Fundamentals of applying magnetic effects for particle structure detachment from magnetizable fibers in gas-particle separation processes

• Applicant: Professor Dr.-Ing. Achim Dittler
• Subject Area: Mechanical Process Engineering
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 529328968

Gas cleaning filters are applied to remove solid or liquid particles from the gas phase. Depending on their structure and application, filters can be divided into depth filters and surface filters. While depth filters are typically not regenerated, the regeneration of surface filters is usually achieved by flow reversal of a pressure pulse or flow-reversal, and in special cases also by mechanical shaking or tapping. The use of magnetic effects for detachment of particle structures from collectors is largely unexplored in gas-particle separation technology. Magnetic effects could be used to move entire filter media or individual collectors. While a magnetically induced movement stimulation of an entire medium could regenerate surface filters, the movement stimulation of individual filter fibers would be more conceivable for depth filters. Studies with single fibers have proven useful for investigating the fundamental processes in the field of depth filtration in gas-particle separation technology, which is why this project aims to investigate the fundamentals of structure detachment through magnetic stimulation on a ferromagnetic single fiber and subsequently expand to a fiber array. One-sided fixed single fibers serve as collectors for non-magnetizable particulate material and are magnetized and set in motion by applying an alternating magnetic field. As a result, the particle adhesion forces can be overcome by appropriate acceleration, and the particle structures detach. In a possible filter element made up of many magnetizable fibers, additional collision processes between the loaded fibers could also support regeneration. When magnetizable fibers are used in surface filters, the novel regeneration concept would avoid temporary flow reversal, and no additional mechanical moving components would be necessary within the filter/in the gas stream, which significantly facilitates the system's use at elevated temperatures and in applications where flow reversal is not possible. Furthermore, targeted cleaning of the filter is also possible. Since the detachment of particle structures depends on the structural composition of the particle layer to be detached and the fiber loading, the focus of these studies is on the detachment of different particle structures and the influence of the loading height. By varying the separation parameters, particle structures in the diffusion/transition/inertial range are to be generated. Different types of stress on the particle structures during detachment are expected due to the different structural compositions. The aim of this project is to gain a fundamental understanding of the potential of magnetically induced filter regeneration.

• DFG Programme: Research Grants