Research On Liquid Distribution Characteristics Of Self-priming Venturi Scrubber

The self-priming venturi scrubber is the core device of the filtered containment venting system(FCVS).It filters the radioactive gases and aerosols in the event of serious reactor accidents,preventing radioactive hazards to the environment and personnel.Based on the containment filtration and venting under severe accidents in nuclear power plants,this paper studied the liquid distribution characteristics of self-priming Venturi scrubbers experimentally and theoretically.The filtration efficiency of the self-priming Venturi scrubber is inseparable from the internal liquid phase distribution.The liquid phase distribution mainly includes three aspects: liquid injection flow rate,liquid film flow rate and atomized droplet size.The injection flow rate directly determines the amount of liquid water entering the Venturi scrubber,which is an important factor affecting the filtration efficiency of the Venturi scrubber;after the water is atomized into droplets,a part of it flows upward in the form of a ring-shaped liquid film in the expansion section,and this part of the volume cannot be ignored.Due to the small relative surface area,the annular liquid film has low impurity removal efficiency,which is not conducive to the improvement of the filtration efficiency of the Venturi scrubber.In addition,the droplet size is still a factor that cannot be ignored.Full atomization can generate a large number of small-size droplets,providing sufficient relative surface area for removing radioactive materials,thereby improving filtration efficiency.In this paper,the injection characteristics of self-priming Venturi scrubber are studied,and the differences in injection performance between different working conditions(throat gas velocity,submergence depth)and six different injection tube arrangements are discussed.Among them,the central straight tube and the central elbow tube have great advantages in the water injection,and the wall opening arrangement(straight tube at wall)used by the traditional Venturi scrubber does not predominate in the water injection.The variation of liquid film flow rate of self-priming Venturi scrubber was studied.The variation of liquid film flow rate and liquid film fraction under different working conditions(throat gas velocity and submergence depth)was discussed.The performance of straight tube and elbow tube was compared under different working conditions.It was found that the elbow tube at center has a higher liquid film flow rate and liquid film share,and the liquid film share of the elbow center is changed from 35% to 49%,the liquid film share of the straight tube at center configuration ranged from 26% to 40%.By measuring the droplets at the outlet of the Venturi scrubber,the droplet size distribution law and the droplet Sauter mean diameter(SMD)are obtained.The throat gas velocity is an important factor in determining the atomization level.The larger the throat gas velocity is,the more complete the atomization will be.The applicability of the RR distribution model and the NT model in predicting droplet size distribution and average diameter was verified based on experimental data.The injection flow rate,liquid film flow rate and droplet size obtained through experiments can help to understand the working performance and atomization mechanism of the Venturi scrubber,and also verify the liquid phase distribution measurement method of the self-priming Venturi scrubber.The effectiveness of the system has laid the foundation for further structural optimization studies and practical applications of Venturi scrubbers.