Patent ID: 8894407

Claim:
A combustor, comprising: an end cover coupled to one end of a casing, the casing at least partially surrounding the combustor housing; an end cap assembly that extends radially and circumferentially within the casing with respect to an axial centerline of the combustor, the end cap assembly including an upstream plate, a downstream plate, a circumferentially extending cap shield that extends axially therebetween, a fuel plenum defined within the end cap assembly and a tube bundle, the tube bundle comprising a plurality of tubes that provide for fluid communication through the upstream surface, the fuel plenum and the downstream surface; a first fuel conduit that extends from the end cover and through the fuel plenum of the end cap; and a fuel duct external to the conduit that spirals around and makes contact with the conduit for heat exchange, the conduit between the end cover and the upstream surface, wherein the duct extends through the upstream surface and provides for fluid communication between the end cover and the fuel plenum; and a barrier that extends radially inside the end cap assembly with respect to an axial centerline of the end cap assembly to at least partially define the fuel plenum, wherein the barrier axially separates the fuel plenum from a diluent plenum, where the fuel plenum is upstream of the diluent plenum, defined inside the end cap assembly with respect to the axial centerline of the combustor, wherein the conduit extends inside the diluent plenum to provide fluid communication to the diluent plenum.