A method for calculating region boundaries based on combustible gas flow gradient

Abstract

This invention discloses a method for calculating regional boundaries based on combustible gas flow gradients, relating to the field of gas flow technology. It addresses the problems of lagging regional division and increased errors in diffusion boundary judgment. The method obtains the division information between the monitoring flow zone and the safe flow zone by calling a flow division library, collects the combustible gas concentration in the monitoring flow zone, and calculates the concentration duration to determine whether a boundary analysis mechanism is triggered. In the boundary analysis mechanism, the instantaneous flow rate at the boundary is collected to calculate the flow gradient, and the flow fluctuation distance is analyzed in conjunction with the concentration change rate. Based on the flow fluctuation distance, the safe flow zone is divided to obtain the flow fluctuation band, and the flow velocity is evaluated and classified as laminar or turbulent. When the flow state is turbulent, the pressure change trend is analyzed, and a flow prediction coefficient is generated in conjunction with the coverage ratio. The division period is dynamically adjusted to improve the accuracy and timeliness of gas flow monitoring, achieving precise regional division and efficient flow monitoring.

Description

Technical Field

[0001] This invention relates to the field of gas flow technology, and more specifically, to a method for calculating region boundaries based on combustible gas flow gradient. Background Technology

[0002] In industrial chemical plants, oil and gas transmission and distribution systems, storage and transportation facilities, and urban gas facilities, the monitoring and early warning of combustible gas leaks is a key link in ensuring production safety and reducing accident losses. Traditional combustible gas monitoring methods are mainly based on gas concentration threshold judgment. By setting up several concentration monitoring points in the target area, it is determined whether the gas concentration exceeds the safety limit, thereby triggering an alarm or executing equipment linkage.

[0003] The existing technology has the following shortcomings:

[0004] Currently, existing technologies rely solely on concentration thresholds for area delineation and leak detection, failing to consider the instantaneous flow rate changes and gradient characteristics of combustible gases in space. This is particularly true in the initial leak stages or unstable diffusion phases, where nonlinear fluctuations in gas flow and changes in diffusion distance are prevalent. The lack of a boundary dynamic calculation mechanism based on comprehensive modeling of flow gradient, concentration change rate, and flow state leads to delayed area delineation, increased errors in diffusion boundary judgment, and reduced monitoring accuracy and early warning timeliness. Therefore, a method for calculating area boundaries based on combustible gas flow gradients is proposed.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a method for calculating regional boundaries based on combustible gas flow gradients. This method addresses the problems mentioned in the background art by employing flow gradient calculation, concentration change rate analysis, flow fluctuation distance modeling, and a joint evaluation mechanism of flow state and pressure trends.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for calculating the region boundary based on the combustible gas flow gradient, comprising the following steps:

[0008] Step S1: Call the division information of the monitoring flow area and the safe flow area through the flow division library, collect the combustible gas concentration in the monitoring flow area according to the division information and count the concentration duration, and determine whether the boundary analysis mechanism is triggered based on the concentration duration.

[0009] Step S2: In the boundary analysis mechanism, the instantaneous flow rate of combustible gas at the boundary between the monitoring flow zone and the safe flow zone is collected to calculate the flow gradient. The observation duration is set to collect the concentration of combustible gas and calculate the concentration change rate. The flow gradient is combined to analyze the flow fluctuation distance.

[0010] Step S3: Divide the safe flow zone based on the flow fluctuation distance to obtain the flow fluctuation band, detect the coverage ratio of the flow fluctuation band and the flow velocity of the combustible gas, and use the flow velocity to evaluate the flow state and classify it as laminar or turbulent flow.

[0011] Step S4: When the flow state is turbulent, detect the instantaneous pressure of combustible gas in the flow fluctuation zone and evaluate the pressure change trend. Combine the coverage ratio to generate the flow prediction coefficient, call the historical division time of the monitoring flow zone and the safe flow zone to calculate the division period, and use the flow prediction coefficient to adjust the division period.

[0012] In a preferred embodiment, in step S1, the on-site space in the chemical production operation area is divided into zones according to the flow characteristics of combustible gas. The monitoring flow zone is used to focus on monitoring the changes in the flow rate and concentration of combustible gas, and the safe flow zone serves as an auxiliary area outside the monitoring flow zone.

[0013] The traffic partitioning library retrieves the partitioning information of the monitoring traffic area and the safe traffic area, including the spatial range of the monitoring traffic area, the spatial range of the safe traffic area, and the boundary position formed when the two were partitioned in the last time.

[0014] Gas sensors are deployed according to the spatial range of the monitoring flow area. The instantaneous concentration value of combustible gas at the sampling time is obtained from each gas sensor in the monitoring flow area according to the preset sampling frequency, which is used as the combustible gas concentration in the monitoring flow area.

[0015] In a preferred embodiment, in step S1, based on the collection and recording of combustible gas concentration over time, the duration during which the combustible gas concentration is continuously maintained above the monitoring concentration threshold within the time window from the start of collection to the current time is defined as the concentration duration.

[0016] When the duration of concentration is greater than or equal to the preset boundary analysis trigger threshold, the boundary analysis mechanism is triggered.

[0017] If the duration of concentration is less than the preset boundary analysis trigger threshold, the existing region division will be maintained and the boundary analysis mechanism will not be triggered.

[0018] In a preferred embodiment, in step S2, in the boundary analysis mechanism, the instantaneous flow rate of combustible gas at the boundary between the monitored flow area and the safe flow area is collected by flow sensors deployed at monitoring points at the boundary locations;

[0019] The flow gradient is obtained by spatial difference calculation of the instantaneous flow at different monitoring points at the boundary;

[0020] The concentration of combustible gas at the boundary is continuously collected during the set observation period. The instantaneous concentration value of combustible gas at the boundary is collected by a gas sensor within the observation period, and the concentration change rate is calculated by time difference.

[0021] In a preferred embodiment, in step S2, a weighted summation method is used to linearly combine the flow gradient and the concentration change rate to calculate the boundary fluctuation amplitude;

[0022] The average boundary fluctuation of all monitoring points along the boundary is obtained by taking the time average of the boundary fluctuation amplitudes of all monitoring points within the observation period.

[0023] The average of the boundary fluctuations of all monitoring points is used as the fluctuation distance ratio coefficient.

[0024] The flow fluctuation distance is obtained by multiplying the fluctuation distance ratio coefficient by the area width of the safe flow zone. The area width of the safe flow zone is defined as the average distance from the boundary between the monitoring flow zone and the safe flow zone along the normal direction to the outer boundary of the safe flow zone.

[0025] In a preferred embodiment, in step S3, the original boundary of the safe flow zone is used as a reference, and the spatial area covered by the flow fluctuation distance extended from the original boundary into the safe flow zone is used as the flow fluctuation zone.

[0026] The area of ​​the flow fluctuation zone relative to the safe flow zone is used as the coverage ratio of the flow fluctuation zone;

[0027] The sampling period is preset and divided into multiple sampling times. The flow velocity of combustible gas at the sampling time is collected by a flow velocity sensor deployed inside the flow fluctuation zone.

[0028] In a preferred embodiment, in step S3, the average value of each flow velocity is taken to obtain the flow velocity mean, and the standard deviation of each flow velocity is calculated as the flow fluctuation factor.

[0029] The flow velocities are sorted in chronological order. The absolute difference between the flow velocities at adjacent sampling times is taken to obtain the magnitude of the change. The average magnitude of the change is obtained by averaging the magnitudes of the changes.

[0030] The ratio of the flow fluctuation factor to the mean flow velocity is taken as the velocity dispersion ratio, and the ratio of the average variation amplitude to the mean flow velocity is taken as the velocity fluctuation ratio.

[0031] The reciprocal of the sum of the velocity dispersion ratio and the velocity fluctuation ratio is used as the flow stability index;

[0032] If the flow stability index is greater than the preset flow stability threshold, the flow state is determined to be laminar flow.

[0033] Conversely, the flow state is determined to be turbulent.

[0034] In a preferred embodiment, in step S4, when the flow state is turbulent, a statistical period is preset and divided into multiple statistical moments, and the instantaneous pressure of the combustible gas at the statistical moment is detected by a pressure sensor.

[0035] The instantaneous pressure at each statistical moment is sorted in chronological order, and the pressure change rate is obtained by subtracting the instantaneous pressure at adjacent statistical moments and dividing by the time interval between adjacent statistical moments.

[0036] The pressure change trend is obtained by averaging the various pressure change rates.

[0037] In a preferred embodiment, in step S4, the pressure change trend and the coverage ratio are standardized to obtain the pressure change coefficient and the coverage ratio coefficient, respectively.

[0038] The flow prediction coefficient is calculated using the pressure variation coefficient and the coverage ratio coefficient.

[0039] The historical data database retrieves the historical division times of the monitoring flow area and the safe flow area. The historical division times are the time records corresponding to the re-division of the boundary positions of the monitoring flow area and the safe flow area.

[0040] After sorting the historical division moments in chronological order, the difference between adjacent historical division moments is used to obtain the historical division interval.

[0041] In a preferred embodiment, in step S4, the relationship between each historical division interval is linearly fitted using the least squares method. The independent variable of the linear fitting is the sequence number corresponding to the historical division interval, and the dependent variable is the historical division interval. After linear fitting, the periodic change slope and intercept term are obtained.

[0042] Period division based on the slope of periodic change: ,in, The slope of the periodic change. For the intercept term, This is the sequence number of the most recent historical interval. To divide the period;

[0043] The division period is adjusted using the flow prediction coefficient.

[0044] The technical effects and advantages of this invention are as follows:

[0045] This invention obtains the division information of the monitoring flow zone and the safe flow zone by calling the flow zone division library, collects the concentration of combustible gas in the monitoring flow zone and counts the duration of the concentration to determine whether the boundary analysis mechanism is triggered; in the boundary analysis mechanism, the instantaneous flow at the boundary is collected to calculate the flow gradient, and the flow fluctuation distance is analyzed in combination with the concentration change rate; based on the flow fluctuation distance, the safe flow zone is divided to obtain the flow fluctuation band, and the flow velocity is evaluated and classified as laminar or turbulent; when the flow state is turbulent, the pressure change trend is analyzed and the flow prediction coefficient is generated in combination with the coverage ratio, and the division period is dynamically adjusted to improve the accuracy and timeliness of gas flow monitoring, thereby achieving accurate area division and efficient flow monitoring. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating the implementation of the region boundary calculation method based on combustible gas flow gradient of the present invention.

[0047] Figure 2 This is a schematic diagram illustrating the steps of the region boundary calculation method based on the combustible gas flow gradient of the present invention. Detailed Implementation

[0048] 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 only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] This invention obtains the division information of the monitoring flow zone and the safe flow zone by calling the flow division library, collects the concentration of combustible gas in the monitoring flow zone and counts the duration of the concentration to determine whether the boundary analysis mechanism is triggered; in the boundary analysis mechanism, the instantaneous flow at the boundary is collected to calculate the flow gradient, and the flow fluctuation distance is analyzed in combination with the concentration change rate; based on the flow fluctuation distance, the safe flow zone is divided to obtain the flow fluctuation band, and the flow velocity is evaluated and classified as laminar or turbulent; when the flow state is turbulent, the pressure change trend is analyzed and the flow prediction coefficient is generated in combination with the coverage ratio, and the division period is dynamically adjusted to improve the accuracy and timeliness of gas flow monitoring.

[0050] Example 1, such as Figures 1 to 2 As shown, the method for calculating the region boundary based on the combustible gas flow gradient includes the following steps:

[0051] Step S1: Call the division information of the monitoring flow area and the safe flow area through the flow division library, collect the combustible gas concentration in the monitoring flow area according to the division information and count the concentration duration, and determine whether the boundary analysis mechanism is triggered based on the concentration duration.

[0052] Step S2: In the boundary analysis mechanism, the instantaneous flow rate of combustible gas at the boundary between the monitoring flow zone and the safe flow zone is collected to calculate the flow gradient. The observation duration is set to collect the concentration of combustible gas and calculate the concentration change rate. The flow gradient is combined to analyze the flow fluctuation distance.

[0053] Step S3: Divide the safe flow zone based on the flow fluctuation distance to obtain the flow fluctuation band, detect the coverage ratio of the flow fluctuation band and the flow velocity of the combustible gas, and use the flow velocity to evaluate the flow state and classify it as laminar or turbulent flow.

[0054] Step S4: When the flow state is turbulent, detect the instantaneous pressure of combustible gas in the flow fluctuation zone and evaluate the pressure change trend. Combine the coverage ratio to generate the flow prediction coefficient, call the historical division time of the monitoring flow zone and the safe flow zone to calculate the division period, and use the flow prediction coefficient to adjust the division period.

[0055] The specific implementation is as follows:

[0056] In step S1, within the chemical production operation area, the site space is divided into zones based on the flow characteristics of combustible gases. The monitoring flow zone focuses on monitoring changes in the flow rate and concentration of combustible gases, and its data changes are highly relevant for gas analysis. The safe flow zone, serving as an auxiliary area surrounding the monitoring flow zone, has a relatively stable flow state and reflects the overall gas flow structure. Since the flow characteristics at the boundary between the two zones are easily affected by fluctuations, to improve the accuracy of the zoning calculation, flow fluctuation zones at the boundaries of the two zones are further identified and marked. The flow state in the flow fluctuation zone is complex and prone to monitoring deviations. By dynamically calculating the flow fluctuation zone and adjusting the zone division cycle in a timely manner, the accuracy and timeliness of gas flow monitoring are improved, resulting in zoning results that better reflect the actual flow conditions.

[0057] The flow classification database retrieves the division information of the monitoring flow area and the safe flow area. This database is a pre-built database that stores area division information, including the spatial extent of the monitoring flow area, the spatial extent of the safe flow area, and the boundary positions formed during the previous division. Specifically, the flow classification database completes the initial division of the monitoring flow area and the safe flow area based on the initial stable operation period's baseline monitoring data. By retrieving the division information of the monitoring flow area and the safe flow area, the current area structure is obtained, allowing for the collection of combustible gas concentrations within a specific spatial range.

[0058] The information collection and monitoring of combustible gas concentration in the flow area is divided. Combustible gas concentration is the content of combustible gas per unit volume, reflecting the current state of combustible gas accumulation within the flow area. When performing combustible gas monitoring, gas sensors are deployed according to the spatial range of the flow area. According to the preset sampling frequency, the instantaneous concentration value of combustible gas at the sampling time is obtained from each gas sensor in the flow area as the combustible gas concentration of the flow area. The combustible gas concentration at each sampling time is recorded.

[0059] It should be noted that the gas sensor is a measuring device that is installed in the monitoring flow area to detect the concentration of combustible gas in real time. Its working principle is to quantitatively detect the gas composition around the sampling point and output the instantaneous content value of combustible gas per unit volume.

[0060] Statistical analysis was conducted on the duration of concentration in the monitored flow area. Based on the aforementioned collection records of combustible gas concentration over time, the duration during which the combustible gas concentration remained continuously above the monitoring concentration threshold within the time window from the start of collection to the current time was defined as the concentration duration. This duration characterizes the degree of continuous accumulation of combustible gas in the monitored flow area. A higher value indicates a stronger degree of accumulation and a more stable trend of change in the combustible gas in the monitored flow area, which means that there is a greater possibility of changes in the gas flow structure, thus affecting the boundary position between the monitored flow area and the safe flow area. A lower value indicates that the combustible gas concentration fluctuates more, does not have obvious accumulation characteristics, and has low regional boundary variability.

[0061] It should be noted that the monitoring concentration threshold is set based on historical operating data of the monitoring flow area. The time series of combustible gas concentration is collected and the mean and standard deviation of the concentration data are statistically analyzed. Combined with the maximum allowable fluctuation range of combustible gas concentration under typical operating conditions, the result of adding the mean and standard deviation is used as the monitoring concentration threshold.

[0062] Compare the duration of concentration with the preset boundary analysis trigger threshold:

[0063] When the concentration duration is greater than or equal to the preset boundary analysis trigger threshold, it indicates that the combustible gas in the monitored flow area is in a state that may affect the stability of the area boundary. At this time, the boundary analysis mechanism is triggered to conduct further analysis at the boundary between the monitored flow area and the safe flow area.

[0064] If the duration of concentration is less than the preset boundary analysis trigger threshold, the existing region division will be maintained and the boundary analysis mechanism will not be triggered.

[0065] It should be noted that the boundary analysis trigger threshold is set using a quantitative analysis method based on historical concentration duration data. Specifically, the concentration duration sequence of the monitored flow area under different operating conditions is collected, and its mean and standard deviation are calculated. The result of adding the mean and standard deviation is used as the boundary analysis trigger threshold.

[0066] Through the above steps, precise control of the boundary analysis mechanism triggering based on the concentration changes in the monitored flow area is achieved, ensuring that subsequent flow gradient analysis and regional boundary adjustments are based on effective and necessary preconditions.

[0067] In step S2, within the boundary analysis mechanism, the instantaneous flow rate of combustible gas is collected at the boundary between the monitored flow area and the safe flow area. The instantaneous flow rate refers to the mass flow rate of combustible gas passing through the monitoring point per unit time at the boundary location. Its value originates from the flow sensors deployed at the monitoring points at the boundary location. By performing spatial difference calculations on the instantaneous flow rates at different monitoring points at the boundary, the flow gradient is obtained, which characterizes the degree of change in the spatial flow of combustible gas at the boundary. The calculation formula is expressed as follows:

[0068] ;

[0069] in, The flow gradient along the spatial direction at the boundary. This is the difference symbol, which cannot be split, and will not be elaborated upon here; Boundary position The instantaneous flow rate value; The distance between monitoring points.

[0070] The flow gradient reflects the local changes in gas flow at the boundary, providing a quantitative basis for analyzing flow fluctuation characteristics.

[0071] It should be noted that the flow sensor is a measuring device installed at the boundary between the monitored flow area and the safe flow area. It is used to acquire the instantaneous flow data of combustible gas in real time. By detecting the flow characteristics of the gas in the flow sensor measurement unit, such as pressure difference, velocity or volume change, the flow signal is converted into a quantifiable mass flow rate or volumetric flow rate output.

[0072] A predetermined observation period is set to continuously collect data on the concentration of combustible gas at the boundary. This period is a pre-determined time window to ensure that short-term trends in gas concentration can be fully captured within this timeframe. During the observation period, the instantaneous concentration of combustible gas at the boundary is collected using a gas sensor, and the concentration change rate is calculated using time difference. The concentration change rate reflects the speed and trend of gas concentration change over time, and the calculation formula is as follows:

[0073] ;

[0074] in, The rate of change of the concentration of combustible gas at the boundary. To collect data at the time of data collection The instantaneous concentration value, The sampling time interval.

[0075] The concentration change rate characterizes the rate of gas accumulation or dilution at the boundary, providing basic data for subsequent flow fluctuation distance analysis.

[0076] The boundary fluctuation amplitude is calculated by linearly combining the flow gradient and the concentration change rate, using the following formula:

[0077] ;

[0078] in, Boundary position At the time of collection The range of boundary fluctuations, and These are preset weighting coefficients that reflect the proportion of contribution of flow rate changes and concentration fluctuations to the fluctuation distance.

[0079] It should be noted that the weighting coefficients were set using a quantitative method based on historical monitoring data and the analysis objectives. Specifically, instantaneous flow gradients and concentration change rates at the boundary under different operating conditions were collected. By comparing the flow fluctuation distance with the historical actual fluctuation range, the contribution of each variable to the boundary fluctuation amplitude was assessed. Subsequently, a multiple linear regression algorithm was used to fit and determine the proportions of the flow gradient and concentration change rate in the combined calculation, which were then used as weighting coefficients, where α+β=1.

[0080] Subsequently, the average boundary fluctuation amplitude of all monitoring points along the boundary within the observation period was taken over time to obtain the mean boundary fluctuation of all monitoring points;

[0081] The average of the boundary fluctuations of all monitoring points is used as the fluctuation distance ratio coefficient.

[0082] The flow fluctuation distance is obtained by multiplying the fluctuation distance ratio coefficient by the area width of the safe flow zone. The area width of the safe flow zone is defined as the average distance from the boundary between the monitoring flow zone and the safe flow zone along the normal direction to the outer boundary of the safe flow zone.

[0083] The above process enables quantitative analysis of gas flow characteristics at the boundary between the monitored flow area and the safe flow area, providing data support for further boundary optimization and area division.

[0084] In step S3, taking the original boundary of the safe flow zone as a reference, a strip-shaped area is constructed as the flow fluctuation zone by extending the flow fluctuation distance from the original boundary into the safe flow zone.

[0085] By spatially mapping the distance of flow fluctuations, the part of the safe flow zone affected by instantaneous flow disturbances is delineated from the safe flow zone to obtain the flow fluctuation band, which is then treated as a separate state object in subsequent analysis.

[0086] By comparing the geometric regions of the flow fluctuation zone and the safe flow zone, the area ratio of the flow fluctuation zone to the safe flow zone is taken as the coverage ratio of the flow fluctuation zone, which reflects the spatial proportion of the safe flow zone affected by instantaneous flow disturbances.

[0087] The sampling period is preset and divided into multiple sampling times. The flow velocity of combustible gas at the sampling time is collected by a flow velocity sensor deployed inside the flow fluctuation zone.

[0088] The higher the flow velocity, the higher the kinetic energy of the combustible gas in the flow fluctuation zone, which makes it prone to velocity fluctuations, vortex shedding, or turbulent diffusion. The influence range of the flow fluctuation zone on the safe flow zone may be further expanded. The lower the flow velocity, the more stable the combustible gas movement and the lower the kinetic energy. The influence of the flow fluctuation zone on the safe flow zone is weaker, and the overall flow is closer to a stable laminar flow state.

[0089] The average value of each flow velocity is obtained by taking the average value of each flow velocity, and the standard deviation of each flow velocity is calculated as the flow fluctuation factor, which reflects the degree of dispersion of each flow velocity.

[0090] The flow velocities are sorted according to time sequence. The absolute value of the difference between the flow velocities at adjacent sampling times is taken to obtain the change range. The average change range is obtained by averaging the change ranges, which reflects the degree of time fluctuation of the flow velocity.

[0091] The ratio of the flow fluctuation factor to the mean flow velocity is taken as the velocity dispersion ratio, the ratio of the average variation amplitude to the mean flow velocity is taken as the velocity fluctuation ratio, and the reciprocal of the sum of the velocity dispersion ratio and the velocity fluctuation ratio is taken as the flow stability index.

[0092] The larger the flow stability index, the weaker the fluctuation of the flow velocity and the smoother the flow of combustible gas; the smaller the flow stability index, the more obvious the fluctuation of the flow velocity.

[0093] The flow stability index is compared with a preset flow stability threshold to classify the flow state within the flow fluctuation zone:

[0094] If the flow stability index is greater than the preset flow stability threshold, the flow state is determined to be laminar flow.

[0095] Conversely, the flow state is determined to be turbulent.

[0096] Among them, laminar flow refers to the regular streamline distribution of combustible gas in the flow channel and the gradual change in velocity, reflecting the stable movement of combustible gas in the flow fluctuation zone and the rapid decay of disturbances; turbulent flow refers to the obvious random fluctuation of flow velocity, reflecting the characteristics of unstable energy transfer and turbulent diffusion in the flow fluctuation zone.

[0097] It should be noted that the preset sampling period can be set according to the monitoring accuracy requirements or process response speed; the flow velocity sensor is a fluid velocity measurement device used to detect the instantaneous flow velocity of combustible gas at the sampling time; the preset flow stability threshold can be set according to the historical velocity data distribution or safety boundary.

[0098] By identifying flow fluctuation zones and classifying flow states into laminar and turbulent types, the system can accurately identify disturbance structures within the safe flow zone and capture turbulent characteristics in a timely manner when the flow velocity of combustible gases fluctuates randomly. This makes the range of flow fluctuation zones more closely match actual fluid behavior, thereby significantly improving the spatial resolution and time response accuracy of combustible gas flow measurement.

[0099] In step S4, when the flow state is turbulent, a statistical period is preset and divided into multiple statistical moments. The instantaneous pressure of the combustible gas at each statistical moment is detected by a pressure sensor installed inside the flow fluctuation zone.

[0100] The higher the instantaneous pressure, the greater the flow resistance of the combustible gas, and the more obvious the tendency of disturbance to propagate outward; the lower the instantaneous pressure, the smoother the flow of the combustible gas, the faster the turbulence decays, and the weaker the impact on the safe flow range.

[0101] The instantaneous pressure at each statistical moment is sorted in chronological order, and the pressure change rate is obtained by subtracting the instantaneous pressure at adjacent statistical moments and dividing by the time interval between adjacent statistical moments.

[0102] The pressure change trend is obtained by averaging the various pressure change rates.

[0103] When the pressure change trend is greater than 0, it indicates that the instantaneous pressure is increasing over time, the combustible gas in the flow fluctuation zone is in a state of continuous pressurization or accumulation, and the flow fluctuation zone has the risk of expanding to a larger area of ​​the safe flow zone; when the pressure change trend is less than 0, it indicates that the instantaneous pressure is decreasing over time, the combustible gas in the flow fluctuation zone is in a state of pressure release or decay, and the flow fluctuation zone tends to contract in the direction of reduction.

[0104] After standardizing the pressure change trend and coverage ratio respectively, the pressure change coefficient and coverage ratio coefficient are obtained.

[0105] It should be explained that the standardization methods include, but are not limited to, standard linear transformation based on interval scaling, statistical Z-Score standardization, or normalization based on nonlinear mapping functions. The application methods of standardization will not be elaborated here.

[0106] Calculate the flow prediction coefficient using the pressure variation coefficient and the coverage ratio coefficient: ,in, The preset adjustment coefficient, This is the pressure variation coefficient. The coverage ratio coefficient, It is a natural constant. For traffic flow prediction coefficients;

[0107] The historical data database retrieves the historical division moments of the monitoring flow area and the safe flow area. The historical division moment refers to the time record corresponding to the re-division of the boundary position of the monitoring flow area and the safe flow area, reflecting the time sequence information of the change of the combustible gas flow state over time and the triggering of boundary updates.

[0108] After sorting the historical division moments in chronological order, the difference between adjacent historical division moments is used to obtain the historical division interval.

[0109] The relationship between each historical partition interval is linearly fitted using the least squares method. The independent variable of the linear fitting is the index corresponding to the historical partition interval, and the dependent variable is the historical partition interval. The linear fitting yields the periodic change slope and intercept term. The periodic change slope refers to the trend of the historical partition interval over time, and the intercept term refers to the overall average offset of the historical partition interval.

[0110] Period division based on the slope of periodic change: ,in, The slope of the periodic change. For the intercept term, This is the sequence number of the most recent historical interval. To divide the period;

[0111] Adjusting the division period using flow prediction coefficients: ,in, To preset the prediction coefficient threshold, For flow prediction coefficients, For the preset scaling factor, To divide the period, The adjusted division period;

[0112] The boundary between the monitoring flow zone and the safe flow zone is recalculated based on the adjusted division period, and the updated region division results are generated.

[0113] When the flow prediction coefficient is greater than the preset prediction coefficient threshold, the current division cycle is shortened, the area boundary is updated in advance, and the response speed to the expansion trend of flow fluctuation zone is improved; when the flow prediction coefficient is less than the preset prediction coefficient threshold, the division cycle is extended to improve the overall operating efficiency of the monitoring system.

[0114] It should be noted that the preset statistical period can be set according to the dynamic change frequency of combustible gas flow and the time scale of instantaneous pressure; the pressure sensor is a fluid pressure measuring device used to detect the instantaneous pressure of combustible gas; the preset adjustment coefficient can be set according to the sensitivity of instantaneous pressure and coverage ratio changes to risk or the historical control effect under different operating conditions; the historical record database is used to store operation and maintenance records related to the historical division time of the monitoring flow zone and the safe flow zone; the least squares method is a linear fitting method based on the principle of minimizing the sum of squared errors, which is used in this embodiment to fit the changing trend of the historical division period to obtain the period change slope and intercept term; the preset scaling factor can be set according to the impact of period adjustment on the system operation stability and boundary update sensitivity; the preset prediction coefficient threshold can be set according to the distribution range of historical pressure change trends and the statistical characteristics of the coverage ratio.

[0115] Through the aforementioned adjustment mechanism based on flow prediction coefficients, the dynamic boundary delineation process between the monitoring flow zone and the safe flow zone simultaneously possesses both early response capability and self-balancing capability, making the zone delineation frequency more closely match the characteristics of fluid disturbance, thereby improving the temporal resolution and spatial delineation accuracy of combustible gas flow measurement.

[0116] Finally, it should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0117] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0118] In this document, the singular forms “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that terms such as “comprising / including” or “having” specify the presence of the stated features, integrals, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integrals, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0119] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0120] The above description of the disclosed embodiments will enable those skilled in the art to make or use various modifications to these embodiments. It will be readily apparent to those skilled in the art that the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating region boundaries based on combustible gas flow gradient, characterized in that: Includes the following steps: Step S1: Call the division information of the monitoring flow area and the safe flow area through the flow division library, collect the combustible gas concentration in the monitoring flow area according to the division information and count the concentration duration, and determine whether the boundary analysis mechanism is triggered based on the concentration duration. Step S2: In the boundary analysis mechanism, the instantaneous flow rate of combustible gas at the boundary between the monitoring flow zone and the safe flow zone is collected to calculate the flow gradient. The observation duration is set to collect the concentration of combustible gas and calculate the concentration change rate. The flow gradient is combined to analyze the flow fluctuation distance. Step S3: Divide the safe flow zone based on the flow fluctuation distance to obtain the flow fluctuation band, detect the coverage ratio of the flow fluctuation band and the flow velocity of the combustible gas, and use the flow velocity to evaluate the flow state and classify it as laminar or turbulent flow. Step S4: When the flow state is turbulent, detect the instantaneous pressure of combustible gas in the flow fluctuation zone and evaluate the pressure change trend. Combine the coverage ratio to generate the flow prediction coefficient, call the historical division time of the monitoring flow zone and the safe flow zone to calculate the division period, and use the flow prediction coefficient to adjust the division period.

2. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 1, characterized in that: In step S1, in the chemical production operation area, the site space is divided into zones for management based on the flow characteristics of combustible gases. The monitoring flow zone is used to focus on monitoring the changes in the flow rate and concentration of combustible gases, while the safe flow zone serves as an auxiliary area outside the monitoring flow zone. The traffic partitioning library retrieves the partitioning information of the monitoring traffic area and the safe traffic area, including the spatial range of the monitoring traffic area, the spatial range of the safe traffic area, and the boundary position formed when the two were partitioned in the last time. Gas sensors are deployed according to the spatial range of the monitoring flow area. The instantaneous concentration value of combustible gas at the sampling time is obtained from each gas sensor in the monitoring flow area according to the preset sampling frequency, which is used as the combustible gas concentration in the monitoring flow area.

3. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 2, characterized in that: In step S1, based on the collection and recording of combustible gas concentration over time, the duration during which the combustible gas concentration is continuously maintained above the monitoring concentration threshold within the time window from the start of collection to the current time is defined as the concentration duration. When the concentration duration is greater than or equal to the preset boundary analysis trigger threshold, the boundary analysis mechanism is triggered; If the duration of concentration is less than the preset boundary analysis trigger threshold, the existing region division will be maintained and the boundary analysis mechanism will not be triggered.

4. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 1, characterized in that: In step S2, in the boundary analysis mechanism, the instantaneous flow rate of combustible gas at the boundary between the monitored flow zone and the safe flow zone is collected by flow sensors deployed at monitoring points at the boundary locations; The flow gradient is obtained by spatial difference calculation of the instantaneous flow at different monitoring points at the boundary; The concentration of combustible gas at the boundary is continuously collected during the set observation period. The instantaneous concentration value of combustible gas at the boundary is collected by a gas sensor within the observation period, and the concentration change rate is calculated by time difference.

5. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 4, characterized in that: In step S2, the weighted summation method is used to linearly combine the flow gradient and the concentration change rate to calculate the boundary fluctuation amplitude; The average boundary fluctuation of all monitoring points along the boundary is obtained by taking the time average of the boundary fluctuation amplitudes of all monitoring points within the observation period. The average of the boundary fluctuations of all monitoring points is used as the fluctuation distance ratio coefficient. The flow fluctuation distance is obtained by multiplying the fluctuation distance ratio coefficient by the area width of the safe flow zone. The area width of the safe flow zone is defined as the average distance from the boundary between the monitoring flow zone and the safe flow zone along the normal direction to the outer boundary of the safe flow zone.

6. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 1, characterized in that: In step S3, the original boundary of the safe flow zone is used as a reference, and the spatial area covered by the flow fluctuation distance extended from the original boundary into the safe flow zone is used as the flow fluctuation zone. The percentage of the area of ​​the flow fluctuation zone relative to the safe flow zone is taken as the coverage ratio of the flow fluctuation zone; The sampling period is preset and divided into multiple sampling times. The flow velocity of combustible gas at the sampling time is collected by a flow velocity sensor deployed inside the flow fluctuation zone.

7. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 6, characterized in that: In step S3, the average value of each flow velocity is taken to obtain the flow velocity mean, and the standard deviation of each flow velocity is calculated as the flow fluctuation factor. The flow velocities are sorted in chronological order. The absolute difference between the flow velocities at adjacent sampling times is taken to obtain the magnitude of the change. The average magnitude of the change is obtained by averaging the magnitudes of the changes. The ratio of the flow fluctuation factor to the mean flow velocity is taken as the velocity dispersion ratio, and the ratio of the average variation amplitude to the mean flow velocity is taken as the velocity fluctuation ratio. The reciprocal of the sum of the velocity dispersion ratio and the velocity fluctuation ratio is used as the flow stability index; If the flow stability index is greater than the preset flow stability threshold, the flow state is determined to be laminar flow. Conversely, the flow state is determined to be turbulent.

8. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 1, characterized in that: In step S4, when the flow state is turbulent, a preset statistical period is divided into multiple statistical moments, and the instantaneous pressure of the combustible gas at each statistical moment is detected by a pressure sensor. The instantaneous pressure at each statistical moment is sorted in chronological order, and the pressure change rate is obtained by subtracting the instantaneous pressure at adjacent statistical moments and dividing by the time interval between adjacent statistical moments. The pressure change trend is obtained by averaging the various pressure change rates.

9. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 8, characterized in that: In step S4, the pressure change trend and coverage ratio are standardized to obtain the pressure change coefficient and coverage ratio coefficient, respectively. The flow prediction coefficient is calculated using the pressure variation coefficient and the coverage ratio coefficient. The historical data database retrieves the historical division times of the monitoring flow area and the safe flow area. The historical division times are the time records corresponding to the re-division of the boundary positions of the monitoring flow area and the safe flow area. After sorting the historical division moments in chronological order, the difference between adjacent historical division moments is used to obtain the historical division interval.

10. The method for calculating the region boundary based on the combustible gas flow gradient according to claim 9, characterized in that: In step S4, the relationship between each historical division interval is linearly fitted using the least squares method. The independent variable of the linear fitting is the sequence number corresponding to the historical division interval, and the dependent variable is the historical division interval. After linear fitting, the periodic change slope and intercept term are obtained. Period division based on the slope of periodic change: ,in, The slope of the periodic change. For the intercept term, This is the sequence number of the most recent historical interval. To divide the period; The division period is adjusted using the flow prediction coefficient.

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