air pollution control unit iv problem set

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Prof S S Jahagirdar, NKOCET

AIR POLLUTION

AND CONTROL

(Elective-I) Problems set for

UNIT-IV

AIR POLLUTION METEOROLOGY

BE (Civil) L- ROLL NO-

Air pollution (Elective -I)

Unit-IV

Stability conditions (Temperature gradient) Problems

1. On the basis of temperature gradient in the situation described below classify the degree of

stability of atmosphere.

i. Temp at ground 340C and temp at 500 m height is 400 C

ii. Temp at ground 350C and temp at 650 m height is 220 C

iii. Temp at ground 250C and temp at 700 m height is 280 C

iv. Temp at ground 250C and temp at 200 m height is 50 C

2. Temperature at ground level is 30OC. Find the atmospheric stability condition in each

of the following cases.

Case Altitude (m) Temp. (OC)

I 700 10

II 500 34

III 1000 25

IV 500 20

3. Determine whether the atmosphere is unstable, neutral or stable for the following case.

Initial Temperature 30.2 oC

Final Temperature - 58.5 oC

Initial Height 221 m

Final Height 23214 m



Unit-IV

Finding Wind speed at higher altitudes Problems

1. The wind speed at 10 m altitude is 5m/s. Find the wind speed at 250 m altitude for

the following stability conditions.

i. Large lapse rate

ii. Zero or small lapse rate

iii. Moderate inversion

iv. Large inversion

2. Wind speed at 10 m altitude is 2m/s. Find the wind speed at 200 m altitude for

following cases

i. Large lapse rate

ii. Zero lapse rate

iii. Moderate inversion

iv. Large inversion

3. The ground level wind velocity at 10 m elevation is 5.2 m/sec in a city. What would

you estimate the velocity to be at 125m elevation in moderately stable atmosphere?



Unit-IV

Maximum Mixing Depth (MMD) Problems

1. At a given location the ground Environmental air temperature is 180 C, while normal

maximum surface temperature for the month is known to be 300 C. At an elevation of

700 m the temperature of the atmosphere measured is a) 150 C and b) 200 C. What is

maximum mixing depth in meters for two cases?

2. Air parcel temp at ground level is 280C. The environmental temperature at ground

level is 300 and at 500 m is 27.5 0C. Determine the MMD

3. A rising parcel of dry air has a temp of 300 C at sea level. Assuming DALR of -

10C/100m, determine MMD if environmental temperature temp at sea level is 150C

and ELR is +10C/100 m

4. In a given situation ground level temperature is 180C, while normal maximum surface

temp for that month is a) 26 0C and b) 240C. At an elevation of 300 m the temperature

is found to be 210C. What is MMD in metres for both the cases?

5. A rising parcel of dry air has a temp of 350 C at sea level. Assuming DALR of -

10C/100m, determine MMD if environmental temperature temp at sea level is 150C

and ELR is +10C/100 m

6. Determine the maximum mixing depth if flue gas temperature is 30oC, when:

i) Average ground temperature is 20 oC and temperature at elevation of 600 m

is 30oC

ii) Average ground temperature is 25 oC and temperature at elevation of 500 m

is 20oC

Assume DALR= -9.8 oC/1000 m.

7. Calculate the maximum mixing height from the following early morning temperature data given below:

The maximum surface temperature for the day was 15oC.

Height (m) 0 250 350 450 550 650

Temperature (oC) 9.5 12.2 15.1 15.6 16.2 16.5



Unit-IV

Minimum (safe) Stack height determination Problems

1. A factory uses 1.5 ML of fuel oil per month. The exhaust gases from factory

contain the following quantities of pollutant per ML per year:

i. Particulate matter = 5 t/yr

ii. Sulphur dioxide= 21 t/yr

Determine the safe height of chimney required for safe dispersion of pollutants.

2. A factory uses 2 ML of fuel oil per month. The exhaust gases from factory contain

the following quantities of pollutant per ML per year:

i. Particulate matter = 5 t/yr

ii. Sulphur dioxide= 21 t/yr

iii. Nitrogen dioxide= 4 t/yr

Determine the safe height of chimney required for safe dispersion of pollutants.



Unit-IV

Plume rise Problems

1. The heat emission rate associated with a stack gas is 4800 KJ/sec, the wind and

stack gas speeds are 5 m/s and 15 m/s respectively and the inside dia of stack top is

2m. Estimate the plume rise by

i. Carson Mosses

ii. Concave

iii. Holland’s formula

2. The wind and stack gas speeds are 3 m/s and 6 m/s respectively and stack dia is 2m.

The atmospheric stability condition is neutral with a temp of 3000K and the stack gas

temp is 4400K. Estimate plume rise in m by Brigg’s equation and TVA model

equation.

3. Determine the effective stack height given by following data

i. Physical stack height= 203 m

ii. Inner dia of stack = 1.07 m

iii. Air temp =130C

iv. Barometric pressure = 1000 mbar

v. Stack gas velocity = 9.14 m/s

vi. Stack gas temperature = 1490 C

vii. Wind velocity at stack top = 5 m/s

4. Determine the effective stack height given by following data

i. Physical stack height= 180 m

ii. Inner dia of stack = 0.95 m

iii. Air temp =20 0C

iv. Barometric pressure = 1000 mbar

v. Stack gas velocity =11.12 m/s

vi. Stack gas temperature = 1600 C

vii. Wind velocity at stack top = 2.75 m/s



Unit-IV

Emission rate Problems

1. A power plant burns coal at the rate of 500 kg/hr. It consists of ash 30 %, Sulphur -3

% and carbon 40 %. Determine the emission rates of SPM and SO2 in mg/m3 and

gm/sec.

2. A power plant burns coal at 500 kg/hr per MWe. Capacity of power plant is 500

MWe.

Coal contains 30 % ash and 1 % sulphur and 40 % carbon.

Determine

i) SPM emission

ii) SO2 and CO2 emission

iii) Quantity of air required for combustion.

3. A power plant burns coal at the rate of 500 kg/min. It consists of ash 30 %, Sulphur -

1 % and carbon 40 %. Determine the emission rates of SPM, CO2 and SO2 in mg/m3

and gm/sec.

4. A power plant burns 25 tonnes of coal/day having 30% ash. Determine the efficiency

of particulate matter control equipment to maintain SPM level below 150

microgram/m3. If stack dia is 2.5 m and flue gas velocity is 9 m/s.

5. A power plant uses 500 kg of coal/hr. Coal contains 40% ash and 2% sulphur. Stack

diameter at exit is 2 m and the stack gas velocity is 20 m/s and temp is 1000C.

Calculate

i. SPM concentration in microgram/m3

ii. SO2 emission in ppm

iii. How much efficiency should be kept for the dust control equipment to

meet emission standard of 150 micrograms/m3



Unit-IV

Gaussian dispersion model Problems

1. A thermal power plant burns coal at the rate of 10 t/hr and discharges the fuel gas

though a stack having effective height of 90 m. The coal has sulphur content of 4%.

The wind speed at stack top is 6m/s. The atmospheric stability class is ‘C’. For this

class at downwind distance of 2000m the constants σy and σz are 200 and 120

respectively. Find the concentration of sulphur dioxide at ground level at 2000m

downwind and 500m crosswind distance.

2. A power plant burns 5 tons of coal per hour with 4% sulphur content, discharges the

product through a stack with 75 m effective height. The velocity of wind at top of

stack is 6 m/s and atmospheric stability class is ‘C’. Determine the maximum ground

level concentration of SO2. Also determine the ground level concentrations at 3.0 km

downwind and cross wind distance of 0.4 m on the either sides of centreline for ‘C’

class stability on the either side of centreline

Distance in m σy in m σz in m

850 88 53

3000 280 170

3. A coal fired power plant emits SO2 at a rate of 200 g/s. If effective stack height is 60

m determine the ground level concentration downwind if wind speed at 60 m height

is 4 m/s and stability class prevailing is ‘B’

Distance 0.5 km 1 km 2 km 3 km

σy in m 70 160 310 420

σz in m 50 140 360 700

Plot concentration versus distance on log x log scale.

4. A coal fired power plant burns 20,000 tonnes of coal per day. Coal contains 3%

sulphur, physical stack height=150 m, stack dia at top 4m, Stack gas velocity= 20

m/s and temperature is 1400 C. Surrounding air temperature is 1200 C and pressure

1000 mbar. Wind speed at 150 m = 6 m/s, Env lapse rate = +10 C/100 m.

Determine

1. Plume rise by Brigg’s formula

2. SO2 concentration at 1000 m downwind from stack (centreline) for ‘B’


class stability, if σy in m= 170 and σz in m= 140 at 1000 m.

5. A coal fired power plant emits SO2 at a rate of 100 g/s. If effective stack height is

100 m determine the ground level concentration downwind if wind speed at 100 m

height is 4 m/s and stability class prevailing is ‘B’


σy in m 70 160 310 420

σz in m 50 140 360 700

Plot concentration versus distance on log x log scale.

6. A coal fired power plant emits SO2 at a rate of 300 g/s. If effective stack height is

150 m determine the ground level concentration downwind if wind speed at 10 m

height is 4 m/s and stability class prevailing is ‘B’


σy in m 70 160 310 420

σz in m 50 140 360 700

7. SO2 is emitted at a rate of 0.9 kg/sec from a stack with effective height of 220 m.

The wind speed at that height is 5 m/sec and stability category is ‘B’. Determine the

downwind centre line concentration in micrograms/m3 at ground level distance from

stack of 1) 0.5 km 2) 1km,3) 2km and 4) 3km. Plot C versus log of distance curve


σy in m 110 160 300 450

σz in m 65 120 220 310

8. A coal fired power plant burns coal at the rate of 500 kg/hr. Coal contains 1%

sulphur and 30% ash, physical stack height=100 with plume rise of 50 m. Wind

speed at stack top is 5 m/sec.

Determine

1. Determine SO2 and SPM emission rate.

2. Also determine GLC of SO2 and SPM at 1000m from stack for ‘B’ class

stability, if σy in m= 60 and σz in m= 25 at 1000 m.

Assume all the other data.

9. An industrial boiler is burning at 12 tons (10.9 mton) of 2.5% sulfur coal/hr with an

emission rate of 151 g/s. The following conditions exist: H = 120 m, u = 2 m/s, y =

0. It is one hour before sunrise, and the sky is clear. Determine downwind ground

level concentration at 10 km.


10. If emissions are from a ground level source with H = 0, u = 4 m/s, Q = 100 g/s, and

the stability class = B, what is downwind concentration at 200 m?

11. A stack in an urban area is emitting 80 g/s of NO. It has an effective stack height of

100 m. The wind speed is 4 m/s at 10 m. It is a clear summer day with the sun

nearly overhead.

Estimate the ground level concentration at:-

a) 2 km downwind on the centerline and

b) 2 km downwind, 0.1 km off the centerline.

air pollution control unit iv problem set

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