## BART D ETERMINATION 

## R EPORT 

## A MERICAN 

## E LECTRIC 

## P OWER 

##  S OUTHWESTERN 

## P OWER 

## S TATION 

## U NIT 

## 3

Prepared by:

N.N. Dharmarajan  AEP

Vern Choquette  Principal Consultant Eugene Chen, PE  Senior Consultant Jeremy Townley  Consultant

T RINITY C ONSULTANTS 120 E. Sheridan Suite 205 Oklahoma City, OK 73104 (405) 228-3292

August 2008

Project 083701.0057AEP Trinity Consultants BART Determination Southwester n Power station Unit 3 083701.0057 i 

## T ABLE OF 

## C ONTENTS



### 1. E XECUTIVE 

### S UMMARY 

### ........................................................................................ 1-1

2. B ACKGROUND 

### ...................................................................................................... 2-1 2.1 BART A PPLICABILITY 

### .......................................................................................... 2-1
2.1.1 CALPUFF M ODELING A NALYSES ......................................................................2-3 

### 2.2 BART D ETERMINATION 

### ....................................................................................... 2-3

3. BART A PPLICABILITY 

### A NALYSIS 

### ...................................................................... 3-1 3.1 BART-E LIGIBLE 

### S OURCES 

### ................................................................................... 3-1 3.2 S OURCE 

### E MISSIONS 

### D ATA 

### .................................................................................... 3-1
3.2.1 PM E MISSIONS ....................................................................................................3-1
3.2.2 S TACK PARAMETERS ...........................................................................................3-2



### 4. SO 2 

### BART D ETERMINATION 

### .............................................................................. 4-1 4.1 I DENTIFICATION OF 

### A VAILABLE 

### R ETROFIT 

### SO 2 

### C ONTROL 

### T ECHNOLOGIES 

### .......... 4-1

5. PM BART D ETERMINATION 

### .............................................................................. 5-1 5.1 I DENTIFICATION OF 

### A VAILABLE 

### R ETROFIT 

### PM C ONTROL 

### T ECHNOLOGIES 

### ........... 5-1

6. NO X 

### BART D ETERMINATION 

### .............................................................................. 6-1 6.1 I DENTIFY 

### A LL 

### A VAILABLE 

### R ETROFIT 

### T ECHNOLOGIES 

### .......................................... 6-1 6.2 E LIMINATE 

### T ECHNICALLY 

### I NFEASIBLE 

### O PTIONS 

### .................................................. 6-2
6.2.1 R EDUCED B URNER S ERVICE ...............................................................................6-2
6.2.2 I NDUCED F LUE G AS R ECIRCULATION (FGR) .....................................................6-2
6.2.3 L OW NO X B URNERS (LNB) WITH O VERFIRE A IR (OFA)...................................6-2 

### 6.3 E VALUATE 

### E FFECTIVENESS OF 

### R EMAINING 

### C ONTROL 

### T ECHNOLOGIES 

### ................ 6-3 6.4 E VALUATION OF 

### I MPACTS FOR 

### F EASIBLE 

### NO X 

### C ONTROLS 

### ................................... 6-3
6.4.1 C OSTS OF C OMPLIANCE ......................................................................................6-3
6.4.2 E NERGY AND N ON

- AIR I MPACTS ........................................................................6-4
6.4.3 R EMAINING U SEFUL L IFE ...................................................................................6-4 

### 6.5 E VALUATE 

### V ISIBILITY 

### I MPACTS 

### ........................................................................... 6-4 6.6 P ROPOSED 

### B ART FOR 

### NO X 

### .................................................................................... 6-5

A PPENDIX 

### A

– E MISSION 

### E STIMATES



### A PPENDIX 

### B

- E CONOMIC 

### A NALYSES



### A PPENDIX 

### C

– CALPUFF M ODELING 

### P ROTOCOL



### A PPENDIX 

### D

– M ODELING 

### I NPUT 

### /O UTPUT 

### F ILESAEP Trinity Consultants BART Determination Southwester n Power station Unit 3 083701.0057 ii 

## L IST OF 

## F IGURES

T ABLE 3-1. C ONSTRUCTION D ATE S UMMARY ...................................................................................3-1

T ABLE 3-2. P RE -BART E MISSIONS S UMMARY ..................................................................................3-1

T ABLE 3-3. PM S PECIATION P ROFILE .................................................................................................3-2

T ABLE 3-4. S PECIATED PM E MISSIONS ..............................................................................................3-2

T ABLE 3-5. P OINT S OURCE S TACK P ARAMETERS ..............................................................................3-2

T ABLE 4-1. B ASELINE M AXIMUM 24-H OUR SO 2 E MISSION R ATES ...................................................4-1

T ABLE 4-2. A VAILABLE SO 2 C ONTROL T ECHNOLOGIES ....................................................................4-1

T ABLE 4-3. SO2 E MISSION E STIMATES (N ATURAL G AS )...................................................................4-1

T ABLE 5-1. E XISTING M AXIMUM 24-H OUR PM E MISSION R ATES .....................................................5-1

T ABLE 5-2. A VAILABLE PM C ONTROL T ECHNOLOGIES .....................................................................5-1

T ABLE 5-3. PM E MISSION E STIMATES ................................................................................................5-1

T ABLE 6-1. E XISTING M AXIMUM 24-H OUR NO X E MISSION R ATE .....................................................6-1

T ABLE 6-2. A VAILABLE NO X C OMBUSTION C ONTROL T ECHNOLOGIES ............................................6-1

T ABLE 6-3. C ONTROL E FFECTIVENESS OF T ECHNICALLY F EASIBLE NO X C ONTROL T ECHNOLOGIES 6-3

T ABLE 6-4. NO X C ONTROL C OSTS S UMMARY ...................................................................................6-4

T ABLE 6-5. S OUTHWESTERN U NIT 3 V ISIBILITY I MPACTS .................................................................6-5AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 1-1 

## 1. E XECUTIVE 

## S UMMARY

American Electric Power/Public Service Comp any of Oklahoma (AEP) owns and operates the Southwestern Power Station, located near Washita, OK. The Southwestern station is an electricity generating station that operates multiple natural-gas fired utility boilers and is a Title V major source of emissions.

Based upon the construction date of the sources at th e Southwestern station, AEP has determined that one unit is eligible to be regulated under the B est Available Retrofit Technology (BART) provisions of the U.S. Environmental Protection Agency’s ( EPA) Regional Haze Rule as established in Title 40, Code of Federal Regulations Part 51 (40 CFR 51) . Southwestern Unit 3 is the only unit that comprises the BART-eligible source at the Southwestern Station.

AEP has determined that Southwestern Unit 3 contributes greater than 0.5 deciviews ( ∆ dv) to visibility impairment in a federally protected Cl ass I area when compared to a natural background. As a result, it does not qualify for exemption and is subject to a BART determination. Per the guidelines in 40 CFR Part 51 1 , a BART determination for SO 2 , NO X , and PM was performed using the five-step analysis that included the following:

1. Identifying all available retrofit control technologies;

2. Eliminating technically infeasible control technologies;

3. Evaluating the control effectiveness of remaining control technologies;

4. Evaluating impacts and document the results;

5. Evaluating visibility impacts

Based on the five-step analysis, AEP proposes the following as BART:

• PM – AEP proposes the use of natural gas at the Southwestern Power Station Unit 3 as BART for PM. Continued use of natural gas w ill ensure an emission rate lower than what could be achieved with add-on PM controls.

• SO 2 – AEP also proposes the use of natural g as at the Southwestern Power Station Unit 3 as BART for SO 2 . As with PM emissions, natural gas use is able to ensure SO 2 emissions lower than add-on SO 2 controls.

• NO X – AEP proposes emission rates of 0.45 lb/MMBtu as BART for NOx. This will be achieved by installing Low NOx burners (LNB)/overfire air (OFA) system

1 40 CFR 51, Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) DeterminationsAEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 2-1 

## 2. B ACKGROUND

On July 1, 1999, the U.S. Environmental Protec tion Agency (EPA) published the final Regional Haze Rule (RHR). The objective of the RHR is to impr ove visibility in 156 specific areas across the United States, known as Class I areas. The Clean Air Act defines Class I areas as certain national parks (over 6,000 acres), wilderness areas (over 5,000 acres), national memorial parks (over 5,000 acres), and international parks that were in existence on August 7, 1977.

On July 6, 2005, the EPA published amendments to its 1999 RHR, often called the BART rule, which included guidance for making source-specific B est Available Retrofit Technology (BART) determinations. The BART rule defines BART-e ligible sources as sources that meet the following criteria:

(1) Have potential emissions of at least 250 tons per year of a visibility-impairing pollutant, (2) Were “in existence” between August 7, 1962 and August 7, 1977, and (3) Are listed as one of the 26 listed source categories in the guidance.

A source that meets these criteria is considered elig ible for BART and must then determine if BART applies.



## 2.1 BART A PPLICABILITY

Per the U.S. EPA’s BART Modeling Guidance, “an individual source will be considered to ‘cause visibility impairment’ if the emissi ons results in a change (delta ∆ ) in deciviews (dv) 2 that is greater than or equal to 1.0 deciview on the visibility in a Class I area...if the emissions from a source results in a change in visibility that is greater than or equal to 0.5 dv in a Class I area the source will be considered to ‘contribute to visibility impairment .’” To determine whether a BART-eligible source causes or contributes to visibility impairment, the U.S. EPA guidance requires the use of an air quality model, specifically recommending the CALPUFF modeling system, to quantify the impacts attributable to a single BART-eligible source. Because contribution to visibility impairment is sufficient cause to require a BART determination, 0.5 dv is the critical threshold for assessment of BART applicability.

Regional haze is quantified using the light extinction coefficient ( b ext ), which is expressed in terms of the haze index ( HI ) expressed in dv. The HI is calculated as shown in the following equation.

       

= 10 ln 10 ext b HI

The impact of a BART-eligible source is determined by comparing the HI attributable to a source to estimated natural background conditions. That is, a single-source visibility impact is measured as the

2 The deciview (dv) is a metric used to represent norma lized light extinction attributable to visibility-affecting pollutants.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 2-2 change in light extinction versus background, and is referred to as ∆ dv. The background extinction coefficient is affected by various chemical sp ecies and the Rayleigh scattering phenomenon and can be calculated as shown in the following equation.



# ( ) Ray EC Coarse Soil OC NO SO background ext b b b b b b b b + + + + + + = −

3 4 1

, Mm

where:



### ( ) 

## [ ] ( ) 

### [ ] ( ) 

### [ ] [ ] [ ] [ ] 

# ( ) ( ) 

### [ ] 3 1 3 4 4

2 4

m μg in ion Concentrat Function Humidity Relative default by Mm 10 Scattering Rayleigh

EC 10 Mass Coarse 6

. 0 Soil 1 OC 4 NO

NH 3 SO

NH 3

3 4

= =

= = = = = = =

−

RH f b b b b b RH f b RH f b

Ray

EC Coarse Soil OC NO SO 

### ( ) 

## [ ] [ ] [ ] [ ] [ ] [ ]

molecules air to due scattering is Scattering Rayleigh carbon elemental of ion concentrat the denotes EC dusts coarse of ion concentrat the denotes Mass Coarse soils fine of ion concentrat the denotes Soil carbon organic of ion concentrat the denotes OC ion concentrat nitrate ammonium the denotes NO NH ion concentrat sulfate ammonium the denotes SO NH

3 4 4 2 4

Values for the parameters listed above specific to the natural background conditions at each Class I area are provided on an annual-average basis in the U.S. EPA’s Guidance for Estimating Natural Visibility Conditions under the Regional Haze Rule

. 3

Particulate species that affect visibility are em itted from anthropogenic (human-caused) sources and include coarse particulate matter (PMC), fine partic ulate matter (PMF), and elemental carbon (EC) as well as precursors to secondary organic aerosols (SOA) and fine particulate matter such as SO 2 and
NO X . The extinction coefficient due to emissions of visibility-affecting pollutants from a single BART-eligible source is calculated according to the following equation. 

# ( )

EC PMC PMF SOA NO SO source ext b b b b b b b + + + + + = −

3 4 1

, Mm

where:

3 U.S. EPA, Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule , Table 2-1, Attachment A, September 2003, EPA-454/B-03-005.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 2-3 

### ( ) 

## [ ] ( ) 

## [ ] ( ) 

## [ ] [ ]

[ ] [ ] ( ) 

## [ ] 3 3 4 3 4 2 4 4

m μg in ion Concentrat Function Humidity Relative EC 10 PMC 6

. 0 PMF 1 SOA 4 NO

NH 3 SO

NH 3

= =

=

= = = = =

RH f b b b b RH f b RH f b

EC

PMC PMF SOA NO SO 

### ( ) 

## [ ] [ ] [ ] [ ] [ ] [ ] carbon elemental of ion concentrat the denotes EC PM coarse of ion concentrat the denotes PMC PM fine of ion concentrat the denotes PMF aerosols organic secondary of ion concentrat the denotes SOA ion concentrat nitrate ammonium the denotes NO NH ion concentrat sulfate ammonium the denotes SO NH

3 4 4 2 4



### 2.1.1 CALPUFF M ODELING 

### A NALYSES

As stated above, the BART Guidelines r ecommend using the CALPUFF modeling system to compute the 24-hour average visibility impa irment attributable to a BART-eligible source to assess whether the 0.5 ∆ dv contribution threshold is exceeded, and if so, the frequency, duration, and magnitude of any exceed ance events. As descr ibed further in the modeling protocol included in Appendix A, CALPUFF is a refined air quality modeling system that is capable of simulating the di spersion, chemical transformation, and longrange transport of multiple visibility-affecting pollutant emissions and is therefore preferred for BART applicability and determination analyses.



## 2.2 BART D ETERMINATION

BART-eligible sources that are found to cause or contribute to visibility impairment at a Class I area are required to make a BART determination. The BART Guidelines define BART as follows:

BART means an emission limitation based on th e degree of reduction achievable through the application of the best system of continuous emission reduction for each pollutant which is emitted by...[a BART-eligible s ource]. The emission limitation must be established, on a case-by-case basis, taking in to consideration the technology available, the costs of compliance, the energy and non-air quality environmental impacts of compliance, any pollution control equipment in use or in existence at the source, the remaining useful life of the source, and the de gree of improvement in visibility which may reasonably be anticipated to result from th e use of such technology. The BART analysis identifies the best system of continuous emission reduction taking into account:

(1) The available retrofit control options, (2) Any pollution control equipment in use at the source (which affects the availability of options and their impacts), (3) The costs of compliance with control options, (4) The remaining useful life of the facility, (5) The energy and non-air quality environmental impacts of control options [ , and ] (6) The visibility impacts analysis.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 2-4 Further, the BART rule indicates that the five b asic steps in a BART analysis can be summarized as follows:

1. Identify all available retrofit control technologies;

2. Eliminate technically infeasible control technologies;

3. Evaluate the control effectiveness of remaining control technologies;

4. Evaluate impacts and document the results;

5. Evaluate visibility impacts

As summarized in Section 3, AEP conducted a BA RT applicability analysis for the Southwestern Power Station Unit 3 determined that it is indeed subject to BART. The BART determinations for each of the three visibility affecting pollutants (SO 2 , NOx, and PM) can be found in Sections 3 through 5.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 3-1 

## 3. BART A PPLICABILITY 

## A NALYSIS



## 3.1 BART-E LIGIBLE 

## S OURCES

In order to determine what specific units constitu te the “BART-eligible” source, the construction dates of the each of the plant’s units must be exam ined. A summary of all units at the Southwestern Station is provided below. As seen from this tabl e, the only unit that was “in existence” within the 15-year BART window (August 7, 1962-August 7, 1977) is Unit 3.

T ABLE 3-1. C ONSTRUCTION D ATE S UMMARY

Unit
No. Heat Duty (MMBtu/hr) Manufacturer Construction Date

1N 482 Babcock/Wilcox, S-1853 Jan. 1952 1S 482 Babcock/Wilcox, S-9747 Jan. 1952 2 940 Babcock/Wilcox, S-9742 Feb. 1954
3 3,290 Babcock/Wilcox, RB-426 May 1967



## 3.2 S OURCE 

## E MISSIONS 

## D ATA

In developing baseline emissions, Trinity utilized a combination of operating records and continuous emission monitoring (CEM) data provided by AEP over a period extending from 2001-05. Modeled emissions are based on the highest hourly emissi on rate (on 24-hour calendar day average) that occurred from 2001 to 2005. A summary of these emissi ons is presented in Table 3-2 below. A more detailed analysis of historical em issions is included in Appendix A.

T ABLE 3-2. P RE -BART E MISSIONS S UMMARY

Unit No. NO x PM SO 2 H 2 SO 4 lbs/hr lbs/hr lbs/hr lbs/hr SW3 3705 24.5 1.97 0.30

Please note that SW3 operated entirely on natural gas from 2001-05.



### 3.2.1 PM E MISSIONS

PM emissions are not directly entered into the model but are instead speciated into constituent components. The PM emissions from the boilers can be speciated according to the Federal Land Managers’ guidance to potentially include the following:

S Coarse particulate matter (PM C , considered PM 2.5-10 )

S Fine particulate matter (PM F , considered PM <2.5 )AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 3-2 S Sulfates (SO 4 )

S Secondary organic aerosols (SOA)

S Elemental carbon (EC)

Based upon FLM guidance, PM emissions from natural gas combustion consists of primarily coarse (25%) and fine (75%). 4 A summary of speciated PM emissions is presented in Table 3-3 below.

T ABLE 3-3. PM S PECIATION P ROFILE

Particulate Matter Species Fraction PM Coarse (Soil) 25% Elemental Carbon (EC) 0%
PM Fine 75% Secondary Organic Aerosols (organic carbon) 0%

Total 100%

A summary of speciated PM emissions from the Southwestern Unit 3 is presented below.

T ABLE 3-4. S PECIATED PM E MISSIONS

Unit No. PM (coarse) 4 PM (fine) 4 EC 4 SOA 4

lbs/hr lbs/hr lbs/hr lbs/hr SW3 6.13 18.39 0 0



### 3.2.2 S TACK PARAMETERS

Table 3-5 provides a summary of source exhaust parameters.

T ABLE 3-5. P OINT S OURCE S TACK P ARAMETERS

Emission
unit Latitude (decimal degrees) Longitude (decimal degrees) Exit Velocity

(ft/s) Stack Height (feet) Stack
Diameter (feet) Exit Temperature (Fahrenheit)

SW3 35.09912 98.35193 53 140 14 275

The base elevation of each of the units is 371 meters (1,217 feet) above MSL based upon visual inspection of USGS topographic maps.

4 http://www2.nature.nps.gov/air/ Permits/ect/ectGasFiredCT.cfmAEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 4-1 

## 4. SO 2 

## BART D ETERMINATION

A summary of existing SO 2 emissions as described in Section 3 is included below.

T ABLE 4-1. B ASELINE M AXIMUM 24-H OUR SO 2 E MISSION R ATES

Emission
Unit SO 2 Emission Rate

(lb/hr) SW3 1.97



## 4.1 I DENTIFICATION OF 

## A VAILABLE 

## R ETROFIT 

## SO 2 

## C ONTROL 

## T ECHNOLOGIES

The first step of a BART determination is the identification of all available retrofit SO 2 control technologies. A list of control technologies was obtained by reviewing the U.S. EPA’s Clean Air Technology Center, control equipment vendor information, publicly-available air permits, applications, and BART analyses, and technical literature published by the U.S. EPA and Regional Planning Organizations (RPOs).

T ABLE 4-2. A VAILABLE SO 2 C ONTROL T ECHNOLOGIES

SO 2 Control Technologies

Dry Sorbent Injection Spray Dryer Absorber (SDA) i.e., Semi-Dry Scrubber Wet Scrubber Circulating Dry Scrubber (CDS)

All of the technologies listed in Table 4-2 involve removing the SO 2 in the exhaust gas, which is known as flue gas desulfurization (FGD). AEP propo ses to restrict fuel usage at the Southwestern Station to natural gas only. Commercial-grade natura l gas is intrinsically low in sulfur content, and results in low sulfur emissions. The facility’s existing Title V operating pe rmit (No. 2003-403-TVR) provides an estimate of SO 2 emissions from the combustion of natural gas, as summarized below.

T ABLE 4-3. SO2 E MISSION E STIMATES (N ATURAL G AS )

SO 2 Emission
Unit lb/hr TPY

SW3 1.97 8.65AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 4-2 SO 2 emissions from Southwestern Power Station Unit 3 are sufficiently low from natural gas usage that no add-on control technology could be considered economically feasible. As a result, AEP determines that natural gas usage is BART for Southwestern Unit 3.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 5-1 

## 5. PM BART D ETERMINATION

A summary of existing PM emissions as descr ibed in Section 3 is included below.

T ABLE 5-1. E XISTING M AXIMUM 24-H OUR PM E MISSION R ATES

Emission
Unit PM Emission Rate

(lb/hr) SW3 24.51



## 5.1 I DENTIFICATION OF 

## A VAILABLE 

## R ETROFIT 

## PM C ONTROL 

## T ECHNOLOGIES

The first step of a BART determination is the id entification of all available retrofit PM control technologies. A list of control technologies was obtained by reviewing the U.S. EPA’s Clean Air Technology Center, control equipment vendor information, publicly-available air permits, applications, and BART analyses, and technical literature published by the U.S. EPA and Regional Planning Organizations (RPOs).

T ABLE 5-2. A VAILABLE PM C ONTROL T ECHNOLOGIES

PM Control Technologies
Electrostatic Precipitator (wet or dry) Baghouse (Fabric Filter)

AEP proposes to restrict fuel usage at the Southw estern Station to natural gas only. As with SO 2 , the use of commercial-grade natural inherently results in low particulate emissions. The facility’s existing Title V operating permit (No. 2003-403-TVR) provides an estimate of PM emissions from the combustion of natural gas, as summarized below.

T ABLE 5-3. PM E MISSION E STIMATES

PM Emission
Unit lb/hr TPY

SW3 25.00 109.52

These emission estimates from natural gas usage are sufficiently low that no add-on control technology could be considered ec onomically feasible. As a result, AEP determines that natural gas usage is BART for PM for Southwestern Unit 3.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 6-1 

## 6. NO X 

## BART D ETERMINATION

The existing maximum daily NO X emission rates that were modeled for the BART applicability determination are summarized in Table 6-1.

T ABLE 6-1. E XISTING M AXIMUM 24-H OUR NO X E MISSION R ATE

Unit ID NO X Hourly Emission Rate NO X Emission Rate (lb/hr) (lb/MMBtu) SW3 3,705 1.126



## 6.1 I DENTIFY 

## A LL 

## A VAILABLE 

## R ETROFIT 

## T ECHNOLOGIES

Step 1 of the BART determination is the identification of all available retrofit NO X control technologies. A list of control technologies was obtained by reviewing the U.S. EPA’s Clean Air Technology Center, control equipment vendor information, publicly-available air permits, applications, and BART analyses, and technical litera ture published by the U.S. EPA and the RPOs.

T ABLE 6-2. A VAILABLE NO X C OMBUSTION C ONTROL T ECHNOLOGIES

NO X Control Technologies

Burner Tuning Burners out of Service – BOOS (placing selected burners out of service)

Induced Flue Gas R ecirculation (IFGR)

Low NO X Burners (LNB) with overfire air (OFA)

NO X emissions controls, as listed in Table 6-2, can be categorized as combustion or post-combustion controls. Combustion controls, including flue gas recirculation (FGR), overfire air (OFA), and Low
NO X Burners (LNB), reduce the peak flame te mperature and excess air in the furnace which minimizes NO X formation. Post-combustion controls, su ch as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) were not ex amined in this analysis. As described in Appendix Y to Part 51, U.S. EPA states that the use of current combustion control technology is highly cost-effective in achieving emission reductions under BART. 5

5 Federal Register, Vol 20, No. 128, 7/6/2005, p. 39172AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 6-2 

## 6.2 E LIMINATE 

## T ECHNICALLY 

## I NFEASIBLE 

## O PTIONS

Step 2 of the BART determination is to eliminate technically infeasible NO X control technologies that were identified in Step 1.



### 6.2.1 B URNERS 

### O UT OF 

### S ERVICE

This option involves shutting off selected bur ners, resulting in reduced fuel usage and therefore lower emissions. This option w ould essentially reduce the maximum firing rate of the boiler, and places a load limit on the unit. AEP estimates that NOx emissions can be reduced 20-25%. Implementation of this option will reduce the maximum firing rate of the unit, thereby creating an artificial load limit. Although this does not preclude this option from being physically implemented, the resulting load limits would effectively result in the shutdown of the units. As a r esult, this option is considered technically infeasible.



### 6.2.2 I NDUCED 

### F LUE 

### G AS 

### R ECIRCULATION 

### (IFGR)

FGR uses flue gas as an inert material to redu ce flame temperatures. In a typical flue gas recirculation system, flue gas is collected fro m the heater or stack and returned to the burner via a duct and blower. The addition of flue gas reduces the oxygen content of the “combustion air” (air + flue gas) in the burner. The lower oxygen level in the combustion zone reduces flame temperatures; which in turn reduces thermal NO X formation. When operated without additional controls, the average NO X control efficiency range for FGR is 30 percent to 40 percent. This control opti on would also place load limits on the boiler and also call for plant component upgrades. As with the Burners Out Of Service , IFGR is considered technically infeasible as a stand alone NOx control for Southwestern Power Station Unit 3.



### 6.2.3 L OW 

### NO X 

### B URNERS 

### (LNB) WITH 

### O VERFIRE 

### A IR 

### (OFA)

LNB technology utilizes advanced burner design to reduce NO X formation through the restriction of oxygen, lowering of flame temperature, and/or reduced residence time. LNB is a staged combustion process that is designed to split fuel combustion into two zones. In the primary zone, NO X formation is limited by either one of two methods. Under staged fuel-rich conditions, low oxygen levels limit flame temperatures resulting in less NO X formation. The primary zone is then fo llowed by a secondary zone in which the incomplete combustion products formed in th e primary zone act as reducing agents. Alternatively, under staged fuel-lean cond itions, excess air will reduce flame temperature to reduce NO X formation. In the secondary zone , combustion products formed in the primary zone act to lower the local oxygen concentration, resulting in a decrease in NO X formation.

OFA diverts a portion of the total combustion air from the burners and injects it through separate air ports above the top level of burners. Staging of the combustion air creates an initial fuel-rich combustion zone with a lower peak flame temperature. This reduces the formation of thermal NO X by lowering combustion temperature and limiting the availability of oxygen in the combustion zone where NO X is most likely to be formed.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 6-3 OFA as a single NO X control technique may reduce NO X emissions by 25 to 55 percent. When combined with LNB, reductions of up to 60 percent may result. 6 This technology is considered a technically feasible option.



## 6.3 E VALUATE 

## E FFECTIVENESS OF 

## R EMAINING 

## C ONTROL 

## T ECHNOLOGIES

The third step in the BART analysis is to rank the technically feasible options according to effectiveness.

T ABLE 6-3. C ONTROL E FFECTIVENESS OF T ECHNICALLY F EASIBLE NO X C ONTROL T ECHNOLOGIES

Control Technology Estimated Control Efficiency (%)

LNB w/ OFA ~30-60



## 6.4 E VALUATION OF 

## I MPACTS FOR 

## F EASIBLE 

## NO X 

## C ONTROLS

Step four for the BART analysis procedure is the impact analysis. The BART determination guidelines list four factors to be considered in the impact analysis:

▲ Cost of compliance
▲ Energy impacts
▲ Non-air quality impacts; and
▲ The remaining useful life of the source

Evaluation of a fifth factor, visibility impacts, is addressed separately in Section 6.5.



### 6.4.1 C OSTS OF 

### C OMPLIANCE

Per the BART Guidelines, the costs of complianc e analysis for each cont rol option consists of comparisons of the average cost effectiveness and the incremental cost effectiveness, which are defined in Section IV.D.4 as follows:

Average cost effectiveness means the total an nualized costs of control divided by the annual emissions reduction (the differen ce between baseline annual emissions and the estimate of emissions after controls), using the following formula:

Average cost effectiveness (dollars per t on removed) = Control option annualized cost ÷ (Baseline annual emissions – Annual emissions with Control option)

6 "Assessment of Control Technology Options for BART -Eligible Sources: Steam Elec tric Boilers, Industrial Boilers, Cement Plants and Paper and Pulp Facilities" Northe ast States for Coordinated Ai r Use Management (NESCAUM), March 2005AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 6-4 ...the incremental cost effectiveness calcul ation compares the costs of performance level of a control option to those of the n ext most stringent option, as shown in the following formula (with respect to cost per emissions reduction):

Incremental Cost Effectiveness (dollars per incremental ton removed) = (Total annualized costs of control option) – (Total annualized costs of next control option) ÷ (Control option annual emissions) – (Next control option annual emissions)

Compliance costs associated with implementing the evaluated control systems were developed in-house by AEP, a nd represent both annual operating costs and annualized capital costs associated with retrofit construction. A detailed summary of those costs is included in Appendix B, while estimates of annual polluta nt reductions for the evaluated control technologies are included in Appendix A. The average cost effectiveness of this control options is summarized in Table 6-4. Please not e that since no other options were examined, incremental cost effectiveness is not relevant (and not included).

T ABLE 6-4. NO X C ONTROL C OSTS S UMMARY

Average Cost
Effectiveness Incremental Cost
Effectiveness Emission Unit Control Strategy $/ton $/ton

SW3 Low NOx Burner
w/ Overfire Air 947 --



### 6.4.2 E NERGY AND 

### N ON



### - AIR 

### I MPACTS

Energy and non-air impacts from an LNB retrof it are minimal. Derating of output from the unit is not expected, or considered insignificant.



### 6.4.3 R EMAINING 

### U SEFUL 

### L IFE

The remaining useful life of the Southwestern units do not impact the annualized capital costs of potential controls because the useful lives of the units are anticipated to be at least as long as the capital cost recovery period, which is 20 years.



## 6.5 E VALUATE 

## V ISIBILITY 

## I MPACTS

In order to determine the change in visibilit y impact from the various NOx control options considered, calculated emissions were modeled in CALPUFF. As discussed in the modeling protocol included in Appendix A, visibility impacts were eval uated each of the four nearby Class I areas.

Pre-BART baseline emissions for each unit are mode led and summarized below. Subsequent control scenarios incorporated calculated NOx emissions fro m post-control scenarios, and incorporated allAEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 6-5 other pollutants at baseline emissions. Per BART determination procedures, visibility impacts are presented below on a unit-by-unit basis.

T ABLE 6-5. S OUTHWESTERN U NIT 3 V ISIBILITY I MPACTS (98 TH P ERCENTILE I MPACT )

Class I Area Pre-BART LNB w/ OFA Visibility Improvement ∆ dv ∆ dv % Caney Creek 0.23 0.09 50% Hercules-Glades 0.14 0.06 48% Upper Buffalo 0.17 0.07 61% Wichita Mountains 3.73 1.66 55%



## 6.6 P ROPOSED 

## B ART FOR 

## NO X

AEP has determined that the NO X BART for Southwestern Unit 3 is LNB w/ OFA. As seen from the modeled visibility improvement and calculated averag e cost effectiveness, this control option cannot be considered either technically or economically infeasible. Based upon the control effectiveness estimates of LNB w/ OFA, AEP proposes a BART NOx emission rate of 0.45 lb/MMBtu.AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 

## A PPENDIX 

## A

– E MISSION 

## E STIMATESUnit 3PM (filterable) PM (condensible)lb/mmBtu lb/hr lb/mmBtu lb/hr lb/mmBtu lb/hr lb/mmBtu lb/hr lb/hr lb/hrCase 1 Baseline Case -- 1.126 3,705 0.0006 1.97 -- 0.30 0.007 24.51 6.13 18.39Case 2 LNB w/ OFA 60% 0.450 1,4821H2SO4emissions based upon the following assumptions:SO2Conversion to SO3= 10%SO3Conversion to H2SO4= 100%MW H2SO4= 98 lb/lbmolMW SO2= 64 lb/lbmolSample Calculation:1.974 lb SO2 lbmol 0.1 lbmol SO3 1 lbmol H2SO4 98 lb H2SO4 = 0.30 lb SO4hr 64 lb SO2 lbmol SO2 lbmol SO3 lbmol hr2Baseline emission data for PM is not available. A conservative estimate was made using U.S. EPA emission factors, AP-42 (7/98) Table 1.4-2Please note that for natural gas usage, PM10 emissions can be considered equivalent to total PM.PM10= 7.6 lb/MMSCF0.0075 lb/MMBtuAverage natural gas heating value = 1020 BTU/scf3Condensible/filterable PM speciation were based on the following profiles:For Natural Gas fired combustion turbines. http://www2.nature.nps.gov/air/Permits/ect/ectGasFiredCT.cfmFilterable 25.00%Condensible 75.00%4NOx control estimate for Case Low NOx burners developed in-house by AEP, email dated 8/13/2008, [Controlled emission rates for NE2-SW3_Comanche.xls]PM Speciation3Southwestern Power Station24-hr Average Emission EstimatesSO4(from SO2)PercentReduction4PM (total)NOxSO2American Electric PowerSouthwestern Power StationModel Inputs (lbhr)Printed on 8/25/2008Page 1 of 2Trinity Consultants083701.0057Unit 3NOx% Reductionlb/mmBtu2tpy1Case 1 Baseline Case -- 0.570 8,214Case 2 LNB w/ OFA 21% 0.450 6,4851Baseline emission factor based upon annual average. Provided by AEP via email, 8/20/20082Emission factors as developed in modeling summary; based upon emissionreduction estimates provided by AEPSouthwestern Power StationAnnual Emission EstimatesUnit IDUnit 3Annual Ave Firing Rate(MMBtu/hr)3,290American Electric PowerSouthwestern Power StationModel Inputs (Annual)Printed on 8/25/2008Page 2 of 2Trinity Consultants083701.0057Southwestern StationCALPUFF Visibility ResultsPeak Impact 98th PercentilePollutant Class I AreaControlTechnology (∆dv)% Reductionfrom previous% Reductionfrom Baseline (∆dv)% Reductionfrom previous% Reductionfrom BaselineNOx Caney Creek Baseline 1.17 -- -- 0.23 -- --LNB w/ OFA 0.48 59% 59% 0.09 61% 61%Herc-Glades Baseline 0.52 -- -- 0.14 -- --LNB w/ OFA 0.20 61% 61% 0.06 60% 60%Upper Buffalo Baseline 0.88 -- -- 0.17 -- --LNB w/ OFA 0.34 61% 61% 0.07 61% 61%Wichita Mts Baseline 8.872 -- -- 3.73 -- --LNB w/ OFA 4.52 49% 49% 1.66 55% 55%PM10Caney Creek Baseline 0.001 -- -- -- -- --Herc-Glades Baseline 0.001 -- -- -- -- --Upper Buffalo Baseline 0.001 -- -- -- -- --Wichita Mts Baseline 0.064 -- -- 0.028 -- --SO2Caney Creek Baseline 0.001 -- -- -- -- --Herc-Glades Baseline -- -- -- -- -- --Upper Buffalo Baseline 0.001 -- -- -- -- --Wichita Mts Baseline 0.012 -- -- 0.006 -- --AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 

## A PPENDIX 

## B

- E CONOMIC 

## A NALYSESPrinted: 8/27/2008



### Economic Analysis for Low NOx Burners w/ Overfire Air

Capital Cost Summary Capital Cost

TOTAL CAPITAL INVESTMENT a TCI = $3,000,000

Annual Cost Summary Annual Cost

DIRECT OPERATING COSTS Low-NOx burners are not expected to incur any additional significant direct operating costs

TOTAL DIRECT COSTS (DC) DC = $0

INDIRECT OPERATING COSTS Administrative Charges (2% of TCI) b $60,000

Insurance (1% of TCI) b $30,000

Property Taxes (1% of TCI) b $30,000

Capital Recovery (CRF x TCI) 20 years @ 8.00% interest CRF = 0.1019 $305,557

TOTAL INDIRECT COSTS (IC) IC = $425,557

TOTAL ANNUALIZED COST (TAC = DC + IC) TAC= $425,557

Cost Effectiveness Summary

Annual Control Cost: $425,557

NOx to be Removed (tpy): c 450

CONTROL COST EFFECTIVENESS ($/ton): $947

a Cost of purchasing and installing Low-NOx burners provided by AEP via email (8/21/2008). b Direct and indirect cost factors taken from OAQPS Control Cost Manual, Sixth Edition, January 2002. c LNB w/OFA NOx Removal Rate = 21%

Annual Capacity Factor = 0.26 Provided by AEP via email, 8/20/2008 Baseline (pre-BART) emission factor = 0.57 lb/MMBtu, based upon an annual average Annual Average Firing Rate = 3,290 MMBtu/hr, as listed in Permit No. 96-288-TV.

Sample Calculation:

0.57 lb 3290 MMBtu 8760 hrs ton 0.26 capacity factor 0.21 NOx Removal Rate = 450 tons NOx MMBtu hr yr 2000 lb year

American Electric Power Southwestern Power Station Cost Analysis (LNB wOFA) Trinity Consultants
083701.0057AEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 

## A PPENDIX 

## C

– CALPUFF M ODELING 

## P ROTOCOLAEP Trinity Consultants BART Determination Southwestern Power Station Unit 3 083701.0057 

## A PPENDIX 

## D

– M ODELING 

## I NPUT 

## /O UTPUT 

## F ILES



### Control Scenario Description Model Run Number
NOx SO 2

Case 1 Baseline Case Run 1 Run 1

Case 2 LNB w/ OFA Run 2 --