Study On Supercritical Hydrothermal Combustion Enhanced Degradation Of Oilfield Wastewater

Water injection development and steam injection development were required as our country's major oilfields was in the late stages of exploitation.Oilfield wastewater obtained during crude oil exploitation has become a serious environmental problem.Hydrothermal combustion technology is a new efficient decontamination of organic wastewater,which can overcome the shortcomings of traditional treatment methods for oilfield wastewater.This paper aims at the difficult problem of severe degradation conditions of nitrogen-containing compounds in oilfield wastewater.The typical nitrogen-containing compounds(ammonia,quinoline)were selected as the research object and added auxiliary fuels in supercritical hydrothermal combustion on a continuous experimental device.The interaction mechanism between auxiliary fuels and refractory has been studied systematically in hydrothermal combustion experiments and enhanced degradation experiments.The main research results obtained in this paper are as follows:The experimental study for hydrothermal combustion characteristics of methanol and ethanol were obtained,and the interaction mechanism for supercritical hydrothermal combustion process of methanol and ammonia was investigated.The result indicated that the methanol solution under the same COD concentration was more active than the ethanol solution,while the combustion rate of methanol was faster than that of ethanol.In hydrothermal combustion for mixture solution methanol and ammonia,the effect of the ammonia/methanol COD ratio on supercritical hydrothermal combustion depends on the concentration of the fuel.Ammonia could depress the ignition and oxidation process at fuel concentration of 57.4g/L,preheating temperature of 420?.And fuel solution cannot ignite when R rises to 0.49.And ammonia could promote the overall combustion process at fuel COD concentration of 73.0 g/L,preheating temperature of 420? and ammonia ratio of 0.05-0.19.Moreover,this experiment also verified that 2.74 wt%quinoline could undergo ignition in dynamic flow of the supercritical water reactor,and the oxidation reaction mechanism of quinoline was further analyzed.The degradation characteristics of ammonia,which is the main intermediate of degradation of nitrogen compounds in oilfield wastewater at the presence of medium and low concentration of auxiliary fuel methanol were studied systematically.The influence of operating parameters(methanol concentration,oxidation coefficient,ammonia concentration)on the degradation of ammonia was obtained.Specifically,near complete conversion of ammonia(97.5%)can be achieved at[CH3OH]0=800 mmol/L,preheating temperature of 415? and oxidation coefficient of 1.5.In particular,the decolorization mechanism of ammonia in a supercritical water environment at the kinetics action and the thermal action was conducted.The formation of nitrate was analysis in supercritical water oxidation process.Methanol and isopropanol served as the auxiliary fuel for ammonia were compared by the positive effect and exothermic performance,which reached that methanol was superior to isopropanol.