Steam Turbine Question(s)

In summary, the conversation discusses a system in which steam is expanded through a high pressure turbine and then a low pressure turbine, with a portion being bled off to a feed heater. The rest of the steam is then expanded to a dryness fraction of 0.93. The questions focus on calculating the isentropic efficiencies of both turbines, the percentage of steam bled off, the power generated by the turbines, and the energy available for low grade heating. The solution involves using steam tables and making assumptions, such as assuming adiabatic conditions for the open feedwater heater.
  • #1
PieD94
1
0

Homework Statement


[/B]
Steam is expanded from 90 bar, 412°C to 4.5 bar saturation in a high pressure turbine, after-which a certain percentage of the steam is bled off to a feed heater. The remaining steam is then expanded through a low pressure turbine to 1.0 bar and dryness fraction of 0.93. All ‘steam’ entering the feed pumps shall be a saturated fluid. Produce a schematic diagram of the system, together with appropriate T-s diagram. Using steam tables only, calculatea) the isentropic efficiencies of both turbines

b) the percentage of steam bled of to the feed heater

c) the power generated by the turbines per unit mass of steam leaving the boiler

d) the energy available for low grade heating from the condenser


Neglect feed pumps and state any assumptions made



Homework Equations

The Attempt at a Solution

(a) Isentropic Efficiency = (h1-h2/h1-h2s)

= (3152-2745)/(3152-2525)

=407/627

= 0.6491

Isentropic Efficiency for high pressure turbine= 65%

(b) Assuming that the open feedwater heater is adiabatic.

Im not sure if a is right and as for the other questions, I am stumped. any help is appreciated. I am getting 0.63/0.64 for question b) however I've a feeling that is far too high
 
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  • #2
For part a) how did you go about calculating the dryness fraction at after the the superheated steam to the 4.5 bars ?Also, you should try to start off with the schematic and the T-s diagram as it will help a lot.
 

What is a steam turbine?

A steam turbine is a device that converts thermal energy from pressurized steam into mechanical energy, which can then be used to generate electricity or power machinery.

How does a steam turbine work?

A steam turbine works by using pressurized steam to rotate a series of blades, which are connected to a central shaft. As the steam passes through the blades, it causes them to spin, generating mechanical energy.

What are the main components of a steam turbine?

The main components of a steam turbine include the rotor, blades, casing, and steam inlet and outlet. The rotor is the central shaft that rotates, while the blades are attached to it and spin with the rotor. The casing surrounds the rotor and blades, and the steam inlet and outlet allow for the flow of steam into and out of the turbine.

What is the purpose of a steam turbine?

The purpose of a steam turbine is to convert thermal energy into mechanical energy, which can then be used to generate electricity or power machinery. Steam turbines are commonly used in power plants to produce electricity from steam generated by burning fossil fuels or nuclear reactions.

What are the advantages of using a steam turbine?

There are several advantages to using a steam turbine. It is a highly efficient and reliable method of converting thermal energy into mechanical energy, making it a popular choice for power generation. Steam turbines also have a long lifespan and require minimal maintenance, making them a cost-effective option. Additionally, steam turbines can be easily scaled to fit different power generation needs, from small-scale applications to large power plants.

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