Possible application of membrane-based membrane aeration and deaeration in beer and malt industry
2002
Petrasinovic, N. (Vrsacka Pivara, Vrsac (Yugoslavia)) | Vladisavljevic, G.D.
The oxygenation of water by pure oxygen stream and the removal of dissolved oxygen from water by nitrogen sweep gas were studied in a transverse flow module made with 1058 hydrophilic polysulfone hollow fibers. In the range of water flow rate of 0.3-3 L/h the overall mass-transfer coefficient ranges from 0.52 to 1.8 x 10E-6 m/s, and from 0.77 to 3.7 x 10E-6 m/s for water flow outside and inside the hollow fibers, respectively. For water flow outside the fibers the main resistance to exygen transfer is in the liquid-phase boundary layer, while for water flow inside the fibers the main resistance is in the membrane. The shell-side Sherwood number is proportional to the Reynolds number raised to powers ranging between 0.63 to 0.67. The mass transfer resistance of the membrane at 291 K is 4.7 x 10E-6 s/m, which is three orders of magnitude higher than that for hydrophobic polypropylene hollow fibers. Nevertheless, polysulfone hollow fibers can be successfully used at low water flow rates to reduce dissolved oxygen level in feed water from 8-9 mg/L to less than 0.04 mg/L or to achieve almost complete saturation of water with pure oxygen.
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