Preliminary Experimental Investigation on the Filtration Performance of Submicron Insoluble Aerosol in a Bubble Column

Abstract

Pool scrubbing is a representative process for aerosol retention involved in severe LWR accidents and has proved to be a potential method for the removal of micron-sized aerosols. Bubble scrubbing, as the key component of pool scrubbing, has the advantages of a large gas-liquid contact area and long residence time. However, the filtration mechanism of submicron aerosol by bubble scrubbing is still not clear. Therefore, the goal of this research is to evaluate the filtration performance of submicron insoluble aerosol in a bubble column. Some preliminary experiments were carried out to investigate the influence of operational parameters on aerosol filtration efficiency, such as inlet aerosol concentration, gas flow rate and pool temperature. Mass method was used to analyze the aerosol filtration efficiency. The results show that the aerosol filtration efficiency is independent of inlet aerosol concentration when inlet aerosol concentration is in the range of 0.2-0.5 g/m 3. Besides the aerosol filtration, efficiency is influenced by the superficial gas velocity. With the increase of superficial gas velocity, homogeneous bubbling, transition and a heterogeneous bubbling regime will appear in turn. The aerosol filtration efficiency decreases in the transition regime due to the appearance of large bubbles but increases in the heterogeneous bubbling regime account for intense gas-liquid interaction. Moreover, the aerosol filtration efficiency significantly decreases with pool temperature because the evaporation rate at the gas-liquid interface will significantly increase as the boiling point is approached, which gives retroaction to aerosol filtration efficiency.