Suivi en-ligne des procédés de cristallisation en solution en milieux pur et impur par émission acoustique Acoustic On-line monitoring of solution crystallization process in pure and impure media

Many mechanical and physical processes are associated with the generation of acoustic waves produced by the rapid release of energy from localized sources within a material. Acquiring and processing these waves allows non-destructive control of phenomena such as the extension of cracks in a structure under stress, plastic deformation, phase transitions, etc. Few works were devoted in past to acoustic emission (AE) during crystallization processes. Moreover, most available studies are purely descriptive and do not provide results enabling to quantitatively monitor basic crystallization phenomena (i.e., nucleation, growth, agglomeration, etc.) New results dealing with the monitoring of batch solution crystallization operations are presented here. The acquired acoustic signals are interpreted thanks to the joint monitoring of the continuous phase (Measurement of the solute concentration thanks to ATR FTIR spectroscopy) and of the dispersed phase, thanks to the video in situ acquisition of images of crystals in suspension. It is shown that acoustic emission sensors “perceive” the development of the crystallization process and, in particular, that an early detection of the nucleation of crystals is allowed. Analysing the parameters of acoustic waves is shown to allow separate monitoring of basic crystallization phenomena which remain to be identified. As far as online monitoring of industrial crystallization processes is concerned, the measurements thus obtained open promising perspectives. ha l-0 06 60 48 2, v er si on 1 16 J an 2 01 2 Author manuscript, published in "XIII° Congrès de la SFGP 2011 Société Française de Génie des Procédés : Des procédés au service du produit au coeur de l'Europe, Lille : France (2011)"