Elective Exam 1 3 Reviewer PDF

REVIEWER: ELECTIVES 1 LAYERS OF THE ATMOSPHERE Characterized by variations of temperature and EXAM 1: Air Pollution Control pressure with height....

REVIEWER: ELECTIVES 1 LAYERS OF THE ATMOSPHERE Characterized by variations of temperature and EXAM 1: Air Pollution Control pressure with height. Basis for Layer Identification: temperature Earth’s Atmosphere profile variation with respect to altitude. Early atmosphere of the earth is composed of the mixture of CO2, N2, H2O (g), and small traces of H2. The early atmosphere of Earth was a mildly reducing chemical mixture, whereas the present atmosphere is strongly oxidizing. Composed primarily of gases N2 (78%), O2(21%), and Ar (1%), whose abundances are controlled over geologic timescales by the biosphere, 1. Troposphere uptake and release from crustal material, and o The lowest layer of the atmosphere: Earth’s degassing of the interior. surface up to Tropopause (10-15km) o Decreasing temperature with height and Water vapor is the 2nd most abundant rapid vertical mixing. constituent; it is found mainly in the lower o Where the weather phenomena occur. atmosphere and its concentration is highly variable, reaching concentrations as high as 3%. 2. Stratosphere o Abundance of water vapor is controlled by o Tropopause up to Stratopause (45-55km) evaporation and precipitation. o Increasing temperature with height and slow vertical mixing. Atmospheric Chemistry o Planes fly in lower stratosphere. Pioneered in the 18thcentury by Joseph 3. Mesosphere Priestly, Antoine-Laurent Lavoisier, and Hendy o Stratopause up to mesopause (80-90km) Cavendish while attempting to determine the o Decreasing temperature with height to the components of the atmosphere. mesopause (coldest point) and rapid vertical mixing. It is the study of mechanisms of molecule o Where meteors burn up. interaction when introduced into the atmosphere and how their reactions affect 4. Thermosphere atmospheric composition and properties. o The region above the mesopause is characterized by high temperatures The driving force for chemical reactions in because of absorption of short-wavelength atmosphere is sunlight. radiation (N2 and O2) and rapid vertical Study of Atmospheric Chemical Processes: mixing. 1. Determining basic chemical steps in the o Where Aurora borealis occurs. laboratory. 5. Ionosphere region 2. Quantifying atmospheric emissions and o Between the upper mesosphere and lower removal processes. thermosphere 3. Incorporating all the relevant processes in o Extreme UltraViolet (EUV) and x-ray solar computational models of transport and radiation ionizes the atoms and molecules transformation. thus creating a layer of electrons. 4. Comparing the predictions with atmospheric 6. Exosphere observations to assess the extent to which our o Outermost atmosphere region (>500km) basic understanding agrees with the actual o Where strong gas molecules escape atmosphere. gravity. PRESSURE AND MIXING RATIONS IN THE particularly when spatiotemporal variation is ATMOSPHERE involved. Pressure When water vapor is involved in total volume Newtons/meter2 (N/m2) or Pascals (Pa) Atmospheric pressure at Earth’s Surface = of the gaseous substance meaning that 1.01325x105 Pa mixing ratio will vary with humidity. It has become common use in atmospheric chemistry to describe mixing ratios by the following units: Equation of pressure at varying heights: ATMOSPHERIC DYNAMICS Involves observational and theoretical analysis of all motion systems of meteorological significance, including such diverse phenomena as thunderstorms, tornadoes, gravity waves, tropical hurricanes, extra tropical cyclones, and global-scale Number Concentration of Air (sea level) and as a circulations. function of Altitude Practical objectives include improving weather prediction, developing methods for prediction of short-term (seasonal and inter annual) climate degree, and understanding the implications of human-induced perturbations (e.g., increased carbon dioxide concentrations or depletion of the ozone layer) on the global climate. Mixing Ratios Meteorology the ratio of the amount (or mass) of the The study of the atmosphere and motions substance in each volume to the total within the atmosphere on short-time scales. amount (or mass) of all constituents in that Commonly known as ‘weather,’ meteorology volume (excluding particulate matter/water). focuses on the atmospheric variables related to current or near-future conditions. It is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on Concentration (mol m−3) depends on weather forecasting. pressure and temperature through the ideal- gas law. Several weather elements describe the atmosphere such as temperature, humidity, Mixing ratios are just mole fractions, are precipitation amount and type, wind direction therefore better suited than concentrations and strength, atmospheric pressure, and to describe abundances of species in air, cloud cover. Atmospheric Stability In the troposphere air temperatures normally decrease as altitude increases, the faster It is a measure of the atmosphere's tendency the rate of decrease, the more unstable the to encourage or prevent vertical motion, and atmosphere. vertical motion is directly correlated to o Under certain conditions, however, a different types of weather systems and their temporary temperature inversion may severity. occur, during which time the air temperature increases with It is also the tendency of air to rise or not, increasing altitude, and the which helps determine whether clouds will atmosphere is very stable. be deep and produce precipitation, or thin with no precipitation, or simply not form at all. If air tends to rise easily, the atmosphere is said to be unstable, and deep clouds and precipitation are likely to form. In unstable conditions, a parcel of air will be warmer than the surrounding air at altitude. If air tends to resist rising, the atmosphere is said to be stable, which usually results in Implications of Inversion clear skies and dry weather. Atmospheric Inversion It is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to a "temperature inversion". Air Pollution trapped over the city of Almaty, Kazakhstan during a temperature inversion. o Areas with heavy pollution are prone to unhealthy air and an increase in smog when an inversion is present because they trap pollutants at ground level instead of circulating them away (smog). They are areas where the normal decrease Temperature inversions prevent the upward in air temperature with increasing altitude is mixing and dispersion of pollutants and are reversed and air above the ground is warmer the major cause of air pollution episodes. than the air below it. Inversion layers are significant to Inversion layers can occur anywhere from meteorology because they block close to ground level up to thousands of feet atmospheric flow which causes the air over into the atmosphere. an area experiencing an inversion to become stable (can result in various types of weather The degree of atmospheric instability patterns). depends on the temperature gradient Some of the most significant consequences (temperature change with altitude). of temperature inversions: freezing rain.  Develops with a temperature inversion in a cold area because snow melts as it moves through the warm inversion layer. The precipitation then continues to fall and passes through the cold layer of air near the ground. When it moves through this final cold air mass it becomes "super-cooled". Turbulence It is a highly irregular (violent) motion of the wind. It is characterized by random and Convection: erratic motions, swirls and eddies of varying sizes. In the tropics, near the equator, warm air rises. It is capable of mixing air with different When it gets about 10-15 km (6-9 miles) properties efficiently and thus, it is important above the Earth surface it starts to flow away to meteorology and air quality. from the equator and towards the poles. Because of the mixing capacity of Air that rose just north of the equator flows turbulence, chimney plumes are diluted north. and spread over larger volumes than they Air that rose just south of the equator flows south. When the air cools, it drops back to the ground, flows back towards the Equator, and warm again. The, now, warmed air rises again, and the pattern repeats. Coriolis Effect But because Earth is spinning, the air that moves north and south from the equator also turns with the spin of the Earth. Air going north turns to the right, air traveling south turns to the left. would be without turbulence. Strong local peaks of pollution are Thus, it is the power of Earth’s spin to turn prevented, and otherwise clean air is flowing air along with it. polluted. Thus, the air pollution meteorologist must Because the Earth does spin, convection is distinguish between conditions of strong divided into three cells north of the equator and weak turbulent mixing. and three south of the equator. Global Atmospheric Circulation In the northern hemisphere, the winds flow to A consistent movement pattern followed by the right and are called northeast trade the air in the atmosphere despite winds. disturbances (inversions, turbulence, weather fronts, and storms). In the southern hemisphere the winds flow to It is caused by the Sun’s heat on Earth being the left and are called the southeast trade more focused at the equator. winds. CONVECTION CELLS The warmer air from the tropics is lighter than the dense, cold polar air and so it rises 1. Hadley Cells as the two air masses meet creating an LPZ. This uplift of warmer air causes low pressure at the surface and the unstable weather conditions that are associated with the mid-latitude depressions (causing wet and windy weather in UK). 3. Polar Cells Polar high is when air from the poles is cooled and sinks towards the ground forming The heated ground at the equator causes air high pressure. It then flows towards the to rise creating an low pressure zone (LPZ) on lower latitudes. the earth’s surface. At about 60 degrees N and S, the cold polar As the air rises, it cools and forms into storm air mixes with warmer tropical air and rises clouds. upwards, creating LPZ called the subpolar Then, the air separates and starts to move at low. both north and south towards the poles. Polar front is the boundary between the When it reaches about 30° north and warm and cold air. It accounts for a great south,0020the air cools and sinks towards deal of the unstable weather experienced in the ground forming the subtropical high- these latitudes. pressure zone. THERMODYNAMICS AND THE ATMOSPHERE As the air sinks, it becomes warmer and drier. This creates an area of little cloud and low The Ideal Gas Law rainfall, where deserts are found. The air completes the cycle and flows back An equation of state describes the towards the equator as the trade winds. relationship among pressure, temperature, and density of any material. 2. Ferrel Cells Atmospheric gases, whether considered individually or as a mixture, obey the following ideal gas equation: The First Law of Thermodynamics For the atmosphere, a more usable form of the First Law of Thermodynamics is: Occurs at higher latitudes (between 30 degrees and 60 degrees N and 30 degrees and 60 degrees S) Air on the surface is pulled towards the poles. In the atmospheric form of the First Law of These winds pick up moisture as they travel Thermodynamics, Cp*ΔT can also be redefined over the oceans. as Enthalpy (h), a term to quantify the total heat At around 60 degrees N and 60 degrees S, content of an air parcel. they meet cold air, which has drifted from the poles. FRAMEWORKS FOR UNDERSTANDING THE ATMOSPHERE Defined for: environment, dry air parcel, and saturated air parcel (moist) lapse rates. Eulerian framework A fixed framework, relative to a single point Environmental lapse rate can be observed by on the Earth’s surface. using atmospheric sensors attached to When a weather forecast is done for a given weather balloons (radiosonde). location on Earth or when you look at a dataset from one weather station, you are The environmental lapse rate varies viewing the atmosphere from a Eulerian depending on time of day, altitude, latitude, perspective — that is, how the wind and air land surface properties, heat fluxes, and air travels past a fixed point. movement. Temperature and moisture advection, properties that travel with and are carried by Can be classified as Dry Adiabatic or Moist the wind are the concerns of this framework. Adiabatic Lapse Rate. Langrarian Framework Dry Adiabatic Lapse Rate (DALR) It is a framework that is constantly moving It is concerned with unsaturated air, i.e., air and travels with the air. which carries all the available moisture in gas It is useful when looking at motions within the form. atmosphere (rising or sinking air) Used to see how properties within the rising Relationships between pressure and plume of air are changing. temperature lead to a simple linear relation Analogy: a small dust particle moving between temperature and altitude for rising exactly with the wind and observing how the or sinking air. atmosphere changes. An air parcel that contains no liquid water or Air Parcels (Mass of Air) ice (none of the moisture in the parcel has Useful for distinguishing processes condensed into liquid, no saturation or latent happening within the air, versus processes heat release), will cool at the DALR. (DALR = happening within the environment. 9.8°C / km) It is an amorphous bubble or blob of air, Moist Adiabatic Lapse Rate roughly the scale of a party balloon or a hot air balloon that contains uniform properties Moist adiabatic lapse rate is NOT a constant. (temperature, density, pressure) throughout. It depends on the temperature of saturated A simplified theoretical construction used to air parcel. discuss and examine motions and instability in the atmosphere. Higher air temperature = smaller moist adiabatic lapse rate LAPSE RATE The change in temperature with altitude, When warm, saturated air cools, it causes specifically a reduction in temperature with more condensation (and more latent heat altitude. release) than for cold, saturated air. A positive lapse rate indicates that the temperature is decreasing with increasing height, while a negative lapse rate indicates a “temperature inversion” meaning that the temperature is increasing with increasing height. Pasquill Stability Class EXAM 2: RA 8749 and Other Related It is a method of categorizing the stability of Regulations a region of the atmosphere in terms of the horizontal surface wind, the amount of solar Issuances and Policy Updates: Memorandum radiation, and the fractional cloud cover. Circulars (MCs) And Department Administrative Orders (DAOs) Related to RA 8749 Stability – is the e tendency of the RA 8749 (Philippine Clean Air Act of 1999) – an atmosphere to resist or enhance vertical act providing for a comprehensive air pollution motion (turbulence). control policy and for other purposes. o related to both the lapse rate driven by the boundary layer energy budget, Related Regulations and wind speed together with MC / DAO Description surface characteristics (roughness). MC Dated Focus on Ambient Air 02/03/09 Monitoring to Ensure The turbulence of the atmosphere is by far Protection of Public Health the most important parameter affecting MC 2007-03 Permitting & Emission dilution of a pollutant. The more unstable the Compliance Guidelines atmosphere is, the greater the dilution. MC 2007-22 Guidelines on the Requirements for Continuous Pasquill Stability Class is based on 3 Emission Monitoring System characteristics: (CEMS) & Other Acceptable o Intensity of Solar Radiation Protocols o Near-surface Wind Speed MC 2008-04 Guidelines on Air Dispersion o Extent of Nighttime Cloud Cover Modelling Memo From Instruction Relative to the Sec Dated Oct. Installation of CCTV Camera 30, 2014 on Stacks of Fuel-Burning Stationary Equipment Nationwide as per Rule XXV of the IRR DAO 2004-26 Amending the Permitting Requirements of DAO 2008- 81 or Implementing Rules & Regulations of CAA MC 2016-08 Clarificatory Guidelines on the Conduct of Stack Emission Tests by DENR-EMB and its Accredited Third-Party Source Emission Testing Firms MC 2011-004 Clarificatory Guidelines on DAO 2000-81, Part VI, Rule XIX, Section 13 (IRR of RA 8749)  MC 2007-03: Annex 2 (Categorization of Sources) partially amended by MC 2016-008 Category (Standby Generators) New & Existing Sources Source Large Medium Small Exempted Diesel Generator ≥ 1259 𝑘𝑊 1249 − 600 𝑘𝑊 𝟓𝟗𝟗 − 𝟑𝟎𝟎 𝒌𝑾 ≤ 300 𝑘𝑊 Once during the first Do not require Twice per year year of its operation. emission testing Frequency of Sampling for each year of Annually Thereafter, it shall be for permitting operation tested once every purposes second year Category (Steam Boilers) New & Existing Sources Steam Boilers (Bio- ≥ 251 HP 250 − 100 HP 99 − 50 HP ≤ 50 HP mass/Diesel Fired) Once during the first Do not require Twice per year year of its operation. emission testing Frequency of sampling for each year of Annually Thereafter, it shall be for permitting operation tested once every purposes second year Category (Other Sources) New & Existing Sources Has potential Can Emit 100 to Emit less Has Potential to Emit Less than or Other Sources tons or more than 100 tons less than 30 tons to equal to 10 tons per year to 30 tons per 10 tons per year per year year Once during the first Do not require Twice per year year of its operation. emission testing Frequency of sampling for each year of Annually Thereafter, it shall be for permitting operation tested once every purposes second year Environmentally Significant Source DAO 2007-22: Guidelines on the Installations of Continuous Emission Monitoring Systems Any source of emissions of hazardous air (CEMS) pollutants included on the list of Priority Chemicals in DAO 1998-58 Existing major source (Rule XXV IRR) The principal emission sources of petroleum Any new or modified source (regardless of refineries, petrochemical works, smelters, industry) w/ potential to emit at least 750 cement kilns, and steel, ferro-alloy and tons/year of any regulated pollutant. glass-making plants. Having the potential to emit more than 100 MC 2007-03 tons/year but less than 750 tons/year any of All sources using Bunker Fuel Oil, Blended the regulated pollutants under Section 4, Fuels involving Bunker Fuel Oil, or fuels with RULE IX of the IRR: CO, NOx, SO2, TSP, PM10, a sulfur content of 1% or more, shall be VOCs, H2S tested twice each year for each year of operation. Installation exemptions: Stand-by, emergency, seasonal, and Large and environmentally significant intermittently operating facilities that sources also require dispersion modelling to operate < 500 hours per year. demonstrate their compliance with the source specific ambient air quality standards Provided that these sources may be subject prior to initial permitting. to 3rd Party Monitoring or other means as approved by EMB. MC 2009-04 Amendment of Annex 2 of MC 2007-003 for Large Standby Electric Generator Predictive Emission Monitoring System using Diesel Fuel (PEMS) – refers to a system that determines the gas concentration (mass emission rate) based on process data and generates an output proportional to the gas concentration (emission rate) without requiring the CEMS specified under USEPA 40 CFR Part 60 Appendix B or equivalent. o PEMS can either be parametric or predictive o A mathematical model that predicts Policy Update-Memo from Secretary Dated Oct. the gas concentration in a stack 30, 2014: Enforcement of Section 5 of Rule XXV based on a set of operating data: of DAO 2000-81 ▪ fuel flow rate ▪ temperature Requiring all owners or operators of ▪ stack excess oxygen Stationary fuel-burning equipment to install ▪ pressure closed circuit television (CCTV) cameras on ▪ heat input all their stacks with receiver located in the ▪ fuel analysis and others boiler room, furnace room or control room. CCTV cameras should be web-based and capable of real-time viewing with night vision and readily accessible by DENR-EMB. Requirement for the issuance of POA Emission Sources. MC 2016-008: Section 5 (Source specific air MC 2011-004: Clarificatory Guidelines on the pollutants (SSAP) for fuel combustion sources Reporting of Breakdown of Air Pollution for permitting purposes) Source Installation or Equipment (APSEs) and Air Pollution Control District (APCDs) AIR POLLUTION Frequency SOURCE INSTALLATION OR EQUIPMENT of Fuel Type SSAP (APSE) Operation The breakdown and non-operation of an Diesel, APSE does not cover 24-hour reportorial Natural CO, requirement. Instead, the same may be Standby Gas, LPG, NOx included in the SMR. Internal Biogas, etc. Combustion Bunker Fuel Engine The breakdown of an APCD lasting up to one Oil (BFO) or PM, (Generator (1) hour only is likewise not covered in the mixed fuel CO, sets. Etc.) Continuous (BFO mixed NOx, 24-hour reportorial requirement. Instead, the with LSFO, SOx same may be included in the SMR. etc.) Liquid fuel The breakdown of an APCD lasting more oil: BFO or PM, CO, than one (1) hour is covered in the 24-hour mixed fuel NOx reportorial requirement. Regardless of Operation Frequency (BFO mixed SOx with LSFO) External PM, CO, Combustion Solid Fuel: NOx, Engine Coal SOx (Boilers, fuel metals burning steel Wood, rice mill furnace, hulls, etc.) – biomass, PM, CO baggasse, etc. Textile PM, CO, Waste metals Solid Fuel: PM, CO, coal, AFRs NOx, including SOx, liquid fuel for start up metals Cement Kiln Bunker Fuel Oil (BFO) or PM, CO, mixed fuel NOx, (BFO mixed SOx with LSFO, etc.) BAGHOUSE FILTERS – DESIGN AND Insufficient CFM = Ineffective ventilation, SIZING CONSIDERATIONS causing: o equipment damage o excessive emissions o reclaimed product loss o hazardous environment (facilities with explosive dust/materials) NOTE: Low CFM can also have an adverse effect on other parameters. Vacuum Pressure (Suction) & Static Pressure (Static Resistance) The basis of a properly functioning dust collection system measured in inches of water gauge (w.g.). The system fan must supply suction enough Baghouse System Design Variables to pull the materials from: the collection point(s) Engineers must design and run a dust to ductwork collection system in such a way that the (4) to the baghouse, then major design parameters are maintained: through the filters, then o Cubic Feet per Minute (CFM) out to the exhaust o Feet per Minute (FPM) o Vacuum Pressure For it to supply suction it must overcome o Air to Cloth Ratio (or A/C) resistance to air flow (differential pressure) caused by filters and ductwork. Any changes to any of these crucial system parameters will cause performance issues Static pressure (static resistance) is a throughout the system. measurement of resistance created by the ductwork and filters in the baghouse (measured in inches of water gauge). Airflow in CFM (Cubic Feet per Minute) A measurement of how much air is moved by Insufficient Vacuum & Static Pressure the system and the sizing basis for causes: baghouses. o Suction loss at the collection points o Insufficient ventilation Larger space being vented (greater number o Reduced air velocity of pickup points) = more CFM required o Caloy was here o Product Dropout CFM generated by the system fan can be fixed or adjusted. o But the total CFM generated by the system fan can be affected by changes in altitude, ductwork restrictions, sizing, as well as air-flow resistance caused by the system (ductwork + filters). Air Velocity and Minimum Conveying Velocity Sizing of the Dust Collection System Air velocity within the system is measured in 1. Find the Minimum Conveying Velocity (ft/m) feet per minute (ft/m). Determine from a credible source the minimum velocity for the material that the Air speed is related to CFM as follows: system will handle. 𝑓𝑡 𝐶𝐹𝑀 Most materials require between 3,500 𝑎𝑖𝑟 𝑠𝑝𝑒𝑒𝑑 ( ) = 𝑚 𝑐𝑟𝑜𝑠𝑠 𝑠𝑒𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑜𝑓 𝑑𝑢𝑐𝑡 ft/m to 5,000 ft/m. The system must be carefully engineered to keep air speed within an acceptable range to prevent: o High air velocity – can quickly wear holes in the ductwork (abrasion). o Low air velocity – can cause dust buildup within the ductwork and lead to poor dust capture at inlets. Dust buildup within the ductwork can cause 2. Identify Total Number of Primary and major safety hazards: Secondary Sources o Provide ample fuel for combustible dust Primary sources fire (explosion) if combined with an ignition source (spark/ember). Need constant venting whenever the system o Collapse of the duct caused by weight is running. buildup of dust. Classifying all sources as primary will cause an unnecessary large system (expensive initial installation and operation). Air to Cloth Ratio Secondary sources It is the gas volume ratio (ACFM) to total cloth area (ft2) of the baghouse. They do not always run simultaneously 𝒇𝒕 𝒂𝒊𝒓 𝒗𝒐𝒍𝒖𝒎𝒆 without primary sources and sometimes they 𝒂𝒊𝒓 𝒕𝒐 𝒄𝒍𝒐𝒕𝒉 𝒓𝒂𝒕𝒊𝒐 ( )= 𝒎𝒊𝒏 𝒎𝒆𝒅𝒊𝒂 𝒂𝒓𝒆𝒂 shut down completely. A baghouse must have enough filters to Common in wood/metal milling, fabrication capture dust from the airstream. and manufacturing shops. Maintaining an adequate air-to-cloth ratio Classifying too many sources as secondary allows peak baghouse operation (99.9% dust will result in an undersized system collection). (insufficient capacity for normal operations). o This will cause production Unmaintained/Insufficient filter medium bottlenecks (inadequate ventilation causes: causing health/safety hazards). o Decreasing collection efficiency o Results in excessive emissions Plan with the objective of defining the o Violation of pollution regulations heavies use scenario so you can size your o Creation of a hazardous environment system to meet it. A good rule of thumb is to oversize the system by roughly 10% to ensure proper operation and accommodate any future expansions. 3. Calculate Total CFM Required for Each Where the next branch connects, add Branch the CFM of both lines together and 1. Determine how much CFM you need at determine what duct size needed for each branch of your system. If your that amount of CFM at given velocity source equipment has a built-in collar or (ft/m). port, identify the diameter. Increase duct size accordingly then proceed to mapping the trunk forward. 2. On larger resources such as kilns, Repeat the process and only increase furnaces or processing equipment or for the duct size at each spot where a sources with custom-designed venting, primary source connects to the main identify CFM required by consulting with trunk. the equipment OEM or by using industry- Continue mapping your main trunk best practice methods. (ensure to connect all primary and secondary sources) until you reach 3. Find the fitting duct size and match to the collector. column with the required conveying velocity to find the needed CFM for each 3. Combine CFM required by each branch branch. where (2) primary branches meet and calculate the duct size needed to provide 4. Create a System Layout and Size Your Main enough CFM for both branches at the Trunk required air velocity (round up to the largest duct size). 1. Make a rough floor plan showing the location of each piece of equipment. 5. Calculate Static Pressure (SP) of Your Take your primary & secondary System sources and create a rough floor plan Refers to the amount of resistance to for every piece of equipment. airflow created by friction and channeling Then, map out the ductwork of air throughout the ductwork. connecting each piece back to the collector. The system will only function properly if NOTE: Place your dust collector in a the system fan can overcome the central, convenient location. resistance caused by the ductwork and NOTE: Safety regulations covering the baghouse. applications involving combustible dust may mandate placing the The system will also only function baghouse outside or on an exterior properly if SP of the system is wall (along with explosion venting to accurately calculated. the outside). To determine the total static pressure 2. Sketch ductwork layout connecting each (SP) of the system you must add the three piece of equipment together and running elements together: all the way back to the dust collector. o The branch with the greatest SP Start at the source farthest away from (worst branch) collector. o Main trunk line SP Using calculated required CFM for o The resistance created by the each branch (step 3), note the dust collectors (precleaners, diameter of the duct needed and map filters) it out running towards the collector to For most, baghouses plan on a maximum the point where the next branch 5”-7” of static resistance (allows for connects (Note the length of each run flexibility). of duct).  EXAM 3: Different Types of Air Particulate matter (PM) Pollution and Their Sources Mercury and more NOTE: certain pollutants may be both primary and secondary pollutants (e.g. NOx). Air Pollutants It can harm when it accumulates in the air in Secondary Air Pollutants high enough concentrations. These are pollutants which are not emitted Urban smog, particle pollution and toxic directly into the air but are formed in the pollutants pose serious health concerns. atmosphere by chemical reactions between People with high exposures to certain air other pollutants and atmospheric gases. pollutants may experience: irritation of the eyes, nose and throat. Major concern as they can be formed from wheezing, coughing, chest tightness and various compounds. Photochemical smog is breathing difficulties. a phenomenon caused by interactions of worsening of existing lung and heart primary pollutants with other molecules in problems, such as asthma; and the air (oxygen, water, hydrocarbons) increased risk of heart attack. o Photochemical smog is made up of Cancer various secondary pollutants like Damage in the immune, neurological, ozone, peroxyacyl nitrates (PANs), reproductive, and respiratory systems. and nitric acid. Angina – chest pain or discomfort caused by insufficient oxygen rich blood in the Different types of secondary pollutants heart. include: o Ozone (O3) Primary Air Pollutants o Sulfuric acid and nitric acid (component of acid rain) Any type of pollutant directly into the o Particulate matter (PMs) environment. o Nitrogen dioxide (NO2) o Peroxyacyl nitrates (PANs) and more They differ from secondary pollutants because secondary pollutants must form in These substances essentially "cook up" in the atmosphere, whereas primary pollutants the atmosphere and are typically found do not. downwind of primary emissions due to the time it takes to produce them. They can be emitted from many sources including cars, coal-fired power plants, When primary pollutants cannot be natural gas power plants, biomass burning, dispersed due to inversion layers in the natural forest fires, volcanoes, etc. atmosphere, smog is formed over the area where they were produced. Major contributors to formation of secondary o This is why smog is so prominent in warm, pollutants because this is what causes dense cities. Secondary pollutants are harmful ground level ozone to form, along very sensitive to weather patterns. with smogs in urban areas. Different types of primary pollutants include: Nitrogen oxides (NOx) Carbon monoxide (CO) Volatile organic compounds (VOCs) Sulfur oxides (SOx) Photochemical Smog (Brown Haze) o Fine Particles (PM2.5). Particles up to 2.5 microns in diameter are so small that only It is a type of smog produced when an electron microscope can detect them, ultraviolet light from the sun reacts with although large concentrations can be nitrogen oxides in the atmosphere. seen as haze. Power plants, motor Largest contributor is automobiles, while vehicles, wood burning and some coal-fired power plants and some other industrial processes generate fine power plants also produce the necessary particles. Because they are so tiny, these pollutants to facilitate its production. particles can penetrate deeply into the lungs. Four Main Sources of Air Pollution o Coarse Particles (PM10). Particles Mobile Sources – such as cars, buses, between 2.5 and 10 microns in diameter planes, trucks, and trains. (main contributors) come from a variety of sources, such as wind-blown soil and airborne residue Stationary Sources – such as power plants, from business and industry. Individual oil refineries, industrial facilities, and particles cannot be seen with the naked factories eye, but collectively can appear as haze, dust or soot. Area Sources – such as agricultural areas, cities, and wood burning fireplaces Carbon Monoxide (CO) Natural Sources – such as wind-blown dust, It is a poisonous gas that forms when the wildfires, and volcanoes carbon in fuels such as gasoline, heating oil, natural gas, wood and charcoal does not burn completely. It is both dangerous and CRITERIA POLLUTANTS deadly. Ozone (O3) Air concentrations of carbon monoxide can be particularly high in areas with heavy traffic A gas composed of three oxygen atoms that congestion. Other sources include industrial can be either beneficial or harmful boilers, waste incinerators and natural depending on where it forms: events such as wildfires. o Good Ozone. Many miles above ground CO levels are higher during cold winter in the Earth’s upper atmosphere, ozone weather because vehicles work harder and occurs naturally and shields from the burn fuel less efficiently. Sun’s harmful ultraviolet rays. Lead o Bad Ozone. Near the ground, ozone is formed when heat and sunlight cause A soft and highly toxic elemental metal found emissions of cars, power plants, naturally in the environment. It is usually factories and other sources to extracted from ore deposits along with chemically react and form “smog”. copper, silver and zinc. Particulate Matters (PM) The major source of lead emissions has been motor vehicles and industry because It includes a mixture of solids and liquid of the past use of leaded gasoline until it was droplets. Some are emitted directly, while phased out (1970s). others are formed when other pollutants react. They come in a range of sizes: Commercial and industrial uses include cables, pipes, paints, and pesticides. Metal processing plants are the most significant remaining sources of lead in the air today. Sulfur Dioxide (SO2) HEALTH AND ENVIRONMENTAL EFFECTS It is a colorless, reactive gas produced from Health Effects power plants, industrial boilers, and other facilities that burn sulfur-containing fuels Short-term exposure can lead to eye (coal and oil). irritation, nausea or difficulty in breathing. Long-term exposures may result in damage Concentrations are highest near industrial to the respiratory, nervous or reproductive complexes. systems, birth and developmental defects, and other serious health problems. Nitrogen Dioxide (NO2) or NOx Factors determine the severity of pollutant It is one of the groups of gases that contain effects on a person/population including nitrogen and oxygen in varying amounts and level, duration, and frequency of exposure, react with other pollutants to form ground- the toxicity of the pollutant, and the overall level ozone. health of people who are exposed. These gases are produced when fuel is Mercury can deposit into soil or surface burned at high temperatures. waters where they are taken up by plants, ingest by animals, thus, getting distributed Primary sources include motor vehicles, into the food chain (very harmful over time). electric utilities, industry, commercial businesses and homes. Sensitive populations include children, older adults, people who are active outdoors and some people with heart or lung diseases, such as asthma. TOXIC AIR POLLUTANTS Environmental Effects Also known as air toxics, these are pollutants that at sufficient concentrations and exposure Acid Rain are known or suspected to cause cancer, other serious health problems or damage to the It is precipitation containing harmful amounts environment. of nitric and sulfuric acids. These acids are formed primarily by nitrogen oxides and Three main types of air toxics: sulfur oxides released into the atmosphere when fossil fuels are burned. Gases. These include benzene, toluene, and xylene, which are all found in gasoline. Acid rain damage trees and causes soils and water bodies to acidify, making the water Liquid Aerosols. Perchloroethylene, a dry- unsuitable for some fish and other wildlife. cleaning agent, and methylene chloride, an industrial solvent, are among these. It also speeds up the decay of buildings, statues and sculptures that are part of our Particles. Examples include heavy metals national heritage. such as cadmium, chromium, lead and mercury, and polycyclic aromatic The ecological effects of acid rain are most hydrocarbons from the burning of fossil fuels clearly seen in aquatic environments, such and waste. as streams, lakes and marshes where it can be harmful to fish and other wildlife.  As it flows through the soil, acidic rainwater This short duration of higher acidity (i.e., can leach aluminum from soil clay particles lower pH) can result in a short-term stress and then flow into streams and lakes. on the ecosystem where a variety of organisms or species may be injured or killed. More acid IN = More aluminum OUT. Nitrogen Pollution Generally, the young of most species are more sensitive to environmental conditions Acid rain also contains nitrogen, and this can than adults. At pH 5, most fish eggs cannot have an impact on some ecosystems. hatch. Nitrogen pollution in the coastal waters is Even if a species of fish or animal can partially responsible for declining fish and tolerate moderately acidic water, the shellfish populations in some areas. animals or plants it eats might not. In addition to agriculture and wastewater, o For example, frogs have a critical pH much of the nitrogen produced by human around 4, but the mayflies they eat activity that reaches coastal waters comes are more sensitive and may not from the atmosphere. survive pH below 5.5. Dry Deposition Dead or dying trees are a common sight in areas affected by acid rain. This is caused by When acid rain and dry acidic particles fall to aluminum leaching and mineral and nutrients Earth, the nitric and sulfuric acid that make removal due to acid rain. the particles acidic can land on statues, buildings and other man-made structures, Acidic fog and clouds at high elevations tend and damage their surfaces. to strip nutrients from the foliage of trees causing them to absorb lesser sunlight The acidic particles corrode metals and (making them unable to withstand freezing cause paint and stone to deteriorate more temperatures). quickly. They also dirty the surfaces of buildings and other structures such as Buffering Capacity monuments. Many forests, streams and lakes that The consequences of this damage can be experience acid rain do not suffer effects costly: because the soil in those areas can buffer the acid rain by neutralizing the acidity in the o damaged materials that need to be rainwater flowing through it. repaired or replaced, It depends on the thickness and o increased maintenance costs, and composition of the soil and the type of o loss of detail on stone and metal bedrock underneath it. statutes, monuments and Episodic Acidification tombstones. A short period of time when streams, lakes, Other Effects of SO2 and NOx and the ground have a much higher pH level SO2 and NOx gases along with other than they normally do and the soil cannot pollutants can be transformed into sulfate bueffer it. and nitrate particles, and ozone that can This often happens in the spring, when the create hazy air and decrease visibility. snow that contains acidic pollutants begins When the pollutants that cause acid rain – to melt. SO2 and NOx, as well as sulfate and nitrate  particles – are in the air, they can be harmful The Gaussian Plume Model to humans. In addition, NOx emissions also contribute to ground-level ozone, which is also harmful to human health. Eutrophication – It is a condition in a water body It provides a formula for the calculation of where high concentrations of nutrients (such as concentration of pollutants at any location nitrogen) stimulate blooms of algae, which in downwind from the source of emission and turn can cause fish kills and loss of plant and at any given time after the emission started. animal diversity. Plume – Gas or aerosol cloud released into Global Climate Change – evidence is mounting the atmosphere at an approximately steady that humans have disturbed this natural balance rate (from chimneys, fires, blow-down of a by producing large amounts of some of these pressurized vessel) will advect with the wind greenhouse gases, including carbon dioxide and take on an elongated shape reminiscent and methane. of a large feather. As a result, the Earth’s atmosphere appears to be trapping more of the Sun’s heat, Jet – a plume with high intrinsic momentum causing the Earth’s average temperature to (velocity decreases as one goes down the rise – a phenomenon known as global stream). warming. Steady Plume – where discharge from a Gas Dispersion Coefficient (Diffusion constant source has been occurring for long Coefficient) enough that the plume is well developed over the relevant range downstream from It is the proportionality factor D in Fick's law the source. by which the mass of a substance dM diffusing in time dt through the surface dF (Positively/Negatively) Buoyant Airborne normal to the diffusion direction is Plume – possibly with initial momentum, in a proportional to the concentration gradient c turbulent atmosphere is more complicated of this substance. Dense Plume at ground level is often the Implies that the mass of the substance expected results of accidents to chemical diffuses through a unit surface in a unit time plant. Such plumes have received much at a concentration gradient of unity (m2/s). attention as the danger associated with them is enhanced by their density. It is a physical constant dependent on o they stay close to the ground and molecule size and other properties of the dilute more slowly as any mixing must diffusing substance as well as on overcome the stable density temperature and pressure. interface at the top of the cloud. For ideal gases, the diffusion coefficient The main parameter which affects the does not depend on substance mixing rate is the Richardson Number (Ri) concentration. for a cloud of height H and density ρ in an atmosphere of density ρa in which the Diffusion in liquids encounters greater velocity associated with turbulence is resistance and the diffusion coefficients for characterized by u*. liquids are lower than 104 to 105 times.