electrostatic precipitation for electrostatic
TRANSCRIPT
Clean Air Technologies
CIBO-2003
Electrostatic Precipitation Technology
Dry ESPs vs. Wet ESPs
CIBO 2003
Electrostatic PrecipitationFor
Multi-Pollutant ControlBy
Dr. Isaac Ray
Clean Air Technologies
Dry ESP vs. Wet ESP Technology• ESP History • Particle Size & Opacity• Primary Functions • Benefits of ESPs • ESP Process• Dry-Wet ESP Comparison • Design Parameters• ESP Configurations• Application-Test Results • New ESP Technologies
Corona Discharge
History of ESP Technology
• Century Old Technology• Developed by Dr. Cottrell in 1907• Originally Applied to Sulfuric Acid Mist• 1925 Power Boiler Industry adopts Dry ESP• Dry ESPs are Foundation of Modern APC• New MACT Regulations are requiring Wet ESPs
PM2.5
PM10
PM1
Particle Size
OPACITY LIGHT EXTENSION
0.5 MICRON PARTICLES ARE THE WORST ACTORS
As Particle Size DecreasesElectrostatic Forces Increase
Primary Functions
• Dry ESP– Course Particulate Removal– Fly Ash -2-10 micron
• Wet ESP– Final “Polishing” Device – PM2.5– Acid Mist -H2SO4 – Metals (including Hg)– Opacity Reduction
Rebuilt Dry ESP at Duke Powercourtesy of Southern Environmental
Benefits of ESP Technology
• Low-Pressure Drop– Low Energy Usage
• Proven Performance - 99% Removal– PM10- Dry ESPs– PM2.5/Acid Mists/Metals- Wet ESPs
• Reliable Control Devices– Dry ESPs- Mechanical Cleaning– Wet ESPs-Washing – Wet ESPs
Ionizing ElectrodeGAS
MOLECULESIONIZED
CORONADISCHARGE
CURRENT METER
HIGH VOLTAGETRANSFORMER
mA
1. Charging •Gas ions formed by high voltage corona discharge•Particles charged by bombardment of gaseous ions
2. Collection •Ions transport particles to collector•Particle charge given up to collector
3. Cleaning •Dry ESP-
•Particles collect on collection surface •Particles accumulate •Plate cleaned by rapping or sonic horns
•Wet ESP•Particle trapped in liquid film•Not on the collection plate•Liquid film continuously cleans surface•No accumulation on collection surface
CLEANING OF THE COLLECTION SURFACE IS THE KEY DIFFERENCE
ALLOWS FOR MUCH HIGHER POWER AND NO RE-ENTRAINMENT
Electrostatic Precipitation Process
PARTICLEENTERS PARTICLE
COLLECTED
PARTICLECHARGED
PARTICLEIRRIGATEDFROM WESP
Dry ESPCollection Surface
CHARGE RETURNS TO TRANSFORMER
Wet ESPCollection Surface
Liquid SlurryParticles
ISSUE DRY ESP WET ESPPM10 Removal YES NOCarbon Steel MOC YES NOCleaning via Rapping/Sonic Horns YES NOBack Corona YES NORe-Entrainment YES NOUnsaturated Flue Gas YES YES*Saturated Flue Gas NO YESPM2.5 Removal NO YESPM1 Removal NO YESSO3 Removal NO YESToxic Metal Removal NO YESMercury Removal NO YES
Dry-Wet ESP Comparison
Design Parameters
PARAMETER UNITS DRY WETESP ESP
PRECIPITATION RATE FT/SEC 0.05 - 1.00 0.15 - 2.00SCA FT2/MCFM 50 - 1000 50 - 500CORONA POWER WATTS/MCFM 50 - 500 500 - 3000GAS VELOCITY FT/SEC 3 - 8 3 - 12+?
ESP Configurations
• Tubular TypeVertical Down Flow-wetVertical Up-flow -wet
• Plate TypeHorizontal Flow-dry/wetVertical Up-flow -wet
For a given volume, a tubular ESP has twice the collection area as a plate ESP. Therefore, a tubular WESP can operate at twice the velocity of a plate type ESP, resulting in a smaller footprint for a given efficiency. .
Make-up
Coal Supply
Flue Gas
Heated Air
Ambient AirDry Bottom Ash Dry Fly Ash Wet FGD Solids
Sluice Water
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Boiler
Air Preheater
Dry ESP
SCR
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+
Wet FGD
WaterTreatment
WESP
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High Sulfur Coal Boiler Application with Dry and Wet ESPs
Saturated Flue Gas with FGD
WESP Pilot PlantWESP Pilot Unit
Coal-Fired Power Plant Pilot WESP- 2400 MW plant- >50% opacity-State requires < 20%
-Rated 5,000 CFM -Tubular WESP-Slip-Stream after FGD-PM2.5 & SO3-Mercury Testing
Minimum Power
Maximum Power
View Through Obs. TubeObservation Tube-Opacity
Medium Power
Coal Fired Utility Pilot Test-Designed for 90% Removal at 5,000 cfm in One Field-Tested at 8,000 cfm - 76%-79% Removal in one field- Modified to 2 Fields - achieved 92%-96% removal- Mercury-Limited Testing-Oxidized removed similar to PM2.5
Summary of Pilot Wet ESP Test Results- Bruce Mansfield Plant –2001-2002Mercury
PM2.5 SO3 Mist Tests Particulate Oxidized ElementalAverage of all TestsTest Series Sep-01 Nov-01 Sep-01 Nov-01 Sept –01 Sept -01 Sept –01Airflow-acfm 8394 8235 8394 8235 8000 8000 15000Velocity –ft./sec.
10 10 10 10
# of fields 1 2 1 2 1 1 1Power Levels 100% 100% 100% 100% 100% 100% 100%
ug/dscm ug/dscm ug/dscmInlet 0.0292 0.0506 11.475 10.01 0.011 0.689 6.245Outlet 0.0063 0.002 2.7 0.85 0.004 0.158 3.474
Removal % 79% 96% 76% 92% 64% 77% 44%
Nov-01 InletPM2.5-116mg/m3
SO3-10.1 ppm
Nov-01 OutletPM2.5- 5 mg/m3
SO3- 0.85 ppm
Iso-Opacity Chart of Test ResultsIso-Opacity Curve
Opacity is a function of both PM2.5 & SO3 mist. An Iso-Opacity chart predicts opacity from a given PM2.5 and SO3 concentration
Kyanite Mining-Virginia-Ore Roasting-cyclone/scrubber/WESP system
Pollutant Units Inlet Outlet Removal %SO2 Ppm 3580.07 21.4 99.4ACID MIST(H2SO4)
gr /dscf 0.228 0.0159 93.0
PM2.5 gr /dscf 1.6 0.006 99.6NOx Ppm 41.1 21.5 47.7CO Ppm 640.63 581.6 9.2CONDENSED,INORGANIC
Gr/dscf 0.13102 0.0143 89
CONDENSED,ORGANIC
Gr/dscf 0.14148 0.01573 90
THC Ppm ascarbon
225.3 85.5 62
Opacity >50% <5%
Pollutant Units Test Runs MACTLimits
Removal%
Particulate Gr/dscf, 7%O2 0.0024-0.0030 0.015 99.94
HCL/Cl2 ppmdv, 2.96-4.84 77 99.95
Chromium Ug/dscm 39.7-42.8 97 99.97
Lead Ug/dscm 3.59-3.85 240 99.95
Mercury Ug/dscm 1.82-1.98 130 79%
Dioxin/furan Ng TEQ/dscm 0 0131-0 0892 0 4 N/D
Eastman Chemical- Hazardous Waste Combustors- Test Results-EPA MACT - Simultaneous worst case - All pollutants
Make-up
Plate RecycleDry Fly Ash
Blow dow n
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Dry ESP
Coal Supply
Flue Gas
Heated Air
Ambient AirDry Bottom Ash
Sluice Water
+Boiler
APH
SCR
Recycle
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WESP
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+
Low Sulfur Coal Boiler Application Hybrid Dry-Wet ESP
Unsaturated Flue Gas with No FGD
Substitute WetLast Field
20 º F To 50 º FAbove Saturation
All Dry: 0.2lb/MBtu
Dry/Wet: 0.03lb/MBtu
Hybrid Dry/Wet ESP
EPRI Test ResultsParticulate matter: 95% Sulfur dioxide: 20%Hydrogen chloride: 35%Hydrogen fluoride: 45%Mercury - to be piloted
Conclusions• ESP Technology is Well-Established & Proven• Dry ESPs -Used for Course Particulate (PM10)• Up to 99% Efficiency• Unsaturated Flue Gas • Horizontal Plate Configuration• Cleaning via Mechanical Rapping or Horns
• Wet ESPs- Used for PM2.5, H2SO4 mist & Metals• Final “polishing “ of the flue gas • Up to 99% Efficiency• Saturated & Unsaturated Flue Gas• Tubular & Plate Configuration
• Cleaning via Washing of Collection Surface