Long distance coal seam drilling plasma ignition gasification control system

Abstract

The present application belongs to the technical field of industrial automation control, and discloses a long-distance coal seam drilling plasma ignition gasification control system. By collecting arc characteristic signals, the high-frequency disturbance component sequence is constructed by extracting the arc voltage mutation rate and the current ripple ratio. Based on the frequency domain distribution characteristics, the normal gasification, water inrush, hole wall deposition and other working conditions are identified. When water inrush occurs, the working medium injection strategy is adjusted and the super-enthalpy compensation mode is triggered. Based on the phase delay characteristics, the gas flow pulsation instruction is generated to form the jet scouring wave. The gasification working face moving prediction model is constructed to realize dynamic anchoring distance control. The present application realizes the full automation intelligent control of the plasma gasification process, and improves the stability and adaptability of the system under complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of industrial automation control technology, and more specifically, to a long-distance coal seam drilling plasma ignition gasification control system. Background Technology

[0002] Existing long-distance coal seam drilling plasma gasification technology faces several technical bottlenecks in practical applications. When the plasma torch operates in deep underground coal seams, traditional systems cannot accurately identify the complex and ever-changing working conditions within the borehole. Operators are essentially "blindly aware" of changes in the borehole environment, often encountering sudden interruptions in the gasification process without warning. Faced with the inevitable intrusion of groundwater into the coal seam, current technology still relies on a single gaseous working medium, unable to intelligently adjust the medium ratio. A large amount of arc energy is consumed by the evaporation of liquid water, frequently resulting in gasification shutdowns due to insufficient power density, forcing forced shutdowns. Solid byproducts such as coal ash and tar produced during coal seam gasification gradually accumulate and clog the borehole walls. The lack of effective online cleaning methods necessitates inefficient manual cleaning during shutdowns, severely impacting continuous operation. Traditional systems cannot predict the movement of the gasification face, and the position and power adjustment of the plasma torch rely entirely on operational experience, frequently leading to equipment overheating damage or low heat transfer efficiency. Meanwhile, plasma torch electrodes wear out rapidly in harsh environments, and the lack of condition monitoring and preventative maintenance mechanisms means frequent replacements are not only costly but also disrupt operational schedules. The ignition and startup process lacks scientific control guidelines, and the trial-and-error high-pressure startup method has a low success rate and is prone to equipment damage. These technical shortcomings intertwine, creating a vicious cycle that makes it difficult to achieve stable and efficient continuous industrial operation of long-distance coal seam drilling plasma gasification technology, thus hindering the widespread application of clean coal utilization technologies.

[0003] In view of this, the present invention proposes a long-distance coal seam drilling plasma ignition gasification control system to solve the above problems. Summary of the Invention

[0004] To overcome the aforementioned deficiencies of the prior art and to achieve the above objectives, the present invention provides the following technical solution: a long-distance coal seam drilling plasma ignition gasification control system, comprising:

[0005] The feature extraction module is used to collect the arc feature signals of the plasma torch in real time during the operation of the plasma torch in the coal seam borehole, extract the arc voltage mutation rate and current ripple ratio from the arc feature signals, and construct a high-frequency disturbance component sequence based on the arc voltage mutation rate and current ripple ratio.

[0006] The working condition identification module is used to identify the current working condition in the coal seam borehole based on the frequency domain distribution characteristics of the high-frequency disturbance component sequence, and to calculate the working condition confidence corresponding to the current working condition. The current working condition includes normal gasification state, water inrush state, and borehole wall siltation state.

[0007] The medium control module is used to determine the level of liquid water intrusion based on the level of liquid water intrusion when the current operating condition is a water intrusion state and the operating condition confidence level is greater than the preset confidence threshold. Based on the level of liquid water intrusion, the module adjusts the working medium injection strategy of the plasma torch, gradually switching the injected medium from the initial gaseous medium to the water vapor medium. At the same time, it triggers the overenthalpy compensation mode to increase the arc power density of the plasma torch until the arc characteristic signal indicates that the liquid water has completed in-situ self-evaporation.

[0008] The silt removal module is used to estimate the siltation and blockage distance based on the phase delay characteristics in the high-frequency disturbance component sequence when the current working condition is siltation on the hole wall. It generates airflow pulsation commands based on the siltation and blockage distance, and modulates the instantaneous flow velocity profile of the working medium based on the airflow pulsation commands to form a local jet scouring wave at the plasma torch nozzle to remove the siltation on the hole wall.

[0009] The predictive control module is used to construct a predictive model of the gasification working face based on the arc characteristic signal, the real-time consumption parameters of the working medium and the current working condition. Based on the predictive model, it outputs the power adjustment amount and axial feed control command of the plasma torch to maintain a dynamic anchoring distance between the gasification working face and the nozzle of the plasma torch.

[0010] The technical effects and advantages of the long-distance coal seam drilling plasma ignition gasification control system of this invention are as follows:

[0011] This invention can accurately identify various working condition changes within the borehole and provide reliable confidence assessments, laying the foundation for precise control. Through intelligent medium adjustment and power density compensation, this invention achieves efficient in-situ treatment of liquid water, solving the problem of vaporization interruption caused by water inrush and significantly improving adaptability under complex hydrogeological conditions. For borehole wall siltation, this invention achieves precise positioning and online cleaning, eliminating the constraints of traditional shutdown procedures and ensuring long-term borehole continuity. By constructing a predictive model driven by physical principles, this invention can proactively optimize plasma torch configuration, dynamically maintaining optimal heat transfer efficiency and improving energy utilization. Improved equipment lifespan management, through intelligent cooling and wear assessment mechanisms, significantly extends the service life of key components and substantially reduces maintenance costs. Scientific ignition start-up control eliminates the blindness of traditional operations, improving success rates and protecting equipment safety. Attached Figure Description

[0012] Figure 1This is a schematic diagram of the long-distance coal seam drilling plasma ignition gasification control system of the present invention;

[0013] Figure 2 This is a flowchart of the method for cleaning silt deposits on the borehole wall according to the present invention. Detailed Implementation

[0014] 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.

[0015] This application provides a long-distance coal seam drilling plasma ignition gasification control system. The system's execution entities include, but are not limited to, underground gasification control platforms, in-situ coal seam conversion systems, plasma gasification devices, and remote drilling operation systems, which can be considered as general control nodes in this application. The gasification control system includes, but is not limited to, at least one of a plasma power controller, a medium injection control unit, and a drilling propulsion actuator.

[0016] Please see Figure 1 In this embodiment of the invention, the long-distance coal seam drilling plasma ignition gasification control system includes:

[0017] The feature extraction module is used to acquire the arc characteristic signals of the plasma torch in real time during its operation within the coal seam borehole. It extracts the arc voltage mutation rate and current ripple ratio from these signals and constructs a high-frequency disturbance component sequence based on them. The arc characteristic signals directly reflect the operating state of the plasma torch and contain rich operational information. The arc voltage mutation rate reflects the arc stability and the abrupt changes in the dielectric environment, while the current ripple ratio characterizes the fluctuation degree and energy transfer efficiency of the discharge process. High-frequency sampling technology is used to acquire the anode voltage and cathode current signals in real time, with the sampling frequency typically set to 10-50kHz to ensure the capture of transient arc changes. The arc voltage mutation rate is obtained through differential calculation of adjacent sampling points, and the current ripple ratio is quantified by the ratio of peak to trough values. The orthogonal fusion of these two parameters forms a high-frequency disturbance component sequence, providing a multi-dimensional feature basis for subsequent operational condition identification.

[0018] The working condition identification module identifies the current working condition state within a coal seam borehole based on the frequency domain distribution characteristics of high-frequency disturbance component sequences, and calculates the corresponding working condition confidence level. The current working condition states include normal gasification, water intrusion, and borehole wall siltation. This module employs frequency domain analysis technology, converting the time-domain signal into a frequency domain representation through Fourier transform, and extracting two key indicators: the proportion of low-frequency energy and the density of high-frequency spikes. Under normal gasification, the electric arc is stable, and the spectrum shows concentrated low-frequency energy and sparse high-frequency spikes. Under water intrusion, liquid water contacting the high-temperature electric arc triggers violent evaporation, leading to a significant increase in low-frequency energy. Under borehole wall siltation, the airflow channel is obstructed, enhancing the interaction between the electric arc and the borehole wall, generating a large number of high-frequency spike signals. By setting energy and density thresholds, the three working conditions are automatically distinguished. The working condition confidence level is obtained through probability distribution normalization, reflecting the reliability of the working condition determination and providing a decision-making basis for the execution of subsequent control strategies.

[0019] The medium control module is used to determine the level of liquid water intrusion based on the operating condition confidence level when the current operating condition is a water intrusion state and the operating condition confidence level is greater than a preset confidence threshold. It then adjusts the working medium injection strategy of the plasma torch according to the level of liquid water intrusion, gradually switching the injected medium from the initial gaseous medium to water vapor medium. Simultaneously, it triggers an overenthalpy compensation mode to increase the arc power density of the plasma torch until the arc characteristic signal indicates that the liquid water has completed in-situ self-evaporation. The core function of this module is to address the interference of coal seam fracture water intrusion on the plasma gasification process. Liquid water intrusion can rapidly cool the arc, lower the gasification temperature, and even cause arc extinction. By gradually switching the working medium to water vapor, utilizing the high specific heat capacity and chemical reactivity of water vapor, it can maintain arc stability while promoting rapid evaporation of liquid water. The overenthalpy compensation mode increases the arc power density by increasing the discharge current, compensating for the heat absorbed by water evaporation and ensuring that the gasification temperature is maintained within an effective range. The medium switching adopts a gradual strategy, increasing the water vapor ratio step by step according to a preset step size to avoid arc instability caused by sudden changes in the medium. By monitoring changes in arc impedance, the switching rate and power compensation amplitude are dynamically adjusted to achieve adaptive control of the water inrush condition.

[0020] The silt removal module, when the current operating condition is that the borehole wall is silted up, estimates the siltation blockage distance based on the phase delay characteristics in the high-frequency disturbance component sequence. Based on this blockage distance, it generates airflow pulsation commands and modulates the instantaneous velocity profile of the working medium to form a local jet scouring wave at the plasma torch nozzle to remove the silt from the borehole wall. This module solves the problem of airflow channel blockage caused by coal dust and ash silt accumulation on the borehole wall during long-distance borehole gasification. The presence of silt not only reduces gasification efficiency but can also cause local overheating and arc deviation. By analyzing the phase difference between the voltage and current disturbance components and combining it with the propagation characteristics of sound waves in the medium, the distance between the silt and the plasma torch nozzle can be accurately estimated. Based on the blockage distance, the system automatically calculates the optimal pulsation frequency and amplitude. A larger pulsation amplitude is needed for a greater siltation distance to generate a sufficiently strong shock wave, while a higher pulsation frequency is used for a closer siltation distance to enhance the removal effect. The airflow pulsation command is sent to the medium injection valve group, and the working medium flow is periodically cut off and released by rapidly opening and closing the valve. A jet scouring wave with a specific frequency is generated at the nozzle, which effectively removes the deposits on the orifice wall by utilizing the fluid dynamics effect and restores the airflow channel.

[0021] The predictive control module constructs a model to predict the movement of the gasification face based on arc characteristic signals, real-time consumption parameters of the working medium, and current operating conditions. Based on this model, it outputs power adjustment and axial feed control commands for the plasma torch to maintain a dynamic anchoring distance between the gasification face and the torch nozzle. This module is the core control component for achieving stable and efficient gasification. The gasification face is the leading edge of the coal seam being gasified by the plasma torch, and its movement rate is affected by multiple factors, including arc power, medium flow rate, coal seam properties, and operating conditions. The predictive model, based on the principle of energy conservation and combined with coal seam thermal properties, calculates the coal seam consumption volume per unit time to derive the theoretical movement rate. A correction coefficient is then applied based on the current operating conditions: the movement rate decreases under water intrusion conditions, is uneven under borehole wall siltation conditions, and is stable under normal gasification conditions. Through time-step integration, the predictive model can output the future position of the gasification face. The system compares the predicted position with the plasma torch nozzle position in real time and calculates the actual distance. When the distance deviates from the dynamic anchoring distance range, it automatically generates power adjustment and axial feed control commands. When the distance is too small, the power is reduced and the plasma torch is moved backward. When the distance is too large, the power is increased and the plasma torch is moved forward, ensuring that the gasification process takes place within the optimal distance range and guaranteeing gasification efficiency and plasma torch safety.

[0022] The modules are connected via wired and / or wireless means to enable data transmission between them.

[0023] In this embodiment of the invention, the detailed implementation steps of real-time acquisition of the arc characteristic signal of the plasma torch, extraction of the arc voltage mutation rate and current ripple ratio from the arc characteristic signal, and construction of a high-frequency perturbation component sequence based on the arc voltage mutation rate and current ripple ratio include:

[0024] The anode voltage and cathode current signals of the plasma torch are acquired synchronously at a preset sampling frequency. Synchronous acquisition is a fundamental step to ensure accurate feature extraction. A dedicated data acquisition card is used to achieve multi-channel synchronous sampling, eliminating errors caused by time deviations. The preset sampling frequency is determined based on the plasma torch's operating frequency and arc fluctuation characteristics, typically set to 20-50 times the operating frequency. For a typical operating frequency of 50-100Hz, a sampling frequency of 10-50kHz is selected. The anode voltage signal is acquired through a high-voltage differential probe, and the cathode current signal is measured using a Hall current sensor. Both signals are amplified and filtered by a signal conditioning circuit before being converted into digital signals by a high-speed ADC. Synchronous acquisition ensures a strict correspondence between the voltage and current signals on the time axis, providing a reliable foundation for subsequent orthogonal fusion.

[0025] The absolute difference between adjacent sampling points of the anode voltage signal is calculated, and these absolute differences are arranged in a time series to form an arc voltage change rate sequence. Differential calculation is a classic method for extracting signal change rates; by quantifying the voltage variation amplitude between adjacent time points, it directly reflects the transient fluctuation characteristics of the arc. The calculation process involves the acquired voltage signal sequence... Calculate the difference between adjacent points ,in The absolute value of the difference eliminates the influence of the direction of voltage change and uniformly represents the intensity of the fluctuation. Arranging the difference values ​​in chronological order of sampling time forms an arc voltage mutation rate sequence. The statistical characteristics of this sequence directly reflect the arc stability. A high mutation rate indicates that the arc is subjected to external interference or changes in the dielectric environment, which is an important indicator of abnormal operating conditions.

[0026] The peak and trough values ​​of current fluctuations are extracted from the cathode current signal, and the ratio of the peak to trough values ​​is calculated to obtain the current ripple ratio sequence. The current ripple ratio is a key parameter for evaluating discharge quality, reflecting the relative amplitude of current fluctuations. The extraction process first applies a sliding window to the current signal, with the window length typically set to one duty cycle. Within each window, the maximum value is identified as the peak current fluctuation. The minimum value is taken as the valley value of current fluctuation. The formula for calculating the current ripple ratio is:

[0027] ;

[0028] A ripple ratio closer to 1 indicates a more stable current, while a ratio significantly greater than 1 indicates severe current fluctuations. Arranging the ripple ratios of each window in chronological order creates a current ripple ratio sequence. This sequence is sensitive to the flow state of the medium and the interaction characteristics between the electric arc and the coal seam. Water intrusion exacerbates current fluctuations and increases the ripple ratio, while siltation on the borehole wall leading to unstable airflow can also cause abnormal ripple ratios.

[0029] The arc voltage mutation rate and current ripple ratio within the same time window are orthogonally fused to generate a high-frequency disturbance component sequence. Orthogonal fusion is an effective method for integrating multi-dimensional features, comprehensively reflecting the complex dynamic characteristics of the arc by constructing an orthogonal feature space. The fusion process first aligns the arc voltage mutation rate sequence and the current ripple ratio sequence in time to ensure data correspondence within the same time window; then, the two sequences are normalized to eliminate dimensional differences and map them to a unified [0, 1] interval; finally, the high-frequency disturbance component is generated using a vector synthesis method, calculated as follows:

[0030] ;

[0031] in, For a moment High-frequency disturbance components. This represents the normalized arc voltage mutation rate. This is the normalized current ripple ratio. The weighting coefficient, typically set to 0.5-0.7, reflects the dominant role of voltage characteristics. The high-frequency disturbance component sequence integrates fluctuation information from both voltage and current dimensions, comprehensively reflecting the operational disturbance state of the plasma torch and providing highly sensitive feature inputs for operational condition identification.

[0032] In this embodiment of the invention, the detailed implementation steps for identifying the current working condition state within a coal seam borehole based on the frequency domain distribution characteristics of the high-frequency perturbation component sequence and calculating the working condition confidence level corresponding to the current working condition state include:

[0033] A Fourier transform is performed on the high-frequency perturbation component sequence to extract the low-frequency energy ratio and high-frequency spike density. The Fourier transform is a core tool in frequency domain analysis, decomposing a time-domain signal into a superposition of different frequency components to reveal the signal's frequency structure characteristics. The transform process employs the Fast Fourier Transform (FFT) algorithm, performing a transform on a sequence of length... The spectrum is obtained by calculating the high-frequency perturbation component sequence. ,in Frequency index. The low-frequency band is defined as 0 to... (Typically 10% of the sampling frequency), the high-frequency band is defined as... (Typically 40% of the sampling frequency) to the Nyquist frequency. The low-frequency energy proportion is obtained by calculating the ratio of the sum of the low-frequency power spectral densities to the sum of the total power spectral densities, reflecting the main energy distribution of the signal; the high-frequency spike density is calculated by identifying the ratio of the number of spikes exceeding a threshold in the high-frequency spectrum to the frequency range, reflecting the high-frequency perturbation complexity of the signal. These two indicators characterize the frequency domain properties of the arc characteristic signal from two dimensions: energy distribution and frequency complexity.

[0034] When the proportion of low-frequency energy exceeds the first energy threshold and the density of high-frequency spikes is less than the first density threshold, the current operating condition is determined to be a water intrusion state. The frequency domain characteristics of the water intrusion state are a significant increase in low-frequency energy and relatively sparse high-frequency spikes. This is because the intense evaporation process caused by the contact arc between liquid water and the electric arc generates a large amount of low-frequency energy fluctuations, but the homogeneity of the water vapor medium is relatively good, resulting in fewer high-frequency disturbances. The determination rule is based on experimental calibration. The first energy threshold is typically set to 0.6-0.7, indicating that the proportion of low-frequency energy exceeds 60%-70%; the first density threshold is set to 50%-60% of the high-frequency spike density under normal operating conditions. When both conditions are met simultaneously, the system determines it to be a water intrusion state and triggers the corresponding medium control response. This determination rule has been verified by a large amount of field data and has high accuracy and reliability.

[0035] When the proportion of low-frequency energy is less than the first energy threshold and the density of high-frequency burrs is greater than the first density threshold, the current operating condition is determined to be orifice wall siltation. The frequency domain characteristics of orifice wall siltation are the opposite of water intrusion, characterized by a relatively low proportion of low-frequency energy and a significant increase in high-frequency burr density. This is because the silt blocks the airflow channel, leading to intensified airflow turbulence and enhanced interaction between the electric arc and the orifice wall, generating a large number of high-frequency disturbance signals. The first density threshold serves as an upper limit; when the high-frequency burr density exceeds this threshold and the proportion of low-frequency energy is low, it indicates that high-frequency disturbances become dominant, and the system determines it to be orifice wall siltation. Under this condition, the siltation cleaning module needs to be activated to clear the obstruction through airflow pulsation and restore normal vaporization conditions. The judgment rule has also been verified in the field and has a good correspondence with actual operating conditions.

[0036] Based on the offsets of the low-frequency energy proportion and high-frequency burr density relative to the baseline state, a probability distribution corresponding to the offset is calculated through normalization. The maximum probability value in the probability distribution is determined as the operating condition confidence level. The operating condition confidence level is a key indicator of the reliability of quantitative operating condition determination, reflecting the degree of matching between the current frequency domain characteristics and typical operating condition characteristics. The calculation process first determines the baseline low-frequency energy proportion under normal gasification conditions. and reference high-frequency band burr density This is obtained through historical data statistics; then the offset of the current state is calculated. and ;in, This represents the proportion of the low-frequency power spectral density to the total power spectral density after the high-frequency perturbation component sequence has undergone Fourier transform at the current moment. This is the ratio of the number of peaks exceeding a set threshold in the high-frequency spectrum to the frequency range after Fourier transform of the high-frequency disturbance component sequence at the current moment. The high-frequency burr density offset represents the deviation of the high-frequency burr density under the current operating condition from the baseline state, reflecting the complexity and severity of the high-frequency arc disturbance. The offset is then normalized and mapped to the [0, 1] interval. Finally, based on the typical offset characteristics of the three operating conditions, a Gaussian probability model is used to calculate the probability that the current offset belongs to each operating condition, and the maximum probability value is selected as the operating condition confidence level. When the operating condition confidence level is greater than a preset confidence threshold (usually 0.7-0.8), the operating condition judgment result is reliable, and the system executes the corresponding control strategy; when the confidence level is low, the system remains in an observation state, accumulating more data before making a judgment, avoiding unnecessary control actions caused by misjudgment.

[0037] In this embodiment of the invention, the detailed implementation steps of adjusting the working medium injection strategy of the plasma torch according to the liquid water intrusion level, gradually switching the injection medium from the initial gaseous medium to the water vapor medium, and simultaneously triggering the overenthalpy compensation mode to improve the arc power density of the plasma torch include:

[0038] The target water vapor percentage is determined based on the level of liquid water intrusion. The proportion of water vapor in the injected medium is gradually increased according to a preset step size until the target water vapor percentage is reached. The level of liquid water intrusion is comprehensively evaluated based on the operating condition confidence level and the incremental increase in the low-frequency energy percentage, and is divided into three levels: light intrusion, moderate intrusion, and heavy intrusion, with corresponding target water vapor percentages set at 30%, 50%, and 70%, respectively. A gradual strategy is adopted for medium switching to avoid arc instability caused by abrupt changes. The preset step size is typically 5%-10%, and the switching cycle is 2-5 seconds. During the switching process, the flow rates of the gaseous medium and water vapor medium are precisely adjusted through proportional control valves to gradually increase the water vapor percentage. The introduction of water vapor medium maintains the stability of the arc plasma and promotes the rapid evaporation of liquid water through its high specific heat capacity and chemical activity. Simultaneously, water vapor participates in the gasification reaction to generate hydrogen-rich syngas, improving the quality of the gasification products. Gradual switching ensures a smooth transition of the medium environment, ensuring stable operation of the plasma torch throughout the adjustment process.

[0039] After each increase in the proportion of water vapor medium, the change in arc impedance in the arc characteristic signal is monitored. Arc impedance is a comprehensive reflection of the conductivity characteristics of the arc plasma and is closely related to the medium composition, temperature, and pressure. The monitoring process obtains the arc impedance in real time by calculating the ratio of arc voltage to arc current, and then compares it with the reference impedance value before the switch to obtain the change in arc impedance. Increasing the proportion of water vapor medium changes the plasma composition, which usually leads to an increase in arc impedance because water vapor molecules have a higher ionization energy. The change in arc impedance is a key indicator for assessing the impact of medium switching on the arc. Real-time monitoring can promptly detect abnormal impedance fluctuations, providing a basis for subsequent compensation control. The monitoring frequency is synchronized with the medium switching step size to ensure accurate impedance feedback after each adjustment.

[0040] If the arc impedance change exceeds the preset impedance stability range, the increase in the proportion of water vapor medium is paused, and the discharge current of the plasma torch is simultaneously increased to trigger the over-enthalpy compensation mode, causing the arc impedance change to fall back to the preset impedance stability range. The preset impedance stability range is determined based on the plasma torch's design parameters and medium characteristics, typically set to ±15% of the reference impedance value. This range ensures the arc remains within a stable operating range. When the impedance change exceeds this range, it indicates that the medium switching speed is too fast or the water vapor proportion is too high, threatening arc stability. The system automatically pauses medium proportion adjustment. Simultaneously, the over-enthalpy compensation mode is triggered, increasing the discharge current through the power controller to increase the input arc power, compensating for the energy absorbed by water vapor evaporation and ionization, and increasing the arc power density and temperature. The discharge current increase is dynamically calculated based on the impedance offset, typically 10%-30% of the reference current. The core of the over-enthalpy compensation mode is to maintain arc temperature and stability by increasing energy input, ensuring effective vaporization even under high water vapor proportion conditions. Impedance closed-loop control ensures that the arc always operates within a safe and stable range, avoiding the risk of arc extinction or overload.

[0041] In this embodiment of the invention, the detailed implementation steps until the arc characteristic signal indicates that the liquid water has completed in-situ self-evaporation include:

[0042] During operation in the overenthalpy compensation mode, the arc voltage fluctuation variance is continuously extracted from the arc characteristic signal. Arc voltage fluctuation variance is a statistical indicator for evaluating arc stability, reflecting the degree of dispersion of the arc voltage around its average value. The extraction process calculates the arc voltage variance value within a continuous time window (typically 5-10 seconds), using the following formula:

[0043] ;

[0044] in, This represents the variance of the arc voltage fluctuation. The number of sampling points within the time window. For the first Voltage values ​​at each sampling point The average voltage is represented by the average voltage. A smaller fluctuation variance indicates a more stable arc. The presence of liquid water causes violent arc fluctuations, significantly increasing the variance. As the liquid water gradually evaporates, the arc environment stabilizes, and the variance gradually decreases. Continuous monitoring of the arc voltage fluctuation variance allows for real-time assessment of the evaporation process, providing a quantitative basis for determining the completion of evaporation.

[0045] When the variance of arc voltage fluctuation remains below the variance convergence threshold for a continuous preset time period, and the arc voltage mutation rate falls back to the reference voltage mutation rate range, it is determined that the liquid water has completed in-situ self-evaporation. The variance convergence threshold is set to 1.2-1.5 times the variance of arc voltage fluctuation under normal vaporization conditions, and the preset time period is typically 15-30 seconds to ensure the stability of the judgment results and avoid misjudgments caused by instantaneous fluctuations. The arc voltage mutation rate falling back to the reference voltage mutation rate range is an auxiliary judgment condition. The reference voltage mutation rate range is determined through statistical analysis of historical data under normal operating conditions and represents the voltage change characteristics under conditions without water inrush interference. When both conditions are met simultaneously, it indicates that the arc environment has stabilized, the liquid water has completely evaporated or been discharged, and the vaporization process can return to normal mode. This judgment method is based on multi-dimensional verification of arc characteristics, has high accuracy and reliability, and effectively avoids the limitations of single-index judgment.

[0046] After determining that the liquid water has completed in-situ self-evaporation, the proportion of water vapor medium is gradually reduced in reverse order according to a preset step size, and the discharge current is restored to the reference current value before compensation. Medium retreat and power recovery are the final stages of the water inrush response process, ensuring a smooth transition back to normal operation. The reduction of the water vapor medium proportion follows the same step size as the lifting process but in reverse, gradually increasing the initial gaseous medium proportion and decreasing the water vapor proportion until the medium ratio under normal operating conditions is restored (usually pure gaseous medium or a small amount of water vapor). Simultaneously, the discharge current is adjusted in reverse according to the trajectory during lifting, gradually reducing to the reference current value before compensation to avoid arc instability caused by sudden power drops. The entire recovery process employs the same closed-loop control strategy as the adjustment process, monitoring arc impedance and voltage fluctuations in real time to ensure a smooth transition. After recovery, the system returns to normal gasification state, continuing to monitor changes in operating conditions to prepare for possible recurrence of anomalies. This adaptive control process achieves a complete response to water inrush conditions, from detection and identification to proactive response and stable recovery, forming a closed-loop management system that significantly improves the adaptability and reliability of the plasma gasification system in complex coal seam environments.

[0047] like Figure 2The diagram shows a flowchart of a method for cleaning deposits on the borehole wall. In this embodiment of the invention, the detailed implementation steps include: estimating the deposit blockage distance based on the phase delay characteristics in the high-frequency disturbance component sequence; generating an airflow pulsation command based on the deposit blockage distance; and modulating the instantaneous velocity profile of the working medium based on the airflow pulsation command to form a local jet scouring wave at the plasma torch nozzle to remove deposits from the borehole wall.

[0048] The phase difference between the voltage and current disturbance components in the high-frequency disturbance component sequence is extracted. Based on the phase difference and the propagation speed of sound in the medium, the obstruction distance is calculated. Phase delay is a physical method for estimating obstacle distance using the propagation characteristics of arc disturbance signals in airflow media. When obstruction exists on the orifice wall, the airflow channel is blocked, causing pressure fluctuations. These fluctuations propagate in the medium at the speed of sound and affect the arc characteristics, resulting in a phase difference between the voltage and current disturbances. The phase difference is extracted using the Hilbert transform method, calculating the instantaneous phases of the voltage and current disturbance components separately, and then obtaining the phase delay by calculating the difference. The propagation speed of sound waves in a vaporized medium Determined based on the medium temperature and composition, for typical vaporization temperatures of 800-1200℃, the propagation speed is approximately 600-800 m / s. (The remaining text appears to be unrelated and refers to a different topic: "Accumulation and blockage distance.") Calculated using phase delay and propagation rate:

[0049] ;

[0050] in, The dominant frequency of the disturbance signal is used. This method converts the phase characteristics of the arc signal into spatial distance information, enabling non-contact ranging of obstacles within the hole and providing location information for precise clearing.

[0051] The pulsation frequency and amplitude are determined based on the distance to the sludge deposit. The sludge deposit distance is negatively correlated with the pulsation frequency, and positively correlated with the pulsation amplitude. Pulsation parameter design is crucial for airflow scouring and cleaning; pulsation characteristics must be optimized according to the location of the sludge deposit to achieve the best cleaning effect. The pulsation frequency determines the number of impacts of the scouring wave. Closer sludge deposits can be cleaned with a higher frequency for rapid, multiple impacts, while farther deposits require a lower frequency to ensure that the energy attenuation during wave propagation is not excessive. Pulsation frequency With blocking distance The relationship is:

[0052] ;

[0053] in, This is the frequency coefficient (typically 50-100 Hz·m). The reference distance is approximately 1 meter. The amplitude of the pulsation determines the intensity of the scour wave; the greater the distance, the larger the initial disturbance is required to maintain sufficient impact force after propagation. Pulsation amplitude With blocking distance The relationship is ,in This is the amplitude coefficient (typically 0.3-0.5, representing the relative magnitude of flow rate changes). This distance-adaptive pulsation parameter design ensures the targeted and effective cleaning action, avoiding insufficient cleaning or energy waste caused by fixed parameters.

[0054] The pulsation frequency and amplitude are encoded into airflow pulsation commands, which are then sent to the media injection valve assembly. Command encoding is the process of converting physical parameters into control signals, employing a standardized communication protocol to achieve reliable interaction between the control system and the actuator. The pulsation command includes parameters such as pulsation frequency, pulsation amplitude, pulsation duration, and pulsation waveform type, encoded as a digital command packet and sent to the media injection valve assembly via an industrial bus (such as CAN or Modbus). The media injection valve assembly contains fast-response solenoid valves or proportional valves capable of precisely controlling the flow rate of the working medium according to the commands. Command transmission employs a closed-loop feedback mechanism; after the valve assembly executes its action, it transmits back actual flow data. The control system compares the command with the feedback, making corrections as necessary to ensure accurate implementation of the pulsation parameters.

[0055] The media injection valve assembly responds to airflow pulsation commands, periodically cutting off and releasing the flow rate of the working medium to generate a jet scouring wave with a pulsating frequency in the instantaneous flow velocity profile. This jet scouring wave acts on the deposits on the orifice wall. Valve assembly execution is the physical realization of the cleaning action, achieving periodic flow modulation through rapid valve opening and closing. When the valve closes rapidly, the flow of the working medium is cut off, and the pressure at the nozzle drops instantaneously; when the valve opens rapidly, the accumulated medium is released, and the flow velocity at the nozzle increases sharply, forming a jet scouring wave. The jet wave propagates forward at the medium flow velocity (typically 50-150 m / s). Upon reaching the deposit location, the impact force acts on the surface of the deposit layer, peeling away loose coal dust and ash through shear stress and pressure pulsation. The pulsation frequency determines the interval of the scouring wave; continuous fluctuations create a resonance effect, enhancing the cleaning capability. The pulsation duration is set according to the degree of deposit accumulation: 10-20 seconds for light deposits and 30-60 seconds for heavy deposits. During the cleaning process, the high-frequency disturbance component sequence is continuously monitored. When the phase delay characteristics return to normal and the high-frequency spike density decreases, it indicates that the deposits have been effectively removed, and the system automatically stops pulsating and resumes normal medium supply. This active cleaning mechanism avoids complete channel blockage caused by continuous accumulation of deposits, ensuring the continuous and stable operation of the long-distance borehole gasification process.

[0056] In this embodiment of the invention, the detailed implementation steps for constructing a prediction model for the movement of the gasification working face based on arc characteristic signals, real-time consumption parameters of the working medium, and the current operating condition include:

[0057] The effective thermal power of the electric arc is determined based on its characteristic signals, and the real-time flow rate and component ratio of the working medium are obtained as input parameters for the gasification reactants. The effective thermal power of the electric arc is the actual heat energy transferred to the coal seam for the gasification reaction, excluding heat loss from the arc to the surrounding environment. The determination process first calculates the arc input power. ,in Arc voltage The arc current is used; then, based on the thermal efficiency of the plasma torch... (Typically 0.6-0.8) Calculate the effective heat power The real-time flow rate of the working medium is measured by a mass flow meter and converted into volumetric flow rate. The component ratios, including the proportions of gaseous and water vapor media, are obtained through the settings of the media control module. These parameters collectively determine the material and energy inputs for the gasification reaction and are the fundamental data for calculating the shift rate.

[0058] By combining the thermal properties of the coal seam and using the energy conservation equation to calculate the coal seam consumption volume per unit time, the theoretical advance rate of the gasification face is obtained. The thermal properties of the coal seam include density. Specific heat capacity Heat of gasification reaction (Endothermic reaction, usually positive) and initial temperature The energy conservation equation is based on the following principle: the effective heat power of the electric arc is used to heat the coal seam to the gasification temperature. It also provides the heat of gasification reaction, and the volume of coal seam consumed per unit time. satisfy:

[0059] ;

[0060] The volume of coal seam consumed per unit time is:

[0061] ;

[0062] Assume the gasification working face has a circular cross-section with a radius equal to the borehole radius. Then the theoretical shift rate for:

[0063] ;

[0064] The theoretical shift rate is based on ideal gasification conditions and does not take into account the influence of actual operating conditions, so it needs further correction.

[0065] A correction factor is applied to the theoretical advance rate of the gasification face based on the current operating conditions. The first correction factor corresponds to the water intrusion state, the second to the borehole wall siltation state, and the third to the normal gasification state. These correction factors reflect the impact of different operating conditions on gasification efficiency and are determined through field experiments and data fitting. Under the water intrusion state, the evaporation of liquid water absorbs a large amount of heat, reducing the effective energy used for coal seam gasification. The first correction factor... Typically, it is 0.5-0.7, indicating a 30%-50% reduction in the migration rate. Under conditions of pore wall siltation, obstructed airflow channels lead to uneven medium distribution and insufficient vaporization in some areas. The second correction factor... Typically, it is 0.6-0.8, and the spatial uniformity of the migration rate decreases. Under normal gasification conditions, the system operates at its design conditions, and the third correction factor... The value is typically 0.9-1.0, close to the theoretical value. The corrected migration rate is... ,in The appropriate correction coefficient is selected based on the current operating conditions. This correction mechanism enables the prediction model to adapt to complex changes in actual operating conditions, thereby improving prediction accuracy.

[0066] The corrected theoretical migration rate of the gasification working face is integrated over a time step to generate a migration prediction model for the gasification working face. This model is used to output the predicted position of the gasification working face after the current moment. Time integration is a mathematical process that transforms instantaneous velocity into position change, using a discrete time step. Numerical integration is performed (typically 1-5 seconds). Within each time step, the transition rate is assumed to be constant. Then the displacement increment is Accumulation starts from the initial time. up to the current moment The predicted position of the gasification working face is obtained by calculating all displacement increments. ,in This is the initial position. The time step is used. The prediction model employs a sliding window mechanism to continuously update the latest migration rate and operating conditions, maintaining real-time prediction. The prediction model not only outputs the current predicted position but can also extrapolate the position trajectory in the short term (e.g., 30 seconds to 2 minutes), providing a basis for forward-looking control. This migration prediction model is the core of achieving dynamic coordination between the plasma torch and the gasification working face, ensuring that the gasification process operates within optimal efficiency and safety limits.

[0067] In this embodiment of the invention, the detailed implementation steps for outputting the power adjustment amount and axial feed control command of the plasma torch based on the shift prediction model to maintain a dynamic anchoring distance between the gasification working surface and the nozzle of the plasma torch include:

[0068] The current predicted position of the gasification face and the current position of the plasma torch nozzle are obtained, and the actual distance between them is calculated. The predicted position of the gasification face is output by the traverse prediction model, representing the position coordinates of the coal seam gasification front interface along the borehole axis. The current position of the plasma torch nozzle is obtained in real time by a position sensor (such as an encoder or laser rangefinder), representing the axial position of the plasma torch within the borehole. Actual distance Calculated as the difference between two position coordinates, i.e. ;in, The coordinates of the gasification working face are the positions of the coal seam gasification front interface (gasification working face) in the borehole axial coordinate system. The coordinates of the plasma torch nozzle position are: the current position of the plasma torch nozzle in the borehole axial coordinate system, and... The same coordinate system is used. This spacing is a key parameter for evaluating the rationality of the gasification process configuration. Too small a spacing may cause the plasma torch to overheat and be damaged, while too large a spacing will reduce gasification efficiency and temperature, affecting product quality. Real-time calculation of the actual spacing provides feedback signals for dynamic control.

[0069] The actual spacing is compared with the preset dynamic anchoring distance range. When the actual spacing is less than the minimum value of the dynamic anchoring distance range, a first axial feed command is generated to control the plasma torch to retreat along the borehole extension direction, and a command to reduce the power adjustment is output. The dynamic anchoring distance range is determined according to the plasma torch performance, coal seam characteristics, and gasification process requirements, and is usually set to 0.5-2.0 meters, with a minimum of about 0.5 meters to ensure a safety margin and a maximum of about 2.0 meters to ensure gasification efficiency. When the actual spacing is less than the minimum value (e.g., less than 0.5 meters), it indicates that the gasification working face is moving too slowly or the plasma torch is moving too fast, and the distance between the two is too close, posing a risk of overheating and mechanical collision. The system automatically generates a first axial feed command to control the plasma torch to retreat along the borehole extension direction, increasing the safety distance. The retreat speed is set according to the spacing deviation, usually 1-5 cm / s, to ensure smooth adjustment. At the same time, a command to reduce the power adjustment is output to reduce the arc heat power, reduce the gasification rate, and slow down the working face movement, thereby increasing the spacing from two aspects and restoring it to the anchoring range.

[0070] When the actual distance exceeds the maximum value of the dynamic anchoring distance range, a second axial feed command is generated to control the plasma torch to advance along the borehole extension direction, and a command to increase the power adjustment is output until the actual distance falls within the dynamic anchoring distance range. When the actual distance exceeds the maximum value (e.g., greater than 2.0 meters), it indicates that the gasification working face is moving too fast or the plasma torch is moving too slowly, resulting in a large distance between them, a decrease in gasification temperature and efficiency, and an impact on product quality. The system automatically generates a second axial feed command to control the plasma torch to advance along the borehole extension direction, reducing the distance. The advancing speed is also set according to the distance deviation, typically 1-5 cm / s. Simultaneously, a command to increase the power adjustment is output to increase the arc thermal power, accelerate the gasification rate, and speed up the working face advancement, thereby reducing the distance from both aspects. This bidirectional adjustment mechanism forms a negative feedback closed-loop control, automatically maintaining the actual distance within the dynamic anchoring distance range. The control algorithm uses a PID controller to calculate the optimal feed speed and power adjustment based on the distance deviation, achieving rapid response and stable control. Once the actual spacing falls within the anchoring range, the system maintains its current configuration, continues monitoring, and is ready to adjust at any time to ensure that the gasification process always operates under optimal conditions. This predictive control module achieves dynamic coordination between the plasma torch and the gasification face, and is the core guarantee for the stable and efficient operation of long-distance coal seam borehole gasification.

[0071] In this embodiment of the invention, during the operation of the plasma torch within the coal seam borehole, the following steps are also included:

[0072] When the current operating condition is normal vaporization and no airflow pulsation command or over-enthalpy compensation mode is triggered, periodic micro-interruption power outages are inserted. Micro-interruption control is a proactive maintenance step to extend equipment life, achieving electrode cooling and condition assessment through brief power outages. The control process first determines whether the current state is normal vaporization and operating without abnormal handling modes; if the conditions are met, a periodic power outage timer is started, typically set to insert a micro-interruption period every 30-60 minutes of operation; when the timer is triggered, a power outage command is generated to stop the arc discharge of the plasma torch, with a power outage duration typically 10-30 seconds. This periodic interruption mechanism provides a regular opportunity for thermal stress release for the plasma torch operating under high loads, effectively delaying electrode ablation and insulation aging.

[0073] It should be noted that the micro-interruption period is implemented through a dual-layer timing control architecture, which includes two independent components: a periodic trigger timer and a power-off duration timer. The periodic trigger timer sets the frequency of micro-interruption events, typically configured to trigger a micro-interruption request every 2-5 minutes of operation. The specific period value is dynamically adjusted based on the plasma torch's rated power and current load rate: a shorter period (2-3 minutes) is used during high-power, high-load operation to increase cooling frequency; a longer period (4-5 minutes) is used during medium- and low-power operation to reduce interference with gasification continuity. When the periodic trigger timer expires, the system first performs a safety condition check to confirm that the current operating condition is normal gasification, there are no abnormalities such as water intrusion or orifice wall siltation, and it is not in an emergency mode such as over-enthalpy compensation or airflow pulsation. Only when all safety conditions are met will the power-off action be actually executed. The power outage duration timer controls the duration of a single micro-interruption, with a standard setting of 2-5 seconds. The specific duration is adaptively adjusted based on real-time monitoring data of the electrode temperature: if the electrode temperature approaches the material's safety limit, the power outage duration is extended to 4-5 seconds; if the temperature is within the safe range, the standard duration of 2-3 seconds is used. To avoid the negative impact of frequent power outages on the gasification reaction, the system is equipped with a minimum continuous operating time protection mechanism, stipulating that at least 120 seconds of continuous operating time must be maintained between two micro-interruption power outage events, while limiting the power outage duty cycle to no more than 3%-5%, ensuring that the micro-interruption mechanism does not significantly reduce the overall gasification efficiency.

[0074] During the intermittent power outage period, the arc discharge of the plasma torch is stopped, but the working medium is continuously injected at a reference flow rate. The flow of the working medium carries away the residual heat of the plasma torch body, achieving self-cooling. The intermittent power outage is an innovative strategy for plasma torch thermal management and lifespan extension. By briefly stopping the discharge, it releases the heat accumulated on the electrodes, reducing thermal stress and ablation rate. The power outage period is typically set to 2-5 seconds, with a cycle of 2-5 minutes, meaning a 2-5 second power outage is inserted every 2-5 minutes of operation. During the power outage, the power controller stops supplying power, the arc is extinguished, but the medium injection valve assembly maintains the continuous injection of the working medium at a reference flow rate (typically 50%-70% of the normal flow rate). The flowing working medium removes the residual heat from the electrodes and nozzles through convection heat exchangers, achieving rapid cooling. The selection of the reference flow rate ensures sufficient cooling while avoiding media waste caused by excessive flow. The self-cooling mechanism eliminates the need for additional water or air cooling systems, utilizing the working medium within the vaporization process itself for thermal management. This simplifies the system structure, improves reliability, and makes it particularly suitable for confined space applications in long-distance boreholes.

[0075] Based on the difference in arc re-breakdown voltage before and after a micro-intermittent power outage period in the plasma torch, the electrode wear status of the plasma torch is assessed, and the duration of the next micro-intermittent power outage period is dynamically adjusted according to the electrode wear status. The arc re-breakdown voltage is the voltage required for the plasma torch to reignite from a power outage state. This voltage is closely related to the electrode shape, gap, and surface condition, and is a sensitive indicator for assessing electrode wear. The stable operating voltage before the power outage is recorded during the assessment process. The re-breakdown voltage after power failure and re-ignition Calculate the difference When electrodes are new, their tips are sharp, resulting in low re-breakdown voltage and a small difference in voltage. As electrodes erode, the tips become blunt, the gap widens, the re-breakdown voltage increases, and the difference widens. By tracking the trend of this difference over a long period, the degree of electrode wear can be quantitatively assessed. When the difference exceeds a preset threshold (e.g., 1.5 times the initial difference), it indicates significant electrode wear, requiring adjustment of the cooling strategy. The dynamic adjustment strategy is as follows: the more severe the electrode wear, the more frequent the micro-intermittent power outages (shortening the cycle) or the longer the power outage duration, strengthening cooling protection and delaying further wear; conversely, when the electrode is in good condition, the power outage frequency can be reduced to improve operational continuity. This adaptive thermal management mechanism enables online assessment and active protection of electrode life, significantly extending the service life of the plasma torch, reducing maintenance costs, and improving the economics of long-distance borehole gasification operations.

[0076] In this embodiment of the invention, before the plasma torch operates within the coal seam borehole, the following steps are also included:

[0077] An initial gaseous medium is injected into the coal seam borehole, and the pressure of the initial gaseous medium is gradually increased to the breakdown preparation pressure. Medium pre-charging is a fundamental step in ignition preparation, creating conditions for arc breakdown by establishing an appropriate atmosphere and pressure. The pre-charging process first confirms that the borehole is well-sealed and has no leakage channels; then, the medium injection system is activated to inject the initial gaseous medium (usually an air or nitrogen mixture) into the borehole; simultaneously, the pressure inside the borehole is monitored and gradually increased to the breakdown preparation pressure (typically 0.1-0.3 MPa, higher than atmospheric pressure but not so high as to cause breakdown difficulties). Appropriate medium pressure increases gas density, reduces breakdown voltage, and simultaneously inhibits the diffusion of coal seam gas into the plasma torch region, creating favorable conditions for safe and controllable ignition.

[0078] Ignition voltage is applied in a stepped, incremental manner, and leakage current curves are monitored at each voltage level. Ignition startup is a critical step in plasma gasification, requiring the establishment of a stable arc channel within the coal seam medium. The stepped voltage increment method avoids equipment shock and coal seam damage caused by sudden voltage changes, employing a gradual pressurization strategy. The stepped voltage levels are typically set to increase by 10%-20% of the rated operating voltage, with each level maintained for 5-10 seconds, allowing sufficient time for system response and stabilization. At each voltage level, the leakage current between the electrode and the coal seam is monitored using a current sensor. This current reflects the conductivity characteristics of the coal seam medium and the breakdown process. The leakage current curve records the change in current over time and voltage, serving as a key basis for determining the breakdown readiness state.

[0079] When the leakage current curve shows a sudden jump and the jump amplitude continues to exceed the preset current jump threshold, the current step voltage level is recorded as the critical breakdown voltage of the coal seam. A sudden jump in leakage current is a characteristic signal that the coal seam medium is about to break down, indicating that the electric field strength is approaching the breakdown field strength and ionization channels are beginning to form inside the coal seam. The preset current jump threshold is determined based on the coal seam resistivity and borehole size, and is typically 2-3 times the steady-state current of the previous level. When the current jump amplitude continues to exceed this threshold (lasting longer than 1 second), it indicates that the ionization process is developing steadily, rather than being a transient disturbance. The voltage level recorded at this time is the critical breakdown voltage of the coal seam. This voltage is the minimum voltage required for the coal seam to break down under the current conditions, and it is a key parameter for subsequent energy density calculations.

[0080] The initial breakdown energy density is determined based on the ratio of the critical breakdown voltage of the coal seam to the borehole depth. When the initial breakdown energy density meets the preset ignition energy conditions, a full-power start-up command is output to activate the plasma torch, completing the ignition and gasification start-up process. The initial breakdown energy density reflects the breakdown voltage required per unit length of borehole and is a comprehensive indicator for evaluating whether the ignition conditions are met. The calculation formula is:

[0081] ;

[0082] in, The initial breakdown energy density, This refers to the borehole depth. The preset ignition energy conditions are determined based on the coal seam type and gasification process, and typically require... Within the range of 50-200 V / m, too low a voltage indicates difficulty in breakdown or abnormal conductivity of the coal seam, while too high a voltage indicates excessively high voltage and potential safety risks. When the calculated... When preset conditions are met, the system determines that ignition is feasible and outputs a full-power command. The power controller quickly boosts the voltage to the rated operating voltage and simultaneously increases the current to the rated value, establishing a stable high-temperature arc channel in the coal seam. The high temperature (3000-10000℃) generated by the arc rapidly ignites the coal seam, initiating the gasification reaction and producing combustible gas. Successful ignition is indicated by the arc voltage and current stabilizing within the operating range, and the continuous output of gasification products. This progressive ignition method avoids the high voltage surges and uncontrollability of traditional ignition methods. By dynamically adjusting the voltage in real-time monitoring of the coal seam response, it achieves safe and controllable ignition startup, laying the foundation for subsequent stable gasification.

[0083] This invention achieves fully automated intelligent control of the long-distance coal seam borehole plasma gasification process through feature extraction, operating condition identification, media control, silt removal, and predictive control. The adaptive control method of this invention can respond in real time to changes in the complex coal seam environment, effectively cope with abnormal operating conditions such as water intrusion and borehole wall siltation, and precisely maintain the optimal configuration between the plasma torch and the gasification face. This provides an efficient and stable technical solution for underground coal gasification, significantly improving the safety, continuity, and economy of the gasification process.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. 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.

[0085] It should be noted that all formulas in this manual are calculated by removing dimensions and taking their numerical values. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters and thresholds in the formulas are set by those skilled in the art according to the actual situation.

[0086] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A long-distance coal seam drilling plasma ignition gasification control system, characterized in that, include: The feature extraction module is used to collect the arc feature signal of the plasma torch in real time during the operation of the plasma torch in the coal seam borehole, extract the arc voltage mutation rate and current ripple ratio from the arc feature signal, and construct a high-frequency disturbance component sequence based on the arc voltage mutation rate and the current ripple ratio. The working condition identification module is used to identify the current working condition state in the coal seam borehole based on the frequency domain distribution characteristics of the high-frequency disturbance component sequence, and to calculate the working condition confidence level corresponding to the current working condition state, wherein the current working condition state includes normal gasification state, water inrush state, and borehole wall siltation state. The medium control module is used to determine the liquid water intrusion level based on the operating condition confidence level when the current operating condition is a water intrusion state and the operating condition confidence level is greater than a preset confidence threshold, and adjust the working medium injection strategy of the plasma torch according to the liquid water intrusion level, gradually switching the injection medium from the initial gaseous medium to the water vapor medium, and triggering the superenthalpy compensation mode to increase the arc power density of the plasma torch until the arc characteristic signal indicates that the liquid water has completed in-situ self-evaporation; The silt removal module is used to estimate the siltation and blockage distance based on the phase delay characteristics in the high-frequency disturbance component sequence when the current working condition is siltation on the borehole wall, generate an airflow pulsation command based on the siltation and blockage distance, and modulate the instantaneous flow velocity profile of the working medium based on the airflow pulsation command to form a local jet scouring wave at the plasma torch nozzle to remove the siltation on the borehole wall. The predictive control module is used to construct a prediction model of the gasification working face based on the arc characteristic signal, the real-time consumption parameters of the working medium and the current working condition, and output the power adjustment amount and axial feed control command of the plasma torch based on the prediction model.

2. The long-distance coal seam drilling plasma ignition gasification control system according to claim 1, characterized in that, The real-time acquisition of the arc characteristic signal of the plasma torch, extraction of the arc voltage mutation rate and current ripple ratio from the arc characteristic signal, and construction of a high-frequency perturbation component sequence based on the arc voltage mutation rate and current ripple ratio, including: The anode voltage signal and cathode current signal of the plasma torch are acquired synchronously at a preset sampling frequency. For the anode voltage signal, the absolute difference between adjacent sampling points is calculated, and the absolute difference values ​​are arranged in a time series to form the arc voltage mutation rate sequence; The peak and valley values ​​of current fluctuations are extracted from the cathode current signal, and the ratio of the peak to valley values ​​is calculated to obtain the current ripple ratio sequence. The arc voltage mutation rate and the current ripple ratio within the same time window are orthogonally fused to generate the high-frequency disturbance component sequence.

3. The long-distance coal seam drilling plasma ignition gasification control system according to claim 1, characterized in that, The process of identifying the current working condition within the coal seam borehole based on the frequency domain distribution characteristics of the high-frequency perturbation component sequence, and calculating the working condition confidence level corresponding to the current working condition, includes: Perform a Fourier transform on the high-frequency perturbation component sequence to extract the low-frequency energy ratio and the high-frequency spike density; When the low-frequency energy ratio is greater than the first energy threshold and the high-frequency burr density is less than the first density threshold, the current operating condition is determined to be a water intrusion state. When the low-frequency energy ratio is less than the first energy threshold and the high-frequency burr density is greater than the first density threshold, the current working condition is determined to be a hole wall accumulation state. Based on the offset of the low-frequency energy ratio and the high-frequency burr density relative to the baseline state, the probability distribution corresponding to the offset is calculated through normalization, and the maximum probability value in the probability distribution is determined as the confidence level of the operating condition.

4. The long-distance coal seam drilling plasma ignition gasification control system according to claim 1, characterized in that, The step of adjusting the working medium injection strategy of the plasma torch according to the liquid water intrusion level, and gradually switching the injection medium from the initial gaseous medium to the water vapor medium, while triggering the superenthalpy compensation mode to increase the arc power density of the plasma torch, includes: The target water vapor percentage is determined based on the liquid water intrusion level, and the proportion of the water vapor medium in the injection medium is gradually increased according to a preset step size until the target water vapor percentage is reached. After each increase in the proportion of the water vapor medium, the change in arc impedance in the arc characteristic signal is monitored; If the change in arc impedance exceeds the preset impedance stability range, the increase in the proportion of water vapor medium is paused, and the discharge current of the plasma torch is increased simultaneously to trigger the over-enthalpy compensation mode, so that the change in arc impedance falls back to the preset impedance stability range.

5. The long-distance coal seam drilling plasma ignition gasification control system according to claim 4, characterized in that, The process until the arc characteristic signal characterizes that the liquid water has completed in-situ self-evaporation includes: During the operation of the superenthalpy compensation mode, the arc voltage fluctuation variance in the arc characteristic signal is continuously extracted; When the variance of the arc voltage fluctuation is continuously lower than the variance convergence threshold for a preset period of time, and the arc voltage mutation rate falls back to the reference voltage mutation rate range, it is determined that the liquid water has completed in-situ self-evaporation. After determining that the liquid water has completed in-situ self-evaporation, the proportion of the water vapor medium is gradually reduced in reverse order according to the preset step size, and the discharge current is restored to the reference current value before compensation.

6. The long-distance coal seam drilling plasma ignition gasification control system according to claim 1, characterized in that, The process of estimating the siltation and blockage distance based on the phase delay characteristics in the high-frequency perturbation component sequence, generating an airflow pulsation command based on the siltation and blockage distance, and modulating the instantaneous velocity profile of the working medium based on the airflow pulsation command to form a local jet scouring wave at the plasma torch nozzle to strip away the deposits on the orifice wall includes: The phase difference between the voltage disturbance component and the current disturbance component in the high-frequency disturbance component sequence is extracted, and the siltation and blockage distance is calculated based on the phase difference and the propagation speed of sound waves in the medium. The pulsation frequency and amplitude are determined based on the aforementioned stagnation and blockage distance; The pulsation frequency and the pulsation amplitude are encoded into the airflow pulsation command, and the airflow pulsation command is sent to the medium injection valve group; The medium injection valve assembly responds to the airflow pulsation command by periodically cutting off and releasing the flow rate of the working medium to generate a jet scouring wave with the pulsation frequency in the instantaneous flow velocity profile, so that the jet scouring wave acts on the deposits on the orifice wall.

7. The long-distance coal seam drilling plasma ignition gasification control system according to claim 1, characterized in that, The method for constructing a prediction model for the movement of the gasification working face based on the arc characteristic signal, the real-time consumption parameters of the working medium, and the current operating condition includes: The effective thermal power of the current electric arc is determined based on the arc characteristic signal, and the real-time flow rate and component ratio of the working medium are obtained as input parameters for the gasification reactants. By combining the thermal properties of the coal seam, the volume of coal seam consumed per unit time is calculated, and the theoretical advance rate of the gasification working face is obtained. A correction coefficient is applied to the theoretical advancing rate of the gasification working face based on the current working condition, wherein the water intrusion state corresponds to the first correction coefficient, the borehole wall siltation state corresponds to the second correction coefficient, and the normal gasification state corresponds to the third correction coefficient. The modified theoretical migration rate of the gasification working face is integrated over a time step to generate a migration prediction model for the gasification working face.

8. The long-distance coal seam drilling plasma ignition gasification control system according to claim 7, characterized in that, The step-by-step prediction model outputs the power adjustment and axial feed control commands for the plasma torch, including: Obtain the current predicted position of the gasification working face and the current position of the plasma torch nozzle, and calculate the actual distance between them; The actual distance is compared with the preset dynamic anchoring distance range. When the actual distance is less than the minimum value of the dynamic anchoring distance range, a first axial feed command is generated to control the plasma torch to retreat along the drilling extension direction, and a command to reduce the power adjustment amount is output. When the actual spacing is greater than the maximum value of the dynamic anchoring distance range, a second axial feed command is generated to control the plasma torch to advance along the drilling extension direction, and a command to increase the power adjustment amount is output until the actual spacing falls within the dynamic anchoring distance range.

9. The long-distance coal seam drilling plasma ignition gasification control system according to claim 1, characterized in that, During the operation of the plasma torch within the coal seam borehole, the following is also included: When the current operating condition is normal vaporization and the airflow pulsation command or the over-enthalpy compensation mode is not triggered, micro-intermittent power outage periods are periodically inserted. During the micro-intermittent power outage period, the arc discharge of the plasma torch is stopped, but the working medium is continuously injected at a reference flow rate; Based on the difference in arc re-breakdown voltage of the plasma torch before and after the micro-intermittent power outage period, the electrode wear status of the plasma torch is evaluated, and the duration of the next micro-intermittent power outage period is dynamically adjusted according to the electrode wear status.

10. The long-distance coal seam drilling plasma ignition gasification control system according to claim 1, characterized in that, Before the plasma torch operates within the coal seam borehole, the following is also included: An initial gaseous medium is injected into the coal seam borehole, and the pressure of the initial gaseous medium is gradually increased to the breakdown preparation pressure. Ignition voltage was applied in a stepped manner, and leakage current curves were monitored at each voltage level. When the leakage current curve shows a sudden jump and the jump amplitude continues to exceed the preset current jump threshold, the current step voltage level is recorded as the critical breakdown voltage of the coal seam. The initial breakdown energy density is determined based on the ratio of the critical breakdown voltage of the coal seam to the borehole depth. When the initial breakdown energy density meets the preset ignition energy conditions, a full power input command is output to start the plasma torch and complete the ignition and gasification start-up process.

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