果糖结晶过程优化

通过实验筛选得到适合果糖结晶的混合溶剂，利用中通量结晶仪器Crystalline测定了果糖在水-乙醇（水的摩尔分数为0.39）混合溶剂中的溶解度和介稳区，采用Apelblat方程拟合了溶解度数据。基于热力学数据设计了晶种引晶的果糖冷却结晶工艺，过程优化得到的产品收率可达78.2%以上，纯度可达99%以上，晶体形貌规则，表面光滑，粒度分布窄。当晶体粒径大于100 μm时，利用粒度无关生长的粒数衡算方程建立了果糖连续结晶过程的动力学模型，模型表明晶体生长级数大于成核级数。

Optimization of crystallization process of fructose

Mixed solvent (water-ethanol) was screened out for cooling crystallization of fructose. The instrument, Crystalline was used to determine the solubility and metastable zone of fructose in the binary mixed solvent of water-ethanol (mole fraction of water 0.39). The experimental data of solubility were correlated as a function of temperature by using the Apelblat equation. Based on thermodynamic data of fructose crystallization, the cooling crystallization process was designed and optimized, with over 78.2% yield much higher than that by cooling crystallization in aqueous solution and purity higher than 99%. Compared with the commercially available crystalline fructose, the product crystals were of regular shape, high toughness and narrow crystal size distribution. Laser particle size analyzer, Malvern 3000 was used to determine the continuous crystallization kinetics of fructose, and the crystallization kinetics equation was built by the model of population balance equation proposed by Larson and Randolph and was of size-independent growth with particle size larger than 100μm. The exponent of growth rate was bigger than that of nucleation rate and the crystals tended to grow rather than to nucleate in this size range.