2019 Vol. 45, No. 3

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Research on methods of mine fire monitoring and trend predictio
SUN Jiping, SUN Yanyu
2019, 45(3): 1-4. doi: 10.13272/j.issn.1671-251x.17407
<Abstract>(127) <HTML> (10) <PDF>(15)
Abstract:
Based on analysis of principle and characteristics of mine fire monitoring methods such as temperature monitoring method, gas monitoring method, smoke monitoring method, visible light image monitoring method and infrared image monitoring method, a mine fire monitoring and trend prediction method based on multi-parameter fusion was proposed. Conclusions were got as following:① Thermocouple temperature measurement method and semiconductor temperature measurement method have advantages of high accuracy, strong real-time performance and early detection of early fire, but there are disadvantages such as large sensor consumption and large maintenance workload; Infrared temperature measurement method has advantages of wide monitoring range and easy sensor arrangement, but shielding and coal dust between sensor and measured object will affect monitoring result; Fiber distributed temperature measurement method has advantages of multi-point temperature monitoring and small amount of cable consumption, but there are disadvantages such as easy damage, complicated installation and difficult maintenance of optical fiber. ② Gas monitoring method and smoke monitoring method have advantages of wide monitoring range, convenient use and maintenance, but there are disadvantages such as cannot monitor early fire with low concentration of index gas and less smoke. ③ Visible light image monitoring method has advantages of wide monitoring range, convenient use and maintenance, low cost, but interference sources such as roadway light, miner's lamp, vehicle lamp and red clothes and smoke will affect monitoring effect, and the method cannot monitor early fire with no flame and less smoke.④ Infrared image monitoring method has advantages of wide monitoring range, convenient use and maintenance, but cost is high, and shielding and coal dust between infrared camera and measured object will affect monitoring effect. ⑤ Mine fire monitoring and trend prediction method based on multi-parameter fusion of temperature, smoke, gas concentration, odor, wind direction, wind speed, air volume, visible light image and infrared image can not only detect fire in time, but also locate fire source and predict fire development trend.
Optimization of mine fire rescue path based on multivariate information evaluatio
JIANG Yuanyuan, SHI Meile
2019, 45(3): 5-11. doi: 10.13272/j.issn.1671-251x.2018100025
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Abstract:
In view of problems that coal mine underground fire rescue model is too complicated, study of roadway safety coefficient is not deep enough and roadway traffic network connectivity after disaster is not considered, a mine fire rescue path optimization model based on multivariate information evaluation was established. Quantitative analysis and calculation of environmental safety factors after fire were carried out such as temperature, gas concentration and smoke visibility in roadway. Taking safety and reliability as constraints, mine fire rescue path optimization model was constructed combined with traffic weight and connectivity of roadway traffic network, and Dijkstra algorithm was used to get the optimal path. Taking a mine in Huainan as an example, the shortest path considering connectivity and safety factor of the node, the rescue path considering only safety factor, and the rescue path without considering safety factor and connectivity were compared and analyzed. The results show that the safest and most effective route is the path obtained by considering safety factor of the roadway and connectivity of the nodes.
Research on dynamic appearance regularity of blow-out from drilling hole in low gas coal seam of Panxi Coal Mine
NIE Fengxiang, GUO Haifeng
2019, 45(3): 12-17. doi: 10.13272/j.issn.1671-251x.17400
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Abstract:
In order to reveal dynamic appearance regularity of blow-out from drilling hole in deep low gas coal seam of Panxi Coal Mine, field tests of gas content and mining stress were carried out in 6198 working face of Panxi Coal Mine, and simulation analysis of stress distribution in front of 6198 working face was also done by use of FLAC3D software. Distribution regularities of gas content and stress in the working face were studied, and dynamic appearance mechanism of blow-out from drilling hole in low gas coal seam was analyzed. The study results show that gas content in 6198 working face is low in general, and the greater mining depth is, the higher gas content is. Affected by faults, the maximum stress concentration factor in front of the working face is 1.36. Dynamic appearance of blow-out from drilling hole in low gas coal seam in 6198 working face of Panxi Coal Mine is a process of coal body crushing under high stress and then spraying under gas pressure. Internal potential released by coal body and gas internal energy can provide energy for coal body to break and move. Compared with shallow coal seam, threshold of gas expansion energy decreases which causes dynamic appearance of blow-out from drilling hole in deep low gas coal seam.
Analysis of gas characteristics and generation rules of coal spontaneous combustion in goaf
ZHOU Dong, LIU Zhentang, QIAN Jifa, LIN Song, LIU Guanhua
2019, 45(3): 18-22. doi: 10.13272/j.issn.1671-251x.2018090037
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Abstract:
At present，there are few researches on coal spontaneous combustion with different metamorphic degree under environment conditions of simulated gradually heated goaf. Taking 4 kinds of metamorphic coal samples, such as coke lean coal, gas-fat coal, anthracite coal and fat coke coal as example, the experiment of coal spontaneous combustion was carried out by using simulation system of coal spontaneous combustion to study combustion characteristics of coal and generation rules of spontaneous combustion gas under goaf environment. Experiment results show that when coke lean coal, gas-fat coal, anthracite and fat coke coal are warmed up, the temperature will rise "S" type. The early temperature will have a slow accumulation process at first and then start to heat up quickly, and finally tend to balance at 300 ℃, and then slowly rising. Different coal samples produce volatile gases such as hydrocarbons and carbon oxides during the spontaneous combustion process and the rate of formation is affected by temperature, as well as the maximum and minimum two inflection points are present. The temperature rise curve of anthracite coal is similar to a straight line, and the gas curve does not fluctuate obviously with temperature. Large amounts of CO and CH4 are produced in spontaneous combustion of gas-fat coal and fat coke coal, the rate of CO production of gas-fat coal is the fastest, the maximum volume fraction of CO can reach 8%; and the rate of CH4 production of fat coke coal is the fastest, the maximum volume fraction of CH4 can reach 14%. The volume fraction of CO and CO2 produced by coke lean coal and anthracite is about 2% and 4% respectively.
Research on noise and vibration characteristics of shearer
TIAN Zhen, JING Shuangxi, ZHAO Lijuan, GAO Shan
2019, 45(3): 23-28. doi: 10.13272/j.issn.1671-251x.2018090032
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Abstract:
In order to study noise and vibration characteristics of shearer under complicated coal seam occurrence conditions, vibration and noise sources of shearer were analyzed , and conclusions were found: noise of shearer is formed by coupling of different forms of noise, and the vibration caused by the nonlinear instantaneous impact load on the cutting tooth during cutting process is the main source of noise generated by shearer, improving equipment vibration in working process of shearer can effectively reduce noise level of working face. The virtual prototype of shearer cutting unit was established by using co-simulation technology, and the vibration and deformation of key parts were obtained by dynamic simulation analysis: the vibration of the protruding end and the heightening ear of the shell are more violent which seriously affects stability of the drive system and the height adjustment system; the serious distortion and violent vibration of the planetary frame reduce life of axial bearing. In order to reduce vibration of shearer in working process, the shell structure was optimized according to the simulation results. The vibration of the optimized shell is obviously weakened and the mechanical properties are significantly improved. The vibration characteristics of shearer can be effectively improved, the noise level of the working face can be reduced, and the shearer can operate effectively and smoothly.
Mechanical performance analysis of two-prop shield caving hydraulic support
ZHANG Zuozhuang, LI Zhixu
2019, 45(3): 29-34. doi: 10.13272/j.issn.1671-251x.2018090012
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Abstract:
The bed rock of shallow-buried depth coal seam is relatively thinner and the loose layer is thicker, the working face is easy to appear step subsidence and other conditions, and mine rock pressure is severe. The two-prop shield caving hydraulic support used in the working face of shallow buried depth coal seam is prone to insufficient working resistance, poor support for the roof, so as to cause production safety problems. In view of the above problems, using space mechanics analysis and structural finite element analysis, stress state of ZFY12000/25/42D two-prop shield caving hydraulic support suitable for shallow-buried depth coal seams was analyzed under the three most dangerous working conditions of the top beam subjected to eccentric load and loaded on both ends of the base, the top beam subjected to torsional load and loaded on both ends of the base and the top beam subjected to eccentric load and the base subjected to torsional load. The analysis results show that under different working conditions, the stress of each structural member of the hydraulic support will be different, and the stress distribution will be different. From the overall stress distribution of the hydraulic support, the top beam and the base will be subjected to large stresses for interact of the top beam, the prop and the bottom plate, and the front and rear connecting rods and the shield beam as the connecting transition parts will be subjected to less stress; the largest stress of the support is at 712.69 MPa under the working condition of the top beam subjected to torsional load and loaded on both ends of the base; the displacement deformation trend of the support is basically the same, from the top beam to the base, the deformation is gradually reduced, but the overall deformation is good. Under the premise of ensuring structural reliability, high-strength plates are used in the stress concentration part or the thickness of the material is increased to improve the stress distribution of the support and enhance roof-controlling ability of the support, so as to ensure the reliability and stability of the support working.
Design of roadway advanced support and study on its mechanical characteristics
YANG Xinshun, YANG Zhiqiang
2019, 45(3): 35-40. doi: 10.13272/j.issn.1671-251x.2018090020
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Abstract:
In view of problem that there is a big difference between calculated load and real load when roof load is estimated or thin plate theory model is used to study mechanical characteristics of advanced support at present, a new type of roadway advanced support was designed, and the mechanical characteristics of the advanced support were studied according to spatial effect of roadway excavation. Based on spatial effect, the coupling mechanism between advanced support and surrounding rock of roadway was studied, and coupled mechanical model of the advanced support and surrounding rock was built. The research results show that along the direction of roadway excavation, the roof load borne by the roadway advanced support decreases gradually, the closer to the working face, the greater the roof load is, and the front end strength of the advanced support is higher than that of the back end. The support timing of the advanced support is very important for the stability of roadway roof, the closer the advanced support is arranged to the roof of working face, the smaller deformation of the roadway roof will be; while the larger the load borne by the advanced support is, the higher the strength required will be.
Comparative analysis of emulsion pump stations of RMI and KAMAT
YE Jia
2019, 45(3): 41-44. doi: 10.13272/j.issn.1671-251x.2018100041
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Abstract:
Overall structure of KAMAT pump station and RMI pump station which have high domestic market share were introduced. Key technologies in terms of deceleration system, hydraulic system, lubrication system, protection system and control system were comprehensively compared and analyzed. Their respective advantages and disadvantages were summarized, and their improvement directions were pointed out: for KAMAT pump station, processing technology and quality of gear shaft, as well as hydraulic system structure should be improved; for RMI pump station, crankshaft strength of deceleration system should be strengthened, and high-pressure seal module design of hydraulic system and arrangement of suction and discharge valve plug seat should be improved.
Research on visible-near infrared spectrum features of typical coal measures rocks
YANG En, WANG Shibo, GE Shirong
2019, 45(3): 45-51. doi: 10.13272/j.issn.1671-251x.2018090047
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Abstract:
In order to study coal-rock identification method based on visible-near infrared spectrum technology, 11 types of typical coal measures rocks including three main categories namely shale, sandstone and limestone were collected from four coal mines of Shanxi and Shandong provinces. Their reflectance spectra in visible-near infrared band (400-2 450 nm) were measured and influences of mineral and elemental compositions on spectrum features were studied. Differences between reflectance spectrum curves of coal measures rocks and the ones of coals from the four coal mines were analyzed, and influence laws of carbonaceous matter content on characteristic parameters of reflectance spectra curves of coal measures shale were obtained. The study results show that reflectance spectrum curves of the most coal measures rocks show multiple absorption valleys with increasing wavelength in visible light band (400-780 nm) and shortwave near infrared band (780-1 100 nm). In longwave near infrared band(1 100-2 450 nm), distinct absorption valleys are mainly located near 1 400 nm, 1 900 nm, 2 200 nm and 2 350 nm wave length. The wave length of absorption valleys of shale and limestone are relatively fixed while the ones of different sandstones show a variety of changes.Except for carbonaceous shale without distinct absorption features, absorption features of reflectance spectra of coal measures rocks and coals from the same coal mine are obviously different in visible-near infrared band. With increase of carbonaceous matter content of coal measures shale, a common feature is presented that spectral slope of reflectance spectrum curves and depth of each distinct absorption valley in visible-near infrared band both decrease rapidly at first and then tend to be flat.
Numerical simulation of cable fire in coal mine chamber
ZHANG Xiaoyi, WANG Deming, YANG Xuehua
2019, 45(3): 52-55. doi: 10.13272/j.issn.1671-251x.2018060049
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In order to master development and evolution law of cable fire in coal mine chamber, FDS software was used to simulate smoke flow, carbon monoxide concentration, oxygen concentration and temperature during development process of cable fire in coal mine chamber. The results show that: ① With increase of time of cable fire in coal mine chamber, smoke flow will accelerate to spread the whole chamber; carbon monoxide concentration increases firstly, then decreases and finally tends to be stable; oxygen concentration decreases firstly, then increases and finally tends to be stable; temperature increases firstly, then decreases and finally approaches initial temperature. ② Concentration of carbon monoxide and oxygen in return airway fluctuates violently, and temperature fluctuation is relatively small, while carbon monoxide concentration, oxygen concentration and temperature in air inlet roadway are not affected by fire, so the air inlet roadway can be used as a safe escape route. ③ Within 60 s after the fire occurs, smoke flow has a small spreading range and concentrates in middle-upper part of chamber, and carbon monoxide concentration, oxygen concentration and temperature are all within safe range. The best time to escape is within 60 s after the fire occurs.
Position detection method of hydraulic support based on vision measurement
ZHANG Xuhui, WANG Dongman, YANG Wenjua
2019, 45(3): 56-60. doi: 10.13272/j.issn.1671-251x.2018090039
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In view of problems of high cost, poor accuracy and real-time performance in current position measurement methods of hydraulic support used in fully mechanized coal mining face, a position detection method of hydraulic support based on vision measurement was proposed. The infrared LED identification plate is set on the hydraulic support, the explosion-proof camera installed on the shearer is used for image acquisition, and the image is processed and calculated based on the visual algorithm of four coplanar feature points to obtain the position and pose of the hydraulic support base, and the straightness in multiple directions can be obtained according to the position and pose coordinates of the hydraulic support. The experimental results show that the method to measure the detection accuracy of the hydraulic support position is within 0.7°, and the straightness accuracy is less than 20 mm, which meets requirements of accuracy detection of the hydraulic support of fully mechanized coal mining face.
Research on hydraulic buffer system of broken belt catch for downward belt conveyor
CHENG Zhifeng
2019, 45(3): 61-65. doi: 10.13272/j.issn.1671-251x.2018110050
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In order to effectively absorb impact existed in broken belt catch process of downward belt conveyor, a hydraulic buffer system of broken belt catch for downward belt conveyor was proposed. Working principle of the system was analyzed, and a simulation model of the system was established based on AMESim. The influences of opening pressure of relief valve, diameter and length of hydraulic hose, bladder volume and charge pressure of accumulator on displacement and rod cavity pressure of hydraulic cylinder were simulated and analyzed. The simulation results show that the larger the opening pressure of relief valve is, the smaller the displacement of hydraulic cylinder is, and the larger the rod cavity pressure peak of hydraulic cylinder is. The larger the hydraulic hose diameter is, the larger the displacement of hydraulic cylinder is, and the smaller the rod cavity pressure peak of hydraulic cylinder is. However, the influence of hydraulic hose diameter on displacement of hydraulic cylinder decreases when hydraulic hose diameter increases to a certain value. The longer the hydraulic hose is, the smaller the displacement and rod cavity pressure peak of hydraulic cylinder are. The larger the accumulator bladder volume is, the smaller the displacement of hydraulic cylinder is, and rod cavity pressure peak of hydraulic cylinder is unchanged. The larger the accumulator charge pressure is, the larger the displacement of hydraulic cylinder is, and rod cavity pressure peak of hydraulic cylinder is basically unchanged.
Vibration signal denoising method for drive roller bearing of mine-used belt conveyor
YANG Xiang, TIAN Muqin, LI Lu, SONG Jiancheng, ZHANG Linfeng, WU Jingkun
2019, 45(3): 66-70. doi: 10.13272/j.issn.1671-251x.2018080013
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EMD has modal aliasing and ICA requires the number of collected vibration signal should not be less than the number of source signal. In view of the above problems that existed in existing vibration signal denoising method, a vibration signal denoising method for drive roller bearing of mine-used belt conveyor was proposed which was based on EEMD and FastICA. Firstly, collected vibration signal is decomposed by EEMD algorithm, so as to obtain several IMF components at different scales that containing faults characteristic frequency. Then, the IMF components are reconstructed based on correlation coefficient to obtain characteristic signal and virtual noise signal, which are formed into input matrix as input of FastICA algorithm. Finally, FastICA algorithm is used to separate signal and noise to achieve purpose of signal denoising. The experimental results verify feasibility and effectiveness of the method.
Parameter identification of mine-used robot driving system
LI Zhenbi, LI Zhongqiang, LIU Yanbin, XIN Yuanfang
2019, 45(3): 71-74. doi: 10.13272/j.issn.1671-251x.2018030058
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In view of problem of low precision of parameter identification based on least square method, a parameter identification method of mine-used robot driving system based on whale optimization algorithm was proposed. Driving system model of mine-used robot is established to determine parameters to be identified which are considered as individual position of whale colony. Fitness function is used to measure the individual position of whale colony. The optimal identification parameters can be obtained by continuously updating the individual position of whale colony with whale foraging strategy until the optimal individual position of whale colony is obtained. The simulation and experimental results show that the method has higher identification accuracy than the parameter identification method based on least square method.
Double motor driven flip-flow screen and its servo control system
CAO Pei, XIONG Xiaoyan, WU Bing, NIU Linkai
2019, 45(3): 75-81. doi: 10.13272/j.issn.1671-251x.2018100026
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Vibration phase of two screen frames in ordinary flip-flow screen varies in accordance with the change of incoming materials, and phase difference between fixed screen frame and floating screen frame is difficult to maintain at ideal 180 degrees, which leads to low screening efficiency. In view of the above problems, mechanical model and vibration equation of double motor driven flip-flow screen were established, relationship of amplitude and phase between fixed and floating screen frames were obtained, and it was concluded that when speed of double excitation motor was synchronized and phase difference of eccentric block is 170°, vibration phase difference of double screen frames can achieve 180°. Servo control system of double motor driven flip-flow screen was proposed, and cross-coupling-based speed synchronization control method and improved Bang-Bang-based phase compensation control algorithm were used. The simulation results show that the system follows quickly in startup phase with short adjustment time and small overshoot, ideal speed synchronization ; rotation speed and phase compensation speed are fast, absolute value of speed fluctuation amplitude is about 70 r/min, and eccentric block phase difference fluctuation amplitude is controlled within 5°, which verifies the system has strong anti-interference performance.
Multi-objective optimization predictive control of high-power explosion-proof permanent synchronous motor
HE Yuanyuan, GU Mingyue, LIU Ya
2019, 45(3): 82-89. doi: 10.13272/j.issn.1671-251x.2018110057
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In view of problems that traditional multi-objective predictive control method based on weighting method cannot effectively deal with contradiction of objectives and complex design of weight coefficient, a multi-objective optimization predictive control method of high-power explosion-proof permanent magnet motor based on two-layer structure compatible framework was proposed. The d-axis current tracking, q-axis current tracking and midpoint potential balance were divided into compatible optimization layers. By introducing boundary interval, compatible control of the three objectives was effectively realized. Switching loss was divided into optimal optimization layer. A switching frequency measurement method based on extension method was proposed. By approximately measuring switching time of multiple control cycles, average switching frequency of the system was effectively reduced. The simulation results show that the proposed method can achieve compatible control of current command tracking and midpoint potential, and can effectively reduce average switching frequency of the system.
Design of adaptive PID anti-saturation controller in switchover process of mine ventilator
SUN Tao, XIA Zhenxing, WANG Qianjin
2019, 45(3): 90-94. doi: 10.13272/j.issn.1671-251x.2018100013
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In view of actuator saturation problem in switchover process of mine ventiliator, an adaptive PID anti-saturation controller was designed based on combination of variable structure PID anti-saturation control and nonlinear adaptive control. Based on the projection algorithm of dead zone, the linear and nonlinear models of switchover process of mine ventilator were established. A variable structure PID anti-saturation controller was designed respectively for the two models. The operation evaluation indexes of linear and nonlinear adaptive PID anti-saturation controller in different states were calculated, and the controller with smaller evaluation index value was selected for the switchover process control of mine ventilator in this state. The simulation results show that the adaptive PID anti-saturation controller can ensure smooth transmission of underground air volume and solve the problem of actuator saturation.
Influence of cylindrical bending on performance of mine-used wearable half-mode substrate-integrated cavity antenna
LIU Fengxue, CUI Jie, SUN Hong, WEI Mingsheng
2019, 45(3): 95-98. doi: 10.13272/j.issn.1671-251x.17378
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Frequency characteristics, impedance matching and radiation characteristics of mine-used wearable half-mode substrate-integrated cavity antenna under cylindrical bending condition were simulated. The simulation results show that cylindrical bending of the antenna leads to an increase of resonance frequency, but the relative bandwidth of -10 dB is basically unchanged. When radiation aperture is bent, impedance matching of the antenna becomes worse as curvature increases. Cylindrical bending of the antenna results in decrease of forward radiation gain and increase of backward radiation gain. Therefore, in view of application of the antenna under cylindrical bending, cavity size and length or width of conductive bottom should be appropriately increased, and radiation aperture should be kept unbent when selecting placement direction of the antenna.
Research on automatic memory coal caving control
CUI Zhifang, NIU Jianfeng
2019, 45(3): 99-102. doi: 10.13272/j.issn.1671-251x.2018060030
<Abstract>(86) <HTML> (10) <PDF>(7)
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For low coal caving efficiency, poor coal caving quality and other problems existing in manual coal caving control mode of fully-mechanized top coal caving working face, an automatic memory coal caving control method was proposed by referring to memory coal cutting control idea of shearer. Automatic memory coal caving control obtains memory coal caving control data through exemplary learning. Electro-hydraulic control system of hydraulic support controls position and attitude of coal caving mechanisms of hydraulic support according to the memory coal caving control data, so as to realize coal caving quantity control through adjusting coal caving opening degree. Meanwhile, the coal caving quantity is calculated by a relationship model between position and attitude of the coal caving mechanisms and coal caving quantity, so as to correct the memory coal caving control data for avoiding overload of rear scraper conveyer. The method is applicable to top coal caving working faces which have stable coal seam with little thickness change.
Application of full-text search engine in coal mine operation and maintenance system
MENG Feng, JING Cheng
2019, 45(3): 103-108. doi: 10.13272/j.issn.1671-251x.2018110071
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In view of problems of single function and low degree of automation of existing coal mine operation and maintenance system, full-text search engine was applied to coal mine operation and maintenance system, and matching solutions were searched from fault solution database through the search engine. Flow of coal mine operation and maintenance system and source, data structure and entry process of fault solution were introduced. By comparing and selecting, Elasticsearch was selected as the full-text search engine of coal mine operation and maintenance system, and its specific application method was given. Example analysis and test results show that search results provided by the search engine are highly correlated with the faults reflected by the alarm content, which can provide effective help for solving the faults.

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