Verification and Validation of Preliminarily Result of CFD ...

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 01, 2015 | ISSN (online): 2321-0613

Verification and Validation of Preliminarily Result of CFD of

Electrostatic Precipitator

Mr.Dharmendra Dekate1 Mr.K.M.Narkar2
1,2Department of Mechanical Engineering

1Thermax Ltd. Enviro Division, Pune, Maharashtra, India 2D.Y. Patil College of Engineering, Pune,

Maharashtra, India

Abstract— The Electrostatic Precipitator’s (ESP’s) are collected. Efficiency of ESP depends on the periodic
widely used for controlling particulate emissions from cleaning of collecting electrodes.

boilers and industrial process sources. The Electrostatic The Proper flow pattern of electrostatic precipitator

precipitation consists of three fundamental steps: (1) particle and effect of different boundary conditions on flow pattern.

charging, (2) particle collection, and (3) removal of the Plays major role and improves the ESP effectiveness and

collected dust. Electrostatic Precipitator is the device used performance and it should meet ICAC (Institute of Clean

for controlling air pollution. Process gases contain Air Companies) guidelines.

suspended dust particles. These dust particles are collected Perforated plates/ GD screens help to promote

on collecting electrodes. The effectiveness of Electrostatic uniform gas distribution inside the ESP, as good uniform

Precipitators is affected by various fact like gas flow gas distribution is important to ESP performance. Poor gas

condition, electric field generation and geometric distribution can diminish ESP performance by creating high

parameters. The industrial ESP are capable of handling large velocity zones which reduce treatment time of the gases.

gas volumes with a wide range of inlet temperatures, Perforated plates are very important in ESP. These are

pressures, dust volumes and gas conditions and exhibit having hole of different sizes arranged in specific manner.

complex interaction mechanism between electric field, fluid The entire plate is divided into no. of parts and as per cross

flow and particulate flows. Flow pattern of electrostatic section it has been perforated with specific openings.

precipitator and effect of different boundary conditions on Researchers have done various experimental

flow pattern has been studied by using Ansys fluent. So that studies to ensure the proper flow distribution in Electrostatic

the flow distribution should be improved and it should meet precipitator by selecting proper opening in GD screens from

ICAC (Institute of Clean Air Companies) guidelines. This that they derived various useful conclusions for further

paper presents the Ansys Fluent (CFD) concept for study and work. However this experimental approach has

modeling and analysis of Electro static precipitator. major drawbacks of higher time lines and cost involved in

Experimental testing is done for validation. The result of physical testing. To overcome this drawback there is need to

CFD concept and physical measurement are discussed. develop a quick and reliable process to properly distribute

Key words: Electrostatic Precipitator (ESP), CFD, GD the flow pattern and study of different boundary conditions

screen, Nozzle, Guide Vanes on flow pattern to maintain the Flow uniformity at the ESP

inlet and outlet at per ICAC Guidelines.

I. INTRODUCTION

The rapid increase in developing industrial processes is II. LITERATURE REVIEW

accompanied by the release of substantial quantities of The paper reviewed are referred and used directly or

pollutants. These pollutants often have detrimental effects, indirectly for completing this work The present project work

directly or indirectly, on human health, animals, natural is based on the studies carried out by various researchers on

resources, the biosphere and construction materials and Flow distribution in ESP and Detail study of ESP. These

metal structures. New industrial processes must therefore be papers are.

designed so that emissions are minimized. A Mizuno [1] have studied role of ESP in

The requirement that the development of new environmental protection. Performance of ESP deteriorates

processes must be balanced by the development of suitable by abnormal phenomena, including back corona for treating

technologies that eliminate or at least reduce the amount of high resistivity dust, abnormal re-entrainment for low

pollutants released to the atmosphere. Many approaches resistivity dust, and corona quenching for fine dusts.

have been devised to control pollutants in the atmosphere. Electrostatic precipitator (ESP) has been used widely in

Often times, different types of technologies can control a various industries such as utility boilers, cements kilns, etc.,

given source in order to achieve a given emission limit and also has been applied in cleaning of indoor air in

given by the emission control board. houses, offices, hospitals, and factories for food processing.

The most popular air pollution equipment is ESP can be operated with high collection efficiency and a

Electrostatic precipitator amongst all other available low pressure drop. The collection efficiency is usually

equipments like Bag filters, Cyclones, Mechanical dust >99%. Sub micrometer particles also can be collected

collector etc. to remove the dust from process gases. The effectively. The pressure drop is normally t1000 Pa. This is

effectiveness of Electrostatic Precipitator is depends of an important advantage of ESP, resulting in low operation

parameters like gas flow condition, electric field generation cost.

and geometric parameters. Feng Z. et.al. [2] have studied the performance of
The time to time cleaning is a major activity which several turbulence models, including the standard k-ε model,
low Reynolds number k-ε models, Large Eddy Simulation
is rather the cause of dust collection. The collecting

electrodes are cleaned periodically on which dust is (LES) models, and Detached Eddy Simulation (DES)

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Verification and Validation of Preliminarily Result of CFD of Electrostatic Precipitator
(IJSRD/Vol. 3/Issue 01/2015/111)

models, for simulating the pressure drop and transitional within the ESP collection regions are accurate to within 28
flows through pleated filters both with and without an and 33% of actual test data, respectively
electrostatic precipitator. The simulated results from the
models were compared with the experimental data from the Zhengwei Long et.al. [5] The initial design of the
literature and measurements. ESP was studied with the help of commercial CFD tool
“ANSYS Fluent” and after understanding its ineffectiveness,
Niles F. Nielsen [3] performed stimulation of ESPs the design was modified by the addition of a filter. The
including inlet nozzle with gas distributions screens, insertion of filter at the inlet helped delay the flow
precipitation sections with collector curtains and baffle separation at the inlet improved distribution of velocity in a
plates, hoppers with partition plates and outlet nozzle with more uniform pattern around all the electrode plates thus
gas distribution screen. Flow management by gas improving the efficiency of the ESP.
distribution screens are needed in inlet and outlet nozzle.
The study has focused on modeling of different ESPs. The III. DETAIL OF ESP
gas flow distribution as well as particle transport has been
investigated and discussed in terms of different designs. The ESP is so arranged that the nozzle is placed in line with
gas flow where GD-Screens are located. The dusty gas is
Robert G. Mudry et.al. [4] have examined the allowed to pass thru this GD-screen. ESP design conditions
accuracy of CFD models of electrostatic precipitators. Flow are well evaluated while sizing ESP, inlet/outlet duct routing
simulation results from ten distinct precipitator CFD models along with nozzle design & orientation may play a major
are compared with actual field measurements of velocity role in spoil in performance of ESP. Even correctly sized
patterns. In five of these cases, data from a physical scale ESP, through uneven gas and dust flow distribution will
modeling effort for the same ESP are available and are also affect ESP performance. That is where CFD study plays a
compared to the field measurements. The velocity major role in improving gas distribution in ESP.
distribution predicted by the CFD and physical models

IV. ANSYS FLUENT AND ITS DETAILS Fig. 1: ESP Model
plates, girders collecting plates, outer casing and nozzle are
given as Wall type boundary condition

The ESP model are made up by collecting plate, baffle A. Gas Distribution Screen Percentage as Per Standard:
plates, girders and perforated sheets, Nozzle, etc. with exact Fig. 2: GD Screen Details
dimensions. Guide vanes, gas distribution screens, wall
plates and other flow obstructions are modeled as baffle-
that are effectively zero thickness, two dimensional cells
.model are mesh with ratio 0.3 with 3-d hexahedral mesh.
The model is defined as Turbulent as K-epsilon and fluid
properties of flow are defined. Atmospheric air is considered
as working fluid, analysis is done for steady state condition
and single phase.

Boundary condition is defined as velocity at ESP
inlet and Pressure at ESP outlet. Perforated sheet is define as
Porous jump condition (minimum of 23% opening and a
maximum 60% opening is considered for CFD). The
properties of working fluid (air) are given as per the
operating conditions. All other components like baffle

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Verification and Validation of Preliminarily Result of CFD of Electrostatic Precipitator
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B. Mesh Model of ESP: measured at those points and then check for ICAC
Mesh generation is basically the discretization of the guidelines & RMS value.
computational domain. The 3D CFD model is discretized
into small fluid cells called mesh. Models are meshed 3D A. Velocity Readings:
hexahedral mesh to capture the fluid domain using ICEM
CFD. All the ESP’s should follow the ICAC guidelines for
uniform flow distribution for attaining maximum efficiency.
Fig. 3: Mesh Model in CFD The velocity pattern shall have a minimum of 85% of the
V. EXPERIMENTAL RESULT velocities not more than 1.15 times the average velocity and
Solution are iterate up to convergence. Test points are 99% of the velocities not more than 1.40 times the average
generate at the end of first field and flow pattern are checked velocity. Average velocity refers to the mean of all velocity
to meet ICAC guidelines. The number of points created is measurements made at a given face of the precipitator.
equal to the number of gas passages along the x-axis and at As per ICAC guidelines all this velocities should be
y-axis a maximum of 1 meter distance between each point measured near the inlet and outlet faces of the precipitator
along the height of collecting plates. Velocities are collection chamber, where as we measured at the end of first
field.

B. RMS Value:

The percent RMS is calculated by the following formula

√( )

----------Equation 1

Where
Vi = Velocity at selected Grid Point
Vavg = Average Velocity over Entire plane
i = Grid Point Center
The typical goal in industry is to achieve a Percent RMS of
less than 15% at the ESP inlet and outlet planes where as we
measured RMS value at the end of first field.

C. Velocity Measurement Plane Considered:

Fig. 4: Model with Velocity Measurement Plane

D. Velocity Contour at Plane 1:

Fig. 5: Velocity Contour Plane
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Verification and Validation of Preliminarily Result of CFD of Electrostatic Precipitator
(IJSRD/Vol. 3/Issue 01/2015/111)

Poin H G 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
ts T P

1 2.5 1.7 1.2 0.9 0.7 0.6 0.4 0.3 0.2 0.2 0.3 0.4 0.6 0.7 0.9 1.2 1.5 2.1
73 6 7 7 1 7 1 6 6 2 7 7 7 3 7 4

2 2.3 1.4 0.9 0.6 0.4 0.3 0.2 0.3 0.2 0.2 0.2 0.3 0.4 0.6 0.8 1.0 1.3 1.9
87 9 521914146965889

3 2.1 1.2 0.8 0.6 0.4 0.3 0.3 0.3 0.3 0.3 0.3 0.4 0.5 0.6 0.7 0.9 1.1 1.7
2 6 3 6 3 3 2 3 1 1 3 6 3 8 7

4 1.8 1.1 0.9 0.7 0.7 0.6 0.5 0.4 0.4 0.4 0.4 0.5 0.6 0.7 0.8 0.9 1.1 1.5
74 1 9 1 2 6 4 4 8 5 4 3 3 5 2 6

5 1.6 1.2 1.0 0.9 0.8 0.7 0.7 0.6 0.5 0.5 0.6 0.6 0.7 0.8 0.9 1.0 1.1 1.3
2 2 3 6 8 2 8 7 1 8 5 4 3 2 2 6

6 1.2 1.1 1.1 1.0 0.9 0.9 0.8 0.7 0.7 0.7 0.7 0.8 0.8 0.9 1.0 1.1 1.1 1.2
95 1 5 7 3 7 3 3 7 2 8 6 4 2 7 5

7 1.2 1.1 1.2 1.1 1.1 1.0 1.0 0.9 0.9 0.9 0.9 0.9 1.0 1.1 1.1 1.2 1.3 1.3
68 6 9 2 6 1 8 5 5 6 9 4 1 9 6

8 1.4 1.2 1.4 1.3 1.2 1.2 1.2 1.2 1.1 1.1 1.1 1.1 1.2 1.2 1.3 1.4 1.4 1.4
29 4 6 9 4 1 8 6 6 7 6 5 4 8 7

9 1.6 1.4 1.6 1.5 1.4 1.3 1.3 1.3 1.3 1.3 1.2 1.2 1.3 1.3 1.4 1.6 1.6 1.6
68 2 2 3 8 6 5 2 9 8 8 9 1 8 8

10 1.9 1.6 1.7 1.6 1.4 1.4 1.4 1.3 1.3 1.3 1.3 1.3 1.3 1.4 1.5 1.7 1.8 1.9
8 5 1 9 3 8 6 4 2 1 3 2 7 4 6 1

11 2.0 1.9 0.1 1.5 1.4 1.3 1.3 1.2 1.2 1.2 1.2 1.2 1.2 1.3 1.5 1.7 1.9 2.0
9 6 78 9 5 5 3 8 7 7 5 4 5 7 6 9 7 9

12 2.0 1.8 1.6 1.3 1.1 1.0 0.9 0.9 0.9 0.9 0.9 0.9 0.9 1.0 1.3 1.6 1.8 2.0
87 5 8 5 1 8 7 8 8 4 1 7 5 7 9 7

Table 1: Velocity Result at Plane 1 For 100% Load Condition

Average Velocity 1.02 Flow uniformity at the ESP inlet and outlet ICAC test planes
m/sec  85% of test points within ≤ 115% of measured

1.15 Times Vavg 1.17 average velocity (ICAC EP-7 criterion)
m/sec  99% of test points within ≤ 140% of measured

1.14 Times Vavg 1.42 average velocity (ICAC EP-7 criterion)
m/sec  ≤ 15% RMS velocity at the ESP inlet and outlet test

Total Velocity Reading 192 Nos. planes.

No of reading Within 1.15 145 % 76 % as per ICAC  Minimize system pressure loss
Times Vavg Criteria
Actu Mode
No of reading Within 1.14 179 % 93 % as per ICAC Uni al Actual l Model Tests
Times Vavg Criteria t Unit Temperat Perfor
Unit Temperat Flow med
Standard Deviation .49 Loa Flow ure Volu ure
d Volu me
RMS in % 48 % me

Table 2: Velocity readings & RMS value tabulated data

VI. VALIDATION RESULT 100 928,8 140oC 2,668 20oC / Velocity
% 00 Am3/ 70oF ,
In order to ensure that the design of the ESP fulfills the Loa
performance requirements, the physical model is d Am3/ hr Pressure
constructed, and tested a physical model as below. ,

Table 3: Design Data

The flow models are used to design flow control

devices to meet the following criteria:

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Verification and Validation of Preliminarily Result of CFD of Electrostatic Precipitator
(IJSRD/Vol. 3/Issue 01/2015/111)

Fig. 6: Physical model of ESP

A. Model Flow Condition: unit is evaluated, the model flow rate is derived from one-
half of the full unit flow rate. All testing are performed on
The model flow rates are correctly scaled from the unit 100% Load condition the velocity are measured at air heater
design flow rate to match the velocity head (dynamic outlet TL-1, at Inlet TL-2, at ESP outlet TL-3.
pressure) of the full-scale unit. Since only one-half of the

Fig. 7: Typical View of ESP Model with test Points

Following are the result for average velocity, RMS Result Show that at 100% load the final model

velocity, and total pressure design achieves the ICAC requirements at both the ESP inlet

Location Target Goal Model Result and outlet planes, and it achieves the RMS target at the ESP
(100% Load) inlet plane.

ICAC Inlet ≥85% of test points 89.8% VII. CONCLUSION
≤115% of average

ICAC Inlet velocity 100% 1) Results are presented for the physical model ESP.
ICAC Inlet ≥ 99% of test points 12.7% Tests performed included velocity and pressure
ICAC Outlet ≤140% of average 88.9% measurements at 100 % load conditions and design
achieves the result as per ICAC
velocity
Velocity RMS ≤15% 2) The pressure loss across the ESP from the
≥85% of test points ≤ beginning of the inlet nozzle to the outlet of the
outlet nozzle (ESP flange-to-flange) is within the
115% of average specified target at 100% Load.

velocity
≥99% of test points

ICAC Outlet ≤140% of average 100% REFERENCES

velocity [1] A Mizuno, “Electrostatic Precipitation”, IEEE
Transactions on Dielectrics and Electrical
ICAC Outlet Velocity RMS ≤15% 17.9% Insulation Vol. 7 No. 5, October 2000.

Total ≤25 mmH2O ESP [2] Feng Z., Long Z., and Chen Q, “Assessment of
various CFD models for predicting airflow and
pressure Flange-to-flange at 24.0 mmH2O

drop 100% Load

Table 4: Physical Model test result

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Verification and Validation of Preliminarily Result of CFD of Electrostatic Precipitator
(IJSRD/Vol. 3/Issue 01/2015/111)

pressure drop through pleated filter system,”
Building and Environment, 75, (2014)132-141.
[3] Niles F. Nielsen, Leif Lind, “CFD simulation of
gas flow and particle movement in ESPs”, Institute
of clean air companies, electrostatic precipitator
gas flow model studies, publication EP-7 January
1997.
[4] Robert G. Mudry, Brian J. Dumont,
“Computational fluid dynamic modeling of
electrostatic precipitators”, Electric Power 2003
Conference 05 March 2003.
[5] Zhengwei Long, Qiang Yao, “Electrostatic
Precipitators (ESP) analysis using CFD”, Journal of
Aerosol Science 41 (2010), 702–718.

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