智能化放顶煤开采的精确放煤控制技术

Intelligent precise control technology of fully mechanized top coal caving face

综放工作面液压支架引入电液控制系统后,实现了定时放煤和记忆放煤。要适应顶煤层地质变化,还需要引入放煤过程全方位监控技术和装备,实时监测放煤前、放煤中和放煤后的顶煤层静态和动态变化情况,精确控制放煤过程,做到随放随探,才能保证回采率和煤质的最优平衡。首先分析放煤过程监控的技术难点,在于放煤时煤岩粉尘造成视觉成像的信号严重衰减;其次根据放煤量数据判断煤矸放落比例的信号处理时间要求达到秒级,才能满足“见矸关门”决策对控制放煤实时性的要求。按照放煤过程分“放煤前、放煤中和放煤后”3阶段采用不同的感知技术和装备,放煤前采用支架顶梁前部安装透地雷达测量顶煤厚度作为放煤量的基准;放煤中采用在支架顶梁和掩护梁结合处安装三维雷达扫描未放顶煤空间,测量出剩余顶煤体量,与放煤前的放煤量基准进行比对,来确定放煤过程何时终止;放煤后将识别后部刮板运输机上已放落的煤炭体量和煤矸比例,提高煤矸检测的鲁棒性。放煤前测量煤层厚度的雷达采用超宽带无线脉冲信号,能够穿透3~6 m的煤层,测量煤层厚度精度达到厘米级;放煤中对顶煤体量的动态变化检测采用激光雷达或毫米波雷达,能够满足空间测量范围、精度和处理实时性要求;放煤后对煤矸的识别采用高清宽动态摄像机辅以透尘光源,通过图像灰度卷积来计算煤矸混放比例参数,用以判断全煤下放、煤矸混放和全矸下放的3个过程数字量化问题,实现实时反馈控制精确放煤。通过放煤前、中和后3阶段的技术综合,研制相应的传感装备,将测量数据实时传输给工作面自动化系统,经过系统数据计算分析和智能化处理,把放煤控制决策数据发送给液压支架电液控制系统,实现对应支架的放煤口大小及时调整和关闭控制。经过具备条件的智能化综放工作面现场工业试验,验证了采用放煤前中后全过程实时监测手段能够精确地控制放煤口大小和关闭,实现了将现场放煤工人解放到安全条件好的巷道或地面监控中心,达到了综放工作面放煤现场无人操作的智能化目标。

The electro-hydraulic control system for the supports of the fully mechanized top coal caving face has achieved a regular and memorized top coal caving,which cannot adapt to the changes in the geological conditions of roof coal,and it is difficult to guarantee mining rate and coal quality.Through introducing the comprehensive monitoring technology and equipment for the coal mining process,a real-time monitoring of the changes in the roof coal seam before,during and after coal mining,and an accurate control of the coal mining process are proposed to achieve an optimal balance of improving the mining rate and coal quality.Firstly,the technical difficulties of coal mining process monitoring are analyzed.The visual imaging signals are severely attenuated due to coal rock dust brought by coal mining.Secondly,the signal processing time for assessing the proportion of coal rock caving according to the coal mining data is in the order of seconds,which meets the requirement of real-time control for“closing window whenever seeing rock”decision.According to the coal mining process,different sensing technologies and equipment are used in three-phases:“before coal mining,during coal mining,and after coal mining”.Before coal mining,a penetrating radar installed at the front of the roof beam of the bracket is used to measure the thickness of roof coal as the amount of coal.The 3D radar installed between canopy and shield beam scans the caved coal space,measures the remaining roof coal volume,and compares it with the pre-caved coal volume benchmark to determine when the coal mining process ends.After coal caving,the coal volume and coal rock ratio caved on the rear scraper conveyor will be identified to improve the robustness of coal rock detection.The radar that measures the thickness of coal seam before coal mining can use ultra-wideband wireless pulse signals,which can penetrate 3 to 6 m of coal seam,and the accuracy of measuring the thickness of coal seam reaches centimeter level.The dynamic change of the amount of roof coal is detected by laser radar or millimeter-wave radar which can meet the requirements of space measurement accuracy.The coal rock is identified after coal caved by using a high-definition and wide dynamic camera supplemented by a dust-permeable light source.Then the coal and rock gray convolution is used to calculate the coal rock mixing ratio parameter to determine the overall digital quantification of three processes of coal decentralization,mixed rock decentralization and full rock decentralization,realizing real-time feedback control and accurate coal placement.Through a technical integration to three-phases before,during,and after coal mining,the corresponding sensor equipment is developed,and the measurement data is transmitted to the workface automation system in real time.After the data analysis,calculation and intelligent processing of the automation system,the coal mining control decision data are sent to the hydraulic support electro-hydraulic control system to realize the size and closing control of the coal opening of the corresponding support.The field industrial test of the intelligent caving face with conditions has verified that the monitoring of the entire process before,during and after the coal mining is implemented,and the switch of the coal caving window is controlled in real time.The surface monitoring center has achieved the intelligent mining goal of unmanned operation at the underground mine workface.