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UDC 628.349

Adel'shin A. B., Adel'shin A. A., Grishin B. M., Bikunova M. V.

Oilfield wastewater treatment with the use of centrifugal apparatuses

Summary

The task of the studies was improving the efficiency of polydisperse oil particles removal from oilfield wastewater. The process is complicated with the presence of adsorption (inhibiting) shells of mechanical impurities on fine-dispersed oil droplets. A new technology of oilfield wastewater treatment is suggested that provides for wastewater pretreatment in hydraulic cyclones equipped with cylindrical (tubular) overflow chambers that allow stimulating the processes of oil droplets coalescence. The flow sheet of a pilot plant for studying the processes of emulsified oil droplets growth is presented. The plant comprises a hydraulic cyclone connected to the upper and lower overflow chambers. Oilfield wastewater of «Tatneft» OJSC was chosen as a test subject (oil concentration 710–800 mg/l). It was stated that the coalescence efficiency was determined by the vortex value parameter in overflow chambers and by the time of wastewater treatment in the centrifugal field. Processing the test results on the oil droplet size distribution showed that the optimal vortex parameter values for the upper overflow chamber of the hydraulic cyclone were within 20–23; whereas for the lower overflow chamber – 16–18.5. The recommended time of wastewater treatment in the upper and lower overflow chambers was relatively 24.5 and 18.5 seconds. It was experimentally determined that the residual oil concentration after oilfield wastewater treatment in the hydraulic cyclone and two hours sedimentation was less than 72 mg/l at 91% treatment efficiency. It was 6% higher compared with the wastewater sedimentation efficiency after treatment in the hydraulic cyclone only. The design of BGTO plant (hydraulic cyclone block – overflow chamber – sedimentation tank) is suggested that provides for the efficient treatment of oil effluents on industrial scale.

Key words

settling , hydrocyclone , oil effluents , oil droplet coalescence , overflow chamber , treatment plant