All questions of Basics of Power Generation for Electrical Engineering (EE) Exam

Understanding Air Preheaters in Steam Power Plants
Air preheaters play a crucial role in enhancing the efficiency of steam power plants. They provide several benefits, as indicated by the options in the question.
1. Raises the Temperature of the Furnace Gases
- Air preheaters increase the temperature of the combustion air before it enters the furnace.
- This rise in temperature contributes to more efficient combustion, ensuring optimal fuel utilization.
2. Recovers Heat from Flue Gases
- They are designed to recover heat from the flue gases that exit the economizer.
- This recovered heat is used to preheat the incoming air, reducing the overall energy consumption of the plant.
3. Improves Combustion Rate
- By supplying warmer air to the combustion process, air preheaters improve the combustion rate.
- Enhanced combustion leads to higher efficiency and reduced emissions, promoting a more sustainable operation.
4. Overall Impact
- The combined effect of these functions results in increased thermal efficiency of the power plant.
- Lower fuel consumption and reduced operational costs are significant outcomes of utilizing air preheaters.
Conclusion
- Therefore, the answer "All of the mentioned" (option D) is correct because air preheaters contribute to raising furnace gas temperatures, recovering heat from flue gases, and improving combustion rates.
- Their role is vital in maximizing efficiency and minimizing environmental impact in steam power plants.

Reflector in Nuclear Power Plants




Effect on Neutron Leakage:

- Decreases: The reflector in nuclear power plants is designed to reflect neutrons back into the reactor core, thereby decreasing neutron leakage.

- Explanation: Neutron reflectors are typically made of materials like graphite or heavy water, which have high neutron scattering cross-sections. When neutrons hit the reflector material, they are scattered back into the reactor core, increasing the probability of further fission events and reducing the chances of neutron leakage.

- Importance: Minimizing neutron leakage is crucial in maintaining a sustained chain reaction within the reactor core, which is necessary for the generation of nuclear power.

- Overall: Therefore, the presence of a reflector in nuclear power plants plays a vital role in reducing neutron leakage and optimizing the efficiency of the reactor.

D) graphite

Introduction:
Steam power plants are widely used in electric power generation due to several reasons. One of the key reasons is the significant difference between the work output of the turbine and the work input to the pump.

Explanation:
1. Higher work output:
- In a steam power plant, the steam generated from the boiler is expanded in a turbine, which converts the thermal energy of the steam into mechanical work.
- The work output of the turbine is directly proportional to the pressure and temperature of the steam entering the turbine.
- Steam power plants operate at high pressures and temperatures, allowing for a high work output from the turbine.
- This high work output ensures efficient conversion of thermal energy into mechanical energy, which can then be used to generate electricity.

2. Work input to the pump:
- The steam that exits the turbine is condensed back into water and then pumped back to the boiler to be reheated and converted into steam again.
- The pump is responsible for supplying the necessary pressure to the water to overcome the pressure drop that occurs in the condenser and other components.
- The work input to the pump is required to overcome the pressure difference between the condenser and the boiler.
- However, the work input to the pump is relatively small compared to the work output of the turbine.

3. Efficiency and power generation:
- The efficiency of a steam power plant is defined as the ratio of the useful work output to the heat input.
- Since the work output of the turbine is much larger than the work input to the pump, the net work output of the plant is significantly greater than the work input required to operate the pump.
- This results in a higher overall efficiency of the power plant.
- The higher work output from the turbine also means that more electricity can be generated from the same amount of fuel.

Conclusion:
Steam power plants are more popular in electric power generation because the work output of the turbine is very large compared to the work input required to operate the pump. This significant difference in work output allows for efficient conversion of thermal energy into mechanical work, resulting in higher overall efficiency and power generation capacity.