The role of wall deposition and re-entrainment in swirl spray dryers

Victor Francia*, Luis Martín, Andrew E. Bayly, Mark J. H. Simmons

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)
62 Downloads (Pure)


A new experimental method is outlined to study fouling in spray dryers and similar devices. In essence, it makes the deposits traceable so that one can quantify the material that comes off the walls, how long it remains there and how the deposits agglomerate with particles in the air. This paper investigates a countercurrent swirl spray dryer of detergent and provides sound evidence that fouling is a dynamic process: clusters form and break at the walls renewing an active layer of deposits. Remarkably, the wall generates >20% of the product and most of the large granules, and increases drastically the residence time of the powder. The assumptions of current numerical models are clearly invalid (i.e. particles rebound at the wall or deposit indefinitely). Several re-entrainment mechanisms and their times scales are identified in this work, and accordingly, a new general framework to describe fouling in spray dryers is proposed.

Original languageEnglish
Pages (from-to)1804-1821
Number of pages18
JournalAIChE Journal
Issue number6
Publication statusPublished - Jun 2015


  • Deposition
  • Fouling
  • Re-entrainment
  • Resuspension
  • Spray drying

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • General Chemical Engineering


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