The Free On-line Aquaculture Dictionary
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The Free On-line Aquaculture Dictionary |
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| Degassing devices Type Design criteria |
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Degassing required |
Type |
Design
criteria |
Merits
|
|
Carbon dioxide |
Aeration |
Medium or coarse bubbles, 25m3 / hour
air flow rate, distributed as evenly as possible across 1m2
cross sectional area, 0.75m deep, for a flow rate of 3000 lpm |
No head loss, can therefore be included easier into
gravity systems. Not generally as efficient as packed column degassing
(below) |
|
Carbon dioxide |
Atmospheric pressure |
Air flow rate required = 2 x water flow rate. Water
flow rate = 55 litres per second per m2 cross sectional area of
the column/tank (assumes 1.5m high degasser and media surface area of 100
- 200m2m3) |
Very efficient. Additional cost of pumping to top
of degasser increases operational costs. Higher capital costs |
|
Nitrogen |
-100 to -150 mbar gas vacuum |
Air flow rate required = 0.25 x water flow rate.
Water flow rate = 25 litres per second per m2 cross sectional
area of the column/tank. |
Higher capital costs die to reinforcement of vessel
structure due to vacuum. No other effective alternative. |