In this contribution, seeding was applied to fed-batch evaporative crystallization ofammonium sulphate at different crystallizer scales. A scale-up procedure was used to apply the seeding conditions of the least conservative experiment in a 75-1 Draft-Tube (DT) crystallizer, i.e. the experiment with the lowest seed load, to a seeded crystallization in an 1100-1 Draft-Tube-Baffle (DTB) crystallizer. The resulting median crystal size was larger, while the width of the Crystal Size Distribution (CSD) was narrower than those in the 75-1 DT crystallizer. This was attributed to the presence of a fines removal system in the DTB crystallizer. Though the results showed a strong influence of the seeding conditions on the product quality and on the reproducibility of the batches, a further reduction in the seed mass could potentially improve the product quality at the expense of the process robustness to the initial conditions. A tight control of the seed quality and initial supersaturation would be necessary to achieve minimal batch-to-batch variations in the product characteristics.
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