Patent ID: 7469489
Filing Date: 2008-12-30
Classification: F23C

Abstract:
1. A method relating to the operation of a thermal unit for heating or cooling the interior of a furnace, said method comprising: flowing gases through an inner pipe out into an outer pipe which has a closed bottom and which surrounds the inner pipe; redirecting the gases that exit the inner pipe back through a volume between the outer pipe and the inner pipe; placing an inner bottom plate in the outer pipe in spaced relationship with the closed bottom of said outer pipe, wherein the inner bottom plate extends across the cross-section of the outer pipe and is substantially perpendicular to the longitudinal axis of the outer pipe to define an insulating gas pocket between the bottom of the outer pipe and the inner bottom plate, whereby gases flowing through the inner pipe and out into the outer pipe impinge against the inner bottom plate and turn to pass between the outer pipe and the inner pipe.