Optimization Design Of Tube Type Static Mixer By Using FLUENT

Tubular static mixer is an advanced hybrid unit.Unlike agitator,there isn't moving parts in its interior.It achieves various fluid mixing by using fluid flow and internal cell.At present,static mixers are mostly used in small scale and high viscosity chemical mixing.In water treatment,the mixer is larger.The static mixer used in water treatment is single,with less the theoretical support.The measured head loss of the static mixer is different from the theoretical calculation.Based on FLUENT fluid dynamics numerical simulation software,three common static mixers,namely SY static mixer,SX static mixer and SK static mixer,were simulated,and pressure drop,dynamic characteristics and homogeneity were analyzed.In addition,the spray head was optimized separately,and it was found that the multipoint addition was beneficial to the uniformity of the mixture.At the third water plant in LingAn province(JinBei water plant),the field experiment was carried out.The pressure drop of the original SY static mixer was analyzed,and the rationality of the model was tested.The conclusions are described as follows:(1)SY1,SY2 and SK static mixer were staggered with the leaves,to change the direction of water flow,the flow of water rotation,resulting in turbulent shear.The water was still flowing in the state of circulation after the blade,and the shear force of the turbulence continues to act on the fluid,so the mixing uniformity of the drug still decreased significantly.SX type static mixer is used to form the barrier fence local head loss,making the drug distribution.(2)The simulation results of the four static mixer type show that as for the pressure drop parameters,SX type >SY1 type >SY2 type >SK type;as for the installation length of the hybrid unit,SY2 type >SY1 type >SX type >SK type;as for the total mixing length,SX type >SK type >SY1 type >SY2 type.The pressure drop of SX type is the highest,but the mixing effect is the worst.Although the installation length of the SY1 type was smaller than that of the SY2 type,the pressure drop and the total mixing length were higher.The total mixing length of the SK type was larger than that of the SY2 type,but the pressure drop was low,and the installation length is 34% of the SY2 type.(3)The effective utilization ratio of mixed strength of the blade unit and the effective utilization rate of the mixing strength of the whole pipe segment were studied respectively by using shear strength pressure drop ratio E and E' value.As for E values of the four mixers,SK type > SX type >SY2 type >SY1 type,as for E 'value has SK type >SY2 type >SY1 type > SX type.The study showed that the energy utilization ratio of SK mixer were higher than those of other mixers.(4)The simulation results of the dosing add method showed that the effect of changing the dosing method on pressure drop was less than 2%,and the total mixing length of the optimal scheme was reduced by 56% compared with the original scheme.Changing the dosing mode shortened the mixing length,saved material without increasing the energy consumption significantly,and provided convenience for installation management.