scada implementation in thermal power plant …

SCADA IMPLEMENTATION IN THERMAL POWER PLANT

Prayaskumar Manubhai Patel B.S. in Electronics and Communication Engineering at North Gujarat University, Gujarat, 2007

PROJECT

Submitted in partial satisfaction of the requirements for the degree of

MASTER OF SCIENCE

in

ELECTRICAL AND ELECTRONIC ENGINEERING

at

CALIFORNIA STATE UNIVERSITY, SACRAMENTO

SUMMER 2010

ii


A Project

by

Prayaskumar Manubhai Patel Approved by: __________________________________, Committee Chair John C. Balachandra, Ph.D. __________________________________, Second Reader Fethi Belkhouche, Ph.D. ____________________________ Date

iii

Student: Prayaskumar Manubhai Patel

I certify that this student has met the requirements for format contained in the University format

manual, and that this project is suitable for shelving in the Library and credit is to be awarded for

the Project.

__________________________, Department Chair ___________________ Suresh Vadhva , Ph. D. Date Department of Electrical and Electronic Engineering

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Abstract

of


by

Prayaskumar Manubhai Patel

The thermal power plant uses the water as the primary source to generate the electricity.

Generally, the water contains so many impurities, which can harm the boiler and other

equipments. The dissolved gases in water can cause the corrosion on the boiler and other

equipments. This project uses some additional equipment before the water move to the

boiler. This additional set up removes the all-visible impurities as well as dissolved gases

from the water.

The overall concept of the project is to set up the power plant in such a way that it

will not reduce only the cost but also improve the efficiency of the power plant. The

small electro dialysis unit avoids the extra labor cost for maintenance of the boiler. In

addition, this project uses SCADA system to provide the artificial intelligence. SCADA

system uses various sensors and alarms which can be monitor remotely from the control

center.

, Committee Chair John C. Balachandra, Ph. D. ______________________ Date

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ACKNOWLEDGMENT

Firstly, I thank to God for giving me patience, determination and the ability to complete

this study successfully.

I would like to express my deepest gratitude to Dr. John C Balachandra who allowed me

to work on this project with him. His valuable advice and guidance supported me to

finish this project. I must say without his continuous help, guidance and support, this

project would not have been successfully completed. I also want to give a special thanks

to Dr. Fethi Belkhouche for reviewing my project report.

In addition, my sincere thanks are due to faculty members of Electrical Engineering

department for helping me in finishing my graduation at California State University,

Sacramento.

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TABLE OF CONTENTS

Page

Acknowledgments............................................................................................................... v

List of Figures ................................................................................................................... ix

Chapter

1 INTRODUCTION ......................................................................................................... 1

1.1. What is SCADA? ................................................................................................ 1

1.2. Overview of the Design .................................................................................. …2

1.3. Design Solution ................................................................................................... 3

2 SCADA SYSTEM ......................................................................................................... 4

2.1. SCADA as a System ........................................................................................... 4

2.2. SCADA Applications ......................................................................................... 5

2.3. Human Machine Interface (HMI) ....................................................................... 6

2.4. SCADA Animation. ............................................................................................ 7

2.5. SCADA System Benefits. ................................................................................... 8

3 WORKING OF SCADA SYSTEM. .............................................................................. 9

3.1. Data Acquisitions. ............................................................................................... 9

3.2. Data Communication. ....................................................................................... 10

3.3. Information/Data Presentation .......................................................................... 10

3.4. Monitoring/Control ........................................................................................... 11

3.5. SCADA Communication Protocol. ................................................................... 13

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4 SCADA SYSTEM OF A THERMAL POWER PLANT ............................................. 14

4.1. Functionality of SCADA Based Thermal Power Plant..................................... 14

4.2. Architecture of SCADA Based Thermal Power Plant ...................................... 16

4.3. Application of SADT Method. ......................................................................... 17

5 THERMAL POWER PLANT ....................................................................................... 21

5.1. Introduction ....................................................................................................... 21

5.2. Components of a Thermal Power Plant ............................................................ 22

5.3. Coal Fired Thermal Power Plant. ..................................................................... 23

5.4. Basic Layout of a Thermal Power Plant. .......................................................... 25

5.5. Working of Thermal Power Plant ..................................................................... 27

6 THERMAL POWER PLANT COMPONENTS ........................................................... 30

6.1. Steam Generator ............................................................................................... 30

6.1.1. Boiler Furnace and Steam Drum....................................................................... 30

6.1.2. Super Heater...................................................................................................... 30

6.1.3. Reheater ............................................................................................................ 31

6.1.4. Fuel Preparation System ................................................................................... 31

6.1.5. Air Path ............................................................................................................. 31

6.1.6. Ash Collector .................................................................................................... 31

6.2. Steam Turbine ................................................................................................... 32

6.2.1. Bearing Gear ..................................................................................................... 32

6.2.2. Condenser ......................................................................................................... 32

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6.2.3. Feed Water Heater ............................................................................................ 33

6.2.4. Deaerator ........................................................................................................... 34

7 SIMULATION OF COMPONENTS OF THERMAL POWER PLANT .................... 37

7.1. Fluid Flow Machines ........................................................................................ 37

7.2. Pipe as an Important Part of Heat Exchanger ................................................... 39

7.3. Heat Exchanger. ................................................................................................ 40

7.4. Model of Pipe. ................................................................................................... 41

7.5. Heat Exchanger Model ..................................................................................... 42

8 SCADA MODELING .................................................................................................... 44

8.1. Important Steps for SCADA Modeling ............................................................ 44

8.2. Components of the Plant. .................................................................................. 45

8.2.1. Valves ............................................................................................................... 45

8.2.2. Aeration Tank ................................................................................................... 46

8.2.3. Sensors .............................................................................................................. 47

8.2.4. Mesh .................................................................................................................. 47

8.2.5. Motors ............................................................................................................... 48

8.3. Step by Step Functionality of the Project. ........................................................ 48

8.4. Values for the Components ............................................................................... 49

9 CONCLUSION .............................................................................................................. 55

References ……………………………………………………………………………….56

ix

LIST OF FIGURES

Page

Figure 1 Standard SCADA Animation. .............................................................................. 7

Figure 2 Old Fashion Vs Modern Animation ..................................................................... 8

Figure 3 Schematic Diagram of SCADA System ............................................................. 12

Figure 4 Circuit Diagram of Comparator ......................................................................... 12

Figure 5 Functionality of Thermal Power Plant ............................................................... 15

Figure 6 Architecture of SCADA System ........................................................................ 16

Figure 7 Hierarchical Methodology of SADT Model. ..................................................... 18

Figure 8 A0 level of SADT Model ................................................................................... 19

Figure 9 A1 level of SADT Model. .................................................................................. 19

Figure 10 A2 level of SADT Model ................................................................................. 20

Figure 11 A3 level of SADT Model ................................................................................ 20

Figure 12 General Layout of Thermal Power Plant .......................................................... 22

Figure 13 Basic Layout of Thermal Power Plant. ............................................................ 27

Figure 14 Water Cooled Surface Condenser .................................................................... 32

Figure 15 Feed Water Heater ............................................................................................ 33

Figure 16 Tray Type Deaerator ........................................................................................ 35

Figure 17 Spray Type Deaerator. ...................................................................................... 36

Figure 18 Characteristic of an Ideal Water Pump ............................................................. 37

Figure 19 Characteristic of Centrifugal Water Pump ....................................................... 38

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Figure 20 Pressure Drip in Pipes versus Flow Velocity. .................................................. 39

Figure 21 Heat Transfer Coefficients versus Increasing Flow Velocity .......................... 40

Figure 22 Model of Infinite Small Pipe. ........................................................................... 41

Figure 23 Parellel Tube Heat Exchanger .......................................................................... 42

Figure 24 Model of a Parallel Heat Exchanger. ................................................................ 43

1

Chapter 1

INTRODUCTION

This chapter provides an introduction about the SCADA based system, the

significance of the SCADA implementation and different potential of the design,

application in real time, an overview of design components which are used in design, and

configuration, control and managing the SCADA system to improve the efficiency and

reducing the cost of the design.

1.1. What is SCADA?

SCADA is used for monitoring and controlling of the industrial processes. SCADA

stands for supervisory control and data acquisition. The processes which can control

using SCADA can be industrial, Infrastructural or Public Utilities. SCADA is used

around the world to control all kind of industrial processes [1].

Industrial processes include manufacturing, Production, Developments, and

Fabrication. Infrastructural processes include gas and oil distribution, Electrical power

and water distribution. Public utilities include light rail, airport, bus transit systems,

Shopping malls [1]

SCADA application has two major components.

1. The system or process you want to control/monitor. It can be electrical power

distribution, manufacturing plant, power plant or production plant.

2

2. A group of the intelligent devices which control the system or process. These

devices include sensors and control input/output to monitor and control the system or

processes.

1.2. Overview of the Design

The objective of this project is to implement the SCADA based thermal power plant

which uses minimal of hardware/software interfaces and provide the higher efficiency. It

also provides low cost solution and reducing the number of loses during process flow.

This project focused on generating the electricity using the water, boiler and steam

turbine. SCADA implementation helps to provide higher efficiency as well as monitoring

and controlling of the process parameters like generated power, turbine speed and quality

of the generated power. SCADA implementation provides the higher controllability due

to sensors, valves and meters incorporated within the path of the process flow. The same

project can be also applicable for various other processing flows like water purification,

Oil purification and manufacturing of the products. The goal of the project is to minimize

the unnecessary steps involve during any process flow and provide the higher efficiency

and throughput.

None of the power plant provides 100 percent efficiency due to various loses

incorporated during the process cycle. Losses can be due to physical damage of the

hardware like scratches, splitting or tearing of the components. Hardware components

tearing are also possible due to the high pressure of water and steam. Most of the

3

components need to be replaced after some amount of time or they need maintenance.

1.3 Design Solution

This project provides the various solutions to minimize loses and provide the energy

efficient power plant which cost less and provide the higher efficiency. Here are some of

the techniques.

1. Removing the excessive particles using filters:

Instead of getting water directly from the reservoir it is fed into the tank and keeps

there for a while so heavy particles can be settled down at the bottom of the tank.

Now water is passed through some large filters following by tiny filter holes and

accumulated at the second tank.

2. Removing gases using Electro dialysis techniques:

Electro dialysis is used to filter out the dissolved particles and gases. This step is

essentially required for the removal of dissolved Oxygen. Dissolved oxygen in

boiler can origin serious deterioration damage in steam systems by attaching to

the walls of metal piping and other metallic tools and forming oxides (rust). It

also combines with any dissolved carbon dioxide to form carbonic acid that leads

further corrosion.

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Chapter 2

SCADA SYSTEM

This chapter describes basic applications and uses of SCADA system. This also

covers basic design aspects of the SCADA system. It clearly explains how to select the

particular SCADA system for specific requirements. It also gives details on the

monitoring and control of the Real time systems

2.1 SCADA as a System

SCADA is one kind of application which collects data from the factory through

various sensors and sends this information to the computer system or remote locations.

SCADA is control and management solutions for the most of the industries. SCADA is a

central control system which consists of controllers, Network interfaces, Input/Output,

communication equipments and software. All together SCADA system collects important

information and sends it to the computer or remote locations.

The most important part of the SCADA is remote terminal unit which is also

known as RTU. RTU consist of programmable logic converter which can be set to

specific requirements or it can also allow human intervention during the operation. For

example, in thermal power plan the water flow can be set to specific value or it can be

change according to the requirements. RTU also displays the error or any critical

warnings at control station so user may be aware of the developments. SCADA system

takes the reading of the meters and checks the status of the sensors in a regular interval so

that it requires minimal interference of human. SCADA system made of many data points

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which include monitor points or software/hardware points. SCADA system creates the

log of the all necessary events and save the history for future references.

2.2 SCADA Applications

SCADA is used for all kind of complex system where human interaction is

impractical. SCADA is used in the applications where there are more control factors

difficult to mange with the short time frame [2].

1. Power generation, transmission and distribution

Power stations use SCADA system to monitor the current flow, voltage level,

checking the status of the transmission line and circuit breakers. Also, sometimes it is

used to power off or shutdown particular sections [2].

2. Water distribution and Reservoir system

SCADA is used for municipal water distribution system to monitor the flow of the

water during the distribution. Also, reservoir water level and pressure can be measure

using the SCADA system [2].

3. Public buildings

Electrical heating, cooling system, lighting can be control using the SCADA to

provide automation and power saving during the normal usage of the buildings [2].

4. Transit Systems

SCADA is used for the traffic light signals, detecting out of order status of the

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signals, regulating the power in subways, bus stations and airports.

5. Generators and Turbines

Monitor and control the temperature and flow in heat exchanger unit and heat

recovery unit.

2.3 Human Machine Interface (HMI)

SCADA system uses interface which is known as human machine interface

(HMI). HMI is the place where the information is displayed and monitored to process by

human. The interface provides the controls so human can interface with the system. HMI

provides the access of multiple control units which can be PLC’s (programmable logic

unit) or RTU’s. Usually RTU and PLC is pre program according to the requirements but

monitoring of them is difficult for the users. SCADA system communicates with the

PLC’s throughout the system and provides the information to the user using network

interfaces.

The HMI provides the graphical presentation of the system. For example, it

provides the graphics picture of the pump connected to the tank. User can see the flow of

the water and pressure of the water. Also, User can on/off the supply of the water within

the particular pipes. HMI also provides the multiple displays so user can control more

equipment at a time. The important part of the HMI is an alarm system which is activated

according to the predefined values. For example, the tank water level alarm is set to 80%

and 90% values. If the water level reaches above the 80% the alarm gives normal

warning and if water level reaches 90% the alarm gives critical warnings. According to

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the warning user can control the flow of the water from reservoir to the tank.

SCADA system also uses database to keep record of all the measurements and

particular state of the controllers. Also, it provides the information for troubleshooting of

the system, schematic diagram of particular parts or sensors, detailed graph of the usage

of the particular segments, installation and maintenance of the system

2.4 SCADA Animation

• Standard Animation

SCADA animation consists of different color bars, text, rotating/sliding parts,

level indicator and position of the parts using different colors. Basic animation of

the SCADA system is shown below.

Figure 1 Standard SCADA Animation [3]

• Modern Animation

Some company provides the software which can give the high graphics 3D view

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of the particular parts as well as sharp images.

Figure 2 Old Fashion Vs Modern Animation [3]

2.5 SCADA System Benefits

• Control units have wide range of temperature and ability to operate in rough

situation.

• SCADA system provides on board mathematical and graphical information.

• SACDA system has ability to measure and store the historical information.

• SCADA system is easily expandable. We can add new set of control unit and

sensors according to the requirements.

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Chapter 3

WORKING OF SCADA SYSTEM

The SCADA system mainly performs the following functions [2].

3.1 Data Acquisitions

3.2 Data Communication

3.3 Information/Data Presentation

3.4 Monitoring/Control

These functions are performed by sensors, RTU’s, Master Units and

Communication networks. Sensors are used to collect the important information and

RTU’s uses this information to display the status of the system at the control equipments.

According to the status of the system user can give command to the other system

components. The operations send the important command through the communication

network [2].

3.1 Data Acquisitions

The Real time system consists of thousand of components and sensors. It is very

important to measure the status of the particular components. For example, some sensors

measure the water flow from the reservoir to the tank which is input to the system. Some

sensors measure the valve pressure as the water is release from the reservoir [2].

Some sensors indicate the normal event of the system. For example, in production

environment sensor counts the number of produced product or the number of defected

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products. Some sensors indicate the condition (on/off) of the particular system

components. Furthermore, some sensors provide very critical information which should

give the accurate results. For instance, it is important to measure the temperature of the

system as it can damage the system. Temperature values are predefined in the system so

that it sounds alarm when system reaches above the threshold value.

3.2 Data Communication

Simple electronic control system uses wired network to communicate between

user and devices but in Real time application there are lots of sensors and components

which should be control remotely. It is important to have strong network between all the

components and user. Early, SCADA network used to communicate through radio and

modem [2]. Today, SCADA uses internet as a communication medium. All information

is transmitted through internet using specific protocols. Sensors and relays are not able to

communicate with the network interface so RTU (Remote Telemetry Unit) is needed to

establish the communication between sensors and network interface [2].

The RTU converts the input from the sensors into specific protocol and send it to

the masters. According to the masters feedback RTU received the protocol formatted

command and apply the electrical signal to the relays [2].

3.3 Information/Data Presentation

Normal circuit network have some indicator which can be visible to the operator

but in Real time SCADA system there are thousands of sensors and alarm which are

nearly impossible to handle simultaneously. SCADA system uses Human system

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interface to provide the all information gathered from the various sensors. SCADA

master works as a human interface. It has many different functions. Master collect the

information from the different sensor also process the accumulated information and

provide the necessary suggestion to improve the efficiency as well as indication of the

alarms [2].

3.4 Monitoring/Control

SCADA system provides the different switches and displays at the control center.

Any part of the process can be turned on/off from the control station using these switches.

For example, if the part following the water distribution system broke up or

malfunctioning then water control can be stopped or slowing down directly from the

control station. Mostly, SCADA system is implemented to work automatically without

human intervention but it is also possible to override the automatic control from the

control station [2].

Most of the monitoring and control operations are performed by RTU’s or PLC’s.

As we can see from the figure that SCADA system RTU Reads the flow level and flow

control form the sensors and sends the set points to the PLC’s. PLC1 compared the flow

with the set point and according to that it manages the speed pump. PLC2 observes the

flow and compare it with the set points and according to that it manages the flow.

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Figure 3 Schematic Diagram of SCADA System [1]

Figure 4 Circuit Diagram of Comparator

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3.5 SCADA Communication Protocol

SCADA system uses protocol for communicating between different RTU’s. IEC

(international electrotechnical commission, DNP3 (Distributed network protocol version

3) and modbus are most commonly used protocols [5].

IEC and DNP3 provide more functions and used to handle large amount of data.

Because of the more functionality and ability to handle large amount of data DNP3 is

mostly used around the world [5].

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Chapter 4

SCADA SYSTEM OF A THERMAL POWER PLANT

4.1 Functionality of SCADA Based Thermal Power Plant

Thermal power plant uses steam as a primary requirement to move the wings of

the turbine. After the passing through the turbine this steam is condense in a condenser.

Steam is generated by different type of fuel depends on the availability and requirements.

Different types of thermal power plant are classified according to the type of fuel and the

primary mover in the plant. The functionality of the thermal power plant can be

understood by the following diagram [12].

15

Figure 5 Functionality of Thermal Power Plant [12]

The overall efficiency of the power plant can be measured by the ratio of the

temperature of the steam input and output. Higher efficiency requires the higher pressure

and higher temperature. The over heated steam is rotates the wings of the turbine and

then return back to the MP body and BP body of the turbine [12]

Most of the thermal power plants can automatically operate but it still allows the

access to human intervention to take some critical decision. Most of the power plant have

alert and monitor system which can be easily operated from the control room.

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4.2 Architecture of SCADA Based Thermal Power Plant

The architecture of the SCADA based thermal power plant is shown in the

following figure. The power plant is connected using the network Ethernet. The network

Ethernet allows the file transfer between the different stations. Also, it avoids the burden

of the node bus network [12]. There are three levels in SCADA system: acquisition,

processing and monitoring. The SCADA system is made of different components which

transfer information using the interface [12].

Figure 6 Architecture of SCADA System [12]

I/A: Intelligent / Automation

17

FBM: Field bus modules

FCM: Field bus Communication module

AW: Application work station

WP: work station processor

CP60: control process60

DNBT: Dual Node bus 10 Base –T Interface

4.3 Application of SADT Method

The SADT model can be based on the type of the SCADA system. To model the

system we need to first determine the overall function of the system, divide the system

into different sub systems. The SADT model can be made of different stages for example,

in Thermal power plant the main module is used to check the overall function of the

power plant. This module is then divided into the sub modules. Each sub module has its

own functions [12]. The following figure shows the top down hierarchical methodology

of SADT model [12].

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Figure 7 Hierarchical Methodology of SADT Model [12]

SADT Model can be implemented by actigrams. The most top module is

generally used to monitor the signal of the power plant. Now this top module is divided

into sub modules. This process continues to the last decomposition level. The following

figures show the different level of SADT.

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Figure 8 A0 Level of SADT Model [12]


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21

Chapter 5

THERMAL POWER PLANT

5.1 Introduction

The coal used in the barbeque is also used to generate the steam and through this

steam it can generate the electricity. As the population increases the requirement of the

power also increases. Nuclear power plant is also a solution to this demand but it is not

safe as thermal power plant. Thermal power plant uses water as a primary resource and

water is heated to generate steam. This steam is used to spin the turbine and generate the

electricity. The steam which passed through the turbine is condensed using condenser [7].

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Figure 12 General Layout of Thermal Power Plant [8]

5.2 Components of a Thermal Power Plant

1. cooling tower

2. cooling water pump

3. 3 phase transmission line

4. 3 phase unit transformer

5. Electric Generator

6. low pressure turbine

7. condensate extraction pump

8. condenser

9. intermediate turbine

10. steam governor valve

11. high pressure turbine

12. deaerator

13. feed heater

14. coal conveyor

15. coal hopper

16. pulverized fuel mil

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17. boiler drum

18. ash hopper

19. super heater

20. forced draught fan

21. reheater

22. air intake

23. economizer

24. air preheater

25. precipitator

26. induced draught fan

27. chimney stack

5.3 Coal Fired Thermal Power Plant

More than half of the energy is generated using the coal based thermal power

plant. The basic concept is to produce the electricity from the energy stored in the coal.

The energy stored within the coal is used to generate the electricity and this electricity is

used in industrial, commercial and residential.

How coal fired thermal plant produce electricity?

First the energy conversion takes place in the boiler. The coal is burnt to generate

24

the heat. Carbon in the coal combines with the oxygen and produces the carbon

dioxide.

Next, the thermodynamic process takes place. The heat from the fired coal boils

the water in the boiler and produces the steam. This steam is transferred to the turbines.

This high pressured steam collides with the wings of the turbine at high speed. This will

cause the pressure on the turbine wings and rotates the turbine. This steam is then

condensed and sends back to the boiler and repeats the same process again.

In final stage, rotation of the turbine rotates the generator rotor based on the

principal of electromagnetic induction. These stages also incorporate many different sub

stages and technologies. For example, combustion, heat transfer, thermodynamics,

aerodynamics.

Let’s consider we have a power plant of capacity 500 MW.

• 2 million tons of coal will be required to produce the power

• Approximately 1.6 million meter of air per hour is delivered by air fans.

• The total ash produced from this combustion is 200,000 tons annually

• Gases like carbon dioxide, sulphur dioxide and nitrogen oxide can damage the

atmosphere.

• To condense all the steam it will require 50000 cubic meter per hour of cooling

water

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• Electrical generator produce very large amount of current and heat which can

be condensed by water and hydrogen.

• The boiler produced around 1600 tons per hour of steam at temperature of 550 to

600 degrees.

• The water is returned back to the source with only increase of 3 or 4 degree

centigrade

• The cooling plant requires 400 cubic meters per day for fresh water to compensate

the losses during the whole cycle.

5.4 Basic Layout of a Thermal Power Plant

Thermal power plants are mostly used to generate the electricity. Thermal power

plant releases large amount of green house gases in our atmosphere. The general layout

of the thermal power plant includes the following main components.

• Coal and Ash circuit

Coal and ash circuit is used to supplying the coal to the boiler and collecting the

ash that is produced after burning of the coal. This includes the components used

to transfer and storage of the coal and ash.

• Air and Gas Circuit

Air is the most important factor for combustion of the coal. Hence, it is required

to supply the sufficient amount of air for the combustion of the coal. The

26

exhausted gases used to heat the air before releasing to the environment.

• Feed water and steam circuit

These components are used to supply the generated steam to the turbine and also

for cooling the steam which is passed through the turbine. This steam is

condensed to form the water. This water is used again for the same process.

• Cooling water circuit

This part is used to condense the steam using water. It requires large amount of

water for cooling the heated steam. The water is generally taken from the river or

reservoir.

27

Figure 13 Basic Layout of Thermal Power Plant [9]

5.5 Working of Thermal Power Plant

Thermal power plant uses coal or natural gases to generate the heat which is used

to boil the water. This boiled water generates the steam, which feeds to the turbines. The

turbine is connected to the generator. This generator provides the electricity to the

consumers.

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The following are the steps for the process of generating electricity

1. Water Intake

The water is feed to the boiler for generating the steam. The water is driven from

the river, pond or reservoir. If the water is not pure then it is filtered using various

techniques. Also, this water can be used again and again for the next cycle.

2. Boiler heating

The boiler is heated using the coal or natural gases. The high temperature causes

the water to transform in to the steam. This steam is feed to the next stage for the

generation of electricity.

3. Steam turbine

The steam generated using boiler is feed to the steam turbine. The pressure of the

steam applied on the blades of the turbine. Hence, the wings of the turbine rotate

according to the pressure of the steam.

4. Generator

The generator is normally connected with the turbine and it produces the

electricity. This produced electricity is passed to the consumers using other

circuits.

5. Special mountings

There are some other components like economizer and air pre heater. Economizer

29

uses the heat from the exhausted gases to heat the feed water. An air pre heater

heats the air sent to the combustion to improve the efficiency.

6. Ash Collection Unit

There are many waste material produced during the whole cycle so it is required

to collect all these waste materials and prevent them to go into environment.

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Chapter 6

THERMAL POWER PLANT COMPONENTS

6.1 Steam Generator

The steam generator produce the high quality steam required for the steam

turbine. Steam generator is a one type of large heat exchanger used to thermally connect

the reactor plant and steam plant. A steam generator also contains other components like

economizer, steam drum, furnace and super heater coils. Some times safety valves are

also required to avoid unnecessary boiler stress.

6.1.1 Boiler Furnace and Steam Drum

The water enters into boiler through economizer and from there it passes to the

steam drum. The boiler transfers the energy to the water by using the coal as a fuel. As

the water comes into the boiler it is converted into steam using the heated water walls.

The Generated steam enters into the steam drum and passes through the number of steam

and water separators. This separators and dryers are used to remove the water from the

steam. This whole process is called natural circulation [7].

6.1.2 Super Heater

Some power plant uses super heater which is used to heat the steam beyond the

saturation temperature. After passing the drying equipment inside the drum the steam is

feed to the furnace called super heater. Super heater uses the hot flue gases to provide the

more energy to the steam vapor. This super heated steam is now above the saturation

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temperature and is passed to the turbine [7].

6.1.3 Reheater

Many power plants contain the reheater which is used to provide the more energy

to the steam so it can drive the blades of the turbine. The reheater uses flue gases outside

of the tubes to produce highly energized steam [7].

6.1.4 Fuel Preparation System

Thermal power plant uses natural gas, fuel oil or coal as the fuel. Coal from the

storage is crushed into small particles. This coal is conveyed through the belt and feed to

the coal feed hoppers. Some power station uses fuel to generate the steam. The oil is

stored into the storage tanks and must kept warm to prevent congealing and becoming

unpumpable [7].

6.1.5 Air Path

The combustion unit requires sufficient air for burning of the coal. The draft takes

the air from the atmosphere, warm the air in preheater and feeds the air in furnace wall

using the air nozzles [7].

6.1.6 Ash Collector

The flying ash collected by the electrostatic precipitators or filters. The flying ash

is collected by filters and then transported using the vehicles. They flying ash should be

periodically removed from the hoppers. The bottom ash is collected using the hopper.

This hopper is filled with the water which quenches the ash.

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6.2 Steam Turbine

The steam turbine is the rotating machine which has large and heavy shaft. This

shaft requires supports and need to keep in accurate position. The shaft contains number

of bearings to minimize the friction during the rotation. It also uses lubricant to further

reduce the friction.

6.2.1 Bearing Gear

Bearing gear is used to supply the rotation to the shaft at low speed even after the

unit it stopped. When the unit stops completely then there is a chance for the shaft to

bend if it is remained in one position too long. The reason behind this is the heat inside

the turbine is concentrated at upper portion of the case. This could lead to bending of the

shaft.

6.2.2 Condenser

Figure 14 Water Cooled Surface Condenser [7]

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Condenser is used to convert the steam into water. Condenser is made of tubes

and water flows through the tubes. The steam from the turbines passed over the

condenser tubes. The condensers are also known as heat exchanger. To achieve the

higher efficiency the condenser temperature is kept as low as practical. Air cooled

condensers are used where the supply of water is not enough. The condenser uses same

water again and again from the tank or it can also use one time water directly from river

or lake.

6.2.3 Feed Water Heater

Figure 15 Feed Water Heater [7]

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Feed water heater is used to heat the water which is supplied to the boiler. Feed

water heater used to increase the efficiency. Feed water heater increases the water

temperature gradually which will reduce the predictable irreversibility incorporated with

water. The steam extracted from the stages of the cycle is used as energy to heat the feed

water. There are two types of feed water heaters. In open feed water heater the extracted

steam is in direct contact with feed water. On the other hand, closed feed water heater

passes the water through the tubes and is heated by extracted steam. Many power plant

have more than one feed water heaters and it can be open or closed depend on the type of

the power plant. The overall purpose of the feed water heater is to increase the system

efficiency.

6.2.4 Deaerator

Deaerator is generally used to remove the air and gases from the water. The

dissolve gases can harm the plant components by attaching to the walls. Water can

combines with the carbon dioxide and produce the carbonic acid which in turn causes

further corrosion. There are two types of deaerator. The deaerator can be horizontal or

vertical depend on the manufacture.

• Tray type deaerator

The schematic diagram of the tray type deaerator is shown in the figure. It has

vertical deaeration section on the top of the horizontal boiler. The water feeds from the

vertical section and flows downwards. Now the low pressure steam flow upward through

the hole. The steam exits via the hole at the top of the section. The vent generally uses

35

valve to allow steam to escape.

Figure 16 Tray Type Deaerator

• Spray type deaerator

The spray type deaerator is shown in the figure. It is horizontal vessel which has

preheating section and deaeration section. The feed water is feed to the section E and

heated by the steam. The purpose of this section is to heat the water to its saturation

temperature. The preheated water now flows to section F. It is deaerated by the steam.

The gases striped out of the water via hole at the top of the section.

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Figure 17 Spray Type Deaerator

37

Chapter 7

SIMULATION OF COMPONENTS OF THERMAL POWER PLANT

7.1 Fluid Flow Machines

In thermal power plant, it is required to transmit the water or oil between various

components of the power plant. To provide the constant flow of the fluid pumps are

required. Sometimes fluid can be flow without the pump based on the density differences

[11].

Figure 18 Characteristic of an Ideal Water Pump [11]

38

Figure 19 Characteristic of Centrifugal Water Pump [11]

The ideal pump has infinite number of shovels. Pumps establish the pressure,

velocity or fluid flow. The pump characteristic fully depends on the shape of the pump

therefore pump characteristic varies based on the type of pump. The above figure shows

the characteristic of the ideal water pump and characteristic of centrifugal water pump

with losses [11].

Pumps cause the losses due to friction, water impacts and other dynamic effects.

The following are the losses incorporated with realistic pumps [11].

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• Reducing the energy

• Hydraulic losses of shovel channels

• Impact losses

• Friction losses of impeller wheel

7.2 Pipe as an Important Part of Heat Exchanger

A pipe is the most common and important part of the fluid flow machines. The

velocity of the water depends on the roughness and cross section of the pipe. The higher

roughness decreases the velocity of the water. The following figure shows the pressure

drop in pipes versus flow velocity [11].

Figure 20 Pressure Drip in Pipes versus Flow Velocity [11]

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7.3 Heat Exchanger

Heat transfer takes place between the two materials and it is transferred based on

the temperature of these two materials. Heat transfer can be caused by convection or it

can be cause by diffusion. In standing water heat transfer takes place according to

diffusion. In thermal power plant water flows through the pipes and heat transfer takes

place between the water and pipes. It is required to define the heat transfer model for the

flowing water and pipe walls. The following figure shows the heat transfer coefficient

verses increasing flow velocity [11].

Figure 21 Heat Transfer Coefficients versus Increasing Flow Velocity [11]

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7.4 Model of Pipe

Different types of model represent the different behavior and all different types of

model require different equations. Let’s consider the infinite small pipe segment. The

velocity and pressure drop across the pipe exist due to the frictions across the pipe walls

[11]. The following figure shows the model of infinite small pipe segment. The red line

in the figure shows that the heat transfer in the axial direction is caused by diffusion [11].

Figure 22 Model of Infinite Small Pipe

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7.5 Heat Exchanger Model

Heat exchange generally takes place from high temperature material to low

temperature material. The following figure shows the parallel heat exchanger model. In

this model the fluid A has higher temperature than fluid B so heat exchange will take

place from fluid A to fluid B. Also, we need to consider the heat exchange between the

pipes in horizontal directions [11].

Figure 23Parallel Tube Heat Exchanger [11]

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Figure 24 Model of a Parallel Heat Exchanger [11]

44

Chapter 8

SCADA MODELING

There are few steps which is necessary for proper implementation of the power plant.

8.1 Important Steps for SCADA Modeling

• Screening

The water from the reservoir, river or lake is not 100 percent pure. Water includes

impurities like rocks, sand, wood and many other particles which need to remove

before using this water for the plant. These materials are sent to landfill [10]

• Pumping

Mostly waste water treatment plants are located below the level of the power

plant. So it is required to send this water to the plant using motors. The plant is

mostly above the level of the river or lake therefore the water needs to pumped up

to the reservoir tank [10].

• Aerating

The water treatment plant shake up the mess and expose it to air. This step is

necessary to remove dissolved gases from the water. Water is passed through the

series of tanks.

First tank feeds the air into the water. Due to organic matter decays, it uses up

oxygen. Bubble passed through the oxygen allows the organic particles to settle.

45

• Removing sludge & Scum

Heavy particles from the water are settled down at the bottom of the tank and

these particles are removed in a step called thickening and then the sludge is

processed in large tank known as digesters [10].

Also, some impurities are light weight. For example, oil, plastic and grease which

can easily float on the surface of the water. These impurities are removed by slow

moving rakes. Some plant also uses filtration in sewage treatment. Water is

passed through the sand which can remove the bacteria, unpleasant odors and

reduces the amount of iron. Sometime water is also passed through the carbon

particles to remove organic particles [10].

This filtered water is still have some gases like oxygen which forms oxides .These

oxides rust and cracks the boilers along with the time so whole boiler system

needs to be replaced after some period of time. This can lead to very high amount

of cost to the company. To avoid this extra cost this water send to the electro

dialysis unit where the gases are removed using some sort of techniques.

8.2 Components of the Plant

8.2.1 Valves

A valve is used to control the flow of the fluid or water. It can be operated

manually or automatically. A valve can be operated manually using wheel, paddle or

handle. An automatic valve operates based on the pressure changes. The Change in the

46

pressure operates the piston and activates the valve. Also, some highly controlled

system uses actuator for controlling the valve. Depending on the controlled input valve

can be positioned accurately according to the requirement.

We have used two types of valve in our project

1. One port valves

One port valves used to allow or obstruct the flow of the fluid, water or

gases. It can allow fluid to flow along the pipes or I can stop moving the fluid.

2. Two port valves

Two port valves are also known as regulating valves because they can be

open, close or partially open. Some valves are designed to regulate the certain

amount of flow.

Here are some operations of the valves

• Control : force or flow speed

• closing at over speed run

• over pressure prevention

• back flow protection

• On/Off operation

8.2.2 Aeration Tank

Aeration is used to remove the iron, manganese and other gases. The water is

47

processed in such way that It can be in more contact with air. Aeration can be done

naturally or using mechanical devices. In natural treatment water flows from the

mountain rocks to provide the more contact with air.

The aeration is used to remove the iron, volatile organic compounds and organic

material.

8.2.3 Sensors

We have used the sensors for the requirements shown below

• measure the water height

• measure the pressure

• measure the temperature

• Measure the flow speed

These sensors directly give output to the control station or it can supply the

information to the next stage. Also, sensors can be analog or digital depend on the

plant design.

8.2.4 Mesh

Mesh is generally used for the following requirements

• Removal of large particles going into the motor

• Removal of the plants , rocks or dead body particles

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8.2.5 Motors

Motors are used to supply the water from one stage to the next stage. For

example, Water needs to be transferred from mesh tank to the nest tank. These heavy

duty motors needs proper supervision to avoid any mishap.

8.3 Step by Step Functionality of the Project

First step of the power plant is to select the proper source of the water. The water

should be easily available. The plant should be near the river or lake so it requires less

effort to move water to the plant. Also, water should be continuously available to gain

more advantage out of the plant.

Next step is the proper storage of the water. Water can be stored in a tank or

reservoir. The water is kept for some amount of time at this stage to settle down most off

the impurities.

Now the water is moved to the tank using motors and valves. The water is also

kept here for some amount of time to remove small particle present in the water. These

tanks have some set of sensors. These sensors are used to control the flow of incoming

water. For example, if the amount of water in the tank is high then higher sensor

deactivates the valve which in turn stops the water flowing into the tank. If the water in

the tank is too low then lower sensor activates the valve and allows the water to flow into

the tank.

Then next step is to remove the impurities from the water. This step is required to

49

remove the big particles which escape from the initial tank. These particles can clog in

pipe or it can damage the motor in next stage. The mesh generally has two stages. First

stage is used to remove the large particles and second stage is used to remove the smaller

particles.

Motors are used to flow water coming from the mesh. Motors send this water to

the next tank which is used for removal of the sludge. This tank has two mode of

operation. During normal mode of operation sludge is screened from the tank by an outlet

at the bottom of the tank. During self cleaning mode the incoming and outgoing of the

water is shut down and the water inside the tank is moved with full speed to remove the

sludge which can be clog over the wall of the tank.

This water is now sent to the scum removal tank. This tank also has two modes of

operation. In normal mode, the scum is screened from the tank by an outlet at the bottom.

This water is now sent to the electro dialysis unit using motors. In self cleaning mode, the

normal supply of water is shutdown and another high speed supply of water is fed into

the tank. The water being supplied is mixed with some chemicals to kill the micro

organism in the tank.

The water coming out from the scum tank is mostly free of any visible impurities.

But this water still need electro dialysis process to remove the gases dissolved in the

water. These gases can damage the boiler parts along the period of time.

8.4 Values for the Components

We used various values for the components and animated the components using

50

the SCADA software. We have also setup the alarms for the critical and warning

conditions. The values for the different components are shown below

• Valves

We used two types of valves. The first valve is normal valve which is used for

one way flow control. This valve controls the input from the reservoir to the tank.

This valve has feedback system and works on the feed back of the sensor R1. This

valve is also used to control the water flow from the electro dialysis tank to the

boiler. This valve works based on the feedback of the valve v3.

Values for the valve V1 and V4

Name: V1

Description: Normal valve

High alarm: 8000

Low alarm: 500

Scan Interval: 1000 ms

Data Logging: > 9 percent

Name: V4

Description: Normal Valve

High alarm: 10000

Low alarm: 1000

51

Scan interval: 1500 ms

Data logging: > 4 percent

The other type of valve is three way control valve. It is used control the flow from

the motor M1 to filter tank. This valve is control by the feedback of motor M1

and M2. The second three way valve is used for the same purpose but the input

depends on the valve V4

Name: V2

Description: Three way valve

High alarm: 10000

Low alarm: 1000


Data logging: > 3percent

Name: V3

Description: Three way valve

High alarm: 10500

Low alarm: 1500



52

• Motors

The motors in the projects are used to pump the water to the next stage. The first

motor work based on the feedback of the sensor R2.

Name: M1

Description: Heavy duty motor

High alarm: 100

Low alarm: 15



Base interval: 20

Name: M2

Description: Pump motor

High alarm: 200

Low alarm: 10



Base interval: 10

• Sensors

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The sensors are used to measure the water level in tank. There are two sensors

one is high sensor and other is low sensor. These sensors sends the data to control

the valve V1 and motor M1

Name: R1

Description: level sensor

High alarm: 9000

Low alarm: 3000



Base interval: 25

Name: R2


High alarm: 10000

Low alarm: 2500



Base interval: 35

• Tanks

54

There are two sensors in the tank to measure the level of the water and the

values of these sensors are shown below

Name: P1 or P2 or P1’ or P2’


High alarm: 9000

Low alarm: 2000



55

Chapter 9

CONCLUSION

The overall ideal of the project is to develop the future power plant in such a way that it

can not only reduce the cost of the plant but also increase the efficiency. The small

additional electro dialysis module in the plant removes the dissolved gases which can

cause the corrosion of the components. This module can avoid the extra labor cost for the

maintenance of the boiler and other components. It also saves time for installing new

components and repairing of the broken components.

In a nutshell, this project helps to build a power plant which not only provide the low cost

solution but also gives higher efficiency.

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REFERENCES

[1] SCADA Discussion

http://en.wikipedia.org/wiki/SCADA

[2] DPS Telecom version 1.2 released April 1 2008

www.dpstelecom.com

[3] http://www.integraxor.com pioneering web SCADA

[4] Sandia National Laboratories

http://www.sandia.gov/scada

[5] International system research laboratory “Technical Report TR-ISRL-04-01”

[6] Products for SCADA automated monitoring and control from CAMPBELL

SCIENTIFIC

http://www.campbellsci.com/scada

[7] Thermal power station

http://en.wikipedia.org/wiki/Thermal_power_station

[8] Modern Power Station Practice, vol 1: Planning & Layout; vol 2: Boilers, Fuel &

Ash-handling plant; vol 3: Turbines & Auxiliary Equipment, Oxford: Pergamon. ISBN 0-

08-016436-6.

[9] Power Plant Layout: Arora, S.C. & Domkundwar, S. (1993) A Course in Power Plant

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Engineering. Delhi: Dhanpat Rai & Sons

[10] Waste water treatment plant

http://ga.water.usgs.gov/edu/wwvisit.html

[11] Simulation of components of a thermal power plant

Arsenal Research Giefinggasse 2 1210 vienna , Austria

http://www.modelica.org/events/modelica2006/Proceedings/sessions/Session2a1.pdf

[12] SCADA system of a thermal Power plant volume 9, November 2, 2009

U.R: Analysis and command of system (ACS), ENIT

http://www.aece.ro/archive/2009/2/2009_2_14.pdf?zoom_highlightsub=optimal+design

scada implementation in thermal power plant …

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