Experimental Study Of Different Spoilers Promote Particle Agglomerate Growth By Phase Doppler Particle Analyzer

The pollution status of fine particulate in the atmosphere is getting worse,which has caused serious impact on people’s life.Studies have shown that flue gas emissions from industrial production are one of the main sources of fine particulate matter.However,the traditional dust removal equipment mostly used in industrial production has limited removal efficiency of fine particles and cannot meet the emission requirements at all.With the implementation of environmental protection policies and the management of environmental monitoring,many factories are forced to upgrade their existing dust removal equipment.However,the composite dust removal equipment is expensive and difficult to operate and maintain,and is not suitable for wide application and large-scale promotion.Turbulent agglomeration technology has gradually been recognized as an economical,practical and non-secondary pollution pretreatment method for fine particles.This technology mainly promotes the agglomeration and growth of fine particles through the turbulence generated by the turbulence device,thereby improving the efficiency of the subsequent dust removal equipment.At present,the research on turbulence agglomeration technology mainly uses numerical simulation methods to improve the agglomeration efficiency of particles by changing the geometry and arrangement of existing turbulence devices,but the mechanism of turbulence promoting particle growth is still unclear.In addition,the motion state of particles in the turbulent flow field is extremely complicated.Some conditions will be ignored or simplified during the simulation process,which cannot reflect the real turbulent flow field.Therefore,in order to further improve the effect of turbulent agglomeration on particle growth,in-depth experimental research is needed.Aiming at problems such as the unclear mechanism of turbulence promoting particle collision and agglomeration,the law of movement of particles of different sizes in the turbulent flow field and the unobvious agglomeration characteristics.In the experiment,firstly,the flow field distribution in the turbulent agglomeration chamber after adding different types of vortex generator was measured,and the influence of vortex generator,turbulence intensity and the changing of turbulent kinetic energy on the particle motion state was analyzed.Secondly,combined with the parameters of particle number concentration and median particle size distribution,the promotion effect of turbulence vortices on particle agglomeration with different particle sizes was investigated.Finally,calculate the agglomeration efficiency of particles after different types of vortex generator,select the vortex generator type that is most conducive to the growth of particle agglomeration and explain the reasons.This research mainly draws the following conclusions:(1).The blocking effect of the vortex generator on the incoming flow and the boundary layer separation phenomenon will cause a velocity gradient between particles;(2).The airflow disturbance generates a vortex with high turbulence intensity,which will spread the turbulence disturbance to the entire reunion chamber with the movement of the fluid;(3).Turbulent flow changes the state of motion of small and large particles,increases the probability of collisions between particles,and helps promote particles to reunite and grow faster;(4).The"V"vortex generator is most helpful to promote particle agglomeration and growth.When the airflow passes through this type of vortex generator,the median particle size distribution at the exit of the agglomeration chamber increases to 13.68μm,the total particle number concentration at the exit of the agglomeration chamber changes from 9.5×10~4/cm~3 to 1.2×10~4/cm~3,which was about87.03%less than that before turbulent agglomeration;(5).Due to the turbulent flow effect of the vortex,there will be two types of agglomeration modes in the turbulent agglomeration chamber at the same time:One is that small particles tend to gather in the vortex region due to their better airflow following.The other is that the large velocity gradient generated by the turbulence vortexes leads to the intersection of the trajectories of large and small particles,thus realizing the capture of large particles to small particles.The above two situations will increase the probability of collision between particles and eventually lead to particle growth.