出席率 : 15% ( 小考 , 簡答題 , 計算題 , 不定期舉行 ) 平時 評量 : 25% ( 期中考前一小時考試 ) 期中 評量 : 30% ( 計算 , 問答等 )

1. 說明 • 出席率:15% (小考,簡答題,計算題,不定期舉行) • 平時評量:25% (期中考前一小時考試) • 期中評量:30% (計算,問答等) • 期末評量:30% (計算,問答等) • 要求: 正常出席,上課不要講話和走動 • 注意:這是水環系必修課

2. 鄭福田, 2013, 空氣污染控制與管理,中華民國環境工程學會編著, 高立圖書 • USEPA, APTI (Air Pollution Training Institute) http://www.apti-learn.net • USEPA, NSCEP (National Service Center for Environmental Publications ) http://www.epa.gov/nscep/index.html

3. Basic Concepts and Concentration Units

4. Gas Temperature • The Fahrenheit scale • The Celsius or Centigrade scale • Absolute Temperature • Rankine (°R) • Kelvin (K) Source: USEPA, APTI 435: Atmospheric Sampling Course Student Manual

5. Gas Pressure • Barometric Pressure: Barometric pressure and atmospheric pressure are synonymous. Source: USEPA, APTI 435: Atmospheric Sampling Course Student Manual

6. Pressure • Gauge Pressure: The gauge or static pressure is measured relative to the prevailing atmospheric pressure. If the system pressure is greater than the atmospheric pressure, then the gauge pressure is expressed as a positive value. If the system pressure is smaller, then the gauge pressure is expressed as a negative value. • Absolute Pressure: Absolute pressure is the algebraic sum of the atmospheric pressure and the gauge pressure: P = Pb + Pg Where P = absolute pressure Pb = barometric or atmospheric pressure Pg = gauge pressure Source: USEPA, APTI 413: Control of Particulate Matter Emissions Student Manual

7. Pressure Units 1.00 atm. = 14.7 psi = 1,013 mb = 760 mm Hg (torr) = 33.9 ft H₂O = 29.9” Hg = 101325 Pa (a Pascal is a Nm⁻² thus hPa = mb) Source: USEPA, APTI 413: Control of Particulate Matter Emissions Student Manual

8. Standard Conditions Standard pressure:1atm = 101.3kPa = 101.3mb Standard temperature: Source: USEPA, APTI 413: Control of Particulate Matter Emissions Student Manual Standard temperature use by Taiwan EPA is 0℃. The standard condition use in this class is: P=1atm, T= 0℃.

9. Ideal gas law • The ideal gas law states that the volume occupied by a gas is a function of these three parameters: • Number of moles of gas • Absolute temperature • Absolute pressure • The ideal gas law is expressed using this standard equation: Where: V = Volume n = Number of moles R = Universal gas constant T = Absolute temperature P = Absolute pressure

10. Ideal Gas Law • The ideal gas law is accurate as long as the pressures are relatively similar to normal ambient atmospheric pressures. This is almost always the case in air pollution-related work since the pressures usually range from -100 in. W.C. (absolute pressure of 307 in. W.C. at standard conditions) to approximately 50 in. W.C. (absolute pressure of 457 in. W.C. at standard conditions). This range of pressures is relatively small and does not extend to the pressures at which gases become compressible and the ideal gas no longer applies. The ideal gas law applies to mixtures of gases as well as to pure gases. Accordingly, it is very useful for evaluating gas stream properties.

11. Universal gas constant • The value of universal gas constant depends on the units. In this class, we will use R= 0.08206 atm l g-mole-1 K-1

12. Molar Volume • The ideal gas law can also be rearranged to calculate the volume occupied by a mole of gas, called the molar volume: • What is the molar volume of an ideal gas at 0°C and 1 atm? At 25°C and 1 atm?

13. Actual Gas Flow rate • Gas flow rate is a measure of the volume of gas that passes a point in an industrial system during a given period of time. • The ideal gas law tells us that this gas flow rate varies depending on the temperature and pressure of the gas stream and the number of moles of gas moving per unit of time. • When gas flow rates are expressed at actual conditions of temperature and pressure, the actual gas flow rateis being used. • Common units of measure for gas flow rate are Actual Cubic Feet per Minute (ACFM) in the American Engineering system of units and Actual Cubic Meters per Minute (m3/min) in the Cgs system of units. • The gas velocity is calculated simply by dividing the actual gas flow rate by the cross-sectional area of the equipment or duct through which the gas passes.

14. Standard Gas Flow Rate • The standard gas flow rate is the gas flow rate expressed at standard conditions. Standard gas flow rates can be expressed in units of Standard Cubic Feet per Minute (SCFM) and Standard Cubic Meters per Minute (Nm3/min). The SCFM and Nm3/min values are measures of the total quantity of gas being handled per minute and therefore are directly related to the number of gas molecules handled during that time period. They are also the volumes that these amounts of gas occupy at standard temperature and pressure.

15. Volume Correction • Since PV/T = nR, and that, for a given number of moles of a gas, nR is a constant.

16. Exercise The standard volumetric flow rate is 200 Nm3/min in a stack. Determine the actual volumetric flow rate in m3/min, assuming that the actual pressure is 0.98 atm and the actual temperature is 100℃

17. Density

18. Exercise Calculate the density of a gas whose molecular weight is 29 at 1 atm (absolute) and 25 ℃.

19. Concentration Units • Mixing ratio or mole fraction (ppm, ppb, ppt, %, …) • Partial pressure • Mass concentration (mass of X/unit volume of air) • Number density (molecule cm-3)

20. Mixing ratio (mole fraction) • The mixing ratio CXof a gas X (equivalently called the mole fraction) is defined as the number of moles of X per mole of air. It is given in units of mol/mol (abbreviation for moles per mole), or equivalently in units of v/v (volume of gas per volume of air) since the volume occupied by an ideal gas is proportional to the number of molecules. Pressures in the atmosphere are sufficiently low that the ideal gas law is always obeyed to within 1%. • The mixing ratio of a gas has the virtue of remaining constant when the air density changes(as happens when the temperature or the pressure changes). Consider a balloon filled with room air and allowed to rise in the atmosphere. As the balloon rises it expands, so that the number of molecules per unit volume inside the balloon decreases; however, the mixing ratios of the different gases in the balloon remain constant. The mixing ratio is therefore a robust measure of atmospheric composition.

21. Mole Fraction (volume fraction, mixing ratio, or volume mixing ratio) fraction [O₂] = 1/5 percent [Ar] = 1% [H₂O] = up to 4% parts per million (10⁶) [CH₄] = 1.7 ppm parts per billion (10⁹) [O₃] = 30 ppb parts per trillion (10¹²) [CCl₂F₂] = 100 ppt

22. Partial Pressure • The partial pressure PXof a gas X in a mixture of gases of total pressure P is defined as the pressure that would be exerted by the molecules of X if all the other gases were removed from the mixture. • Dalton’s law states that PXis related to P by the mixing ratio CX: Px= CxP • The total pressure is the sum of the pressures of each of the components. • Because the partial pressure value is related to the total pressure, concentration data expressed as partial pressure are not the same at actual and standard conditions. The partial pressure values are also different in American Engineering units and Cgs units.

23. Mass concentration • Three different sets of units are used to express pollutant concentrations in terms of mass per cubic meter: • Milligrams per cubic meter (mg/m3)Micrograms per cubic meter (µg/m3)Nanograms per cubic meter (ng/m3)

24. Mass Concentration • The volume term in the denominator of these units for concentration can be either actual cubic meters or standard cubic meters. It is important to state the basis for the cubic meter volume because concentration data expressed as mass per cubic meter do not have the same numerical values at actual and standard conditions.

25. Exercise In a stack, the actual pressure is 0.98 atmand the actual temperature is 100℃. If the concentration of PM10 is 10mg/M3. Determine the concentration of PM10 in mg/NM3.

26. Converting Concentration Data fromUnits of Mass Per Cubic Meter to ppm

28. 練習: 請問上題中的氣體移到1atm, 0 ℃時, SO2濃度變為多少ppm?多少μg/m3?

29. Exercise A 25°C gas stream with a flow rate of 150m3/min has a heptane(C7H16) concentration of 20,000 ppmv. Determine the mass flow rate of heptane.

30. Wet vs. Dry basis concentration • Water vapor is commonly present in a heated gas stream, e.g., combustion of a hydrocarbon fuel. • Water vapor can condense as temperature cools down. The amount varies and is very sensitive to temperature. • To prevent the variation, standards are written to correct to "dry" conditions when expressing concentrations.

31. Oxygen Basis Conversions • Pollutant concentrations for combustion sources specified in Taiwan air pollution regulations are often expressed on a 6% oxygen basis. Different oxygen basis is used for different emission sources. • These formats are used to account for dilution air that often enters through fans, cracks in ductwork expansion joints, and air pollution control equipment. The oxygen formats for the concentration limit ensure that regulations are fair for all sources, regardless of the extent of ambient air dilution of the effluent gas stream prior to the continuous emission monitor or the emission test location. It is also useful for comparing emissions from different facilities having substantially different oxygen concentrations in the gas stream. Source: http://www.epa.gov/eogapti1/bces/module2/oxygen/oxygen.htm

32. Oxygen Basis Conversions • The standard equation for the correction of concentration to a specific oxygen level is as follows: Where: Cs = Gas concentration at standard O2 level Cm = Gas concentration at measured O2 level Os = Oxygen concentration at standard level Om = Oxygen concentration at measured level The value, 21% in the above equation, is the oxygen concentration in the atmosphere. A measured NOx concentration of 45 ppmv (dry basis) in a gas having 7 volume % O2is 45 × ( 21 - 6 ) ÷ ( 21 - 7 ) = 48.2 ppmv (dry basis) of NOx when corrected to a gas having a standard O2content of 6 volume %.

33. AQI • The Air Quality Index (AQI), formerly the Pollutant Standards Index (PSI), is a uniform system developed by U.S. EPA to enable the public to determine whether air quality levels in a particular location are good, moderate, unhealthful, or worse. • The number of air pollutants makes it difficult to communicate the general condition of air quality in a community.AQIis easier to communicate and understand • In June 2000, EPA updated the PSI index and renamed it Air Quality Index (AQI). The AQI includes a new health risk category (unhealthy for sensitive groups) and two additional pollutants: ozone averaged over 8 hours, and fine particulate matter (PM 2.5). Source: http://scorecard.goodguide.com/env-releases/def/cap_psi.html

34. AQI • AQI methodology • Designed to communicate relative risk to public health from criteria pollutants • Criteria pollutant measurements used in the AQI estimation: O3 8-hr, O3 1-hr, PM2.5, PM10, CO, SO2, NO2 • AQI above 100 means a criteria pollutant has exceeded its NAAQS Source: MARAMA

35. AQI • AQI methodology • Daily concentrations of each criteria pollutant (except lead) at a monitoring site are used to interpolate an AQI for that pollutant from the table below • Reported AQI is the highest of the individual pollutant AQIs ppm ppb µg/m3 µg/m3 ppm ppb ppb Source: MARAMA

36. AQI • A city’s monitoring site reports the air pollutant concentrations shown. The AQI is assessed from these measurements. Conclusion: 122 is the maxof the individualAQIs, hence anAQI of 122 is reported. AQI values from: http://airnow.gov/index.cfm?action=aqi.conc_aqi_calc Source: MARAMA

37. 空氣污染指標(Pollutant standard index, PSI) • 空氣污染指標為依據監測資料將當日空氣中懸浮微粒(PM10)(粒徑10微米以下之細微粒)、二氧化硫(SO2)、二氧化氮(NO2)、一氧化碳(CO)及臭氧(O3)濃度等數值，以其對人體健康的影響程度，分別換算出不同污染物之副指標值，再以當日各副指標之最大值為該測站當日之空氣污染指標值(PSI)。

38. 污染物濃度與污染副指標值對照表

39. PSI值對人體健康的影響