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# OAR Box 1781 Prepped by Ollie Stewart



### Document

Number: 

# 31)11-1-23 Docket Number: 

# A-90-3 7

Printed 10/29/2008 10:46:19 AM Sheet 31 of 1421 P. 2 

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<NOT E change s t

o the lO/STntecommendatio n ar e give in italics>

NESCAU M STATIONAR

Y SOURC E COMMTTTE

E RECOMMENDATION O N EMISSIO N LIMIT S FO RCOMBUSTION TURBINE S Draf t Apri l 199 1 Applicability: Smple or

combined

cycle combustion turbines, operating more than 2500 hrs/yr. A recommendation on simple cycle turbines operating less than 2500hours is available fromNESCAUM. Al l emissio n limit s i n ppm

v reflec t dr y basis , correcte d t o 15 % oxyge n and ISO conditions. I . Nitroge n Oxide Emissio n Limit s A . 1 MMBtu/h

r to 1(X ) MMBtu/h

r (not e 1 ) Ga s us e 3 0 ppm v (not e 2 ) Oil us e 5 0 ppm v (not e 2 ) B . Greater

tha n 10 0 MMBtu/h

r (not e 1 ) Ga s o r oi l a s primar

y fue l 9 ppm

v (note s 2 and 3 ) Limits different

from these may be considered if an applicant

proposes an advanced or innnovative combustion technology Gas primary

fuel with oil back-up fuel in use 9ppm for gas (note s 2 an d 3 ) 18ppm for oil (note s 2 and 3 ) 25 ppmv without

an SCR system It is possible that

higher NOx limits for oil will be considered

with corresponding decreases in NH3 slip. II . Carbo n Monoxide Emissio n Limit s A. Less than 100MMBtu/hr 50ppmv B. 100to 400MMBtu/hr 25 ppmv C. Greater

than 400MMBtu/hr

10ppmv With high levels of

water or steam injection, states may require oxidation catalysts to attain these emission limits. IU . Ammoni aEmission Limit

Ammoni aemission s o r

"slip " froma

n advance d nitroge

n oxide contro l system shoul d b e maintaine d belo w 1 0 ppm v unles s thi s emissio n limi t i s shown to b e inappropriate . Committee Draf

t 1 4/16/9 1P. 3

effective as steam

for NOx control and results in relatively higher CO emissions, for

the same water

to fuel ratio and, therefore, the use of water injection must

be justified. This guideline includes a recommendation for higher CO limits

for smaller turbines. For example, the smaller

frame combustion turbines (<10MW) which can meet the NOx guideline by water

(steam) injection would

be recommended

to meet a 50ppmvd

CO limit for economic reasons and

avoid a CO catalyst. However, aircraft derivative turbines generally require a CO catalyst whether or not SCR fuel gas treatment

is used. Intermediate size machines (10-40 MW) are being recommended to meet an intermediate CO limit <which has been deemed

feasible based

on ?what evidence>. (ref-NJ

turbine guidelines?> V . Ammoni aUs e (1.2.8 ) Th e Stationar

y Sourc e Committe e i s concerne d about release s of

ammoni afrom NO x contro l system s fo

r tw o reasons. First , individua l stat e permittin g program s ma

y require a n analysi s o

f ammoni aus e an d th e potentia l fo r releases . Second , i

f a n agenc y determine s tha

t aprojec t require s aPS D permit , the n th e Jun e 198 6 North County PS D reman d i n Regio n 9 (6 ) require s tha t th e toxi c effects o

f ammoni ab e include d in th e review. These hazards can be largely avoided by the use ofaquaeous ammonia. There ar e tw o basi c processes.therma l and catalytic , fo

r usin g ammoni ainjectio n t

o contro l nitrogen oxid e emission s fromlea n bumcombustio n equipmen t suc h a s ga s turbines . Th e therma

l proces s (SNCR

) i s effective only a

t temperature s greate

r tha n approximatel

y 1400° F although enhancers are being developed to allow operation at

turbine exhaust temperatures. Thi s i s highe r tha n norma l ga s turbin e exhaus t

temperature s of approximately 1000° F an d i s achievabl e only b y reheating th e ga s turbin e exhaus t i n a devic e suc h a s aduc t

burner . Th e catalyti c process , SCR , operate s i n a n optimu m temperatur

e windo w o f

approximately 650-850°F , arang e which i s normall y achieve d b y coolin g ga s turbine exhaus t i n ahea t recover y boiler . Catalysts are being developed to allow SCR operation at

variable exhaust

temperatures.(ref.?) I n either process , som

e unreacte d ammoni apasse s throug h to th e atmosphere . Thi s unreacte d ammoni ai s commonl y referred t

o a s ammoni a"slip. " Typically , th e amoun t o f ammoni aslip ca

n var y fromnearly "0 " (dr

y basi s correcte d to 15 % oxygen) , in awel l controlle d stabl e systemwit h moderat e conversio n efficiency (les s tha n 90%) , t o 3 0 ppm v o r more in system s requirin g very high conversio n efficiencie s or i n poorly controlle d o

r highl y variabl e systems . Sinc e a t thi s time , th e SC

Rproces s i s much mor

e prevalent

an d i s readily adaptabl e to ga s turbin e exhaus t conditions , the focu s her

e i s o n ammoni aslip from SC Rcontrolle d ga s turbin e emissions . I n the SC Rprocess , the overal l chemica l reactio n require s atheoretica l mola r rati o of NH3:NC> 2 o f 1:1 , although th e reaction i s complex becaus e o f the varyin g oxidatio n number s of

th e differen

t oxidize d specie s o

f nitrogen present

in th e exhaus t

ga s bein g treated . However , a s i s th e cas e in man y chemica l reactions , th e la

w o f mas s actio n require s a n exces s o f th e reagent , NH3 , t o driv e the reactio n if high conversio n efficienc y i s desired . Also , operatin g th e SCRammoni ainjection syste ma t it s theoretica

l limi t i s not practical du e t

o imperfect

mixing , loca

l variation s o

f concentration s i

n the reactor, and othe

r factors . I n practice , som

e amoun t o f unreacte d ammoni aslip mus t b e tolerate d i

n th e exhaus t gas . Catalys t

manufacturer s wis h t o operat e a t 20 % exces s ammonia , whic h correspond s to approximately 3 0 ppm v slip . Som

e o f the factor s tha

t influenc e th e amoun

t o f slip are : 1 . contro l systemla

g an d imperfec t

operatio n o

f instrumentation , continuou s emissio n monito r problems , etc . Committe e Draf

t 6 4/16/9 1P. 4

» A 2 . high temperatur e "hotspots " favoring oxidatio n o f NH3 3 . lo w temperatur

e area s resultin g i

n incomplet

e o r slo w reactions 4 . variation s i n NH 3 an d NO x concentratio n acros s th e duc t 5 . incomplet

e mixin g o f ammoni awid

i the exhaus t

ga s 6. conversion of

nitrogen to ammonia 7 . variation s i

n the quantit

y o f exhaus t ga s due t o loa d change s and sluggishnes s in achievin g ane

w equilibriumse

t poin t i n the contro l system . I n man y ga s turbin e applications , th e trade-of f fo r th e reductio n in NO

x emission s ma y b e the substitutio n o

f a n equivalen

t amoun t o f ammoni aemissions . For

example , a typica l water-injecte d turbin e ma

y reduc e NO

x t o 5 0 ppm v and a n add-on SC

Runi t woul d reduc e NO x to 9ppmv. However , the exhaust gas may contain 10ppmv ofNHj. A s of Augus t 1988 , dire e SC

Rcontrolle d ga s turbine s i n Ne w Jersey hav e bee n permitte d fo

r maximu mallowabl e ammoni aemission s o f 20-3 0 ppmv . An odor

threshold for ammonia of

20ppmv is supported

by a review of

the literature( 10,11). Hig h conversio n efficiencie s (greate r tha n 90% ) and variabl e exhaus t condition s typicall

y result i n ammoni aslip s o

f 20-3 0 ppmv . At

alowe r conversio n efficiency (les s tha n 90% ) an d stabl e operation , a1 0 ppm

v sli p appear s i s a

n achievabl e objectiv e fo

r SC Rsystems . I

n situation s involvin g high conversio n efficiencies , variabl e loads , o r poorly responding contro l systems , a

n add-o n ammoni adecompositio n catalys t ma y b e neede d to mee

t thi s limit . Thi s recommendatio n state s tha t ammoni asli

p froma n advance d nitrogen oxide contro l systemshoul d b e maintaine d belo w 1 0 ppm v unles s thi s emissio n limi t i s show n to b e inappropriate . Japanese and European SCR projects are reportedly achieving 5 ppm. (ref) VI . Cos t o f Control s A s o f Augus t 1988 , ga s turbine installation s usin g SC Rsystem s hav e bee

n approve d in th e northeas t

for a n industr y standar d small ga s turbin e (th e G

E LM-2500 , a 2 1 M W unit ) and aindustr

y standar d larg e turbin e (the G

E Fram e 6 , a5 5 M

W unit) . <should this be changed

to the list developed

by McVay and

Seidmanfor

AWMA?> Thes e permit s indicat

e that , i n som

e cases , the cost-effectivenes s fo r advance d NO x contro l system s i s considere d "reasonable " compare d to othe r NO x control s bein g considere d by th e agencies . Th e NESCAU

M Stationar

y Sourc e Committee develope d aBAC T Guideline, which wa s approve d b y th e NESCAU M Boar d o f Director s on Octobe

r 11,198 8 (3) . Th e purpos e o f thi s documen

t i s t o promot

e consisten

t agency analysi s of

contro l technologie s durin g BAC T reviews . It

i s als o intende d t o provide prospectiv e applicant s wit h guidanc e o n conductin g aBAC T analysis . Th e documen t include s adiscussio n o f

cos t calculations . Fo r al l turbin e projects , a

n analysi s o

f th e cos t o f contro l option s usin g abasi s o f dollar s per to n of pollutan t controlle d should b e conducte d fo r eac h pollutan t subject t o BACT . Thi s shoul d b e calculate d usin g the tota l cos t o f the contro l technolog y system(s ) divide d by the tota l amoun t o f controlle d emissions , no t

jus t the incrementa

l cos t of an y advance d emissio n contro l systems . A copy o f th e BAC T Guideline i s availabl e fromNESCAUM . Combustion turbine emission control alternatives which should be considered (not necessarily in this order) are: 1. Low NO x

combustor 2. Increased

steam injection with CO catalyst 3. SCR 4. Dual function catalyst

(NO x and CO). Committee Draf

t 7 4/16/9 1P. 5

VII. Advanced

Combustion Control Since October

1988, there have been advances in combustion control and for some turbines N0

X exhaust concentrations of

approximately 12 ppmvd at 15% oxygen are reported to be achievable with bw N0 X combustors and

steam or water injection. Also, SCR use on gas turbines has increased. All new or significantly modified

projects with heat input over 100million BTU's per

hour should include a control

technology analysis to consider turbines with advanced combustion control technology, water

injection and

SCR. The NESCAUM

states do not

mandate tail

gas treatment

processes which involve ammonia injection if

low emissions can be achieved by other means such as combustion control. One reason is that anhydrous ammonia is classified as a hazardous substance in some states. Unless significant emission reductions are achieved, the NESCAUM states are reluctant

to mandate any technology which may present risk of catastrophic accident even if an acceptable risk

management

program can be incorporated. These processes result in unreacted

ammonia (slip) which offset the N0

X reduction. Therefore, the NESCAUM

states may consider

15 ppm N0

X without SCR to be equivalent

to 9ppm N0

X and 10ppm ammonia (slip) with SCR, assuming natural gas is used

as the primary

fuel. Nevertheless, if

the project

is affected

by the PSD regulations or is greater than 100million BTU per hour heat input, a thorough evaluation of SCR, low N0

X combustion, and

other available methods capable of achieving N0

X emissions lower

than 25 ppm, should

be evaluated in permit applications. The Committee is aware that several combustion gas turbine manufacturers are presently developing dry or wet (water or steam injection) low N0 X combustors. These machines may be able to achieve an N0 X emission level

of 25 ppmv or

less, for natural gas fuel, without

installing an SCR system. For example, the NJDEPrecently permitted two General Electric utility peaking turbines at 25 ppmv with natural

gas fuel and water injection. These were the Frame 6 (40MW) and

Frame 7 (75 MW) size machines. General Electric is also developing a new combustor for the Frame 7

turbine capable of achieving 25 ppmv N0 X without water injection and

11-13 ppmv N0

X with water injection. The Committee is also aware of the following examples. The Pratt & Whitney division of

United Technologies Inc. is developing a dry low N0 X combustor

for its model FT-8(50MW) gas turbine, that may be capable of

achieving 25 ppmv with natural gas. Siemens Kraftworks Union model V84 (150MW) is presently guaranteed at 25 ppmv N0

X with a dry low combustor

firing natural

gas. Turbines will

be available soon that

are expected to achieve 10ppmv. <ABB - Reggie to supply info; Bill K to get guarantees being offered> VIII . Conclusio n Th e NESCAU

M state s ar

e receiving and reviewing man y application s fo

r ga s turbine s which coul d represent larg e increase s in NO x emissions . Th e Stationar y Sourc e Committe e believe s tha

t turbine s wil l b e asignifican t new sourc e o

f NO x emission s i

n the region. Their

significance , combine d wit h th e nee d t o identif

y contro l technologie s fo

r us e in th e a"top-down " BAC T process , lead s th e Committe e to recommend ver y stringent emissio n limit s fo

r thes e sources . Th e fiv

e technica l and polic y issue s discusse d abov e - appropriate cutpoint s fo

r stringen t NO x controls , intermittent oi l us e an d catalys t life , ammoni ause , cos t

of controls , and lo w NO x burner s - ca n b e resolve d throug h appropriat e desig n an d operatio n o

f NO x contro l systems . In addition, advances in combustion controls may lead

to low NOx

levels without

the use of

catalysts. In order

to meet the goals of the Clean Air

Act of 1990, the NESCAUM region will need to achieve stringent Committee Draf

t 8 4/16/9 1P. 6 

### c . N0 X controls on gas turbines and other stationary sources. Therefore, the states expect to follow the development

of new control technologies and the ability to

further lower permitted NOx emissions. Vm . Bibliograph

y 1 . Champagne , D.L . January-February , 1988 . SC RCos t Effectiv e fo

r Smal l Ga s Turbines . Cogeneration . p.26-29 . 2 . Heck , R.M . e t

al . 1987 . Catalyti c Ai r

Pollutio n Controls-Commercia l Developmen

t o f Selectiv e Catalyti c Reductio n fo r NO x . Technica

l Pape r No . 87-52.3 , Englehar

d Industries . Ai r

Pollutio n Contro l Association . 3 . Northeas t

State s fo r Coordinate d Ai r

Us e Managemen t

Octobe r 1988 . BAC T Guideline. 4 . Potter , J . Craig . Decembe r 1987 . U.S . Environmenta

l Protectio n Agency , memo from J . Crai g Potter

t o Regiona l Administrator s I.

- X . Improvin g Ne w Sourc e Review Implementation . 5 . Suyama , K . 1985 . Operatin g Experienc e on SC RSystemfo

r Stea mGenerators . Mitsubishi Heavy Industries , Ltd. , Nagasak i Shipyar d an d Engin e Works , 1- 1 Akunoura

Machi , Nagasaki , Japan, . 6 . Thomas , Le e M. , Administrator , U.S . Environmenta l Protectio n Agency . Jun e 1986 . Reman d t o U S EP A Regio n X . o

f PS D Appea

l No* . 85-2 . Nort

h Count y Resourc e Recover y Associates . 7 . U.S . Environmenta

l Protectio n Agency . Jul y 1987 . Ne w Sourc e Performanc e Standard s fo

r Ga s Turbines , Titl e 4 0 Cod e of Federa l Regulation s Par

t 60 , Subpar

t GG , an d Appendi x A . 8 . Winkler , D.G . Septembe r 12,1985 . Selectiv e Catalyti c Reductio n an d C O Oxidize

r Process . IC S Cogeneratio n Workshop Series . Johnso n Matthey , Inc . 9 . Yasuyuk

i Nakabayash

i an d Ribiy aAbe . Apri l 1986 . Curren t Statu s o f SCRi n Japan . Research an

d Engineerin g Office , Therma l Powe r Development , Electri c Powe r Development

Company , Ltd. , Tokyo , Japa n 100 . 10. Documentation of

the Threshold

Limit Values and

Biological

Exposure Indices, 5th Edition, American Conference of Governmental

Industrial

Hygienists, Inc. 11. Journal

of Applied Toxicology. 1983 Vol

3, Number

6. P. 272-292 <Any other

updates to the bibliography? > Thi s recommendatio n wa s approve d b y th e NESCAU

M Boar d of Director s on ? Th e recommendatio n will be reviewe d ever y tw o year s an

d revise d wher

e appropriate . turbrecmd-rev-91 b

Committee Draf

t 9 4/16/9 1