Stationary Source Controls & Source Sampling
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Transcript of Stationary Source Controls & Source Sampling
Stationary Source Controls & Source
Sampling
Marti Blad Ph.D., P.E.
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What we will learn Control of air pollution is possible
Physical, chemical or biological Control of air pollution is not perfect
“Shell game” Control mechanisms for particles are different
from those that control gasses Examples of types of controls
How air pollution control devices work Sampling of point sources
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Stationary Source Control
Philosophy of pollution prevention Modify the process: use different raw
materials Modify the process: increase efficiency Recover and reuse: less waste = less
pollution Philosophy of end-of-pipe treatment
Collection of waste streams Add-on equipment at emission points
AP control of stationary sources Particulates Gases
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Particulate Control Technologies
Remember this order: Settling chambers Cyclones ESPs (electrostatic
precipitators) Spray towers Venturi scrubbers Baghouses (fabric filtration)
All physical processes
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Settling Chambers “Knock-out pots” = initial separators Gravity and inertia forces
Simplest, cheapest, no moving parts Least efficient & large particles only
Creates solid-waste stream Can be reused
Pictures on next slides Baffle, Gravity, Centrifugal
Variety of styles
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Simple boxes= collection
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Cyclones Inexpensive, no moving parts More efficient than settling chamber
still better for larger particles Single cyclone or multi-clone design
In series or in parallel Creates solid-waste stream Picture next slide
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Notice shapes and fans
12Dry collection systems
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Venturi Scrubber
Detail illustrates cloud atomization from high-velocity gas stream shearing liquid at throat
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Venturi Scrubber High intensity contact between water
and gas => high pressure drop Venturi action modified spray tower High removal efficiency for small
particles Creates water pollution stream Can also absorb some gaseous
pollutants (SO2)
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Venturi and scrubbers
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Spray Towers Water or other liquid “washes out” PM Less expensive than ESP but more than
cyclone, still low pressure drop Variety of configurations Higher efficiency than cyclones Creates water pollution stream Can also absorb some gaseous
pollutants (SO2)
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Spray Tower
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ESPs Electrostatic precipitator More expensive to install, Electricity is major operating cost Higher particulate efficiency than
cyclones Can be dry or wet Plates cleaned by rapping Creates solid-waste stream Picture on next slide
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Electrostatic Precipitator Concept
Same Size & Shape
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Electrostatic Precipitator
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Electrostatic Precipitator
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Baghouses Fabric filtration – vacuum cleaner High removal efficiency for small particles Not good for wet or high temperature
streams Uses fabric bags to filter out PM Inexpensive to operate Bags cleaned by periodic shaking or air
pulse Creates solid-waste stream
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Pulse-Air-Jet Type Baghouse
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Baghouse in a Facility
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Baghouse= fabric filters
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Stationary Source Controls:
Gaseous Pollutants and Air Toxics
Source of Gaseous Pollutants
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Controlling Gaseous Pollutants: SO2 & NOx
Modify Process Switch to low-sulfur coals Desulfurize coal Washing-bioclean Gasification
Increase efficiency Low-NOx burners
Recover & Reuse Heat Staged combustion
Multi chambers Better process control
Flue-gas recirculation Gas is heat sink Absorbs heat from high flame area Lowers peak flame temperatures
Picture next slide 36
How FGR fits in process
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Controlling Gaseous Pollutants: CO & VOCs
Wet/dry scrubbers Used for PM but double w wet
Absorber solutions NOx and SOx included
Combustion Process Proper operating conditions Low NOx burners
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Scrubbers / Absorbers SO2 removal: “FGD” (flue gas
desulfurization) Lime/soda ash/citrate absorbing solutions Can create useable by-product OR solid
waste stream NOx removal—catalytic and non-
catalytic Catalyst = facilitates chemical reaction Ammonia-absorbing solutions Process controls favored over this
technology CO & CO2 removal Some VOC removal
VOC / CO Process Control Keep combustion HOT
Reuse & recycle heat Control cold start-ups, shut-downs, wet
inputs wood-fired, chemical incinerators, boilers
Increase residence time of gas in combustor
Unfortunately, things that reduce NOx tend to increase VOC’s Atmosphere in air combustion 78% N2
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How it might look together
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Flares
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Thermal Oxidation Chemical change = burn
CO2 and H2O ideal end products of all processes
Flares (for emergency purposes) Incinerators
Direct Catalytic = improve reaction efficiency Recuperative: heat transfer between inlet
/exit gas Regenerative: switching ceramic beds that
hold heat, release in air stream later to re-use heat
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Thermal Oxidation
Actual Oxidizers
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Regenerative
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Recuperative
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Carbon Adsorption Good for organics (VOCs) Both VOCs and carbon can be recovered
when carbon is regenerated (steam stripping)
Physical capture Adsorption & Absorption
Bettermarriageblanket.com Under-tec.com (farty pants)
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Adsorb
Absorb
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Stack Sampling
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Are you afraid of heights?
Stack sampling site setup
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What is source sampling?
Sample air pollutants at the source Stacks, vents, pt. of compliance, etc.
Sample specific pollutants Standard methods/protocols
Determine amount of a pollutant emitted Pollutant concentration
Mass pollutant per unit volume exhaust gas
Pollutant mass rate Mass pollutant emitted over a time
interval
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Why is source sampling done?
Evaluate process efficiency Evaluate equipment & control
performance Calculate process material balances Evaluate process economics Input of models (point source) Regulatory compliance
verification/permit review
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Before Sampling Sources Plan what will be done
Describe sampling objective, pollutants & site Identify responsible persons Sampling locations & access Standard methods
CFR, ASTM, AAC Sample type (grab, integrated or instrument) Methods – field sampling & lab analyses QA/QC requirements (field and lab) Health & safety considerations (plan) Each test is done 3 times
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Standard Methods – Basic
Method 1 Sample port location & number of ports,
determine absence of cyclonic flow Method 2
Stack gas velocity & flow rate Method 3
Gas MW & composition (%O2, %N2, %CO2) Method 4
Moisture content of stack gas Method 5
total particulate emissions Method 9
visual determination of opacity
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Standard Methods – Gases
Method 6 Sulfur dioxide
Method 7 Nitrogen oxides
Method 10 Carbon dioxide
Other methods Hydrocarbons Hydrochloric acid Hydrogen sulfide Fluoride Dioxins & furans PCBs, PAHs, Formaldehyde
(HCHO), others
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Continuous Emission Monitoring
Real-time detection of emissions gases Carbon dioxide Nitrogen oxides Sulfur oxides Hydrogen chloride Total hydrocarbons
Real time measure of flow and temperature
Continuous monitoring of opacity
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Continuous Emission Monitoring cabinet
CO NO NOx SO2 THCs Flow Temperature
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Is this something you should do?
Source sampling is Involved Expensive Time consuming
Source sampling requires Specialized training, experience &
equipment Laboratory support capacity Significant QA/QC
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What should you be able to do?
Know if it is being planned right
Know if it is being done right Know if it is reported right What resources are available
ITEP EPA CARB Smoke school
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What We just Covered Air pollutants can be controlled
involve tradeoffs, shell game Different controls for different types of
pollutants Source sampling is regulatory requirement
to ensure facilities are operating within permit requirements
Source sampling usually a series of methods
Source sampling not likely something you will do
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http://www.iowadnr.gov/Environment/AirQuality/HowAirPollutionIsControlled.aspx
Animated Control Technologies