DE8906036U1 - Filters for separating solid particles from hot, gaseous or liquid media - Google Patents

Description

Applicant: HERDING GmbH

August-Borsig-Strasse 3

D-8450 Amberg/Federal Republic of Germany

Representative and delivery- Fritz MERTEN
Authorized representative: Patent and civil engineer

Tristanstrasse 5

D-8500 Nuremberg 40/Federal Republic of Germany

Astliehes reference number: Applicant No.: 309 07 95

Our reference: 31.4419
Date: 09.05.1989

Title: Filter for separating solid particles from hot, gaseous or liquid media

The invention relates to a filter for separating solid particles from hot, gaseous or liquid media, in particular dust particles from hot flue gases in the temperature range between 120 and 800° C, consisting of a permeable, dimensionally stable carrier material with large pores, i.e. a support body, whereby the carrier material is heat-resistant and in particular contains components of non-corrosive materials, such as glass, ceramics, metals or compounds thereof, and in which filter the carrier material can be produced by intimate, partial bonding of its heat-resistant particles, and the carrier material also has a structure or spatial shape adapted to the application and the given volume.

It is generally known that filters can be used to separate particles from gaseous or liquid media and that, depending on their application, they can be classified as textile, carbon fibre or

water filters, felt filters, paper filters, plastic filters, metal or ceramic filters. While textile, felt, paper and plastic filters are used in a lower temperature range up to approx. 150° C, metal and ceramic filters can cover the higher temperature range, up to about 800° C, so that the latter filters are also suitable for use in the flue gas area of heating systems. This is particularly desirable because, with increasing reductions in environmentally harmful emissions, the filtration of hot gases with temperatures of more than 250° C is becoming increasingly important, because on the one hand the high heat content of the cleaned gas can then be used without further measures, and on the other hand these flue gases cause less pollution of the environment.

The use of the above materials for the filters has shown that glass, ceramic and carbon fibers are fragile due to their brittleness, and that in the case of metal wires or metal meshes, the space between the wires is too large to achieve a sufficient filtering effect for fine dust. In addition, the use of heat-resistant materials such as sintered materials, porous, small-pore ceramic materials, etc., is relatively ineffective, as the initially good filtering effect continually deteriorates because fine dust penetrates the pores of these materials, which cannot be removed even by special cleaning measures and ultimately leads to the filter becoming clogged.

The filters that have been established for use in the so-called high temperature range are those whose filter elements are often made of clay or ceramic and which, for the sake of simplicity, are designed as cylindrical tubes in the form of filter candles. These filter candles, the end-

are open on the sides, are installed between brackets in the housing for the filter and are secured there in such a way that the medium to be filtered penetrates through the casing of the filter candle into the interior and leaves this interior again through an opening at one end of the filter candle. This opening in the filter candle leads into a space for the filtered medium, which this medium leaves via an outlet nozzle on the filter. The filter candles secured to the brackets are rigidly placed on them ^and cannot follow the loads caused by the flow of the medium and in particular the loads caused by countercurrents during cleaning of these candles, which means that breakages, particularly at the necks of the filter candles, cannot be prevented (cf. DE-PS 30 17 851).

In order to avoid such damage to the filter candles in particular, filter candles of this type are attached to their holders in a pendulum manner . This pendulum attachment of the respective filter candle is made possible by the fact that, on the one hand, the holder separating the clean room from the filter room is designed as a perforated plate, with the holes designed so that they have a larger opening cross-section towards the room than towards the filter room. The filter candle, in turn, is provided with a flange-shaped collar on its end facing the clean room, with which this filter candle rests on the inward-drawn bulge of the hole in the holder. In order to ensure that the filter candle rests better on this bulge, this bulge can also be designed as a dome-shaped annular shoulder, and the further cross-section of this hole is designed to be wider from this annular shoulder, increasing towards the filter room, in order to create the necessary space for the filter element to pendulum. The end of the filter element, ie the filter candle, facing away from this neck is provided with a hole into which a

Bolt engages. This bolt can be inserted into the hole either with or without play, whereby in the case of a bolt without play the bolt is supported against the filter candle via an elastic sleeve. The dome-shaped ring shoulder on the neck of the filter element and the elastic support of the bolt at the opposite end on the one hand enable the bolt to be supported at the opposite end and on the other hand the pendulum-shaped suspension of the filter candle on the brackets so that it is better protected against damage compared to fixedly adjusted filter candles. However, it is considered a disadvantage with this filter that the respective filter candle is clamped too unstably between the brackets, which on the one hand can lead to sealing problems and thus to contamination of the filtered medium and on the other hand the removal of the filter candles is made more difficult by hanging the filter candles on the dome-shaped ring shoulders (cf. DE-PS 35 15 365).

Accordingly, the invention is based on the object of developing a filter of the type mentioned at the beginning in such a way that it is suitable for filtering hot media, such as flue gases, etc., whereby despite high temperatures, e.g. 600° C and possibly more, the filter retains its dimensional stability and filtering effect and is not prone to cracks or the separation of material components, and furthermore this filter is attached absolutely tightly to the holders, can be mounted and dismounted from them without great effort and also remains attached to these holders in such a way that even mechanical stress on it, especially during cleaning, cannot lead to damage to it.

According to the invention, this object is achieved in that

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the structure of the carrier material provided with larger pores is covered on one of its outer surfaces with a fine-grained and also heat-resistant filler material that enables finer pores, and this filler material is applied to the carrier material in particular as a thin coating, and that this filler material consists of parts of a dispersed mixture, of which a part can be volatilized from the mixture during a firing process, while another part can be inserted into the larger pores of the carrier material, and that this mixture is prepared using an adhesion promoter and a suspension liquid and can be applied to the carrier material in this state of aggregation, where it can be bonded partly to itself and partly to the carrier material, and that these fine-grained components of the filler material, as well as the adhesion promoter, consist of a respective substance that has a linear thermal expansion coefficient that is approximately the same as the carrier material, and the material of the filler material is in such a way that its grain size is such that the pore size of the filling material is still below 10 μπα, and this filling material is embedded in the larger pores in the area of the shell of the carrier material and there, in particular, fills the larger pores of the carrier material, at least partially.

These measures not only advantageously solve the problem underlying the invention, but also provide the advantage that the different structures of the filter, i.e. its carrier material and filler material, have the same or almost the same thermal expansion behavior and that, despite special adhesion conditions, these tend neither to damage their structures nor to expand the pores, especially of the filler material. This special design of the filter ensures a

Excellent filtering effect, even when the temperatures of the media to be filtered fluctuate greatly, so that this filter is particularly suitable for hot gases in the temperature range from 250 ° C up to 600 - 800° C. Because all materials and thus all structures of the _filter can follow temperature fluctuations without damage, it is almost impossible for cracks or flaking to occur, especially in the cover layer, so that this filter also has surface filtration, which has the advantage of a largely blockage-free filtering effect. This surface filtration also prevents increasing pressure losses, so that the filter can be operated with a constant, low energy consumption.

The different structures of the filter can also be varied according to the requirements of the filter, so that, for example, the carrier material can be given a larger or smaller pore size. Analogous to this pore size, the pore size of the filling material can also be made larger or smaller, e.g. in such a way that either coarse or fine-grained filling material is applied to the carrier material or the carrier material is covered with more or fewer layers of the same. The filling material can also be made of, for example, heat-resistant glass beads, ceramic grains or powder, fibers.

i| etc., which, after being applied to the carrier material, cover it in a film-like manner.

p A further advantageous embodiment of the invention is characterized by the fact that the filter is designed as a dimensionally stable filter candle and that this filter candle is clamped between the holders in a spring-loaded manner and is hermetically sealed against the interior of the filter housing by these holders, that to hold each filter candle on

these holders, each filter candle has an injector-shaped pipe flange at its end facing the clean room and a round bolt at its end facing the base of the discharge shaft, both of which, pipe flange and round bolt, have a belt -shaped collar, a seal is provided between the and the filter candle on the one hand and the and the holder on the other hand, and that ;, in addition to these calibrating guide and cooling means for the filter candle, a spring is provided between the collar of its round bolt and the holder, which presses the filter candle against all ^; ,'| its seals and/or individual seals itself. |§

Another development of the invention is characterized in that the injector-shaped pipe flange has a skirt that dips into the filter candle from its collar and a collar that is raised in the opposite direction from this collar, and that this collar extends through the opening of the holder into the clean room. %

Another advantageous embodiment is that the ' round bolt has annular grooves, at least in its section between its collar and its projecting extension, and that this section is inserted into holes in the holder.

Further advantageous developments of the invention can be found in particular in the remaining subclaims, for which independent protection is also claimed within the scope of this application.

Some of the possible embodiments of the invention are shown schematically in the drawings. They show:

Fig. 1 is a side view of a cylindrical tube

- 8 right-hand filter element,

Fig. 2 a section through the filter element in the plane H-II in Fig. 1,

Fig. 3 a side view of a filter element designed as a plate pack,

Fig. 4 a section through the filter element in the plane IV-IV in Fig. 3,

Fig. 5 is an enlarged plan view of a section of the cut filter element according to Fig. 1 or 3 with several balls forming the cover layer thereof, e.g. of the same diameter,

Fig. 6 is a similar, enlarged top view as Fig. 5, but with balls, e.g. of different diameters,

Fig. 7 a section through the filter element in the area of its cover layer with a row of balls accumulated on it and powder particles embedded in the carrier material according to section III,

Fig. 8 a longitudinal center section through a filter housing with a filter element consisting of several filter candles,

Fig. 9 a cross-section through the filter housing with two parallel arranged filter elements in the plane H-II in Fig. 1,

Fig. 10 is an enlarged view of a filter element designed as a filter candle and the filter

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_ 9 candle holding support in section,

Fig. 11 an enlarged longitudinal center section through the head of the filter candle with the pipe flange supporting it against its holder, and

Fig. 12 an enlarged longitudinal center section through the base of the filter candle with the round bolt supporting it against the holder.

The filter housing 1 according to Figures 1 to 7 is shown and described here using the example of two of the possible configurations. A simple configuration of this kind can be a tubular filter element 1, as shown in Figures 1 and 2. This filter element 1 is designed in such a way that it forms a cylindrical support body 2, which has a flange-shaped head 3 at its fine end and a base 4 at its other end. While the flange-shaped head 3 has the opening cross-section 5 of the filter element 1, i.e. the support body 2, which at the same time approximately corresponds to the opening cross-section 6 of the cylindrical support body 2, the base 4 of the support body is designed as a closure of the same and is optionally provided with a foot 7 in order to be able to fix the support body in a support frame 8 of a filter housing 13. The support body 2 itself, which is made of a heat-resistant material, e.g. ceramic, has a large-pored structure, i.e. large pores 9, onto which a fine-pored structure in the form of a cover layer 11 with fine pores 10 is applied. This cover layer 11 forms the filtering surface of the filter element 1, on which the particles to be separated out of the medium to be filtered are separated.

The filter element 1 according to the further possible configuration

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The device according to Fig. 4 is based on a so-called lamella filter, as shown for example in DE-OS 34 13 213 and differs from this essentially in that its carrier body 2 or its carrier material is made of a heat-resistant material, e.g. of the ceramic origin described above, and its cover layer 11 is formed by a plurality of bodies 12, preferably in the form of spheres and/or powders, which are also made of heat-resistant material and are connected to the material of the carrier body 2 and/or to one another.

The different parts of the filter element 1, i.e. the carrier material 2 and its backing layer 11, have different pore widths, whereby the pores 9 of the carrier material must be larger than the pores 10 of the cover layer so that filtration of the medium can take place on the surface of the filter element 1.

t The carrier material 2 made of ceramic can be in the form of a

Aluminium oxide (AI2O3), zinc oxide (ZnO2) or silicon

zium oxide (S1O2), whereby its production can be carried out in such a way that the selected material is processed in the conventional way into a molding compound, e.g. extruded into tubes, and then fired, from which the open-pored, i.e. large-pored carrier body, i.e. the carrier material 2, is then created. If, however, the mass of the carrier material 2 is filled into molds, which can often be more advantageous, the flange-shaped head 3 and the base 4 closing the tube can also be filled.

The fine-pored cover layer 11 is applied to the outer surface of this coarse-pored carrier material 2 either in the form of an emulsion by spraying or brushing, whereby this emulsion is mainly distributed in the

- 11 -

openings or holes in the carrier material and covers the larger pores 9 with a large number of small openings or pores 10. The small pores 10 on the cover layer 11 are produced by the material of the cover layer, e.g. in the form of larger and smaller bodies 12, e.g. balls, connecting partially, e.g. point-like or line-like, with the unconnected surfaces retaining the openings in the form of pores 10. These pores 10 or openings can be dimensioned to a large extent as desired, so that the cover layer 11 or the top layer forms a fine-pored layer, like a film that still allows a medium to pass through, which has a fine dimension of pores 10.

Another possibility for applying the cover layer 11 is to make a slip from the fine-grained powder for the cover layer, as is used in a similar consistency for enameling. The carrier body, i.e. the carrier material 2, can be immersed in this slip. This cover layer is then fired together with the carrier material, creating a fine and open-pored engobe, similar to a glaze. As with the carrier material 2, the required, small, open pores 10 are created here by evaporating the suspension liquid.

To manufacture the filter element 1 from these heat-resistant materials, it is first assumed that components of the same basic materials are used for the carrier material 2 and its cover layer 11, whereby the adhesion promoter used causes these materials to melt together on their surface in the manner of sintering when these materials are heated (e.g. during the firing process), thereby creating a homogeneous, solid bond.

- 12 -

This is the case and was also determined by various tests with carrier material 2 and cover material 11 made of aluminum oxide (AI2O3) as well as a ceramic adhesive of similar consistency.

Similarly stable structures are created when chemically non-identical but similar substances interact with one another and they mix with one another in the liquid state (eutectic, for example, from AI2O3 and S1O2 or ZnO2 and S1O2). A chemical bond between the carrier material 2 and the cover layer 11 is also possible, provided that it is stable at the operating temperature and has approximately the same or better chemical resistance to structural changes as the carrier or cover material 2, 11. The partial bond between the carrier and cover material 2, 11 is made by an adhesion promoter 14, which, depending on the type of bond, can be applied during the firing process, similar to an applied glaze, or as an adhesive bond.

The thickness 15 of the coating, i.e. the cover layer 11, can be easily adapted to the respective requirements for the degree of purity of the medium by applying more or less cover material to the carrier material 2. This measure can also increase the filtering effect of this cover layer 11 accordingly.

The connection between the cover layer 11, i.e. its filling material, and the carrier material 2 is preferably a homogeneous, intimate connection that generally cannot be broken. This is important in that the cover layer 11 cannot be washed off the carrier material 2, which could easily happen when filtering liquids.

The filter element 1 according to the invention, according to the embodiment

8-12 differs little from the filter element according to Fig. 1 - 7 and is also used to separate particles from gaseous or liquid media. For the sake of better understanding, this filter element 1 is designed as a tube or filter candle and is essentially arranged in a filter housing 13 together with at least one other filter element in this housing. The housing 13 itself has a clean room 16 for the filtered medium and a discharge shaft 17 for the particles, as well as inlet and outlet nozzles 37 and 38 for the medium. The filter element 1, which according to the example shown here is designed in the form of the tubular filter candle, is preferably also made of a ceramic material, which consists, for example, of a support body 2 having larger pores 9 and a surface coating, i.e. cover layer 11, with fine pores 10. The attachment of this filter element 1, i.e. The installation of the filter candle, i.e. the respective filter candle, in the filter chamber of the filter housing 13 can be carried out vertically or horizontally, with each filter candle having special fastening parts at its respective end, i.e. candle head 18 and candle base 19, by means of which it is fixed to brackets 20, 21 in the filter chamber. The fastening parts on the candle head 18 are essentially formed by an injector-shaped pipe flange 22 and at least one seal 23, 24, of which the pipe flange has, in addition to an annular collar 25, a collar 26 projecting into the clean chamber 16 and a skirt 27 immersed in the filter element 1. The annular collar 25, which forms approximately the belt line of the pipe flange 22, has a larger diameter than the casing of the filter element 1. As a result, the pipe flange 22 has sufficiently large supports against which the ends of the filter element, i.e. the filter candle, on the one hand against the holder 21 for this candle and on the other hand against the holder 20 at the clean gas end.

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In order to make the seal very effective, it is recommended to provide seals 23, 24 on both sides of the ring collar 25, i.e. coaxially to it, one of which could be a ring seal 32 and the other seal 24 could also have a sack-like extension in addition to the ring surface. In such a case, the sack-like extension would concentrically enclose the shirt 27 that dips into the filter element 1 and provide both a seal and a radial, elastic support. Of course, it is also conceivable to provide a ring seal 32 at this point instead of the sack-like seal and to support the filter candle and holder 20 against each other only via this seal.

The other flange of the filter element 1 is primarily supported on the flange 28 of a round bolt 29, whereby this bolt - similar to the pipe flange 22 - also has a collar

30 and an opposite extension

31. With the collar 30, this round bolt 29 is inserted into the free end of the filter element 1 up to the collar 28, whereby this collar can have no or only a small radial play between itself and the inner casing of the filter element. The actual sealing of this end of the filter element 1 at the candle base 19 is carried out, as well as at the candle head 18, via a ring seal 32, against which the end of the filter element is sealingly applied. The extension 31 of the round bolt 29 itself dips into a hole 33 in the holder 21 and engages into it so far that the filter

: terelement 1 not only against radial movements, but

j also remains guided against axial _t in the bore. To

In order to hermetically seal the respective filter element 1 against the filter chamber of the filter housing 13, a spiral spring 34 is placed around the extension 31 between the collar 28 of the round bolt 29 and the holder 21, which spring is against the Bw.xi 28 on the one hand and against the holder 21 on the other hand.

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This spiral spring 34 presses the filter element 1, i.e. the filter candle, against the seals 23, 24 on the candle head 18, as well as the collar 28 against the ring seal 32, so that these seals come into full contact there.

The round bolt 29 itself can be attached to its collar 30 and ^ Extension 31 may be solid-walled, or it may have annular grooves 35 J|

, as shown in the drawing Fig. 10 S . Instead of the round bolt 29, an equivalent guide part, such as a pine-shaped spring or an arm cross, could also be used. Likewise, instead of

the spiral spring 34 a disc spring or a plate spring |j

derpaket can be used, which provides the axial preload |

of the filter element 1. I

The brackets 20, 21 themselves, which can be designed as U-shaped % struts, are fixed with their ends to

Brackets 36 of the filter housing 13 are supported and can *

be supported there rigidly or elastically.

The medium to be filtered, which enters the filter chamber of the filter housing 13 through the inlet connection 37, flows around the individual filter elements 1 and passes through them into the clean room 16, while the particles it carries with it adhere to the casings of the filter elements. The medium which has entered the clean room 16 in this way leaves the latter via the outlet connection 38 in order to reach the outside or to be fed into another process. The particles which have adhered to the filter candles are thrown off by a known counter-blowing of the filter candles from the inside to the outside and reach the discharge shaft 17, from which they are discharged continuously or discontinuously. The counter-blowing device can be a known jet cleaning device, the nozzles of which

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- 16 -

6. Blow your cleaning medium, e.g. compressed air, into the openings of the injector-shaped pipe flanges 22.

The assembly and disassembly of the filter elements 1, 2, 3 of the filter candles is made easier in this candle-shaped design in that after inserting the extension 31 of the ring 29 into the hole 33 of the holder 2 and pressing it against the force of the spiral spring 34, the collar 38 of the pipe flange 22 on the candle head is first pressed in front of the hole in the holder 20 at this end and after the pressure is slowly released, this collar snaps into the hole and fixes the filter candle there. The disassembly of the filter candle or the filter element 1 takes place in the reverse order when it is necessary to remove it from its holders 20, 21.

The composition of the filling material, i.e. the cover layer 11, which is applied to the support body 2, is composed of the following components according to an advantageous choice of material.

These components, which are dispersed as a mixture, are applied to the support body 2, ζ. β. using a brush, and this filling material is exposed together with the support body to a temperature of approx. 1 hour of approx. 500° C, whereby the filling material η burns into the material or the pores 9 of the support body 2.

The components of the filling material or the covering layer 11 can be composed as follows:

1 volume fraction of sodium silicate
14 volume parts water
4 parts kaolin by volume

. - 17 -

2 volume parts feldspar

2 parts starch (starch flour) by volume

0.2 volumes of sodium diphosphate

The filling material produced in this way and applied to the support body 2 is deposited in the area of the outer surface of the pores 9 of the support body 2 and fills them to such an extent that a film-like coating is formed on the surface of the same . The water is evaporated when exposed to a temperature of 4 and the starch is also separated from the mixture by combustion at this temperature.

As already mentioned above, the filter elements 1 are made of ceramic, heat-resistant material. This does not, of course, preclude the use of other filter elements 1, for example made of plastic, if the filter is to operate in a different temperature range. It is also possible to use other configurations of filter elements 1.

The filter element 1 was shown and explained here for the filtration of hot gases. Of course, this filter element 1 can also be used for the filtration of hot liquids or non-hot gases or liquids. This filter element 1 is also particularly interesting for aggressive media in the gaseous or liquid range, since it is hardly attacked by the aggressive substances.

The heat-resistant filter element 1 was shown and described here using the examples of the tubes and the so-called lamella filter, as shown in Fig. 1 - 4. Of course, this filter element 1 can also have other configurations.

here the configuration should be chosen that has the largest possible filter surface. Such a configuration can also be a combined one, such as oval, triangular, etc. The configuration will usually depend on the volume to be filtered, the stability of the filter element, i.e. the filter candle, and the medium to be filtered. The latter also determines the pore size, which is adjusted to the medium in order to optimize the pressure losses.

The function of the filter is shown and described here, in relation to jet cleaning, using the example of separating particles from gaseous media. The separation of particles from liquids takes place in a similar way, but in such a case the cleaning must be carried out differently, i.e. by countercurrent of a pure liquid. If the liquid allows air to be blown in, compressed air can also be used for cleaning.

; J". . &iacgr; ! "*· · ·**· "··; Filter element Our reference: 31.4419 &bull; REFERENCE SYMBOL LIST ·'"'-'' '··' Support body 34 Spiral spring Applicant: HERDING GmbH Head 35 ring grooves 1 Floor 36 Console 2 Opening cross-section 37 Inlet nozzle 3 Opening cross-section 38 Outlet nozzle 4 Foot 5 Support structure 6 Pores (large) 7 Pores (small) 8th Top layer 9 Body 10 Filter housing 11 Adhesion promoter 12 thickness 13 Cleanroom 14 Discharge chute 15 Candle head 16 Candle base 17 bracket 18 bracket 19 Pipe flange 20 poetry 21 poetry 22 Ringbund 23 collar 24 Shirt 25 Federation 26 Round bolts 27 collar 28 Extension 29 Ring seal 30 drilling 31 32 33

Claims (19)

ADDRESS 1. Filter for separating solid particles from hot, gaseous or liquid media, in particular dust particles from hot flue gases in the temperature range between 120 and 800° C, consisting of a permeable, dimensionally stable carrier material provided with larger pores, i.e. a carrier body, the carrier material being heat-resistant and in particular containing components of non-corrosive materials such as glass, ceramics, metals or compounds thereof, and in which filter the carrier material can be produced by intimate, partial bonding of its heat-resistant particles, and the carrier material also has a structure adapted to the application and the given volume, characterized in that the structure of the carrier material provided with larger pores (carrier body 2) is covered at least on the surface side with a fine-grained and also heat-resistant filling material (cover layer 11) which enables finer pores (10), and this filling material is applied in particular as a thin coating to the carrier material. material is applied, and that this filler material consists of parts of a dispersed mixture, of which a part can be volatilized from the mixture during a firing process, another part can be placed in the larger pores of the carrier material, and that this mixture is prepared by means of an adhesion promoter (14) and a suspension liquid and can be applied to the carrier material in this state of aggregation, where it can be connected partly to itself and partly to the carrier material, and that these fine-grained components (body 12) of the filler material, as well as the adhesion promoter, consist of a respective substance, which have a linear thermal expansion coefficient that is approximately the same as the carrier material (carrier body 2), and the material of the filler material is dimensioned in such a way in terms of its grain size that the pore size of this filler material is still below 10 μιη. and this filling material is embedded in the larger pores (9) in the area of the shell of the carrier material and there, in particular, fills these larger pores of the carrier material, at least partially. 2. Filter according to claim 1, characterized in that the fine-grained filling material (cover layer 11) in powder form is suspended with a liquid (e.g. water) and is applied to the carrier material (support body 2) after addition of the adhesion promoter (14), and that this filling material is connected to the carrier material via the adhesion promoter. 3. Filter according to claim 2, characterized in that the liquid for suspending the filling material (cover layer 11) is a substance (water) which evaporates under the influence of heat and which, after being applied to the carrier material (carrier body 2), leaves the filling material, leaving fine pores (10) in the latter. - 3 - I 4. Filter according to claim 1, characterized in that the filling material (cover layer 11) forms a homogeneous, inseparable bond with the carrier material (carrier body 2) through the action of heat. 5. Filter according to claim 1, characterized in that the filling material (cover layer 11) applied to the carrier material (support body 2) can be fired into the latter at an elevated temperature. 6. Filter according to claims 1 to 3, characterized in that the filling material (cover layer 11) is applied to the carrier material (support body 2) in at least one layer. 7. Filter according to claims 1 to 3, characterized in that the filling material (cover layer 11) is applied to the carrier material (support body 2) in two layers, of which the first layer consists of relatively large components which, in addition to narrowing the larger pores (9) of the carrier material, also serves as an additional support structure for the following second layer, and that the second layer consists of fine components, and this second layer has the necessary small pores (10) for surface filtration. 8. Filter according to claim 1, characterized in that the filling material (cover layer 11) can be applied to the carrier material (carrier body 2) by spraying it on and these materials are jointly subjected to an adhesion process, in particular a firing process. 9. Filter according to claim 1, characterized in that the filling material (cover layer 11) is an emulsion in a * t t * t t Φ &igr; &bull; * t t · « I ■ &igr; · &igr;&igr; · I ' &bull; I (I Il Il a bath is available, and that the carrier material (carrier body 2) is coated by immersing it in the emulsion and then these materials are subjected to a baking process. 10. Filter according to claim 1, characterized in that the carrier material (support body 2) and the filling material (cover layer 13) consist of ceramic, and that these materials are sintered together inseparably by the action of heat, but with open pores. 11. Filter according to claim 1, characterized in that the carrier material (support body 2) and the filling material (cover layer 11) form a eutectic mixture and are inseparably connected to one another after cooling. 12. Filter according to claim 1, which is in particular tubular designed and is inserted in a filter housing (13) with inlet and outlet nozzles (37, 38) for the medium to be filtered and filtered, as well as a discharge shaft (17) for the separated particles, and from the outside, through whose jacket the medium to be filtered can flow inwards and in the opposite flow direction, at intervals, for the purpose of cleaning, the jacket surface of which can be blown through or flowed through by a clean stream, and in which filter housing (13) in the area of its outlet nozzle (38) a clean room (16) for collecting and discharging the filtered medium, as well as at least one device for cleaning the filter element are provided, and between this device and the base of the discharge shaft (17) holders (20, 21) are provided for at least the one filter element (1) arranged between them, of which the cleanroom 1*4 *·
I > ti I &bull; I Il I · facing holder (20) is additionally equipped with at least one opening between the filter element (1) and the clean room (16) and the holder facing the base is equipped with at least one support (candle base 19) for the filter element (1), characterized in that the filter element (1) is designed as a dimensionally stable filter candle and that this filter candle is spring-loaded between the holders (20, 21), clamped and hermetically sealed at these holders against the interior of the filter housing (13). that in order to hold each filter candle on these holders , the filter candle has an injector-shaped pipe flange (22) at its end facing the clean room (16) and a round bolt (29) at its end facing the base of the discharge shaft (17), both of which, the pipe flange and the round bolt, have a belt-shaped collar (25, 28), a seal (23, 32) is provided between the and the filter element (1) on the one hand and the and the holder (20, 21) on the other hand, and that in addition to these calibrating guide and holding means for the filter candle, a spring (34) pressing the filter element (1) against all of its seals (23, 24, 32) and/or individual seals itself is provided between the collar (28) of its round bolt (29) and the holder (21). 13. Filter according to claim 12, characterized in that the injector-shaped pipe flange (22) has, from its annular collar (25), a shirt (27) which dips into the filter element (1) and a collar which is raised in the opposite direction from this collar, and that this collar extends through the opening of the holder (20) into the clean room (16). &bull;&bull;It t · (I &bull; · IIIII · I Il
*·· The The · The ·. Il Il ·· Il 14. Filter according to claim 12, characterized in that the round bolt (29), at least on its section between its annular collar (25) and its projecting extension (31), has annular grooves (35), and that this section of each extension dips into bores (33) of the holder (21). 15. Filter according to claim 12, characterized _in that each holder (20, 21) extends approximately from inner wall to inner wall of the filter housing (13), and that a plurality of filter elements (1) are clamped in a spring-loaded manner between two associated holders. 16. Filter according to claim 12, characterized in that the clamping of the respective filter element (1) between its holders (20, 21) is designed to be floating. 17. Filter according to claim 15, characterized in that each filter element (1) is clamped so as to be displaceable at least in the axial direction between its holders (20, 21). 18. Filter according to claim 1, characterized in that its filling material (cover layer 11) is composed of a dispersing mixture of several components, of which 1 part by volume is sodium water glass, 14 parts by volume water, 4 parts by volume kaolin, 2 parts by volume feldspar, 2 parts by volume starch (starch flour) and 0.2 parts by volume sodium diphosphate. 19. Filter according to claim 18, characterized in that after application of the filling material (cover layer 11) to the carrier material having the larger pores (9) &bull; (ti If (Support body 2) these are jointly subjected to a firing process ^ and that during this firing process the volume fractions of water evaporate and the volume fractions of starch are burned out.