ISBN 9783843945721

978-3-8439-4572-1, Reihe Verfahrenstechnik

Marc Oliver Wittner
Application of Air-Core-Liquid-Ring atomization in spray drying processes: Proof of concept and Methods for process design

193 Seiten, Dissertation Karlsruher Institut für Technologie (2020), Softcover, A5

Zusammenfassung / Abstract

Spray drying is one of the most important techniques for the production of powdered products from liquid sources. As applies for all drying techniques, the main objectives of industrial process improvement are increases in energy efficiency and throughput. In spray drying, the throughput of a spray dryer is limited by its specific water evaporation rate. Moreover, the convective removal of water is very energy consuming and possibilities of internal energy recovery are restricted in spray drying processes. To deal with this challenge, the aim is to increase the feed dry matter content to the highest possible extent prior to the actual spray drying step. Increasing dry matter content, however, poses the challenge of exponential increases in viscosity for most feed liquids. In turn, higher feed viscosities require the application of higher specific energies for droplet formation. Based on first experimental studies, the application of the Air-Core-Liquid-Ring (ACLR) atomization appeared promising in overcoming the described challenges in spray drying of high viscous feed liquids. The ACLR atomizer presents a specific type of internal mixing pneumatic atomizer, which was further developed from an effervescent atomizer (EA). For industrial application, however, ACLR atomization had to be adapted to the requirements of spray drying processes operated at increased levels of dry matter contents. These requirements mainly comprise narrow and constant spray droplet size distributions with specific mean droplet sizes at specific liquid flow.

The main objectives of this thesis were to further investigate the mechanisms of ACLR atomization, to prove the concept of ACLR atomization based spray drying processes and to develop methods for knowledge based design and scale up of ACLR atomizers.