Experimental set-up for electrochemical measurements in hydrothermal sub- and supercritical oxidation: polarization curves, determination of corrosion rates and evaluation of the degradability of reactors during hydrothermal treatments of aqueous wastes

Influence of chromizing treatment on the corrosion behavior of AISI 316 stainless steel in supercritical water oxidation

“…One major problem in the supercritical water oxidation process is corrosion, because all metallic tubes in the process are exposed to high temperature and high pressure as well as severe corrosive species such as Cl , and O 2− [5][6][7]. The presence of Cl − when the pH of a solution is very low and the solution has excess oxygen causes active corrosion and metal loss by metal-chloride and/or oxychloride formation.…”

Accelerated estimation of corrosion rate in supercritical and ultra-supercritical water

“…Corrosion rates of materials in SCW and USCW, at conditions that are representative of the proposed operational parameters, have been exclusively determined using long-term exposure testing. 4,9,16,21,25 Fig . 3 Quantification of corrosion behavior: Summary of a corrosion rates calculated from exposure testing, b corrosion rates calculated from electrochemical frequency modulation, c corrosion rates calculated from electrochemical impedance spectroscopy, d polarization resistance values from electrochemical impedance spectroscopy for SS316, N50, I718 and I625 exposed to supercritical water at 530°C and ultrasupercritical water at 600°C As shown in Table 2, the corrosion rates obtained for the gravimetric studies compare favorably with the corrosion rates calculated from the EFM and EIS methods used in this study.…”

“…4,7,8 Electrochemical analyses performed by other authors have demonstrated the viability of accelerated corrosion tests, but, to allow such testing, they used conditions that were significantly different from the actual operating conditions of power plants. 9 Botella et al demonstrated that potentiodynamic polarization scans can be used to evaluate corrosion within a static, 80-mL autoclave that contains SCW. 9 While polarization curves were obtained, various additives were used to improve conductivity, including KCl, HCl, H 2 SO 4 , and K 2 SO 4 .…”

“…9 Botella et al demonstrated that potentiodynamic polarization scans can be used to evaluate corrosion within a static, 80-mL autoclave that contains SCW. 9 While polarization curves were obtained, various additives were used to improve conductivity, including KCl, HCl, H 2 SO 4 , and K 2 SO 4 . Also, this method was limited to a maximum temperature of 400°C, which does not allow the materials to be tested at the service conditions proposed for supercritical water reactors.…”

Plastic Reactor Suitable for High Pressure and Supercritical Fluid Electrochemistry

“…In particular, there can be problems with the reliability of sealing, it is necessary to take precautions to ensure that electrodes cannot be ejected from the reactor at high pressure, and many flag electrodes require additional electrical insulation with glues which add significantly to the complexity of, and time required for, preparing an experiment, which in our experience is commonly approximately 1 day for a single experiment. The problem of corrosion and chemical reactivity of metallic reactors has been dealt with by varying the reactor alloy 3,22 and inert inserts. 7,23 Our experience is that surface treatments can suffer from problems of longevity with repeated thermal cycling and inserts almost inevitably still allow access of the fluid to the metal and thus only reduce reaction rates and still allow corrosion and leaching.…”