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WET
SCRUBBER |
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Packed
Tower |
DAV
packed tower is built according to the counter-flow
principle: the gas or airstream travels upwards through
the tower, meeting the scrubber liquid - which flows
downwards - on its way.
Migration of unwanted components from gas phase to
liquid phase happens in the packing, where a very
intensive contact between both phases is organized.
The performance of a packed tower scrubber can thus
be improved by using the correct packing.
In a well structured packing, the contact surface
between unwanted gaseous components and the scrubber
fluid is maximized. This enables optimal efficiencies,
and thus low operational costs.
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DAV’s
scrubbers are conservatively engineered. This is particularly
true as it relates to calculations on gas flow through
the column. Generally, gas flow should not exceed
450 ft/min for these systems. Undersized columns operating
at excessive velocity are common sources of operational
difficulties, and are never used on DAV systems. |
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Liquid
Recirculation
Recirculation flow rates of DAV gas scrubbers are 10
to 20 gpm per sq. ft of scrubber cross section. This
assures maximum contact between incoming contaminant
and scrubbing liquid.
Many industrial gas scrubbers recirculate
at too low a rate. This “downsizing” produces
scrubber inefficiency, which is worsened when coupled
with a too-small scrubber column diameter. The result
is over-velocity and under-flow, a combination that
does a disservice to the owner.
DAV systems are engineered for optimum
velocity and flow rates, and maximum operating efficiency,
both short and long-term.
Packing
Depth
In addition to tower diameter and liquid recirculation
rate, consideration must be given to the analysis
required to develop the necessary tower packing depth
for each stage. DAV scrubber designs are based on
considerations that have been field-proven and validated.
DAV scrubbers are built exclusively on hard data from
successful installations.
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In
the venturi scrubber, gas and liquid are fed into
the scrubber in the same direction (co-current manner).
By passing the gas stream through the conical taper
section and through the narrow throat, an area of
high velocity flow and turbulence is created. On leaving
this compressed zone, the gas-liquid mixture expands
as it passes through the conical outlet extension.
In this zone, particles are captured by the scrubbing
liquid at a very high efficiency. In general, the
smaller the particle the greater the pressure drop
required for efficient transfer. |
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| DAV’s
scrubber comes with standard instruments as follow.
1. manometer – to indicate pressure
drop across scrubber.
2. pressure gauge on liquid header – to indicate
nozzle blockage
3. flowmeter on pump outlet – to indicate pump
failure.
With optional instrument as follow
1. thermal couple and digital temperature display on
air outlet – to indicate when scrubber fail to
saturate gas stream.
2. PH metering system – to monitor PH of circulating
liquid for preparation of dosing.
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Copyright
© 2005 DAV ENGINEERING SDN BHD |
