Dual fuel ultra-low NOX combustor

In a gas turbine having a compressor for producing compressed air, a combustor comprising:

• a) a shell forming a combustion zone in which a fuel is burned in compressed air;
• b) a fuel/air pre-mixing zone enclosed by a first liner, said first liner enclosing second and third liners, a first annular passage formed between said first and second liners and a second annular passage formed between said second and third liners, each of said annular passages having an inlet in flow communication with said compressor and an outlet in flow communication with said shell, whereby a portion of said compressed air from said compressor flows through each of said annular passages, said pre-mixing zone having a flow area defined by an inner diameter of said first liner at said first passage outlet, said shell having a flow area adjacent said passage outlets defined by an inner diameter of said shell, said shell inner diameter being at least about 40% greater that said first liner inner diameter, whereby said compressed air flowing through said passages undergoes an expansion upon exiting said passages;
• c) means for introducing a fuel into each of said passages;
• and
• d) means, disposed within said passages, for mixing said fuel introduced into each of said annular passages with said compressed air flowing through said passages.