Numerical Study On The Gas-liquid Two-phase Flow Field Characteristcs Of Annular Slit Venturi In New Og System Of Primary Dedusting For Converter

The oxygen converter steelmaking is the main steelmaking method in China.As the continuous expansion of the steel industry,the number of steel converters in our country is increasing year after year.Oxygen converter steelmaking produces a large amount of high temperature flue gas,which not only contains recyclable carbon monoxide,but also contains metal dust that can pollute the environment.As the key part of the new OG?Oxygen Converter Gas Recovery?system of primary dedusting for converter,a viable throat annular slit venturi scrubber is directly related to the system's dust removal efficiency,pressure control accuracy and the service life of the equipment.This study was based on Eulerian-lagrangian method,adopts CFD-DPM and Realizable k-?turbulence model,and uses the SIMPLE algorithm to deal with the coupling of velocity and pressure.The interaction between gas and droplet,atomization of liquid jet and collision and breakup of droplets in the annular slit venturi were considered in the simulation.On this basis,the numerical simulation of gas-liquid two-phase flow characteristics of annular slit venturi were carried out under different working conditions of annular slit trip,L_i,liquid-to-gas volume flow ratio,L/G,and flue gas flow rate,Q_g.The influence rule of various factors on the flue gas average velocity at the throat,the pressure drop and the dedusting efficiency of annular slit venturi were mainly revealed.In addition,the optimization analysis of the internal spray water method was carried out by changing the spray position,the spray angle and the nozzle quantity in order to improve the dedusting effect of annular slit venturi.The uniformity of the velocity field at the throat and the change of droplets mean diameter were explained by analyzing the relative standard deviation of velocity at the throat,C_V,and the sauter mean diameter of droplets,SMD.The following conclusions were obtained.?1?The flue gas average velocity at the throat,V_th,is reduced by spray droplets in the gas-phase flow field and the larger the L/G,the smaller the V_th.However,L/G has little effect on V_thh in the reasonable range.V_th is proportional to L_i.The larger the L_i,the more uneven the flue gas velocity distribution at the throat,which is not conducive to the uniform distribution of droplets.Additionally,V_th does not vary linearly with L_i,the growth rate of V_thh increases slightly with L_i.During the range of L_i selected in this study,V_th increases by about 6⁸%when L_i per 50 mm increases.?2?The pressure drop of annular slit venturi is directly proportional to L_i,L/G and Q_g,and three variables have different effects on the pressure drop.Within the range of variables selected in this study,the pressure drop increases by about 12¹7%when L_i per50 mm increases.The pressure drop increases by about 7⁹%with L/G increases by 0.1l/m³,and the pressure drop increases by about 10%when Q_g increases by 5000Nm³/h.The pressure drop almost increases linearly with L/G and Q_g,but does not increase linearly with L_i.The pressure drop increases more significant with the increase of L_i,especially for L_i is more than 700 mm.The pressure drop of annular slit venturi approximately has quadratic relation with L_i,and the quadratic relation between the two quantities decreases for the lower L/G.L/G and Q_g has more significant influence on the pressure drop when L_i is larger,especially when L_i is larger than 700 mm.The growth rate of pressure drop increases slowly with the increase of L_i,when Q_g increases.L_i should be selected in the range of 650-700mm.Under this working condition,a better dedusting effect can be achieved by increasing L/G properly.?3?The nozzle spray angle is in direct proportion to C_V and inversely proportional to SMD when spraying water at the throat,and the variation trend of C_V is very gentle when the spray angle,?,is less than 75 degrees.Finally,?is suitable for 75 degrees.C_V decreases with the increase of the spray position at the throat,on the contrary,the SMD value increases more significantly.C_V decreases more gently with the rising of the spray position,while the SMD value increases more significant when the spray position is above the middle of the throat.Therefore,it's better to choose the spray water at the middle of the throat.As the nozzle quantity increases,the droplet coverage becomes wider and the droplet distribution is more uniform at the throat.The values of C_V and SMD decrease and the pressure drop of the annular slit venturi increases as the rise of nozzle quantity when spraying water at the throat.The pressure drop increases by about17%when the nozzle quantity increases from 2 to 4.The values of C_V and SMD decrease more significant and the pressure drop increases more significant as the rise of nozzle quantity.The pressure drop increases by about 3%when the nozzle quantity increases from 2 to 3,while the pressure drop increases by about 13%when the nozzle quantity increases from 3 to 4.