Page 1 

Final Notes from Site Visit at 

Appalachian Power Company’s Mountaineer Plant 

on September 11, 2008 

EPA conducted a site visit at Appalachian Power Company’s Mountaineer Plant 

(Mountaineer) located in New Haven, WV on Thursday, September 11, 2008 to learn 

about the operations at the plant, specifically the FGD wastewater treatment system. 

These notes describe the information collected during the site visit and the pre-site visit 

phone call, which was held on August 8, 2008. Attached to this document are the 

following: 

(1) List of site visit participants; 

(2) Proposed NPDES Water Balance Diagram for the Mountaineer Plant, dated 3 Dec 

2007; 

(3) Process flow diagrams for the FGD unit and FGD wastewater treatment system; 

(4) Presentation that the Mountaineer personnel gave during the site visit; 

Plant Overview 

• The Mountaineer plant has one generating unit with a net capacity of 

1,300 MW. The table below gives some general information about the one 

unit. 

• Mountaineer operates a recirculating cooling system with a cooling tower. 

The cooling tower blowdown is transferred to the wastewater treatment 

ponds. 

• Mountaineer operates a limestone forced oxidation FGD scrubber system. 

• Mountaineer burns a blend of eastern bituminous (1.2-7.5 pounds of sulfur 

per MMBTU electricity produced) and Powder River Basin (PRB) coal. 

Mountaineer blends up to a maximum of 15 percent of PRB into the coal. 

Mountaineer stated that they perform the blending of the coal on site. 

• The blended Mountaineer coal has a sulfur content of 5.5-6 percent sulfur, 

or 4.5 pounds of sulfur per MMBTU electricity produced. 

• Mountaineer operates a sulfur trioxide mitigation system. Mountaineer 

injects trona into the flue gas upstream of the ESPs to control sulfur 

trioxide emissions. 

Unit 

Installation 

Date 

Capacity 

(MW) 

Particulate 

Control NOx Control SO2 Control 

1 September 

1980 

1,300 Cold-side 

ESP 

SCR – May 

2002 

Wet FGD - February 

2007 
Page 2 

• Mountaineer is conducting a pilot test of several technologies for the 

treatment of mercury in the FGD purge stream. 

• Mountaineer is working with Alstom on a pilot test for a carbon capture 

technology. 

Coal Pile

• Mountaineer has four coal pile runoff ponds, one located at each corner of 

the coal pile. During the site visit, Mountaineer staff measured the 

temperature and pH of water in each of the coal pile runoff ponds. The 

following table summarizes the data collected during the site visit. 

Pond Level Temperature (°C) pH 

Southwest Pond Full 23.1 3.5 

Northwest Pond Drained 22.2 7.17 

Northeast Pond Drained 23.6 7.29 

Southeast Pond Drained 23.6 7.72 

• Mountaineer stated that the runoff collected in the northwest, northeast, 

and southwest ponds are all transferred to the southeast pond before being 

pumped to the bottom ash ponds.

Ash Handling 

• The Mountaineer plant has dry fly ash handling. The dry fly ash is 

pneumatically blown to silos for temporary storage. Mountaineer uses 

reclaim water to condition the fly ash prior to trucking it to the on-site 

landfill. 

• The Mountaineer plant has a wet bottom ash handling system. The wet 

bottom ash sluice is sent to the two bottom ash ponds. Process wastewater 

from pyrite transport, fly ash silo sumps, limestone pile, gypsum pile, and 

the coal pile are also sent to the bottom ash ponds. Mountaineer only 

operates one bottom ash pond at a time; therefore, while one is in service, 

the other is out of service. 

• The overflow from the bottom ash ponds is transferred to one of two 

wastewater treatment ponds. Each bottom ash pond has its own 

wastewater treatment pond; therefore, like the bottom ash ponds, only one 

wastewater treatment pond is operating at a time. In addition to overflow 

from the bottom ash ponds, the treatment ponds also receive cooling tower 

blowdown, landfill runoff, and low volume wastes. 

• The wastewater treatment ponds overflow to a single reclaim water pond. 

Some of the overflow from the reclaim water pond is recycled for plant 
Page 3 

operations and the rest is sent to the clearwater pond, which discharges to 

the Ohio River. 

SCR System 

• Mountaineer operates a SCR system directly after the boilers. The SCR is 

located prior to the air preheater and ESPs because the system is operated 

at a temperature of 600-800°F. Mountaineer stated that a minimum

temperature of 620°F is needed for the SCR reaction to initiate. 

• Mountaineer does not store ammonia on site. Instead, Mountaineer stores 

urea and hydrolyzes the urea to obtain ammonia gas. Mountaineer stated 

that 1 pound of urea is hydrolyzed to 0.56 pounds of ammonia. 

• Ammonia is injected into the flue gas upstream just prior to the flue gas 

entering the SCR. 

• The Mountaineer SCR system has three levels of plate catalysts. There are 

four injection points in each level. 

• Mountaineer stated that ammonia slip happens when the catalyst becomes 

depleted. Additionally, Mountaineer stated that issues mixing the 

ammonia into the flue gas can lead to ammonia slip. Mountaineer has 

monitors to measure ammonia slip; however, the monitors can only 

measure the ammonia at the specific monitoring location in the SCR and 

does not account for the entire system. Typical ammonia slip is 2-2.5 ppm. 

 

• Mountaineer stated that the SCR typically achieves a NOx removal 

efficiency greater than 90 percent. 

• Mountaineer stated that the catalysts are sent off site to be regenerated. 

For Mountaineer, the catalysts have a lifespan of 3 to 8 years before 

requiring regeneration. However, plant personnel expect that lifespan to 

decrease now that the SCR will be operating year round. 

FGD System 

• Mountaineer operates a wet limestone forced oxidation FGD scrubber on 

the one generating unit. The FGD system consists of two modules made 

with 2205 stainless steel alloy. The FGD scrubber was installed in 

February 2007. 

• The FGD system achieves a 98 percent removal of SO2 from the flue gas. 

• Mountaineer stated that they unload 1,500 tons of limestone per hour from 

barges. The limestone pile on site contains approximately 15,000 tons of 

limestone. 
Page 4 

• The limestone is ground in two ball mills which reduce the size of the 

limestone to 95 percent passing 325 mesh. Each of the ball mills 

processes 90 tons of limestone per hour. Mountaineer stated that they are 

able to hold 226,000 gallons of limestone slurry reagent. The limestone 

slurry is approximately 25 percent solids. 

• The FGD scrubber modules have six spray levels and each level has a 

designated recirculation pump. Mountaineer stated that they are currently 

operating four of the six recirculation pumps. Mountaineer stated that the 

number of pumps needed depends on the sulfur content of the coal. Each 

recirculation pump recirculates the FGD scrubber slurry at a flow rate of 

76,075 gpm. 

• The Mountaineer FGD scrubber modules have two blowdown pumps that 

continuously blow down the FGD scrubber slurry at 2,182 gpm. 

Mountaineer stated that the blowdown pumps are operating continuously, 

but the flow is recirculated when a blowdown isn’t necessary. 

• Mountaineer stated that they do not use any additives in the FGD system 

because many additives are byproducts of other industries and the 

availability of these additives are dependent on industry shifts. Additives 

are typically added to enhance the alkalinity of the system. 

• Mountaineer stated that the gas flow rate within each module is 2,600,500 

acfm. The upward velocity of this gas is 10 feet per second and the 

average mass transfer contact time is 1-1.5 seconds. The flue gas approach 

temperature is approximately 350°F. The temperature within the scrubber 

is approximately 128°F, which is the adiabatic saturation temperature at 

the pressure within the absorber. 

• Mountaineer stated that the liquid to gas (L/G) ratio is 120 gallons/1000 

acfm. The L/G ratio for limestone forced oxidation systems is higher than 

that of AEP’s Gavin power plant, which has a L/G ratio of 28-32. Gavin 

is a magnesium-enhanced chemistry that operates at a greater alkalininty 

than the limestone forced oxidation process and so requires less L/G. 

The SO2 removal rate is dependent upon how fast SO2 can be absorbed 

into the liquid phase. The low alkalinity of limestone chemistry thus 

makes absorption the rate-limiting factor. Higher alkalinity systems (i.e., 

AEP’s Gavin plant) are not rate-limited by the absorption of SO2 and thus 

can operate at lower L/Gs. As a result, higher L/G ratios are needed for 

limestone-based chemistries. 

• Mountaineer stated that the mist eliminators are layers of “Z” shaped 

packing that provide areas for water droplets to collect, nucleate, and fall 

back into the FDG scrubber. The plant washes the mist eliminators with 

fresh water to prevent plugging. 
Page 5 

• Mountaineer typically blows down the FGD slurry from scrubber modules 

when the percent solids in the modules reaches 17 percent. The blowdown 

is operated until the percent solids is reduced to approximately 14 percent. 

The maximum allowable solids content in the scrubber is 20 percent. 

• Mountaineer stated that the size of the gypsum crystals is affected greatly 

by residence time, and degree of agitation. 

• Mountaineer stated that the design chlorides concentration in the scrubber 

is a maximum of 12,000 ppm. The scrubber purge is generated 24 hours

per day, 5 days per week. The flow rate is typically 270 gpm, which can 

increase to 350 gpm. The purge contains 5,000-6,000 ppm chlorides. 

• The blowdown from the FGD scrubber is sent to one of three sets of 

hydroclones. The underflow from the hydroclones contains 58 percent 

solids. 

• Mountaineer transfers the hydroclone underflow to one of three vacuum 

belt filters. The vacuum belt filters handle 83 tons of gypsum per hour and 

dry the gypsum to approximately 10 percent moisture content.

Mountaineer does not wash the gypsum on the vacuum belt filter. 

• Mountaineer estimated that the final gypsum product has a chlorides 

concentration of 10,000 ppm. 

• The overflow from the hydroclones, which contains five percent solids, is 

either returned to the FGD scrubber or transferred to a purge tank and sent 

to the FGD wastewater treatment system. 

• The filtrate from the vacuum belt filter is recycled back to the FGD 

scrubber system. 

• The Mountaineer plant does not sell any of the gypsum produced. All of 

the gypsum is landfilled. Mountaineer stated that a small amount of water 

is added to the gypsum product at the landfill for handling and landfilling. 

• In addition, off-specification gypsum produced at the Mitchell plant 

(located in Moundsville, WV) is transferred to Mountaineer for disposal. 

• The landfill where the gypsum solids are sent has a “No free liquid” 

requirement, which means that the gypsum must not contain any water 

that easily flows off of the solids. 

• Plant personnel stated that there is no market for the Mountaineer gypsum 

because the plant is too far away from major highways. 
Page 6 

Mountaineer FGD Wastewater Treatment System 

• The overflow from the hydroclone is sent to the purge tank and then 

transferred to the Mountaineer FGD wastewater treatment system. 

Mountaineer stated that the design flow rate from the purge tank is 350 

gpm. 

• Mountaineer stated that a portion of the FGD wastewater has to be purged 

from the system because otherwise chlorides would build up in the system 

and the metallurgy of the system cannot handle the high chlorides 

concentrations. Mountaineer stated the goal of the FGD wastewater 

treatment system is to remove solids and control the pH of the FGD 

wastewater before discharging to the Ohio River. 

• From the purge tank, the FGD wastewater is transferred to one of two 

desaturation tanks, each 11,800 gallons, where lime is added to increase 

the pH from approximately 5.6 to 8.2. 

• The overflow from the desaturation tanks is transferred to the primary 

clarifiers. Each desaturation tank has a designated primary clarifier. Each 

clarifier is 30 feet in diameter. As the wastewater flows to the primary 

clarifier, an anionic polymer (GE 1125) is added to the wastewater. The 

primary clarifiers are designed to remove 95% of the solids present in the 

wastewater. 

• The underflow from the primary clarifiers is transferred to a sludge tank 

for temporary storage and then sent through a filter press for dewatering. 

The filter press cake is sent to a landfill. 

• The overflow from the two primary clarifiers are combined and transferred 

to the equalization tank. The filtrate from the filter press is also 

transferred to the equalization tank. 

• From the equalization tank, the wastewater undergoes iron coprecipitation and coagulation. The wastewater is transferred to the ferric 

chloride mix tank. Mountaineer stated that they no longer add ferric 

chloride to this tank. Instead they add a cationic polymer (GE 1195). 

 

• The overflow from the ferric chloride mix tank is split and enters two 

secondary clarifiers, each 30 feet in diameter, where an anionic polymer is 

added (GE 1125). The underflow from the secondary clarifiers is recycled 

back to the primary clarifiers. The overflow from the two secondary 

clarifiers are combined and transferred to a 15,000 gallon effluent storage 

tank. 

• From the effluent storage tank, the FGD wastewater is transferred to the 

clearwater pond and then discharged to the Ohio River. 
Page 7 

• Mountaineer stated that this system is operated 24 hours a day, 5 days a 

week. The typical flow rate of the purge stream is 270 gallons per minute 

and can be as high as 350 gallons per minute. 

• Mountaineer stated that the chlorides levels in the effluent of the FGD 

wastewater treatment system range between 5,000 to 6,000 ppm. 

• Mountaineer stated that they regularly monitor the FGD wastewater 

effluent for TSS and pH. However, the Mountaineer plant does not have a 

NPDES permit for the effluent from the FGD wastewater treatment 

system, since it discharges into the plant’s pond complex which does have 

an NPDES permit. 

Landfill 

• Mountaineer stated that its fly ash is compacted and transported to its 

landfill.

• An underground collection system directs the runoff and leachate from the 

fly ash to the leachate collection pond. The leachate collection pond also 

receives leachate from the FGD gypsum pile. 

• Mountaineer estimated that a combined total of 3,500 tons of fly ash and 

gypsum are generated every day. 

• The overflow from the leachate collection pond flows into the wastewater 

ponds. 

• Uncontrolled runoff from this landfill flows to a storm outfall. 

CO2 Capture Project 

• [CBI information has been removed from this document.] 

Mountaineer FGD Wastewater Treatment Pilot Testing 

• [CBI information has been removed from this document.] 
Page 8 

Table 1. Site Visit Attendees 

Name Organization (Representing) Telephone E-maRandy Brown Appalachian Power Company - Mountaineer (304) 882-4024 rlbrown4@aepDave Hall Appalachian Power Company - Mountaineer (304) 882-4071 drhall@aep.coJ.L. Perry Appalachian Power Company - Mountaineer (304) 882-4106 jlperry@aep.coCharlie Powell Appalachian Power Company - Mountaineer (304) 882-4100 capowell@aepGreg Price Appalachian Power Company - Mountaineer (304) 882-4020 gkprice@aep.cBrian Sherrick Appalachian Power Company - Mountaineer (614) 716-1923 bdsherrick@aeDavid Thompson Appalachian Power Company - Mountaineer (304) 882-4023 rdthompson1@Paul Cree American Electric Power (614) 716-1845 ptcree@aep.coTom Hart American Electric Power (614) 716-3260 tomlhart@aepAmanda Janasov American Electric Power (614) 716-3751 agjanasov@aeTim Lohner American Electric Power (614) 716-1255 twlohner@aepMark O’Brien American Electric Power (614) 716-1852 mobrien@aep.Brent Watts American Electric Power (304) 882-4115 mbwatts@aepDonna Hill Southern Company. (205) 257-5234 dbhill@southeJosh Hall EPA/Office of Water (202) 566-1002 hall.josh@epaRon Jordan EPA/Office of Water (202) 566-1003 jordan.ronald@Deb Bartram ERG (Contractor to EPA) (703) 633-1669 deborah.bartra
Page 9 

Kurt Blohm ERG (Contractor to EPA) (703) 633-1675 kurtis.blohm@

T.J. Finseth ERG (Contractor to EPA) (703) 994-7130 thomas.finseth

B A

2

1

8765439

E D A IGS0700 2 1 CM H G 7 6 5 4 F 3 INCH 16 16 12 4 3 J 

TENT

J H G F E D

C BC

1-5180000


Flue Gas Desulfurizatio

(FGD) System
Mountaineer FGD Design

• 1300 MW (Net) generating unit• Wet limestone with forced oxidation• Designed for 98 % SO2 Removal• 7.5 lb SO2/MMBtu Coal• 2 absorber towers – open spray type• 2,600,500 acfm gas flow per absorber• 350 Deg F flue gas temperature
Mountaineer FGD System

• Reagent Unloading and Storage System• Reagent Preparation System• Absorption System• Dewatering System• Wastewater Treatment System

Reagent Unloading and Sto

• Unloading Crane – Rated 1500 tph• Unloading Conveyor – Rated 1500 tph• Active Limestone Stockpile – 15,000 ton• Reclaim Feeders (2) – Rated 400 tph• Reclaim Conveyor – Rated 400 tph• Limestone Storage Silos (2) – 1400 ton • Limestone Size – 0 x 3⁄4 inch
Reagent Preparation

• Limestone Weigh Feeders (2) - Rated 90 tph• Ball Mills (2) - Rated 90 tph - Motor 4100 hp• Limestone Size Reduced to 95 % < 325 mesh• Mill Recycle Tank - 8,900 gallon storage • Mill Recycle Pumps (2) - 2300 gpm• Mill Product Classifier (2) – 17 hydrocyclones• Reagent Storage Tank (2) – 226,000 gallon st• Reagent Feed Pumps (2) – 2087 gpm 
MILL SUMP TANK w/ AGITATOR

WEIGH FEEDER

HYDROCYLONE

BALL MILL

DRIVE SYSTEM

MILL

WATER

SUMP

WATER

FE

LT

PT

FE

FE FLOW ELEMENTDE DENSITY ELEMENT (NUCLEAR)PT PRESSURE TRANSMITTERLT LEVEL TRANSMITTER

LT

FRESH

FEED

DAY SILO w/ BIN VENT

TYPICAL LIMESTONE 

GRINDING CIRCUIT 

TYPICAL LIMESTONE 

GRINDING CIRCUIT

DRAIN
Absorber Island Equipment

• Absorber 2205 Alloy, 60+’ dia. x 195’• Recycle Pumps (6) – 76,075 gpm (hp 2-• Absorber Blowdown Pumps (2) – 2182 g• Oxidation Air Blowers (3) – 2500 hp• Reaction Tank Agitators (7) – 75 hp• ME Wash Pumps (2) – 848 gpm• Makeup Water Pumps (2) – 3120 gpm• Purge Pumps (2) – 363 gpm
Mountaineer L/G = 120

Liquid-to-Gas Ratio
Mechanism of SO2 Absorpti

Flue GasScrubber Liquor

SO2(g)

SO2(L)

Sulfur

Dioxide

H2 SO3(L)

Sulfurous

Acid

H2 

O(L)

Water

+

H2 SO3(L)

Sulfurous

Acid

2H

+

(L)

Hydrogen

Ion

+ SO

3

-

(L)

Sulfite

Ion

Dissociates
Simplified Equation for Process Chem

SO2 (g)

Sulfur

Dioxide

CaCO3 (s)

H2 

O(L)

Calcium 

Carbonate

+ + CaSO3 1/2 

H2 

O(s)

Calcium Sulfite

+ 

CO2 (g

Carbon 

Dioxid

Process Chemistry
OXIDATION

+ 1⁄2 O

2 CaSO4 2H2 

O

Calcium Sulfate Dihydrate (g

CaSO3 1⁄2 H2 

O
FGD Absorber
H2 

O

SO

2

SO

2

SO

2

SO

2

SO

2

Greater L/G

gpm/1000acfm
CaSO4 CaSO H 4 2 CO2

SO2

H2 SO3

SO2 SO2

H2 SO3

SO2

CaSO3 CaCO3

SO2

H2 SO3

SO2

CaCO3

O

H2 SO3

CaSO CaSO34

CO2 H2 

O
Mountaineer Recycle Pump
Mountaineer Absorber Towe
Mountaineer Absorber Towe
Mountaineer Recycle Spray He
Mountaineer Recycle Spray No

Mountaineer Mist Eliminato
Dewatering Island Equipme

• Hydrocyclone Classifiers (3) – 15 each • Vacuum Belt Filters (3) – 83 tph (106 

plates)

• Vacuum Pumps (3) – 600 hp• Filtrate Return Pumps (3) – 375 gpm• Gypsum Conveying System - 1500 tph
Mountaineer Hydrocyclones
Hydrocyclone is a device used to separate particles based on size and specific gravity
Mountaineer Vacuum Belt F
Mountaineer FGD Process

Limestone + SO2 Reaction Products 

87 TPH 49 TPH 136 TPHWater Evaporation + Gypsum + CPS537 TPH 428 TPH 23 TPH 86 T

(1700 gpm) (92 gpm) (340 g

Gypsum Solids + Water Gypsum (Landfil

136 TPH 23 TPH 159 TPH

1300 MW (Net) Unit

4.5% Sulfur, 12,000 Btu/lb

SO2 Emission = 0.98 TPH
FGD Wastewater Treatment S

• HCL is removed by FGD• Leads to chloride ion accumulation in FGD• FGD Designed for maximum chloride ion 

concentration of 12,000 ppm based on metallu

• To control chlorides in FGD process, must pur

portion of the liquid from the FGD System

• Function of WWT System is to remove TSS an

adjust the pH of the FGD Chloride Purge Stea(CPS)
FGD WWT System Design

• 350 gpm treatment capacity• Effluent TSS of 30 mg/L monthly averag

and 100 mg/L daily maximum

• Effluent pH between 6.5 and 9.0 • Add no oil & grease to the influent• No Free Liquid in Filter Cake• Minimum of 40 % Solids in Filter Cake
FGD Wastewater Treatment Equip

• Desaturation Tanks (2) – 11,800 gallons• Primary Clarifiers (2) – 30 ft diameter• Lime Storage Silos (2) – 60 tons• Equalization Tank (1) – 92,000 gallons• Ferric Chloride Mix Tank (2) – 5,850 gallons• Secondary Clarifiers (2) – 32 ft diameter• Effluent Storage Tank (1) – 15,000 gallons• Sludge Feed Tanks (2) – 20,490 gallons• Plate & Frame Filter Presses (2) – 510 ft3
Mountaineer FGD WWT System
Mountaineer FGD WWT Sys
Mountaineer Plate & Frame Filter P
Mountaineer Plate & Frame Filter P
SO3 Mitigation

(SO3 ) System
What is Sulfur Trioxide?

• Sulfur Trioxide (SO3 

)

exists in the flue gas 

• At high concentrations 

SO3 will cause a visible, blue plume 

• SO3 readily combines with H2 O to form Sulfuric Acid (H2 SO4 

)

• AEP is committed to 

mitigate SO3 to enhance plume appearance

• Mitigation Target: 10 ppm 

SO3 at the stack
SO3 Sources

• Furnace Generated• SCR Generated

2

2

3 1 2

2

2

OSO SO

OS SO

heat

heat

 

 

2

2

3 1 2 OSO SO  catalyst  

2

2

3 1 2 OSO SO  catalyst  
SCR

ML1

7.51.2

665

0.31

2540

Coal Sulfur Content (lb/MMBtu)

Boiler Conversion (%)

SCR Inlet Temperature (°F)

SCR Conversion (%)

AH Removal (%)

FGD Removal (%)

Boiler 

Generated 

SO3 ECONOMIZER 

OUTLET

SCR 

OUTLET

AH Outlet

BOILER

AIR HEATER

ESP

SCRUBB

SCR

ESP Outlet

Sc

GeneratedSO3

42 ppm

53 ppm

33 ppm

20 

MT1

SO3 Concentrations – Without Mitig

Coal Sulfur Content (lb SO2/MMBtu) 7.5Boiler SO2 to SO3 Conversion (%) 1.1 to 1.3SCR SO2 to SO3 Conversion (%) 0.30 to 0.35Air Heater SO3 Removal (%) 20 to 30FGD SO3 Removal (%) 35 to 40

49 to 58 ppm

34 to 46 ppm

38 to 46 ppm

2
Sorbents for SO3 Mitigation

AEP has tested various sorbents for SO3 contro
SO3 Mitigation Plan

• Removal Target: 10 ppm 

SO3 at the stack

• Options :

– Magnesium Hydroxide 

Injection in the furnace

– Lime Injection post Air 

Heater

– Trona Injection post Air 

Heater

• Performance• Availability• Economics

Mg(OH)2 Lime 

SR 7 to 1 4 to 1 

Max 

Removal 80-90% 40-50% 

Cost (per 

ton) high low 

Delivery Truck - from MI multiple 

f

Availability low high 

Trona is the SO3 sorbent of choice for AE
Trona, 

• Trona, Sodium 

Sesquicarbonate, is mined as a raw material for the production of soda ash

• Average Particle 

Size = 28 micron

CONa 32  NaHCO 2 23 OH
Trona/SO3 Reaction at High Tempe

2 CONa 32 NaHCO

2 23  heatOH  

3 32

2 

5

2OHCOCONa



 SOCONa 332   42

COsSONa 2

  OHSOsSONa

lNaHSO

 42 23

4 

2

  OHSOsSONa

sNaHSO

 42 23

4 

2
Mountaineer Unit 1, Duct 3 Temperature Profile at the A• The worst case temperature profile was used for equipme

expected increase due to furnace slagging (°5F)

Tem(°F)

3

3

Modeled Temperature Profile at Test Port Plane
Selective Catalytic Reduct

(SCR) System
What is an SCR?

• SCR stands for 

Selective 

Catalytic 

Red

• Nitrogen Oxide (NOx) is formed during t

combustion process and is present in thexhaust gas from the steam generator

• Ammonia is used as the reagent, and is 

into and is thoroughly mixed with the NOflue gas upstream of the SCR reactor.
What is an SCR?

• Ammonia reacts with the NOx in th

presence of a catalyst to form harmelemental nitrogen and water vapo

• Reduction process takes place in t

exhaust gas temperature regime be600 and 800o 

F

• Removal efficiencies >90% can be 

achieved
SCR Chemical Reaction 

• NOx is comprised of NO and NO

2

• In the presence of free O2 in the flu

the NH3 injected into the gas stream 

passed over catalyst. This results in following chemical reactions:

• 4NO + 4NH3 + 

O2 ===> 4N2 + 6H2 

O

• 2NO2 + 4NH3 + 

O2 ====> 3N2 + 6H2 

O
SCR Principles
View of Top of Catalyst Layer Inside Re
Catalyst Replacement

2.521.51.5

2

4

6

8 10 12 

Years

Ammonia Slip (ppm)

NewReplace

Empty
Urea (NH2 

)2 CO to Ammonia Conve

• Urea is a stable white, granular powder 

under atmospheric conditions 

• Urea is typically used as a fertilizer and 

not classified as Toxic by Fed. Regulations

– Permitting & Reporting are greatly simplified

• One pound of urea can provide ~ 0.56 

lbs. of Ammonia

– Cost per equivalent mass of ammonia is 

higher than anhydrous
Urea to Ammonia Conversio

• Process Consists of

– Preparation of a 40 to 50% solution 

using demineralizer water

– hydrolyzing and flashing at 450 °F wi

supplemental heat (usually steam) to obtain a vapor mix of ammonia, carbodioxide, and water

– Direct injection into the flue gas 

stream.
AODTM Process Flow Diagram Process Flow Diagram

DRY UREA 

UREA

FEED

SILO

MIX

TANK

RECYCLE

SOLUTION

STORAGE

TANK

UREA

SOLUTION

STORAGE

TANK

AMMONIA

TO SCR

HYDROLYZER

ECONOMIZER

STEAM

DI

WATER

F F

AODTM

PROCESS FLOW DIAGRAM

UREA SOLUTION STORAGE OPTION

Hg Capture
Background

• USEPA Introduced the Clean Air Mercu

(CAMR) in March 2005

– National Cap & Trade Program– Phase 1: Approximate 30% Reduction fro

Levels in 2010

– Phase 2: Approximate 70% Reduction fro

Levels in 2018

– Allocations Determined by States

• Mercury Monitors Required on All Utility 

by 1-1-2009
• SCR/WFGD Co-Benefits

– Proven Capture, Capital Intensive

• Activated Carbon Injection (ACI)

– Most Proven Hg-Specific Capture Method

• Fuel Switching/Blending

– Lower Reductions, Fuel Variability

• Boiler Chemical Additives (BCA)

– Limited Research, Varied Results

• Non-Carbon Sorbents

– Some Promise, Still Developing Technolo

Mercury Capture Technol
• Baseline Emissions

– Approx. 6 tons/year

• SCR-FGD Retrofits are Backbone of Plan

– Assume 85-86% co-benefit Hg reduction w/Bitumi– Reduce Hg by >2.5 tons/year in AEP System

• Make Up Difference with ACI-ESP

– Reduce Hg by approx. 1 ton/year

• Phase II Requires Dramatically More Controls

– Reduce Hg by approx. another 1.5 ton/year– Development of new technologies will be investiga

AEP CAMR Strategy
Activated Carbon Injectio

• Full Scale Testin

Performed at ThFacilities, 30-DaTerm Tests

– Bituminous/PR

• Standard C

– Texas Lignite

• Brominated 

– 100% PRB

• Brominated