High Firing Temperature GT36 H-Class Low NOX Combustor Engine Validation and Performance

In order to minimize footprint on the environment of human activities, technologies to reduce greenhouse gases while meeting always growing electricity demands are critical. Amongst the various sources of energy production, Gas Turbines (GT) are an efficient way to stabilize the grid with regards to renewable sources like wind and solar energies. H-class Gas Turbine market drives then naturally for higher efficiency, higher power output while reducing emissions (especially NO and NO2) levels at high loads. Development and validation of a 2 stages sequential combustor, so-called Constant Pressure Sequential Combustion (CPSC), to achieve these goals have been accomplished by Ansaldo Energia. The CPSC consists of a premix burner system (First Stage) and of a sequential burner (SB) in a series in a can combustor. This paper focuses on the last step of this development process, test engine validation. At last year conference, high pressure test rig validation results of the CPSC were introduced. The advantages with regards to fuel flexibility, hydrogen combustion and low emissions at high firing temperature were presented. The second generation of sequential combustion concept was developed and applied on the new GT36 H-class gas turbine combustor. This article focuses on the validation of the combustor performance in the Birr engine test facility which includes detailed validation from ignition to full speed no load, part load operation and full load over various ambient and engine thermal state conditions. To allow for detailed validation, dedicated fully instrumented combustor cans were installed in the GT. Detailed validated air distribution and emission models support the results obtained on the engine.  Ignition and ramps to full speed no load have been validated with large variations of first combustor stage firing temperature to minimize power consumption and start-up time. Full speed no load combustor stability was also demonstrated for various variable inlet guide vanes (VIGV) positions. The potential of the CPSC is revealed with regards to turndown capabilities with minimum environmental load (MEL) below 25% GT load while keeping low CO levels. The MEL can be kept low over a wide range of ambient temperature and fuel composition by adjusting the inlet temperature of the sequential burner. Low NOx values were achieved at baseload and peak firing temperature. The operational flexibility and stability of the premixed first stage combustor over the load range and large variation of combustor inlet plenum pressure was as well validated along with the operation concept of the gas turbine.