大气资料整理

1、1. ESPElectrostatic precipitator, which is like a gravity setter or centrifugal separator, and electrostatic force drives the particles to the wall.2. PM10 particles with the aerodynamic diameter less than 10m,which is also called Inhalable particles.3. PM2.5particles with the aerodynamic diameter l

2、ess than 2.5m,which is also called Respirable Particles.4. Lean burn（engine）An engine operated with the fuel supplied is less than that which would react with the available air.5. Wet scrubberA device that collects particles by contacting the dirty gas stream with liquid drops.6. A/F ratio: Air to f

3、uel ratio for auto engines7. AerosolParticles small enough to remain suspended in the atmosphere or in other gases for long times are called aerosols, which indicates that they behave as if they were dissolved in the gas.8. EGRExhaust gas recirculation, in which the incoming combustion air is dilute

4、d with up to 20 percent or more exhaust gas.9. Alternative FuelSeveral other fuel except of conventional gasoline and diesel, which have been used for many years in slightly modified automobile engines, for reasons of cost and availability.10. TWCThree-way catalyst, Catalyst used to remove hydrocarb

5、ons (HC), nitrogen oxides(NOX) and carbon monoxide(CO) simultaneously in the emission of automobiles:11. TSP: Total suspended particles, particles in the atmosphere with the aerodynamic diameter less than 100m 12. Four-way catalyst:Four-way catalyst, Catalyst used to remove Particular matter (PM), h

6、ydrocarbons (HC), nitrogen oxides (NOX) and carbon monoxide (CO) simultaneously in the emission of diesel engines:13. LPG: Liquified petroleum gas, Mixture of petroleum and natural gas, which is compressed, liquid at ordinary temperature, and with propane as main composition(USA and Canada)14. CNG:

7、Compressed natural gas, which is stored in high-pressure (2500 psia) containers in the vehicle.15. Primary particles:particles found in the atmosphere in the form in which they were emitted Secondary particles:particles formed in the atmosphere form gaseous precursors.16. Terminal gravitational sett

8、ling velocity:the velocity with which a particle settles through the atmosphere or through water.17. Globe warming18. Temperature inversions逆温(现象)19. VOCSVolatile organic compounds are liquids or solids that contain organic carbon ,which vaporize at significant rate.20. Adsorption 吸附Adsorption is th

9、e process whereby molecules of a liquid or a gas are preferentially separated from a flow stream and collected on the surface of a solid21. Absorption 吸收Absorption is the mass transfer of pollutants from the gas to the liquid phase which is driven by a concentration gradient at the gas-liquid interf

10、ace22. Condensation浓缩 is the conversion of compounds from the gas phase to the liquid phase by decreasing temperature or increasing pressure.23. Biofiltration : Biological Oxidation生物过滤作用24. SCR: Selective Catalytic Reduction 选择性催化还原Temperature 300 - 400 oC25. SNCR: Selective Noncatalytic Reduction

11、Temperature 800 - 1000 oCAbove 1000 oCSCR and SNCR: 6NO+4NH3 5N2+6H2O 4NO+4NH3+O2 4N2+6H2O2NO2+4NH3+O2 3N2+6H2O These reactions can be carried out over a variety of catalysts, the temperature is between 1600 0 and 1800 0 F,once the temperature increases ,the dominant reaction is NH3+O2 NO + 3/2H2O ,

12、the catalytic接触反应的 processes are called SCR, and the higher-temperature ones, without catalysts, called SNCR.26. Thermal, Fuel, Prompt NO NO formed by the Zeldovich mechanism is highly sensitive to temperature and is called thermal NO Thermal NO dominates the scene at high temperaturesIf the fuel co

13、ntains nitrogen, some will end up as NO, called fuel NO to distinguish its sourceThe highly reactive species such as CH3 found in flames of carbonaceous fuels interact rapidly with nitrogen and oxygen to form prompt NO27. Air pollutantIt is the presence of undesirable material in air, in quantities

14、large enough to produce harmful effects, usually caused by human activities.28. FGDFlue gas desulphurization脱硫 are major costs for the electric utility industry, which is continually trying to improve FGD performance and to develop less expensive alternative processes29. FGR30. NAAQS31. Cyclones32.

15、Inertia SeparatorsInertial SeparatorsCyclone separators cause air to move in a tight radius.Dense particles move outward (actually, fail to make the tight turn) and impact the walls of the separator. They fall to the bottom and are collected. These systems are low in initial cost and maintenance. Th

16、ey are often used to remove large particles before final cleaning in baghouses or electrostatic precipitators. They typically have efficiencies of 98% for particles 5 mm.33. Re-entrainment (集尘的)再飞散34. driving velocity35. Aerodynamic diameter简答1. What are primary air pollutants and secondary air poll

17、utants? Any example?primary air pollutants are directly from the sources, for examples, NO, CO, SO2. Thesecondary air pollutants are from the primary pollutants, such as NO2, O3, fine particles.NO+CH+O2+sunlight NO2+O3Hydrocarbons + sulfur oxides + nitrogen oxides fine particles2. What kinds of indo

18、or air pollutants are mostly concerned by public?a) Radon氡b) Combustion by-products副产品i. CO, CO2, SO2, Formaldehyde甲醛, Hydrocarbons, NOx,ii. Particulates, Polyaromatic hydrocarbonsc) Cigarettesd) Volatile organic compoundse) Formaldehydef) Biological contaminants3. Which are the main constituents fo

19、r the ground level ozone formation?Ozone is formed when the following constituents are present. Nitrogen Oxides Volatile Organic Compounds Sunlight High temperature (18C)4. How to control VOCs pollution by prevention?Substitution Replace oil based with water based paints, coatings, solvents and inks

20、. Replace gasoline with compressed natural gas or propane.Leakage Control Filling leaks Breathing leaks Emptying losses Seal leaksProcess Modification5. Please explain the formation of acid rain?sulfur oxides and nitrogen oxidesNO NO2 HNO3 nitric acidSO2 H2SO4 sulfuric acid6. Please introduct the pr

21、ocess of forced-oxidation Limestone Wet Scrubbing briefly.Limestone scrubbing (1)SO2 + H2O H2SO3(2) CaCO3 + H2SO3 CaSO3 + CO2 + H2O(3)2 CaSO3 + O2 2 CaSO4Reactions (1) and (2) in scrubber, (2) and (3) in holding tank.In fact, the aqueous chemistry of these systems is quite complex 7. What are basic

22、principles of electrostatic Precipitators (six activities)?l Ionization - Charging of particles l Migration - Transporting the charged particles to the collecting surfaces l Collection - Precipitation of the charged particles onto the collecting surfaces l Charge dissipation - Neutralizing the charg

23、ed particles on the collecting surfaces l Particle dislodging - Removing the particles from the collecting surface to the hopper l Particle removal - Conveying the particles from the hopper to a disposal point 8. Can TWC be applied in the treatment of diesel柴油机 exhaust? Why?9. What are main sources

24、of air pollutants?Fuel combustion - Largest contributor Chemical plants化学工厂Motor vehiclesPower and heat generators Waste disposal sites Operation of internal-combustion engines 10. How to control particulate pollutants? Point out at least 5 measures.11. Please give out five major types of wet scrubb

25、ers and explain their work mechanism.Plate scrubbers,Packed scrubbers,Preformed Spray Scrubber,Gas-AtomizedSpray Scrubber,Centrifugal Scrubber,Impingement-Entrainment Scrubber,Mechanically Aided Scrubber,Moving Bed Scrubber.12. How to control NOx pollution from motor vehicle emissions?Post flame tre

26、atment: add a reducing agent which transforms the NOAlternative Fuels: Alcohol Natural Gas Hydrogen ElectricityAlternative transportation: Public Transportation ; Carpooling合伙使用汽车Modified engine design: stratified charge engine 分层进气13. How to control SO2 pollution from power plant emissions?change t

27、o a lower sulfur content fuel, remove sulfur from the fuel, modify the combustionprocess, or dont burn it at all.14. Which kinds of air pollutants source are mainly produced by human activities?industrial plants, fuel burn, vehicle emissions, smoking and some bad habits.15. Please give out at least

28、5 natural air pollution sources.Volcanoes 火山 Coniferous forests针叶树林 Forest fires Pollens花粉 Spores孢子Dust storms尘暴 Hot springs 温泉16. How to control and reduce the concentration of ground level ozone?17. How to control VOCs pollution? Point out at least 5 measures.substitution, process modification, le

29、akage control, condensation, adsorption, scrubbing,combustion, biological oxidation.18. Please give out five major types of Particulate Collection Devicesgravidity settlers, cyclones, ESP, filters, scrubbers.19. What kind of pollutants are called VOCs?Volatile Organic Compounds (VOCs) are those orga

30、nic liquids or solids whose roomtemperature vapor pressures are greater than about 0.01 psia(=0.0007atm) and whoseatmospheric boiling points are up to about 500 0 F(=260 0 C), which means most organic compounds with less than 12 carbon atoms.20. How to control NOx pollution from industrial flue gase

31、s?There are two ways to control NOx pollution: Modify the combustion processes to prevent the formation of NOx or treat the combustion gas chemically, after the flame, to convert the NOx to N2 .21. Please give out at least four kinds of Greenhouse gases.CO2 CH4 N2O H2O(water vapor) O322. Give out th

32、ree major types of Particulate Collection Devices without the use of liquid.Gravity setters, Dry ESP, Centrifugal separator.23. What are basic principles of Forced-Oxidation Limestone Web Scrubbers to control SO2 pollution from power plant emissions?24. Three-way catalyst plays an important role in

33、the treatment of exhaust of gasoline-fueled motor vehicles and comes to a satisfactory performance, why does three-way catalyst fail to solve the emission problem when it comes to the diesel engine?The mixture process of fuel and air for gas engines is distinguished from that for diesel engines, hen

34、ce the character of one type engine is different from the other one: there are mainly five gases (NOX, HC, CO and O2, CO2) in the exhaust of gas motors, while there are ample O2 and four other gases mentioned above in the tailpipe emission of diesel engine. And the presence of abundant O2 would inhi

35、bit the performance of TWC.Moreover, the contact and reaction of solid-solid-gas resulting in the difficulties for catalysts to oxidation the particulate in the exhaust of diesel engine, while the contact and reaction of solid-gas-gas occur in the exhaust of gasoline engine, and the latter reaction

36、is easier.25. How to control motor vehicle pollution pollution? Piont out at least 3 measures.Engine modification, EGR, Catalytic treatment(DOC, TWC,FWC), Non-emission control technologies26. Please give the source of Pollutants of motor vehicles (Three sources)EvaporativeCrankcase: 20%HCTailpipe em

37、issions: all CO、NOX、Pb and 60%HCCh10Combustion: Three basic types of combustionThe first type is direct flame incineration temperatures up to 25000 F NOx no preheating of gas stream no secondary energy recoveryThe second combustion process is thermal incineration used when concentration of combustant is too low for DFI preheatin