NOx Emissions from Stationary Gas Turbines - US Environmental ...

for natural gas and oil fuels, respectively.
The decision whether to use water versus steam injection for
NO reduction depends on many factors, including the availability
x
of steam injection nozzles and controls from the turbine
manufacturer, the availability and cost of steam at the site, and
turbine performance and maintenance impacts. This decision is
usually driven by site-specific environmental and economic
factors.
A system that allows treated water to be mixed with the fuel
prior to injection is also available. Limited testing of water-
in-oil emulsions injected into the turbine combustor have
achieved NO reductions equivalent to direct water injection but
x
at reduced water-to-fuel rates. The vendor reports a similar
system is available for natural gas-fired applications.
Dry low-NO combustion control techniques reduce NO
x x
emissions without injecting water or steam. Two designs, lean
premixed combustion and rich/quench/lean staged combustion have
been developed.
Lean premixed combustion designs reduce combustion
temperatures, thereby reducing thermal NO . Like wet injection,
x
this technique is not effective in reducing fuel NO . In a
x
conventional turbine combustor, the air and fuel are introduced
at an approximately stoichiometric ratio and air/fuel mixing
occurs simultaneously with combustion. A lean premixed combustor
design premixes the fuel and air prior to combustion. Premixing
results in a homogeneous air/fuel mixture, which minimizes
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