Abstract: There is provided an improvement in a recuperator of the type having an elongated flow passage defined by an inner heat exchanger wall wherein the flow passage has a selected cross-sectional shape, a lower hot gas entrant end adjacent the gas outlet of a heating furnace and an upper gas exit end above and axially aligned with the lower end of the passage. The improvement involves the use of a radiator member in the form of a plug reciprocably mounted within said passage and movable axially within the passage between a normal plug position adjacent the upper end of the flow passage and a furnace capping position adjacent the lower end of the flow passage.

Abstract: A method and system is provided for controlling a reheating furnace having entrance and discharge ends, a preheating zone at the entrance end, and heating and soaking zones sequentially adjacent the preheating zone in the direction toward the discharge end, and an exhaust gas flue at the entrance end. The method and control system provides for obtaining an optimum temperature profile through the preheating and heating zones with minimum fuel consumption in connection with operation of the preheating zone by controlling the fuel supply to the preheating zone in accordance with the rate or quantity of fuel flow to the heating zone and the temperature of the exhaust gas from the furnace.