Sequential combustion arrangement with dilution gas

1. A sequential combustor arrangement, comprising:

a first combustor with a first burner for admitting a first fuel into a combustor inlet gas during operation;

a first combustion chamber for burning the first fuel;

a dilution gas admixer for admixing a dilution gas to the first combustor combustion products when leaving the first combustion chamber; and

a second combustor with a second burner for admixing a second fuel and a second combustion chamber, wherein the first combustor, the dilution gas admixer, the second burner and second combustion chamber are arranged sequentially in a fluid flow connection, wherein a pressure loss coefficient of the first combustor and a pressure loss coefficient of the dilution gas admixer are configured so that during base load operation a ratio of pressure loss of the first combustor to pressure loss of the dilution gas admixer is in a range of 2 to 12 such that operation of the admixer occurs at a constant momentum flux ratio and there is a homogenous temperature profile for an inlet of the second combustor, the constant momentum flux ratio being a ratio between a first momentum flux of a dilution gas flow of the dilution gas fed into the dilution gas admixer and a second momentum flux of a flow of the first combustor combustion products admitted to the dilution gas admixer; and

wherein a reference cross section for the pressure loss coefficient of the first combustor is a cross section at an exit of the first combustion chamber and a reference cross section for the pressure loss coefficient of the admixer is the cross section at the exit of the first combustion chamber.

2. The sequential combustor arrangement as claimed in claim 1 , wherein the ratio of the pressure loss of the first combustor to the pressure loss of the dilution gas admixer is in a range of 3 to 10.

3. The sequential combustor arrangement as claimed in claim 1 , wherein the ratio of the pressure loss of the first combustor to the pressure loss of the dilution gas admixer is in a range of 5 to 8.

4. The sequential combustor arrangement as claimed in claim 1 , wherein the dilution gas admixer comprises:

at least one streamlined body which is arranged in the dilution gas admixer for introducing dilution gas into first combustion products leaving the first combustion chamber during operation through at least one nozzle.

5. The sequential combustor arrangement as claimed in claim 1 , comprising:

a feeder for dilution gas which connects a compressor plenum to the dilution gas admixer.

6. The sequential combustor arrangement as claimed in claim 5 , comprising:

a dilution gas control valve is arranged in the feeder for dilution gas.

7. The sequential combustor arrangement as claimed in claim 6 , wherein the dilution gas control valve and the feeder for dilution gas are configured to inject dilution gas from a compressor plenum into combustion products emitted by the first combustor that flow through the dilution gas admixer to adjust a ratio of (i) the first momentum flux of dilution gas being injected to (ii) the second momentum flux of the combustion products being admitted into the dilution gas admixer as a function of an operating parameter of a gas turbine.

8. The sequential combustor arrangement as claimed in claim 7 , wherein the operating parameter is relative load or a gas temperature of the second combustor or a gas temperature of the first combustor.

9. The sequential combustor arrangement as claimed in claim 7 , wherein the dilution gas control valve and the feeder for dilution gas are configured so that the ratio of the first momentum flux to the second momentum flux is maintained as a constant ratio.

10. The sequential combustor arrangement as claimed in claim 1 , wherein the first and second combustors are configured in a sequential can-can architecture.

11. The sequential combustor arrangement as claimed in claim 1 , first combustor is configured as a can-architecture and the second combustor is configured as an annular combustion chamber.

12. A gas turbine comprising:

a compressor;

a turbine; and

a sequential combustor arrangement according to claim 1 arranged between the compressor and the turbine.

13. The gas turbine of claim 12 , wherein the ratio of the pressure loss of the first combustor to the pressure loss of the dilution gas admixer is in a range of 3 to 10.

14. The gas turbine of claim 12 , wherein the ratio of the pressure loss of the first combustor to the pressure loss of the dilution gas admixer is in a range of 5 to 8.

15. The gas turbine of claim 12 , wherein the sequential combustor arrangement also comprises a feeder for dilution gas which connects a compressor plenum to the dilution gas admixer.

16. The gas turbine of claim 15 , wherein the sequential combustor arrangement also comprises a dilution gas control valve arranged in the feeder for dilution gas.

17. The gas turbine of claim 12 , wherein the dilution gas admixer comprises:

at least one streamlined body which is arranged in the dilution gas admixer for introducing dilution gas via at least one nozzle into first combustion products leaving the first combustion chamber.

18. The gas turbine of claim 17 , wherein the sequential combustor arrangement also comprises:

a feeder for dilution gas which connects a compressor plenum to the dilution gas admixer; and

a dilution gas control valve arranged in the feeder for dilution gas.