state of practice for sncr robert j. schreiber, jr. schreiber, yonley & associates research...
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State of Practice for SNCRState of Practice for SNCR
Robert J. Schreiber, Jr. Schreiber, Yonley &
Associates
Research Conducted for thePortland Cement Association
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Project TasksProject Tasks
Task 1: Literature Search Task 2: Terminology / Methodology Task 3: Identification of SNCR Reagents Task 4: Regulatory Consideration and
Applicability of SNCR Task 5: Current State of Practice for SNCR Use Task 6: Current State of Practice for SNCR
Installation Task 7: Experience in Other Industries
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Task 1: Literature SearchTask 1: Literature Search
PCA provided summary– Search terms
SNCR or Selective Non-Catalytic Reduction; and
Ammonia / Urea / Reagent; andOxide / Emission / Pollutant; 2000 – 2007 publish date
– SYA requested specific titles
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Task 2: Terminology / Task 2: Terminology / MethodologyMethodology
Terminology:– NOx Formation
Thermal NOx Prompt NOx Fuel NOx Feed NOx
– Amidogen ion (NH2 amine radical)– Reducing Reagents
Ammonia– Anhydrous– Aqueous
Urea Biosolids
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Task 2: Terminology / Task 2: Terminology / MethodologyMethodology
Terminology:– Normalized Stoichiometric Ratio
Molar ratio– Ammonia– Urea
– Reagent Utilization– Ammonia Slip– SNCR Effectiveness – Percent NOx reduction
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Task 3: Identification of Task 3: Identification of SNCR ReagentsSNCR Reagents
Reagents:– Primary reagents
Ammonia– Anhydrous (RMP, PSM, Homeland Security)– Aqueous
Urea– Other reagents
Cyanuric Acid (C3H3N3O3) Biosolids Processed Photographic water
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Task 3: Identification of Task 3: Identification of SNCR ReagentsSNCR Reagents
Reagents:– Primary reagents
SuppliersCostsSpecial considerations
– PSM– RMP– Homeland Security
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Task 4: Regulatory Task 4: Regulatory ConsiderationsConsiderations
– Clean Air ActNOx NAAQS
– Clear Skies Legislation– Clean Air Interstate Rule (CAIR)– Ozone Transport Commission– South Coast Air Quality
Management District
Other Regulatory Other Regulatory ConsiderationsConsiderations
Regional Haze (BART)– NOx affects PM2.5
– PM2.5 non-attainment areas
– Regional Planning Organizations
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Task 4: Regulatory Task 4: Regulatory ConsiderationsConsiderations
– State Specific Reductions– Department of Homeland Security
Aqua ammonia 20% or greaterAnhydrous ammonia
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Task 5: Current SNCR Task 5: Current SNCR PracticePractice
– Operating IssuesTemperature
– Where to inject the reagentHigh turbulenceSufficient residence time
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Task 5: Current SNCR Task 5: Current SNCR PracticePractice
– Operating IssuesReagent handling
– Ammonia is a toxic chemical RMP PSM
– Urea solutions are more viscous Delivery system must allow for this
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Task 5: Current SNCR Task 5: Current SNCR PracticePractice
– Operating Issues Ammonia slip
– Ammonia emissions– Odors– Inefficient use of reagent– Impact on synthetic gypsum from
scrubber– Ammonium salt formation
SNCRSNCR
Equipment Required– Reagent tank– Distribution system– Control system– CEMS for NOx & ammonia required to
determine optimum ammonia injection rate to maximum NOx control & minimize ammonia slip
– If urea used, water treatment system & heat traced storage & piping required
Reagent TankReagent Tank
Reagent Injection SystemReagent Injection System
SNCRSNCR
Until Recently, SNCR Limited to PH or PH/PC Kilns
SNCR Used Extensively in Europe for NOx Control
One Plant in Europe Using SNCR on Long Wet Kilns
Two plants in U.S. Tested SNCR on Long Wet Kiln Systems & Expect to Use SNCR to Comply with New Ozone SIP Requirements
SNCR in Wet KilnsSNCR in Wet Kilns
Urea injector
Location 21100°C
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Task 6: Current SNCR Task 6: Current SNCR InstallationsInstallations
Table 2. Temperatures at Reagent Injection Points Temperature at Injection
Point Reagent Reference
1,050°C (1,922°F) Urea Solution 6 890°C (1,640°F) Urea Solution 11
832 – 843°C (1,530 – 1,550°F)
Urea Solution 9
900°C (1,652°F) Aqueous Ammonia 1 871°C (1,600°F) Aqueous Ammonia 29 862°C (1,580°F) Aqueous Ammonia 35
860 – 980°C (1,580 – 1,800°F) Aqueous Ammonia 27 (expected location) 850 – 1,150°C (1,550 –
2,100°F) Aqueous Ammonia 17, 18, 19, 20, 21, 22
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Task 6: Current SNCR Task 6: Current SNCR InstallationsInstallations
Table 3. Reagent Injection Locations Kiln Type Reagent Injection Location Reference
Location PH/PC Between precalciner and 4th stage cyclone 1 PH/PC Between tertiary air and 4th stage cyclone 1 PH/PC Between top of preheater and 4th stage
cyclone 11, 12
PH/PC Calciner 9, 28, 29 PH/PC Bottom of calciner 13 PH/PC Kiln feed shelf before calciner 14, 15, 16 PH/PC Between bottom preheater stage and
calciner 27
PH/PC Calciner before lowest stage cyclone 30, 31, 32, 33, 34, 35
Preheater Kiln inlet (lowest part of pre heater) 18, 19, 20, 21, 22 Preheater Top of calciner and crossover duct 23, 24, 25, 26 Long Wet Into kiln, near feed end 6
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Task 6: Current SNCR Task 6: Current SNCR InstallationsInstallations
Table 5. Maximum NOx Emission Reductions Achieved Reagent to NOx Ratio (NSR)
Maximum % NOx Reduction Obtained with
SNCR Kiln Type Throughput (ton / hr) Reference
1.4 85 PH/PC Kiln Capacity - 266 8 2.0 73 PH/PC Kiln Feed - 230 – 260 1 1.5 78 PH/PC Kiln Feed - 200 – 250 1 2.0 90 PH/PC Kiln Feed - 160 9 1.1 80 PH Kiln Feed - 150 17, 18, 19,
20, 21, 22 1.2 85 PH/PC Kiln Capacity - 87 8
25 PH Clinker Max - 150 23, 24, 25, 26
20 PH/PC Clinker Max - 145 11, 12 25 PH/PC Clinker Max - 123 13
0.5 65 PH/PC Clinker - 120 30, 31, 32, 33, 34
0.5-3.5 15-70 Long Wet 6 1.0 82 PH/PC Clinker - 110 35
RACT / BACT / LAER RACT / BACT / LAER DatabaseDatabase
The RBLC database has identified the following SNCR applications– Branford Cement (Suwanee)
Permit limit of 1.95 lb/ton– American Cement
Permit limit of 1.95 lb/ton– Sumter/Center Hill Cement
Permit limit of 1.95 lb/ton– Brooksville Cement Plant (Florida Crushed Rock)
Permit limit of 2.4 lb/ton at startup (180 days) then limit of 1.95 lb/ton
– Thompson Baker Cement Plant (Florida Rock) Permit limit of 2.45 lb/ton (180 days) then limit of 1.95 lb/ton
– Lehigh Mason City Permit limit of 2.85 lb/ton
SNCR Controls in Europe SNCR Controls in Europe (Cement) (2005)(Cement) (2005)
Country Number of SNCR PlantsDenmark 1 (by end of 2005)Germany > 30France 14 (by end of 2005)Great Britain 1 (by end of 2005)Italy < 10Austria 5Sweden 3Switzerland 4Spain 1
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Task 7: Current SNCR Task 7: Current SNCR Use in Other IndustriesUse in Other Industries
– Electric Utility IndustryExxon patented ammonia SNCR in
1975EPRI patented urea SNCR in 1980
– Current trend is multi-pollutant strategiesEconomicsTo meet more stringent requirements
SNCR Cost ConsiderationsSNCR Cost Considerations
Anhydrous Ammonia: – Delivered cost is approximately $850 per
ton– Truck contains 22 tons
Aqua Ammonia: – Delivered cost is approximately $950 per
ton (anhydrous basis)– Truck contains 4.5 tons (anhydrous basis)
Urea:– Delivered cost is approximately $250 per
ton for a 50% solution
Reagent Cost ExampleReagent Cost Example
– Assumptions Uncontrolled NOx emissions = 1000 tpy
– NOx is 90% NO, 10% NO2
% Reduction = 40% Total NOx Reduced = 400 tons Ammonia used as reagent
– Cost of 19% ammonia = $950/ton anhydrous basis
– Cost of anhydrous ammonia = $850/ton– Cost of 50% urea = $250/ton
NSR = 1.0
Reagent Cost ExampleReagent Cost Example
Annual Usage (tons)
Price ($/ton) Annual Reagent Cost ($/yr)
Anhydrous Ammonia
538 850 457,300
19% Aqua Ammonia
2,836 (as 19%)
950 (anhydrous basis)
511,100
50% Urea 2,065 (as 50%)
250 516,250
SNCR Cost ConsiderationsSNCR Cost Considerations
Ammonia costs have increased in the past year.– 80% of US ammonia usage is agricultural– 40% of US ammonia usage is for corn– Ammonia demand increase is driving
cost With an ammonia system, cost
analysis must include RMP, PSM compliance costs
Ammonia increases provided by AirGas
SNCR Cost Analysis (cont.)SNCR Cost Analysis (cont.)
Operating costs:– Reagent: $500,000– Utilities: $235,000
Electricity
– Labor and Materials: $99,500– Overhead: $151,000
Taxes Administration Insurance
– Total Operating Cost: $1 MM/YR
Reagent Cost EffectivenessReagent Cost Effectiveness
Reagent costs have increased– Cost Effectiveness in 2007 (reagent$ /ton
NOx removed) Anhydrous: $808/ton 20% Aqua: $921/ton Urea: $826/ton
– Cost effectiveness in 2008 (reagent$ /ton NOx removed)
Anhydrous: $1,143/ton 20% Aqua: $1,227/ton Urea: $1,290/ton
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SummarySummary
SNCR is a mature technology– Application is more easily applied to
PH/PC systems– NOx reductions of 30-60% typical– Consideration must be given to
Temperature Turbulence Residence Time NSR
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SummarySummary
SNCR is a mature technology–Potential adverse affects
Ammonia slip–Odors–Formation of ammonium salts–Detached plume
NOx may increase if the temperature is too high