Dynamic Simulation of Mechanical Solid-Liquid Separation in Centrifuges

以下子项目“机械固液分离离心机的动态模拟”涉及开发一个动态过程模型，用于连续离心机中分离行为和脱水的流程模拟。在前两个供资期间，对PVC的沉降行为、沉积物积累和固体输送的材料功能进行了实验研究。PVC沉积物堆积的研究表明，饱和滤饼的孔隙率近似恒定，材料行为不可压缩。除了材料的实验室测试之外，实验室沉降式离心机的工艺条件和机器参数的逐步变化实验验证了分离行为的瞬时变化与液体的停留时间分布之间的相关性。结果在动态过程模型中产生。该方法将分离行为、停留时间分布和通过螺旋输送机系统的固体输送与材料性质联系起来。建模的基础是不同隔间的相互连接。这允许局部分布的材料特性的解决方案。此外，所提出的方法相结合的沉降行为与泥沙输运通过考虑泥沙半径校正的分离区的体积。在第三个供资期间，将通过粗分散颗粒的脱水、絮凝悬浮液的固结行为以及沉淀和固液分离之间相互联系的流程模拟来扩展动态过程模型。实验室离心机用于确定脱水过程的动力学。脱水动力学过程模型揭示了滤饼在脱水机锥部的输送过程和脱水动力学过程。絮凝颗粒表现出完全不同的材料行为的沉积物积累。滤饼的孔隙率取决于压缩屈服应力，其在实验室离心机中测量。实验研究揭示了压缩屈服应力的材料函数。此外，饱和滤饼的润湿性取决于剪切应力和屈服点。两者都是在环剪切试验机测量，并结合在沉降式离心机中的絮凝浆料的动态过程模型中的压缩屈服应力。与AG Kind集团合作进行沉淀和沉降式离心机的流程模拟，将展示Dysol的效率。这包括通过考虑进入沉淀反应器的细粉的催泪流而将沉淀和固液分离相互连接，并且。这导致整个过程的完全耦合的动态流程图。

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.