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For many technically relevant systems to be crystallised, attrition of crystals due to their impact onto stirrer blades, pumps, etc., is the main source of nucleation. In this study, a new experimental set-up for continuous crystallisation is applied to quantitatively determine attrition model parameters. These parameters are to be used for simulation calculations of technical crystallisers. The apparatus provides the possibility to obtain high supersaturation and large crystals under well-mixed conditions. For this purpose on the one hand, a particular pump is used, which obviates attrition. On the other hand, an impingement device is included in the circulation loop of the FC Crystalliser, in order to mechanically stress the crystals in a well-defined manner. Experimental results and simulations are presented for pentaerythritol-water and for ammonium sulphate-water. The simulations well describe the influence of mechanical stress on the crystal size distribution, whereas the influence of residence time is not well described. |
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