Rajalakshmi Engineering College, Thandalam.Department of Mechanical Engineering

Branch : CIRCUIT BRANCHESSem./Year : II SEM / I YEARSubject code : ME2151Subject Name : BASIC CIVIL AND MECHANICAL ENGINEERING

Staff In-Charges : V.Vasugi / R.Shanthi

NOTES OF LESSON

Unit III INTRODUCTION TO POWER PLANTS & BOILERS

1. Subject introduction & Overview

Introduction to the subject, ‘Power Plant Engineering’

Power plant is an assembly of equipments that generates and delivers electrical energy by

using the available energy.

Overview of the lesson plan

Overview of the question pattern

2. Layout of Steam Power Plant

Working principle of steam power plant

Water is converted into steam which expands in turbine to produce mechanical power

which in turn operates the generator, thus producing electrical energy

Essential components

Boiler, turbine, condenser, feed water pump, boiler mountings and accessories, Fuel and

Ash handling systems

Advantages of steam power plant

Can be located nearer to load center – hence less transmission losses

Construction & commissioning requires less time than hydel

Power generation does not depend on natural phenomena

Fuel used is cheap

Disadvantages of steam power plant

Fossil fuel may be exhausted in future

Efficiency decreases with time

Air pollution problems

Transportation of fuel and ash disposal

Cost of power generation is high

Cannot be used as peak load plant

3. Layout of Hydel Power Plant

Working principle of hydro-electric power plant

Potential energy of water stored at high elevations converted into mechanical energy in

hydraulic turbines which in turn operates the generator, thus producing electrical energy

Essential components of hydel power plant

Catchment area

Water reservoir

Dam- Storage dams,

Diversion dams

Detention dams

Overflow dams

Non-overflow dams

Masonry dams

Fill dams

Trash rack

Fore bay

Surge Tank

Penstock

Spillway

Water turbine

Draft tube

Advantages of hydel power plant

Operating cost and running cost is less than thermal plant

Water is renewable source of energy and free of cost

No problem of fuel and has handling, no pollution

Efficiency does not change with age

Quick start-up and stoppage

Disadvantages of hydel power plant

High capital cost

Site selected is usually away from the load center

Availability of water depends on nature

Construction and commissioning time is high

4. Layout of Diesel & MHD Power Plants

Working principle of diesel power plant

Diesel as fuel

Similar to steam power plant except that the turbine is absent and the generator is directly

coupled with the engine shaft

Essential components of diesel power plant

Diesel engine

Air intake system

Exhaust system

Fuel supply system

Engine starting system

Lubricating system

Engine cooling system

Governing system

Advantages of diesel power plant

Higher thermal efficiency than thermal plant

Wide range of fuels can be used

Easy fuel handling

Simple layout, easy to install

Quick to respond to load variations

Initial investment is less than other plants

Disadvantages of diesel power plant

Diesel cost is high

Does not work satisfactorily under continuous overload conditions

Noise pollution

Maintenance cost is high

Capacity limited to 50 MW

Life less than steam power plant

Field of applications of diesel power plant

Industries of small power requirement

Peak load plants in combination with other power plants

Mobile power plants- transporting systems- rail road, ships, automobiles and air crafts

Stand by power plants- emergency services

Frequent power cut areas

Central power stations

Principle of MHD power generation

Based on faradays law of electromagnetic induction

Simple magneto hydro dynamic power plant

Open cycle & Closed cycle MHD plants

Advantages of MHD plants

Thermal efficiency is high compared to steam plant

Large amount of power generation is possible

Reduced energy losses due to direct conversion

Absence of moving parts – so less maintenance cost

Pollution less in open cycle and nil in closed cycle

Disadvantages of MHD plants

High frictional losses due to movement of gases

Large magnet is required

Erosion of exposed surfaces due to carry away ashes

5. Layout of Nuclear Power Plant

Nuclear fission and chain reaction

Nuclear fusion

Nuclear fission

Controlled and Uncontroled chain reactions

Difference between fusion and fission reactions

Working principle of nuclear power plant

Energy released by the split-up of nucleus into two or more smaller nuclei is used to

generate steam and subsequently electrical energy

Essential components of nuclear power plant

Nuclear reactors

Reactor core

Moderator

Control rods

Reflector

Thermal shielding

Coolant

Biological radiation shield

Advantages of nuclear power plant

Water is cheap and multipurpose usage

Reactor is more compact and higher power-density ratio

Steam is free from contamination

Fuel is used efficiently

Disadvantages of nuclear power plant

High primary loop pressure is required and leak proof vessel

High capital cost, expensive preparation of fuel element

Poor thermal efficiency due to secondary circuit

6. Layout of Gas Turbine Power Plant

Working principle of gas turbine power plant

Essential components of gas turbine power plant

Advantages & Disadvantages of gas turbine power plant

7. Combined Power Cycles

Working principle of combined power cycles

Advantages of combined power cycles

8. Comparison and Selection, Load Duration Curves

Nuclear power plant Vs Thermal power plant

Nuclear power plant is more economical

Less man power required for nuclear power plant

Less space required for nuclear power plant

Capital cost, Operating cost are less for nuclear power plant

Cost for waste disposal less in nuclear plant

Maintenance cost is less for thermal plant

Gas turbine power plant Vs Thermal power plant

Ash disposal totally nil in gas turbine plant

Less space required and compact in size for gas turbine plant

Gas turbine plant located near by load center

Thermal power plant located near by availability of water

Gas turbine plant desirable for peak load

Thermal plant desirable for base load

Gas turbine plant is more economical for operating conditions below load factor

Gas turbine plant can be brought into peak load quickly

Gas turbine power plant Vs Diesel power plant

Maintenance cost & fuel cost is less for gas turbine plant

Initial cost is low and less space required for gas turbine plant

Gas turbine plant has poor part load efficiency against diesel plant

Diesel power plant is comparatively quick to respond to load variations

Comparison of steam power plant with hydel power plant

Comparison of thermal power plant with diesel power plant

Selection of power plants, factors to be considered

Load curves & Load duration curves

Load curves

Graphical representation –load(kW) Vs time (hours)

Daily load curve

Monthly load curve

Annual load curve

Load duration curve

Rearrangement of daily load curve in descending order of magnitude

9. Steam Boilers and Cycles

Steam boilers & boiler cycles

Rankine cycle

Reheat cycle

Regenerative cycle

10. High Pressure and Super Critical Boilers

Modern features & Advantages of high pressure boilers

Lamont boiler

Loeffler boiler

Benson boiler

Velox boiler

Super critical boilers

11. Fluidised Bed Boilers

Fluidized bed combustion (FBC) systems

Advantages of FBC syatems

Classification of fluidized bed boilers

Atmospheric fluidized bed combustors (AFBC)

Atmospheric bubbling fluidized bed combustors

Atmospheric circulating fluidized bed combustors

Pressurised fluidized bed combustors (PFBC)

STEAM POWER PLANT

12. Fuel and Ash Handling

Out Plant Handling

Inplant Handling

Coal delivery

Unloading

Coal preparation

Coal transfer

Outdoor storage

Covered storage

Weighing and Measuring

Ash handling

Requirements of Ash Handling Systems

Mechanical system

Hydraulic system

Pneumatic system

Steam Jet syatem

13. Combustion Equipment for burning coal

Combustion equipments for burning coal

Stoker firing method for solid fuels

Pulverised firing method for pulverized fuels

Hand firing

Stokers firing

Pulverised firing

14. Mechanical Stokers

Advantages of stoker firing

Disadvantages of stoker firing

Classification of Mechanical stokers

Overfeed stokers

Underfeed stokers

15. Pulverisers

The types are

Ball mill

Ball and race mill

Impact or Hammer mill

Bowl mill

16. Electrostatic Precipitator

Principles of ElectroStatic Precipitator

Components of ESP

Merits of ESP

Demerits of ESP

17. Draught – different types

Natural Draught (Chimney Draught)

Artificial Draught

Forced Draught

Induced Draught

Balanced Draught

18. Surface Condenser Types

Functions of surface condensers

The types are

Down flow surface condensers

Central flow surface condensers

Inverted flow surface condensers

Evaporative surface condensers

Regenerative surface condensers

Advantages and disadvantages

19. Cooling Towers

The types are

Principles of cooling towers

Atmospheric cooling towers

Natural draught cooling towers

Mechanical draught cooling towers

NUCLEAR AND HYDEL POWER PLANTS

20. Nuclear Energy – Fission, Fusion Reaction

Nuclear fusion

Nuclear fission

Controlled and Uncontroled chain reactions

Difference between fusion and fission reactions

21. Types of Reactors,

Pressurized water reactor (PWR)

Boiling water reactor (BWR)

Fast breeder reactor (FBR)

22. Pressurized water reactor

Components and working principle

Advantages

Disadvantages

23. Boiling Water Reactor

Principle and construction of BWR

Advantages

Disadvantages

24. Waste Disposal and safety

Solid waste

Liquid waste

Gaseous waste

24. Hydel Power Plant – Essential Elements

Essential elements

Catchment area

Water reservoir

Dam- Storage dams,

Diversion dams

Detention dams

Overflow dams

Non-overflow dams

Masonary dams

Fill dams

Trash rack

Fore bay

Surge Tank

Penstock

Spillway

Water turbine

Draft tube

Advantages and Disadvantages

25. Selection of Turbines

Factors to be considered are

Working head

Specific Speed

Part load efficiency

Cavitation

Maximum Efficincy

Type of water available

Runaway speed

Overall cost of the plant

26. Governing of Turbines

Governing of impulse turbine

Governing of Reaction turbine

27. Micro Hydel developments

Construction and principle of operation

Advantages of micro hydel power stations

DIESEL AND GAS TURBINE POWER PLANT

28. Types of Diesel Plants, Components

According to the construction

Stationary diesel power plant

Package diesel power plant

Barge mounted diesel power plant

Gas turbine operated diesel power plant

According to stroke

two stroke and four stroke engines

According to speed

According to cooling system

Components of a diesel power plant

Diesel engine

Air intake system

Exhaust system

Fuel supply system

Engine starting system

Lubricating system

Engine cooling system

Governing system

29. Selection of Engine Type

Factors to be considered are

Power requirement

Speed

Cooling systems

Maintenance factors

Control system

Altitude

Temperature

Drive type

Starting equipment

Humidity

30. Applications

Diesel engine power plants find applications in:

Industries of small power requirement

Peak load plants in combination with other power plants

Mobile power plants- transporting systems- rail road, ships, automobiles and air crafts

Stand by power plants- emergency services

Frequent power cut areas

Central power stations

31. Gas Turbine Power Plant

Working principle

Advantages of gas turbine power plants

Disadvantages

Applications

32. Fuels

Natural gas

Liquid fuels

Residual fuels

Furnace oil

Boiler fuel oil

32. Gas Turbine Material

Special material with necessary cooling arrangement

Turbine rotor disc

Outer surface- austenitic steel with 12-18% Chromium, 8-12% Nickel

Central portions-Ferrite steel with high creep strength

Turbine rotor blade

Stainless steel &Nimonic alloys

Combustion Chamber

Nimonic 75 alloy

Compressor

Centrifugal compressor- Aluminium alloy

Axial flow compressor-Titanium alloy

Properties required for blade material

33. Open and Closed Cycles

Open cycle

Principle of operation – Gases leaving the turbine –exhausted to atmosphere

Schematic

T-s Diagram

Efficiency

Closed cycle

Principle of operation- Gases leaving the turbine- re-used after cooling

Schematic

T-s diagram

Efficiency

34. Reheating – Regeneration and Intercooling

Brayton cycle

Working principle

P-V and T-s diagram

Reheating

Arrangement

Effect-Increase in efficiency

T-s diagram

Regeneration

General arrangement

Effect- reduction in the mass of fuel in the combustion chamber

T-s diagram

Efficiency

Inter cooling

General arrangement

Effect- reduction in power requirement for compressor

T-s diagram

Efficiency

35. Combined Cycle

Combination of reheating, regeneration and inter cooling

T-s diagram

Efficiency

UNIT – IV

INTERNAL COMBUSTION ENGINES

Introduction

Classification of IC engines

Engine construction

IC engines components and its functions

Terminology of IC engines

Working of four stroke cycle engines

Working of four stroke cycle (petrol) SI Engine

Valve timing diagram for a four-stroke cycle CI engine (diesel engine)

Valve timing diagram for a four stroke CI engine

Two stroke cycle engine

Working of two stroke cycle SI Engine (petrol engine)

Port timing diagram for two stroke CI engine

Comparison of two stroke and four stroke engines

Comparison of SI and CI engines

Fuel supply system in SI (petrol) engines

Fuel pumps

Carburettor

Functions of carburettor

Types of carburettor

Simple carburettor

Defects in a simple carburetor

Solex carburettor

Solved problems in carburetor

Fuel supply systems in CI (diesel) engine

Methods of fuel injection

CAV fuel injection pump

Fuel injector

Types of nozzles

Fuel filter (petrol)

Diesel fuel filters

Ignition system of IC engines

Battery ignition system or coil system

Magneto ignition system

Comparison of magneto and coil ignition system

Electronic ignition system

Transistorised ignition system

Performance calculations

Commercial tests

Thermodynamic tests

Efficiencies of IC engine

Specific fuel consumption(SFC)

Heat balance sheet

Performance curves

problems

Fuels

Types of fuels

Calorific value of fuel

Combustion of fuels

Generalised combustion equation for any hydrocarbon fuel

Stochiometric air-fuel ratio

Actual air-fuel ratio

Determination of air supplied per kg of fuel

Solved problems

Knocking

Pre-ignition

Knocking phenomenon in CI engines or diesel knock

Comparison of knock in SI and CI engines

Lubrication system in IC engines

Properties of lubricant

Methods of lubrication

Cooling systems

Air-cooling

Water cooling

Thermostat in cooling system

Exhaust gas analysis

Exhaust gas recirculation (EGR) system

Treating the exhaust gas

Air pollution and its control

Air pollutants

Diesel engine emission

SI engine emission

Pollution control

Redesigning the combustion chamber

Resetting valve timing

Changing in cooling system

Changing the fuel supply system

Evaporative emission control of SI engine

Evaporative emission control system for CI engine

Crankcase emission control

Positive crankcase ventilation

Problems for practice

UNIT-V

REFRIGERATION AND AIRCONDITIONG

Introduction to refrigeration

Vapour compression refrigeration system

Superheating and Sub cooling of refrigerant

Performance calculations

Solved problems

Vapour absorption refrigeration system

Ammonia-water system

Lithium bromide system

Vapour compression Vs Vapour- absorption system

Psychrometry

Introduction

Psychrometric properties

Dalton’s law of partial pressure

Psychrometric chart

Solved problems

Cooling load calculation in A/c system

Fresh air and Room air mixture-By pass factor

Apparatus dew point

Heat load estimation

Determination of air quantity

Solved problems

Air conditioning systems

Summer air conditioning system

Winter air conditioning system

Room AC system or Unitary AC system

Central A/c system

Problems for practice