AGGREGATE STRUCTURE OF FINE POWDER AND COMPACTION PROCESS

Compacting process of fine powder is greatlyaffected by the aggregate structure of particles.Accordingto the experiment in which several kinds of silicon nitrides indifferent partical shape and size were compacted in uniaxualorientation,it is found that the volume compacting rate offorming body differs with the pressure.The aggregatestructure of each sample A,B or C was estimated byapplying Cooper’s equation to the analysis of the compactingprocess of each sample     

食品及包装机械输送机(装置)的张紧机构

本文论述了食品及包装机械输送机(装置)张紧机构造型设计的必要性,并将目前国内外输送装置所采用的张紧机构进行了整理和分类,为设计提供参考资料.     

Impact of shape representation schemes used in discrete element modelling of particle packing

In different computer models, shape is represented using different methodologies, to varying degrees of precision. This paper examines two approaches to shape representation, and their effects on accuracy in the context of cylindrical particle packing. Two discrete element method (DEM) based software packages are used. A X-ray CT scan of a packed bed provides the experimental measurements for comparison. Eight sphere-composite representations of the same cylindrical pellet were tested. Two of these gave results that quantitatively follow experimental measurements. A range of factors that in theory could affect accuracy of the simulation results are examined, including edge roundedness, surface roughness and restitutional behaviour as a function of sphere-composite representations. The conclusion is that, for packing at least, matching the object's overall shape and dimensions is not enough. Only when a high enough resolution is applied to corners and edges, could the sphere-composite approach possibly match the experimental data quantitatively.     

波纹板填料的流体力学性能

应用商用Fluent软件,采用RNG k-?湍流模型,对波纹板填料内三维气相流场进行了数值模拟研究。结果发现,气体从填料底部进入后,大部分气体流入波纹板波谷,并沿波纹板倾角方向流动,此时气体流速较大,压降较小;小部分气体在波纹板波锋区域流动,方向曲折向上,气体流速较小,压降也较大;不同气体动能因子下填料的干板压降模拟值与Billet模型预测值、文献实验数据吻合较好;在理想波纹板填料模型中,气体沿波纹板倾角方向流动碰到塔壁时,转向相邻板片波纹倾角的方向流动,实际应用中容易出现壁流现象。本研究对波纹板填料结构改型及应用具有重要指导意义。     

Computational Fluid Dynamics Simulation of 13CO Distillation in Structured Packing

Physical 3D models were established for corrugated packing used in the enrichment of the isotope ¹³C. Computational fluid dynamics (CFD) simulation results indicated that common corrugated packing was not well wetted when used for isotope distillation. It is concluded that liquid misdistribution in the packed tower results from the structure of the packing rather than from the height of the packing beds. The existence of entrainment was also demonstrated by CFD simulation. It is proved that mass transfer equations based on the Nusselt theory are not suitable for distillation calculation in such a corrugated packing system. By comparison, the recently developed structured packing model with a corrugation geometry based on the right‐angled triangle, known as Zigzag‐pak, describes vapor‐liquid distribution properties well and has significant advantages over common corrugated packing due to its better liquid distribution character.     

中空纤维PVA/PAN复合膜填料的乙醇水溶液精馏性能

以乙醇/水溶液为分离对象,中空纤维PVA/PAN复合膜作为精馏填料,考察了不同膜组件的传质分离效率。实验结果表明:各种组件的分离效率均随塔釜加热功率的增加而减小;和大多数中空纤维膜接触器一样,其总传质系数Ky随中空纤维膜组件填充密度φ的增加而减少;相比于传统精馏填料而言,用中空纤维膜做精馏填料分离乙醇水溶液的分离效果更好,可以在常规填料不能操作的液泛线以上进行操作。当塔釜加热功率为120 W,45根中空纤维膜封装在内径为1.6 cm玻璃管中的传质单元高度(HTU)为5.64 cm。     

多晶硅生产中残液搅拌罐密封结构的改造

在处理多晶硅生产中产生的残液时,残液搅拌罐填料密封出现泄漏,针对此问题提出了优化措施,达到了预期效果。     

规整填料塔技术在尿素解吸塔改造中的应用

通过对氨气提法尿素生产工艺的分析和模拟计算 ,对提出的 2套改造方案进行系统比较 ,确定了最佳改造工艺 ,节省了投资 ,简化了操作 ,使规整填料塔的技术优势得到更大的发挥。     

Marley-600型冷却塔的改造

介绍Marley-600型循环水冷却塔的运行使用情况,利用国产材料和技术改造过程,改造后的冷却效果,改造费用以及目前仍存在的问题。     

丙烯聚合釜密封和传热的设计

介绍了丙烯聚合时反应热量的计算与传热结构的设计,以及一种能可靠运行1年以上的中压填料密封的设计。