INSTRUMENTATION SCHEME OF

THERMAL POWER PLANT

BY:

ANKUR MAHAJAN( 112505)

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.

INTRODUCTION This entire task is often taken up by control &

instrumentation or simply instrumentation system which has following functions:

a) Measurement

b) Control

c) Operation

d) Monitoring

e) Protection

INTRODUCTION 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

(e Bearing of turbine & Thermocouple generator (f feed pump, condensate RTD pump

(3) Flow (a High Pressure Steam Orifice, Venturi, 75-100 (b Feed water inlet Flow Nozzle,etc. (c Condensate

(4) Level (a Boiler Drum (b condensate tank Differential 75-100 (c Water line pressure methods

(5) Expansion (a Turbine Shaft Relative 6-8 (b Turbine casing Displacement

(6) Vibration (a turbine & generator Mass spring with shafts & bearing shells potentiometric Capacitive, eddy 30-50 current, piezo electric & optical types are used

(7) Analysis(i) WATER (a feed water at econ- -omiser inlet (b Boiler inlet Conductive cell 8-12 (c Condenser with meter (d Condensate pump discharge(ii) STEAM (a Saturated steam Conductive cell 4-6 (b Main line steam with meter (c Super heater inlet Na Analyser 1-2(iii) FLUE

GASES (a O2 – economiser to air Zirconia cell 2-4 heater (b CO2 – Air heater inlet CO2 analyser 2-4 & outlet (c CO – stack CO analyser 2-4 (d SO2 - Stack SO2 analyser 1-2

(e Nitrogen Oxide- stack N- Oxide Analysesr 1-2

(f Dust concn.- stack Optical method 2-3

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 Tube

C shaped & made into an arc of about 270

0

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.

1

21T

T

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 -60

0 TO 15

0

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 110

0C 1773

0C

COPPER 00C 180

0C 1083

0C

NICKEL -2200C 300

0C 1435

0C

TUNGSTEN -2000C 1000

0C 3370

0C

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.

THANKS