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