Dynamic Simulation of Mechanical Solid-Liquid Separation in Centrifuges

离心机机械固液分离的动态仿真

• 批准号: 238344535
• 负责人: Professor Dr.-Ing. Hermann Nirschl
• 金额: --
• 依托单位: Arbeitsgruppe Verfahrenstechnische Maschinen (VM)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/238344535?language=en
• 关键词: Dynamic; Simulation; Mechanical; Solid; Liquid

The following sub-project Dynamic Simulation of Mechanical Solid-Liquid Separation Centrifuges deals with the development of a dynamic process model for flowsheet simulations of the separation behaviour and dewatering in continuous centrifuges. During the first two funding periods, material functions for the settling behaviour, the sediment build-up and solids transport of PVC were experimentally investigated. The investigations for the sediment build-up of PVC show incompressible material behaviour with an approximately constant porosity of the saturated cake. In addition to the laboratory tests for the material, experiments for the stepwise change of process conditions and machine parameters for a lab-decanter centrifuge verify a correlation between transient changes of the separation behaviour and the residence time distribution of the liquid. The results yield in a dynamic process model. The approach connects the separation behaviour, residence time distribution and the solids transport by the screw conveyor system with the material properties. The basis of the modelling is the interconnection of different compartments. This allows the solution of local distributed material properties. Moreover, the presented approach combines the settling behaviour with the sediment transport by correcting the volume of the separation zone by considering the sediment radius. In the third funding period, the dynamic process model will be extended by the dewatering of coarsely-dispersed particles, the consolidation behaviour of flocculated suspensions and the flowsheet simulation for the inter-connection between precipitation and solid-liquid separation. A lab centrifuge is used for determining the kinetics of the dewatering process. The cake transport in the conical part of the machine and the dewatering kinetics reveal in the dynamic process model for dewatering. Flocculated particles exhibit a completely different material behaviour for the sediment build-up. The porosity of the cake depends on the compressive yield stress, which is measured in a lab centrifuge. The experimental investigation reveals in the material function for the compressive yield stress. Furthermore, the conveyability of a saturated cake depends on the shear stress and the yield point. Both are measured in a ring shear tester and are combined with the compressive yield stress in the dynamic process model of flocculated slurries in decanter centrifuges. Cooperation with the group of AG Kind for the flowsheet simulation of precipitation and decanter centrifuge will be exhibit the efficiency of Dyssol. This includes the inter-connection of precipitation and solids-liquid separation by taking a tear stream of the fines into the precipitation reactor into account and. This results in a completely coupled dynamic flowsheet of the overall process.

机械固液分离离心机动态模拟的下列子项目涉及开发动态过程模型，用于连续离心机中分离行为和脱水的流程图模拟。在前两个资助期，对聚氯乙烯的沉降行为、泥沙堆积和固体迁移的材料功能进行了实验研究。对聚氯乙烯沉淀物的研究表明，聚氯乙烯是一种不可压缩的材料，其饱和滤饼的孔隙率基本恒定。除了对材料的实验室测试外，对实验室-卧螺离心机的工艺条件和机器参数的逐步改变的实验验证了分离行为的瞬时变化与液体停留时间分布之间的相关性。结果在动态过程模型中产生。该方法将螺旋输送系统的分离行为、停留时间分布和固体输送与物料性质联系起来。建模的基础是不同车厢之间的相互连接。这允许解决本地分布的材料属性。此外，该方法通过考虑泥沙半径来修正分离区的体积，从而将泥沙的沉降行为与泥沙的输移结合起来。在第三个资金期，将扩展动态过程模型，包括粗分散颗粒的脱水、絮凝悬浮液的固结行为以及沉淀与固液分离相互联系的流程图模拟。用实验室离心机测定脱水过程的动力学。脱水机锥体部分的滤饼输送和脱水动力学反映在脱水的动态过程模型中。对于沉积物的堆积，絮凝颗粒表现出完全不同的材料行为。蛋糕的孔隙率取决于压缩屈服应力，这是在实验室离心机中测量的。实验研究揭示了材料函数对压缩屈服应力的影响。此外，饱和滤饼的输送能力取决于剪应力和屈服点。两者都是在环形剪切试验机上测量的，并与卧螺离心机中絮凝泥浆的动态过程模型中的压缩屈服应力相结合。与AG集团合作进行沉淀和卧螺离心机的流程图模拟，将展示Dyssol的效率。这包括通过考虑进入沉淀反应器的细小颗粒的撕裂流来实现沉淀和固液分离的互连。这导致了整个过程的完全耦合的动态流程图。