Worldwide Pollution Control Association

Worldwide Pollution Control Association IL Regional Technical Seminar September 13-15,211 Visit our website at www.wpca.info

Babcock Power Inc. The Future Of Coal Fired SCRs In A Carbon Capture World 211 WPCA IL September 13, 211

Introduction Future Coal Plants Integrated Gasification Combined Cycle (IGCC), oxy-fuel combustion or postcombustion fuel gas CO 2 capture With exception of purification of oxy-fuel derived flue gas, all will require AQCS systems Competing against gas turbines firing natural gas or coal synthesis gas Achieve 2 to 5 ppm outlet NO x What will it take to match this level with coal fired units?

Introduction Present State Of Art Low NO x burners with Selective Catalyst Reduction (SCR) 9% to 92.5% NO x reduction in SCR.3 lb/mbtu (22 ppmvd) to.4 lbs./mbtu (29 ppmvd) outlet NO x 2 ppm ammonia slip Effect on downstream equipment Sale of flyash Assuming a lack of economical method of removal of ammonia from flyash Condensable PM

Necessary Input Values Of The MEA Process PM [mg/nm 3 ] NO X as NO 2 [mg/nm3] SO X as SO 2 [mg/nm 3 ] grs/scf ppm ppm lb/mmbtu lb/mmbtu lb/mmbtu 13. BImSchV (FRG 24) < 2.12.25 < 2 (solid fuel) 97.4.135 < 2 7.135 input values of the MEA - < 15.95.2 < 3 (NO 2 ) 14.6.2 < 3 1.5.2 Process Daily average values for plants with thermal capacity of > 3 MW

NO x Reduction Requirements NO x Reduction required to Meet 2 and 5 ppm Outlet NO x SCR NOx Reduction SCR NOx Reduction Coal Type Wall-Fired Boiler Tangential Fired Boiler Baseline NOx, ppm 18 13 PRB-Lignite Low - Medium Sulfur Coal High Sulfur Coal Overall Reactor Reduction 97.22% 96.15% Outlet NOx, ppm 5 5 Overall Reactor Reduction 98.89% 98.46% Outlet NOx, ppm 2 2 Baseline Nox 285 215 Overall Reactor Reduction 98.25% 97.67% Outlet NOx, ppm 5 5 Overall Reactor Reduction 99.3% 99.7% Outlet NOx, ppm 2 2 Baseline Nox 36 285 Overall Reactor Reduction 98.61% 98.25% Outlet NOx, ppm 5 5 Overall Reactor Reduction 99.44% 99.3% Outlet NOx, ppm 2 2 Source: Advanced SCR Design Assessments for NO x Less than 5 ppm, by R. Himes et. al.

The 95% SCR More catalyst can only do so much If NO x is not there to react, NH 3 will slip through = distribution induced slip Higher removals through better mixing The more uniform the NH 3 /NO x profile, the greater the catalyst performance and the lower the distribution induced slip Maximum design NH 3 /NO x standard deviation to be 2 3 % Current BPEI test data for NH 3 /NO x standard deviation are < 2% Actual test results show 94.2% removal with NH3/NOx standard deviation of <2% yield undetectable slip for new catalyst (Based on catalyst design of 2 ppm slip expected to be met)

Limitations On High NO x Removal Temperature, velocity, and NH 3 /NO x distribution Key limitation is NH 3 /NO x distribution NOx and ammonia become progressively more non-uniform as it passes down through catalyst layers 1% 3 95% 9% 25 NOx Reduction Efficiency 85% 8% 75% 7% 65% 2 15 1 Ammonia Slip (ppm) 6% 55% 5 5%.6.7.8.9 1 1.1 NH3:NOx Ratio Source: Enhanced Ammonia Distribution for Maximum SCR Performance, R. Sigling et. al.

Effect Of Increasing NO x Removal Catalyst Volume - Distribution Source: Selective Decomposition of Ammonia for Coal-fired Power Plant Selective Catalytic Reduction Application by J. Bertole et. al.

Impact Of RMS On NH 3 Slip Source: FERCO Engineering

Mixing System Results NH3/NOx Standard Deviation (%) 1 9 8 7 6 5 4 3 2 1 Reactor A 1% Bit. Reactor A PRB Blend Reactor B 1% Bit. Reactor B PRB Blend 25 275 3 325 35 375 4 425 45 475 5 525 55 LOAD (MW G )

Effect Of Increasing NO x Removal Rapid increase in catalyst volume Increase in cross-sectional area Increased difficulty in achieving uniform distribution Increase the number of catalyst layers More expensive catalyst management Possible requirement to replace more than one layer at each outage Increased pressure drop

NO x Reduction With Two Reactors 9% NOx Removal In First SCR Reactor SCR NOx Reduction SCR NOx Reduction Coal Type Wall-Fired Boiler Tangential Fired Boiler Baseline Inlet NOx, ppm 18 13 NOx at Outlet of First Reactor, ppm 18 13 PRB-Lignite Second Reactor Reduction 72.22% 61.54% Outlet NOx, ppm 5 5 Second Reactor Reduction 88.89% 84.62% Outlet NOx, ppm 2 2 Baseline Inlet NOx, ppm 285 215 NOx at Outlet of First Reactor, ppm 28.5 21.5 Low - Medium Sulfur Coal Second Reactor Reduction 82.46% 76.74% Outlet NOx 5 5 Second Reactor Reduction 92.98% 9.7% Outlet Nox 2 2 Baseline Inlet NOx, ppm 36 285 NOx at Outlet of First Reactor, ppm 36 28.5 High Sulfur Coal Second Reactor Reduction 86.11% 82.46% Outlet NOx 5 5 Second Reactor Reduction 94.44% 92.98% Outlet NOx 2 2

Multi-Stage Mixing Two Reactors In Series Method A First reactor has low outlet ammonia slip Second reactor is preceded by second ammonia injection Advantages Additional injection grid allows for more tuning of second reactor Conventional (but more challenging) ammonia control for both reactors Some adjustment can be made on NO x removal split between the two reactors Disadvantages More expensive and complicated ammonia and control systems Longer mixing length required for entrance to second reactor Probably not possible to construct as a retrofit Additional pressure drop from additional mixing and ductwork

Multi-Stage Mixing Two Reactors In Series Method B First reactor has high outlet ammonia slip Second reactor is preceded only by flue gas mixing Advantages Less catalyst in first reactor Less expensive / complicated ammonia system Single conventional ammonia control system Disadvantages No ammonia distribution tuning possible for second reactor More challenging flue mixing required for second reactor Probably not possible to construct as a retrofit Additional pressure drop from additional mixing and ductwork

Advanced Catalyst Design Ammonia Slip Destructive Catalyst NO x catalyst followed by separate ammonia destructive catalyst Minimize NO x catalyst volume while maintaining low ammonia slip Requires selective catalyst that minimizes SO 2 conversion Requires selective catalyst that minimizes ammonia conversion back to NO x May require two catalyst management plans

Advanced Catalyst Design Selective Destructive Of Ammonia (Cormetech) NO x catalyst that selectively reduces areas of high ammonia to smooth out NH 3 /NO x SO + 2 NH + O SO + N + 3H O 3 3 2 2 2 2 Special first catalyst layer Minimizes catalyst volume May require two catalyst management plans

Increase SCR Performance Through Reliability Improvements Operational Experience Increase reagent injection redundancy by tying Unit 1 & Unit 2 NH 3 injection systems together Aggressive equipment maintenance programs Continuous system condition monitoring On-line catalyst vacuuming and SAH water wash

Mixing System Improvements Operational Experience In-house verification of ammonia injection as needed based upon changes in: Reactor de-no x performance Fuel quality Ammonia-in-ash SAH ΔP

Low Temperature SCR Operation Operational Experience Real-time NH 3 MIT (Minimum Injection Temperature) calculated from measured flue-gas parameters using ABS dewpoint curves Increased SCR performance at low-load operation Eliminates catalyst recovery periods Reduces Secondary Air Heater (SAH) deposition

Optimal Control Strategy Operational Experience Real-time ammonia injection flow control based upon: SCR outlet NO x vs. NO x outlet setpoint SCR outlet NH 3 slip Real-time MIT (Minimum Injection Temperature) Permissives and trips on each reactor Real-time catalyst ΔT monitoring Real-time ABS monitoring Parallel reactors are controlled independently

Improved Catalyst Inlet Ammonia-To-NO x Ratio Increase mixing during initial design at cost of pressure loss Current designs have obtained less than 1 % RMS during testing Use mixing system design with active controls Designs must be reliable and able to alert operators

Design Of <2% RMS Mixing System Babcock Power studied the effect of individual mixings during model study Model study results verified with multiple field tests Mathematical optimization performed in model and field scale confirming design 4.2-.4 5.-.2 6 -.2-. 7 -.4--.2 8 9 1 A B C D E F G H I J K 1 2 3 c c DNH 3 / NOx

System Requirement For Enhanced Control Mixing system design is predictable and repeatable Model study accurately provides full scale injector influences One to one correspondence of NO x measurement to injection point Furnace NO x SCR inlet influence controlled

Valve Influence Test And Optimization Test Constant ammonia flow Test each valve individually Plot results for each valve Create influence coefficient matrix Computer optimization program Linear equations Ammonia flow constraints Review and adjust valves

Injector Influence: Coal-Fired 4 MW SCR Reactor * VARIATION OF CATALYST OUTLET NOx CONCENTRATION VARIATION OF CATALYST OUTLET NOx CONCENTRATION VARIATION OF CATALYST OUTLET NOx CONCENTRATION (ppm @ 3% O2) (ppm @ 3% O2) (ppm @ 3% O2) Ammonia Injection Ammonia Injection Ammonia Injection Distribution % 1% % % % % Distribution % % % % % % Distribution % % % % % 1% 73 #/hr 73 #/hr 72 #/hr #6 #5 #4 #3 #2 #1 #6 #5 #4 #3 #2 #1 #6 #5 #4 #3 #2 #1 Inlet Flue Gas Duct Location Inlet Flue Gas Duct Location Inlet Flue Gas Duct Location 45 39 9 179 32 369 377 375 385 45 35 312 229 126 129 26 275 332 45 41 415 414 391 344 182 94 72 4 35 3 25 2 15 1 5 114 123 116 82 155 17 14 126 217 225 182 191 297 294 265 268 364 39 372 397 367 397 366 NOx Probe394 379 385 384 381 394 4 399 396 4 38 36 34 32 3 28 26 24 22 2 18 16 14 12 1 8 6 4 4 35 3 25 2 15 1 5 331 329 345 35 33 32 343 351 239 253 312 36 192 229 254 25 191 239 24 31 286 324 281 NOx Probe315 263 32 322 316 32 322 342 342 35 34 33 32 31 3 29 28 27 26 25 24 23 22 21 2 19 18 17 16 15 14 13 4 35 3 25 2 15 1 5 49 49 42 41 411 412 47 415 412 48 49 415 39 365 372 384 325 215 277 157 23 134 238 NOx Probe168 146 118 98 112 18 111 94 11 4 38 36 34 32 3 28 26 24 22 2 18 16 14 12 1 8 5 1 15 2 25 3 35 4 45 5 5 1 15 2 25 3 35 4 45 5 5 1 15 2 25 3 35 4 45 5 Reactor Platform and Test Probe Location Reactor Platform and Test Probe Location Reactor Platform and Test Probe Location BBP Contract #: Project Name: Unit: Reactor: 119 AEP Big Sandy 2 R1 Sandy R1 7173 Test Date: Test End 216 Test: Test Start Time: Time: Big VI2 Valve 5 7/17/3 252 Test Drescription: Full Load Valve Influence Valve 5 Test - ppm: 282 % Removal: 3 Avg Outlet NOx Std Deviation: 99.5 BBP Contract #: Project Name: Unit: Reactor: 119 AEP Big Sandy 2 R1 Sandy R1 7173 Test Date: Test End 2247 Test: Test Start Time: Time: Big VI2 Valve 3 7/17/3 2233 Test Drescription: Full Load Valve Influence Valve 3 Test - ppm: 284 % Removal: 29 Avg Outlet NOx Std Deviation: 5.2 BBP Contract #: Project Name: Unit: Reactor: 119 AEP Big Sandy 2 R1 Sandy R1 7173 Test Date: Test End 22 Test: Test Start Time: Time: Big VI2 Valve 1 7/17/3 2144 Test Drescription: Full Load - Valve Influence Valve #1 Test ppm: 285 % Removal: 29 Avg Outlet NOx Std Deviation: 115.4 VARIATION OF CATALYST OUTLET NOx CONCENTRATION (ppm @ 3% O2) Ammonia Injection Distribution 1% % % % % % 735 #/hr #6 #5 #4 #3 #2 #1 Inlet Flue Gas Duct Location VARIATION OF CATALYST OUTLET NOx CONCENTRATION (ppm @ 3% O2) Ammonia Injection Distribution % % 1% % % % 78 #/hr #6 #5 #4 #3 #2 #1 Inlet Flue Gas Duct Location VARIATION OF CATALYST OUTLET NOx CONCENTRATION (ppm @ 3% O2) Ammonia Injection Distribution % % % 1% 1% % 718 #/hr #6 #5 #4 #3 #2 #1 Inlet Flue Gas Duct Location 45 4 35 3 25 2 15 1 5 44 95 98 93 97 89 143 15 116 117 183 217 216 169 185 348 316 298 275 287 393 393 386 45 384 397 384 48 392 NOx Probe419 387 389 382 393 46 398 45 398 49 419 4 38 36 34 32 3 28 26 24 22 2 18 16 14 12 1 8 6 45 4 35 3 25 2 15 1 5 348 321 32 333 338 37 287 291 327 337 22 225 242 294 291 117 173 221 236 236 131 212 184 24 239 3 281 325 284 NOx Probe32 28 266 298 321 321 34 32 324 343 349 34 33 32 31 3 29 28 27 26 25 24 23 22 21 2 19 18 17 16 15 14 13 12 45 4 35 3 25 2 15 1 5 396 389 392 412 412 411 4 42 418 417 49 396 394 416 414 375 367 347 376 377 312 147 286 185 259 152 232 141 236 NOx Probe17 67 12 114 18 116 56 92 15 1 15 4 38 36 34 32 3 28 26 24 22 2 18 16 14 12 1 8 6 5 1 15 2 25 3 35 4 45 5 Reactor Platform and Test Probe Location 5 1 15 2 25 3 35 4 45 5 Reactor Platform and Test Probe Location 5 1 15 2 25 3 35 4 45 5 Reactor Platform and Test Probe Location BBP Contract #: Project Name: Unit: Reactor: 119 AEP Big Sandy 2 R1 BBP Contract #: Project Name: Unit: Reactor: 119 AEP Big Sandy 2 R1 Test: Test Date: Test Start Time: Test End Time: Big Sandy R1 7173 VI2 Valve 4 7/17/3 2255 239 Test: Test Date: Test Start Time: Test End Time: Big Sandy R1 7173 VI2Valve 6 7/17/3 2117 2131 Test Drescription: FullLoad Valve Influence Test - Valve 4 Test Drescription: Full Load Vlave Influence Test - Valve 6 Avg Outlet NOx ppm: % Removal: Std Deviation: 279 3 49 Avg Outlet NOx ppm: % Removal: Std Deviation: 287 28 113.2 * Benes & Erickson, Electric Power 25 BBP Contract #: Project Name: Unit: Reactor: 119 AEP Big Sandy 2 R1 Sandy R1 71173 Test Date: Test End 2225 Test: 2 Test Start Time: Time: Big VI2 Valve 7/17/3 2211 Test Drescription: Full Load Valve Influence Valve 2 Test - ppm: 276 % Removal: 31 Avg Outlet NOx Std Deviation: 17.2

Automatic Control Example 18 MW gas fired single unit Poor ammonia flow control at non-design low injection rates Solution enhanced ammonia control Limited number of NH3 injectors Clearly defined influence fields Modified with additional outlet NO x meter for two feedback loops Installed in summer 25 Extended time between injection point tune ups

Automatic Control Example

Summary Meeting 2 5 ppm Outlet NO x Outlet Values can be met with multiple reactors but at substantial cost Alternate catalyst technologies can meet this level of performance but are under development Outlet NO x levels of 2 5 ppm are achievable with additional mixing and controls

Babcock Power would like to thank Wayne Whitaker, Duke Energy, for his contribution to and support of this work Thank You DISCLAIMER The contents of this paper contain the views and analyses of the individual authors only. The paper is offered to chronicle developments and/or events in the field, but is not intended and is not suitable to be used for other purposes, including as a professional design or engineering document. Babcock Power Inc., its subsidiaries and employees, make no representations or warranties as to the accuracy or completeness of the contents of this paper, and disclaim any liability for the use of or reliance upon all or any portion of the contents of this paper by any person or entity.