【作者】 刘宝河；

【导师】 黄培；

【作者基本信息】 南京工业大学 ， 化学工程， 2003， 硕士

【摘要】 结晶是一种从蒸汽、溶液或熔融物中析出晶体的单元操作。结晶过程与许多传统工业有着密切联系。近年来，新材料、信息电子、生物化工、新型能源材料及环境科学等高新技术产品的制备、分离和提纯也越来越有赖于结晶技术的支撑。结晶是一种复杂的多相流过程，取决于平衡热力学和过程动力学。相对于热力学，结晶过程动力学研究进展缓慢，这种状况阻碍了结晶分离技术的工业化应用。目前，随着现代分析测试技术及计算机模拟技术的飞速发展，结晶动力学研究手段更趋先进，相关领域的研究正日趋活跃，结晶技术的应用研究已经成为国际工业界和学术界关注的焦点之一。针对间歇结晶分离技术的研究，本文从简单的无机盐体系着手，以添加晶种硝酸钾水溶液间歇冷却结晶为对象，通过建立先进的实验过程检测装置，研究溶液结晶过程中成核和晶体生长机理，考察过饱和度等条件对成核或晶体生长速率的影响，并在此基础上进一步开展尿苷酸溶析结晶过程的研究。本文首先建立了溶液间歇冷却结晶实验装置，实现结晶器的程序温控和结晶过程溶液浓度与透光率的在线检测。研究了密度法在线测量溶液浓度的方法，确立了20 ℃下硝酸钾水溶液密度与浓度的关系。由晶体粒径分布（CSD）与体系透光率之间的关系设计了透光率在线检测装置，并采用双光路检测，有效地提高了装置的稳定性。为研究溶液结晶过程中成核与晶体生长机理，本文以KNO3-H2O为模型体系，进行了改变晶种添加量的溶液间歇冷却结晶实验。提出了利用浓度模拟来研究添加晶种间歇结晶过程成核和生长的方法。研究发现：添加较少量的晶种体系仍有一定数量的新核生成；随着晶种质量的增加，成核逐渐减弱，过程以晶种的生长为主导。晶种对结晶过程过饱和度的变化产生影响。对于线性冷却溶液结晶过程，较多的晶种能够抑制体系产生过高的过饱和度。在低过饱和度下，体系无明显的新核生成。作为一种重要的生化产品，尿苷酸通常采用溶析结晶方法进行精制。本文建立了尿苷酸溶析结晶实验装置，实现结晶器内温度和溶媒含量的双重控制功能，并实现溶析结晶过程的浓度，透光率和温度的在线测量。在20℃条件下，测定了<WP=4>尿苷酸在乙醇-水混合溶剂中的溶解度和饱和溶液密度，以及混合溶剂质量组成一定时的尿苷酸浓度和溶液密度的关系。通过溶液体积与尿苷酸浓度之间的关系，拟合得到了三元溶液体系尿苷酸浓度与溶液密度的变化关系式：。实验测定了尿苷酸溶析结晶过程的浓度，透光率，推导出晶体线性生长速率方程。将晶体线性生长速率与相对过饱和度关联，得到了晶体生长经验模型的动力学参数，和分别为0.166 μm/min和4.06。根据经验模型参数，从过饱和度角度解释了尿苷酸晶体在低过饱和度下生长缓慢，在高过饱和度下迅速析出的实验现象。更多还原

【Abstract】 Crystallization，as an important unit operation process, is widely used in many traditional industries to obtain solid products with high purity and perfect crystal structures from vapor, solution or melts. With the prompt development and application of new materials, biochemical products and novel energy sources in recent years, it also plays an indispensable role in separating and purifying the final products. As a sophisticated process with multiple flows, crystallization is fundamentally governed by thermodynamics equilibrium and process kinetics. Compared with thermodynamics, kinetics is more complex. The progress in kinetics research lags far behind than that in thermodynamics, which largely impedes the industrialization of crystallization. Recently, with the rapid progress in computer simulation, modern analytic and measurement techniques, some active and efficient methods have been applied to further disclose the mechanisms of crystallization process. Therefore, crystallization and its related fields have become one of the focuses not only on academic but also on industry circles.In this paper, an ideal binary solution was selected as the modeling system to evaluate the effectiveness of the experimental apparatus, the analytical methods and the data treatment. The primary research indicates that the purity of the final product is greatly influenced by the rates of nucleation and crystal growth. Aimed at seeded batch cooling crystallization of potassium nitrate aqueous solution, the mechanisms of nucleation and crystal growth were investigated. Uridine-5’-monophosphate (5’-UMP), an important biochemical product, is generally prepared by solvent out crystallization. To improve the quality and enhance the added value of the final product, some fundamental research on solvent out crystallization were carried out.In order to obtain the information occurred in both liquid and solid phases, a<WP=6>set of self-made apparatus equipped with dynamic light scattering (DLS) units and densitometer was established in this paper. The relationships of DLS vs. the crystal size distribution (CSD) and the density vs. the concentration of the potassium nitrate aqueous solution at 20 ℃ were experimentally determined, respectively. The stability of transmittance on-line measurement was improved efficiently by the dual-optical detection circuit. Moreover, the temperature of the crystallizer was also programmable, which could be controlled accurately on requirement.For investigating the different influences of the nucleation and crystal growth on the crystallization process, a series of seeded batch cooling crystallization experiments were conducted for nitrate potassium aqueous system. A method, which originated in the difference between the real and the simulated concentration, was proposed in this paper. The results indicated that the generation of the new nuclei could not be fully inhibited if insufficient seeds were added to the system. With the increase of the seed load, the nucleation was gradually weakened and crystal growth dominated over the crystallization process. The further analysis indicated that the real influence of seed load on crystallization could be practically attributed to its direct influence on the supersaturation, which is commonly considered as the driving force of crystallization. The level of the supersaturation was greatly inhibited with the increase of the seed load and under the lower level of supersaturation, no new nucleus was observed.Based on the preliminary research performed on batch cooling crystallization for ideal binary system, another setup for solvent out crystallization of 5’-UMP was also established. In this apparatus, the temperature and the amount of the precipitant were automatically controlled. Meanwhile, the solubility of 5’-UMP at 20℃ in alcohol-water mixed solvents and the density of solution were measured simultaneously. On the basis of the data analysis, the relationship between the concentration of 5’-UMP and the density of the solution was<WP=7>presente更多还原