【作者】 王胜群；

【导师】 李军；

【作者基本信息】 四川大学 ， 化学工艺， 2001， 硕士

【摘要】 在杀虫单生产中，最后一步工序是结晶，长期以来，由于缺乏对结晶过程的研究，产品质量，如晶体的粒度分布、晶体形态和纯度等一直无法达到满意的要求。因此，研究结晶过程对杀虫单生产非常重要。 本文首先用实验测定了杀虫单结晶体系的介稳区宽度，并在此基础上针对有机高粘度、扩散控制的结晶过程进行了介稳区宽度的理论计算，两者结果较为接近，说明此计算方法是可行的，能够为工业结晶提供一个可靠的过饱和度范围。其次，作者研究了几种添加剂(表面活性剂)对杀虫单结晶形态的影响，结果证明添加剂L5在30ppm的浓度下效果很好，晶体形态变为较粗壮的柱状，母液夹带量比不加添加剂时减少了近50％。究其原因，作者认为对晶形的改变是由于添加剂选择性吸附在不同的晶体表面上从而使晶面的生长速率发生变化导致的。并通过测定添加剂对介稳区宽度的影响，表明添加剂L5在适当的浓度下可使体系的介稳区宽度增大，这可从一方面解释晶体粒度增大的原因，同时作者认为可能还有热力学上的某些因素，但具体原因尚不清楚。结晶母液中的主要杂质是氯化钠，杀虫单是一种单钠盐，因此，作者接着研究了杀虫单-氯化钠-水的三元体系相图，并根据相图的分析得出，可以利用氯化钠的盐析效应将杀虫单的产率提高到>80％，这已被实验证实。同时，加入适当的添加剂后，产品纯度可达到95％。最后，作者进行了一些连续结晶实验，并对产品粒度分布的平衡方程进行了离散化处理，考虑了结晶过程的聚结和断裂作用，从对粒度分布的模拟结果看，比直线模拟误差小得多，并从中得出了结晶过程的更接近实际的成核和生长速率，这对设计出合适的连续结晶器有很大帮助。更多还原

【Abstract】 The final process of the industrial production of monomehypo is crystallization. For a long term, the factory can not get a desired product with sufficient quality, crystal size distribution, shape and purity for the lack of study on the crystallization process. So, it is very important to study the crystallization in order to improve the product quality.In this thesis, the author studied the crystallization of monomehypo hi four aspects. Firstly, the metastable zone width was measured through experiments and predicted by theoretical computation respectively. The results of the two methods were comparable and could provide a criterion for the control of the supersaturation in the industrial crystallization. At the same time, the theoretical computation method could be applied to other high-viscous, diffussion-controled crystallization of some organic system. Secondly, the effects of some additives on the morphology of the crystal were studied. One anionic surfactant(L5) was very effective at the concentration of 30 ppm. At the presence of additive L5, the monomehypo crystal became course and the water entrainment decreased by almost 50%. The changes of the crystal morphology were because of the selected-adsorption of additives on different faces of the crystal. Through the comparison of the temperature at which the solution turned turbid with or without additives, it was proved that the metastable zone width was enlarged at appropriate additive concentration. This could partly account for the enlargement of the crystalsize and the author suggested some unclear changes of the thermodynamic parameters might play an important role too. Thirdly, the phase diagram of the ternary system monomehypo-NaCl-ItO was plotted through experiment. By analyzing the phase diagram, the author advised to use NaCl as saltingout agent to increase the yield. The experiments showed that the productivity could be increased to as high as 80% and at the same time, combined with the effects of the additive that was added, the purity of the product was increased to 95%. Finally, the author carried out the continuous crystallization experiments. The CSD of the product were simulated though discretized model of the Equation of Population Balance(EPB) which included the aggregation and breakup effects. It was proved more accurate than linear simulation of the CSD and the actual growth rate and nucleation rate were obtained. All of these were very important for the design of the continuous crystallizer.更多还原