2019 Vol. 45, No. 5

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Mine exogenous fire identification method based on visible light and infrared image
SUN Jiping, SUN Yanyu, FAN Weiqiang
2019, 45(5): 1-5. doi: 10.13272/j.issn.1671-251x.17435
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Abstract:
Mine exogenous fire monitoring methods were analyzed, and a mine exogenous fire identification method based on visible light and infrared image was proposed. ① Mine exogenous fire monitoring methods based on sensors for temperature, smoke and others need to arrange multiple points, so cost is high, and maintenance workload is large. ② Mine exogenous fire monitoring method based on visible light image has advantages of large monitoring range, simple use, low cost, small influence by distance, high resolution ratio, rich color information, clear edge texture information, easy extraction of flame structure information, etc. But it is influenced greatly by cap-lamp lights, roadway lights and red objects. ③ Mine exogenous fire monitoring method based on infrared image has advantages of large monitoring range and simple use, and can monitor fire in case of low visibility with smoke or others. But monitoring distance, mine dust, ambient temperature or humidity and emissivity of object surface all affect temperature measurement. Close-range workers, incandescent lamps and electromechanical equipment will affect fire monitoring. ④ The mine exogenous fire identification method based on visible light and infrared image improves accuracy of fire identification. When both visible light image and infrared image identify fire, it is determined to be a fire, and a fire alarm signal is issued. When there is only a single visible light image or infrared image to identify fire, it is not determined to be a fire, and a suspected fire alarm signal is issued. ⑤ The feasibility of the mine exogenous fire identification method based on visible light and infrared image is verified by experiments.
Research status and prospect of coalfield fire monitoring technologies
ZHENG Xuezhao, JIA Yongxiao, GUO Jun, WEN Hu, WANG Baoyuan
2019, 45(5): 6-10. doi: 10.13272/j.issn.1671-251x.17404
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Research status of coalfield fire monitoring technologies was reviewed including electromagnetic detection method, resistivity method, radio wave method, geological radar method, gas measurement method, isotope radon measurement method, temperature method, remote sensing method and so on. Advantages and disadvantages of each technology were compared. It was pointed out that there were some questions existed in coalfield fire monitoring technologies at current such as lots of environmental factor limits, high cost, large technical limits and so on. Prospect of coalfield fire monitoring technology was taken out. It was pointed out that low altitude remote sensing technology of unmanned aerial vehicle equipped with an infrared thermal imager was development direction of coalfield fire monitoring technology. Moreover, development ideas were proposed which took high efficiency, intelligence and integration as leading role.
Research on characteristic of methane explosion induced by high-temperature source based on self-developed equipment
WANG Haiyan, ZHANG Lei, GUO Zengle
2019, 45(5): 11-15. doi: 10.13272/j.issn.1671-251x.17405
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Abstract:
A self-developed experimental system for high-temperature source-induced flammable gas explosion was used to simulate methane explosion induced by high-temperature source. Similarities and differences of methane explosion characteristic parameters between high-temperature source induction mode and electric spark induction mode were compared. The results show that methane explosion limit range under high-temperature source induction mode is 5.5%-14.5%, and that under electric spark induction mode is 5%-15.5%. It is more difficult for high-temperature source to detonate methane at explosion limit boundary. The methane explosion induced by electric spark has a more obvious temperature gradient than that induced by high-temperature source. The maximum explosion pressure of methane explosion induced by temperature source is higher than that induced by electric spark at different methane concentration. Methane concentration of the maximum explosion pressure under high-temperature source induction mode is 14.5%, while that under electric spark induction mode is 9.5% and 14.5%. Pressure boosting time of methane explosion induced by high-temperature source is larger than that induced by electric spark at each methane concentration.
Research on distribution law of production quantity of coal seam index gas in Pingdingshan No.10 Coal Mine
ZHU Yu, QIN Ruxiang, WU Canchun
2019, 45(5): 16-21. doi: 10.13272/j.issn.1671-251x.2018110053
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Abstract:
In view of problem of spontaneous combustion of VI-15, VI-16, VI-17 and VI-18 coal seams in Pingdingshan No.10 Coal Mine, temperature programmed oxidation experiment was used to analyze change of gas production quantity in each coal seam, and coal seam index gas were determined. Propane can be used as index gas of VI-15 coal seam, ethane can be used as index gas of VI-16 coal seam, and CO can be used as index gas of VI-17 and VI-18 coal seam. The experimental data were imported into Matlab software for curve fitting, so as to obtain fitting relationship equation between production quantity of index gas and temperature of coal seam. Temperature and production quantity of index gas of coal seam in different periods were measured through drilling holes arranged on site. The temperature measurement data were substituted into the fitting relationship equation, so as to obtain calculated data of production quantity of index gas. The calculated data is basically consistent with the actual measurement data, which verifies the validity of the fitting relationship equation.
Research on spontaneous combustion "three zones" in goaf of fully mechanized working face with large mining height
QU Shijia, AN Shigang, WU Fusheng, LI Peng
2019, 45(5): 22-25. doi: 10.13272/j.issn.1671-251x.17403
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In view of goaf spontaneous combustion prevention of 12401 fully mechanized working face with large mining height in Shangwan Coal Mine, CO is determined as prediction index gas of coal spontaneous combustion and C2H4 is used as auxiliary index gas to master coal spontaneous combustion through temperature programmed oxidation experiment. Gas in goaf is monitored by laying beam tubes on air return side in goaf of the working face, and spontaneous combustion "three zones" in goaf were divided according to monitoring results. Heat dissipation zone is 0-32 m away from the working face, spontaneous combustion zone is 32-225 m away from the working face, and suffocation zone is 225 m away from the working face. According to total length of heat dissipation zone and spontaneous combustion zone and the minimum coal spontaneous combustion period, the minimum safe advancing speed of the working face is about 6.4 m/d. The research results can provide reliable basis for formulation of fire prevention measures on the working face.
Research on inhibition of coal spontaneous combustion by composite superabsorbent resi
ZHANG Kang, DU Zhihao, WANG Deming, DOU Guolan
2019, 45(5): 26-30. doi: 10.13272/j.issn.1671-251x.17417
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In view of problems of poor fluidity, unsatisfactory fire-extinguishing effect and high cost of existing mine-used anti-fire extinguishing resistant material,inorganic clay composite superabsorbent resin was synthesized by aqueous solution polymerization method, and its structural characterization and thermal stability were measured. The resistive properties were studied combined with heating process of coal spontaneous combustion. The results of infrared spectrum and thermal stability analysis show that the prepared composite superabsorbent resin has main functional group with high water absorption characteristics and high thermal stability. The coal samples were treated with CaCl2, ascorbic acid and composite superabsorbent resin to resist the oxidation, and the oxidation kinetics and index gas tests were carried out on the coal samples after the inhibition. The results show that compared with the raw coal, CaCl2 and ascorbic acid resistant coal sample, composite superabsorbent resin resistant coal sample has the smallest oxygen consumption when the temperature of coal sample reaches 70 °C, and its intersection temperature is the highest, the initial temperature required to produce CO and CO2 is higher, which indicates that the composite superabsorbent resin has better inhibition effect on coal spontaneous combustion.
2019, 45(5): 31-34. doi: 10.13272/j.issn.1671-251x.17410
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Research on key technologies of intelligent large mining height fully mechanized mining equipments
ZHANG Yuliang
2019, 45(5): 35-39. doi: 10.13272/j.issn.1671-251x. 2019020023
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Abstract:
In order to ensure safe and high-efficient operation of intelligent fully mechanized mining equipments and normalized application of intelligent fully mechanized mining technologies, for fully mechanized mining equipments such as shearer, hydraulic support and video system in large mining height fully mechanized mining face of Shaanxi Huangling No.2 Coal Mine Co., Ltd., some key technologies were focused on including on precise height sensor and its protection equipment, mechanical and hydraulic system reliability, CAN bus communication isolation, remote start-stop control and outer spraying equipment for shearer, pressure sensor, travel sensor and support pushing control for hydraulic support and wide-angle camera with high performance and multi-angle adjustable mounting frame for video system. The key technologies can continuously improve reliability and monitoring accuracy of intelligent large mining height fully mechanized mining equipments.
Research on negative pressure distribution laws of drainage borehole with different deformation and instability
JIAO Rongkun, ZHANG Xuebo, LI Yi
2019, 45(5): 40-45. doi: 10.13272/j.issn.1671-251x.2018070064
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A solid-flow coupling model of gas drainage was established which synthetically considered dynamic variation of negative pressure of drainage borehole according to variation mass flow characteristic of gas flowing in the borehole and its deformation situation. Taking Xi'an Coal Mine as an example, distribution of negative pressure of drainage borehole with different deformation and instability were numerically simulated by use of multi physical fields coupling software Comsol Multiphysics. The simulation results show that: ① Coal-seam gas distribution near hole collar and hole bottom of complete borehole is almost the same. Negative pressure loss is little. ② When borehole is collapsed, coal-seam gas distribution around collapsed section is only slightly different from that in the complete borehole. The total negative pressure loss is larger than that in the complete borehole, but still lower than that at hole collar. ③ When borehole is blocked, the difference of coal-seam gas pressure between hole collar and hole bottom is significant, effective drainage length of borehole reduces, and blank tape will appear in coal-seam near the blocked section. Drainage pressure in the complete section varies little and is still negative pressure, while that in the blocked section becomes positive. What's more, the drainage pressure in the blocked section is close to coal-seam gas pressure gradually with approach to hole bottom. The field test results show that the negative pressure loss of complete borehole is small and decreases with prolongation of drainage time, which is consistent with numerical simulation results.
Reliability analysis of planetary reducer of shearer cutting unit
TIAN Zhen, GAO Shan, JING Shuangxi, ZHAO Lijuan
2019, 45(5): 46-50. doi: 10.13272/j.issn.1671-251x.2018100004
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In order to study reliability of planetary reducer of shearer cutting unit under influence of multiple factors, taking the MG400/951-WD shearer as research object, the load curve of spiral drum is calculated according to force analysis of pick and measurement result of coal sample mechanical properties. The load is applied to the model of cutting unit for simulation, and stress information of planet carrier and planet shaft is obtained. The reliability information of planet carrier and planet shaft is obtained by building a stress-reliability Gaussian membership function. Based on orthogonal test, influence law and significance degree of Protodyakonov coefficient of coal, traction speed of shearer and cutting depth of spiral drum on reliability of planetary reducer are analyzed. It is concluded that traction speed of shearer has the greatest influence on the reliability of planetary reducer, followed by Protodyakonov coefficient of coal, and the cutting depth has the least influence on the reliability of planetary reducer. With the increase of the Protodyakonov coefficient of coal, the decrease of the reliability of planetary reducer increases, and the decrease trend of the reliability becomes more obvious. With the increase of traction speed and cutting depth, the decrease of planetary reducer reliability tends to be gentle.
Research on mixed-fault diagnosis of mine-used belt conveyor gearbox
YANG Yun, XIONG Jijun, SONG Yaobin, MA Liyun, WANG Xiangling
2019, 45(5): 51-55. doi: 10.13272/j.issn.1671-251x.2018110004
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In view of problem that fault diagnosis methods of mine-used belt conveyor gearbox based on vibration signal analysis are not easy to process mixed-fault signals, a new mixed-fault diagnosis method of mine-used belt conveyor gearbox based on self-organizing map network was proposed. The standard multi-fault samples of mine-used belt conveyor gearbox are pre-processed by wavelet threshold denoising method incorporating Shannon entropy，Gaussian mixture distribution model is established for the standard multi-fault samples after pre-treatment, and the expectation-maximization algorithm is used to estimate the parameters of the model to obtain corresponding feature vectors which are input into the self-organizing map network. At last, the fault signals of different fault types are clustered and identified by self-organizing map network to determine the fault category. The test results show that the method can effectively diagnose the fault type of mine-used belt conveyor gearbox, and the overall accuracy of the diagnostic method is 88%, and the accuracy under six conditions is 100%. It provides a new method for gearbox fault diagnosis of mine electromechanical equipment.
Research on lever arm effect error compensation method for strap-down inertial navigation system of shearer
SI Zhuoyin, LI Wei, TONG Junling
2019, 45(5): 56-61. doi: 10.13272/j.issn.1671-251x.2018120038
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In view of problem that existing mechanical compensation methods of lever arm effect ca't get angular acceleration information in real time, an improved method of lever arm effect error compensation was proposed on the basis of analyzing cause of lever arm effect on strap-down inertial navigation positioning system of shearer.The method uses same component of the gravity acceleration information at different moments of navigation coordinate system to obtain length of lever arm.Then, it adopts the angular velocity to determine the angular acceleration of the carrier coordinate system with respect to the navigation coordinate system. Finally, it uses lever effect error equation to calculate the error of measured acceleration to compensate the output acceleration. The simulation results show that the error compensation method can improve precision of the strap-down inertial navigation positioning system of shearer, and compensate position error of shearer effectively to remove cumulative error. Compared with the uncompensated methods, the positioning accuracy of the shearer in x direction and y direction improves 5.1% and 23.6% respectively.
Simulation research on pitch angle control system of boom roadheader
ZANG Fuyu, WANG Kaishuo, JI Xiaodong, ZHANG Minjun, LIU Dan, LYU Fuyan, WU Miao
2019, 45(5): 62-67. doi: 10.13272/j.issn.1671-251x.2018110068
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At present, detection error of pitch angle of roadheader is mainly compensated by manually controlling front blade and rear support of roadheader, the compensation range is very limited, and the efficiency, control precision and automation degree are low. In view of the above problem, mathematical model of pitch angle and actuator of boom roadheader were established, and the method was determined that adjusting position and posture of boom roadheader by using PID controller to control displacement of front shovel and rear support of the roadheader. AMESim was used to establish complete hydraulic model of actuator of the roadheader. The AMESim simulation shows that response time of the system is less than 3 s and the control error of hydraulic cylinder displacement is less than 2 mm, so the basic performance of the pitch angle control system is verified. The Simulink simulation results verify that the pitch angle control system has short response time, small tracking error, and good dynamic tracking performance.
Influence of shape factor of rectangular roadway on electromagnetic waves under high-order mode
WANG Xuqi
2019, 45(5): 68-72. doi: 10.13272/j.issn.1671-251x.2018100062
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The propagation characteristics of electromagnetic waves in different shape roadway are different, and are also different in different modes. On the basis of analysis of theory of electromagnetic wave transmission and multi-mode theory, the influence of shape factor on electromagnetic waves propagation attenuation in rectangular roadway under high-order mode was researched by computer simulation. The simulation results show that when the shape factor of rectangular roadway is constant, the attenuation of electromagnetic wave increases with increase of electromagnetic wave transmission mode. Under different modes, with the increase of the shape factor, the slope of attenuation curve of electromagnetic wave remains unchanged. In the horizontal polarization mode, the attenuation of electromagnetic wave first decreases and then increase with increase of the shape factor, and the attenuation rate is the smallest when the shape factor is 1.7. In the vertical polarization mode, the attenuation curve also tends to decrease first and then increase with increase of the shape factor, and the attenuation rate is the smallest when the shape factor is 0.7. When the shape factor is equal to 1, the influence of the horizontal polarization and vertical polarization modes on electromagnetic wave propagation attenuation is same. When the shape factor is less than 1, the influence of the vertical polarization mode on the electromagnetic wave attenuation is greater than that of the horizontal polarization mode. And when the shape factor is greater than 1, influence of the horizontal polarization mode on electromagnetic wave propagation attenuation is greater than that of vertical polarization mode.
Research on four-coil structure of magnetically coupled resonant wireless power transmission system
FENG Liu, HE Jialua
2019, 45(5): 73-78. doi: 10.13272/j.issn.1671-251x.17385
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For the position of four coils of traditional four-coil magnetically coupled resonant wireless power transmission system is relatively fixed and cannot be changed at will, which leads to limitation of its use, a new four-coil structure was proposed: power coil and load coil are connected with the lumped capacitor separately to form power resonant circuit and load resonant circuit, the power coil can produce magnetic resonance with transmitting coil, the load coil can produce magnetic resonance with receiving coil. At the same time, the relative position of the four coils can be changed, the distance between the four coils can be adjusted appropriately, which not only can increase transmission distance of wireless electric energy, but also can improve frequency splitting, so as to maximize output power and transmission efficiency of the system. The effects of different coupling coefficients between the four coils on transmission efficiency and output power of the system were analyzed by simulation and experiment. The results show that the larger the coupling coefficient between the power coil and the transmitting coil is, the higher the transmission efficiency of the system will be, with the increase of the coupling coefficient, the transmission efficiency increases first and then decreases. The output power and transmission efficiency decrease obviously with the increase of the transmission distance between the load coil and the receiving coil. For different transmission distances, adjusting the distance between the load coil and the receiving coil enables the system to obtain the maximum transmission efficiency and output power under the same load.
Pulse sequence predictive control of permanent magnet synchronous motor powered by three-phase four-switch inverter
ZHANG Meimei, HAO Jianqi
2019, 45(5): 79-84. doi: 10.13272/j.issn.1671-251x.2019010019
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In view of problems of less control degree of freedom and large ripple of current and torque in single vector predictive control method, a pulse sequence predictive control method of permanent magnet synchronous motor powered by three-phase four-switch inverter was proposed. Two kinds of symmetrical pulse sequences with three voltage space vectors are constructed, and the optimal pulse sequence is selected by using cost function of current reference value tracking. Calculation formula of duty cycle under current reference value tracking target is given, and the duty cycle is compensated by adjusting DC component to achieve DC bus capacitor voltage balance. The simulation results show that the method can track current reference value and balance bus capacitor voltage, which effectively reduces current ripple and torque ripple.
Sensorless control strategy of interior permanent magnet synchronous motor
GU Mingyue, LIU Ya
2019, 45(5): 85-91. doi: 10.13272/j.issn.1671-251x.2018110003
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To improve steady-state and dynamic performance of sensorless control of permanent magnet synchronous motor with medium and high speed, and solve the problem that traditional quadrature phase-locked loop can not operate effectively when the motor is reversed, a sensorless control strategy of interior permanent magnet synchronous motor based on super-twisting sliding-mode observer and improved quadrature phase-locked loop was proposed. In the two-phase stationary coordinate system, the super-twisting function is used to replace switching function of the traditional sliding-mode observer to establish super-twisting sliding-mode observer, which can fully suppress chattering of sliding-mode and avoid using low pass filter, and can solve problems of phase delay and amplitude attenuation caused by low pass filter. The improved quadrature phase-locked loop algorithm avoids use of tangent function and uses a simple reverse electromotive force signal reconstruction strategy to obtain the error signal. Compared with the quadrature phase-locked loop algorithm based on tangent function, the improved algorithm is more simple and effective, and can make the motor reverse operation. In addition, the speed and position estimation error is small in operation process.The simulation results verify reliability and effectiveness of the control strategy.
Design of bolt force monitoring system based on synchronous monitoring
PENG Yuejin, LI Qingfeng, DENG Hongzhe, GU Hongfei, HUANG Qiyun
2019, 45(5): 92-95. doi: 10.13272/j.issn.1671-251x.2018100040
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In view of problems of complex structure, single measuring point and inconvenient installation of existing bolt force monitoring method, a bolt force monitoring system based on synchronous monitoring was designed. The system selects the diffusion silicon pressure sensor to collect the axial force of the bolt in a certain section of the roadway, and the force data of 8 bolts can be obtained simultaneously; the collected data are stored and transmitted after partial voltage filtering and AD conversion. The experimental results show that the system realizes synchronous monitoring of multiple bolts and anchor cables in a certain section of the roadway with high sampling rate, and its measurement accuracy can meet requirements of synchronous section bolts monitoring.
Early fault feature extraction method of vibration signal of mine-used motor
ZHANG Jiangong
2019, 45(5): 96-99. doi: 10.13272/j.issn.1671-251x.17399
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In view of problems of parameter setting, frequency aliasing and signal distortion existing in current fault feature extraction methods of vibration signal of mine-used motor, an early fault feature extraction method of vibration signal of mine-used motor based on dual-tree complex wavelet transform was proposed. Firstly, collected vibration signal of mine-used motor is decomposed by using dual-tree complex wavelet transform, so as to obtain dual-tree complex wavelet coefficients of each layer. Then soft threshold filtering is used to filter the dual-tree complex wavelet coefficients of each layer. At last, denoising signal is obtained by reconstruction of the filtered dual-tree complex wavelet coefficients. The application results show that the method can effectively remove noise in the motor vibration signal, and extracted early fault feature can reflect actual operating condition of motor, which provides an effective basis for early fault diagnosis of motor.
Current status and development trend of measuring methods of conveying capacity of mine-used belt conveyor
ZHANG Shaobin, JIANG Weiliang, RUI Feng
2019, 45(5): 100-103. doi: 10.13272/j.issn.1671-251x.2019010055
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Measuring methods of current mine-used belt conveyor were analyzed, which are electronic belt scale measuring method, nuclear belt scale measuring method, ultrasonic ranging measuring method, laser CCD image measuring method and laser scanning measuring method. Various methods were compared and analyzed from aspects of measurement accuracy, response time,etc. In contact measuring methods, electronic belt scale measuring method has high measurement accuracy, but response speed is slow and stability is poor. In non-contact measuring methods, laser scanning measuring method has high measurement precision, high response speed and good stability. It is indicated that development trend of measuring methods of conveying capacity is to improve measurement accuracy, anti-interference and adaptability; non-contact measurement method or a method combining various technologies will gradually become the mainstream measuring methods of conveying capacity.
Scheme of gob-side entry retaining by cutting roof to release pressure for Shiquan Coal Mine
LIANG Huajie, ZHANG Fengjie
2019, 45(5): 104-108.. doi: 10.13272/j.issn.1671-251x.17382
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Based on analysis of technical advantages of gob-side entry retaining by cutting roof to release pressure, combined with geological and mining technical conditions of 19022 working face of Shiquan Coal Mine, the scheme of gob-side entry retaining by cutting roof to release pressure for Shiquan Coal Mine was proposed: high-strength anchor with single hydraulic props were selected for advanced reinforcement support of mining roadway; pre-split blasting was carried out on the roof of roadway from goaf to advanced support section to form fracture top cutting line during pressure relief; reinforcement support in the back of the working face adopted the form of sluice column + single hydraulic props lifting shed + hydraulic lifting shed. The results of mine pressure monitoring show that the average subsidence of roadway roof is 95 mm, and the average displacement of the two gangs is 225 mm, which is in line with the deformation requirements of the roadway section;the average support resistance of the roadway supports is 33 MPa, which meets the requirements of roadway support strength.

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