1、Questions for the Last Lecture Please give three or more Abbreviations about American environmental organizations or air pollution laws.2 Please explain the four air pollution control philosophies.AnswerEPA:Environmental Protection AgencyNAAQS:National Ambient Air Quality StandardsACGIH:American Con
2、ference of Governmental Industrial HygienistsCAA:Clean Air Actfour air pollution control philosophiesq Emission standards philosophy cleanest possible air philosophy,the best technologyq Air quality standards philosophy zero-damage philosophyq Emission taxes philosophy suitable tax for emitterq Cost
3、-benefit standards philosophy minimizing the sum of control cost and damage cost and damage cost,get maximum benefitAir Pollution Measurements,Emission Estimates The components of monitoring or sampling device How to get a representative sample?How to determine the concentration correctly?How to sel
4、ecting the sampling flow rate?How to selecting correct analytical methods?How to estimate emissions?The components of monitoring or sampling deviceq Two kinds of air pollution measurements methodsambient monitoringconcentrations of pollutants in the air the public breathessource testingconcentration
5、 and emission rates from air pollution sources The components of monitoring or sampling deviceDetector to quantify instantaneous or cumulative amount of pollutantGas meterSample GasflowInlet device to exclude unwantedsampling probe heated to prevent condensationDevices for positioning the sampling p
6、robeAir mover(pump)Vent to airGas sourcesamplingdeterminingpowerFlow rate How to get a representative sample?(1)selecting a suitable sampler siteGenerally the ambient air sampler should be located at the place to which the public has free access where the pollutants concentration is the highest.q Fo
7、r ambient sampling How to get a representative sample?q For source testingIn 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 unif
8、ormThe section far away the bend,more uniform How to get a representative sample?q For source testingPage 66,Figure 4.3(2)Excluding unwanted materialsv a bug screen(昆虫网）昆虫网）v PM10 (particulate matter 10 microns or smaller)v PM2.5(particulate matter 2.5 microns or smaller)How to get a representative
9、sample?(3)Probes are normally heated to prevent condensation of gases on the walls of sampling probe How to get a representative sample?How to determine the concentration correctly?(1)Eliminating the interference effectFor example Determining SO2 concentration passes the gas through a dilute solutio
10、n of NaOH.if not considering of CO2,Cdeterming CtrueMeasuring the change in NaOH concentration by simple acid-base titration.SO2+NaOH NaSO3 +H2OCO2+2NaOH Na2CO3+H2O(2)Averaging the concentration How to determine the concentration correctly?v Real time instruments can memorize a lot of values during
11、a period of time.Time 0tConcentrationAverage concentration=Cavg=(1/t)CdtC=area of the shadow t=the time of measurement(2)Averaging the concentrationv Averaging instruments of the concentration of particles.Average C=Cavg=Total volumeTotal massExample4.2Page 69A PM2.5 sampler ran for 24 hours,average
12、 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?335338.201008.2min6024min)107.16()1400.01405.0(mgmgmgCavg How to selecting the sampling flow rate?isokinetic flowsampling for particulates in stack.Vn:gas velocity inside the sampli
13、ng probe Vs:gas velocity in the stackVn=Vs nozzlestack (1)Vs VnDensity of particulate is much larger than density of air,so particulates are more inertial and keep direct.Cdeterming VsC=mass flow nozzle volume (2)Vs VnMass keep constant,Vn Ctrue How to selecting correct analytical methods?P27,Table
14、4.1According to standard sampling methods by EPATest methods for major air pollutants in ambient air.How to estimate emissions?Emission factorsPage 7478Sections 4.84.9 are studied by yourselves.This Lecture and the Next Lectureq This Lecture:v Chapter 4 Page 6382q The Next Lecture:v Chapter 5 Page 83118Homework Page 794.44.8DISCUSSIONTopics about Air pollution:q Introducing yourselfq Interesting news or information about air pollution your having read or heardq Your opinions on this Air Pollution courseq Your suggestions for Chinese Air Pollutionq Other familiar issues about Air Pollution
