Study on characterization of SrO Aerosols Generated by Optimized Thermal Plasma Torch Aerosol Generator

Abstract

Plasma Torch Aerosol Generation System (PTAGS) has been employed to generate nano aerosols with desirable characteristics. The operational parameters of PTAGS installed in the aerosol test facility have been optimized, and aerosols are generated using non-radioactive SrO2 powder. The current-voltage characteristics, electro-thermal efficiency and torch power are studied as a function of the flow rate of the plasma-generating gas (mixture of argon and nitrogen) and the arc current of the plasma torch. The arc characteristics relation is determined using the Nottingham formulation. Based on this, torch parameters are evolved and optimized as 20 kW power, 70% electro-thermal efficiency, 25 L min− 1 flow rate of plasma forming gas, 5 mg min− 1 powder feed rate and for 4–5 min torch operation towards the generation of SrO nano aerosols to achieve 1012 m− 3 and ~ 25 mg m− 3 for the count and mass concentration of aerosol respectively. The initial size distribution of the aerosols is in the few tens of nanometre range (10–40 nm) with a mean diameter of 26 nm (σg = 1.45). SEM and EDAX analysis reveal that the morphology of nano aerosols was nearly spherical and the formation of SrO nanoparticles. A set of operational parameters of PTAGS has been standardized to perform further experiments related to reactor safety analysis. PTAGS shall be tuned for aerosol generation in a large facility to achieve the characteristics equivalent to reactor accidental conditions.