The Research On Numerical Simulation And Structure Improvement Of Galvannealing Furnace In Hot-dip Galvanized Line

In recent years, among the zinc-and zinc alloy-coated steels used in automotivebodies, galvannealed (GA) sheets were the most widely accepted due to their superior spotweldability, corrosion resistance, paintability and improved resistance to scratching.Galvannealing furnace as the key equipment in continuous hot-dip galvanizing line, thetemperature distribution in the furnace directly affects the quality of hot dip galvanizedsheet. As a result, through numerical simulation and experimental measurement to fullyunderstand the thermal process in the furnace, it has the theoretical significance andpractical guiding significance to produce hot galvanized sheet with good the formabilityand powdering resistance.Take the soaking section and the cooling section of galvannealing furnace as researchobjects, the numerical simulation, experimental test and structure improvement were made.The main work of this thesis includes:(1) The physical3D models of the soaking section and the cooling section ofgalvannealing furnace were established, and the computational domains were divided intocells by ICEM CFD software. In accordance with the principle of fluid dynamics, themathematical model of turbulent flow and heat transfer in the furnace were establishedwith standard k-ε model and SIMPLE algorithm.(2) The temperature distribution in the soaking section and the cooling section ofgalvannealing furnace was simulated at two specification (1248×0.898mm,1610×0.696mm) of strip. The results show that the strip in the soaking section, with the heightincreasing, the temperature of the strip has decreasing trend and the temperature of thestrip along the width direction tends to even. Under the same heating power, thetemperature of the strip which is1248mm wide and0.898mm thick is lower than theprocess requirements. In the cooling section, the temperature of the gas nearer the stripsurface is higher than other areas.(3) Several data was gained by means of field testing of the galvannealing furnaces in hot-dip galvanizing line. The environmental temperature, the inlet temperature, thetemperature at7meters height, the temperature at15meters height, the exit temperatureand pressure have been tested of the soaking section; the speed of gas from nozzle and theexit temperature have been tested of the cooling section. The results of simulation datawith test data are consistent by comparison, which indicate that this model and thesimulation results are correct.(4) In view of the production of the strip with slightly thicker, the temperature of thesoaking section can’t meet the process requirements, the structure of galvannealingfurnaces was improved. The side panels were installed in the front and rear at the exit ofthe soaking zone, the opening of the side panels can automatically adjust according to thetemperature settings of the furnace. The improved structure can effectively prevent warmair escaping in soaking zone. On the precondition of ensuring strip quality, the temperatureof the soaking zone can meet the process requirements.