Enhancement of Glass Production Rate in Joule Heated Ceramic Melter

Abstract

Abstract In this research work, experimental studies and numerical simulation of Joule Heated Ceramic Melter (JHCM) used for vitrification of radioactive liquid waste (RLW) were carried out. The isolation of the long-lived radioactive isotopes by fixing them in suitable host matrix is the only practical approach adopted for conditioning of highly radioactive waste generated from the nuclear fuel cycle. RLW and preformed glass beads are added simultaneously on a molten glass pool maintained at 1000 °C in JHCM to form a product that is qualified for long term storage. The sequence and kinetics of different reactions taking place in JHCM were identified and calculated by carrying out Thermogravimetric Analysis of the radioactive species present in RLW at different heating rates. The effects of these constituents on the melter throughput and quality of the Vitrified Waste Product (VWP) produced were assessed. The foam generated during vitrification process has a major influence on the design of melters. The amount of foam generated was quantified and its influence on glass production rate was analyzed. Melt rate limitations were determined for JHCM based on the measured thermo-physical properties. Minimum residence time required for producing product of the desired specification is determined. A model is developed for determining the glass melting rates. Experiments were carried out for generating data required for validation of the model. The model predictions are compared with experimental results. The factors affecting the product throughput and quality are identified with an objective of reducing the residence time of the product thereby increasing the throughput. The effect of agitation on the rate of melting of glass was determined.