ENVE 4003

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ENVE 4003

• PHILOSOPHIES AND GENERAL IDEAS IN POLLUTION
  CONTROL
• Alternative philosophies and actions, costs,
  efficiency, penetration

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• Alternatives for industrial point sources faced
  with an air pollution problem
• Improve dispersion (Tall stacks)
• Relocate the plant
• Reduce emissions (process change and/or control
  technology) Pollution Prevention (sometimes
  referred to as P2)
• The order of these alternatives is also the
  historical evolution of our general approach to
  the air pollution problem
• The air pollution problem has evolved from being
  characterized by industrial point sources to a
  combination of area sources (motor vehicle
  emissions, residential space heating)
• Improving dispersion and site selection are not
  effective in dealing with the main sources of
  pollution we face today.

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Air Pollution Control Philosophies

• The Emission Standard Philosophy
• The Air Quality Standard Philosophy
• Emission Tax Philosophy
• Cost-benefit Philosophy

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EMISSION STANDARD PHILOSOPHY

• Basic premise There is some maximum degree of
  emission control for a given class of air
  pollutant source.
• BACT Best Available Control Technology
• RACT Reasonably Available Control Technology
• LAER Lowest Achievable Emission rate
• All (new) sources in that category should be
  required to meet this level of control.
• "Cleanest possible air"

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AIR QUALITY STANDARD PHILOSOPHY

• Basic premise All pollutants of concern have a
  threshold dose-response curve.
• Regulate the time, place, amount of emissions
  such that the threshold value is not exceeded
  anywhere, anytime zero damage
• The cause-effect relationship between emissions
  and ambient concentrations must be determined by
  a combination of measurement and modelling.

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Figure 3.2 de Nevers

• The NAAQS process

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EMISSION TAXES - ECONOMIC INSTRUMENTS

• Basic premise The atmosphere has some finite
  capacity to deal with emissions of pollutants,
  i.e. keep pollutant concentrations below
  threshold levels
• Put a (realistic) price on this capacity and
  charge people who "utilize" it.

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COST-BENEFIT PHILOSOPHY

• Basic premise There are no threshold levels,
  all pollution is damaging, this damage can be
  quantified in money terms.
• Optimize the total cost of pollution damage plus
  pollution control costs.

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The cost of air pollution control

• Capital costs proportional to volumetric flowrate
  (Q, cfm, Nm3/h)
• The power required to push the air through the
  control equipment is usually the most significant
  part of the operating costs, proportional to the
  product of Q and pressured drop, ?P
• ?? ? fan or blower efficiency
• Low pressure drop and efficient blowers are key
  considerations in air pollution control equipment
  design

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Efficiency (?) and penetration (p)

• Control equipment efficiency, ?, quantifies what
  fraction of the pollutant going into the
  equipment we were able to capture.
• Penetration, p, quantifies what fraction went
  through
• p 1 - ?
• Five nines ? 99.999
• For multiple pollutants (or size ranges)
  efficiency may be different!

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Figure 3.10 Cooper Alley

• Efficiencies and penetrations for control
  equipment in series