Magnetic filter

Abstract

A magnetic filter carriage (16) for use in filtering contaminants from fluid in a high pressure fluid flow comprises a frame (18, 20, 22) arranged to support a plurality of magnet filter rods (42), such that the rods (42) are each supported at both ends thereof in a fixed orientation, for example parallel to one another. The frame (18, 20, 22) is adapted to be inserted within a pressure vessel (4) across the direction of fluid flow between a fluid inlet (7) and a fluid outlet (9) of the pressure vessel (4), and may be arranged such that more than about 90% of the flow across the vessel (4) passes through the frame (18, 20, 22). The rods (42) are mounted in a plurality of cassettes (36) which are easily removable for cleaning or replacement.

Claims

1. A magnetic filter carriage for use in removing magnetically susceptible contaminants from fluid in a fluid flow, the magnetic filter carriage comprising: a frame arranged to support a plurality of magnetic rods, the frame comprising: a first side plate, a second side plate and a guide plate extending between the first side plate and the second side plate, the guide plate including a plurality of locating pegs extending from an inner surface of the guide plate, wherein the frame is adapted to be mounted within a pressure vessel across a direction of the fluid flow between a fluid inlet and a fluid outlet of the pressure vessel; and two or more removable cassettes mounted in the frame, each removable cassette of the two or more removable cassettes comprising: a retaining plate including locating apertures extending therethrough, each locating aperture being configured to fit over a respective one of the plurality of locating pegs of the frame, and at least two magnetic rods of the plurality of magnetic rods attached to the retaining plate so as to be aligned in a row of magnetic rods and such that each magnetic rod of the at least two magnetic rods is supported by the removable cassette at both a first end and a second end of the magnetic rod in a fixed orientation, wherein one of the locating apertures is aligned with the row of magnetic rods and disposed between two of the at least two magnetic rods.

2. A magnetic filter carriage as claimed in claim 1, further comprising guide members provided on an outer side of the frame for engaging with cooperating members of the pressure vessel so as to allow sliding movement between the magnetic filter carriage and the pressure vessel, wherein the frame comprises a side wall, and wherein one of the guide members extends a length of the side wall.

3. A magnetic filter carriage as claimed in claim 1, wherein the frame is arranged to support the plurality of magnetic rods such that each magnetic rod of the plurality of magnetic rods extends substantially parallel to the other magnetic rods of the plurality of magnetic rods.

4. A magnetic filter carriage as claimed in claim 1, in which each removable cassette of the two or more removable cassettes comprises: a pair of mounting blocks or plates attached to opposing ends of the at least two magnetic rods, and wherein the pair of mounting blocks or plates is attachable to opposite sides of the frame.

5. A magnetic filter carriage as claimed in claim 1, wherein the two or more removable cassettes are arranged in a plurality of rows of cassettes in the frame, and wherein adjacent rows of the plurality of rows of cassettes comprise a different number of magnetic rods of the plurality of magnetic rods.

6. A magnetic filter carriage as claimed in claim 1, each removable cassette of the two or more removable cassettes carrying three or four magnetic rods of the plurality of magnetic rods.

7. A magnetic filter carriage as claimed in claim 1, wherein each magnetic rod of the plurality of magnetic rods comprises a plurality of magnets.

8. A magnetic filter carriage as claimed in claim 1, wherein each magnetic rod of the at least two magnetic rods is removable from the removable cassette.

9. A system comprising a pressure vessel and a magnetic filter carriage, wherein the pressure vessel comprises opposed side walls comprising guide members for cooperating with guide members on the magnetic filter carriage, and wherein the magnetic filter carriage comprises: a frame arranged to support a plurality of magnetic rods, the frame comprising: a first side plate, a second side plate, and a guide plate extending between the first side plate and the second side plate, the guide plate including a plurality of locating pegs extending from an inner surface of the guide plate wherein the frame is adapted to be mounted within the pressure vessel across a direction of a fluid flow between a fluid inlet and a fluid outlet of the pressure vessel; and two or more removable cassettes mounted in the frame, each removable cassette of the two or more removable cassettes comprising: a retaining plate including locating apertures extending therethrough, each locating aperture being configured to fit over a respective one of the plurality of locating pegs of the frame, and at least two magnetic rods of the plurality of magnetic rods attached to the retaining plate so as to be aligned in a row of magnetic rods and such that each magnetic rod of the at least two magnetic rods is supported by the removable cassette at both a first end and a second end of the magnetic rod in a fixed orientation, wherein one of the locating apertures is aligned with the row of magnetic rods and disposed between two of the at least two magnetic rods.

10. A system as claimed in claim 9, comprising an operable hatch or lid of sufficient dimension so as to allow insertion and removal of the magnetic filter carriage in to and out of the pressure vessel.

11. A system as claimed in claim 9, in which the magnetic filter carriage is arranged such that the cross-sectional area of the magnetic filter carriage receives at least about 90% of fluid flow through the pressure vessel.

12. A system as claimed in claim 9, in which the pressure vessel is configured to contain fluid at a pressure of between 10 and 50 bar.

13. A system as claimed in claim 9, in which the pressure vessel is configured to contain fluid at a temperature of between 10 and +50 C.

14. A system as claimed in claim 9, in which the magnetic filter carriage is configured to remove magnetically susceptible contaminants from a fluid flowing at a rate of between 750 and 2000 m.sup.3 per hour.

15. A system as claimed in claim 9, in which each removable cassette of the two or more removable cassettes comprises: a pair of mounting blocks or plates attached to opposing ends of the at least two magnetic rods, wherein the pair of mounting blocks or plates is attachable to opposite sides of the frame.

16. A system as claimed in claim 9, wherein the two or more removable cassettes are arranged in a plurality of rows of cassettes in the frame, and wherein adjacent rows of the plurality of rows of cassettes comprise a different number of magnetic rods of the plurality of magnetic rods.

17. A system as claimed in claim 9, wherein each magnetic rod of the plurality of magnetic rods comprises a plurality of magnets.

18. A system as claimed in claim 9, in which the pressure vessel is configured to contain fluid at a pressure of between 30 to 100 bar.

19. A system as claimed in claim 9, in which the fluid is aviation fuel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order that the present invention may be more readily understood, reference will now be made by way of example to the accompanying drawings, in which:

(2) FIG. 1 is a perspective view of a filter arrangement comprising a pressure vessel including a magnetic filter carriage;

(3) FIG. 2 is a side view of the filter arrangement of FIG. 1;

(4) FIG. 3 is a perspective view of a filter carriage including filter rods;

(5) FIG. 4 is a perspective view of the carriage frame of FIG. 3; and

(6) FIG. 5 is a perspective view of a rod cassette of FIG. 3.

DETAILED DESCRIPTION

(7) Referring now to FIGS. 1 and 2, a high pressure pipe line 2 is shown for carrying fluid such as a petroleum product, for example an aviation fuel. A filtration path including a pressure vessel 4 is provided in the pipe line by means of a pair of elbow sections 6, and a pair of large diameter pipe sections 8 on either side of the vessel 4. A bypass flow path is also provided in the form of a bypass pipeline 10 for bypassing the pressure vessel 4, with valves 12 for selecting the required path.

(8) Typical dimensions of the pipe might be about greater than or equal to about 6 inches, 8 inches, or 12, 18 or 24 inches with the large diameter pipe being about 0.5 to 1.5 or 1 to 2, 1.5 to 3 metres in diameter, and the vessel approximately 1, 1.5 or 2.0 metres tall, and 0.5 to 2, or 0.5 to 1.5 or 0.5 to 1 metres wide. However, other dimensions and multiple inlets or outlets are also possible.

(9) The elbow sections 6 are each connected through a wall of one of the large diameter pipe sections 8, which extend substantially parallel to the pipe line. The vessel 4 is substantially cylindrical, extending substantially perpendicular to the large diameter pipe sections 8, and the large diameter sections 8 are connected through the walls of the vessel in opposed relation to provide an inlet 7 and outlet 9 respectively for the fluid flow across the vessel 4. Typical dimensions of the pipe might be about 8 inches, with the large diameter pipe being about 0.5 metre in diameter, and the tank approximately 1.1 metres tall, and 580 mm wide. However, other dimensions and multiple inlets or outlets are also possible.

(10) The vessel includes an access hatch 14 at the top, which may be hingedly opened. The vessel 4 supports a magnetic filter carriage 16 extending across the diameter of the vessel perpendicular to the flow direction between the inlet and the outlet. The carriage carries a plurality of magnetic filter rods, as will be described below, for filtering particles from the flow.

(11) Referring now to FIGS. 3 and 4, the carriage 16 comprises a frame including a pair of side plates 18, a lower guide plate 20 extending between the lower edges of the side plates 18, and a block cage 22 extending between the upper edges of the side plates 18.

(12) The side plates 18 are rectangular, and are each provided on an outer face 24 thereof with a pair of parallel elongate flanges 26 extending along the length thereof and serving as guide rails for cooperating with corresponding tracks (not shown) on the side walls of the pressure vessel 4. The side plates 18 are preferably welded along their short sides 28 to opposing short sides 30 of the guide plate 20, which is rectangular and has a corresponding width. The side plates may alternatively be removable to allow alternative configurations to be used for accommodating different carriage designs.

(13) The guide plate 20 has locating pegs 32 extending from an inner face 34 thereof for locating a plurality of magnet rod cassettes 36. The block cage is also rectangular, and is preferably welded along opposite short sides 40 to the upper short sides 38 of the side plates.

(14) Referring also to FIG. 5, each magnet rod cassette 36 is sized so as to be convenient for manual handling, for example comprising three or four long rods 42. The rods 42 each comprise a tube containing a plurality of magnets, as is well known in the art. The rods are each attached at their lower ends 44 to an elongate retaining plate 46 such that the ends 44 are aligned along the length of the plate. The retaining plate 46 also comprises locating apertures 48 between the rods sized to fit over the locating pegs 32 in the guide plate 20 of the carriage frame so as to hold the cassette firmly in place and reduce any flow induced vibration.

(15) At the top end 50, the rods pass through corresponding elongate retaining blocks 52 such that they extend substantially parallel and in fixed relation to each other. Each retaining block 52 has a width corresponding to lengthwise gaps 54 in the block cage 22 so as to fit closely therein when the cassette 36 is fitted in the frame 16 as can be seen from FIGS. 3 and 4. The block cage 22 additionally has retaining bars 56 which are spaced apart to correspond with the length of each block 52.

(16) The blocks 52 are each provided with a handle 58 for lifting the cassettes out of the frame. A retaining frame 60 may be secured to the block cage 22, for example using quick release fasteners 62 to retain the cartridges in the frame. The side plates 18 are each provided with a pair of steel shackles 64 which can be used to lift and lower the carriage 16.

(17) The frame and cassettes are arranged to provide offset rows of rods. Thus in this example there are three rows of two cassettes. The outer rows comprise two cassettes containing three rods each, and the inner row comprises two cassettes, one containing four rods and the other containing three rods.

(18) In use, the hatch 14 of the vessel 4 is opened, the carriage 16 is lowered into the vessel 4, and the hatch is closed. With the valves 12 directing the flowthrough the filter path, the flow enters an elbow section 6, and is directed into a larger diameter pipe section 8. Consequently, the speed of the flow is reduced. The fluid then enters the vessel 4 through the inlet 7, with the speed once again reduced due to the larger cross-sectional area presented by the vessel, and passes through the filter carriage and between the magnet rods. Particles such as magnetised steel and rust particles are attracted by the magnetic fields and adhere to the rods. The filtered fluid exits the vessel 4 through the outlet 9 into the other large pipe section 8 and back to the pipeline via the elbow section.

(19) As material builds up on the rods, the ability of the magnetic field to capture further particles decreases until the level of filtration achieved falls below useful levels. The rods therefore need to be cleaned or replaced periodically. With this arrangement, each cassette can be separately removed for cleaning or replacement. Thus any damaged or worn cassette can be replaced allowing continued operation.

(20) Additionally each rod may easily be removed, from the cassette. The rods may be cleaned using a wash solution which is miscible or compatible with the fluid within the pipe, or with non-compatible liquids (such as water when the fluid is a fuel).