Influence of throat and diverging section on the performance of venturi scrubber by using computational fluid dynamics

Filtered Containment Venting System (FCVS) is a safety system of nuclear power plants whose primary objectives are control of over-pressurization and prevention of release of radioactivity in severe accidents. In a severe accident scenario, when pressure of containment exceeds a set limit, this system gets activated and part of containment steam/gases mixture is transferred to FCVS where removal of hazardous radioactive gases like iodine takes place via scrubbers and then cleaner air is vented out. Iodine removal is necessary because if discharged into environment, it can cause serious health concerns including thyroid cancer. Venturi scrubbers are a key component in FCVS for retention of iodine. Research on various parameters of venturi scrubbers is necessary in order to attain maximum removal efficiency. This research was carried out to investigate the effect of geometric parameters of venturi scrubber on iodine removal using Computational Fluid Dynamics. Parameters such as number of orifices, diameter and length of diverging section and length and diameter of throat section were studied. Influence of variation in above-mentioned geometric parameters on different operational parameters like pressure, volume fraction phase-1, velocity, mass transfer rate and iodine mass fraction was investigated. Order of effect of geometric parameters on iodine removal from lower to higher comes out to be diverging diameter, diverging length, throat length, number of orifices, and throat diameter. 5-68% increase in mass transfer rate was observed from variation in parameters. This research would be very helpful for researchers and designers in parametric optimization and design of an efficient venturi scrubber.