**Christian Melches, Hermann Plate, Jürgen Schürho**ff **and Robert Buchfink \***

GEA Messo GmbH, 47229 Duisburg, Germany; Christian.Melches@gea.com (C.M.); Hermann.Plate@gea.com (H.P.); Juergen.Schuerhoff@gea.com (J.S.)

**\*** Correspondence: Robert.Buchfink@gea.com; Tel.: +49-2065-903-327

Received: 15 May 2020; Accepted: 22 June 2020; Published: 24 June 2020

**Abstract:** Many processes to produce fine chemicals and precursors of pharmaceuticals are still operated in batchwise mode. However, recently, more producers have taken a change to continuous operation mode into consideration, performing studies and trials on such a change, while some have even already exchanged their production mode from batchwise to continuous operation. In this paper, the stepwise development from an initial idea to industrial implementation via laboratory testing and confirmation is revealed through the example of an organic fine chemical from the perspective of a crystallization plant manufacturer. We begin with the definition of the objectives of the project and a brief explanation of the advantages of continuous operation and the associated product properties. The results of the laboratory tests, confirming the assumptions made upfront, are reported and discussed. Finally, the implementation of an industrial plant using a draft tube baffled (DTB) crystallizer and the final product properties are shown. Product properties such as crystal size distribution, crystal shape, related storage stability and flowability have successfully been improved.

**Keywords:** fine chemicals; continuous crystallization; crystal shape; process design; DTB crystallizer; scale up
