- #1
Marshiewoo
- 4
- 0
Task:
A steady flow boiler takes in feed water at 1.5kg/s, at a temperature of 30 °C. The water is heated and turned into wet steam. This leaves at 1.5kg/s, with a pressure of 10 bar and a dryness fraction of 0.97 to the superheater, where it receives heat at a constant pressure and emerges at a temperature of 400 °C.
Determine, using steam tables:
A. the rate of thermal energy transfer in the boilet
B. the rate of thermal energy transfer in the superheater
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I have managed to find out the efficiency of the turbine, which is after the superheater.
I am not really looking for an answer, although that would be fantastic. I would mainly like somebody to explain the difference between what I have worked out (below) and what the question above is asking.
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My attempt at a different task which is slightly related:
Thank you and my apologies for the terrible use of the fantastic itex system.
A steady flow boiler takes in feed water at 1.5kg/s, at a temperature of 30 °C. The water is heated and turned into wet steam. This leaves at 1.5kg/s, with a pressure of 10 bar and a dryness fraction of 0.97 to the superheater, where it receives heat at a constant pressure and emerges at a temperature of 400 °C.
Determine, using steam tables:
A. the rate of thermal energy transfer in the boilet
B. the rate of thermal energy transfer in the superheater
--------------------------------------------------------------------------------
I have managed to find out the efficiency of the turbine, which is after the superheater.
I am not really looking for an answer, although that would be fantastic. I would mainly like somebody to explain the difference between what I have worked out (below) and what the question above is asking.
--------------------------------------------------------------------------------
My attempt at a different task which is slightly related:
Steam enters the turbine below from the superheater at a pressure of 20 bar and temperature 300 °C and exhaustss at a pressure of 1 bar and dryness fraction 0.95. The steam consumption rate is 1.8 tonnes per hour and the shaft output power is 0.2 MW.
Determine the turbine efficiency.
[itex]\hat{m}[/itex] = 0.5 kg/s
[itex]T\omega[/itex] = 0.2[itex]x10^6[/itex]
Temperature in = 300 °C
Pressure in = 20 bar
Pressure out = 1 bar
Dryness fraction out = 0.95
h1)
h1 = [itex]hg[/itex] @ 20 bar & 300 °C
= 3025000
h2)
h2 = [itex]hf + xhfg[/itex] @ 1 bar
= 417 + (0.95)(2258)
= 2563000
h1 - h2 = 463000
Turbine Efficiency)
Turbine Efficiency = [itex]\frac{T\omega}{(h1-h2)\hat{m}}[/itex]
= [itex]\frac{0.2x10^6}{(463000)(0.5}[/itex]
= 0.86393
= 86.4%
Thank you and my apologies for the terrible use of the fantastic itex system.