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Stationary Source Controls & Source Sampling Marti Blad Ph.D., P.E.

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Presentation on theme: "Stationary Source Controls & Source Sampling Marti Blad Ph.D., P.E."— Presentation transcript:

1 Stationary Source Controls & Source Sampling Marti Blad Ph.D., P.E.

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 for control of gasses Examples of types of controls How air pollution control devices work Sampling of point sources 2

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 3

4 Particulate Control Technologies Remember this order Settling chambers Cyclones ESPs (electrostatic precipitators) Spray towers Venturi scrubbers Baghouses (fabric filtration) All physical processes 4

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7 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 7

8 Variety of styles 8

9 Simple Boxes= Collection 9

10 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 10

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12 Notice Shapes and Fans 12 Dry collection systems

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15 Venturi Scrubber Detail illustrates cloud atomization from high-velocity gas stream shearing liquid at throat 15

16 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 ) 16

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18 Venturi and Scrubbers 18

19 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 ) 19

20 Spray Tower 20

21 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 21

22 Electrostatic Precipitator Concept 22

23 Same Size & Shape 23

24 Electrostatic Precipitator 24

25 Electrostatic Precipitator 25

26 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 26

27 Pulse-Air-Jet Type Baghouse 27

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29 Baghouse in a Facility 29

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31 Baghouse= Fabric Filters 31

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33 Stationary Source Controls: Gaseous Pollutants and Air Toxics

34 Sources of Gaseous Pollutants 34

35 Controlling Gaseous Pollutants : SO 2 & NO x Modify process Switch Switch to low-sulfur coals Desulfurize coal Washing–bioclean Gasification Increase efficiency Low-NO x burners 35

36 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

37 How FGR Fits in the Process 37

38 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 38

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41 Controlling Gaseous Pollutants: CO & VOCs Wet/dry scrubbers Used for PM but double w wet Absorber solutions NO x and SO x included Combustion Process Proper operating conditions Low NOx burners 41

42 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 VOCs Atmosphere in air combustion 78% N 2 Atmosphere in air combustion 78% N 2 42

43 How it Might Look Together 43

44 Flares 44

45 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 45

46 Thermal Oxidation 46

47 Actual Oxidizers 47

48 Regenerative 48

49 Recuperative 49

50 Carbon Adsorption Good for organics (VOCs) Both VOCs and carbon can be recovered when carbon is regenerated (steam stripping) Physical capture Adsorption & Absorption (farty pants) 50

51 51 Adsorb Absorb

52 52

53 Stack Sampling 53 Are you afraid of heights?

54 Stack Sampling Site Setup 54

55 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 55

56 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 56

57 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 57

58 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 58

59 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 59

60 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 60

61 Continuous Emission Monitoring cabinet 61  CO  NO  NOx  SO2  THCs  Flow  Temperature

62 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 62

63 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 63

64 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 64

65 65 ment/AirQuality/HowAirPollution IsControlled.aspx Animated Control Technologies

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