NOVELTY - The recuperative reformer comprises a preheater section (110) and a reactor section (120). The preheater section comprises a first portion of a flue gas flow path (130) and a first portion of a reforming mixture flow path (140). The first portion of a reforming mixture flow path is partially embedded within the first portion of the flue gas flow path to permit heat transfer between a flue gas in the flue gas flow path and a reforming mixture in the reforming mixture flow path. The reactor section comprises a second portion of the flue gas flow path.    USE - The recuperative reformer is useful for reforming hydrocarbon fuel into higher calorific fuel and in a thermal waste recovery system (all claimed), which is useful in recuperators, regenerators, waste heat boilers and heating applications such as heat treat furnaces, melters, burners, engines and turbines.    ADVANTAGE - The recuperative reformer ensures efficient and economical reformation of the hydrocarbon fuel into the higher calorific fuel.    DETAILED DESCRIPTION - The recuperative reformer comprises a preheater section (110) and a reactor section (120). The preheater section comprises a first portion of a flue gas flow path (130) and a first portion of a reforming mixture flow path (140). The first portion of a reforming mixture flow path is partially embedded within the first portion of the flue gas flow path to permit heat transfer between a flue gas in the flue gas flow path and a reforming mixture in the reforming mixture flow path. The reactor section comprises a second portion of the flue gas flow path and a second portion of the reforming mixture flow path. The second portion of the reforming mixture flow path partially embedded within the second portion of the flue gas flow path to permit heat transfer between the flue gas in the flue gas flow path and the reforming mixture in the reforming mixture flow path. The flue gas flow path is configured to receive hot flue gas from a thermal process. The first portion of the reforming mixture flow path is configured to receive a gaseous reforming mixture having a volumetric flow rate. The second portion of the reforming mixture flow path is configured to receive the reforming mixture from the first portion of the reforming mixture flow path. A part of the second portion of the reforming mixture flow path contains extended surfaces of metal material. The second portion of the reforming mixture flow path is configured to provide residence time greater than or equal to a predetermined threshold (1 second to 2 minutes) for the reforming mixture having the volumetric flow rate. A volume of the second portion of the reforming mixture flow path is larger than a volume of the first portion of the reforming mixture flow path. A surface area of the extended metal surfaces in the second portion of the reforming mixture flow path is larger than the surface area required for efficient heat transfer between flue gas and reforming mixture. The first section of the reforming mixture flow path comprises a preheater plenum. The preheater plenum has a first portion positioned on one side of the first section of the flue gas flow path a second portion positioned on an opposite side of the first section of the flue gas flow path, conduits connecting the first portion of the preheater plenum and the second portion of the preheater plenum, and baffles present in the first and second portions of the preheater plenum to guide the reforming mixture into the conduits of the first section of the reforming mixture flow path. The second section of the reforming mixture flow path comprises a reactor plenum. The reactor plenum has a first portion positioned on one side of the second section of the flue gas flow path, a second portion positioned on an opposite side of the second section of the flue gas flow path, conduits connecting the first portion of the reactor plenum and the second portion of the reactor plenum, and baffles present in the first and second portions of the reactor plenum to guide the reforming mixture into the conduits of the second section of the reforming mixture flow path. The conduits connecting the first and second portions of the reactor plenum are pipes and plate-shaped channels. The flue gas flow path is configured so that the hot flue gas passes through the second portion of the flue gas flow path and then through the first portion of flue gas flow path. The volume of the second portion of the reforming mixture flow path provides a maximum space velocity of 3600 hr-1. INDEPENDENT CLAIMS are included for:    (1) a thermal waste recovery system; and    (2) a method of reforming hydrocarbon fuel into higher calorific fuel.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a non-catalytic recuperative reformer.    Preheater section (110)    Reactor section (120)    Flue gas flow path (130)    Reforming mixture flow path (140)    Plenum. (150)