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DEPARTMENT OF MECHANICAL & MANUFACTURING ENGINEERING
FACULTY OF ENGINEERING
UNIVERSITY OF RUHUNA
INDUSTRIAL TRAINING REPORT SUBMITTED IN PARTIAL FULFILMENT OF THE DEGREE OF BACHELOR OF SCIENCE IN ENGINEERING
29 th April 2016
CEYLON ELECTRICITY BOARD
(From 04th January 2016 To 24 th April 2016)
WICKRAMARATHNE G.T (EG/2012/2111)
Preface
I am a Mechanical & Manufacturing engineering undergraduate at University of Ruhuna.
I trained under Ceylon Electricity Board ( CEB) from 04th January 2016 to 24
th March
2016 under the second industrial training session of my degree program. Electricity
generation and distribution are done by Ceylon Electricity Board.
My working experience and industrial exposure in the above company during the 12
week time period is mentioned in this report. Chapter 1 is dedicated to the
“Introduction of the Ceylon Electricity Board”. And Chapter 2 is described for the
training experience and industrial exposure of myself at there. Chapter 3 has reserved
to discuss the “Management” where it is mentioned about the managements knowledge
that I could gain at CEB. Finally the chapter 4 is separated for the “Summary and
Conclusion”.
I have tried my best to present what I could learn at CEB with graphical explanations.
Acknowledgment
As an engineering student I was lucky to have this valuable and rare chance to have my
second industrial training experience at Ceylon Electricity Board where I was able to
gain great work place experience and technical knowledge.
Most especially I’m thankful to Dr. Sumith Baduge, Department head of the
Mechanical & Manufacturing Department.
And also I take this opportunity to express my profound gratitude and deep regard Dr.
J.M.R.S Appuhami who coordinated and guided us in selecting training places and
taking all the arrangements to make it more successful. My sincere gratitude goes to
Engineering Education Center of Ruhuna Engineering Faculty for giving me this
opportunity and also to NAITA for granting us for the training.
I convey my special thanks to Head of the Training Center of CEB and the staff of Train-
ing Center who arranged a better training sessions for us, for supporting and guiding us
during the training period. I would also like to thank all the staff at CEB for their
great support and for the knowledge and experience they shared with us.
I thank all the Engineers and other staff of CEB at the who spent their valuable time to
explain and to teach us about different fields.
My heartiest gratitude goes to my parents, my brothers and friends who helped me a lot
to make my industrial training a success .The blessing, help and guidance given by them
time to time shall carry me a long way in the journey of life on which I am about to
embark.
Thank you.
Wickramarathne G.T.-EG/2012/2111
Faculty of Engineering,
University of Ruhuna,
Galle.
1
Contents
1 INTRODUCTION ...................................................................................................... 6
1.1 About the Training Session .................................................................................. 6
1.2 Ceylon Electricity Board (C.E.B.) ....................................................................... 7
1.2.1 Organizational Structure of the CEB ............................................................ 9
1.3 Electricity Generation Sources ........................................................................... 10
1.4 CEB Grid Network............................................................................................. 11
2 TECHNICAL DETAILS .......................................................................................... 13
2.1 Hydroelectric Power .......................................................................................... 13
2.2 Main Components of Hydroelectric Power Plant .............................................. 15
2.2.1 Dam ............................................................................................................. 15
2.2.2 Water Reservoir .......................................................................................... 16
2.2.3 Intake or Control Gates ............................................................................... 16
2.2.4 Penstock ...................................................................................................... 17
2.2.5 Surge Tank .................................................................................................. 19
Power Station ............................................................................................................ 20
2.2.6 Main inlet valve (MIV) ............................................................................... 20
2.2.7 Turbine ........................................................................................................ 21
2.2.8 Generator .................................................................................................... 22
2.2.9 400V Switch Board ..................................................................................... 26
2.2.10 Switch Yard ................................................................................................ 27
2.2.11 Generator Transformer ............................................................................... 27
2.2.12 HVAC system ............................................................................................. 28
2.3 Maintenance Works ........................................................................................... 30
2.3.1 Annual maintenances (28/12/2015- 11/01/2016) – Kukuleganga Power
Station ................................................................................................................... 30
2.3.2 Breakdown Maintenance at Kukuleganga Power Station .......................... 37
2.3.3 Maintenance works at Samanalawewa ....................................................... 38
2.3.4 First Aid Camp at Samanalawewa .............................................................. 39
2.4 Thermal Power: How It Works .......................................................................... 40
2.4.1 Important of Coal Power Plant to Sri Lanka .............................................. 41
2.4.2 Working of a Coal Fired Plants .................................................................. 42
2
2.4.3 Introduction to LakVijaya Power Station ................................................... 44
2.5 Main Sections of LakVijaya Power Station ....................................................... 44
2.5.1 Fuel Handling Section ................................................................................ 44
2.5.2 Boiler and Boiler Auxiliaries Section ......................................................... 53
2.5.3 Turbine and Turbine Auxiliaries ................................................................ 67
2.5.4 Generator .................................................................................................... 73
2.5.5 Transformer ................................................................................................ 73
2.5.6 Balance of Plant (BOP) .............................................................................. 74
2.5.7 Maintenance Works .................................................................................... 81
3 MANAGEMENT ..................................................................................................... 83
3.1 Demand Side Management (DSM) .................................................................... 83
3.2 Financial Management ....................................................................................... 84
3.3 Human Resource Management (HRM) ............................................................. 86
3.4 Quality Control Program .................................................................................... 87
3.5 Health and Safety Management ......................................................................... 88
3.6 Energy and Waste Management ........................................................................ 90
4 SUMMARY AND CONCLUSION ......................................................................... 93
4.1 Summary ............................................................................................................ 93
4.2 Conclusion ......................................................................................................... 94
5 References ................................................................................................................. 95
3
List of Figures
Figure 1-1 Crest of the Ceylon Electricity Board ............................................................... 7
Figure 1-2 Organizational structure of the CEB ................................................................ 9
Figure 1-3 Electricity generation in Sri Lanka by source ................................................. 10
Figure 2-1 Hydro power works ......................................................................................... 13
Figure 2-2 Samanalawewa location .................................................................................. 14
Figure 2-3 Regulation pond gate of the Kukule Ganga Hydroelectric Power Plant ........ 17
Figure 2-4 Schematic diagram of Samanalawewa Power Station .................................... 18
Figure 2-5 Schematic diagram of Kukuleganga Power Station ........................................ 19
Figure 2-6 MIV with by-pass system ............................................................................... 20
Figure 2-7 MIV with service seal ..................................................................................... 20
Figure 2-8 Turbine of Samanalawewa .............................................................................. 21
Figure 2-10 Bearing arrangement of generator shaft ........................................................ 22
Figure 2-12 Chilled water cooling system ........................................................................ 28
Figure 2-13 Air handling unit arrangement ...................................................................... 29
Figure 2-14 Repairing and maintenance of spiral casing process .................................... 30
Figure 2-15 Paints used for repainting the spiral casing................................................... 31
Figure 2-16 Pressure testing setup .................................................................................... 31
Figure 2-17 Repairing of gate valve ................................................................................. 32
Figure 2-18 Portable oil filter unit .................................................................................... 33
Figure 2-19 Clearance measuring test .............................................................................. 34
Figure 2-20 Replacing the ‘O’ rings of the oil cooler ...................................................... 34
Figure 2-21 Clearance measuring of runner guide veins .................................................. 35
Figure 2-22 Crack detector dye penetrant ........................................................................ 36
Figure 2-23 Closing the manhole of spiral casing ............................................................ 36
Figure 2-24 Tightening a coupling .................................................................................. 37
Figure 2-25 Some equipment in machine shop ................................................................ 38
Figure 2-26 First aid tips................................................................................................... 39
Figure 2-27 Artifical breathing practical section .............................................................. 39
Figure 2-28 How a steam power plant works ................................................................... 40
4
Figure 2-29 From coal to electricity ................................................................................. 43
Figure 2-30 Coal unloading system .................................................................................. 46
Figure 2-31 Jetty ............................................................................................................... 46
Figure 2-32 Self propeller barge ....................................................................................... 47
Figure 2-33 Coal unloading process ................................................................................. 47
Figure 2-34 Parts of bridge ship unloader ........................................................................ 48
Figure 2-35 Coal yard ....................................................................................................... 49
Figure 2-36 Bucket wheel stacker-reclaimer .................................................................... 49
Figure 2-37 Coal bunker ................................................................................................... 50
Figure 2-38 Coal feeder .................................................................................................... 51
Figure 2-39 Coal pulverizer .............................................................................................. 52
Figure 2-40 Steam cycle ................................................................................................... 55
Figure 2-41 Steam drum ................................................................................................... 56
Figure 2-42 Main component of the re- heater system ..................................................... 57
Figure 2-43 Boiler main auxiliary systems and steam path arrangement ......................... 57
Figure 2-44 Burner and wind box arrangement inside the furnace .................................. 58
Figure 2-45 Plane view of the fire arrangement and imaginary fire circle ....................... 59
Figure 2-46 Primary air fan .............................................................................................. 60
Figure 2-47 Seal air fan .................................................................................................... 61
Figure 2-48 FD and ID fans .............................................................................................. 62
Figure 2-49 Working principle of ESP ............................................................................. 63
Figure 2-50 Fluegas desulfurization unit ........................................................................ 64
Figure 2-51 Working principle of aeration basin ............................................................. 66
Figure 2-52 Aeration of sea water to remove Sulphur ..................................................... 66
Figure 2-53 LP, IP and HP turbines.................................................................................. 67
Figure 2-54 Bearing arrangement of the rotor .................................................................. 68
Figure 2-55 Coagulation tanks .......................................................................................... 75
Figure 2-56 Ultra filter ...................................................................................................... 75
Figure 2-57 RO device ...................................................................................................... 76
Figure 2-58 Energy recovery unit operation principle ..................................................... 77
Figure 2-59 Make-up water treatment process flow chart ................................................ 77
Figure 2-60 Hydrogen generating system ......................................................................... 79
Figure 2-61 Hydrogen generating storage system ............................................................ 79
5
Figure 2-62 Control room ................................................................................................. 80
Figure 2-63 Repair the pulley system of a gantry crane ................................................... 82
Figure 3-1 Summary statics 2013 ..................................................................................... 85
Figure 3-2 How to avoid accidents ................................................................................... 88
Figure 3-3 Different types of fire extinguishers in power plant ....................................... 89
Figure 3-4 Eye washer ...................................................................................................... 90
Figure 3-5 Waste disposal coding system ........................................................................ 91
Figure 3-6 ESP unit .......................................................................................................... 92
6
CHAPTER ONE
1 INTRODUCTION
1.1 About the Training Session
For the second session of industrial training I got the opportunity to train in Ceylon
Electricity Board. The training session was planned to both hydro and thermal power
generation .The training session was expanded for 12 weeks from 04/01/2016 to
24/03/2016.
Before starting the training we were asked to report to Office of Deputy General Manager
(Training), Piliyandala and there we got our training schedule. The provided training
schedule is shown in table 1.1.
Table 1.1. Training Schedule
Branch/Workplace From To
Samanala Hydro Complex 04/01/2016 12/02/2016
LakVijaya Coal Power Station 15/02/2016 24/03/2016
In the 6 week period of Samanala Hydro Complex, first we had 3 weeks training in Kukule
Ganga Hydro power Station and then 3 weeks in Samanalawewa Hydro Power Station.
7
Figure 3-1 Crest of the Ceylon Electricity Board
1.2 Ceylon Electricity Board (C.E.B.)
Vision
“Enrich Life Through Power”
Mission
To develop and maintain an efficient, coordinated and economical system of electricitysupply to the whole of Sri Lanka, while adhering to our core values
* Quality
* Service to the nation
* Efficiency and effectiveness
* Commitment
* Safety
* Professionalism
* Sustainability
8
CEB is empowered to
o Generate electrical energy
o Transmit electricity
o Distribute it to reach all categories of consumers and
o Collect the revenue.
CEB is also empowered to
o Acquire assets, including human resources following the approved procedures.
It is the duty of the CEB to make the optimal use of the resources through the
application of pragmatic and time-tested managerial methods.
Statutory Obligation
It shall be the duty of the Board, with effect from the date of the transfer to the Boardof Government Electrical Undertakings under Section 18, to develop & maintain anefficient, coordinated & economical system of electricity supply for the whole of SriLanka.
Section 11, Ceylon Electricity Board Act No.17 of 1969
9
1.2.1 Organizational Structure of the CEB
Figure 3-2 Organizational structure of the CEB
10
1.3 Electricity Generation Sources
C.E.B. generates typically 74% of the total electricity demand of Sri Lanka. C.E.B.
purchase electricity from P.P.P. (Private Power Purchases) to fulfil the remaining
electricity demand. Electricity generation in Sri Lanka can be categorized into 4 major
categories. They are
Hydro
Thermal-oil
Thermal-coal
NCRE (Non-Conventional Renewable Energy)
Contribution of each category depends on several facts like weather (rain), fuel prize,
condition of plants etc. For an example consider following charts taken from the
‘Statistical Digest of the C.E.B. 2013’.
Figure 3-3 Electricity generation in Sri Lanka by source
By considering above charts it can be seen that rainfall in 2012 is less than 2013. That’s
why Hydro electricity generation in 2012 is less than 2013. As well in 2013 only the phase
1 of LakVijaya coal power plant was operational. That’s why contribution from thermal-
coal power plants is less than the contribution from thermal-oil power plants.
11
1.4 CEB Grid Network
Table 1.2 - Existing and Committed Power Plants
Plant Name Units x
Capacity Capacity
(MW) Expected
Annual
Avg.
Energy
(GWh)
Year of
Commissioning
Canyon 2 x 30 60 160 1983 - Unit 1
1989 - Unit 2
Wimalasurendra 2 x 25 50 112 1965
Old Laxapana
3x 9.5+
2x12.5
53.5 286 1950
1958
New Laxapana 2 x 58 116 552 Unit 1 1974
Unit 2 1974
Polpitiya 2 x 37.5 75 453 1969
Laxapana Total 354.5 1563
Upper Kotmale 2 x 75 150 409 Unit 1 - 2012
Unit 2 - 2012
Victoria 3 x 70 210 865 Unit 1 - 1985
Unit 2 - 1984
Unit 3 - 1986
Kotmale 3 x 67 201 498 Unit 1 - 1985
Unit 2&3 –‘88
Randenigala 2 x 61 122 454 1986
Ukuwela 2 x 20 40 154 Unit 1&2 – ‘76
Bowatenna 1 x 40 40 48 1981
Rantambe 2 x 24.5 49 239 1990
Mahaweli Total 812 2667
Samanalawewa 2 x 60 120 344 1992
Kukule 2 x 35 70 300 2003
Small hydro 20.45
Samanala Total 210.45 644
Existing Total 1376.95** 4874
Committed
Broadlands 2x17.5 35 126 2017
Moragolla 2x15.5 31 97.6
2020
12
Note: * According to feasibility studies. ** 3MW wind project at Hambantota not included
Multi-Purpose Projects
Uma Oya 2x60 120 231 2017
Gin Ganga 2x10 20 66 -
Thalpitigala 2x7.5 15 52.4 -
Moragahakanda (2x5) +
7.5 +
7.5
25 114.5 Unit 1-2017
Unit 2-2020
Unit 3-2022
Total Hydro 246 687.5*
Puttalam Coal Power
Plant Puttalam CPP
3 x 300
3 x 275
-
2011 & 2014
Puttalam Coal Total 900 825 -
Kelanitissa Power Station
Gas turbine (Old) 4 x 20 4 x 16.3 417 Dec 81, Mar 82,
Apr 82,
Gas turbine (New) 1 x 115 1 x 113 707 Aug 97
Combined Cycle (JBIC) 1 x 165 1 x 161 1290 Aug 2002
Kelanitissa Total 360 339.2 2414
Sapugaskanda Power
Station
Diesel 4 x 20 4 x 17.4 472 May 84, May 84,
Sep 84, Oct 84
Diesel (Ext.) 8 x 10 8 x 8.7 504 4 Units Sept 97
4 Units Oct 99
Sapugaskanda
Total
160 139.2 976
Other Thermal Power
Plants
UthuruJanani 3 x
8.9
3 x 8.67 Jan 2013
Existing Total
Thermal
1446.7 1329.4 3390
13
CHAPTER TWO
2 TECHNICAL DETAILS
2.1 Hydroelectric Power
Hydropower is using water to power machinery or make electricity. When flowing water
is captured and turned into electricity, it is called hydroelectric power or hydropower. In
this case a power source-water is used to turn a propeller like piece called a turbine, which
then turns a metal shaft in an electric generator, which is the motor that produces
electricity.
Figure 3-4 How hydro power works
The theory is to build a dam on a large river that has a large drop in elevation. The dam
stores lots of water behind it in the reservoir. Near the bottom of the dam wall there is the
water intake. Gravity causes it to fall through the penstock inside the dam. At the end of
the penstock there is a turbine propeller, which is turned by the moving water. The shaft
from the turbine goes up into the generator, which produces the power. Power lines are
connected to the generator that carry electricity to our homes. The water continues past the
propeller through the tailrace into the river past the dam.
14
There are three types of hydropower facilities as
Impoundment
The most common type of hydroelectric power plant is an impoundment facility. An
impoundment facility, typically a large hydropower system, uses a dam to store river
water in a reservoir. Water released from the reservoir flows through a turbine, spinning
it, which in turn activates a generator to produce electricity.
Therefore Samanalawewa power station belongs into this category where its dam is located
in the Udawalawe basin. It was built at the confluence of the Walawe River and the Belihul
Oya, a location 400 m above mean sea level.
Figure 3-5 Samanalawewa location
Diversion
A diversion, sometimes called run-of-river, facility channels a portion of a river through
a canal or penstock. It may not require the use of a huge dam. So there won’t be a huge
reservoir to only a small pond is built up. Kukuleganga hydro power station falls under
this category where its catchment area is 312 km2, full spill level is 206.00 msl and
minimum operating level is 204 msl and effective storage is 1.67 million m.
15
Pumped storage.
Another type of hydropower called pumped storage works like a battery, storing the
electricity generated by other power sources like solar, wind, and nuclear for later use. It
stores energy by pumping water uphill to a reservoir at higher elevation from a second
reservoir at a lower elevation. When the demand for electricity is low, a pumped storage
facility stores energy by pumping water from a lower reservoir to an upper reservoir.
During periods of high electrical demand, the water is released back to the lower reservoir
and turns a turbine, generating electricity. [1]
2.2 Main Components of Hydroelectric Power Plant
2.2.1 Dam
The dam is the most important component of hydroelectric power plant. The dam is built
on a large river that has abundant quantity of water throughout the year. It should be built
at a location where the height of the river is sufficient to get the maximum possible
potential energy from water. E.g.:
Samanalawewa dam
Length : 460m
Height : 100m
Type : Rock fill clay core type
Spillway gates : 3 (max 1200 m3/s x 3)
Irrigation gate : 10 m3/s (max)
Low Level Outlet : 75 m3/s (max)
Kukuleganga dam-
Length : 110m (at Meepagama)
Height : 16m
Type : Gravity type
Low Level Outlet : 2.5 m3/s (max)
The water so collected in the pond is run through a settling tank or a sand trap, to stop
some of the sediment particles which could damage the turbines from entering into the
waterway.
16
2.2.2 Water Reservoir
The water reservoir is the place behind the dam where water is stored. E.g.:
Samanalawewa
Catchment area : 341 𝐾𝑚2
Main feeds : Walawe ganga and Belihul oya
Capacity : 278 MCM
Usable capacity : 218 MCM
Max water level : 455 MSL
Minimum water level : 424 MSL(for power generation)
Leak : 1.8𝑚3/s
Kukuleganga
Catchment area : 312 𝐾𝑚2
Main feeds : Kukule ganga
Capacity : 1.67 MCM
Max water level : 206 MSL
Minimum water level : 204 MSL(for power generation)
2.2.3 Intake or Control Gates
These are the gates built on the inside of the dam and water enters the power generation
unit through these gates. When the control gates are opened the water flows due to gravity
through the penstock and towards the turbines.
Samanalawewa
To get a vortex free or lesser water supply to tunnels intake is built with Bell mouth shape.
To collect logs and trash which flow towards the intake there is a trash rack as well. The
intake to the tunnel is some 5.5km up steam of the dam on the right bank of the walawe
river limb of the reservoir the tunnel intake consist of a screened bell mouth and anti-
vortex structure, a short section of tunnel leading to emergency and control and monitoring
equipment. The bell mouth structure is constructed in front of the tunnel portal with an
invert level of 416.75msl.the trash screens are inclined at an angle of 45 degrees.
17
An anti-vortex structure is constructed above bell mouth in take to prevent the formation
of air entering vortices as the level approaches the lowest reservoir level of 424.0 msl. The
bell mouth structure terminates at the 6m long transition to the 4.5m internal diameter
concrete lined intake tunnel which extends horizontally for some 40m to the bottom of the
gate shaft at invert level 417.0 msl. The gate shaft is divided into upstream chambers. A
control gate operates in the downstream chamber. Bothe the control and emergency gates
are equipped with 300mm diameter by-pass valves for controlled tunnel filling and
pressure equalizing.
Figure 3-6 Regulation pond gate of the Kukule Ganga Hydroelectric Power Plant
2.2.4 Penstock
The penstock is the long pipe or the shaft that carries the water flowing from the reservoir
towards the power generation unit, comprised of the turbines and generator. In
Samanalawewa first water carries out by power tunnel till to portal valve house. And then
use the penstock to bring water to power house. We can’t see such portal valve house at
Kukuleganga.
18
Samanalawewa
- Power tunnel
Length : 5.35 km
Slope : 1:100
Internal diameter : 4.5 m
- Portal valve house
Type of valve : Butterfly
Hydraulically operated
By pass valve included
- Penstock
Length : 670 m
Diameter : 3.85m at inlet & 2.85m at outlet
Figure 3-7 Schematic Diagram of Samanalawewa Power Station
19
Kukuleganga
- Headrace tunnel
Length : 5.7 km
Internal diameter : 6.4 m
Figure 3-8 Schematic Diagram of Kukuleganga Power Station
2.2.5 Surge Tank
This is situated after the concrete made tunnel and is made to bear the sudden pressure
impact when the main inlet valve (MIV) is closed at the power house. Surge chamber is
located at just upstream of portal valve house. The top of 18m diameter surge chamber is
at level 477 msl and 12m above ground level with the floor at 391.0msl. and 6m diameter
shaft leads vertically from and connects to the 4.5m diameter tunnel.
20
Power Station
2.2.6 Main inlet valve (MIV)
Samanalawewa
- Spherical ball valve
- By pass valve included
- Nominal diameter 1.5 m
- Design pressure 44 bar
Figure 3-9 MIV with by-pass system
Kukuleganga
- Spherical ball valve hydraulically operated
- No by pass. MIV is open after pressure balanced by opening service seal.
- Nominal diameter 1.7 m
- Design pressure 24 bar
Figure 3-10 MIV with service seal
By- pass system
Hydraulic
Actuator
21
2.2.7 Turbine
When water falls on the blades of the turbine the kinetic and potential energy of water is
converted into the rotational motion of the blades of the turbine. The rotating blades causes
the shaft of the turbine to also rotate. There are many types of turbines such as Kaplan
turbine, Francis turbine, Pelton wheels etc. The type of turbine used in the hydroelectric
power plant depends on the height of the reservoir, quantity of water and the total power
generation capacity.
Samanalawewa
- Vertical shaft Francis type
- Normal speed 500rpm
- counter clockwise rotation
- Turbine setting level 109 MSL
- 20 wicket gates
- Wicket gates operated by hydraulic servo motor
Figure 3-11 Turbine of Samanalawewa
22
Kukuleganga
- Vertical shaft Francis type
- Normal speed 500rpm- clockwise rotation view from above
- Turbine effective head 183.17 m
- Turbine setting level 206 MSL
- 20 wicket gates -Wicket gates operated by hydraulic servo motor
Bearing arrangement of generator shaft
Both power plants have same bearing arrangement as follows
Figure 3-12 Bearing arrangement of generator shaft
2.2.8 Generator
It is in the generator where the electricity is produced. The shaft of the water turbine rotates
in the generator, which produces alternating current in the coils of the generator. It is the
rotation of the shaft inside the generator that produces magnetic field which is converted
into electricity by electromagnetic field induction. Hence the rotation of the shaft of the
turbine is crucial for the production of electricity and this is achieved by the kinetic and
potential energy of water. Thus in hydroelectricity power plants potential energy of water
is converted into electricity.
23
Samanalawewa
- Vertical shaft
- Salient poles
- 3 phase ,2 units
- Rated power 70.6 MWA
- Rated voltage 10.5 KV
- Output 60 MW
Kukuleganga
- Vertical shaft
- Salient poles-12 poles
- 3 phase
- 2 units
- Rated power 4200KVA
- Rated frequency 50 Hz
- Power factor 0.85
- Output 37 MW
Generator and main systems
- Cooling system
- Compress air system,
- Brake system
- LP and HP oil system
- Fire protection system
- Etc...
Following are some details about those systems of Samanalawewa Power Station that I
could studied.
24
Cooling Water System
In the cooling water gallery, there are 5 cooling water pumps. Two for each unit, among
two, one for operation and other one is standby pump while other one for stationary
supplies. Main cooling water pumps are horizontal shaft double suction centrifugal pump
have 35m-10.5 m3/ min, service water supply pump is horizontal shaft single suction
centrifugal pump have 25m- 3.5m3/min.
Cooling water system of generator
The cooling water system comprises three main circuits supplied in parallel:
- Air coolers for generator
- Oil coolers for LP lube oil system for the upper bearing housing
- Cooling coil in the lower guide bearing oil chamber.
Compressed Air System
Two compressed air systems
1. Service compressed air system
Vertical water cooled 2 stage compressor
Ratings of compressor 9 bar – 180 𝑚3/ℎ𝑟
Volume of air tank: 3000l
2. Governor compressed air system
W – Type air cooled 3 stage compressor
Ratings: 67 bar – 477lit /min
Volume of air tank: 2000 l
HP and LP Lube Oil System
• HP oil system - Oil is drowning from the upper bearing housing via a strainer to a single
outlet, electrically driven, high pressure Oil pump. The high pressure oil passes through a
Micronics filter to a distribution manifold in the bearing housing. Each thrust pad is fed
from the manifold by a separate flexible hose. A standby AC motor – driven pump is
provided in case of failure of the main pump.
25
• LP oil system - LP oil for the combined thrust and upper guide bearing is circulated
externally in a low pressure flow system comprising oil strainer, main and standby ac
motor driven pumps and shell and tube type oil coolers.
Braking and Jacking System
The generator is equipped with 6 combined brake/jack unit a mounted on the lower bearing
bracket and acting against a brake track mounted on the underside of the rotor. The units
are actuating for braking by compressed air, from the unit brake air compressor. The brakes
are controlled by means of an air valve by ‘on’ and ‘off’ solenoids. A manual operating
facility is also provided locally at the valve by means of key-operated pilot valve for ‘on’
and push button operated pilot valve for ‘off’.
An arrangement of manual valves allows a mobile HP oil pump to be connected to the
system so that the brake units may be used for jacking up the rotor during maintenance
operations. A creep detector is fitted to enable shaft rotation to be detected whilst the
machine is shutdown.
Governor
The governor is of hydroelectric PID type. The main item of the governor system are the
regulator, actuator, speed signal generator (S.S.G), pressure oil supply equipment.
Regulator - The regulator is of the PID type. It consists of various solid state
control circuits which include a speed sensing circuit and proportional integral
derivative circuits and power amplifier circuit. The control signal is provided from
the regulator to the converter equipped in the governor actuator.
Actuator - The actuator is enclosed in the steel cubicle. When the unit speed
changes, the actuator immediately responds to the electrical signal from the
regulator.
S.S.G-The S.S.G consisting of three magnetic pickups and toothed wheel is
insulated on the top of the generator housing. The S.S.G is insulated electrically
from the generator. It provides a frequency signal proportional to the unit speed.
26
The pressure oil supply equipment -The governor oil supply system consist of the
oil pressure tanks, sump tank, oil pumps, unloader valves, pilot valves, strainers
etc. oil in the sump tank is drawn up by the oil pump and stored in the oil pressure
tanks. Compressed air is trapped in the space above the oil level of the oil tank.
Pressure oil from the tanks is used for operating the governor, inlet valve,
automatic control devices etc. one oil supply system is provided for water turbine,
while two oil pumps are provided, one being selected for normal operating and the
other for standbys.
Fire Protection System of the Generator
Fire protection of the main transformer is by a high velocity water spray system. On
detection of a fire, the automatic deluge value controlling the fire area is caused to operate.
This release pressurized water at 10.75bar, from the 40 m3 capacity pressure tank, in to the
water distribution pipe work. The distribution pipe work then routes the water to the
transformer bay where it is directed at the transformer by a series of projectors.
A fire is detected by quartzite bulb/pressurized water detection system. The quartzite bulbs
are design to shatter should the temperature exceed 79oC, thereby releasing the pressure in
the detector pipe work. This fall in pressure acts on the deluge valve casing it to trip to the
open position. A small water charging pump and an air compressor are provided for filling
the water pressure tank. The system is controlled from a control kiosk located in the
transformer firefighting bay.
2.2.9 400V Switch Board
The main 400V switchboard consists of four individual switchboards interconnected by
encapsulated resin filled bus ducts. In addition to the 400V switchboard, an auxiliary 400V
switchboard for the diesel generator set is provided. The main 400V switchboard has four
in feeds, namely unit transformer one, unit transformer two, station transformer (fed from
the 33KV network) and the diesel generator supply. Only one in feed supplies the 400V
board at any time. Order of priority being either unit transformer, station transformer or
diesel generator. The diesel generator supplies only the essential service board and one of
the unit boards to enable black start of one generating unit.
27
2.2.10 Switch Yard
The 132kV switch yard is the outdoor double bus bar configuration utilizing conventional
open terminal equipment. The switch yard comprises four outgoing feeder circuit, two
incoming or generator circuits and a bus coupler circuit. Three empty bays are provided
which are available for future extension to the switch yard. Each incoming and outgoing
circuit is provided with surge arresters, capacitor voltage transformers, SF6 circuit breaker
and two bus bar selection disconnecting switches. In the case of the generator circuits, the
surge arresters are located at the main transformers, rather than in the switchyard. The
outgoing circuits additionally are equipped with a line trap bolted to the top of the yellow
phase capacitor voltage transformers. The bus coupler circuit couples bus bar 1 to 2 via
two bus bar disconnecting switches and a SF6 circuit breaker. The disconnecting switches
and SF6 circuit breaker. The disconnecting switches are provided with earth connection
Switches to earth one or both of the station bus bar. Current transformers are positioned
on either side of the bus coupler circuit breaker for over current protection and are used in
the station bus bar protection scheme. The 132KV circuit breakers are of the SF6 puffer
type, the operating mechanism being electro-hydraulic. A mechanical interlocking system
is provided for the switchyard equipment utilizing fortress key interlocks.
There are three mode of control of the switchyard equipment as local, remote mimic panel
or remote supervisory control.
2.2.11 Generator Transformer
Each generator is provided with a step up transformer of voltage ratio 138/10.5 KV and
rated at 71MVA. The transformers are of the oil immersed three phase type with
ONAN/ONAF cooling. The HV and LV bushing are oil/air insulated. The H.V. bushing is
of the open terminal type for connection to the overhead 132KV line conductors. The L.V
terminals are connected to the 10.5KV isolated phase bus bar system and are totally
enclosed.
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2.2.12 HVAC system
There are two different air conditioning systems in the plant. One for control room area
and office area and other one are machine hull and loading bay area.
Water chiller, chilled water circulation pump, air handling unit and control panels are
provided in the A/C plant room. Water chiller in the A/C plant room serves the both HVAC
systems. Chilled water is supplied to the AHU-1 in the A/C plant room and cooling that
coil by the circulating cooling water through the heat exchanger. River water from the tail
race is supplied to the system by the cooling water supply pump which is installed in the
cooling water gallery. That system can represent roughly by using the following figure.
Then chilled water is passes through the cooling coil in the air handing unit. Chilled water
flow path and arrangement of the air handling unit is shown in the figure,
Chilled water in Chilled water out
Cooling water inlet
from the tail race
Cooling water outlet
from the tail race
Figure 3-13 Chilled water cooling system
29
Figure 3-14 Air handling unit arrangement
As shown in the above figure, air temperature at the return position of the cooling coil in
AHU is transmitted to 3- way motorized valve by dew pint sensor and chilled water flow
volume is controlled by motorized valve to suit the air temperature same as the set point
on the automatic control panel. There is a smoke exhaust air system with a AHU. At the
time of the fire accident, air condition supply system stop and return air fan operates as
smoke exhaust fan automatically. Smoke detector and motorized damper are provided to
serve this mechanism.
By considering necessity of the clean, smell and dirty free air toilet exhaust, kitchen
exhaust, oil store exhaust are not used for return air. Separate ventilation systems are
provided for that area.
Fresh air
Supply air
Return
air
Smoke
detector
Louvers
30
2.3 Maintenance Works
2.3.1 Annual maintenances (28/12/2015- 11/01/2016) – Kukuleganga Power
Station
Repairing and maintenance of spiral casing was done.
- Dewatering of spiral case and draft tube liner was done by closing the Main Inlet
valve (MIV) and draft tube flap gate and opening the drainage valve of spiral case.
- Then the maintenances have been started.
- After dewatering visual inspection was done in mud removed and cleaned spiral
casing and the damages of painting for water contact surface were solved by
repainting process.
- Such a repainting process was done on that day. First old paint was removed and
primer was applied and then an anticorrosive paint was applied.
Figure 3-15 Repairing and maintenance of spiral casing process
31
Figure 3-16 Paints used for repainting the spiral casing
A Cooler of the generator was pressure tested.
- Tested Pressure : 6 bar (Working Pressure : 5 bar)
- If Leakage is detected, rubber packing was replaced. But fortunately there was no
leakage.
Figure 3-17 Pressure testing setup
32
Resistive Temperature Detection Tests for the temperature sensors of main bearing,
lower guide bearing were done.
- Equipment Used: Heater, SAE 46 lubricating oil vessel, Thermometer are used
- First the oil bath was heated up and temperature was measured using
thermometer and compare it with the reading displayed by SCARDA system
(calibration was done).
By using a Low Pressure Pump the main bearing (trust bearing) is cooling from draft
water. With parallel to annual maintenance the sealing packing of it that pump was
replaced.
Repaired gate valves of cooling unit of the turbine were re-fixed.
Figure 3-18 Repairing of gate valve
Cyclone separators are in service to supply clean water to turbine shaft seals where the
cooling water further purified and sand and other particles are removed. Sand collector
will be equipped under the cyclone separator, the motor driven drain valve can be
opened automatically by timer or manually by pushing the button to discharge the
sand drain. Such a cyclone separator was dissembled to repair under the annual
maintenance.
33
The oil of lower guide bearing, turbine guide bearing and trust bearing was filtered
using the portable oil filter unit.
Figure 3-19 Portable oil filter unit
The clearance larger than recommended value may permit excessive vibration of
turbine. Therefore clearance should be adjusted if necessary. For that the clearance in
between bearing pad and shaft were measured.
o Procedure
I. Guide bearing housing cover was removed.
II. Clearance between shaft and bearing was measured with long feeler gauge.
This clearance will probably not be uniform since the shaft may not have come to rest
in the center of bearing. However the average sum of clearance at diametrically
opposite points is desirable. But for the easiness using pulling bolts clearance at
one point of diametrically opposites were made into zeros.
34
Figure 3-20 Clearance measuring test
The ‘O’ rings of the oil cooler of lower guide bearing were replaced.
Procedure
I. The required diameter and length of rubber cord were determined.
II. Drop of Loctite instant (Adhesive) was applied to one end of rubber cord.
III. Two ends of rubber cord was jointed.
IV. Then the rubber ‘O’ ring was placed and coolers were re-fixed.
Figure 3-21 Replacing the ‘O’ rings of the oil cooler
35
Oil cooler of governor unit that helps the counter balance which used as mechanical
hydraulic unit to keep the turbine speed stable and regulate the turbine output was
pressure tested at 5 bar and the sealing packing was replaced.
The sealing packings of water supply line system of the governor unit was replaced
and the valves were cleaned.
Clearances of runner guide veins were measured using feeler gauge and electronic
venire caliper.
Figure 3-22 Clearance measuring of runner guide veins
Non Destructive Testing for pole stoppers was done.
o Procedure
- Test part was cleaned and dried before applying penetrant.
- Penetrant was sprayed to cover the test area.
- Time of 20 mins. was allowed before removing surface penetrant.
- Surface penetrant was removed by wiping surface clean with a cloth
moistened with cleaner/ remover.
- Then the developer can was held 20 to 30 cm from the area to be inspected
and thin, even film was sprayed on the part. Followed 10-15 mins of
recommended developing time.
- Final visual inspection was done to identify the cracks. If there are any crack
we can see purple lines clearly in white background. But here we could not
find any cracks
36
Figure 3-23 Crack detector dye penetrant
Spiral casing, draft water tube and etc. were inspected before closing the manholes to
re-fill the water.
Rubber sealing were replaced and manholes were closed after ensuring that nothing
and nobody is inside of those.
Figure 3-24 Closing the manhole of spiral casing
The couplings of bearing oil circular pump and bearing oil coolers pumps were re-
fixed and tighten
37
Figure 3-25 Tightening a coupling
Cleaned parts of the dust remover (filtering bags) that used to suck out dust inside
generator were re-fixed.
2.3.2 Breakdown Maintenance at Kukuleganga Power Station
A sound from chiller was noted down and the air intake was examined.
o Reason: Then the damper switch of one air intake (There are two air
intakes as standby and operational) wasn’t closed well. So the signal to start
other intake at particular shift change wasn’t taken place.
o Solution: As the reason to malfunctioning damper switch is the dust and
deposition of water particles over long time on that contact surfaces. So a
cleaning is done by spraying a cleaner on it. At that time other intake was
started by switching manual mode in control panel.
38
2.3.3 Maintenance works at Samanalawewa
Gate valve of a cooling unit was repaired.
Some gas and arc welding processes were carried out to maintenance works
Different machines of workshop were studied and a chance to operate them was
received. In the workshop of Samanalawewa hydro power station there are
machines for lathe operations, drilling operations, milling, pipe bending, grinding
and etc.
Figure 3-26 Some equipment in machine shop
Water chiller in Air Conditioning plant room services both AC and ventilation
purposes. In our training days at there, one chiller unit had a leakage in its
condenser (water cooled) due to high pressure where we got a chance to reassemble
that unit for repairing. Reason to have a high pressure is due to scaling in copper
tubes of copper tubes of condenser unit as the condenser used in power station not
the best selection for those working conditions. Due to number of tubes for water
cooling is less high pressure is created when units works at fully load. Then
leakages occurred due to that high pressure. Dissembled chiller unit due to water
leakage.
39
2.3.4 First Aid Camp at Samanalawewa
During our training period we got a chance to participate for a one day first aid camp
where we could get knowledge of how to handle an immediate accidents, what are the
first aid tips that we must follow in those situations and etc. Some of first aid tips are
follows as extracted from leaflet provided at that day.
Figure 3-27 First aid tips
Figure 3-28 Artifical breathing practical section
40
2.4 Thermal Power: How It Works
1. Steam Power Plant
2. Diesel Power Plant THERMAL POWER PLANT:
3. Gas Turbine Power Plant Converts Heat into Electric Energy
4. Nuclear Power Plant
Figure 3-29 How a steam power plant works
As similar in hydro power plant that water flows through the turbine, here steam is sent
through the turbine to generate the electricity which produced by coal fired, diesel fired,
nuclear powered or any energy power operated boiler.
In Sri Lanka we have KPS Gas Turbine, Sapugaskanda-Diesel, Puttalam LakVijaya Coal
Plant and few other steam power plants.
But only one coal power plant in Sri Lanka is Puttalam LakVijaya Coal Plant where I got
an opportunity to get a training of six weeks.
41
2.4.1 Important of Coal Power Plant to Sri Lanka
In the present energy has become a more significant factor in the world in power side and
also in an environmental side and also the CEB search the ways to generate electricity
which is cheap and environmental friendly. Hydraulic Power is the cheapest and
environmental friendly method to generate electricity, but hydraulic power cannot fulfill
the nation’s energy consumption
Also with Sri Lanka’s exponential growth the demand for electricity is increasing by about
10% annually. Presently daily electricity requirement of the country stood at 1.9 GW.
Energy supply in Sri Lanka is mainly based on three primary resources, namely,
hydroelectricity, petroleum, and biomass. Hydropower produces 49.4% of electricity and
the wind power produce 0.02% and deficit of 50.58% is fulfilled by fuel.
Generating electricity from oil(diesel, heavy fuel) is cost nearly around 60 rupees per one
unit .So generating electricity from coal is much more than oil because it will cost only 9
rupees per unit. Environmental conditions can be managed by adding suitable methods.
However, Sri Lanka s average consumption is 400 kilo Watt hours per person per annum
and for the country to elevate itself to that of a middle-income level country like Malaysia,
power consumption should be around 2,000 kWh per capita per annum. The North and
Eastern Province too has already progressed in the electrification process and electricity
demand will rice soon.
Electricity costs in Sri Lanka were among the highest in the world with all users paying
high cost for industrial, commercial and domestic uses and driving away the investors.
Main reason for electricity to cost so much is because of our dependence on expensive fuel
oil. The ideal energy source for Sri Lanka should have been a combination of hydro and
coal but high-cost diesel had been promoted due to commercial pressure with diesel being
preferred the energy source of Sri Lanka s Independent Power Plants.
But now at the present moment still we are not taking electricity from private suppliers
also there is a severe drought. All are due to this coal power plant. Otherwise CEB has to
make lot of power cuts and pay lot for private suppliers.
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2.4.2 Working of a Coal Fired Plants
In a coal fired steam station water is turned into steam, which in turn drives turbine
generators to produce electricity. Here’s how the process works.
1. Heat is created
Before the coal is burned, it is pulverized to the fineness of talcum powder. It is then mixed
with hot air and blown into the firebox of the boiler. Burning in suspension, the coal/air
mixture provides the most complete combustion and maximum heat possible.
2. Water turns to steam
Highly purified water, pumped through pipes inside the boiler, is turned into steam by the
heat. The steam reaches temperatures of up to 1,000 degrees Fahrenheit and pressures up
to 3,500 pounds per square inch, and is piped to the turbine.
3. Steam turns the turbine
The enormous pressure of the steam pushing against a series of giant turbine blades turns
the turbine shaft. The turbine shaft is connected to the shaft of the generator, where
magnets spin within wire coils to produce electricity.
4. Steam turns back into water
After doing its work in the turbine, the steam is drawn into a condenser, a large chamber
in the basement of the power plant. In this important step, millions of gallons of cool water
from a nearby source (such as a river or lake) are pumped through a network of tubes
running through the condenser. The cool water in the tubes converts the steam back into
water that can be used over and over again in the plant. The cooling water is returned to
its source without any contamination, and the steam water is returned to the boiler to repeat
the cycle.
43
Figure 3-30 From coal to electricity
44
2.4.3 Introduction to LakVijaya Power Station
As the 1st coal power plant in Sri Lanka LakVijaya Coal Power Plant is doing a great
amount of work to the National energy supply. It is located at Norachcholai village, in
Narakkalliya. As the main advantage of LakVijaya power station is it will not affect by the
environmental conditions like the hydraulic power plants because of that CEB can have
full load capacity throughout the year. It would be a major advantage for the CEB when
energy problem started. As the main weakness of the LakVijaya power plant is supplying
the coal at right time and stores them to a certain period. Because ships cannot come every
month of the year from May to October because of the sea waves because of that coal
storing facilities should be improved. Also there will be SO2 byproduct in flue gas, it is
not good for humans and it should be removed from flue gas.
2.5 Main Sections of LakVijaya Power Station
2.5.1 Fuel Handling Section
Coal handling- Provides coal to the three boilers in the power plant and unloads the coal
from the ships.
Supply ignition and combustion supporting oil-light diesel oil.
There are delivery pumps for diesel and conveyer system with other supporting equipment
for coal.
In LakVijaya Power Plant we use Bituminous coal,
As it has following characteristics compared to Anthracite and Lean coal
Ignition and combustion are relatively easy
Flame is long
Calorific value is relatively high
Weak chocking behavior during combustion
45
And also relative to Earth coal Bituminous coal good for long distance conveying and
longtime storage.
Bituminous coal specifications
- Particle Size : < 50 mm
- Moisture Content : < 12 %
- Gross Calorific Value : 5800 - 6300 kCal/kg
- Ash Content : < 15 %
- Bulk Density : 0.8-0.85 t/m3
- Sulphur content : 0.2 –1.2 %
- Volatile matter : > 22 %
- Fixed carbon : > 43 %
Power Plant will burn imported coal of high quality and low Sulphur Bituminous coal from
Australia, South Africa, Indonesia and the United States (but most of the time these coal
imported from Indonesia and South Africa). Imported coal would be unloaded to barges
at mid sea, and coal barges will then be unloaded onto conveyors on near shore trestle jetty
and transferred to the coal storage yard.
- Coal is transported by the ships called “PANAMAX” and capacity of these ships
nearly around 85000GWT.
- Then that coal transported to the jetty by the self-propelled barges (Capacity:
around 1500-2000 tons) and then they unload by the ship unloader.
- Coal purchasing and handling up to jetty is done by “Lanka Coal Company”
- Coal consumption for one Boiler : 114 t/hr
- Coal storage capacity 738,720 t
46
Figure 3-31 Coal unloading system
Figure 3-32 Jetty
47
Figure 3-33 Self propeller barge
Ship Unloader
Bridge type grab ship unloader is one of the main unloading devices of project loading and
unloading feedstock coal in Puttalam 300MW coal power station dock, this is the type with
4-winding-drums hauling car. When working, after grab bucket grabs bulkcargo from
cabin, grab car runs towards shore, unload the bulkcargo to the inboard hopper of front
gantry, cart drives the whole machine to run along the dock track to realize shifting taking
materials.
Figure 3-34 Coal unloading process
48
Bridge type grab ship is mainly composed by security supporting facilities, including steel
structure; rising, opening and closing, car running gear (the three melds, we call them 4-
winding-drums gear for short); amplitude gear; cart running gear; material conveying
system; dustproof and environmental system; mobile operator’s cab; electrical system;
inspecting facilities and wheel clamping device, anchoring, hitch lines, safty hook, limit
device,etc.
Figure 3-35 Parts of bridge ship unloader
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Coal Yard
Figure 3-36 Coal yard
The total storage capacity of coal yard is approximately 738,720 t, which can meet up with
the coal consumption of 900MW units for 90 days or three months. There is a wind
resistance wall with height of 15m located near sea side along the coal yard. Anti-penetrate
film is provided on the coal yard ground to prevent coal water from penetrating or
contaminating the ground water. Also the coal yard consists of dry coal shed. That means
of concrete supports with a steel roof enclosed and for phase I dry coal shed has
length/width/height of 50m/100m/30m, and the capacity is 19,152 t, which can meet up
with the coal consumption of 300MW units for 7 days.
Bucket Wheel Stacker-Reclaimer
There are two bucket wheel stacker-reclaimers in the power plant and its arrangement
makes coal stacking to coal yard and supplying coal to coal bunkers simultaneously.
- stacking capacity : 1500t/h
- reclaiming capacity : 600t/h
Figure 3-37 Bucket wheel stacker-reclaimer
50
Belt Conveyer
This conveyer system is use for the transport coal from jetty to coal yard and coal yard to
coal bunkers. The design capacity of conveyor and their associated equipment will be
calculated on the basis of 24 hours continuous operation. These conveyers are different
from each other.
Coal Bunkers
After coal is transport through the belt conveyers to feed to the boiler they are temporally
stored in the coal bunkers. There are five coal bunkers for the one boiler.
Fuel Supply System to Boilers
By the fuel system supplies the necessary fuel to the furnace. For the startup of the boiler
diesel is used and after reaching the balanced condition coal is used in the furnace. This
diesel line is always in operational which means that diesel oil pumps always operating
when plant is at operational and circulating the diesel. Coal feeding system consists of
coal feeder, coal pulverizer and coal burners.
Figure 3-38 Coal bunker
51
Coal feeder
There are five coal feeders in one phase and it is able to supply coal continuously and
evenly. During whole process of operation, the feeder performs accurate weighing of the
feeding and indicates the instantaneous value and accumulative amount of coal supply,
and automatically adjust coal supply quantity according to the instruction of boiler
combustion control system to meet the requirement of boiler load.
Figure 3-39 Coal feeder
Coal pulverizer
The type of mill is MPS HP or ZGM and bowl type middle speed mill. When burning the
rainy season coal or range of coal, all pulverizer have to be used. The total output of
operating pulverizes except the standby one is greater than 110% of consumption of coal
at BMCR condition. Pulverizes is capable of re-starting, following an emergency trip.
There are five coal pulverizer in one phase and four is operational and one is standby. Its
main function is to pulverize the coal from coal feeder. It consists of transmission device,
grinding roller, spring load device, bowl device, side body, separator body, blades device,
Venture Outlet and porous outlet devices, coal pulverizer outlet valve device.
52
Figure 3-40 Coal pulverizer
53
2.5.2 Boiler and Boiler Auxiliaries Section
In this part mainly consist of boiler and to support the functions of the boiler and there are
many boiler auxiliary systems such as,
Furnace
Air system
Ash handling system (both fly ash and bottom ash)
Fuel system
Electrostatic Precipitator (ESP)
Flue Gas Desulphurization system (FGD)
Boiler
The boiler is all steel-frame suspension structured, bituminous coal- fired drum boiler with
sub-critical parameters, natural circulation single furnace, primary intermediate reheat,
balanced draft, corner firing four corner arrangement sway burner ,tangent burning, and
dry ash extraction. The boiler mainly consists of steam drum, water wall, divisional panels,
re-heaters, super heaters, economizer, soot blowers and air pre heaters. The wall type
radiation re-heater and big patch divisional panels are arranged (hanged) in the upper
furnace to increase the radiation characteristics of the re-heater and the super-heater. There
are all together 92 soot blowers which include 60 wall soot blowers and 32 extension soot
blowers which use for the cleaning of the ash deposit on the water wall.
Table 2.1: Boiler specifications
Boiler design parameters BMCR condition THA condition
Super heated steam flow 1025t/h 912t/h
Super heated outlet pressure 17.3Mpa 17.2Mpa
Supper heated steam outlet temperature 5410C 5410C
Reheated steam flow 851.3t/h 762.8t/h
Reheated steam inlet pressure 3.993Mpa 3.574Mpa
Reheated steam outlet pressure 3.793Mpa 3.395Mpa
Reheated steam inlet temperature 338.50C 326.90C
Reheated steam outlet temperature 5410C 5410C
Feed water temperature 282.20C 274.60C
BMCR : Boiler Maximum Continuous Ratings THA : Thermal Heat Acceptance
54
55
Figure 3-41 Steam cycle
56
Main Components of the Boiler System
Economizer
The function of the economizer is to heat the boiler feed water, thereby recovering heat
from the flue gas leaving the boiler. Its arrangement has been designed to be completely
drainable. The water flow preferably is upwards. The economizer has been divided into
banks the height of which is not more than 3.2m and the distance between the banks is not
less than 0.8m.
Super heater system
The super heater consists of six main components; final stage super-heater, rear plate
super-heater, isolating platen, vertical low-temperature super-heater, horizontal low-
temperature super-heater, rear pass wall enclosure and ceiling super-heater. The super-
heaters are equipped with two-stage de-super-heater sprays. Total flow of spray water is
less than 10 percent of MCR flow of boiler.
Steam drum -
Drum diameter Φ1778mm, wall thickness 178mm, body length18000mm, total length
20184mm, gross weight 189 tons. There is cyclone separators inside the drum to separate
the water in steam and also it consist of safety valves for the safety of the drum. The feed
water for the boiler is directly entered to the drum through the economizer and then the
water and steam separated in drum and water is delivered to the water walls through the
down comers.
Figure 3-42 Steam drum
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Re-heater system
The re-heater consists of three main components; final re-heater, re-heater front platen,
wall radiant re-heater. Burner tilting is adopted to control steam temperature of re-heater
and total flow of emergency de-superheating spray water for re-heater is less than 5 percent
of MCR flow. Change of excess air also can control RH steam temperature as assistant
method at lower load.
Figure 3-43 Main component of the re- heater system
Figure 3-44 Boiler main auxiliary systems and steam path arrangement
Boiler
Furnace
Economizer
HPH1
HPH2
HPH3
Supper heater
LP Turbine
Condenser
Hot well
HP Turbine
IP Turbine Re-heater
LPH1
LPH2
LPH
3 LPH
4 Gland steam condenser
Deaerator
Deaerator tank
58
Furnace
Furnace consists of four oil burners at four corners which can be tilted up and down and
the all burners are tangential firing and also consist of five coal burners in five layers at
four corners. Also there are secondary air delivery windows.
In the furnace it uses the tangential firing method to fire coal and the oil. In furnace ignition
oil are used for warming up boiler during start up, coal nozzle ignition and the stabilizing
combustion under low load. Extractable high energy igniter and simple mechanical
atomization nozzle is adopted in oil gun
Two imaginary cycles are adopted in the furnace. Main burning system imaginary cycle is
must be tangential firing with counter clockwise. OFA is designed to be anti-tangential.
So it can form reverse momentum to balance the main rotary momentary and reduce the
furnace outlet gas deviation. Furthermore combusting with higher ratio of OFA reduce the
NOx formation.
Figure 3-45 Burner and wind box arrangement inside the furnace
59
Figure 3-46 Plane view of the fire arrangement and imaginary fire circle
Table 2.2: Furnace Specifications
Primary air ratio 22.20%
secondary air ratio 73%
Primary air temperature 3360
secondary air temperature 344.40
primary air velocity 27m/s
Secondary air velocity 47m/s
tangential circle diameter 800m
Air System
In the air system is consists of primary air system, secondary air system, seal air system
and flue gas system. By the secondary air system it supplies necessary air for the furnace.
The seal air system is used to supply the seal air for the coal mills and coal feeder.
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Primary Air system
The function of this system is providing air to pulverizer for transport coal to furnace. The
primary air is supplied by two constant speeds, electric motor-driven, centrifugal, primary
Air (PA) fans. Fans are suitable for all weather outdoor operation. There are two primary
air fans and after the primary air fans part of air goes to the APH (air pre-heater) and other
part goes to wind box. Then heated air outlet of the primary air will be combined into a
common duct at wind box which the air distributed to each pulverizer. The air flow rate
will be controlled to maintain the proper velocity in the pulverizer and in the conveying
pipes.
Figure 3-47 Primary air fan
Secondary Air system
The function of the secondary air system is to provide large amount of hot air for the
optimum combustion process in the furnace. Two forced draft (FD) fans having constant
speed, electric motor - driven, axial flow supply secondary air to the furnace. Fan inlets
are provided with silencers. Variable dynamic blade pitch is used to control (hydraulically
controlled) the flow through the fans. Secondary Air is heated by Air Pre-Heater (APH).
From the APH, the secondary air is distributed into the boiler wind boxes.
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Seal Air system
Seal air is supplied to the following equipment pulverizers, coal Feeders, pulverizer
primary air inlet dampers, and pulverized coal shut off gate other dampers and accessories.
The source of the seal air is air from the PA fan. Two constant speed and electric motor-
driven, seal air blowers is used to obtain the required seal air pressure. While one fan is in
operation, the other one is stand-by. The capacity of each seal air blower will be 1.2 times
of the total seal air.
Figure 3-48 Seal air fan
Flue Gas system
In the flue gas system, gas flue flow coming from burning goes through heat exchangers
then is vented to the outside air continuously and instantly in order to maintain boiler
running. To take out the flue gas from the furnace there are two induced draft (ID) fans.
When the flue gas came out from the boiler their heat energy is recovered by the Air Pre
Heater (APH) and by this heat it heated the secondary air. This APH works as the gas to
gas heat exchanger.
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FD fan and ID fan
Forced Draft Fans supplies the air necessary for fuel combustion and must be sized to
handle the stoichiometric air, plus the excess air needed for proper burning of the specific
coal for which they are designed. It provides air to make up for air heater leakage and for
some sealing air requirements. Forced draft fans supply the total airflow except when an
atmospheric-suction primary –air fan is used. It operates in the cleanest environment
associated with a boiler and is generally the most efficient fans in the power plant. The
main purposes of the ID fans are to take out the flue gas which in inside the furnace. The
flow rate of the flue gas is control by adjusting the stator blades angle of the ID fans.
Always flow rate from ID fan higher than FD fan to maintain negative pressure inside the
furnace.
Electrostatic Precipitator (ESP)
ESP is a highly-efficient, energy-saving equipment for flue gas cleaning, having merits of
high collection efficiency, large gas volume to be treated, long life span and low cost of
maintenance. At present, as the requirements for environmental protection are becoming
more and more stringent, ESP is used more widely.
When passing through the high voltage electrostatic fields, dust particles in the gas will be
charged by colliding with positive ions, negative ions and electrons or in the ion dispersion
movement. The particles with electrons and ions will then move, under the influence of
Figure 3-49 FD and ID fans
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the electric force, toward and later accumulate on the electrodes of opposite polarity. By
means of rapping, the layer of dust particles on the electrodes will be dislodged into the
bottom hoppers. Practice shows that the higher the strength of electrostatic field, the more
effective an ESP will be, and that it is preferable to have an ESP operating with negative
corona.
Figure 3-50 Working principle of ESP
Then passing through the high voltage electrostatic fields, dust particles in the gas will be
charged by colliding with positive ions, negative ions and electrons or in the ion dispersion
movement. The particles with electrons and ions will then move, under the influence of
the electric force, toward and later accumulate on the electrodes of opposite polarity. By
means of rapping, the layer of dust particles on the electrodes will be dislodged into the
bottom hoppers. Practice shows that the higher the strength of electrostatic field, the more
effective an ESP will be, and that it is preferable to have an ESP operating with negative
corona.
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Flue Gas Desulphurization system (FGD)
Flue-gas desulfurization (FGD) is a set of technologies used to remove sulfur dioxide
(SO2) from exhaust flue gases of fossil-fuel power plants, and from the emissions of other
sulfur oxide emitting processes.
Most FGD systems employ two stages: one for fly ash removal and the other for SO2
removal. Attempts have been made to remove both the fly ash and SO2 in one scrubbing
vessel. However, these systems experienced severe maintenance problems and low
removal efficiency. In wet scrubbing systems, the flue gas normally passes first through a
fly ash removal device, either an electrostatic precipitator or a wet scrubber, and then into
the SO2-absorber. However, in dry injection or spray drying operations, the SO2 is first
reacted with the sorbent, and then the flue gas passes through a particulate control device.
Another important design consideration associated with wet FGD systems is that the flue
gas exiting the absorber is saturated with water and still contains some SO2. These gases
are highly corrosive to any downstream equipment such as fans, ducts, and stacks. Two
methods that can minimize corrosion are:
o Reheating the gases to above their dew point, or
o Choosing construction materials and design conditions that allow equipment to
withstand the corrosive conditions.
Both alternatives are expensive, and engineers designing the system determine which
method to use on a site-by-site basis.
Figure 3-51 Fluegas desulfurization unit
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The FGD system includes a booster fan (Axial flow fan with adjustable guide vanes), a
GGH (gas-gas heater), a FGD inlet damper, a FGD outlet damper, three absorber pumps,
three aeration fans and other auxiliary devices. SWFGD Process is operating using the
seawater as the only absorbent. The seawater absorbs and neutralizes SO2 and any other
acidic mass in the flue gas.
At the first flue gas enters bottom of the FGD and it gives it heat through the GGH to
treated flue gas. Then sea water pumps to top of the FGD and by plastic packing layer sea
water is uniformly distributed throughout the absorber. Then the SO2 in the flue gas is
absorbed by the sea water and the same time those treated flue gas heated through the
GGH by the incoming flue gas to the FGD. In the absorber following chemical processors
are take place.
SO2 (gas) SO2 (dissolved in the sea)
SO2 (dissolved in the sea) + H2O SO32- + 2H+
After absorbing the SO2 by sea water those sea water is send the aeration basin. In the
aeration basin, following chemical processors are take place in the aeration basin.
SO32- + 1/2 O2 (gas) SO4
2-
CO32- + H+ HCO3
-
HCO3- + H+ CO2 (gas+ dissolved in the sea) + H2O
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Figure 3-52 Working principle of aeration basin
Figure 3-53 Aeration of sea water to remove Sulphur
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2.5.3 Turbine and Turbine Auxiliaries
The turbine body is comprised of rotating and static parts. Rotating parts include cascades,
impellers, main shaft, coupling and fasteners. Static parts are comprised of cylinder nozzle
box, diaphragm sleeve, gland seal, bearings, bearing seats, anchorage system, base and
related fasteners.
Turbine is sub-critical, primary intermediate reheat, single-shaft, double cylinder, double
exhaust, reaction, and condensing steam turbine. This turbine has three pressure stages as
high pressure, Intermidiate pressure and low pressure.high, intermediate pressure
cylinders are integrated into one, and through-flow parts are reversely arranged. For the
high-pressure cylinder, the steam enters it from the lower part, and flows through high-
pressure automatic main steam valve, governing valve, into the positive governing stage,
and then turns the steam flow back by 180° to the 12th reaction stage reversely. For the IP
cylinder, the steam enters it from the lower part, and flows through the IP combined control
valve into the positive 9th reaction stage. For the LP cylinder that is symmetrically
arranged, the steam enters it from the middle, and flows reversely via 7 reaction stages,
respectively. High, intermediate pressure cylinders are double-layer cylinders, and the LP
cylinder is a three-layer cylinder.
Figure 3-54 LP, IP and HP turbines
LP Turbine
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Rotor
HP rotor is combined rotor type, with governing stage at the middle and HP and IP part at
front and back which is integrally forging cast by heat-resistant alloy steel. There are
cooling steam holes at the roots of governing stages after which steam is extracted to cool
the first stage of IP stages, and this method can prolong the service life of rotor. An
extension bearing is connected with the front end of HP and IP rotor, thrust disc, main oil
pump and emergency ram are installed on it. HP and IP flow is arranged conversely, and
axial thrust is balanced by 3 balancing pistons to keep a small positive thrust.
Bearings
The whole turbo-generator unit has a total of six journal bearings that are respectively
fixed on the base seat. The radial bearings of HP & IP rotors are compressible, and the LP
rotor is equipped with 2 tilting-pad bearings and spherical cushion circular journal bearing.
The thrust bearing is a tilting, double adjusting block, located on the short shaft of the
turbine inside the front bearing housing
Figure 3-55 Bearing arrangement of the rotor
Turbine auxiliaries
In this part mainly consist of turbine and to support the functions for the turbine and there
are many turbine auxiliary systems such as,
Boiler feed water pump
Regenerative system
Lubrication system
Circulating water system
EH oil system Generator
Barings
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Boiler Feed Water Pump
Boiler feed water pump is consist of two main parts. They are boiler feed water pump and
boiler feed booster pump. At first feed water came in to the boiler feed booster pump. The
function of the boost pump is to raise the inlet water pressure of the feed-water pump in
order to prevent vaporization in the feed-water pump. Three 50% capacity, horizontal type,
single stage, double suction, centrifugal type boosts pumps are provided. Along the flow
direction, the inlet water pipes of boost pumps are equipped consecutively with a motor
operated gate valve, a pressure release valve and a coarse strainer. The pressure release
valve protects the boost pump and its inlet pipe from possible over pressure, in addition,
the pump warm-up water during reverse warm-up of the pump can also go through the
stand-by boost pump into the inlet pipe. Under those two conditions, an over pressure may
be induced in the stand-by boost pump and its inlet piping, if the inlet isolating valve of
the stand-by boost pump is closed. After the booster pump feed water enters to the boiler
feed water pump. Three 50% capacity, horizontal type, multistage double casing, barrel
type centrifugal motor operated regulating feed-water pumps are provided in the system.
Each feed-water pump is installed with its boost pump as an assembly, and sharing one
motor. A fine strainer is provided in the inlet pipe of BFP, its function is the same as that
of the coarse strainer, but it will not be removed after a certain period of operation. When
the fine strainer is closed by contaminants and high differential pressure is induced, the
pump will be shut-down to clean it out. A main feed water flow nozzle is provided on main
feed water pipe downstream of the highest pressure heater to measure feed water flow to
boiler. The main boiler feed pumps have an inter stage bleed point to furnish re-heater de-
super heater water at the appropriate pressure level. Water to the main steam de-super
heaters is furnished from main feed water line upstream of the No.3 HP heater. The
controls for the re heater and super heater at temperature sprays are part of the coordinated
control system (CCS) to control the steam temperatures by modulating the spray control
valves.
Regenerative System
In the power plant there are eight regenerative stages and this regenerative system uses for
the increase the efficiency of the power plant. It consists of steam extraction, HP and LP
heaters and deaerator.
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Steam Extraction
The turbine has eight (8) pressure stages of non-regulating extraction steam. The No.1,2&3
extraction steam stages supply steam to three (3) HP heaters respectively to heat the feed
water which will flow into boiler. The No.4 extraction steam stage supply steam to
auxiliary steam header and deaerator. The No.5, 6, 7 & 8 extraction steam stages supply
steam to four (4) LP heaters respectively to heat condensate water which will flow into
deaerator.
HP and LP heaters
Feeding water system adopted in this 300MW unit adopts single series, horizontal and big
bypass arrangement. It consists of three HP heaters and uses the No.1, 2 and 3 extraction
steams as the heating medium.
This 300MW unit has four LP heaters, which are arranged in series connection. The type
is horizontal, double flow surface type. There are four LP heaters in one 300MW unit and
it uses the No. 5,6,7 & 8 extraction steam to heat the feed water.
Deaerator
In order to remove corrosive gases entrained in boiler feed water an open feed water heater
called a deaerator is incorporated into the power cycle. The deaerator is designed to heat
the incoming feed water to the saturation point in order to reduce the solubility of any
entrained gases. These are mainly oxygen, carbon dioxide and ammonia that become very
corrosive at elevated temperatures. The water is sprayed in a fine mist into the area that
contains the steam drawn from the high pressure heater drain and extraction steam from
the cold reheat section. This divides the water droplets increasing the overall surface area
therefore increasing the overall heat transfer. The water is then passed over a set of trays
that separates the water into thin sheets from which the gas can easily escape. The gases
are then vented out of the deaerator to the atmosphere.
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Lubrication System
The function of lube oil system is to supply lube oil to the bearings of the unit, the pressure
oil to the governing and emergency system, to the generator bearing and to the turning
gear and jacking device. This system adopts traditional turbine rotor to drive main oil
pump-oil ejector system directly, the main oil pump supplies the pressure oil to governing
and emergency system and also supplies the power oil to the oil ejector. The lubrication
system adopts horizontal type cylindrical oil tank. The AC lube oil pump, DC emergency
oil pump, HP START-UP oil pump, oil level indicator, oil level switch and oil tank electric
heater are installed on the cover plate of oil tank. The oil ejector is installed on internal
piping of oil tank. The oil tank is arranged above 0m floor. One HP oil jacking device is
set in T-G bearings, that the oil jacking pump is plunger pump and supplies oil to every
bearing through diverter and single-way throttle valve. When the speed increases
to1200r/min during startup, cut off jacking device; and during shutdown period, when the
speed decreases to 1200r/min, start oil-jacking device.
Circulating water system
The main function of circulating water is taking away the surplus heat of exhaust
discharged from turbine to condenser, and making it condensate to water. The main
equipment of this system includes a movable grilling filter in the CW pump house front
pit, two rotating filters at the inlet of CW pump, two CW pumps, one set of cooling water
device for CW pump motor, two debris filters, two sets of ball cleaning device for
condenser and its auxiliary pipelines.
Condenser
The function of the condenser is to make the exhaust steam form the turbine condensed
and turn in to the water and to ensure the exhaust outlet of turbine to build the necessary
auxiliary equipment with certain vacuum. Condenser consists of connection neck, shell,
water room and connection pipes of exhaust steam. The final two stages assembled LP
heaters (#7, #8 LP heaters) and condensers adopt single square shell. Its advantage is that:
it is made by welding steel plates, its process is simple, its weight is low and it may make
full use of space under turbine. It is single shell, bisection, double flow surface type.
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Exhausted steam of both turbine and feeding water pump enters into condenser. The water
room of the condenser is divided into two separate cooling water pipes, which have their
own cooling water inlets and outlets. When condenser is dirty, turbine does not need to
stop, it can be cleaned under condition of decreasing a certain load.
EH oil system
EH oil system supplies high pressure oil to turbine governing system, it is pumped from
fire-resistant oil tank by HP oil pump, it passes pressure oil filter and enters into HP
accumulator through single direction valve. EH oil then is sent to actuators and emergency
governing system by HP oil head pipe. EH oil system consists of oil tank, oil pump, control
block, oil filter, overflow valve, accumulator, oil cooler, EH terminal box and so on. There
are 12 steam valves in DEH system for one unit of the power plant, 2 HP combined steam
valves, among which there are 2 HP main steam valves, 6 HP governing valves; two IP
combined steam valves, among which there are 2 reheated main steam valves, 2 reheated
governing valves. The 4 combined steam valves are located at left and right sides of the
unit respectively. HP main steam valves (TV) are double valve butterfly style, operated
horizontally, arranged at two sides of HP and IP cylinder. There is one small valve for
startup inside the main valve; all valves are single seat non-balance butterfly valves. Open
startup valve to extreme position of its travel, if it opens further, main valve will open.
When main valve is fully open, it is self-sealing structure and there is permanent filter
screen and temporary filter screen at steam inlet. When it closes, startup butterfly valve in
main valve is able to align automatically. Main steam valve is a control type, which is able
to control steam valve at any middle position and to regulate inlet steam proportionally to
meet requirement.
Six (6) HP governing steam valves are installed in the unit, which are allocated at left and
right side of HP & IP cylinder, and assembled together with main steam valves in an
integrated forged piece, composing a steam incoming group. For each steam incoming
group, 1 main steam valve and3 HP steam governing valves are installed. HP steam
governing valve is to control steam flow coming into HP steam cylinder.
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2.5.4 Generator
The generator is three phases non salient pole synchronous generator. The neutral of
generator is grounded through dry transformer with secondary neutral. The generator
include stator, rotor, end shield and the bearing , hydrogen cooler, oil seal, sole plate, brush
holder, collector cover etc. The generator is completely enclosed. The main cooling
material is hydrogen gas circulated by fans. The excitation system of the generator is static
excitation system.
Table 2.3: Generator specification
Aperent power 353MVA
Active power 300MW
Maximum continuous power 332MW
Rated power factor 0.85(lag)
Rated stator voltage 20000V
Rated stator current 10190A
Excitation voltage 365V
Excitation Current 2642A
Efficiency 98.90%
Frequency 50Hz
Rotate speed 3000rpm
Number of phase 3
Stator winding connection type YY
Number of terminals of stator 6
2.5.5 Transformer
Generator Transformer
The transformer will be 3 phase, 50Hz, forced-oil force-air cooled (FOA), oil immersed,
outdoor type with copper windings and low losses. Transformer is supplied with radiators.
The Generator transformer's high voltage terminals are protected by three zinc oxide
lightning arresters at 220KV terminal cable to the switchgear.
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Startup /Standby Transformer (SST)
One Start/ Standby transformer (SST) is set for phase one. The SST is a three wingding
transformer with two equally rated secondary windings. It’s an outdoor type transformer
with on-load tap changer .The high voltage terminal of SST is connected to the 220kV GIS
switchgear through the cable, the low voltage terminal of SST is connected to the 6kV
spare incoming switchboard through the non-segregated phase metal enclosed bus. The
SST provide power to two separate 6kV buses during startup and normal shutdown of the
plant and during plant operation upon loss of the normal auxiliary electrical supply.
Unit Auxiliary Transformer (UAT)
The UAT transformer the generator voltage down to 6.3kV and provides power to two
separate 6kV buses during normal operation. The UAT is a three winding transformer with
two equally rated secondary windings. It’s an outdoor type transformer with no-load tap
changer.
2.5.6 Balance of Plant (BOP)
Balance of the plant section consists of sea water desalination system, boiler makeup water
system, condenser polishing plant, waste water treatment system, auxiliary boiler and
hydrogen generation system. These systems are used as the support system to the other
systems in the plant.
Sea Water Desalination System
Sea water desalination system uses to produce raw water from the sea water. It supply
desalted water for domestic, boiler make-up water system, firefighting, industrial water
and etc. The capacity of seawater desalted system will be 100 m3/h. Sea water will be
clarified and filtered, then will be transferred to sea water desalted system. There are four
treatment stages in the process,
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I. Coagulation
In this process they add two chemicals to the sea water coming from the row water pumps
which is called Poly Aluminum Chloride (PAC) and Polyacrylamide (PAM). Then this
water send to coagulation tanks and in the tank mud partials are settled in the bottom of
the tank.
Figure 3-56 Coagulation tanks
II. Filtration
After the coagulation process the water sent to the gravity filtration process. In this process
Water flows through the filter medium contained in an open tank or vessel under the
influence of gravity and then filtered water sent to the clear water basin.
III. Ultra filtration
Water in the clear water basin is then pump in to the ultra-filters (UF filters) to further
filtration process. This is a process of filtration with a semi permeable membrane with
pressure relatively lower than RO. Then the filtered water pump to the UF tanks
Figure 3-57 Ultra filter
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IV. Reverse osmosis (RO)
After the UF tanks water enters to the RO process. In here it removes many types of large
molecules and ions from solutions by applying pressure to the water. RO unit consists of
cartridge filter, energy recovery unit, high pressure pump, circulation pump and RO
membrane.
Figure 3-58 RO device
Energy Recovery unit (ERI)
By this unit Waste energy recycled at up to 98% efficiency. It consists of a rotor and
surrounding of that rotor has a sleeve and two end covers. At first high pressure reject
concentrate from RO enter one side of the ERI and low pressure sea water enters other
side of the ERI and fills the rotor where it exposed to the high pressure reject concentrate.
Then the hydraulic pressure is been directly transfer in to the reject to seawater. This sea
water goes back in to the system and joined to the stream from HP pump and concentrate
exits to drain. This pressure transferring process continuous and rotor only using fluid for
rotating and because of high rotating speed (1200 r.p.m) mixing between concentrate and
sea water is low.
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Figure 3-59 Energy recovery unit operation principle
After the RO device desalted water is send to the service and fire water, for make-up water
treatment system and for portable water inside the plant domestic work.
Make-up Water Treatment System
This system main functions are supply high purity boiler make-up water (De-mineralized
water) for boiler, supply high purity water to systems in power plant operation (chemical
lab, sample analysis, closed cycle cooling water system) and supply necessary high purity
water for the cleaning and flushing of boiler and turbine system and for lay-up and filling
of the system before start-up.
The capacity of second stage RO will be 2×36m3/h, the capacity of demineralizer will be
2×60 m3/h. The system will be RO, first-stage demineralization and mixed bed, and the
flow path will be as follows,
Figure 3-60 Make-up water treatment process flow chart
Desalted water De-carbonator Intermediate
water tank Safety filter
Second stage RO
Cation exchanger
Anion exchanger
Mixed bed
De-mineralized water storage
tank Main building
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Chlorination Plant
By this plant it provides the chlorine need to dosing to the sea water inlet in the sea. In
here it makes chlorine as sodium hypo chlorate (NaOCl). With seawater as raw material,
6.0KVAC is transformed and rectified to DC through transformer rectifier and applied to
the cathode and anode of seawater electrolytic cell. The seawater get electrolytic reaction
and generate active chlorine, which is put into once-through water cooling system and
seawater pretreatment system with sodium hypochlorite dosing pump to resolve issues
such as the adhesion and breeding of marine organisms and thallophytic in cooling water
pipes and copper condenser tubes, which reduce flow area and influence of water-delivery
capacity, lower cooling efficiency of the condenser, forcing the generating unit to operate
in low load and influence of power generation.
Anode reaction: 2Cl - Cl2+2e
Cathode reaction: 2H2O+2e 2OH-+H2
Chemical reaction between electrodes:
Cl2+2OH- ClO-+Cl-+H2O
ClO-+H2O HClO + OH-
HClO H++ ClO-
Overall reaction:
NaCl+H2O NaClO+H2
Hydrogen Generating System
The cooling method of our plant 1 × 300MW generator unit is water - hydrogen – hydrogen
cooling; hydrogen station provides central hydrogen supply. System include electrolyzer,
oxygen separation scrubber, hydrogen separation scrubber, hydrogen coolers, hydrogen
drying devices, hydrogen storage tank and the rectifier cabinet, desalted water cooling
devices. The hydrogen system is under complete automatic control, the system can
perform automatic open, shut down, automatic alarm and command operation. In the
normal operation, the computer screen can show process, real-time parameters, curves,
store data automatically and print various sheets. Total capacity of hydrogen storage is
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designed in accordance with normal consumption of hydrogen-cooled generator, and the
accumulated hydrogen storage is equivalent to total capacity of startup charging hydrogen
of largest hydrogen-cooled generator within seven days or so.
Figure 3-61 Hydrogen generating system
Figure 3-62 Hydrogen generating storage system
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Control Room (DCS) Operation
A distributed control system (DCS) refers to a control system usually of a manufacturing
system, process or any kind of dynamic system, in which the controller elements are not
central in location but are distributed throughout the system with each component sub-
system controlled by one or more controllers.
DCS (Distributed Control System) is a computerized control system used to control the
production line in the industry. The entire system of controllers is connected by networks
for communication and monitoring. DCS is a very broad term used in a variety of
industries, to monitor and control distributed equipment.
In LakVijaya Coal Power Plant we examine all the activities happened in power plant
from control room and if there is any deviation in process it will give notification.
Figure 3-63 Control room
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Gas-Insulated Substation (GIS)
Compact, multi-component assembly.
Enclosed in a ground metallic housing.
Sulphur Hexafluoride (SF6) gas: the primary insulating medium.
(SF6) gas- superior dielectric properties used at moderate pressure for phase to phase and
phase to ground insulation.
Preferred for voltage ratings of 72.5 kV, 145 kV, 300 kV and 420 kV and above.
Various equipment like Circuit Breakers, Bus-Bars, Isolators, Load Break Switches,
Current Transformers, Voltage Transformers, Earthing Switches, etc. housed in metal
enclosed modules filled with SF6 gas.
In Kukuleganga and Samanalawewa they have used not GIS but switchyards.
2.5.7 Maintenance Works
As electricity is a form of energy it can be neither created nor destroyed. And also the
Alternative Current (AC) can’t be stored. Thus, there should be real time the electricity
production with demand at that time.
This balancing act is done by taking the Frequency of your Power supply (50 Hz in Sri
Lanka) as a guide. When we supply exactly the demand the frequency of supply will be
stable (usually at the rated 50Hz). If our supply is less than your demand, the frequency
will fall below 50Hz and if we supply more, the same will increase above 50Hz.
However, during certain emergencies, our power plants can get tripped (disconnected or
automatically switched off). When a large power station gets tripped in this manner, this
supply demand balancing act gets disturbed. As result, the frequency of the power supply
starts to drop. The Engineers who are Operating the Power System has to act quickly and
resupply the shortage. However, this takes some time. Until the supplydemand balance is
restored, the frequency starts to fall below 50Hz
It is not healthy for power plants to operate below a certain frequency. For example most
of the present Grid Connected Power Plants in our system cannot operate below 47Hz.
Thus, if the low frequency situation is allowed to persist, after a certain time, the remaining
power plants too start to get switched off thus aggravating the power shortage further. This
could escalate in to a total cascaded failure.
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Such island blackout caused during our training period. We got the chance to see how the
engineers manage such instance. And replacing of diaphragm of generators where done.
Before starting of units all the units where checked. Especially we also got chance to
engage which inspection of pulverizer units, coal feeders and etc.
During my training at coal handling section pulley system of a gantry crane was repaired.
And also a coal handling belt system was repaired.
Figure 3-64 Repair the pulley system of a gantry crane
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CHAPTER THREE
3 MANAGEMENT
To a successful engineer it is very important to have not only the technical knowledge but
also the management skills when we are dealing with the industry. In the industry we have
to work with several kinds of fields such as
Demand Side Management
Financial Management
Human Resource Management
Quality Management
Safety Management
Environment and Waste Management
Etc.
3.1 Demand Side Management (DSM)
Demand Side Management covers “systematic utility and government activities designed
to change the amount and/or timing of the customer’s use of electricity” for the collective
benefit of the society, the utility and its customers. [2]
It is a combination of
Corporate objectives
- Improving power quality and reliability
- Minimizing pilferage,
- reducing system losses,
- improving the distribution network,
- upgrading substations,
- high collection efficiency ,
- improving customer service
- etc.
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Load Shape objectives
- Primarily DSM is considered as a cost-effective alternative to supply-side
options, it generally address one of the following specific load shape objectives
Peak Clipping: The reduction of utility load primarily during periods of
peak demand
Valley-Filling : The improvement of system load factor by building
load in off-peak periods
Load Shifting: The reduction of utility loads during periods of peak
demand, while at the same time building load in off-peak periods. Load
shifting typically does not substantially alter total electricity sales.
Conservation : The reduction of utility loads, more or less equally ,
during all or most hours of the day
Load Building : The increase of utility loads, more or less equally ,
during all or most hours of the day
Flexible Utility Load Shape : Refers to programs that set up utility
options to alter customer energy consumption on an as needed basis, as
in interruptible / curtailable agreements
No-load Shape objectives
3.2 Financial Management
Due to the authority of CEB in Sri Lankan power supply, it gets chance to earn more and
more income. But there are many key factors cause for deterioration of the liquidity of the
CEB such as, political disturbances, escalation of fuel prices and the cost of purchased
power, low generation from hydro’s due to less rains- climate effects, frequently occurring
unexpected break downs, more maintenance costs for old transmission system and etc.So
good financial management is necessary for CEB and the availability of working them
independently is important to achieve goals of company.
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Figure 3-1 Summary statics 2013
86
3.3 Human Resource Management (HRM)
In order to achieve the goals, the quality of Human Resources of an organization plays a
vital role. CEB staff totaling about 15000 employees have proven that they can deliver
output under any circumstances with their efforts to provide reliable and quality electricity
to all the customers. The Training Branch, Personnel Branch, and Human Resources
Officers deployed in the Regions and Divisions have played a vital role towards the well-
being of the organization.
HRM organizes training programs of professional development to all employees
in maintaining and enhancing competence of all the engineering and the technical
staff and soft skills of employees.
The human resources goal must be to get the mind set of all the Regions and
Divisions staff that all of them are a part of a single team to deliver one CEB to the
nation, to innovate and consistently think of faster and better ways to provide their
services to the customer.
CEB provides high salary and remuneration benefit to the team well above local industry
standards. Other than that, to create an environment which motivates employees towards
achieving goals of the Board, CEB has developed several schemes for the benefit of the
employees. These included
Payment of Bonus
Payment of Incentive against Un-availed Sick and Vacation Leave
Payment of various special monetary advances.
Long Service Awards
CEB Provident Fund
Employees’ Trust Fund
CEB Pension (subject to the CEB Pension Rules)
CEB Medical Assistance Scheme
CEB Loan Scheme
Retirement Gratuity
Other fringe benefits.
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Welfare Unit Welfare Unit - for looking after the staff welfare of its employees.
CEB circuit bungalows
Welfare shop
Maintain Montessori schools at all Power Stations
School transport services to the children of CEB families in addition to the
weekend long distance transport facilities to employees.
Sports and recreation facilities
3.4 Quality Control Program
The quality control program clearly defines the responsibility and duties of the quality
control. Checklists that describe the activities, the applicable specifications, standards and
requirements, the initiator, the interval of the examination etc. shall be included to such
program.
Contractor submits to employer for each test/control comprehensive report including all
main details on
Control/testing date, place, and conditions, responsible
Control / testing equipment
Control / testing results
Comments
There are several quality control systems to carry out in the plant operations as following,
Coal quality testing
Demine water testing
Boiler drum water testing
Waste water testing
Lubrication oil testing
To do those testing there is one chemical lab in the LakVijaya Power Station. And
Samanalawewa Power Station does only the lubrication oil testing. That test was done
from external lab.
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3.5 Health and Safety Management
CEB is highly concern “Safety First” concept as the risk at there is very high as they deal
with electricity which can be caused to many damages to lives and death. So safety
equipment such as overall, helmet and boots are mainly provided to all the employees of
power stations for improvement of the safety.
Safety in a Power Station
Planning ahead to control risks
- Ensuring that systems of work are safe and that equipment is properly
maintained.
- Employees are given health and safety information, training and appropriate
supervision.
Figure 3-2 How to avoid accidents
Station evacuation
Whatever the nature of the crisis, people must be able to get out of a hydropower
station safely. So in stations there are at least two independent ways to exit.
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Flood protection
Hydropower stations can and do flood. Failure of drainage pumps will lead to a
slow increase in the water level and eventual flooding of the station. So there is
alarms systems to detect the water levels automatically close the gates and valves.
Fire and smoke control
To detect fires as early as possible, prevent them from spreading, alert all
personnel, and provide safe and well-lit means of evacuation as soon as possible
fire control is important.
Different fire extinguishers used in power plants based on the type of fire as follows
Table 3.1- Fire Extinguisher Types
Fuel (caused for the fire) Extinguisher
Class A Organic solids
Ex. Papers ,woods
Pressurized Water
Class B Combustible liquid/oils
Ex. Oils, Petroleum
Foams, Water
Class C Combustible Gases
Ex. LP gas,CH4
Carbonated Water
Class D Electrical based fire Dry Chemical dust
Figure 3-3 Different types of fire extinguishers in power plant
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Smoke control and ventilation system also very important in hydro power stations.
Boiler hazards control devices like pressure regulators, water level detectors and
etc.
Chemical hazard-
Power plants workers are routinely exposed to dangerous chemicals such as
corrosives (acids and bases), oxidizers and solvents. So there are equipment
consists of emergency showers, face washes and eyewashes.
Figure 3-4 Eye washer
3.6 Energy and Waste Management
Environmental Policy Statement:
“Ceylon Electricity Board will manage all its business activities in a manner, which cares
for the natural and manmade environment and contribute to sustainable development. By
means of openness in dealing with environmental issues, we intend to create confidence in
our activities on the part of the public, customers, authorities, employees, and owners. We
will actively pursue a policy of incorporating and integrating environmental
considerations into our activities.”- [ceb.lk]
91
In order to integrate Environmental Considerations into its’ activities, CEB has set up an
Environment Unit which is responsible for monitor and assist in the implementation of the
Environmental Policy of CEB.
In my training period I was lucky to work in Samanalawewa Hydro Power Station which
was the first government entity to be certified with ISO 14001:2004 for its’ Environmental
Management System.
All the activities and processes in power station, dam, reservoir, tunnel intake, surge
chamber, portal valve house and CEB village (with staff quarters) are covered by the
Environmental Management System to assure the optimizing usage of resource and the
prevention of pollution. E.g.:
Environmental emergencies identification process.
- The process to prevent or mitigate associated adverse environmental impacts
by identifying and managing the potential emergencies of power station and
making instructions to handle them.
Environmental monitoring and measurement process
- Solid waste disposal system. Ex: To maintain a cleaner environment there is a
standard waste disposal system in the according to 5S method. The buckets that
collect the waste are colored as the type of waste is allowed for them.
Figure 3-5 Waste disposal coding system
- Dam monitoring system including leakage measuring, piezo-metric pressure,
water quality tests and sound and lighting level measurements.
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Energy conservation process
- Consumption of electricity reduces year by year with in the project with
different programs like replacing of incandescent lamps by Compact
Florescent Lamps.
In Puttalam LakVijaya Power Plant also highly concerned about the environment safe
guard as the pollution that can be occurred from a thermal coal power plant is higher than
hydro power plant. E.g.:
Minimizing of particular matter- Electro Static Precipitator unit is installed to
precipitated 98% of fly ash generated. Then the collected fly ash is sold for cement
manufacturing where disposal of collected fly ash problem solved automatically.
Figure 3-6 ESP unit
Control of Oxides of Sulfur and Nitrogen
After Electro Static Precipitator flue gas is sent to the Flue Gas Desulphurization
plant to remove the Oxides of Sulphur (SOx) and the boiler is designed with
advanced low NOx burner, in order to control the NOx emissions.
Dispersion of Flue Gas
After FGD flue gas will be dispersed into the atmosphere through a 150m tall
stack (chimney) during operation.
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CHAPTER FOUR
4 SUMMARY AND CONCLUSION
4.1 Summary
In my second undergraduate Industrial Training period I was placed in Samanalawewa
Hydro Complex for 6 weeks and Lakvijaya Power Station for 6 weeks. As a request of us
they divide our Samanalawewa 6 weeks into 2 sections as 3 weeks in Kukuleganga and 3
weeks in Samanalawewa. Due to that we got a rare chance of Annual maintain ace, First
aid camp and etc. And we could clearly understand the difference of modern and past
technologies of power plants designing and controlling where Samanalawewa is very old
compare to Kukuleganga project. And technology differences of Japanese and Chinese
(LakVijaya).
Finally we could get wide knowledge and experience in both hydro and thermal power
generation and management and HRM techniques used at those power stations.
And also during my training I have to travel to different parts of country through many
areas where I could get lot of experiences of multi-cultural societies.
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4.2 Conclusion
Industrial training period is the most valuable time period for an Engineering
undergraduate to deal with the field works. I was fortune enough to have my training
session of three months in a places like Kukuleganga, Samanalawewa and LakVijaya
power station. LakVijaya plant is the only coal power station in Sri Lanka. These 12 weeks
of Industrial Training has been very important and very helpful to developer engineering
skills and it broadens our knowledge about engineering world. It provides us to elevate our
engineering career in both theoretical and practical aspects of engineering.
While I was in power station there were so many things to learn. The DGMs, Chief
Engineers & Engineers of Operation, Maintenance sections gave me maximum
opportunities to have a good training section.
The Engineers and all the technical staff have given an excellent guidance and they were
always willing to share their practical knowledge with us. They always invited us to join
with them when they were doing some technical work so that we can take working
experience. The organization culture or the working environment was very pleasant and
encouraging to work. They maintained a necessary and sufficient formal relationship and
a good informal relationship with the trainees.
Since that was a government organization we could get little of hand on experiences. But
due to Annual maintenance of Kukuleganga Power Station we could get huge experience
than any of trainee of any other organization. If EEC (Engineering Education Center)
university of Ruhuna can discuss all necessary arrangement of trainees and training
schedules with organizations about maintenance periods, it will be good for
undergraduates so that students may try to get the maximum while training. As a whole, I
must say that CEB provides a useful training for engineering undergraduates to make them
knowledgeable and energetic engineers to country.
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5 References
[1] "How Hydropower Works," 24 April 2016. [Online]. Available:
http://energy.gov/eere/water/how-hydropower-works.
[2] "http://www.ceb.lk/," [Online]. [Accessed 2016 April 2016].
[3] CEB, Maintainance and Operational Manuals- Kukuleganga, Samanalawewa and
LakVijaya Power Statios.
[4] "Kukuleganga- wikipedia," [Online]. Available:
https://en.wikipedia.org/wiki/Kukule_Ganga_Dam#Power_station. [Accessed 15
April 2016].
[5] "Wikipedia, the free encyclopedia," [Online]. Available:
https://en.wikipedia.org/wiki/Samanala_Dam. [Accessed 16 April 2016].
[6] CEB, "Annual Report," CEB, 2013.
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