CONCEPTUALIZED FLY-ASH AND
   SULFUR DIOXIDE SCRUBBING
SYSTEM WITH BY-PRODUCT RECOVERY

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CONCEPTUALIZED FLY-ASH AND
SULFUR DIOXIDE SCRUBBING
SYSTEM WITH BY-PRODUCT RECOVERY
by
Gary E. Carlson
and

David. E. James
OqCo'7
January 29, 1971

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;) It, 7
CONCEPTUALIZED FLY-ASH AND SULFUR DIOXIDE
SCRUBBING SYSTEM WITH BY-PRODUCT RECOVERY
General
Based on the experimental data gathered during this contract, a.
conceptualized air pollution system was established.
The system lNas
designed to remove 99% of the fly-ash and 97 1/2% of the sulfur
dioxide contained in an assumed but typical flue gas.
A venturi-
type scrubber was chosen to remove the fly-ash, and a tray-type
absorber was chosen for sulfur dioxide absorption.
A slurry of
magnesium oxide and magnesium sulfite is the active absorbent.
The
conceptualized system is sholNn schematically on Drawing No. 390407B-0.
Drawings Nos. P17-96-lXO and P17-96-2XO show the side and. plan views
of scrubbing venturis and sulfur dioxide absorbers as integrated
into an 800 MW boiler system.
The outline and. location of the major
pieces of equipment are sholNn on Drawing No. P17-96-3XO.
The above dralNings were utilized. to develop the cost of the
conceptualized system.
Whenever possible, commercially available
equipment was utilized in the design and cost estimate.
When commercial
equipment was not available, suitable conceptual equipment designs
were developed, and the cost of the equipment established.
I

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System Description
The system, as conceptualized here, starts at the plen~m which
collects the flue gas leaving the primary and secondaryair;heaters.
The flue gas passes through the following equipment which is arranged
in parallel: four venturi scrubbers, four sulfur dioxide abiorbe~s,
four induced fans, and two steam coil gas reheaters.
The gas.1s then
discharged through a stack.
The entrances to the stack ar.e considered
terminal points.
The cost of the stack has not been included in the
estimate.
The gas entering the venturis is mixed with water which contacts
and removes the entrained fly-ash.
The resulting fly-ash slurry is
transferred to a thickener for separation.
The clarified overflow
is returned to the venturis for reuse while the underflow is pumped
to filters.
Here, the fly-ash is washed with fresh water to minimize
the amount of soluble sulfur and magnesium compounds that leave the
system with the fly-ash.
Pumps have been included to sluice the
fly-ash to a pond.
The discharge of these pumps is the terminal,
point of the ash system.
The particulate-free flue gas passes to the absorbers where sulfur
dioxide is removed by reacting with magnesium sulfite.
The resulting
magnesium-sulfur compounds are dewatered by thickening and centrifuging.
The liquor which is separated from the slurry in the thickener and centri-
fuges is returned to the absorberso
Magnesium oxide, which results from
the regeneration of the magnesium-sulfur compounds, is added to the
absorbers to replace the magnesium which reacts with sulf~r dioxide and
is removed to the thickener as a sulfide.
The solid materials leaving
the centrifuge are dried and then decomposed to yield magnesium
2

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System Description (Continued)
oxide and a gas stream containing 17.7% sulfur dioxide by weight.
The product gas leaving the reactor is cooled and filtered and leaves
the system.
This gas is suitable for making concentrated sulfuric
acid.
The cost of the acid plant is not included in this study.
The flow quantities at the terminals described above are
listed below:
Gas at Entrance to Fly-Ash Scrubber
Temperature - 300 F
. Lb/Hr
Lb/Hr
L b/Hr
Lb/Hr
Lb/Hr
Lb/Hr
Total
Stack Gas
Temperature - 180
F
L b/Hr
Lb/Hr
Lb/Hr
Lb/Hr
Lb/Hr
Lb/Hr
Total
Product Gas
Temperature - 400 F
Lb/Hr
Lb/Hr
Lb/Hr
L b/Hr
Lb/Hr
Total
3
S02 4-3,500 
C02 1,386,000 
02 24-3,000 
N2 4-,790,000 
H20 392,000 
Ash 67,200 
 6~92l~700 Lb/Hr
802 1,090 
C02 1,386,000 
°2 24-3,000 
N2 4-,790,000 
H20 729,000 
Ash 670 
 7,14-9,760 Lb/Hr
S02 4-0,200 
C02 23,300 
02 20,100 
N2 132,500 
H20 11,700 
 227,800 Lb/Hr

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System Description (Continued.)
Waste to Ash Pond
Temperature - 128 F
Solids
Water
Total
Lt-
Lb/Hr
Lb/Hr
69,720
J.OLt-,580
17Lt-,~00 Lb/~r

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~'1uiDment Cost Estimates
For estimating purposes, the air pollution control sys'~em'has-
been divided into three sections.
These secttons, the equipment
associated with each, and the costs are listed below.
is the cost of erecting the equipment.
,Also' shown'
Boiler Associated Equipment

Flue Platework
Expansion Joints and Dampers
Venturis (4)
Sumps (4)
S02 Absorbers (4)
Ash and Sulfite Collection Tanks (2)
Foundations
Structural Steel
Brickwork, Refractories, Insulation,
and Lagging
Controls
Electricals
Valves
Pumps and Drives (28)
Mixer
Steam Coil Gas Reheaters (2)
Absorber Packing
Demisters (4)
I.D. Fans (4)
I.D. Fan Drives (4)
Piping and Fittings
Rubber Lining for Tanks
Engineering and Drawings
Total Cost for Boiler Associated Equipment
$5,835,000
5

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Eauiument Cost Estimates (Continued)
Dewatering Equipment
Filtrate Tanks (2).
Foundations
Structural Steel
Brickwork, Refractories, Insulation,
and Lagging
Controls
Electricals
Valves
Pumps arid Drives (24)
Mixer
Thickeners and Filters (7)
Rubber Lining for Tanks
Piping and Fittings
Engineering and Drawings

Total Cost for Dewatering Equipment
$1,205,000
Regeneration Equipment

Flue Platework
Expansion Joints and Dampers
Heat Exchangers (2)
Reactors (2)
Combustors (2)
Dryers (2)
HOlding, Wash, and Storage Tanks (4)
Coal Bunker
Foundations
Building Steel
Structural Steel
Brickwork, Refractories, Insulation,
and Lagging
Controls
Electricals
Valves
Pumps and Drives (8)
Mixer
Fans and Blowers (12)
Fan Drives (12)
Conveyors (4)
Cyclones (5)
Centrifuges (4)
Bag Filter Houses
Pug Mills (2)
Rotary Feeders (14)
Engineering and Drawings

Total Cost for Regeneration Equipment
.$3,225,000
6

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Equipment Cost Estimates (Continued)
Total Equipment Costs
Erection Cost
$10,265,000
$ 3,3 9 8 , 500
$13,663,500
Total Delivered and Erected Cost
7

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Operating Requirements
The following list of operating utilities has been prepared and
is based on the terminal flow quantities listed above and an 800 MW
steam generator operating at a levelized load factor of 70% or
6,132 hours per year.
Electrical Power
86.1 x 106 kwhr
yr
Fuel
1,281,000 MkB
yr
57.9% coal
4-2.1% oil
Water
~o~. ~ x 106 gal
yr
Steam
ill, '500 MkB
yr
(added fuel input)
Dolomite
'5,94-0,000 Ib
yr
8

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8 LO~Q6£
BOILER
COAL
I
COAL
FLY ASH
SCRUBBER
AIR
FORCED
DRAFT FAN
FLY ASH
DEWATERING SYSTEM
TO ASH DISPOSAL
S02 PRODUCT
CONTRACT NO. CPA 22-69-129
I FOR NATIONAL AIR POLLUTION CONTRO.L ABMINISTRATION

I
9
THE l'ICO(l( & WILCOX COMP'NY
POWER GENERATION DIV.
S 02 ABSORBER
FLUE GAS
"EHEATER
INDUCED
DRAFT FAN
SPENT SCRUBBING
SLURRY DEWATERING
SYSTEM
SPENT SCRUBBING
SLURRY DR'fI.NG
SYSTEM
MAGNESIA
REGENERATION SYSTEM
9 hf lOSS DIAGRAM FOR MAGNESIA
SLURRY ABSORPTION OF S021MAGNESIA
REGENERATION AND BY- PRODUCT RECOVERY
STAC.K
SCAL!!
INCH!!. = I ,.OOT
"390407 -

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