Deposition of iron oxides in supercritical water reactor: A review

Abstract

Low-temperature corrosion of the system and external input make it difficult to avoid the entering Fe ions in the supercritical reactor. Fe ions crystallize into particles in supercritical water and deposit on the surface of the reactor, causing safety threats and economic losses. In this paper, research on the Fe ion deposition process, from crystallization, to oxide particle formulation and to completely adhering to the wall surface, is reviewed. The literature mainly includes theoretical and experimental research on the nucleation and growth process of Fe oxide particles in a supercritical water (SCW) environment, particle movement and experimental observation methods in trans-critical turbulence, and the effects of Derjaguin-Landau-Verwey-Overbeek (DLVO) and collisions considered in the process of particle attachment. The particle deposition process involves particle formation, particle movement and surface adhesion. These three dynamic processes have cross-influencing factors that include geometric factors (the size of the particles themselves, the roughness of the wall), hydrodynamic factors (turbulence and transcritical conditions), and environmental parameters (temperature, pH). Independent research on dynamic processes is no longer suitable. The review aims to clarify the mechanism of three dynamic processes and their roles in the particle deposition process so that they can be comprehensively considered in the study of particle deposition in actual operating systems in the future.