Absorption Flashcards
For absorbing a sparingly
soluble gas in a liquid, the ____ should be ____
liquid side
coefficient
should be
increased
For contacting a highly
soluble gas with a liquid
bubble the gas through liquid
Wetted wall tower experiment
determines
Mass transfer coefficient
Channeling is most severe
in towers packed with stacked packing
Stacked packing compared to
dumped packing
gives lower pressure drop
Flooding results in
Low tray efficiency
Operating velocity in a
packed tower is usually
Half the flooding velocity
At the same gas flow rate, the
pressure drop in a packed
tower being irrigated with
liquid
Is greater
than that in dry
packed
Berl saddle made of carbon
cannot be used
in oxidizing
atmosphere
Flooding in a column results
high pressure drop
The operating line for an
absorbed is curved when
plotted in terms of
partial pressure
In case of an absorber, the
operating line
always lies above the equilibrium curve
For an absorber, both
equilibrium and operating line
will be straight for
dilute solution and isothermal operation
In case of an absorber, the
operating
a.) line always lies above the equilibrium curve
Absorption factor is defined
as
slope of the operating line/slope of the equilibrium curve
H2S present in naphtha
reformed gas is removed by
absorbing with
Ethanolamine
If G = insoluble gas in gas
stream and L = non-volatile
solvent in liquid stream, then
the slope of the operating line
for the absorber is
L/G
The minimum liquid rate to
be used in an absorber
corresponds to an operating
line
Tangential to
the equilibrium
curve
Type of tray that is most widely used because of low cost
Sieve or perforated trays
Solute reacts with solvent
Chemical Absorption
Vertical, cylindrical pressure vessel containing one or more packing material
Packed column
Fitted to enhance the removal if absorbent droplets
Demister pad
Most important of all the column internal devices
Liquid distributor
Designed to flow on top of the packed bed
Hold down grid
Type of material that if thin walled, better contact between streams but strength is compromised
Raschig rings
Type of packing materials in random packing that has superior wettability but inferior strength
Ceramics
Expansion of liquid stream due to high gas velocity
Foaming
Unresolved entrainment problems
Flooding
Two phase regime where the gas phase is continuous and it occurs for low weir heights
Spray regime
Used for low efficiency, and highly soluble gaseous contaminants (industrial equipment)
Spray tower
Function is to maintain the desired liquid level on each tray
Weir
Entering gas called
Rich gas
Liquid which takes up one or more components from a gaseous mixture
Absorbent
HTU means
Height of transfer units
Most important component of packed column
Packed bed
A unit operation where a soluble vapor is absorbed from its mixture with an inert gas by means of a liquid in which the solute is more soluble
Gas Absorption
Process of removing gas dissolved in a liquid where the liberated gas is taken up in a gas or vapor in contact with the liquid
Desorption
Tower where liquid flows down over a packing material in a countercurrent or co-current flow with gaseous mixture while one or more of the gaseous components are absorbed in the liquid
Absorption tower
Condition in which the packing surface is not wetted due to low liquid rates
Channeling
Plate column where a gas is absorbed while a gas mixture bubbles through the liquid which passes down from plate to plate
Absorption Column
Excessive build up of liquid on the plates caused by insufficient drainage through the downcomers
Downflow flooding
Upper limit to the rate of gas flow
Flooding Velocity
In loading point, pressure drop start to ___ with ___ gas or vapor velocity caused by rapid increase in liquid hold up.
Increase, increasing
Cylindrical shell filled with small objects to bring about intimate contact between rising fluid and descending liquid
Packed Column Tower
Outer diameter of proprietary rings
Packing diameter
Process in which the liquid is employed to achieve or assist in the removal of dispersed particles from the gas
Scrubbing
In stacked packing, rings were placed ____ each other with vertical axis
Beside
In stacked packing, wooden grids were used in ___
Cross-packed layers
Liquid leaks through the perforations ot valves because of insufficient counter-current gas flow
Weeping
Excessive weeping
Dumping
___ weirs frequently used in low pressure or vacuum columns
Low
___ weirs are used for low liquid loads
Notched (rectangular or v-shaped)
Intersection of OL and EL for which infinite stages is required
Pinch point
In absorption factor, A= L’/mV’, when A is large, the solute tends to be ____
absorbed in the liquid phase
simplified Kremser-Brown absorption equation
Tiller-Tour equation
Method to be used in graphing if one of the lines (OL and EL) is not straight
McCabe-Thiele Method
If the solution is dilute, OL is
Straight
