In: Civil Engineering
The urban air above the city of Shanghai if the mixing height
above the city is 1210 m, the width of the box perpendicular to the
wind is 105 m, the average annual wind speed is 15,400 m/hr, and
the amount of sulfur dioxide discharged is 1375 × 106 lb/yr. Is
this a conservative or non-conservative system? State all
assumptions. Sketch a diagram to represent the system. Write the
complete mass balance for SO2. Estimate the SO2 concentration in
the air leaving the city in μg/m .
Hint: Determine the wind flow in m3/hr.
avg wind speed = 15400/3600 = 4.27 m/s
wind flow = 1210*105*15400= 19.5657 m3/hr
SO2 discharge = 1375*106 lb/yr = 1375*106/365/24 = 16.63 lb/ hr = 117.74576437863671 mols/ hr
117.74576437863671 mols of SO2 = 22.4*117.745= 2637.50 litres/hr = 2.637 m3/ hr
concentration of SO2 in ppm = 1ppm of SO2= =
1 litre of SO2 has mass of = 64/22.4= 2.85 gm
1000litre or 1m3 = 2857.1gm
therefore 1 ppm of SO2 = 2857.1 gm/ 10^6 m3 =
1 ppm of SO2 = 2857.1micro gram / m3
0.0013441 ppm of SO2 = 3.840 microgram / metric cube
this a conservative system
assumption are standard temprature and pressure conditions
temperature of 273.15 K (0°C or 32°F)
and a pressure of 105 Pascals formerly 1 atm