Consider the following statements for analysis of steam cycles: 1. A steam power plant continuously converts the energy stored in fossil fuels or fissile fuels into shaft work. 2. Steam power plants work on Brayton cycle. 3. In supercritical steam cycle, steam is generated in a 'once-through' boiler at a pressure above the critical point of 27.5 bar. 4. Deaerator is used for the purpose of deaerating the feedwater. Which of the above statements are correct?

Consider the following statements for analysis of steam cycles: 1. A steam power plant continuously converts the energy stored in fossil fuels or fissile fuels into shaft work. 2. Steam power plants work on Brayton cycle. 3. In supercritical steam cycle, steam is generated in a 'once-through' boiler at a pressure above the critical point of 27.5 bar. 4. Deaerator is used for the purpose of deaerating the feedwater. Which of the above statements are correct? Correct Answer 1 and 4 only

Explanation:

Steam Power Plant:

A steam power plant continuously converts the energy stored in fossil fuels (coal, oil, natural gas) or fissile fuels (uranium, thorium) into shaft work and ultimately into electricity.

The working fluid is water which is sometimes in the liquid phase and sometimes in the vapor phase during its cycle of operations.

Rankine Cycle:

Rankine cycle:

Rankine cycle is an ideal cycle of heat engine which uses water and steam as a working fluid to generate power with the help of a steam turbine.

Supercritical Boiler:

• A steam generator or boiler which operates at pressures above then the critical pressure of working fluid (220 bar for water) is called a supercritical boiler.
• Critical pressure is the pressure at which liquid water immediately converts into steam without any latent heat transfer.
• They are also called a once-through boiler because the entire process of heating, steam formation and superheating is done in a single continuous tube. Feeds pumps feed water to economizer from where it goes to the radiant heating section at the pressure above then the critical pressure. So it does not contain headers and steam separators
• It is a drumless boiler.
• Benson boiler is an example of a supercritical boiler.

Deaerator

• Deaerator removes dissolved gases like O2, CO2 etc. from feed water which is used for steam generation in the boiler.
• It is done by heating water to its boiling temperature.