大气复习资料
一、概念解释
（1）Globe warming:Global warming is the increase in the average measured temperature of the Earth's near-surface
air and oceans since the mid-twentieth century, and its
projected continuation.
（2）Temperature inversions：A temperature inversions is a thin layer of the atmosphere where the decrease in temperature
with height is much less than normal (or in extreme cases,
the temperature increases with height).
（3）ESP: Electrostatic precipitator, which is like a gravity setter or centrifugal separator, but electrostatic force
drives the particles to the wall.
（4）HEPA: High Efficiency Particulate Air
（5）Lean bum ：Lean burn refers to the use of lean mixtures in an internal combustion engine .The air-fuel can be as
high as 65:1 ,so the mixture has considerably less fuel
in comparison to the stoichiometric combustion ratio (14.7
for petrol , for example ).
（6）Plume rise: the plume rising a distance △h above the top of the stack before leveling out.
（7）Wet scrubber: A device that collects particles by
contacting the dirty gas stream with liquid drops.
（8）Photochemical smog：
（9）Thermal NO: Thermal NO x refers to NO x formed through high temperature oxidation of the diatomic nitrogen found in combustion air.
（10）A/F ratio: Air to fuel ratio for auto engines.
（11）PM2.5:particle with the aerodynamic diameter less than
2.5 um, which is also called Respirable Particles.（12）Alternative fuel: Several other fuels except of conventional gasoline and diesel, which have been used for many years in slighutly modified automobile engines, for reasons of cost and availability.
（13）VOCs: Volatile organic compounds are those organic liquids or solids whose room temperature vapor pressure are greater than about 0.01 psia(=0.0007atm) and whose atmospheric boiling points are up to about 500℉, which means most organic compounds with less than 12 carbon atoms.
（1）SCR and SNCR:6NO+4NH3→5N2+6H2O, 4NO+4NH3+O2→4N2+6H2O
2NO
2+4NH
3
→3N
2
+6H
2
O.
These reactions can be carried out over a variety of catalysts, the temperature is between 1600℉and 1800℉,
once the temperature increases, the dominant reaction is
NH
3+O
2
→NO+1.5H
2
O, the catalytic processes are called SCR,
and the higher-temperature ones, without catalysts, call
SNCR.
（2）Aerodynamic diameter: Airborne particles have irregular shapes, and their aerodynamic behavior is expressed in
terms of the diameter of an idealized spherical particle
known as Aerodynamic diameter.
（3）Primary Particles: Particles found in the atmosphere in the form in which they were emitted, for examples,
NO,CO,SO2
（4）Point Sources: small number of large sources that emit larger amounts per source, at higher elevations (power
plants, smelters, cement plants, etc.) called point
sources
二、Answer following questions
(1)Which are the main constituents for the ground level ozone
formation?
Ozone is formed when the following constituents are present.
Nitrogen oxides, Volatile Organic, Compounds, Sunlight, High temperature(>18 ℃)
NO+VOC+O
2+Sunlight→NO
2
+O
3
(2)Please list five major types of wet scrubbers.
Plate Scrubber （板式）Packed Scrubber （填料式）Preformed Spray Scrubber（喷雾式）Gas-Atomized Spray Scrubber （气体雾化）Centrifugal Scrubber （离心式）Impingement-Entrainment Scrubber（冲击夹带式）Mechanically Aided Scrubber （机械辅助式）Moving Bed Scrubber （移动床式）
(3)How to control VOCs pollution by prevention? Two examples. Substitution(代替), Replacing gasoline as a motor fuel with compressed natural gas or propane is a form of substitution. Process Modification(过程修改),Replacing gasoline-powered vehicles with electric-powered vehicles is a form of process modification.
Leakage（渗漏） Control, Storing large amounts of gasoline in floating roof tanks.
(4)Please introduce the process of forced-oxidation Limestone
Wet
Scrubbing briefly？
(5)What are the most different points between SCR and SNCR?
(6)Can TWC be applied in the treatment of diesel exhaust
(=emission
of diesel engine)? Why？
·The characteristic of emission of diesel engine: Ample PM and
Excessive O2, Lower temperature;
·The difficulty in the reaction of solid-gas-solid.
Key: The mixture process of fuel and air for gas engines is distinguished from that for diesel engines, hence the character of one type engine is different from the other one: there are mainly
five gases (NO
X , HC, CO and O
2
, CO
2
) in the exhaust of gas motors,
while there are ample O
2
and four other gases mentioned above in the
tailpipe emission of diesel engine. And the presence of abundant
O
2
would inhibit 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 is easier.
(7)What kinds of indoor air pollutants are mostly concerned by
public?
a)Random
b)Combustion by-products
1.CO, CO2, SO2,Formaldehyde,Hydrocarbons,NOx
2.Particulates, polyaromatic hydrocarbons
c)Cigarettes d)Volatile organic compounds
f) Biological contaminants
(8)List the technology strategy for the control of particles.
(9)Give names of three typical kinds of combustion reactors.
Which
has lowest operator temperature among those reactors?
1.Direct flame incineration
2.Thermal incineration
3.Catalytic incineration (has lowest operator temperature) (10)What are the major development problems of
Forced-oxidation limestone wet scrubbing?
(11)What are primary air pollutants and secondary air
pollutants?
Any example?
primary air pollutants are directly from the sources, for examples, NO, CO, SO2.
The secondary air pollutants are from the primary pollutants, such as NO2, NO3, fine particles.NO+CH+O2+sunlight → NO2+O3 (12)Basic strategy of control for particulate pollutants
(three
aspects )?
Impaction 碰撞 Interception 截留 Diffusion 扩散
By forcing the individual particles to contact each other,
By contacting them with drops of water,
By preventing the emission of gaseous Pollutants.