optimized concentration-signal relationship; and fusing the locally optimized concentration-signal relationship into the concentration-signal relationship.

[0011] In a possible implementation, the real-time concentration output module further performs the following processing: generating a real-time trend chart of the real-time concentration based on the monitoring interface; setting an environmental protection concentration threshold based on environmental protection standards and a safe concentration threshold based on a safe range; generating a first warning by identifying the real-time trend chart using the environmental protection concentration threshold and generating a second warning by identifying the real-time trend chart using the safe concentration threshold; and outputting the first warning and the second warning respectively through the monitoring interface.

[0012] This application also provides a method for continuous monitoring of non-methane total hydrocarbon emissions from exhaust gas. The method includes: connecting a data acquisition device to extract a gas to be tested from an exhaust gas source; injecting the gas to be tested into a gas chromatograph for gas chromatographic separation to determine the separated components; detecting the separated components as they exit the gas chromatograph using a flame ionization detector to generate an ion flow and converting it into a current signal; performing weak current analysis based on the current signal, comparing it with the standard gas concentration-standard gas response signal relationship, and fitting to establish a concentration-signal relationship; extracting the real-time gas to be tested for processing by the gas chromatograph and the flame ionization detector, and combining it with the concentration-signal relationship to generate a real-time concentration; and outputting the real-time concentration through a monitoring interface.

[0013] This application proposes a continuous emission monitoring system and method for non-methane total hydrocarbons in exhaust gas. The system involves connecting a data acquisition device to extract the target gas from the exhaust gas source; performing gas chromatography separation to determine the separated components; detecting the components using a flame ionization detector to generate an ion current, which is then converted into a current signal; performing weak current analysis to establish a concentration-signal relationship; extracting the real-time target gas for processing and, based on the concentration-signal relationship, generating a real-time concentration; and outputting the real-time concentration through a monitoring interface. This method solves the technical problem in existing technologies where continuous monitoring is difficult to effectively extract and separate different pollutant components, leading to insufficient accuracy and timeliness of emission monitoring results. It achieves the technical effect of improving the accuracy and timeliness of emission monitoring results. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments of this disclosure will be briefly described below. Flowcharts are used in this application to illustrate the operations performed by the system according to the embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, various steps can be processed in reverse order or simultaneously as needed. Furthermore, other operations can be added to these processes, or one or more steps can be removed from these processes.

[0015] Figure 1 This is a schematic diagram of a continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas, provided as an embodiment of this application.

[0016] Figure 2 This is a schematic flowchart of a method for continuous monitoring of non-methane total hydrocarbon emissions from exhaust gas, provided in an embodiment of this application.

[0017] Explanation of reference numerals in the attached figures: 10 for gas extraction module, 20 for component separation determination module, 30 for current signal acquisition module, 40 for weak current analysis module, 50 for real-time concentration generation module, and 60 for real-time concentration output module. Detailed Implementation

[0018] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below.

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description of this application will be provided in conjunction with the accompanying drawings. The described embodiments should not be considered as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In the following description, references to "some embodiments" describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same or different subsets of all possible embodiments and can be combined with each other without conflict. The terms "first" and "second" are used merely to distinguish similar objects and do not represent a specific ordering of objects. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, system, product, or server that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or modules not explicitly listed or inherent to these processes, products, or devices. Unless otherwise defined, 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. The terminology used herein is for the purpose of describing embodiments of this application only.

[0021] This application provides a continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas, such as... Figure 1 As shown, the system includes: The gas extraction module 10 is used to connect to the acquisition device and extract the gas to be tested from the exhaust gas source.

[0022] Preferably, the gas to be tested is collected from the exhaust gas source (such as the exhaust gas emission pipe of a factory or an industrial chimney) by means of a gas sampling device. Specifically, the sampling device connected to the exhaust gas source uses a sampling probe installed at the exhaust port or pipe of the exhaust gas source to directly contact the exhaust gas and collect the gas to be tested, thereby extracting the gas to be tested in real time.

[0023] The separation component determination module 20 is used to inject the gas to be tested into a gas chromatograph for gas chromatographic separation and to determine the separated components.

[0024] Preferably, the gas to be tested extracted by the collection device is injected into a gas chromatograph for gas chromatographic separation. The gas chromatograph is used to analyze the components in the gas sample and separates them based on the different partition characteristics of the components in the stationary phase and the mobile phase. Specifically, the gas to be tested is injected into the chromatographic column (a thin tube) through a microsyringe (such as in a gas sample bottle). Gas chromatographic separation is based on the difference in the partition coefficient of the gas components in the chromatographic column. The chromatographic column is filled with a stationary phase (usually a solid or liquid material coated inside the thin tube), while the mobile phase is a gaseous carrier gas (such as nitrogen, helium, etc.). After the gas to be tested is injected, as the carrier gas flows, the gas components interact with the stationary phase in the column. Each component has a different migration rate due to its different affinity for the stationary phase, and is thus separated. Specifically, the gas to be tested enters the chromatographic column through the injection port of the gas chromatograph. Different components in the sample have different degrees of interaction with the stationary phase of the chromatographic column due to their physicochemical properties (such as volatility, polarity, molecular weight, etc.), resulting in different residence times in the chromatographic column. Inside the chromatographic column, the components undergo processes such as partitioning, adsorption, and desorption, and move forward together with the carrier gas. Finally, the different components are separated and leave the chromatographic column at different time points. Through the separation by gas chromatography, each component in the gas to be tested will be detected individually, and the separated components will be determined. Thus, the gas components such as non-methane total hydrocarbons (such as olefins, aromatic hydrocarbons, and other organic compounds) in the waste gas sample can be separated and determined efficiently and accurately.

[0025] The current signal acquisition module 30 is used to detect the separated components as they flow out of the gas chromatograph using a hydrogen flame ionization detector, generate an ion flow, and convert it into a current signal.

[0026] Preferably, a flame ionization detector (FID) is used to detect the separated components, thereby generating corresponding electrical signals. After the gas sample is separated by the chromatographic column, it forms different gas components that elute sequentially from the column at different times (i.e., residence times). The FID is placed after the gas chromatograph and detects the separated components as they elute. The FID is a commonly used detector in gas chromatography for detecting organic gas components, especially suitable for analyzing organic gases such as non-methane hydrocarbons. The core of the FID is the flame, typically formed by the combustion of a mixture of hydrogen (H2) and air (O2). Specifically, when organic compounds (analyte gases, such as hydrocarbons) pass through the flame, they undergo ionization. In the ionization reaction, gas molecules react with hydrogen atoms in the flame to produce positively charged ions and free electrons, i.e., positive ions (H⁺) and free electrons (e⁻). The collision of ions and electrons generates an electric current, and this current signal is proportional to the gas concentration. The hydrogen flame ionization detector has two electrodes: a combustion electrode and a collection electrode. When the separated organic gases (such as hydrocarbon components in non-methane total hydrocarbons) come into contact with the flame, they react chemically with the hydrogen in the flame to generate positively charged ions and free electrons. These charged particles (ion current) are guided to the collection electrode by an electric field, thereby generating a current signal that reflects the concentration of the analyzed gas component. The stronger the signal, the higher the concentration of organic gases in the sample.

[0027] The weak current analysis module 40 is used to perform weak current analysis based on the current signal, compare it with the standard gas concentration-standard gas response signal relationship, and fit to establish a concentration-signal relationship.

[0028] Preferably, a weak current analysis is performed on the current signal generated by the hydrogen flame ionization detector. Specifically, the current signal is amplified and filtered by electronic circuitry to obtain more stable current data, which is then compared with the standard gas concentration-standard gas response signal relationship. Here, the standard gas (also called standard gas) refers to a standard gas sample with a known concentration. The standard gas concentration-standard gas response signal relationship is the correspondence between the concentration of the standard gas and the current signal it generates. That is, changes in gas concentration will cause changes in the current signal, and this change is predictable. The detector is calibrated using a standard gas of known concentration. By using standard gas of different concentrations, a response curve between concentration and current signal can be plotted. Then, the concentration of the standard gas is compared with the output current signal data to obtain a set of corresponding data. These data are then fitted using a mathematical model (such as linear regression, nonlinear regression, etc.) to obtain the functional relationship between concentration and current signal. That is, a nonlinear regression model (such as exponential model, polynomial model, etc.) is used for fitting to represent the proportional relationship between concentration and current signal, i.e., establishing the concentration-signal relationship.

[0029] The real-time concentration generation module 50 is used to extract the gas to be tested in real time, process it through the gas chromatograph and the hydrogen flame ionization detector, and generate the real-time concentration by combining the concentration-signal relationship.

[0030] Preferably, by real-time sampling and processing of the gas sample to be tested, and utilizing the combined action of a gas chromatograph and a flame ionization detector, combined with a pre-established concentration-signal relationship (i.e., calibration curve), the gas concentration is analyzed and calculated in real time, thereby generating a real-time concentration. Specifically, the gas sample to be tested, including pollutants such as non-methane hydrocarbons (NMHC), is continuously collected from the exhaust gas source during the exhaust gas monitoring process by a collection device. The collected gas sample is then injected into the gas chromatograph, which separates different components (such as various hydrocarbon compounds) in the gas sample. After each component is separated in the chromatographic column, it will be... The gas flows out and enters the downstream detector for detection. The high-temperature flame generated by hydrogen combustion ionizes the organic components in the gas, generating an ion stream. Under the influence of an electric field, this stream produces a current signal, the intensity of which is proportional to the concentration of the organic components in the gas. Finally, the current signal of the gas to be measured is compared with the established concentration-signal relationship to calculate the concentration of the gas in real time. For example, if the real-time signal is a specific current value, the system converts the current value into the corresponding concentration (such as ppm or ppb) through this relationship, thereby achieving continuous, real-time, and accurate monitoring of the concentration of harmful substances (such as non-methane total hydrocarbons) in the exhaust gas.

[0031] The real-time concentration output module 60 is used to output the real-time concentration through a monitoring interface.

[0032] Preferably, the real-time gas concentration data obtained by the hydrogen flame ionization detector and gas chromatograph is displayed and monitored through a monitoring interface. This means the data is presented to the user in a visual and operable manner. Specifically, the monitoring interface is typically a graphical user interface that provides real-time data display via a computer or dedicated monitoring equipment. For example, the monitoring interface displays real-time gas concentration data (such as ppm or ppb values) and shows the concentration trend over time. In addition to real-time data display, the monitoring interface has alarm and warning functions, enabling managers to monitor the emission status at any time and react quickly. For instance, when the gas concentration exceeds a preset threshold, the system will issue an alarm, reminding staff to take appropriate measures to address the emission of high-concentration pollutants. This facilitates real-time and accurate monitoring of pollutant emissions and improves the environmental friendliness and compliance of the production process.

[0033] Furthermore, the specific configuration of the component separation determination module 20 also includes: identifying the components of the gas to be tested through the air inlet; heating and evaporating the non-gaseous components according to a preset heating temperature until the non-gaseous components are completely converted into gaseous components to obtain a sample gas; wherein the air inlet is connected to the gas chromatograph; calculating the amount of separated components per unit time based on the column capacity of the chromatographic column in the gas chromatograph to obtain the injection volume; and injecting the sample gas into the gas chromatograph with the injection volume.

[0034] Preferably, the air inlet may be equipped with a sensor or a simple gas analysis device to identify the components of the gas to be tested. The gas to be tested may contain some non-gaseous components (such as solid or liquid pollutants, particulate matter, or moisture), which must be converted into gaseous state through heating and evaporation before subsequent gas analysis can be performed. Specifically, by controlling the heating temperature, the non-gaseous components (such as liquid or solid substances) are completely converted into gaseous state at a certain temperature, ensuring that all components are completely converted into gaseous state before entering the gas chromatograph. The gas sample after heating is called the sample gas, which is the completely vaporized gas to be tested, and can be sent to the gas chromatograph for detailed detection. The air inlet is connected to the gas chromatograph through a pipe or sampling device to ensure that the sample gas can enter the gas chromatograph for separation and detection.

[0035] Preferably, in gas chromatography analysis, the chromatographic column separates gas components based on their physicochemical properties (such as molecular weight, volatility, polarity, etc.). Through the design and capacity of the chromatographic column, the analytical instrument can calculate how many gas sample components (usually expressed as volume or mass) the column can separate per unit time, thus determining the injection volume—the volume of sample gas injected into the chromatograph for each analysis. This volume must match the separation capacity of the chromatographic column to ensure accurate and stable separation results. Finally, based on the calculated appropriate injection volume, the sample gas is precisely injected into the gas chromatograph. The size of the injection volume determines the amount of sample gas entering the chromatograph. Specifically, after the sample gas is injected into the gas chromatograph's inlet, it rapidly passes through the chromatographic column, where it is separated according to its different gas components. The separated components are displayed as peaks on the gas chromatogram. Ultimately, based on these signals, the concentration and characteristics of each component can be determined, ensuring the accuracy and efficiency of the analysis and providing precise gas component analysis results.

[0036] Furthermore, the specific configuration of the separation component determination module 20 also includes: calculating the interaction time between the chromatographic column and the sample gas to obtain the retention time; identifying the gas components in the sample gas based on the retention time to obtain the separated components; wherein the gas components are quantified based on the detector response signal to obtain the component concentration, and correlated with the separated components.

[0037] Preferably, the interaction between the chromatographic column and the sample gas is used to analyze the components in the sample gas, determine the concentration of each component, and perform quantitative analysis based on the detector response signal. The chromatographic column is the core component of the gas chromatograph. It interacts with the components of the gas sample through a stationary phase (such as silica gel, polymer, or metal) that is filled or coated. Each gas component has a different affinity for the stationary phase based on its physicochemical properties (such as molecular weight, polarity, volatility, etc.), resulting in different flow rates within the column. Specifically, in a gas chromatograph, each component in the sample gas undergoes an interaction with the stationary phase after entering the column. This interaction time is called the retention time, which is the time required from the injection of the sample gas into the chromatograph to the component passing through the column and reaching the detector. The retention time of a component is the result of its interaction with the stationary phase; components with stronger affinity have longer retention times, while components with weaker affinity have shorter retention times.

[0038] Preferably, after the gas sample is separated by a chromatographic column, each component elutes from the column at different times (i.e., retention times). By recording and analyzing these retention times, the instrument can identify components based on known standard sample data. For example, by plotting a chromatogram in the chromatograph, each gas component forms a peak, and the peak's position corresponds to a specific retention time. By comparing these peaks with the retention times of known standard gases, analysts can determine which components are contained in the sample gas. After passing through the chromatographic column, the gas components are sent to a flame ionization detector (FID). The detector quantifies the gas components by generating a response signal, typically a current signal proportional to the gas concentration. The signal intensity (current magnitude) reflects the component concentration. Based on the response signal generated by the detector, each gas component is quantitatively analyzed. Specifically, through the concentration-signal relationship (calibration curve), the signal of each component is automatically correlated with its corresponding concentration based on the peaks and retention times in the chromatogram, thereby providing accurate gas composition analysis and concentration measurement.

[0039] Furthermore, the specific configuration of the weak current analysis module 40 also includes: identifying the current signal based on a weak current signal threshold to obtain a weak current signal; extracting a first weak current signal based on the weak current signal; performing signal enhancement and noise suppression on the first weak current signal to obtain a first gain current signal; calculating the ratio of the first gain current signal to the standard gas concentration-standard gas response signal relationship to generate a first weak concentration; calculating the concentration by traversing the weak current signals using the first weak concentration until the Nth weak concentration is obtained; and establishing the concentration-signal relationship by performing polynomial fitting based on the proportional coefficients of the N weak current signals and the N weak concentrations.

[0040] Preferably, the weak current signal threshold is a pre-set standard value that distinguishes between valid current signals and noise. Specifically, the current signal is compared with the weak current signal threshold to identify weak current signals, which are usually very small currents (possibly at the microampere level). Due to their low intensity, they may be interfered with by background noise. A first weak current signal is randomly selected from the obtained weak current signals. Then, the first weak current signal is subjected to signal enhancement and noise suppression. That is, the intensity of the valid signal is increased by using specific algorithms (such as amplification, filtering, etc.), while filtering techniques (such as low-pass filtering, high-pass filtering, band-pass filtering, etc.) are used to remove background noise (such as electrical noise, environmental noise, etc.) from the signal, thereby retaining the valid current signal, i.e., obtaining the first gain current signal. By calculating the ratio of the first gain current signal to the concentration-response signal during calibration, the weak concentration corresponding to the current signal (i.e., the first weak concentration) can be obtained, reflecting the relationship between signal strength and concentration, thereby realizing the quantitative determination of concentration.

[0041] Preferably, starting with the first weak concentration, the same calculation method is used to iterate through other weak current signals to calculate the concentration corresponding to each current signal. Each weak current signal is associated with a specific concentration value. The concentration corresponding to each current signal is continuously calculated based on the signal until N weak concentrations are obtained, where N is a positive integer representing the total number of weak current signals. Finally, a polynomial fitting is performed on the ratio coefficients between the N weak current signals and the N weak concentrations. The ratio coefficients refer to the conversion coefficients between the current signal and the concentration. Specifically, the relationship between the signal and the concentration is transformed into a mathematical model through mathematical methods (such as the least squares method), which is usually a polynomial function. For example, assuming that the relationship between concentration and signal is non-linear, a second-order, third-order, or higher-order polynomial may be used to represent this relationship during the fitting process. Through fitting, the system obtains a mathematical relationship between concentration and current signal, i.e., the concentration-signal relationship, which is used to convert the future acquired current signals into concentration data to achieve accurate measurement of the gas sample concentration.

[0042] Furthermore, the specific configuration of the weak current analysis module 40 also includes dividing the proportional coefficient into a training set and a validation set, wherein the training set is used to train the model architecture of the concentration-signal relationship, and the validation set is used to validate the model architecture of the concentration-signal relationship and output predicted values; calculating the mean absolute error between the predicted values ​​and the true values ​​in the training set; evaluating the prediction accuracy of the model architecture of the concentration-signal relationship based on the error range using the mean absolute error; and adjusting the proportional coefficient through the evaluation coefficient to obtain the concentration-signal relationship.

[0043] Preferably, the scaling factor is divided into a training set and a validation set. The training set is used to train the model architecture, that is, to adjust the model parameters (such as the scaling factor) based on the training data (including current signals and corresponding concentration data), so that the model can learn the relationship between signal and concentration. The validation set is used to validate the model architecture of the concentration-signal relationship, helping to test the model's predictive ability on unseen data. By inputting the current signal from the validation set, the model generates a predicted value (i.e., the predicted concentration). The absolute value of the difference between the predicted value and the true value is calculated, and then the average of these differences is obtained to quantitatively evaluate the model's predictive performance. The smaller the error, the more accurate the model's prediction. Finally, the mean absolute error is used to evaluate the predictive accuracy of the concentration-signal relationship model architecture, that is, using the average error. The accuracy of the model is evaluated using absolute error. A large error indicates poor prediction accuracy, while a small error indicates high accuracy. The scaling factor is then adjusted using evaluation coefficients. The mean absolute error reflects the model's prediction accuracy, while the evaluation coefficients indicate whether the model needs optimization. By analyzing the mean absolute error and its range, the scaling factor (concentration-signal conversion coefficient) can be adjusted. For example, if the model's prediction error is too large, the scaling factor may need to be readjusted, or the model architecture and training methods may need to be adjusted to improve accuracy. Ultimately, the concentration-signal relationship is obtained, enabling the accurate conversion of weak current signals into gas concentrations in practical applications, ensuring prediction accuracy, and achieving real-time, precise concentration measurement.

[0044] Furthermore, the specific configuration of the weak current analysis module 40 also includes: introducing an online standard gas through the hydrogen flame ionization detector to perform real-time calibration response; calculating the offset between the online standard gas and the standard gas concentration-standard gas response signal relationship based on the triggering of the real-time calibration response; performing incremental calibration on the concentration-signal relationship with the offset to obtain a locally optimized concentration-signal relationship; and fusing the locally optimized concentration-signal relationship into the concentration-signal relationship.

[0045] Preferably, the online standard gas is a gas sample of known concentration, typically used to determine the response of a gas detector (such as a flame ionization detector) to ensure the accuracy of the device. Specifically, by introducing an online standard gas into the flame ionization detector and measuring the response signal (usually a current signal) of this standard gas, the device can be calibrated in real time by comparing the detector's response with the known concentration of the online standard gas, ensuring that the detector maintains an accurate response to changes in gas concentration. Each time the standard gas is introduced, the detector triggers a calibration response, generating a corresponding current signal, thereby detecting the deviation between the current detector response and the known concentration of the standard gas, and calculating the offset. The offset refers to the difference between the current standard gas concentration - standard gas response signal relationship and the online standard gas concentration, which may be due to various factors. Factors (such as environmental changes, equipment aging, temperature, and humidity) cause shifts in the detector's response. The calculated shift is then used to incrementally calibrate the concentration-signal relationship. This involves making small adjustments to ensure the detector's response more accurately matches the concentration of the standard gas. Specifically, parameters in the concentration-signal model (such as the proportional gain) are adjusted based on the calculated shift to ensure the model accurately reflects the relationship between the actual concentration of the standard gas and the detection signal, thus obtaining a locally optimized concentration-signal relationship. This optimized relationship is then integrated into the original concentration-signal relationship to form a more accurate global concentration-signal relationship. This not only calibrates the response under the current conditions but also ensures the original model remains consistent under new data, thereby ensuring the instrument maintains a stable and highly accurate response under different times and conditions.

[0046] Furthermore, the specific configuration of the real-time concentration output module 60 also includes: generating a real-time trend chart of the real-time concentration based on the monitoring interface; setting an environmental protection concentration threshold based on environmental protection standards and a safe concentration threshold based on a safe range; generating a first warning by identifying the real-time trend chart using the environmental protection concentration threshold and generating a second warning by identifying the real-time trend chart using the safe concentration threshold; and outputting the first warning and the second warning respectively through the monitoring interface.

[0047] Preferably, a real-time trend chart is generated based on the real-time concentration data (i.e., the change of gas concentration over time) from the monitoring interface. This chart displays the dynamic trend of gas concentration changes over time, helping operators to intuitively view changes in pollutant concentration and thus respond promptly. Environmental concentration thresholds are set according to environmental standards (the maximum safe value that gas concentration must not exceed) to indicate when the concentration reaches or exceeds the environmental standards. For example, some harmful gases, such as sulfur dioxide and nitrogen oxides, have clear environmental concentration limits. Once the concentration exceeds this value, it may cause harm to the environment and human health. Safe concentration thresholds are then set according to the safe range (based on operational and personnel safety). These thresholds are usually set higher than the environmental thresholds to ensure that measures can be taken as early as possible when the concentration is too high, preventing harm to staff or facilities.

[0048] Preferably, when the concentration data in the real-time trend graph exceeds the set environmental protection concentration threshold, a first warning is generated, usually an environmental protection warning, prompting staff to take measures to reduce pollution emissions, adjust production processes, or perform other environmental control operations. When the concentration data in the real-time trend graph exceeds the set safety concentration threshold, a second warning is generated, notifying relevant personnel that the gas concentration has exceeded the safe range and may have a direct impact on operators or equipment. This warning is more urgent and usually triggers stronger response measures, such as personnel evacuation, equipment shutdown, and emission source closure, to ensure personnel safety and equipment operation are not threatened. Finally, the first and second warnings are displayed on the monitoring interface, and the operator is notified through warning boxes or graphical interfaces. For example, the colors of the warning boxes or icons may differ, such as green for normal, yellow / orange for the first warning, and red for the second warning. An audible alarm may be issued to ensure that staff can respond quickly, prevent environmental pollution and personal injury, and ensure the safety of the production process and compliance with environmental regulations.

[0049] In the above text, refer to Figure 1 A continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas according to an embodiment of the present invention is described in detail. Next, reference will be made to... Figure 2 A method for continuous monitoring of non-methane total hydrocarbon emissions from exhaust gas is described according to an embodiment of the present invention.

[0050] A method for continuous monitoring of non-methane total hydrocarbon emissions from exhaust gas, such as Figure 2As shown, the method includes: connecting a data acquisition device to extract the gas to be tested from the waste gas source; injecting the gas to be tested into a gas chromatograph for gas chromatographic separation to determine the separated components; detecting the separated components as they flow out of the gas chromatograph using a flame ionization detector to generate an ion flow and convert it into a current signal; performing weak current analysis based on the current signal, comparing it with the standard gas concentration-standard gas response signal relationship, and fitting to establish a concentration-signal relationship; extracting the real-time gas to be tested for through-processing by the gas chromatograph and the flame ionization detector, and combining it with the concentration-signal relationship to generate a real-time concentration; and outputting the real-time concentration through a monitoring interface.

[0051] In one possible implementation, the method for continuous monitoring of non-methane total hydrocarbon emissions from exhaust gas further includes: identifying the components of the gas to be tested through an air inlet; heating and evaporating the non-gaseous components according to a preset heating temperature until the non-gaseous components are completely converted into gaseous components to obtain a sample gas; wherein the air inlet is connected to the gas chromatograph; calculating the amount of separated components per unit time based on the column capacity of the chromatographic column in the gas chromatograph to obtain the injection volume; and injecting the sample gas into the gas chromatograph using the injection volume.

[0052] In one possible implementation, the method for continuous monitoring of non-methane total hydrocarbon emissions from exhaust gas further includes: calculating the retention time by means of the interaction between the chromatographic column and the sample gas; identifying gas components in the sample gas based on the retention time to obtain separated components, wherein the gas components are quantified based on the detector response signal to obtain component concentrations, and correlated with the separated components.

[0053] In one possible implementation, the continuous monitoring method for non-methane total hydrocarbon emissions in exhaust gas further includes: identifying the current signal based on a weak current signal threshold to obtain a weak current signal; extracting a first weak current signal based on the weak current signal; performing signal enhancement and noise suppression on the first weak current signal to obtain a first gain current signal; calculating the ratio of the first gain current signal to the standard gas concentration-standard gas response signal relationship to generate a first weak concentration; calculating the concentration by iterating through the weak current signals using the first weak concentration until the Nth weak concentration is obtained; and establishing the concentration-signal relationship by performing polynomial fitting based on the proportional coefficients of the N weak current signals and the N weak concentrations.

[0054] In one possible implementation, the continuous monitoring method for non-methane total hydrocarbon emissions in exhaust gas further includes: dividing the proportionality coefficient into a training set and a validation set, wherein the training set is used to train a model architecture for the concentration-signal relationship, and the validation set is used to validate the model architecture for the concentration-signal relationship and output predicted values; calculating the mean absolute error between the predicted values ​​and the true values ​​in the training set; evaluating the prediction accuracy of the model architecture for the concentration-signal relationship based on the mean absolute error, and adjusting the proportionality coefficient through the evaluation coefficient to obtain the concentration-signal relationship.

[0055] In one possible implementation, the continuous monitoring method for non-methane total hydrocarbon emissions in exhaust gas further includes: introducing an online standard gas through the hydrogen flame ionization detector and performing a real-time calibration response; calculating the offset between the online standard gas and the standard gas concentration-standard gas response signal relationship based on the triggering of the real-time calibration response; performing incremental calibration on the concentration-signal relationship with the offset to obtain a locally optimized concentration-signal relationship; and fusing the locally optimized concentration-signal relationship into the concentration-signal relationship.

[0056] In one possible implementation, the continuous monitoring method for non-methane total hydrocarbon emissions in exhaust gas further includes: generating a real-time trend graph of the real-time concentration based on the monitoring interface; setting an environmental concentration threshold based on environmental standards and a safe concentration threshold based on a safe range; generating a first warning by identifying the real-time trend graph using the environmental concentration threshold and generating a second warning by identifying the real-time trend graph using the safe concentration threshold; and outputting the first warning and the second warning respectively through the monitoring interface.

[0057] The continuous monitoring system for non-methane total hydrocarbon emissions in exhaust gas provided in this embodiment of the invention can execute the continuous monitoring method for non-methane total hydrocarbon emissions in exhaust gas provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0058] Although this application makes various references to certain modules in the system according to the embodiments of this application, any number of different modules can be used and run on user terminals and / or servers. The various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional unit are only for easy distinction between each other and are not used to limit the scope of protection of this invention.

[0059] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas, characterized in that, The system includes: The gas extraction module is used to connect to the acquisition device and extract the gas to be tested from the exhaust gas source; The component separation determination module is used to inject the gas to be tested into a gas chromatograph for gas chromatographic separation and to determine the separated components. The current signal acquisition module is used to detect the separated components as they flow out of the gas chromatograph using a flame ionization detector, generate an ion flow, and convert it into a current signal. The weak current analysis module is used to perform weak current analysis based on the current signal, compare it with the standard gas concentration-standard gas response signal relationship, and fit to establish a concentration-signal relationship. The real-time concentration generation module is used to extract the gas to be tested in real time, process it through the gas chromatograph and the hydrogen flame ionization detector, and generate the real-time concentration by combining the concentration-signal relationship. A real-time concentration output module is used to output the real-time concentration through a monitoring interface; The weak current analysis module includes: A current signal identification unit is used to identify the current signal based on a weak current signal threshold to obtain a weak current signal; The first weak current signal extraction unit is used to extract a first weak current signal based on the weak current signal. The first gain current signal acquisition unit is used to perform signal enhancement and noise suppression on the first weak current signal to obtain the first gain current signal. The first weak concentration generation unit is used to calculate the ratio of the first gain current signal to the standard gas concentration-standard gas response signal relationship, and generate the first weak concentration. A weak concentration acquisition unit is used to calculate the concentration by traversing the weak current signals with the first weak concentration until the Nth weak concentration, thereby obtaining N weak concentrations. A polynomial fitting unit is used to perform polynomial fitting based on the proportionality coefficients of N weak current signals and N weak concentrations to establish the concentration-signal relationship. The weak current analysis module includes: The scaling factor partitioning unit is used to partition the scaling factor into a training set and a validation set, wherein the training set is used to train the model architecture of the concentration-signal relationship, and the validation set is used to validate the model architecture of the concentration-signal relationship and output the predicted value. The mean absolute error calculation unit is used to calculate the mean absolute error between the predicted value and the true value in the training set. A scaling factor adjustment unit is used to evaluate the prediction accuracy of the concentration-signal relationship model architecture by combining the error range with the mean absolute error, and adjust the scaling factor by the evaluation factor to obtain the concentration-signal relationship; The weak current analysis module includes: A real-time calibration response unit is used to introduce online standard gas through the hydrogen flame ionization detector to perform real-time calibration response; The offset calculation unit is used to calculate the offset of the online standard gas relative to the standard gas concentration-standard gas response signal based on the triggering of the real-time calibration response. An incremental calibration unit is used to perform incremental calibration on the concentration-signal relationship with the offset to obtain a locally optimized concentration-signal relationship. The relationship fusion unit is used to fuse the local optimized concentration-signal relationship into the concentration-signal relationship.

2. The continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas as described in claim 1, characterized in that, The separated component determination module includes: The heating and evaporation unit is used to identify the components of the gas to be tested through the air inlet, and to heat and evaporate the non-gaseous components according to the preset heating temperature until the non-gaseous components are completely converted into gaseous components to obtain sample gas. The air inlet is connected to the gas chromatograph. The injection volume obtaining unit is used to calculate the amount of separated components per unit time based on the column capacity of the chromatographic column in the gas chromatograph, and obtain the injection volume. A sample gas injection unit is used to inject the sample gas into the gas chromatograph at the injection volume.

3. The continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas as described in claim 2, characterized in that, The separated component determination module includes: The retention time calculation unit is used to calculate the retention time by means of the interaction between the chromatographic column and the sample gas. A gas component quantification unit is used to identify gas components in the sample gas based on the retention time to obtain separated components. Specifically, gas component quantification is performed based on the detector response signal to obtain component concentrations, which are then correlated with the separated components.

4. The continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas as described in claim 1, characterized in that, The real-time concentration output module includes: A real-time trend chart generation unit is used to generate a real-time trend chart of the real-time concentration based on the monitoring interface. The safe concentration threshold setting unit is used to set environmental concentration thresholds according to environmental standards and to set safe concentration thresholds based on safe ranges. The real-time trend chart recognition unit is used to recognize the real-time trend chart through the environmental protection concentration threshold to generate a first warning, and to recognize the real-time trend chart through the safety concentration threshold to generate a second warning; The warning output unit is used to output the first warning and the second warning respectively through the monitoring interface.

5. A method for continuous monitoring of non-methane total hydrocarbon emissions from exhaust gas, characterized in that, The method is applied to a continuous monitoring system for non-methane total hydrocarbon emissions from exhaust gas according to any one of claims 1-4, the method comprising: Connect the data acquisition device to extract the gas to be tested from the exhaust gas source; The gas to be tested is injected into a gas chromatograph for gas chromatography separation to determine the separated components; When the separated components elute from the gas chromatograph, they are detected by a flame ionization detector to generate an ion stream, which is then converted into a current signal. Weak current analysis is performed based on the current signal, and a concentration-signal relationship is established by comparing it with the standard gas concentration-standard gas response signal relationship and fitting the signal. The gas to be tested is extracted in real time and processed by the gas chromatograph and the flame ionization detector, and the real-time concentration is generated by combining the concentration-signal relationship. The real-time concentration is output through the monitoring interface.

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