Air Pollution Control Processes Slide for ENVIRONMENTAL Engineering

Air

1. Air Pollution Control Processes
Fall 2024
Rosa M. Flores
[email protected]
Office M4 -238
1

2. “there is only one way in
this world to achieve true
happiness, and that is to
express yourself with all
your skill and enthusiasm
in a career that appeals to
you more than any other. In
such a career, you feel a
sense of purpose, a sense
of achievement. You feel
you are making a
contribution. It is not
work”
2https://www.brainpickings.org/2012/12/14/how-to-avoid-work/

3. http://www.brainpickings.org/2012/08/24/how-to-be-an-explorer-of-the-world-keri-smith/3

4. 4

5. Answer the following questions:
§When and Where did it occur? Why did it happen?
§Which compounds where mainly emitted? Maximum concentration?
§How many deaths were registered daily?
§How long did it last?
5http://www.learner.org/courses/envsci/visual/animation.php?shortname=anm_london_fog_graph

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Some particles
are large enough
to see with the
naked eye, while
others can only
be viewed under
an electron
microscope.

13. 13

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16. §Chapter 7: General Ideas in Air Pollution Control
§7.1 Alternatives Week 1
§7.2 Resource recovery Week 2
§7.3 The ultimate fate of pollutants Week 2
§7.6 Minimizing volumetric flow rate and pressure drop Week 2
§7.7 Efficiency, penetration, and nines Week 2
§7.8 Homogeneous and nonhomogeneous pollutants Week 2
§7.10 Combustion
§7.11 Changing volumetric flow rates
§7.12 Acid dew point
§Chapter 8: The Nature of Particulate Pollutants
§8.1 Primary and secondary pollutants
§8.2 Settling velocity and drag forces
§8.3 Particle size distribution functions
§8.4 Behavior of particles in the atmosphere
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17. §MIDTERM 1
§Chapter 9: Control of Primary Particulates
§9.1.1 Gravity settlers
§9.1.2 Centrifugal separators
§9.1.3 Electrostatic precipitators
§9.2.1 Surface filters
§9.2.2 Depth filters
§9.2.4 Scrubbers
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18. 18
available in google drive.
Noel de Nevers
3rd edition
MGW
2017

19. Points Total
§Midterm exams 2 x 100 40%
§Final exam 1 x 100 40%
§Project 1 x 100 10%
§Quizzes 2 x 100 10%
100%
§Attendance of 70% is required. You can miss 8 classes. 9 missing classes = DZ
§Quizzes will be online during class time.
§I will let you know quiz date one week before.
§Plagiarism will not be tolerated. Collaboration is OK.
§Slides will be continuously shared on google drive
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20. §Fall Semester starts Mon 30 Sep
§Republic Day Mon-Tues 28-29 October
§Midterm Week 18-24 Nov
§New Year Wed 01 Jan
§End of semester Sun 12 Jan 2025
§Finals Week 13-26 Jan
§Make-up exam Week 27 Jan - 9 Feb
§Spring 2021 begins 17 Feb – 15 Jun
9/25/2420

21. §E-mail: [email protected]
§Office M4-238 **by appointment
§Office hours: Wednesdays 8:30-10:30
9/25/2421
tinyurl.com/ENVE3042Fall24

22. 7.1 General ideas in air pollution control22

23. 23

24. §7.1 Alternatives
§7.1.1 Improve dispersion
Dispersion: the larger the volume, the lower
The pollution concentration
•~70 years ago, it was the most widely used approach
to pollution problems.
•Strongly disapproved of by industry
“ Dilution is the solution to pollution”
Do you agree?
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25. §7.1.1 Tall stacks
§Pollution emitted from a taller stack has to travel a longer distance to get to
the ground, so it will become more dilute.
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26. §With a tall enough smokestack, pollution is emitted within the inversion aloft, forming a fanning plume that does not pollute the area near the smokestack. If it's not tall enough, it will fumigate the countryside.
§Switching the layers so that the inversion is at the ground, we need the smokestack tall enough to be above the ground inversion, so that a lofting plume is formed. Engineers will need to know the average depth of the nocturnal radiation inversion in order to know how tall to build the smokestack.
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28. §The faster the smoke gushes out, the more
momentum it has, and the higher it will fly
before it levels out and disperses toward
the ground.
§Use pump or reduce diameter of stack
§Narrowing the smokestack's opening forces
the smoke out as a faster streaming,
narrower jet.
§Backpressure from the smaller opening
may reduce the efficiency of the flow of
smoke out of the chimney, however,
partially offsetting the increasing in plume
momentum.28

29. §The higher the temperature, the greater
the positive buoyancy in smoke
streaming out of the smokestack.
§The smoke has to rise higher before it
has adiabatically cooled to a neutral
buoyancy temperature
§Heat the emission gases or run hotter
combustion process
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30. §Is improving dispersion a viable alternative?
§Transboundary pollution
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31. §7.1.1 Improving dispersion
§7.1.1.2 Intermittent control schemes
§ Attempt to reduce emissions at certain times of the day or year.
§ Allow emissions to return to normal rates at less critical times.

§ Fuel switching
§ Production decrease
§ Plant shutdown
Predictive: Based on the knowledge that the atmospheric conditions call for an emission reduction. Pollutants need to be emitted several hours before the predicted violation.
Observational: Emissions are promptly decreased when the sensor or network of sensors indicate that the air quality is deteriorating. It is a problem when not enough sensors are available, then emissions do not affect sensors until after hours after they have been emitted.
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32. §7.1.1 Improving dispersion
§7.1.1.2 Intermittent control schemes
Predictive-Observational: Best of all. In case of failure of the
predictive approach, observations play a role in the initiation
of a public notice.

Example: Use oxygenated fuels only during the period when
high CO concentrations are expected.
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34. 34http://news.sciencemag.org/earth/2009/04/china-falls-short-olympic-cleanup

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36. §7.1.1 Improving dispersion
§7.1.1.3 Relocate the plant
§ It is hard to move an existing plant
§ New plant can be prevented to be constructed in areas with severe air pollution
§ A new plant can be located where its emissions will have their greatest impact in nonpopulated areas.

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37. §Where do we locate a new coal-fired power plant?
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38. §7.1.2 Reduce emissions by process change
§Modify the process to reduce emissions
Examples:
§Factories that apply paint to their products (such as
automobiles, refrigerators) were required to reduce the emissions
of hydrocarbon solvents (paint thinners).
§Solution: Replace water-based paints for oil-based paints.
§Copper smelters replaced furnaces that produce high-volume,
low-concentrations of SO2 waste gas, with other processes that
produce low-volume, high-concentrations of SO2 waste gas.
§Advantage: The waste gas is easier and more economical to treat
with downstream devices.
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39. §7.1.2 Reduce emissions by process change
§Open burning of municipal or industrial waste
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40. §7.1.2 Reduce emissions by process change
§Switching fuels: Replace coal by natural gas
§Carpooling, walking, use of public transportation
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41. §7.1.2 Reduce emissions by process change
§Replace low-efficiency incandescent light with higher efficiency fluorescent light
§MAJOR EFFORTS TO REDUCE EMISSIONS RATHER THAN CONTROL THEM41

42. §7.1.3. Use a downstream pollution control device
§Also called tailpipe or end-of the-pipe control device
§It treats a contaminated gas stream to remove or destroy enough of the
contaminant to make the stream acceptable for discharge into the ambient
air.
42http://techalive.mtu.edu/envengtext/ch12_particulatecontrol.htm
Purpose of this
class

43. §7.1.3. Use a downstream pollution control device
§An environmental engineer will first examine the previous two options
(Improve dispersion and reduce emissions by process change) to see if they
are more practical and economical than a downstream control device.
§For major plants, three approaches can be combined to meet the regulations:
1.A tall stack for improved dispersion
2.Intermittent control to deal with difficult weather situations
3.Process change to reduce emissions
4.Downstream control to treat the effluent
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