Industrial Gas Turbine Engine Catalytic Pilot Combustor-Prototype Testing (2010)

PCI has developed and demonstrated its Rich Catalytic Lean-burn (RCL®) technology for industrial and utility gas turbines to meet DOE's goals of low single digit emissions. The technology offers stable combustion with extended turndown allowing ultra-low emissions without the cost of exhaust after-treatment and further increasing overall efficiency (avoidance of after-treatment losses). The objective of the work was to develop and demonstrate emission benefits of the catalytic technology to meet strict emissions regulations. Two different applications of the RCL® concept were demonstrated: RCL® catalytic pilot and Full RCL®. The RCL® catalytic pilot was designed to replace the existing pilot (a typical source of high NOx production) in the existing Dry Low NOx (DLN) injector, providing benefit of catalytic combustion while minimizing engine modification. This report discusses the development and single injector and engine testing of a set of T70 injectors equipped with RCL® pilots for natural gas applications. The overall (catalytic pilot plus main injector) program NOx target of less than 5 ppm (corrected to 15% oxygen) was achieved in the T70 engine for the complete set of conditions with engine CO emissions less than 10 ppm. Combustor acoustics were low (at or below 0.1 psi RMS) during testing. The RCL® catalytic pilot supported engine startup and shutdown process without major modification of existing engine controls. During high pressure testing, the catalytic pilot showed no incidence of flashback or autoignition while operating over a wide range of flame temperatures. In applications where lower NOx production is required (i.e. less than 3 ppm), in parallel, a Full RCL® combustor was developed that replaces the existing DLN injector providing potential for maximum emissions reduction. This concept was tested at industrial gas turbine conditions in a Solar Turbines, Incorporated high-pressure (17 atm.) combustion rig and in a modified Solar Turbines, Incorporated Saturn engine rig. High pressure single-injector rig and modified engine rig tests demonstrated NOx less than 2 ppm and CO less than 10 ppm over a wide flame temperature operating regime with low combustion noise (<0.15% peak-to-peak). Minimum NOx for the optimized engine retrofit Full RCL® designs was less than 1 ppm with CO emissions less than 10 ppm. Durability testing of the substrate and catalyst material was successfully demonstrated at pressure and temperature showing long term stable performance of the catalytic reactor element. Stable performance of the reactor element was achieved when subjected to durability tests (>5000 hours) at simulated engine conditions (P=15 atm, Tin=400C/750F.). Cyclic tests simulating engine trips was also demonstrated for catalyst reliability. In addition to catalyst tests, substrate oxidation testing was also performed for downselected substrate candidates for over 25,000 hours. At the end of the program, an RCL® catalytic pilot system has been developed and demonstrated to produce NOx emissions of less than 3 ppm (corrected to 15% O2) for 100% and 50% load operation in a production engine operating on natural gas. In addition, a Full RCL® combustor has been designed and demonstrated less than 2 ppm NOx (with potential to achieve 1 ppm) in single injector and modified engine testing. The catalyst/substrate combination has been shown to be stable up to 5500 hrs in simulated engine conditions.