The Control Of Zinc Vapor Emissions Within Snout Based On Push And Pull Ventilation System

Hot galvanized strip steel is widely applied into architectural decoration material,shells of automotive and appliances.Zinc ash forms white strip or dot marks on the surface of strip steel,which will affect the appearance and reduce the quality of strip steel.The defects of zinc ash are produced in the snout of the hot-dip galvanized steel production line.Zinc vapor is produced by evaporation of zinc liquid surface,which accumulates into zinc ash after condensation.In this paper,the push and pull ventilation system is used to control zinc vapor within snout.The control effect of the zinc vapor is discussed.(1)In this paper,a push and pull ventilation system experimental device is established.In normal temperature and normal pressure,velocity in different conditions is measured.Comparisons between the result of simulation and the experimental data demonstrate the average relative error is 9.9% and the model is effective.(2)Under industrial conditions,the primary design of push and pull ventilation system in the snout is carried out based on the jet terminal velocity control method,the critical section method,and the new flow ratio method.Through numerical simulations,the collection efficiency of zinc vapor is obtained.Considering the total wind quantity and the collection efficiency of zinc vapor,the preliminary design results are as follows: the blowing velocity is 3.0-7.0 m/s,the suction velocity is 1.0-5.0 m/s,the height of blowing inlet is 0.01-0.04 m,the height of suction outlet is 0.1-0.3 m,position of suction outlet is 0.15-0.2 m.(3)Based on the preliminary design results,the five factors and three levels are studied using orthogonal experimental design twice.The numerical simulation results of the first orthogonal design optimize the parameter range: the blowing velocity is 5.0?7.0 m/s,the suction velocity is 3.0?5.0 m/s,the height of blowing inlet is 0.025 ? 0.04 m and the height of suction outlet is 0.2-0.3m,and the position of suction outlet is 0.15-0.75 m.The significance ordering of each factor is obtained by the second orthogonal design: the suction velocity > the height of suction outlet > the blowing velocity > the height of blowing inlet > the position of suction outlet.The calculation formula of zinc vapor capture efficiency is obtained by regression fitting: ?=46.17+2.01v1+4.89v3+140.86b1+63.24b3-26.42h3.Through the factor analysis method,the calculation formula for determining the exhaust wind quantity Q3 is obtained.The results also show that the total wind quantity after optimization design is 84.8% of that using classical design method when the zinc vapor capture efficiency is the same as that of the classical design method.