EAAC0423 Environmental Science and Engineering PDF

BA TA A N P ENINSULA STA TE UNIVERSITY C OL L EG E OF EN G I N EERI N G A N D A RC H I TEC TURE D e par tm e nt o f Me c hani c al Eng i ne e r i ng EAAC0423 Environmental Science and Engineering BSME...

BA TA A N P ENINSULA STA TE UNIVERSITY C OL L EG E OF EN G I N EERI N G A N D A RC H I TEC TURE D e par tm e nt o f Me c hani c al Eng i ne e r i ng EAAC0423 Environmental Science and Engineering BSME (3A, 3B, 3C) Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing AIR ⚬ Mostly gas, it isn’t just gas. ⚬ Important for living things. ⚬ Carbon dioxide in the air can be both good and bad. ⚬ Air also holds water. ⚬ Air changes as you go up. ⚬ A protective cushion. ⚬ Air pollution is measured with the Air Quality Index, or AQI. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Air Pollutants Pervasive throughout areas ⚬ products of daily-life activities such as transportation, power generation, space and water heating, and waste incineration Generated by activities such as chemical, manufacturing, and agricultural processing ⚬ pollutant byproducts tend to be localized in nearby areas or are spread long distances by tall stacks and prevailing winds Categorized by their emission characteristics: ⚬ Point sources ⚬ Area sources ⚬ Mobile sources Engr. Andrea Shane M. Torres  BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing The Air Quality Index (AQI) designed by EPA reports the daily levels of ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide on a scale of 0 to 500. The range corresponds to six different categories of health concern that are also characterized by colors. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Ozone Ozone (O3) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man- made product that occurs in the Earth's upper atmosphere (the stratosphere) and lower atmosphere (the troposphere). It is a very reactive chemical that readily attacks other molecules, including those in the tissues of the respiratory system. Exertions that increase the need for oxygen will increase air intake and allow ozone molecules to penetrate and damage the sensitive areas of the lungs. Engr. Andrea Shane M. Torres  BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Why is the ozone layer important? It absorbs 97% to 99% ultraviolet radiation (UV-B). Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Particulate Matter “Fine particles” are less than 2.5 microns in size and require electron microscopy for detection. ⚬ Formed by the condensation of molecules into solids or liquid droplets, whereas larger particles are mostly formed by mechanical breakdown of material. “Coarse particles” are between 2.5 and 10 microns in diameter and cannot penetrate as readily as fine particles. Sulfur Dioxide Sulfur-dioxide exposures are usually accompanied by exposures to particulate matter, which together exacerbate the effects. ⚬ The diesel fuel used in vehicles can contain up to 500 ppm by weight of sulfur. It also increases the harmful effects of ozone when both of these gases are present. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Dioxin “ The term “dioxin” refers to a group of compounds that cause similar adverse health effects. They belong to three classes of chemicals: chlorinated dibenzo-p-dioxins (CDDs), chlorinated dibenzofurans (CDFs), and polychlorinated biphenyls (PCBs). ⚬ Combustion of certain materials, chlorine bleaching of pulp and paper, and certain chemical manufacturing processes all may create small amounts of dioxins. ⚬ Dioxins are characterized as likely human carcinogens. Asbestos “Asbestos” is the generic term for silicate materials that occur in fibrous form. A fibrous form that is classified as a serpentine is called “chrysotile” ⚬ Asbestos air concentrations are in terms of nanograms per cubic meter—asbestos background concentrations are usually in the range of 0 to 10 ng/m3. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Motor Vehicle Emissions The Conventional Otto Cycle Engine ⚬ The most common internal combustion engine is a four-stroke, spark-ignited, piston engine invented around 1880 by a German engineer, Nicholas Otto. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Intake: Intake valve open, piston motion sucks in fresh air/fuel charge. Compression: Both valves closed, air/fuel mixture is compressed by rising piston, spark ignites mixture near end of stroke. Power: Air fuel mixture burns, increasing temperature and pressure, expansion of combustion gases drives pistons down. Exhaust: Exhaust valve open, spent gases are pushed out of cylinder by rising piston. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Sample air to fuel ratio Complete combustion in oxygen: Complete combustion in air: Engr. Andrea Shane M. Torres  BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Stoichiometric Air to Fuel Ratio Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Air Pollution Instrumentation utilized in the two major air quality areas of source and ambient monitoring with a further breakdown in the source monitoring category to the manual, and continuous type of instrumentation. ⚬ MANUAL MONITORING—SOURCE INSTRUMENTATION ⚬ CONTINUOUS MONITORING—SOURCE INSTRUMENTATION ⚬ EXTRACTIVE MONITORS Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing MANUAL MONITORING—SOURCE INSTRUMENTATION Provides a means to determine compliance with existing regulations and for developing design criteria for control of air pollution. ⚬ The most familiar procedure, “Method 5,” utilizes the basic equipment and sampling procedures (i.e., impingers, dry gas meter, pump, etc.) Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing MANUAL MONITORING—SOURCE INSTRUMENTATION As an example, Method 17 shown in Figure 2, utilizes the same components from the EPA 5 “sampling train” with a change in the filter location. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing MANUAL MONITORING—SOURCE INSTRUMENTATION The EPA methodology and equipment were developed specifically to improve the accuracy of the source testing programs and supplement the “ASME Train” (the “ASME” or American Society of Mechanical Engineers Train was developed to allow the determination of stack gas concentrations primarily in the electric utility area). ⚬ The major reason for the testing methodology change (ASME to EPA) was to improve the capture efficiency of smaller (submicron) particles and allow for gaseous concentration determinations. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing CONTINUOUS MONITORING—SOURCE INSTRUMENTATION Two basic types of source emission monitoring instrumentation 1. Opacity monitors (Transmissometers) ⚬ measure the transmittance of light through the gas stream (two basic types: single-pass systems and double pass systems) 2. Gaseous emission monitors ⚬ measure the concentration of specific gaseous components of the exhaust gas ⚬ These instruments are divided into two basic types: ￭ Extractive systems ￭ In-situ systems In-stack monitors Cross-stack monitors Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing CONTINUOUS MONITORING—SOURCE INSTRUMENTATION 1. Opacity monitors ⚬ provide information relative to combustion conditions, or control device efficiency. Two basic types: 1. Single-pass system ⚬ incorporates a light source on one side of the stack and a detector on the opposite side. ⚬ more economical of the two systems but it does not meet the EPA requirements for system zero and calibration checks without complete process shutdown every 24-hours. 2. Double-pass system ⚬ houses both the light source and detector with attendant calibration and zero-check instrumentation on the same side of the stack with only a reflecting mirror on the opposite side. ⚬ Most of the double-pass systems satisfy the EPA design criteria. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing CONTINUOUS MONITORING—SOURCE INSTRUMENTATION 2. Gaseous Emissions Monitoring ⚬ measure the concentration of specific gaseous components of the exhaust gas. ￭ Extractive Analyzers—Other Methods Paramagnetism-used in some oxides analyzers. Thermal conductivity-used in some sulfur dioxide continuous monitors. ￭ In-situ systems A system that will directly measure gas concentrations in the stack without modifying the flue gas composition. ⚬ Cross-stack monitors measure the gas concentration across the entire of the stack diameter. ⚬ In-stack systems (or short-path monitors) have a shorter path length of 5 centimeters to a meter. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing EXTRACTIVE MONITORS The basic principle behind an extractive monitor is the withdrawal of a gas sample from the main exhaust stream into the analyzer. This withdrawal must be conducted such that a representative sample is selected, and then appropriate interferents (particulates, water vapor, etc.) must be removed dependent upon analytical methodology. Three general categories: Absorption spectrometers Luminescence analyzers Electroanalytical monitors Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing EXTRACTIVE MONITORS Absorption spectrometers ⚬ An optical spectrometer measures the amount of light absorbed by a sample as a function of wavelength. Two types: a. Non-dispersive infrared analyzers (NDIR) ￭ can monitor SO2, NO, CO, CO2 and hydrocarbons b. Non-dispersive ultraviolet analyzers (NDUV) ￭ used primarily to monitor SO2 and NO2 Electroanalytical Monitors ⚬ These instruments rely on the methods of polarography, electrocatalysis, amperometric analysis, and conductivity. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing EXTRACTIVE MONITORS Luminescence Analyzers ⚬ measure the emission of light from an excited molecule ⚬ Dependent on the mode of molecule excitement, molecules can exhibit; ￭ Photoluminescence (fluorescence) utilized for SO2 analysis occurs when a molecule is excited by light energy of a given wavelength, and light energy of a second wavelength is emitted. ￭ Chemiluminescence the reaction involves ozone (O3) and nitric oxide (NO) used for NOx and NO2 determinations and operate on the principle of the emission of light energy resulting from a chemical reaction. ￭ Flame luminescence detect sulfur compounds and are specific to sulfur alone use the principle of luminescence through molecule/flame interaction. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Indoor Air Quality (IAQ) It refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. ⚬ Understanding and controlling common pollutants indoors can help reduce your risk of indoor health concerns. Indoor air can be exchanged with outdoor air by any combination of three mechanisms: infiltration, natural ventilation, and forced ventilation. ⚬ Infiltration is used to describe the natural air exchange that occurs between a building and its environment when doors and windows are closed. ⚬ Natural ventilation is the air exchange that occurs when windows or doors are purposely opened to increase air circulation. ⚬ Forced ventilation occurs when mechanical air-handling systems induce air exchange using fans or blowers. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Infiltration ⚬ Driven by pressure differences between the inside of the building and the outdoor air. These pressure differences can be caused by wind or by inside to-outside temperature differences. ￭ Wind blowing against a building creates higher pressure on one side of the building than the other, inducing infiltration through cracks and other openings in the walls. ⚬ Temperature induced infiltration (usually referred to as the stack effect) is influenced less by holes in the walls than by various openings in the floors and ceilings. ￭ In the winter, warm air in a building wants to rise, exiting through breaks in the ceiling and drawing in colder air through floor openings. ￭ Greater leakage areas in the floor and ceiling encourage stack- driven infiltration, whereas leakage areas in vertical surfaces encourage wind-driven infiltration. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Infiltration ⚬ Infiltration rates may be expressed in units such as m3/hr or cubic feet per minute (cfm), but more often the units are given in air changes per hour (ach). ￭ The air exchange rate in ach is simply the number of times per hour that a volume of air equal to the volume of space in the house is exchanged with outside air. ￭ Typical average infiltration rates range from about 0.5 ach to 1 ach. Some very poorly built houses have rates as high as 3–4 ach. ￭ Continuous plastic sheet “vapor barriers” in the walls can achieve infiltration rates that are as low as 0.1 ach. At such low infiltration rates, moisture and pollutant build-up can be serious enough to require extra ventilation, and the trick is to get that ventilation without throwing away the heat that the outgoing stale air contains. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Infiltration ⚬ A mechanical heat-recovery ventilator (HRV) ￭ the warm outgoing stale air transfers much of its heat to the cold fresh air being drawn into the house. Exhaust fans in bathrooms and range hoods over gas stoves, for example, can greatly reduce indoor pollution, and by using them only as necessary, heat losses can be modest. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Infiltration ⚬ Heat-recovery ventilator (HRV) Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing An Indoor Air Quality Model Engr. Andrea Shane M. Torres  BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing An Indoor Air Quality Model Consider the simple, one-box model of a building shown in Figure 65. ⚬ There are sources of pollution within the building that can be characterized by various emission rates. ⚬ In addition, ambient air entering the building may bring new sources of pollution, which adds to whatever may be generated inside. Those pollutants may be removed from the building by infiltration or ventilation, or they may be nonconservative and decay with time. ⚬ In addition, if there is a mechanical air-cleaning system, some pollutants may be removed as indoor air is passed through the cleaning system and returned. Engr. Andrea Shane M. Torres BA TA A N P EN I N SUL A STA TE UN I VERSI TY EAAC0423 C OL L EG E OF EN G I N EERI N G A N D A RC H I TEC TURE Environmental Science and Engineering D epar tment of Mec hani c al Eng i neer i ng