Particle-shape monitoring and control in crystallization processes

We present a simple technique that can identify suitable data from a noisy signal produced on-line by commercially available image-analysis software. A controller successfully uses this signal to regulate the flow rate of a habit modifier stream to maintain a desired crystal habit. We demonstrate these methods on a simple chemical system: sodium chlorate (NaClO 3 ) crystallization using sodium dithionate (Na 2 S 2 O 6 ) as a habit modifier.