Sepn. of oil-in-water emulsions - using ultrafiltration with membrane not permeable by oil with physical or chemical pretreatment

摘要

Oil in water emulsions are sepd. using ultrafiltration with a membrane which is permeable to water but not to oil. This involves known physical or chemical processes or a combination of both for reducing the oil content prior to entering the ultrafilter. In order to operate the process continuously, a proportion of the oil enriched emulsion recycled from the ultrafilter is returned to the preseparation phase to remove the oil. Together with treated fresh feed, the recycled emulsion from which the bulk of the oil has been removed is fed back to the ultrafiltration feed tank. The preseparation process is held at such a pressure that the temp. can be well above the normal boiling pt. of the mixture. For use in preparing pure water from a water oil emulsion. The problem is that ultrafiltration is slow if an excessive amount of oil is present. Generally speaking separation becomes impossible once the oil content reaches 50%. The system described allows the bulk of the oil to be removed by other means e.g. centrifuging, only leaving the final frame to be removed by the ultrafiltration. This prolongs filter life and allows a virtually-continuous process to be developed.