Procedure and arrangement for the recovery of thermal energy during the heat treatment of cold rolled steel tape in a bell furnace for annealing

摘要

Procedure for the recovery of thermal energy during the heat treatment of cold rolled steel tape (2) in a bell furnace for annealing (4), where the steel tape (2) is heated under an atmosphere of protective gas up to a temperature higher than the recrystallization temperature and is then subjected, in a subsequent first phase of slow cooling (Pslow) and a second phase of rapid cooling (Pfast) which takes place following the first phase of slow cooling (Pslow), to the action of a protective gas (6), whose temperature is reduced during the first phase (Pslow) to an intermediate temperature (Tint), in particular 400 ° C and in the second phase from the intermediate temperature to a final temperature (Tend), in Particularly lower than 80 ° C, characterized in that a first heat exchanger (8) is provided that is passed through the protective gas (6) exclusively in the first phase (Pslow) and that transfers the energy thermal guidance of the protective gas (6), through a closed oil circuit (10) and a second heat exchanger (12; 12.1; 12.2; 12.3), to a working medium (14), which at normal pressure has a boiling temperature below 80 ° C, in particular below 70 ° C, and which evaporates in the second heat exchanger (12; 12.1; 12.2; 12.3) and is driven to a steam engine (16) that transforms part of the thermal energy contained in the working medium (14) into mechanical and / or electrical energy, and because an additional heat exchanger (18) is provided that is crossed by the protective gas (6) exclusively in the second phase of rapid cooling (Pfast) and in which the thermal energy contained in the protective gas (6) is transferred to an additional heat transport means (22), preferably water, for heating water for industrial use (20).