Experimental study on oil-containing wastewater gasification in supercritical water in a continuous system

Recently, promising multi-fluid thermal stimulation technology has been studied and applied successfully to the offshore heavy oil recovery process. However, there are still some shortcomings, including heavy reliance on diesel, heavy and bulky water pretreatment plant, etc., which hinders the further industrialization process of the current generation system of thermal multi-fluid. A novel thermal multi-fluid generation technology to decrease reliance on diesel was presented in this paper. In this technology, oil-containing wastewater can be used directly as the material and energy source. Increased attention should be given to the supercritical water gasification (SCWG)process as the core of this novel technology. An experimental study on SCWG of diesel, a representative of oil-containing wastewater, was described detailly in this paper. Experiments were conducted in a continuous SCWG system under different experimental conditions, as follows: pressure of 23 MPa; reaction temperature of 600 °C–680 °C; mass ratios of water to diesel in emulsification of 1:1, 1:2.5, and 1:3.5; and reactor diesel concentration (R_DC)of 4.70 wt% to 7.70 wt%. The effects of alkali catalyst (K₂CO₃)on gaseous and liquid products were also investigated. A simplified gasification mechanism in SCW was obtained, which may provide a theory basis for the novel thermal multi-fluid generation technology based on oil-containing wastewater gasification in supercritical water.