DE19505174A1 - Adsorption filter used to purify air streams - Google Patents

Abstract

Adsorption filter consists of air-tight carrier material charged with adsorbents parallel to carrier layer. The novelty is that the filter contains at least 250, pref. at least 300g absorbents per litre. The ratio pressure loss (Pa) (at 1 m/s) to butane capacity (at 76 ppm and 62 cm/s, 23 deg C and 35% rF) is less than 10.

Description

An important application of adsorption filters is the cleaning of air flows men who are directed into interiors. In addition to particles with particle filters are removed, the air contains a number of pollutants in low Concentrations in the ppm and ppb range. Among these are those which are difficult to adsorb due to their volatility. Here you help partly with impregnation (chemisorption), partly with very narrow micropo Ren in which the adsorption is particularly pronounced. Narrow micropores in the Å For example, the range is low for sorption in road traffic Concentrations of benzene occurring are absolutely necessary. It's over Lich, the micropores by the dynamic butane capacity, for example ge measure at a concentration of 76 ppm, a flow rate of 62 cm / s, a temperature of 23 ° C and a relative humidity of 35 % to characterize. Butane is a gas that is difficult to adsorb point - 0.5 ° C). The dynamic butane capacity is therefore a measure of the color Ability to adsorb volatiles, especially volatile hydrocarbons beers and is therefore a quality feature of the filter.

Another characteristic of the quality of a filter is the pressure drop, more common measured wise at 1 m / s. A high butane capacity requires a considerable amount che mass of adsorbents that, in order not to over-permeability to air reduce, not be too compact. Well proven has the principle of "fixed expanded bed" (EP 340 542), where Adsorben are fixed to a three-dimensional support structure: the intermediate space me between the particles guarantee high air permeability, while the Brownian molecular motion nonetheless turned into an excellent one Degree of separation leads. The pressure loss / butane capacity ratio is the half an important criterion for filter quality.

The aim of the present invention was to find new filter designs where there is a favorable ratio of air permeability to butane capacity , the following guideline was aimed for:

The German patent application DE 40 20 427 A describes a filter because characterized in that a strip-shaped, air-impermeable material coated on one side with adsorbents and to a disk or a cuboid is wound up. Preferably, the one not covered with adsorbents Side with a pressure sensitive or hot melt adhesive and the filter glued to a solid block that can be cut into slices. The Adsorber particles serve as spacers between the carrier webs. The The filter is placed parallel to the air-impermeable, coated with adsorbents flowed through elements. It is therefore clear that the air resistance in primarily from the adsorbents serving as spacers, in particular depends on their quantity, size and shape and thus fluctuations in their Dimension for fluctuations in the air passage that are not always controllable must lead. On the other hand, one-sided loading leads to one not optimal ratio of weight of adsorbents / total weight. This one simple and easy to manufacture filter construction should be in the light of the new Er knowledge will be improved.

First, an attempt was made to cover the carrier material on both sides with adsorbents loaded. This is best done by squeezing (gusset) the straps sheet with a highly viscous adhesive and sprinkled on both sides with adsor benzien. So-called "high solids" PU coatings are used as adhesives from Bayer has proven itself well because it has a high initial tack as well as Cure through a minimum viscosity, which leads to a high Haf  tion of the particles on the carrier and the formation of "support bases", the latter increasing the accessibility of the adsorber particles. The Other suitable adhesive compositions are available to a person skilled in the art, so that the mentioned high solids should not be regarded as a limitation.

So that the air permeability does not depend solely on the adsor depends on benzene, it is advantageous to emboss the carrier web. If the detention mass, as suggested, is applied with squeeze rollers, must be on it be made sure that the embossing "stands up" again after being squeezed. This is the case, for example, with embossed PES or PA knitwear or nonwovens made of the same material: the embossing, e.g. B. a knob embossing, is pressed flat, but comes out again after a few moments. The embossing preferably has a height of 2 to at most 5 medium Particle diameters with a width of one to four times the height. Of the There are basically no limits to the shape of the embossing. In addition to the nop Zigzag embossing is also an option.

If the adsorbents themselves act as spacers between the layers they should not be less than a certain size. So are at for example, particle sizes from 0.3 to a few mm are suitable. It applies here the same as for the bed: the smaller the particles, the better the Ki netik, but also the higher the pressure loss in the filter. One way that Keeping pressure loss within limits despite small particles is that Apply adhesive mass in spots so that the adsorbents do not cover the entire surface, but are in piles and there are free passages between them ren. The Brownian movements ensure that it is still an ad sorption is coming.  

The carrier webs covered with adsorbents must then go to Fil terelements are processed. As in DE 40 20 427, this can be done A1 was stimulated to happen by winding around a core, each Round, oval or rectangular filter discs are produced on request can be.

Another possibility is that the path carrying the adsorbents in parallel Layering layers. All embodiments have in common that the filtering element parallel to the carrier layer and not through the carrier layer is flowed through.

The following examples are intended to show in what way the desired Quality criterion has been reached. In all of the examples, fine-pored were active coal (grain coal and spherical coal) with a butane capacity (76 ppm, 62 cm / s, 23 ° C) of 40-60 g / kg. The grain coal was made of coconut made of shells and had an inner surface of approx. 1,100 m² / g. The Ball coals had surfaces of around 1,000 m² / g and pitches and polymers as a starting product. A description of spherical carbons can be found at for example in the German patent specification P 29 32 571 and the US patent font 4957897.

Other adsorbents, e.g. B. moisture-insensitive molecular sieves, various impregnated activated carbons etc. for use as required come, so that the examples themselves are not viewed as a limitation that may.

example 1

An approximately 110 g / m² heavy polyester knit was with a 1.5 mm high Provide embossing. The roughly hemispherical knobs had one Diameter of 3 mm. The roller temperature was 180 ° C. The embossed  The web was then made with a mixture of 100 parts of Impranil HS 62 and 6.2 parts of Imprafix HSC squeezed. Squeezing effect approx. 100%. The tacky adhesive and thus sealed The carrier web was covered with grain coal - average particle size 1.1 mm - on both sides sprinkled and condensed the adhesive. The 40 cm wide product was in 5 cm wide and 20 cm long strips cut into a stack of 15 cm height were piled up. The stack consisted of 50 layers, each of which de contained about 8.8 g of activated carbon. The stack was on the 5 cm long edges welded (hot melt adhesive) and pressed into a frame. The stack was flows parallel to the layers. The pressure loss was 1 m / s 240 Pa. The dynamic butane capacity (76 ppm, 62 cm / s, 23 ° C and 35% RH) was 26.4 g.

Example 2

A 90 g polyester fleece was made with the same knob embossing as in Example 1 and squeezed with the same adhesive. Squeeze effect about 100%. The sticky nonwoven web was then covered with a spherical carbon sprinkled with an average diameter of 0.55 mm on both sides. The coal print run was 510 g / m². Strips of 5 × 20 cm were produced, which too a 15 cm high stack were stacked, which then ent 73 layers held. The amount of coal in the package was 375 g. The stack was like in the case game 1 flows parallel to the views. The dynamic butane capacity (76 ppm, 62 cm / s, 23 ° C and 35% RH) was 23 g, the pressure drop (1 m / s) 170 Pa.

Example 3

A paper web was covered with a 6 mesh stencil with the adhesive of the Example 1 printed in dots (50 g / m²). The hemispherical Pile of glue was sprinkled with the same grain coal as in Example 1 and the material was condensed out. There was a coal edition of  220 g / m² achieved. Then part of the web was turned over and on one soft pad on the back also printed with glue and with Coal sprinkled. The coal coating totaled 430 g / m². The one-sided printed web had a thickness of 1.6 mm, the one printed on both sides those of 3 mm. As in Example 1, a stack of 92 and 49 strips, respectively manufactured. The filter contained 215 g activated carbon in the first case and in the second 211 g. The pressure loss at 1 m / s was 180 Pa or 130 Pa. For the butane capacity (76 ppm, 62 cm / s, 23 ° C and 35% r.h.) 13 g were found the.

Example 4

The same paper as in Example 3 was covered on both sides with the same Chen adhesive mass applied as in Example 1 and sprinkled with spherical carbon. 90% of the balls had a diameter of approx. 0.55 mm and 10% a diameter of approx. 1.2 mm. Separation has been carefully avoided avoided. After the adhesive was condensed out, the web became 5 × 20 cm cut large strips, each containing 4.9 g of coal. 88 strips were piled up in a pile. The stack contained 430 g of carbon balls chen. The butane capacity (76 ppm, 62 cm / s, 23 ° C and 35% RH) was to 25 g at a pressure drop of 210 Pa (1 m / s).

Example 5

Adhesive was applied to both sides of a paper web as in the example and sprinkled with spherical carbon (⌀ 0.3-0.8 mm). The amount of coal was 490 g / m². The coal-laden material was again cut into strips of 5 × 20 cm cut. On the other hand, a 0.1 mm thick Alufo lie, which had a 1.4 mm high zigzag embossing, strips of 6 × 20 cm punches. A stack was formed as in the other examples, the Aluminum foil served as a spacer between the strips loaded with coal. The layers could be interlocked somewhat by pressure, so that a  15 cm high stack containing 76 layers of activated carbon was obtained Contained 372 g of activated carbon balls. 22 g of butane could be adsorbed, while the pressure drop was 190 Pa at 1 m / s. The good thermal and electrical conductivity of the aluminum intermediate layers enables a uniform Heating, which is both with warm air as well as through passage current can happen. For this purpose, the schma on both sides of the block, protruding film strips on both sides trisch connected and connected to a control transformer. When recording of 150 watts could reach temperatures above 100 ° C within 10 minutes can be achieved. This allows the desorption of many medium-volatile substances zen what, for example, the life of a filter for automotive interiors would increase pregnant. DE 42 25 272 A1 describes a filter in which chem the metallic support structure for the adsorbents are heated can. The adhesive is sometimes overused. In the front example, the aluminum intermediate layers are heated, which with the coal, but do not come into contact with the adhesive.

Claims (8)

1. Adsorption filter, consisting of stacked strips of a preferably airtight, loaded with adsorbent carrier material rials, which are flowed through parallel to the carrier layer, characterized in that the filter contains at least 250 g, preferably at least 300 g of adsorbents per liter, and the ratio pressure loss in Pa, measured at 1 m / s, to butane / capacity, measured at 76 ppm and 62 cm / s, 23 ° C and 35% RH, is less than 10. 2. Adsorption filter according to claim 1, characterized in that the Trä layer has a nub structure, the height of the nubs is at least at least 2 and at most 5 average diameters of the adsorber particles and the base of the knobs (diameter) is one to four times larger than the height is. 3. Adsorption filter according to claim 1, characterized in that the Adsorbents consist of small and large particles, the large less than half, preferably less than a third, of the Total, make up and at least double, more preferred wise three times the diameter of the small particles. 4. Adsorption filter according to claim 1, characterized in that the Adsorbents are arranged in nests. 5. Adsorption filter according to one or more of the preceding claims che, characterized in that the adsorbents activated carbon in the form  of granular coal or spherical coal, agglomerated moisture-resistant Molecular sieves or porous polymers. 6. Adsorption filter according to one or more of the preceding claims che, characterized in that the adsorbents have a particle size of 0.2-10 mm, preferably 0.3-2 mm. 7. Adsorption filter according to one or more of the preceding claims che, characterized in that between the adsorbents bearing Layers, smooth, preferably embossed foils, are stored, which as Spacers serve. 8. Adsorption filter according to claim 7, characterized in that eina foils are made of metal and can be heated electrically.