GB2153246A - Improvements in and relating to filters - Google Patents
Improvements in and relating to filters Download PDFInfo
- Publication number
- GB2153246A GB2153246A GB08402375A GB8402375A GB2153246A GB 2153246 A GB2153246 A GB 2153246A GB 08402375 A GB08402375 A GB 08402375A GB 8402375 A GB8402375 A GB 8402375A GB 2153246 A GB2153246 A GB 2153246A
- Authority
- GB
- United Kingdom
- Prior art keywords
- medium
- layer
- density
- fibres
- microns
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000001914 filtration Methods 0.000 claims abstract description 11
- 239000007788 liquid Substances 0.000 claims abstract description 10
- 239000000835 fiber Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 13
- 229920000728 polyester Polymers 0.000 claims description 9
- 239000004743 Polypropylene Substances 0.000 claims description 7
- 229920001155 polypropylene Polymers 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- -1 polypropylene Polymers 0.000 claims description 6
- 239000002131 composite material Substances 0.000 claims description 5
- 238000009952 needle felting Methods 0.000 claims description 5
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 4
- 239000002657 fibrous material Substances 0.000 claims 1
- 239000010410 layer Substances 0.000 description 48
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 238000011001 backwashing Methods 0.000 description 9
- 239000002245 particle Substances 0.000 description 8
- 238000004140 cleaning Methods 0.000 description 4
- 238000005411 Van der Waals force Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002356 single layer Substances 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical group C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 229920003235 aromatic polyamide Polymers 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000002455 scale inhibitor Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D36/00—Filter circuits or combinations of filters with other separating devices
- B01D36/02—Combinations of filters of different kinds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
- B01D29/111—Making filtering elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
- B01D29/117—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for outward flow filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/50—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with multiple filtering elements, characterised by their mutual disposition
- B01D29/56—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with multiple filtering elements, characterised by their mutual disposition in series connection
- B01D29/58—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with multiple filtering elements, characterised by their mutual disposition in series connection arranged concentrically or coaxially
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2101/00—Types of filters having loose filtering material
- B01D2101/005—Types of filters having loose filtering material with a binder between the individual particles or fibres
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2201/00—Details relating to filtering apparatus
- B01D2201/18—Filters characterised by the openings or pores
- B01D2201/188—Multiple filtering elements having filtering areas of different size
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Filtering Materials (AREA)
Abstract
This invention is concerned with a backwashable filter element comprising a filter medium formed from man made fibres the diameter of which ranges between 10 and 105 microns. The density of the medium varies within the range of 0.05 to 0.35 gm/cc from one side to the other side, the arrangement being such that during filtration liquid to be filtered is passed from the low density side to the high density side. As shown the element has three layers 3, 5, 7 of different densities. <IMAGE>
Description
SPECIFICATION
Improvements in and relating to filters
The present invention relates to filters and a method of filtering water.
Reservoirs for storing petroleum and the like are formed below the ground or below the sea bed in suitable strata. To recover the petroleum or like from the reservoir it is a practice to force water, commonly sea water into the reservoir and out of the reservoir by wells. It is necessary to filter the water used for injection into the reservoir for various reasons which are explained in
G.B. Patent Application Specification No. 2109261A. This Specification discloses various filtering materials which are unsatisfactory and seeks to improve filtration by means of a filter element consisting of polyacrylonitrile fibres of a single density. However, it is believed that single density filters do not utilise the filter material to its best advantage and this results in a requirement for relatively frequent backwashing and shortened filter element life.
A A backwashable filter element according to the invention comprises a filter medium formed from man made fibres wherein the fibre diameter ranges between 10 and 105 microns, and wherein the density varies between one side of the medium to the other side of the medium, the medium being so arranged that during filtration the liquid to be filtered is passed from the low density side of the medium to the high density side, the total range of densities being within the range 0.05 to 0.35 gm/cc.
In a preferred embodiment the variation in density between one side of the medium and the other is obtained by a triple layer element, the first or front layer being within the range 0.05 to 0.2 and preferably 0.1 gm/cc, whilst the second layer is of a density between 0.08 to 0.25 and preferably 0.125 gm/cc, and whilst the third or outer layer has a density range from 0.1 to 0.35 and preferably 0.26 gm/cc.
It is known that fibre diameter is an important factor in filtration as well as the density of the medium and it is believed that fibre attraction by electrostatic and van der Walls forces play a significant role in particle removal. In produced and sea water van der Waals forces of attraction are likely to be effective with the result that an increase in fibre diameter should give an increased attraction. Conversely by reducing the fibre diameter this should reduce the van der
Waals forces of attraction.
The mechanism of particle release during backwashing is also believed to be affected by van der Waals forces of attraction, hence in the preferred embodiment there is provided a coarse (open) density inner or frontal layer comprising large diameter fibre, followed by a denser central layer of intermediate diameter fibres and followed by a dense outer layer of fine fibre. This layered construction effects a compromise between van der Waals high attraction forces in the frontal (open) layer and low attraction forces in the outer dense layer. Layer depth can affect cleaning performance and particle capture, thus careful selection of fibre diameter, layer depth and layer porosity is important in controlling filter element effectiveness.
The preferred thickness of the medium in the element is within a range of 4 to 20 mm with individual layer thicknesses ranging from 1 to 10 mm. The thicknesses are given with the medium in an uncompressed state. Preferably the inner or frontal layer is about 5 mm thick, the intermediate or central layer is 3 mm thick and the outer or dense layer is about 2 mm thick.
In the preferred embodiment the frontal layer has fibre diameters of 105 and 50 microns, the central layer has a fibre diameter of about 25 microns, whilst the outer or dense layer has fibre diameters of 13 and 17.5 microns.
In the preferred embodiment the filter element is in the form of a cylinder. The medium is a non-woven material manufactured by the needle felting process both for individual layers and the composite assembly. If necessary, to support needling a reinforcing scrim may be employed on any layer.
The fibre materials may be polypropylene, polyester or polyacrylonitrile. A convenient polyacrylonitrile fibre is Dralon T (Dralon is a registered trade mark).
The filter element according to the invention is suitable for the treatment produced, sea- or land-based reservoir water containing up to 150 mg/litre of particles in the size range 1 to 500 microns. Removal efficiency of 50% of 1 to 2 micron particles and greater than 98% of 10 micron particles and larger may be achieved.
The filter element is designed for cleaning by backwashing. However, in the preferred embodiment backwashing may be carried out to a section of the element whilst maintaining filtration through the rest of the element.
The filter element of this invention can be used to remove solids and associated oil, or oil from a stream containing oily water which method comprises filtering the liquid to be filtered through a filter element according to the invention. The filter element is suitably mounted in the apparatus disclosed in our British Patent Specification No. 2046115.
The liquid to be filtered may be one containing a large proportion of oil in relation to the water, e.g. an oil well production stream, and the method is therefore suitable for oil field location. Alternatively the water content of the liquid to be filtered may be much larger, in which case the method is suitable for water cleaning.
An embodiment of the invention will now be described with reference to the following drawings and examples, the drawings showing in
Figure 1 a perspective cutaway view of a filter element according to the invention.
In Fig. 1 there is a shown a cylindrical filter element 1 suitable for fitting in to a backflush filter apparatus such as is shown in our British Patent Specification No. 2046115. The use of the element 1 is as described in that Specification, thus the liquid to be filtered is intended to be passed from the inner or frontal surface 9 of the filter and out of the outer surface 11 of the filter in the general direction of arrow 2 to arrows 4.
The filter element comprises an outer layer 3 an intermediate or middle layer 5 and a frontal or inner layer 7.
During trials the filter element of Fig. 1 was made and used according to the following examples:
EXAMPLE 1
A composite multi-layer element was produced by the needling felt process using a polypropylene and polyester medium in layers. The element had the following properties: l) Thickness : 10 mm Total - Frontal layer - 5 mm
- Middle layer - 3 mm
- - Outer layer - 2 mm
2) Density : Frontal layer - 0.1 gm/cc polyprop
ylene
Middle layer - 0.125 gm/cc polyester
Outer layer - 0.26 gm/cc polyester
3) Fibre Diameter : Frontal layer - 105 & 50 micron
Middle layer - 25 micron
Outer layer - 13 & 17.5 micron
EXAMPLE 2
The element was installed in a stainless steel support assembly and a produced water stream was filtered through the element flowing radially outward.Produced water was received via a first stage production separator and was treated by: (i) injection of 25 mg/litre of scale inhibitor, (ii) injection of demulsifier to assist prime separation of produced oil and water, (iii) primary separation of oil; water and sand/drilling fluids.
Water flowed through the filter element at a rate of 42 m3/m2/hr. Filtrate examined showed a particle range of 5 to 400 microns.
The filter element was installed to protect coalescing filter elements requiring filtration down to 5 microns to protect them against blockage by particulate and hence reduced operating life.
After 3.5 hours operation the element was cleaned by backwashing a strip 1 cm wide by flowing clean water at operating pressure radially inward through the 1 cm strip at a rate of 10 to 15 litres/linear cm/min. whilst maintaining flow in the normal direction. Backwashing continued to actuate at varying intervals between 2 and 4 hours, dependent on debris load for a period of 15 days during which time no significant build up in pressure loss across the element was evident (i.e. element returned to initial (clean) pressure loss of approximately 28 mbar after backwashes).
EXAMPLE 3
As a means of comparison other single density; single layer elements manufactured in polyester, aramid, polypropylene, PTFE faced and flurocarbon treated polyester were previously tested according to Example 2.
Without exception, all single layer/single density elements tested resulted in (i) quicker build up of pressure loss, (ii) more frequent backwashing, (iii) less pressure loss recovery after backwashing, (iv) shortened element life.
Features presented by the composite multi-layer variable density felt offer advantages over single density/single layer elements.
(A) Full element depth is utilised effectively as a result of decreasing porosity through the element thickness.
(B) Pressure loss increase is significantly slower even though filtration efficiency is maintained.
(C) Initial clean pressure loss is reduced.
(D) Backwash frequency is extended by a factor of + 4 times.
(E) Backwash cleaning effectiveness is improved.
(F) As a result of improved backwash effectiveness element life prior to replacement is extended.
(G) Less frequent backwashing reduces loss of water to drainage.
The filter of Fig. 1 is suitable for the backflush apparatus shown in our British Patent
Specification No. 204611 5, the contents of which are included by reference.
Whilst the filter medium of the element is suitable for cylindrical filters it may be used in planar filters such as is shown in our British Patent Application Specification No. 2088232, the contents of which are also included by reference.
In the production of the composite multi-layer element of Example 1 the layers were produced separately by the needle felting technique, the layers were then overlaid on each other and reneedled so that each layer was bound to the next layer. It is believed that the use of polypropylene as a frontal layer in the Example 1 whilst using polyester as a middle and outer layer material has advantages particularly with regard to particle release. The process for joining the layers is preferably by needling which is essentially a mechanical linking process, however, it is conceivable that other processes for instance by slightly heating opposed layer faces or by the application of sprayed adhesives could be used. However, needling has proved satisfactory and convenient.
The achieving of variable density from the front to the outer side is most conveniently achieved by the layered construction but it is possible though difficult to achieve variable density of a single layered medium by needling.
The provision of different diameter fibres in a particular layer is designed to increase strength whilst controlling the pore size which should be relatively small. Whilst in Example 1 the frontal layer has 105 and 50 micron fibres, these may be within the ranges 90 to 110 and 40 to 60 microns, whilst in the outer layer which has 13 and 17.5 micron fibres, these may be in the ranges 10 to 15 and 15 to 25 microns, the large diameter fibres giving strength whilst the small fibres decrease the pore size.
Claims (26)
1. A backwashable filter element comprising a filter medium formed from man made fibres wherein the fibre diameter ranges between 10 and 105 microns, and wherein the density varies between one side of the medium to the other side of the medium, the medium being so arranged that during filtration the liquid to be filtered is passed from the low density front side of the medium to the high density outer side, the total range of densities being within the range of 0.05 to 0.35 gm/cc.
2. An element as claimed in claim 1 wherein the medium is layered with different densities in each layer, there being two or more layers.
3. An element as claimed in claim 2 wherein three layers are provided.
4. An element as claimed in claim 3 wherein the first and front layer has a density range of 0.05 to 0.35 gm/cc.
5. An element as claimed in claim 3 or 4 wherein the second and middle layer has a density range of 0.08 to 0.25 gm/cc.
6. An element as claimed in any of claims 3 to 5 wherein the outer and third layer has a density range of 0.1 to 0.35 gm/cc.
7. An element as claimed in claim 3 wherein the front layer has a density of about 0.1 gm/cc, the middle layer has a density of about 0.125 gm/cc and the outer layer has a density of about 0.26 gm/cc.
8. An element as claimed in any of claims 1 to 7 wherein the medium is of a similar fibrous material.
9. An element as claimed in any of claims 1 to 7 wherein the medium is layered with dissimilar materials in at least two layers.
10. An element as claimed in any of claims 1 to 9 wherein the total medium thickness is between 4 and 20 mm.
11. An element as claimed in any of claims 1 to 10 being layered and wherein the layer thickness is between 1 and 10 mm.
12. An element as claimed in any of claims 1 to 11 wherein at least a part of the medium is formed from fibres having a different diameter.
13. An element as claimed in any of claims 1 to 12 wherein the fibres have a diameter of between 110 and 10 microns.
14. An element as claimed in any of claims 1 to 13 wherein the fibres are selected from at least two of the following ranges 110 to 90 microns, 60 to 40 microns, 25 to 15 microns and 15 to 10 microns.
15. An element as claimed in any one of claims 1 to 14 wherein the fibres are formed from polypropylene and/or polyester and/or polyacrylonitrile.
16. An element as claimed in any one of claims 1 to 15 wherein the medium is layered and the frontal layer is formed from polypropylene fibres whilst the outer layer is formed from polyester fibres.
17. An element as claimed in any one of claims 1 to 16 wherein the medium is subjected to a a needle felting process.
18. An element as claimed in any one of claims 1 to 17 wherein the medium is layered, each layer being subjected to a needle felting process.
19. An element as claimed in claim 18 wherein adjacent layers are assembled in a composite whole by a needle felting process.
20. An element as claimed in any one of claims 1 to 19 wherein the medium is formed into a cylinder.
21. A filter element substantially as described with reference to Example 1.
22. A filter element substantially as described with reference to the accompanying drawing.
23. A method of treating a liquid by passing it through the filter element of any of claims 1 to 22 from the frontal side to the outer side.
24. A method of treating a liquid according to claim 23 wherein the volumetric flow is in the range 20 to 100 m3/m2/hr.
25. A method of treating a liquid substantially as described with reference to Example II.
26. A method of producing a filter medium comprising forming a first needled felted layer and forming at least a second needle felted layer and linking the layers together by needling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08402375A GB2153246A (en) | 1984-01-30 | 1984-01-30 | Improvements in and relating to filters |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08402375A GB2153246A (en) | 1984-01-30 | 1984-01-30 | Improvements in and relating to filters |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8402375D0 GB8402375D0 (en) | 1984-02-29 |
| GB2153246A true GB2153246A (en) | 1985-08-21 |
Family
ID=10555754
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08402375A Withdrawn GB2153246A (en) | 1984-01-30 | 1984-01-30 | Improvements in and relating to filters |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2153246A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2269114A (en) * | 1992-07-31 | 1994-02-02 | Pall Corp | Recovering catalyst by filtration |
| US5628916A (en) * | 1994-08-17 | 1997-05-13 | Pall Corporation | Method for filtering edible oils |
| WO2022086457A1 (en) * | 2020-10-20 | 2022-04-28 | Antel Aritma Tesisleri Insaat Sanayi Ve Ticaret A.S. | Industrial filter for reducing turbidity and suspended solids with an effective backwash equipment |
-
1984
- 1984-01-30 GB GB08402375A patent/GB2153246A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2269114A (en) * | 1992-07-31 | 1994-02-02 | Pall Corp | Recovering catalyst by filtration |
| GB2269114B (en) * | 1992-07-31 | 1995-10-18 | Pall Corp | Method of removing catalyst |
| US5690836A (en) * | 1992-07-31 | 1997-11-25 | Pall Corporation | Method of removing catalyst |
| US5628916A (en) * | 1994-08-17 | 1997-05-13 | Pall Corporation | Method for filtering edible oils |
| WO2022086457A1 (en) * | 2020-10-20 | 2022-04-28 | Antel Aritma Tesisleri Insaat Sanayi Ve Ticaret A.S. | Industrial filter for reducing turbidity and suspended solids with an effective backwash equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8402375D0 (en) | 1984-02-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |