The surface filtration of oil in water dispersions with imposed fluid rotation
thesisposted on 17.12.2013, 11:46 by Ian D. Smith
The separation of oil in water dispersions is an important process, with research principally concentrating upon polymeric and ceramic filters where the filtration mechanism is predominantly by capture within the depth of the filter. This work utilises novel metal filters which possess a non-tortuous pore channel and so filter by a sieving mechanism. An evaluation of a variety of types of metal surface filters was conducted with a large proportion of the research focusing upon a filter possessing circular pores which open into a conical shape. Rejection of challenging emulsified oil droplets was solely by exclusion due to size at this pore. Enhancement of emulsion filtration was combined with the surface filters using a selection of rod and helical inserts within a tubular filter to modify the flow conditions; in the case of helical inserts to produce a centrifugal velocity upon the less dense oil droplets away from the filter surface. Further filtration enhancement was produced by air backflushing to alleviate fouling of the filter surface and electrolytic generation of bubbles to capture oil drops on bubbles. The latter method increased the overall feed size and should have increased the centrifugal separation by lowering particle or aggregate density. Research is also reported into the mechanism of rejection of emulsified oil droplets using filters with circular pores. The mechanism has been evaluated and shown to depend on the capillary pressure of deformable oil drops impinging upon the pore. A mathematical model is described, which predicts the deformation of drops using the physical properties of contact angle and interfacial tension combined with the properties of pore size, shape and droplet size.
- Aeronautical, Automotive, Chemical and Materials Engineering
- Chemical Engineering