Abstract: Supercritical water is uniquely a green medium for diverse applications because of its changing nature from polar to non-polar. Owing to this property, it is being considered for heavy oil upgradation since it dissolves both organics (oil) and hydrogen while inorganics behave conversely. However, because of the high pressure and temperature (22.1 MPa, 374 °C), corrosive environment (chlorides, sulfides and salt deposition) and stresses involved, there are serious concerns encountered while utilizing supercritical water in reactors. These include change in the component-material microstructure due to hydrogen ingress, sulfide stress corrosion cracking and salt deposition leading to pitting and de-alloying. Various alloys such as ferritic–martensitic steels, austenitic stainless steels, Ti-, Ni- and Zr-based alloys have been used, while new alloys and materials are continuously being investigated to considerably help abate these problems and ultimately improve the life of reactors. Despite significant past efforts in material development, reactors still suffer from these problems and challenges. This review assesses materials selection, the current progress in material development as well as their potentials in ameliorating reactors resistance to oxidation, pitting, embrittlement, etc. This study aims to improve understanding of material selection for supercritical water reactors based on the corrosive environment of the reactor and hence help engineers to make insightful decisions in selecting material for the specific corrosive environment. Graphical Abstract: Schematic illustration of materials susceptibility in supercritical water reactor [Figure not available: see fulltext.].
Bibliographical notePublisher Copyright:
© 2019, Springer Science+Business Media, LLC, part of Springer Nature.
- Heavy oil upgrading
- Supercritical water
ASJC Scopus subject areas
- Metals and Alloys
- Materials Chemistry
- Inorganic Chemistry