Effect of evaporation on the energy conversion of a supercritical water oxidation system containing a hydrothermal flame

• Published in: Energy (Oxford) Vol. 226; p. 120406
• Main Authors: Zhang, Fengming, Li, Yufeng, Jia, Cuijie, Shen, Boya
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2021; Elsevier BV
• Subjects: Coking; Destruction; Energy conversion; Energy conversion efficiency; Energy efficiency; Energy utilization diagram; Evaporation; Exergy; Heat exchangers; Heating; Hydrothermal flame; Modules; Oxidation; Phenols; Self sufficiency; Supercritical water oxidation; Thermodynamics; Volatility; Volatilization; Wastewater; Water injection; Evaporation; Energy utilization diagram; Hydrothermal flame; Volatility; Supercritical water oxidation
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2021.120406

Hydrothermal flame is an effective solution to avoid coking and salt plugging in the preheating section of a supercritical water oxidation (SCWO) system with a transpiring wall reactor (TWR). An SCWO system with an evaporation module (SCWOE) is proposed in this work to concentrate the wastewater and promote the formation of a hydrothermal flame. The SCWOE system is simulated using Aspen Plus, and the simulation model is validated by comparing with the experimental data on the migration of organics in evaporation. The introduction of the evaporation module greatly reduces the exergy input. The exergy destruction mainly comes from the TWR, electric heater, and heat exchangers. The highest exergy destruction in the TWR appears in the reaction section, and the total exergy destruction in the TWR due to the transpiring water injection reaches 89.9%. The increase in concentration ratio (α) and feed concentration (ω) can lower the exergy input and improve the energy efficiency, and an energy self-sufficient rate of 79.7% occurs at ω = 15% and α = 2. Moreover, the involatile property of organics is conducive to improving energy self-sufficient rate, and the volatilization rate of phenol in wastewater must be controlled in this system. •A supercritical water oxidation system with an evaporation module is proposed.•Feed is concentrated to promote the formation of a hydrothermal flame.•The proposed supercritical water oxidation system is simulated using Aspen Plus.•Exergy destruction mechanism is revealed using the energy utilization diagram.•Optimized parameters to increase energy self-sufficient rate are obtained.