共查询到17条相似文献,搜索用时 93 毫秒
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综述了聚合物脱挥设备的分类和基本情况,并着重介绍了双螺杆挤出机在聚合物脱挥领域中的应用、优点、国内外发展概况及发展趋势等,同时在大量工业化应用的基础上提出了切实可行的同向双螺杆挤出机脱挥工艺,并详细分析了同向双螺杆挤出机主要零部件的设计要求和设计方法。 相似文献
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根据聚甲醛的生产特点,通过研究双螺杆挤出机的脱除挥发分(简称脱挥)机理,结合聚甲醛实际生产的脱挥工艺,从螺杆组合、螺杆转速、进料量、筒体温度、螺杆长径比等方面分析了影响挤出机脱挥效率的主要因素,给出了适合聚甲醛生产的工艺参数:进料量与螺杆转速的比值维持在18~20,筒体温度为180~195℃,真空度维持在0.01 MPa以下。通过对现有挤出机脱挥系统的优化改造,使脱挥后聚甲醛中甲醛挥发量达100μg/g以下。 相似文献
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聚合物中挥发分含量的不同导致聚合物脱挥过程遵循不同的热质传递机理,基于脱挥过程关键机制开发高能效的聚合物脱挥技术与装备具有重要工程意义。本文分别简述了闪蒸脱挥、起泡脱挥以及扩散脱挥3种脱挥方式的传递机理、过程特征以及过程模型,在此基础上从脱挥工艺和装备两个方面综述了近年来聚合物脱挥过程强化的手段与方法,并系统介绍了栅缝降膜脱挥、超重力旋转强化脱挥、超临界流体辅助脱挥、超声空化强化脱挥等过程强化新技术及其应用现状,提出了未来聚合物脱挥理论与工程实践的研究方向:一方面仍需深入研究扩散脱挥与起泡脱挥的耦合作用机制,建立精准、普适的脱挥过程模型;另一方面指出立式降膜脱挥技术因其能效优势,有望成为未来大规模工业脱挥器的重要选择。 相似文献
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分别研究了二醋酸纤维素塑料水分、增塑剂吸收量及生产过程中螺杆转速、喂料量、螺杆组合对脱挥效率的影响。结果表明,水分作为助脱挥剂,有利于脱挥;增塑剂吸收量高,不利于脱挥;高螺杆转速、低喂料量、排气口前高屏障型螺纹元件均有利于脱挥;挥发分的有效脱除可改善产品通透度和热稳定性;挥发分中60 %以上为邻苯二甲酸二乙酯(DEP)成分;通过设计冷凝系统,实现了挥发分中增塑剂的分离,从而实现了DEP的回收利用。 相似文献
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In this paper we introduce the concept of the length of a transfer unit (LTU) for polymer devolatilization and show that the LTU is an appropriate measure of the effectiveness of the process unit in which the devolatilization operation is conducted. The utility of the concept is demonstrated for the case when the process unit is a twin screw extruder for which values of the LTU were determined from experimentally measured values of devolatilization rates. Values of the LTU were found to depend solely on the fluid mechanics in the extruder as expected and were in good agreement with the predictions of a theoretical expression developed for the system that was studied. Finally, we discuss the implications of the LTU concept in relation to the engineering design and analysis of polymer devolatilization processes. 相似文献
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N. H. Wang 《化学工程与技术》2001,24(9):957-961
Polymer devolatilization, including flash, surface renewal and stripping‐agent‐added techniques in screw extruders, is one of the most important polymer processing technologies. Its development requires an understanding of the relationships among some facts and subjects. Surface renewal devolatilization (SRDV) is a commonly used technique, which includes the two essential elements of film interface area and exposure time. A main feature of SRDV in various types of screw extruders is extrusion devolatilization, in which those elements vary with screw speed and throughput. An extrusion‐devolatilization model for SRDV model has been developed, which solves some important engineering problems encountered in devolatilization. 相似文献
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Ning He Wang 《Polymer Engineering and Science》2007,47(11):1920-1926
The concept of surface renewal for polymer devolatilization (DV) in screw extruder was defined based on the traditional penetration theory, and a measuring criterion and comparing methods for comparing surface renewal devolatilizing performance (SRDP) between different extruders and between different types of extruders were proposed based on this concept and the extrusion–devolatilization theory previously developed by the authors. Their proprieties were further verified by using the literature data obtained in a single screw extruder (SSE) and an intermeshing co‐rotating twin‐screw extruder (ICoTSE). Moreover, the effects of some important screw geometry factors on the SRDPs of both the extruders were discussed, and the comparisons of the SRDPs between them and between types of SSE and ICoTSE were given and discussed. POLYM. ENG. SCI., 47:1920–1926, 2007. © 2007 Society of Plastics Engineers 相似文献
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组合式同向旋转双螺杆特性曲线分析 总被引:3,自引:0,他引:3
应用有限元分析软件ANSYS对同向旋转双螺杆挤出机螺纹输送元件中的三维非牛顿流动进行了模拟,计算出在一定转速和挤出量等工艺条件下螺纹元件的建压能力,确立了一定导程螺纹元件的特性曲线。在此基础上,对组合式同向旋转双螺杆挤出机工作特性进行了分析,并对双螺杆计量段充满长度和排气段脱挥长度的确定作了初步探讨。 相似文献