when gas turbine is running on low load then any effect on gas turbine efficiency

 

Gas turbines normally get less efficient at low loads.

 

Take a look at the performance curves for the unit. I think you will find that the lowest heat rate (peak efficiency) occurs at the design point. That says that any deviation from the design point will reduce efficiency. In general, the bigger the deviation, the greater the impact on efficiency.

 

1-At the FSNL you have to consume some amount of gas to rotate turbıne shaft. thıs amount of gas is constant. We will call it "X" afterward.
2-you have to consume gas for producing electricity. you will consume "Y" unıt gas per Mw

assume that you are at 210Mw. Than your gas consumption per Mw is (X + Y)/210
assume that you are at 260Mw. Than your consumption is (X+Y)/260
it is so obvious that (x+y)/260 is less than (x+y)/210
that means you are at a higher efficiency in higher megawatts.

regards..