Electrical Engineering XYZ MCQs
Which of the following contributes to the Rankine cycle efficiency improvement in a thermal power plant:
- Reheat of steam an intermediate stages
- Use of high pressure
- Use of steam for heating of boiler feed water
- All of the above
Correct answer: 4. All of the above
Explanation: All of the above is correct answer.
- Reheat of steam at intermediate stages: In a Rankine cycle, after the steam expands through the turbine, it is condensed back into water and then reheated before entering the turbine again. This reheat process helps to increase the average temperature at which heat is added to the steam, thus increasing the efficiency of the cycle. Reheating reduces the moisture content in the steam, which in turn reduces the erosion and corrosion of turbine blades, leading to improved efficiency and turbine longevity.
- Use of high pressure: Higher pressure in the Rankine cycle means that more work can be extracted from the steam in the turbine. According to the Rankine cycle principle, increasing the pressure at which the steam is generated and expanding it through the turbine increases the work output. This is because higher pressure leads to a higher temperature at which heat is added to the steam, resulting in improved thermodynamic efficiency.
- Use of steam for heating of boiler feed water: Preheating the boiler feed water with steam extracted from the turbine helps to increase the temperature of the water before it enters the boiler. This reduces the amount of fuel needed to raise the temperature of the water to the operating level, thereby improving overall efficiency. By utilizing waste heat from the steam cycle to preheat the feed water, less heat is lost to the surroundings, resulting in a more efficient use of energy.
Each of these factors contributes to the overall efficiency improvement in a thermal power plant utilizing the Rankine cycle. Therefore, the correct answer is indeed “All of the above.”