INTRODUCTION TO AIR POLLUTION ENGINEERING
OPEN BOOK EXAMINATION
Question 1: Which emits more SO2 per unit amount of electricity produced: a
coal-fired plant with 85% efficient S02 scrubbers or an oil-fired plant with no
scrubber? The coal has a heat content of 11,000 Btu/lb and contains 2.8%
sulfur, and that the oil has a heat content of 6.0 (10)6 Btu/barrel (1 barrel= 42
gallons) and contains 0.85% sulfur. Assume the oil has a specific gravity of 0.91.
Do the above plants meet New Source Performance Standards? State your
assumptions.
Question 2: Determine the centerline, ground-level concentration of SO2 1 km
and 5 km downwind from a 400-megawatt power plant burning 8000 tons of 1.5%
sulfur coal per day. The effective stack height is 200 m on a clear, sunny day.
The atmospheric stability was recorded using sigma theta. The value of sigma
theta was 10 degree. The wind recorded on the same day was 3 m/sec at 10 m
above the ground. The dispersion coefficients at these distances are:
y z
X
(m) (m)
(km)
1
140 125
5
540 500
Question 3 (a): A company has bought a Scrubber system in 1995 for $60,000.00. The
estimated life of the machine is five years, after which it has salvage value of $ 100.00.
Find the annual depreciation by the straight-line method.
Question 3(b) Calculate the maximum mixing height from the following early
morning temperature data given below:
Height (m)
Temperature (oC)
0
200
300
400
500
600
10.0
11.5
16.2
18.0
15.2
15.3
The maximum surface temperature for the day was 18.5 oC.
Question 4: The rate of emission of SO2 from the stack of a power plant is 180
gm/sec. The stack height is 58 m. Calculate the effective stack height on a
sunny September day when the wind velocity is 6 m/sec. Use Class C stability.
The effluents are being released at 9 m/s and at a temperature of 300 oK. The
atmospheric temperature is 292oK. The stack diameter is 0.8 m.
Question 5: A cyclone has been designed with an inlet width of 10 cm and an inlet
height of 6 cm. The height of the main upper cylinder is 16 cm and the height of the
lower cone is 16 cm. The inlet gas velocity is 16 m/s and the particle density is 1.6 gm/cc.
The working temperature of the process is 400o K. Estimate the particle size that will be
collected with 50 percent collection efficiency.