Ultra Low NOx Using Rich Catalytic/Lean-Burn Catalytic Pilots: Gas Turbine Engine Test

Lean premixed (LP) combustion is limited to a minimum NOx of 5–9 ppm due to flame stability. To improve flame stability and lower NOx, an advanced Rich Catalytic Lean-burn technology was developed and integrated to replace only the injector pilot with catalyst modules. This system focuses on replacing the highest temperature zone of the LP combustion system with a catalytic pilot (which can stabilize the main flame at reduced equivalence ratio) to reduce overall NOx emissions. This concept synergistically combines the best features of catalytic and aerodynamically stabilized combustion technologies. During Taurus 70 (T70) engine testing of a set of injectors equipped with catalyst modules for natural gas applications, emissions at baseload conditions were NOx of ∼ 2.5 ppmv and CO less than 2 ppm, both corrected to 15% O2 . Low single digit emissions were achieved from 50% to 100% load. Combustor acoustics were low (below 0.1 psi/690 Pa) during testing. Reactor catalyst temperature was within the design limit and no-preburner was required. The initial emissions results are promising providing an alternative to conventional LP technology for less than 5 ppm NOx systems. Further development work is needed to establish engine integration and long term catalyst durability before advancing to production.Copyright © 2009 by ASME