Crystallization Rate and Purity of Produced Crystals

结晶率和所产生晶体的纯度

基本信息

批准号：
05650770
负责人：
TOYOKURA Ken
金额：
$ 1.47万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

In industrial crystallization, high purity substance is needed through purification and separation process with saving energy. Concerning separation from cutectic melt, mother melt happens to be included on the surface of crystals, to make the purity lower, and so sweating operation has been selected to improve the purity. In this study, correlation between basic crystallization phenomena and crystal purity wereinvestigated focusing nucleation and growth phenomena, to aim to propose the new theory on the mother inclusion in the process of crystallization, and optimum condition for high purification performance. In this study for the cutectic system of benzene and cyclohexane, experiments of benzene crystallization were performed using semi batch apparatus, to measure the time course of particle size distributions (PSD) and purity of crystals in the determined size range. From the time course of PSD,crystal growth was recognized to proceed by the mechanism of uniting primary nuclei wach … More other and attaching them, and secondary nuclei were observed to be produced periodically. And also crystal purity after wiping operation, was correlated quantitatively with crystal size, to make clear that there are three stages in which (1) formation of small crystals including much mother melt by the agglomeration mechanism of fineparticles, (2) formation of middle sizeone having low content of mother melt : in which find particles are thought to be incorporated into the large crystal, (3) formation of large crystals, in which mother melt are kept between the fine crystals attached to the surface of large crystal. And also batch experiments were performed in the cutectic system of paraxylene and cyclohexane. By the result, initial primary nucleation phenomena affected the purity, and also the mechanism of impurity discharge was shown by our model, considering crystal growth phenomena in the equipment. Based on the result described above, the mechanism and kinetics of impurity inclusion and discharge were considered to propose the optimum crystallization operatin condition for high purification. Less

通过纯化和分离过程，需要通过节省能量来进行工业结晶，高纯度物质。关于与可爱熔体的分离，恰好在晶体表面包含母亲熔体，以使纯度降低，因此选择了出汗的操作以提高纯度。在这项研究中，基本的结晶现象与晶体纯度之间的相关性被对核和生长现象进行了分组，目的是提出有关母亲在结晶过程中包含的新理论，以及高纯化性能的最佳条件。在这项针对可爱的苯和环己烷系统的研究中，使用半批量设备进行了苯结晶的实验，以测量确定尺寸范围内粒径分布（PSD）的时间过程（PSD）和纯度。从PSD的时间过程开始，晶体生长被认为是通过团结原代核WACH的机制来进行的……更多其他并附着它们，并且观察到二次核可以定期生产。擦拭操作后的晶体纯度也与晶体大小相关，以表明在三个阶段中（1）形成小晶体，包括许多母亲，包括许多母亲融化的细粒子的聚集机制，（2）中间尺寸的中间尺寸含量较低的母亲的含量很低：在哪些晶体中融合了大型晶体（3），这是在大型晶体中融合在一起的（3）（3）（3）（3），（3）在（3）中融合了（3）（3）（3）（3），（3）在（3）中融合了（3）（3）（3）（3），（3）是（3），（3）在（3）形成了（3）（3）（3）（3），则是（3），（3）在（3）中融合了（3）（3）。连接到大晶体表面的晶体。并在可爱的甲氧烷和环己烷的可爱系统中进行了批处理实验。结果，我们的模型表明了初始的原代成核现象影响了纯度，并且考虑到设备中的晶体生长现象，也显示了杂质排放的机制。根据上述结果，认为杂质包容性和排放的机制和动力学被认为提出了最佳结晶算子的高纯化条件。较少的