EPA/450/2-81/017e U.S. Environmental Protection Agency Air Pollution Training Institute COURSE 81:422 3rd Edition AIR POLLUTION CONTROL ORIENTATION COURSE **************************************************************** °p § I W Unit 5 Control Techniques for Gaseous and Particulate Pollutants ------- United States Air Pollution Training Institute EPA 450/2-81-017e Environmental Protection MD 20 June 1981 Agency Environmental Research Center Research Triangle Park NC 27711 Air APTI Course S 1:422 3rd Edition Air Pollution Control Orientation Course Units Control Techniques for Gaseous and Paniculate Pollutants Prepared By: Under Contract No. Northrop Services, Inc. 68-02-2374 P. 0. Box 12313 EPA Project Officer Research Triangle Park, NC 27709 R. E. Townsend United States Environmental Protection Agency Office of Air, Noise, and Radiation Office of Air Quality Planning and Standards Research Triangle Park, NC 27711 ****** This is one of nine self-instructional units in the Air Pollution Control Orientation Course SI:422. This unit consists of a cassette tape and this flip- book, which you will use simultaneously. Turn the page and read the tips on effective use of this material. ------- Tips for Effective Use *>f This Material 1. Listen to the recorded script while you go through this flipbook. The recorded portion is coordinated with the flipbook. Wait for the tape to finish the details of one point before studying the next point on the page. 2. When you hear a "beep" on the tape, direct your attention to the next page in the flipbook. 3. Pay attention to both words and pictures they both convey important informa- tion. The flipbook will usually summarize main points or give examples. 4. Stop the tape at any point if you wish to spend more time reading a page in the flipbook. Rewind the tape if you wish to review a portion of the script. 5. Review the lesson objectives before answering the questions at the end of each lesson. Ask yourself whether you have mastered the information indicated in the objectives. 6. Answer the questions. They will help you assess your progress in mastering the course materials. 7. Check your answers. The correct responses can be found on the page(s) fol- lowing the questions. 8. If you answer a question incorrectly, review the flipbook material covering the subject matter. Now Turn On the Tape Recorder and Begin Lesson I. 11 mmnmmmvvvvmwuwuuuu Lesson I: Control Techniques Not Requiring Control Devices Objectives 1. Name the two physical forms of air pollutants. 2. Identify four techniques for reducing pollutant emissions that do not require the use of emission control devices. ------- Two Forms of Air Pollutants Gaseous Particulate Primary Gaseous Pollutants sulfur oxides odors acid gases carbon monoxide nitrogen oxides hydrocarbons Common Particulate Pollutants cement dust metal fumes smoke fly ash acid mists ------- Emission Reduction Techniques Not Using Emission Control Devices Process change Change in fuel Good Operating practices good housekeeping maintenance Plant shutdown uuuwmmmvvwwttuwwwwv Process Change Fossil-fuel fired, ------- Change in Fuel &&&. ' '*&'$"%$*"..' ' :'&?:'j . &&^&^&*fr yp&~g W-vJ^!*;?- Good Operating Practices Bad Good ri^?,v% & Bad Good Good Housekeeping Maintenance ------- Plant Shutdown 8 National Emission Estimates 1970-1977 (Millions of metric tons/year) Year 1970 1971 1972 1973 1974 1975 1976 1977 TSP(a) 22.2 20.9 19.6 19.2 17.0 13.7 13.2 12.4 S0x(a) 29.8 28.3 29.6 30.2 28.4 26.1 27.2 27.4 N0x(a) 19.6 20.2 21.6 22.3 21.7 21.0 22.8 23.1 VOC(b) 29.5 29.1 29.6 29.7 28.6 26.9 28.7 28.3 CO 102.2 102.5 103.8 103.5 99.7 96.9 102.9 102.7 (a) FSF Total Suspended Paniculate matter in the case ot emissions, just paniculate mailer SO\ Sulfur Oxides NOx - Oxides of Nitrogen (b) V'OC - Volatile Organic Compounds hydrocarbons etc. 9 ------- .-.j'f" 'r'"'- £>.*t?.'£>- '' ': Gray or black emissions from smoke stacks are easily seen by everyone but no one sees the gaseous emissions. 10 Lesson I Questions 1. Name the two forms of air pollutants. 2. Four of the following are methods of pollutant reduction that do not require the use of emission control devices. Which one is not? a. tall chimneys d. change in fuel b. plant shutdown e. process change c. good operating practices Answers on next page. 11 ------- Lesson I Answers 1. gaseous, paniculate 2. a. tall chimneys After checking your responses, please turn on the tape recorder. 12 Lesson II: Control Techniques for Gaseous Emissions Objectives 1. Name the four main techniques used in devices that control gaseous emissions. 2. Identify the definition of each of the following terms: absorption, adsorption, condensation, and combustion. 3. Given a diagram of a control device (as it appears in this flipbook), name the control device and tell whether it is of the adsorption, absorption, condensa- tion, or combustion type. 4. Identify the factors that must be considered when choosing a device for the control of gaseous emissions. 13 ------- Control Techniques for Gaseous Emissions Adsorption Absorption Condensation Combustion 14 ttnmmmsnmmmnumnmn Adsorption The removal of a gaseous pollu- tant from a gas stream by allow ing the pollutant molecules in the gas stream to become attached to a solid surface. 15 ------- Adsorption Design Factors Nature of the contaminant Surface area of adsorbent Temperature and pressure Nature of adsorbent 16 How do we dispose of adsorbents? Dispose of both the pollutant and the adsorbent together 17 Remove the pollutant from the solid surface and re-use adsorbent bed (regeneration) ------- Adsorption Systems Nonregenerative Have thin beds Commonly used where there are low concen- trations of pollutants in a gas stream Regenerative Have thick beds Used for solvent or hydrocarbon recovery Regenerative System Clean gas out A Dirty gas in Steam for regeneration 18 Pollutant and steam out Dirty gas in Water out r< Water in Particulate filter Clean gases X Cooling coil (if required) Blower Unit #1- Removing pollutants Activated carbon Regenerative System Unit #2- Being regenerated Activated carbon Collected pollutant Clean air out Low pressure steam for regeneration 1 Q ------- Absorption The dissolving of a gaseous pollutant in a liquid solvent 20 Factors Affecting Absorption Type of pollutant Type of solvent Temperature of system Pressure on system 21 ------- With absorption equipment we try to get as much gas-liquid mixing as possible. 22 Absorption Equipment Spray tower Spray-chamber Venturi scrubber Packed column 23 ------- nr Clean gas out Packed Column Liquid in Packing material Dirty gas in Liquid and pollutant out mmwwmmvvivmwuuuuuu Condensation occurs when: Pressure increased Heat extracted from a system (the most economical method is temperature reduction) 25 ------- Condensers are usually used in conjunction with: afterburners absorbers adsorption units 26 WWWWWWVVUWttttttttWWW Surface Condenser (Temperature Reduction) Cooling medium Clean gas out in Cooling medium V Condensate out out 27 NJ Cooling medium: water or air ------- Clean gas out Contact Condenser (Temperature Reduction) Dirty gas in Water in 28 Water and condensate out mmmmmwvmwttttuwuww Combustion The result of the combination of oxygen with a combustible material, usually accompanied by heat and light 29 ------- Combustion is commonly used as a control technique for hydrocarbon emissions. 30 Combustion Equipment Flare Thermal incinerator Catalytic incinerator 31 ------- Flare 32 mmmwmmvmwttttwuuuu Thermal Incinerator (Afterburner) Dirty gas Fuel and air Dirty gas Ave. temp: 1400-1500 °F I Clean out 33 ------- Catalytic Incinerator Fuel Air Dirty gas Preheat burner Catalyst 600-900DF 800-1100°F Clean out 34 Choice of Control Technique Some questions to consider: 1. Will the pollutant burn? 2. Is the product of combustion a pollutant? 3. Is the pollutant soluble in water or another solvent? 4. Can the pollutant be easily condensed? 5. Is carbon adsorption applicable? 6. What is the age of the plant? 7. Is re-use of pollutant desirable? 8. What is the impact of control cost on selling price of the product? 9. What are equipment costs? 10. What are utility requirements? 35 ------- Lesson II Questions 1. Name the four main techniques used in devices that control gaseous emissions. 2. The phrase, "the removal of a gaseous pollutant from a gas stream by allowing the pollutant molecules to become attached to a solid surface" defines which of the following terms? a. condensation d. adsorption b. absorption e. evaporation c. combustion f. none of the above 36 umwwMmvvimuuuuuwuu Clean gas out 3. The diagram at the right depicts which of the following " type of control device? a. adsorption b. absorption c. combustion Liquid in Packing material Dirty gas in Liquid and condensate out ------- 4. The device depicted in question No. 3 is a: a. flare. d. regeneration adsorber. b. surface condenser. e. contact condenser. c. catalytic incinerator. f. packed column. 38 ttnimmiiniuuuumuuuunu 5. Which of the following is not a factor to consider when choosing a device for the control of gaseous emissions? a. color of the pollutant d. age of the plant b. equipment costs e. whether or not the pollutant c. whether or not the pollutant can be reused will burn f. solubility of the pollutant Answers on next page. 39 ------- Lesson II Answers 1. adsorption, absorption, condensation, and combustion 2. d. adsorption 3. b. absorption 4. f. packed column 5. a. color of the pollutant After checking your responses, please turn on the tape recorder. 40 Lesson III: Control Techniques for Particulate Emissions Objectives 1. Name the 4 types of paniculate matter. 2. Categorize each of the 4 types of paniculate matter as either solid or liquid. 3. Identify the factors that must be considered before choosing a paniculate con- trol device. 4. Name the 5 main types of paniculate control devices. 5. Given a diagram or picture of a control device (as it appears in this flipbook), name the control device. 6. Describe, briefly, the ideal solution to the problem of collected paniculate matter disposal. ------- 42 ttWWWWUWWUWUUUWW Common Terms Used to Describe Particulate Matter Solid Dust Smoke Fumes Liquid Mist ------- Information Needed About Gases and Particles Particle size Gas flow rate Temperature Moisture content Type and concentration of particles in gas stream Significant characteristics of particles abrasive, explosive, flammable, acidic, etc. Degree of Control Desired (i.e. efficiency) weight of particles enteringweight of particles leaving Efficiency total weight entering control equipment 44 fflnmnmmmiiiuuuuuuuuu- Particulate Control Devices Settling chamber Cyclone Wet collector (scrubber) Electrostatic precipitator Fabric filter (baghouse) ------- Settling Chamber Dirty gas in Clean gas out Collection force: gravity Collection efficiency: low Initial cost: inexpensive Operating cost: low Dust hoppers 46 wttuummuuuuuuuuuuuu Outlet tube Dirty gas in Cone Dust hopper Clean gas out Cyclone Cylinder Collection efficiency: low to medium Initial cost: inexpensive Operating cost: low Collected dust out 4-7 ------- Several small cyclones are used together to increase collection efficiency. 48 uuuuuuwuuuuuuuuuuuu Clean gas out Dirty gas in gas out Outlet tube Spin vanes Multiple Cyclone t Collector Element Collected dust out 49 ------- Wet Collector (Scrubber) Spray C ollection efficiency: medium to high Initial cost: moderate Operating cost: high Clean gas out Water and condensate out 50 High voltage Electrostatic Precipitator to plates (Plate Type) to wires Dirty gas in Discharge electrode (wire) gas ,n ,'^ '* Collection efficiency: medium to high Initial cost: high Operating cost: moderate to high Weights ------- Electrostatic Precipitator (Tube Type) Dirty gas in Clean gas out Dirty gas in 52 Clean gas out; mf|||F Spray Discharge electrode (wire) Weights AwuwwwvvvvYUVYYuuuuuuu Mechanism for shaking, rapping, or vibrating bags Clean air out Dirty air in Fabric Filter (Baghouse) Collection efficiency: high Initial cost: high Operating cost: high Clean air out air in 53 ------- Particulate control systems often require two or more control devices to obtain the highest possible efficiency. For example, Cyclone to collect large particles Electrostatic Precipitator to collect remaining small particles 54 .immmmiutttuuuuiuuuuui Disposal of Collected Material Most dry particulate material will be disposed of in land-fills or dumps. Water slurries go to basins or sewers or treatment plants. The ideal solution is to recycle the collected material. 55 ------- Lesson III Questions 1. Name at least four common kinds of paniculate matter. 2. Which of the following is (are) liquid particle(s)? a. dust c. fumes b. mist d. smoke 3. Which of the following should be considered before choosing a particulate control device? a. moisture content of stack gas d. type & concentration of b. gas flow rate particles c. characteristics of particles e. temperature f. all of the above 56 mmmummmtwutttuuuuui 4. Name the five main types of particulate control devices. 5. The control device depicted at the right is a(n)-. a. settling chamber. b. cyclone. c. wet collector. d. electrostatic precipitator. e. fabric filter. f. none of the above. 6. Describe briefly the ideal solution to the problem of collected particulate matter disposal. Spra Water and condensate out Answers on next page. ------- Lesson III Answers 1. dust, smoke, fumes, mist 2. b. mist 3. f. all of the above 4. settling chamber cyclone wet collector (or scrubber) electrostatic precipitator fabric filter (or baghouse) 5. c. wet collector (or scrubber) 6. The recycling of the collected material After checking your responses, review any material that you are not sure of, and then take the Unit Test which begins on the next page. 58 WWMWVVVVUUUUUUUUWUU Unit Test The two physical forms of air pollutants are: a. liquid and paniculate. d. gaseous and vaporous. b. liquid and gaseous. e. none of the above. c. gaseous and paniculate. Which of the following is not a method for reducing pollutant emissions? a. tall chimneys d. process change b. plant shutdown e. good operating practices c. change in fuel -o ------- 3. Which of the following is not a technique used in devices that control gaseous emissions? a. adsorption d. combustion b. condensation e. electrostatic precipitation c. absorption 4. The phrase "the dissolving of a gaseous pollutant in a liquid solvent" defines which of the following terms? a. adsorption d. combustion b. absorption e. none of the above c. condensation 60 uumimmuumimuuuiiums The diagram at the right depicts which of the following types of control device? a. adsorption absorption combustion condensation electrostatic precipitation b. c. d. e. Clean gas out A Regenerative System Dirty gas in Pollutant and steam Steam for regeneration 61 ------- 6. Which of the following must be considered when choosing a device for the control of gaseous emissions? a. equipment costs d. whether or not the pollutant b. whether or not the pollutant can be reused will burn e. solubility of the pollutant c. age of the plant 7. Which of the following is not a common kind of paniculate matter? a. mist d. vapor b. dust e. fumes c. smoke 8. Which of the following should be considered before choosing a device to control paniculate pollutants? a. moisture content of stack gas d. type and concentration of b. gas flow rate particles c. characteristics of particles e. temperature f. all of the above 62 UttttttWUUUUUUUUUUUUUU 9. The control device depicted at the right is a(n): a. settling chamber. b. cyclone. c. wet collector. Dirty gas in d. electrostatic precipitator. r-..:. A; e. fabric filter. A A Clean gas out Outlet tube Spin vanes t Collected dust out Collector Element ------- 10. Describe briefly the ideal solution to the problem of collected particulate matter disposal. Answers on next page. 64 AttttttttttttWWUUUUUUUUUU Answers 1. c. gaseous and particulate 2. a. tall chimneys 3. e. electrostatic precipitation 4. b. absorption 5. a. adsorption 6. a-e. equipment costs, whether or not the pollutant will burn, age of the plant, whether or not the pollutant can be reused, and solubility of the pollutant. 7. d. vapor 8. f. all of the above 9. b. cyclone 10. The recycling of the collected material. 65 ------- |