A STUDY OF EXPLANATION OF CRYSTAL GROWTH UNIT IN CRYSTALLIZATION

在工业结晶领域中，晶体粒度分布和纯度的控制是最重要的方面，已经得到了广泛的研究。然而，成核和晶体生长的现象还没有得到很好的理解。因此，本工作采用快速动态光散射法和光学显微镜研究了在落差轴和1g微重力作用下的二次成核过程和随后的晶体生长过程。发现在微重力条件下，溶液中形成的晶体的运动完全被抑制，没有发生碰撞和团聚现象。除种子晶表面外，未发生成核。用快速动态光散射法可以测量出纳米级晶体的数量和尺寸。同时，利用干涉光学显微镜、核磁共振和ESC对生长晶体界面区域的溶液结构进行了观察，以获得晶体生长单元的信息。结果表明，浓度梯度及其区域随溶液的过饱和、结晶方向和离子浓度的变化而变化。根据核磁共振和ESC的结果，推测过饱和溶液中存在分子聚集和络合离子。此外，为了将上述结果应用于晶体产品，我们尝试对间歇式结晶器中产品晶体尺寸分布的控制进行研究，提出了一种利用红外发光二极管和光电姐妹的光传感器原位测量结晶器中不同高度固体浓度的方法。并应用该方法获得了间歇式结晶器中晶体浓度的信息，并在此基础上通过改变搅拌速率来控制晶体的分散。实验结果表明，该系统可以跟踪结晶过程，对晶体尺寸分布的精确控制具有重要意义。少

In the field of industrial crystallization, the control of crystal size distribution and purity is most essential aspect, and has been investigated extensively. However the phenomena of nucleation and crystal growth have not been well understood. Therefore, in this work, the process of secondary nucleation and the subsequent crystal growth process have been investigated both by fast-dynamic light scattering method and optical microscope under the micro gravity in drop shaft and 1 g. It was found that the movement of crystals formed in solution could be suppressed completely in micro gravity, in which collision and agglomeration phenomena did not take place. No nucleation occurred except for the seed crystal surface. Also it could be measured the number and size of produced crystals with order of nano-meter by fast-dynamic light scattering method. Also, to obtain of information for crystal growth unit, the solution structure in the region of interface of growing crystal have been observ … More ed by interference optical microscope, NMR and ESC.It was found that the concentration gradient and that's region appear with the supersaturation, the direction of crystal and addition ion concentration. From the results of NMR and ESC, the existence of molecular conglomeration and complex ions in supersaturated solution was inferred. Still more, to apply to products of crystals the above results, we try to examine for control of the crystal size distribution of products in a batch crystallizer, an in-situ measurement method of solid concentration at different heights in a crystallizer was proposed by using the light sensor with infrared light emitting diodes and phototarnsisters. And this method was applied to get the information about the crystal concentration in a batch crystallizer and to control of crystal dispersion by the change of the agitation rate based on the above information. It was found that this system proposed in this work could follow the crystalization process and was useful the control of the crystal size distribution accuratel. Less