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Associate

Join Date: Nov 2011
Posts: 34

### Combined Cycle Efficiency According to ST Exhaust Temperature

10/19/2012 8:38 AM

Hello. I understand that combined cycle power output decreases when ST exhaust temperature is higher.

However, I wish to know if the combined cycle efficiency also must be decreased when ST exhaust temperature is higher or it can make the same in the plant construction phase through optimization of HRSG, Heat Recovery Steam Generator.

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Guru

Join Date: Oct 2007
Location: India
Posts: 1272
Good Answers: 33
#1

### Re: Combined Cycle Efficiency According to ST Exhaust Temperature

10/19/2012 11:42 AM

You are invited to follow the LINKS, it is likely, that you may find your answer. You will, I am sure, definitely learn a thing or two, improve your knowledge base on ST.

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Guru

Join Date: Feb 2010
Posts: 887
Good Answers: 30
#2

### Re: Combined Cycle Efficiency According to ST Exhaust Temperature

10/21/2012 12:12 PM

In such systems, the proper matching of the prime mover output with the requirement in steam energy is the key to high efficiency.

If the prime mover (engine) is running at the same output (power) whilst the exhaust temperature is fluctuating between higher and lower temperature, this will mean that the Steam generator output is fluctuating (The demand for steam power is fluctuating). Therefore, the unabsorbed heat from the exhaust will make the exhaust temperature to rise, and when the steam demand increases, then the exhaust temperature will decrease.

Since the HRSG is the item contributing to the increased efficiency of the combined cycle as a unit, you should now make your conclusions to justify what you said in your question.

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