Transcript
7/25/2019 Plant Emissions Reduction Pgm
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by Nathan Long
Muskingum River PlantMuskingum River Plant
Emissions ReductionEmissions Reduction
Programs Programs
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Precipitators Precipitators
Ohio Environmental Protection Agency (EPA) dictates opacity must bebelow 20! Other states may have di""erent regulations!
#nits $%&
Each unit has a 'oyestern precipitator!
*onsists o" $+ "ields powered by , trans"ormerrecti"iers!
Neundor"er voltage and rapper controls!Opacity averages between -%$2
#nit -
.esearch *ottrell / two boes!
Each bo has 10 recti"ied "ields!
Neundor"er voltage and rapper controls
Opacity averages approimately -!
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Precipitator Problems Precipitator Problems
#nits $%&
*asing leas allows moisture to enter precipitator creating high levels o"
sparing thus driving power levels down!
3rans"ormerrecti"iers "ailing more "re4uently than in the past!
.eaching end o" li"e5
Neundor"er controls aggresively ramp voltage bac up "ollowing spar
4uenching which may be shortening li"e o" trans"ormerrecti"iers!
Electrodes were "ailing causing grounds! .esolved by installing a heavier
gauge electrode wire!
Precipitators are undersi6ed so any upsets o"ten cause load curtailments to
stay under 20 opacity!
#nit -
Precipitators are oversi6ed! No real problems!
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Sulfur Trioxide (SO3) and Sulfur Trioxide (SO3) and mmonia (!"3)mmonia (!"3)
#lue $as %onditioning S&stem #lue $as %onditioning S&stem
#sed on units $%& (subcritical units)
7ecreases "lyash resistivity to improve collection o" ash in precipitators!
Advantageous when sul"ur content o" coal drops below 1!- lbs8btu!
9O1 system
8olten sul"ur stored in $00 ton tan (appro! +0 day capacity) at $&1 deg! * (2:0 deg!
;)!
9ul"ur pumped through steam <aceted lines to sul"ur burners!
9ul"ur gas passes through vanadium pentoide catalyst which accelerates the
natural process o" the chemical reaction to ensure at least :- o" the sul"ur dioide
is converted to sul"ure trioide!
$- w (20 =P)> 1+00 rpm process air blower / $- cmmin (-10 sc"m)
2!2 w (1 =P)> 1+00 rpm purge blower eeps piping and no66les clear when system is
out o" service!
+ in<ection probes distribute the 9O1 into the duct upstream o" precipitator!
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Sulfur Trioxide (SO3) and Sulfur Trioxide (SO3) and mmonia (!"3)mmonia (!"3)
#lue $as %onditioning S&stem #lue $as %onditioning S&stem
N=1 9ystem
#sed with 9O1 system to enhance ?collectibility@ o" the ash!
Anhydrous ammonia stored as a pressuri6ed li4uid in a bul storage tan!
3an e4uipped with 2 / $0 w heaters which vapori6es the ammonia!
Ammonia vapor passes through a regulating valve ($%- ppm) be"ore being
in<ected through + probes!
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Sulfur Trioxide (SO3) and mmonia (!"3)Sulfur Trioxide (SO3) and mmonia (!"3)
Problems Problems
9ul"ur 3rioide
8ust maintain proper insulation on steam <aceted sul"ur lines or sul"ur will
solid"y! Eperienced this on startups> had to heat lines with torches to get
sul"ur to "low! mproved insulation too care o" the problem!
3he sul"ur metering pumps are a submersible gear type pump with very
close tolerances! 3he pumps wear and eventually will not pump at which
time they have to be replaced and sent out "or re"urbishment! 3hey cannotbe repaired on site!
hen the system is shut down> the purge air blower must be in service or
"lue gas will come bac into the lines and plug the probes!
3he probes are buly and heavy and must be removed to be unplugged!
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Sulfur Trioxide (SO3) and mmonia (!"3)Sulfur Trioxide (SO3) and mmonia (!"3)
Problems Problems
Ammonia (N=1)*are must be taen not to over in<ect or it will "oul the precipitator!
Ammonia detection systems and alarms must be maintained around
the storage tan and in<ection sids to alert personnel o" any leas!
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%ontinuous Emissions Monitoring S&stem%ontinuous Emissions Monitoring S&stem
(%EMS) (%EMS)
All "ive units e4uipped with a redundant continuous emissions monitoringsystem!
8onitorsB
Opacity
9ul"ur 7ioide (9O2)
Nitrous Oide (NO)
*arbon 7ioide (*O2)
;lue gas sample is diluted with air 100B$ to etend li"e o" instrumentation andmae the system more reliable!
8onitors analy6e the gas sample and send raw data to a polling computer whichcalculates mass emissions rates!
3he *E89 technician per"orms daily checs o" the data be"ore sending on to AEP> *olumbus! 3he data is submitted to the Ohio Environmental Protection
Agency on a 4uarterly basis!Preventive maintenance is per"ormed on the e4uipment on a 4uarterly basis!
8onitors automatically calibrate daily!
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!ox Reduction $oals !ox Reduction $oals
#nits $% 2 8aintain NO Emission .ate under
CC: gcal (0!&& lbmbtu)
#nits 1%& 8aintain No Emission .ate under
&++ gcal (0!10, lbmbtu)#nit - 8aintain NO Emission .ate under
$0$ gcal (0!0+C lbmbtu) with 9*.
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Terminolog& Terminolog&
3heoretical air is the minimum air re4uired
"or complete combustion o" the "uel>
resulting in stoichiometric combustion! 9toichiometry (also called stoichiometric
ratio) is a term relating the actual air to the
theoretical minimum air re4uired to complete
combustion!
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Terminolog& Terminolog&
Excess air is the amount of air supplied for combustion
in "excess" of that theoretically required for complete
combustion.
This additional air is required because of imperfectionsassociated with the combustion process and the
practical limitation of providing the Three T's of
Combustion.
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Overfire ir Overfire ir
zone
zone !overfire air
fuelair mixture
in the overfire air to complete the
combustion process.
zone !# $ring in %&!% of total air
combustion air to burn fuel under
less than stoichiometric conditions.
zone # $ring in (%&)% of total
fuelair mixture
*econdary +urnace
,rimary +urnace
_______________________________________________________________________
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How OFA System Reduces NOx U1&2
+uel&rich combustion zoneThe reducing environment helps control fuel and
thermal -xThe lower pea/ flame temperature helps further reduc
the formation of thermal -x verfire air zoneThermal -x formation is limited due to lower gas and
flame temperatures
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How OFA System Reduces NOx
U3&4
+uel&rich zone0ithholding air causes the cyclones to be operated fuel&rich. 1s
a result2 C is produced within the cyclone. 3n the lower furnace
this C aggressively reduces already formed -x to -! in its
attempt to form C!.The lower pea/ flame temperature provides an additional
incremental reduction in -x. verfire air zone
Thermal -x formation is limited due to lower gas and flame
temperatures.
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Business Confidential 28
Application of Overfire Air
Co!ustion "one #toic$ioetr%
1&00&85 1&15
O'idi(in)*educin)
+ O ' , o r a t i o n * a t e
C O -
i s s i o n s
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1tmospheric -itrogen -x4!52 temp.
Thermal NOx Mecha!sm
Critical
Temperature
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!on S%R !Ox Reduction Problems !on S%R !Ox Reduction Problems
.educing atmosphere causedB Accelerated tube wastage in primary "urnace
=ad to "ind acceptable stoichiometric setting to limit wastage
9evere erosionloss o" re"ractory on "urnace "loor! Large amounts
o" molten iron pooled on the "urnace "loor at a higher "re4uency!
9u""ered numerous tap throughs!9tarted with silicon carbide re"ractory! Eperimented with other "orms
o" re"ractory! =igh alumina> - chrome re"ractory seems to hold up
best!
9evere pluggage in convection pass! Added + electric sootblowers
to eep area clean!
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Selective %atal&tic Reduction (S%R) Selective %atal&tic Reduction (S%R)
Degan operation in 8ay> 200-!Operates "rom 8ay $ through 9eptember 10!
ill be re4uired to operate year round beginning in 200:!
3here"ore> it was decided not to install bypass ducts and dampers!
3wo reactor boes (north and south)
9i6ed to hold "our layers o" catalyst! nitial operation is with two layers! 3hird layer is
to be installed in 9pring o" 200C! ;ourth layer is "or "uture use> perhaps "or mercuryremoval!
*atalyst supplied by =itachi America Ltd!
Plate type> titanium dioide (3iO2) carrier impregnated with tungsten trioide (O1)
and vanadium pentoide (2O-)!
C2 catalyst modules per layer (: wide F , deep grid)!
nitial guarantee is "or $+>000 hours o" :0 NO removal be"ore third layer is added!
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Selective %atal&tic Reduction (S%R) Selective %atal&tic Reduction (S%R)
3wo dra"t booster "ans were installed to overcome the new 9*. system pressure drop!
Located between the precipitator and the stac
=owden ?aria@ constant speed> single stage> hori6ontal> aial "low!
#tili6es variable pitch blades "or "low control! Dlades are hydraulically controlled!
mpeller diameter is 1!C meters ($&+ inches)!
Operates at ,:- rpm!
Ammonia vapor system
#rea brought in by truc
7issolved in water to a &0 by weight solution in a mi tan!
=eated to 2$0 deg * (&$0 deg ;) at 2,!$2 gscm (&00 psig) by steam in ahydrolysis reactor (hydroli6er)! 9team comes "rom high pressure turbineehaust!
Produces ammonia and carbon dioide!
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Selective %atal&tic Reduction (S%R) Selective %atal&tic Reduction (S%R)
Ammonia vapor system (continued)9pent solution (recycle G 1 solution) is continuosly withdrawn "rom the
hydroli6er> sent through an economi6er and then to a recycle storage tan!
t is then used in the mi tan to mi batches o" urea solution!
Haseous ammonia and carbon dioide leave the hyrdoli6er vessel and
"eeds a dilution sid upstream o" each catalyst bo! Each sid has an
ammonia "low control valve that meters the correct amount o" ammonia toachieve desired NO reduction!
3he rate o" ammonia generation in the hydroli6er is controlled to maintain
constant mani"old pressure at the dilution sids!
hen the ammonia vapor gets to the dilution sid> it is diluted and mied
with air "rom dilution air "ans! t is then in<ected into the duct through a grid
o" pipes upstream o" the catalyst!
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Ammo!a"o"#emadTMAmmo!aAmmo!a""oo""#emad#emadTMTM
To
*C6
1mbien
1ir *team
7ry*torage
7emin 0ater
,reheater
M!x Ta$
Hydroly%er
Flash
Searator
'lo
Selective %atal&tic Reduction (S%R)Selective %atal&tic Reduction (S%R)
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Selective %atal&tic Reduction (S%R)Selective %atal&tic Reduction (S%R)
Problems Problems
Large particle ash (LPA)Large particles o" ash carried through the ductwor settles out on the screensabove the catalyst! As it accumulates it blocs o"" the gas path and "iner ashthen builds up as well!
*reates a di""erential increase through the catalyst "rom G -0 gs4m (2 incheswater) to G :+!- gs4m (1!, inches o" water) at which time the unit has to bebrought o"" line "or cleaning o" the catalyst!
At :+!- gs4m (1!, inches o" water) di""erential> the catalyst chamber is -0bloced!
*reates a problem "or the booster "ans to maintain desired economi6er outlet pressure!
*urrently designing a hopper to install under the economi6er to catch thelarge ash be"ore it reaches the catalyst boes!
8ay incorporate a screen to catch and direct the ash to the hopper!
Plan to install hopper in 9pring o" 200C!
(2) M*+,-.*
1/002//( 13321 .M8.( lb"9btu-x
x!t +as Tem& M!!mum
3/1 #+ F
-x 8.(! lb"9btu
CE9 6ight
CE9 :ef t
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Plant 'nformation (P') Screen Plant 'nformation (P') Screen
1/002//( 13321 .M
-orth *C6 6eactor
:ayer ;
:ayer
,recipitator
From coom!%er
$ooster +an
+as -let
(;<.=(
7E> +
+AS OUT4T
;8.);7E> +
-orth 1ir ?eater
!.)8
AH #!55,
3n. ?!8
:ayer !
NH3 -6ect!o
:ayer @
*outh *C6 6eactor
:ayer ;
:ayer
,recipitator
From coom!%er
$ooster +an
+as -let
(;!.@(
7E> +
+AS OUT4T
;8@.);7E> +
*outh 1ir ?eater
;.;=
AH #!55,
3n. ?!8
:ayer !
NH3 -6ect!o
:ayer @
%.<) 3n. ?!8
%.== 3n. ?!8
8.(
8.(!
lb"9btu-x
-x -x
-x
lb"9btu
8.== lb"9btu
8.=8 lb"9btu
( lb"hr
=8 +
8 psi
Ander 6angelb"hr
psi
=; +
!< 1mps
;( '
!(@ 1mps
@@ '
&;.);3n. ?!8 &=.=% 3n. ?!8
8.8 ).<' 6emoval ' 6emoval
(;<.<@
(;!.!8 7E> +
7E> +7E> +
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*! lb"9btu2,33
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-x Trends
8.
8
8.!3/,/) ,,9
Calc. *; :eaving *C6
-orth *outh
-orth*outh
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#lue $as esulfuriation S&stem #lue $as esulfuriation S&stem
or has begun to build a "lue gas desul"uri6ation systemon unit -! Pro<ect has been postponed to an in service dateo" $21$20$0!
*hiyoda design "rom 'apan
7i""ers "rom the conventional spray tower scrubber in that it
uses a <et bubbling reactor which sparges the "lue gas into alime slurry bath where $00 o" the "lue gas reacts with thelime slurry be"ore bubbling o"" the top and leaving thereactor to the stac!
;oundations have been completed "or the reactor and a new
2-2 meter (,2+ "oot) high stac!
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#lue $as esulfuriation S&stem #lue $as esulfuriation S&stem
7esigned to provide su""icient limestone slurry to absorb:, 9O2 "rom the "lue gas!
Allows the burning o" $$!1 mgm 9O1cal (C!- lb 9O28btu) coal
.edundant $00 ball mill systems capable o" grinding &0tons o" limestone per hour!
,:- w ($200 hp)> & motors> hori6ontal> wet> with steel grindingballs!
9*. booster "ans will be replaced with two =owden> -0capacity aial "ans> each rated at G $$!2 mw ($->000 hp)!
Hypsum will be produced at G C1 tonshour and will be
dewatered by one vacuum belt "ilter be"ore being land"illed!
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%onceptual Model for Scrubber %onceptual Model for Scrubber
*et +ubbling*et +ubblingReactor Reactor T&pical Spra&T&pical Spra&
To,er To,er
Gas is sparged
into Liquid
Liquid is sprayed to
into Gas
.et Bu!!lin) /a%er
*eservoir
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