870:186g: Studies in Air Quality
for Science Educators
Summer 2008 Name ___________________________________________
Period: ___ Date: _____ Score: _____/
National Ambient Air Quality Standards (NAAQS)
Simulated Smoke Plumes
A) Open the shared drive
folder on your computer. Open the
Czarnetzki subfolder
B) Double click on
QBASIC.
C) Press the Esc key to
clear the screen.
D) Use the mouse to
select the File option.
Select the Open option and then select the file PLUME1.BAS.
Then select the OK option.
Select the Run option and then select Start.
E) Take notes on the
values you enter next and the characteristics of the
resulting plume.
F) Enter the requested
parameters:
H:
heating category
U0: surface wind speed
in mph (can’t be calm)
generally, a light wind is probably about 1 to 5 mph, while a fast
wind is > 10 mph
CR: horizontal
compression ratio
on all displays, the tick marks are always 100 m apart
for CR=1, the downwind range drawn on the screen is 400 m
for CR=2, the downwind range drawn on the screen is 800 m
etc. (10 to 20 works well to
see farther downrange)
DW: deposition width
(really only need to use options 1 and 4)
options 1-3 give you a side view of the stack and plume
options 4-6 give you an upwind view of the stack and plume
G) For vertical scale
reference, note that the stack is 80 meters tall.
The
program
also simulates plume rise due to buoyancy and momentum of effluent.
H) Use the Pause key on
the keyboard to pause the simulation if you wish and
restart by pressing the Enter key.
I) Use the Esc key to
stop the simulation and then any key to continue.
J)
When you’re done with this exercise, select File then Exit to
close the program.
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1. Run experiments to
see if you can discover some rules about how the plume
behaves under each of the 5 heating categories and for slower and faster wind
speeds. Note also how the
location and degree of maximum ground concentration vary
with
meteorological conditions. Because
a random “seed” is used to create the
initial conditions, run the program several times with the same inputs
before you
make generalizations. In the
space on the next page, Note some of the rules you
discover.
Things to look for include i) location of surface deposition, ii)
intensity of surface deposition, and iii) approximate plume shape (coning,
fanning, etc.).
Heating Category
a) Daytime, intense
Light winds
Fast winds
b) Daytime, moderate
Light winds
Fast winds
c) Daytime, overcast
Light winds
Fast winds
d) Nighttime, cloudy
Light winds
Fast winds
e) Nighttime, clear
Light winds
Fast winds
2. Under what conditions
does the plume reach the ground very close to the stack?
3. Under what conditions
should pollutants be released to minimize the likelihood
that the
plume will reach the ground?
4. For the same wind
(say about 5 mph) and after the same amount of elapsed time
(at least
200 min), do more pollutants reach the ground close to the stack
under clear
or cloudy conditions (circle one for each) during:
a)
daytime
clear - or -
cloudy
b)
nighttime
clear - or -
cloudy
870:186g:
Studies in Air Quality for Science Educators
Summer 2008 Name ___________________________________________
Period: ___ Date: _____ Score: _____/
National Ambient Air Quality Standards (NAAQS)
The Gaussian Plume Model
1. In this exercise, you will use emission factors published by the EPA to estimate the production of PM by a hypothetical coal fired power plant in Waterloo that has a rated capacity of 750 MW (7.12 x 105 BTU/s). We’ll assume that the plant will burn subbituminous coal that averages 8,480 BTU/lb and has 5% ash by weight. The resulting Activity Rate would then be 0.0420 tons coal/s. Here are some relevant conversion factors:
1 kg = 1000 g = 2.2046 lbs
a) The general equation for emissions estimation is:
E = A x EF x (1 - [ER/100])
where:
· E = emissions;
· A = activity rate;
· EF = emission factor, and
· ER = overall emission reduction efficiency, %
If the emission factor for PM is (10A lbs PM)/(ton of coal), where A is the ash content in percent, and ER = 97.9, what are the PM emissions in lbs per second?
b) Convert your answer from (a) to grams of PM per second.
2. Open the Gaussian Plume Model spreadsheet in our shared drive folder.
3. Here are some default values for the secondary variables in the spreadsheet in case you change them and would like to restore the default values:
stack height = 122 m stack diameter = 8 m
stack gas velocity = 20 m/s stack gas temperature = 347 K
4. Enter your answer from 1b as the Emission Rate in the spreadsheet.
5. Describe the change in the
top-down and cross-sectional views of the plume and in the downwind location of
the maximum concentration as you change each of the following:
a) increase emission rate:
b) increase wind speed:
c) change stability class from A > B > C > D > E > F:
d) increase stack height:
e) increase stack diameter:
f) increase stack gas velocity:
g) increase stack gas temperature:
h) increase ambient temperature: