EDIT: After looking a little closer, I would say the white object IS for the big flame, and the small hose and nozzle at the bottom of the picture are a pilot light/ignition source through which the large nozzle will blast propane.
I concur. That is indeed what it appears to be. Problem is, I can't seem to make all of that steel fit the concept art. The black steel would shoot through the dome I would think.