POWER PLANT ENGINEERING

POWER PLANT ENGINEERING

$R33UYAMBAZHAHAN M.E., Ph.D. (IITM) Principal, S.A. Engineering College Avadi-Poonamallee High Road, Veeraraghavapuram, Thiruverkadu Post Chennai, Tamilnadu

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Preface Several books on “Power Plant Engineering” are available in the market today. But the buyers must be smart enough to know which book to purchase. The first edition of the book comprising five units namely Thermal Power Plants, Hydroelectric Power Plants, Nuclear Power Plants, Gas and Diesel Power Plants, and NOn-Conventional Power Generation. It is assured that this book will satisfy the need for why it is bought and also serves as a good textbook for both students and faculties. All kinds of suggestions and constructive criticisms are earnestly solicited for enhancements. I dedicate this book to the !LMIGHTYfor this opportunity. This book is designed by profoundly comprehending the needs of emerging Electrical and Electronics Engineers and as per the syllabus of fourth semester course h%%0OWER 0LANT %NGINEERINGv prescribed by Anna University, Chennai. This book is prepared in a very systematic and self-explanatory approach and the contents are presented in an elegant, comprehensive and lucid fashion with neat diagrams wherever required. The contents of the book are made available in such a way that even the beginners of the subject can understand the concepts of Power Plant Engineering and various power plants from the scrap. The content of the book is sectioned into five units namely Thermal Power Plant, Hydroelectric Power Plants, Nuclear Power Plants, Gas and Diesel Power Plants, and Non-Conventional Power Generation. Particularly topics such as boilers, turbines, condensers, pumps, Hydroelectric Power Plants nuclear Power Plants, gas and Diesel Power Plants, various non-conventional power generation techniques are elaborately dealt. All the units are provided with ample of review questions and solved problems. This book will surely satisfy the students in preparing for the University examinations and achieving prolific results and also it will quench the thirst of success in preparing other competitive examinations. ˆ$R33UYAMBAZHAHAN

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Contents Preface



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4HERMAL0OWER0LANTS

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1.1 1.2 1.3

Introduction—Power Plant Engineering ............................................................................... 1 Classification of Power Plants ................................................................................................ 1 Sources of Energy .................................................................................................................... 1 1.3.1 Conventional Sources of Energy ............................................................................. 1 1.3.2 Non-Conventional Sources of Energy .................................................................... 2 1.3.3 Comparison of Sources of Energy ........................................................................... 4 1.4 History of Thermodynamics ................................................................................................... 4 1.4.1 Temperature and Heat ............................................................................................ 5 1.4.2 Laws of Thermodynamics ....................................................................................... 7 1.4.3 Thermodynamic Processes ...................................................................................... 9 1.4.4 Thermodynamic Cycles ......................................................................................... 10 1.5 Steam or Thermal Power Plant ............................................................................................ 16 1.6 Major Components of Thermal (Steam) Power Plant ........................................................ 18 1.6.1 Boiler ...................................................................................................................... 18 1.6.2 Turbines ................................................................................................................. 28 1.6.3 Condensers ............................................................................................................. 33 1.6.4 Pumps ..................................................................................................................... 40 1.7 Pulverised Coal Burners ....................................................................................................... 45 1.8 Principle of Fluidised Bed Combustion (FBC) System ...................................................... 49 1.9 Coal Handling Systems ......................................................................................................... 56 1.10 Ash Handling System ........................................................................................................... 62 1.11 Forced Draught ...................................................................................................................... 67 1.12 Superheaters .......................................................................................................................... 69 1.13 Regenerator ........................................................................................................................... 75 1.14 Dearearators (Air Preheaters) ............................................................................................. 75 1.15 Economizer ............................................................................................................................. 77 1.16 Cooling Towers ...................................................................................................................... 78 1.17 Selection of Steam Power Station ........................................................................................ 80 Review Questions .............................................................................................................................. 81

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( viii )



(YDROELECTRIC0OWER0LANT

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2.1 Introduction ........................................................................................................................... 85 2.2 Classifications ........................................................................................................................ 85 2.3 Layout of Hydroelectric Power Plant ................................................................................... 86 2.4 Dams ....................................................................................................................................... 88 2.5 Selection of Water Turbines ................................................................................................. 88 2.6 Factors to be Considered While Selecting the Site for Hydroelectric Power Plant ......... 90 2.7 Pumped-Storage Plants ........................................................................................................ 90 2.8 Mini Hydro Plants ................................................................................................................. 91 2.9 Micro Hydro Plant ................................................................................................................. 92 2.10 Pumped Storage Hydroelectric Power Plants in India ...................................................... 93 Review Questions .............................................................................................................................. 93



.UCLEAR0OWER0LANT

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3.1 Principles of Nuclear Energy ............................................................................................... 95 3.2 Elements and Atoms ............................................................................................................. 95 3.3 Radioactivity .......................................................................................................................... 96 3.4 Biological Effects of Radiation ............................................................................................. 97 3.5 Radioactive Decay ................................................................................................................. 97 3.6 Nuclear Life Cycle ............................................................................................................... 101 3.7 Nuclear Energy—Fission and Fusion ................................................................................ 103 3.8 Uranium-235 Chain Reaction ............................................................................................ 106 3.9 Use of Water for Cooling ..................................................................................................... 108 3.10 Nuclear Power Plant Reactors ........................................................................................... 109 3.11 Types of Nuclear Reactions ................................................................................................ 117 3.12 Outside a Nuclear Power Plant .......................................................................................... 118 3.13 The Significant Problems with Nuclear Power Plants ..................................................... 118 3.14 Nuclear Power Plants - Safety ........................................................................................... 118 3.15 Working Principle of Nuclear Power Plant ....................................................................... 119 3.16 General Components of Nuclear Reactor .......................................................................... 121 3.17 Merits and Demerits of Nuclear Power Plant ................................................................... 124 3.18 Nuclear Power Plants in India ........................................................................................... 124 Review Questions ............................................................................................................................ 125



'AS0OWER0LANT 4.1

4.2 4.3

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Gas Power Plant .................................................................................................................. 127 4.1.1 Introduction .......................................................................................................... 127 4.1.2 Classification of Gas Turbines ............................................................................ 127 4.1.3 Closed Cycle Gas Turbine Power Plant ............................................................. 127 4.1.4 Open Cycle Gas Turbine Power Plant ............................................................... 129 4.1.5 Gas Turbine Plant with Intercooling ................................................................. 130 4.1.6. Gas Turbine Plant with Reheating .................................................................... 130 4.1.7 Gas Turbine Plant with Regeneration ............................................................... 132 4.1.8 Merits and Demerits of Gas Power Plant .......................................................... 134 4.1.9 Solved Problems ................................................................................................... 134 Diesel Engine Power Plant ................................................................................................. 137 Fuel Supply System in Diesel Engine ............................................................................... 138

( ix ) 4.4 Types of Diesel Power plants ............................................................................................. 140 4.5 Working Principle of Diesel Power Plant .......................................................................... 141 4.6 Merits and Demerits of Diesel Power Plant ...................................................................... 142 4.7 Application of Diesel Power Plant ..................................................................................... 142 4.8 Comparison of Power Plants .............................................................................................. 143 Review Questions ............................................................................................................................ 144



.ON #ONVENTIONAL0OWER'ENERATING3YSTEMS

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5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11

Solar Power Plant ............................................................................................................... 146 Wind Power Generation ...................................................................................................... 150 Tidal Power Generation ...................................................................................................... 155 Geothermal Power Plant .................................................................................................... 156 Ocean Thermal Energy Conversion (OTEC) ..................................................................... 159 Biogas Generation ............................................................................................................... 163 Fuel Cells ............................................................................................................................. 168 MHD Power Generation ..................................................................................................... 170 Typical Configuration of Thermoelectric Power Generation System .......................... 173 Thermionic Power Generation ........................................................................................... 181 Solar Inverter ...................................................................................................................... 183 5.11.1 How an Inverter Works ....................................................................................... 183 5.12 Lighting Arrester ................................................................................................................ 186 Review Questions ............................................................................................................................ 188

5NIVERSITY1UESTION0APERS

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)NDEX

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1 

Thermal Power Plants

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In the modern scenario, the need for electricity is increasing very rapidly. Electric power is considered as the heart of any industry. Electricity is used in our day-to-day life for lighting, heating, lifting, and cooking and so on. Therefore, it is necessary to produce electricity in large scale and also economically. The large scale power production could be achieved only by means of suitable power producing units like power plants. The most commonly used power plants are steam/thermal, Gas, Diesel, Hydroelectric and nuclear power plants. The main aspects consider while constructing or designing a power plant is the selection of proper location and appropriate equipments for the plant such that maximum output is achieved. The generated power must also be cost effective, reliable and fairly uninterrupted.



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Bulk electric power is generated by special plants known as generating stations or power plants. A generating station consists of a prime mover coupled to an alternator to produce electric power. The prime mover converts different energy forms like kinetic energy, potential energy, chemical energy, into mechanical energy. The alternator converts the mechanical energy to electrical energy. Depending upon the energies or input converted by prime mover into mechanical energy, the power plants are classified as follows: 1. Steam power plants 2. Hydroelectric power plants 3. Diesel power plants 4. Nuclear power plants.



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The energy sources can be classified as: • Conventional energy sources or Non-renewable energy sources • Non-conventional energy sources or Renewable energy sources

 &RQYHQWLRQDO6RXUFHVRI(QHUJ\ The conventional resources are finite and exhaustible. Once consumed, these sources cannot be replaced by others. Examples are coal, timber, petroleum, lignite, natural gas, fossil fuels, nuclear fuels etc. 1

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POWER PLANT ENGINEERING

The examples for conventional sources of energy are: (i) Fossil fuel energy (ii) Nuclear energy (iii) Hydro energy Fossil Fuel Energy Fossil fuel is an invaluable source of energy produced due to chemical changes taking place in the absence of oxygen in plants and animals that have been buried deep in the earth’s crust for many million years. Fossil fuels like coal, petroleum and natural gas are formed in this manner. These are conventional sources of energy. For example, energy from, Petroleum, natural gas, coal, nuclear energy, etc. Nuclear Energy Nuclear energy is obtained by fission of nuclear material. Uranium is a fairly common element in earth’s crust. Naturally found uranium contains 0.72% of uranium 235 (U-235) by mass rest being Uranium 238 (U-238) and small amount of isotopes. Isotopes are atoms of same element having different atomic weights. Plutonium and thorium are another alternate fuel for creating nuclear energy. Hydro Energy It is the energy possessed by the water. The potential energy of water stored in a reservoir at high level is converted into high kinetic energy water by passing to the turbine through the nozzles to produce mechanical energy. Then the mechanical energy is converted into electrical energy by coupling turbine with generator. Thus the hydro energy is obtained for producing electricity. The conventional power plants are producing electricity using conventional energy



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The non-conventional sources are being continuously produced in nature and are not exhaustible. Examples are wood, geothermal energy, wind energy, tidal energy, nuclear fusion, gobar gas, biomass, solar energy etc. The examples for non-conventional sources of energy are: (i) Solar energy (ii) Wind energy (iii) Geothermal energy (iv) Ocean energy such as tidal energy, wave energy (v) Biomass energy such as gobar gas. It is evident that all energy resources based on fossil fuels has limitations in availability and will soon exhaust. Hence the long-term option for energy supply lies only with nonconventional energy sources. The non-conventional power plants are producing electricity using non-conventional energy. Renewable Energy Renewable energy is energy which is generated from natural sources i.e., sun, wind, rain, tides and can be generated again and again as and when required. They are available in plenty and by far most the cleanest sources of energy available on this planet. For example, Energy that we receive from the sun can be used to generate electricity. Similarly, energy from wind, geothermal, biomass from plants, tides can be used this form of energy to another form.

THERMAL POWER PLANTS

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Advantages • The sun, wind, geothermal, ocean energy are available in the abundant quantity and free to use. • The non-renewable sources of energy that we are using are limited and are bound to expire one day. • Renewable sources have low carbon emissions, therefore they are considered as green and environment friendly. • Renewable helps in stimulating the economy and creating job opportunities. The money that is used to build these plants can provide jobs to thousands to lakhs of people. • You don’t have to rely on any third country for the supply of renewable sources as in case of non-renewable sources. • Renewable sources can cost less than consuming the local electrical supply. In the long-run, the prices of electricity are expected to soar since they are based on the prices of crude oil, so renewable sources can cut your electricity bills. • Various tax incentives in the form of tax waivers, credit deductions are available for individuals and businesses who want to go green. Disadvantages • It is not easy to set up a plant as the initial costs are quite steep. • Solar energy can be used during the daytime and not during night or rainy season. • Geothermal energy which can be used to generate electricity has side effects too. It can bring toxic chemicals beneath the earth surface onto the top and can create environmental changes. • Hydroelectric provide pure form of energy but building dams across the river which is quite expensive can affect natural flow and affect wildlife. • To use wind energy, you have to rely on strong winds therefore you have to choose suitable site to operate them. Also, they can affect bird population as they are quite high. Non-Renewable Energy Renewable energy is energy which is taken from the sources that are available on the earth in limited quantity and will vanish fifty–sixty years from now. Non-renewable sources are not environmental friendly and can have serious affect on our health. They are called non-renewable because they can be re-generated within a short span of time. Non-renewable sources exist in the form of fossil fuels, natural gas, oil and coal. Advantages • Non-renewable sources are cheap and easy to use. It can easily fill up in car tank and power the motor vehicle. • It can use small amount of nuclear energy to produce large amount of power. • Non-renewable have little or no competition at all. For example, in a battery driven car, battery gets discharged then it won’t be able to charge in the middle of the road rather it is easy to find a gas pumping station. • It is very cheap when converting from one type of energy to another. Disadvantages • Non-renewable sources will expire some day and we have to us our endangered resources to create more non-renewable sources of energy.

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POWER PLANT ENGINEERING

• The speed at which such resources are being utilized can have serious environmental changes. • Non-renewable sources release toxic gases in the air when burnt which are the major cause for global warming. • Since these sources are going to expire soon, prices of these sources are soaring day by day.



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Sl. No.

Renewable energy sources

Non-renewable energy sources

1.

They don’t cause pollution to atmosphere.

They cause pollution to atmosphere.

2.

Their efficiency is comparatively less.

Their efficiency is comparatively high.

3.

They are available at low intensities.

They are available at high intensities.

4.

Their initial cost is comparatively less.

Their initial cost is comparatively high.

5.

Their running cost is less.

Their running cost is more.



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