ArulmiguMeenakshi Amman College of Engineering
Vadamavandal-604410.
Important questions and answers
CME384- POWER PLANT ENGINEERING
Prepared by
V.Umapathy,
Prof. /Mech.
S.No. Questions and answers
Unit-I
COAL BASED THERMAL POWER PLANTS
2 – marks question and answers
1. What is coal based thermal power plant?
A coal-based thermal power plant is a type of power generation facility that uses coal as the primary fuel source
to produce electricity.
2. What is the Rankine cycle modification?
The Rankine cycle is a thermodynamic cycle used in steam power plants. Modifications to the basic Rankine
cycle aim to improve efficiency, reduce costs, and increase flexibility.
3. What is the Rankine cycle?
The Rankine cycle is a thermodynamic cycle used to generate steam power, typically in power plants. It's a model
for predicting the performance of steam turbine systems.
Key Components:
1. Boiler: Water is heated to produce steam.
2. Turbine: Steam expands, generating mechanical energy.
, 3. Condenser: Steam is condensed back to water.
4. Pump: Water is pumped back to the boiler.
4. What is the layout of a thermal power plant?
Selection of site, general layout of a thermal power plant showing paths of coal, steam, water, air, ash and flue
gasses, ash handling system, Brief description of components : Boilers, Super heaters, Economizers, electrostatic
precipitators, steam Turbines : Impulse and reaction turbines, Condensers, feed water.
5. What are the four main circuits in the general layout of a modern steam power plant?
Coal and Ash Circuit:
- Coal handling, storage, and feeding to the boiler.
- Ash collection, handling, and disposal.
2. Air and Gas Circuit:
- Air supply for combustion.
- Flue gas handling, including dust collection and emission control.
3. Steam and Water Circuit (Rankine Cycle):
- Water treatment and feeding to the boiler.
- Steam generation, superheating, and expansion in the turbine.
- Condensation and reuse of water.
4. Cooling Water Circuit:- Cooling water supply for the condenser.
- Heat dissipation through cooling towers or other systems.
6. What is a supercritical boiler?
, A supercritical boiler is a type of boiler that operates above the critical pressure of water (221 bar or 3200 psi) and
temperature (374°C or 687°F). At these conditions, water becomes a supercritical fluid, exhibiting properties of
both liquids and gases.
7. What is the difference between a supercritical boiler and a subcritical boiler in terms of components?
Components and Design:
1. Drum:
- Subcritical: Has a drum for steam-water separation.
- Supercritical: No drum; once-through design.
2. Water Circulation:
- Subcritical: Natural or forced circulation.
- Supercritical: Once-through, no circulation loop.
3. Tubing and Materials:
- Supercritical: Requires advanced materials for high temperatures and pressures.
4. Control Systems:
- Supercritical: More sophisticated controls for managing supercritical conditions.
Operational Differences:
1. Pressure and Temperature:
- Supercritical: Operates above critical point (221 bar, 374°C).
- Subcritical: Operates below critical pressure.
2. Efficiency:
- Supercritical: Higher efficiency due to higher steam parameters.
, 8. What is FBC?
Fluidized Bed Combustion (FBC) is a combustion technology used in boilers for burning fuel, typically coal or
biomass, in a fluidized bed of inert material.
Key Features:
1. Fluidized Bed: Air is blown through a bed of sand or other inert material, creating a turbulent mixture.
2. Fuel Combustion: Fuel is added to the bed, burning at a lower temperature (800-900°C).
3. High Efficiency: Good mixing and heat transfer lead to efficient combustion.
9. What is the role of air in an FBC boiler?
Fluidization:
- Air is blown through the bed of inert material (e.g., sand), creating a fluidized state.
- Promotes mixing and turbulence, enhancing combustion.
2. Combustion:
- Provides oxygen for burning fuel in the fluidized bed.
- Helps achieve efficient combustion at lower temperatures (800-900°C).
3. Heat Transfer:
- Air movement enhances heat transfer between the bed and boiler tubes.
4. Emission Control:
- Air staging can help reduce NOₓ emissions.
10. What are the two types of cogeneration systems?
Topping Cycle:
- Process: Electricity is generated first, and waste heat is recovered for useful applications (e.g., heating, process
steam).
- Common: Gas turbines, diesel engines, or steam turbines with heat recovery.
2. Bottoming Cycle:
- Process: High-temperature heat is used for industrial processes first, and waste heat generates electricity.
- Common: Waste heat recovery systems in industries like cement or steel.
Vadamavandal-604410.
Important questions and answers
CME384- POWER PLANT ENGINEERING
Prepared by
V.Umapathy,
Prof. /Mech.
S.No. Questions and answers
Unit-I
COAL BASED THERMAL POWER PLANTS
2 – marks question and answers
1. What is coal based thermal power plant?
A coal-based thermal power plant is a type of power generation facility that uses coal as the primary fuel source
to produce electricity.
2. What is the Rankine cycle modification?
The Rankine cycle is a thermodynamic cycle used in steam power plants. Modifications to the basic Rankine
cycle aim to improve efficiency, reduce costs, and increase flexibility.
3. What is the Rankine cycle?
The Rankine cycle is a thermodynamic cycle used to generate steam power, typically in power plants. It's a model
for predicting the performance of steam turbine systems.
Key Components:
1. Boiler: Water is heated to produce steam.
2. Turbine: Steam expands, generating mechanical energy.
, 3. Condenser: Steam is condensed back to water.
4. Pump: Water is pumped back to the boiler.
4. What is the layout of a thermal power plant?
Selection of site, general layout of a thermal power plant showing paths of coal, steam, water, air, ash and flue
gasses, ash handling system, Brief description of components : Boilers, Super heaters, Economizers, electrostatic
precipitators, steam Turbines : Impulse and reaction turbines, Condensers, feed water.
5. What are the four main circuits in the general layout of a modern steam power plant?
Coal and Ash Circuit:
- Coal handling, storage, and feeding to the boiler.
- Ash collection, handling, and disposal.
2. Air and Gas Circuit:
- Air supply for combustion.
- Flue gas handling, including dust collection and emission control.
3. Steam and Water Circuit (Rankine Cycle):
- Water treatment and feeding to the boiler.
- Steam generation, superheating, and expansion in the turbine.
- Condensation and reuse of water.
4. Cooling Water Circuit:- Cooling water supply for the condenser.
- Heat dissipation through cooling towers or other systems.
6. What is a supercritical boiler?
, A supercritical boiler is a type of boiler that operates above the critical pressure of water (221 bar or 3200 psi) and
temperature (374°C or 687°F). At these conditions, water becomes a supercritical fluid, exhibiting properties of
both liquids and gases.
7. What is the difference between a supercritical boiler and a subcritical boiler in terms of components?
Components and Design:
1. Drum:
- Subcritical: Has a drum for steam-water separation.
- Supercritical: No drum; once-through design.
2. Water Circulation:
- Subcritical: Natural or forced circulation.
- Supercritical: Once-through, no circulation loop.
3. Tubing and Materials:
- Supercritical: Requires advanced materials for high temperatures and pressures.
4. Control Systems:
- Supercritical: More sophisticated controls for managing supercritical conditions.
Operational Differences:
1. Pressure and Temperature:
- Supercritical: Operates above critical point (221 bar, 374°C).
- Subcritical: Operates below critical pressure.
2. Efficiency:
- Supercritical: Higher efficiency due to higher steam parameters.
, 8. What is FBC?
Fluidized Bed Combustion (FBC) is a combustion technology used in boilers for burning fuel, typically coal or
biomass, in a fluidized bed of inert material.
Key Features:
1. Fluidized Bed: Air is blown through a bed of sand or other inert material, creating a turbulent mixture.
2. Fuel Combustion: Fuel is added to the bed, burning at a lower temperature (800-900°C).
3. High Efficiency: Good mixing and heat transfer lead to efficient combustion.
9. What is the role of air in an FBC boiler?
Fluidization:
- Air is blown through the bed of inert material (e.g., sand), creating a fluidized state.
- Promotes mixing and turbulence, enhancing combustion.
2. Combustion:
- Provides oxygen for burning fuel in the fluidized bed.
- Helps achieve efficient combustion at lower temperatures (800-900°C).
3. Heat Transfer:
- Air movement enhances heat transfer between the bed and boiler tubes.
4. Emission Control:
- Air staging can help reduce NOₓ emissions.
10. What are the two types of cogeneration systems?
Topping Cycle:
- Process: Electricity is generated first, and waste heat is recovered for useful applications (e.g., heating, process
steam).
- Common: Gas turbines, diesel engines, or steam turbines with heat recovery.
2. Bottoming Cycle:
- Process: High-temperature heat is used for industrial processes first, and waste heat generates electricity.
- Common: Waste heat recovery systems in industries like cement or steel.
