A furnace stave comprising a plurality of internal channels or conduits for circulating cooling fluid through the stave; an inlet and an outlet channel associated with each internal channel; wherein the inlet channels of two internal channels are fed by the same inlet pipe or conduit. In another preferred aspect, the inlet channels of two internal channels fed by the same inlet pipe or conduit may or may not be overlapping or in fluid communication with each other.

A fluid cooled combustion can, comprising: an internal core housed in an intermediate core; wherein the inteimediate core is housed in an external housing; wherein an outer surface of the intermediate core defines one or more ribs that together with an inside surface of the external housing define a cooling fluid circuit that is in fluid communication with a cooling fluid inlet and outlet.