EN3004 Air Pollution Control Engineering Lecture 8 (24S1) PDF

EN3004 Air Pollution Control Engineering Week 8 Project Assignment & Engineering Approaches for Air Pollution Control Tuti Mariana Lim School of Civil and Environmental Engineering Nanyang Technological Univ...

EN3004 Air Pollution Control Engineering Week 8 Project Assignment & Engineering Approaches for Air Pollution Control Tuti Mariana Lim School of Civil and Environmental Engineering Nanyang Technological University 1  Syllabus & Course Schedule Lecture: Friday 15:30-17:20 Dr. Maszenan Venue: LT18 Tutorial: Friday 09:30-10:20 (G1@TR+35) & 12:30-13:20 (G2@TR+29) Lecturer Week (date) Content Tuti Lim 1 (16 Aug) Course Briefing; Introduction to Air Pollution Tuti Lim 2 (23Aug) Air Pollution Control: Regulation, Philosophy & Monitoring, Tutorial 1 Tuti Lim 3 (30 Aug) The Atmosphere & Meteorology, Atmospheric Stability; Tutorial 2 Tuti Lim 4 (06 Sep) Air Quality Modeling & Plume Dispersion Models; Tutorial 3 Tuti Lim 5 (13 Sep) Indoor Air Pollution, Human Exposure, Box Model; Tutorial 4; Group Project Tuti Lim 6 (20 Sep) SOD, Acid Rain, Green House Gases & Climate Change; Tutorial 5 Tuti Lim 7 (27 Sep) Special Issues: Combustion related emissions, Quiz #1; Tutorial 6 S5 No tutorial on week 1 & week 8 ; NTU Recess Week (30 Sep – 4 Oct) Tuti Lim 08 (11 Oct) Disc on Project Assignment, General Idea of Air Pollution Control Approach Tuti Lim 09 (18 Oct) Properties of Particles and Particle Collection Mechanism; Tutorial 8 Tuti Lim 10 (25 Oct) Particulate matters control; Tutorial 9 Tuti Lim 11 (01 Nov) VOCs and HCs – Characteristic & Control; Tutorial week 10 Tuti Lim 12 (08 Nov) Oxides of Sulfur and Nitrogen – Characteristic and Control; Tutorial 11 Tuti Lim 13 (15 Nov) Control of mobile source pollutant; Quiz #2; Tutorial 12 Note: Lecture materials may not be in accordance with the scheduled lectures. SOD : Stratospheric Ozone Depletion  EN3004 Project Assignment Objectives To train students : Familiarize IAQ sampling process (sample collection, PM & GC- MS working principles, instruments, etc) Conduct proper data analysis through this project Improving communication skills & promote team work. High intensity light source used to illuminate the room. The particles pass through the light source and counting can be done either via light scattering, light obscuration & direct imaging. Light scattering: redirected light is detected by a photo detector. Light obscuration/blocked: detect the loss of light detected. Direct imaging: HD camera to record passed particles & analyzed by computer to measure particle characteristics. 3  Gas Chromatography -Mass Spectrometry (GC-MS) Separation of volatile organic compounds Separation is based on the vapor pressure and polarity of the components. 4  Working Principles GC utilizes a capillary column to do the separation. The difference in the chemical properties between different molecules in a mixture will separate the molecules as the sample travels the length of the column. The molecules take different times (called the retention time) to come out of the GC. Injection Recorder port Oven Detector Column Nitrogen cylinder 5  The MS in the downstream will capture, ionize, accelerate, deflect, and detect the ionized molecules separately. The MS does this by breaking each molecule into ionized fragments and detecting these fragments using their mass to charge ratio. 6 What kind of information can MS give you?  Molecular weight  Elemental composition  Structural information 7  GC- separate VOCs MS - analyze compositions Each component ideally produces a specific spectral peak The size of the peaks is proportional to the quantity of the corresponding substances 8 How to read your experiment results? Gas chromatogram peak1 9 Peak 1 Mass spectrum 10 11  Basic Requirement on the Report 1. Each group will submit one group report 2. The group report should not exceed 2000 WORD Counts with font size of 12, font style being Times New Roman and 1.5 spacing, please include a cover page that contains the name of each group member with signature. 3. Please make sure to include the following information/discussion in your report: The sampling location you’ve chosen. VOCs you’ve found and possible sources. Compare your results with another given data and discuss the differences and possible reasons. Submit your group IAQ report by 08/11/2024 (week #12) Central Environmental & Science Engineering Lab (CESEL) Location: N1-B2A-02 Officer in Charge: Maria Chong Ai Shing 12  A Good Project Report ❑Background or introduction (highlight the importance of IAQ control, possible sources of VOCs in your selected location, their impacts to environments, etc) ❑Objective /purpose of this project ❑Methodology/experiments of air sampling ❑Results and discussion (what have been found in the sample, concentration levels vs. relevant emission standards, consequences, comparison with provided data, etc.) ❑Conclusion & recommendation (e.g. how to improve air quality). ❑References 13 Today’s Lecture 14  Engineering Approaches for Air Pollution Control ⚫ Three general approaches for air pollution control ✓ Dispersion ✓ Process change and pollution prevention ✓ Tailpipe control ⚫ Basic concepts in downstream pollution control processes ✓ Efficiency and penetration ✓ Economic considerations ✓ Units of measurement ⚫ Properties of particulate matters 15 General Idea of Air Pollution Control ⚫ What? ? ⚫ Why? ⚫ How? 16 Recap….. Air Pollutants are… Substances that are not part of composition of “air”, which in sufficient amount can be harmful to people or their environment. ⚫ Primary Air Pollutants – directly emitted from the source ⚫ Secondary Air Pollutants – formed from reactions between existing air pollutants under certain conditions VOC + NOx + Heat + Sunlight = Ozone 17 Recap….. Sources of air pollution : Natural & Human activities 18 Recap….. Effects of Air Pollutions Clear Day Hazy Day 19 How to Control Air Pollutions? 20  Three General Approaches for Air Pollution Control (1) Improved dispersion (2) Process change and pollution prevention (3) Downstream (Tailpipe) pollution control devices Which one is the first choice? 21  (1) Improved Dispersion (Dilution) of Air Pollutants "Dilution is the solution to pollution" ⚫ Tall stacks To emit pollutants so high that by the time they reach ground level they’ve been diluted by clean air to non-hazardous levels. In the atmosphere, SO2 + oxidants --> H2SO4. Dispersed SO2 => dispersed H2SO4. Acidic rain and snow. In a sparsed populated In a densely populated world world 29,000 persons/km2 1 person/km2 Smelter at Sudbury, Ontario Singapore: 8,000 persons/km2 500 m tall smokestack 22 (1) Improved Dispersion (Dilution) of Air Pollutants ⚫ Intermittent control schemes ✓ Intermittent control schemes ban some activities in times of poor dispersion ✓ In most cases, the short-term emission reduction is brought about by a plant shutdown. ⚫ Relocate the plant A new plant can be located where its emission will have their greatest impact in non-populated areas. Basis for industrial zoning and land-use planning regulation Bhopal Gas Tragedy 23  Bhopal Gas Tragedy ⚫ 40 tonnes of methyl isocyanate (MIC) was released. ⚫ MIC is extremely toxic, and can damage by inhalation, H3C-N=C=O. ingestion and contact in quantities as low as 0.4 ppm. ⚫ It was the the world's worst industrial Disaster. The plant was located close to a densely populated area 24 (2) Process Change and Pollution Prevention ⚫ Replacing oil-based paints with water-based paints to reduce HC emission ⚫ Changing open burning of wastes to closed burning ⚫ Switching fuels Coal Mineral oil natural gas Hydrogen H H C C H C C C H H H H H C C C H H H H H H H H H H H H H C C C C H C C C C C C C C C C H H H H H H H H H H H H H H C C C C H H H C C C C H H H H H C C C Decane H:C = 2:1 Propane H:C = 2.7:1 Methane H:C = 4:1 Hydrogen H:C =  H C C C H C C H H Corones H:C = 0.5:1 25  Changes in Vehicle Systems http://autozine.kyul.net/technical_school/engine/te ch_pic_eng_prius.jpg Hybrid http://www.redjellyfish.com/newima ges/merlin.jpg Fuel Cell http://www.evworld.com/archives/test drives/carpicts/ecom_sm.jpg Battery-Electric Typical Engine Combustion: Fuel + Air => Hydrocarbons + Nitrogen Oxides + Carbon Dioxide + Carbon Monoxide + water 26 (3) Downstream (Tailpipe) Air Pollution Control ⚫ Gravity settling (large drums or vessels) ⚫ Filtration ⚫ Chemical scrubbing (absorption) ⚫ Activated carbon adsorption ⚫ Biological oxidation – biofiltration or bioscrubbing ⚫ ……….. pollutants Clean stream Main process S42 Control device 27 28  First choice process change and pollution prevention Second choice downstream control device Last choice improved dispersion for better air pollution control ! 29  Outdoor Air Pollution Control Downstream control devices Improved dispersion Process change: Improved Burns natural gas Dispersion Source: John Kraemer, 2002 30 Basic concepts in downstream pollution control processes 31 Selection of Appropriate Air Pollution Control Devices ⚫ Degree of reduction of emissions required to meet emission standards ⚫ Process and effluent characteristics ⚫ Equipment capacities, efficiency and limitations ⚫ Capital investment and operation costs S37 32  Gravity Settlers Electrostatic Precipitators (ESP) 33 Cyclones 34 Surface Filter (Baghouse) 35 Scrubber 36  Efficiency and Penetration Incoming amount Outgoing amount Collector Incoming amount – Outgoing amount Efficiency,  = Incoming amount Outgoing amount Penetration, p = Incoming amount p = 1-  S32 the fraction not collected 37  Efficiency and Penetration Q0 Q1 C0 Collector C1 Efficiency,  = (Q0C0-Q1C1)/ Q0C0 = 1- Q1C1/ Q0C0 Penetration, p = 1-  = Q1C1/ Q0C0 C0: Influent concentration; Q0: Influent volumetric flow rate C1: Effluent concentration; Q1: Effluent volumetric flow rate 38 Example 1: Four control devices are placed in series, each of 90% efficiency. Determine the overall efficiency,  (Assume the volumetric flow rate does not change). C0 C1 C2 C3 C4 90% 90% 90% 90% Q0 Q0 Q0 Q0 Q0 p1 = C1/C0; p2 = C2/C1; p3 = C3/C2; p4 = C4/C3 p (overall) = C4/C0 = (C1/C0) (C2/C1) (C3/C2) (C4/C3) = ( p1)( p2)( p3)( p4) = (1- 1) (1- 2) (1- 3) (1- 4)  (overall) = 1- p (overall) = 1- ( p1)( p2)( p3)( p4) In general, for n series of control devices Ans: 99.99%  (overall) = 1 - p (overall) = 1- ( p1)( p2)…( pn) 39 Four control devices are placed in series with different efficiencies. The volumetric flow rate is changed after each device. ? Efficiency,  = ? Penetration, p=? C0 C1 C2 C3 C4 1 2 3 4 Q0 Q1 Q2 Q3 Q4 40 In the current air pollution literature, it is common to refer to the high efficiencies required for waste incinerators as “four nines”, which means the control efficiency is ___________. ? A. 99.99 B. 99.9999% C. 99.99% 41  Economic Considerations Factors affecting air pollution control costs ⚫ The amounts of gas to be treated Quantity ⚫ Pollution removal efficiency Quality S27 For cost savings, we need to: ⚫ Try to use standard-size pollution control devices ⚫ Control fluid velocity in air pollution control equipment (~12 m/s) ⚫ Minimize volumetric flow rate and pressure drop ⚫ Resource recovery pump cost vs. capital charge for equipment Power ≈Q P/  42  Fluid Velocities in Air Pollution Control Equipment  Q= Db2 V 4 velocity cost of pumping Diameter Cost of the pipe pumping cost + capital cost of pipes and ducts 43  Minimizing Volumetric Flow Rate and Pressure Drop Q P Power = , P = P1 − P2  Q P Power Q = volumetric flow rate η = fan or blower efficiency P1 = inlet absolute pressure P2 = outlet absolute pressure 44  National Ambient Air Quality Standards POLLUTANT STANDARD STANDARD VALUE * TYPE Carbon Monoxide (CO) 8-hour Average 9 ppm (10 mg/m3) Primary 1-hour Average 35 ppm (40 mg/m3) Primary Nitrogen Dioxide (NO2) Annual Arithmetic Mean 0.053 ppm (100 µg/m3) Primary & Secondary Ozone (O3) 1-hour Average 0.12 ppm (235 µg/m3) Primary & Secondary 8-hour Average 0.08 ppm (157 µg/m3) Primary & Secondary Lead (Pb) Quarterly Average 1.5 µg/m3 Primary & Secondary Particulate (PM 10) Particles with diameters of 10 micrometers or less Annual Arithmetic Mean 50 µg/m3 Primary & Secondary 24-hour Average 150 µg/m3 Primary & Secondary Particulate (PM 2.5) Particles with diameters of 2.5 micrometers or less Annual Arithmetic Mean 15 µg/m3 Primary & Secondary 24-hour Average 65 µg/m3 Primary & Secondary Sulfur Dioxide (SO2) Annual Arithmetic Mean 0.030 ppm (80 µg/m3) Primary 24-hour Average 0.14 ppm (365 µg/m3) Primary 3-hour Average 0.50 ppm (1300 µg/m3) Secondary * Parenthetical value is an approximately equivalent concentration. 45 (from http://www.epa.gov/air/criteria.html) WHO Guidelines (1999) for Common Pollutants Pollutant Annual ambient Guideline value Concentration at Exposure time air concentration (µg/m3) which effects on (µg/m3) health start to be observed (µg/m3) CO 500-7000 100,000 Not applicable 15 min 60,000 30 min 30,000 1 hour 10,000 8 hours Lead 0.01-2.0 0.5 Not applicable 1 year NO2 10-150 200 365-565 1 hour 40 1 year O3 10-100 120 Not applicable 8 hour SO2 5-400 500 1000 10 min 125 250 24 hour 50 100 1 year 46 (from http://www.who.int/inf-fs/en/fact187.html)  Units of Measurement (Gas) Volume volume of pollutant gas *106 Parts Per Million ppm = total volume of gas mixture volume of pollutant gas *109 Parts Per Billion ppb = total volume of gas mixture volume of pollutant gas *1012 Parts Per trillion ppt = total volume of gas mixture μg/m3; mg/m3 Mass 47  Conversion: ppm to mg/m3 & μg/m3 At T=298.15 K (25C), P=1 atm, 1 mol = 24.45 L [ mg ]= ppm X MW 1000 MW [ μg ] = ppm X m3 24.45 m3 24.45 MW 273.15 (K) P (atm) [ mg ] = ppm X X X m3 22.4 T (K) 1 (atm) 1000MW 273.15 (K) P (atm) [ μg ]= ppm X X X m3 22.4 T (K) 1 (atm) 48  Properties of Particulate Matters PM – sums of all solid and liquid particles suspended in air, many of which are hazardous. -Vary in size, shape, composition & origin 49  Common PM Pollutants Solid particles larger than colloidal size capable of Dust temporary suspension in air Finely divided particles of ash entrained in flue gas. Fly ash Particles may contain unburned fuel Particles formed by condensation, sublimation, or Fume chemical reaction, predominantly smaller than 1g (tobacco smoke) Dispersion of small liquid droplets of sufficient size to fall Mist from the air Smoke Small gasborne particles resulting from combustion Particle Discrete mass of solid or liquid matter Fog Visible aerosol Soot An agglomeration of carbon particles 50  How Particulate Pollutants are Formed? Midsize Coarse particles(0.005-0.1μ) Finest particles particles (0.1-2μ) are (2-100μ) formed bythe enters agglomeration atmosphere mechanically generated and/or by chemical condensation and can conversion of be removedhot by of gases vapors. and Overtime capturing device vaporasingravity they grow such thebyair. They can beonto agglomeration settler.. removed each by rainout other either(drops in gasinphase clouds) or washout or inside cloud(rainfall). or fog droplets. Agglomeration process is slower than rainout & washout. 1: Condensation processes atmospheric reactions combustion 2. Accumulation processes 3 combustion 2 coagulation 1 condensation on existing particles Rainout atmospheric reactions and Sedimentation Washout 3. Mechanical processes wind blown dust Emissions Particle in air are either: Sea spray 1.Directly emitted (primary particles) – 3rd peak. Volcanoes 2.Indirectly formed from gaseous precursors in Plant Emitted Particles the air (secondary particles) – 1st & 2nd peaks. 51 Coagulation: Particles collide and stick together. Condensation: Gases condense onto a small solid particle to form a liquid droplet. Cloud/Fog Processes: Gases dissolve in a water droplet and chemically react. A particle exists when the water evaporates. Sulfate Chemical Reaction: Gases react to form particles. Source: Timothy S. Dye, et al. 52  In the area close to the exhaust the aerosol shows high concentration and narrow size distribution (primary particles). As the air carries the aerosol away from the exhaust, the particles collide with each other forming larger agglomerates (decreasing the number of smaller particles.) This process also causes broadening of the size distribution. 53  Characteristics of Particulate Matters N The efficiency of the particle collection mechanisms E X strongly depends on particle size. T W e The particle size distribution of flue gas determines the e k operating conditions necessary to collect the particles and control device’s collection efficiency (control concern). Particle size distribution are important in determining the behavior of particles in the respiratory tract (health concern). dp > 10 m 1 < dp 10 m PM2.5 Coarse 2.5 m < dp < =10 m Particles less than 0.1 μm Fine 0.1 m < dp