Liquid purification or separation – Processes – Using magnetic force
Reexamination Certificate
2000-10-24
2004-06-01
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Processes
Using magnetic force
C210S745000, C210S085000, C210S143000, C210S222000, C210S223000, C210S259000, C210S322000, C209S223100, C209S232000
Reexamination Certificate
active
06743365
ABSTRACT:
DESCRIPTION
The present invention relates to a magnetic filtration system for filtering ferrous and some non-ferrous material from a fluid in which said material is in suspension.
The magnetic filter device of a previous application (9515352.4) (WO97/04873) (MARLOWE) comprises an annular magnet disposed between a pair of annular metal plates. Fluid flows into the device through recesses in the metal plates, and returns through the centre of the device when used in conjunction with a conventional filter.
Another device (FREI) (U.S. Pat. No. 2,149,764) uses a series of cylindrical magnets separated by a series of metal baffle plates, which are magnetised through contact with the magnets. The flux fields generated are designed to collect particles on the plates themselves and also around the edges of the perforations in the plates. A metal screen abuts the edges of the plates and is therefore magnetised through contact with it. The screen forms an envelope around the arrangement and is designed to increase the magnetised area in the actual flow path. Disadvantageously, however, the metal particles, which build up on the screen, form an ever-increasing obstruction to flow. In addition, any particles collected on the plates are exposed to the flow, and are in danger of being washed off. In the present invention, the magnetic flux direction and properties are used to advantage as described later herein.
A magnetic filtration system for filtering ferrous and some non-ferrous material from fluid, in which said material is in suspension, comprises inlet and outlet means. The system can advantageously be inserted at almost any point in a fluid system. The filtration system comprises one or a plurality of collection units that can be disposed in a housing. Magnetisable material, in particular ferrous particles and some non-ferrous particles drawn along with the ferrous particles can be collected in the collection units. Particles are advantageously magnetically held out of the flow path, and therefore do not result in obstruction of flow. The collection units can be readily removed from the housing, to be dismantled, cleaned of any material collected and re-installed for re-use in the system. In an embodiment where the magnet is an electromagnet, when the electromagnet is active, material can be collected from the fluid, and when the electromagnet is deactivated, the material collected can be removed from the units and disposed from the system.
The present invention is applicable to fluid systems that are subject to high flow rate and pressure.
In accordance with one aspect of the present invention, there is provided a magnetic filtration system for filtering magnetisable material from a fluid in which said material is in suspension comprising inlet means and outlet means, in which one or a plurality of collection units is disposed, each collection unit comprising one or a plurality of plates or plate arrays disposed either side of one or a plurality of magnets so that the plates or plate arrays have opposing polarities, wherein portions of the plates or plate arrays extend beyond part or all of an edge or edges of one or a plurality of said magnets, facing plates have one or a plurality of apertures, and wherein facing apertures define a region of magnetic repulsion, and facing plate portions define therebetween, a region of magnetic attraction and magnetisable material collection, such that the magnetic flux fields thus created facilitate preferential collection of magnetisable materials in the collection region between facing portions rather than in the region between said facing apertures.
It is an advantage that the facing collecting regions alternate with facing apertures such that the attractive flux fields generated in the collection regions and the repulsive fields disposed either side thereof facilitate collection in a volume sandwiched between exposed facing plate portions. Particles can thus be retained in three-dimensional space rather than on merely the magnetised surface area that is exposed to fluid flow. Each collection unit thus offers greater capacity for debris than that possible with the exposed surface area of its component parts when disassembled. The repulsive forces in the apertures of each collection unit divert magnetisable material from the apertures so that they collect preferentially between facing plate portions rather than in the apertures, to thus allow fluid to continue to flow through the unit even at capacity.
Advantageously, the respective plates of adjacent collection units having like polarity are disposed adjacent to one another so as to substantially restrict the collection of magnetisable particles to the collection regions substantially within the interior of the collection units. An individual collection unit will have its own distribution of magnetic flux, part of which are regions of magnetic attraction between the facing plate portions of the unit. If another unit is disposed so that the respective neighbouring plates have unlike polarity, one North, the other, South, the flux existent within the collection unit (as an individual) will be dispersed through the generation of further magnetic fields of attraction between adjacent collection units. If the collection unit is disposed beside another so that like poles of adjacent plates are facing, then the repulsive forces thus created between adjacent collection units will condense the attractive magnetic flux towards the region between facing plate portions, more so than when there are no further adjacent units.
Advantageously, there is provided a housing made of a non-magnetisable material. This limits magnetisable material collection to the collecting regions within the collection units if the collection units are disposed in close proximity to the interior of said housing. The housing can be made of a magnetisable material if said collection units still facilitate fluid passage therethrough even when filled with contaminant.
It is an advantage that there is provided a housing integral to a fluid flow system, said filtration system still permitting fluid flow the through even at capacity.
In one embodiment, each collection unit can be further separated from an adjacent collection unit by a spacing member. This allows for the better utilisation of the available magnetic flux density.
It is an advantage that the spacing member is non-magnetic. It is also an advantage in certain instances that the spacing member is magnetic. The magnetisation or non-magnetisation of the spacing member is discussed later.
It is an advantage that the apertures in respective collection units, which are in closer proximity to the inlet means, are larger than those of units disposed nearer the outlet means. This provides collection units of varying magnetic strength along the direction of flow and alleviates any collection bias on the collection units closest to the inlet.
It is preferred that alignment means is provided for disposing the apertures and plate portions in facing plates of a collection unit in substantial axial alignment. As fluid flows more smoothly through apertures that are aligned, regions of particle collection surrounding the apertures are thus exposed to a minimum of fluid turbulence, thus aiding in the retention of material collected. The presence of an aperture on a plate creates adjacent plate regions of like polarity, which thus generate between them, an axial region of magnetic repulsion. By aligning a pair of apertures of facing plates, the region of magnetic repulsion extends through an axial length of the collection unit. As the apertures are also the means for fluid flow through the collection unit, the path of fluid flow is also the region from which magnetisable particles, suspended in the fluid, will be repelled. As the repulsive force acts radially, particles will tend to be redirected from the fluid flow path and repelled towards the adjacent region between the plate portions either side of the axial region of repulsion. The plate portions have between them, an attractive magnetic
Reifsnyder David A.
Smith Gambrell & Russell
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