The document presents a set of problems related to air pollution control equipment, specifically focusing on particulate control systems such as cyclones, gravity settling chambers, bag filters, and electrostatic precipitators. It includes calculations for efficiencies, gas velocities, settling velocities, and design parameters for various particulate sizes and flow rates. The problems address both theoretical concepts and practical design considerations for environmental engineering applications.

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