AIR POLUUTION CONTROL course material by Prof S S JAHAGIRDAR,NKOCET,SOLAPUR for BE (CIVIL ) students of Solapur university. Content will be also useful for SHIVAJI and PUNE university students

1. Prof S S Jahagirdar, NKOCET
AIR POLLUTION
AND CONTROL
(Elective-I)
Problem set for
UNIT-VII
AIR POLLUTION
(PARTICULATE)CONTROL
EQUIPMENTS
Page | 1

2. BE (CIVIL)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-VII
Control equipment collection efficiency Problems
1.
A power plant has allowable SPM rate of 1.6 tonnes/day. Assume that it burns coal
at the rate of 3800 tonnes/day and coal has ash content of 4.5 %. Find overall
efficiency required for a SPM control device.
2.
Calculate the overall efficiency of a particulate control system composed of
cyclone (75 % efficient) followed by a ESP (95% efficient).
3.
A stream of gas from a manufacturing plant contains 50 gms/m3 of PM.
Regulations requires overall control efficiency of 98.5%. The proposed control
system consists of a cyclone (70% efficient) followed by ESP. Calculate
a) The allowable outlet concentration of PM
b) Efficiency of ESP
4.
A cyclone operates removes 75% of particulate matter fed to it. The filter is then
fed to an ESP which operates with 90% efficiency. What is the overall efficiency of
this particulate system?
Unit- VII

3. BE (CIVIL)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-VII
Gravity Settling Chamber Problems
1.
Calculate the terminal settling velocity for a particle of 10 µ diameter in air at 250C
and having density of 1.5 gm/cc. Assume all the necessary data.
2.
A gravity settling chamber is to be used to remove particulates having dia 80 µ and density
1.5 gm/cc. What is the maximum gas velocity that can be used if the chamber is 9 m long
and 3 m high and the desired collection efficiency is to be not less than 90 %?
3.
A gravity settling chamber is to be used for following data
SPM dia- 100 µ
SPM density – 1500 kg/m3
Length of chamber – 10 m
Height of chamber – 2 m
Efficiency should not be less than 90 %. What is max gas velocity that can be used?
5.
A settling chamber is designed to process a flow of 150 m3/sec. Chamber length -15 m,
height – 3m and width – 5 m. Determine the efficiency of the chamber for removing 1 µ, 5
µ, 10 µ, and 20 µ dia particles having density 1.5 g/cc.
6.
A gravity settling chamber is to remove 50 µ dia particles having density 1.5 gm/cc. What is
max gas velocity that can be use if the chamber is 6 m long and 2 m high? The efficiency
expected is more than 90 %
7.
A settling chamber is to be designed for a waste gas flow of 30 m3/sec at 700C. The particles
to be removed are 30 µ with 80 % efficiency. Design the chamber with trays and also
calculate efficiency for 15 to 25 µ dia particles
8.
Estimate the value of minimum size of particles to be removed with 100 % efficiency for a
settling chamber with length 8 m, height 1.3 m and gas velocity 25 cm/sec. The temperature
is 800F. The density of particle is 2.5 g/cm3. Viscosity of gas at given temperature is 0.067
kg/m.hr.
9.
A settling chamber is designed to remove particulates from an air stream having velocity of
2 m/s and temperature of 770C. The chamber has a size of 6.25 m x 2.5 m. Determine the
size of particles which are removed 100 %. Use specific gravity of particle =2 and air
viscosity = 2.1 x 10-5 kg/m.s. If the length is changed to 8.5 m, what is percentage change in
removal efficiency of above sized particles?
10.
What is smallest diameter of particulates in µ having a density of 2 gm/cc which can be
collected with 80 % efficiency in gravity settling chamber which is 12 m long and 3 m high.
Unit- VII

4. BE (CIVIL)
L-
ROLL NO-
Gas velocity is 0.78 m/sec. Mention how you can improve the efficiency?
11.
Calculate the terminal settling velocity for a particle of 1 µ diameter in air at 270C
and having density of 1.85 x 10-5N.S/m2. Assume all the necessary data.
12.
Determine minimum size of particulates that will be removed with 100 % efficiency from a
settling chamber, under following conditions
i.
Air : Horizontal velocity= 0.3 m/sec
Temp = 770C
ii.
Particles : Sp Gr = 2.0
iii.
Chamber : Length = 7.5 m
Height = 1.5 m
What will be efficiency for same particles if chamber length is 6 m?
13.
A settling chamber is designed for removing 80µ dia particles with 100 % efficiency. The
particulate matter density is 1500 kg/m3. Depth and width of chamber is 2 m each.
Determine:i.
ii.
Unit- VII
Length of chamber required without trays.
Length of chamber with 10 trays.

5. BE (CIVIL)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-VII
Cyclone Problems
1.
A cyclone is designed with an inlet of 10 cm and 5 effective turns. The inlet gas
velocity is to be 10 m/s and particulate density is 1.7 gm/cc. Estimate the particle
size that will be collected with 50 % efficiency, if the gas is air and its temperature
is 3500 K. Viscosity of air is 0.075 kg/m.hr
2.
A cyclone is designed with an inlet of 13 cm and 4 effective turns. The inlet gas
velocity is to be 16 m/s and particulate density is 1.7 gm/cc. Estimate the particle
size that will be collected with 60 % efficiency, if the gas is air and its temperature
is 350 0K. Viscosity of air is 0.0748 kg/m.hr
3.
An air stream with flow rate of 7 m3/sec is passed through a cyclone of standard
proportions. The diameter of cyclone is 2m and air temperature is 770C and
numbers of effective turns are 5. Density of particle is 1500 kg/m3
i.
ii.
4.
Determine the particle size which can be removed with 50 % efficiency.
Sketch the cyclone giving all dimensions in meter.
A cyclone is designed with an inlet of 10 cm and 4 effective turns. The inlet gas
velocity is to be 15 m/s and particulate density is 1.5 gm/cc. Estimate the particle
size that will be collected with 50 % efficiency, if the gas is air and its temperature
is 3500 K. Viscosity of air is 0.075 kg/m.hr.
5.
An air stream with a flow rate of 7 m3/sec is passed through a cyclone of standard
proportions. The dia of cyclone is 2 m. µ = 2.1 x 10-5 kg/m-sec.
a) Determine the removal efficiency for a particle with a density of 1500
kg/m3 and a dia of 10 µ. Take Ne = 5 turns
b) Determine the collection efficiency base on the above if bank of 64
cyclones with diameters 24 cm are used instead of single cyclone.
6.
A conventional cyclone with dia. 1 m handles 3 m3/sec of standard air, carrying
particles with a density of 2000 kg/m3. For Ne = 6, determine the cut size and the
efficiency as function of particle diameter. µg = 1.81 x 10-5 kg/m-sec
Unit- VII

6. BE (CIVIL)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-VII
Bag house filter Problems
1.
A filter bag house is to be designed for a gas flow of 150 m3/sec. Make necessary
assumptions and determine the size of bag and no. of bags. Draw neat sketch
2.
A fabric filter is to be constructed using bags having 22 cm diameter and 6 m height.
The bag house is to receive 12 m3/s of air and filtering velocity is restricted to 2
m/min. Determine the number of bags required for a continuously cleaned operation.
3.
A fabric filter is to be constructed using bags having 0.2 m diameter and 6 m height.
The bag house is to receive 10 m3/s of air and air to cloth ratio is 2 m/min. Determine
the cloth area and number of bags required.
4.
A fabric filter must process 15 m3/sec of waste gas. The bag house is to be divided
into 8 sections of equal cloth area, so that one section can shut down for cleaning
while other continues operations. Assume air to cloth ratio 9 m3/min/m2 and bag
diameter 0.25 m and 7 m long. Determine no of bags and physical arrangement
5.
Determine no of bags necessary to treat 16 m3/sec of polluted air laden with
particulates. The air/cloth ratio = 10 m/min. The bags have 0.25 m dia and 7 m length
Unit- VII

7. BE (CIVIL)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-VII
Electrostatic Precipitator (ESP) Problems
1.
An ESP with overall spacing 23 cm and mean gas velocity of 1.5 m/s has collector
plate area of 6000 m2 gives 97 % efficiency in treating 200 m3/s of flue gas. To
achieve 98 % and 99 % efficiency what should be plate area required?
2.
For an ESP of given geometry and operating conditions, the collection efficiency
for 2 µ particle is 99.90 %. On the basis of Deutch equation for efficiency, estimate
the collection efficiency for
i.
ii.
0.5 µ
iii.
3.
1µ
0.1 µ.
Design the ESP are for controlling 40 m3/s of dirty gas containing 60 % particles of
1 µ dia, 40 % of 0.5 µ dia. The overall efficiency required is 99 %
Unit- VII