Investigation On Solid Particle Movement Influencing Factors Of Liquid-solid Two-phase Flow In Pulp Mixing

The purpose of the slurry stirring is to make the solid particles suspend in the liquid phase,increase the reaction efficiency of the pulp and the medicament,and reduce the loss of the industrial cost.The suspended state of solid particles is affected by many factors,such as the properties of solid particles,the mechanical structure of the mixing tank and the impeller.In order to master the suspension characteristics of the solid particles,people have carried on the thorough research to obtain the critical suspension speed changing with the different influence factor from the experimental research,the solid-liquid suspension mathematical model and so on.At the present,the study of the critical suspension speed affecting factors are based on the single factor,the change of impeller diameter and blade angle were not considered in the mathematical model,and these will affect the correctness of the critical suspension speed.In addition,the relationship between the stirring power and its influencing factors were not studied deeply.Therefore,firstly the influence of the impeller diameter,impeller off-bottom clearance,blade angle,and the fraction of solid mass on the critical suspension speed were investigated from the perspective of two-factors in this paper,and the relationship between various factors and critical suspension speed were analyzed;secondly,the influence of the stirring speed,impeller diameter,impeller angle and leaf number on the stirring power were studied from the perspective of energy consumption;finally,optimum combination of factors affecting the critical suspension speed and the influence factors order queue through orthogonal experiment were analyzed.Matlab software was used to fit the mathematical model between the critical suspension speed and the various factors,which provided the basis for the design and performance optimization of industrial solid-liquid mixing equipment.The experiment results show that the lower impeller off-bottom clearance,the larger blade angle,the lower solid mass fraction and the larger impeller diameter are beneficial to the solid-liquid suspension,and the critical suspension speed-Njs is small.The solid phase suspension effect can be improved when increasing the stirring speed of impeller,but stirring power will be increased and consume more energy.Under the same stirring speed,the power consumption increases with the increase of blade angle,impeller diameter and number of blades.The orthogonal experiment results show that the queue order of the critical suspension speed affecting factors is: the impeller diameter > the blade angle > the particle mass fraction > the impeller off-bottom clearance.The mathematical model between the critical suspension speed and various factors is obtained by Matlab software fitting: 1.400 0.208 0.278 0.426=211jsN D C X ?--? ? ? ?In this paper,the study of the critical suspension speed affecting factors can provide a reference for the study of the suspension mechanism of solid particles in the stirred tank.It also provides a theoretical basis for the design of solid-liquid stirring device in the industrial slurry stirring tanks.