Method for the utilization of waste heat from pig iron production in rotary hearth furnaces

摘要

Evaluating the waste heat produced from pig iron production in rotating furnaces comprises after burning a waste gas (1) containing residual amounts of CO and H2 in a steam generator (2) together with combustion air (3) to form an inert process gas; forming hot vapor (4) by heat exchange; and super heating the hot vapor by heat exchange with the process gas in super heating stages. The process gas is withdrawn in partial streams (6,7) at different temperature levels. The receiving gas temperatures are regulated by the amount and/or temperature of the combustion air. The temperature level of a first partial stream withdrawn from the steam generator is matched with the process gas for pre-heating crude ore. The temperature level of a second partial stream withdrawn from the steam generator is matched with the process gas for drying coal. Preferred Features: The process gas partial stream (6) is withdrawn at a temperature of 1000-1200 deg C and the partial stream (7) leaves the generator at a temperature of 750-900 deg C.