Study On Supercritical Water Oxidation Of Oily Sludge

Supercritical water oxidation technology is a new type technology of the complete destruction of the organic matter structure. Most organic pollutants and oxygen can dissolve in supercritical water, and they can form a good environment. Thus the organic matter in the waste can be decomposed by oxidants into water, carbon dioxide and simple small molecule compounds.Hydrogen peroxide is the oxidant in this paper, self-designed experimental device is used, the actual oily sludge and the simulation oily sludge are destruction by hydrogen peroxide in supercritical water. The reaction temperature, the reaction pressure, the reaction residence time and oxidants are study on the removal rate of organic matter of oily sludge. Formaldehyde has been used as a co-oxidant, sodium bicarbonate has been used as catalyst to promote organic matter removal rate of oily sludge at low temperature. And supercritical water oxidation reaction mechanism was discussed.The experimental results show that: the best reaction temperature is 420℃—440℃; best reaction pressure is 24MPa—30MPa; best reaction residence time is 10min—15min; the initial hydrogen peroxide, th ratio of the actual amount and theoretical demand is 4—7; oily sludge volume, initial COD is 2000mg/L—6000mg/L; optimum pH value is 10; the co-oxidative effect of formaldehyde on oil-field sludge is characterized for oilfield sludge concentrations (50000mg/L) and formaldehyde concentration (15mg/L) for a range of temperatures (380℃-440℃), the COD removal rate is 99.9% at T=440℃, p=24MPa,τ=10min, [COD]initial=2000mg/L, with formaldehyde in supercritical water, and finally effluent COD <10mg/L. Radical reaction mechanism is the mechanism of supercritical water oxidation oily sludge, acetic acid and carbon monoxide are the reaction intermediate product. First acetic acid and carbon monoxide are generated in supercritical water, and then further oxidized to carbon dioxide and water.