Deals with systems wet scrubbing and dry scrubbing.

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Scrubbing Systems
Dr. Akepati S. Reddy
School of Energy and Environment
Thapar University, Patiala
INDIA

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Categories of Scrubbing Systems
Depending on whether liquid is used for scrubbing or not
categorized as
• Wet scrubbers – liquid is used for scrubbing
• Dry scrubbers – either solid sorbent or slurry is used
Based on the manner of bringing the gas phase in contact
with the liquid phase categorized as
• Gas phase contacting scrubbers – use gas stream energy
• Liquid phase contacting scrubbers – use liquid stream energy
• Wet film scrubbers – use energy of both liquid and gas
streams
• Combination liquid phase and gas phase scrubbers – use
energy of both liquid and gas streams
• Mechanically aided scrubbers – mechanically driven rotors
are used for the contact

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Categories of Scrubbing Systems
Based on gas side pressure drop categorized as
• Low energy scrubbers – pressure drop <5” water column
– spray towers – particles of >5µ size are removed
• Medium energy scrubbers – pressure drop 5-15”
• High energy scrubbers – pressure drop >15” – venturi
and condensation scrubbers
But many scrubbers operate over a wider range pressure drop
Depending on the use categorized as
• Scrubbers primarily used for collecting particles
• Scrubbers primarily used for gaseous pollutants removal
Dry scrubbers are categorized as
• Dry sorbent injectors (DSI)
• Spray dryer absorbers (SDA) – also known as semi-dry
scrubbers or spray dryers

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Venturi Scrubbers
A gas phase contact scrubber used to collect both particles
and gaseous pollutants
Has 3 sections: converging, throat and diverging section
Exhaust stream is forced to move through throat at
extremely high velocity (30-120 m/sec.)
• Liquid is introduced into the throat either at the throat or at the
entrance of the converging section
• At the throat the liquid is sheared from walls and atomized
into very small droplets
• Gas exiting the diverging section is forced to slow down for
removing the liquid droplets
• Entrainment separator (cyclonic or mesh pad or blade
separator) is used for the removal of entrained liquid droplets
– Cyclonic separator when used is connected to the venturi usually
by a flooded elbow

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Diverging section
Converging section

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Venturi Scrubbers
• Non-wetted (dry throat) approach venturi
– liquid is introduced at the throat
– in case of high temperature exhaust caking of throat can
occur
– appropriate for cool moist exhaust
• Venturi with wetted approach
– liquid is introduced at the entrance of the converging
section
• Venturi with round throat can not handle larger flows (>
88000 m3/hr) - Venturi with long, narrow, rectangular
throat can be used

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Venturi Scrubbers
• For handling variable gas flows adjustable throat venturis
(with varying throat areas) are used
– Venturi with a plunger or adjustable disc moving up and
down the throat (decreasing and increasing annular
opening of the throat)
– Rectangular throat venturis with movable plates that
decrease or increase throat area
• Venturi rod or rod deck scrubber – a number of pipes
parallel to each other in the exhaust flow path create a
series of rectangular throat openings

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Venturi Scrubbers
Highest particle collection efficiency (90-99%) among
scrubbers
• Operated at pressure drops of 5 to 100 inches (gas velocity in
the throat is 30 to 120 m/S)
– Increasing pressure drop across increases efficiency
• Liquid to gas ratios employed are 0.4 to 1.3 L/m3
– Higher ratios do not significantly increase efficiency and lower
ratios may not sufficiently wet the throat
Removal efficiency for gases is 30-60%
• Very short gas-liquid contact time limit gas absorption
• Efficient removal occurs if the gas is chemically reactive with
or it is highly soluble in the liquid
• Lower exhaust velocities and higher liquid to gas ratios can
enhance the removal efficiencies
– Liquid to gas ratios of 2.7 to 5.3 L/m3

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Venturi Scrubbers
Wear or abrasion of the scrubber shell is the primary
maintenance problem with venturis
– Lining the throat with silicon carbide or using replaceable liner
can minimize the problem
– A pre-cleaner through removing larger particles can also reduce
abrasion problem
• Flooded elbow at the bottom of the scrubber can reduce
abrasion downstream to the throat
Method of liquid injection (spray nozzles/weirs) can also
cause problems
• Spray nozzles can clog specially with recirculated liquid
– Nozzles holes twice the size of openings of the strainers used in
the liquid recycle line can minimize clogging

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Ejector Venturi
Actually a spray tower capable of moving exhaust without
the aid of any blower or fan
– Preferred in explosive or extremely corrosive environment
High pressure (15-120 psig) and high rate (7-13 L/m3)
liquid spray (with a lone nozzle) into throat creates
vacuum, sucks exhaust from the side duct and moves
through the venturi
Entrainment separator is usually used
Effective in removing particles of >1µ size but gas
absorption efficiencies are very low
For extremely high collection efficiencies multiple stages of
ejector venturis are used
Pressure drop across is 1.3 to 13 cm water
Abrasion can be problem in nozzles and throat

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Orifice Scrubbers
Medium energy (5 to 25 cm water pressure drop across)
devices used for particals removal (and also gases)
Exhaust stream is forced through a pool of liquid at high
velocity (15.2 m/S) creating liquid droplets
• Larger particles are removed by impingement on scrubber
liquid surface - smaller particles by impacting liquid droplets
– Baffles/air foils are provided for the turbulent mixing of liquid
droplets with the exhaust
– Baffles placed in the path of cleaned exhaust stream serve as
impingement surfaces for entrainment removal
• Sludge accumulated in the scrubber needs liquid circulation
through a sludge removal facility

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Orifice Scrubbers
Designed to operate with a specific liquid level for a given
gas velocity
– Gas velocities should not fluctuate beyond 10-15% of
design values
– Low gas flows or reduced liquid levels reduce atomization
and particle collection efficiencies
– High gas flows can blow the liquid chamber dry
Designed for maximum exhaust flow rate and makeup air is
introduced when flows become less

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Orifice Scrubbers
Maintaining water level at desired level (in the face of
sludge separation and removal) is an important and
difficult maintenance problem
Plugging and scale buildup are not problems
– Reactive scrubbing (gaseous pollutants chemically react
with liquid) can still produce scales and plug the internals
Collection efficiencies are moderate and used for the
removal of >1 µ particles
Liquid gas ratio is
– 1.3 to 5.3 L/m3 for particles removal
– 0.07 to 0.7 L/m3 for gases

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Plate Towers
Effective in removing gaseous pollutants
– Particulates can also be simultaneously removed
– Can prove good for flue gas desulphurization
One or more plates are mounted horizontally inside a
vertical column
Exhaust enters at the bottom and flows upwards passing
through the plates
Liquid enters at top and travels across each plate to a
down comer and from their to next plate below and
ultimately to the tower bottom
– Liquid to gas ratio followed is 0.7 to 2.0L/m3
These are medium energy scrubbers (2.5 to 20 cm
pressure drop per plate)

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Plate Towers
Plates are sieve, impingement, bubble cap and valve types
• Sieve plates: Have 1800-9000/m2 openings of 0.32-2.5 cm
size and form 10-100µ size droplets
• Impingement plates: plate openings have impaction targets
above to increase the gas-liquid contact
• Bubble cap plates: around each hole a riser is provided – over
the riser a cap with several slots is provided
• Valve plates: have liftable caps above the openings and
plates attached to legs limit the caps’ vertical movement
Smaller openings can increase the particle collection
efficiency but can get plugged
Cost wise sieve plates are cheapest, impingement plates
come next, and bubble cap plates are the costliest

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Plate Towers
Gas removal efficiencies of > 98% can be easily achieved
and for increasing efficiencies following can be done
– Increasing number of plates
– Using higher liquid to gas ratios
– Increasing pressure drop across the plates
Particle collection efficiencies are moderate
– Decreasing hole size and increasing number of holes
increase particle collection efficiencies –
– Increasing number of plates beyond 2 or 3 do not increase
efficiency significantly

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Plate Towers
Susceptible to plugging and/or scale build-up problems
– high solid content in scrubber liquor can be a cause
– can not be used for exhaust with dust or sticky materials
– access to plates for cleaning is important
– water sprays underside the lower most plate can avoid
wet-dry interface and scaling
– low pH wash can dissolve and remove scales
Higher liquid injection rates and higher exhaust gas
velocities can cause flooding of plates – this in turn
increase pressure drop but decreases gas-liquid mixing
Too low gas velocities cause weeping (liquid dripping
through holes) and decrease the gas-liquid contact
Poor scrubbing liquor distribution can be a problem

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Spray Towers
Low energy (pressure drop is 1.3 to 7.6 cm water)
inexpensive devices
Used as pre-scrubbers for removing
– larger particles (of size >10-25µ)
– highly soluble gases (with 50-80% efficiency - plate towers
and packed towers are superior for gas absorption
removal)
chemical reagent addition to the liquid (KMnO4 for odor
removal) can also increase the efficiency
Used to handle flows upto 50 m3/sec

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Spray Towers
Counter-current, co-current and cross-current
configurations are used
• Cross-current configurations (horizontal spray scrubbers)
can have more than one spray sections
– For better results the liquid can flow counter-current and
cleanest liquid can be sprayed in the last section
• Counter-current configurations can have multilevel liquid
spray nozzles
• For similar collection efficiencies co-current configuration
is smaller than a counter-current configuration
– Exhaust relative velocity is higher in the counter-current
configuration

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Spray Towers
Exhaust enters the bottom and moves upwards in counter-
current flow configuration
• Exhaust gas velocity is within 0.3 to 1.2m/sec. to prevent
liquid carry over
Liquid at pressure is 10-400 psig is sprayed through
nozzles downwards into the spray tower
• Produces droplets of size 500 to 1000µ (venturis
produce 10 to 50µ size droplets)
– injection of liquid at 300 to 450 psig pressure creates fog
like droplets
• Liquid to gas ratios employed are 0.7 to 2.7 L/m3

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Spray Towers
• Decreasing liquid droplet size and increasing liquid to
gas ratio can increase the absorption removal
• Liquid droplets after falling short distance tend to
agglomerate into bigger drops or hit walls and
comedown affecting efficiency
• Completely open design – have least scale buildup and
plugging problems
• Nozzle plugging or eroding can occur specially with
recycled liquid

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Baffled Spray Scrubbers
Similar to spray towers both in design and operation
– In addition to spray nozzles, baffles (that allow further
atomizing of liquid) are added to boost treatment
Used mostly as pre-cleaners for the removal of >10µ size
particles
– Not specifically used for the removal of gases
Pressure drop is 2.5 to 7.5 cm water
Liquid to gas ratio is 0.13 L/m3
Liquid inlet pressure is <15 psig
Maintenance problems are the least – solids buildup on
baffles can occur

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Cyclonic Spray Scrubbers
Low to medium energy devices (pressure drop is 4
to 25 cm of water)
– Uses the features of both a dry cyclone and spray
tower for collecting particulate matter
– More efficient than spray towers but less efficient than
venturi scrubbers
– Particles >5 µ are removed with >90% efficiency
– Particle velocity is 60-180 m/sec. comparable to
venturis (in spray towers it is 0.6 to 1.5 m/sec.
– Turbulence level is much lesser than that generated
in a venturi
Less efficient in removing gaseous pollutants and
not chosen for gaseous pollutant removal

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Cyclonic Spray Scrubbers
Include Irrigated cyclones and Cyclonic spray scrubbers
Irrigated cyclone
– Exhaust enter tangentially near the top into water sprays and
swirls downward, then change direction return upward in a
tighter spiral
Cyclonic spray scrubber
– Exhaust enters the chamber tangentially near the bottom, swirl
through the chamber moves upwards and exit from top
– Liquid is sprayed from nozzles on a central post and directed
toward the chamber walls
– Straightening vanes are provided at the top of the chamber
– Can also act as entrainment separators

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Cyclonic Spray Scrubbers
Nozzle plugging and corrosion or erosion side walls are the
maintenance problems
– Better install the nozzles in a way for ease of access for
maintenance
– Abrasion resistant materials may be used to protect the
cyclone body
Liquid to gas ratio employed is 0.3 to 1.3 L/m3
Liquid inlet pressure is 280 to 2800 kPa

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Packed Tower Scrubber
Medium energy scrubbers used for gas absorption
– Particles are also removed, but submicron particles not
efficiently
– Both liquid phase and gas phase provide the energy
needed for the scrubbing
Used for handling smaller flows and easy to handle gases
– For larger flows and difficult gases plate towers are
preferred
Cheaper but weight is more than that of plate tower
Packing material supported over trays is sprayed with liquid
to form liquid film coat
Exhaust is passed through packing for contact with liquid
and absorption removal of gaseous pollutants

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Packed Tower Scrubber
Absorption removal is enhanced by
– Liquid film surface
– Turbulent contact between the liquid and gas
– Contact time
– Solubility of the gaseous pollutants
Higher gas velocity through packing ensures good mixing
but can cause flooding of packing
Increasing liquid injection increases absorption efficiency
but can cause flooding

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Packed Tower Scrubber
Common used configurations include counter-current, co-
current and cross-flow
Counter-current flow configuration
– Liquid is introduced at the top of packing by sprays/weirs
– Exhaust is entered at bottom and flown through upward
Co-current flow configuration
– Both exhaust and liquid enter at top and move downward
– Can operate at higher liquid & gas flow rates without
flooding
– Removal efficiencies are limited
– For similar flows and absorption efficiencies, diameter of
the tower is relatively smaller and pressure drop is lower

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Packed Tower Scrubber
Cross flow configuration
– Exhaust moves horizontally while liquid moves vertically
– liquid sprays at the face of packing on the inlet side may
also be used
– packing can be slanted in the direction of incoming
exhaust for ensuring complete wetting of packing
– can include more than one sections
– liquid flow rate can be higher in the front section for
particulate washout
– last section can be left dry to act as entrainment separator
– considered as better for handling exhausts with high
particulate concentration
– can be designed to have lower pressure drop
Fiber bed scrubber with cross flow scheme

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Packed Tower Scrubber
Material used as packing include stoneware, porcelain,
metal, high density thermoplastics (polyethylene and
polypropylene), etc.
– Dimensions can be of 0.6 to 10 cm in size
– Smaller size offers larger specific surface area but
increases pressure drop
Shapes of packing material used
– Raschig rings (5 cm)
– Tellerette packing (2.5 cm)
– Tripacks
– Pall rings
– Intelox metal
– Bari saddle, etc.

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Packed Tower Scrubber
Factors influencing selection of packing material include
nature of contaminants, geometric mode of contact, size
of the absorber, and scrubbing objectives
Cost, pressure drop, corrosion resistance, specific area,
structural strength, weight, design flexibility, etc., also
influence
Packing can be either random or stacking systematically
– Random packing provides higher specific surface area but
cause higher pressure drop and poor liquid distribution
– Stacked packing provides better liquid distribution but
installation costs are higher

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Packed Tower Scrubber
Proper design of support trays can ensure uniform
distribution of exhaust through the packed bed
Metals plates or grids used to support the packing also act
as distribution baffles
Liquid should be distributed over the entire the top surface
of the packed bed
Channeling of the liquid should be avoided
Liquid tend to flow towards tower walls and result in short
circuiting
– Require redirecting from the tower walls back to the center
of the packed column by liquid redistributors placed at
intervals of <3 m or at 5 tower diameters from the top

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Packed Tower Scrubber
Liquid distribution is by weirs, tubes or spray nozzles
Distribution Weirs:
– Do not plug and can handle dirty liquids but require leveling
– Can be easily inspected and maintained
Perforated tubes:
– Can be buried within the packing – allows the packing above the
perforated tube to act as entrainment separator
– Avoids liquid blowing against the side walls of the tower
– Tubes (and perforations) can clog and knowing it is difficult
Spray nozzles:
– Nozzle clogging and erosion can be a problem
– Use of fewer relatively large nozzles can avoid the clogging
– Can be easily inspected
– Pressure drop is the highest among the three

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Packed Tower Scrubber
Buildup of solids in the packing is a serious problem
• Particulate matter tend to get removed and accumulate in the
packing - pre-cleaning spray can reduce the solids buildup
• Buildup could also result from chemical reactions between the
liquid and absorbed gases
• Liquid draining through the packing carry the collected
particles and plug the void spaces
• Tower internals are not easily accessible and cleaning
requires shutting the system and removing, cleaning and
reinstalling the packing

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Packed Tower Scrubber
Maintaining proper liquid and exhaust flows is needed -
increasing any of the two can result in flooding
– Flooded packing result in higher pressure drop, pulsating
air flow and dramatically reduced efficiencies
– Optimal operating flow rates should be 60-75% of the
flooding flow
Lower gas flow rates can result in gas channeling
Liquid to gas ratio employed is 0.13 to 2.0 L/m3 and liquid
inlet pressure is 5-15 psig
Pressure drop is 1.7 to 5 cm water per foot or 2 to 8.5 cm of
water per meter of installed packing and 5 to 22 cm of
water across the packed tower

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Mobile Bed Scrubbers
Similar to packed towers but packing is in constant motion
– Gas stream powers motion of the packing
– Liquid is sprayed over the packing
– Bottom sprays are used for saturating the gas (also
removes large particles)
– Entrainment separators are required
Preferred when high collection efficiency of particulates and
gaseous pollutants is required
Provides effective absorption like packed and plate towers
but without plugging problems
Because of high gas velocities these are much more
compact than packer towers and plate towers but these
are not as energy efficient as the latter

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Mobile Bed Scrubbers
Based on the degree of movement of the packing mobile
bed scrubbers are classified as
– Flooded bed scrubbers
– Fluidized bed scrubbers
Packing used in the scrubbers
– Spheres of plastics, glass or marble in flooded beds
– Hollow polypropylene/polyethylene balls in fluidized beds
Flooded bed scrubbers:
– Packing gently moves and rotates
– Packing of 10 to 20 depth is used
– Bubbles formed in the bed create a layer of froth over the
bed twice the depth of packing

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Mobile Bed Scrubbers
Fluidized bed scrubbers (also known as turbulent
contact absorbers):
• Packing is suspended or fluidized within the bed
• For this exhaust gas velocity of 1.8 to 4.8 m/sec. is used
• packing of 0.3 to 0.6 m depth is used and froth zone is
about 0.6 m thick over the packing
• More than one fluidized packing sections (upto 6) may
be used for efficient gas absorption
– If gas absorption is not needed then a single packed
section is sufficient

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Mobile Bed Scrubbers
Particulates can be collected
– At inlet below the bed by bottom sprays
– At the packing by impingement on the wetted surface
– In the froth layer over the packing
Maintenance problems
– Plugging and scale buildup can occur specially at the
scrubber inlet and on the packing support grid
– Nozzle maintenance is of concern in lime or limestone
scrubbing systems
– Deterioration of spheres of packing can occur from high
temperature and constant rubbing against each other

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Mobile Bed Scrubbers
• Pressure drop in mobile bed may range from 5 to 15 cm
water per section
• Liquid to gas ratio is 2.7 to 8 L/m3 for gases and 0.4 to
0.7 L/m3 for particulates removal
• Increasing liquid-to-gas ratio, increasing the depth of
packing and increasing the number of packing stages
enhance adsorption
– Removal efficiencies are 99% for gases
– For SO2 removal from flue gases 8L/m3 ratio is used
• Particles >2 to 3µ are removed

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Mechanically Aided Scrubbers
Motors are used to supply the energy needed for scrubbing
More compact but have higher overall power requirement
Capable of high particle collection efficiencies and can
remove particles of >1µ size
– Generally not used for gas absorption
Operate at low liquid to gas ratio
– 0.07 to 0.2 L/m3 for centrifugal fan scrubbers
– 0.5 to 0.7 L/m3 for spray rotor scrubbers
Because of moving parts maintenance problems are high
– Moving parts are susceptible to corrosion and fouling
– Rotating parts are subject to vibrations – induced fatigue
or wear cause them to become unbalanced
Not used with corrosive or sticky materials

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Mechanically Aided Scrubbers
Centrifugal fan scrubbers
• Serve as both air movers and particle collection devices
• Water is sprayed (at 20-60 psig pressure) on blades to
form droplets and to impart centrifugal motion to droplets
• Rotating blades force both liquid and particles off the
blades towards the walls of the casing
• Extra power consumption equivalent to 10.2 to 15.2 cm
water occurs from use as particulate collection devices
Induced spray scrubbers
• Vertical whirling rotors submerged in a liquid pool are
used to produce fine droplet sprays
• Exhaust is forced to move through the spray
• Pressure drop across the device is 10-20 cm water

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Dry Sorbent Injection Scrubber
Used to control acid gas (SO2, HCl, HF, etc.) emission
Have advanteges over the wet scrubbers which can be
alternative
– Release of steam plume is avoided
– Requirement of a system of piping and pumps for the
collection, treatment and recirculation of scrubbing liquid
associated with wet scrubbers is avoided
Powdered sorbent is injected into flue gas at
– Furnace of the boiler
– Duct work or reaction chamber prior to the air pollution
control device
Reaction chamber increases residence time of acid gases to
react with the sorbent

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Dry Sorbent Injection Scrubber
Includes two main sections:
• Device to introduce the sorbent – consists of
– a dry sorbent storage tank
– a weight feeder to meter the sorbent
– a blower and transfer line
– an injection device (venturi)
Sorbent is blown through pneumatic line to the injection area
Injection is done countercurrent to the flue gas to create
turbulence and promote mixing
• Particulate matter control device to remove the reaction
products, excess sorbent and other SPM of the exhaust
– Fabric filters or Electrostatic precipitators are used

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Dry Sorbent Injection Scrubber
Injection at elevated temperature may be needed for the
decomposition reaction of the sorbent
– CaCO3 decomposition into CaO
Efficiency is 50% for SO2 and 90% for HCl in simple
systems – can be increased by
– Cooling and/or humidifying the flue gas
– Recycling portion of the collected particulate matter (has
unreacted sorbent)
– Operating at higher stoichiometric ratios of sorbent
– Introducing an expansion/reaction chamber can increase
residence time and efficiency

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Spray dryer systems
Used to control acid gas (SO2, HCl, HF, etc.) emission
Have advantages over the wet scrubbers which can be
alternative
– Use lesser quantities of liquid – hot flue gases
evaporate the moisture and avoid release of steam
plume
– Do not require the system of piping and pumps for the
collection, treatment and recirculation of scrubbing
liquid
Mixing of acid gases with alkaline sorbent is more effective
than in dry sorbent injectors and can achieve higher
removal efficiencies

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Spray dryer systems
Typical spray drying includes
– Lime storage and slacking system
– Lime making and feeding tanks
– Atomizer
– Spray dryer chamber (absorption tower/reaction chamber)
– Particulate control device
– Particulate recycle system (optional)
Exhaust is introduced into absorbing tower (reaction or
drying chamber) for contacting with finely atomized
alkaline slurry
– Then passed through a fabric filter or an electrostatic precipitator
for the particulates removal
– Collected solids can be recycled and used in slurry making

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Spray dryer systems
Performance can be affected by
– Flue gas flow rate and temperature
– Stoichiometric ratio of the alkaline sorbent
– Properties of the alkali used
For better performance
– Gas residence time in the spray dryer should be 10-15 sec.
– Spray dryer outlet temperature should be above and close to
dew point
Amount of water to be used depends on incoming flue gas
temperature and moisture content
Alkaline slurry loading rate depends on acid gas level in the
exhaust and removal efficiency desired
Use of 1.5 to 2.5 times stoichiometric ratio can achieve 75-
80% SO2 removal or 95% HCl removal

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Spray dryer systems
Rotary atomizers (atomizing wheels) and duel fluid nozzles,
are used to inject the alkaline sorbent slurry
Rotary atomizers (atomizer wheel)
– 8 to 16 inches size wheels of corrosion and abrasion resistant
materials
– Have higher capacity and simpler piping system and single
atomizer is used
– Atomation energy is supplied via a motor coupled to the
atomizing wheel
– Rotational speed is 7000 to 20000 rpm and produce 25-150µ
size droplets
Duel fluid pneumatic nozzles
– Multiple nozzles are used
– High velocity and high pressure air is used
– Easier to maintain – each nozzle can be isolated
– Energy is supplied primarily as high pressure air

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Spray dryer chamber
• Gas and liquid flow scheme may be cocurrent or counter
current or mixed
– Cocuurent is most commonly used
– Counter current dryers have higher drying capacity
– Precise control of exit gas temperature is possible in
cocurrent dryers
• Typical dryer diameter is 25-30 ft.
– Design of the dryer chamber is affected by the atomizing
method used
• Length to diameter ratio for chambers with rotary
atomizers is 0.8:1 – droplets should not deposit on walls
Spray dryer systems

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Particulate matter collection
• Either fabric filters or ESP are used
– Fabric filters give better acid gas removal than ESP
• Potential heat loss in the particle collection system
should minimum
– The particulate matter being hygroscopic can cause
corrosion problems or plugging
– Insulation, hopper heaters and reducing air in-leaks can
prevent operational problems
Spray dryer systems

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Dry scrubbing systems
Except for atomizers, these systems are relatively simple
devices and have fewer moving parts
Plugging in solid or slurry transport systems is the primary
maintenance problem with these systems
– Dead areas of solid/slurry piping, valves and atomizers are
more prone to plugging
– Flexible piping is less susceptible to plugging
– T joints & quick connectors allow quick flushing & deplugging
– Use of screens ahead of atomizers & valves minimize
plugging - screens require frequent cleaning (by acid!)
– Atomizers may need frequent flushing with water
Draining and flushing of lines and storage tanks during
extended downtimes is also helpful
Low quality lime and/or water can result in scaling, plugging
and reduce acid gas removal efficiencies