Experimental Research And Numerical Simulation Simulation Of High Viscous Horizontal Devolatilization Reactor

During the production of polycarbonate,there will produce by-products such as water and phenol.The by-products must be removed in time to ensure the positive progress of the polycondensation reaction.The devolatilizers is important to devolatilization process.Choosing a proper devolatilization equipment will accelerate the devolatilization.The horizontal disc reactor is a typical representatibe of the devolatilization equipment.In this paper,the established of the high-viscosity reactor are the research background.We used hollow disc paddles to study the variation of power characteristic flow characteristics and film formation characteristics in the reactor under different operating conditions.We fitted the dimensionless Np correlation and the film thickness correlation and proposed a method to optimize the operation of the reactor.At the same time,we established a CFD simulation algorithm for high-viscosity devolatilization reactor through Fluent and studied the film formation characteristics shear flow field characteristics and interface flow characteristics in the reactor.The influence of rotation speed viscosity and liquid level on hydrodynamic characteristics was investigated.The results show some points.(1)The stirring power increases with the increase of the blade tip linear velocity u,the material viscosity ?,and the changing amount f.We fitted the power quasi dimensionless relationship.(2)The rotation process of the disc is in accordance with the model of extraction and pressing.When the rotation speed of the disk is too high,the liquid film on the disk will break,so there is a maximum film formation speed of the disk.(3)The liquid holding capacity of the disc becomes larger with the increase of the blade tip linear velocity u and the material viscosity u.The liquid holding capacity increases first and then decreases with the increase of the liquid level height H.The maximum liquid holding capacity appears at the middle liquid level.When ?=860 Pa·s,the maximum liquid holding capacity appears at f=0.296.(4)The film thickness ? increases with the increase of the blade tip linear velocity u and the material viscosity ?.The film thickness ? varies with the liquid level H at different phase angles.The maximum film thickness of?=90°?135°?180° occurs at the low liquid level of H=120 mm.The relationship between ?=0° and R=205 mm dimensionless film thickness was fitted.The numerical simulation results show some points.(5)The axial length will affect the flow field and film formation characteristics in the reactor.The results obtained by the two simulation methods of SRF and SG are not much different,but the calculation speed of SRF is faster and suitable for the complex system of multi-phase flow.The addition of a scraper can greatly reduce the film thickness and accelerate the rate of devolatilization.(6)The liquid phase recirculation speed of the disk pressing area is the largest.The disc opening window enhances the axial flow of the liquid film.(7)The smaller the rotation speed,the higher the viscosity and the higher the liquid level,the larger the film-forming area.Liquid level is the most important factor affecting the film-forming properties of high-viscosity systems.Rotational speed is the most important factor affecting the surface update rate.This paper provides basic data for the design and optimization of industrial high-viscosity devolatilization reactors through cold mold experiments.At the same time,the CFD model and algorithm of the hydrodynamic characteristics of the high-viscosity horizontal devolatilization reactor were constructed,which laid the foundation for the numerical simulation of the industrial high-viscosity horizontal devolatilization reactor.This subject comes from the practical application of the textile industry and has a clear application production value.