矿浆搅拌液固两相流固体颗粒运动影响因素研究

发布时间：2019-05-16 17:00

【摘要】：矿浆搅拌的目的是使固相颗粒全部悬浮于液相中,增大矿浆与药剂的反应效率,进而降低工业上成本的损耗。固相颗粒的悬浮状态受多种因素的影响,如固相颗粒属性、搅拌槽与叶轮机械结构等。为了掌握固相颗粒的悬浮特性,人们进行了深入的研究,从试验研究、固-液悬浮数学模型等方面得到临界悬浮转速随不同影响因素的变化规律。现阶段对于临界悬浮转速影响因素的研究都是针对单因素状态,且在数学模型中没有考虑到叶轮离底间隙和叶片倾角的变化,而这些将关系到临界悬浮转速的正确性。另外,还没有深入研究矿浆搅拌功率与其影响因素之间的关系。为此,本文先从双因素角度考察桨径、叶轮离底间隙、叶片倾角、以及固相质量分数对临界悬浮转速的影响,分析各影响因素与临界悬浮转速的关系;其次从能耗角度研究搅拌转速、桨径、叶片倾角以及叶片数目对搅拌功率的影响;最后通过正交设计试验分析影响临界悬浮转速的最佳因素组合,比较出影响因素的排队顺序。并利用Matlab软件拟合出临界悬浮转速与各因素间的数学模型,为工业固-液搅拌设备的设计、性能优化提供依据。试验结果表明,较低的叶轮离底间隙、较大的叶片倾角、较低的固相质量分数和较大的桨径均有利于固相悬浮,对应的临界悬浮转速Njs较小。增加叶轮搅拌转速能够提高固相悬浮效果,但随着搅拌转速的增大,搅拌功率会增大、消耗更多的能量。在相同的搅拌转速下,功率消耗随着叶片倾角、桨径和叶片数目的增大而增加。正交设计试验研究表明,临界悬浮转速影响因素的排队顺序为:桨径叶片倾角固相质量分数叶轮离底间隙。通过Matlab拟合得到临界悬浮转速与各因素之间的数学模型为:1.400 0.208 0.278 0.426=211jsN D C Xθ--????。通过本文对临界悬浮转速影响因素的研究,可为搅拌槽内固相颗粒悬浮机理的研究提供参考,也为工业矿浆搅拌槽固-液搅拌装置的设计提供理论基础。
[Abstract]:The purpose of slurry stirring is to make all solid particles suspended in liquid phase, to increase the reaction efficiency between pulp and reagent, and to reduce the cost loss in industry. The suspension state of solid particles is affected by many factors, such as solid particle properties, stirring tank and turbomachine structure. In order to master the suspension characteristics of solid particles, the variation of critical suspension speed with different influencing factors was obtained from the aspects of experimental research and mathematical model of solid-liquid suspension. At present, the research on the influencing factors of critical suspension speed is aimed at the single factor state, and the change of impeller bottom clearance and blade inclination angle is not taken into account in the mathematical model, which will be related to the correctness of critical suspension speed. In addition, the relationship between pulp mixing power and its influencing factors has not been deeply studied. In this paper, the effects of paddle diameter, impeller clearance from bottom, blade inclination and solid mass fraction on critical suspension speed are investigated from a two-factor point of view, and the relationship between each influencing factor and critical suspension speed is analyzed. Secondly, the effects of stirring speed, paddle diameter, blade inclination angle and blade number on stirring power are studied from the point of view of energy consumption. Finally, the optimal combination of factors affecting critical suspension speed is analyzed by orthogonal design test, and the queuing sequence of influencing factors is compared. The mathematical model between critical suspension speed and each factor is fitted by Matlab software, which provides the basis for the design and performance optimization of industrial solid-liquid mixing equipment. The experimental results show that the lower impeller bottom clearance, larger blade inclination angle, lower solid mass fraction and larger paddle diameter are beneficial to solid phase suspension, and the corresponding critical suspension speed Njs is smaller. The effect of solid phase suspension can be improved by increasing the stirring speed of impeller, but with the increase of stirring speed, the stirring power will increase and more energy will be consumed. At the same stirring speed, the power consumption increases with the increase of blade inclination, blade diameter and blade number. The experimental results of orthogonal design show that the queue order of the influencing factors of critical suspension speed is the clearance between the impeller and the bottom of the impeller with inclined angle and solid phase mass fraction. The mathematical model between critical suspension speed and various factors is obtained by Matlab fitting as follows: 1.400 0.208 0.278 0.426=211jsN D C X. Through the study of the influencing factors of critical suspension speed in this paper, it can provide a reference for the study of solid particle suspension mechanism in the stirred tank, and also provide a theoretical basis for the design of the solid-liquid mixing device in the industrial slurry mixing tank.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD923

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