ENVI ENG Particulate Emissions

Vocabulary flashcards covering air-pollution control devices, regulatory pollutants, and sampling methods from the lecture notes.

Cloth-Screen Filter (Baghouse)

A fabric filtration unit that traps particulate matter on cloth bags while allowing cleaned gas to pass; bags are shaken or pulsed to remove dust.

Cyclone Separator

A centrifugal device that spins the gas stream so heavier particles are flung to the wall and collected, effective for larger particulates.

Multicyclone

An array of small cyclone separators operating in parallel to boost particulate removal efficiency and handle higher gas flow rates.

Hopper (Collector)

The conical bottom section of a control device where separated particulates accumulate before disposal.

Volatile Organic Compounds (VOCs)

Carbon-based chemicals that readily vaporize at ambient temperatures and act as precursors to photochemical smog.

Condensation (as Control Device)

Cooling and/or pressurizing a vapor stream to liquefy pollutants, used as a pretreatment step to cut gas volume and load.

Contact Condenser

A condenser in which hot gas mixes directly with a cold liquid, transferring heat and condensing vapors.

Surface Condenser

A condenser where gas passes over cooled surfaces (e.g., tubes) without direct liquid contact, causing vapors to condense.

Removal Efficiency

The percentage of a pollutant captured or destroyed by a control device; condensers typically reach 50–95 %.

Incineration (Combustion)

High-temperature oxidation that converts organic pollutants to CO₂ and H₂O; includes flares, thermal, and catalytic units.

Direct Combustion / Flare

Immediate burning of waste gas at a burner tip with no residence chamber, achieving about 98 % destruction efficiency.

Thermal Incineration

Waste gases pass a burner into a heated residence chamber, completing oxidation with >99 % pollutant destruction.

Catalytic Incineration

After initial flame heating, gases pass over a catalyst bed, allowing oxidation at lower temperature with >95 % efficiency.

Residence Chamber

The high-temperature zone in a thermal incinerator that provides the required time for complete oxidation of pollutants.

Desorption

The release of molecules previously absorbed or adsorbed on a surface; the opposite of absorption/adsorption.

US EPA Criteria Pollutants

Six common air contaminants regulated nationwide: PM₁₀/PM₂.₅, ground-level O₃, CO, Pb, NO₂, and SO₂.

Kyoto Protocol Greenhouse Gases

Targeted gases for climate mitigation: CO₂, CH₄, N₂O, HFCs, PFCs, and SF₆.

Philippine Clean Air Act Criteria Pollutants

Local list including TSP, PM₁₀, photochemical oxidants as O₃, CO, Pb, NO₂, and SO₂.

Ozone-Depleting Substances – Class I

CFCs, halons, carbon tetrachloride, methyl chloroform, and methyl bromide—chemicals with high ozone-depletion potential.

Ozone-Depleting Substances – Class II

Hydrochlorofluorocarbons (HCFCs), transitional chemicals with lower but still significant ozone-depleting potential.

Photochemical Smog Precursors

Nitrogen oxides (NOₓ) and VOCs that react under sunlight to form ground-level ozone and other oxidants.

Acid Deposition Precursors

Sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) that convert to acidic species responsible for acid rain.

Sedimentation & Settling Devices

Simple chambers or jars where gravity causes large particles to settle out of an airstream.

Inertial / Centrifugal Collectors

Equipment (e.g., cyclones) that removes particles >10 µm by forcing abrupt changes in gas direction, exploiting inertia.

Electrostatic Precipitator (Sampling Type)

Device that charges airborne particles with an electrode and collects them on oppositely charged plates for analysis.

Automatic Tape Smoke Sampler

Instrument that continuously draws air through a moving filter tape to log particulate loading over set intervals.

High-Volume Sampler (Hi-Vol)

EPA reference sampler that pulls 40–60 cfm of air through a weighed filter to measure total suspended particulates.

Impingers

Sampling devices that collect particles by forcing gas to impact into liquid (wet) or solid (dry) surfaces; size-dependent efficiency.

Cascade Impactor

Sampler with sequential stages of decreasing nozzle size, sorting particles onto slides by aerodynamic diameter.

Nuclei Counter

Instrument measuring condensation nuclei by humidifying and adiabatically expanding an air sample, then counting droplets.

Pollen Sampler

Slide coated with petroleum jelly exposed for 24 h to trap airborne pollen grains for microscopic counting.