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Driven by global warming, a relentless march towards increased fuel efficiency has resulted in increased firing temperature for HA-class engines without an increase in baseload emissions. Moreover, emissions compliance for CO, NOx, and unburned hydrocarbons are desired over increased range in gas turbine load. In addition, exceptional gas turbine operational flexibility is desired to address potential intermittency due to the penetration of renewables in the electrical grid. Staged/sequential combustion is a state of the technology to provide operational flexibility and reduced emissions in power generation gas turbines. GE Power’s 7HA-class gas turbine combustion system combines GE’s proven DLN-2.6+ combustion technology, that has run reliably for over 1.3 million fired hours across more than eighty 9FA.03, 9F.05 & 7FA gas turbine engines, with an axially fuel staged system (AFS). Axially staging combustion to two zones allows for increased firing temperature at baseload (while maintaining the same NOx level) by operating the later/second stage hotter than the first/primary stage. During low load operation as the gas turbine firing temperature is reduced, percentage fuel split in the staged fuel system can either be reduced significantly or turned off and thereby keeping the overall combustion system into emissions compliance over a wider range of firing temperatures. This paper presents both the development testing of the staged combustion in the FA and HA class gas turbine combustion system rigs at GE Power’s Gas Turbine Technology Laboratory and the validation testing of staged combustion system for the 7HA.01 engine completed during Spring 2016 at GE Power’s engine test facility in Greenville, SC. The paper also discusses the significant simplification of operational principle and flexibility of startup, loading and baseload operation of the 7HA combustion system. Discussion of engine test results will show how axial fuel staging was utilized to demonstrate emissions compliance ( NOx (15% O2) < 25 ppm; CO < 9 ppm), operation from 14% load to 100% load with low combustion dynamics and also to enable wide wobbe capability, which is a normalized measure of fuel flexibility.

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A new rich-catalytic lean-burn combustion concept (trademarked by PCI as RCL) was tested at industrial gas turbine conditions, in Solar Turbines’ high-pressure (17 atm) combustion rig and in a modified Solar Turbines engine, demonstrating ultralow emissions of NOx<2 ppm and CO<10 ppm for natural gas fuel. For the single-injector rig tests, an RCL catalytic reactor replaced a single swirler/injector. NOx<3 ppm and CO<10 ppm were achieved over a 110°C operating range in flame temperature, including NOx<1 ppm at about 1350°C flame temperature. Combustion noise was less than 0.15% peak to peak. Four RCL catalytic reactors were then installed in a modified (single can combustor) engine. NOx emissions averaged 2.1 ppm over the allowable operating range for this modified engine, with CO<10 ppm and without combustion noise (less than 0.15% peak to peak).

This paper describes the design and testing of a catalytically-stabilized pilot burner for current and advanced Dry Low NOx (DLN) gas turbine combustors. In this paper, application of the catalytic pilot technology to industrial engines is described using Solar Turbines’ Taurus 70 engine. The objective of the work described is to develop the catalytic pilot technology and document the emission benefits of catalytic pilot technology when compared to higher, NOx producing pilots. The catalytic pilot was designed to replace the existing pilot in the existing DLN injector without major modification to the injector. During high pressure testing, the catalytic pilot showed no incidence of flashback or autoignition while operating over wide range of combustion temperatures. The catalytic reactor lit off at a temperature of approximately 598K (325°C/617°F) and operated at simulated 100% and 50% load conditions without a preburner. At high pressure, the maximum catalyst surface temperature was similar to that observed during atmospheric pressure testing and considerably lower than the surface temperature expected in lean-burn catalytic devices. In single injector rig testing, the integrated assembly of the catalytic pilot and Taurus 70 injector demonstrated NOx and CO emission less than 5 ppm @ 15% O2 for 100% and 50% load conditions along with low acoustics. The results demonstrate that a catalytic pilot burner replacing a diffusion flame or partially-premixed pilot in an otherwise DLN combustor can enable operation at conditions with substantially reduced NOx emissions.

A new Rich-Catalytic Lean-burn combustion concept (trademarked by PCI as RCL) was tested at industrial gas turbine conditions, in Solar Turbines’ high-pressure (17 atm) combustion rig and in a modified Solar Turbines engine, demonstrating ultra-low emissions of NOx < 2 ppm and CO < 10 ppm for natural gas fuel. For the single-injector rig tests, an RCL catalytic reactor replaced a single swirler/injector. NOx < 3 ppm and CO < 10 ppm were achieved over a 110 C operating range in flame temperature, including NOx < 1 ppm at about 1350 C flame temperature. Combustion noise was less than 0.15% peak-to-peak. Four RCL catalytic reactors were then installed in a modified (single can combustor) engine. NOx emissions averaged 2.1 ppm over the allowable operating range for this modified engine, with CO < 10 ppm and without combustion noise (less than 0.15% peak-to-peak).

This paper discusses some of the advanced concepts and research and development associated with implementing catalytic combustion to achieve ultra-low-NOx emissions in the next generation of land-based gas turbine engines. In particular, the paper presents current development status and design challenges being addressed by Siemens Westinghouse Power Corp. for large industrial engines (>200 MW) and by Solar Turbines for smaller engines (<20 MW) as part of the U.S. Department of Energy’s (DOE) Advanced Turbine Systems (ATS) program. Operational issues in implementing catalytic combustion and the current needs for research in catalyst durability and operability are also discussed. This paper indicates how recent advances in reactor design and catalytic coatings have made catalytic combustion a viable technology for advanced turbine engines and how further research and development may improve catalytic combustion systems to better meet the durability and operability challenges presented by the high-efficiency, ultra-low emissions ATS program goals. [S0742-4795(00)01502-7]