CE 476 Air Pollution Control Final

a resource used by many but owned by none

a factor not priced in the market; a consequence experienced by third parties not involved in a market transaction

market fails to efficiently allocate resources (e.g. market is incapable of pricing an externality)

1. generation, prevention, and control of pollutants
2. transport, chemical transformation, and deposition
3. their effects

anthropogenic (caused by humans) and non-anthropogenic

stationary, mobile, transporation, fugitive emissions, and indoor air pollution

power plants, boilers, incinerators, refineries, heaters, ovens, kilns, dryers

thermal energy input, net electric output

a vapor

on-road and non-road

there is no vertical mixing which traps the air pollutants lower in the earth

leaks from pipes, valves, and seals, and dust from construction

paints, cleaners, chemicals, stoves/ovens, heaters/fireplaces

a pollutant that is directly emitted to the atmosphere (ex. sulfur dioxide)

a pollutant that is formed in the atmosphere (ex. ozone, sulfuric acid)

a reactant that leads to the formation of a secondary pollutant (ex. sulfure dioxide is a precursor to sulfuric acid)

ambient concentrations are regulated under national ambient air quality standards (NAAQS), ex: sulfure dioxide, NOx, CO, PM, lead, VOCs, and ozone

air pollutants regulated under the national emission standards for hazardous air pollutants (NESHAPs), ex: benzene, asbestos, phosphoric acid, polymers and resins

CO2, CH4, N2O, fluorinated gases

eye, nose, throat irritation, absorbs into upper respiratory system

adverse effects on respiratory system (asthma)

CO binds with hemoglobin which restricts the transport of O2 to organs and can lead to death

respiratory and cardiovascular disease, cancer, death, nervoous system effects

many are known/suspected carcinogens

command and control, air-quality standards, risk-based standards, market-based approaches

technology-based typically in the form of emission limites, design, equipment, work pratice, or fuel/feedstock composition (ex: new source performance standards - NSPS which applies to different industrial plants)

exhaust emissions and evaporative emissions (fueling and running losses)

on-road, non-road, and aviation

easy to implement and enforce as it applies uniformly to all sources

not flexibile, not always cost effective, and doesn't consider interactions between pollutants

health-based standards dictated by effects, not emission sources set to protect the vulnerable subpopulations (ex: NAAQS and criteria pollutants)

primary standards prevent adverse effects on human health and secondary standards focus on vegetation and property damage

new source review (NSR) - ensures that air quality is not significantly impacted from new/modified source

prevention of significant deterioration (PSD)

best available control technology (BACT), air quality analysis, additional impacts analysis, public involvement, and cannot violate NAAQS or PSD increment

max allowable increase in conc that is allowed to occur above a baseline conc for a pollutant

lowest acheivable emission rate (LAER), offsets from other sources, opportunity for public involvement

protects public health and there is some flexibility with control options

complicated and lack of enforcement

US specific, in line with NESHAP, using maximum achievable control technology (MACT)

1. technology-based: MACT
2. evaluate residual risl

equity to exposed populations and address health effects

uncertainty and inequity in exposure & risk based on race, socioeconomic status, ethnicity

impose an emission cap over a number of sources, create a market for permits and allow trading, enable least-cost system-wide emissions reduction (cap & trade)

cost-effectiveness and flexible for emitters

complexity and inequity to exposed populations

relate quantity of pollutant emitted to the activity associated the the release of the pollutant

EF = EI/AF where EI is emission inventory (mass of pollutant) and AF is activity factor (mass of source)

EF controlled = EF uncontrolled (1-n control)

repeatability of a measurement

proximity of the average of repeated measurements to the true value of the quantity

real differences in values of a quantity among members of a population (frequency distribution)

lack of knowledge regarding the true value of a quantity (probability distribution)

if a EF can be used for multiple scenarios (ex: EF for a diesel truck as an estimate for a NG PP)

differences in design and operation conditions, coal composition

random error and systematic error

an interval that encloses the true mean with confidence p

screening studies, lack of theoretical basis, and avg of many emission sources

based on data from a small pop of similar plants, not useful for single source emissions, representativeness, variability, uncertainty

yes

operational condition at given combustion

operating @ stoiciometric conditions

less fuel, more air - fuel lean/excess air combustion

more fuel, less air - fuel rich/insufficient air combustion - incomplete combustion (produces CO, HCs)

kinetic (1/2mv^2), potential (mgh), work, heat, internal

kinetic, potential, internal

work and heat

translation, rotation, vibration

depends on the amount of material (internal energy (U) or enthalpy (H))

does not depend on mass or size (specific internal energy (u) or specific enthalpy (h))

surroundings, system

system, surroundings

delta U + delta Ek + delta Ep = Q - W

delta U = Q - W

total heat content of a system

U + PV

Q - Ws

zero

change in enthalpy associated with a change in temperature (feel)

enthalpy of rxn for formation of a compound from elemental species

sensible enthalpy and enthalpy of formation

heat released from combustion process

heat of rxn when all warer is present as liquid

static condition, absence of change, absence of any tendency for change, absence of any driving force for change, all forces for change in balance, achieved given sufficient time for rxns to occur

reversible

positive

measure of disorder of system and it is an extensive state function

the direction of a chemical rxn can be reversed at any point by an infinitesimal change in external conditions

amt of useful work a system can perform at given T&P

G = H - TS

spontaneous

non-spontaneous

@ equilibrium and reversible

chemical energy that can be producedeacted for a given chemical species

@ equilibrium aka same amt of reactants and products

reactants

products

the same

stays constant

exothermic

endothermic

reactants

products

residence time < time required to reach equilibrium

they are necessary conditions for rxns, but insufficient for rxn on its own

collision, sufficient energy to break bonds (activation energy), orientation and shape of molecules

step in which kinetic energy of original molecules is just converted into potential energy to break chemical bonds

Ea,f - Ea,r

endothermic

exothermic

simple event in which some kind of transformation occurs (ex: two molecules colliding and reacting)

unimolecular (R=k[A]), bimolecular (R=k[A][B]), termolecular (R=k[A][B][C])

time period during which slow initiation reactions result in build-up of radicals, prior to the onset of rapid radical chemistry

# of radicals produced = # of radicals consumed

produce more radicals than consumed (@ beginning)

consumes radicals, produces none (@ end)

exothermic, may require energy exchange w a third molecule, and relatively slow

1. intake
2. compression
3. power
4. exhaust

raises temp and pressure

ignition delay/induction period

NOx, CO

NOx, CO

NOx, CO

CO

exhaust (unburned HCs), crankcase, and evaporative

air and fuel are pre-mixed in the intake air manifold and introduced to cylinder via an intake valve

fuel is directly injected into the cylinder

1. modify vehicle operation
2. modify engine design
3. exhaust gas treatment
4. modify fuel
5. maintenance

HC

dynamometer, site specific, portable emissions measurement system (PEMS)

engine tractive power demand

substitutioneformulation, work practices, modify processes, collection/capture, incineration, flaring, recovery through adsoption or condensation

enclose concentration levels within which a compound will burn without continuous application of external heat

VOC -> CO -> CO2

time, temp, turbulence (velocity)

separation

weak bonding of gas molecules to a solid, exothermic: heat of vaporization

actual chemical bonding, exothermic: heat of rxn

dual bed (one online - adsorption and one in regeneration - desorption)

inlet stream

particle filtration and dehumidification

ketones

impurities in fuels, incomplete combustion, combustion process

lignite, subbituminous, bituminous, anthracite

when it is practicel to achieve the same degree of control among all members of an emissions class

improves the allocation of emissions control expenditures

informs decisions regarding how much should we spend to avoid damages

protects human health from the adverse effects of exposure to ambient air pollution

Kp will increase

25%

the mass of VOC adsorbed versus the VOC partial pressure at equilibrium

higher

29 gmol/m^3

to protect catalytic control devices from degradation or poisoning

12 g / gmol C

fuel lean

Joules (J)

0 Jmol