instrumentation scheme of thermal power plants with little introduction

2. INSTRUMENTATION
SCHEME OF THERMAL
POWER PLANT
BY:
ANKUR MAHAJAN( 112505)

3. 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

4. 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.

5. 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

6. 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

7. 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)

8. CLASSIFICATION OF POWER PLANTS

9. 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.

10. COAL MINES IN INDIA

11. OPERATION

12. LAYOUT OF STEAM POWER PLANT

13. SUB CYCLES OF THERMAL POWER PLANT
 WATER CYCLE -------- CONDENSATION, FEEDPUMP,
ECONOMIZER
 COMBUSTION CYCLE ---------- ECONOMIZER, BOILER, SUPER
HEATER
 STEAM CYCLE ------------------ BOILER, SUPER HEATER, TURBINE

14. QUANTITIES TO BE MEASURED
 Pressure
 Temperature
 Flow
 Level
 Expansion/ Contraction
 Analysis of (1) Water (2) Steam (3) Flue Gases
 And Others

15. 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

16. (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

17. (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

18. 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

19. 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

20. 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.

21. MEASUREMENT OF PRESSURE

22. 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.

23. MEASUREMENT OF PRESSURE
 Bourdon Tube
C shaped & made into an arc of
0
about 270
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.

24. 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
1
T1
T2 = Temp. inside the condenser
T1= Superheater temperature
 Temp. can be measured only by using indirect
methods.

25. MEASUREMENT OF TEMPERATURE
 THERMOELECTRIC THERMOMETRY
 The actual value depend upon the material used &
on temperature difference between the junctions.

26. MEASUREMENT OF TEMPERATURE
TYPE METAL A METAL B TEMPERAT POINT TO
URE KNOW
RANGE
0 RESISTANT TO
T COPPER COPPER- 400 C CORROSION IN
NICKEL MOST
(CONSTANTAN) ATMOSPHERE
0 NOT COMMONLY
J IRON COPPER- 850 C USED BECAUSE
NICKEL OF RUSTING &
(CONSTANTAN) EMBRITTLEMENT
0 SUITABLE FOR
E NICKEL- COPPER- 700 C OXIDISING &
CHROMIUM( NICKEL INERT
CHROME) (CONSTANTAN) ATMOSPHERE
0 MOST
K NICKEL- NICKEL- 1100 C COMMONLY
CHROMIUM( ALUMINIUM USED
CHROME) (ALUMEL)

27. MEASUREMENT OF TEMPERATURE
TYPE METAL A METAL B TEMPERAT POINT TO
URE KNOW
RANGE
0
R PLATINUM1 PLATINUM 1400 C SUITABLE FOR
OXIDISING &
3%RHODIUM INERT
ATMOSPHERE
0
S PLATINUM1 PLATINUM 1400 C SUITABLE FOR
OXIDISING &
0%RHODIUM INERT
ATMOSPHERE,
CAN BE USED IN
VACUUM FOR
SHORT PERIOD
THERMISTOR ARE NOT USED IN THERMAL POWER PLANTS
0 0
BECAUSE ITS RANGE IS -60 TO 15

28. 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

29. MEASUREMENT OF TEMPERATURE
METAL MIN. TEMP. MAX.TEMP. MELTING
POINT
0 0 0
PLATINUM -260 C 110 C 1773 C
0 0 0
COPPER 0C 180 C 1083 C
0 0 0
NICKEL -220 C 300 C 1435 C
0 0 0
TUNGSTEN -200 C 1000 C 3370 C

30. 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.

31. MEASUREMENT OF FLOW

32. 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.

33. ANALYSIS

34. 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.

35. 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.

36. REFERENCES
 Educational Technology Service Centre- IIT
KHARAGPUR; S. BANERJEE; EE Deptt., Energy
resource & technology.
 V.K. Mehta, “Principles Of Power System”, S
Chand.

37. THANKS