US 5,320,753 AGranted

Continuous filter

AssigneeThe Dow Chemical Company

InventorsPeter T. Keillor, III, William A. Kirksey

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Abstract

Filtration process and filters for use with materials such as, but not limited to, melts, utilizing a band of filter medium sealed in the filter rollers to seal the material from the outside. In one embodiment, the seal rollers reduce to a minimum the leakage of melt to the outside and make it possible to advance the filter medium through the filter continuously. In various embodiments, the filter medium can be advanced either by the takeup spool or by driving the seal rollers and the rate of movement of the filter medium through the filter can be controlled to maintain a constant pressure drop across the filter. Two component wear-resistant seals are also provided. Maintaining constant conditions through continuous advancement of the filter medium during filtration yields higher product quality and dimensional stability.

Claims22

Dependent claims

An apparatus for continuously filtering contaminants from a heat-softened plastic material containing contaminants, said apparatus comprising:

(i) a housing with a passage for the flow of material therethrough, the passage having an inlet for receiving material containing contaminants and an outlet for discharging filtered material from which contaminants have been removed;
(ii) a filter band having a portion capable of continuously moving across the passage, said filter band portion positioned between the inlet and outlet of the passage so that material passing from inlet to outlet passes through the filter band portion, the filter band having an upstream side adjacent the inlet and a downstream side adjacent the outlet;
(iii) a first pair of roller means for sealing the portion of the filter band through which material passes, the roller means comprising seal rollers, means for rotatably mounting said seal rollers within said housing, said seal rollers positioned on opposite sides of the passage and in direct contact with the upstream side of the filter band;
(iv) elastomeric seals located at contact points between the seal rollers and the housing to provide a seal therebetween;
(v) a filter support located in the passage, between the first pair of roller means and against the downstream side of the filter portion that faces the outlet of the passage, to support the portion of the filter band capable of moving across the passage when material flows through the filter band;
and
(vi) positioning means for urging the first pair of roller means for sealing against the upstream side of the filter band and urging the downstream side of the filter band against a surface in the housing thereby providing a seal sufficiently tight to prevent leakage of material from the housing;
and
wherein the surface in the housing against which the roller means urges the downstream side of the filter band comprises the surfaces of seal rollers of a second pair of roller means for sealing located opposite to the first set of roller means and on the downstream side of the filter band, and means for rotatably mounting said second pair of roller means within said housing.

6 more elements

An apparatus for continuously filtering contaminants from a heat-softened plastic material containing contaminants, said apparatus comprising:

(i) a housing with a passage for flow of materials therethrough, the passage having an inlet for receiving material containing contaminants and an outlet for discharging filtered material from which contaminants have been removed;
(ii) a filter band having a portion capable of continuously moving across the passage, said filter band portion positioned between the inlet and outlet of the passage so that material passing from inlet to outlet passes through the filter band portion, the filter band having an upstream side adjacent the inlet and a downstream side adjacent the outlet;
(iii) a first pair of roller means for sealing the portion of the filter band through which material passes, the roller means comprising seal rollers, means for rotatably mounting said seal rollers in the housing, said seal rollers positioned on opposite sides of the passage and in direct contact with the upstream side of the filter band;
(iv) a flat plate filter support with holes therethrough for flow of material that has passed through the filter band, said filter support located in the passage, between the pair of roller means and against the downstream side of the filter portion capable of moving across the passage to support said portion of the filter band;
and
(v) positioning means for urging the first pair of roller means for sealing against the upstream side of the filter band and urging the filter band against a surface in the housing thereby providing a seal sufficiently tight to prevent leakage of material from the housing.

3 more elements

An apparatus for continuously filtering contaminants from a heat-softened plastic material containing contaminants, said apparatus comprising:

(i) a housing with a passage for the flow of material therethrough, the passage having an inlet for receiving material containing contaminants and an outlet for discharging filtered material from which contaminants have been removed;
(ii) a filter band having a portion capable of continuously moving across the passage, said filter band portion positioned between the inlet and outlet of the passage so that material passing from inlet to outlet passes through the filter band portion, the filter band having an upstream side adjacent the inlet and a downstream side adjacent the outlet;
(iii) a first pair of roller means for sealing the portion of the filter band through which material passes, the roller means comprising seal rollers and means for rotatable mounting said first pair of seal rollers within said housing said seal rollers positioned on opposite sides of the passage and in direct contact with the upstream side of the filter band;
and
(iv) a filter support, located in the passage between the first pair of rollers and against the downstream side of the filter portion that face the outlet of the passage, to support the portion of the filter band capable of moving across the passage;
(v) positioning means for urging the first pair of roller means for sealing against the upstream side of the filter band and urging the filter band against surfaces of second seal rollers of a second pair of roller means for sealing against the downstream side of said filter band, means for fixedly holding axes of the second pair of roller means relative to the housing, the second seal rollers being located opposite the first pair of roller means and on the downstream side of the filter band, means for rotatably mounting said second pair of roller means such that the surfaces of the second seal rollers rotate when the filter band moves across the passage.

3 more elements

An apparatus for continuously filtering contaminants from a heat-softened plastic material containing contaminants, said apparatus comprising:

(i) a housing with a passage for the flow of material therethrough, the passage having an inlet for receiving material containing contaminants and an outlet for discharging filtered material from which contaminants have been removed;
(ii) a filter band having a portion capable of continuously moving across the passage, said filter band portion positioned between the inlet and outlet of the passage so that material passing from inlet to outlet passes through the filter band portion, the filter band having an upstream side in contact with unfiltered material and a downstream side in contact with filtered material;
(iii) a first pair of roller means for sealing the portion of the filter band through which material passes, the roller means comprising seal rollers and means for rotatably mounting said seal rollers within said housing, said seal rollers positioned on opposite sides of the passage and in direct contact with the upstream side of the filter band;
(iv) elastomeric seals located at contact points between each of the seal rollers and the housing to provide a seal therebetween;
(v) a filter support located in the passage against the downstream side of the filter band, between the first pair of roller means, to support the filter band portion capable of continuously moving across the passage when material flows through the filter band;
and
(vi) positioning means comprising, a second pair of roller means, the positioning means including means for urging said second pair of roller means against the downstream side of the filter band and urging the upstream side of the filter band against a surface in the housing thereby providing a seal sufficiently tight to prevent leakage of material from the housing.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/061,877Filed 17 May 1993 · continuation in part
Priority: 18 Jun 1991
Granted: 14 Jun 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

B01D 33/056
Filters with filtering elements which move during the filtering operation: construction of filtering bands or supporting belts, e.g. devices for…
B01D 33/04
Filters with filtering elements which move during the filtering operation: with filtering bands or the like supported on cylinders which are…
B29C 48/692
Filters or screens for the moulding material: in the form of webs displaceable for using adjacent areas consecutively
B29C 48/05
Characterised by the shape of the extruded material at extrusion: filamentary, e.g. strands