Mechanical Engineering Journal (Jun 2020)
Distribution of particle sedimentation thickness under constant relative centrifugal force in rotating separation system using wireless electrical resistance detector
Abstract
The demand for high separation efficiency needs an advanced device that can be installed in the separation machinery. Parameters in the separation system, such as feeding flow rate and rotational speed, influence the sedimentation formation. A wireless electrical resistance detector (WERD) was developed with an ability to detect the change of the electrical properties of the suspension inside the centrifugal separation domain. The main focus is to observe the particle sedimentation thickness in the specific positions inside an industrial-scale centrifuge. This wireless instrument has an excellent performance in ultra-high rotation operating speed due to its lightweight and flexibility. WERD transmitted the measured resistance to the processing PC, which then processed the data using the particle thickness formula. The code refers to the resistance strength and normalization method under the boundary of the particle volume fraction in the sedimentation state. Simulation and experimental studies solved the constant of the particle thickness formula. In these studies, the sediment layer was represented by the suspended microsphere acrylic particles with a diameter of 10 μm. The suspension was a mixture of the aqueous Sodium Chloride and the acrylic particles. The real-scale experiment was conducted on industrial centrifuge with a constant relative centrifugal force of RCF = 2,130 G. As a result, the distribution of particle sedimentation thickness during the centrifugation was successfully observed by WERD. The results showed as the feeding rate increases; the particle sedimentation thickness increased up to near the feeding point. Under constant relative centrifugal force, the particle distribution rate under a low feeding flow rate gave a smoother thickening distribution. In the high feeding flow rate, the distribution was thicker and faster especially at the position nearer to the feeding point. These findings of the WERD application is useful for the non-invasive sedimentation monitoring in the separation system.
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