This document analyzes particulate control in a thermal power plant using an electrostatic precipitator (ESP). It investigates ESP performance at the Korba East Phase III power plant in India. Mathematical models are used to predict emission levels based on ESP dimensions and migration velocity. The models show that higher migration velocity and fly ash percentage lead to lower required collection area to meet emissions standards. Upgrading ESPs with advanced control systems is a more cost effective solution than increasing ESP size.

1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME
149
INVESTIGATION OF PARTICULATE CONTROL IN THERMAL
POWER PLANT USING ELECTROSTATIC PRECIPITATOR
Sanjay paliwal1
, H.Chandra2
1
Research Scholar, Singhania University Jhunjhunu, Rajasthan, India
2
Department of Mechanical Engineering, Bhilai Institute of Technology, Durg (CG) India
ABSTRACT
Analysis of particulate control in thermal power plant using electrostatic precipitator
has been carried out by using standard mathematical models supplemented by the relevant
data collected from Korba East Phase (Ph)-III thermal power plant, under Chhattisgarh State
Electricity Board (CSEB) operating at Korba, Chhattisgarh, India. The mathematical models
have been used to predict the emission level for different parameters of ESP. In this paper
focuses on the Indian power scenario in view of Coal based thermal power generation.
Several types of pollutants emitted from power plant are considered but the main focus of this
paper is air pollutants emitted from thermal power plants. It is shown that significant
improvement in thermal efficiency and environment advantages may be obtained for a coal
based thermal power plant.
1 INTRODUCTION
Out of different air pollutants ash is mineral matter present in the fuel. For a
pulverized coal unit 60-80 % of ash leaves as fly ash with the flue gases. Though there are
several devices for collection of fly ash, the two efficient (≥ 99 % collection efficiency)
emission control devices are fabric filters and Electrostatic Precipitator (ESPs). Fabric filters
has low installation cost but high maintenance cost; and large pressure drop, which reduces
the plant efficiency. The ESP is one of the most widely used devices for controlling
particulate matter especially fly ash. Although they often demand higher capital investment in
comparison with gas cleaning methods, the low operating cost and maintenance costs, the
high collection efficiency (> 99%) & the ability to face severe operating conditions make
ESPs suitable in the pollution problems characterizing many process installations such as
coal-based thermal power plants, cement plants, iron industries and glass manufacture [1],
[2], [9], [10], [11], [12].
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ISSN 0976 – 6340 (Print)
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Volume 4, Issue 3, May - June (2013), pp. 149-154
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The ESP once designed for a set of parameters to provide certain efficiency will
definitely not function to the desired level if the designed parameters are changed. Certainly
the design can accommodate a little variance in the parameter but one should not expect
miracle from an ESP. It is costly to replace the old ESPs, however after proper investigations,
they can be made function quite efficiently by replacing/ upgrading of some of the
components adopting better operational methods [3],[11].
Upgrading or designing mostly means taking account of stricter inlet and outlet
requirements resulting from the latest emission limits set by public authorities. For this reason
a comparison of the original and new rating specifications is imperative. In doing this it is
important to look at as many as possible previously taken measurement readings, especially
the measurement made in the course of acceptance tests, and to compare and evaluate them
with reference to the required future performance [5].
In this paper analysis has been carried to predict emission levels achieved based on
the dimensional and migration velocity obtained during operation of ESPs selected in Korba
East Ph-III power plant of CSEB. New parameters of ESPs have been obtained for meeting
improved emission standards.
2 SPECIFICATION OF PLANT
As per the requirement of different data for the coal analysis, coal is taken into
account from Manikpur coalmines (open cast mines) at Korba district of Chhattisgarh. The
ash content has been taken on the basis of collection of five years data of “analysis of coal as
received from the Manikpur coalmines”. Three cases of ash are analyzed, which are:
(i) Minimum ash case: A=38.6%, M=5.5%, V.M=21.6%, F.C=33%
(ii) Average ash case: A=42%, M=5.1%, V.M=20.5%, F.C=32.4%
(iii) Maximum ash case: A=43.1%, M=5.1%, V.M=19.7%, F.C=32.1%
Where A, M, V.M, F.C are ash, moisture, volatile matter, and fixed carbon respectively.
The data for the ultimate analysis of the Manikpur coal, on as received basis in
percent is taken from the Central Power Research Institute (CPRI) –materials technology
division, C.S.E.B, Korba (east) dated 21-02-2012. It is shown as below:
Carbon (C) =37.9%, Hydrogen (H) =3.38%, Nitrogen (N) = 0.69%, Sulfur (S) = 0.43%.
Now the technical specification of the ESP (used for fly ash collection from
pulverized coal fired boiler flue gas) at Korba East Phase (Ph)-III thermal power plant (2×120
MW), as provided by [4] is given below:
(1) Design conditions: gas flow rate = 215 m3
/s, temperature = 1410
C, dust concentration
(inlet) = 90 gm/Nm3
.
(2) Type of precipitator: FAA-4*45-2*72-140
(3) Number of ESP/boiler = 2
(4) Number of gas path/ boiler = 1

3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME
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(5) Number of fields in series/ gas path = 4
(6) Guaranteed collection efficiency for design condition = 99.83 %
(7) Treatment time = 33.75 seconds
(8) Collection electrodes: total number of collecting plates/ boiler = 2352, nominal height
of collecting plate = 14 m, nominal length of collecting plate = 750 mm
(9) Emitting electrodes: type = spiral, number of electrodes/ESP = 10368, spacing (mm) =
200/ 300
(10) Dust hoppers: number of hoppers/boilers = 16, capacity = 1936 kg
(11) Rectifier: rating = 70 kV (peak) 800 mA, number = 8/ESP, type = semiconductor
diodes full wave, location = ESP roof
(12) Migration velocity = 0.028 m/s
(13) Total collection area = 48388 m2
(14) Area per gas path = 24193.95 m2
3 METHODOLOGIES
3.1 Sampling
Feed coal and electrostatic precipitator (ESP) fly ashes were at Korba East Phase
(Ph)-III thermal power plant. The contents of the coal samples have been collected and the
percentages of oxygen (O).For the investigation of particulate matter, using ESPs in thermal
power plant, standard mathematical models are used. To get the collection efficiency of ESP
it is required to know the inlet dust concentration to ESP. For this some parameters are
required and are given below.
3.2 Analysis
The contents of the coal samples have been collected and the percentage of oxygen
(O) in the coal is calculated by using following formula [6] taking coal as 100 %:
O = 100 – (C+H+N+S+A+M) (1.1)
Where, O, C, H, N, S, A, and M are percentage of oxygen, carbon, hydrogen, nitrogen,
sulfur, ash and moisture in coal sample.
Now the theoretical air-fuel ratio (A/F) is calculated by [7].
(A/F)th, m, d = (2.66 C + 7.94 H2 +0.998 S – O2)/ 0.232 kg of air/ kg of fuel (1.2)
where, A/F is air-fuel ratio, ‘th’ is for theoretical, ‘m’ is for gravimetric (mass), ‘d’ is
for dry, and C, H2, S, & O2 are percentage of carbon, hydrogen, sulfur, & oxygen in coal
sample.
(F/A)th, m, d = 1/{(A/F)th, m, d} kg of fuel/ kg of air (1.3)
Volume of air = Vair = V1 = mass of air (mair)/ density of air (ρair) m3
/ kg of fuel (1.4)

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Where, mair = (A/F)th, m, d kg of air/ kg of fuel, and ρair = density of air at 1410
C (design
condition temperature of ESP) is 2.556 kg/ m3
.
Let volume, temperature and pressure of air at Normal Temperature and Pressure
(NTP) is V2, T2, and P2 respectively, then:
(P1V1)/T1 = (P2V2)/T2 (1.5)
Where, P1, V1, and T1 are pressure, volume, and temperature of air ate design condition of
ESP. If P1 = P2, T1 = (141+273) = 414 K and T2 = 273 K, then:
V2 = (V1T2)/ T1 Nm3
/ kg of fuel (1.6)
V3 = (V2)/ 1000 Nm3
/ gm of fuel (1.7)
Inlet dust concentration (m1) = {(F/A)th,m,d ×A×FA}/{EA × V3} gm/Nm3
(1.8)
Where, A, FA and EA are percentage ash, fly ash (taking as 80%, 85%, and 90%) and
excess air (105%).
After getting value of m1 we can perform design analysis of ESP. The collection
efficiency of ESP (η) is given as:
η = 1- (m2/m1) (1.9)
Where, m2 = outlet dust concentration (gm/Nm3) which has maximum value of 0.150
gm/Nm3
according to CPCB. The collection efficiency of ESP (η) is also given by Deutsch-
Anderson equation [2], [8].
η = 1- exp {(-wA)/Q} (1.10)
Where, w = migration velocity (m/s), A = total collection area of plates (m2
) and Q=
volume flow rate of gas stream (m3
/s) = 215 m3
/s.
4 RESULTS AND DISCUSSIONS
By using above mathematical model we will take results for percent change in total
collection area (as the original total collection area is 48388 m2
); for two cases: (i) changing
migration velocity (from 0.028 to 0.04 m/s) & keeping other variables constant, (ii) keeping
migration velocity constant and changing other variables. All the calculation is done for the
cases, minimum ash, average ash & maximum ash. When the migration velocity is changing
then results are drawn for each specific outlet dust emissions of 0.150, 0.125, 0.100, 0.075, &
0.05 g/Nm3
by varying inlet dust concentration (Fig. 1).

5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME
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Fig.1 Manikpur coal, minimum ash, outlet emission = 0.150 gm / Nm3
Also when migration velocity is changing then results are drawn for constant inlet dust
concentration & varying outlet emissions (Fig.2).
Fig.2 Manikpur coal, inlet dust concentration = 46.5 gm/Nm3
Similarly, when keeping migration velocity constant then results are obtained by varying inlet
dust concentration (Fig. 3).
Fig. 3 Manikpur coal, migration velocity = 0.028 m/s
-39
-32
-25
-18
-11
-4
3
46 48 50 52
%ChangeInTotalCollectionArea
Inlet Dust Concentration(gm/Nm3)
w-0.028
w=0.03
w=0.035
w=0.04
Linear (w-0.028)
Linear (w=0.03)
Linear (w=0.035)
Linear (w=0.04)
-43
-36
-29
-22
-15
-8
-1
6
13
20
0.04 0.08 0.12 0.16
%ChangeInTotal
CollectionArea
Outlet Emissions(gm/Nm3)
w=0.028
w=0.030
w=0.035
w=0.04
Linear (w=0.028)
Linear (w=0.030)
Linear (w=0.035)
Linear (w=0.04)
-43
-36
-29
-22
-15
-8
-1
6
13
20
0.04 0.08 0.12 0.16
%ChangeInTotal
CollectionArea
Outlet Emissions(gm/Nm3)
w=0.028
w=0.030
w=0.035
w=0.04
Linear (w=0.028)
Linear (w=0.030)
Linear (w=0.035)
Linear (w=0.04)

6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME
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The results reveal that for a constant outlet emission and fly ash percentage, the total
collection area decreases with the increase in migration velocity. For constant migration velocity
and outlet emission, the total collection area increases with the increase in the fly ash percent. For
constant migration velocity and outlet emission, the total collection area increases with the ash
content in the coal. i.e. from minimum ash to maximum ash. As far as the efficiency is concerned,
it increases with the fly ash percent and the inlet dust concentration while, it also increases with
the ash content but it decreases with the outlet emission at constant migration velocity, fly ash
and ash content.
5 CONCLUSIONS
The investigation shows in order to meet the better emission standards the size of ESPs
should be increased which is costly affair. A cheaper option is to adapt micro processor controller
charging system which will enhance the migration velocity and hence met the emission standards.
The cost of such device will be much cheaper as compared to increase the size of ESP.
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