Method of operating a gas turbine assembly and the gas turbine assembly

1. A method of operating a gas turbine assembly, which includes a compressor, a combustor, a gas turbine, and a heat recovery steam generator connected downstream the gas turbine, the method comprising:

operating the gas turbine assembly at a partial load with respect to a base load of the gas turbine assembly;

introducing at least a portion of an exhaust gas discharged from the gas turbine into an exhaust gas duct extending through the heat recovery steam generator;

bypassing a portion of blow-off air from the compressor; and

introducing the portion of blow-off air into the exhaust gas duct after the heat recovery steam generator with the at least the portion of the exhaust gas discharged from the gas turbine, in which the portion of blow-off air is fed via a bearing strut housing, a bearing strut, a diffuser casing, a circumferential loop distributor or a diffuser strut.

2. The method according to claim 1 , further comprising:

adjusting a flow mass of the portion of the blow-off air with a control valve.

3. The method according to claim 1 , wherein the operating of the gas turbine assembly at the partial load with respect to the base load of the gas turbine assembly comprises:

operating the gas turbine assembly at 30% to 50% relative load.

4. The method according to claim 1 , further comprising:

emitting carbon monoxide and nitrogen oxide from the gas turbine assembly during the operating of the gas turbine assembly at the partial load.

5. The method according to claim 1 , further comprising:

maintaining a constant air-to-fuel ratio in the combustor; and

controlling a combustion flame temperature of the combustor at a level where emissions are kept below a permissible limit by bypassing the portion of the blow-off air from the compressor into the exhaust gas duct.

6. The method according to claim 1 , further comprising:

introducing the portion of blow-off air into the exhaust gas duct after the heat recovery steam generator from multiple exit holes in a bypass line.

7. The method according to claim 1 , further comprising:

reducing a temperature of the exhaust gas from the gas turbine with the portion of the blow-off air.

8. A gas turbine assembly, comprising:

a compressor for compression of inlet air;

a combustor for combustion of a fuel gas with the compressed inlet air to form an exhaust gas;

a gas turbine for expansion of the exhaust gas to drive a load, wherein the gas turbine includes an exhaust gas duct;

a heat recovery steam generator connected downstream of the gas turbine, the exhaust duct extending through the heat recovery steam generator; and

a bypass line leading from a blow-off point of the compressor into the exhaust gas duct after the heat recovery steam generator, in which a portion of blow-off air is fed via a bearing strut housing, a bearing strut, a diffuser casing, a circumferential loop distributor and/or a diffuser strut into the exhaust gas duct, and the portion of blow-off air is combined with the exhaust gas from the gas turbine in the exhaust gas duct.

9. The gas turbine assembly according to claim 8 , further comprising:

a control valve is disposed in the bypass line to adjust a flow mass of the blow-off air.

10. The gas turbine assembly according to claim 8 , wherein the gas turbine assembly is operated at a partial load with respect to a base load of the gas turbine assembly, and wherein the partial load of the gas turbine assembly is 30% to 50% relative load.

11. The gas turbine assembly according to claim 10 , wherein the gas turbine assembly emits carbon monoxide and nitrogen oxide during the operating of the gas turbine assembly at the partial load.

12. The gas turbine assembly according to claim 8 , wherein a constant air-to-fuel ratio is maintained in the combustor, and a combustion flame temperature of the combustor is controlled at a level where emissions are kept below a permissible limit by bypassing the portion of blow-off air from the compressor into the exhaust gas duct.

13. The gas turbine assembly according to claim 8 , wherein the portion of blow-off air is introduced into the exhaust gas duct after the heat recovery steam generator from multiple exit holes in the bypass line, and a temperature of the exhaust gas from the gas turbine is reduced with the blow-off air.

14. A method of operating a gas turbine assembly, which includes a compressor, a combustor, a gas turbine, and a heat recovery steam generator connected downstream the gas turbine, the method comprising:

operating the gas turbine assembly at a partial load with respect to a base load of the gas turbine assembly, the partial load being 30% to 50% relative load;

introducing at least a portion of an exhaust gas discharged from the gas turbine into an exhaust gas duct extending through the heat recovery steam generator;

bypassing a portion of blow-off air from the compressor; and

introducing the portion of blow-off air into the exhaust gas duct after the heat recovery steam generator with the exhaust gas from the heat recovery generator.

15. The method according to claim 14 , further comprising:

adjusting a flow mass of the portion of the blow-off air with a control valve.

16. The method according to claim 14 , further comprising:

emitting carbon monoxide and nitrogen oxide from the gas turbine assembly during the operating of the gas turbine assembly at the partial load.

17. The method according to claim 14 , further comprising:

maintaining a constant air-to-fuel ratio in the combustor.

18. The method according to claim 14 , further comprising:

controlling a combustion flame temperature of the combustor at a level where emissions are kept below a permissible limit by bypassing the portion of blow-off air from the compressor into the exhaust gas duct.

19. The method according to claim 14 , further comprising:

introducing the portion of blow-off air into the exhaust gas duct after the heat recovery steam generator from multiple exit holes in a bypass line.

20. The method according to claim 14 , further comprising:

reducing a temperature of the exhaust gas from the gas turbine with the blow-off air.