DE19708692A1 - Air filter for handling gaseous pollutants - Google Patents

Abstract

A two-stage adsorption filter comprises a first stage containing activated charcoal particles and a second stage, in which charcoal is incorporated, which is a textile weave.

Description

With increasing environmental awareness and knowledge of the effects of pollutants high on both health and manufacturing sensitive electronic building materials, air currents are becoming increasingly common cleaned via adsorption filter. For such filters are important criteria too name: a low pressure drop, a relatively long service life as well as very low breakthroughs of pollutants. The most today The adsorbent used is activated carbon. Because of the very different buttocks Both high boilers and volatile compounds find a suitable one Adsorption site, so that activated carbon is called "girl for everything" that can. The pore system is also dependent on the starting material and the manufacturing process, so that it is adapted to special applications can be.

In order to have a low pressure drop, a high porosity of the Filter material. In order to achieve a high capacity (service life), it is necessary a sufficient amount of activated carbon. To make the breakthrough as low as Keeping it possible requires good adsorption kinetics, but small ones Coal particles requires, in turn, a lower porosity and thus lead to a higher pressure drop.

Today, adsorption filters are offered in which granular adsorbents with particle sizes of approximately 0.2-1.00 mm are applied or incorporated into a highly air-permeable substrate by means of punctiformly applied adhesives or hot-melt adhesive particles. For many applications, they represent a portable compromise between capacity and breakthrough characteristics. Depending on the design, coal quantities of up to 500 g / m ^{2 can be} accommodated. Such materials can also be folded, so that classic particle filters can be added to save space.

Furthermore, there are plate-shaped filters, which basically consist of granular ad sorbents and hot melt adhesive particles are built up. Here too is the part size a compromise between pressure drop and breakthrough characteristics stik.

DE 38 13 563.9 describes a very good compromise. On a high air-permeable three-dimensional carrier framework are made with an adhesive granular or spherical, on average 0.4, -0.8 mm large adsorbents fixed, the amount of which can be up to 300 g / l. The pressure drop is approx. 10 × low lower than with an equivalent filling.

With all filter materials described, however, there is always an - if even small - breakthrough. It is apparently not possible every 3 kri series, namely capacity, pressure drop and the lowest possible breakthrough, optimize at the same time. To further reduce the amount that breaks through ren was the aim of the present invention.

The solution according to the invention is that the filter in two areas is divided: a first area that absorbs up to 99% of the pollutants and has a high capacity with low pressure loss, and a second Area of low capacity but with high adsorption kinetics to the last To filter out residues.

For the first area, all of the filter designs already mentioned are suitable. Granular or spherical adsorbents with particle sizes of 0.2 mm to 3 mm, preferably 0.3 mm-1 mm, are ideally suited to accommodate a large mass with a low pressure drop. If the adsorbent is activated carbon, one with an inner surface of 900-1500 m ² / g, a pore volume of 0.5-1.0 cm ³ / g in a macro, meso and. Micropore distribution of approx. 1: 1: 1 to 1: 1: 2 and with an average micropore diameter of 8-10 Å are preferred. With good kinetics, good adsorption of high and normal boilers is also guaranteed here.

For the second area are adsorbents with high affinity for volatile Use substances. Textile surfaces have proven particularly successful made of activated carbon. These have an enormous outer surface (where yes the adsorption begins) and essentially the best of narrow micropores pore system, are therefore ideally suited to difficult to adsorb Absorb substances. The textile activated carbon fabric - a fleece, knitted fabric or fabric - can be combined directly with the filter of the first area the or be designed as a cover or "packaging" of the "coarse filter".

Measurements have shown that the initial breakthrough of a filter (i.e. the Performance of the new filter) by at least a power of ten can do what makes the invention particularly valuable for clean room filters.

example 1

A filter block consisting of a reticulated PU foam with 18 PPI and loaded with a spherical carbon of approximately 0.6 mm in diameter in an amount of 220 g / l foam and a thickness of 42 mm was exposed to air at 20 ° C. which contained 100 ppm tolnol and 76 ppm butane, at a speed of 0.6 m per second. An initial breakthrough of 0.04 ppm toluene and 0.6 ppm butane was recorded. The filter block was then covered with an activated carbon fleece (40 g / m ² ) on the back and the measurement was repeated. Tolnol was now no longer detectable on the clean gas side and the butane breakthrough dropped to 0.05 ppm.

Example 2

A layer consisting of 90% carbon with a particle size of 0.3-0.8 mm and 10% hot-melt adhesive particles (approx. 0.05-0.) Was placed on a PP fleece, which is used to manufacture particle filters for crane vehicle cabins , 1 mm in size) applied with a doctor device. The mixture was moistened to prevent segregation. Then a light covering (PE knitted fabric, 50 g / m ² ) was applied and everything was consolidated on a laminating press to form a laminate. The coal coating was 270 g / m ² . This "combination filter", which contained 400 g activated carbon / m ² , was measured as in Example 1. The initial breakthrough was 1.8 ppm toluene and 5 ppm butane. The same activated carbon fleece as in Example 1 was then laminated onto the back using a hot-melt adhesive web (13 g / m ² ) and the filter was measured again. The initial breakthrough dropped to 0.1 ppm toluene and 0.2 ppm butane.

Example 3

A slightly grooved roller (∅ 10 cm) with its own drive was installed across the nonwoven web of Example 2 transversely to the web so that a gap of 2 mm was present between the roller and the nonwoven. The peripheral speed was 8 mm / min, that of the nonwoven web 10 m / min. In front of the roller was a mixture of granular coal with a particle size of 0.3-0.8 mm and rarely melt fibers (PE) or bicomponent fibers (PE / PP) each in lengths of 0.2-1 mm, with emphasis by 0.6 mm, in an amount of 25% based on coal. Separation was avoided by the rotation of the roller. Behind the roller, the fleece was covered with an even layer of activated carbon and melt fibers. The layer had a height of approx. 1.5 mm and was slightly consolidated with an IR radiator. The coal coating was 380 g / m ² . An active carbon fleece (40 g / m ² ) was then laminated on as in Example 2. The measurement carried out as in the previous examples showed an initial breakthrough of <0.05 ppm tol nol and approx. 0.1 ppm butane.

Example 4

A surface filter manufactured according to DE 33 04 349 C2 - point-shaped Be print a particle filter with an adhesive on which granular adsorbents tien are stuck with an activated carbon fleece, which with Laminated onto the adsorbents with the help of a light web of hot melt adhesive was upgraded. A combi-pleated filter was also made from this material drawn adsorptive properties.

Example 5

The same activated carbon fleece of the preceding examples was printed in spots with a thickened styrene-butadiene latex (wet application approx. 60 g / m ² ), sprinkled with a spherical activated carbon (average ∅ 0.5 mm) _1, the excess was removed and the material at 150 ° C condensed. The spherical carbon was then covered with a particle filter fleece and the carbon fleece with a light polyester fleece (laminating aid: 13 g / m ² hot-melt adhesive web). This material was also ideally suited for the production of a combination filter.

Example 6

A particle filter was coated as in Example 4 with the help of a dot-printed adhesive with approximately 250 g / m ² spherical carbon. In a similar way, an activated carbon fleece of 40 g / m ^{2 was provided} with a heavy layer of spherical carbon of 200 g. Then the two layers of carbon were sheared together using a 13 g / m ² hot melt adhesive web and the active carbon fleece was covered in the same operation as in Example 2. The amount of spherical coal was approximately 500 g / m ² .

These examples are not to be considered as limitations. The expert can certainly be other combinations, especially combined Particle and adsorption filters. Basically, the Layer of granular adsorbents and then the activated carbon fleece (or Ak active carbon fabric or knitted fabric).

Claims (13)

1. Adsorption filter consisting of a layer of granular or spherical ger adsorbents and behind it a textile activated carbon fabric. 2. Adsorption filter according to claim 1, characterized in that the Adsorbent is activated carbon. 3. Adsorption filter according to claim 1, characterized in that the granular or spherical adsorbent with the help of an adhesive on egg NEN air permeable carrier are applied. 4. Adsorption filter according to one or more of the preceding An sayings, characterized in that the granular or spherical Adsorbents mixed with hot melt adhesive particles that are smaller than that Adsorber grains are applied and thermal with the carrier, however also connected to each other. 5. Adsorption filter according to one or more of the preceding An sayings, characterized in that the granular or spherical Adsorbents as a mixture with chopped melt fibers or bi component fibers is applied and with the carrier, but also un are thermally connected to each other. 6. Adsorption filter according to one or more of the preceding An sayings, characterized in that the carrier for the granular or spherical adsorbents is a particulate filter.   7. Adsorption filter according to one or more of the preceding An sayings, characterized in that the granular or spherical Adsorbents a particle size or diameter of 0.2-3.00 mm, in particular 0.3-1.0 mm. 8. Adsorption filter according to one or more of the preceding An sayings, characterized in that the layer of granular or spherical shaped adsorbents covered with a light knitted fabric or fleece and an activated carbon sheet is laminated onto it. 9. Adsorption filter according to one or more of the preceding An sayings, characterized in that the layer of granular or spherical Abge shaped adsorbents directly with an activated carbon fabric is covered. 10. Adsorption filter according to one or more of the preceding An sayings, characterized in that the activated carbon sheet is laminated with a hot melt adhesive. 11. Adsorption filter according to one or more of the preceding An sayings, characterized in that the activated carbon sheet is stuck with a sprayed adhesive. 12. Adsorption filter according to one or more of the preceding claims, characterized in that the activated carbon sheet is a fleece, knitted fabric or fabric with a weight of 10-200 g / m ² , preferably 20-50 g / m ² . 13. Combination filter with high separation efficiency, consisting of one part kelfilter, a layer of granular or spherical Adsorbents and a cover that at least partially consists of one Activated carbon fabrics exist.