Investigations On Filting Performance Of The Venturi Scrubber Working In Self-priming Mode

The containment in a nuclear power plant is the last barrier toprevent the release of radioactive fission product into the environment.In a severe accident that the core melts through the pressure vessel,then the coolant with high-pressure and high-temperature will release into the containment.At the same time,the molten core will react with concrete floor and produce large amounts of non-condensable gases,leading to a continuous increase of pressure in containment.When the pressure went up to the limit value or above,the integrity of containment would be threatened.This research is based on the wet part of the Filtered Containment Venting System(FCVS),the injection mechanism of the self-priming venturi scrubber and the removal performance for aerosol,iodine vapour and gas methyl iodine are researched with experiment and theoretical analysis.The experiment is mainly carried out in cold condition,and the major contents of study in thesis can be summarized as follow:1?The static pressure distribution at throat(integrated type)and divergent nozzle outlet(split type)is researched in the self-priming venturi scrubber,and the influence of pressure distribution on injcection flow rate is discussed also.The results show that the radical pressure gradient at throat distributes obviously for the integrated type venturi scrubber,and the pressure variation in radial direction present regional effects and the variation laws of injection flow rate is reverse consensus with pressuer.For the split type venturi scrubber,the static pressuer gradient at nozzle exit distibutes obviously also.This distribution is closely realte to the static pressure in liquid channel,which is at becomes more significant with increasing gas velocity.The injection flow rate mainly depends on the size,number and radical position of the suction channels.For the split type venturi scrubber,the static pressure at divergent nozzle exit also exist obvious radical distribution phenomenon,which the pressure near the wall higher than the center.The pressure in liquid channel is consistent with wall,which means that the effective pressure difference for suction is limited especially in injecting condition.In this case,increasing the liquid channel aera is more effective for improving injection flow rate.2?The aerosol collection and gas absorption performance in the venturi scrubber is researched with experiment and theoretical analysis.It indicates that the particle collection efficiency is closely relate to the aerosol diameter,the structure of the scrubber and two phase flow conditions,and the efficiency is mainly controlled by the small size aerosol.To fulfil the efficiency requirement,the structure and operation condition is optimized based on experimental research and theoretical analysis.The venturi scrubber present excellent performance for iodine vapour absorption,and the efficiency is not sensitive to structure and operation parameters when the injection flow rate is abundant.In contrary,the gas methyl iodine absorption efficiency in the venturi scrubber is unsatisfactory even with various structure parameters and operation conditions.3?The solubility coefficienct of methyl iodine under different temperature and pressure is measured based on Hemy's low and mass conservation law,and a uniform expression is fitted within measurement conditions.The maximum absorption efficiency in venturi scrubber and submerged solution are estimated respectively.The result shows that the potential absorption ability of methyl iodine in the venturi scrubber is limited but is considerable in submerged layer,and further improvement on efficiency should turn to submerged section.4?Based on the gas absorption process at the outlet of venturi scrubber,the absorption mechanism of methyl iodine in submerged solution is researched.The experiment firstly analysised the equilibrium establishment process of gas absorption.According to the process analysis the main factors of limiting absorption efficiency under different working condition is confirmed,at the same time,the influence of limiting factors on improving efficiency is verified also.In addition,the influence of solution temperature,the system pressure,the gas flow rate,the solution level and entrance concentration on absorption efficiency are also discussed in this research.