A new system design for supercritical water oxidation

• A lab-scale SCWO system based on DGSWR was described in detail.
• Gas seal of DGSWR was verified under supercritical conditions.
• Sewage sludge with 2.62–11.78% DS was safely treated.
• Gravity sedimentation of solids partially achieved.

As the main obstacles for the industrialization of supercritical water oxidation (SCWO) technology, corrosion and plugging are mostly occurring in the high pressure high temperature (HPHT) sections, including preheater, reactor, heat exchanger and cooler. In this paper, a lab-scale SCWO system based on dynamic gas seal wall reactor (DGSWR) has been described, tested and discussed in detail. The results showed that the preheating problems of waste with high solid content has been solved and the “gas seal” of DGSWR has been successfully verified under 28–29 MPa and around 400 °C. Sewage sludge with 2.62–11.78% dry solid has been degraded and the COD removal efficiency can reach up to 99.15%. However, the solid particle sedimentation was only partly achieved. According to the results analysis, based on the Stokes’ Law, both small particle size and counter-current of upward reaction medium and downward solids are responsible. Future improvements for the SCWO system were also discussed at the end of this article.

Figure optionsDownload as PowerPoint slide