Combined Cycle Plant Efficiency
Combined Cycle Plant Efficiency
(OP)
Hello all,
I'm trying to get some idea of the electrical efficiencies that one might realistically expect to achieve with combined cycle plants consisting of two GT's and one steam turbine and, having an overall capacity rating of 60 MW or less.
Has anyone had any practical operating experience with such a system who could help me out?
Best Regards,
vtpwringeniero
I'm trying to get some idea of the electrical efficiencies that one might realistically expect to achieve with combined cycle plants consisting of two GT's and one steam turbine and, having an overall capacity rating of 60 MW or less.
Has anyone had any practical operating experience with such a system who could help me out?
Best Regards,
vtpwringeniero






RE: Combined Cycle Plant Efficiency
Electrical efficiencies are given by the mfg. of the equipment.
However if you mean plant efficiencies that is totally different.
Which do you want?
RE: Combined Cycle Plant Efficiency
RE: Combined Cycle Plant Efficiency
I'm looking for efficiencies based on electrical output and heat input and, a measure of efficiency based on electrical output + heat for process as compared to heat input.
One formula that I've come across is:
% eff = [{(Rated kW)(3412BTU/kWh) + BTU/hr recovered for process)}/Heat input in BTU/hr] x 100%.
We have been told of electrical efficiencies only, reaching 60% and efficiencies based on electricity and supplimental heat available for process reaching 90%. Intuitively, since a gas turbine operating on simple cycle has an efficiency of only 25% or so, these values seem excessive. However, I've had no experience with combined cycle plants to know for sure.
RE: Combined Cycle Plant Efficiency
Low ambient temperature in winter help to increase the efficiency. Operation altitude significantly above sea level and less than full gas turbine output produces lower efficiency.
Efficiency also could be reduced over time, around 3% over time requiring maintenance or overhaul periodically. There are small none recovered efficiency.
RE: Combined Cycle Plant Efficiency
http://www.gepower.com/publications/en_us/pdf/GER4206.pdf
cuky2000's 55% is probably a good number for newer systems - older ones will be less.
RE: Combined Cycle Plant Efficiency
RE: Combined Cycle Plant Efficiency
Thanks to all who replied. You've helped.
Best Regards,
vtpwringeniero