Experimental study on supercritical water oxidation of lubricating oil from nuclear power plant

Abstract

BackgroundRadioactive waste oil mainly comes from the maintenance of equipment such as main pumps and steam turbines of nuclear power plants (NPP), and is a typical radioactive organic liquid waste (ROLW). Because there is no suitable treatment technology for ROLW, it can only be stored for a long time. Long-term storage has potential safety hazards such as leakage and fire.PurposeThis study aims to solve the problem of radioactive waste oil treatment by carrying out an experimental study on the supercritical water oxidation (SCWO) treatment of lubricating oil from NPP.MethodsA continuous SCWO reaction system was used as experimental platform with maximum working temperature of the 600 ℃ and pressure of 28.4 MPa. The effects of different reaction temperature, reaction time and excess oxygen coefficient on the chemical oxygen demand (COD) removal rate of VG 32 (Mobil DTE light turbine oil) lubricants were investigated. In addition, the reaction kinetics of SCWO treatment of lubricating oil from NPP at 420~580 ℃ was studied.ResultsThe experimental results show that the best operating conditions are reaction temperature of 550 ℃, reaction time of 80 s and oxygen enrichment coefficient of 250%. Under these conditions, the COD removal rate of organic matter is up to 96%. The activation energy Ea of the reaction is 43.10 kJ·mol-1, and the pre exponential factor A is 8.861 s-1. The deviation between the calculated value of the kinetic model and the experimental value is less than 3%.ConclusionsThis work proves the credibity of the model, and lays an experimental basis for supercritical water oxidation treatment of radioactive waste oil.

Keywords

• supercritical water oxidation
• vg 32 lubricant
• cod removal rate
• reaction kinetics