CFD Simulation and Optimization of a Cake Filtration System
Authors: Ogunnowo Enoch , Awodele Damilare , Parajuli Vipan , Zhang Ning 
Published: February 2024

Abstract
This study presents a simulation of filter cake formation during the filtration of rice hull ash and liquid mixture using ANSYS Fluent software. Filter cake formation is a crucial process in filtration, and it plays a vital role in determining the filtration efficiency and the quality of the filtrate. Rice hull ash is a byproduct of the rice milling process, and it has been identified as a promising alternative to traditional filter aids due to its low cost and high adsorption capacity. A simulation was performed using a 2D model of a cylindrical filter cake formed on a flat filter surface. The model was developed using the Eulerian approach, and the filtration process was simulated using transient analysis. The particle size distribution of the rice hull ash was considered, and the effect of the particle size on filter cake formation was analyzed. The simulation results were compared with experimental data, and the agreement between the simulation and experimental data was found to be good. The simulation showed that the formation of the filter cake was influenced by several factors, including the particle size of the rice hull ash, the liquid flow rate, and the pressure drop across the filter. The simulation results indicated that smaller particles of rice hull ash resulted in a more compact and uniform filter cake. The effect of the liquid flow rate on filter cake formation was found to be significant, with higher flow rates resulting in a thinner and less uniform filter cake. The simulation also showed that the pressure drops across the filter increased with time, indicating the gradual buildup of the filter cake. The pressure input can also be optimized using the simulation results to determine the optimal pressure drop for a given application. By adjusting the pressure drop, the deposition rate of particles onto the filter surface can be controlled, resulting in a more uniform and efficient filter cake formation. To optimize the pressure drop, the simulation can be used to adjust the operating conditions such as flow rate, particle size distribution, and filter area. The simulation results can be used to determine the optimal operating conditions for a given application, which can result in a more uniform and efficient filter cake formation. The simulation is extended to 3D and incorporates a user-defined function (UDF) to model the adsorption of particles onto the filter surface, which is an important process in filter cake formation. By incorporating this process into the simulation, the accuracy of the filtration process can be improved, resulting in a more realistic representation of the filter cake formation.
This study demonstrates the feasibility of using ANSYS Fluent software to simulate the filtration of a mixture of rice hull ash and liquid and to predict the formation of the filter cake. The simulation results provide valuable insights into the factors that influence filter cake formation and can be used to optimize the filtration process for maximum efficiency and quality of the filtrate. This study aims to improve the efficiency of the filter cake using the pressure input and UDF. By optimizing these factors, filtration efficiency can be improved, resulting in a more uniform and efficient filter cake formation. This has important implications for industrial filtration processes, where efficient and cost-effective filtration is crucial to produce high-quality products. Further studies are needed to explore the full potential of ANSYS Fluent software in optimizing the filtration process and improving the efficiency of filter cake formation.