乳化液自动配比系统设计与优化

发布时间：2018-10-10 10:59

【摘要】：乳化液被誉为井下支护设备的血液,在煤矿中有着重要作用。乳化液浓度是影响其使用性能的关键因素,因此需要对配制乳化液的浓度进行准确控制。传统的乳化液手动法配比和机械配比法由于配比精度低,操作复杂等缺点已被逐渐淘汰,现多用自动配液的方式。自动配液系统主要有双缸定比配液系统、自力式自动配比系统、单片机控制配液系统以及PLC控制配液系统。双缸定比配液系统由于缺少传感器,无法对系统的配比浓度进行监控;而自力式自动配比系统由于井下风压、水压不稳定,配比精度无法保障;单片机控制的自动配液系统多为开环控制;而PLC控制的自动配液系统由于浓度传感器在使用过程易受污染影响精度,故设计时不用浓度传感器直接测量,而采用液位传感器的方式对乳化液浓度进行间接测量,实质上乳化液充分混合后,浓度传感器在清洁的情况下对系统乳化液浓度的精度把控远高于液位传感器,因此自动配液系统的改进需解决乳化液充分混合以及浓度传感器污染的问题。基于以上问题,本文对乳化液自动配比系统做了以下几方面的研究。首先对配液装置整体进行了设计,配液装置集乳化液箱和乳化油箱于一体,且为了整体美观,将各类执行机构和传感器都嵌于配液装置内部,各类器件在箱体内部都通过钢管走线并汇总到接线盒内,配液装置整体结构紧凑、简洁、美观。同时对配液装置进行了壁厚优化,在满足使用条件的基础上使箱体轻量化,节省成本的同时减少井下工人劳动量。接着对乳化液混合起关键作用的搅拌器进行数值模拟,比较圆盘式四直叶涡轮搅拌器、圆盘式45°涡轮搅拌器以及开式45°涡轮搅拌器完成配液的混合时间和能量消耗,结果表明开式45°涡轮搅拌器作用下,液箱体内部湍流强度最为均匀,混合完成时间最短以及混合消耗能量最少。同时就搅拌器的不同安装高度对乳化液混合的影响进行了数值分析,当桨叶距底高度为250mm时,乳化液整体混合完成所需时间最短。其次就浓度传感器的堵塞问题进行了探究,不同安装位置以及箱体堵板不同的开孔形式在搅拌器的剪切作用下,都不足以对浓度传感器起到冲洗的作用,故需要设置冲洗装置进行传感器的清洗。通过对比不同喷嘴的轴向速度分布以及传感器感光元件壁面的动压和打击力,得出角型喷嘴形成的壁面动压和打击力最大,并在入口直径为8mm、收缩角α为13°、出口直径d为4mm、出口扩散角β为20°以及入口压力为3MPa的参数条件下对浓度传感器起到良好冲洗效果的结论。最后设计了基于浓度传感器直接测量的自动控制系统,完成了相应程序编写和画面组态。系统经地面试验和实际井下运行验证均取得良好的效果。
[Abstract]:Emulsion is regarded as the blood of underground support equipment and plays an important role in coal mine. The concentration of emulsion is the key factor affecting its performance, so it is necessary to control the concentration of emulsion accurately. The traditional emulsion manual and mechanical proportioning methods have been gradually eliminated because of their low precision and complicated operation. The automatic liquid distribution system mainly consists of two cylinder fixed ratio distribution system, the self-powered automatic matching system, the single-chip microcomputer control liquid distribution system and the PLC control liquid distribution system. Due to the lack of sensors, the system can not monitor the concentration of the system, while the automatic matching system can not guarantee the precision because of the underground wind pressure, the water pressure is unstable and the matching precision can not be guaranteed. The automatic liquid distribution system controlled by single chip microcomputer is mostly open-loop control, and the automatic liquid distribution system controlled by PLC is designed without the direct measurement of concentration sensor because the concentration sensor is easily affected by pollution in the process of use. The emulsion concentration is indirectly measured by the liquid level sensor. In fact, after the emulsion is fully mixed, the concentration sensor controls the accuracy of the system emulsion concentration much higher than the liquid level sensor under the condition of cleaning. Therefore, the improvement of automatic liquid distribution system needs to solve the problems of sufficient mixing of emulsion and contamination of concentration sensor. Based on the above problems, this paper has done the following research on the emulsion automatic proportioning system. First of all, the whole liquid distribution device is designed. The liquid distribution device integrates the emulsion tank and the emulsified oil tank, and for the sake of overall beauty, all kinds of actuators and sensors are embedded in the liquid dispensing device. All kinds of devices are connected to the junction box through the steel pipe inside the box. The whole structure of the distribution device is compact, simple and beautiful. At the same time, the wall thickness of the liquid distribution device is optimized, which makes the box body lightweight on the basis of satisfying the operating conditions, saves the cost and reduces the labor quantity of the underground workers. Then, the mixing time and energy consumption of the four straight blade turbine agitator, the 45 掳disk turbine agitator and the open 45 掳turbine agitator are compared by numerical simulation of the agitator, which plays a key role in the emulsion mixing, and the energy consumption is compared between the four straight blade agitators, the disk 45 掳turbine agitators and the open 45 掳turbine agitators. The results show that under the action of open 45 掳turbine agitator, the turbulence intensity in the liquid tank is the most uniform, the mixing completion time is the shortest and the mixing energy consumption is the least. At the same time, the effect of different installation heights of agitator on the emulsion mixing is analyzed numerically. When the blade height is 250mm, the whole emulsion mixing takes the shortest time. Secondly, the clogging problem of the concentration sensor is explored. The different installation positions and the different opening forms of the box block plate are not enough to wash the concentration sensor under the shear action of the agitator. Therefore, it is necessary to set up a washing device to clean the sensor. By comparing the axial velocity distribution of different nozzles and the dynamic pressure and impact force of the sensor wall, it is concluded that the wall dynamic pressure and impact force formed by the angular nozzle is the largest. When the inlet diameter is 8 mm, the contraction angle 伪 is 13 掳, the outlet diameter is 4 mm, the outlet diffusion angle 尾 is 20 掳and the inlet pressure is 3MPa, a good washing effect is obtained for the concentration sensor. Finally, the automatic control system based on the direct measurement of concentration sensor is designed, and the corresponding program and picture configuration are completed. The system has been tested on the ground and proved to be effective in underground operation.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD350.4

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