Study On Interfacial Property On Oil Recovery From Petroleum Sludge

Petroleum sludge, or oily sludge is a kind of solid waste which generates from oil industry. It generates from oil, water and solid which sediments in the bottom of oil tank or oil separator. Due to its hazardous to the environment along with resource potential, it is meaningful to recover oil from oily sludge and gain environmental and economic benefits. Oily sludge is a mixture of water in oil emulsion and solid suspension. Centrifugation is a widely employed separation method but because oily sludge has extremely high viscosity as well as superfine solids inside, centrifugation tends to gain low efficiency. Normal experiment shows that although at centrifuge speed over 10000 g, fine particles and water droplets still remains in the recovered oil. Focusing on the shortage of centrifugation process, this paper developed a study of separation theory based on the interfacial properties of oil-solid-water phases. Main contents include:1. Physicochemical properties studied..on oily sludge samples, including water/oil/solid composition measured by azeotropic distillation; microscope study; proximate and ultimate analysis; SAR of oil phase by column chromatography; solid analysis by SEM, EDS and XRD.2. Study on the surface character of solids in oily sludge. We combined FT-IR, SEM, AFM and contact angle measurement with different solids in oily sludge extracted by hexane, toluene and chloroform. Results shows that solids in oil tends to adhere heavy components such as resins and asphaltenes which contributes to its hydrophobic surface and hard to separate. We studied the relationship between particle lypohydrophilic and oil viscosity. We discovered that adding ferric salts and surface modified hydrophobic silicate will strongly increase the apparent viscosity of oil. We built a viscosity model to evaluate the solids contribution to viscosity change and it’s well fit with experimental results.3. This paper studies the migration behaviors of oil, water, and solids in sludge during centrifugation. Solid particles size distribution, surface topography and lypohydrophilic properties were detailed studied. Water phases were characterized by differential scanning calorimetry analysis. Equivalent molecular weight of oil phases was measured by gel permeation chromatography. The result shows solvent is essential to separate oil phase into molecular light and weight fractions. A model was proposed for calculating the solid residue in oil phases and oil residue in solid phases after sedimentation. The findings of this paper provide information for optimizing the oil recovery and clean treatment.4. According to the theory studies above, we built a pilot-scale experiment platform based on a continuous sampling tube style centrifuge for evaluate the technique feasibility in production. We compile a standard for equipment selection by pilot experimental guidance. We cooperated with Nahai Solid Waste Company and built a 100 tons per day demonstration projects in Zhoushan, Zhejiang. Separation method and selection standard was employed and operated in the project.