Simulation of Agglomeration in Spray Drying Installations: The EDECAD Project

Abstract

Spray drying is used for the manufacture of many consumer and industrial products such as instant dairy and food products, laundry detergents, pharmaceuticals, ceramics, and agrochemicals. During spray drying, agglomerates of powder particles are formed which determine the instant properties of the powder. Agglomeration during spray drying is considered to be a difficult process to control. The main cause of this is the complex interaction of the process variables: the atomization process, the mixing of spray and hot air, the drying of suspension droplets and the collision of particles which might lead to coalescence or agglomeration. As a consequence, agglomeration during spray drying is operated by trial-anderror. In an EC-sponsored project, named the EDECAD projects, an industrially validated computer model, using CFD technology, to predict agglomeration processes in spray drying machines is developed. An Euler-Lagrange approach with appropriate elementary models for drying, collision, coalescence and agglomeration of the dispersed phase is used. The main result of the EDECAD project is a so-called ''Design Tool,'' which establishes relations between the configuration of the drying installation (geometry, nozzle selection), process conditions, product composition and final powder properties. The Design Tool is being validated on pilot-plant scale and industrial scale. It will provide an advanced tool for improved design and optimization of spray drying and agglomeration equipment, to improve the quality of products and to increase the productivity of such equipment. This article introduces the background and approach of the project and some preliminary results.

One-dimensional simulation of co-current, dairy spray drying systems – pros and cons

“…Several publications have comprehensively reported how 2-D and 3-D simulation approaches using various CFD packages (e.g. Fluent and CFX) can be helpful to predict agglomeration behavior during spray drying [33,49,97], evaluate particle trajectories [11], design new drying chamber configurations and assess atomizer performance [11,[36][37][38] as well as to study gas distribution within drying chambers [11,28,33,34,45,50,53,68,93,101,111]. The accuracy of prediction by finerscale approaches mainly depends on the selection of mass-heat-momentum conservation equations, the accuracy of turbulence models, the appropriateness of numerical methods used for solving equations and the quality of grid generation and algorithm development [28,47,50].…”

An overview of the recent advances in spray-drying

“…Main reason for this is the complex interaction of the process variables, e.g., atomization, contact between the atomization zone and the drying medium, and drying kinetics of the droplets and particles. Verdurmen et al [57] carried out the well-known EDE-CAD project designed to develop an industrial computation model for predicting agglomerations in a spray dryer using CFD.…”

“…Stochastic and direct simulation Monte Carlo collision and coalescence models approaches were implemented in the CFD codes they developed [2,48,57]. The "Design" tools developed by EDECAD project were validated in a pilot spray dryer [59].…”

“…In order to validate droplet collision and coalescence models, the experiments on spray interaction were carried out [41,57]. Stochastic and direct simulation Monte Carlo collision and coalescence models approaches were implemented in the CFD codes they developed [2,48,57].…”

Modeling of Drying Curves of Silica Nanofluid Droplets Dried in an Acoustic Levitator Using the Reaction Engineering Approach (REA) Model

“…Moreover, in recent years, the spray drying process has become a frequent subject for computational fluid dynamics (CFD) modeling [6,7]. However, it is important to be able to correctly model the drying kinetics of the suspended droplets in order to predict the performance of a spray dryer.…”