This PPT explains the basic of COAL BASED THERMAL POWER PLANTS.

3.  Steam power plants converts the energy stored in
the fossil fuels in the form of heat energy
 In thermal power plants, the input energy is
produced by burning the coal

4.  1. CONVENTIONAL
◦ Fossil fuel energy
◦ Hydraulic energy
◦ Nuclear energy
 2.NON CONVENTIONAL ENERGY SOURCES
◦ Solar energy
◦ Wind energy
◦ Tidal energy
◦ Wave energy
◦ Geo thermal energy
◦ Biomass energy

6.  Coal and Ash circuit
 Air and Flue gas circuit
 Water and Steam circuit
 Cooling water circuit

7.  Coal and Ash circuit:
◦ Coal to boiler transfer
◦ Ash resulting during combustion of coal from boiler removed and its stored
in ash storage device in ash handling
◦ Power plant of 100MW produces normally 20 to 25 tons of ash per hour.

9.  Air is taken from atmosphere and send through an air
preheater.
 Dust is removed from the air through series of filters
 The waste heat of flue gas passed to the chimney for
preheating the air in the preheater
 Afetr the combustion process the sufficient quantity of
flue gas is passed around the boiler tubes for preheat the
water and air

11.  It consists of boiler feed pump, boiler, turbine and feed water
pump
 The steam generated in the boiler passes through superheater
and supplied to steam turbine
 Out Water sent through condenser
 Then the feed water passes through economizer for boiler
 Feed water supplied external source to compensate losses

13.  It consists of condenser , cooling water pump and
cooling tower
 The warm water coming out from the condenser is
cooled in the cooling tower and recirculate within the
plant

15.  Initial investment is low
 The power plant can be located near load centre, so the
transmission cost and losses are considerably reduced
 The power production does not depend on the nature mercy

16.  Air pollution is the major problem inviting additional
investment
 It cannot be used as a peak load plant
 The coal may be exhausted by gradual use
 Power production cost is considerably high compared to hydel
plant
 Life efficiency is low as compared to hydel plant

17.  Theoretical cycle which works on steam turbine works.
 Ideal cycle for vapour power cycles.
 The diagram shows the rankine cycle
 Process 1-2 (Turbine)
 Process 2-3 (condenser)
 Process 3-4 (pump
 Process 4-1 (Boiler)

19.  Reheat rankine cycle
 Regeneration
 Combined reheating and regeneration

20.  Efficiency can be increased by increasing the pressure and temperature of
steam entering in to the turbine.
 Steam is initially expanded in high pressure steam
 Reheat the steam with the help of fluegas
 Then steam is expanded in to low pressure turbine.

22.  In rankine cycle in condensate which is coming out has very low
temperature and it mixes with hot water in boiler.
 It results it decrease in cycle efficiency
 Increase the temperature of the feed water is raised to the saturation
temperature before entering to the boiler.

23. REGENERATION CYCLE

24. 1. Reheating
• Flue gas reheating ( flue gas coming out from boiler to reheat the
steam)
• Live stream reheating (high-pressure steam from the boiler is used to
reheat the steam coming out from H.P Turbine designed for design heat
exchanger)
• Combined flue gas and live stream reheating : ( first pass through live
stream heater and gas heater)
2. Regeneration
• Ideal :
• Single Stage :
• Two Stage :

31.  Boiler is a closed vessel in which the steam is generated from
water by applying heat.
 Boiler is also known as steam generator
1.ACCORDING TO THE FLOW AND HOT GAS:
 Fire tube boiler
◦ Hot gas is passed through the tubes and the water
circulated around the tubes
◦ Eg:- Cochran Boiler, Locomotive Boiler
 Water tube boiler
◦ Water circulated through a number of tubes and hot gas
pass around the tubes
◦ Stirling boiler and Wilcox boiler

32.  2. According to the axis of shell:
◦ Vertical boilers
◦ Horizontal boilers
◦ Inclined boilers
 3.According to location or position of the furnace
◦ Internally fired boilers
◦ Externally and externally fired boilers
 4. according to the method of water circulation
◦ Natural circulation boilers
◦ Forced circulation boilers
 5. According to the application or boiler mobility
◦ Stationary boilers
◦ Mobile boilers
 6. According to steam pressure
◦ Low pressure , medium pressure, high pressure, supercritical boilers

33.  7. According to number of tubes used:
◦ Single tube used
◦ Multi tube boilers
 8.According to draft
◦ Natural draft boilers
◦ Artificial draft boilers
 9. according to types of fuel used
◦ Solid fuel boilers
◦ Liquid or gaseous fuel boilers
◦ Electrical heated and nuclear energy boilers

34. High Pressure Boilers
1. La- Mont Boiler

35.  Forced circulation
 Steam circulation maintained by centrifugal pump.

36. 2. Benson Boiler

37. 3. Loeffler Boiler

38.  Lamont boiler problem: Salt deposition and sedimentation in
water tubes
 So, forced circulation is used
Working:
 ecomomiser to evaporating drum
 Saturation steam from drum
 Steam passed through convection and radiant superheaters
 1/3rd steam passed from convection and radiant superheaters
 Remaining 2/3rd passd through the water in evaporating drum
to evaporate feed water

39. 4. Velox Boiler

40.  Boiler makes use of pressurized combustion
 Boiler pressure generate : 84 kg / cm2
Working
 Feed water from Economizer to tube evaporating section
 Gasturbine increases atm pr to furnace pressure.
 Steam separation from evaperator and flows to super heater
to turbine

41.  Super critical boiler is a type of boiler which is operated at
super critical pressure.
 Working range of steam generating plants from 125 atm and
510°C to 300 atm and 660°C . Power plants operated above
the critical pressure and temperature condition is called super
critical powerplant
Two type of super critical boilers are
 Drum Type boiler (
 Once through boiler

44.  Pressure gauge
 Stop valve
 Feed check valve
 Safety valve
 Fusible valve
 Blow off valve
 Water level indicator
 Man holes

45.  Economiser
 Steam super heater
 Airpreheater
 Deaerators ( removal of air and other gases in feed water)
 Steam seperator

46.  The fuel are fed on a distribution plate ,due to high velocity of
air the feed material remains in suspended condition during
burning
 The bed temperature is about 800-900 C
 So2 emission and Nox emissions are greatly reduced with the
use of limestone/dolamite
 Steam can be produced by fossils and waste fules using these
technique
 TYPES OF FBC:
◦ Circulating fluidized bed boiler
◦ Bubbling fluidized bed boiler

49.  Coal crushed (6-20 mm )
 Air fan flow upwards
 Chamber having large number of carbon particles
 H2SO4 acid less formation by bed material limestone
 Combustion 800-900degree C less Nox
 Heat release 10-15 times than conventional boiler

51.  Coal in lower section , limestone also
 Air distributors (primary and secondary)
 800-900 degree C
 Unburned particles colleceted in cyclone seperator again feed
to furnace

52. WORKING OF STEAM TURBINE
THERMAL ENERGY
KINETIC ENERGY
MECHANICAL ENERGY
STEAM TURBINE
Nozzle
Moving Blades

53. IMPULSE AND REACTION TURBINE

54. STEAM TURBINE AND BLADES

56.  Absorbing the jet velocity in more than one stage when steam
flows over moving blades
 Velocity compounding
 Pressure compounding
 Pressure – Velocity compounding

60.  The method of maintaining the speed of the turbine constant
irrespective on the basis of variation of load is known as
governing of turbines

64. Steam rate:
Capacity of the steam plant expressed in terms of steam rate or
specific fuel consumptions
SSC=Mass of steam / Work output unit kg/kWh
Heat rate:
It indicates the amount of fuel required to generate one unit of
electricity
Heat rate= Heat supplied/Work output kJ/kWh

65.  Fuel handling system
 Ash Handling system
 Cooling Towers
 Draught Systems
 Feed system

66. Coal delivery
Unload
Preparation
Transfer
Outdoor storage
Covered Storage
In plant handling
Weighing and measuring
Furnace

70. Coal Desulphurization
•Chemical Seperation
•Chemical TRW Meyers Process
•Working
•Coal To Mixing Tank
•Mixed With Ferric Sulphate
•RESULTING SLURRY HEAT UP TO 100-
130oc
•Coal Solution Pumped To Filter
•Neutrailized By Addition Of Coal
•In Extractor, Coal Is Mixed With Warm
Acetone And Water Which Dissolves
Remaining Sulphur In A coal

72.  1. Outplant handling of coal
◦ Transportation by sea or river
◦ By ropes
◦ By rail
◦ By road
◦ By pipeline
 2. Inplant handling of coal
◦ Belt conveyor
◦ Screw conveyors
◦ Bucket elevators

73. Coal Transfer Equipment
1. Belt Conveyor
2. Screw Conveyor
3. Bucket Elevator
4. Grab bucket elevator
5. Flight Conveyor
6. Skip hoists

80.  Fuel bed Furnaces (Coarse Particles)
 Fluidized bed furnaces (Crushed small Perticles)
 Cyclone Furnaces (Crushed particles)
 Pulverized coal furnaces (Fine Particles)
◦ Dry bottom furnance
◦ Wet bottom furnance

83.  Stokers are used to feed the solid fuels into the furnace in
power plants
 According to feed system, the stokers are classified into
types.
 Overfeed stokers
 Underfeed stokers

86.  Pulveriser mill is used to pulverize the coal for combustion in
the steam generating furnaces .
 Pulverized coal increase its surface exposure and complete
combustion.
Benefits:
 Combustion rate is increased
 Thermal efficiency is increased
 Fuel feed rate is increased

87.  Ball mill
 Hammer mill
 Ball and race mill
 Bowl mill

101.  Coal fired boilers about 10 to 15% of the burned products in
the form of ash
 Large scale power plants produces about tones of ash per day
 Ash handling requires quenching because,
1. Quenching reduces the temperature of ash
2.It reduces the corrosive action of ash
3.Quench reduces the dust accompanying ash
Following methods to remove ash:
1. Vaccum extraction plant 2. Hydraulic system
3. Mechanical Conveyor 4. Steam jet system
5. Pneumatic System

104.  In a steam jet system, the ash is carried by high velocity
steam which carrying dry solid materials.
 In pneumatic system ash is carried by high velocity air or
stream to the point of delivery.

106.  The warm water discharged from the condenser is fed into the
cooling tower and the cooled water is fed back to the
condenser

108. Forced Draft Cooling Tower Induced draft Cooling Towers

109. Dry cooling tower
1.Direct type

112. FEED WATER TREATMENT

114. Boiler Feed water treatment system

115.  The function of the demineralization plant is to remove the
dissolved salt by ion exchange method i.e. chemical method.
 Generally hard water contains sodium,chloride, carbonates,
bi-carbonates, silicates and potassium, iron, Calcium and
Magnesium.

117.  Carbonic acid dissolved to water and carbon di oxide
H2CO3=H2O+CO2

118.  Deaeration is the process of removing the dissolved more
oxygen from the water to avoid corrosion
(Sodium sulphite)2Na2SO3+O2= (sodium sulphate)2Na2SO4

119.  Uses Semipermeable membrane
 Solvent molecules passed through region of higher
concentration side to region of lower concentration side.
 Purity level higher than demineralization