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Answer EPA : Environmental Protection Agency NAAQS : National Ambient Air Quality Standards ACGIH: American Conference of Governmental Industrial Hygienists NESHAP: National Emission Standard for Hazard and Air pollutions CAA: Clean Air Act
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Prof. Jiakuan Yang
Huazhong University of Science and Technology
Air Pollution Control Air Pollution Control EngineeringEngineering
Questions for the Last Lecture
1 Please give three or more Abbreviations about American environmental organizations or air pollution laws.
2 Please explain the four air pollution control philosophies.
Answer
EPA : Environmental Protection AgencyNAAQS: National Ambient Air Quality StandardsACGIH: American Conference of Governmental Industrial Hygienists
NESHAP: National Emission Standard for Hazard and Air pollutions
CAA: Clean Air Act
four air pollution control philosophies
Emission standards philosophy cleanest possible air philosophy, the best technology Air quality standards philosophy zero-damage philosophy Emission taxes philosophy suitable tax for emitter Cost-benefit standards philosophy minimizing the sum of control cost and damage cost and damage cost, get maximum benefit
Lecture Lecture 4 4 Air Pollution Measurements, Emission Estimates
Ⅰ The components of monitoring or sampling deviceⅡ How to get a representative sample?Ⅲ How to determine the concentration correctly?Ⅳ How to select the sampling flow rate?Ⅴ How to select correct analytical methods? Ⅵ How to estimate emissions?
Ⅰ The components of monitoring or sampling device
Two kinds of air pollution measurements methods
ambient monitoring concentrations of pollutants in the air the public breathes
source testingconcentration and emission rates from air pollution sources
Ⅰ The components of monitoring or sampling device
Detector to quantify instantaneous or cumulative amount of pollutant
Gas meter
Sample Gasflow
Inlet device to exclude unwanted
sampling probe heated to prevent condensation
Devices for positioning the sampling probe
Air mover(pump)
Vent to air
Gas sourcesampling determining power
Flow rate
Ⅱ How to get a representative sample?
(1) selecting a suitable sampler site
Generally the ambient air sampler should be located at the place to which the public has free access where the pollutants concentration is the highest.
For ambient sampling
Ⅱ How to get a representative sample?
For source testing
In source testing , for most such stacks the velocity and concentration in the stack vary from point to point and from time to time , so that many separate measurements must be made and averaged.
The section near the bend, less uniform
The section far away the bend, more uniform
Ⅱ How to get a representative sample?
For source testing
Page 66, Figure 4.3
(2) Excluding unwanted materials
a bug screen (昆虫网) PM10 ( particulate matter 10 microns or smaller )
PM2.5 (particulate matter 2.5 microns or smaller )
Ⅱ How to get a representative sample?
(3) Probes are normally heated to prevent condensation of gases on the walls of sampling probe
Ⅱ How to get a representative sample?
Ⅲ How to determine the concentration correctly?
(1) Eliminating the interference effect
For example Determining SO2 concentration passes the gas through a dilute solution of NaOH.
if not considering of CO2 , Cdeterming > Ctrue
Measuring the change in NaOH concentration by simple acid-base titration.
SO2 + NaOH NaSO3 +H2O
CO2 + 2NaOH Na2CO3 + H2O
(2) Averaging the concentration
Ⅲ How to determine the concentration correctly?
Real –time instruments can memorize a lot of values during a period of time .
Time
0 t
Con
cent
ratio
n Average concentration =Cavg = (1/t)∫Cdt
C=area of the shadow t = the time of measurement
(2) Averaging the concentration
Averaging instruments of the concentration of particles.
Average C = Cavg = Total volumeTotal mass
Example4.2Page 69
A PM2.5 sampler ran for 24 hours, average flow of 16.7 L /min , fresh filter : 0.1400 g , gross weight of used filter : 0.1405 g , what is the average PM2.5 concentration ?
335
33
8.201008.2
min6024min
)107.16(
)1400.01405.0(
mg
mg
mgCavg
Ⅳ How to selecting the sampling flow rate?
isokinetic flow sampling for particulates in stack.
Vn : gas velocity inside the sampling probe
Vs : gas velocity in the stack
Vn= Vs
nozzlestack
(1) Vs < Vn
Density of particulate is much larger than density of air, so particulates are more inertial and keep direct.
Cdeterming < Ctrue
Mass keep constant, Vn> VsC =mass
flow nozzle volume
(2) Vs > Vn
Mass keep constant, Vn< VsC =mass
flow nozzle volume
Cdeterming > Ctrue
Ⅴ How to selecting correct analytical methods?
P27, Table 4.1
According to standard sampling methods by EPA
Test methods for major air pollutants in ambient air.
Ⅵ How to estimate emissions?
Emission factors
Page 74~78Sections 4.8~4.9 are studied by yourselves.
This Lecture and the Next Lecture
This Lecture: Chapter 4 Page 63~82
The Next Lecture: Chapter 5 Page 83~118
Homework
Page 794.44.8
DISCUSSION
Topics about Air pollution:
Introducing yourself
Interesting news or information about air pollution your
having read or heard
Your opinions on this Air Pollution course
Your suggestions for Chinese Air Pollution
Other familiar issues about Air Pollution