WO2011076188A2 - Method for dry-coating grains, method for producing at least one filter body, filter body produced according to said method, and mixing device for dry-coating grains - Google Patents

Abstract

The invention relates to a method for dry-coating porous or non-porous grains (5) of at least one absorbing material with a binder comprising a plurality of porous polymer particles, wherein the grains (5) are subjected to a mixing process with the polymer particles in a mixing device (6) and mechanical friction heat is produced by the mixing process, wherein the grains (5) are coated with the binder by means of the friction heat produced. The invention further relates to a method for producing at least one filter body from filter grains coated in such a way and to the filter produced therefrom.

Description

 Process for the dry coating of grains, process for the production of at least one filter body as well as filter body produced according to this process and mixing apparatus for dry coating of grains

The invention relates to a method for dry coating of grains according to the preamble of claim 1, a method for producing at least one filter body and according to this method produced filter body according to claims 1 1 and 13 and a mixing device for dry coating of grains according to the features of the preamble of claim 1 5.

From the prior art are a variety of filters for fine filtration of

Liquids and gases and processes for their preparation known. Such filters include, inter alia, filters whose filter body by means of a

Sintering process are made.

Such sintered filters comprise a housing in which a filter body is received. The filter body is made from a loose bed of porous or non-porous grains of absorbent material, especially activated carbon or the like, absorbent materials. The grains of the absorbent material are made by means of a binder in the form of a polymer, preferably polyethylene, which in porous granular form or in porous

Tuber form is present, sintered, in different elasticity ranges. The sintering or the "baking process" of the filter body is usually carried out in different elasticity ranges of the introduced binder and its mixing with the grains of the absorbent material with each other prior to filling the sintering or baking mold and a compression by compressing or shaking the granules in the sintering or . Baking pan.

CONFIRMATION COPY To produce the filter body, the granulate consisting of the loose bed of granules of the absorbent material and the binder is first introduced into a mold and compacted, for example, by exposure to mechanical vibrations or by shaking. This is followed by a heat treatment process, optionally under pressure, preferably below the melting temperature. Through this sintering process is over the porous

Binder particles creates a preferably pointwise connection between the compressed grains of the absorbent material, whereby a solid porous filter body with a filter matrix or space lattice structure is formed. Here, the binder particles or its particle size have a significant influence on the

Pore sizes of the filter body and thus its filter properties.

Disadvantageously, filter bodies produced by known processes do not have a uniform filter structure or filter fineness due to the binder particles used, i. The pore sizes of the filter matrix are different or arise at least partially nests of coarser density in the filter body. A uniform compacting of the granules consisting of the loose bed of grains of the absorbent material and the binder particles by exposure to mechanical vibrations, vibrations or by shaking before the final matrix or space lattice formation of the filter body in the context of the manufacturing process is not guaranteed in the known production process. Becomes

For example, during the manufacturing process, the binder in its shape even slightly changed, by mechanical or thermal engineering

Influences, inevitably different density differences occur in the

Filter body. Also, the binder particles are usually of different sizes, i. do not have a homogeneous structure, so that this already a uniform compression of the granules is extremely difficult or can only be realized by means of a high manufacturing complexity. Furthermore disadvantageous

claimed the binder has a volume fraction of at least 20% of

Filter body, so that, for example, a filter made of activated carbon is a Adsorptionsleistungsverlust ^" of ^" at least ^" 20% ^_ ^ f: Based on this, the present invention seeks to provide a method for dry coating of filter granules and a method for producing at least one filter body for the fine filtration of fluids or gases, which eliminates the disadvantages known from the prior art and in particular the

Production of filter bodies with a given filter unit allows. The object is achieved on the basis of the preamble of claim 1 by its characterizing features. Furthermore, a filter body produced according to the method and a mixing device for dry coating of grains is also an object of the invention.

The essential aspect of the method according to the invention is to be seen in that the grains are subjected to a mixing process with the polymer particles in a mixing device and a mechanical frictional heat is generated by the mixing process, wherein by the frictional heat generated a coating of the grains with the binder. By applying a binder, in particular polymer layer on at least a portion of the intended for the preparation of the filter body porous or non-porous grains in a mechanical mixing process, the sliding property of the surface of the grains is substantially increased, thereby a

simplified and more uniform compacting of the porous grains in the context of the sintering process is possible. This advantageously achieves a high mechanical stability of the filter body with a uniform filter structure with respect to the filter fineness in the entire volume of the filter body. By uniformly mixing and then compacting by means of a predetermined vibrating technique or vibration technique, the porous grains, for example of carbon,

Activated carbon or similar ground, crushed or crushed non-uniform powder or granule particles are processed to form a uniform homogeneous mesh, matrix or space lattice structure. Further advantageously, the uniform compression takes place before the formation of the final matrix / space lattice structure. By intended for heat generation

Reibschmelzverfahren the pores of the porous grains remain open, especially one Closure of the pores, especially macropores of activated carbon particles would render them useless for adsorption purposes.

Further advantageously, a viscoelastic film is produced by means of the generated mechanical frictional heat on the surface of the polymer particles, which leads to a coating of the grains with the binder due to the existing frictional resistance between the grains and the polymer particles. As part of the

The superficial thin viscoelastic "skin" of the polymer particles is thus scraped off in layers by the generated mechanical friction, which in particular enables the inward-acting thermal insulation caused by the porosity of the polymer particles.The excellent sliding properties of the binder are enhanced by the coating on the grains of the absorbent

Transfer materials, which advantageously allows a uniform and reproducible compression behavior in the context of the sintering process.

A further aspect of the method according to the invention can be seen in the fact that a mechanical frictional heat is generated at the metal surfaces of the mixing device which come into contact with the grains and the polymer particles due to the mixing process. Particularly advantageously, therefore, the mechanical frictional heat required for the coating is preferably generated at the mixing blades and the mixing vessel wall, wherein the frictional heat generated is precisely adjustable, through

appropriate choice of the speed of the mixing blade and / or the friction surface flow of the blade surface of the mixing device. The layer thickness is by means of

volume fractional introduction of the binder set in the mixing device.

Advantageously, the mechanical mixing process is carried out until the

Polymer particles in the mixture are almost completely dissolved. As a result, the occurrence of irregularities in the filter structure is effectively avoided.

As binders preferably high molecular weight low-density polyethylene particles are used, wherein the volume fraction of the binder in the mixture of grains and Polymer particles from over 20% to less than 10% is reduced. Thus, the

Pore size of the filter matrix insignificantly influenced. The mixing process is carried out until the polymer particles have a mixing temperature between 160 ° C and 220 ° C.

The polymer particles used for the preparation have a density between 0.45 g / cm 3 and 0.65 g / cm 3, preferably 0.55 g / cm 3 and a porosity between 35% and 65%, preferably 45%.

Further advantageous developments of the invention are the subject of the dependent claims. In addition, advantageous developments, advantages and

Uses of the invention also from the following description of exemplary embodiments and from the figures. In this case, all described and / or illustrated features alone or in any combination are fundamentally the subject matter of the invention, regardless of their combination in the claims or their relationships. Also, the content of the claims becomes one

Part of the description.

The invention will be described in more detail with reference to an embodiment. Show it:

1 shows a section through a filter with a filter body according to the invention, FIG. 2 shows a section through an alternative embodiment of a filter with a filter body according to the invention,

3 shows a section through a mixing device for coating a bulk material of porous grains of an absorbent material with a binder, FIG. 4 shows a cross section through the mixing device according to FIG. 1 along the line

A-A and

5 shows a section along the line BB through a mixing blade according to FIG. 4. FIGS. 1 and 2 show, by way of example, a schematic sectional illustration through a filter 1 for the fine filtration of fluids or gases, which has in each case a housing 2, a filter body 3 and a housing cover 4.

The housing 2 consists for example of a circumferential wall 2.1 and a bottom section 2.2, wherein the circumferential wall 2.1 in the embodiment of Figure 1 at least partially formed fluid and / or gas permeable. The filter body 3 is accommodated in the housing 2 and the housing 2, which is still open at the top, is closed by the housing cover 4. In the embodiment according to FIG. 2, the supply of the fluid or gas to be filtered takes place via at least one

Inlet opening 4 "in the housing cover 4. At least one outlet opening 4 'is provided in the housing cover 4 to the outlet of the filtered gas or fluid.

The filter body 3 is annular in cross-section, for example, and has a central collecting channel 3 'for discharging the filtered fluid or gas via the outlet opening 4' to the outside. For this purpose, the collection channel 3 'runs

For example, along the longitudinal axis LA of the filter. 1

The fluid or gas to be filtered passes over the circumferential wall 2.1,

in particular its fluid- and / or gas-permeable section, or the

Inlet opening 4 "in the filter 1 and is through the filter body 3 via the

Collection channel 3 'and the outlet 4' out of the filter 1 again. It is understood that regardless of the present embodiment, the inventive method for dry coating of grains 5 and for the production of

Filter bodies 3 different shapes and formats can be applied.

According to the inventive method, the filter body 3 is subjected to a sintering process from a bulk material of porous or non-porous grains 5 of an absorbent material, in particular a carbonaceous absorbent material, activated carbon or similar materials, together with a binder consisting of a plurality of porous polymer particles. The bulk material, however, will before the sintering process, at least partially coated with the binder or a polymer layer derived therefrom, according to a method for

Dry coating porous or non-porous grains 5. Here, in a mixing process in a mixing device 6 mechanical frictional heat is generated, which leads to the coating of the porous grains 5 of the absorbent material with the binder.

The grains 5 of the absorbent material, in particular carbon grains or activated carbon grains, for example, have an approximately homogeneous grain size, at least when using grains 5 to a particle size of about 80 // m. When using grains 5 a smaller grain size homogeneity is no longer guaranteed.

To create filter bodies 3 with different filter fineness, it is also possible to use porous or non-porous grains 5 having at least two different particle sizes. In order to obtain as homogeneous a filter structure as possible, the porous or non-porous grains 5 are subjected to a pretreatment prior to the sintering process known per se, and indeed they are coated with a polymer layer by the mechanical mixing process according to the invention in the mixing device 6 set up for this purpose. When using grains 5 with at least two different particle sizes, only one of the two groups of grains is coated. The remaining group of grains 5 is added uncoated. By increasing or reducing the fine grain content, the filter fineness of the filter body 3 is adjustable.

By at least partially coating the surface of the grains 5 with a polymer layer, the sliding properties of the porous grains 5 of the absorbent material are increased, without thereby closing the pores, in particular macropores of the absorbent material, i. the

Absorption properties of the grains 5 remain unchanged. Due to the now sliding surface of the coated grains 5 is a much higher and More uniform compaction of the grains 5 in the sintering mold in the context of the sintering process I like. Due to the uniform compaction of the grains 5 before the final formation of the fi lter matrix or its space lattice structure, the fineness and uniformity of the fi lter body 3 over the entire volume is substantially improved.

In addition, if the volume fraction of the binder in the mixture is at least partly removed by the "attrition," I precipitate, the weight proportion of the total amount of the mixture remaining the same.Preferably, the binder of porous polymer particles becomes almost completely soluble during the mixing process

used up and is thus already present on the surface of the porous grains 5 of the absorbent material in the form of the polymer layer, so that after the compacting by supplying heat, a direct connection between the respective adjacent grains 5 manufacturable ler, without still isolated in the compacted bulk material Polymer particles are present, which can interfere with the uniformity of fi ltermatrix. By the method according to the invention are fi lter body 3 with a fineness of 0, 1 μνη up to 5 // m manufacturable, and that liegt here the volume fraction of the binder compared to the total volume of the bulk material in the context of Trockenbeschichtung process after coating 1 0%, so that in addition to the prior art, an improvement in the adsorption performance of the filter body 3 is present.

To coat the surface of the porous grains of the absorbent material purely mechanical friction forces are used, which by the mechanical

Blending process for dry coating are produced. The density of the porous polymer particles is, for example, between 0.45 g / cm ³ and 0.65 g / cm ³ , preferably 0.55 g / cm ³ . The porosity of the polymer particles is between 35% and 65%, preferably 45%. Advantageously, the dry coating process is carried out in a temperature range between 1 60 ° C and 220 ° C. The heat present on the respective surface of the porous polymer particles causes a change in the surface strength of the outer layer of the porous polymer particle, namely, this becomes viscoelastic. As a result, abrasion of the outer layer of the porous polymer particles by the grains 5 of the absorbent material is possible, which thus in the context of the mixing process with the

be coated molten polymer. Here, the outer layer of the porous polymer particles is preferably in a vorviskoseelastischen

Transition area.

According to the invention, the porous polymer particles are exposed to the effects of mixed friction until the particle size of the porous polymer particles, preferably of particles of high molecular weight low-density polyethylene, is reduced such that the filter fineness is no longer influenced thereby. Thus, a thin viscous-elastic outer layer of the porous polymer particles is "scraped off" by friction by the described friction / melting process.

The coated with the binder, preferably high molecular weight low-density polyethylene, grains 5 are introduced after their coating in the form of bulk material in a sintered mold and compacted by mechanical vibrations or vibration in a vibrating process until the optimum and / or maximum bulk density is reached. The filter fineness can be determined by the use

additional porous, uncoated grains of different grain size can be adjusted individually. The sintered shape corresponds to the later form of the filter body 3.

Subsequently, the compacted coated porous grains 5 and added uncoated porous grains are sintered in the sintering mold, preferably in the just-viscous-elastic range, by light pressure for positional stability or by pressure in a pre-viscous-elastic range. The filter body 3 has due to the inventive coating of the porous grains 5 in comparison to the known from the prior art mixture with the porous polymer particles on a more stable body structure, ie, the porous grains 5 are connected only at the mutual contact points surface, preferably slightly elastic. This results in the advantageous evenly

Filter structure.

FIG. 3 shows, by way of example, a schematic section through a mixing device 6 for the coating according to the invention of the porous grains 5 of an absorbent material with the porous polymer particles.

The mixing device 6 consists of a closed mixing container 7, which has at least one filling opening 8 and one outlet opening 9, which are preferably provided at the opposite, front-side ends 7 ', 7 "of the mixing container 7.

A mixing blade 10, which is rotatably arranged about the longitudinal axis LB of the mixing container 7 and which preferably has a plurality of mixing blades 10.1, 10.2, 10.3, is mounted at the two opposite, end-side ends 7 ', 7 "of the mixing container 7. FIG Line AA through the mixing device 6 and in Figure 5 shows a section along the line BB through the mixing blade 10.3.

The mixing blades 10.1, 10.2, 10.3 are on a common blade shaft 10 'driven, wherein the blade shaft 10', for example, along the longitudinal axis LB of the mixing container 7 and is guided by the front ends of the mixing container 7 to the outside. The mixing blades 10.1, 10.2, 10.3 are preferably formed spirally and / or blade-like and are along the blade shaft 10 'offset from each other, and preferably by about 45 °. Preferably, the mixing blades 10.1, 10.2, 10.3 each have the same size and the same structure. For rotatably supporting the blade shaft 10 'in the front ends 7', 7 "of the mixing container 7 each one concentric with the longitudinal axis LB of the mixing container 7 arranged bearing assembly 1 1, 1 1 'is provided consisting of a plurality of ball bearings.

The mixing blade 9 is driven off, for example, via an external motor unit 12 about the longitudinal axis LB of the mixing container 7. In this case, the rotational speed is selected such that an optimal mechanical coating required for the coating

Frictional effect arises. As a result, the mixture received in the mixing container 7 of the porous grains 5, preferably carbon grains or activated carbon grains and the porous polymer particles is intensively stirred or mixed.

By the abrasive grains 5, in particular carbon grains or activated carbon grains is in the context of the mixing process at the passing with the grains 5 and the polymer particles in contact metal surfaces of the mixing device 6, in particular the inner walls of the mixing vessel 7 and the mixing blades 10.1, 10.2, 10.3 a mechanical

Friction heat generated with a friction temperature of more than 100 ° C. The mixing process is continued until a mixing temperature between 160 ° C and 220 ° C in the mixing container 7 is present. The mixture is carried out until all

Polymer particles are dissolved in the mixture and thus a coating of the grains 5, in particular activated carbon grains is achieved with the viscoelastic film of polymer.

The invention has been described above by means of exemplary embodiments. It is understood that numerous changes and modifications are possible without thereby departing from the inventive concept underlying the invention. For example, features, in particular partial features of individual

Embodiments or examples may be combined with features or sub-features of other embodiments or examples. LIST OF REFERENCE NUMBERS

filter

 casing

 .1 wall

 .2 floor section

 filter body

 'Collecting channel

 housing cover

 'Outlet opening

 "Inlet opening

 porous grains

 mixing device

 7 mixing tanks

 7 ', 7 "free, frontal ends

 fill opening

 9 outlet opening

 10 mixing blades

 10 'mixing shaft

 10.1 mixing blade

 10.2 mixing blade

 10.3 mixing blade

 1 1, 1 1 'bearing arrangement

 12 motor unit

LA longitudinal axis

 LB longitudinal axis

Claims

claims 1 . Process for the dry coating of porous or non-porous grains (5) of at least one absorbent material with a binder consisting of a multiplicity of porous polymer particles, characterized in that the grains (5) interact with the polymer particles in a mixing device (6)  Be subjected to mixing process and a mechanical frictional heat is generated by the mixing process, whereby by the generated frictional heat, a coating of the grains (5) takes place with the binder. 2. The method according to claim 1, characterized in that by means of the generated mechanical frictional heat on the surface of the polymer particles, a tough elastic film is formed, due to the existing frictional resistance between the grains (5) and the polymer particles to a coating of the grains (5) with the Binder leads. 3. The method according to claim 1 or 2, characterized in that at the with the grains (5) and the polymer particles due to the mixing process in contact passing metal surfaces of the mixing device (6) a mechanical frictional heat is generated. 4. The method according to any one of claims 1 to 3, characterized in that the coating of the grains (5) with the molten polymer takes place such that the pores, in particular macropores of the grains (5) are still open. 5. The method according to any one of claims 1 to 4, characterized in that the mixing process carried out until the polymer particles are almost completely dissolved in the mixture. 6. The method according to any one of claims 1 to 5, characterized in that are used as binders particles of preferably high molecular weight low density polyethylene. 7. The method according to any one of claims 1 or 6, characterized in that the mixing process is carried out until the polymer particles have a  Have mixing temperature between 160 ° C and 220 ° C. 8. The method according to any one of claims 1 to 8, characterized in that Polymer particles are used with a density between 0.45 g / cm ³ and 0.65 g / cm ³ . 9. The method according to any one of claims 1 to 10, characterized in that polymer particles having a porosity between 35% and 65%, preferably 45% are used. 10. The method according to any one of claims 1 to 10, characterized in that the volume fraction of the binder is reduced to the mixture by the mixing process of over 20% to less than 10%. 1 1. Method for producing at least one filter body (3) for fine filtration of fluids or gases, in which bulk material consists of porous or non-porous grains (5) of at least one absorbent material, in particular activated carbon or similar materials, together with a binder consisting of a multiplicity of porous polymer particles subjected to a sintering process, characterized in that at least a part of the grains (5) before the Sintering process with the binder are at least partially coated, by means of a method for dry coating according to any one of the preceding claims. 12. The method according to claim 1 1, characterized in that the with  Binder-coated grains (5) are optionally evenly compressed in a sintering mold with further uncoated grains, preferably by means of a shaking method. 1 3. filter body for the fine filtration of fluids or gases characterized by its production by a method according to claim 1 1 or 12th 14. Filter body according to claim 1 3, characterized in that the filter fineness is between 0.1 / vm up to 5 // m. 1 5. Mixing device for dry coating of porous or non-porous  Granules (5) of an absorbent material comprising a binder consisting of a multiplicity of porous polymer particles, characterized by a closed mixing container (7), an inlet opening (8), an outlet opening (9) and a mixing blade (10), which by means of at least one bearing arrangement ( 1 1, 1 1 ') rotatable about the longitudinal axis (LB) of the mixing container (7) in the frontal free ends (7', 7 ") of the mixing container (7) is mounted, wherein the mixing blade (9) for generating a mechanical frictional heat at least on the container walls a plurality of mixing blades (10.1, 10.2, 10.3) which are arranged one behind the other along the longitudinal axis (LB) of the mixing container (7). 16. Mixing device according to claim 1 5, characterized in that the  Blade blades (10.1, 10.2, 10.3) via a blade shaft (9.2) can be driven from the outside. 1 7. A mixing device according to claim 15 or 16, characterized in that the mixing blades (10.1, 10.2, 10.3) about the longitudinal and rotational axis (LB) offset from one another. 18. Mixing device according to one of claims 15 or 17, characterized in that mixing blades (10.1, 10.2, 10.3) are formed in a spiral and / or blade-like manner.