design & operation of building on experience

Design & Operation of Design & Operation of UU22AATMTM

Building on ExperienceBuilding on Experience

Jeffery E. FisherWahlco, Inc.

H. James Peters

Hamon Research-Cottrell/Wahlco Inc.

Electric Utilities Environmental ConferenceTucson, ArizonaJanuary 2002

Feb-02

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UU22AATM TM BackgroundBackground

U2ATM (urea to ammonia) is a patented system to meet ammonia needs with reduced risks

Highest ammonia risks:• Shipping • transfer • storage

Urea is a benign material• Safely transported, transferred and stored• Readily available as bulk commodity chemical• Urea is 56% ammonia (equivalent) • Economical alternative to aqueous ammonia

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EC&C (Dr. Spencer, Dr. Cooper) licensors

Strong technical supportU.S. patents 6,077,491; 6,322,762

HRC/Wahlco AllianceOffices on both coastsFlexible execution

EC&C, Wahlco and Hamon Research-Cottrell

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PROTOTYPESPROTOTYPES

Phase I and IIPrototype Reactors

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Process characteristicsOnce through processIndirect heat exchangeClosed water balance Reactor at equilibriumPredictable reaction dynamicsExperience shows no reactor fouling due to side reactions

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Ammonia Generation from Urea:

NH2CONH2 + (x)H2O

NH2COONH4 + (x-1)H2O

2 NH3 + CO2 + (x-1)H2O•Urea hydrolyzes to carbamate•Carbamate dissociates to ammonia and carbon dioxide•Reaction is reverse of urea synthesis•Generates only ammonia, water, carbon dioxide

Thermal Hydrolysis of UreaThermal Hydrolysis of Urea

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FormaldehydeFormaldehyde

AES/Alamitos Results from January 2000:No increase in reactor concentration ~1000 hours operation

• Feed 40% urea solution @ 0.2% formaldehyde = 1000 mg/l • Reactor liquor average from 5 samples = 1117 mg/l

HCHO is driven off in reactor• 0.4 ppm increase in HCHO upstream of catalyst over baseline• Increase agrees with material balance for ~0.2% HCHO in urea

SCR catalyst provides catalytic oxidation of HCHO• 0.02 ppm HCHO measured at stack after catalyst (>95%)

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UU22AATMTM Process ControlProcess Control

Simple process control

Hydrolysis ReactorUrea Solution

PLC

NOxAnalyzer

Pressure and Flow control

Heat control

Level control

Ammonia Product Gas

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PLC

NOxAnalyzer


Heat control

Level control

Ammonia Product Gas

Urea solution is dissolved in DI water at 40 to 60 wt%

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PLC

NOxAnalyzer


Heat control

Level control

Ammonia Product Gas

Solution is pumped to reactor to maintain constant level

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PLC

NOxAnalyzer


Heat control

Level control

Ammonia Product Gas

Heat is added to initiate and control endothermic hydrolysis reaction

Reaction products go into reactor liquid which then releases:

CO2

NH3, H2O

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PLC

NOxAnalyzer


Heat control

Level control

Ammonia Product Gas

Reactor is maintained at constant pressure

by regulating heat input

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PLC

NOxAnalyzer


Heat control

Level control

Ammonia Product Gas

Product gas piping is maintained at temperature above carbamate formation and water condensation temperatures

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PLC

NOxAnalyzer


Heat control

Level control

Ammonia Product Gas

Controlled product gas stream can be used directly

or diluted with air at ammonia flow control unit

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Start UpStart UpReactor contains equilbrium liquid from prior operation

Approximately 15%-20% urea or carbamateApproximately 3% ammonia

Heating mode in stages to achieve 250ºF and 40 psig under temperature controlMode changes to injection under pressure control at 80 psig set pointAbout 30-45 minutes from cold condition, 0-15 minutes from idles condition

Vapor Phase NH3 Inventory

Pressure

Level

NH3

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Normal Operation and RampingNormal Operation and RampingInjection mode

Constant pressure and levelTemperature and steam varyVapor inventory (~1 minute) instantly availableChange in heat input adjusts reaction rate to maintain reactor pressure (1 ºF change yields ~5% change in rate) Level control maintains urea solution (~3 hours inventory)


Pressure

Level

NH3

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Normal ShutdownNormal Shutdown

Normal shutdown NH3 continues to processSteam and feed pump shutoffReactor cools (due to endothermic reaction) and enters standby mode


Pressure

Level

NH3

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UU22AATMTM ProjectsProjects

Allegheny Energy/Harrison Station 3,700 lb/hrAllegheny Energy/Pleasants Station 1,800 lb/hrAES/Alamitos Station 260 lb/hrAES/Huntington Beach Station 340 lb/hrDTE Energy/Monroe 10,000 lb/hrConstellation Energy/Wagner Station 460 lb/hrIST/Dominion Energy/Kauai 30 lb/hr

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Experience ReviewExperience Review

AES/Alamitos400:1 scale-up from pilotBoiler load following and NOx ComplianceComparison to 29% aqueousFormaldehyde analysisReactor liquid and residual materials analysis

• Predictable based on urea trace materials

• No side reactions• Confirmed materials of construction

AES Huntington BeachSmooth start-up One day to automatic operation Carbamate formation and heat tracing4000 operating hours to date

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Load FollowingLoad Following

Process easily follows boiler load variations AES Alamitos hourly averaged dataApproximately 10:1 turndown over typical daily cycling operation

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Comparison of Prototype Operation Comparison of Prototype Operation to 400 lb/hr systemto 400 lb/hr system

Temperature from Reaction rate

200

220

240

260

280

300

320

340

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0

Specific reaction rate

Tem

pera

ture

- de

g F

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Allegheny Energy SupplyAllegheny Energy Supply

Harrison and PleasantsHarrison and Pleasants

The Harrison project was the first U2A commercial award and represents “new technology” risk for Allegheny.Phase I operations were planned to identify any issues with process design or procedures well in advance of May 2002 SCR start up.Phase I deemed successful by mid September 2001.Allegheny Energy/Harrison operation builds on U2A experience at AES/Alamitos and AES/Huntington Beach.

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UU22AATMTM –– Allegheny HarrisonAllegheny HarrisonAllegheny Energy Supply Harrison Station

3700 lb/hr ammonia from ureaSupply to 6 SCRs on 3 x 600MWThree 50% reactors

ScopeUrea dry storage, handlingUrea solution preparationHydrolysis reactorsAmmonia flow control units

ScheduleFirst 1850 lb/hr reactor

• operational in September 2001Unit #1 start up May 2002

Test ResultsExceeded rating by >20%Met load-following and safety goals

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Harrison Phase IHarrison Phase IProduction of Ammonia (lb/hr) vs. Temperature (F)

Data taken at/near equilibrium during manual operationFull production temperature within a few degrees of predictionReactor capable well in excess of nominal rating

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Instantaneous Ramp UpInstantaneous Ramp Up

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Normal ShutdownNormal Shutdown

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Experience ReviewExperience Review

Allegheny Energy SupplyHarrison Phase I

Confirmation of process scale up• 2000:1 from pilot• 5:1 from AES

Confirmation of start up/shutdownHeating characteristics for tube bundle

• Instantaneous ramping

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What’s Next?What’s Next?

Allegheny Energy SupplyHarrison Phase IIPreparation for May 2002

Start Up – Unit #1 SCRBalance of delivery/constructionUrea supply and logistics

• Urea supplier selection Urea dry storageAutomated batch dissolvingTwo reactor operation

• One operating, one standby

Other U2A start ups – May 2002DTE/Monroe – one unitConstellation/Wagner

WAHLCO, INC.

design & operation of building on experience

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