Limited space global gas monitoring security system based on multi-sensor heterogeneous fusion

Abstract

The invention relates to a limited space global gas monitoring security system based on multi-sensor heterogeneous fusion, and belongs to the technical field of limited space gas monitoring security of percolate and the like. An on-site instrument layer of the system comprises a multi-sensing heterogeneous fusion unit which is provided with a plurality of sampling points according to the actual working condition of the limited space area of the leachate of the waste incineration plant, and the multi-sensing heterogeneous fusion unit of the on-site instrument layer is connected with a distributed control layer and transmits monitoring data to the distributed control layer; the distributed control layer performs real-time alarm control and prevention and control measure instruction issuing according to the monitoring data; the distributed control layer further transmits the obtained monitoring data to the information management layer, and the information management layer supports data tracing, remote monitoring and decision analysis in the whole plant range. According to the invention, the problem that the existing electrochemical sensor is easily interfered by gas in high-humidity, dusty and complex-gas environments of percolate is effectively solved, and the problems of indicating value distortion such as false alarm, virtual high indicating value, full scale and the like are reduced.

Description

Technical Field

[0001] This invention belongs to the field of gas monitoring and security technology in confined spaces such as leachate, and relates to a confined space global gas monitoring and security system based on multi-sensor heterogeneous fusion. Background Technology

[0002] Currently, electrochemical sensors (such as CO alarms) are commonly used in the leachate area of ​​waste incineration plants. These sensors are easily affected by interfering gases such as alkanes and alkenes, leading to false alarms, falsely high readings, and full-scale distortions.

[0003] Existing fixed electrochemical gas detectors are designed for gas leak detection and alarm purposes, and are not suitable for gas detection in environments where toxic or harmful gases are generated. Furthermore, long-term use in complex background and interfering gas environments will accelerate the consumption of the electrochemical sensor electrolyte, eventually leading to aging and failure, resulting in distorted instrument readings. Currently available in China are fixed or extractable single / multi-group electrochemical gas detectors; no application examples of multimodal sensor array-type gas detectors have been found.

[0004] In confined spaces such as leachate areas of waste incineration plants in Europe, America, and Japan, sensors using electrochemical and catalytic combustion technologies are commonly employed. Although multi-sensor fusion technology (electrochemical + NDIR + FTIR + photoionization PID) has been applied, combined with gas pretreatment systems (dehumidification and dust removal) and AI algorithms to resist interference, enabling real-time monitoring of multiple parameters such as CO, CH4, H2S, O2, and VOCs, and with sensor lifespans exceeding two years, these sensors are mostly used for quantitative measurements at stationary pollution sources or ambient air monitoring sections, and are quite expensive.

[0005] In summary, the leachate collection areas (collection ponds and corridors) of waste incineration plants are typical high-risk confined spaces. Their harsh operating conditions—high humidity, high dust levels, strong corrosion, and complex background gases—lead to the severe failure of traditional electrochemical gas monitoring technologies, manifesting in three core challenges: Severe measurement distortion: The electrochemical CO sensor is subject to cross-interference from gases such as hydrogen and alkanes, resulting in falsely high readings or even full-scale readings (500ppm), inaccurate monitoring data, and rendering the early warning function ineffective.

[0006] The equipment has a very short lifespan and high maintenance costs: the complex gas environment causes the electrolyte of the CO sensor to be consumed rapidly, reducing its lifespan from the usual 1 year to 1-2 weeks. Spare parts need to be replaced frequently, resulting in a heavy maintenance burden.

[0007] Maintenance operations pose significant risks: personnel must frequently enter high-risk confined spaces to perform tasks such as cleaning, dredging, and maintenance, facing major safety threats such as poisoning and suffocation, creating the paradox of "taking risks to ensure safety." Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a security system for full-area gas monitoring in a limited space based on multi-sensor heterogeneous fusion.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A confined space gas monitoring and security system based on multi-sensor heterogeneous fusion comprises a field instrument layer, a distributed control system (DCS), and an information management system (MIS). The field instrument layer includes a multi-sensor heterogeneous fusion unit with multiple sampling points set according to the actual operating conditions of the confined space area of ​​a waste incineration plant's leachate. This multi-sensor heterogeneous fusion unit connects to the DCS and transmits monitoring data to it. The DCS then performs real-time alarm control and issues commands for prevention and control measures based on the monitoring data. Furthermore, the DCS transmits the acquired monitoring data to the MIS, which supports plant-wide data traceability, remote monitoring, and decision analysis. Combining the spatial distribution of the release source and ventilation airflow, the real-time monitoring of multiple systems by multi-sensor heterogeneous fusion units at multiple points forms a dynamic monitoring network. The actual ventilation efficiency is quantitatively evaluated through monitoring data, gas accumulation is identified, and the supply and exhaust systems are linked to control based on the quantitative evaluation results. The field instrument layer employs a multi-sensor heterogeneous fusion unit that uses measurement point polling and sensor reuse to reduce the number of gas detectors in the confined space of the leachate. The system is equipped with multiple sampling pipelines, each corresponding to a different measurement point. These multiple sampling pipelines are connected to a multi-sensor heterogeneous fusion unit that is organically combined in series and parallel with various types of gas sensors. The multi-sensor heterogeneous fusion unit includes methane detectors, hydrogen sulfide detectors, oxygen detectors, and carbon monoxide detectors. These detectors are organically combined based on their sampling flow characteristics. Furthermore, the carbon monoxide detector uses non-dispersive infrared detection technology to detect the concentration of carbon monoxide.

[0010] Furthermore, the field instrument layer includes a sampling unit, a purging unit, a pumping unit, a calibration unit, and a multi-sensor heterogeneous fusion unit. The sampling unit acquires sample gas from different monitoring points; the purging unit purges the sampling pipeline; the pumping unit delivers the sampled gas to the multi-sensor heterogeneous fusion unit for actual measurement; and the calibration unit calibrates the multi-sensor heterogeneous fusion unit. The extraction unit consists of two branches: an extraction pump and a pre-extraction pump. The extraction pump is connected to the sampling unit to form a sampling measurement loop, while the pre-extraction pump and the sampling unit form a prediction loop. Both the sampling measurement loop and the prediction loop are equipped with blockage alarms. In the sampling measurement loop, a filter and a condenser are connected in series between the extraction pump and the multi-sensor heterogeneous fusion unit. The filter is used to remove impurities, and the condenser is used to remove moisture from the gas. The condenser includes a gas supply pipe connected to the sensor unit and a drain pipe for discharging condensate. The measured gas and condensate are discharged into the confined space through the gas supply pipe and the drain pipe, respectively. The multi-sensor unit performs multi-type gas concentration detection. After detection, the gas is directly discharged into the confined space through the exhaust pipe.

[0011] Furthermore, the sampling unit includes several sampling valves and their corresponding sampling pipelines. The sampling valves are set at different measurement points and are connected to the corresponding sampling measurement loop and prediction loop in sequence through the sampling pipelines. The purging unit includes a backflush pressure stabilizing tank and a pulse purging valve group. The backflush pressure stabilizing tank and the pulse purging valve group are also connected to different sampling pipelines. During real-time sampling, the sampling valve at the corresponding measurement point is opened according to the control command to complete the gas detection at the corresponding measurement point. During purging, the sampling pipeline is purged sequentially according to the purging control command by using the backflush pressure stabilizing tank and pulse purging valve group.

[0012] Furthermore, the carbon monoxide detector includes an infrared emitter, a measuring chamber, an infrared detector, a preamplifier, a signal conditioning circuit, and a micro signal processor. The infrared emitter emits a constant infrared light source. Carbon monoxide absorbs part of the infrared light in the measuring chamber. The infrared detector receives the infrared light signal during the absorption process and transmits it to the micro signal processor through the preamplifier and signal conditioning circuit. The micro signal processor calculates the carbon monoxide concentration based on the infrared light signal emitted by the infrared emitter and the infrared light signal received by the infrared detector.

[0013] Furthermore, the process by which the micro-signal processor of the carbon monoxide detector processes the signals from the measurement channel and the reference channel is as follows: Demodulation: The amplitudes of the AC signals from the two channels are extracted based on the modulation frequency of the light source, and denoted as follows: and Their respective infrared light intensities are proportional to the intensity of their respective channels. and ; Ratio calculation: Calculate the ratio of the measurement channel signal to the reference channel signal. :

[0014] Based on the Lambert-Beer law, the concentration model is established as follows:

[0015]

[0016] in, A constant ratio Represented as:

[0017] Assuming a stable light source and a symmetrical system design ,therefore:

[0018] in , is a system constant; The resulting exponential relationship is transformed into a linear relationship through calibration. 1) Zero-point calibration: The ratio R0 measured in pure air when the carbon monoxide concentration is 0; 2) Range calibration: Measure a ratio Rspan in a standard carbon monoxide gas of known concentration; 3) The final concentration c is obtained by linear interpolation of R0, Rspan and the currently measured R or by calculation through a fitted curve.

[0019] Furthermore, the DCS layer is the central control unit of the gas monitoring system, responsible for data acquisition, real-time processing, alarm linkage and communication transmission. Among them, it receives real-time concentration data from the field instrument layer through the MODBUS RS485 protocol and performs verification and filtering on the raw data. Set the concentration alarm threshold for each gas. When the real-time concentration exceeds the limit, immediately trigger the audible and visual alarm and automatically start the supply and exhaust fans for ventilation and replacement.

[0020] Furthermore, the MIS layer serves as the remote management platform for the gas monitoring system, providing data visualization, data traceability, remote monitoring, and decision analysis functions. Data visualization includes real-time monitoring interface display, concentration change trend analysis, spatial distribution map display, and remote monitoring. Data traceability includes automatically generating gas concentration statistical reports by date and providing compliance reports. Decision analysis is based on the data visualization content and gas concentration statistics.

[0021] The beneficial effects of this invention are as follows: This invention employs multi-sensor heterogeneous fusion technology, organically combining a methane detection unit, a hydrogen sulfide detection unit, an oxygen detection unit, and a carbon monoxide detector using non-dispersive infrared detection technology. This effectively solves the problem of existing electrochemical sensors being susceptible to interference from H2 and alkane gases in high-humidity, dusty environments like leachate, avoiding false alarms, inaccurate readings, and full-scale distortion. It significantly extends the actual service life of the sensor and reduces the high maintenance costs associated with frequent sensor replacements.

[0022] The specific structure of the multi-sensor heterogeneous fusion unit of this invention provides strong support for eliminating monitoring blind spots. Each unit has several sampling interfaces, a standard input interface, and a high-pressure air input interface, connecting to different monitoring points. A flame arrester is connected in series after each sampling interface for safety. The sampling gas path is divided into two branches, connected in series with a solenoid valve and an on / off valve, respectively, and then connected to the main gas path and the exhaust gas path. Multiple devices are connected in series in the main gas path and then connected to the multi-sensor unit. Through polling of measurement points and sensor multiplexing, it can comprehensively cover confined spaces such as waste storage pits, leachate collection pools, and corridors, ensuring the safety of maintenance personnel entering high-risk areas for maintenance work and effectively preventing accidents such as poisoning or suffocation.

[0023] The multi-sensor heterogeneous fusion unit of this invention comprises two parallel detection branches. One branch connects a flow meter, an oxygen detection unit, a hydrogen sulfide detection unit, and a methane detection unit in series; the other branch connects a flow meter, a condensate separator, a thermometer, and a carbon monoxide detector in series, and finally merges into an exhaust gas path. This invention can simultaneously and accurately detect the concentrations of multiple key toxic and harmful gases, providing more comprehensive and accurate data support for determining the degree of leachate fermentation or the source of leakage.

[0024] The DCS layer of this invention serves as the central control unit, undertaking data acquisition, real-time processing, alarm linkage, and communication transmission functions. It receives real-time concentration data via the MODBUS RS485 protocol, performs verification and filtering to eliminate outliers, and promptly triggers audible and visual alarms based on set concentration alarm thresholds, notifying relevant personnel and automatically initiating control measures. The MIS layer provides data visualization, report generation, access control, and system maintenance functions, facilitating real-time data monitoring and analysis by management personnel for informed decision-making, thereby improving the overall management efficiency and effectiveness of the gas monitoring system.

[0025] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the gas path connection of the multi-sensor heterogeneous fusion unit in an embodiment of the present invention. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0029] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0030] Please see Figure 1 This is a finite space full-area gas monitoring and security system based on multi-sensor heterogeneous fusion.

[0031] Example This embodiment details a confined space-wide gas monitoring and security system based on multi-sensor heterogeneous fusion, comprising a field instrument layer, a distributed control system (DCS), and an information management system (MIS). The field instrument layer includes a multi-sensor heterogeneous fusion unit with several sampling points set according to the actual operating conditions of the confined space area of ​​the waste incineration plant leachate. This multi-sensor heterogeneous fusion unit connects to the DCS and transmits monitoring data to it. The DCS performs real-time alarm control and issues commands for prevention and control measures based on the monitoring data. The DCS also transmits the acquired monitoring data to the MIS, which supports plant-wide data traceability, remote monitoring, and decision analysis. Combining the spatial distribution of the release source and ventilation airflow, the real-time monitoring of multiple systems by multi-sensor heterogeneous fusion units at multiple points forms a dynamic monitoring network. The actual ventilation efficiency is quantitatively evaluated through monitoring data, gas accumulation is identified, and the supply and exhaust systems are linked to control based on the quantitative evaluation results. The field instrument layer employs a multi-sensor heterogeneous fusion unit that uses measurement point polling and sensor reuse to reduce the number of gas detectors in the confined space of the leachate. The system is equipped with multiple sampling pipelines, each corresponding to a different measurement point. These multiple sampling pipelines are connected to a multi-sensor heterogeneous fusion unit that is organically combined in series and parallel with various types of gas sensors. The multi-sensor heterogeneous fusion unit includes methane detectors, hydrogen sulfide detectors, oxygen detectors, and carbon monoxide detectors. These detectors are organically combined based on their sampling flow characteristics. Furthermore, the carbon monoxide detector uses non-dispersive infrared detection technology to detect the concentration of carbon monoxide.

[0032] In this embodiment, the DCS layer is the central control unit of the gas monitoring system, responsible for data acquisition, real-time processing, alarm linkage, and communication transmission functions, specifically including: Data acquisition and preprocessing: Real-time concentration data (CO, CH4, H2S, O2) from the field instrument layer (gas detectors) are received via the MODBUS RS485 protocol. The raw data is then validated and filtered.

[0033] Real-time monitoring and alarm management; Threshold setting: Alarm thresholds for each gas concentration are set according to national standards (e.g., GBZ 2.1-2019) and process safety requirements (e.g., CO level 1 alarm 25ppm, level 2 alarm 50ppm). Alarm triggering: When the real-time concentration exceeds the limit, an audible and visual alarm is immediately triggered, and relevant personnel are notified via SMS / APP. Linkage control: Automatically starts the supply and exhaust fans to adjust the ventilation volume, or closes relevant valves to prevent gas accumulation that could lead to explosions or poisoning accidents.

[0034] In this embodiment, the MIS layer is the remote management platform for the gas monitoring system, providing data visualization, report generation, access control, and system maintenance functions, specifically including: Data visualization and interaction; Real-time monitoring interface: Displays real-time concentrations, equipment status (e.g., detector online / offline), and alarm information at each monitoring point via web or client software. Trend analysis: Supports comparison of multiple gas concentration curves (e.g., correlation analysis of CO and CH4 concentration changes) to help determine the degree of leachate fermentation or the source of leakage. Spatial distribution map: Combines GIS technology to mark areas with excessive gas concentrations on the plant layout map, guiding inspection personnel to quickly locate potential hazards.

[0035] Reporting and Statistical Analysis; Automatic Report Generation: Generates daily / weekly / monthly gas concentration statistical reports (such as maximum value, average value, number of times exceeding the standard), supporting export to Excel or PDF format. Compliance Reports: Generates data reports that comply with GB12358-2024 "General Technical Requirements for Ambient Gas Detection and Alarm Instruments in the Workplace", GBZ-T223-2009 "Specifications for the Installation of Toxic Gas Detection and Alarm Devices in the Workplace", and GBT50493-2019 "Design Standard for Combustible and Toxic Gas Detection and Alarm Devices in the Petrochemical Industry" according to safety requirements, for verification by emergency management departments.

[0036] In this embodiment, a heterogeneous fusion multiplexing polling extraction architecture is adopted. For the measurement of the concentration of key toxic and harmful gases in a complex background gas in a limited space, four gas detectors (CO, CH4, H2S, O2) based on different principles are organically combined in series and parallel according to the analysis flow requirements to form a multi-sensor unit. The unit extracts and samples 16 independent sampling gas paths in a time-division manner, and reuses one set of four gas detectors based on different principles to simultaneously detect the real-time concentration of the sampled gas in the current gas path.

[0037] Specifically, in this embodiment, as Figure 1 As shown, the field instrument layer includes a sampling unit, a purging unit, a pumping unit, a calibration unit, and a multi-sensor heterogeneous fusion unit. The sampling unit acquires sample gas from different monitoring points; the purging unit purges the sampling pipeline; the pumping unit pumps the sampled gas from the sampling unit to the multi-sensor heterogeneous fusion unit for actual measurement; and the calibration unit calibrates the multi-sensor heterogeneous fusion unit. The extraction unit consists of two branches: an extraction pump and a pre-extraction pump. The extraction pump is connected to the sampling unit to form a sampling measurement loop, while the pre-extraction pump and the sampling unit form a prediction loop. Both the sampling measurement loop and the prediction loop are equipped with blockage alarms. In the sampling measurement loop, a filter and a condenser are connected in series between the extraction pump and the multi-sensor heterogeneous fusion unit. The filter is used to remove impurities, and the condenser is used to remove moisture from the gas. The condenser includes a gas supply pipe connected to the sensor unit and a drain pipe for discharging condensate. The measured gas and condensate are discharged into the confined space through the gas supply pipe and the drain pipe, respectively. The multi-sensor unit performs multi-type gas concentration detection. After detection, the gas is directly discharged into the confined space through the exhaust pipe.

[0038] The sampling unit includes several sampling valves and their corresponding sampling pipelines. The sampling valves are positioned at different measurement points and connected sequentially to the corresponding sampling measurement loop and prediction loop via the sampling pipelines. The purging unit includes a backflush pressure-stabilized air tank and a pulse purging valve group, which are also connected to different sampling pipelines. During real-time sampling, the sampling valve at the corresponding measurement point is opened according to control commands to complete gas detection at that point. During purging, the sampling pipelines are sequentially purged via the backflush pressure-stabilized air tank and the pulse purging valve group according to purging control commands. In this embodiment, there are n=16 sampling pipelines (sampling pipelines 1-16) and corresponding sampling valves 1-16.

[0039] More specifically, the carbon monoxide detector in this embodiment employs nondispersive infrared (NDIR) technology based on the Lambert-Beer law; CO molecules exhibit strong selective absorption of infrared light in a specific infrared band (primarily around 4.6 μm). This is because the stretching vibration frequency of the carbon-oxygen bond in the CO molecule matches the energy of infrared photons in this band, causing energy level transitions and thus absorbing infrared light. The Lambert-Beer law describes the quantitative relationship of light absorption:

[0040] in, This represents the intensity of transmitted light after passing through the gas. Indicates the incident light intensity or initial light intensity. This represents the absorption coefficient of carbon monoxide (CO) at a specific wavelength, and it is a known constant. This indicates the concentration of CO in the gas being tested; This indicates the optical path length of infrared light as it passes through the gas.

[0041] Based on non-dispersive infrared (NDIR) technology, the carbon monoxide detector in this embodiment does not use expensive gratings or prisms to disperse infrared light into a continuous spectrum (i.e., Fourier transform infrared spectroscopy, FTIR). Instead, it uses a broadband infrared light source and a detector that is particularly sensitive to the CO absorption band. By measuring the intensity change of infrared light in a specific band before and after passing through the gas, the concentration of the gas can be deduced.

[0042] In this embodiment, the carbon monoxide detector includes an infrared emitter, a measuring chamber, an infrared detector, a preamplifier, a signal conditioning circuit, and a micro signal processor. The infrared emitter emits a constant infrared light source. Carbon monoxide absorbs part of the infrared light in the measuring chamber. The infrared detector receives the infrared light signal during the absorption process and transmits it to the micro signal processor through the preamplifier and signal conditioning circuit. The micro signal processor calculates the carbon monoxide concentration based on the infrared light signal emitted by the infrared emitter and the infrared light signal received by the infrared detector.

[0043] Specifically, the key component of the infrared light emission section is the infrared light source, commonly a miniature ceramic filament or a MEMS infrared emitter. There are two critical requirements for this infrared light source. First, stability: the emitted infrared light intensity must be highly stable, as any fluctuation will directly cause measurement errors; therefore, a constant current source is typically used for driving it. Second, spectral range: it needs to cover the absorption band of carbon monoxide (4.3-4.6 μm) and a reference band not absorbed by carbon monoxide. Furthermore, to overcome low-frequency noise (such as 1 / f noise) from ambient light and the detector itself, the infrared light source is usually pulse-modulated or low-frequency modulated (e.g., a few Hz to tens of Hz) to shift the signal frequency to a less noisy band for processing.

[0044] The measuring chamber is a metal or ceramic tube with an internal gold-plated lining. Several key requirements exist for this part. First is the optical path length (L). According to the Lambert-Beer law, a longer optical path length results in higher sensitivity to low-concentration gases. To achieve long optical paths in miniaturized devices, multiple-mirror structures such as White Cell or Herriott Cell are commonly used. Second is reflectivity; the inner wall is plated with gold or other highly reflective materials to minimize light intensity loss. Finally, gas diffusion / flow is crucial; the design includes inlets and outlets to ensure the gas to be measured can enter the chamber sufficiently and rapidly.

[0045] The infrared detector, a thermopile or pyroelectric detector, is one of the most critical components. Its working principle and setup are as follows: A narrow-band optical filter is mounted in front of the detector. The center wavelength of the measurement channel filter is precisely aligned with the absorption peak of carbon monoxide (4.6 μm), allowing only infrared light in this band to pass through. The center wavelength of the reference channel filter is selected in an infrared band where carbon monoxide does not absorb (e.g., around 3.9 μm or 5.0 μm). To integrate the measurement and reference channels, the detector is typically made into a dual-channel or quad-channel system, with one filter for each channel. In terms of function, the light intensity I_measure detected by the measurement channel is affected by both carbon monoxide absorption and general factors (such as light source aging, dust contamination, and temperature-induced device performance drift); the light intensity I_ref detected by the reference channel is only affected by these general factors and is almost unaffected by the carbon monoxide concentration.

[0046] The process by which the micro signal processor processes the signals from the measurement channel and the reference channel is as follows: Demodulation: Based on the modulation frequency of the light source, the amplitudes of the AC signals from the two channels are accurately extracted using techniques such as digital lock-in amplification, and denoted as follows: and These two values ​​are proportional to the infrared light intensity of their respective channels. and .

[0047] Ratio calculation: Calculate the ratio of the measurement channel signal to the reference channel signal. :

[0048] ratio This is key to eliminating common-mode interference. Because any common factors affecting both channels (such as reduced light source intensity, window contamination, temperature drift) will be largely canceled out in the ratio calculation.

[0049] Based on the Lambert-Beer law, the concentration model is established as follows:

[0050]

[0051] in, Since it is a constant, therefore, the ratio It can be represented as:

[0052] Assuming a stable light source and a symmetrical system design, it can be considered that... ,therefore:

[0053] in , is a system constant.

[0054] Linearization and Calibration: The relationship above is exponential. In practical applications, it is usually transformed into a linear relationship through calibration.

[0055] 1) Zero-point calibration: In pure air (or nitrogen), where the CO concentration c=0, a ratio R0 is measured.

[0056] 2) Range calibration: Measure a ratio Rspan in a standard CO gas of known concentration (e.g., c=500ppm).

[0057] 3) The final concentration c can be obtained by linear interpolation of R0, Rspan, and the currently measured R, or by calculation using a fitted curve. Typically, the sensor internally stores a set of calibration curves or polynomial coefficients. The gas absorption coefficient α is affected by ambient temperature and air pressure. High-precision sensors integrate temperature and pressure sensors, and the microprocessor compensates for the calculation results based on this real-time data, ensuring measurement accuracy across the entire temperature range and at different altitudes.

[0058] In this embodiment, the carbon monoxide detector solves the problem of interference from gases such as SO2 on traditional electrochemical detectors, thereby fundamentally solving the problem of measurement distortion such as the full-scale reading of CO gas alarm at 500ppm.

[0059] The heterogeneous fusion multiplexing polling extraction method is used to measure the concentration of key toxic and harmful gases in complex background air in confined spaces. It organically combines gas sensors with different principles. The detector moves from the confined space to a safe area and uploads data to the DCS in real time. When the alarm limit is reached, the on-site audible and visual alarm is activated, and the supply and exhaust fans are activated simultaneously.

[0060] Employing a polling and sensor multiplexing mode, one set of four sensors (CO, CH4, H2S, O2) measures gas concentrations at multiple points at different elevations, covering an area of ​​405m. 2 Multiple sets of equipment can be combined to monitor gas concentration in the entire confined space of the waste pit, whether it is a collection pool or a 300m2 corridor.

[0061] In summary, one of the cores of this invention lies in achieving the leap from static to dynamic. On the one hand, dynamic distribution law verification is carried out. Based on the deployed dynamic monitoring network, for the first time, through on-site measured data, it is systematically verified that in a confined space with partial exhaust or forced supply and exhaust, the spatial distribution of gases such as CO is mainly jointly dominated by the release source and the ventilation air flow, forming a dynamic and uneven concentration field, rather than strictly following the static distribution theory based on gas specific gravity, thus deepening and improving the applicability of the GB / T50493 design standard to complex industrial scenarios. On the other hand, accurate assessment of ventilation efficiency is carried out. Based on the dynamic monitoring network, the actual ventilation efficiency is quantitatively evaluated through monitoring data, and gas accumulation is identified, providing a scientific decision-making basis for optimizing ventilation strategies and implementing data-driven safety access management.

[0062] The second core innovation is the multi-sensor heterogeneous fusion, which overcomes the problem of measurement distortion. In terms of sensor selection, the NDIR infrared CO sensor adopts the non-dispersive infrared principle. Based on the selective absorption characteristics of gas molecules, it is fundamentally immune to the interference of H2 and hydrocarbons, completely solves the problem of CO indication distortion, and extends the sensor life from 2 weeks to more than 3 years; compared with the catalytic combustion principle under the same technical conditions, the dual-wavelength infrared CH4 sensor has its life extended from 1 year to 8 years, achieving long-term stable and reliable monitoring. In terms of architecture design, the sensors with four different principles of NDIR, electrochemistry (for measuring H2S and O2), and dual-wavelength infrared (CH4) are innovatively integrated into one body, realizing synchronous, accurate, and stable monitoring of toxic and harmful gases.

[0063] The third core innovation of this invention lies in adopting the "reuse polling + extraction type" design to achieve full-domain coverage and intrinsic safety. The "extraction type" migration moves all detectors from the inside of the confined space to the external safe area as a whole. The maintenance work changes from "high-risk confined space operation" to "routine thermal control operation", fundamentally eliminating the personnel access risk; the "reuse polling" mechanism, through a set of sensor arrays, combined with multi-channel gas valve switching, time-sharing reuse, and轮流检测多达n=16个不同点位,实现了“以一套设备,监控一片区域”的革命性突破,大幅减少探测器总数,将全厂所需气体探测器数量降低至不足原设计台套数的1 / 3,并实现了全域覆盖监测。

[0064] The fourth core innovation is to build a three-level intelligent security prevention system to achieve active early warning and linkage. The on-site perception layer accurately collects data in real time by the gas detector system; the DCS control layer receives data through MODBUS RS485, conducts real-time monitoring and alarm, and quickly links the supply and exhaust fans within 3 seconds, realizing the closed-loop from "perception" to "prevention and control"; the MIS information layer uploads data to the management information system, supporting data traceability, remote monitoring and decision-making analysis across the whole plant.

[0065] It should be noted that there is an unclear expression in the translation of . The original Chinese "轮流检测多达n=16个不同点位" seems a bit inaccurate in grammar. It might be better as "轮流检测 up to n = 16 different points". The above translation is based on the original text as accurately as possible while trying to make sense of this unclear part.Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A confined space all-area gas monitoring security system based on multi-sensor heterogeneous fusion, characterized in that: It comprises a field instrumentation layer, a distributed control system (DCS) layer, and an information management system (MIS). The field instrumentation layer includes a multi-sensor heterogeneous fusion unit with multiple sampling points set up according to the actual operating conditions of the confined space area of ​​the waste incineration plant's leachate. This multi-sensor heterogeneous fusion unit connects to the DCS layer and transmits monitoring data there. The DCS layer then uses this monitoring data to issue real-time alarm control and preventative measures commands. The DCS layer further transmits the acquired monitoring data to the MIS layer, which supports plant-wide data traceability, remote monitoring, and decision analysis. Combining the spatial distribution of the release source and ventilation airflow, the real-time monitoring of multiple systems by multi-sensor heterogeneous fusion units at multiple points forms a dynamic monitoring network. The actual ventilation efficiency is quantitatively evaluated through monitoring data, gas accumulation is identified, and the supply and exhaust systems are linked to control based on the quantitative evaluation results. The field instrument layer employs a multi-sensor heterogeneous fusion unit that uses measurement point polling and sensor reuse to reduce the number of gas detectors in the confined space of the leachate. The system is equipped with multiple sampling pipelines, each corresponding to a different measurement point. These multiple sampling pipelines are connected to a multi-sensor heterogeneous fusion unit that is organically combined in series and parallel with various types of gas sensors. The multi-sensor heterogeneous fusion unit includes methane detectors, hydrogen sulfide detectors, oxygen detectors, and carbon monoxide detectors. These detectors are organically combined based on their sampling flow characteristics. Furthermore, the carbon monoxide detector uses non-dispersive infrared detection technology to detect the concentration of carbon monoxide.

2. The finite-space, all-area gas monitoring and security system based on multi-sensor heterogeneous fusion according to claim 1, characterized in that: The field instrument layer includes a sampling unit, a purging unit, a pumping unit, a calibration unit, and a multi-sensor heterogeneous fusion unit. The sampling unit acquires sample gas from different monitoring points; the purging unit purges the sampling pipeline; the pumping unit delivers the sampled gas to the multi-sensor heterogeneous fusion unit for actual measurement; and the calibration unit calibrates the multi-sensor heterogeneous fusion unit. The extraction unit consists of two branches: an extraction pump and a pre-extraction pump. The extraction pump is connected to the sampling unit to form a sampling measurement loop, while the pre-extraction pump and the sampling unit form a prediction loop. Both the sampling measurement loop and the prediction loop are equipped with blockage alarms. In the sampling measurement loop, a filter and a condenser are connected in series between the extraction pump and the multi-sensor heterogeneous fusion unit. The filter is used to remove impurities, and the condenser is used to remove moisture from the gas. The condenser includes a gas supply pipe connected to the sensor unit and a drain pipe for discharging condensate. The measured gas and condensate are discharged into the confined space through the gas supply pipe and the drain pipe, respectively. The multi-sensor unit performs multi-type gas concentration detection. After detection, the gas is directly discharged into the confined space through the exhaust pipe.

3. A confined space all-area gas monitoring security system based on multi-sensor heterogeneous fusion according to claim 2, characterized in that: The sampling unit includes several sampling valves and their corresponding sampling pipelines. The sampling valves are set at different measurement points and are connected to the corresponding sampling measurement loop and prediction loop in sequence through the sampling pipelines. The purging unit includes a backflush pressure stabilizing tank and a pulse purging valve group. The backflush pressure stabilizing tank and the pulse purging valve group are also connected to different sampling pipelines. During real-time sampling, the sampling valve at the corresponding measurement point is opened according to the control command to complete the gas detection at the corresponding measurement point. During purging, the sampling pipeline is purged sequentially according to the purging control command by using the backflush pressure stabilizing tank and pulse purging valve group.

4. A confined space all-area gas monitoring and security system based on multi-sensor heterogeneous fusion according to claim 1, characterized in that: The carbon monoxide detector includes an infrared emitter, a measuring chamber, an infrared detector, a preamplifier, a signal conditioning circuit, and a micro signal processor. The infrared emitter emits a constant infrared light source. Carbon monoxide absorbs part of the infrared light in the measuring chamber. The infrared detector receives the infrared light signal during the absorption process and transmits it to the micro signal processor through the preamplifier and signal conditioning circuit. The micro signal processor calculates the carbon monoxide concentration based on the infrared light signal emitted by the infrared emitter and the infrared light signal received by the infrared detector.

5. A confined space global gas monitoring security system based on multi-sensor heterogeneous fusion according to claim 4, characterized in that: The process by which the micro-signal processor of the carbon monoxide detector processes the signals from the measurement channel and the reference channel is as follows: Demodulation: The amplitudes of the AC signals from the two channels are extracted based on the modulation frequency of the light source, and denoted as follows: and ; They are respectively proportional to the infrared light intensity of their respective channels. and ; Ratio calculation: Calculate the ratio of the measurement channel signal to the reference channel signal. : Based on the Lambert-Beer law, the concentration model is established as follows: in, A constant ratio Represented as: Assuming a stable light source and a symmetrical system design ,therefore: in , is a system constant; The resulting exponential relationship is transformed into a linear relationship through calibration. 1) Zero-point calibration: The ratio R0 measured in pure air when the carbon monoxide concentration is 0; 2) Range calibration: Measure a ratio Rspan in a standard carbon monoxide gas of known concentration; 3) The final concentration c is obtained by linear interpolation of R0, Rspan and the currently measured R or by calculation through a fitted curve.

6. A confined space global gas monitoring security system based on multi-sensor heterogeneous fusion according to claim 1, characterized in that: The DCS layer is the central control unit of the gas monitoring system, responsible for data acquisition, real-time processing, alarm linkage and communication transmission. It receives real-time concentration data from the field instrument layer through the MODBUS RS485 protocol and verifies and filters the raw data. Set the concentration alarm threshold for each gas. When the real-time concentration exceeds the limit, immediately trigger the audible and visual alarm and automatically start the supply and exhaust fans for ventilation and replacement.

7. A confined space global gas monitoring security system based on multi-sensor heterogeneous fusion according to claim 1, characterized in that: The MIS layer is the remote management platform for the gas monitoring system, providing data visualization, data traceability, remote monitoring, and decision analysis functions. Data visualization includes real-time monitoring interface display, concentration change trend analysis, spatial distribution map display, and remote monitoring. Data traceability includes automatically generating gas concentration statistical reports by date and providing compliance reports. Decision analysis is based on the data visualization content and gas concentration statistics.

Images