Air Pollution Control Engineering Week 8

Air Pollution Control Engineering - Week 8

• Course is EN3004
• Topics include project assignment and engineering approaches for air pollution control
• Lecturer is Titi Mariana Lim
• Course held at Nanyang Technological University's School of Civil and Environmental Engineering
• Lectures are held on Fridays from 15:30-17:20
• Tutorials are held on Fridays at 09:30-10:20 (G1@TR+35) and 12:30-13:20 (G2@TR+29)
• The location for lectures and tutorials is LT18.

Syllabus & Course Schedule

• Week 1 (16 Aug): Course briefing; introduction to air pollution
• Week 2 (23 Aug): Air pollution control: regulation, philosophy, and monitoring; Tutorial 1
• Week 3 (30 Aug): The atmosphere and meteorology, atmospheric stability; Tutorial 2
• Week 4 (6 Sep): Air quality modeling and plume dispersion models; Tutorial 3
• Week 5 (13 Sep): Indoor air pollution, human exposure, box model; Tutorial 4; group project
• Week 6 (20 Sep): SOD, acid rain, greenhouse gases, and climate change; Tutorial 5
• Week 7 (27 Sep): Special issues: combustion-related emissions; Quiz #1; Tutorial 6; no tutorial on week 1 and week 8 of NTU recess week
• Week 8 (11 Oct): Discussion on project assignment; general idea of air pollution control approach; no tutorial
• Week 9 (18 Oct): Properties of particles and particle collection mechanisms; Tutorial 8
• Week 10 (25 Oct): Particulate matter control; Tutorial 9
• Week 11 (1 Nov): VOCs and HCs - characteristic and control; Tutorial week 10
• Week 12 (8 Nov): Oxides of sulfur and nitrogen - characteristic and control; Tutorial 11
• Week 13 (15 Nov): Control of mobile source pollutant; Quiz #2; Tutorial 12
• Note: Lecture materials may not be in line with scheduled lectures. SOD: Stratospheric Ozone Depletion

Project Assignment Objectives

• Familiarize IAQ (Indoor Air Quality) sampling process (sample collection, PM & GC-MS)
• Conduct proper data analysis
• Improve communication skills and promote teamwork
• Employ light scattering, light obscuration (blocking), and direct imaging for particle detection and analysis
• Use a HD camera for direct imaging to analyze passed particles and compute their characteristics

Gas Chromatography -Mass Spectrometry (GC-MS)

• Separates volatile organic compounds (VOCs)
• Separation is based on vapor pressure and polarity

Working Principles of GC

• Capillary column is utilized for separation
• Difference in chemical properties between molecules separates them as the sample travels through the column
• Molecules take different time (retention time) to exit the GC

Working Principles of MS

• MS in downstream captures, ionizes, accelerates, deflects, and detects ionized molecules separately
• Molecules are broken into ionized fragments; fragments are detected based on their mass-to-charge ratio

What kind of information can MS give

• Molecular weight
• Elemental composition
• Structural information

GC-MS analysis

• GC separates VOCs
• MS analyzes the resulting compositions
• Each component creates a spectral peak.
• Peak size corresponds to compound quantity.

How to read experiment results

• The data should be examined for peaks

How to read a Gas Chromatogram

• Each compound (peak) in the chromatogram should be identified, using MS data and other references
• The size of the peaks corresponds to the quantity of the compound being measured.

A Good Project Report

• The project report should contain background/introduction (importance, sources, etc.)
• Objective / purpose
• Methodology (air sampling experiments)
• Results and discussion (emission standards, consequences, data comparisons)
• Conclusion and recommendation(improving air quality)
• References and group member signatures

Air Pollutants (Recap)

• Primary air pollutants: emitted directly from sources
• Secondary air pollutants: Formed from reactions between existing air pollutants under certain conditions
• Sources: Natural and human activities

Effects of Air Pollution Examples

• Clean day vs. Hazy day
• Impacts of harmful pollutants
• Impacts on health (using diagrams of red blood cells and respiratory systems)

How to Control Air Pollution (Recap)

• Three general approaches for air pollution control: Improved dispersion, process change, and downstream (tailpipe) control devices
• Order of preference: Process Change > Downstream Control > Improved Dispersion

Improved Dispersion

• Emission from tall stacks to dilute pollutants to non-hazardous levels before ground contact
• Controlling schemes: banned activities in poor dispersion times
• Relocating plants to emission areas with less population

Principles of Downstream Control Devices

• Include Gravity settling, chemical scrubbing (absorption), Activated carbon adsorption, and biological oxidation

Efficiency and Penetration (Calculations)

• Efficiency = (Incoming Amount – Outgoing Amount) / Incoming Amount
• Penetration = Outgoing Amount / Incoming Amount

Economic Considerations

• Factors affecting air pollution control costs: treated gas quantity, and pollution removal efficiency
• Cost savings solutions: Standard-size control devices
• Control fluid velocity (approx 12m/s)
• Minimizing pressure drop and volumetric flow rate
• Resource recovery

Particle Size

• Common particulate pollutants: Dust, Fly ash, Fumes, Mist, Smoke, Particle, Fog, Soot
• Particle size distribution of flue gas impacts collection efficiency
• Particle size distribution effects respiratory system, which are important in determining health risks.
• Important factors: Size and shape, density
• Calculating aerodynamic diameter to categorize particle size by aerodynamic properties.

Particle Size Categories (EPA Classifications)

• Define total suspended particulate matter and subdivisions (PM10, PM2.5)