液固流化床中倾斜板的作用机理研究

发布时间：2018-01-02 22:07

本文关键词：液固流化床中倾斜板的作用机理研究　出处：《中国矿业大学》2016年硕士论文　论文类型：学位论文

【摘要】：针对传统液固流化床处理难选物料效果较差、且其设备处理量有待进一步提高等问题,提出了在垂直段流化床基础上增设倾斜板段从而将流态化作用与倾斜板沉降作用结合起来以改善分离效果的新思路。从颗粒运动动力学的角度阐述了液固流化床中倾斜板对物料沉降、分离过程及处理量提升等方面的作用机理。论文以单一颗粒的自由沉降过程为基础,通过矢量计算、理论推导和几何关系应用相结合的方法,建立了倾斜板通道中颗粒基于自由沉降末速与设备尺寸、上升水速关系的动力学理论模型,描述了颗粒在沉降、分离及临界运动等不同情形下的运动规律。通过自行设计的设备模型机和试验系统对模型进行了验证与修正。提出了利用单一颗粒的速度矢量描述运动规律的思路,并建立了单特性颗粒在倾斜板通道中的运动模型:通过不同粒度的玻璃颗粒(0.2-0.4mm、0.4-0.6mm、0.6-0.8mm)及磁铁矿(0.2-0.3mm、0.3-0.5mm)试验轨迹测定分析,结果表明理论模型计算值与颗粒实际运动规律较接近,在上升水速较低时模型预测越准确,且对大粒度、大密度的物料预测结果更好。引入悬浮液浓度从干扰沉降的角度对模型进行验证和修正,所得表达式为:根据单一特性物料的运动轨迹理论模型,推导出了两种特性颗粒同时沉降分离时的运动位移差异的理论模型:,并提出了倾斜板有效分离长度比和分离效率。提出了利用不同特性颗粒的运动轨迹差异解释流化床中增设倾斜板以提高分离精度的作用机理。通过试验研究发现Lpd随着入料量及水量的增大而变大,但入料量的影响程度要远大于上升水速。倾斜板有效分离长度比k和分离效率η均随着水速的提高而变小、随着入料量的增大而变大,当入料量在50g-200g时,k值约介于2.5-8之间,η值集中在70-90%之间。通过对倾斜板通道中临界颗粒的运动研究,提出了倾斜板对提高处理量的理论表达式1,得到了临界颗粒运动满足的条件:,并以此为基础提出了沉降效率表达式:。通过浓度对临界水速与沉降效率的影响研究发现,临界水速和沉降效率均随入料量增大而变小。最低入料量(50g)时临界水速可达颗粒沉降末速的2.5倍。当入料量为50-400g时沉降效率处于0.45-0.7之间。论文从颗粒运动轨迹的角度,通过模型建立和试验分析,对液固流化床中倾斜板增大处理量及提高分选精度的作用机理进行了定性及定量描述,研究结果对于后续可能的流化床中倾斜板结构设计和操作具有一定的理论意义和实际价值。
[Abstract]:In view of the traditional liquid-solid fluidized bed treatment difficult to choose the material effect is poor, and its equipment treatment capacity needs to be further improved and so on. A new idea to improve separation effect by adding inclined plate section to vertical fluidized bed is put forward. The liquid-solid fluidized bed is expounded from the point of view of particle motion dynamics. Medium inclined plate for material settlement. Based on the free settlement process of single particle, the paper combines the method of vector calculation, theoretical derivation and geometric relation application. Based on the relationship between the final velocity of free settlement and the size of the equipment and the rising water velocity, the dynamic model of the particle in the inclined plate channel is established, and the settlement of the particle is described. The motion law under different conditions, such as separation and critical motion, is verified and modified by the self-designed equipment model machine and test system. The idea of describing the motion law by using the velocity vector of a single particle is put forward. Road. The motion model of single characteristic particles in inclined plate channel was established: 0.2-0.4mm / 0.4-0.6mm glass particles with different sizes were used. (0.6-0.8mm) and magnetite (0.2-0.3mm / 0.3-0.5mm). The results show that the calculated values of the theoretical model are close to the actual movement of particles. The more accurate the model is when the rising water velocity is low, and the better prediction result is for the material with large particle size and large density. The suspension concentration is introduced to verify and revise the model from the angle of interference settlement. The formula is as follows: according to the theoretical model of the motion trajectory of a single characteristic material, the theoretical model of the difference of motion displacement between two characteristic particles when they are separated simultaneously by settlement is derived: 1. The effective separation length ratio and separation efficiency of tilting plate are proposed, and the mechanism of adding tilting plate to improve separation accuracy in fluidized bed is explained by using the difference of motion trajectory of particles with different characteristics. The experimental results show that the separation accuracy can be improved by experiments. Lpd increased with the increase of feed and water content. The effective separation length ratio k and separation efficiency 畏 both decrease with the increase of water velocity and become larger with the increase of feed rate. When the feed volume is 50g-200g, the K value is between 2.5-8 and 畏 value is between 70-90%. The motion of critical particles in the inclined plate channel is studied. The theoretical expression of the tilting plate to increase the handling capacity is put forward, and the conditions of the critical particle motion are obtained as follows: 1. On the basis of this, we put forward the settlement efficiency expression:. Through the study of the influence of concentration on critical water velocity and settlement efficiency, we find out. The critical water velocity and sedimentation efficiency decrease with the increase of feed intake. The critical water velocity can reach 2.5 times of the final velocity of particle settlement. The sedimentation efficiency is between 0.45-0.7 when the feed volume is 50-400g. Through modeling and experimental analysis, the mechanism of increasing treatment capacity and separation accuracy of inclined plate in liquid-solid fluidized bed is described qualitatively and quantitatively. The results are of theoretical significance and practical value for the design and operation of inclined plate structure in the following possible fluidized bed.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD94;TD45

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