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Steam calculations

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Homework Statement


The maximum steam pressure by the turbineintake is 550 C. Based on available cooling water the pressure in the condensor will be 0,06bar the isentropic efficency is 80 %. Decide the steam pressure at the turbine intake if the steam content is at least 90 %

We have struggled with this question for a while and would appreciate any help we can get.
 

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  • #2
SteamKing
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Homework Statement


The maximum steam pressure by the turbineintake is 550 C. Based on available cooling water the pressure in the condensor will be 0,06bar the isentropic efficency is 80 %. Decide the steam pressure at the turbine intake if the steam content is at least 90 %
I assume you mean the vapor quality of the exhaust steam is 90%
We have struggled with this question for a while and would appreciate any help we can get.
Please don't delete parts of the HW Template.

Simply saying that you've struggled to answer a problem is not showing sufficient effort to solve the problem. :frown:

You must show actual calculations to that effect and tell us exactly where you are having difficulty in proceeding to a solution. :wink:
 
  • #3
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Yes thats exactly what i mean, well we need somewhere to start since we cant find any sufficient formulas in our textbook :)
 
  • #4
SteamKing
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Yes thats exactly what i mean, well we need somewhere to start since we cant find any sufficient formulas in our textbook :)
Well, it's going to take more than one formula to solve this problem. Your going to need either a Mollier diagram or a set of steam tables.

It's not clear what the turbine inlet conditions are. You mentioned the inlet temperature of 550 °C but called it pressure by mistake. Are you supposed to find the maximum turbine inlet pressure to satisfy the efficiency and the exit conditions?

Please post the actual problem statement verbatim.

Your book should have a formula for calculating isentropic efficiency. If not, you can find one on the internet.
 
  • #5
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Okay well translated as good as we can, the problem
When planning a steam power plant process, we have decided to have a maximal steam temperature of 550 degrees celsius at the turbine inlet. Based on available cooling water the pressure in the condensor will be 0,06 bar. The isentropic efficiency of the turbine is 80%. Decide the steam pressure at the turbine inlet, IF the vapor quality in the turbine exhaust have to be atleast 90 %.
 
  • #6
SteamKing
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Okay well translated as good as we can, the problem
When planning a steam power plant process, we have decided to have a maximal steam temperature of 550 degrees celsius at the turbine inlet. Based on available cooling water the pressure in the condensor will be 0,06 bar. The isentropic efficiency of the turbine is 80%. Decide the steam pressure at the turbine inlet, IF the vapor quality in the turbine exhaust have to be atleast 90 %.
OK.

This page shows you the definition of isentropic efficiency of the turbine, in case you haven't located it in your textbook:

http://www.learnthermo.com/T1-tutorial/ch08/lesson-C/pg03.php

The rest of the problem involves using steam tables or a Mollier diagram (enthalpy v. entropy) to determine the turbine inlet pressure which satisfies your conditions.

You may have to make several trial solutions to find one which is best for your purposes. Good Luck!
 
  • #7
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Okay thank you very much !!
 

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