1. Unit -2 Power Plants
Steam power plant
Layout
Boilers
Pulverized coal burners
Fluidized bed combustion

2. Power generating units are mega projects
Require huge capital investment
Require natural resources like, fossil fuels
Large amount of water
Changes the local eco system
Huge Impacts on the Environment and Health

3. In a thermal power plant, steam is produced and used to spin a turbine that operates a generator. Shown here is a diagram of a conventional thermal power plant, which uses coal, oil, or natural gas as fuel to boil water to produce the steam. The electricity generated at the plant is sent to consumers through high-voltage power lines.

4. Understanding Coal fired Thermal Power plants

5. Understanding Coal fired Thermal Power plants

6. Coal Mining
Surface Mining
Strip Mining
Underground Mining

7. Understanding Coal fired Thermal Power plants
Air Quality
Around the coal based plants the ambient concentrations of Sulphur Dioxide, Oxides of Nitrogen and SPM are high.
Epidemiological Studies have shown that of the area surrounding coal based thermal plants, population living within a 2 -5 km radius of the plant suffers from respiratory disorders .
Two other gases, carbon dioxide and ozone are emitted. The high amount of carbon dioxide emission from thermal power plants contribute to global warming leading to climate change is significant Ground level ozone, which is formed due to photolytic reactions of NOx and its impacts are under study

8. Understanding Coal Fired Thermal Power Plants
Fly ash contains a toxic brew of dangerous chemicals and is the largest contributor to mercury pollution

9. Understanding Coal fired Thermal Power plants
Composition of Fly ash
It contains as main chemical components SiO2 (51.4 wt%), Al2O3 (22.1 wt%) and Fe2O3 (17.2 wt%; ignited weight basis). As commonly observed, many toxic elements and heavy metals are highly enriched in the fly ash relative to the original coal. For example, considerable amounts of Be (16.4 ppm), Cu (106 ppm), Zn (578 ppm), As (40.4 ppm), Cd (2.6 ppm), Hg (18 ppm), Pb (71 ppm), and U (21.8 ppm) is found in Fly ash.

10. Understanding Coal fired Thermal Power plants
Water slurry is used to take the ash from the power plant to the ash pond for disposal. 
Water slowly seeps into the ground while carrying with it the ash leach ate. Water may contain harmful heavy metals like boron, which have a tendency to leach out over a period of time. 
When fly ash comes into contact with water, leaches into groundwater supplies which get polluted and unsuitable for domestic use. 
The release of ash pond decant into the local water bodies- water dries up, dust nuisance, increases turbidity, decreases primary productivity, affects fishes and other aquatic biota

12. Coal Power Plant Operation
Steam Turbine Generator
Is a series of steam turbines interconnected to each other and then a generator
Steam Condenser
Steam enters from the turbine generator and is pumped into the bottom of the condenser, where pumps recycle the condensed steam from the feedwater
Stack
Releases process emissions.

13. Introduction What is a Boiler?
Vessel that heats water to become hot water or steam
At atmospheric pressure water volume increases 1,600 times
Hot water or steam used to transfer heat to a process
A boiler is an enclosed vessel that provides a means for combustion heat to be transferred to water until it becomes heated water or steam.
When water at atmospheric pressure is boiled into steam its volume increases about 1,600 times, producing a force that is almost as explosive as gunpowder. This causes the boiler to be an equipment that must be treated with utmost care
The hot water or steam under pressure is then usable for transferring the heat to a process.

14. Introduction BOILER Figure: Schematic overview of a boiler room
STEAM TO PROCESS
EXHAUST GAS
VENT
STACK
DEAERATOR
ECO- NOMI- ZER
PUMPS
BOILER
VENT
BURNER
WATER SOURCE
BLOW DOWN SEPARATOR
FUEL
BRINE
CHEMICAL FEED
SOFTENERS
Figure: Schematic overview of a boiler room

15. Types of Boilers Fire Tube Boiler Water Tube Boiler Packaged Boiler
Fluidized Bed (FBC) Boiler
Stoker Fired Boiler
Pulverized Fuel Boiler
Waste Heat Boiler
Thermic Fluid Heater (not a boiler!)

16. Type of Boilers 1. Fire Tube Boiler
Relatively small steam capacities (12,000 kg/hour)
Low to medium steam pressures (18 kg/cm2)
Operates with oil, gas or solid fuels

17. Type of Boilers 2. Water Tube Boiler
Used for high steam demand and pressure requirements
Capacity range of 4,500 – 120,000 kg/hour
Combustion efficiency enhanced by induced draft provisions
Lower tolerance for water quality and needs water treatment plant

18. Type of Boilers 3. Packaged Boiler Comes in complete package Features
High heat transfer
Faster evaporation
Good convective heat transfer
Good combustion efficiency
High thermal efficiency
Classified based on number of passes
Oil Burner
To Chimney

19. 4. Fluidized Bed Combustion (FBC) Boiler
Type of Boilers
4. Fluidized Bed Combustion (FBC) Boiler
Particles (e.g. sand) are suspended in high velocity air stream: bubbling fluidized bed
Combustion at 840° – 950° C
Capacity range 0,5 T/hr to 100 T/hr
Fuels: coal, washery rejects, rice husk, bagasse and agricultural wastes
Benefits: compactness, fuel flexibility, higher combustion efficiency, reduced SOx & NOx

20. Type of Boilers 4a. Atmospheric Fluidized Bed Combustion (AFBC) Boiler
Most common FBC boiler that uses preheated atmospheric air as fluidization and combustion air
4b. Pressurized Fluidized Bed Combustion (PFBC) Boiler
Compressor supplies the forced draft and combustor is a pressure vessel
Used for cogeneration or combined cycle power generation

21. Type of Boilers
4c. Atmospheric Circulating Fluidized Bed Combustion (CFBC) Boiler
Solids lifted from bed, rise, return to bed
Steam generation in convection section
Benefits: more economical, better space utilization and efficient combustion

22. Type of Boilers 5. Stoke Fired Boilers a) Spreader stokers
Coal is first burnt in suspension then in coal bed
Flexibility to meet load fluctuations
Favored in many industrial applications

23. Type of Boilers 5. Stoke Fired Boilers
b) Chain-grate or traveling-grate stoker
Coal is burnt on moving steel grate
Coal gate controls coal feeding rate
Uniform coal size for complete combustion

24. 6. Pulverized Fuel Boiler
Type of Boilers
6. Pulverized Fuel Boiler
Pulverized coal powder blown with combustion air into boiler through burner nozzles
Combustion temperature at °C
Benefits: varying coal quality coal, quick response to load changes and high pre-heat air temperatures
Tangential firing

25. Type of Boilers 8. Thermic Fluid Heater User equipment
3. Heat transfer through heat exchanged
8. Thermic Fluid Heater
Control panel
Blower motor unit
Fuel oil filter
Exhaust
Insulated outer wall
User equipment
2. Circulated to user equipment
4. Fluid returned to heater
1. Thermic fluid heated in the heater
(Energy Machine India)