DE102008005794A1 - Multi-purpose filter for e.g. food, pharmaceutical filtration has hard woven structure retaining small particles - Google Patents

Abstract

A fleece (2) fibre filter medium (1) has a woven structure (3) with pores. The woven structure retains ultra-small particles smaller than 100 microns that are not held back by the pores. Further claimed is a filter assembly with a commensurate filter insert. The solid weave structure has pores with a nominal size in the range 40 to 1 microns and consists of two or more layers with one woven layer and a second layer of fleece fibres.

Description

State of the art

contraption for filtering substances such as liquids or gases known in various technical fields. The to be filtered Flow through substances for example, a filter medium or a filter medium with openings, wherein substance components are retained in or on the filter medium becomes. A filter medium may be, for example, a sieve, a tissue, a porous one Include plate or a non-woven fabric.

nonwovens are characterized in the filter insert by a relatively large capacity for filtering Substances, in particular micro particles. The non-woven fabric has in particular a multiple layering of fiber pieces, wherein the structure For example, showing hundreds of layers. After the connection the fibers, for example, by a sintering process, the obtained Flies arrangement or a "web" example with Rollers are pressed to obtain a desired pore geometry. The pores of a nonwoven fabric are in proportion to the desired filter fineness relatively large. The filtration effect of the nonwoven fabric is mainly due to an accumulation of the particles to be filtered on the fibers. there van der Waals forces in particular play a role. Because of the comparatively huge Pores of the nonwoven fabric is a relatively low pressure drop when flowing through liquids or to observe gases through the non-woven fabric.

Purpose and advantages of the invention

task It is the object of the present invention to provide a filter medium comprising a nonwoven fabric has, in terms of filter performance economically advantageous to improve.

These Task is by the claims 1 and 13 solved. In the dependent claims Advantageous developments of the invention are shown.

The The invention is based on a filter medium with permeable filter element sections which is flown to filter a substance of this, with a filtration during the process through which Nonwoven fabric and a fabric structure. The core of the invention lies in that the fabric structure is designed to be of the Nonwoven non-retained Micro particles which have a particle size of less than about 100 μm, filter out. The nominal pore size or nominal filter fineness the fabric structure is corresponding to approx. 100 μm. The pore size distribution or the pore sizes of the Nonwoven fabrics are in particular significantly larger than those of the fabric structure and can be chosen differently depending on the filter task.

Especially can realized with the proposed filter medium better filter performance be, opposite Previous arrangements using a nonwoven fabric and a Tissue structure in a filter medium. Is particularly advantageous the defined or reproducible structure of the filter medium in With regard to the pore size of the fabric structure. With the novel filter medium, the previously not sure controllable Disadvantages of filtration tasks in terms of filter performance the fiber fleece or the fabric structure can be eliminated. For example can the fibers present in the fiber fleece, if necessary by mechanical stress or break pulsation or dissolve and become mobile, so that the particles have no retention structure get into the filtrate. Such particles could according to the invention the fabric structure with the comparatively small pore size or retained the low filtration fineness become.

So far could not be economically justified when using fiber webs prevents pieces in particular the fibers of the non-woven fabric detach and exit from the filter or get into the filtrate, which is undesirable. So far, the use of fiber webs for a number of applications impossible.

at the recent use of tissue structures in filter media it is disadvantageous that these lead to a comparatively strong increase in pressure lead during filtration and a relatively low absorption capacity for the substances to be filtered exhibit. The likewise existing advantages of the tissue structures, z. B. the defined filter fineness, the regular pore geometry or the mechanical strength, could not do so for all interesting applications be used in the filter area.

With the proposed filter medium, the disadvantages of the nonwoven fabric be eliminated by the combination with the tissue structure and vice versa can the respective disadvantages of the fabric structure by the Turn off nonwoven fabric, taking advantage of nonwoven fabric and fabric structure fully preserved. Overall, it can be a compact filter medium for one Series of sophisticated filtering tasks, e.g. B. for solid, liquid or gas streams or for from this mixed filter streams with big Material flows of to be filtered substance. Such filters are for example in the chemical or pharmaceutical industry or in machines or Plants used, for. For example High-performance units such as internal combustion engines in the air and Astronautics.

Especially it is advantageous that the tissue structure pores with a nominal Pore size of below approx. 100 μm having. With the proposed corresponding nominal filter fineness or the relatively small pores or flow openings The tissue structure can be a safe restraint or filtration of corresponding substance proportions are achieved. A leakage of small particles through the filter medium, especially fibers or fiber fragments from the nonwoven fabric is prevented by the fabric structure. The Tissue structure can in particular by the type or production of the fabric so that a desired nominal pore size in particular from below about 100 microns exact and consistent can be specified. In particular, you can such fabric structures in precision wire weaving be made with modern weaving methods.

The nominal pore size of one Filter medium or the nominal filter fineness is obtained by application a filter in practice. For example, it is defined as that 98 percent of the substance to be filtered or z. B. one Suspended particles greater than or equal to the nominal filter fineness are withheld become. This separation efficiency is in addition to the filter medium itself, too influenced by the ambient conditions.

Prefers For example, the fabric structure has pores having a nominal pore size of below about 40 μm to approx. 1 μm on. This allows substances or particles with the smallest particle dimensions or with average particle diameters in the stated size range safely retained in the filter medium become.

The Fabric structure also gives the filter medium advantageously increased mechanical stability, eg. B. if the fabric structure is outside on the fibrous web and / or if the fabric structure is inside the filter medium is positioned.

Basically you can with the proposed nominal pore size particles are filtered have different particle shapes or particle materials. Also a restraint of oblong thin Particles with the appropriate tissue structure is possible, for Example broken or unbonded fibers of the nonwoven fabric, the elongated and thin could be, For example, have a thickness of about 5 to 10 microns.

It is of particular advantage that the tissue structure as Tressengeweben is designed, in particular as Köpertressengewebe. A thread tissue Like any other fabric, it consists of weft threads and transversely aligned ones Warps. One Tissue tissue is characterized by its very small pore size or low filtration grade. A weaving fabric becomes a smooth bond (1/1). It can the warp threads interwoven with larger distances be as the weft threads. advantageously, is the surface closed the tissue of tissue, so that the filtration in the point of bonding of warp and weft threads can take place. Across from other tissues can significantly higher yield mechanical strength. In addition, tresses tissue are characterized through a very regular tissue structure with the smallest pores.

Especially Advantageously used is the so-called Köpertressengewebe, which is a twill weave (2/2) and by interweaving warp yarns with a larger number of weft threads is realized. With a Köpertressengewebe, for example relatively dense z. B. light-tight fabric can be generated. With a Proposed Köpertressengewebes may be a nominal pore size of the body scler tissue of approx. 1 μm up to about 50 microns, z. B. to about 100 microns will be realized. Due to the comparatively high material density in Twill Dutch Weave arises in comparison to the pores or openings provided with it a very robust fabric. This can be a filter medium, which a Köpertressengewebe covers, in various technical fields use. An exemplary Einsetzgebiet is the exhaust gas purification.

in principle are alternative to the Tissue tissues and other tissue structures or bond types conceivable to the tissue structure with pores of the desired form relatively small nominal pore size.

It it is further proposed that an at least two-layer construction formed with a layer of the fabric structure and a layer of the nonwoven fabric is. This comes close to a minimum configuration of the filter medium, which already has a reliable and high filter performance can be realized.

besonderst It is advantageous that in the flow direction according to one of the Nonwoven fabric formed layer formed from the fabric structure layer follows. So lets realize a combination filter medium, the filter leakage of micro particles from the filter medium especially safely avoids.

In particular, a comparatively large surface area for an attachment of the substance to be filtered can be provided with the nonwoven fabric of a multiplicity of fiber layers. With a corresponding thickness of the nonwoven fabric layer, a depth filter can be realized, which also shows properties of a surface filter due to the fabric structure, so z. B. a combined surface depth filter ready is adjustable.

In an advantageous embodiment of the subject invention, a multilayer structure is realized, with two layers of tissue structure present between where a layer of the non-woven fabric is arranged. In particular a filter medium can be provided, which in opposite Filterdurchströmrichtungen or filter directions can be used advantageously. In addition, can the filter medium is precisely matched to a preferred direction of flow become.

Advantageous can in the direction of flow follow a nonwoven fabric after a first fabric structure and then a second tissue structure, wherein the first tissue structure a smaller Filter fineness than the second fabric structure. Basically instead of a layer with the nonwoven fabric and a multi-layer nonwoven fabric can be used, wherein the individual layers of the fiber webs formed differently could be, z. B. may have different pore dimensions.

alternative or in combination with a Tressen- or Köpertressengewebe can, for. B. a microperforated perforated plate with one of the proposed or Köpertressengewebe comparable nominal pore size or Filter fineness are provided. The microperforated perforated plate can z. B. in the flow direction through the filter medium in front of the nonwoven fabric and / or behind the nonwoven fabric to be ordered. It is conceivable in a three-layer filter medium structure with a fibrous web present in the middle z. B. an arrangement of the microperforated perforated plate on one side and the arrangement a weave fabric on the other side of the three-layer filter medium.

advantageously, includes the fabric structure weft threads and warp threads, wherein the warp threads one to the diameter of the weft threads larger diameter exhibit. It can the warp threads z. B. be about 20 to 40% larger in diameter than the weft threads, what especially with regard to the production and stability of the fabric structure is advantageous.

Further It is advantageous that the fabric structure of metallic fibers is formed, in particular made of stainless steel. With a metallic one Material in particular from a high-quality alloy can that Fabric particularly resistant against chemical, thermal and / or mechanical influences.

alternative to the metallic structure forming the fabric structure are also Fibers made of other materials usable. For example, glass fibers, Mineral fibers or plastic fibers or structures, such Include fiber. Alternatively you can Woven in a fabric structure different materials be, z. B. the warp threads made of a different material than the weft threads.

The Fabric structure is preferably made of monofilament fibers, wherein The use of multifilament fibers is also conceivable.

Next Metal fibers are alternatively also multifilament glass, mineral and / or plastic materials for the fibers can be used.

Further it is preferred that a sintered bond between the fabric structure and the nonwoven fabric is formed. This is a particularly effective one Realizable and stable connection for fabric and nonwoven structures. in principle can Other types of connections may be advantageous, for example press, welding, Adhesive or solder joints.

besonderst It is advantageous that the nonwoven fabric comprises metallic fibers. In particular, a metal fiber fleece with comparatively short and single very thin wire pieces prefers. The pieces of wire can For example, have a thickness of about 10 to less than 8 microns. Such a metal fiber fleece can by joining the short very thin pieces of wire be formed. The respective bonds are generally comparatively weak or loose.

The Invention also relates a device for filtering a substance with a filter medium, that according to the above Said is formed.

In order to can be in a device for filtering, for example a Filter module or a filter apparatus, the advantages mentioned above achieve.

figure description

The Invention is based on two embodiments, which are strong are shown schematically, closer explained. In detail shows:

1 a section of a filter medium according to the invention in sectional view and

2 a section of a further filter medium according to the invention in a sectional view.

1 shows in section an inventive filter medium 1 strongly schematized. The filter medium 1 is flowed in the direction of flow according to arrow S1 by a substance to be filtered (not shown), wherein on the opposite downstream side of the filter medium 1 that from the filter medium 1 according to arrow S2 emerging filtrate (not shown) is obtained. The substance to be filtered first passes through a first layer of the filter medium 1 , here a fiber fleece 2 , with strichisch indicated fibers 2a in different orientation. To the fiber fleece 2 closes a second layer of the filter medium 1 on, here a trained as Köpertressengewebe tissue 3 with parallel warp threads 3a and transversely aligned multiply bent weft threads 3b , The diameter of the cross-section round warp threads 3a is about 30% larger than the diameter of the weft threads 3b ,

The two layers of the fiber fleece 2 and the fabric 3 are connected by sintering. The thickness of the fabric 3 typically z. B. in the range of about 50 microns to about 250 microns and the thickness of the nonwoven fabric 2 z. B. in the range of about 0.5 mm to about 1.5 mm.

The fiber fleece 2 can in particular be made of many individual very thin and short pieces of wire, which comparatively many small particles in particular can attach in the nonwoven fabric. Particles which the fiber fleece 2 penetrate through or on the tissue 3 retained. This allows the tissue 3 act as a protective filter against leakage of minute particles. By the combination shown in accordance with 1 with the fiber fleece 2 , which in the flow direction or flow direction of the tissue 3 followed, can also be peeling fibers 2a or parts thereof, safely in the tissue 3 be withheld.

2 shows a moreover advantageous embodiment of the filter medium according to the invention 4 very schematic in cross section. The filter medium 4 comprises in the direction of flow according to the arrow S1, a first tissue 5 , then a fiber fleece 6 to which a second tissue 7 followed. The tissue 5 and the tissue 6 are designed as Köpertressengewebe with the same type of binding, especially from warp and weft wires made of stainless steel. The tissue 7 has larger wire diameter than the fabric 5 , This allows the tissues 5 and 7 especially in their filtration effect differ from each other.

The fiber fleece 6 is especially as a metal fiber fleece with metallic fibers 6a constructed of stainless steel. On both sides of the fiber fleece 6 are the tissues 5 respectively. 6 arranged, for example, on the nonwoven fabric 6 each are sintered. With the arrangement according to 2 can be a deposition according to the direction of flow S1 of particles on the tissue 5 take place, with more in particular fine particles within the fiber fleece 6 can be deposited. Outflow side occurs according to arrow S2 from the filter medium 4 Filtrate (not shown), wherein the filtrate is free of small particles, since these in the tissue 7 be retained, for example, thin from the nonwoven fabric 6 detached fibers 6a or fragments thereof.

Typical pore sizes for the tissues 3 respectively. 5 and 7 are in the range of 1 micron to about 100 microns.

Diameter of the threads of the tissues 3 . 5 respectively. 7 are in the range of about 20 microns to about 100 microns for the warp threads or in the range of about 15 microns to about 70 microns in the weft wires.

Basically It is also conceivable that instead of a non-woven fabric, for example a fabric is formed with multifilament fibers. With this arrangement If necessary, the nonwoven fabric can be cheaper be replaced.

1

filter media

2

non-woven fabric

2a

fiber

3

tissue

3a

warp

3b

weft

4

filter media

5

tissue

6

non-woven fabric

6a

fiber

7

tissue

Claims (13)

Filter medium ( 1 . 4 ) with permeable filter element sections, which is flown for filtering a substance of this, with a through-flow during the filtering process fiber fleece ( 2 . 6 ) and a tissue structure ( 3 . 5 . 7 ), Characterized in that the fabric structure ( 3 . 5 . 7 ) is formed so as to be separated from the fibrous web ( 2 . 6 ) filter off non-retained minute particles having a particle size of less than about 100 microns. Filter medium according to claim 1, characterized in that the fabric structure ( 3 . 5 . 7 ) Has pores with a nominal pore size of less than about 100 microns. Filter medium according to claim 1 or 2, characterized in that the fabric structure ( 3 . 5 . 7 ) Has pores with a nominal pore size of less than about 40 microns to about 1 micron. Filter medium according to one of the preceding claims, characterized in that the fabric structure ( 3 . 5 . 7 ) is designed as a traction tissue, in particular as Köpertressengewebe. Filter medium according to one of the preceding claims, characterized in that an at least two-layer structure with a layer of the fabric structure ( 3 ) and a layer of the non-woven fabric ( 2 ) is trained. Filter medium according to one of the preceding claims, characterized in that in the flow direction according to one of the fiber fleece ( 2 . 6 ) formed one of the tissue structure ( 3 . 7 ) situation follows. Filter medium according to one of the preceding claims, characterized in that a multi-layer structure is realized, wherein two layers of the fabric structure ( 5 . 7 ) are present, between which a layer of the non-woven fabric ( 6 ) is arranged. Filter medium according to one of the preceding claims, characterized in that the fabric structure ( 3 . 5 . 7 ) Warp threads ( 3a ) and weft threads ( 3b ), the warp threads ( 3a ) one to the diameter of the weft threads ( 3b ) have larger diameter. Filter medium according to one of the preceding claims, characterized in that the fabric structure ( 3 . 5 . 7 ) is formed of metallic fibers, in particular of stainless steel. Filter medium according to one of the preceding claims, characterized characterized in that the fabric structure of non-metallic fibers is formed, for. As glass fibers, mineral fibers, plastic fibers. Filter medium according to one of the preceding claims, characterized in that a sintered connection between the fabric structure ( 3 . 5 . 7 ) and the non-woven fabric ( 2 . 6 ) is trained. Filter medium according to one of the preceding claims, characterized in that the fiber fleece ( 2 . 6 ) comprises metallic fibers. Device for filtering a substance with a Filter medium according to one of the preceding claims.