INTERNATIONAL COLLABORATION STUDY OF THE FLOW THROUGH POROUS MEDIA

Filtration through steady porous beds and fluidised beds are two processes of major importance in operations like liquid and gas filtration, heterogeneous catalysis, or fluidised bed combustion.
University College of Engineering of Vitoria-Gasteiz (Spain) and University College Leuven (Belgium) started a joint project where students and lecturers of both university colleges build an experimental setup for filtration and backwash. With this setup it is possible to comprehend the theory and applications of sand filtration and fluidised beds.
Friction of the liquid with the media particles of a porous or fluidised bed causes the head loss during the process of filtration and backwash. The head loss indicates the need to backwash the filter. For filtration, this is calculated by the Darcy-Weisbach equation and the Ergun equation. With the apparatus the constants in the Ergun equation can be determined experimentally being valid for any system, rate and size, and thus the head loss. For fluidised beds the constants in the Fair-Geyer law can be determined experimentally and thus the head loss only for the specific system.The obliged fluidisation of all the particles (even the coarse particles), allows to determine the minimum rate to do that.
The goal of a second experiment is the determination of the equivalent diameter of several layers of a heterogeneous porous bed. This parameter allows determination of the shape coefficient (lambda), by the ratio between equivalent diameter and the one got from sieving. Furthermore, the knowledge of minimum details of the particles allows to assess ground drainage characteristics, prevention of high head losses in the sand filter first layers and others.