This paper describes reduced NOx diffusion flame combustors that have been
developed for both simple cycle and regenerative cycle MS3002 and MS5002 ga
s turbines. Laboratory tests have shown that when firing with natural gas,
without water or steam injection, NOx emissions from the new combustors are
about 40 percent lower than NOx emissions front the standard combustors. C
O emissions are virtually unchanged at base load, but, increase at part loa
d conditions. Commercial demonstration tests have confirmed the laboratory
results. The standard combustors on both the MS3002 and MS5002 gas turbine
are cylindrical cans, approximately 10.5 inches (27 cm) in diameter. A sing
le fuel nozzle is centered at the inlet to each can and produces a swirl st
abilized diffusion flame. The walls of the cans are louvered for cooling, a
nd contain tin array of mixing and dilution holes that provide the air need
ed to complete combustion and dilute the burned gas to the desired turbine
inlet temperature. The MS3002 turbine is equipped with six combustor cans,
while the MS5002 turbine is equipped with twelve combustors. The new, reduc
ed NOx, emissions combustors (referred to as a "lean head end," or LHE, com
bustors) retain, all of the key features of the conventional combustors; th
e only major difference is the, arrangement of the mixing and dilution hole
s in the cylindrical combustor cans. By optimizing the number diameter, and
location of these holes, NOx emissions can be reduced considerably. Minor
changes are also sometimes made to the combustor cap. The materials of cons
truction, pressure drop, and fuel nozzle are all unchanged. The differences
in NOx emissions between the standard and LHE combustors, as well cis the
variations in NOx emissions with firing temperature, are well correlated us
ing turbulent flame length arguments. Details of this correlation are prese
nted.