DE102015002001B4 - Filter element and method of filtration - Google Patents

Abstract

Filter element (1) with a mesh structure (5) with pores (7), characterized in that the pore size can be changed reversibly under the action of an external pressure, means for selective pretensioning of the mesh structure in at least one direction being provided in order to adapt the filter effect and / or to stretch the mesh structure (5) for backwashing.

Description

The present invention relates to a filter element according to the preamble of claim 1 and a method for filtration according to the preamble of claim 8.

Various means and methods are used in the filtration, separation or purification of substances, especially liquids and gases. Most of the time, the substance runs through a filter, which filter can consist of different materials. Filters made of paper, textile fabric, ceramic and metal are known, for example, whereby not only one-piece filters but also filters in the form of beds and the like are known.

When the fabric passes through the filter, it is resisted, which creates a pressure drop. This filter resistance becomes greater the longer the filter is in operation, because either through the formation of a filter cake or the clogging of its pores, it can no longer pass as many substances as in the original state.

To reactivate the filter, the filter cake must therefore be removed, the pores cleaned and / or the filter completely replaced. A special method for reactivation is what is known as backwashing, in which the material transport is reversed at periodically recurring intervals in order to remove contamination.

The CH 647 956 A5 discloses a method for producing a porous filter layer, wherein a filter pack is built up from a plurality of filter disks made from a wire mesh and then pressed together under high pressure. The resulting filter is then resistant to deformation.

The DE 29 26 533 A1 discloses multi-layer filter disks made of wire mesh, which are pressed together under high pressure over the entire surface, as a result of which a porous filter layer is formed which is enclosed by a sheet metal ring so that the pore size set by the pressure is retained.

The U.S. 2,334,263 A discloses the production of a wire mesh composite body from a wire mesh layer which is rolled up into a roll and then compressed in a pressure cylinder.

The DE 28 349 069 A1 relates to a smoke filter, in particular for motor vehicle applications, the filter bed not suffering any deformation or displacement during operation and retaining its original shape and texture even under difficult operating conditions.

The DE 10 2012 220 159 A1 discloses a filter for process gases in soldering systems and soldering suction systems, with special chemicals being used which can be arranged on a metal mesh.

The DE 20 2007 000 177 U1 discloses a filter unit for separating soot, fine dust, dust and other emissions from exhaust air and exhaust gas, the exhaust gases being passed through an oil. In addition, steel wool is used to hold back oil.

The object of the present invention is to provide a filter element that is particularly easy to manufacture and that enables very good filtration performance. In particular, these filter elements should be designed to be adaptable and easy to reactivate in terms of their filter performance.

This object is achieved with the filter element according to the invention according to claim 1 and the method according to the invention for filtration according to claim 8. Advantageous developments are given in the dependent subclaims and the description.

On the part of the invention, it was recognized that this object can be achieved in a surprising manner in a particularly simple manner if flexible filter elements are used for this purpose, which can be reversibly compressed, for example, in order to thereby reduce the pore size. This can take place, for example, during the filtration through the applied differential pressure. This means that particles to be filtered are better rejected and less likely to get stuck in the filter element. In addition, the flexibility means that the pores widen again during backwashing, which accelerates the cleaning of the filter element. Or the widening can be generated by a negative bias. According to the invention, means are provided for selective pre-tensioning of the mesh structure in at least one direction in order to adapt the filter effect and / or to stretch the mesh structure for backwashing.

The filter element according to the invention therefore has a mesh structure with pores and is characterized in that the pore size can be reversibly changed when an external pressure is applied. In particular, such an acting external pressure can be the differential pressure built up during the filtration, whereby the pore size is reduced.

This reversible variability can be achieved, for example, by using a filter fabric. For example, stainless steel wire mesh can be used which contain crescent-shaped openings, the openings being reduced in size when a differential pressure caused by filtration is applied, or enlarged again or even widened during backwashing.

Conventional filter elements made of steel wires are also known, but there they are rolled or welded into grids. This rigid construction, structure and processing bring significant disadvantages in terms of function, durability and cost. They filter poorly, have to be cleaned and replaced more often and cause higher costs. These filter grids are also exposed to considerable pressures from the filtrate and cleaning fluid with opposite flow directions. There are also temperature fluctuations and aggressive media. Due to the rigid construction, the load on the connection points is extremely high. The grilles break and no longer work properly. In addition, it should be noted that conventional filter elements are cheaper to buy, but have to be cleaned, serviced and replaced much more frequently. This reduces the reliability of the filter performance and increases the costs for cleaning, maintenance and replacement investments. These disadvantages are also overcome by the construction according to the invention.

Folded mesh filters are particularly preferred, since filter elements of any shape can be manufactured particularly easily and inexpensively and these filter elements also have an excellent filter performance. Due to the folding, the mesh structure does not have to correspond directly to the particle size to be filtered, but the pore size is specifically adjusted by the folding. In this regard, it is advantageous if not only a folding but also a compression takes place, which can in particular take place transversely and / or longitudinally to the folding. This folding also brings about the flexibility of the filter element to change the pore size or, in combination with the special filter fabric, significantly increases it again.

The mesh structure is therefore preferably on, the mesh structure being provided on a surface element which is folded at least once.

If the mesh structure is folded many times, in particular folded in a meander shape, and / or at least doubled, preferably at least tripled, most preferably at least quadrupled, in particular at least fivefold in thickness compared to the surface element with regard to a filter passage direction through the pleat, then the filter element is particularly effective.

If the surface element is in the form of a wire or chain mesh, then the surface element can be produced particularly easily and the folding process is considerably facilitated. Wire meshes are preferred because the filter element produced is then stable in its created form and at the same time, with the appropriate choice of material, builds up certain restoring forces against applied pretension. The folding is advantageously carried out transversely or perpendicularly to the longitudinal extension of such wires. The surface element can be present as a fabric.

The mesh structure preferably comprises a metal, in particular stainless steel, duplex and super duplex steel, Inconel, Monel, because then the filter element is largely insensitive to many substances and can be cleaned particularly easily. Such filter elements have a wide field of application, in addition to petroleum filtrations also being possible in the food sector.

It is also preferred if the mesh structure is designed to be compressible, because the function according to the invention can then be implemented particularly easily.

If the underlying surface element has a two-dimensional surface or is designed as a tube, the filter element can be produced very quickly in any desired shape. Such two-dimensional surfaces can be flat or curved in any shape. Tubing surfaces can be peripheral surfaces of a cylinder or also peripheral surfaces of convex or concave polyhedra, for example of barrels or pellets.

The filter element according to the invention can be produced in any shape, the following shapes being preferred because of their advantageous filter effect and cleanability: cylinder shape, cylinder shape open on one side, hollow cylinder shape, box shape, pot shape, cuboid shape, cube shape, spherical shape, lens shape, prism shape, pyramid shape, cone shape, truncated cone shape , Cylinder stump shape, disc shape, ring shape and tube shape. It is expediently provided with at least one collar, for example for manipulating and removing the filter element.

Means are provided for prestressing the mesh structure in at least one direction, the means preferably being adapted to generate a positive prestress in relation to an untensioned normal state in the filter element densifying the mesh structure, and / or generating negative prestress in order to stretch the mesh structure. This preload, which is also an externally applied pressure, allows the filter effect to be specifically adapted to the requirements and backwashing and reactivation is made considerably easier. The preload can be designed in such a way that the differential pressure caused during the filtration no longer leads to any further pore size reduction or no further pore enlargement takes place during backwashing because the pores are already expanded far beyond the normal state.

The means for pretensioning can be present, for example, as a holder for the filter element with at least two holder jaws, between which the filter element is inserted, the distance between which can be selectively adjusted. This allows targeted compression of the filter element and when the distance is increased to the original filter element dimension, the pretension can be removed again. If the jaws are fixedly connected to the corresponding sides of the filter element, the filter element can be stretched, equivalent to a negative bias, by specifically expanding the distance between the jaws.

A filtering device would have the filter element according to the invention.

Independent protection is claimed for the method according to the invention for the filtration, in particular of liquids and gas, with the aid of at least one filter element which is characterized in that at least one filter element according to the invention is used.

In an advantageous development it is provided that the filter effect is adapted by setting a certain bias voltage in at least one direction on the filter element and / or that backwashing is carried out to clean the filter element, with a negative bias voltage being set on the filter element in at least one direction in particular so that the mesh structure is stretched. However, in most cases it will be sufficient to reduce or remove the pre-tensioning during backwashing so that no negative pre-tensioning is required.

A method for producing filter elements would be characterized in that a mesh structure is produced with pores, the size of which can be reversibly changed when exposed to external pressure.

It would be particularly advantageous if a surface element with a mesh structure is folded at least once, the surface element in particular being pressed into a shape in order to fold the mesh structure and form the shape of the filter element.

In addition, the filter element would preferably be designed as the filter element according to the invention.

A device for producing filter elements would be characterized by means for producing a mesh structure with pores, the size of which can be changed reversibly under the action of an external pressure.

In a preferred development, it would be provided that the device is adapted to carry out the method for producing filter elements, means for at least one folding of at least one surface element with a mesh structure being preferably provided.

1. 1. Die Filterelemente sind unter anderem hervorragend einsetzbar:
   • • bei Hochtemperatur-Anwendungen,
   • • bei korrosiven Flüssigkeiten und Gasen,
   • • bei hoher mechanischer Beanspruchung,
   • • bei starken Vibrationen,
   • • bei hydraulischen Einwirkungen,
   • • bei Schwankungen von Durchflussrate, Druck und Verunreinigungen und
   • • bei begrenzten Platzverhältnisse.
2. 2. Dabei ermöglichen die erfindungsgemäßen Filterelemente unter anderem:
   • • eine Filtrationsqualität von 30 µm bis 600 µm,
   • • eine Betriebstemperatur von -60 °C bis 816 °C (-76 °F bis 1500 °F),
   • • einen Max. Δp über dem Filterelement: bis zu 360 PSI und
   • • einen Max. zulässiger Betriebsdruck: bis zu 29.000 PSI.
3. 3. Die bevorzugten Einsatzgebiete für die erfindungsgemäßen Filterelemente sind unter anderem:
   • • Öl-Förderung, um Kühlflüssigkeiten schnell und effizient zu filtern,
   • • Gas-Förderung, um feste Bestandteile aus dem Gas herauszufiltern,
   • • Fracking (Hydraulic Fractioning), um das Frack-Fluid, das aus vielen unterschiedlichen Bestandteilen besteht, zu filtern,
   • • Automotive,
   • • Luft- und Raumfahrt,
   • • Schiffsbau - Ballastwasser-Filtration,
   • • Eisenbahn und Transport,
   • • Verteidigung und
   • • Meerwasser-Filtration.

Die erfindungsgemäß vorgesehene Flexibilität der Porengröße kann dabei sowohl durch die besondere Struktur des Flächenelements, also beispielsweise mit sichelförmigen Öffnungen, als auch durch die Faltung erzielt werden, wobei vorteilhafterweise eine Kombination aus beiden Maßnahmen gewählt wird.The particular advantages of the present invention can be illustrated as follows.

1. 1. Among other things, the filter elements can be used excellently:
   • • for high temperature applications,
   • • with corrosive liquids and gases,
   • • with high mechanical stress,
   • • with strong vibrations,
   • • in the event of hydraulic effects,
   • • in the event of fluctuations in flow rate, pressure and contamination, and
   • • when space is limited.
2. 2. The filter elements according to the invention enable, among other things:
   • • a filtration quality of 30 µm to 600 µm,
   • • an operating temperature of -60 ° C to 816 ° C (-76 ° F to 1500 ° F),
   • • a max. Δp over the filter element: up to 360 PSI and
   • • a maximum allowable operating pressure: up to 29,000 PSI.
3. 3. The preferred areas of application for the filter elements according to the invention include:
   • • Oil production to filter coolants quickly and efficiently,
   • • Gas conveyance to filter solid components out of the gas,
   • • Fracking (Hydraulic Fractioning) to filter the fracking fluid, which consists of many different components,
   • • Automotive,
   • • Aerospace,
   • • Shipbuilding - ballast water filtration,
   • • rail and transport,
   • • Defense and
   • • Sea water filtration.

The flexibility of the pore size provided according to the invention can be achieved both by the special structure of the surface element, for example with sickle-shaped openings, and by the folding, a combination of both measures being advantageously selected.

• 1 ein erstes bevorzugtes Referenzbeispiel des Filterelements in einer perspektivischen Ansicht,
• 2 das dem Filterelement nach 1 zugrunde liegende Flächenelement in einer Detailansicht,
• 3 eine Querschnittsansicht des Filterelements nach 1,
• 4a bis 4 Querschnittsansichten alternativer Ausgestaltungen des Filterelements,
• 5a, 5b perspektivische Darstellungen verschiedener alternativer Ausgestaltungen des Filterelements und
• 6 eine bevorzugte Ausgestaltung der Filtriereinrichtung in einer Schnittansicht.

The characteristics and further advantages of the invention will become clear in the context of the following description of preferred reference examples in connection with the figures. Purely schematically show:

• 1 a first preferred reference example of the filter element in a perspective view,
• 2 that according to the filter element 1 underlying surface element in a detailed view,
• 3 a cross-sectional view of the filter element according to FIG 1 ,
• 4a to 4th Cross-sectional views of alternative designs of the filter element,
• 5a , 5b perspective representations of various alternative configurations of the filter element and
• 6th a preferred embodiment of the filtering device in a sectional view.

In 1 to 3 is a first preferred embodiment of the filter element 1 shown in different views. It can be seen that this filter element 1 has the shape of a pot, namely as a hollow cylinder open on one side with a circumferential collar 3 is trained (cf. 1 and 3 ).

In 1 it can also be seen that the filter element 1 from a mesh structure 5 consists of pores 7th includes, the mesh structure 5 by multiple folding of a surface element 9 was created, which is partially in 2 is shown. It can be seen there that the surface element 9 as a braid of wires 11 is formed, which is essentially in a laying direction V extend and crescent shaped openings 12th that react flexibly to external pressure. The fold to form the filter element 1 took place essentially across this laying direction V so that there is a dimensionally stable filter element 1 results, which is therefore dimensionally stable, without the need for an adapted housing.

Inconel is used as the material, which makes the filter element 1 is largely resistant to aggressive substances and can therefore be used in the food sector. The wire 11 is cold drawn and without rolling or welding to form the surface element 9 so interwoven that crescent-shaped openings 12th form. In addition, a compression took place with the folding, so that a certain pore size is set, whereby certain particle sizes 13 be filtered.

In connection with the choice of material and the incomplete compression, the build-up of restoring forces results R. of the filter element 1 compared to the entry of preloads or differential pressures K in the direction of the longitudinal extension L. of the filter element 1 . This means that when a positive preload or a positive differential pressure K + is entered, an opposing negative restoring force R + acts and when a negative preload or a negative differential pressure K- is entered, an opposing positive restoring force R- is built up, each after the end of the action of the external pressure and the corresponding compression or expansion to normalize the filter element 1 to lead.

This allows the filter element 1 reversible according to the invention with the involvement of suitable means (not shown) in the longitudinal direction L. be compressed and relaxed again or stretched and relaxed again. Compression reduces the pore size, leaving finer particles 13 can be filtered, while by stretching, the pore size is enlarged and thus finer particles 13 be let through. The latter can be used, for example, when pressing “naturally cloudy” juices and the like.

In addition, the filtration itself also leads to the build-up of a differential pressure, which compresses the mesh structure and thereby the pores 7th be reduced.

For the one-time or periodically recurring reactivation by means of backwashing, it is advantageous if during the backwashing an expansion takes place by the appropriate means, so that the pores are opened 7th can be enlarged so that they can be flushed and cleaned more easily. This brings about an even better cleaning, but also the flexibility of the filter element 1 already to leads to an enlargement of the pores compared to the filtering, whereby the cleaning takes place easily.

The manufacture of the filter element 1 takes place in that a tubular surface element (not shown) is introduced into a cup-shaped shape with a central mandrel (comparable to a cup cake shape) and meander-shaped in the longitudinal direction by means of a punch L. folded on top of each other and compressed so that the desired size of the pores 7th adjusts. As a result of the folding, the surface element completely fills the shape and a mesh structure results 5 , as 1 is shown.

The size of the pores can thus be adjusted via the compression during the shaping, but also through targeted adjustment of the mesh size, wire thickness and layer thickness of the underlying surface element.

In the 4a Various alternative configurations are shown in FIG 4a a filter element 20th in the form of a hollow cylinder, in 4b a filter element 30th in the form of a disc, in 4c a filter element 40 in the form of a cup with an opening 41 in the ground 43 , in 4d a filter element 45 in the form of a bowl, in 4e a filter element 50 in the form of a lens, in 4f a filter element 60 in the form of a barrel and in 4g a filter element 70 in the form of a ring element.

In the 5a and 5b Different shapes and filter elements are shown, namely hollow cylindrical or tubular filter elements of different sizes and shapes 20 a to 20 g , various large and shaped disc-shaped filter elements 30a to 30e , various sizes and shapes of cup-shaped and perforated filter elements 40a to 40d , the cup-shaped filter element 45 after 4d , two barrel-shaped filter elements 60a running on a common conduit 61 are arranged, a frustoconical filter element 90 with collar 91 , a variety of different sized and shaped annular filter elements 93a to 93c and a variety of disk-shaped, perforated filter elements of various sizes and shapes 95a to 95g . It can be seen that the most varied shapes and sizes can be produced in a dimensionally stable manner with the manufacturing process.

The specialty of the cylindrical filter elements 20a to 20c is that they have bezels on both sides 21st which makes them easier to store in cascades. In order to defy the compressibility, a high rigidity of the cylindrical filter element 20d to achieve are the two bezel rings 21st via an internal stiffening element 23 rigidly connected to each other.

In 6th in a preferred embodiment of the filtering device 100 shown in cross section. It can be seen that this is in the usual way with a housing 101 , an inlet 103 and an outlet 105 is formed, the outlet 105 in one with a lower housing part 107 screwable upper part of the housing 109 is provided. In the plane 111 between the lower part of the housing 107 and upper part of the housing 109 are three filter cascades 113 attached, each with a conduit pipe closed at the bottom 115 have with radial openings 117 to the supply line, with this line pipes 115 a number of filter elements 60 in barrel form 4f are arranged sealed.

During the filtration, the substance to be filtered becomes 119 , for example a liquid, through the inlet 103 into the filtering device 100 guided, penetrates the filter elements with the removal of filtered particles 60 the filter cascade 113 and leaves the filtering device 100 as a filtrate 121 through the outlet 105 .

A reactivation of the filter device 100 can be done by backwashing, with a cleaning fluid, such as water, flowing through the outlet 105 pressed and so the particles in the cleaning liquid through the inlet 103 be discharged. The housing can be cleaned completely 101 opened and the filter elements 60 can be removed and individually reactivated or exchanged.

From the above illustration it has become clear that the present invention provides a filter element 1 is provided, which can be produced particularly easily and thereby enables a very good filtration line. Here is the filter element 1 its filter performance can be adapted and easily reactivated.

Unless otherwise stated, all features of the present invention can be freely combined with one another. Unless otherwise stated, the features described in the description of the figures can also be freely combined with the other features as features of the invention. Objective features can also be used as process features and process features as objective features.

List of reference symbols

1

Filter element

3

collar

5

Mesh structure

7th

Pores

9

Surface element

11

Wires

12

sickle-shaped openings

13

Particle sizes

20th

Filter element in the form of a hollow cylinder

20a to 20g

hollow cylinder or tubular filter elements

21st

Bezels

23

Stiffening element

30th

Filter element in the form of a disc

30a to 30e

disc-shaped filter elements

40

Filter element in the form of a cup

40a to 40d

Cup-shaped filter elements with a perforated bottom

41

Breakthrough

43

ground

45

Filter element in the form of a bowl

50

Filter element in the form of a lens

60

Filter element in the form of a ring element

60a

barrel-shaped filter elements

61

Conduit pipe

70

Filter element in the shape of a barrel

90

frustoconical filter element

91

collar

93a to 93c

annular filter elements

95a to 95g

disc-shaped, perforated filter elements

100

Filtering device

101

casing

103

inlet

105

Outlet

107

Housing base

109

Housing upper part

111

Level between the lower part of the housing 107 and upper part of the housing 109

113

Filter cascades

115

Line pipes 115

117

Breakthroughs

119

substance to be filtered

121

Filtrate

K

preload

L.

Longitudinal extension of the filter element 1

R.

Restoring forces

V

Laying direction

Claims (10)

Filter element (1) with a mesh structure (5) with pores (7), characterized in that the pore size can be changed reversibly under the action of an external pressure, means for selective pretensioning of the mesh structure in at least one direction being provided in order to adapt the filter effect and / or to stretch the mesh structure (5) for backwashing. Filter element (1) after Claim 1 , characterized in that the mesh structure (5) is provided on a surface element (9) which is folded at least once, the surface element being present as a wire or chain mesh. Filter element (1) after Claim 2 , characterized in that the mesh structure (5) is folded many times, in particular folded in a meander shape, and / or that in relation to a filter passage direction through the fold at least one doubling, preferably at least one tripling, most preferably at least four times, in particular at least five times the Thickness compared to the surface element (9) is present. Filter element (1) according to one of the preceding claims, characterized in that the mesh structure (5) comprises a metal, in particular stainless steel, duplex and super duplex steel, Inconel, Monel and / or that the mesh structure is designed to be compressible. Filter element (1) according to one of the preceding claims in connection with Claim 2 , characterized in that the underlying surface element (9) has a two-dimensional surface or is designed as a tube. Filter element (1) according to one of the preceding claims, characterized in that the Filter element (1) has one of the following shapes: cylindrical shape, cylinder shape open on one side, hollow cylinder shape, box shape, pot shape, cuboid shape, cube shape, spherical shape, lens shape, prism shape, pyramid shape, cone shape, truncated cone shape, truncated cylinder shape, disc shape, ring shape or tube shape and preferably with at least one Collar is provided. Filter element (1) according to one of the preceding claims, characterized in that means are provided for prestressing the mesh structure in at least one direction, with means preferably being adapted to generate a positive prestress in relation to an untensioned normal state in the filter element (1), to compress the mesh structure (5), and / or to generate negative prestress in order to stretch the mesh structure (5). Method for filtration, in particular of liquids and gas, with the aid of at least one filter element (1), characterized in that at least one filter element (1) according to one of the Claims 1 to 7th is used. Method of filtration according to Claim 8 , characterized in that the filter effect is adapted to the filter element (1) by setting a certain pre-tension in at least one direction. Method of filtration according to Claim 8 or 9 , characterized in that backwashing is carried out to clean the filter element (1), a negative preload being set on the filter element in at least one direction, so that the mesh structure (5) is stretched.

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