RFG Compressor in Power plant

RFG on Google.com came up with a lot of Info.

RFG stands for Recirculated Flue Gas
Flue Gases are the gases produced as a result of combustion of fossil fuel, like in a thermal power plant or other places where boilers are used.
It is a prcatise followed in order to limit the formation of NOX gases, at the expense of reduced heat generation capacity of the boilder.
These flue gases are re-introduced into the chamber where the fossil fuel is burnt. by means of a compressor, called RFG Compressor :)
Due to the presence of these flue gases, the percentage of oxygen in the chamber is reduced. As a result of this suppresion of combustion process, the flame reaches a lower temperature which is not sufficient enough for the formation of NOX gases

Since the natural pressure gradient from the exhaust back to the combustion chamber may not permit the flow of the Flue Gas, a compressor has to be used for this purpose

BTW
was your query about RFG compressors, related to the Flue Gas or Refinery Fuel Gas, as you have just pointed out in another thread

I should have clearly mentioned in the Query :-"Refinery fuel gas" Compressor.

Though my query was related to "Refinery fuel gas" Compressor,details furnished about "Recirculated Flue Gas" are useful and informative.

Well in that case, the compressor is to be used in order to supply the the Gas turbine with pressurised fuel for combustion, with provision to be provided in the compressor to remove any condensed fuel

1. Are there two compressors in GT circuit - one for Air, and other for Fuel Gas?

2.Are these two compressors also run with the same shaft of Gas turbine?

1.) AFAIK Fuel gas compressors for power plant are specialised eqpt designed with the sole purpose of compressing the fuel to be used in the Gas turbine.

2.)The shaft of the air compressor is directly coupled to the shaft of the Gas Turbine. However, there may be provision of a seperately powered air compressor, that functions only @ the initial stage of turbine operation, when the turbine is not rotating fast enough to run the main air compressor @ required speed. Once this speed is achieved, the seperately powered air compressor is stopped and the Main Air compressor take over.
As for the fuel gas compressor, it too has its own shaft that is coupled with the Shaft of the Gas turbine, using suitable mechanism, inorder to recieve adequate power to operate.