Combustion system. The system includes a combustor generating a combustion gas and a splitter for receiving the combustion gas and dividing the combustion gas into first and second gas streams. A temperature controller receives the first gas stream, mixes it with recycled gas and introduces it into a heat recovery steam generator at a desired temperature. A mixer receives the second gas stream, mixes it with recycled gas and introduces it into the heat recovery steam generator. The cool gas that exits the heat recovery steam generator forms the recycled gas. A suitable combustor is an oxy-coal combustor.