Research On Energy Saving Analysis And Numerical Simulation Optimization Of Annealing Furnace For Hot-Dip Galvanizing Unit

Iron and steel industry consume a lot of energy and high quality steel needs more complex process leading to increase heat consumption and environment pollution.Hot-dip galvanized steel needs a recrystallization process in annealing furnace before plating in the zinc pot.Energy saving as the significant focus has been increasingly concerned about in steel enterprises.The annealing furnace preheating section plus the direct-fired section(PHS&DFS)and the radiant heating section(RHS)were used as the research object,and the heat balance test was carried out respectively.Based on the heat balance results of PHS&DFS and RHS sections,the structure inspection and analysis were carried out to find out the reasons for the increase of gas consumption in the annealing furnace.Some improvement measures were put forward such as adjusting the DFS section of the air coefficient from 0.82 to 0.94,reducing RHS air coefficient to 1.1±replacing the damaged refractories and so on.Under such conditions,PHS&DFS saves 27.22x105/h and thermal efficiency is increased by 7.37%,RHS saves 7.45×105 kJ/h and thermal efficiency is increased by 3.79%.Combining the statistical data of the production performance table of the annealing furnace,select emprical formula to get the relationship between the heat load and the productivity as well as unit energy consumpution and productivity,finding out productive economy point,the lowest unit energy consumption and heat load of the optimal productivity.Unit energy consumption can be effectively reduced with economic point productivity,reasonable thermal insulation load and operation rate.Simulations of flow field,temperature field and concentration distribution in the DFS under the test conditions were conducted by using Fluent.When air-fuel ratio rises from 3.5 to 4.2,the mean temperature of the furnace rises first and then decreases.The air preheating temperature rises from 500K to 800K,and the average temperature in the furnace is on the rise.further validated that the adjusted air-fuel ratio of the DFS was reasonable.Several sets of optimized combination parameters(3.7/720 K、3.8/600 K、3.9/450 and 4.0/300 K)were simulated,among which the set of air-fuel ratio of 4.0 and air temperature with 300 K makes gas consumption decreased by 16.88%and saves about 1.86×105 Nm3 coke oven gas.