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SCR and HAPs Converters for Stationary Engines
MARAMA / ICAC WebinarNovember 9, 2012
Wilson ChuJohnson Matthey
Presentation Outline
• Catalysts for NOx, HC, CO and HAPs• Catalytic Converter Designs• HAPGuard Exhaust Monitor• SCR Systems for NOx• Orange County Sanitation District Digester Gas
SCR and Oxidation System Case Study
Catalysts and Catalytic Converters
• 3-Way NSCR, 2-Way Oxidation, SCR• Metallic or Ceramic• Coated or Extruded• Round, Rectangular or Square
Catalysts
Converter Designs
Modulex C Modulex BDualOx
Catalytic ConverterFeatures and Benefits
Features Benefits
Modular Design Low cost option
Catalyst Hatch Easy access for element cleaning or replacement
Construction Carbon Steel or Stainless Steel
Silencing Critical Grade (25-30 dBA)Hospital Grade (30-35 dBA)
Low Back Pressure Design
4 to 5” w.c. un-silenced14” w.c. with silencer
DualOx Converters
DualOx Converter Silencer
HAPGuard™ Exhaust Monitor
� RICE NESHAP compliance� Monitors the system and alerts the operator
if the pressure drop across the catalyst is not within
� ± 2” w.c. at 100% load� Monitors the temperature and alerts the
operator if :Rich Burn: 750°F < T (catalyst inlet) < 1250°FLean Burn: 450°F < T (catalyst inlet) < 1350°F
� Engine tested� Battery backup� LCD display� Removable memory, 5 years data storage� Suggested list price - $2,500
SCR Systems
SCR
• Selective Catalytic Reduction• Controlled urea injection• Capable of >90% NOx reduction• Concerns:
– Urea decomposition and distribution– Operating temperature
SCR System
SCR System Components
• Oxidation Catalyst or DPF, if required• Mixing Duct• Injection Lance/Nozzle• Urea Injection System• Temperature Probe• SCR Housing • SCR Catalyst• Options - Burner(s), NOx Analyzer, Insulation,
Differential Pressure Measurement, Pressure Blowers)
SCR Housing and Catalyst(Cutaway View)
Mixing Duct
Urea Connection
Compressed Air Connection
Internal Static Mixer
Injection Lance and Static Mixer
Urea Injection Control System
• PLC-Based Control• Touch Screen HMI• Precise Injection Dosing
Pump• Urea or Aqueous
Ammonia• Remote Monitoring• Data logging Options• AC Option• Heater Option• Enclosure Options
SCR Applications
Natural Gas Drilling Rigs in WY
Challenge:• Freezing temperatures• Dynamic load changes• Portability
Hotel & Casino in CA
Challenge: Reliability (off grid)
Staten Island Ferry (John Noble)
Challenge:• Small
space• 2 ppm
max. NH3slip
University of Central Florida
Challenge:• Small space• 3 ppm max. NOx• Sound Attenuation
Orange County Sanitation DistrictDigester Gas SCR and Oxidation
System
SCAQMD Rule 1110.2Technology Demonstration(slides courtesy of OCSD, Lisa Rothbart)
Demonstration Engine
• 3471 Hp lean burn Cooper Bessemer V12 (1992)
• 2500 kW generator
• HRSG• NOx and CO
CEMS
Digester Gas Composition
Min. Max. Avg.(%) (%) (%)
CO2 25.5 40.1 33.9CH4 53.7 62.6 58.7N2 0.9 5.1 2.2O2 0.1 1.4 0.6
Sulfides in the Digester Gas
CompoundCarbon Bed Inlet
Min. Max. Avg.(ppmv) (ppmv) (ppmv)
Hydrogen Sulfide 14.690 31.870 26.381Carbonyl Sulfide .010 .028 .019Methyl Mercaptan .048 .081 .062Ethyl Mercaptan .189 .304 .258Dimethyl Sulfide .006 .017 .012Carbon Disulfide .004 .009 .006n-Propyl Thiol .454 .679 .581iso-Propyl Thiol .214 .416 .344Dimethyl Disulfide ND ND NDIsopropyl Mercaptan .250 .250 .250n-Propyl Mercaptan .320 .320 .320
Siloxanes in Digester Gas
CompoundCarbon Bed Inlet
Min. Max. Avg.(ppmv) (ppmv) (ppmv)
Hexamethyldisiloxane (L2) <MDL <MDL <MDLHexamethylcyclotrisiloxane (D3) .010 .017 .012Octamethyltrisiloxane (L3) .010 .019 .014Octamethylcyclotetrasiloxane (D4)
.369 1.6 0.704
Decamethyltetrasiloxane (L4) .073 .170 .121Decamethylcyclopentasiloxane (D5)
1.300 14.000 5.371
Total Siloxanes .919 15.700 5.452
Pre-Engine Digester Gas Cleaning
• Single fixed bed of activated carbon by Applied Filter Technology
• 9900 lbs capacity
Catalytic Oxidizer/SCR System
SCR Catalyst
Urea Injection
Catalytic Oxidizer
SCR Urea Injection Control Paneland Urea Tank
Emission Levels Achieved, ppmv
Pollutant Engine Exhaust
Stack Outlet Average
Average % Conversion
Rule 1110.2 limit
NOx 31 7.2 (best was 0.8)
77% (best was 97%)
11
CO 452 7.5 98% 250
VOC 97 3.6 96% 30
