A reformer furnace (1), comprising: at least one triple conduit
assembly (200), including a
flue gas conduit (220) enclosing a reaction conduit (240) enclosing a
product gas conduit (260), wherein: the reaction conduit (240) extends between a lower end (244) defining a reaction gas inlet (245), and a closed upper end (242); the
product gas conduit (260) extends between an upper end (262) defining a
product gas inlet (263), and a lower end (264) defining a product gas outlet (265); the
flue gas conduit (220) extends between an upper end (222) defining a
flue gas inlet (223), and a lower end (224) defining a
flue gas outlet (225); and an annulus (250) between the reaction conduit (240) and the product gas conduit (260) comprises a catalyst (252); a
combustion chamber (100) that encloses an approximate upper half (226, 246, 266) of the at least one triple conduit
assembly (200) while an approximate
lower half (228, 248, 268) thereof resides outside of and below the
combustion chamber, and that includes at least one burner (110), disposed inside of the
combustion chamber and outside of the
flue gas conduit (220), such that the approximate upper half (226) of the
flue gas conduit substantially shields the reaction conduit (240) from direct burner
flame heat
radiation and impingement.