Simulation And Analysis Of Heating Process In Rotary Hearth Furnace

The rotary hearth furnace is important heating equipment on the production line of seamless steel tube, and its control operation level directly influences the tube billet heating quality,output,energy-consumption and also affects composite economic results. It is a pressing concern to enhance its automation control in thermal process to a higher level. The accomplishment of on-line optimization control can achieve remarkable economic benefit and energy-saving effect. And the thermal process mathematical model of heating furnace is fundamental to conducting on-line control.Mathematical model of the thermal process of cylindrical billet in rotary hearth furnace was established in this thesis. Element balance method was used to deduce the heat conduction differential equation under the two-dimensional column coordinate of the cylindrical billet. Triangular net and non-uniform two-dimensional grids were employed to discretize the temperature field of the furnace bottom. Considering the thermal contact resistance between trough and cylindrical billet, total heat absorption rate method was used to compute the temperature field of the coupling boundary of the two. The expression of the surface heat flux which distributed along the cylindrical billet was deduced and the distribution curve was drawn. All above laid the foundation for the dynamic simulation of the temperature field of cylindrical billet and furnace bottom.The result of simulation indicated that the furnace bottom functioned as heat source at the early stage of heating, and along with the heating process, it became the major factor that caused the warming lag of the cylindrical billet's underpart. Through an analysis of the temperature field of the furnace bottom, significant difference is found from that of one-dimensional temperature field at the initial stage of heating. However, along with the process of heating, the difference gradually diminished. When gaps in the troughs changed within ten times the average distance, the temperature in the center of the cylindrical billet changes little. And when the actual contact area increased from 60% to 80%, the distribution of heat flux along the circumferential billet of the cylindrical surface was uneven yet the temperature in the billet center did not change significantly.Based on the mathematical model, the way to optimize furnace temperature setting of rotary hearth furnace was studied in this paper. The author introduced the principles of the heuristic method and how to establish the model in this way. And at last we got an optimized curse of furnace temperature. The author also compared the optimized results and non-optimized results and analyzed the effect of this optimized method. The result of simulation indicated that optimized furnace temperature can meet the production requirements and achieve the effects of energy-conservation.