GB1566172A

GB1566172A - Filter device

Info

Publication number: GB1566172A
Application number: GB43448/77A
Authority: GB
Original assignee: Metzeler AB
Current assignee: Metzeler AB
Priority date: 1977-10-19
Filing date: 1977-10-19
Publication date: 1980-04-30

Description

(54) A FILTER DEVICE (71) We, METZLER AB, a joint stock company organised under the laws of Sweden, of S-543 00 Tibro, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a filter device.

There is no conventional filter means which is sufficiently effeotive to separate oilproducts from water contaminated with such products, since after the filter has been in use for some time, oil-particles migrate through the filter and pass to the outlet of the filter housing. Because of this, it has become a practice to strew different kinds of absorbent material, such as foamed plastics, over the surface of the contaminated water thereby to soak up the oil floating on the surface of said water. Although a large per centage of the oil present is absorbed by the foamed plastics, the method is only suitable for use in applications such as cleaning of the floors of workshops and like floors which become soiled with oil and which are washed down with water to cleanse the same.

It is not normally possible to remove with conventional filters all the minute particles of oil suspended in the waste water thus obtained, which particles ultimately reach the sewage system to which the drain of the workshop floor in question is connected.

When this sewage system discharges into a purification plant which includes a biological Purification stage, the microiorganisms will be destroyed by the particles of oil contained in the effluent, thereby causing the, biological decomposition of organic material to be impaired.

Neither can such known filter means be used effectively to purify waste-water ob tained when flushing the oilaanks of ships for example, especially since it is not prac ticaily possible in this respect to expose the water to an oil-absorbing material, and consequently after the conventional filter means gi present employed to remove oil from tile wash-water has been used for some time, oil will migrate through the filter of said means to mix with the water discharged to the sea. Since the amount of oil carried in this way through the filter means can be quite considerable, the problem is a serious one.

According to the invention, there is provided a filter device for separating a dispersed phase of petroleum products from a second fluid phase carrying such products, the device including an inlet, an outlet, and a filter element disposed between the inlet and the outlet, which element is of a material made by: a) subjecting a soft, open cellular plastics material to shock-pressure treatment to rupture the cells of said material; b) dividing said cellular plastics material into a plurality of smaller pieces; c) applying an adhesive to at least part of at least one surface of each said. smaller pieces; and d) joining said smaller pieces together under pressure to form the filter element material.

Exemplary embodiments of the invention will now be described with reference to the accompanying schematic drawings, in which: Figure 1 is a vertical sectional view of a first filter means incorporating a filter element according to the invention Figure 2 is a vertical sectional view of a second filter means; Figure 3 is a vertical sectional view of a third filter means; and Figure 4 is a plan view of the filter means shown in Figure 3.

In Figure 1 there is shown a filter housing sealed against the unintentional ingress of fluid, such as water. and provided with a lid 2. Connected to the housing 1 is an inlet pipe 3 for oil-contaminated water, and an outlet pipe 4. Arranged between the inlet pipe 3 and the outlet pipe 4 is a filter 5.

This filter element 5 comprises a body, which may be self-supporting, manufactured from small pieces of soft foamed plastics material having open cells and which has been subjected to shock-pressure treatment.

The starting material comprises blocks of open cellular foamed plastics material or large pieces of such material and is conveniently shredded or divided in a granulating mill having rotary knives, for cutting the pieces of plastics material to a suitable size. The small pieces of plastics material are then conveniently subjected to the aforementioned pressure-treatment in a hammer mill. The foamed plastics material may also be subjected to said pressure-treatment in a shredder having teeth which subject the plastics material to pressure pulses or impact forces sufficient to rupture the cell walls at the same time as the plastics material is shredded or divided into smaller pieces. It is also possible to first subject the starting material e.g. blocks of foamed plastics material, to pressure impulses or impact forces and then to divide said blocks into the required size. It is preferred however, that the materal is subjected to said pressuretreatment at the same time as it is divided.

The resulting small pieces of foamed plastics material, which may be optionally treated with a hydrophobic substance, are then formed into bodies of desired shape and size by providing at least parts of the surfaces of the foamed plastics pieces with a hardening and preferably foaming binding agent, whereafter the foamed-plastics bodies are subjected to a pressure of 0.01--0.4 kg/cm3 during the hardening process. The binding agent conveniently comprises the same raw material as the plastics body in general. The plastics bodies are either formed initially as filter elements or are cut or sawn to the intended shape and size.

In the Figure 1 embodiment, the housing 1 is assumed to be cylindrical and the filter element 5 comprises a cylindrical, plate-like body. Arranged in the interior of the housing 1, on the wall 7, and extending between the inlet 3 and the outlet 4 is a circular bar 6 which is provided with a lower circular flange 8 on which a net or grid 9 rests, said net forming a support for the filter element 5. The grid can be omitted if the element 5 has a thickness which renders it self-supporting. The vehicle medium flowing in through the inlet 3, which medium may be water or air, will thus pass through the filter element 5 and through the grid 9 to the outlet 4, and particles of oil or emulsion suspended in said vehicle medium will remain in the plastics material of the filter element 5 while water or air will pass through the outlet 4.

Subsequent to the filter element 5 having absorbed oil to about 93% by volume of said element, the element 5 is exchanged for a further element.

In Figure 2 there is shown a further embodiment in which the housing is defined by the walls 'of a well in a floor 10, said well being connected to an outlet 11 extending downwardly through the floor 10. The inlet is formed by a plate 12 provided with throughpassing holes 13 to enable oil-containing water present on the floor to run down into the well or drain in the floor.

Arranged in the well is a cup-shaped filter element 14 made of the same plastics material as the previously described filter element 5. Water contaminated with oil or oil-emulsion will thus collect in the cupshaped filter element 14, and the water will flow through the element out through the outlet 11, whilst the emulsion or oil is absorbed in the filter element. It will be understood that because the oil taken up by the filter element displaces any water therein out of said filter as a result of its capillary-like aotion, the filter will absorb much more oil than will a known filter before becoming saturated. Subsequeunt to the filter element having absorbed the maximum amount of oil that it is capable of containing, which is approximately 93% by volume calculated on the volume of the filter, the cup-shaped filter element 14 is removed and a further element inserted into the well.

Figures 3 and 4 illustrate a further embodiment particularly, although not exclusively, intended for use in large filtermeans which are intended to filter large quantities of contaminated waste-water containing large particles of metal, wire and the like and large oil agglogemations The filter means comprises a liquid-ught housing 15, manufactured for example of sheet steel. The housing has a main bot- tom 16 and side-walls 17, 18, 19 and 20 extending upwardly from said bottom. In the illustrated embodiment the filter housing is open at the top thereof, although it may also be provided with a tightly fitting lid. Connected to the wall 17 is an inlet 21 for the fluid vehicle, which inlet is connected to the broad nozzle 22 in the form of a pipe having open ends. The nozzle 22 is arranged in a chamber 23 defined by parts of the walls 17, 18 and 20 and by a wall 24 extending between the walls 18 and 20, and also by a bottom 25. Arranged in the bottom 25 of the chamber 23 are a plurality of through-openings 26, through which heavy particles, such as pieces of metal, may fall onto the bottom of a separating chamber 27. The separating chamber 27 is defined by a part of the main bottom 16, parts of the walls 17, li8 and 20 and by a wall 28 having a bottom 29 sloping downwardly from said wall 28 towards the wall 17.

Heavier particles in the fluid vehicles will fail to the bottom of the separating chamber 27 and can be removed therefrom through a pipe 30 connected to the bottom portion of the chamber 27. Connected to the forward, substantially vertical wall 24 of the chamber 23 is a chute 31 formed by an extension of the bottom plate 25 and an edgeplate 32 having a flange4ike edge portion 33 bent in towards the wall 24. When the filter is in use, this edge portion 33 lies on a level with an outlet 34 from the housing.

The ends d the chute 31 are sealingly connected to the side walls 18 and 20.

Arranged in the lower portion of the separating chamber 27 is an air-injection nozzle 35 which in the illustrated embodiment comprises a pipe having a plurality of air-injection orifices 36. The pipe 35 extends substantially over the whole width of the housing 15 and air under pressure is supplied to the pipe from a supply line 37 oonnected to one end of the pipe 35, as shown in Figure 4. The other end of the supply line 37 is connected to a compressor (not shown). The pipe 35, whose end remote from the supply line 37 is closed, extends substantially parallel with the straight over-flow edge 33 and at a small distance in front of said edge. When air is supplied to the nozzle or the pipe 35, the upwardly rising air stream forms an air-curtain and will entrain with it large agglomerations of oil and move these agglomerations over the edge 33. These agglomerations are then collected in the chute and subsequently depart therefrom through an outlet 38. There is no risk of such oil agglomerations passing the air-bubble curtain formed by means of the pipe 35, and consequently the fluid vehicle will flow towards the wall 28 and out through outlet openings 381 containing only minor particles of oil. Arranged between the outlet 34 and the separation chamber 27 is a plurality of filter element 39, 40 and 41 of the type aforedescribed.

In the illustrated embodiment, each filter element 39, 40, 41 comprises a rectangular sheet of foamed plastics material of the described type which sealingly abuts the bottom 16 and the side walls 18 and 20 re speotively. The walls 18 and 20 have fixed thereto flanges 42 and 43 for respective filter element and grooves are arranged in the edges of associated filter elements to enable each element to be pushed down against the bottom of the housing with the flanges sliding in said groove.

This greatly facilitates the removal of a saturated filter element. The oil can be readily removed from said saturated filter element by squeezing the same, e.g. in a press whereafter the filter element can be reused.

Filter elements comprising minute pieces of foamed plastics material in accordance with the above have surprisingly been found capable of absortoling approximately 95% by volume of oil without risk of the oil leaving the foamed-plastics material, even when the oil is subjected to pressure from water flowing through said material. This completely unexpected effect cannot be fully explained, although it is thought to be due to the fact that the mechanical shock-like pressure treatment to which the soft foamed plastics is subjected gives rise to the formation of capillaries which are randomly oriented in the finished foam-plastics filter element. This mechanical shock-like pressure-treatment is preferably carried out at the same time as the foam-plastics block is shredded into small pieces, each of which has a greatest dimension of preferably 2-7 mm. These capillaries cause the captured oil to be so firmly held by the filter element that there is no risk of oil migrating out of said element. The cellular foamed plastics material, which as before mentioned shall be a soft material, i.e. a material of the type which can be greatly deformed without cracking or without becoming permanently deformed or without disintegrating, comprises, for example, a polyurethane, a polypropane, a polyethylene or a polyether having open cells and the finished filter element should have a bulk density of 40250 kg/ m3.

WHAT WE CLAIM IS:- 1. A filter device for separating a dispersed phase of petroleum products from a second fluid phase carrying such products, the device including an inlet, an outlet, and a filter element disposed between the inlet and the outlet, which element is of a material made by: a) subjecting a soft, open cellular plastics material to shock-pressure treatment to rupture the cells of said material; b) dividing said cellular plastics material into a plurality of smaller pieces; c) applying an adhesive to at least part of at least one surface of each said smaller pieces; and d) joining said smaller pieces together under pressure to form the filter element material.

2. A device as claimed in Claim 1, wherein the filter element material has been made by a method in which step (b) preceded step (a).

3. A device as claimed in Claim 1, wherein the filter element has been made by a method in which step (a) and step (b) were carried out simultaneously.

4. A device as claimed in any one of the preceding Claims wherein the small

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. fail to the bottom of the separating chamber 27 and can be removed therefrom through a pipe 30 connected to the bottom portion of the chamber 27. Connected to the forward, substantially vertical wall 24 of the chamber 23 is a chute 31 formed by an extension of the bottom plate 25 and an edgeplate 32 having a flange4ike edge portion 33 bent in towards the wall 24. When the filter is in use, this edge portion 33 lies on a level with an outlet 34 from the housing. The ends d the chute 31 are sealingly connected to the side walls 18 and 20. Arranged in the lower portion of the separating chamber 27 is an air-injection nozzle 35 which in the illustrated embodiment comprises a pipe having a plurality of air-injection orifices 36. The pipe 35 extends substantially over the whole width of the housing 15 and air under pressure is supplied to the pipe from a supply line 37 oonnected to one end of the pipe 35, as shown in Figure 4. The other end of the supply line 37 is connected to a compressor (not shown). The pipe 35, whose end remote from the supply line 37 is closed, extends substantially parallel with the straight over-flow edge 33 and at a small distance in front of said edge. When air is supplied to the nozzle or the pipe 35, the upwardly rising air stream forms an air-curtain and will entrain with it large agglomerations of oil and move these agglomerations over the edge 33. These agglomerations are then collected in the chute and subsequently depart therefrom through an outlet 38. There is no risk of such oil agglomerations passing the air-bubble curtain formed by means of the pipe 35, and consequently the fluid vehicle will flow towards the wall 28 and out through outlet openings 381 containing only minor particles of oil. Arranged between the outlet 34 and the separation chamber 27 is a plurality of filter element 39, 40 and 41 of the type aforedescribed. In the illustrated embodiment, each filter element 39, 40, 41 comprises a rectangular sheet of foamed plastics material of the described type which sealingly abuts the bottom 16 and the side walls 18 and 20 re speotively. The walls 18 and 20 have fixed thereto flanges 42 and 43 for respective filter element and grooves are arranged in the edges of associated filter elements to enable each element to be pushed down against the bottom of the housing with the flanges sliding in said groove. This greatly facilitates the removal of a saturated filter element. The oil can be readily removed from said saturated filter element by squeezing the same, e.g. in a press whereafter the filter element can be reused. Filter elements comprising minute pieces of foamed plastics material in accordance with the above have surprisingly been found capable of absortoling approximately 95% by volume of oil without risk of the oil leaving the foamed-plastics material, even when the oil is subjected to pressure from water flowing through said material. This completely unexpected effect cannot be fully explained, although it is thought to be due to the fact that the mechanical shock-like pressure treatment to which the soft foamed plastics is subjected gives rise to the formation of capillaries which are randomly oriented in the finished foam-plastics filter element. This mechanical shock-like pressure-treatment is preferably carried out at the same time as the foam-plastics block is shredded into small pieces, each of which has a greatest dimension of preferably 2-7 mm. These capillaries cause the captured oil to be so firmly held by the filter element that there is no risk of oil migrating out of said element. The cellular foamed plastics material, which as before mentioned shall be a soft material, i.e. a material of the type which can be greatly deformed without cracking or without becoming permanently deformed or without disintegrating, comprises, for example, a polyurethane, a polypropane, a polyethylene or a polyether having open cells and the finished filter element should have a bulk density of 40250 kg/ m3. WHAT WE CLAIM IS:-

1. A filter device for separating a dispersed phase of petroleum products from a second fluid phase carrying such products, the device including an inlet, an outlet, and a filter element disposed between the inlet and the outlet, which element is of a material made by: a) subjecting a soft, open cellular plastics material to shock-pressure treatment to rupture the cells of said material; b) dividing said cellular plastics material into a plurality of smaller pieces; c) applying an adhesive to at least part of at least one surface of each said smaller pieces; and d) joining said smaller pieces together under pressure to form the filter element material.

4. A device as claimed in any one of the preceding Claims wherein the small

pieces of foamed plastics material were joined together under a pressure of 0.01- 0.4 kg/m3.

5. A device as claimed in any one of the preceding claims, wherein said small pieces of foamed plastics material had a maximum individual size of 2 to 7 mm.

before being joined together.

6. A device as claimed in any one of the preceding claims, wherein said filter element material has a bulk density of 40250 kg/cm3.

7. A device as claimed in any one of the preceding Claims, wherein the small pieces of plastics material were coated with a hydrophobic substance before being joined together.

8. A filter device as claimed in any one of claims 1 to 7, wherein said filter element is plate-shaped and is arranged substantially perpendicularly to the direction of fluid flow through the housing.

9. A filter device as claimed in any one of claims 1 to 7, wherein the filter element is cup-shåped.

10. A filter device as claimed in any one of the preceding claims wherein there is provided a housing which is of substantially rectangular cross-section as seen in the direction of fluid flow and has slide rails arranged on two mutually opposing walls, said guide rails being arranged to engage in grooves in the edge portions of the filter element adjacent respective walls.

11. A filter device as claimed in any one of the preceding claims, wherein arranged between the inlet and the filter element is a separation chamber for separating coarse particles from the fluid.

12. A filter device is claimed in claim 11 for separating oil from another liquid wherein arranged in the upper portion of the separation chamber is an upwardly open chute having a substantially horizontal edge member located beneath the normal liquidlevel in the housing; an outlet means connected to said chute and discharging externally of the housing; and an air-injection means arranged in the lower portion of the separation chamber, said airiinjection means being arranged to form an air-bubble curtain between the inlet and the outlet means from the separation chamber and to move oil agglomerations present in the liquid up to said chute.

13. A filter device substantially as hereinbefore described with reference to Figure 1, Figure 2, or Figures 3 and 4 of the accompanying drawings.