A method and system for preventing blockage and explosion in pulverized coal conveying

Abstract

This invention discloses a blockage and explosion-proof control method and system for pulverized coal conveying. The method calculates a flow stability index using the ratio of the standard deviation to the mean of the pressure pulsation signal, the energy integral of the electrostatic discharge signal at high frequencies, and the pulverized coal concentration deviation. When the flow stability index exceeds a first preset threshold, the pulverized coal conveying is determined to be in the initial stage of blockage. The system then controls the conveying fan to superimpose a sinusoidal disturbance signal of a specific frequency onto a reference wind speed, creating a pulsed airflow within the pipeline. Real-time data collection of oxygen concentration, pulverized coal concentration, electrostatic discharge energy, and local temperature within the pipeline is used to calculate an explosion risk index. Based on the magnitude of the explosion risk index, a gradient inerting strategy is implemented, controlling the opening of the nitrogen control valve group to adjust the nitrogen replenishment. This invention achieves safe monitoring of the pulverized coal conveying process. The system improves the accuracy of explosion-proof inerting control.

Description

Technical Field

[0001] This invention belongs to the field of safety control technology for pulverized coal pneumatic conveying, and relates to a method and system for preventing blockage and explosion in pulverized coal conveying. Background Technology

[0002] Pulverized coal conveying is a critical process in thermal power generation and coal chemical industries. In existing pneumatic conveying systems, pulverized coal is transported over long distances through pipelines driven by fans. This process requires simultaneously ensuring the flowability of the pulverized coal to prevent blockages and ensuring environmental safety to prevent explosions.

[0003] Current conveying systems primarily rely on constant air velocity to maintain the suspension and transport of pulverized coal. However, when the conveying concentration is high or the pipeline layout is complex, pulverized coal is prone to deposition at bends or changes in diameter. Existing anti-clogging measures typically involve manually increasing the fan speed or using a simple logic controller after an increase in pressure differential is detected. This passive adjustment method has a delayed response, often only initiating action after the blockage has already reached a certain extent, leading to difficulties in unblocking and affecting system stability.

[0004] In terms of explosion protection, existing technologies mainly rely on fixed nitrogen protection systems. These typically involve setting a fixed oxygen concentration alarm threshold, and once exceeded, a large amount of nitrogen is injected. This control strategy lacks a comprehensive assessment of multiple risks, including pulverized coal concentration, electrostatic energy, and localized high temperatures. This results in high nitrogen consumption and an inability to perform fine-grained inerting based on actual risk levels, leading to safety blind spots or resource waste.

[0005] Furthermore, existing systems lack refined perception of flow conditions. Subtle flow anomalies at the initial stages of blockage, such as slight changes in pressure pulsations and alterations in electrostatic characteristics, often fail to be detected in time. This failure to implement effective disturbance measures at the nascent stage of blockage ultimately leads to transport interruptions, impacting production continuity. Therefore, there is an urgent need for an intelligent control method and system that can simultaneously address the aforementioned problems of blockage prevention and explosion prevention. Summary of the Invention

[0006] To address the problems existing in the background art, this invention proposes a blockage and explosion-proof control method and system for pulverized coal conveying.

[0007] The first aspect of this application provides a method for preventing blockage and explosion during pulverized coal conveying, comprising: The sensor array collects pressure pulsation signals, pipe wall friction electrostatic discharge signals, and coal powder concentration data in real time within the coal powder conveying pipeline. The flow stability index is calculated based on the ratio of the standard deviation to the mean of the pressure pulsation signal, the energy integral of the electrostatic discharge signal in the high-frequency band, and the coal powder concentration deviation. When the flow stability index is greater than the first preset threshold, it is determined that the coal powder conveying is in the initial stage of blockage. The conveying fan is controlled to superimpose a sinusoidal disturbance signal of a specific frequency on the reference wind speed to form a pulse airflow in the pipeline. Real-time data collection of oxygen concentration, coal dust concentration, electrostatic discharge energy, and local temperature within the pipeline; calculation of the explosion risk index. Based on the magnitude of the explosion risk index, a gradient inerting strategy is implemented to control the opening of the nitrogen control valve assembly to adjust the nitrogen replenishment amount.

[0008] Optionally, the formula for calculating the flow stability index is: ; in, It is the flow stability index; This is the pressure pulsation weighting factor; The standard deviation of the pressure pulsation signal; This represents the average value of the pressure pulsation signal; These are the electrostatic characteristic weighting coefficients; This is a characteristic frequency band for high-frequency discharge; The power spectral density of the electrostatic discharge signal; The average delivery wind speed; The weighting factor for concentration deviation; This represents the measured average coal powder concentration. The target coal powder concentration is set.

[0009] Optionally, the frequency of the sinusoidal disturbance signal at a specific frequency satisfies the following relationship: ; Where n is a positive integer; c is the velocity of sound in the gas-solid two-phase flow, which is obtained by looking up a table based on the average coal powder concentration and gas temperature in the coal powder conveying pipeline; This refers to the length of the pulverized coal conveying pipeline.

[0010] Optionally, the formula for calculating the explosion risk index is: ; in, Explosion risk index; This is the empirical coefficient for the coupling term between pulverized coal concentration and oxygen concentration. This refers to the oxygen concentration inside the pipeline. This refers to the concentration of pulverized coal. This is an empirical coefficient for electrostatic discharge energy; This refers to the energy generated by electrostatic discharge. This is an empirical coefficient for the local high temperature. This refers to the local temperature of the pipeline.

[0011] Optionally, the step of implementing a gradient inertia strategy based on the magnitude of the explosion risk index includes: When the explosion risk index is greater than the second preset threshold and less than the third preset threshold, it is determined to be a warning state and the first-stage nitrogen supply valve is opened. When the explosion risk index is greater than or equal to the third preset threshold, an emergency state is determined, the coal powder supply is cut off, and the emergency replacement valve is fully opened.

[0012] A second aspect of this application provides an anti-blocking and explosion-proof control system for pulverized coal conveying, comprising: The data acquisition module is used to collect pressure pulsation signals, pipe wall friction electrostatic discharge signals, coal powder concentration data, oxygen concentration, coal powder concentration, electrostatic discharge energy, and local temperature in the coal powder conveying pipeline in real time. The data processing module is used to calculate the flow stability index and explosion risk index based on the collected data, and to generate control commands; The command processing module is used to receive and execute the control commands.

[0013] Optionally, the formula for calculating the flow stability index is: ; in, It is the flow stability index; This is the pressure pulsation weighting factor; The standard deviation of the pressure pulsation signal; This represents the average value of the pressure pulsation signal; These are the electrostatic characteristic weighting coefficients; This is a characteristic frequency band for high-frequency discharge; The power spectral density of the electrostatic discharge signal; The average delivery wind speed; The weighting factor for concentration deviation; This represents the measured average coal powder concentration. The target coal powder concentration is set.

[0014] Optionally, the formula for calculating the explosion risk index is: ; in, Explosion risk index; This is the empirical coefficient for the coupling term between pulverized coal concentration and oxygen concentration. This refers to the oxygen concentration inside the pipeline. This refers to the concentration of pulverized coal. This is an empirical coefficient for electrostatic discharge energy; This refers to the energy generated by electrostatic discharge. This is an empirical coefficient for the local high temperature. This refers to the local temperature of the pipe. Optionally, Optionally, the data processing module is used to execute a gradient inerting strategy based on the magnitude of the explosion risk index, and control the opening of the nitrogen control valve group to adjust the nitrogen replenishment amount.

[0015] Optionally, the step of implementing a gradient inertia strategy based on the magnitude of the explosion risk index includes: When the explosion risk index is greater than the second preset threshold and less than the third preset threshold, it is determined to be a warning state and the first-stage nitrogen supply valve is opened. When the explosion risk index is greater than or equal to the third preset threshold, an emergency state is determined, the coal powder supply is cut off, and the emergency replacement valve is fully opened.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a blockage and explosion prevention control method and system for pulverized coal conveying, which can effectively improve the safety and stability of the pulverized coal conveying process. Multiple key data points within the pulverized coal conveying pipeline are collected in real time through a sensor array. The data processing module performs comprehensive analysis and judgment based on the collected data. The system can achieve early identification and proactive intervention for blockage and explosion risks. This invention enables proactive blockage prevention. The system calculates a flow stability index based on the ratio of the standard deviation to the mean of the pressure pulsation signal. This index can sensitively reflect minute changes in the pulverized coal flow state. The system can make accurate judgments in the early stages of blockage formation. A specific frequency sinusoidal disturbance signal is superimposed onto the variable frequency conveying fan. This measure can generate pulsed airflow, effectively dispersing deposited pulverized coal. This proactive disturbance method responds quickly, avoiding the lag of traditional passive adjustment methods. It significantly reduces the probability of pipeline blockage and ensures production continuity. This invention enables accurate assessment of explosion risks. Multiple factors such as oxygen concentration, pulverized coal concentration, electrostatic discharge energy, and local temperature are comprehensively considered. An explosion risk index is calculated based on these parameters. This index can comprehensively reflect the current environmental hazard level. Based on the risk index, the system implements a gradient inertia strategy. In a warning state, a small amount of nitrogen is replenished. In an emergency state, power to the coal feeder is cut off and the emergency purging valve is fully opened. This strategy achieves refined management of safety protection, ensuring production safety while avoiding waste of nitrogen resources. Attached Figure Description

[0017] Figure 1 This is a flowchart of an anti-blocking and explosion-proof control method for pulverized coal conveying according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an anti-blocking and explosion-proof control system for pulverized coal conveying according to one embodiment of the present invention. Detailed Implementation

[0018] 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.

[0019] In one embodiment, such as Figure 1 As shown, a method for preventing blockage and explosion in pulverized coal conveying is provided, which is applied to... Figure 1 Taking China as an example, the following specific steps will be used: S10: Real-time acquisition of pressure pulsation signals, pipe wall friction electrostatic discharge signals, and coal powder concentration data within the coal powder conveying pipeline via a sensor array.

[0020] Specifically, the sensor array includes high-frequency pressure sensors, electrostatic probes, and concentration sensors. High-frequency pressure sensors are installed in straight sections and bends of the pulverized coal conveying pipeline. These sensors capture minute pressure fluctuations generated during fluid flow, acquiring data at a sampling frequency of several kilohertz per second. This high-frequency acquisition method can capture weak flow instability signals in the early stages of blockage. Electrostatic probes are embedded in the inner wall surface of the pulverized coal conveying pipeline. During high-speed transport, pulverized coal particles rub against the pipe wall. This friction generates static charge that accumulates on the pipe wall. The electrostatic probes directly contact the pipe wall to detect the discharge signals of this frictional static electricity. The probes can sense changes in static energy release at the microsecond level, which is crucial for assessing the risk of static charge accumulation and early blockage. Concentration sensors employ capacitance tomography or microwave measurement principles. They are installed around a specific cross-section of the pipeline. These sensors can non-invasively measure the distribution density of pulverized coal in the airflow, generating a concentration distribution image of the pipeline cross-section, allowing the system to monitor the dynamic changes in pulverized coal concentration in real time. Exemplarily, all sensors are connected to a data acquisition card via shielded cables. The data acquisition card converts analog signals into digital signals. The collected pressure pulsation signals, electrostatic discharge signals, and pulverized coal concentration data are synchronously transmitted to the data processing module. This synchronous acquisition ensures the temporal consistency between different physical quantities, providing reliable data support for the subsequent accurate calculation of the flow stability index and explosion risk index.

[0021] S20: Calculate the flow stability index based on the ratio of the standard deviation to the mean of the pressure pulsation signal, the energy integral of the electrostatic discharge signal in the high-frequency band, and the coal powder concentration deviation.

[0022] Specifically, firstly, statistical analysis is performed on the collected pressure pulsation signals. The standard deviation of the pressure pulsation signals within a time window is calculated. This standard deviation reflects the dispersion of pressure fluctuations. Simultaneously, the mean of the pressure pulsation signals within this time window is calculated. This mean represents the average pressure level during that period. Dividing the standard deviation by the mean yields the dimensionless coefficient of pressure fluctuation. This coefficient increases significantly when the flow within the pipeline becomes unstable or local bridging occurs. Secondly, frequency domain analysis is performed on the electrostatic discharge signals from pipe wall friction. A fast Fourier transform is used to convert the time-domain electrostatic discharge signals into frequency-domain signals. In the frequency domain, a high-frequency range is defined, and the integral value of the signal energy within this high-frequency range is calculated. An increase in the energy integral value in the high-frequency range usually indicates severe friction or irregular collisions between particles and the pipe wall, which is often a characteristic of impending blockage. Thirdly, the coal powder concentration deviation value is obtained. The real-time collected coal powder concentration data is compared with the set standard concentration value, and the absolute value of the difference between the two is calculated. This deviation value reflects the stability of the transport medium's proportions. Both excessively high and low concentrations can affect the flow pattern of gas-solid two-phase flow, thus impacting flow stability. Finally, the three parameters mentioned above are weighted and fused to construct a calculation model for the flow stability index. This model linearly or nonlinearly combines the dimensionless coefficient of pressure fluctuation, the high-frequency energy integral value, and the coal powder concentration deviation value according to preset weighting coefficients. These weighting coefficients are determined through historical data training or expert experience. The calculated flow stability index is a comprehensive evaluation indicator. The higher the index, the more unstable the flow state within the pipeline, and the greater the risk of blockage.

[0023] This invention enables a comprehensive assessment of flow conditions. While a single parameter may lead to misjudgment, combining the characteristics of pressure, static electricity, and concentration significantly improves the accuracy of the assessment. This invention can sensitively detect subtle signs of impending blockage, providing valuable time for the system to initiate anti-blockage measures in advance. This avoids production interruptions and equipment damage caused by unstable flow.

[0024] The formula for calculating the flow stability index is as follows: ; in, It is the flow stability index; This is the pressure pulsation weighting factor; The standard deviation of the pressure pulsation signal; This represents the average value of the pressure pulsation signal; These are the electrostatic characteristic weighting coefficients; This is a characteristic frequency band for high-frequency discharge; The power spectral density of the electrostatic discharge signal; The average delivery wind speed; The weighting factor for concentration deviation; This represents the measured average coal powder concentration. The target coal powder concentration is set.

[0025] It is important to note that the first term in the formula reflects the dispersion of the pressure pulsation. The pressure pulsation signal acquired by the high-frequency pressure sensor has certain statistical characteristics. This represents the standard deviation of the signal, which describes how the pressure value varies around its mean. The magnitude of the fluctuation. As a pressure pulsation weighting coefficient, it is used to adjust the contribution weight of this term in the overall index. When the pulverized coal flow becomes unstable or begins to deposit, the pressure fluctuations within the pipeline become drastic, leading to a significant increase in the standard deviation. This term can sensitively capture minute disturbances in this flow state. The second term in the formula reflects the high-frequency characteristics of electrostatic discharge. The electrostatic signal generated by the friction between pulverized coal particles and the pipe wall contains rich frequency components. This represents the power spectral density of the electrostatic signal. The system focuses on the high-frequency discharge characteristic band. Energy integral within. As a weighting coefficient for electrostatic characteristics, it is used to balance the influence of this term. In the early stages of blockage, the aggregation and sliding patterns of pulverized coal particles change, leading to an increase in high-frequency discharge events. The energy integral of this frequency band is divided by the average conveying wind speed. This can eliminate the interference of wind speed changes on electrostatic characteristics, making the indicators more objective. The third term in the formula reflects the control deviation of pulverized coal concentration. This represents the measured average coal powder concentration. This indicates the set target coal powder concentration. The weighting coefficient for concentration deviation is used to adjust the sensitivity of this item. This part calculates the relative deviation between the measured concentration and the target concentration. When abnormalities occur in the conveying process, the measured concentration will deviate from the set value. This item directly reflects the control performance and material balance of the conveying system. For example, the data processing module reads data from the sensor array in real time. The module performs calculations according to the above formula. Each parameter is calibrated according to the actual operating conditions. Weighting coefficient , , The value is set based on the pipe material, pulverized coal particle size, and conveying distance. Through this multi-parameter fusion calculation method, the flow stability index... This invention provides a highly sensitive blockage early warning mechanism that comprehensively and accurately reflects the flow health status within pipelines. Monitoring a single parameter is easily affected by environmental noise, leading to misjudgments. This formula effectively overcomes the limitations of a single indicator by weighted fusion of signals from three different dimensions: pressure, static electricity, and concentration. It can identify early signs of flow instability, providing an accurate basis for subsequent anti-blockage control measures.

[0026] S30: When the flow stability index is greater than the first preset threshold, it is determined that the coal powder conveying is in the initial stage of blockage. The conveying fan is controlled to superimpose a sinusoidal disturbance signal of a specific frequency on the reference wind speed to form a pulse airflow in the pipeline.

[0027] Specifically, when the flow stability index calculated by the data processing module continuously exceeds the first preset threshold, the system determines that the pulverized coal conveying is in the initial stage of blockage. This state is usually manifested as pulverized coal particles beginning to locally accumulate on the pipe wall, or the flow pattern becoming turbulent, but the airflow has not yet been completely blocked. At this time, the system immediately generates a control command and sends it to the frequency converter controller of the conveying fan. The control fan superimposes a sinusoidal disturbance signal of a specific frequency onto the reference wind speed. The reference wind speed is the stable airflow velocity required to maintain normal pulverized coal conveying. The sinusoidal disturbance signal of a specific frequency is a frequency that has been experimentally verified in advance and can effectively disrupt powder bridging or agglomeration. This sinusoidal signal is used as a modulation signal and superimposed on the control signal of the reference wind speed. The conveying fan adjusts its speed according to the superimposed composite signal. The fan speed is no longer constant, but fluctuates periodically according to a sinusoidal law. This speed fluctuation causes the airflow pressure and velocity in the conveying pipeline to change periodically. A pulsed airflow is formed in the pipeline. This pulsed airflow has alternating high-pressure, high-velocity zones and low-pressure, low-velocity zones. The high-pressure, high-velocity zone impacts and disperses coal dust clumps accumulated within the pipeline. The low-pressure, low-velocity zone provides a buffer time for the redistribution of coal dust particles. The periodic disturbance of the pulsed airflow disrupts the balance of adhesion and friction between coal dust particles and between coal dust and the pipe wall. It effectively prevents coal dust from forming stable arches or bridging under gravity or electrostatic forces. For example, the selection of a specific frequency is crucial. Too high a frequency may prevent the airflow disturbance from reaching the central region of the pipeline, while too low a frequency may fail to effectively interrupt the blockage formation process. The specific frequency is typically related to the physical properties of the coal dust, the pipe diameter, and the conveying distance. The system automatically selects the optimal specific frequency for disturbance based on different operating parameters. This embodiment enables accurate identification and rapid response to the initial state of blockage. Traditional control methods often only take action after blockage has occurred and the flow rate has significantly decreased, at which point unblocking is more difficult. This embodiment, however, eliminates blockage in its nascent stage by actively applying pulsed airflow with minimal energy consumption. This invention improves the self-healing capability of the coal dust conveying system. It avoids transport interruptions and production losses caused by blockages. At the same time, it reduces the maintenance workload of manually tapping pipes or stopping the machine for cleaning, and improves the system's automation level and operational safety.

[0028] The frequency of the sinusoidal disturbance signal at a specific frequency satisfies the following relationship: ; Where n is a positive integer; c is the velocity of sound in the gas-solid two-phase flow, which is obtained by looking up a table based on the average coal powder concentration and gas temperature in the coal powder conveying pipeline; This refers to the length of the pulverized coal conveying pipeline.

[0029] It is important to note that in the formula... represents the total length of the pulverized coal conveying pipeline. This length is an inherent parameter of the physical structure. c represents the velocity of sound in the gas-solid two-phase flow. This velocity is not a fixed value; it is affected by the state of the medium inside the pipeline. The magnitude of the velocity is closely related to the average pulverized coal concentration and gas temperature within the pipeline. The system has a built-in preset parameter lookup table. The data processing module queries this table based on the real-time measured average pulverized coal concentration and gas temperature to obtain the corresponding velocity of sound c. n represents the positive integer harmonic order. This value is automatically selected by the control system based on the specific boundary conditions of the pipeline. This represents the frequency of the sinusoidal disturbance signal to be superimposed. The calculation of the frequency of the sinusoidal disturbance signal follows the physical laws of standing wave formation within the pipe. For example, a sinusoidal disturbance signal is superimposed on a reference wind speed control signal by controlling a variable frequency conveyor fan. The frequency of this disturbance signal is strictly set according to the formula described above. When the frequency satisfies this relationship, the pulsed airflow propagates within the pipe. The pulsed airflow is reflected at the pipe's ends. The incident wave and the reflected wave superimpose within the pipe. This superposition forms a stable standing wave pressure field. The standing wave pressure field has specific distribution characteristics within the pipe. Antinodes are formed in the middle of the pipe. The pressure pulsation amplitude reaches its maximum at the antinodes. Nodes are formed at both ends of the pipe. This pressure distribution generates a strong longitudinal oscillation force. This strong longitudinal oscillation force acts on the deposited or accumulated coal dust layer. It effectively disperses coal dust agglomerates. It can peel off coal dust adhering to the pipe wall. This resonant disturbance method achieves maximum unblocking effect with minimal energy input.

[0030] This invention provides a highly efficient and energy-saving active anti-clogging mechanism that precisely matches the acoustic characteristics of the pipeline to create resonance between the pulsed airflow and the pipeline structure. This resonance effect greatly enhances the airflow's ability to carry pulverized coal, effectively removing pulverized coal from dead flow zones, significantly improving the smoothness and stability of pulverized coal transportation, and avoiding the energy waste caused by blindly increasing airflow in the traditional method.

[0031] S40: Real-time acquisition of oxygen concentration, coal dust concentration, electrostatic discharge energy, and local temperature within the pipeline to calculate the explosion risk index.

[0032] Specifically, firstly, high-precision oxygen sensors are used to collect real-time oxygen concentration data within the pipeline. These sensors, employing electrochemical or paramagnetic principles, are installed at the air inlet and areas prone to coal accumulation within the pipeline. The sensors continuously monitor the oxygen content in the gaseous environment at a sampling frequency of once per second. Oxygen concentration is a key indicator of the likelihood of an explosion; excessively high oxygen concentrations significantly lower the ignition point of pulverized coal. Secondly, an electrostatic sensor array is used to collect electrostatic discharge energy. The electrostatic sensors not only detect electrostatic potential but also calculate the discharge energy per unit time through integration. The sensors capture transient discharge pulses generated by the friction of pulverized coal particles. The magnitude of the discharge energy directly affects whether a flammable gas mixture can be ignited. High-energy electrostatic sparks are one of the main ignition sources for pulverized coal explosions. Thirdly, a concentration sensor is used to acquire pulverized coal concentration data. This sensor, based on capacitive, microwave, or electrostatic induction principles, measures the mass concentration of pulverized coal at the pipeline cross-section. The system compares the real-time concentration with the lower explosive limit. When the pulverized coal concentration is within the explosive limit range, the risk of explosion increases significantly. The sensors ensure accurate data even under abnormal high or low concentration conditions. Finally, temperature sensors are used to monitor the local temperature inside the pipeline. These sensors, employing thermocouples or platinum resistance thermometers, are installed on easily worn parts such as pipe walls and bends. The sensors provide real-time feedback on local environmental temperature changes. Abnormal temperature increases may be due to frictional heating or initial smoldering, which are important signs of an impending explosion. After obtaining the above four parameters, a calculation model for the explosion risk index is constructed. Oxygen concentration, coal dust concentration, electrostatic discharge energy, and local temperature are normalized. Weighting coefficients are assigned based on the contribution of each parameter to the explosion. For example, a higher weight is given when the coal dust concentration is within the explosion limit range. The weight is also increased when the electrostatic discharge energy exceeds the safety threshold. A comprehensive explosion risk index is calculated using a weighted summation or fuzzy logic algorithm. This index is a dimensionless value that comprehensively reflects the explosion hazard level under the current operating conditions. This embodiment enables dynamic assessment of explosion risk. Traditional monitoring methods typically focus on only a single parameter, easily overlooking the explosion risk under the coupled effects of multiple factors. This embodiment, by comprehensively analyzing four key factors—oxygen, coal dust, electrostatic discharge, and temperature—can identify potential explosion hazards in advance. This invention improves the safety early warning capability of pulverized coal conveying systems. It provides reliable early warning signals before an explosion occurs, allowing sufficient time for the system to take safety measures such as reducing oxygen levels, shutting down, or depressurizing. This effectively avoids equipment damage and personnel casualties caused by pulverized coal explosions, ensuring the safe and stable operation of the production process.

[0033] The formula for calculating the explosion risk index is as follows: ; in, Explosion risk index; This is the empirical coefficient for the coupling term between pulverized coal concentration and oxygen concentration. This refers to the oxygen concentration inside the pipeline. This refers to the concentration of pulverized coal. This is an empirical coefficient for electrostatic discharge energy; This refers to the energy generated by electrostatic discharge. This is an empirical coefficient for the local high temperature. This refers to the local temperature of the pipeline.

[0034] Specifically, the first term in the formula represents the coupling effect between the combustible material and the oxidizer. This represents the oxygen concentration inside the pipe. This represents the concentration of pulverized coal. When the concentration of pulverized coal is within the explosive limits and the oxygen concentration reaches a certain level, an explosive mixture is formed. The empirical coefficient, representing the coupling term between pulverized coal concentration and oxygen concentration, reflects the combustion and explosion characteristics of a specific coal type. The calculation of this term is essentially a mathematical expression of the matching relationship between combustible material and oxygen in the explosion triangle. The system determines whether a chemical environment with explosion potential has been formed by monitoring the real-time concentrations of these two components. The second term in the formula characterizes the magnitude of the ignition energy. This represents electrostatic discharge energy. Pulverized coal is highly susceptible to static electricity buildup during high-speed transport. When the electrostatic voltage reaches the breakdown threshold, a discharge occurs. This discharge energy is the primary ignition source for the pulverized coal cloud. As an empirical coefficient for electrostatic discharge energy, it is used to correct for the difference in minimum ignition energy of pulverized coal with different particle size distributions. The introduction of this term allows the system to incorporate potential ignition sources into the risk assessment framework, rather than solely focusing on the flammability of the ambient medium. The third term in the formula characterizes the thermal ignition factor. This represents the local temperature within the pipeline. High local temperatures may originate from frictional heat generated by equipment or conduction from external heat sources. Excessively high temperatures may trigger spontaneous combustion of pulverized coal. As an empirical coefficient for localized high-temperature conditions, it reflects the thermal conductivity characteristics of pipes made of different materials and the spontaneous combustion tendency of pulverized coal. Monitoring localized temperatures can effectively prevent combustion and explosion accidents caused by heat accumulation.

[0035] For example, the data processing module collects data on oxygen concentration, pulverized coal concentration, electrostatic discharge energy, and local temperature in real time. The module performs a weighted summation calculation according to the above formula. Various empirical coefficients... , , Derived from historical operational data and safety test calibrations, this linear combination method integrates four key safety parameters into a dimensionless risk index. .

[0036] This invention establishes a multi-factor comprehensive evaluation explosion early warning model. Traditional safety monitoring often relies on threshold alarms for a single parameter, which is prone to missed or false alarms. This formula, by coupling oxygen concentration and pulverized coal concentration, while also taking into account the effects of electrostatic energy and local high temperature, comprehensively covers the necessary conditions for an explosion. This comprehensive evaluation method significantly improves the accuracy and reliability of explosion risk identification, providing a scientific decision-making basis for the precise control of subsequent nitrogen control valve groups.

[0037] S50: Based on the magnitude of the explosion risk index, execute a gradient inertization strategy to control the opening of the nitrogen control valve group to adjust the nitrogen replenishment amount.

[0038] Specifically, the data processing module calculates the explosion risk index in real time, comprehensively reflecting multiple factors such as oxygen concentration, coal dust concentration, electrostatic discharge energy, and local temperature within the pipeline. When the calculated explosion risk index changes, the system activates a gradient inerting strategy.

[0039] The gradient inerting strategy includes multiple control levels, with different preset risk thresholds used to classify risk levels. When the explosion risk index is greater than the second preset threshold but less than the third preset threshold, the system determines it to be in a warning state. In this state, the data processing module generates a low-level control command. This low-level control command opens the first-stage nitrogen injection valve, injecting a small amount of high-purity nitrogen into the pulverized coal conveying pipeline. The injection of nitrogen dilutes the oxygen concentration in the pipeline, effectively inhibiting the oxidation reaction of the pulverized coal and reducing the explosion risk.

[0040] When the explosion risk index continues to rise and exceeds or equals the third preset threshold, the system determines an emergency state, and the data processing module immediately generates a high-level emergency control command. This command cuts off the power supply to the variable frequency coal feeder, forcibly stopping the coal powder delivery. Simultaneously, the command fully opens the emergency replacement valve, rapidly filling the coal powder delivery pipeline with a large amount of nitrogen. The high-concentration nitrogen environment instantly replaces the air in the pipeline, completely eliminating the conditions for the formation of an explosive gas atmosphere.

[0041] The nitrogen control valve assembly consists of multiple solenoid valves and pneumatic valves. These valves receive control signals from the data processing module, and their opening is precisely adjusted, effectively controlling the flow and pressure of nitrogen. This precise flow control ensures that the amount of nitrogen replenished is just right at different risk levels, avoiding nitrogen waste while ensuring the inerting effect.

[0042] This invention achieves refined management of safety protection. Through tiered response, it avoids resource waste or insufficient response caused by single actions. In the early warning state, it provides minor replenishment, maintaining production continuity. In the emergency state, it performs rapid cutoff and full-opening replacement, ensuring the absolute safety of equipment and personnel, and significantly improving the inherent safety level of the pulverized coal conveying system.

[0043] In one embodiment, the step of executing a gradient inertization strategy based on the magnitude of the explosion risk index includes: when the explosion risk index is greater than a second preset threshold and less than a third preset threshold, determining it as a warning state and opening the first-stage nitrogen supply valve; when the explosion risk index is greater than or equal to the third preset threshold, determining it as an emergency state, cutting off the coal powder supply, and fully opening the emergency replacement valve.

[0044] Specifically, the data processing module continuously calculates the explosion risk index to obtain the overall safety status within the pipeline. The system has preset threshold parameters for determining the risk level. When the explosion risk index is greater than a second preset threshold but less than a third preset threshold, the system determines that the pulverized coal conveying is in a warning state. The warning state indicates that the risk of combustion and explosion within the pipeline is accumulating but has not yet reached the critical point for immediate detonation. In this situation, the data processing module generates a low-level inerting command. The low-level inerting command controls the opening of the first-stage nitrogen injection valve. The first-stage nitrogen injection valve is a subunit of the nitrogen control valve group. A small amount of high-purity nitrogen is injected into the pulverized coal conveying pipeline through this valve. The injection of nitrogen dilutes the oxygen concentration around the suspended pulverized coal within the pipeline, which slows down the oxidation reaction rate of the pulverized coal. By supplementing nitrogen in small amounts, the risk is nipped in the bud, while maintaining the continuity of production. When the explosion risk index continues to rise and is greater than or equal to the third preset threshold, the system determines that the pulverized coal conveying is in an emergency state. The emergency state indicates that the pipeline has an extremely high probability of explosion, posing an immediate danger. In this situation, the data processing module immediately generates a high-level emergency inerting command. The high-level emergency inerting command first acts on the variable frequency coal feeder. Upon receiving the cut-off signal, the feeder immediately stops rotating, forcibly interrupting the supply of pulverized coal and preventing further combustibles from entering the pipeline. Next, the command controls the emergency replacement valve. The emergency replacement valve is the high-flow-rate channel in the nitrogen control valve group. Upon receiving the command, the emergency replacement valve quickly opens fully, allowing a large amount of nitrogen to rush into the pulverized coal conveying pipeline at a high flow rate. The high concentration of nitrogen rapidly fills every corner of the pipeline, completely replacing the air inside. The explosive gas atmosphere is quickly destroyed, and an inert gas protective atmosphere is formed within the pipeline.

[0045] For example, the implementation of the gradient inerting strategy relies on precise timing control. The amount of nitrogen supplied during the early warning state is precisely calculated. It is sufficient to suppress the escalation of risk without causing drastic disturbances to the conveying air velocity. The actions during the emergency state have priority preemption characteristics, with the cutting off of pulverized coal supply and the full opening of the emergency replacement valve proceeding simultaneously. This synchronized action minimizes the response time.

[0046] This invention achieves dynamic adaptability in safety protection. By classifying warning and emergency states, the system can take the most appropriate countermeasures for different risk levels. Fine-tuning is performed during low-risk periods, while strong intervention is implemented during high-risk periods. This tiered strategy avoids production losses caused by a single emergency shutdown and also prevents the inadequacy of relying solely on trace nitrogen supplementation to cope with high risks. It significantly improves the inherent safety level and operational economy of the pulverized coal conveying system.

[0047] In one embodiment, such as Figure 2 As shown, an anti-blocking and explosion-proof control system for pulverized coal conveying is provided. This anti-blocking and explosion-proof control system for pulverized coal conveying corresponds one-to-one with the anti-blocking and explosion-proof control method for pulverized coal conveying in the above embodiments. The anti-blocking and explosion-proof control system for pulverized coal conveying includes: a data acquisition module, a data processing module, and a command processing module. The detailed description of each functional module is as follows: The data acquisition module is used to collect pressure pulsation signals, pipe wall friction electrostatic discharge signals, coal powder concentration data, oxygen concentration, coal powder concentration, electrostatic discharge energy, and local temperature in the coal powder conveying pipeline in real time. The data processing module is used to calculate the flow stability index and explosion risk index based on the collected data, and to generate control commands; The command processing module is used to receive and execute the control commands.

[0048] Specifically, the data acquisition module, acting as the system's perception layer, is responsible for real-time acquisition of multi-dimensional physical signals within the pulverized coal conveying pipeline. This module includes various types of sensors: a pressure pulsation sensor to acquire dynamic pressure change signals within the pipeline; an electrostatic sensor to acquire electrostatic discharge signals generated by friction against the pipe wall; a concentration sensor to acquire pulverized coal concentration data; an oxygen analyzer to acquire oxygen concentration within the pipeline; an energy analysis unit to quantify electrostatic discharge energy; and a temperature sensor to acquire localized pipeline temperature. All sensors sample data at high frequencies. The acquired raw signals are transmitted to the data processing module via wired or wireless means. The data acquisition module ensures the comprehensiveness and real-time nature of the monitoring data, providing a solid data foundation for subsequent risk assessment. The data processing module, acting as the system's decision-making layer, is responsible for receiving and processing data from the data acquisition module. This module first filters and denoises the raw data. Then, the module performs calculations based on a preset algorithm model. The module calculates a flow stability index to assess the likelihood of pipeline blockage. Simultaneously, the module calculates an explosion risk index to assess the degree of combustion and explosion hazard in the current environment. The explosion risk index calculation comprehensively considers multiple factors such as pulverized coal concentration, oxygen concentration, electrostatic energy, and local temperature. The data processing module pre-stores risk level judgment thresholds. The module compares the calculated index with these thresholds. When the index exceeds the set threshold, the module generates corresponding control commands. These commands include operations such as opening the nitrogen supply valve or cutting off the pulverized coal supply. The data processing module has a fast processing speed, ensuring timely decision-making. The command processing module, as the system's execution layer, is responsible for receiving and executing the control commands generated by the data processing module. This module includes drive circuits and a logic controller. The module monitors command signals from the data processing module in real time. Once a command is received, the module immediately parses the command content. For commands to open the nitrogen supply valve, the module outputs a corresponding electrical signal to drive the valve motor and adjust the valve opening. For commands to cut off the pulverized coal supply, the module immediately cuts off the power or control signal to the variable frequency coal feeder. For commands to fully open the emergency replacement valve, the module drives the emergency replacement valve's actuator to quickly reach its maximum opening. The command processing module has a short response time, ensuring that the actuator completes the specified action in the shortest possible time.

[0049] For example, the three modules exchange data via standard industrial communication protocols. A high-speed data bus connects the data acquisition module and the data processing module. Hardwiring or real-time Ethernet connects the data processing module and the command processing module. This layered architecture makes the system structure clear, facilitating maintenance and upgrades. Each module operates independently without interference. The system boasts high reliability and stability.

[0050] This invention automates and intelligently monitors the safety of pulverized coal conveying. Through comprehensive sensing by the data acquisition module, potential risk factors can be detected promptly. Through integrated calculation by the data processing module, the risk level can be accurately assessed, avoiding false alarms and missed alarms based on single parameters. Through rapid execution by the command processing module, risks can be controlled at their nascent stage. The three modules work collaboratively to form a closed-loop control system, significantly improving the safety protection level and emergency response capability of the pulverized coal conveying system.

[0051] Furthermore, the formula for calculating the flow stability index is as follows: ; in, It is the flow stability index; This is the pressure pulsation weighting factor; The standard deviation of the pressure pulsation signal; This represents the average value of the pressure pulsation signal; These are the electrostatic characteristic weighting coefficients; This is a characteristic frequency band for high-frequency discharge; The power spectral density of the electrostatic discharge signal; The average delivery wind speed; The weighting factor for concentration deviation; This represents the measured average coal powder concentration. The target coal powder concentration is set.

[0052] Furthermore, the formula for calculating the explosion risk index is as follows: ; in, Explosion risk index; This is the empirical coefficient for the coupling term between pulverized coal concentration and oxygen concentration. This refers to the oxygen concentration inside the pipeline. This refers to the concentration of pulverized coal. This is an empirical coefficient for electrostatic discharge energy; This refers to the energy generated by electrostatic discharge. This is an empirical coefficient for the local high temperature. This refers to the local temperature of the pipeline.

[0053] Furthermore, the data processing module is used to execute a gradient inerting strategy based on the magnitude of the explosion risk index, and control the opening of the nitrogen control valve group to adjust the nitrogen replenishment amount.

[0054] Further, the step of implementing a gradient inertia strategy based on the magnitude of the explosion risk index includes: When the explosion risk index is greater than the second preset threshold and less than the third preset threshold, it is determined to be a warning state and the first-stage nitrogen supply valve is opened. When the explosion risk index is greater than or equal to the third preset threshold, an emergency state is determined, the coal powder supply is cut off, and the emergency replacement valve is fully opened.

[0055] Specific limitations regarding the anti-blocking and explosion-proof control system for pulverized coal conveying can be found in the limitations on the anti-blocking and explosion-proof control methods for pulverized coal conveying described above, and will not be repeated here. Each module in the aforementioned anti-blocking and explosion-proof control system for pulverized coal conveying can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0056] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0057] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 method for preventing blockage and explosion during pulverized coal conveying, characterized in that, include: The sensor array collects pressure pulsation signals, pipe wall friction electrostatic discharge signals, and coal powder concentration data in real time within the coal powder conveying pipeline. The flow stability index is calculated based on the ratio of the standard deviation to the mean of the pressure pulsation signal, the energy integral of the electrostatic discharge signal in the high-frequency band, and the coal powder concentration deviation. When the flow stability index is greater than the first preset threshold, it is determined that the coal powder conveying is in the initial stage of blockage. The conveying fan is controlled to superimpose a sinusoidal disturbance signal of a specific frequency on the reference wind speed to form a pulse airflow in the pipeline. Real-time data collection of oxygen concentration, coal dust concentration, electrostatic discharge energy, and local temperature within the pipeline; calculation of the explosion risk index. Based on the magnitude of the explosion risk index, a gradient inerting strategy is implemented to control the opening of the nitrogen control valve assembly to adjust the nitrogen replenishment amount.

2. The anti-blocking and explosion-proof control method for pulverized coal conveying according to claim 1, characterized in that, The formula for calculating the flow stability index is as follows: ； in, It is the flow stability index; This is the pressure pulsation weighting factor; The standard deviation of the pressure pulsation signal; This represents the average value of the pressure pulsation signal; These are the electrostatic characteristic weighting coefficients; This is a characteristic frequency band for high-frequency discharge; The power spectral density of the electrostatic discharge signal; The average delivery wind speed; The weighting factor for concentration deviation; This represents the measured average coal powder concentration. The target coal powder concentration is set.

3. The anti-blocking and explosion-proof control method for pulverized coal conveying according to claim 1, characterized in that, The frequencies of the sinusoidal disturbance signal at a specific frequency satisfy the following relationship: ； in, is the frequency of the sinusoidal disturbance signal, n is a positive integer; c is the velocity of sound in the gas-solid two-phase flow, which is obtained by looking up a table based on the average coal powder concentration and gas temperature in the coal powder conveying pipeline. This refers to the length of the pulverized coal conveying pipeline.

4. The anti-blocking and explosion-proof control method for pulverized coal conveying according to claim 1, characterized in that, The formula for calculating the explosion risk index is as follows: ； in, Explosion risk index; This is the empirical coefficient for the coupling term between pulverized coal concentration and oxygen concentration. This refers to the oxygen concentration inside the pipeline. This refers to the concentration of pulverized coal. This is an empirical coefficient for electrostatic discharge energy; This refers to the energy generated by electrostatic discharge. This is an empirical coefficient for the local high temperature. This refers to the local temperature of the pipeline.

5. The anti-blocking and explosion-proof control method for pulverized coal conveying according to claim 1, characterized in that, The step of implementing a gradient inertization strategy based on the magnitude of the explosion risk index includes: When the explosion risk index is greater than the second preset threshold and less than the third preset threshold, it is determined to be a warning state and the first-stage nitrogen supply valve is opened. When the explosion risk index is greater than or equal to the third preset threshold, an emergency state is determined, the coal powder supply is cut off, and the emergency replacement valve is fully opened.

6. A blockage-proof and explosion-proof control system for pulverized coal conveying, characterized in that, For implementing the method as described in any one of claims 1 to 5, comprising: The data acquisition module is used to collect pressure pulsation signals, pipe wall friction electrostatic discharge signals, coal powder concentration data, oxygen concentration, coal powder concentration, electrostatic discharge energy, and local temperature in the coal powder conveying pipeline in real time. The data processing module is used to calculate the flow stability index and explosion risk index based on the collected data, and to generate control commands; The command processing module is used to receive and execute the control commands.

7. The anti-blocking and explosion-proof control system for pulverized coal conveying according to claim 6, characterized in that, The formula for calculating the flow stability index is as follows: ； in, It is the flow stability index; This is the pressure pulsation weighting factor; The standard deviation of the pressure pulsation signal; This represents the average value of the pressure pulsation signal; These are the electrostatic characteristic weighting coefficients; This is a characteristic frequency band for high-frequency discharge; The power spectral density of the electrostatic discharge signal; The average delivery wind speed; The weighting factor for concentration deviation; This represents the measured average coal powder concentration. The target coal powder concentration is set.

8. The anti-blocking and explosion-proof control system for pulverized coal conveying according to claim 6, characterized in that, The formula for calculating the explosion risk index is as follows: ； in, Explosion risk index; This is the empirical coefficient for the coupling term between pulverized coal concentration and oxygen concentration. This refers to the oxygen concentration inside the pipeline. This refers to the concentration of pulverized coal. This is an empirical coefficient for electrostatic discharge energy; This refers to the energy generated by electrostatic discharge. This is an empirical coefficient for the local high temperature. This refers to the local temperature of the pipeline.

9. The anti-blocking and explosion-proof control system for pulverized coal conveying according to claim 6, characterized in that, The data processing module is used to execute a gradient inerting strategy based on the magnitude of the explosion risk index, and control the opening of the nitrogen control valve group to adjust the nitrogen replenishment amount.

10. The anti-blocking and explosion-proof control system for pulverized coal conveying according to claim 9, characterized in that, The step of implementing a gradient inertization strategy based on the magnitude of the explosion risk index includes: When the explosion risk index is greater than the second preset threshold and less than the third preset threshold, it is determined to be a warning state and the first-stage nitrogen supply valve is opened. When the explosion risk index is greater than or equal to the third preset threshold, an emergency state is determined, the coal powder supply is cut off, and the emergency replacement valve is fully opened.

Images