Stationary Source Controls & Source Sampling Marti Blad, PhD, PE

2 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

3 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

4 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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7 Settling Chambers  “Knock-out pots”  Simplest, cheapest, no moving parts  Least efficient  large particles only  Creates solid-waste stream  Can be reused  Picture on next slide

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9 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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13 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

14 Electrostatic Precipitator Concept

15 Electrostatic Precipitator

16 Electrostatic Precipitator

17 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 (SO 2 )

18 Spray Tower

19 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 (SO 2 )

20 Venturi Scrubber Detail illustrates cloud atomization from high- velocity gas stream shearing liquid at throat

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22 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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25 Baghouse in a Facility

26 Pulse-Air-Jet Type Baghouse

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Stationary Source Controls: Gaseous Pollutants and Air Toxics

29 Controlling Gaseous Pollutants : SO 2 & NO x  Modify Process  Switch to low-sulfur coals  Desulfurize coal (washing, gasification)  Increase efficiency  Low-NO x burners  Recover and Reuse (heat)  staged combustion  flue-gas recirculation

30 Controlling Gaseous Pollutants: CO & VOCs  Wet/dry scrubbers  Absorbers  NO x and SO x included  Proper operating conditions  Thermal and catalytic oxidation  Chemical  Carbon adsorption  Physical

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 NO x tend to increase VOC’s  Atmosphere in air combustion 78% N 2 31

32 Scrubbers / Absorbers  SO 2 removal: “FGD” (flue gas desulfurization)  Lime/soda ash/citrate absorbing solutions  Can create useable by-product OR solid waste stream  NO x removal—catalytic and non-catalytic  Catalyst = facilitates chemical reaction  Ammonia-absorbing solutions  Process controls favored over this technology  CO & CO 2 removal  Some VOC removal

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34 Thermal Oxidation  Chemical change = burn  CO 2 and H 2 O 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

35 Flares

36 Catalytic Oxidation

37 Carbon Adsorption  Will do demonstration shortly  Good for organics (VOCs)  Both VOCs and carbon can be recovered when carbon is regenerated (steam stripping)  Physical capture  Adsorption  Absorption

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39 Adsorb Absorb

40 Controlling Air Toxics  “Technology-based” approach  Maximum achievable control technology (MACT)  Based on emissions levels already being achieved by better-controlled and lower-emitting sources in an industry  Provides level economic playing field  In setting MACT standards, EPA does not generally prescribe a specific control technology

41 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

42 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

43 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

44 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 (%O 2, %N 2, %CO 2 )  Method 4  Moisture content of stack gas  Method 5  total particulate emissions  Method 9  visual determination of opacity

45 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

46 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

47 Continuous Emission Monitoring (cont.) Total Hydrocarbon Setup

48 Continuous Emission Monitoring (cont.)  CO  NO  NOx  SO2  THCs  Flow  Temperature

49 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

50 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  CARB  Smoke school

51 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

52 ment/AirQuality/HowAirPollution IsControlled.aspx Animated Control Technologies