Downflow Bubble Contactor. A
properly designed low pressure
oxygen diffusion system is capable
of effectively transferring in excess
of 90 percent of the oxygen mixed
through the component. One such
system is a downflow bubble contact
oxygenator (DFBC), also
referred to as a bicone or a Speece
cone. The DFBC system consists
of a cone-shaped reactor with a
water and oxygen input port at
the top (Figure 8). As the water
and oxygen bubbles move down
the cone, the flow velocity decreases
until it equals the upward
velocity of the bubbles. This configuration
and mode of operation
provides a long contact time between
the water and bubbles and
nearly 100 per-cent absorption of
the injected gas. The dissolved
oxygen concentration of water
leaving a DFBC can be as high as
25 mg/L given a system pressure
of approximately 10 psi.