Spray drying modelling based on advanced droplet drying kinetics

Abstract A novel theoretical model of the steady-state spray drying process is presented. The model utilizes two-phase flow Eulerian–Lagrangian approach and involves a comprehensive description of two-stage droplet drying kinetics. Such an approach enables prediction of mass, moisture content and temperature profiles within the spray droplets along with flow patterns of the continuous phase. The developed two-stage spray drying model has been incorporated in on Computational Fluid Dynamics (CFD) package FLUENT™ via user-defined functions and utilized for simulation of the drying process in a short-form pilot-scale spray dryer fitted with a pressure nozzle atomizer. The predicted drying behaviour of the dispersed phase and flow patterns of air velocity, temperature and humidity are compared with the data calculated using the built-in FLUENT drying kinetics model. The results of the numerical simulations demonstrate the considerable influence of the utilized drying kinetics model on the predicted heat and mass transfer in the drying chamber as well as the significant influence of particle-wall boundary conditions on the predicted particle trajectories and residence time. Therefore, a proper modelling of the droplet drying kinetics and realistic boundary conditions are crucial for the numerical representation of the actual spray dryer performance.

[1]  K. Shinohara,et al.  Estimation of Diameter of Granule Prepared by Spray Drying of Slurry with Fast and Easy Evaporation , 2002 .

[2]  Timothy A. G. Langrish,et al.  The assessment of a characteristic drying curve for milk powder for use in computational fluid dynamics modelling , 2001 .

[3]  Avi Levy,et al.  Theoretical Drying Model of Single Droplets Containing Insoluble or Dissolved Solids , 2007 .

[4]  A. Levy,et al.  Theoretical Models of Single Droplet Drying Kinetics: A Review , 2010 .

[5]  P. Kerkhof,et al.  Air flow, temperature, and humidity patterns in a co-current spray dryer: modelling and measurements , 1997 .

[6]  A. S. Mujumdar,et al.  A Parametric Study of the Gas Flow Patterns and Drying Performance of Co-current Spray Dryer: Results of a Computational Fluid Dynamics Study , 2003 .

[7]  A. Levy,et al.  Modeling of Droplet Drying in Spray Chambers Using 2D and 3D Computational Fluid Dynamics , 2009 .

[8]  D. Oakley,et al.  Computational modelling of spray dryers , 1993 .

[9]  Arun S. Mujumdar,et al.  A comparative study of a spray dryer with rotary disc atomizer and pressure nozzle using computational fluid dynamic simulations , 2006 .

[10]  A. S. Mujumdar,et al.  Use of Computational Fluid Dynamics to Evaluate Alternative Spray Dryer Chamber Configurations , 2003 .

[11]  Ireneusz Zbicinski,et al.  Development and experimental verification of momentum, heat and mass transfer model in spray drying , 1995 .

[12]  Liang-Shih Fan,et al.  Principles of gas-solid flows , 1998 .

[13]  Avi Levy,et al.  Droplet–Droplet Interactions in Spray Drying by Using 2D Computational Fluid Dynamics , 2008 .

[14]  Don W. Green,et al.  Perry's Chemical Engineers' Handbook , 2007 .

[15]  FG Frank Kieviet,et al.  Modelling quality in spray drying , 1997 .

[16]  J. Vasseur,et al.  Superheated steam dryer: simulations and experiments on product drying , 2002 .

[17]  Wan Ramli Wan Daud,et al.  CFD Evaluation of Droplet Drying Models in a Spray Dryer Fitted with a Rotary Atomizer , 2008 .

[18]  David F. Fletcher,et al.  Spray drying of food ingredients and applications of CFD in spray drying , 2001 .

[19]  I. Zbiciński,et al.  Conditions for Accurate CFD Modeling of Spray-Drying Process , 2006 .

[20]  M. Sommerfeld,et al.  Multiphase Flows with Droplets and Particles , 2011 .

[21]  David F. Fletcher,et al.  What is important in the simulation of spray dryer performance and how do current CFD models perform , 2006 .

[22]  David F. Fletcher,et al.  USE OF COMPUTATIONAL FLUID DYNAMICS TECHNIQUES TO ASSESS DESIGN ALTERNATIVES FOR THE PLENUM CHAMBER OF A SMALL SPRAY DRYER , 2001 .

[23]  Avi Levy,et al.  Modelling of particle breakage during drying , 2008 .