BOILER FEED WATER TREATMENT USING ELECTRODIALYSIS
Ankit Patel
B.E., Gujarat University, India, 2007
Dhaval Savla
B.E., Mumbai University, India, 2006
PROJECT
Submitted in partial satisfaction of
the requirements for the degree of
MASTER OF SCIENCE
in
ELECTRICAL AND ELECTRONIC ENGINEERING
at
CALIFORNIA STATE UNIVERSITY, SACRAMENTO
SUMMER
2010
BOILER FEED WATER TREATMENT USING ELECTRODIALYSIS
A Project
by
Ankit Patel
Dhaval Savla
Approved by:
__________________________________________________, Committee Chair
John Balachandra, Ph.D.
___________________________________________________, Second Reader
Fethi Belkhouche, Ph.D.
________________________________
Date
ii
Student: Ankit Patel
Dhaval Savla
I certify that these students have met the requirements for format contained in the
university format manual and that this project is suitable for shelving in the library and
credits to be awarded for the Project.
_________________________, Department Chair
Suresh Vadhva, Ph.D.
Department of Electrical and Electronic Engineering
iii
________________
Date
Abstract
of
BOILER FEED WATER TREATMENT USING ELECTRODIALYSIS
by
Ankit Patel
Dhaval Savla
Water treatment is the most important part of any power plant. Water from natural
reservoir is fetched into plant and treated to reduce impurity level, before it is used to
generate saturated steam. The saturated steam rotates turbine at high speed so that desired
amount of electrical energy is generated. In this whole process water purification is very
important. Proper water treatment can increase efficiency, reduce fuel consumption,
increase life time of control system vessels.
There are various water treatment methods and they are mainly divided into two
categories

Chemical methods

Non-chemical methods (e.g. UV radiation method and Electrodialysis).
iv
Chemical water purification is concerned with a lot of different methods. These methods
require special attention because of the use to harmful chemicals. Special equipments are
required to handle them and this will increase the cost of power generated per unit.
Nowadays, carbon foot print is a big issue for any industry. More use of chemical
increase carbon footprint.
So, far Electrodialysis is used to regenerate salts and chemical solutions with specific
concentration. It is a modern technique which uses DC power and is capable to purify
water up to drinking level. Power requirement for this system is very low compared to
other chemical treatment systems. It uses almost no chemicals, so it is environmental safe
and reduces the carbon footprint of the power plant. Furthermore, capital costs, operating
costs, and maintenance costs are lower than chemical treatment systems. These benefits
are very realistic for any industry needing purified water supply. So we are going to focus
on Electrodialysis to purify boiler feed water in power plant.
_________________________________________________, Committee Chair
John C. Balachandra, Ph.D
________________
Date
v
TABLE OF CONTENTS
Page
List of Figures………………………………………………………….……………
ix
List of Tables…………………………………………………………………..........
xi
List of Graphs ……………………………………………………………………………..
xii
Chapter
1.
2.
SOURCES OF WATER AND IMPURITIES………………………………...
1
1.1 Effects of impurities ...………………………………………………....
3
TYPE OF WATER PURIFICATION.....…………………………………….
11
2.1 Filtration……………………………………………………..…………
11
2.2 Sand Filtration .............................................................................…......
11
2.3 Cross Flow Filtration……..………………………………...……….....
11
2.4 Micro Filtration…..…………………………………………………….
12
2.5 Ultra Filtration…………………….………………………….…...........
12
2.6 Nano Filtration…………………………………………………………
13
2.7 Reverse Osmosis……………………………………………………….
13
2.8 UV Radiation …………………………………………………………
13
2.9 Distillation……………………………………………………….…….
14
2.10 pH Adjustment……………………………………………………….
14
2.11 Electrodialysis ………………………………………………………..
15
2.12 Sand Filtration………………………………………………………
17
2.13 Slow Sand Filter………………………………………………………
17
vi
2.14 Rapid Sand Filter...……………………………………………………
19
2.15 Micro Filtration…..…………………………………………………...
22
2.16 Membrane Filters for Water Purification ……….……………………
23
2.17 Classification of Membrane…………………………………………..
24
2.18 Classification Based on Separation Mechanism ……..………………
25
2.19 Porous/ Non Porous Membranes….…………………………………
25
2.20 Ion Exchange Membrane…………….…..…………………………… 26
3.
2.21 Classification Based on Morphology……..…………………….......
26
2.22 Composite Membranes………………………………………………
26
2.23 Classification Based on Geometry……..……………………………..
27
2.24 Membrane Cleaning ……….………….………………………….…..
28
2.25 Forward Flushing……………..………………………………………
28
2.26 Backward Flushing ……………...…………………………………...
29
2.27 Air Flush…………………………...…………………………………
30
2.28 Chemical Cleaning …………………………………………………..
31
2.29 General Membrane Equation ………………………………………...
34
2.30 pH adjustment ………..………………………………………………
35
2.31 Flocculation ………………………………………………………….
35
2.32 Active Carbon Filtration ……………………………………………
36
ELECTRODIALYSIS.……………………………………………………..
37
3.1 Electrodialysis Principle..…………………………………………….
38
3.2 Elements of Electrodialysis .………………………………..................
41
vii
3.3 Power Consumption…………………………………………………..
43
3.4 Advantages of Electrodialysis …………………………………...........
47
3.5 Issues with Electrodialysis ……………………………………………
48
3.6 Electrodialysis Reversal (EDR).………………………………………
50
3.7 Advantages of EDR...…………………………….……………………
52
3.8 Cost Consideration.……………………………………………………
53
4.
MATLAB CODE FOR SIMULATION……………..………………………
57
5.
CONCLUSION ……………………………………………..……………….
63
6.
Bibliography …………………………………………………………..
64
viii
LIST OF FIGURES
Page
1.
Figure 1 Corrosion Due to Presence of Oxygen………………………………. 4
2.
Figure 2 Reduced Flow Channel Due to Deposits…………………………….. 4
3.
Figure 3 Destruction After Boiler Explosion………………………………….. 5
4.
Figure 4 Construction of Slow Sand Filter……………………………………. 18
5.
Figure 5 Basic Block Diagram of Rapid Sand Filter………………………….. 19
6.
Figure 6 Actual Experimental Setup (a) General View………………………. 20
7.
Figure 7 Actual Experimental Setup Front View……………………………... 21
8.
Figure 8 Cross Flow Microfiltration Technique………………………………. 22
9.
Figure 9 Schematic Representation of Isotropic Porous Membranes, (a)
25
Macropores>50nm; (b) Mesopores >50nm ; (c) Micropores <2nm……………
10. Figure 10 Schematic Drawing of Asymmetric Membrane …………………… 27
11. Figure 11 Schematic Drawing of Composite Membrane …………………….. 27
12. Figure 12 Forward Flush Cleaning Technique………………………………… 28
13. Figure 13 Backward Flush Cleaning Technique………………………………. 29
14. Figure 14 Air Flush Cleaning Technique……………………………………… 30
15. Figure 15 Membrane Cleaning Effect of Short Term Experiment ……………. 32
16. Figure 16 Membrane Cleaning Effect of Long Term Experiment…………….. 33
17. Figure 17 Typical Electrodialysis Cell ……………………………………….. 38
18. Figure 18 Ion Separation During Electrodialysis. (CM - Cation Exchange
39
Membrane, D - Diluate Chamber, e1, e2 - Electrode Chambers, AM - Anion
Exchange Membrane, K - Concentrate Chamber ……………………………...
ix
19. Figure 19 Close Look Into Electrodialysis Process………………………......... 40
20. Figure 20 Electro dialyzer made by Zhejiang Feiying Environmental
42
Technology Engineering Co. LTD …………………………………………….
21. Figure 21 Change In Polarity And Product Outlate in EDR ………………….. 50
22. Figure 22 Self Cleaning During Electrodialysis Reversal…………………….. 51
x
LIST OF TABLES
Page
1.
Table 1 Water Impurities, Issues and Solution ……………………………….
6
2.
Table 2 Classification of Membrane Separation Processes for Water
Purification……………………………………………………………………
16
3.
Table 3 Volume of Water Filtered In a 24 Hour Period by Filters of Varying
Size Surface Area……...………………………………………………………
18
4.
Table 4 Working Condition For Electrodialyzer Made by Zhejiang Feiying
Environmental Technology Engineering Co., LTD…………………………...
42
5.
Table 5 Allowed Impurities In Boiler Water…………………………………..
46
6.
Table 6 Comparison Between RO & ED by Boris Pilate……………………...
47
7.
Table 7 Water Content Difference Before and After Electrodialysis
54
Treatment…………………………………………………………………........
8.
Table 8 Costing for Electrodialysis Plant Established by Howard R Green
Company………………………………………………………………………
xi
55
LIST OF GRAPHS
1.
Graph 1 Experimental Result to Decide Limit for Dissolved Solids in Water...
xii
2