Study On The Fine Disposal Of Oily Sewage In The Oil Field Using Modified Polytetrafluoroethylene Membrane

Modified PTFE membrane is developed using techniques such as physicochemical treatment and radio chemotherapy. It's effective in dealing with the fine disposal of oily waste water in the oil field. Laboratory tests indicate that the stream potential of the membrane surface is about -5mV/Kpa, and the Zeta potential is about-20mV; the electric property of the membrane surface is insensitive to the aperture diameter of the membrane, temperature and flow rate; the Zeta potential of the suspended particle in the waste oily water is also negative. The modified PTFE is surface charged which makes it more capable in trapping suspended particles and improving its anti- contamination function. In this paper, the filtering effects of the modified PTFE membrane in fine disposal of field oily waste water is evaluated using deionized water and oily waste water respectively. The affect of operation temperature, flow rate and the aperture diameter of the membrane to the material behavior of the membrane is also discussed. The results indicate that the oil content after filtering is most influenced by operation temperature with flow rate and the aperature diameter coming secondly; the higher operation temperature and flow rate, the bigger oil content in the waster water after filtering. The tests indicate that the eliminating rate of oil and suspentions exceeds 90%.Modified PTFE membrane filtering element is designed and one set of facility has been developed using the modified PTFE membrane(two patents related granted,another one in censorship). In view of the drawback of traditional boost bridge 4QC which need higher DC side operating voltage, a kind of new LOGO type converter topologiy is proposed whose DC side working voltage is reduced to approaching 50%, thus is appropriate for lower voltage applications. A continuous control model and discrete model as to LOGO single phase 4QC system generalized object are established using"average value segregation"and"half period average value method". Systematic experiments are carried out for the creeping current follow-up control and PI voltage control. SICT current-control and PI digital control are designed directly for the LOGO single phase system. Analog and experimental researches of stable state and various dynamic procedures are carried out. The results indicate that the stable state analog and experiment wave pattern coincide with the stable state theoretical analysis perfectly and apply to commercial uses safely. This fine filtering device is used to the backfilling of the low permeable sublayer and ultra-low permeable sublayer oily waster water of Jiangsu oilfield. Field test results indicate that the water quality after filtering is stable and fits for SY/T5329-94 standard demands. Long term performance tests indicate that this filtering device works well with a long backwashing cycle and good regeneration effect, thus fits for the actual service demand. It essentially resolves the technical problems of backfilling water in the low permeable sublayer. Eeconomic effect and social effect is distinguished.