AN IMPROVED MATHEMATICAL MODEL TO PREDICT THE REAL TIME TRANSIENT PERFORMANCE OF A LARGE STEEL REHEATING FURNACE

This paper describes the development and application of a two-dimensional model based on the zone method of radiation analysis to simulate the thermal behaviour of a large steel reheating furnace at Tata Steel. The furnace has a maximum throughput of 160 t/hr of steel blooms and is equipped with a total of 75 burners firing a mixture of combustible fuel gases arising from the steelmaking process. The model was validated for two different furnace throughput rates using experimental and plant data supplied by Tata Steel. Following validation it was then used to assess the furnace performance at a wider range of throughputs as well as examining the effect of the distribution of heat input along the furnace on furnace efficiency and stock temperature uniformity. The model differs from previous work since it takes into account the radiation interchange between the top and bottom firing sections of the furnace and also allows for enthalpy exchange due to the flows of combustion products between these sections. The results to-date showed that the model predictions are in good agreement with typical heating profile of the stock encountered in the actual furnace and are potentially suitable for incorporation into a model based furnace control system due to its relatively fast computing time.