ANS:B - passing it through a pressure reducing valve.

Converting dry saturated steam into superheated steam involves raising the temperature of the steam above its saturation temperature without changing its pressure or moisture content. This process is essential in many industrial applications where high-temperature steam is required for various purposes such as power generation, heating, and drying. There are several methods to achieve superheating, but one common method is by passing dry saturated steam through a pressure reducing valve. Here's a more detailed explanation of this process:

1. Initial State: Dry saturated steam is a state where steam is at its saturation temperature corresponding to its pressure. It is typically produced by heating water until it reaches its boiling point and then allowing it to vaporize.
2. Pressure Reduction: Dry saturated steam is passed through a pressure reducing valve, also known as a pressure regulator or throttle valve. This valve reduces the pressure of the steam while maintaining its enthalpy constant.
3. Isoenthalpic Expansion: As the pressure of the steam is reduced, it undergoes an isenthalpic expansion. During this process, the enthalpy of the steam remains constant while its temperature and volume increase.
4. Temperature Increase: The reduction in pressure causes the steam to expand, leading to an increase in its temperature above the saturation temperature. This rise in temperature results in the steam becoming superheated.
5. Superheated Steam: The steam exiting the pressure reducing valve is now superheated, meaning it has a temperature higher than its saturation temperature at the reduced pressure. Superheated steam is characterized by its dryness and higher energy content compared to saturated steam.

Superheated steam offers several advantages over saturated steam, including improved thermal efficiency, better control over temperature, and reduced risk of condensation in piping systems. It is commonly used in power plants, industrial boilers, steam turbines, and various manufacturing processes where precise temperature control and high heat transfer rates are essential.