Improvements in cleanout systems for filters

摘要

A "wet clean-out" system for tanks housing filter elements used for filtration of dry-cleaning solvent prior to recovery or re-circulation in dry-cleaning plants comprises a jet positioned within and adjacent to the bottom of, the filter tank, for introducing a flushing liquid to agitate accumulated dirt, and outlet adjacent the jet for withdrawing suspended dirt, and a valve in the outlet, the valve incorporating a "pusher plate" which covers the outlet opening when the valve is closed, and causes accumulated dirt to be removed from the outlet opening when the valve is opened (see Groups I and XVII). A tank 10 housing filter elements 11 from which filtered solvent is withdrawn through a manifold 12 is periodically cut out of the dry-cleaning system when sufficient dirt has accumulated on the bottom of the tank after repeated back-washing of the elements 11. Solvent is first drained to the level of a pipe 13, and that remaining in the tank is circulated through pipes 15, 16, 17, 19, 20 and 22 by a pump 14, also cut out of the dry-cleaning system by closing of the valves 25 and 27. From pipe 22 solvent is forced into the bottom of the tank 10 through a slot 24a in an elbow 24 to set up a cyclic circulation for re-suspending the dirt, and through a hole 28a in a plug 28 for removing accumulated dirt from the vicinity of a valve 29. After a time the circulation is discontinued, and valve 29 is opened by screwing in a threaded rod 31. The valve disc 32 at the other end constitutes a "pusher-plate" for removing any remaining unsuspended dirt from the opening, and the suspension is pumped via pipes 30, 35, 36, 17, 19, 37 to a centrifugal extractor 34 incorporating a strainer bag via pipe 38, or to a body of water contained in the lower tapered portion of a settling tank 41 via pipe 47. In the latter case the mixture is allowed to stand for at least four hours, after which solvent is withdrawn through pipes 46 and a dirt-and-water mixture through pipe 49. A settling tank such as 41 may be provided in addition to a centrifugal extractor such as 34.