NAME: SARVESH KUMAR

CLASS: X DIV : A:SCHOOL:LIPS

THERMAL POWER PLANT

CONTENTS

INTRODUCTION OF POWER PLANT OBJECTIVE OF INSTRUMENTATION & CONTROL CLASSIFICATION OF POWER PLANTS THERMAL POWER PLANT SUB CYCLES OF THERMAL POWER PLANT QUANTITIES TO BE MEASURED MEASUREMENT POINT & VARIABLES MEASUREMENT PROCESS REFERENCES

INTRODUCTION

Power plant is assembly of systems or sub-systems to generate electricity.

Power plant must be useful economically & environmental friendly to the society.

Design of power plant incorporate two important aspects:

(1)Selection of power generating equipments should be such so that maximum of return will result from minimum expenditure over the working life of the plant.

(2)Operation should be such so as to provide cheap, reliable & continuous service.

This entire task is often taken up by control & instrumentation or simply instrumentation system which has following functions:

a) Measurementb) Controlc) Operationd) Monitoringe) Protection

For a plant Measurement system needs to be: Very accurate Reliable Delays should be as small as possible Should be switched on manually when

a overall control system fails

Objective OF Instrumentation &

Control Efficient Operation of the plant Economic Operation of the plant Safe operation of the plant Pollution control

GURUNANAK THERMAL POWER PLANT, BATHINDA(PUNJAB)

Classification Of Power Plants

Thermal Power Plant

A Generating station which convert heat energy into electrical energy

The Steam Power Plant, Diesel Power Plant, Gas Turbine Power Plant& Nuclear Power Plant are called THERMAL POWER PLANT. Works on RANKINE

Cycle.

Coal Mines In India

Operation

Layout OF Steam Power Plant

Sub Cycles Of Thermal Power Plant

WATER CYCLE -------- CONDENSATION, FEEDPUMP, ECONOMIZER

COMBUSTION CYCLE ---------- ECONOMIZER, BOILER, SUPER HEATER

STEAM CYCLE ------------------ BOILER, SUPER HEATER, TURBINE

Quantities To Be Measured

Pressure Temperature Flow Level Expansion/ Contraction Analysis of (1) Water (2) Steam (3) Flue

Gases And Others

Measurement Points & Variables

Variables/ Measuring Points Types Of Sensors/ Approx. number Parameters Instruments in the plant

(1) Pressure (a) Boiler Bourdon Tube, (b) Turbine Diaphragm, (c) Turbine Throttle Bellows 375-

400 (d) Furnace Bell Gauges

(2) Tempera (a Steam at superheater Thermocouple ture inlet & outlet (b Feed Water at economiser inlet (c Water at condenser RTD 700-750 inlet (d Air Preheater (e Flue Gases Thermocouple

Measurement Of Pressure

Varies from vacuum as in furnace to 200 Mpa at the main steamline.

Pressure measuring devices are divided into two groups: (1) Liquid Columns (2) Expansion Elements

Liquid columns: Manometric type instruments Low range pressure measurement P =0

h Patm

WELL TYPE MANOMETER

Measurement Of Pressure

These are not favoured in modern power plant but are still used in older power plants.

Expansion elements: Used in modern power plants Usually metallic & its movement indicates

the pressure Either directly coupled with mechanical

linkages or indirectly by an electrical transducer

connected to a read out device

Measurement Of Pressure

Expansion elements

Diaphragms Bellows Bourdon tube Diaphragms: Commonly corrugated diaphragms are used

because large deflection can be produced without nonlinearity compared with flat type.

In order to increase the deflection capabilities two or more corrugated diaphragms are welded at the circumferences--- Capsule element.

Measurement Of Pressure

Measurement Of Pressure

Bellows

Manufactured from Brass, Brass alloys,

Stainless steel.

Used for low pressure

measurement.

For high pressure measurement bellows are

connected with spring.

Measurement Of Pressure

Bourdon TubeC shaped & made into an arc

of about 2700

Material from which it made depends upon the pressure

range of the device

Bourdon tubes are also used in forms other than C type Spiral element: large movement than C tube.

Helical element: produce more or less circular

movement which is useful for driving a recorder pen

directly.

Measurement Of Temperature

Since power generation is a Thermodynamic process so up to date knowledge of temperature of the plant is most important.

The efficiency of generation also depend on the temperature measurement

T2 = Temp. inside the condenserT1= Superheater temperature Temp. can be measured only by using indirect

methods.

121TT

Measurement Of Temperature

THERMOELECTRIC THERMOMETRY The actual value depend upon the

material used & on temperature difference between the junctions.

Measurement Of Temperature

TYPE METAL A METAL B TEMPERATURE RANGE

POINT TO KNOW

T COPPER COPPER- NICKEL (CONSTANTAN)

4000C RESISTANT TO CORROSION IN MOST ATMOSPHERE

J IRON COPPER- NICKEL (CONSTANTAN)

8500C NOT COMMONLY USED BECAUSE OF RUSTING & EMBRITTLEMENT

E NICKEL-CHROMIUM(CHROME)

COPPER- NICKEL (CONSTANTAN)

7000C SUITABLE FOR OXIDISING & INERT ATMOSPHERE

K NICKEL-CHROMIUM(CHROME)

NICKEL- ALUMINIUM (ALUMEL)

11000C MOST COMMONLY USED

Measurement Of Temperature

TYPE METAL A METAL B TEMPERATURE RANGE

POINT TO KNOW

R PLATINUM13%RHODIUM

PLATINUM 14000C SUITABLE FOR OXIDISING & INERT ATMOSPHERE

S PLATINUM10%RHODIUM

PLATINUM 14000C SUITABLE FOR OXIDISING & INERT ATMOSPHERE, CAN BE USED IN VACUUM FOR SHORT PERIOD

THERMISTOR ARE NOT USED IN THERMAL POWER PLANTS BECAUSE ITS RANGE IS -600 TO 150

Measurement Of Temperature

RESISTANCE THERMOMETRY Suggested by Siemens in 1871- but not

satisfactory used for high temperature Today RTD is given by H.L.Calender in 1891 PROPERTY-The resistance of the conductor

changes when its temperature is changed. Copper is occasionally used Platinum, nickel or nickel alloys are commonly

used Tungsten is used for high temperature

applications

Measurement Of Temperature

METAL MIN. TEMP. MAX.TEMP. MELTING POINT

PLATINUM -2600C 1100C 17730CCOPPER 00C 1800C 10830CNICKEL -2200C 3000C 14350CTUNGSTEN -2000C 10000C 33700C

Measurement Of Flow

A universal flow meter for all applications in power station is not available.

Infact there are more ways of measuring flow than measuring pressure & temperature.

Dual function meters usually measure flow rate with linear output & minimum error.

Vortex & Ultrasonic meters have become available in recent years (1986) & their full potential is not still fully developed.

Measurement Of Flow

Analysis pH, DO,TURBIDITY & HYDRAZINE: Need to be checked for acidity (pH),

Dissolved oxygen(DO) Turbidity arising out of contamination

by suspended particles . Hydrazine which is added from outside

to the feed water but the excess should be monitored.

Oxygen reacts with thallium to form thallium oxide which in aqueous solution show good conductivity.

ANALYSIS

Analysis

Turbidity is measured at the outlet of the condenser.

Hydrazine is added to decrease dissolved oxygen

Hydrazine nitrogen + water Its also makes water alkaline & prevent

acidic corrosion. Its is also toxic so its overuse can effect

the aquatic life.

References

British Electricity International,Modern Power station practice, control & instrumentation, vol F.

A.K. Sawhney, “A course in Electrical & Electronic measurements & instrumentation”, Danpat Rai & CO.,seventeenth edition.

D Patranabis, “Principles of Industrial Instrumentation”,TMH, second edition.

Frederick T. Morse, “ Power Plant Engineering”. “Power Plant Engineering”,

http://en.wikipedia.org/wiki/power plant engineering A.K. Raja, “Power plant Engineering”,New Age

International Publishers.

References

Educational Technology Service Centre- IIT KHARAGPUR; S. BANERJEE; EE Deptt., Energy resource & technology.

V.K. Mehta, “Principles Of Power System”, S Chand.