Furnace with integrated heat recovery utilizing radiative recuperator for preheating combustion reactants using heat from flue gas

A method of recuperative heat exchange for preheating a combustion reactant with waste heat energy from flue gas produced by a furnace, comprising:

• injecting fuel and oxidant from one or more burners mounted in a furnace wall of a furnace into a combustion space within a combustion chamber enclosed by the furnace wall and combusting the injected fuel and oxidant in the combustion space thereby heating solid and/or molten glass or glassmaking materials or solid and/or molten metal and producing flue gas, at least one of the fuel and oxidant being preheated;
• receiving the flue gas at a first end of a duct extending along an axis, one or more portions of the duct being comprised of a material having a thermal conductivity of greater than 1 W/(m·K);
• discharging the received flue gas from a second end of the duct;
• exchanging heat between the flue gas and the duct by radiative heat exchange;
• exchanging heat between the duct and one or more metallic pipes by radiative heat exchange across an non-reactive gas space filled with non-reactive gas, the one or more metallic pipes extending through the non-reactive gas space, the non-reactive gas space being defined between an outer surface of the duct and an inner surface of an insulating wall that extends parallel to the duct axis and adjacent the outer surface of the duct;
• exchanging heat between the one or more metallic pipes and either fuel or oxidant flowing through the pipes by convective heat exchange to provide preheated fuel or preheated oxidant;
• and
• feeding the preheated fuel or preheated oxidant to the one or more burners.