Study on the flow fields in different baffled flocculation reactors

The flow fields of the flocculators with different baffle in the shape of vertical,perforated,arc and sine were studied respectively by LDV.The velocity and turbulent kinetic energy along with power number were compared in different types of baffled reactor.It shows that the flow fields in different baffled flocculators with the same type of pitched blade turbine(PBT) were generally axial circular flow,while the design of baffle has some degree impact on the flow filed in the circulation zone near the baffles.In different baffled flocculators the mean axial velocities have little difference,while the mean radial,tangential velocities,turbulent kinetic energy and power number have larger variation.In the flow field near the baffles,the average radial velocity increased by 0.043Utip,0.025 Utip and 0.058 Utip,the average tangential velocity increased by 0.023 Utip,0.019 Utip and 0.038 Utip,and the turbulence kinetic energy increased by 0.016 Utip2,0.015 Utip2 and 0.021 Utip2,for perforated,arc and sine baffles respectively,compared to that of the vertical baffles.Furthermore,the energy consumption was reduced by 0.98%,1.33% and 5.78%,respectively.Reasonable structure of baffles can effectively resolve the problem of non-homogeneous mixture,intensify the flow field of flocculation reaction,improve flocculating effect,reduce energy consumption,and enhance economic benefit.