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Join Date: May 2012
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### How to Calculate Efficiency of a Power Plant When You Know Its Heat Rate [HHV] ?

07/05/2012 2:45 AM

I want to calculate Efficiency of an IPP while i know its Heat Rate. This particullar Plant is a combined cycle with diesel engines [ Wartsila] and a steam turbine [ PeterBrotherhood]. The Heat rate value is in kJ/kWh. I have read that we can calculate only energy efficiency through this value which seems legit. Also i came accross following equation while searching for this topic :

Efficiency = (860.4*4.18*100)/(Heat rate in kJ/kWh)
Why i am asking it here then ? Reason is that i am not sure if this equation applies to a combined cycle plant like the one mentioned above.

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#1

### Re: How to Calculate Efficiency of a Power Plant When You Know Its Heat Rate [HHV] ?

07/06/2012 12:02 AM

Your efficiency will probably run between 52% and 56%....

"To avoid confusion, the efficiency of heat engines and power stations should be stated HHV (aka Gross Heating Value) or LCV (aka Net Heating value), and whether Gross output at the generator terminals or Net Output at the power station fence are being considered.

In general in service Combined Cycle efficiencies are over 50 percent on a lower heating value and Gross Output basis. Most combined cycle units, especially the larger units, have peak, steady state efficiencies of 55 to 59%. Research aimed at 1370°C (2500°F) turbine inlet temperature has led to even more efficient combined cycles and 60 percent efficiency has been reached in the combined cycle unit of Baglan Bay, a GE H-technology gas turbine with a NEM 3 pressure reheat boiler, utilising steam from the HRSG to cool the turbine blades. Siemens AG announced in May 2011 to have achieved a 60.75% net efficiency with a 578 megawatts SGT5-8000H gas turbine at the Irsching Power Station.[1]"

http://en.wikipedia.org/wiki/Combined_cycle#Efficiency_of_CCGT_plants

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#2

### Re: How to Calculate Efficiency of a Power Plant When You Know Its Heat Rate [HHV] ?

07/06/2012 8:02 PM

Tony; Please pardon my interruption into this communication.

Solar Eagle;

Have you any experience with or know what affect adding water injection sprays into the turbine exhaust for curbing NOX emissions will do to the efficiency rating? (Formulae?) (Anyone?)

Also; Any idea what degree of oxidation and errosion might we expect to see inside the stack as it is high carbon steel?

I am currently pursuing restoration of a 60 MW, 4 Unit, circa 1973 CCPP (NG/Oil) with GE compressors that require updating/lowering the emissions in order to meet current EPA standards and receive an operating license permit.

This is just one of the presented options that on the surface seems reasonably easy to do and is highly cost effective.

Any sites or documentation available on the subject that I can access for review and argument?

Thx,

Jim