Kinetic mechanism study of mixed ion exchange resins gasification in supercritical water

Abstract

Supercritical water gasification (SCWG) is a promising technology for the treatment of organic radioactive waste. This paper aims to establish a reaction kinetic model for SCWG of spent ion exchange resins (IERs) produced by nuclear plants to enhance guidance for optimal industrial reactor design. This paper aims to establish a reaction kinetic model for the SCWG of spent ion exchange resins (IERs) generated by nuclear plants, thereby enhancing guidance for optimal industrial reactor design. The model is developed based on experimental results obtained in a batch reactor under various conditions, specifically at temperatures ranging from 650 to 750 °C and reaction times between 5 and 30 min. Validation results indicate that the kinetic model can predict gas concentration with an acceptable level of deviation. Furthermore, reaction rate analysis reveals that monocyclic aromatic compounds, particularly IntA, are the significant intermediate products of skeleton structure gasification. And the benzene ring opening is identified as the critical reaction that limits the gasification of the skeleton. Additionally, the nitrogen component is ultimately converted into ammonia and nitrogen gas.