US 5,462,653 A · Apparatus for continuous polymer filtration

Abstract

An improved continuous large area polymer filter employs a single valve to control molten polymer flow into and out from at least two but preferably three or more filter assemblies. In a neutral position the valve apportions flow equally to each of the filter assemblies. When filters in any one of the assemblies becomes clogged and requires cleaning or replacement, the valve is repositioned to prevent flow into and out from the clogged assembly while continuing to apportion flow among the remaining assemblies. A small amount of polymer is bled from the selected assembly to effect depressurization and the assembly is removed, restored to function and replaced. The valve is repositioned to allow a slow bleeding of polymer into the restored assembly and the bleed valve is opened to allow air and air entrapped polymer to be removed from the assembly before returning it to service. When the bleed valve flow has stabilized the valve is once again repositioned to allow full flow into and out from the serviced assembly and to apportion flow to each assembly. The valve has mechanical stops to prevent flow from being blocked to all of the assemblies simultaneously and a shield is attached to the valve to prevent access to operating assemblies. The shape of the filter cavities is tapered toward the output end to reduce the volume of molten polymer entrapped stagnantly between the cavity and the filter therein.

Claims29

Dependent claims

A filter apparatus for uninterruptably filtering molten polymer comprising:

supply means for flowing molten polymer under pressure;
a plurality of separate filter paths containing respective removable filters therein;
a common valve means for selectively apportioning said flowing polymer among said plurality of filter paths in parallel, said valve means having a normally neutral position providing equal flow into and out from each of said filter paths, a first plurality of positions wherein flow is completely blocked into and out from a respective selected filter path, and a second plurality of positions wherein trickle flow is allowed into said selected path while flow out from said selected path is completely blocked;
means for selectively bleeding air and air-entrained polymer from said selected path;
and
passage means for combining polymer flow from said plurality of separate filter paths into a common outflow path.

3 more elements

A filter apparatus for molten polymer having plural filter elements and wherein selected filter elements can be replaced without interrupting polymer flow through the apparatus, said apparatus comprising:

an elongate housing;
an inlet passage defined in said housing for receiving flowing molten polymer under pressure;
multiple cavities extending longitudinally through said housing, said cavities being oriented in n groups, where n has a value of at least one, each group comprising m cavities where m has a value of at least two;
a plurality of elongate candle filters, each disposed in a respective one of said cavities;
a common valve means for selectively delivering the received flowing polymer to said groups of cavities in parallel flow relation and conducting polymer from said filters in said cavities;
said common valve means including at least (n+1) operative positions, wherein in each of n positions said valve means blocks polymer flow into a respective group of said cavities and blocks polymer flow from filters disposed in said respective group of cavities, and in one position said valve means permits polymer flow into all of said groups cavities and out from all of said filters;
plural cross passage means, each in a respective cavity group for conducting flowing polymer received from said valve means in parallel to each cavity in said respective group;
and
outlet passage means for combining polymer outflow from all of said filters that are not blocked by said common valve means.

6 more elements

A filter apparatus for uninterruptably filtering molten polymer comprising:

supply means for flowing molten polymer under pressure;
a plurality of separate filter paths containing respective removable filters therein;
valve means for simultaneously apportioning said flowing polymer among said plurality of filter paths in parallel, said valve means having a normally neutral state wherein substantially equal flow is simultaneously provided into and out from each of said filter paths, a first plurality of states in each of which flow is completely blocked into and out from a respective selected filter path, and a second plurality of states in each of which trickle flow is allowed into a respective selected filter path while flow out therefrom is completely blocked;
means for selectively bleeding air and air-entrained polymer from said respective selected path in said second state;
and
passage means for combining polymer flow from said plurality of separate filter paths into a common outflow path.

3 more elements

Dependencies are inferred from the claim text.

Apparatus for continuous polymer filtration

Life of this patent

Apparatus for continuous polymer filtration

Life of this patent

Abstract

Claims29