A THERMAL SYSTEM MODEL FOR A RADIANT-TUBE CONTINUOUS REHEATING FURNACE

A thermal system mathematical model developed for a gas-fired radiant- tube continuous reheating furnace is discussed. The mathematical model of the furnace integrates submodels for combustion and heat transfer within the radiant tube with models for the furnace enclosure. The tra nsport processes occurring in the radiant tube are treated using a one -dimensional scheme, and the radiation exchange between the load, the radiant-tube surfaces, and the furnace refractories are analyzed using the radiosity method. The continuous furnace operation is simulated u nder steady-state conditions. Model simulations of load surface temper ature variation compare well with measurements in an industrial galvan nealing furnace. The scope and flexibility of the model are assessed b y performing extensive parametric studies using furnace geometry, mate rial properties, and operating conditions as input parameters in the m odel and predicting the thermal performance of the furnace. The variou s parameters studied include the effects of load and refractory emissi vities, load velocities, properties of the stock material, and variati ons in the radiant-tube designs.