工矿自动化

All source mine positioning: a new paradigm for intelligent coal mine positioning service

HU Qingsong, QIAN Jiansheng, LI Shiyin, SUN Yanjing, ZHANG Zhen

2021, 47(1): 1-8. doi: 10.13272/j.issn.1671-251x.17684

<Abstract>(128) <HTML> (13) <PDF>(11)

Abstract:
Mine moving target positioning system provides location-based services for intelligent construction of coal mines. However, most of the traditional mine positioning systems use single or combined communication technologies between positioning beacons and positioning tags with inflexible structure, limited coverage, low robustness and limited positioning accuracy. Using single or combined ranging technology, the optimal ranging technology cannot be selected adaptively according to different usage scenarios. For the position solution algorithm is fixed, the optimal solution algorithm cannot be selected adaptively according to different usage scenarios and signal changes. Hence, a new paradigm for all source mine positioning service is proposed, which can dynamically select the optimal combination of devices that meets current needs from all available positioning signal measurement devices according to the changes of the positioning environment and the target bearing platform. The paradigm can select the optimal combination of algorithms from the available ranging algorithms, positioning solving algorithms and result optimization algorithms adaptively to calculate the optimal position of the target node. In this study, all source mine positioning system architecture is designed, the available positioning signal measurement devices in mines and the types of measurement attribute values that can be used for positioning are discussed, and the functional differences of positioning servers between single mine positioning and all source mine positioning are compared. This paper discusses three key technologies in all source mine positioning service: unified positioning framework technology, which aims to meet the modular, combined and expandable needs of all source positioning; all source positioning information fusion technology, which organizes the measured attribute values to improve positioning accuracy; communication and positioning integration technology, which simplifies the design of all source mine positioning system and improves positioning accuracy through the positioning capability of wireless communication network itself. This paper proposes the implementation architecture of a terminal-edge-cloud based all source mine positioning system in order to fit in with the mainstream construction mode of intelligent coal mine and reduce the implementation difficulty and system cost significantly.

Development and application of gas leakage channel detection device for gas extraction borehole

BA Quanbin

2021, 47(1): 9-14. doi: 10.13272/j.issn.1671-251x.2020070104

<Abstract>(83) <HTML> (12) <PDF>(9)

Abstract:
The perimeter cracks of gas extraction borehole and the gap passage of sealing section are the main causes of the failure of borehole leakage. In order to detect the gas leakage channels in the borehole effectively, a gas leakage channel detection device is developed based on the theory of tube flow hydrodynamics and gas leakage detection method. Detecting gas sample parameters at different drilling depths and analyzing the distribution and abrupt changes are used to identify the cause of extraction borehole failure and the location of gas leakage channels. The detection device adopts highly stable piezoresistive pressure sensors, laser methane sensors and fluorescent oxygen sensors to detect extraction negative pressure, gas concentration and oxygen concentration. The device adopts 1.5 m/section quick-connect 25 mm thin-walled stainless steel pipe as the gas extraction fittings and the drilling depths is up to 30 m. The application results show that the variation of testing parameters in extraction pipe section is stable, the extraction pipe is not damaged, the interface is not leaking, and the sealing effect of the extraction pipe is good. In the sealing section, there are several abrupt change points of different degrees in the range of 9-18 m from the hole. The largest air leakage channel is in the range of 9-12 m from the hole, indicating that the original sealing depth is insufficient and the original sealing process cannot seal the air leakage channel effectively. In this study, the sealing depth is increased to 12 m and the 'two plugging and one injectio' pressure-injected grouting sealing technology is used for comparative tests. The results show that the overall extraction effect of the test hole is greatly improved, the volume fraction of gas at the hole is increased to more than 55%, the change of gas volume fraction is stable within the depth range of 12 m from the hole, the volume fraction of oxygen is almost 0, and the gas leakage channels are reduced. The test results verify that the gas leak channel detection device can effectively detect gas leakage channels, provide a basis for the targeted adjustment of sealing methods, related parameters and subsequent improvement.

Networked high-precision and high-stability array electronic belt scale instrument

ZONG Hao, GE Zhiqi, HUA Gang

2021, 47(1): 15-20. doi: 10.13272/j.issn.1671-251x.2020100061

<Abstract>(72) <HTML> (13) <PDF>(9)

Abstract:
The traditional methods applied in improving the measurement accuracy of electronic belt scales are designing highly sensitive scales and improving the sampling accuracy of weighing sensor. These methods are difficult to compensate for the weighing errors caused by belt tension. However, the effect of belt tension on measurement accuracy can be reduced by setting up multiple scales in parallel and forming an array of scales. Based on the analysis of internal force theory, it is concluded that the belt tension at both ends of the electronic belt scale is the main cause of weighing errors, and the proportion of belt tension at both ends decreases with the increase of the weighing unit. Therefore, the array electronic belt scale can reduce the impact of belt tension changes on the measurement accuracy and improve stability. In this study, a networked high-precision and high-stability array electronic belt scale instrument is designed with high-performance ARM processor STM32F767 as the control core. The functions of the scale include 8-channel weighing array dynamic metering, logic control, human-machine interaction, power-down storage, industrial control & communication and Internet remote monitoring. By using static coding method, the test results show that the weighing error of the instrument is about 0.03%, the scale is insensitive to the tension changes caused by the belt speed and load, and the scale has high measurement accuracy and stability.

Classification coding of coal mechanical equipment information for full life cycle management

ZHANG Jianzhong

2021, 47(1): 21-27. doi: 10.13272/j.issn.1671-251x.2020070016

<Abstract>(113) <HTML> (16) <PDF>(13)

Abstract:
There are a large number of information islands in the process of cross whole life cycle management of coal mechanical equipment, which leads to the inability to deepen the data application. To solve the above problems, the classification and coding system of coal mechanical equipment information for full life cycle management is designed. The system is based on the operation mode of the product chain, asset chain and value chain of the coal mechanical equipment full life cycle business process, combines the existing international, national, coal industry and related fields information classification and coding standards, and uses Unified Modeling Language (UML) and Object Oriented Analysis Method (OOA). Firstly, a hybrid classification method combining line classification method and surface classification method is used to classify coal mechanical equipment information. Secondly, the GTIN of the GS1 coding system is used to realize the unique mark of coal mechanical equipment category, and the additional attribute method is used to associate MJLBM-1 code of coal mechanical equipment. Thirdly, the SGTIN-96 code of EPC coding system is used for the unique identification of single coal mechanical equipment to achieve the conversion between SGTIN and GTIN. Application examples have verified the feasibility of the classification and coding system. To a certain extent, the system solves the problems of confusion classification and coding of coal mechanical equipment information, poor standardization and difficulty in information sharing. Furthermore, the system achieves system compatibility with the global GS1 system, which broadens the circulation of relevant products and technologies in the coal industry.

Study on sealing technology and equipment of non-solidified paste materials for large diameter gas extraction boreholes

TANG Weidong, LI Xiaowei, ZHOU Dong

2021, 47(1): 28-35. doi: 10.13272/j.issn.1671-251x.2020040071

<Abstract>(93) <HTML> (16) <PDF>(9)

Abstract:
For large diameter gas extraction boreholes, the solid material sealing method has a good sealing effect at the beginning. However the gas concentration of the extracted gas from the borehole decreases rapidly after the deformation and destruction of the sealing borehole over time. In order to solve these problems, a non-solidified paste material sealing technology for large diameter gas extraction boreholes is proposed. This technology uses expanded cement and non-solidified paste material to form a multi-segment "solid, liquid, solid" structure, uses expanded cement material to form three solid sealing segments, and then injects non-solidified paste material into the solid sealing segments during different extraction time. Hence the technology realizes the effective sealing of the whole process of extraction and the secondary and multiple sealing of the borehole during different extraction time. Based on the theoretical analysis of the fracture radius around the large diameter borehole, the relationship between the optimal grouting pressure and viscosity is numerically simulated. The technical parameters related to the sealing of non-solidified paste material are studied. The optimal grouting pressure is 1.2 MPa and the optimal viscosity is 0.001-0.03 Pa·s. A borehole sealing equipment is developed based on the grouting pressure and viscosity obtained from the research, which utilizes the principle of "solid, liquid, solid" technology to form a multi-segment borehole sealing structure, and realizes the extraction sealing mode of solid sealing liquid and liquid sealing gas. The results of field industrial tests show that the sealing technology of non-solidified paste material in large diameter gas extraction boreholes, combining the characteristics of the paste material changing with the time and space of the extraction, can solve the problems of sealing failure and rapid decay of extraction concentration, which caused by new fracture formed by the solid material sealing due to borehole deformation. Furthermore, the volume fraction of extraction can be increased by about 10% after secondary grouting which can improve the gas extraction rate effectively.

Research on intelligent control algorithm of coal gangue sorting robot armbased on reinforcement learning

ZHANG Yongchao, YU Zhiwei, DING Lili

2021, 47(1): 36-42. doi: 10.13272/j.issn.1671-251x.2020080047

<Abstract>(133) <HTML> (23) <PDF>(14)

Abstract:
The problems of the traditional gangue sorting robot arm control algorithms such as the grasping function method and the dynamic target grasping algorithm based on Ferrary method are relying on an accurate environment model and lacking adaptivity in the control process. At the same time, the problems of the traditional intelligent control algorithms such as deep deterministic policy gradient (DDPG) are excessive output actions and sparse rewards that are easily covered. In order to solve these problems, this study improves the neural network structure and reward function in the traditional DDPG algorithm, and proposes an improved DDPG algorithm based on reinforcement learning, which is suitable for handling six-degree-of-freedom gangue sorting robot arms. After the gangue enters the working space of the robot arm, the improved DDPG algorithm can make decisions according to the gangue position and robot arm state returned by the corresponding sensor, and can output a set of joint angle state control quantity to the corresponding motion controller. The algorithm can control the movement of the robot arm according to the gangue position and joint angle state control quantity, so that the robot arm moves to the nearby gangue to conduct gangue sorting. The simulation results show that compared with the traditional DDPG algorithm, the improved DDPG algorithm has the advantages of model-free versatility and adaptive learning of grasping pose in interaction with the environment. Moreover, the improved algorithm can be the first to converge to the maximum reward value encountered during exploration. The robot arm controlled by the improved DDPG algorithm has better policy generalization, smaller joint angle state control output and higher gangue sorting efficiency.

Research on improved PDR algorithm for underground personnel positioning

SUN Yanxin, MAO Shanjun, SU Ying, YANG Meng

2021, 47(1): 43-48. doi: 10.13272/j.issn.1671-251x.2020080086

<Abstract>(88) <HTML> (8) <PDF>(13)

Abstract:
As the traditional pedestrian dead reckoning (PDR) algorithm being used for underground personnel positioning, the positioning error gradually increases due to the cumulative error of the step frequency detection, step length estimation and heading estimation phases. Moreover, the commonly used error correction methods such as zero speed correction, heading drift elimination and gait signal optimization cannot change the inherent defects of the PDR algorithm, and the positioning accuracy needs to be improved. It is proposed to use an improved peak detection method to achieve step frequency detection in the PDR algorithm, and to achieve step length estimation based on a deep recurrent neural network (RNN). The improved PDR algorithm is used for underground personnel positioning. Firstly, cell phone accelerometer, gyroscope and magnetometer are used to obtain pedestrian movement data. Secondly, the improved peak detection method is used to obtain the average step frequency in a fixed time interval. The average step frequency, the time interval, acceleration and acceleration variance are used as features to be input to the trained deep RNN model for step length estimation. Finally, the estimated heading angle is added to predict the current position of the personnel. The experimental results show that the improved PDR algorithm for underground personnel positioning has a relative error of 5.9% in predicting the test set data and has a relative error of 1.6%-3.9% in positioning the actual test route. The relative error is smaller than the positioning error of the traditional PDR algorithm and the proposed PDR algorithm has improved the accuracy of underground personnel positioning effectively.

Positioning algorithm of mine-used monorail crane locomotive based on strapdown inertial navigatio

GUO Liang, SONG Jiancheng, NING Zhenbing, WANG Mingyong, LIN Lingyan, HUANG Jianqi

2021, 47(1): 49-54. doi: 10.13272/j.issn.1671-251x.2020080015

<Abstract>(102) <HTML> (16) <PDF>(11)

Abstract:
A positioning algorithm of mine-used monorail crane locomotive based on strapdown inertial navigation is proposed for the problems of low positioning accuracy and high positioning cost of common positioning methods for underground monorail crane locomotives in coal mines. Nine-axis inertial measurement unit (IMU) is used to collect the acceleration data of the locomotive, and the acceleration data is pre-processed by limiting filtering and zero offset removal to calculate and output the attitude angle and acceleration values. The direction cosine matrix method is applied to filter out the gravity component contained in the acceleration data so as to eliminate the interference of this component to the data. The acceleration rate of change threshold method and zero speed correction method are used to correct the steady-state error so that the steady-state acceleration and speed are closer to the real value. The Lagrange interpolation polynomial distance measurement method is applied to measure the driving distance of the monorail crane locomotive, and the distance measurement result timing correction method is used to compensate the distance measurement error. Therefore, the positioning can be obtained according to the starting point and driving distance of the locomotive. The experimental results show that when the driving distance is 30.8 m, the ranging error is basically within 0.65 m, which can meet the requirements of high-precision and low-cost positioning.

Research on leakage positioning method of underground gas extraction main pipeline based on transient model

ZHANG Yibin, ZHANG Lang, ZHANG Huijie, LI Wei, LIU Yanqing, SANG Cong

2021, 47(1): 55-60. doi: 10.13272/j.issn.1671-251x.2020080024

<Abstract>(103) <HTML> (12) <PDF>(11)

Abstract:
At present, most of the existing positioning methods of underground gas extraction main pipeline leakage in coal mines use single positioning method. The problems of these methods include poor applicability, low efficiency and susceptibility to environmental impact. In order to solve the above issues, this paper proposes a leakage positioning method of underground gas extraction main pipeline based on transient model by combining flow balance method, negative pressure wave method and wavelet noise reduction principle. Firstly, the method analyzes the flow change law and the difference of the both ends of of the pipeline, eliminate the interference signal, use the flow balance method to identify the pipeline leakage state and determine whether the pipeline is leaking. The method compares the flow changes under normal operation and leakage. When the difference between the both ends of the pipeline flow is greater than the threshold value of the pipeline flow difference, it means that the working conditions have changed or leakage occurs. Secondly, according to the propagation mechanism of negative pressure waves in the pipeline, wavelet noise reduction technique is used to denoise the pressure signal. The neighborhood interpolation method is applied to seek the signal mutation point. Finally, the leak location formula is used to calculate the leak position so as to obtain the leak position of the pipeline effectively. The simulation analysis results verify the accuracy of the method.

Research on gas pre-drainage in coal roadway strips by combined ordinary drilling and directional drilling

JI Pengfei, GUO Ying, ZHANG Lei, KONG Xiangguo, WANG Xu, ZHOU Yuxuan

2021, 47(1): 61-66. doi: 10.13272/j.issn.1671-251x.2020030071

<Abstract>(92) <HTML> (12) <PDF>(7)

Abstract:
When single layered ordinary drilling or directional drilling are used in gaspre-drainage in coal roadway strips, the long boreholes easily deviate from the trajectory and the cost of directional drilling is high. With the case study of 21601 excavation working face of Qinglong coal mine, the method of gaspre-drainage in coal roadway strips by combined ordinary drilling and directional drilling is proposed to solve the above problems. Numerical simulation results show thatwhen extracting the gas by single drilling, the axial gas pressure contour of drill hole at the end position of drill hole in the early stage is "V" shaped distribution. As the extraction time increases, the "V" shaped distribution of gas pressure gradually smooths. The gas pressure in the radial direction of the borehole gradually increases outwards in a ring shape with the borehole as the center. The effective extraction radius reaches 3.80 m at 93 d of pre-drainage. The ordinarydrilling and directional drilling can effectively control the gas in the range of 15 m in front of the two sides of the coal roadway and 200 m in front of the coal working face respectively. Field application results show that when ordinary drilling and directional drilling are combined for pre-drainage, the average value of total gas extractionis 19.86×103 m3, the average gas extraction volume fraction is 53.5%, the average pure gas extraction flow is 1.97 m3/min, the average mixed gasextraction is 3.68 m3/min, and the residual gas content is less than 8 m3/t.The gas extraction effect is proved to be good.

Determination of reasonable length of wind-blocking curtain in 10201 working face of Bailongshan Coal Mine

CUI Chuanfa

2021, 47(1): 67-73. doi: 10.13272/j.issn.1671-251x.2020050057

<Abstract>(95) <HTML> (12) <PDF>(6)

Abstract:
In order to solve the problems of serious air leakage and high gas concentration in the upper corner of 10201 working face of Bailongshan coal mine, Fluent software based numerical simulation studies are carried out to obtain the change law of working face air volume and gas concentration, the change law of gas distribution and spontaneous combustion oxidation zone in the air inlet side with different lengths of wind-blocking curtains. The results showed that in the range of 0-80 m from the working face to the inlet lane, the air volume of the working face gradually increase. In the range of 0-190 m from the working face to the inlet lane, the gas concentration of the working face gradually decreases with the increase of the length of the wind-blocking curtain. The wind-blocking curtain can reduce the gas concentration in the shallow and central part of the return side of the mining area. But for the deep part of the inlet side and return side of the mining area, the wind-blocking curtain will increase the gas concentration. The installation of the wind-blocking curtain on the inlet side is able to increase the width of the spontaneous oxidation zone on the inlet side of the mining area, reduce the width of the spontaneous oxidation zone on the return side of the mining area. As the length of the windshield increases, the spontaneous combustion oxidation zone on the inlet side of the mining area gradually approaches the working face. The numerical simulation results show that the reasonable length of wind-blocking curtain is 5 m. The application results show that after the curtain installation, the effective air volume of the working face increases, the average gas volume fraction is 0.521% with a decrease of 13.5%, the average carbon monoxide volume fraction is 2.26% with the decrease of 8.1%, and the risk of gas overrun in the upper corner and spontaneous fire in the mining area is reduced.

Application of adaptive local iterative filtering in gear fault identification

GUO Dewei, PU Yasong, JIANG Jie, YU Libin, MIN Jie, ZHANG Wenbin

2021, 47(1): 74-80. doi: 10.13272/j.issn.1671-251x.2020070070

<Abstract>(122) <HTML> (15) <PDF>(8)

Abstract:

In order to solve the problem that the measured signal of gears cannot accurately reflect the fault characteristics due to noise interference, adaptive local iterative filtering is proposed to be applied to gear fault identification, which is combined with sample entropy and grey correlation to realize gear fault identification. By using adaptive local iterative filtering to decompose the gear non-stationary signal into a finite number of stationary intrinsic mode functions, and calculating the sample entropy of each intrinsic mode function, it is found that the sample entropy of the first few intrinsic mode functions can represent different fault types, bounded by the sample entropy of the intrinsic mode function corresponding to the frequency conversion signal of the gear system. The average value of the sample entropy of multiple training samples under four working conditions of gear system, including normal, mild tooth surface wear, moderate tooth surface wear and broken tooth, is calculated and used as the reference value of the standard failure mode of the corresponding working condition. The grey correlation between the sample entropy of the sample to be detected and the average value of the sample entropy of the training samples under each condition is calculated, and the standard failure mode with the largest grey correlation with the sample to be identified is considered as the failure type of the sample to be identified. The results of the case analysis show that the adaptive iterative filtering can suppress the modal aliasing phenomenon effectively and find obvious gear frequency conversion signals. On the other hand, the modal aliasing phenomenon is more obvious after the signal decomposition by EEMD method, and the frequency conversion component of the gear is basically invisible in the decomposition results of EEMD method. The obvious differences in the shapes of the sample entropy curves of the four working conditions indicate that the sample entropy can represent the changes of gear fault characteristics effectively. The grey correlation method, which can classify and identify the four different fault types effectively, has better classification identification performance than that of BP neural network and has better classification identification ability for small sample data.

Predictive control of high-power three-level PWM rectifier without weighting coefficient

CHENG Weiwei, WU Rui

2021, 47(1): 81-86. doi: 10.13272/j.issn.1671-251x.2020070015

<Abstract>(74) <HTML> (11) <PDF>(8)

Abstract:
A high-power three-level PWM rectifier predictive control algorithm without weight coefficients is proposed for the problem of complicated design of the weight coefficients of the cost function in the traditional predictive control algorithm. The Pareto optimal solution set for multi-objective satisfactory optimal control of current command tracking and midpoint potential regulation is calculated based on the introduction of a tolerance interval for the target tracking error. When the Pareto optimal solution set is an empty set, the current command tracking based on the control deviation degree measurement function and the midpoint potential are used to adjust the target cost function so as to eliminate the weight coefficient of the cost function in the traditional predictive control. When the Pareto optimal solution set is not an empty set, a new switching loss cost function is designed to achieve low switching frequency control of the rectifier. The simulation results have verified the effectiveness and dynamic performance of the algorithm.

Research on strong anti-misalignmemt methods of double-coupled LCL topology ICPT system

JIAN Yinwen, CHENG Zhijiang, CHEN Xingzhi, YANG Handi

2021, 47(1): 87-93. doi: 10.13272/j.issn.1671-251x.2020080036

<Abstract>(190) <HTML> (10) <PDF>(9)

Abstract:
Inductively coupled power transmission (ICPT) systems cause fluctuations in output power and output voltage when the coil is offset.The existing anti-misalignmemt methods have the problems of relying too much on the system modeling and poor adaptivity. Most of the methods do not consider the impact on the system output characteristics when the coupling coefficient changes continuously. To address the above problems, taking the dual-coupled LCL topology ICPT system based on DDQ coils as the research object, the paper proposes a strong anti-misalignmemt method based on fuzzy adaptive control in variable universe. Firstly, the output power expression of the dual-coupled LCL topology ICPT system is derived from the circuit analysis, and the relationship between the output power, the coupling coefficient and system parameters is obtained. Secondly, by applying the finite element analysis software ANSYS, a three-dimensional magnetic field modeling of the DDQ coil is carried out to obtain the correspondence between the coupling coefficient and the coil offset. On the basis, the corresponding values of the three sets of offsets and the coupling coefficients are used as the data, and the square sum of deviations of the system output power fluctuations is taken as the objective function. Hence, the parameter optimization method of ICPT system based on adaptive particle swarm is proposed to obtain a set of optimal parameter values of the system under the minimum output power fluctuation and improve the anti-misalignmemt performance of the system to a certain extent. Finally, a fuzzy adaptive control method based on variable universe is used to achieve the purpose of quickly adjusting the load terminal voltage by dynamically adjusting the correction value of the PID control coefficient to make the system output higher power. The simulation results show that the method solves the problem of poor adaptivity of existing methods, adapts well to the working conditions with continuous changes of coupling coefficients, has better adaptability and control effect, improves the strong anti-misalignmemt performance of ICPT system, and maintains the basic constant output voltage at the load side.

Research on air flow control device for excavating face

GONG Xiaoyan, CUI Xiaoqiang, LEI Kefan, ZHAO Kuan, LIU Hui, FENG Xiong

2021, 47(1): 94-99. doi: 10.13272/j.issn.1671-251x.17634

<Abstract>(89) <HTML> (12) <PDF>(9)

Abstract:
At present, it is difficult to adjust the air flow at the outlet of the wind pipe dynamically by the total ventilation control method commonly used in the excavating face, resulting in insufficient air volume or unreasonable air flow distribution, and causing safety hazards such as gas and dust accumulation. Taking S1200-Ⅲexcavating face of Ningtiaota Mine as an example, by analyzing the problems of the original wind field and the requirements of wind flow control, the air flow control device is designed, which installed a mechanical structure driven by a pneumatic cylinder or a pneumatic motor. The device is able to realize the dynamic adjustment of outlet deflection angle, caliber size and front-back displacement. This paper introduces the design scheme of mechanical system, pneumatic actuation system and control system of the device. ANSYS Workbench software is used to conduct finite element analysis on the safety of the mechanical system. The results show that the maximum stress is 87.2 MPa, the safety factor is 2.69, the maximum deformation is 0.84 mm, and the average deformation is 0.42 mm. FluidSIM software is applied to simulate and analyze the pneumatic actuation system. The results show that the device can complete the predetermined action and run smoothly and reliably. Underground test results show that after adopting this device, the air flow distribution at the driver and pedestrian breathing zone height is more reasonable. When the air duct outlet is 5 m away from the working surface, the dust concentration at the driver and pedestrian breathing zone is reduced by 45.3% and 33.4% respectively compared with situation before the control. When the air outlet is 10 m away from the working face, the concentration is reduced by 40.4% and 34.3% respectively.

Research on combined gas extraction technology of high andbottom extraction lane in high gas mine

GAO Hong, YANG Hongwei

2021, 47(1): 100-106. doi: 10.13272/j.issn.1671-251x.2020060054

<Abstract>(112) <HTML> (13) <PDF>(11)

Abstract:
In order to solve the problems of low extraction efficiency, low extraction concentration, poor permeability of coal seam and difficulty in drilling holes in the gas management of U-ventilated return working face of loose and low-permeability coal seams, the combined gas extraction technology of high and bottom roadway in high gas mine is proposed. The research object of this paper is 1307 fully mechanized mining face of Zhaozhuang Mine of Shanxi Jin Coal Group. The technology consists of a high extraction lane, a central bottom extraction lane and a side bottom extraction lane on the basis of the original U-shaped ventilation. The side bottom extraction lane covers the drilling of two heading faces, the central bottom extraction lane penetrates the strip of the seam area to pre-pump the gas of the coal seam, and the high extraction lane extracts the gas from the upper corner. This study proposes the position of the side bottom extraction lane and the central bottom extraction lane, and proposes the drilling arrangement and the reasonable layer arrangement of the high extraction lane. The practical application results show that the maximum gas volume fraction of the coal working face covered by the side bottom extraction lane is 0.48%, and the extraction through the layer drilling reduces the gas emission from the heading face effectively. After the central bottom extraction lane extracting the gas from this coal seam, the gas content decreases by 4.18 m3/t on average. As the negative pressure of the high extraction lane is 12-15 kPa, the pure extraction volume is stable at about 46.13 m3, which reduces the gas emission to the working face.

Design of synchronous acquisition device for mine delayed seismic source

CUI Weixiong

2021, 47(1): 107-111. doi: 10.13272/j.issn.1671-251x.2020070064

<Abstract>(96) <HTML> (9) <PDF>(8)

Abstract:
In mine seismic exploration, there is a certain time delay from the power-on to the explosion of the explosive source. This delay time directly affects the accuracy of mine seismic data processing and exploration results. In order to ensure the time accuracy of data acquisition in coal mines, a synchronous acquisition device for mine delayed seismic source is designed. When the detonator initiates, the high voltage current from the detonator produces an induced current through the current transformer. The induced current signal is converted into a voltage pulse signal that can be recognized by the nodal seismograph through the pulse shaping circuit. The near-field vibration pickup receives the vibration signal generated by the delayed detonation of the explosion and transmits it to the seismic acquisition substation. The seismic acquisition substation uses the vibration signal time and pulse signal time as the identification basis for the synchronous time of seismic data so as to obtain the accurate delay time of the seismic source explosion. Correcting the delay time of a single explosion in the data acquisition process can improve the synchronous accuracy of the seismic acquisition system. In terms of structure design, the design of passive circuit is obtained by adopting the core-structured current mutual inductance technology, so as to effectively solve the problem of connecting the leading wire with the synchronous acquisition device. The synchronous acquisition device is quickly installed and fixed on the anchor rod near the blast hole through the anchor rod connection hole. This method not only solves the problem of installing the synchronous acquisition device near the blast hole, but also receives the near-field seismic shock wave conveniently, quickly and accurately. The test results show that the synchronous acquisition device can be triggered within 10 μs, the trigger signal amplitude is about 2.5 V, the duration is about 30 ms, and the performance index meets the requirements of the synchronous acquisition device for seismic wave exploration.

Design of mine-used intrinsically safe line array X-ray receiving box

FANG Chongquan

2021, 47(1): 112-117. doi: 10.13272/j.issn.1671-251x.2020050022

<Abstract>(68) <HTML> (12) <PDF>(11)

Abstract:
The mine-used explosion-proof line array X-ray receiving box is not suitable for nondestructive testing of high-speed conveyor belts. And there are difficulties in processing the explosion-proof enclosure and heavy weight for nondestructive detection of wide-surface conveyor belts. In this context, a mine-used intrinsically safe line array X-ray receiver box based on FPGA is designed. The X-ray receiving box consists of signal detection board and signal processing board. The signal processing board supports 4 buses. Each bus cascades up to 6 signal detection boards. Each signal detection board is equipped with 4 X-ray detectors. The image spacing of the X-ray detector is 1.6 mm and the detector has 16 detection channels. Hence, the X-ray receiving box has a detection width of 2.4 m. The signal detection board is used to collect the X-ray signal attenuated by the conveyor belt and convert it into line array X-ray image data. The signal processing board realizes the simultaneous high-speed acquisition and processing of the image data of the signal detection board, and also collects the real-time running speed of the conveyor belt and transmits the data through the Gigabit Ethernet interface. The test results show that the X-ray receiving box has the characteristics of light weight and easy installation, and meets the requirement of X-ray nondestructive inspection of coal mine steel cord conveyor belt with high belt speed and wide belt surface.

Design of vibration sensor for coal gangue identificatio

CAO Guanqiang, YU Rui, MENG Xiangtao, ZHAO Wensheng, LIU Qing

2021, 47(1): 118-122. doi: 10.13272/j.issn.1671-251x.2020070097

<Abstract>(164) <HTML> (15) <PDF>(37)

Abstract:
At present, there are a variety of coal gangue identification technologies in automatic top coal mining. Gamma ray is too expensive and harmful to human body. Infrared technology is affected by ambient temperature. Radar detection has serious signal attenuation when the coal seam is thick. Sound technology has low cost and small difficulty, but can be severely interfered by external sound signals. Image technology is effective when the color difference of coal gangue is large, but is affected by dust and light factors. However, vibration technology not only has the advantages of sound technology but also can avoid environmental noise interference and obtain a higher detection accuracy. For the properties of top coal and gangue are different, the vibration signal generated when falling onto the hydraulic support tail beam also shows different characteristics. Based on this feature, a vibration sensor is designed, which is installed at the web of the tail beam of the hydraulic support to sense the vibration signal generated by the top coal or gangue hitting the hydraulic support, and identify the coal and gangue in the coal release process through signal processing and analysis. The sensor uses an accelerometer to collect the tail beam vibration signal, and conducts front-end filtering processing of the collected data. Fourier transform is applied to analyze the power spectrum of the data so as to obtain the maximum vibration frequency, amplitude and power spectrum energy per unit time. The laboratory test results show that the sensor measurement error is within 1%. The underground test results show that most of the signals collected by the vibration sensor are the vibration signals of coal falling, and the frequency range is 100-200 Hz. However, the vibration signals of gangue falling is above 200 Hz. Therefore, the differences of the vibration signal characteristics are useful to identify the top coal and gangue.

2021 Vol. 47, No. 1

Submission System

Latest AcceptedMore>