This course discusses the generation of pollutants in combustion chambers, pollutant reduction by combustion control, as well as the pre- and post-combustion treatment of fuels and effluents. The emphasis is on the illustration (or introduction) of fundamental laws -- of physics, chemistry, thermodynamics, chemical kinetics, and momentum, heat and mass transport -- that govern these phenomena. At the end of the semester, the students should be able to (a) identify and understand the bottom-line issues, including the preliminary design of air pollution control processes, and (b) effectively and efficiently locate the reliable sources of additional information where important and relevant details can be studied further.
This
is a core course for the degree in Environmental Systems Engineering (www.ems.psu.edu/environment/ugradprog.htm).
It is also a good introduction to more specialized courses dealing with
atmospheric processes (e.g., METEO 455).
Summary of
‘tools’ needed in FSC430
Here is a part
of the textbook-in-progress for this class.
Below is the grade scale that
we shall use:
A 94-100
A- 90-93
B+ 85-89
B 80-84
B- 75-79
(Of
course, I trust that everybody will get >B-… Indeed, the course is designed
so that you can get the grade that you want… and hopefully deserve… See
Syllabus!)
C+ 70-74
C 60-69
D 50-59
F <50
During
the first two weeks of the semester, we want to make sure that you have at your
disposal the math skills (AND the software) that will make your life easier (in
this class and in others as well). Only then, through parametric
sensitivity analysis and visualization of
important equations, can we REALLY understand the science and technology
that governs air pollution and its control. Two of the many available tools are
Excel and Mathematica. Excel is fine, but it’s primarily for accountants… every
self-respecting science/engineering student really wants to move up to
Mathematica (or MathCad, or MatLab, or Maple, etc.)...
Here
is a nice tutorial on the use of Mathematica… Here
is another one (which you can very easily find yourself using google)!
MathReader is available for free…
The
NYTimes article by Matthew
Wald, “Travel habits must change to make a big difference in energy
consumption” (12/30/2006) is a good starting point for our discussion. See also “Can coal be clean?” in The Economist of 12/02/06. (Can you find
these articles online easily?)
STOICHIOMETRY/THERMODYNAMICS
OF COMBUSTION REACTIONS
-Analysis of the
ExxonMobil op-ed piece of 02/29/2007
-Simple CO2
emissions ‘algorithm’ Familiar with "Tata nano"? How is it related to CO2
emissions?
-Comparison
of greenhouse effects of various fuels
-Simple SO2
emissions ‘algorithm’
-SO2/SO3
equilibrium algorithm Example 7-5 in H+K
-Here is a template
for the preparation of van’t Hoff plots. Figure 1-19 (H+K) Can you
find (and download... and use!)
Chemeq.bas?
-Here is a template
for analyzing the combustion stoichiometry for
CxHyOz compounds… and here
for BOTH fuel-lean and fuel-rich mixtures.
-Here is a
template for the preparation of Cp vs. T
plots.
-Here is a
template for a power plant fuel consumption analysis (based on a simple mass
and energy balance).
-Here
is a (bit) more challenging, and currently VERY relevant, stoichiometry
problem, which is helpful in the selection of candidate additives for RFG!
The
NYT of 2/8/07 reports that the “European Commission … proposed binding rules
that require automakers to cut carbon dioxide emissions for new cars … to an
average 130 grams a kilometer by 2012.” Explain what this means in practical
terms (and we’ll discuss it in class)!
Phase equilibria: for G/L, all we need is
the Henry's law
constant (Why?) And for G/S... (Stay tuned!)
Here is a
template for easy construction of Figure E7-7(H+K).
Solutions: #1a #1b #2 (partial) #3
Homework 2 (due 02/06, accepted until 02/08)
(1)
Make a graph of U.S. energy consumption vs. time over the last half a century
or so, showing clearly the relative contributions of the various energy sources
(coal, oil, gas, etc.). Discuss concisely any clear trends; in particular, see
whether there has been an important shift to natural gas consumption over the
last decade (at the expense of which fuel?) and comment on the environmental
benefits of such a shift.
(2)
(a)
Make a graph of the temperature dependence of heat capacity of SO2
and CaSO4 using information from at least two independent (and
hopefully authoritative!) sources. (b) For SO2 compare the
polynomial obtained with that provided in Chemeq.bas.
(b)
For CaSO4, if not available in Chemeq.bas, enter the polynomial
obtained into the react.dta file and then construct the van't Hoff plot for the
environmentally important reactions CaCO3 = CaO + CO2 and
CaO + SO2 + 0.5O2 = CaSO4; with the help of
this graph, discuss the ("temperature window" of) thermodynamic
feasibility of sulfur capture using limestone.
-"CaSO4",-1305.0,-1417.2,70.2,9.87,0,0,0...
Do you agree that this line should go into the react.dta file? Either way, be
sure to justify your answer!
-In order to understand the a+bT+cT2+dT3+eT-2
polynomial used by Chemeq.bas, did you study (carefully!) the Cp vs.
T template for SO2 (especially its 10-2, 10-5
and 10-9 parts)?
-For another source of thermo
information, what happens when you do a LIAS search of "thermodynamic (or
thermochemical?) properties of inorganic substances"? And if you ask a
librarian?
-Both the CRC and Perry's Handbook
should have information on SO2, while Perry's handbook and the
Knacke monograph (see LIAS) have CaSO4 info... Right?
-Does your solution to #2 look like this?
BASIC KINETICS OF
COMBUSTION, AIR POLLUTION AND AIR POLLUTION CONTROL
Calculation of
collision frequency (Remember
Phys101... kinetic theory of gases?) For a first-order homogeneous reaction, the collision
frequency is obtained from the following equation:
ZA=
p dA2 cmean CA
How does this compare to the expression for the collision frequency
ZW shown in the template? And to the expression for a second-order
reaction (either ZAA or ZAB)?
Get a 'feel' for the
Arrhenius expression Any useful
(interactive) Internet web sites?
(Who was Arrhenius, anyway? Try
google.com... And for what exactly did he win the Nobel prize?)
Here is a
simple Mathematica script for integrating first-order rate equations (see
"Basic combustion kinetics" handout).
For an illustration of SSA and RDS
see, for example, pp45-46 in H+K... See also this template that
explores the differences between the kinetics of fluidized bed combustion and
pulverized coal combustion. (And in Ref. B3-B4?)
Here is another
hopefully useful kinetics template (for solving first-order differential
equations).
In-lieu-of-class activity #1 (due in Angel dropbox by midnight
02/09):
(a)
Provide the missing numbers for a bituminous coal and a lignite in the handout
entitled "Exercise in combustion stoichiometry".
Here is one
version of the solution...
(b)
Provide the missing numbers and expressions in the handout entitled "Basic
kinetics->Arrhenius eqn"; for example, show that at 227 and 1187 oC the k values are 4.3x10-12 and
1.124 s-1, respectively. The activation energy should therefore be
166 kJ/mol... Right? (Makes sense?)
Here is one
version of the solution...
Note: Be sure to consult me (by
e-mail) if you have any doubts or questions about numbers or assumptions to use
in the resolution of these problems! But also describe how far you have gotten
in your own analysis of the problem(s).
In-lieu-of-class activity #2 (due in Angel dropbox by midnight
02/11): Many
air pollution problems (as indeed most issues in life) are a matter of relative
rates... The concept of rate-determining step (RDS, introduced in the class
handout entitled "Series vs. parallel reactions") should thus rank in
importance somewhere close to Einstein's equations or Newton's laws! Use the
above-mentioned handout to determine the rate of formation of S for the
consecutive scheme (A->R->S) in the following cases for [A] = 1 mol/m3:
(a) k1=10 s-1, k2=1 s-1; (b) k1=10
s-1, k2=100 s-1. In both cases compare the
exact solution with the appropriate approximate solution in which only the rate
constant of the appropriate RDS is considered. Express the discrepancy observed
as % error and comment. If the ratio of rates were two orders of magnitude
(instead of one), what would the corresponding % error be? Based on this
analysis, explain what is meant by RDS!
Here is one version
of the solution...
In-lieu-of-class activity #3 (due in Angel dropbox by midnight
02/13): Using the appropriate handout from class,
calculate the time required to achieve 20, 50, 90, 99, 99.9, and 99.99%
conversion of carbon burning in 1 atm air at 1800 K. (Note: As always,
if and when you need assistance or clarification, please ask specific questions
by e-mail, 24/7.)
Here is one version
of the solution...
In-lieu-of-class
activity #4 (due in Angel dropbox by midnight 02/16): Transport
processes (of heat, mass or momentum) – see handout "Intro to Transport
phenomena" -- occur most often in series with chemical reaction. As
an example of mass transfer, O2 molecules need to diffuse through
the boundary layer surrounding a burning coal particle in order for the
combustion reaction to take place.
Let's explore the intuitively more
didactic transport of heat through a
double pane window, in order to further grasp the RDS concept. Analyze pages 360-361 in Ref. B2 (see Syllabus) and
then show that the RDS for heat loss from a double-pane window (two 1/8"
panes separated by a 1/2" layer of stagnant argon gas) is, by a very wide
margin, the transfer of heat through the stagnant gas and not through the glass
pane(s). Determine both the corresponding R-values and the
temperature gradients (DT), and show that the RDS is the one
that exhibits the largest DT and thus
offers the largest resistance to heat loss (and also has the smallest
heat transfer coefficient (thermal conductivity), by analogy with the
problem we analyzed in the in-lieu-of-class activity #2). Assume the cross-sectional area of the window
to be 1 ft2 and the overall DT, between
indoors and outdoors, to be 54 oF, as in Illustration 19-2 in Ref.
B2.
Here is one version
of the solution...
CLEAN COAL TECHNOLOGY: It’s an increasingly
popular concept… What exactly does it mean?
-coal
composition, C/H ratio, S content, ash ‘content’, widely varying heating values
-PCC
(C+O2), nice example of Arrhenius-type
behavior (high T necessary)
-FBC
(AFBC, PFBC), CaO + SO2 + 0.5O2 = CaSO4 (intermediate
T OK, so lower NOx as well)
-IGCC (see, for
example, http://www.tampaelectric.com/news/powerstation/polk/igcc/),
C+H2O, C+O2 (Why? Thermo software:
Try StanJan or Chemeq.bas!)
-coal
liquefaction (makes sense at >$50/bbl?), C+H2 (OK, but where will
the H2 come from?)
-CO2
sequestration (“zero emissions”)
Extra credit
assignment:
In The NYT of 3/10/2007 (“TXU
Announces Plans for 2 Coal Plants Designed to Be Cleaner-Burning”), Krauss and
Wald make the following statement: “[T]he amount [of CO2] to be
sequestered is so much larger than the available oil field capacity. For
example, sequestering the carbon dioxide globally from 600 coal plants of 1000
megawatts each (a bit more than double what the United States has now) would
require injecting about 50 million barrels a day back into the ground. In
comparison, the world pumps a little more than 80 million barrels a day.” Show how these ball-park numbers are obtained and whether
they are ‘correct’ (or make sense, based on reasonable assumptions).
Another one: In a more recent article ("Scientists Would Turn Greenhouse Gas
Into Gasoline", 02/19/2008), Kenneth Chang of The NYT argues that gasoline "is an almost ideal fuel (except
that it produces 19.4 pounds of carbon dioxide per gallon)" because, among
other benefits, it "generates more energy per volume than most
alternatives." Provide calculations that show your (dis)agreement with
these arguments; in particular, make comments about any assumption(s) that
need(s) to be made to support their validity.
TRANSPORT PHENOMENA IN
COMBUSTION
Why
is mixing
(i.e., “fluid dynamics” or momentum, heat and mass transport) the RDS in
many combustion systems, thus often leading to formation of CO and soot?
Combustion time: parametric sensitivity analysis
Evaporative
emissions: constructing a ‘template’!
(You
want to avoid tedious calculations, so that you can understand a phenomenon
with the help of many quick “what if” analyses.)
Here is a
summary of useful physical, thermochemical and transport properties of many
gases (and liquids) of interest in air pollution control studies. Source: Properties of Gases and Liquids, 5th Ed.,
by Poling, Prausnitz and O'Connell, McGraw-Hill, 2001, available online through
the PSU library.
Also
available online are the CRC Handbook of
Chemistry and Physics, Perry's
Chemical Engineers' Handbook and Lange's
Handbook of Chemistry, among others... Can you find them?
To
understand the emissions of some air pollutants, a combination of tools or empirical
(statistical) information may be necessary...
-for NOx need combination of thermo
and kinetics: Zeldovich1 Zeldovich2 NOx analysis template
-for CO and PM need AP-42 (Can you find it? Is it easy to
understand, and thus accept, the AP-42 values for sulfur oxides?)
Terminal velocity
analysis (see Figure E11-6 in H+K)
Does this (appropriately?)
modified template help with #2? (If you adopt it, be sure to provide the
necessary explanations!)
Do you agree that the diffusivity
values for acetaldehyde, benzene, CCl4 and CHCl3 are, approximately,
1.1e-5, 8.3e-6, 7.5e-6 and 8.4e-6 m2/s? Does this trend agree with
that shown in Table A-8 of H+K (0.77e-5, 0.62e-5 and 0.87e-5 m2/s
for benzene, CCl4 and CHCl3)?
One version of the solutions: #1 #2 #2a #3 #4
Exam
#1: 1a: T 1b: T 2a: T 2b: T 3a: T 3b: T 4a: T 4b: F 5a: T 5b: F
In-lieu-of-class activity #5 (due in Angel dropbox by midnight
Friday, March 7): The
"bottom line" of atmospheric physics, which will allow us to convert
pollutant emissions (say, in kg/h) to pollutant concentration (say, in ppm),
can be summarized in three graphs: (a) pressure vs. height (above sea level),
(b) temperature vs. height, and (c) wind speed vs. height. Spend up to three
hours on the Internet and summarize your degree of success (or failure) in
finding such graphs, hopefully on reliable web sites. Some of the promising
initial key words should be "atmospheric pressure gradient", "atmospheric
temperature gradient", "lapse rate"...
WHAT CAN NATURE DO:
(RUDIMENTARY ASPECTS OF) METEOROLOGY OF AIR POLLUTION
Now
we need to convert tons/day of pollutant emissions to ppm (and hopefully ppb)
of pollutant concentration. For this, we need to understand and determine the temperature, velocity and
concentration gradients in the atmosphere. So we need to introduce
and/or review the basic concepts of heat, momentum and mass transfer (see above) as they apply to
meteorology (“weather”).
-see relevant handouts as well as Ch.
6 and, especially so, Ch. 9 in H+K
Analysis of pressure
gradients (Equations correct? TRUST BUT VERIFY! See Section 9.3 in H+K…
Effect on p vs. z curves?)
Analysis of wind speed
(…when intuition is NOT of much help!)
Visualization (and analysis?)
of plumes Richardson number
(parametric sensitivity analysis)
Another
type of 'plume': smog (smoke + fog)...
Have you seen The
Economist article "A large black cloud" (03.13.2008)?
And The Daily
Collegian of 03/18/2008 ("Air fails national smog test")?
Smog 101 A typical ozone
isopleth
Fundamentals:
GaussianDistribution1 (getting a feel for the Gaussian plume...)
GaussianDistribution2 (diffusion eqn...)
Box
model (extra credit assignment): Analyze Problem
9.7 in H+K (see also relevant class handouts and Section 9.1 in H+K)
and then carry out a parametric sensitivity analysis
by preparing the following graphs:
-effect of mixing height, from 50 to
1000 m
-effect of wind speed, from 1 to 15
m/s
-effect of wood burning rate, from
0.01 to 1 kg/min
A
simple Gaussian plume exercise
A
comparison of dispersion coefficients
Yet another
comparison (we better get these sigma values ‘right’… if not, all else will
be essentially meaningless)
Here is a simplified
("black box") Gaussian plume model
Here is one
solution to Examples 9.6 and 9.7 in H+K.
In-lieu-of-class
activity for March 28:
(1)
Download the ISCPC software.
(2)
See whether it works on an XP PC.
(3)
See whether it works on a Vista PC.
(4)
When you get it to work (if not, let me know asap), answer part (a) of #2 and
compare your result to the following:
A: 0.050 mg/m3 (at 1 m/s)
B: 0.036 mg/ m3 (at 2.5
m/s)
C: 0.036 mg/ m3 (at 5 m/s)
D: 0.015 mg/ m3 (at 5 m/s)
E: 0.005 mg/ m3 (at 3 m/s)
F: ca. 0 mg/ m3 (at 2 m/s)
Exam
2
-Here
(stability category B) and here
(stability category D) are the key points regarding #1.
-In #2 need to justify carefully
your selection of relevant box size, based on the shape of the CGL
vs. x curve.
-Be sure to tabulate the
results of your sensitivity analysis.
Part III: What must society do?
(Legislate and clean up, of course… And how about not polluting in the first place?
“Natural capitalism”?)
Introduction to air quality
legislation
Notes1 on Legislation Notes2 on Legislation Notes3 on Legislation
When
it comes to air quality legislation, use of up-to-date primary sources of information is
essential, e.g.,
http://www.epa.gov/ttn/atw/combust/boiler/cfrda98.pdf
http://www.epa.gov/ttn/atw/combust/boiler/cfrda02.pdf
Note
the subtle but very important difference for NOx? And more recently for (all?)
the other air pollutants?
For
the recent Clean Air Rules of 2004, see www.epa.gov/cleanair2004.
Here is an
example of the Code of Federal Regulations (primary source of
information)...
Nonattainment areas for criteria pollutants
And what about Hg?
Here
is an example of how to fill in the blanks in class handouts.
Homework 6:
Note that the various solutions (and their evaluations in the "peer
review" mode) are available on the Angel web site.
Two
additional transport phenomena concepts (needed to understand pollutant control
strategies):
GENERAL STRATEGIES FOR
POLLUTANT REMOVAL:
-before combustion (e.g., coal
gasification or liquefaction, petroleum HDS)
-during combustion (e.g., FBC,
air/fuel staging)
-after combustion (flue gas treatment)
Air pollution
control technology fact sheets
PM control:
brief overview of key issues
Adsorption:
overview
Absorption
(mass transfer) and dissolution (phase equilibrium): Henry’s law
and another illustration RDS
SOx control_1 SOx control_2 (the same applies, of course, to absorption-based CO2
removal…)
Reactive
absorption: another example of the usefulness and importance of the RDS
concept
Units of
the absorption mass transfer coefficient
(a fine example of the need to understand a phenomenon by studying the units of
its key parameters)
Here is a ‘template’
that should facilitate the analysis of adsorber performance (and capabilities!)...
NOx control
-Zeldovich mechanism:
an important example of combined thermodynamic and kinetic analysis Notes1 Notes2
-SNCR (selective non-catalytic
reduction): what is ‘selective’ about it?
-SCR (selective catalytic reduction):
what does the catalyst do?
Honeycomb catalyst:
the ‘wonder-muffler’! (oxidizes CO and unburnt HC (VOC), reduces NO…)
NOx, CO and HC vs. equivalence ratio (internal combustion engines)
CO emissions
control: Thermo + kinetics problem!
Catalytic
oxidation (combustion): a technology whose time has come (e.g., CH4,
CO, VOCs)!?
Example 7-4 in H+K
(Excel file) Example 7-4 in H+K
(Mathematica file)
In-lieu-of-class
activity #6 (due in Angel dropbox by midnight 04/21):
-Write an essay (a paragraph for each)
on the 'messages' of these two
cartoons from The Daily Collegian
of 04/17/2008. Analyze them carefully. What do they say or don't say? Discuss
how they are related to the issues covered in EGEE 470.
In-lieu-of-class
activity #7 (due in Angel dropbox by midnight 04/23):
-Fill in the blanks in at least three of the recent
class handouts. If you have questions or doubts, be sure to clarify them
through e-mail correspondence.
In-lieu-of-class
activity #8 (due in Angel dropbox by midnight 04/27):
-Upload the graph for part #1 of
problem #2 in HW7 and provide a brief commentary about its meaning. (To be
discussed in class on 04/28.)
Homework 7: The
various solutions, many of them very good and "correct" (and some
VERY nice!), are available in the "peer review" mode on the Angel web
site.
Exam 3 (due
in Angel dropbox by noon, May 7... Good luck, and have a wonderful and
productive summer!)
lrr3@psu.edu (last updated 05/07/2008, 07:50 am)
