Dynamic agglomeration profiling during the drying phase in an agitated filter dyer: Parametric investigation and regime map studies

Ashutosh Tamrakar, Alfeno Gunadi, Patrick M. Piccione, Rohit Ramachandran

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


One of the serious challenges with the operation of an agitated filter dryer (AFD) is the issue of undesired agglomeration which often plagues the unit operation during the agitated drying cycles. Experimental analyses of the lumped powder formation at various operating conditions are now being used to gain insight into minimizing such activity; however, there is still a lack of understanding into the fundamental processes prompting such behavior and the effectiveness of suggested mitigation measures. This study aims to investigate the underlying agglomeration mechanisms induced during the agitated drying phase of an AFD operation. Through parametric study and granule growth regime map analysis, the dynamic drying and agglomeration profiles were studied for a model cohesive powder, micronized acetaminophen, at various process conditions. The granule growth regime map analysis showed that induction and nucleation type of granule enlargement where the dynamics of wetting dictates the formation of granules is predominant during agitated drying. Depending on the amount of time the drying experiment remains in the specific growth regime, the dynamic agglomeration profile differs drastically. In addition, through parametric investigation, the choice of wash solvent and the presence of critical residual moisture content at the start of the drying cycle showed dominant influence on agglomerate formation. Wash solvents which have high fluid viscosity seem to form stronger agglomerates that retain their structure through the drying process. In terms of the amount of residual moisture content, a critical moisture content range is noticeable for different wash solvents where the agglomerates formed possess superior strength. For prevention of agglomerates, such critical moisture levels and use of high viscous solvents must be avoided.

Original languageAmerican English
Pages (from-to)109-123
Number of pages15
JournalPowder Technology
StatePublished - Dec 1 2016

ASJC Scopus subject areas

  • Chemical Engineering(all)


  • Agglomeration issues
  • Agitated drying
  • Golf ball formation
  • Granule growth regime map


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