Process efficiency in polymer extrusion: Correlation between the energy demand and melt thermal stability
Process efficiency in polymer extrusion: Correlation between the energy demand and melt thermal stability
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DOI：
10.1016/j.apenergy.2014.08.086
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发表时间：
2014-12-15
期刊：
影响因子：
11.2
通讯作者：
Price, Mark
中科院分区：
文献类型：
--
作者：
Abeykoon, Chamil;Kelly, Adrian L.;Price, Mark
热稳定性在聚合物挤出中非常重要，产品质量取决于挤出机螺杆所达到的熔体均匀度水平。挤出是一种能源密集型工艺，为了以较低的单位成本生产高质量的产品，在保持熔体稳定性的同时优化工艺能耗是必要的。随着世界能源价格在过去几年中迅速上涨，优化工艺能源使用是及时的。在本研究的第一部分中，对挤出机的效率进行了一般性的讨论。在此基础上，探讨了不同工艺设置和螺杆几何形状下聚合物挤出过程中熔体热稳定性与能量需求之间的关系。使用高度仪表化的单螺杆挤出机挤出了一种商品级的聚苯乙烯，该挤出机配备了能耗和熔体温度场测量。此外，还使用离线流变仪观察了实验材料的熔体粘度。结果表明，挤出机的比能量需求(即单位质量聚合物的加工能量)随着产量的增加而降低，同时能量需求的波动也减小。然而，熔体温度与挤出机产量之间的关系是复杂的，温度随熔体流动的径向位置而变化。此外，随着生产量的增加，熔体的热稳定性恶化，这意味着在损害熔体稠度的情况下获得了更高的效率。挤出机螺杆设计对能耗与熔体稠度的关系也有显著影响。总体而言，过程能量需求与热稳定性之间的关系似乎是负相关的，而且本质上也是高度复杂的。此外，在此实现的工艺理解水平有助于为设备的选择和操作条件的设置提供信息，以同时优化能源和热效率。(C)2014年提交人。爱思唯尔有限公司出版。
Thermal stability is of major importance in polymer extrusion, where product quality is dependent upon the level of melt homogeneity achieved by the extruder screw. Extrusion is an energy intensive process and optimisation of process energy usage while maintaining melt stability is necessary in order to produce good quality product at low unit cost. Optimisation of process energy usage is timely as world energy prices have increased rapidly over the last few years. In the first part of this study, a general discussion was made on the efficiency of an extruder. Then, an attempt was made to explore correlations between melt thermal stability and energy demand in polymer extrusion under different process settings and screw geometries. A commodity grade of polystyrene was extruded using a highly instrumented single screw extruder, equipped with energy consumption and melt temperature field measurement. Moreover, the melt viscosity of the experimental material was observed by using an off-line rheometer. Results showed that specific energy demand of the extruder (i.e. energy for processing of unit mass of polymer) decreased with increasing throughput whilst fluctuation in energy demand also reduced. However, the relationship between melt temperature and extruder throughput was found to be complex, with temperature varying with radial position across the melt flow. Moreover, the melt thermal stability deteriorated as throughput was increased, meaning that a greater efficiency was achieved at the detriment of melt consistency. Extruder screw design also had a significant effect on the relationship between energy consumption and melt consistency. Overall, the relationship between the process energy demand and thermal stability seemed to be negatively correlated and also it was shown to be highly complex in nature. Moreover, the level of process understanding achieved here can help to inform selection of equipment and setting of operating conditions to optimise both energy and thermal efficiencies in parallel. (C) 2014 The Authors. Published by Elsevier Ltd.