Calculation Model, Influencing Factors, and Dynamic Characteristics of Strip Temperature in a Radiant Tube Furnace during Continuous Annealing Process

Strip temperature control is central to the continuous annealing process, and a strip temperature calculation model is necessary to realize accurate and stable strip temperature control. This paper focuses on the radiant tube furnace (RTF), which is the most important and most difficult to control in the continuous annealing process. A calculation model of strip temperature distribution is established using the heat balance method, which is suitable for online control. The model is verified to be accurate and reliable based on the measured data. On this basis, the influencing factors of strip temperature distribution in RTFs are further analyzed. The results show that strip thickness, line speed, and the radiant tube temperature of each column have significant influence on strip temperature distribution, while strip width has little influence. Furthermore, the dynamic characteristics of strip temperature under different working conditions are also investigated. The results reflect that strip temperature at the RTF exit has different response times, and amplitudes to the change of line speed, strip thickness, and radiant tube temperature. After changing the process parameters, the re-stabilization process of strip temperature shows a significant time lag.