Crystallization of Glycine by Drowning-Out Combined with Fines Dissolution and Cooling Process with in Situ Control using Focused Beam Reflectance Measurement and Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy

The DFC process (a combined process of drowning-out, fines dissolution, and cooling crystallization) was applied for the crystallization of glycine. The DFC process encourages seed crystals to grow further by the dissolution of fines generated by drowning-out. Therefore, glycine crystals obtained through the DFC process have relatively large size and uniform size distribution with high product yield compared with those obtained by conventional crystallization methods. In the present work, an operating strategy of the DFC process with in situ control was proposed. First, antisolvent is injected until generation of fine particles is assumed to be completed. Second, fines dissolution by heating is conducted until fine particles are mostly dissolved. Here, generation and dissolution of fine particles are monitored by focused beam reflectance measurement and attenuated total reflectance–Fourier transform infrared. The main advantage of the in situ controlled approach demonstrated in the present work is no requirement for any predetermined data and a reduction of the operating time compared with the previously proposed DFC process, in which operating profile is predetermined by the mass balance equations.