Dynamic modeling of the heat pipe-assisted annealing line

Abstract

In a conventional continuous annealing line, the energy supplied to steel strip during heating is not recovered while cooling it. Therefore, an alternative heat transfer technology for energy efficient continuous annealing of steel was developed. This technology enables reusing the heat extracted during cooling of the strip in the heating part of the process. This is achieved by thermally linking the cooling strip to the heating strip via multiple rotating heat pipes. In this context, the dynamic simulation of a full heat pipe assisted annealing line is performed. The dynamic simulation consists of the interaction of computational building blocks, each comprising of a rotating heat pipe and strip parts wrapped around the heat pipe. The simulations are run for different installation configurations and operational settings, with the heat pipe number varying between 50 and 100 and with varying strip line speed and dimensions. The heat pipes are sized to be 0.5 m in diameter and 3 m in length. The simulation results show that the equipment is capable of satisfying the thermal cycle requirements of annealing both at steady-state and during transition between steady-states following changes in boundary conditions. With this concept, energy savings of up to 70% are feasible.