# Minnkota Power**~Pc;j** 

# coo PER 

### A T I V E, 

### INC.
1822 Mill Road· P.O. Box 13200 • Grand Forks, NO 58208-3200 • Phone (701) 795-4000 

### February 20, 2009

Mr. Terry O'Clair Director, Division ofAir Quality North Dakota Department of Health 918 

### E. Divide Avenue, 2nd 

### FI Bismarck, ND 58501-1947 Your Touchstone Energy'" Partner


# -

RE: Supplemental information for the North Dakota Department of Health's Best Available Control Technology Determination for Control of Nitrogen Oxides for M.R. Young Station Units 1 and 2, dated June 2008
Dear Mr. O'Clair: In response to the Department's request for additional information concerning the use of Low Dust SCRs and Tail End SCRs at Milton R. Young Station, please find enclosed the report titled "Supplemental Information for Consideration Regarding NOx BACT for M.R. Young Units 1 and 2: Technical Feasibility Issues for TESCR or LDSCR Retrofit, February 20,2009". Minnkota continues to believe the NDDH's preliminary BACT determination dated June 2008 to be correct and appropriate. Should you have any questions concerning this submittal, please contact me at 701- 795-4221. Sincerely, POWER COOPERATIVE, INC.

# ~~ John T. Graves, P.E. Environmental Manager
C: David Sogard

## Supplemental Information for Consideration by NOOH Regarding NOx BACT for M.R. Young Units 1 and 2: Technical Feasibility Issues for TESCR or LOSCR Retrofit

prepared for 

# Minnkota Power Cooperative, Inc. And 

# Square Butte Electric Cooperative
February 20, 2009 prepared by Burns 

## &McDonnell Engineering Company, Inc. Kansas City, Missouri and Steve Benson, PhD Department of Chemical Engineering, University of North Dakota Project No. 31777

### Supplemental Information for Consideration Regarding NOx BACT for M.R. Young Units 1 and 2: Technical Feasibility Issues for TESCR or LOSCR Retrofit February 20, 2009
1. Purpose Bums & McDonnell (B&McD), along with Steve Benson ofthe Department ofChemical Engineering atthe University ofNorth Dakota1
, have reviewed the technical literature provided by the North Dakota Department ofHealth (NDDH) regarding submicron particle collection and penetration for dry electrostatic precipitators (ESPs), and have prepared this document in response. The information and commentary provided herein are being submitted to NDDH for consideration relative to selective catalytic reduction (SCR) technology infeasibility for control ofnitrogen oxides emitted from Milton R. Young Station Units I and 2. Issues related to the technical infeasibility ofSCRs located in both the low-dust configuration (LDSCR) and the tailend configuration (TESCR) are addressed. [Referto the basic schematic diagrams below].

Low Dust

Tail End

1 formerly employedby Energy & Environmental Research Center (EERC) ofthe University ofNorth Dakota. Supplemental Information For Consideration by NDDH 1 February 20, 2009We continue to believe that the administrative record fully supports a fmding by the NDDH that separated over-fIre air (SOFA) in conjunction with selective non-catalytic reduction (SNCR) technology is BestAvailable Control Technology (BACT) for NOx control for electric generating units thatutilize cyclone burners fIring North Dakota lignite.



### 2. Scope The following sections address specifIc topics pertaining to the NDDH's PreliminaryNOx BACT Detennination for Nitrogen Oxides for Milton R. Young StationUnits 1 and 2, datedJune 2008 (NDDH, 2008)

• SignifIcance ofsubmicron aerosol particle removal by ESPs and wet FGD

• Evaluation ofsubmicron particle penetration dataprovidedby NDDH

• Sodium-rich aerosol fonnation and penetration through ESP and FGD at M. R. Young Station fIring North Dakota lignite o Fonn ofsodium in Center lignite o Vaporization ofsodium in the high temperature cyclones' combustionprocess o Condensation ofsodium and concentrating in the submicron size fraction o Electrostatic precipitator collection effIciency o Aerosol capture efficiency in scrubbers o Powerspan testing atMRYS o MRYS sulfate aerosol sampling

• Detennination ofSodium Loading Adversely Affecting SCR Catalyst Performance

• Alkali Aerosol Loading and CatalystDeactivation

• Experience ofESPIFGD equippedutility plants co-fIring biomass and coal with TESCR

• Relevance ofrecent TESCR investigations atWe Energies' South Oak Creek Station

• Relevance ofongoing LDSCR installation at We Energies' South Oak Creek Station

• Relevance ofexisting LDSCRinstallation at PSEG Mercer Station

• Additional technical feasibility issues for TESCR at MRYS

• Summary and Conclusions
Supplemental Information For Consideration by NDDH 2 February 20, 2009

### 3. Significance of Submicron Aerosol Particle Removal by ESPs and WetFGD The removal percentage ofsubmicron or aerosol particles by an ESP or any otherdevice is not important. The key is not what is removed, but ratherthe quantity that is notremoved. The amount (mass and number) ofsubmicron and ultrafme particles, as well as the speciation ofthe particles which pass through the ESP, are extremely important. These particles have the following detrimental characteristics:

• Condensed vaporphase species concentrate in the less than I J.1m size fraction and are in the range ofparticle sizes where ESPs and wet flue gas desulfurization systems (FGDs) are ineffective in capturing them

• Small particles that can penetrate deep into catalystpores

• Highly reactive, because ofchemistry [rich in sodium (Na), potassium (K), sulfur (S), phosphorus (P)], which results in poisoning sites

• Highly reactive, because ofphysical characteristics

- high surface area can react with gas phase species, which results in blinding ofpores

• Highly concentratedbecause ofthe removal oflargerparticles by cyclone and air pollution control devices

• Highly concentrated aerosols (not diluted by large particles) thatupon accumulation can efficiently bond together causing catalystblinding and are available to poison active sites 

## 4. Evaluation of Submicron Particle Penetration Data provided by NDDH The NDDH provided publications on the efficiency ofESPs and scrubbers to remove particulate as well as penetration ofaerosol particles through the devices. The following are some ofthe key conclusions that canbe drawn from the review ofthe information described in these papers. The information provided indicates poor collection efficiency ofsubmicron particles:

• The particulate collection efficiencies for the coarse fraction particles orparticles larger than I to 5 J.1m in ESPs are generally very good (99.9%). Supplemental Information For Consideration by NDDH 3 February 20, 2009• Forparticles less than 1 J.1m, the collection efficiency drops offsignificantly.

• Particles in the finer size fractions are largely composed ofcondensed vaporphase species such as sodium, potassium, chlorine (CI), and sulfur.

• Highercombustiontemperatures result in more vaporization and increased levels of submicronparticles.

• Emission rates downstream ofESPs described in the reports range from 4,500 to 50,000 J.1g1Nm3• The particulate are dominatedby aerosols rich in sodium andpotassium. NOTE: The level of22,500 J.1g1Nm3 ofsodium and potassiumrich fly ash derived from biomass resulted in catalyst deactivation of40 

### % in 1500 hours (Kling and others, 2007).
Specific observations and/or comments on each ofthe documents providedby NDDH are presentedbelow: 

### Mohr, M., 

### Ylatalo, S., Klippel, N., 

### Kauppinen, E.L, Riccious, 0., andBurtscher, H., Submicron FlyAsh Penetration through Electrostatic Precipitators at Two CoalPowerPlants, AerosolScience and Technology 24:191-204(1996) Measurementofthe size distribution offme particulate (diameter less than 0.5J.1m) atthe inlet and outlet ofthe ESP for two full scale pulverizedcoal fired powerplants was conducted. The coals fired consisted ofhigh volatile bituminous coals from South Africa and Columbia. The characteristics ofthese coals are summarized in Table 1. The analysis indicates very low levels ofsodium as well as other alkali and alkaline earth elements [I(, calcium (Ca), and magnesium (Mg)]. The potential for formation ofalkali rich aerosols from these coals is extremely small because ofthe form ofthe alkali and abundance.

Supplemental Information For Consideration by NDDH 4 February 20, 2009Table 1. Coal analysis (Mohr and others, 1996) COAL**~try** South Colombia South Africa .Africa Coal field Klein Eldorado Klein KDpie

. Kopie Location ofbuming PlantA Plant A PlantB Date 9.5.94 17.5.94 11.8.93 Proximate analysis Total moisture % 9.9 13.5 7.4 dryweightbases Ash 9fJ 17.1 10.2 16.2 Volatile matter % 20.7 35.5 23 fixed carbon % 62.2 54.2 60.9 Omss calorificvalue MJ/kg 27.42 29.99 27.34 Ultimate analysis Caibon % 70.3 73.4 68.4 Hydrogen % 3.4 4.6 1.S N'atrogen % 

### L7 1.5 3.5 Osysen % 7 9.4 9.9 Sulfur % 0.43 0.81 

## o.s Coal ash P20, % 1.2 0.3 1.2 Si02. % 45.3 55.7 47.7**P~03** % 3.5 7.3 3.1 Al20 3 % 31.4 21.0 33.2 

### nOt % 1.6 0.9 1.1 

## Cao % 7.3 4.1 6.2 

# Mao % 1.7 2.1 1.4 

### SO, % 5.4 3.1 4.8 K20 9& 1.0 2.1 0.7 Ha20 % 0.3 0.6 0.2 Li20 % 0.0 0.0 0.0 By comparison, Table 2 summarizes the average lignite properties relevantto MRYS. It can be seen that the characteristics ofthe MRYS coals are very different and will produce significantly different size distributions ofash than the coals fired in the plants reportedby Mohr and others, 1996. Table 2. Average Center lignite and ash composition (moisture, ash, sulfur, andheating value expressed on an as-receivedbasis; and ash composition expressed as weight percent equivalent oxide ofthe ash).

Average 37.13 9.64 0.98 6578 11.68 0.52 13.15 8.90 3.99 0.12 1.33 36.04 4.40 18.39

This testing has little relevance to the collection ofash in the MRY boilers for two primary reasons. The first is the firing type. The boilers are pulverizedcoal (PC)-fired andpartitioning to the finer ash fraction will be much lowerthan that observed for cyclone-firedboilers. The Supplemental Information For Consideration by NDDH 5 February 20, 2009second reason is coal type. The coals tested are bituminous coals. The ash fonning components in the bituminous coals are mineral grains with no organically associated elements (Na, K, Ca and Mg). The fraction ofthe elements in an easily vaporizable fonn is much lower in the bituminous coals producing lowerlevels ofash in the smaller sized fractions.



### Nobrega, 

### S.

### W:, Falaguasta, M.

## c.R., andCoury, LIt, A Study of a Wire-Plate Electrostatic Precipitator Operating in theRemovalof Poly dispersedParticles, Brazilian Journal of ChemicalEngineering, Vol21, 

### No. 02,pp 273-284, 

### April-June2004. This paperis a laboratory and computermodeling effortthat examinedthe perfonnance ofESPs. The precipitators tested were small scale laboratory systems. A phosphatic concentrate was used as particulate. Computational models for predicting fme particle removal in ESPs were improved. However, the relationship to particulate collection from coal ftred power systems is small.



### PowerStation Emissions Handbook, CooperativeResearch Centrefor Coal in Sustainable Development, http://www.ddsd.biztpSE Handbook/5/6/5/index.cfm accessed11/24/2008. This document states: "Wet scrubbers can remove more than 90% for particles with diameters above 10 microns. Efficiencies for smallerparticles will be signiftcantly lower." "The size distribution ofthe dust influences the overall ESP collection efficiency. Particles in the range of0.1 to 1.0 Jlm are the most difficult for an ESP to collect. " "ESP collection efficiency is particularly affectedby several factors including coal ash resistivity, gas temperature, chemical composition andparticle size distribution (Wu 2001)." There is no discussion on fly ash types that are collected. Only general data is provided. Application to high sodium lignite derived coal ashes is not apparent from the website.

Supplemental Information For Consideration by NDDH 6 February 20, 2009

### ICACInstitute of CleanAir Companies, Particulate controls, http://www.icac.com/i4a/pages/index.cfm?pageid=3398 This website states: "Precipitatorcollection efficiencies will be somewhat lower for particles with diameters near 0.3 microns. The reason for a minimum in collection efficiency for 0.3 micron particles is thatboth particle charge and the resistance ofthe gas to particle motion both increase with particle size. Near 0.3 micron, the particle charge is low enough and the resistance to particle motion is high enough thatparticles are collected relatively poorly."
These conclusions indicate that aerosols can penetrate through ESPs.



### Lind, 

### T., Hokkinen, J., 

### andJokiniemi, J.K., 

### Saarikoski,S., andHillamo, 

### R., Electrostatic Precipitator Collection efficiencyand Trace ElementEmissionsfrom Co-Combustion of Biomass andRecoveredFuelin Fluidized-bed Combustion, EnvironmentalScience and Technology, 2003, 37, 2842-2846. This paperdescribes the removal efficiency ofash particles produced in a 66 megawatt (MW) biomass-fired bubbling bed fluidized bed combustion (FBC) system. Fluidizedbed combustion systems operate at lowertemperatures (1400 to 1600 OF) than conventional pulverized coal-fIred or cyclone-firedutility boilers. The bed material in the FBC was sand. The fuel was mixture of peat and wood wastes. Fluidizedbed systems typically have significant levels ofentrained ash particles that provide sites for condensation ofvaporized species. The particles thatpenetrated the ESP were found to contain mostly alkali salts (Na, K, Cl, and S04). The quantity of materials penetrating the ESP was 4.5 to 9 mg/Nm3 (4,500 to 9,000 flg/Nm3). The 2003 paperby Lindreferences her earlierwork on ash formation mechanisms (Lind, and others, 2000). This paperdescribes in detail the mechanisms offormation ofthe aerosol particles andthatthey are enriched in alkali salts (Na, K).

Supplemental Information For Consideration by NDDH 7 February 20, 2009

### Ohlstrom, M., 

### Jokiniemi, J., 

### Hokkinen, J., 

### Makkonen, P., 

### and Tissari, J., 

### Combating ParticulateEmissions in Energy Generation andIndustry, Tekes, VTTTechnicalResearch Centre of Finland, 2006. This paperalso describes the concentrating ofvaporized elements such as sodium andpotassium in the fme (less than 1**~m)** size fraction. The authors also state "highercombustion temperatures typically increase the amount offmeparticle released." In addition, they discuss the fact that "Electrostatic precipitators are attheir least efficientwhen handling particle sizes between 0.1 

### JlIll to 1**~m."** They indicated in Table 8 onpg 29 ofthe report thatthe emissionrates ranged from 15 to 50 mg/Nm3(15,000 to 50,000**~g/Nm3)** from the ESP. This paper also shows that scrubbers are extremely ineffective in removing aerosols. 

### 5. Sodium-Rich Aerosol Formation and Penetration Through ESP and FGD at M. R. Young Station Firing North Dakota Lignite As described above, the fly ash penetration derived from the preceding described literature is not fully relevant to MRYS due to the significantdifferences in the sodium content ofthe fuels fired and the differences in the fuel firing mechanism employed in the plants tested. The following discussion will briefly review the following topics:

• Form ofsodium in Center lignite

• Vaporization ofsodium in the high temperature cyclones' combustionprocess

• Condensation ofsodium and concentrating in the submicron size fraction

• Electrostatic precipitator collection efficiency for fme particulate andrelationship to ash produced from Center lignite

• Aerosol capture efficiency in scrubbers

• Powerspan testing at MRYS

• MRYS sulfate aerosol sampling. 

### Form ofSodium in 

### CenterLignite Sodiumis associatedwith the organic matrix in Centerlignite. That means the sodium is atomically dispersed in the organic matrix. The sodium is associated with a carboxylic acid groups (ion exchange sites). The carboxylic acid groups act as bonding sites for various

Supplemental Information For Consideration by NDDH 8 February 20, 2009elements such as Ba, Ca, Mg, and Sr along with minor amounts ofK. Figure I illustrates the bonding ofsodium to the organic fraction ofthe coal and the association ofother coal impurities
.

Included Minerals
Excluded Minerals

OrganicS 

# ..•

/_.

. 

# •... HzOwithWater SolubleMinerals
•Present in minoramounts •NazSO. and othersoluble salts are the most common types.
MineralsGraIns •Included in coal particles
•Excluded in coal particles o Na'O·11 

### :) o 

### J.l )=0

0·0 Ca++


### o II )_

.......... -

0·0 Mg++ OrganicallyAssociatedElements
•Bound assalts ofcarboxylic acids
•Organicallyassociated sulfur
•Coordination complexes Aj3+and Fe3+ Figure 1. Form ofsodium in coal (Benson and Laumb, 2008).


### Vaporization ofSodium in the High Temperature Cyclones' Combustion Process Sodium is a volatile element and is in the easily volatilized organic form in Center lignite and will be transformed into a gas upon combustion. The vaporization ofsodium during the combustion oflignite is a very well known fact that has been examinedby numerous investigators, including work conductedby MIT, CalTech, SandiaNational Laboratory, National Energy Technology Laboratory, University ofUtah, and others (see review by Lighty and others, 2000). For example, research conductedby Senior and others (2000) reported thatrelative to
Supplemental Information For Consideration by NDDH 9 February 20, 2009other coals, North Dakota lignite producedmore vaporized ash. The actual amountvaporized for ND lignite is double the level vaporized as compared to subbituminous and lignite coals from Montana as illustrated in Figure 2.
7 

# I D Calculated 

# II Actual 

# I I i



# .. aI



### ..... 

# I i

# r 1 0 Figure 2. Ash vaporized during combustion oflignite and subbituminous coals (Senior and others, 2000).

Work conducted at the MR Y plantrelated to the vaporization ofsodiumfrom a cyclone fIred system is illustrated in Figure 3. The results show overtwo thirds ofthe sodium is not retained in the slag and is vaporized in the high sodium lower ash coals 1-3. In the low sodium high ash coals 4-5, very small amounts ofthe sodiumwas vaporized.

Supplemental Information For Consideration by NDDH 10 February 20, 200914JJO 

# r-----------------------------...,

0.00 IIffI MAY MAY CDaI ColI Slag

444 

### C5O.rheJ Figure 3. Comparison ofsodium levels in Centerlignite coal and slag samples.
Condensation ofSodium and Concentrating in the Submicron 

### Size Fraction EPA has evaluatedthe literature onparticle fonnation during combustion and from other sources and incorporatedit into an educational module that was found on the following website: (http://www.epa.gov/apti/bces/module3/fonnationffonnate.htm). The classification ofparticle types shownby EPA is illustratedin Figure 4. The EPA classification is consistent with the review conductedby Lighty and others (2000). Vaporized species can condense heterogeneously on surfaces ofother entrained coarse ash particles and can condense homogeneously to fonn the fme and ultrafme particles. The distribution ofparticles depicted in Figure 4 is shown on a "frequency percentparticles by mass" basis. The number ofparticles versus size is also important. A comparison ofthe number ofparticles andparticle size is summarized in Table 3. The number ofaerosol particles is significant. These particles have high surface areas and are very reactive.

Supplemental Information For Consideration by NDDH 11 February 20, 20090.1 1.0 10 Particle diameter(Dp), IJm 0.002 Ultrafine

0.01 Fine 

### cOarse Supercoarse

100 1000 Figure 4. Particle size categories used to classify particles. (http://www.epa.gov/apti/bces/module3/category/category.htm)

Figure 5 provides a comparison ofthe mass distribution andparticle numberdistribution. As the particle size decreases the number ofparticles in the size fraction increases. In addition, as illustrated 

### in Table 3, the surface area increases significantly with decreasing particle resulting in the opportunity for reactive gases such as sulfuroxides to react, forming stickyphases thatbond particles together.

Table 3. Particle size, number ofparticles, and surface areal (http://www.epa.gov/apti/bces/module3/category/category.htm) 

## T_ 

# • 1 

# " • d "PIIiIl:1W

# 1'1III_--



# .... 

# ....'-

# 1.'.--_ (11II) 

# .-aJ 

# ...
..... .- IJ 

# -

.- 'I 

# - - 1 ... 11 2.- 

# - .. 1 

# .. I 

### &, 

# •

Supplemental Information For Consideration by NDDH 12 February 20, 200910

# :============~~:1~=i.ITSP .. ..'PM • 

# .. ..'PM' 10 I



### ....

:::=::;:;;;;;;;;;: .. !11JIrIdM PM : 

### 2.S: :**~..** .'NInopIrIcIeI : ;:: 100 

## _---.;.----.;------i---i--....;..-., , 1 I**~MnIeal** AlJIIdCombuIlIan

# PM SoaI

....

, 

## , , 

### , PIinaryComIIuI1IoI'I
..... SoaI Fume from 1tIIttVlIflCIIlDl!On



# .....

_---------------... I04ITSP**_-------------:--_~'PM** I 

# :::======::;;;;;;;Pi.--:"jPMU

# "! 10 :

### ;'.~::;~~~~~.J-----~:--~:**-~:~-..,** 10.000 ,Soat,
...... Md 

### :Acld NucleIMod!' I I Col1lllUIlIon em-t**~Mo*** 

### , 

### , I I

Figure 5. Comparison ofMass Distribution and Particle NumberDistribution for Combustion Derived Particles and Aerosols (Lighty and others, 2000).

Particle size distributions for fly ash collected upstream and downstream ofan ESP are illustrated in Figure 6. This workwas conductedby Markowski and others (1980) specifically aimed at characterizing the submicron aerosol mode offly ash formation. Figure 6B shows the penetration offme particulate through the ESP.

Supplemental Information For Consideration by NDDH 13 February 20, 20092.Il Q.lO 

## .I, 1 - IIolPACTOR 2.4 30 ---IMPACroRUPPfRBOUND l , I**-~** i \ / 0." 2.0 ; 

### , , 

# '" 

# f\ "'"' 

### 1/ 0 0 0 r 

## - 1.6 a" 

### ,

## .. 20

# ~! 12**.~** -IMPl\C1OR

### ~! 15 I \

---- IMI'I\C'roRUPP"JlIIOUIID I \ -EM I \ 0.8 0 EMEJlRlIRESTIIMTE 10 

### f \ ! I 

### i \ OA 

# j i /


### . 

### , 

### ,,- lbii, 0.1 1 10 0 0• 01 0.1 10 GEOMflRICAEROSOI.I*MfTER (jIIIl) A. GEOMElRICAaIOSOl.DIAMETERIlJml B. Figure 6. Typical differential mass distributions ofparticulate collectedupstream (A) and downstream ofan ESP 

### (b) (Markowski and others, 1980).

Fly ash producedupon the combustion ofhigh sodium lignites in a pulverized coal (PC) fired system shows significant enrichment ofsodium in the smaller size fractions as shown in Figure 7. This figure illustrates the increase in the sodium content in the fmer size fractions ofash as a result offiring high sodium lignite. The sodium and sulfurcontent ofthe less that 

### 3 micrometer size fraction ofthe sampling train approached 20% Na20, and 25% S03. The form ofthe sodium is likely sodium oxide and sulfate.

Supplemental Information For Consideration by NDDH 14 February 20, 2009

# /'

11Pa MgO

_______.J. ••• 

### ten



# ....**--------·I---~p.I_n=­** O
.....**----f--~:.:-=--=-=i-=--=---·---------or_-ZW'5** >10 10-3 <3



### MuItkydonesize 

### pm Figure 7. Composition distribution ofash particles during combustion ofNorth Dakota Lignite (Benson and others, 1984).



### Electrostatic Precipitator Collection Efficiency The classical curve for ESP particle collection efficiency is shown in Figure 8. This curve is typical ofwell behaved ash materials that do notpresent significantproblems in collection. The collection efficiency is very good forparticles greaterthan 5 to 10Jlm and the collection efficiency decreases with decreasing particle size, with a minimum collection efficiencybetween

Supplemental Information For Consideration by NDDH 15 February 20, 20090.2 to 211m in diameter. The collection efficiencies vary significantly because ofparticle size and composition.
Low collection efficiency for difficultto collectparticles is between 0.1 to 1 11min particle diameter. Figure 9 provides an illustration ofthe range ofcollection efficiencies. Based on EPA education modules (http://www.epa.gov/apti/bces/module3/collect/collect.htm). no airpollution control device shows high collection efficiency in this range (0.1 to 1.0 11m) due to inherent limitations ofthe collection devices and particle characteristics. The following mechanisms of particle capture are impactedby the size ofthe particles. The impact ofthese mechanisms are described

-Inertial impaction and interception

-Brownian diffusion -Gravitational settling -Electrostatic attraction

-Thermophoresis

-Diffusiophoresis The EPA has indicated thatbased on a number ofstudies ofactual "sources stationary sources generating high concentrations ofparticles in the 0.1 to 0.5 micrometer range may be an especially challenging control problem. '" The gap is most noticeable in wet scrubbers and electrostatic precipitators." A generalized plot showing the range ofcollection efficiencies is shown in Figure 9. Overlaid on the diagram is the mass size distribution ofparticles collected downstream ofthe ESP wet FGD atthe MRYplant (Markowski and others, 1983). This shows that ash produced in the MRY planthave a particle size thatpass through the scrubberand that these particles are rich in sodium as previously shown in Figure 7.

Supplemental Information For Consideration by NDDH 16 February 20, 2009D.2 0.3 Q.5Q,7 1 23457 

### PartkIecIfameIer,JU'" 99.9**.----,....--,----r---r~T"T""TT"-_._-,..._** __.......**...,.~OJJD1**



### .. cum .,,9J:1 ?}9U

# I~ 

# I: • 95 IJ 10**L..L:~~~uL___..JL_L_l_LJLU..J3**

0.1 Figure 8. Typical ESP Collection efficiency curve for removal of particulate from gas streams (http://www.epa.gov/apti/bces/module3/collect/collect.htm).



### .,. 75 1.0 

# i f**.~** .\.**.~** 

# g 

# Iso • 

### \**.~** 

### c



## ... 

# .' 

# j \./ 0.1 

# I B 25 100**r----,---:::~=:p=:=--..,**



### 100.0 1.0 1QD 

## PartIclediameter,lAIn 01....----"'-----"'-------'

0.1 Figure 9. Particulate control efficiency for difficultto control particulate combinedwith the mass distribution ofparticulate collected downstream of the scrubberatMRYS (Markowski and others, 1983 and (http://www.epa.gov/apti/bces/module3/collect/collect.htm). Supplemental Information For Consideration by NDDH 17 February 20, 2009

### Aerosol Capture Efficiency in 

### Scrubbers As indicatedby EPA (Woodward, 1998), scrubbers do not effectively remove particulate less than 1**~m** in diameter. There is significant evidence that sodium-rich aerosols penetrate ESPs as well as scrubbers at full-scale powerplants when firing high-alkali-containing fuels. An example is a biomass fired system using a towertype scrubberwhere the removal efficiency of the smaller size fraction ofash is low, as shown in Figure 10 (Ohlstrom and others, 2006).

I

-- Wood, grate boiler, scrubber inlet I



# - I

- - - - Wood, grate boiler, scrubberoutlet I I



## ... • 

# ,- I 

# .- I



## ...... 

# . I 

# ,- I 

# ,- 

# I 

# \ I I 

# - I 

# - 

# I 

# r.\. I



# - ..**.~** 

### !



# - I , 

# \\ cut-alf 

## , I F 

## , I. I D50=-3um 

# - • 

# I , 

# \\ i , 

## ,**~A** 

## , '. 

# .- / M'," 

# - - ; 

# ............ 

# '--

•• I**-~** 

# ....

--**·-L.~** 

# ... 0 

# ..- I I I 1



### 0.1 1 Dp[Jlml 

### 10 100
Figure 10. Removal offme aerosols using a scrubber on a wood fired combustor (Ohlstrom and others, 2006). Minnesota Power's Boswell Energy Station found that when it fired high-sodium, lower-ash northern PowderRiver Basin subbituminous coal (7% Na2

### 0 in the ash), it experienced increases in opacity. Hurley and Katrinak (1992) conducted a field-testing project on UnitNo.4, a pulverized coal-fIred boiler equipped with a venturi wet scrubber, to betterunderstand the reasons for the opacity problems. During the field testing, sampling ofthe coals, flue gases, and scrubbermaterials was conducted. The particulate in flue gases downstream ofthe scrubber was aerodynamically classifiedusing multicyclone followed by an impactor and aNucleopore filter. Supplemental Information For Consideration by NDDH 18 February 20, 2009The sized fractions were weighed and analyzed to detennine the abundance and composition of the submicron-sized fractions. The mass loadings in the various size bins are plotted in Figure 11, showing thatthe scrubber is quite effective in removing the largerparticles. However, the scrubber is not very effective in removing the aerosols less than 1 micrometer in diameter for both the blended coal and the high sodium coal (Coal A). 

### 1 

# 1 0.1 

# f j 0.01



### 0.001 

## Blend -inlet Blend - 

### outlet Coal A

### -Inlet Coal A- outlet 

# e D50

### ==

# a.omicrons**~D50** 

### ==25

### microns 

# .050- 0.7

### microns 

# 1IBD50<0.7

### mla'ons 

### OYeraH 

## masssizedIstrIbutfonsfor

### entrained

## ash SImples. Figure 11. Mass loadings and size for particulate collectedupstream and downstream ofthe wet venturi scrubber at Clay Boswellplant (Hurley and Katrinak, 1992)

The results ofthe study indicatedthat the particulate collected downstream ofthe scrubber was coal-related and causedby the high sodium content ofthe coals. Vapor-phase sodium condenses in the boiler's convective pass to fonn fme sodium-rich aerosols or otherNa species that later react with ash particles. Pure Na2S04 particles are too small to be removed by such scrubbing. Figure 12 shows the spikes ofthe ash material collected on Stage 10 ofthe impactor. This impactor accumulation represents particles ofless than 0.7 to 2.5 micrometer size fraction ofthe Supplemental Information For Consideration by NDDH 19 February 20, 2009submicron aerosol. The spikes are made up ofsubmicronparticulate matter, and the chemical analyses ofthe spikes and ash particles collected on the Nucleopore filters downstream ofthe impactorplates are shown in Table 4. Both samples are dominatedby sodium and sulfurthat are likely in the form ofsodium sulfate. These sulfate materials exhibithighly cohesive tendencies.

Figure 12. Scanning electron microscope images ofspikes formed on impactorplates when high-sodium subbituminous coal is combusted (the picture on the right is a close-up ofthe spike) (Hurley and Katrinak, 1992).

Supplemental Information For Consideration by NDDH 20 February 20, 2009Table 4. Chemical Composition ofthe Spike Shown in Figure 12 andthe Filter (weightpercent expressed as equivalent oxide). 100% Coal A 

### Oxide Spike Filter NazO 35.1 17.3 MgO 1.4 7.8 Alz 0 3 2.0 9.8 SiOz 9.1 10.6 PzOs 0.4 0.2 503 39.7 28.0 KzO 2.6 1.5 CaO 6.2 15.7 TiOz 0.2 1.8 CrZ03 1.4 0.1 Fez03 0.9 2.9 BaO 0.5 2.6

In addition to the aforementionedtesting results, penetration ofsubmicronparticles through ESP and scrubbers has been reportedby numerous researchers (Markowski and others, 1983, and Lighty and others, 2000). Figure 13 shows the penetration ofparticulate from ND lignite to be the highest ofthe combustion systems tested as part ofthe DOE field testprogram.

Supplemental Information For Consideration by NDDH 21 February 20, 2009

# •**-~** 

# . !**t-------r-----J~_R_-_+___t** 

## ----IIIIIIJ 

# I • CMIInaI 

# I ...-------!---I--+---"""',r-.-f

# 1.-_-._-_-_ COII

__ OMk

_ ...

0.1 t 10 100



### Plant Description Slack Emissions Bailly 345 MW, Cyclone Burner 60 kg/hr Dryscrubber. ESP Illinois high-sulfurbituminous Cardinal 615 MW, well-mounted cell burner 100 kg/hr ESp, no sulfur removal Pittsburgh No.8 bituminous Coal Creek 550 MW, tangential-fired 260 kg/hr Wetscrubber, ESP North Dakota lignite
Figure 13. Nonnalized differential particle mass distributions measured in the stack for a sample ofcoal-fIredpowerplants using differentburner and gas-cleaning technologies (Lighty and others, 2000). Supplemental Information For Consideration by NDDH 22 February 20, 2009Powerspan Testing at MRYS The Powerspan slipstream electrocatalytic oxidation (ECO) reactor system was designedby Powerspan and the EERC (Tolbert and Benson, 2008). The slipstream system was installedby the EERC at Minnkota Power Company's Milton 

### R. Young Station Unit 1 downstream ofthe ESP where the flue gas temperature ranged from 300°F to 350°F. The dielectric barrier discharge (DBD) reactorhas quartz electrode rods inside where electric current is passed in order to generate the plasmaused to oxidize nitrogen oxide (NO) to nitrogen dioxide (N02). The temperature ofthe quartz electrodes was approximately 100°F higherthan the gas temperature. The system at MRYS was commissioned on July 3,2007, and it operated for 107 days. Operational performance ofthe system was monitored and data were archived for post processing. A pair ofelectrodes was extracted andreplaced on a bi-weekly basis. Each pair of electrodes was shippedto Powerspan for testing in their laboratory reactor for NO conversion testing. Tested electrodes were then shipped to the EERC for scanning electron microscopy imaging and x-ray microanalysis. Measurement ofNOx conversion in the field by the slipstream system was notpossible due to the nitric acidproduction ofthe DBD reactor. Aerosols passing through the ESP at MRY Unit 1 resulted in significant accumulation on Powerspan's slipstream ECO barrier discharge reactorrods resulting in significant degradation in performance. The operational observations, performance results, and lab testing showedthatthe systemwas adversely affected by ash fouling. NOx conversion by ash covered electrodes was significantly reduced. Figure 14 visually compares a clean unexposed quartz rod to one exposedto flue gas and aerosols downstream ofthe ESP at MRY Unit 1. The abundance ofsodium in lignite coal fired during the Powerspan testing atMRYS is shown in Figure 15. The results show sodium levels measuredby the full stream elemental analyzer (FSEA) ranged from 3.5 to 6 % Na20 in ash. Figure 16 shows the degradation inNO conversion measured during subsequent lab testing at EERC using the exposed quartz rods removed from the slipstreamtest ECO DBD reactor at MRYS as a result ofbeing coated with aerosols. The NO conversion was severely impacted.

Supplemental Information For Consideration by NDDH 23 February 20, 2009A. Clean quartz rod. B. Dirty rod exposedto flue gas downstream ofthe ESP at MRYS Unit 1 for 16 days. Figure 14. Comparison ofa clean quartz rod and rod exposed to flue gas.

SODIUM FULL STREAM ELEMENTAL ANALYZER 3 July -18 October, 2007 9.00 8.00 7.00

.. 6.00 c CII 5.00 ·S cr w -4.00 

## i 3.00 2.00 I I-Na20**I~** I -AvgTrend



# --

# ~I 1\ f-- - 

## V I 

# U tJ i-" 

# - I-

## ~Ir II \ 

### N 

## " It1-- 

# r' "\ f-J 

# 1'\ \
1.00 0.00 3-Jul 17-Jul 31-Jul 14-Aug 28-Aug 11-Sep 25-Sep 9-0ct Date 23-0ct
Figure 15. Sodium levels in lignite delivered during testing ofthe Powerspanbarrier discharge reactor at MRYS Unit 1.

Supplemental Information For Consideration by NDDH 24 February 20, 2009

### SAMPLING SCHEDULE SAMPLING LOCATION REMOVE DAYS IN REPLACE DAYS IN DATE ROD# REACTOR WITH ROD REACTOR 3-Jul START TESTING 19-Jul F 6 16 15 91 K 11 16 1-Aug M 13 29 17 78 8 2 18 16-Aug H 8 44 19 63 D 4 20 3O-Aug C 3 58 81 49 J 10 82 13-Sep I 9 86 83 35 G 7 84 27-Sep E 5 100 85 21 L 12 86 11-0ct NU oAM'"'L :0 I:A I t(j\..; I I:U uut: U I Ht: "

... 11 T I U THE FINALSAMPLING. A 1 iAll Of me e1ectroaes IIstea 18-0ct 107 abOve will be removed for N 14 lab testing and analysis. LignitePilotElectrode Performance
100 90 80 70 60 50 40 30 20 10 

### o £.6 All' £. .. 0_ aA 

# -

11III .. I!I!



## ... 

# .. """ III o III '11II
8 10 12 14 16 18 20 EnergyDensity (watts/scfm)

AEERC #7 - CL 0 EERC #5

- D1Y AEERC #3

- CL ABurger
- CL /:"EERC #9

- CL III EERC #12 - D1Y IIIEERC#10
- D1Y
Figure 16. NO conversion for clean (CL) and dirty (DTY) for quartz tube exposedthe flue gas during the MRYS testing. Burger is a slipstream pilot ECO system in Ohio used for reference.

Supplemental Information For Consideration by NDDH 25 February 20, 2009

### Examination ofthe 

### quartz rodsremoved 

### from the slipstream ECO DBD reactor at MRYS (crosssectioned to expose coating thickness) by EERC using scanning electron microscope equipped with an x-ray analyzer showed significant elemental sodium, sulfur, and calcium in the ash coating the tubes after only 16 days oftesting. The data is reported on Figure 17. The thickness ofthe 

### layer was approximately 25 /lrn. A sonic hom was used for in-service cleaning ofthe 

### rodtube deposits. Images ofthe 

### reactor and coatings on the electrodes are shown in Figure 18.

Tag Na Mg AI Si P S CI K ca Ti Fe Sa

1 35.38% 0.98% 14.10% 4.68% 0.00% 35.75% 0.00% 1.42% 6.61% 0.02% 1.07% 0.00% 2 0.00% 0.00% 0.22% 98.52% 0.00% 0.00% 0.07% 0.89% 0.00% 0.30% 0.00% 0.00% 3 0.00% 0.00% 0.61% 98.11% 0.00% 0.00% 0.00% 1.05% 0.00% 0.00% 0.22% 0.00% 4 0.00% 0.00% 0.20% 98.33% 0.00% 0.00% 0.00% 1.19% 0.00% 0.00% 0.27% 0.00% 5 0.00% 0.00% 0.00% 98.70% 0.00% 0.00% 0.00% 1.24% 0.00% 0.00% 0.06% 0.00% 6 0.00% 0.00% 0.25% 97.26% 0.00% 0.00% 0.27% 1.70% 0.00% 0.00% 0.36% 0.16% 7 0.00% 0.00% 0.00% 97.93% 0.00% 0.00% 0.00% 1.55% 0.00% 0.00% 0.47% 0.05% 

### Figure 17. Example ofSEM point analysis on electrode #11 (removed from slipstream ECO reactor atMRYS after 16 days ofservice). Supplemental Information For Consideration by NDDH 26 February 20, 2009Figure 18. Images oftop ofslipstreamECO DBD reactor at MRYS showing ash accumulations on electrodes and reactor surfaces. Conclusions gainedby this work are: 1.) Sodiumrich aerosols and small ash particles thathad penetratedthe ESP accumulate and become bonded on the surface ofthe silica electrodes despite using a sonic hom as recommendedby Powerspan. 2.) Ash accumulations adversely affectedthe NOx conversion. 3.) The adverse impact occurs within a two weektime period.

Supplemental Information For Consideration by NDDH 27 February 20, 2009

### MRY Sulfate Aerosol Sampling The penetration ofaerosols through ESP and wet scrubbers is well known and has been studied since the mid 1970s (McCain and others, 1975; Ensor and others, 1975). As a result ofthese challenges, the quantity oftotal aerosols and sulfate aerosols was measured atMRYS by Markowski and others, 1983. Markowski and others (1983) collectedEPA method 17 particulate samples and size segregated the particles using an impactorthat aerodynamically separates particles and allows for the characterization ofeach fraction. The results ofthe EPA method 17 samples conducted over a four day period. The mass concentrations ofaerosols as determined by EPA method 17 sampling are illustrated in Figure 19 for the inlet and out ofthe scrubber. At the inlet aerosol mass concentrations ranging from a high ofover 10,000 /lg/m3 to a low of4000 /lg/m3• Significant levels were also found at the scrubber outletranging from 8800 to 2500 /lg/m3• The removal efficiency varied from -25 to 66%. Markowski and other (1983) offeredno explanation ofthe differences in the levels ofaerosols measured in the flue gas and removal efficiency. They did not considerthat the ash content ofthe coal varied significantly during the testing. Results oftesting at MRYS have shown significant differences in the quantity vaporized for coals thathave different ash contents (see Figure 3). The variations in ash content shown in Figure 19 reflect changing coal characteristics thatresulted in differences in aerosol mass concentration.

Supplemental Information For Consideration by NDDH 28 February 20, 200912000 

## :§ 10000 Q :::L C 8000 .2 

# - ns 

# .. 6000 

# - c CII u c 4000 0 v In In 2000 ns ::i 0 • Inlet

• Outlet

6/10/1981 6/11/1981 6/12/1981 6/13/1981

8.41% 12.12% 18.87% 5.74%

Sampling Date and Ash Content (as received) Figure 19. Mass Concentration ofAerosol Collected atMRYS Unit 2 at the ScrubberInlet and Outlet (Markowski and others, 1983). The results ofthe measurements ofaerosol capture are illustrated in Figure 20. The results show that aerosols less than one micrometer in diameter are not effectively captured in the wet FGD at the MRY facility. The graph also indicates the penetration ofthe particles through the FGD as a function ofparticle size. The penetration is the outlet size distribution dividedby the inlet size distribution. (Penetration = 1- efficiency). Markowski and others (1983) showed that the "metallic" sulfate aerosols (sodium sulfate) penetrated the FGD much more effectively than the largerparticulate materials.

Supplemental Information For Consideration by NDDH 29 February 20, 2009100

### .-------"""r"------"""r"-------, 1000

10 

## '0

0., 0.1**"---",,~** 

# i

"" 

# - " Q



## , ,.0 1.0 

# .B' II A. 

# "

0.0'0. ....,------,.... 0------.... 

# '0-----,:°1 ACTUAL

### DIAME'lER(MICROMETBlS) Figure 20. Penetration through the MRYS Unit 2 wet scrubber (Markowski and others, 1983).

The mass ofeach ofthe impactor size fractions for the aerosols collected at the inletand the outlet ofthe wet FGD upstream and downstream ofthe MRYS Unit 2 scrubber are illustrated in Figure 21 and 22 with the results tabulatedin Table 5. The total mass distributions are summarized in Figure 21 and the sulfate mass distribution is illustratedin Figure 22. Based on the impactor data the total mass ofparticulate thatpenetrates the scrubberis 5990 J.lg/m3 (Markowski and others, 1983). These ash materials consist ofa combination ofsulfates and Supplemental Information For Consideration by NDDH 30 February 20, 2009oxides ofsodium, calcium, and sulfur. Much ofthe aerosol is present in the 

### >14 J.lm size fraction. There are also significantmass in the less than 1 J.lm size fraction that has the potential to penetrate the pores ofthe catalyst. In addition, there is a significant mass in the <0.26 Ilm fraction. This fraction represents the ultrafme component that has been implicated as the most significant contributor to catalystpoisoning (Kling and others, 2007).
Table 5. Size segregated total and sulfateparticulate collectedupstream and downstream ofthe MRYS FGD (Markowski and others (1983). Inlet Outlet Inlet Outlet Total, Total, Sulfate, Sulfate, Size,**~m ~g/m3** **~gfm3 ~gfm3** **~m3**

<0.26 1910 769 436 602 0.26-0.52 401 640 164 274 0.52-1.1 883 1410 293 459 1.1-2.5 1020 265 291 69.2 2.5-6.7 337 154 173 94 6.7-14 300 367 100 103

>14 700 2390 439 46.2
Total 5550 5990 1896 1650
>1.1 2357 3176 1003 312.4 <1.1 3194 2819 893 1335 Percent

>1.1 42.5% 53.0% 52.9% 18.9% <1.1 57.5% 47.1% 47.1% 80.9%

Supplemental Information For Consideration by NDDH 31 February 20, 20093000 

## Total Particulate 

# - 2500 Q :::L 

### r: 2000 0 

# .. III 1500 

# .. ... c u 1000 c II Inlet 0 v III 500 II Outlet III III :E 0

Size, Jlm

Figure 21. Total particulate removal across scrubber at MRYS.

700 600 

# - Q :::L 500 

### r: 0 400 

# .. III 

# .. ... 300 c u c 200 0 v III 100 III III :E 

## Sulfate Particulate

II Inlet II Outlet

Size, Jlm Figure 22. Sulfate particulate removal across scrubber at MRYS.


### 6. Determination of Sodium Loading Adversely Affecting SCR Catalyst Performance Alkali metals such as potassium and sodium are known poisons and blinding agents for SCR catalysts used for NOx emissions control. As previously discussed (Burns & McDonnell and others, November 2008) and repeated above, there will be submicron sodium, likely in sulfate Supplemental Information For Consideration by NDDH 32 February 20, 2009form, emitted from the 

### dry ESPs at MRYS that will contaminate SCR catalyst located in a lowdust ortail-end configuration. The first fundamental issue is "how to estimate the amount (mass rate) ofsodium and in what size range couldbe emitted from the boilers at MRYS, for the purposes ofa BACT analysis". Because BACT analyses on existing sources are not common, we also presume themto be "studies on paperusing available information". We do not consider BACT analyses as research projects requiring design ofexperiments, site-specific testing, and development engineering for the control technique being considered. Thus, this first issue is a significant challenge. The second fundamental issue is "forthe purposes ofa BACT analysis, whatrate ofcatalyst deactivation is likely to occur as a result ofexposure to the expectedparticle or aerosol size range and concentration ofsodium emitted from a boiler over a given period oftime?" Only by assuming thatthese fundamental issues canbe resolved with the degree ofcertainty required for purposes ofa BACT analysis, can such a comparison then be performed that could leadto a basis oftechnical feasibility oflow-dust and tail-end SCR technology for MRYS. Because most coals fired in utility boilers do not have the high sodium content ofNorth Dakota lignite, andbecause cyclone boilers fire at high temperatures which promotes the emission of submicron sodium aerosols, there is not much publishedtechnical information that is available to help answerthese fundamental questions. We can gain some insight into what might happen to SCR catalyst exposedto flue gas containing significant amounts ofalkali salts by looking atthe impact ofco-firing biomass such as straw or switchgrass with coal. This is increasingly important to utilities thathave chosen to pursue such a fuel mix strategy who also employ SCR technology on theirboilers. We have previously commented on the high-dust SCR catalyst experience atthe Avedore plant (Burns & McDonnell and others, November 2008) and the high frequency ofcatalyst washing performed to counteract the apparent highly negative impacts of biomass cofrring. 

### 7. Alkali Aerosol Loading and Catalyst Deactivation There is evidence that alkali aerosol loading in the flue gas streams results in catalyst deactivation. The total and sulfate aerosol mass loading measurements were conductedby Markowski and others (1983) at the inlet and outlet ofthe wet FGD scrubber at MRYS Unit 2. Supplemental Information For Consideration by NDDH 33 February 20, 2009The key data obtainedby Markowski and others (1983) is illustrated in Figure 23 as well as the size fractionated data in Figures 21 and 22 provide information on loadings. The dataprovided shows a range ofmass concentrations up to 8800 J.lg/m3 at the outlet ofthe scrubberbased on EPA method 17. Based on results in mass size distribution ofthe aerosol, 47 to 80% ofthe aerosols thatpass through the scrubber are less than 1.1 J.lm. Much ofthis material is in the ultrafine fraction. These materials have the potential to penetrate into the catalyst, causing plugging, and can react with active components in the catalyst. There are numerous publications supporting these mechanisms. Kling and others (2007) found thatthe rate ofcatalyst deactivation was related to the accumulation ofsodium and potassium on the catalyst as shown in Figure 24 and 25. The work by Kling and others (2007) is consistent with the work conducted by Khodayari, 2001 illustrated in Figure 26 where he shows thatthe deactivation rate is more significant for PC-fired systems as compared to fluidized beds. The work based on Kling and others (2007) when applied to PC and cyclone-fired systems will likely underestimate the degree ofcatalyst deactivation because ofthe firing methods.

12000



## ... E 10000 

# - Ol ::. c' 8000 0 -.;:: III 

# .. 6000 

# ... C 41 u c 4000 0 V III III 2000 III :;: 0 III Inlet III Outlet

6/10/1981 6/11/1981 6/12/1981 6/13/1981

8.41% 12.12% 18.87% 5.74%

Sampling Date and Ash Content (as received) Figure 23. Mass Concentration ofparticulate collected atMRYS using EPA Method 17 (Markowski and others, 1983).

Supplemental Information For Consideration by NDDH 34 February 20, 2009n 

### cq u



# .. <>

... 

### <>A A 

# • A

.....

..... o FR (season_C)
• B+30%DW(season B) o P+15%W(season_B) OP (season_C) mFR+S (season C A FR+S (season 0 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% 0,00 0,05 0,10 0,15 0,20 0,25 0,30 Accumulation ofalkali (potassium+sodium] on catalyst sample [weight percent] Figure 24. Catalyst deactivation compared to accumulation ofpotassium and sodium on the catalyst surface (Kling and others, 2007).


## o;e 60% 

## i:.. 

# ..... 

# ..

# . 50% 

# &:**~.e** 40% >. 

## 15"c 

# ... 30% u.s**~e** -::::s 20% 

# !s uao c M 10% 

# .-

# . .I! .::::s 

### ,90 0% .c 

# Ii**~<; ~iii'**  .-. 

# <; iii' 

### 6 6'**~.-. ~~**  u #. c l 

## a. 

# i' • en c l f/) c' 0<1 

### om #.C o::c o::c o::c**~§** c l**~~** 100**u.~ u.~** **u.~ ~~** **~~**

### ~~ ... fIl IO fIl + aI + aI aI aI aI aI 

# U.l U.l .-tll Mal 

## a.! a.! ! i i 

## ! + 

### i + 

### i

...... ...... 

### m...... mFigure 25. Loss in catalyst activity when exposed to flue gases containing vaporized Na and K when combusting biomass in a fluidized bed combustion system (Kling and others, 2007).

Supplemental Information For Consideration by NDDH 35 February 20, 20091:IM-r-------------------------..,



# .CFB .CFB eCFB OPe 

### OPe OPe APe



### ..**L--I_----I-_--I-_--1-_--1-_--I-_-\-_-+-==+==~** 

### o - 1C1OO 1500 2alID 25IJD 3IIJD !SUD 4lIXI 450D 5CXIJ Op 

### uantllne'" Figure 26. Comparison ofpoisoning ofcatalysts in a CFB boilerfIring forest residues and in a PC fIring pulverized wood (Khodayari, 2001). There is a direct relationship to the concentration ofsodium and potassium in the flue gas with accumulation on the catalyst and subsequent deactivation. The deactivation shown in Figures 24 and 25 directly relates the accumulation ofsodium and potassium on the catalystwith deactivation. Deactivation rates of40 to 55 percent (considering the errorbars) was measured on catalyst that had accumulated 0.25 wt % sodium and potassium on the catalyst surface when exposed to flue gas containing 22,500**~g/m3** sodium and potassium for only 1500 hours. The flue gas downstream ofthe scrubber at the MRYS Unit 2 has been shown to contain aerosols at levels of8800**~g/m3** with about 50% ofthe mass being less than 1.1**~m.** The ash that exits the ESP on Unit 1 is dominatedby sodium and sulfurbased on the results from the Powerspan testing. The quartz elements exposed to the flue gases for 16 days (384 hours) were completely covered with sodium and sulfurrich ash (see Figure 17). These elements were exposedto cleaning using a sonic hom. The sodium and sulfurrich ash produced a dense layer on the surface ofthe quartz rods approximately 25**~m** thick in 384 hours. The MRYS results along with research efforts conducted in Europe show that masking and poisoning ofSCR catalysts from flue gases containing alkali aerosols is a significantproblem thathas notbeen overcome by SCRcatalyst vendors.
Supplemental Information For Consideration by NDDH 36 February 20, 2009

### 8. Experience of ESP/FGD Equipped Utility Plants Co-Firing Biomass and Coal with TESCR In previous communications to NDDH, it was stated that no recent TESCR installations hadbeen completed on utility boilers anywhere in the world. Burns & McDonnell subsequently learned aboutthe Amager facility currently under construction in Copenhagen, Denmarkthat will involve a TESCR system on a multiple fuel-fired boilerthat is expected to burn combinations of pulverized coal, wood pellets, straw, and fuel oil. A technical paperwritten by HaldorTopsoe described the design efforts for SCRs on biomass (straw)-frredboilers (Crespi, and others, 2008) and indicatedthat the TESCR configuration was chosen specifically to address the concerns about catalystpoisoning due to the constituents ofthe straw (notably potassium). Follow-up communications were initiated by Bums & McDonnell with HaldorTopsoe, which suppliedthe catalyst for Amager's TESCRreactor; Alstom, which was the supplier ofthe SCRreactor system and the Flowpac wet FGD system (see attachedproject summary); and a plant engineer for the boiler's operator (Vattenfall A/S) (Bums & McDonnell personal communications, 2009). These personal communications provided the following information about this installation:

a. The boiler is wall-fired and can be frred with oil (start-up), coal and wood- and straw-pellets. Coal and bio-pellets are pulverized in mills [priorto firing in the boiler], with full flexibility from 

### 0 to 

### 100 % straw. 

### It is expected to frre 

### 100% biomass most ofthe time. Maximum heat input to the boiler is 

### 350 MW during coal and oil fIring and 

### 300 MW during wood/straw pellets fIring. b. Danish regulations on emission include an emission fee ($/ton ofS02 orNOx emitted), therefore the utility looks for the best compromise between low cost fuel and low emissions. The utility wants to be able to fire any mixture as specified above for the flexibility ofcost and availability ofboth straw and coal. This is common for European customers who have to balance carbon dioxide (C02) emissions. When a new plant is built, the utility wants to make
sure it can fire any fuel that may come on the market in the coming years without being limitedby his boiler and cleaning equipment. Ofthe biofuels, straw is consideredto be the most difficult as compared to woodchips, saw dust, paper, etc. The situation is the same in Sweden, Holland and some othercountries. Supplemental Information For Consideration by NDDH 37 February 20, 2009c. Atthe planning stages ofthe Amagerproject it was expectedto co-fire biomass and coal in the boiler. Now, ifbio-mass fuels are not available, 100% coal will be fired. When bio-mass is fired, NOx emissions are expectedto be low, so the utility is allowed to bypass the flue gas cleaning system. According to European regulations, the NOx emission limitwith bio-mass is 300 mglNm3 (dry 6% 

### 02). Both the FGD and the SCR systems will be bypassed, ifNOx in the flue gas emitted from boiler is below 300 mglNm3• No dampers are installedupstream of the TESCR. There is a global by-pass ofboth FGD and TESCR systems. The wet FGD and TESCR are mainly needed for any coal firing flue gas cleaning. When pure straw/ biomass is fired the whole wet FGD and SCR system can be bypassed, saving a lot ofoperating cost as both SOx andNOx will be within the limits from the authority. The clientwas not sure that they could get enough ofstraw available at an acceptable price, so the boilerhad to have great fuel flexibility.
Based on this information, it appears that the Amagerplant's TESCR system will typically be bypassed when the fuel firing conditions are most difficult for the SCR catalystwith regard to poisons. Consequently, Burns & McDonnell does not believe the Amager facility projectunder construction provides any indication that TESCR technology is technically feasible for application to MRYS.



### 9. Relevance of Recent TESCR investigations at We Energies' South Oak Creek Station Recently, in response to a Consent Decree that requires the installation ofSCRtechnology on Units 5, 6, 7 and 8 at its South Oak Creek Generating Station in Oak Creek, Wisconsin, We Energies (Wisconsin Electric) has investigatedthe use ofTESCR technology. The investigation ultimately led to the determination that the TESCR approach would not be used. Based on information obtainedby Burns & McDonnell from the engineering consultant and the technology vendor for thatproject (Bums & McDonnell personal communications, 2009), the decision notto use TESCR technology was based on economics. However, the fact that TESCR systems were considered to be feasible for specific application at the South Oak Creekunits is not indicative thatthe same technology would be technically feasible for application at MRYS. This is due to Supplemental Information For Consideration by NDDH 38 February 20, 2009the substantial differences between the South Oak Creekboilers and the MRYS boilers, as summarized in the Table below:

Table 6. Comparison ofBoilers for South Oak Creek and Milton R. Young Station South Oak Creek Milton R. Young Fuel Type PRB Coal ND lignite (low ash, very low sulfur) FGD Design Fuel Sulfur Content, 1.15 3.95 SOzlb/mmBtu Firing Type PC wall-fired (Units 5 & 6) Cyclone fired (Units 1 & 2) PC tangential (Units 7 & 8) (slagging-type, wet bottom) (dry bottom) Design Boiler Outlet NOx 0.15 0.51 (Unit 1 w/ASOFA) Ib/mmBtu 0.49 (Unit 2 w/ASOFA) Consent Decree NOx Limit 0.10 TBD Ib/mmBtu
The significant differences in the ash characteristics, especially with regard to the sodium content, between PRB coal and North Dakota lignite have been explained inprevious submittals to NDDH (Burns & McDonnell and others, 2007 and 2008). The effect that cyclone firing has on the partitioning ofsodium has been explainedpreviously, and reiterated in this document. In addition, it can be seen from the tabulation above that the S02 content ofthe flue gas will be up to four times as high atMRYS as at South Oak Creek, eitherbefore or afterthe FGD system. This means that the potential for deposition ofammoniumbisulfate on the SCR catalyst, due to the reaction between the ammonia reagent and the S03 that fonns within the SCR reactorwhen catalytic S02 oxidation occurs, will be proportionally much greaterfor the application ofTESCR technology to MRYS than it would have been at South Oak Creek. Finally, it shouldbe noted that compliance with the Consent Decree for NOx emissions in the case ofSouth Oak Creek required only a moderate degree ofemission reduction in the SCR systems, meaning thatthe design was notparticularly challenging from a percentage reduction standpoint.

Supplemental Information For Consideration by NDDH 39 February 20, 2009

### 10. Relevance of Ongoing LDSCR Installation Project at We Energies' South Oak Creek Station Following the elimination ofTESCR systems from further consideration for the SCRretrofits requiredby the Consent Decree, We Energies is proceeding with the installation ofLDSCRs at Units 5, 6, 7 and 8 at South Oak Creek. Again, as shown in Table 6, the significantdifferences between the fuel, firing type, sulfurcontent and NOx reduction requirement supportthe contention that installation ofLDSCR systems under construction at South Oak Creek does not constitute a demonstration that LDSCRtechnology is technically feasible for MRYS.



### 11. Relevance of Existing LDSCR Installation at PSEG Mercer Station In response to a January 2002 Consent Decree that required the installation ofSCRtechnology on Units I and 2 at its coal-fired electric generating station in Mercer County, New Jersey, PSEG Fossil (PSEG) has installed and operated LDSCR systems atthis site since 2004 (Unit 2) and 2005 (Unit 1). However, the fact that LDSCR was consideredto be feasible for specific application at the Mercerunits is not indicative that the same technology wouldbe technically feasible for application at MRYS. This is due to the substantial differences between the Mercer boilers and the MRYS boilers, as summarized in the Table below: Table 7. Comparison ofBoilers for Mercer and Milton R. Young Station Mercer Milton R. Young Fuel Type Low-sulfur bituminous coal NO Lignite (Venezuelan and eastern 

## u.s. blend) Firing Type PC wall-fired, slagging-type (wet Cyclone fired (slagging-type, bottom) wet bottom) Design Boiler Outlet NOx 1.40 (prior to controls) 0.51 (Unit 1 w/ASOFA) Ib/mmBtu (see note below) 0.49 (Unit 2 w/ASOFA) Consent Decree NOx Limit 0.10 TBO Ib/mmBtu Mercer has demonstrated and employed various NOx reduction techniques before LOSCR installation in 2004, primarily SNCR, with and without fuel-lean gas reburn, and in-duct SCR.
Supplemental Information For Consideration by NOOH 40 February 20, 2009The significant differences in fuel type and firing type between these two plants would create very different flue gas characteristics ofthe flue gas entering the LDSCR, especially with regard to the sodium aerosol. The significant differences in the ash characteristics, especially with regard to the sodium content, between bituminous coal andNorth Dakota lignite have been explained in previous submittals to NDDH. The effect that cyclone firing has on the partitioning ofsodium has also been explained previously, and reiterated in this document.



### 12. Additional Technical Feasibility Issues for TESCR at MRYS As noted in previous submittals to NDDH (Burns & McDonnell and others, Septemberand November, 2008), there are no existing orplanned TESCRs on coal-firedutility powerplants in the U.S. A review ofthe TESCR applications on German coal-firedpower stations has indicated that these installations are configured basically as shown in the diagram on page 1 ofthis document. That is, flue gas from the outlet ofthe wet flue gas desulfurization (FGD) system absorber is reheatedprior to entering the TESCR system, using aregenerative (Ljungstrom type) gas-to-gas heat exchanger (GGH) that supplies heat that was extracted from the flue gas upstream ofthe FGD. According to consultation with the designers ofthe LDSCR systems for South Oak Creek, the expected leakage through this type ofheat exchangerwill be at least 5.0 percent. When flue gas leaks across this "FGD GGH" from the inletto the outlet flue gas stream, it effectively bypasses the FGD absorber, meaning thatno S02 removal takes place from this slipstream ofthe total flue gas. In the case ofboth MRYS Unit 1 (in the CD) and Unit 

### 2 (in the proposed BART), NDDH has indicated that 95% S02 removal is required. This will preclude the use ofthis type ofGGH, because, as leakage around the FGD system approaches five percent, itbecomes 

### impossible to achieve 95% overall S02 removal. This was not an issue for the German FGD systems, which were notrequired to achieve the same high level ofS02 removal efficiency that is dictatedby the MRYS CD and the proposed S02 BART.

Supplemental Information For Consideration by NDDH 41 February 20, 2009This leakage couldbe avoided ifthe saturated flue gas from the FGD system absorber were sent directly to the "SCR GGH" upstream ofthe TESCR reactor as shown in the diagram on page 1. However, according to the engineering consultant who performed the evaluation ofTESCR technology at South Oak Creek (as described in Section 9 above), "Saturated flue gas tends to be corrosive and there is virtually no experience with Ljungstrom GGH handling corrosive saturated gas. Saturated gas from the absorber tower carries gypsum slurry droplets, which tend to plug the cold end ofthe GGH with gypsum deposits that are extremely difficult to clean on-line." Another aspect ofthe TESCR approach that appears infeasible at MRYS is thatthe flue gas would enterthe new fiberglass reinforcedplastic (FRP) ductwork leading to the respective chimneys, and Unit 2's FRP chimney liner, at a normal temperature above the 200°F design limit, due to the TESCRreactor's outlettemperature being above 500 OF entering the treated-side ofthe SCR GGH. Based on these considerations, the only way to apply TESCR technology to the units atMRYS while providing high S02 removal would be to employ a flue gas reheating technology which has not been proven in the application to a TESCR system at any full scale powerplant installation. This indicates that TESCRtechnology is technically infeasible for application to the Units at MRYS.


### 13. Summary and Conclusions

• Because ofthe unique properties ofFort Union Lignites, they produce more vaporized ash (Na and other elements) that othercoals including PRB and bituminous coal.

• Highercombustion temperatures associated with cyclone firing result in more ash vaporization and increased levels ofsubmicron fine and ultrafme aerosol particles.

• Cyclones reduce the quantity ofcoarse flyash particles in the flue gas available to provide sites for sodium condensation and to dilute the bonding effects ofthe aerosols once deposited on a surface.

• The particle collection efficiencies for fine particles less than 1 J.lm are poorfor both ESP and wet FGD, such as those utilized at MRYS.

• The number offlue gas particles per gram increases ten times for 1 J.lm versus 10 J.lm and anotherten times for 0.1 J.lm versus 1 J.lm (diameter), so the fme andultrafme aerosols are plentiful in numberbecause ofpenetration through ESPs and scrubbers. These fine particles have high surface areas, are highly reactive, and readily bond togetherbecause ofhigh surface energies. Supplemental Information For Consideration by NDDH 42 February 20, 2009• Particles in the 0.1 to 1.0 J.1m size fractions are largely composed ofcondensed vapor phase species such as sodium, potassium, and sulfur.

• Sodium-rich aerosol particles present in flue gas downstream ofthe ESP at MRYS Unit 1 significantly impactedthe performance ofthe Powerspan slipstream ECO barrierreactor system in less than two weeks ofexposure.

• Sodium- and sulfur- rich coatings on the surface ofthe Powerspan quartz rods were dense, continuous, and difficult to scrape off. These sodium and sulfurrich layers were produced in only 384 hours and were 25 J.1m thick.

• Emission rates downstream ofESP described in the reports providedby the NDOH range from 4,500 to 50,000 J.1g1Nm3• The particulate emitted are dominated fine andultra fme aerosols rich in sodium andpotassium. NOTE: The level of22,500 J.1g/Nm3 ofsodiumandpotassium-rich fly ash derived from biomass firing resulted in catalyst deactivation of 30 to 40 

### % in 1500 hours (King and others, 2007).

• These are no TESCR installations in the U.S. on utility coal-firedboilers, and there are no examples ofTESCRtechnology being applied worldwide on any coal-fIredboilers having the same high percentage S02 removal requirements that are applicable at MRYS. The heat exchangertechnology thathas been employed on other TESCR systems for bituminous coal-fIredboilers located in Germany, ifapplied at MRYS, will preclude compliance with the established S02 removal requirements.

• The expected outlet temperature from the TESCR and downstream gas-to-gas heat exchangers will be too high for the fiberglass flue gas ductwork exhausting the chimneys atMRYS.

• The existing LOSCR installations in the U.S. are on units fIring coals and using coal fmng technology that will notproduce the same high level ofcatalystpoisons in the flue gas as wouldbe the case atMRYS, where both units are cyclone furnaces firing highsodium lignite.


### Conclusions In the end, arguments regarding the technical feasibility oftail-end and low-dust SCR technology at Milton R. Young Station are reduced to disputing the characterization ofthe gas stream characteristics and the impacts ofthose characteristics on boiler and emissions control operations. Those who suggest that these impacts can be resolved by the use ofLOSCR and TESCR, and that such technology will work atMRYS without failure, cannotpointto relevant data showing success at other coal-fIredboiler SCRs which have such high levels ofsodium in the fuel and the flue gas stream. Considering the findings and conclusions presented above and previously, low-dust and tail-end SCRtechnology would not be available to apply to Units 1 and 

### 2 atMRYS without extensive long-term pilot-scale testing and design development efforts. As BACT is notthe selection ofa pollution reduction technology that requires such research and development in order to determine Supplemental Information For Consideration by NDDH 43 February 20, 2009ifit canbe successfully deployed for full-time, full-scale operation, we believe that low-dust and tail-end SCRtechnology is not technically feasible atMRYS for Unit 1 and Unit 2 NOx emissions control (Arfmann and others, 2007).

Supplemental Information For Consideration by NDDH 44 February 20, 2009

### References Arfmann, D.; Benson, S.A; Weilert, C.V. prepared forMinnkota Power Cooperative, Inc., Appropriateness ofConducting PilotTesting ofSelective Catalytic Reduction (SCR) Technology at Milton 

### R. Young Station Units 1 and 2, ForUse In A NOx BACT Analysis, August 14, 2007. Benson, S.A.; Laumb, M., Fuels and Power Systems Workshop, Centerfor Innovation, Grand Forks, ND, June (2008). Benson, S.A; Rindt, D.K.; Montgomery, G.G.; Sears, D.R. Microanalytical Characterization ofa North DakotaFly Ash. IndustrialandEngineeringProductResearch andDevelopment, 1984, 23,252. Burns & McDonnell, University ofNorth Dakota, and Fuel Tech, Responses to Hans Hartenstein's October 2008 Remarks to September 22,2008 Comments and Responses on NDDH Preliminary NOx BACT Determination for Milton 

### R. Young Station (MRYS), November 17, 2008. Burns & McDonnell, personal communications with Haldor Topsoe (SCR catalyst supplier), Alstom (SCR reactor and Flowpac wet FGD system supplier), and Vattenfall A/S (operator of the Amager district heating powerplantunder construction), January-February, 2009. Burns & McDonnell, personal communications with the Washington Group ofURS (engineer for the SCR), and BabcockPowerEnvironmental (SCR reactor and system supplier ofthe We Energies' South Oak CreekUnits 5&6 and Units 7&8 low-dust SCRs under construction), February, 2009. Crespi, M., Porle, M., Larsson, AC., La Civita, 

### R., Nielsen, AR., The influence ofbiomass burning in the design ofan SCRinstallation, available from Haldor Topsoe's website accessed 1- 22-2009 at http://www.topsoe.com/Business_areas/Flue_and_waste**~as/~/media/PD** F%20files/Scr

_denoxl The%20influence%200fUIo20biomass%20burning%20in%20the%20design%200fU1020an%20SC R%20%20Powergen%20Europe%202008.ashx Ensor, D.S., Jackson, B.S., Calvert, S., Lake, C., Walton, D.V., Nilan, R.E., Campbell, K.S., Cahill, T.A., Flocchini, 

### RIG., EPA Report No. 600/12-75-074, Washington, D.C., 1975. Hurley, J.P.; Katrinak, K.A., Determination ofAsh Formation and Deposition Mechanisms at Minnesota Power Clay Boswell Station; DOE/MC/10637-3365, July 1992. ICAC Institute ofClean Air Companies, Particulate controls, http://www.icac.com/i4a/pages/index.cfm?pageid=3398 Khodayari, R., Selective Catalytic Reduction ofNOx: Deactivation and Regeneration Studies and Kinetic Modeling ofDeactivation, Ph.D. Thesis, 2001, Dept. ofChemical Engineering II, Lund, Sweden. Kling, A.; Andersson, C.; Myringer, A; Eskilsson, D.; Jaras, S.G., Alkali Deactivation ofHighDust SCR Catalysts Used for NOx Reduction Exposed to Flue Gas from 100-MW-Scale Biofuel and PeatFired Boilers: Influence ofFlue Gas Composition. Applied Catalysis B: Environmental 2007,69,240-251.

Supplemental Information For Consideration by NDDH 45 February 20, 2009Lind, T., Hokkinen, J., and Jokiniemi, J.K., Saarikoski,S., and Hillamo, R., Electrostatic Precipitator Collection efficiency and Trace Element Emissions from Co-Combustion of Biomass and Recovered Fuel in Fluidized-bed Combustion, EnvironmentalScience and Technology, 2003, 37, 2842-2846. Lind, T., Valmari, T., Kauppinen, E., Nilsson, K., Sfiris, G., and Maenhaut, W., Ash Formation Mechanisms During Combustion ofWood in Circulating fluidized Beds, Proceedings of the Combustion Institute, 2000, 28, 2287-2295. Lighty, J.S., Varanth, 1M., and Sarofim, A.F., Combustion Aerosols: Factors Governing Their Size Composition and Implications to Human Health, 

### J. Air & Waste ManageAssoc, 2000, 50:1565-1618. Markowski, G. R. Ensor, D. S. Hooper, R. G. Carr, R. C. A submicron aerosol mode in flue gas from a pulverized coal utility boiler, Environ. Sci. Technol., 1980,14 (11): 1400-1402. Markowski, G.R., Downs, 1L., and Woffmden, G.J., Sulfate Aerosols from Western Low-Rank Coal-FiredBoilers with FGD: Summary ofTests at Coal Creek, Clay Boswell, Milton R. Young, and San Miguel Stations, DOE/FC/I0182-t15 (DE83014539), May 1983. McCain, J.D., Gooch, J.P., Smith, W.B., 

### J. AirPol/ut. ControlAssoc., 1975,25, 117. Mohr, M., Ylatalo, S., Klippel, N., Kauppinen, E.!., Riccious, 

### 0., and Burtscher, 

### H., Submicron Fly Ash Penetration through Electrostatic Precipitators at Two Coal Power Plants,Aerosol Science andTechnology, 1996,24, 191-204. ND Department ofHealth, Division ofAir Quality Preliminary BestAvailable Control Technology Determination for Control ofNitrogen Oxides for M.R. Young Station Units 1 and 2, June 2008, released for public commentJune 3, 2008. Nobrega, S.W., Falaguasta, M.C.R., and Coury, J.R., A Study ofa Wire-Plate Electrostatic Precipitator Operating in the Removal ofPoly dispersed Particles, Brazilian Journalof Chemical Engineering, April-June 2004, Vol 21, No. 02, pp 273-284. Noppenau, Henrik, CleanerFossil Fuels for Sustainable Development Co-firing Coal and Biomass, Accessed 10/28/2008 at http://www.usea.org/CFFS/CFFSNeptun/Co-firing%20- (WEC-CFFS)%20Neptun%20June%2013%202006.pdf Ohlstrom, Mikeal, Jokiniemi, Jorma, Hokkinen, Jouni, Makkonen, Pasi, and Tissari, Jarkko, Combating Particulate Emissions in Energy Generation and Industry, Tekes, VTT Technical Research Centre ofFinland, 2006. Power Station Emissions Handbook, Cooperative Research Centre for Coal in Sustainable Development, http://www.ddsd.biz/PSE Handbook/5/6/5/index.cfm accessed 11/24/2008. Senior, C.L., Panagiotou, T, Sarofim, A. F., and Helble, J.1., Formation ofUltra-Fine Particulate Matter from Pulverized Coal Combustion, Preprints Division ofFuel Chemistry, 2000,American Chemical Society, 45(1). Tolbert, S.G.; Benson, S.A. N Task 117

- Impact ofLignite Properties on Powerspan's NOx Oxidation System; Final Report (May 1 - Dec 31, 2007) for U.S. Department ofEnergyNational Supplemental Information For Consideration by NDDH 46 February 20, 2009Energy Technology Laboratory Cooperative AgreementNo. DE-FC26-98FT40321, Powerspan, Montana-Dakota Utilities Co., Minnesota Power, Basin Electric Power Cooperative, North Dakota Industrial Commission, and Minnkota Power Cooperative, Inc.; EERC Publication 2008- EERC-03-09; Energy & Environmental Research Center: Grand Forks, ND, April 2008. U.S. EPA, educational modules found on the following website: http://www.epa.gov/apti/bces/module3/formation/formate.htm Woodward, K. , Stationary Source Control Techniques Document for Fine Particulate Matter, EPA-452/R-97-001, October 1998. (http://www.epa.gov/ttncatcl/dirl/fmepmtech.pdf)

Supplemental Information For Consideration by NDDH 47 February 20, 2C09