共查询到18条相似文献,搜索用时 125 毫秒
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熔融结晶过程的新进展 总被引:15,自引:0,他引:15
本文综述了工业结晶过程的一个主要部分,即熔融结晶过程的新进展。重点介绍了国内外各种新型塔式熔融结晶装置的研究、开发与工业应用的现况;并比较了它们的优缺点。本文对已提出两种基本传递过程的数学模型也做了简单的阐述。 相似文献
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根据结晶学原理,对结晶过程中影响结晶质量的因素进行了讨论,论述了国内外单质炸药结晶控制技术的概况,并对单质炸药结晶控制技术和结晶方法进行了分析和比较。预测了在线颗粒分析系统(FBRM)应用于单质炸药结晶控制中的价值。认为直接从反应液中制得满足使用要求的结晶产品具有较好的工业前景。 相似文献
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运用结晶机理,对DMT结晶工艺条件进行了优化选择,并结合改造实践,对真空结晶工艺进行分析、总结,为工业结晶提高生产能力、节能、降耗、高效运行提供了新的途径。 相似文献
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本研究对间歇冷却结晶过程的数学模型进行了分析,根据动态法测定得到的结晶成核速率B与成长速率G相关于降温速率U的函数关系的经验式,推导出描述过程的状态方程组,协状态方程组及Hamitonian函数,应用Pontryagin极大值原理对过程进行了最优控制条件的计算,建立了一个求解间歇冷却结晶最佳操作时间表安排的新型应用软件.并在DTB型工业规模的结晶器中进行了冷却间歇结晶实验.软件计算结果与实验结果的一致性,充分验证了软件的适用性.本研究所建立的简捷法策略与应用软件可用于指导Ⅱ类结晶物系间歇冷却结晶过程的操作与设计. 相似文献
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介绍了结晶法精制苯甲酸的三种工艺-升华结晶,溶液结晶,熔融结晶。重点评述了熔融结晶法的装置与应用现状,同时展望了苯甲酸精制的未来发展动向。 相似文献
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针对工业结晶过程中的溶液结晶部分,探讨了晶体成核和成长的动力学模型,并对模型的应用情况进行了简单的阐述。 相似文献
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Jürgen Bucko Moriz Mayer Dr. Walther Benzinger Dr.‐Ing. Wolfgang Augustin Prof. Dr.‐Ing. Stephan Scholl Prof. Dr.‐Ing. Roland Dittmeyer 《化学,工程师,技术》2012,84(4):491-502
The advantages of microstructure devices concerning heat and mass transfer are well known. However, the usage of microstructure devices in chemical industry is still limited today. A limitation for industrial application is the liability of microstructures to blocking due to impurity of the fluid or by unintended deposition (fouling) in the microchannels. Fouling can lead to a degradation of the heat transfer performance, to an increase of the pressure drop, to a change of the fluid distribution in the microstructures and to a shorter residence time of the fluid. In the framework of this research project a micro heat exchanger for fundamental experimental investigations on crystallization fouling of CaCO3 in microchannels was developed and manufactured. 相似文献
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通过对溶剂结晶法分离精制豆甾醇工艺进行对比分析,得出工艺简单、适合工业化生产工艺路线。介绍国内外溶剂结晶法(多级分步结晶法、极性溶剂结晶法、有机溶剂结晶法)分离精制豆甾醇的工艺方法并进行对比,可知有机溶剂结晶法中的重结晶法工艺比较简单,非常适合工业化生产。 相似文献
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Manuel Garcia‐Leiner Maureen T.F. Reitman M. Jamal El‐Hibri Ryan K. Roeder 《Polymer Engineering and Science》2017,57(9):955-964
Key relationships between molecular structure and final properties are reported for standard flow and high flow grades of commercially‐available polyetheretherketone (PEEK) resins that differ primarily in molecular weight and molecular weight distribution. Despite similar chemistry and composition, the molecular size‐dependent structural differences associated with the PEEK resins in this study are shown to influence the crystallization rate, final crystallinity, and melt rheology during processing, which subsequently affects mechanical properties, including strength, ductility, and impact resistance. These structure‐property relationships provide fundamental understanding to aid in the design and manufacturing of industrial and medical devices that leverage both the advantages common to all PEEK resins, including chemical and thermal resistance, mechanical strength, and biocompatibility, as well as more subtle differences in crystallization kinetics, melt rheology, ductility, and impact resistance. POLYM. ENG. SCI., 57:955–964, 2017. © 2016 Society of Plastics Engineers 相似文献
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This paper examines antisolvent crystallization under a new perspective and in the unique environment offered by porous hollow fiber membrane devices. The latter are compact, extremely efficient on a volumetric basis, easy to scale up and control. Their inherent characteristics promote the creation of homogeneous concentration conditions on a scale considerably smaller than existing industrial crystallizers without the necessity of a large energy input, properties that are desirable but rarely achieved in industrial crystallizers.Mixing studies were performed to examine the maximum achievable supersaturation in porous hollow fiber devices. It was shown that they are able to offer the supersaturation levels necessary to perform antisolvent crystallization. Moreover, supersaturation is created uniformly due to the large number of feed introduction points, the membrane pores. In addition, radial mixing is substantial in contrast with traditional tubular devices and the characteristic time involved in this process is comparable to the device residence time.Porous hollow fiber antisolvent crystallization of aqueous L-asparagine monohydrate systems proved successful. Mean crystal sizes up to two times smaller compared to batch stirred crystallizers were obtained in standalone membrane hollow fiber crystallizers (MHFC) and their combinations with completely stirred tanks. The CSD was confined below for the former and for the latter, levels that are sufficient for most pharmaceutical crystalline products, for which bioavailability and formulation concerns dictate the desired CSD. In addition, porous hollow fiber devices achieved comparable or slightly higher nucleation rates with respect to batch stirred crystallizers and similar values compared to tubular precipitators. Considerable improvements can be obtained by carefully designing membrane hollow fiber crystallizers. 相似文献
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Crystallization modelling is limited by the availability of methods to reliably predict mixing, temperature and concentration distributions, supersaturation, nucleation and growth kinetics for crystallization systems of industrial size. A new software environment for modelling batch cooling crystallization has been developed integrating crystallization and fluid dynamics. The mathematical model can reliably predict mixing in stirred vessels of a given geometry and its effect on the crystallization kinetics and crystal product properties thus reducing the cost and time required for the design and scale-up of industrial crystallizers. The paper describes the development and application of crystSim for modelling industrial crystallization in stirred tanks. The software is developed in Visual C# making full use of Object Oriented Programming (OOP) and multithreading. 相似文献
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Summary
Detailed knowledge of polymer crystallization kinetics is a mandatory requirement in modeling of transformation processes.
On the other hand, techniques for investigation of crystallization kinetics are limited to cooling rates much lower than those
experienced by the materials in industrial processes. A method suitable to investigate crystallinity evolution during cooling
procedures carried out adopting rates comparable with those experienced by the polymer during industrial processes is thus
extremely attractive.
In this work a method is proposed, based on fast cooling of thin samples by means of air/water sprays and optical detection
of the crystallization phenomenon. Preliminary results of crystallization temperatures detected with a device based on such
a method are presented and, in the low cooling rate range, are compared favorably with calorimetric results. The comparison
of experimental crystallization temperature with results of a kinetics model previously developed leads to satisfactory agreement.
Received: 26 October 2001/Revised version: 12 February 2002/ Accepted: 12 February 2002 相似文献
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现行高纯硫酸生产工艺复杂、能耗大且成本高。降膜结晶法具有绿色环保、节能和工艺简单的优势。采用减压蒸馏、降膜结晶工艺对工业硫酸进行净化提纯,可以制备出达到BV-Ⅲ级的高纯硫酸。最佳工艺条件:1)通过减压蒸馏将工业硫酸中的大部分杂质除去;2)通过降膜结晶获得粗晶体,结晶条件为初始结晶温度-5 ℃、降温步长每10 min降温0.6 ℃、结晶时间80 min、料液流量20 mL/min;3)对粗晶体进行发汗提纯,发汗条件为发汗终温
6 ℃、升温速度3 ℃/h、升温方式每10 min升温0.5 ℃。该工艺在高纯硫酸的制备方面有着广阔的应用前景。 相似文献
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采用平衡法和激光法测定了磷酸二氢钾在水中的溶解度和超溶解度,获得了介稳区宽度数据。结合磷酸二氢钾工业装置的蒸发结晶工艺,讨论了结晶热力学实验数据在磷酸二氢钾生产中的应用,对工业结晶操作条件进行了优化。针对产量为1 000 kg/h的磷酸二氢钾工业结晶过程,得到了最佳的料液循环量、加热蒸汽用量和蒸发器的真空度分别为:50.4 m3/h、1 932 kg/h和0.067 MPa。按照所确定的工艺条件进行结晶操作,可以克服粉状结晶、获得粒度均匀的高品质结晶产品。 相似文献