抄録
In industrial cooling crystallization, the knowledge of scale formation is important, because this phenomenon becomes a cause of decreased heat exchange coefficient and productivity loss. However, only a few researches which investigated the dynamic change of scale formation have been reported. This study focuses on crystallization and scale formation dynamics which occur during the cooling operation at start-up of melt crystallization. The methacrylic acid containing 5 wt% of MeOH was linearly cooled with cooling coil and the crystallization phenomenon was observed dynamically. During crystallization, five crystallization processes were newly observed: (i) nucleation in melt bulk, (ii) rapid formation of bulky scale on the surface, (iii) temperature increase and loss/disappearance of suspension crystals, (iv) dissolution of bulky scale, (v) growth of dense layer scale. Since dynamic scale formation in the initial stage of start-up operation became clear, it is expected that these results are useful for designing the start-up operation.
