Consider the following statements regarding effects of heating of stea...
Heating of steam increases specific output of turbine and improves the quality of exit steam.
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Consider the following statements regarding effects of heating of stea...
Effects of Heating of Steam in a Steam Turbine
Heating of steam in a steam turbine can have various effects on the turbine performance and the quality of the exit steam. Let's analyze each statement in detail to determine which ones are correct.
Statement 1: It increases the specific output of the turbine
When steam is heated in a steam turbine, its temperature and pressure increase. This increase in temperature and pressure results in an increase in the specific volume of the steam. As a result, more energy can be extracted from the steam during expansion in the turbine, leading to an increase in the specific output of the turbine. Therefore, statement 1 is correct.
Statement 2: It decreases the cycle efficiency
The cycle efficiency of a steam turbine is determined by the heat input and the work output. Heating the steam to higher temperatures can increase the heat input to the turbine. However, it also increases the specific output of the turbine (as stated in statement 1), which means more work is extracted from the steam. If the increase in work output is greater than the increase in heat input, the cycle efficiency can actually improve. Therefore, statement 2 is incorrect.
Statement 3: It increases blade erosion
Heating the steam in a steam turbine can increase the temperature and pressure of the steam. This higher temperature and pressure can lead to increased erosion of the turbine blades due to the more aggressive nature of the steam flow. The high-energy steam can cause erosion and wear on the blade surfaces, leading to reduced efficiency and increased maintenance requirements. Therefore, statement 3 is correct.
Statement 4: It improves the quality of exit steam
The quality of the exit steam refers to the moisture content in the steam after it has passed through the turbine. Heating the steam can help in reducing the moisture content, thereby improving the quality of the exit steam. The higher temperature of the steam helps in evaporating any moisture present, resulting in drier steam at the turbine exit. Therefore, statement 4 is correct.
Conclusion
Based on the analysis above, we can conclude that statements 1 and 4 are correct. Heating of steam in a steam turbine increases the specific output of the turbine and improves the quality of the exit steam. However, statement 2 is incorrect as heating the steam does not necessarily decrease the cycle efficiency. Statement 3 is correct as heating the steam can lead to increased blade erosion.