【作者】 祝超；

【导师】 秦波涛；

【作者基本信息】 中国矿业大学 ， 安全科学与工程， 2016， 博士

【摘要】 煤自燃是煤矿开采的主要自然灾害之一。为防治矿井煤炭自燃,堵漏控风防止煤氧复合是最有效的方法之一。无机固化泡沫是一种新型的堵漏防灭火材料,以粉煤灰和水泥为基材,添加一定的外加剂,通过物理机械的发泡方式,最后形成的具有较强抗压能力的轻质固态泡沫材料。无机固化泡沫具有封堵裂隙漏风严密、可向高处堆积、覆盖均匀、隔热性能好、成本相对低廉等特点,在煤矿现场有着广阔的应用前景。无机固化泡沫产生装置是制备无机固化泡沫材料的关键,其主要部件为:大比重复合浆体搅拌装置、水基泡沫发泡器以及泡沫浆体混合器。本论文开展了无机固化泡沫产生装置的设计原理及实验研究,取得了如下研究成果:(1)复合浆体是由一定比例的粉煤灰、水泥、外加剂与一定比例的水在搅拌装置中搅拌制备而成。针对复合浆体比重大、粘度高、不易混合均匀的特点,设计了一种大比重复合浆体搅拌装置。主要原理是利用螺带螺旋的运动,使复合浆体在搅拌槽中产生强烈的对流和剪切混合作用,增强了复合浆体的湍流程度,使复合浆体在较短时间内实现快速均匀混合。在此基础上,开展了复合浆体混合均匀度的实验研究,提出了复合浆体均匀度的评价指标,得出了充满系数、搅拌时间、水灰比与复合浆体混合均匀度的关系。当水灰比为0.4~0.6时,搅拌时间6~8 min,充满系数为0.55,σ(密度标准差)值最小,混合均匀度最好。(2)基于孔隙式发泡原理,发明了用于制备无机固化泡沫材料的水基泡沫发泡器。表面活性剂稀释液在压风作用下,经填充孔隙率下小上大的多孔介质作用形成压降,持续发泡,这种发泡方式能防止产生的水基泡沫液膜堵塞通道,提高产泡效率。该发泡器主要由泡沫腔室、发泡筒、压缩空气入口管、发泡剂稀释液入口管、水基泡沫出口管以及排放管组成,具有结构简单、成本低廉、易于加工制作的特点。建立了水基泡沫实验系统,确定了水基泡沫制备的评价指标及其测试方法。研究了操作参数即不同的压缩空气流量和发泡剂稀释液流量对产生的水基泡沫性能的影响,得出了在不同压缩空气流量情况下,发泡剂稀释液流量与水基泡沫评价指标之间的关系曲线,为水基泡沫的制备提供了依据。(3)发明了一种能均匀混合水基泡沫和大比重复合浆体的中空螺旋式混合器。设计原理是水基泡沫通过中空螺旋管上的各个水基泡沫出口与混合腔室中的复合浆体逐级混合,能有效降低水基泡沫的破泡率,提高水基泡沫和复合浆体混合的均匀程度。探究了中空螺旋式混合器的混合机理。采用数值模拟的方法对中空螺旋式混合器的结构进行了优化,确定了以不均匀系数COV作为混合性能的评价指标,选定螺旋叶片螺距p、中空螺旋管的直径D、水基泡沫出口直径d作为模拟的因素,对混合器的结构参数做三因素三水平的正交模拟实验,得出混合器的最佳结构参数为:中空螺旋管的直径D=30 mm、螺旋叶片螺距p=100 mm、水基泡沫出口直径d=14 mm。对优化的中空螺旋式混合器的流场、压力降、湍流动能、混合效果进行了分析。(4)建立了无机固化泡沫制备实验系统。基于正交实验设计方法,以混合器转速、水基泡沫流量、复合浆体水灰比、复合浆体流量为实验因素,以无机固化泡沫的发泡倍数(破泡率)以及无机固化泡沫的均匀度作为评价指标,对无机固化泡沫的制备进行了四因素三水平正交实验。提出了利用数字图像处理与分析技术对无机固化泡沫泡孔均匀性进行定量表征的方法,通过Image-Pro Plus软件,获取无机固化泡沫截面的泡孔面积,通过计算划分的子区域泡孔面积的标准差来定量表征泡孔分布均匀程度。该方法的优点是能对无机固化泡沫均匀性进行定量表征,操作简单方便,结果准确可靠。通过对正交实验数据的处理和分析,得出了各因素的影响顺序和最佳的配比。制备无机固化泡沫的最佳工艺参数组合方案为:混合器转速150 r/min、复合浆体流量2 m3/h、水基泡沫流量14 m3/h、复合浆体水灰比0.5。(5)研究了无机固化泡沫的防灭火性能。无机固化泡沫的粘结性能测试表明,无机固化泡沫具有优良的粘结松散煤体的能力。堵漏风性能模拟测试表明,无机固化泡沫材料堵漏风效果显著。阻化性能实验表明无机固化泡沫材料对煤自燃指标气体的产生具有很好的抑制作用。无机固化泡沫扑灭煤堆火实验表明,无机固化泡沫能够覆盖在煤堆表面,沿着煤炭裂隙逐渐渗流到煤堆内部,保持结构形态不变,具有良好的热稳定性和优良的灭火性能。更多还原

【Abstract】 Coal spontaneous combustion is one of the major natural disasters in coal mining. Plugging leaks and controlling wind to prevent coal/oxygen-compounded reactions is the most effective approach for preventing the spontaneous combustion of coal. Inorganic solidified foam is a novel material for preventing coal spontaneous combustion, it is based on fly ash and cement as the base material, adding some admixtures, and through physical and mechanical foaming method, finally formed a compressive capacity of lightweight solid materials. It has characteristics of plugging the wind with good effect, wide coverage, relatively low cost, easy accumulation, enclothe even, so it has broad application prospects in coal mine. Inorganic solidified foam generation device plays a key role in preparing of inorganic solidified foam materials, its main parts are the composite slurry mixing device, aqueous foam generator, foam slurry mixer. This paper carried out the inorganic solidified foam preparation system design optimization and experimental research, research results are as follows:Composite slurry is prepared by a certain proportion of fly ash, cement, admixtures and a percentage of the water in mixing device.The characteristics of composite slurry is high density and difficult to mix uniformity, we designed a high density composite slurry mixing device. Its main principle is to use the screw with a spiral motion, make the composite slurry in the stirred tank produces strong convection and shear mixing effect, enhances the degree of turbulence in the composite slurry, the composite slurry in a relatively short time to achieve rapid mixing. An experimental study is carried out on the mixing uniformity. We proposed to use density standard deviation as a composite slurry evenness index, the influence law of the mixing uniformity on the high density composite slurry mixing device with fill level, mixing time and water cement ratio was obtained. By the analysis, the optimum matching relation of the parameters of the composite slurry mixing device was obtained. When the range of water cement ratio is from 0.4 to 0.6, the range of mixing time is from 6 to 8 min, fill level is 0.55, the mixing uniformity is best.Based on the pore type foaming principle, invented the pore type foam generator, used in the preparation of aqueous foam. Gas-liquid through porous media produce aqueous foam, porosity is gradually increasing from down to up. It mainly consists of the foam chamber, foam tube, compressed air inlet pipe, foaming agent diluent inlet pipe, aqueous foam outlet pipe and the discharge pipe. The foam generator has simple structure, low cost, easy processing and production. The aqueous foam experimental system was established. We determined the evaluation indexes and test methods of the prepared aqueous foam. Operating parameters is studied in the different compressed air flow and foaming agent diluent flow affect the performance of the aqueous foam, obtained the relationship between foaming agent diluent flow and aqueous foam evaluation index curve under different compressed air flow conditions. Provide the basis for the preparation of aqueous foam.We invented a hollow spiral mixer for mixing aqueous foam and composite slurry. Design principle is aqueous foam by means of the various aqueous foam hollow spiral pipe exports with the composite slurry in the mixing chamber mixed by level, and can effectively reduce the bubble broken rate of and increase aqueous foam and composite slurry mixing uniformity. Numerical simulation method is used to optimize the structure of the mixer. We selected the spiral blade pitch p, the hollow spiral pipe diameter D, aqueous foam outlet diameter d as simulation factor, and the three factors three levels orthogonal experiment were done about the structure of mixer. The optimum parameters of the novel mixer are the hollow spiral pipe diameter of 30 mm, the spiral blade pitch of 100 mm, aqueous foam outlet diameter of 14 mm. For the optimal structure of the mixer, we analysed the flow field, pressure drop, turbulent kinetic energy, mixing effect of mixer.The inorganic solidified foam experimental system was established. In order to get the best preparation conditions, an orthogonal test involving rotational speed of mixer, composite slurry flow rate, aqueous foam flow rate, and water/cement ratio was conducted to select the most effective combinational measurement, we used homogeneity and the broken rate of aqueous foam as inorganic solidified foam performance evaluation index. In this experiment, the digital image processing and analysis technique were used to quantitative characterization of inorganic solidified foam bubble holes uniformity, inorganic solidified foam preparation experiment was carried out. The optimum parameters of preparation of inorganic solidified foam combination scheme is rotational speed of mixer of 150 r/min, composite slurry flow rate of 2 m3/h, aqueous foam flow rate of 14 m3/h, water/cement ratio of 0.5.We studied the fire extinguishing performance of inorganic solidified foam. Inorganic solidified foam adhesive curing performance test showed that inorganic solidified foam has good bonding ability of loose coal. Plugging wind performance simulation tests showed that the effect of inorganic solidified foam plugging wind is remarkable.The inhibitor performance experiments showed that inorganic solidified foam with good inhibitory effect of coal spontaneous combustion index gases. Inorganic solidified foam extinguish the coal fire experiments showed that Inorganic solidified foam can cover in the coal pile surface, along the coal fracture seepage gradually into the pile, the structure shape unchanged, with excellent fire performance.更多还原