Inorganic salts crystallization and deposition characteristics and mechanisms in supercritical water

Low density and dielectric constant along with low viscosity and high diffusivity make supercritical water (SCW) an admirable reaction medium for some technologies, such as supercritical water oxidation and supercritical water gasification. However, polar inorganic salts and other ionic compounds are difficult to dissolve in supercritical water, so leading to crystallization and deposition problems to limit the scale-up of the processes above. Therefore, to further promote the development of SCW-related technologies, the crystallization and deposition characteristics and mechanisms of inorganic salts in SCW require more attention. This work comprehensively reviews the solubility data and prediction models of inorganic salts in SCW, deeply analyzes the interaction of different salts in multi-component water-salt systems, and summarizes the simulation studies related to micro nucleation crystallization and macro deposition. To realize the commercialization of SCW-related technology, it is of great significance to study the phase behavior, crystallization and deposition characteristics and mechanisms of multi-component water-salt systems. • Solubility and prediction models of salts in supercritical water are summarized. • Characteristics of water-salt systems and solubility influence are discussed. • Salt crystallization and deposition mechanisms are systematically analyzed. • Particle movement, deposition and crystallization in SCW are reported deeply. • Multi-component systems help to analyze crystallization and deposition kinetics.