372 ENVIRONMENTAL ENGINERING
What type of plume would you expect if the exit temperature of the plume at the stack
were 15°C and the smokestack were 40 m tall? 120 m tall? 240 m tall?
18.4 Three industrial emitters and an air sampling station are located at the
following coordinates on a map (the Y axis points North; the X axis East):
Industrial Plant A at X = 3, Y = 3
Industrial Plant B at X = 3, Y = 1
Industrial Plant C at X = 8, Y = 8
Air sampling station at X = 5, Y= 5.The data at the air sampling station are:
Day Wind direction Particulates (pg/m3) SO2 (~g/m~)1 N 80 80
2 NE 120 20
3 Nw 30 30
4 N 90 40
5 NE 130 20
6 sw 20 180
7 S^30 100
8 sw 40 200
9 E 100 60
10 W 10 100Draw wind roses and pollution roses, and determine which plant is most guilty of the
measured air pollution.
18.5 Using Eq. (18.7), derive an expression for the maximum ground level con-
centration in terms of the wind speed u and the dispersion constants cy and 0,.
18.6 A power plant burns 1000 tons of coal per day, 2% of which is sulfur.
All of the sulfur is burned completely and emitted into the air from a stack with
an effective height of 100 m. For a wind speed of 6 ds, calculate (a) the ground level
SO2 concentration along the plume center line 10 km downwind, (b) the maximum
ground level SO2 concentration for B stability, using a conservative value for the
wind speed, and (c) the downwind distance of maximum ground level SO2 for B
stability.
18.7 The power plant in Problem 18.6 uses coal with a 14% by weight ash content,
half of which is fly ash (entrained in the off-gas). If the ash particles (which we assume
to be uniform!) have a diameter of 15 pm and a density of 1.5 g/cm3, calculate the ash
deposition rate along the plume center line (a) 5 km downwind on a bright sunny day
and (b) l0km downwind on a night when the weather is overcast. Use the minimum
compatible wind speeds.
18.8 The odor threshold of hydrogen sulfide is about 0.7 pg/m3. If 0.08 g of
H2S is emitted per second out of a stack with an effective height of 40m during an
overcast night with a wind speed of 3 m/s, calculate the maximum ground level con-
centration of H2S and estimate how far downwind this concentration occurs. Estimate