Effects of Furnace Length on the Thermal Performance of a Walking Beam Reheating Furnace

Abstract

The influence of furnace length on several key performance indicators of a reheating furnace such as the fuel consumption, thermal efficiency and through-thickness temperature uniformity of a discharged slab was investigated. Energy balance equations of radiation set up by the zone method were solved by coupling them with the heat conduction equations of the slab. The zone model was validated by actual data collected during an instrumented slab trial. The simulation results showed that the model predictions were in good agreement with actual measurements. Under the premise that the throughput rate and the total fuel consumption were fixed, every additional meter of the preheating zone length increased the slab discharge temperature by about 10.75 °C and decreased the exhaust temperature by about 13.29 °C, but made no change in the section temperature difference in the slab at discharge; every additional meter of the soaking zone length decreased the section temperature difference in the slab at discharge by about 2.88 °C, but made a somewhat gentle change in the slab discharge temperature and exhaust temperature. For the existing furnace, the actual length was not suitable to be changed, so the relative length was defined as representing the actual length, which could be indirectly changed by adjusting the current fuel consumption. After optimization, the relative lengths of the preheating zone and soaking zone increased by five meters and one meter, respectively, while the relative lengths of the first and second heating zones decreased by five meters and one meter, respectively, and the section temperature difference in the slab at discharge, exhaust temperature and fuel consumption simultaneously decreased.