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Application of Seeding as a Process Actuator in a Model Predictive Control Framework for Fed‐Batch Crystallization of Ammonium Sulphate
Author(s) -
Kalbasenka Alex N.,
Spierings Lukas C. P.,
Huesman Adrie E. M.,
Kramer Herman J. M.
Publication year - 2007
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.200601053
Subject(s) - seeding , supersaturation , seed crystal , crystallization , dissolution , nucleation , sieve (category theory) , suspension (topology) , materials science , crystal (programming language) , scanning electron microscope , chemical engineering , chemistry , analytical chemistry (journal) , chromatography , composite material , crystallography , thermodynamics , mathematics , single crystal , programming language , physics , organic chemistry , combinatorics , homotopy , computer science , pure mathematics , engineering
Seeding is discussed from the viewpoint of reproducible process actuation. Seeded experiments in a 75‐l Draft‐Tube (DT) crystallizer were performed in triplicate to verify reproducibility of the product characteristics. The seeded experiments displayed a significantly improved reproducibility of the results in comparison with the corresponding unseeded batches. Narrow sieve fractions of ground seeds were utilized as a seeding material. The seeds were suspended in a saturated solution before being fed into the crystallizer. It was found that the Crystal Size Distribution (CSD) of crystals suspended in a saturated solution changed during the time of their residence in the seeding vessel. Images taken by the Scanning Electron Microscope (SEM) confirmed that the initial change in the median size was caused by the dissolution of fines. The dissolution was subsequently accompanied by the crystal growth and attrition. An optimal residence time was found. Finally, the influence of the initial supersaturation, the seed load, and the seed size on the product quality was investigated. The experimental studies indicated that the initial supersaturation should be as high as possible yet not high enough to trigger primary nucleation. The lowest admissible sieve fraction and the corresponding minimal seed load were found. The conservatism of the used seeding model with respect to the minimal seed load was addressed.