1. In thermal power plants, the function of economizer is to:
A. Heat steam from boiler
B. Heat feed water using flue gas
C. Heat air fuel mixture
D. Heat steam taken from turbine outlets
Answer: B. Heat feed water using flue gas
Explanation:
Economizer:
2. Air forced into the tower in mechanical draft cooling towers by using:
A. Spray nozzles
B. Propellers
C. Louvers
D. Deckings
Answer: B. Propellers
Explanation:
Explanation:
The load is the amount of power in the electrical grid.
Baseload is the level that it typically does not go below, that is, the basic amount of electricity that is always required. Baseload is typically provided by large coal-fired and nuclear power stations. They may take days to fire up, and their output does not vary.
Examples of baseload power plants are:
Nuclear power plant
Coal or thermal power plant
Hydroelectric plant
Geothermal plant
Biogas plant
Biomass plant
Solar thermal with storage
Ocean thermal energy conversion
Peak load is the daily fluctuation of electricity use. It is usually lowest in the morning and highest in the early evening. It also varies seasonally. Peak load, the variable part of the electrical supply and demand, is provided by more responsive and smaller plants whose output can be quickly ramped up and down or that can even be quickly turned on and off.
Examples of peak load power plants are:
Gas plant
Solar power plants
Wind turbines
Diesel generators
Storage type hydro plants
4. The function of electrostatic precipitator in a coal-based thermal power plant is to:
A. Collect dust from flue gas
B. Clean the turbine blades
C. Collect dust at the air inlet
D. Collect dust from the coal
Answer: A. Collect dust from flue gas
Explanation:
Electrostatic precipitators (ESP):
5. In a Steam power plant, _________ heats the feed water on its way to the boiler by deriving heat from the flue gases.
A. Superheater
B. Economizer
C. Preheater
D. Turbine
Answer: B. Economizer
Explanation:
Superheaters:
Explanation:
Steam power station:
Disadvantages:
7. The overall efficiency of the steam power plant is defined as:
Answer:
The efficiency of Steam Power Station:
Thermal Efficiency:
Explanation:
Economizer:
It is also known as a feedwater heater. It is a device in which the waste heat of the flue gases is utilized for heating the feed water.
In economizer, feed water is preheated to improve overall efficiency and only sensible heat transfer is taking place so feed water is heated without converting it into steam. Therefore, the economizer is placed after the superheater and located in the feeding water circuit.
Following are the advantages:
Condensers:
Explanation:
Prime Mover:
Explanation:
Economizer:
Important Points:
Air preheater:
Superheater:
11. Which of the following methods is a conventional method of electrical energy generation?
A. Photovoltaic cells
B. Fuel cells
C. Wind power plant
D. Thermal power plant
Answer: D. Thermal power plant
Explanation:
Energy resources can be classified into two categories:
Renewable source (Non-conventional energy)
Non-Renewable source (Conventional energy)
12. The overall efficiency of a steam power plant is about
A. 56%
B. 29%
C. 45%
D. 66%
Answer: B. 29%
Explanation:
The overall efficiency of the steam power plant is about 29%.
A. Heat steam from boiler
B. Heat feed water using flue gas
C. Heat air fuel mixture
D. Heat steam taken from turbine outlets
Answer: B. Heat feed water using flue gas
Explanation:
Economizer:
- It is also known as a feedwater heater. It is a device in which the waste heat of the flue gases is utilized for heating the feed water.
- In economizer, feed water is preheated by using flue gases to improve overall efficiency and only sensible heat transfer is taking place so feed water is heated without converting it into steam. Therefore, the economizer is placed after the superheater and located in the feeding water circuit.
- Reduce fuel consumption
- Preheating a fluid (feed-water in case of steam boiler)
- Increases the efficiency of the power plant
- There is about 15 to 20% of coal saving.
- It increases the steam raising capacity of a boiler because it shortens the time required to convert water into steam.
- It prevents the formation of scale in boiler water tubes.
2. Air forced into the tower in mechanical draft cooling towers by using:
A. Spray nozzles
B. Propellers
C. Louvers
D. Deckings
Answer: B. Propellers
Explanation:
- Cooling towers are often found in commercial and industrial sites, helping to keep components cool and to allow the HVAC system to do its job with less stress and strain.
- The principal function of a cooling tower is to remove heat from the water discharged from the condenser so that the water can be discharged to the environment or recirculated and reused.
- Cooling towers are used in conjunction only with water-cooled chillers and vary in size from small rooftop units to very large hyperboloid structures.
- Cooling towers are also characterized by the means by which air is moved.
- Mechanical draft cooling towers are the most widely used in buildings and rely on power-driven fans to draw or force the air through the tower. They are normally located outside the building.
- The two most common types of mechanical draft towers to the HVAC industry are induced draft and forced draft.
- Induced draft towers have a large propeller fan at the top of the tower (discharge end) to draw air upward through the tower while warm condenser water spills down. This type requires much smaller fan motors for the same capacity than forced draft towers.
- Forced draft towers utilize a propeller fan at the bottom or side of the structure. Air is forced through the water spill area and discharged out the top of the structure.
- After the water has been cooled in the cooling tower, it is pumped to a heat exchanger or condenser in the refrigeration unit where it picks up heat again and is returned to the tower.
3. Which of the following is not a peak power plant?
Gas plant
Solar and wind power plant
Diesel power plant
Thermal power plant
Answer: Diesel power plant
Gas plant
Solar and wind power plant
Diesel power plant
Thermal power plant
Answer: Diesel power plant
Explanation:
The load is the amount of power in the electrical grid.
Baseload is the level that it typically does not go below, that is, the basic amount of electricity that is always required. Baseload is typically provided by large coal-fired and nuclear power stations. They may take days to fire up, and their output does not vary.
Examples of baseload power plants are:
Nuclear power plant
Coal or thermal power plant
Hydroelectric plant
Geothermal plant
Biogas plant
Biomass plant
Solar thermal with storage
Ocean thermal energy conversion
Peak load is the daily fluctuation of electricity use. It is usually lowest in the morning and highest in the early evening. It also varies seasonally. Peak load, the variable part of the electrical supply and demand, is provided by more responsive and smaller plants whose output can be quickly ramped up and down or that can even be quickly turned on and off.
Examples of peak load power plants are:
Gas plant
Solar power plants
Wind turbines
Diesel generators
Storage type hydro plants
4. The function of electrostatic precipitator in a coal-based thermal power plant is to:
A. Collect dust from flue gas
B. Clean the turbine blades
C. Collect dust at the air inlet
D. Collect dust from the coal
Answer: A. Collect dust from flue gas
Explanation:
Electrostatic precipitators (ESP):
- In electrostatic precipitators, the flue gas is made to pass through a highly ionised zone, where the particles get electrically charged and are separated out from the gas, with the help of electrostatic forces in the power full electric field.
- Electrostatic precipitator in a coal-based thermal power plant collects dust from flue gas.
- They are widely used in Thermal power plants, Pulp and Paper industries, Mining and Metallurgical Industries, Iron and Steel plants, Chemical industries, etc.
- The main two advantages of ESP are particles may be collected wet or dry and efficiency more than 99% can be achieved.
- ESP can handle both gases and mists for high volume flow and even very small particles can be removed.
- It uses very high voltage to generate a powerful electric field. Hence, power consumption is very high and subsequently, ESP is very costly as compared to other air pollution control devices.
5. In a Steam power plant, _________ heats the feed water on its way to the boiler by deriving heat from the flue gases.
A. Superheater
B. Economizer
C. Preheater
D. Turbine
Answer: B. Economizer
Explanation:
Superheaters:
It is used to dry the wet steam and raise the temperature of the steam above its saturation temperature. It is generally placed in the path of the furnace gases so as to utilize the heat from the hot flue gases.
Economizer:
Economizer:
It is also known as a feedwater heater. It is a device in which the waste heat of the flue gases is utilized for heating the feed water.
Air Preheater:
Air Preheater:
It is used to increase the temperature of the air before it enters the furnace. It is generally placed after the economizer; so that the flue gases pass through the economizer and then to the air preheater.
6. Which of the following generating power stations requires lot of time for starting?
A. Steam power station
B. Diesel power plant
C. Hydro-electric power plant
D. Nuclear power plant
Answer: A. Steam power station
6. Which of the following generating power stations requires lot of time for starting?
A. Steam power station
B. Diesel power plant
C. Hydro-electric power plant
D. Nuclear power plant
Answer: A. Steam power station
Explanation:
Steam power station:
- A generating station which converts heat energy of coal combustion into electrical energy is known as a steam power station.
- A steam power station basically works on the Rankine cycle. Steam is produced in the boiler by utilising the heat of coal combustion.
- The fuel (i.e., coal) used is quite cheap.
- Less initial cost as compared to other generating stations.
- It can be installed at any place irrespective of the existence of coal. The coal can be transported to the site of the plant by rail or road.
- It requires less space as compared to the hydroelectric power station.
- The cost of generation is lesser than that of the diesel power station.
Disadvantages:
- It pollutes the atmosphere due to the production of large amount of smoke and fumes.
- It is costlier in running cost as compared to hydroelectric plant.
- It requires lot of time for starting.
7. The overall efficiency of the steam power plant is defined as:
Answer:
Explanation:
The efficiency of Steam Power Station:
- The overall efficiency of a steam power station is low (about 29%) due mainly given reasons.
- Firstly, a huge amount of heat is lost in the condenser.
- Secondly, heat losses occur at various Stages of the plant.
- We cannot avoid the heat lost in the condenser. It is because heat energy cannot be converted into mechanical energy without temperature difference.
- The greater the temperature difference, the greater is the heat energy converted into mechanical energy.
- Therefore we have to keep the steam in the condenser at the lowest temperature. But the greater temperature difference causes a greater amount of heat lost.
Thermal Efficiency:
The ratio of heat equivalent of mechanical energy transmitted to the turbine shaft to the heat of combustion of coal is known as thermal efficiency of the steam power station.
The thermal efficiency of a modern steam power station is about 30%.
Overall efficiency:
The thermal efficiency of a modern steam power station is about 30%.
Overall efficiency:
The ratio of heat equivalent of electrical output to the heat of combustion of coal is known as the overall efficiency of the steam power station.
The overall efficiency of the Thermal Power Plant is about 29% because there is an approximation of 1% loss in the Alternator.
8. The part of the steam power plant that extracts heat from the flue gases before applying to the boiler is the ________.
A. super heater
B. draught system
C. condenser
D. economiser
Answer: D. economiser
The overall efficiency of the Thermal Power Plant is about 29% because there is an approximation of 1% loss in the Alternator.
8. The part of the steam power plant that extracts heat from the flue gases before applying to the boiler is the ________.
A. super heater
B. draught system
C. condenser
D. economiser
Answer: D. economiser
Explanation:
Economizer:
It is also known as a feedwater heater. It is a device in which the waste heat of the flue gases is utilized for heating the feed water.
In economizer, feed water is preheated to improve overall efficiency and only sensible heat transfer is taking place so feed water is heated without converting it into steam. Therefore, the economizer is placed after the superheater and located in the feeding water circuit.
Following are the advantages:
- There is about 15 to 20% of coal saving.
- It increases the steam raising capacity of a boiler because it shortens the time required to convert water into steam.
- It prevents the formation of scale in boiler water tubes.
Condensers:
A condenser is a device that condenses the steam at the exhaust of the turbine.
Superheaters:
Superheaters:
It is used to dry the wet steam and raise the temperature of the steam above its saturation temperature. It is generally placed in the path of the furnace gases so as to utilize the heat from the hot flue gases.
9. The prime mover used in thermal power plant is
A. wind turbine
B. steam turbine
C. PV cell
D. Francis Turbine
Answer: B. steam turbine
9. The prime mover used in thermal power plant is
A. wind turbine
B. steam turbine
C. PV cell
D. Francis Turbine
Answer: B. steam turbine
Explanation:
Prime Mover:
Prime Mover is a machine that used to convert another form of energy into rotational energy or mechanical energy for driven the shaft of Alternator to create revolving flux or cut the stationary flux for the generation of electrical energy.
Example: Steam turbine, gas turbine, water turbine, etc
The Prime Mover used in various power plant:
Types of Power Plant VS Prime Mover
10. Economizers are used to heat:
A. condensed steam
B. air
C. steam
D. feed water
Example: Steam turbine, gas turbine, water turbine, etc
The Prime Mover used in various power plant:
Types of Power Plant VS Prime Mover
- Thermal Power Plant----Steam Turbine
- Nuclear Power Plant----Steam Turbine
- Low Head Hydro Power Plant----Francis Turbine, Kaplan Turbine
- Medium Head Hydro Power Plant----Francis Turbine
- High Head Hydro Power Plant---Impulse Turbine
10. Economizers are used to heat:
A. condensed steam
B. air
C. steam
D. feed water
Answer: D. feed water
Explanation:
Economizer:
- It is also known as feed water heater. It is a device in which the waste heat of the flue gases is utilised for heating the feed water.
- In a steam boiler, it is a heat exchanger device that heats up fluids or recovers residual heat from the combustion product i.e. flue gases in a thermal power plant before being released through the chimney.
- Economiser is situated before air pre-heater in the flue gas path.
- Economiser increases the efficiency of the power plant.
Important Points:
Air preheater:
- Air preheaters are used in large boilers found in thermal power stations producing electric power.
- An air preheater or air heater is a general term to describe any device designed to heat air before another process (for example, combustion in a boiler) with the primary objective of increasing the thermal efficiency of the process.
- The purpose of the air preheater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas.
Superheater:
- A superheater is a device used to convert saturated steam or wet steam into superheated steam or dry steam
- Superheated steam is used in steam turbines for electricity generation, steam engines, and in processes such as steam reforming
- While the temperature of the steam in the superheater rises, the pressure remains the same as that of the boiler.
11. Which of the following methods is a conventional method of electrical energy generation?
A. Photovoltaic cells
B. Fuel cells
C. Wind power plant
D. Thermal power plant
Answer: D. Thermal power plant
Explanation:
Energy resources can be classified into two categories:
Renewable source (Non-conventional energy)
- Renewable energy resources are natural resources that can be regenerated continuously and are inexhaustible. They can be used again and again in an endless manner.
- Examples are Wood, Solar energy, wind energy, hydropower, tidal energy, geothermal energy, Biomass Energy etc.
Non-Renewable source (Conventional energy)
- Non-Renewable energy resources are natural resources that can not be regenerated once they are exhausted. They cannot be used again.
- Examples are Oil, Coal, petroleum, natural gas, nuclear fuels, hydel power, thermal power etc.
12. The overall efficiency of a steam power plant is about
A. 56%
B. 29%
C. 45%
D. 66%
Answer: B. 29%
Explanation:
The overall efficiency of the steam power plant is about 29%.
- Steam power plant----28 – 35%
- Nuclear power plant----40 – 45%
- Diesel engine power plant----35 – 42%