A method for dynamic calibration and risk prediction operation of a fire monitoring and early warning device in confined spaces

Abstract

This invention discloses a dynamic calibration and risk prediction operation method for a confined space fire monitoring and early warning device, relating to the fields of safety monitoring and industrial Internet of Things technology. The method includes: deploying multi-parameter monitoring terminals in the confined space and completing self-testing and time synchronization; using heated sampling and dust removal-condensation purification to ensure the sample gas temperature is 20-40°C above the dew point; establishing a calibration coefficient matrix based on zero gas / standard gas and reference analysis data to correct for temperature, humidity, pressure, and cross-interference online; and integrating CO and H2O data. ₂ CH ₄ O ₂ CO ₂ This method uses multi-source data such as temperature and smoke to calculate the combustion precursor index and flammability margin, and predict the time to exceed limits. It triggers tiered early warnings based on thresholds and coordinates with ventilation, inerting, and shutdown for ventilation. This method is applicable to confined spaces such as underground utility tunnels, tunnels, storage tanks, silos, and containerized biomass gasification / carbonization units, achieving low false alarm rates and high reliability for fire early warning.

Description

Technical Field

[0001] This invention relates to the fields of fire monitoring and early warning, confined space safety, and industrial Internet of Things, specifically providing a dynamic calibration and risk prediction operation method for a confined space fire monitoring and early warning device. Background Technology

[0002] Confined spaces are typically characterized by limited access, poor natural ventilation, difficulty in dispersing heat and smoke, and easy accumulation of dust and corrosive gases. They are commonly found in underground utility tunnels, storage tanks, silos, equipment rooms, and inside containerized energy equipment. In such scenarios, early smoldering or localized overheating is often accompanied by a slow rise in CO, changes in temperature gradients, and fluctuations in oxygen content. At the same time, the accumulation of combustible gases or volatile organic compounds in confined spaces can easily lead to a combustion-explosion coupling risk.

[0003] Existing fire alarm methods are mostly based on fixed threshold triggering, which is difficult to adapt to changes in temperature and humidity in confined spaces, dust pollution, sensor cross-interference, and dynamic changes in ventilation / inertia conditions. In addition, distributed energy equipment such as biomass gasification / carbonization produces combustible / toxic gases such as CO, H2, and CH4 during operation, and is often arranged in containers with limited internal space. If there is a lack of predictable and interconnected monitoring and early warning methods, problems such as frequent false alarms, missed alarms, or delayed response are likely to occur. Summary of the Invention

[0004] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a dynamic calibration and risk prediction operation method for a confined space fire monitoring and early warning device. Through a closed-loop process of "heat tracing sampling - purification and blockage - online calibration - multi-source fusion - risk index - over-limit time prediction - graded linkage response", early identification and early warning of confined space fires can be achieved.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a dynamic calibration and risk prediction operation method for a confined space fire monitoring and early warning device, comprising: deploying monitoring terminals and edge gateways and completing self-testing and time synchronization; controlling sample gas condensation and reducing dust pollution through heat tracing sampling and purification units; establishing a calibration coefficient matrix based on zero gas / standard gas and reference analysis data and correcting drift and cross-interference online; fusing multi-source data to calculate the combustion precursor index and flammability margin and predict the time of exceeding the limit; triggering graded early warning based on the prediction results and linking ventilation, inerting, shutdown and venting.

[0006] In a preferred embodiment, the temperature of the heated sampling pipeline is maintained at 20–40°C above the dew point, and a backflushable filter element and condensate separation structure are configured to reduce condensation blockage and dust pollution.

[0007] In a preferred embodiment, the calibration coefficient matrix is ​​obtained by periodic injection of zero gas and multi-point standard gas, and sensor drift is constrained and corrected using reference data from micro gas chromatography or infrared spectroscopy.

[0008] In a preferred embodiment, the flammability margin is calculated using the lower explosion limit corrected for O2 and CO2 / N2, and the time to exceed the limit is predicted by an LSTM or GRU time series model, thereby providing advance notice for on-site handling.

[0009] The technical solution provided by this invention has the following beneficial effects: (1) By using heat-traced sampling and purification to prevent blockage, the condensation, blockage and drift of dust in confined spaces under high humidity and dust conditions can be reduced; (2) By online calibration of zero gas / standard gas and reference analysis constraints, false alarms / missed alarms caused by cross interference and long-term drift are reduced; (3) By integrating the combustion precursor index and flammability margin for evaluation, and outputting the predicted value of the time to exceed the limit, the system can achieve "early warning" rather than just "status alarm". (4) Improve the timeliness of response and system safety by using graded early warning and ventilation-inerting-shutdown-release linkage; (5) It can be used as a safety monitoring module for containerized biomass gasification / carbonization devices, providing support for the stable operation and maintenance traceability of biomass projects. Attached Figure Description

[0010] Figure 1 This is a flowchart illustrating the dynamic calibration and risk prediction operation method of a confined space fire monitoring and early warning device according to the present invention. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0012] Example 1 like Figure 1 As shown, the dynamic calibration and risk prediction operation method for a confined space fire monitoring and early warning device provided in this embodiment includes the following steps: S1: Monitoring terminal deployment, self-testing, and time synchronization.

[0013] Monitoring terminals are deployed at key locations within confined spaces. These key locations include low-lying areas where gas may accumulate, near heat sources, in ventilation dead zones, and areas where personnel are working. Upon startup, the monitoring terminal completes sensor zero-point checks, power and communication self-tests, and synchronizes its time with the edge gateway to establish a mapping between terminal IDs and spatial identifiers.

[0014] S2: Heat-traced sampling and purification to prevent blockage.

[0015] The monitoring terminal extracts sample gas through a high-temperature resistant sampling probe. The heating tape and temperature sensor control the temperature of the sampling pipeline to be 20-40°C above the dew point of the sample gas. The sample gas passes through a primary filter and a backflushing high-efficiency filter element in sequence, and then enters the condensate separation component. When the filter element pressure difference ΔP_filter reaches the threshold, a reverse pulse cleaning is triggered, and the maintenance event is recorded.

[0016] S3: Online calibration and cross-interference correction.

[0017] Zero gas and multi-point standard gas are periodically injected into the sampling manifold, and a calibration coefficient matrix is ​​established by combining reference analysis data from micro gas chromatography or infrared spectroscopy. The sensor zero point, range, and cross-interference coefficients are updated using weighted least squares or recursive least squares, and a temperature, humidity, and pressure compensation model is superimposed to obtain calibrated continuous monitoring data.

[0018] S4: Multi-source fusion assessment and over-limit time prediction.

[0019] By integrating calibrated data on CO, H2, CH4, O2, CO2, temperature, humidity, and smoke / dust, the pre-combustion index (TI) and flammability margin (M) are calculated. M is calculated using the lower explosion limit (LEL_corr) corrected for O2 and CO2 / N2. The trends of TI or M over the next 5–60 minutes are predicted using LSTM, GRU, or grey prediction models, and the time to exceed the limit is output.

[0020] S5: Tiered early warning and coordinated response.

[0021] When TI, M, or the over-limit time meets preset conditions, a Level I / II / III warning is triggered. Under a Level II warning, ventilation / exhaust is activated and the ignition source is restricted. Under a Level III warning, inerting gas (CO2 or N2) injection, combustible gas valve closure, shutdown, and switching to a flare or safety burner are executed, and the event data packet is uploaded to the upper-level system for traceability. When applied to containerized biomass gasification / carbonization units, the Level III warning command can directly act on the gas supply and atmosphere control unit to achieve rapid inerting and safe release.

[0022] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention; any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic calibration and risk prediction operation method for a confined space fire monitoring and early warning device, characterized in that, include: At least one monitoring terminal and one edge gateway are deployed in the confined space to complete terminal self-testing, time synchronization, and spatial identification. The sample gas is dusted and condensed through a heat-traced sampling and purification unit to keep the temperature of the sampling pipeline 20-40°C above the dew point of the sample gas. A calibration coefficient matrix is ​​established based on zero gas / standard gas and reference analysis data through a calibration and soft measurement unit, and online correction is performed for temperature, humidity, and pressure drift and cross-interference of the terminal. Multi-source data including at least CO, H2, CH4, O2, CO2, temperature, humidity, and smoke / dust are collected and fused to obtain the combustion precursor index and flammability margin, and the predicted value of the time to exceed the limit is output. The system triggers graded early warnings based on the combustion precursor index, flammability margin, and predicted over-limit time, and coordinates with the implementation of ventilation adjustment, inerting gas injection, process shutdown, and safety venting.

2. The operating method according to claim 1, characterized in that, The heat tracing sampling and purification unit includes: a high-temperature resistant sampling probe, a two-stage filtration assembly and a condensate separation assembly; the two-stage filtration assembly includes at least a primary filter and a backflushing high-efficiency filter element, and a reverse pulse cleaning is triggered when the filter element pressure difference ΔP_filter ≥ a preset threshold.

3. The operating method according to claim 1, characterized in that, The calibration coefficient matrix is ​​obtained by periodically injecting a mixture of zero gas and a standard gas with a concentration gradient of no less than 3 points into the sampling manifold; Using reference analysis data as the baseline and continuous measurements from terminal sensors as the observations, weighted least squares or recursive least squares are used to update the zero point, range, and cross-interference coefficient.

4. The operating method according to claim 3, characterized in that, The reference analysis data is provided by at least one of a micro gas chromatograph, infrared spectroscopy, or portable analyzer, and the output cycle of the reference analysis data is 5 to 30 minutes, which is used to constrain the drift correction of the terminal sensor.

5. The operating method according to claim 1, characterized in that, The combustion precursor index TI is calculated by combining at least the following parameters: CO concentration rise rate dCO / dt, temperature rise rate dT / dt, O2 fall rate dO2 / dt, soot / smoke concentration and its rate of change, and TI is smoothed by sliding window and outlier removal is performed.

6. The operating method according to claim 1, characterized in that, The flammability margin is calculated by the following formula: M = 1 -(C_fuel / LEL_corr), where C_fuel is the equivalent concentration of flammable gas, and LEL_corr is the lower explosion limit after correction for oxygen and inert gas concentrations; LEL_corr is corrected online based on the volume fractions of O2, CO2 and / or N2 to reflect changes in ventilation and inerting conditions in confined spaces.

7. The operating method according to claim 1, characterized in that, The predicted time of exceeding the limit is obtained through a time series prediction model, which is at least one of LSTM, GRU or first-order grey prediction model. The input features include TI, M and pressure / wind speed information of the confined space, and the output is the time of exceeding the limit of TI or M within the future t_pred=5 to 60 min.

8. The operating method according to claim 1, characterized in that, The graded early warning system includes at least three levels: Level I warning: When TI ≥ threshold TI1 and the time exceeding the limit > t1, it prompts for inspection and increases the sampling frequency; Level II warning: When TI ≥ threshold TI2 or M ≤ threshold M2, ventilation / exhaust will be activated and ignition source will be restricted. Level III warning: When TI ≥ threshold TI3 ​​or M ≤ threshold M3 or the time exceeding the limit is ≤ t3, inert gas injection, combustible gas valve closure, shutdown and switching to flare or safety burner will be activated.

9. The operating method according to claim 8, characterized in that, The inert gas is CO2 or N2. Before inertization injection, the pressure of the confined space is determined, and inertization is performed under a slight negative pressure of -200 to -800 Pa or an equivalent safe pressure window to suppress the escape of combustible gas and reduce the risk of backfire.

10. The operating method according to claim 1, characterized in that, The confined space refers to the gas purification room, silo, carbon silo, or gas pipeline of the containerized biomass gasification / pyrolysis / carbonization unit. When a Level III warning is triggered, the edge gateway sends a shutdown and inerting command to the gas supply and atmosphere control unit of the biomass unit and generates a traceable event data packet for operation and maintenance and safety review.

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