Experimental Research On Bubble Distribution And Performance Of Swage Oil Removal In Closed Flotation Device

Air flotation technology in wastewater treatment has a wide range of industrial applications and scientific research.Due to outdoor setting,most of traditional flotation column causes secondary pollution and environment has bad influence on treatment.Hence a novel kind of closed loop type flotation device is designed.This subject shows a late-model closed flotation device whose advantage is that the floatation tank is closed.Meanwhile,most air floatation technologies use advection flotation tank.The bubble size distribution in contact and separation area has a great influence on the effect of air flotation which needs us to study in.Solving the problems existing in traditional air flotation device and analyzing the bubble size distribution become to the research direction.Based on the technology that already have and the structure of traditional air flotation device,designing the process of closed flotation and selecting the equipment.Then the experiments use microscope imaging method to measure gas bubbles.Through the Matlab program dealing with the data,the result shows that the bubble size reaches 30μm when the dissolved gas pressure at 0.34 MPa,gas-liquid ratio at 5%,the concentration of surfactant at 50 ppm,the salinity at 1mol/L.At this time,the bubble quality is better and the density is larger,which is favorable for the separation of air floatation.In the contact zone and separation zone,the bubble diameter becomes bigger as the height increases.What’s more,the liquid inlet quantity should be less than 600L/h to ensure the stability of flow field.After 8 days of long period running experiments,the separation efficiency is more than 80%.Compared with the traditional pressurized dissolved air floatation process,the device has better treatment effect and less gas / liquid ratio.After that,the oil removal efficiency experiment shows that the system stability time is 60 min.when the liquid inlet volume is at 350L/h,the concentration of oil sewage less than 450mg/L,the dissolved gas pressure at 0.35 MPa,the gas-liquid ratio at 5%,the reflux ratio at 30%,the concentration of de-emulsifier at 15 ppm and the concentration of surfactant at 20 ppm,the oil removal efficiency is more than 90%.Based on the data analysis,the paper establishes the forecast model of separation efficiency.This devices not only ensures efficient separation of wastewater contamination,but also achieves an entire process cycle of a confined operation.The setting has the advantages of compact structure,good sewage treatment efficiency,the limitation of secondary pollution,odorless,close to gas-zero-loss,strong suitability on environment and climate and low operating cost.It can also be applied under high temperature and high pressure.This method and device can be an alternative to traditional types of flotation.