DE20321162U1 - Heavy duty filtration material removing dust from industrial gases, includes base felt, and cover felt with thinner fibers consolidated by fluid-jet needling - Google Patents

Abstract

To form the covering layer, a three dimensional outer felt layer (4) is anchored onto the base felt (2). This has thinner fibers than the base felt, and is a felt consolidated by fluid-jet needling. Further layers on the support layer (1) are fluid-jetted felt. The layer on the support layer is fluid-jetted through its entire thickness. All fibers of the cover felt are thinner than staple fibers of the base felt. The cover felt is entirely made of the same fibers. The support layer has material at least equivalent in use, to the staple fibers of the base felt. The support layer is accommodated between two felt base layers (2, 3), of which only one carries a cover felt. The cover felt is based on, or at least partially comprises, finer fibers of diameter 10 mu m at most, or a fiber fineness of at most 1.0 dtex. The cover layer basis fibers are at least partially: splitting fibers and/or melt-blown material. The cover felt is based on very fine fibers and/or splitting fibers with a length preferably of 30-60 mm. Its thickness is 0.1-1.0 mm and its weight is preferably 100-200 g/m2>. The total thickness is 1-3 mm. The needling fluid is water. An independent claim is included for the corresponding method of manufacture.

Description

The Invention relates according to a first idea of the invention a regenerable filter material for powerful Filter, in particular for the dedusting of industrial waste gases, with a Support material layer, on the at least one side a pad is applied, the one inner, consisting of staple fibers Basisfilzlage and one with their supporting material facing away Side, a comparatively low permeability having covering layer and is according to another inventive concept to a method of making such a filter material one.

In a known filter material of this type, the cover layer is formed as a membrane made of a PTFE film, which is laminated to the underlying there Stützmaterial- or felt layer. This prior art is in 4 shown schematically. The membrane provided here represents a very thin, practically only two-dimensional element, which is consequently very sensitive to mechanical stress and surface injuries. Another, very particular disadvantage, however, is the fact that the membrane is only selectively fixed on the support material layer and can be released after a certain time from the support material layer under mechanical stress. This disadvantage, known as delamination, is further intensified by the cleaning operations required for a regenerable filter material, in which pressure is applied from the rear side. In terms of process engineering, there is the disadvantage that the small pore size of the membrane required for the separation of ultrafine particles produces a high flow resistance, which manifests itself in operation at a high pressure drop.

There are already known filter materials with cover layer, which are produced in total by mechanical needling. This prior art is in 5 indicated schematically. In this case, the outer cover layer consists of fibers which are finer than the inner base felt layer fastened on a backing material layer. Experience has shown, however, that there is a risk here that the finer fibers are damaged during needling by the needles. This danger is greater, the finer the fibers used are. In order to keep damage to an acceptable level, only a small amount of compaction can be provided when using fine fibers. Apart from that, the fibers used here as finer fibers are in many cases not fine enough. As a result of needling, no homogeneous felt structure can be achieved. Another very particular disadvantage is also to be seen in that a comparatively large proportion of the thin fibers of the outer layer is transported by the needling into the underlying material. The effectiveness of the outer layer is reduced due to the formation of Nadeleinstichlöchern and reducing the amount of fiber in the outer layer.

It has also been proposed a filter material ( DE 44 10 110 C2 ), in which a support material is connected front and / or rear with a nonwoven fabric which is solidified by water jets. However, this known arrangement is not a layer material with a base felt layer and a cover layer received on it. However, this construction would result in the use of relatively fine fibers to a high susceptibility to mechanical stress, high buckling resistance and insufficient adhesion to the support material, quite apart from the high material costs. In addition, results in this known arrangement due to the locally on the substrate or the gaps between very different compression of the nonwoven layer an extremely non-uniform pore structure, which has inhomogeneous flow and thus reduced separation efficiency result.

Of these, It is therefore the object of the present invention, under Avoiding the disadvantages of the known arrangements a filter material mentioned above Kind with simple and inexpensive To improve funds so that not only a high deposition performance but also a comparatively high mechanical strength and service life be achieved. Another object of the invention is to a simple and inexpensive Process for the preparation of the filter material according to the invention available put.

The on the improvement of the filter material directed task solved according to the invention that to form the topcoat a three-dimensional, on the base felt layer anchored, outer cover felt layer is provided, which is at least partially opposite to the Staple fibers of the base felt layer thinner Fibers, and that at least the cover felt layer as fluid beam strengthened Felt is formed.

The object directed to the specification of a method for producing the filter material according to the invention is achieved according to the invention by applying on at least one side a support material layer comprising an inner base felt layer consisting of staple fibers and a three-dimensional outer cover felt layer anchored on its side facing away from the support material. which is formed by compacting a raw or at most pre-needled web which is at at least partially consists of compared to the staple fibers of the base felt layer thinner fibers and is compressed by high-pressure blasting of a fluid.

These activities advantageously provide a layer material with one above the other arranged felt layers, wherein in consequence of the different fiber thicknesses a from the outside inside increasing pore size available is. This has an advantageous effect on the prevention of constipation of the filter material and facilitates the cleaning, which is a ensures high operational safety. Another advantage of the measures according to the invention can be seen in that one opposite a diaphragm is provided with a comparatively thick covering felt layer, the high mechanical strength and high insensitivity guaranteed against mechanical stresses on the surface. Through the base felt layer is also an equalization of density and reaches the pores of the cover felt layer. In addition, the distance causes to the support material situation one even flow, what in an elevated Separation performance especially for fine dust results. The high-pressure jet compression of the cover felt layer is in an advantageous manner suitable, the cover felt layer simultaneously on simple and reliable Way on the underlying base felt layer by positive connection anchor the fibers of the two layers. This can be a reliable Cleaning done without fear of so-called delamination. By The high-pressure jet compression is also in an advantageous manner ensured that the individual fibers of the cover felt layer to a great extent spared and practically not mechanically damaged, so that even finer Fibers than previously used and yet a high and homogeneous compression can be achieved.

in the Contrary to mechanical needling, high-pressure blasting a compression of the felt layers by turbulence of the fibers and not by fiber transport and reorientation in the direction of the needle penetration reached. It also ensures that due to the smaller fiber diameter and the so huge Abscheideaktiv surface a high separation performance for ultrafine particles exhibiting Deckfilzlage held as far as possible on the surface will and only to a very small extent with the underlying Base felt layer is mixed, so that the formation of the cover felt layer used material as far as possible to achieve the desired high separation efficiency for Fine particles comes into play.

In procedural terms, there is the advantage that the three-dimensional structure of the cover felt layer a large Abscheideaktive fiber surface that offers a surface-oriented and high separation efficiency for Ensures finest particles, This happens at comparatively low flow resistance and pressure loss.

advantageous Embodiments and appropriate training the parent Measures are in the subclaims specified. So everyone can be useful Fibers of the cover felt layer thinner as the staple fibers used to form the base felt layer. This results in a particularly high separation performance for ultrafine particles.

A further advantageous measure may be that the recorded on the support material situation Edition over their entire thickness as compressed by high pressure jet fluid beam Felt is formed. this makes possible a particularly rational production, since here the cover felt layer and at the same time the base felt layer is compressed or at least densified can be. In addition, can thereby a desired one Increase in pore size from the outside to be reached inside.

The Thickness of the fibers underlying the cover felt is expedient at most 10 μm or 1.0 dtex. This will be one with the known membrane arrangements quite comparable deposition effect achieved.

Find appropriate to form the fluid jet bonded felt, fluid jets preferably in the form of water jets at a pressure of at least 20 MPa, preferably 30 to 35 MPa, use. This high pressure associated with the comparatively large mass of liquid guaranteed the required good turbulence and intensive connection of the Documents. Furthermore This also ensures that when using Splitting fibers these are splitted particularly reliable.

Further advantageous embodiments and expedient developments of the higher-level measures are specified in the remaining subclaims and from the the following example description with reference to the drawing closer.

In the drawings described below show:

1 a cross section through a filter material according to the invention,

2 a schematic representation of an apparatus for producing the filter material according to the invention,

3 an alternative to 2 .

4 the known filter material with membrane in 1 corresponding representation and

5 the known, in total condensed by needling filter material in 1 corresponding representation.

The main field of application of the invention is dedusting of industrial waste gases, wherein the deposition effect should be at least as efficient as with membranes provided with filters, that is, it should be at a total separation efficiency with an emission value of less than 1 mg / Nm ³ especially very fine particles with a particle size less than 5 μ / m be deposited in a high mass.

That the 1 underlying filter material contains a trained as a fabric or scrim or the like support material layer 1 which is provided with a support or, as in the example shown, is embedded between two supports. In the example shown, the support material layer 1 between two opposite base felt layers 2 . 3 embedded. The upstream base felt layer 2 is on its outside, that is, on its from the backing material layer 1 opposite side, with a cover layer forming, three-dimensional cover felt layer 4 connected. In the example shown, as already mentioned, two base felt layers 2 . 3 provided, whereby the interposed Stützmateriallage 1 protected on both sides against external forces. In many cases, however, one comes only with a base felt layer 2 out, on the cover felt layer 4 is included.

Every base felt layer 2 . 3 consists of staple fibers, which may have a diameter of 15 μ / m or a fiber fineness of 1.7 dtex upwards and a length of 20 to 80 mm. The support material situation 1 may be made of multifilament yarns, and / or Stapelfasergarnen and / or monofilaments, etc., where appropriate, the same or a similar or in use at least equivalent material as for the staple fibers of Basisfilzlagen 2 respectively. 3 Use finds.

The cover felt layer 4 consists at least partially, preferably entirely, of substantially finer fibers than the base felt layers 2 respectively. 3 , Thicker fibers may be mixed to a lesser extent. Finer fibers with a diameter of the order of at most 10 μ / m or a fineness of at most 1.0 dtex and / or so-called splitting fibers with a thickness of 1 to 5 μ / m or a fineness of at most 0 can be used as finer fibers , 3 dtex in the open state and / or melt blown nonwovens with a fiber diameter of 1 to 5 μ / m find use. The thickness of the fibers of the cover felt layer is accordingly not more than 10 μ / m or 1.0 dtex. The melt blown fibers are endless fibers which are already produced in non-woven form. The ultrafine fibers and / or splitting fibers used may have the same length as the staple fibers, ie 20 to 80 mm. Preferably, 30 to 60 mm are provided.

To form the cover felt layer 4 For example, it is possible to use a mixture formed of fibers of the type mentioned above, wherein the mixing ratio can be adapted to the conditions of the individual case. In general, however, it is preferable to simplify the storage when forming the cover felt layer 4 only fibers of a kind find use.

At least the cover felt layer 4 is formed as a fluid jet-strengthened felt, that is, felt compressed by high-pressure blasting of a fluid. The fluid should have a comparatively high mass. For this purpose, therefore, preferably a liquid, preferably water, use. The said high-pressure jets not only provide for a compression of the cover felt layer 4 , but at the same time also an anchoring of the cover felt layer 4 with underlying base felt layer underneath 2 effect at comparatively low fiber exchange. The cover felt layer 4 and the base felt layer underneath 2 are connected by mutual entanglement and turbulence. An adhesive bond, etc. is therefore advantageously not required.

The thickness of the cover felt layer 4 can be 0.1 to 1 mm, depending on the application. The basis weight of the cover felt layer 4 is in the range of 20 to 250 g / m ³ , preferably 100 to 200 g / m ² . The total thickness of the filter material according to the invention may be about 1 to 3 mm, wherein the difference between the total thickness and the thickness of the cover felt layer 4 on the base felt layer or layers 2 respectively. 3 and the support material situation 1 omitted. If so, as in the example shown, two Basisfilzlagen 2 . 3 are provided, this difference is distributed on the support material layer and the two Basisfilzlagen 2 . 3 , If only one base felt layer is provided, its thickness may correspond to the common thickness of the two base felt layers of the illustrated embodiment.

In the production of the filter material according to the invention can according to the in 2 be suggested example. In this example, here's a role 5 developable support material layer 1 one or both sides, here on both sides, one of staple fibers mentioned above type, here also developable from a roll nonwoven layer 6 respectively. 7 hung up. Usually, the nonwoven layers which can be developed onto a roll and which can be developed therefrom become 6 . 7 In order to achieve such Hantierbarkeit, at least slightly needled or vorver seals. The on the support material situation 1 applied nonwoven layer or layers 6 . 7 be further pre-compressed in the example shown by needling and with the support material layer 1 connected, such as by a needling device 8th is indicated. Subsequently, on one side, here above, another, also in the example shown, unwound from a roll outer fleece layer 9 placed, which consists at least partially, preferably entirely of fibers which are thinner, ie finer than the staple fibers of the nonwoven layers 6 respectively. 7 are.

The fleece layer 9 may also be slightly needled in order to achieve the necessary handling. This applies to nonwovens consisting of fine fibers or splitting fibers. When using a melt-blown nonwoven such needling can be omitted, since the required handling is already given here in the original state. Such a fleece could also online with the support material situation 1 and the inner nonwoven layers 6 . 7 generated package and stored on this. It is also conceivable, the nonwoven layer 9 attach to the underlying layer by light needling. In any case, the needling is so low that thereby no damage to the thin fibers of the nonwoven layer 9 is to be feared.

The nonwoven package thus formed is then one by high pressure blasting 11 accomplished compacting process. For this purpose, the fleece package, as in the embodiment according to 2 without intermediate storage directly at least one arranged in line high pressure jet device 10 be supplied. However, it would also be conceivable to wind up the fleece package prepared in the manner described above onto a roll and, in this form, to a high-pressure jet device located at another location 10 bring to. In the formation of the mentioned role, it proves to be expedient if the outer nonwoven layer 9 , as mentioned above, adhered to the underlying layer or when all layers are slightly needled together and connected.

Of the 3 is based on the above-mentioned alternative. The 3 shows a role 12 from which a fleece package 13 deducted above type, the at least one high-pressure jet device 10 for treatment with high pressure jets 11 is supplied.

The high pressure jets 11 the high-pressure jet device 10 cause a compression of the outer nonwoven layer 9 to the cover felt layer 4 and a final densification of the nonwoven layers 6 . 7 to the base felt layers 2 . 3 , The fleece layer 9 is compressed to at least 20%, preferably at least 10% of the initial volume. In the case of using splitting fibers, the high pressure jets also cause their splitting, giving them their extreme fineness and large surface area. Prior to high pressure jet application, the splitting fibers are essentially uninterrupted, favoring nonwoven formation in a conventional manner in the form of carding and needles.

Simultaneously with the compression, anchoring of the cover felt layer takes place 4 on the base felt layer underneath 2 by mutual entanglement. The loading of the fleece package with the high-pressure jets 11 leads advantageously to no appreciable mixing of the fibers of the adjacent layers. Rather, it remains at a largely segregated state, that is, the fibers of the outer nonwoven layer 9 stay with the formation of the cover felt layer 4 as far as possible on the surface and only in the area of the boundary layer to the adjacent base felt layer 2 hooked or swirled to form a sufficient anchorage with the local fibers.

The diameter of the formation of the rays 11 provided nozzle holes is suitably 0.10 to 0.14 mm. The pressure with which the rays 11 is ejected, is at least 20 MPa, preferably 30 to 35 MPa. This pressure is sufficient, even under the cover felt layer 4 underlying base felt layer 2 bring to the desired final degree of compaction.

Appropriately, the fleece package, as from the 2 and 3 can be seen from above and from below by high pressure jets 11 so that also a reliable final compaction of the lower nonwoven layer 7 to the lower base felt layer 3 as well as a good adhesion of this situation takes place. The high-pressure jet device therefore contains upper and lower nozzle arrangements. These are expediently offset from one another in the transport direction of the fleece package in such a way that initially the upper layer side is acted on, here the upper side, and then the opposite side, here the lower side. The intensity of the rays entering the fleece package 11 decreases with the penetration depth, whereby a decreasing from outside to inside compression and thus increasing pore size is effected, which facilitates the cleaning especially in filters with only one-sided base felt layer and one-sided compression. The to the formation of high pressure jets 11 Use of pressure can be different up and down. It is expedient to provide a greater pressure on the cover layer side than on the opposite side.

As fluid is suitably a liquid, preferably water use. This can be cold water. Of course, a hot fluid could be used instead of a cold fluid. If fluid as a liquid When used, the filter material brought to final density by the latter must be dehumidified and dried after compaction. In 2 are to achieve a dehumidification nip rolls 14 intended. In 3 is a suction device acted upon by suction 15 provided over which the filter material is passed away. Drying can be done by air drying. Appropriately, however, this is a drying oven in 3 at 16 indicated type use.

If equipment of the filter material is desired, a suitable finishing agent can be added to the fluid or it can be used as a fluid. Where this is not possible due to the nature of the finishing agent, the finishing agent may be used as in 3 is indicated, after the compression of the filter material by means of the high pressure jets 11 be applied to the filter material. In the example according to 3 find this spray nozzles 17 Use. When using a liquid finishing agent, the loading of the filter material hereby takes place, as in the example shown 3 expedient in the area between two dehumidifiers, here in the form of suction 15 , The finished, dried material can, like 3 further shows, wound onto a roll and so be transported away.

Claims (14)

Filter material for powerful filters, in particular for the dedusting of industrial waste gases, with a support material layer ( 1 ), on which at least on one side a support is applied, which has an inner base felt layer consisting of staple fibers ( 2 ) and a covering layer which has a comparatively low permeability and which is connected to its supporting material side, characterized in that, for forming the covering layer, a covering layer is provided on the base felt layer ( 2 ) anchored outer cover felt layer ( 4 ) is provided, which at least partially from compared to the staple fibers of the base felt layer ( 2 ) thinner fibers, and that at least the cover felt layer ( 4 ) is formed as a fluid-jet-reinforced felt. Filter material according to claim 1, characterized in that the support received on the support material layer pad in a more than the cover felt layer ( 4 ) comprehensive area is formed as a fluid jet reinforced felt. Filter material according to claim 2, characterized in that on the support material layer ( 1 ) received support is formed over its entire thickness as a fluid beam-reinforced felt. Filter material according to one of the preceding claims, characterized in that all the fibers of the cover felt layer ( 4 ) thinner than the staple fibers of the base felt layer ( 2 ) are. Filter material according to one of the preceding claims, characterized in that the covering felt layer ( 4 ) consists entirely of the same fibers. Filter material according to one of the preceding claims, characterized in that the support material layer ( 1 ) of a material at least equivalent in use to the staple fibers of the base felt layer (US Pat. 2 ) consists. Filter material according to one of the preceding claims, characterized in that the support material layer ( 1 ) between two base felt layers ( 2 . 3 ), of which only one is a cover felt layer ( 4 ) wearing. Filter material according to one of the preceding claims, characterized in that the covering felt layer ( 4 ) underlying finer fibers have a diameter of at most 10 microns or a fiber fineness of at most 1.0 dtex. Filter material according to claim 8, characterized in that the cover felt layer ( 4 ) underlying fibers are at least partially splitting fibers. Filter material according to claim 8 or 9, characterized in that the cover felt layer ( 4 ) underlying fibers are at least partially melt-blown material. Filter material according to claim 8 or 11, characterized in that the cover felt layer ( 4 ) underneath ultrafine fibers and / or splitting fibers have a length of 20 to 80 mm, preferably 30 to 60 mm. Filter material according to one of the preceding claims, characterized in that the thickness of the cover felt layer ( 4 ) Is 0.1 to 1.0 mm. Filter material according to one of the preceding claims, characterized in that the basis weight of the covering felt layer ( 4 ) in the range of 20 to 250 g / m ² , preferably in the range of 100 to 200 g / m ² . Filter material according to one of the preceding claims, characterized characterized in that the total thickness is 1 to 3 mm.