A METHOD AND DEVICE FOR CLEANING NON-FIXED MEDIA FILTERS

摘要

A method and apparatuses are presented for rejuvenating a bed of granular filter medium that has accumulated contaminants during filtration of a liquid stream. The method first includes the step of establishing a small volumetric flow rate of clean filtrate in reverse flow. Then, the filter media is agitated to break-up contaminants that have become agglomerated on the surface of or within the interstitial spaces of the filter media. The agitating step is accomplished by exposing the liquid-full filter media to a jetting stream comprised mostly of a gas mixed with a clean liquid. The jetting stream is dispersed throughout the filter media through a plurality of radial nozzles located within the filter bed. The radial nozzles disperse the gas within the liquid and filter media causing sufficient turbulence and agitation o the filter media granules to liberate the trapped contaminants without the need for high liquid flow rates. The number of nozzles and their placement within the filter bed are varied depending on factors such as size and shape of the filter vessel and the type of filter media being cleaned. The amount of water and gas flowing through the nozzles is also adjusted to provide substantially uniform cleaning of the entire bed. This method results in lower volumes of clean filtrate being consumed in the backwash cycle and the associated storage and recycle of that liquid back into the process. The radial nozzles are each comprised of two horizontal and parallel circular disks spaced apart to create a cylindrical void through which the pressurized gas and liquid jetting stream flows. The apparatuses presented are a singular filter vessel an a plurality of filter chambers within a common filter vessel each containing granular filter media and a plurality of radial nozzles disposed with the media for dispersing the jetting stream throughout during the cleaning and rejuvenation steps of a filtering process.