In a gas turbogroup, which comprises a compressor, a first combustion chamber, a first turbine, a second combustion chamber, and a second turbine, the first combustion chamber is arranged downstream of the compressor, the first turbine is arranged downstream of the first combustion chamber, the second combustion chamber is arranged downstream of the first turbine, and the second turbine is arranged downstream of the second combustion chamber, wherein the second combustion chamber has a convectively cooled wall. A cooling air feed line for the second combustion chamber branches from the main flow path of the gas turbogroup downstream of the compressor and upstream of the first combustion chamber. A return line for heated cooling air leads from the second combustion chamber upstream of the first turbine to the main flow path.
1. A gas turbogroup, comprising a compressor, a first combustion chamber, a first turbine, a second combustion chamber, and a second turbine, wherein the first combustion chamber is arranged downstream of the compressor, the first turbine is arranged downstream of the first combustion chamber, the second combustion chamber is arranged downstream of the first turbine, and the second turbine is arranged downstream of the second combustion chamber, in which gas turbogroup the second combustion chamber has a convectively cooled wall, wherein a cooling air feed line for the second combustion chamber branches from the main flow path of the gas turbogroup downstream of the compressor and upstream of the first combustion chamber, and wherein a return line for heated cooling air leads from the second combustion chamber upstream of the first turbine to the main flow path.
2. The gas turbogroup as claimed in claim 1 , wherein the return line leads to the first combustion chamber.
3. The gas turbogroup as claimed in claim 1 , wherein the return line leads to the main flow path upstream of the first combustion chamber.
4. The gas turbogroup as claimed in claim 3 , wherein the return line leads to a plenum of the first combustion chamber.
5. The gas turbogroup as claimed in claim 4 , wherein the return line of the cooling air leads to burners of the first combustion chamber.
6. The gas turbogroup as claimed in claim 3 , wherein the return line of the cooling air leads to burners of the first combustion chamber.
7. The gas turbogroup as claimed in claim 6 , wherein the return line of the cooling air is specifically guided to individual burners of the first combustion chamber.
8. The gas turbogroup as claimed in claim 3 , wherein the return line leads to the compressor.
9. The gas turbogroup as claimed in claim 1 , wherein the return line leads to the compressor, preferably upstream of the last one to four stages.
10. The gas turbogroup as claimed in claim 9 , wherein an auxiliary compressor is arranged in the cooling air feed line.
11. The gas turbogroup as claimed in claim 1 , wherein an auxiliary compressor is arranged in the cooling air feed line.
12. The gas turbogroup as claimed in claim 11 , wherein the return line leads to the region of a flow constriction of a convergent-divergent flow element.
13. The gas turbogroup as claimed in claim 1 , wherein the return line leads to the region of a flow constriction of a convergent-divergent flow element.