Effect of Hydrodynamic and Magnetic Stabilization on Fluidized-Bed Adsorption

Abstract

Direct fermentation broth processing using fluidized beds is extremely advantageous due to the low operating pressure drop of the device and the ability of the bed to process suspended-solids-containing solutions. Unfortunately, the solid particles in fluidized beds typically show a great deal of mixing compared to those in packed beds. This mixing may lead to early breakthrough and inefficient use of adsorptive capacity. Stabilization reduces the solids mixing and improves the performance and efficiency of a fluidized bed. A comparison of packed, fluidized, and stabilized beds reveals that, while normal fluidized beds do contain a significant amount of mixing, the breakthrough behavior of the bed is not drastically different than that of a packed bed. Magnetic stabilization of the bed usually leads to an increase in adsorption efficiency but is dependent on field strength and orientation. Permanently magnetized beds were also investigated and produced breakthrough efficiencies similar to those of packed beds.

Separation of yeast cells from aqueous solutions using magnetically stabilized fluidized beds

“…Accordingly, cell deposition becomes more efficient if channelling or preferential paths for liquid flow are prevented, as the case in horizontal magnetic field stabilization. These results are in agreement with those of Seibert and Burns (1998).…”

“…As a consequence, cell deposition on the particles decreases and a postponement of the breakthrough point occurs as the flow rate increases. These results are in agreement with those of Seibert and Burns (1998) and Tong and Sun (2003). In addition, Odabasi et al.…”

Small-sized dense magnetic pellicular support for magnetically stabilized fluidized bed adsorption of protein

“…So, the efficiency of BSA adsorption in the MSFB was much higher than that in the EB. This exhibits obviously the advantages of MSFB over EB for efficient protein adsorption (Goto et al, 1995;Serbert and Burns, 1998;Tong and Sun, 2003). Moreover, due to the high-density feature of the present MPS, the present MSFB was operated at flow velocities over three times higher than that with a low-density magnetic support (Tong and Sun, 2003).…”

“…This indicates that at the range of lower magnetic field intensity, the increase of the external field intensity could stabilize the bed and reduce the liquid-phase dispersion. However, when the intensity became too strong, it would cause particle alignment and chaining (Serbert and Burns, 1998), aggravating the liquid-phase dispersion. In field intensities higher than 750 Gs, bed collapse was observed in this work.…”

Co-immobilized enzymes in magnetic chitosan beads for improved hydrolysis of macromolecular substrates under a time-varying magnetic field

“…flow regimes that lead to sufficient mass transfer may destabilize the fluidized bed. Magnetically stabilized fluidized beds alleviate this problem using a static (DC) magnetic field to stabilize magnetic particles that carry immobilized enzymes, extending the useable flow regime (Seibert and Burns, 1998). Unfortunately, using the DC field has several drawbacks including flow channeling and even reduced liquid mass transfer compared with that of conventional fluidized beds (Franzreb et al, 2001).…”