Experimental study on optimal operation of an actual-size batch crystallizer

间歇结晶可用于小规模生产各种精细化学品。它在操作上具有灵活性。但是，长期以来所期望的控制晶体尺寸的方法尚未建立。在本研究计画中，使用大型与小型批次冷却结晶器，实验性地研究了晶种对产物结晶尺寸分布的影响。本研究的目的是建立晶体尺寸控制的方法。实验工作是用钾明矾系统进行的。作为冷却方式，主要采用淬火（自然冷却）方法。首先，在小型结晶器（12 L）上考察了晶种加入量和溶液初始浓度对产物粒度分布的影响。发现在足够的温度下，产物晶体的粒度分布趋于单峰 ...更多信息 h接种超过临界种子浓度。在此条件下，产物晶体均为生长的晶种。对于高初始浓度的溶液，获得了相同的结果。此外，在上述实验的基础上，通过测定细晶的生成率，明确了晶种对结晶器（600L）的影响机理。细晶体的附聚（或粘附）到晶种和短时间的高过饱和度被证明起着重要的作用。通过比较淬火方法与其他冷却方式，冷却方式本身并不是产生单峰尺寸分布晶体的重要因素。晶种量是影响结晶器性能的重要因素。本研究结果可望推广应用于生产可控尺寸晶体的间歇结晶器的设计。本项目的部分成果已在国际期刊上发表（5篇论文），并在会议和研讨会上发表（16篇论文）。少

Batch crystallization can be used for the production of a variety of fine chemicals in small scale. It has flexibility in operation. But, the method for control of crystal size, which has been long desired has not be established yet. In this research project, the effect of seeding on the product crystal size distribution was investigated experimentally using both large and small scale batch cooling crystallizers. The aim of this research was to establish the method for crystal size control. Experimental work was made with the potassium alum system. As a cooling mode, quenching (natural cooling) method was mainly employed. For comparison, the other methods, linear and controlled cooling methods, were also tested.At first, a small scale crystallizer (12 L) was used to investigate the effect of seed amount and initial solution concentration on the crystal size distribution of product. The size distribution of product crystals has been found to become uni-modal under the condition of enoug … More h seeding over a critical seed concentration. Under this condition, the product crystals were all grown seeds. The same result was obtained for solutions for high initial concentration. Even for the large scale crystallizer (600L) used, the uni-modal crystal size distribution was confirmed similarly to be obtained under the condition of enough seeding.In addition to the above experiments, the generation rate of fine crystals was measured to clarify the mechanism for the seeding effect on the production of uni-modal size distribution. Agglomeration (or sticking) of fine crystals to seed crystals and the short period of high supersaturation were shown to play important roles. By comparing the quenching method with the other cooling modes, the cooling mode itself was shown not to be an important factor in producing crystals of uni-modal size distribution. 'It is the seed amount that plays an important role.The results obtained in this project is expected to be extended to a useful and practical design method of a batch crystallizer for the production of the crystals of controlled size. Part of the results obtained in this project have been published in international journals (5 papers) and presented in meetings and symposia (1 6 papers). Less