Dr.-Ing. Stefan Heisel

Crystallization is a common technique for separation, purification as well as product design of organic compounds. Due to the increasing demand in specific product characteristics, optimization of the crystallization process is of high interest. Crystalline products are widely characterized by the crystal size distribution (CSD); however, no information is given about the agglomeration –the bonding of single crystals by solid bridges - of the crystals.

In this work, the focus is on the agglomeration processes occurring during crystallization. For this matter, a new experimental setup is developed that uses image analysis to make high quality videos of the crystal suspension. Image analysis and sophisticated classification tools that were already developed in the past (Terdenge et al., 2015), are used to distinguish between the different types of crystals. The aim is gain a more detailed understanding of the agglomeration processes and to use this knowledge for optimization of the crystallization process

Dissertation

• S. Heisel
  Contribution to Quantification of Crystalline Product Quality using Image Analysis
  TU Dortmund, 2021, Verlag Dr. Hut, München, ISBN 978-3-8439-4900-2

Paper

• S. Heisel, J. Holtkötter, K. Wohlgemuth
  Measurement of agglomeration during crystallization: Is thedifferentiation of aggregates and agglomerates via ultrasonic irradiation possible?
  Chemical Engineering Science 210 (2019) 115214, doi.org/10.1016/j.ces.2019.115214
   
• S. Heisel, J. Ernst, A. Emshoff, G. Schembecker, K. Wohlgemuth
  Shape-independent particle classification for discrimination of single crystals and agglomerates
  Powder Technology 345 (2019) 425-437, doi.org/10.1016/j.powtec.2019.01.018
   
• S. Heisel, M. Rolfes, K. Wohlgemuth
  Discrimination between Single Crystals and Agglomerates during the Crystallization Process
  Chemical Engineering & Technology 41 (6) (2018) 1218-1225, doi.org/10.1002/ceat.201700651
   
• S. Heisel; T. Kovačević; H. Briesen, G.Schembecker, K. Wohlgemuth
  Variable Selection and Training Set Design for Particle Classification using a Linear and a Non-Linear Classifier
  Chemical Engineering Science 173 (2017) 131-144, doi.org/10.1016/j.ces.2017.07.030
   
• L.-M. Terdenge, S. Heisel, G. Schembecker, K. Wohlgemuth
  Agglomeration degree distribution as quality criterion to evaluate crystalline products
  Chemical Engineering Science 133 (2015) 157-169, doi.org/10.1016/j.ces.2015.03.002

Conference Proceedings

• S. Heisel , M. Rolfes, K. Wohlgemuth
  Image-based discrimination of single crystals and agglomerates during batch cooling crystallization
  Proceedings of the 25th International Workshop on Industrial Crystallization “BIWIC” (2018) 195-200
   
• S. Heisel, J. Schön, A.-L. Diekmann, G. Schembecker, K. Wohlgemuth
  Evolution of the agglomeration degree over time during batch cooling crystallization
  Proceedings of the 24th International Workshop on Industrial Crystallization “BIWIC” (2017) 60-65
  Verlag Dr. Hut, ISBN 978-3-8439-3247-

Oral presentations

• S. Heisel, M. Rolfes, K. Wohlgemuth
  Differentiation of adipic acid aggregates and agglomerates during batch cooling crystallization
  Jahrestreffen der ProcessNet-Fachgruppe “Kristallisation”, Bremen, DEU (2018)
   
• S. Heisel, J. Schön, A.-L. Diekmann, G. Schembecker, K. Wohlgemuth
  Evolution of the agglomeration degree over time during batch cooling crystallization
  24th International Workshop on Industrial Crystallization “BIWIC”, Dortmund, DEU (2017)

• S. Heisel, A.-L. Diekmann, G. Schembecker, K. Wohlgemuth
  Online Investigation of Agglomeration Processes during Batch Cooling Crystallization
  Jahrestreffen der ProcessNet-Fachgruppe “Kristallisation”, Köln, DEU (2017)

Poster presentations

• S. Heisel, M. Rolfes, K. Wohlgemuth
  Image-based discrimination of single crystals and agglomerates during batch cooling crystallization: Necessity of disaggregation for accurate measurement
  25th International Workshop on Industrial Crystallization “BIWIC”, Rouen, FRA (2018)

• S. Heisel, J. Schön, A.-L. Diekmann, G. Schembecker, K. Wohlgemuth
  Online measurement of the agglomeration degree of adipic acid during batch cooling crystallization
  20th International Symposium on Industrial Crystallization “ISIC”, Dublin, IRL (2017)