DE2525660A1 - GAS PURIFICATION DEVICE, IN PARTICULAR FOR CATALYTIC GAS PURIFICATION - Google Patents

Description

Dr- ΗΓ.Γ.3-Α. Browns

8 Munch «] £ 3, heuiiiiauamf. 28

June 9, 1975 74-64

ENGELHARD MINERALS & CHEMICALS CORPORATION 430 Mountain Avenue, Murray Hill, N.J. 07974, V.St.A,

Gas cleaning device, in particular for catalytic gas cleaning

The present invention relates to a catalytic Device which is suitable for cleaning gases, and which in particular for the treatment of exhaust gases from internal combustion engines can be used to reduce pollution of the surrounding atmosphere.

Gases from different sources often enter the Ambient atmosphere and contaminate the atmosphere with undesirable particles. This problem has been going on for

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Years of research and many different types of devices have been proposed to to overcome it, however, prevention of such pollution is becoming more and more urgent.

A particular difficulty is the cleaning of exhaust gases from internal combustion engines like them used in motor vehicles, for example. The exhaust gases from engines, which are usually hydrocarbon fuels, such as hydrocarbon gases, gasoline or diesel fuel cause significant pollution of the atmosphere. Among the impurities present in these exhaust gases there are hydrocarbons and oxygen-containing compounds, the latter being nitrogen oxides and contain carbon monoxide. The removal of these contaminants from the exhaust gases or the conversion of them Contamination in less hazardous substances is of considerable importance for general wellbeing.

U.S. Patent 3,441,381 relates to a catalytic device which has been used to purify various gases, such as exhaust gases, and which have proven to be particularly effective in the treatment of exhaust gases from internal combustion engines has proven which hydrocarbons or others Use fuels. The device has a housing section in which a one-piece catalyst is arranged, which has a number of gas flow channels. At each end of the housing is a Gas inlet or a gas outlet provided. The outside diameter of the catalyst, which is essentially the same The cross-section of the case is slightly smaller

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as the inside dimension of the housing to allow the catalyst to be inserted into the housing after these parts were manufactured separately from each other.

In order to hold the catalytic converter firmly within the housing, an elastic, flexible element is under pressure in the Annular space arranged between the housing and the catalyst. The catalyst usually consists of a refractory one ceramic material, while the housing is made of metal. In a very functional training the arrangement, the elastic flexible element is designed as a corrugated metal element, which is permeable, like a wavy metal knitted fabric.

According to a preferred embodiment of the arrangement according to US Pat. No. 3,441, each end of the catalyst stands in contact with a flange which extends inwardly from the housing. These puddles are on the inner circumference of the Housing arranged, bridge the space between the housing and the catalyst and protrude sufficiently the respective end faces of the catalytic converter to prevent longitudinal movement within the housing to back up. It is also desirable that the flanges prevent the gas being treated from bypassing the catalyst, by closing off each end of the annulus between the catalytic converter and the housing so that the gases are forced to pass through the catalyst as they move from the inlet to the outlet of the assembly stream.

Although the device according to US Pat. No. 3,441,581 is at the cleaning of exhaust gases from internal combustion engines has proven to be excellent, there are cases in which

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the catalytic converter is damaged during operation. the the outlet end face of the catalytic converter is occasionally damaged as a result of abrasive action caused by the catalytic converter rotating or can move in another way within the housing in abutment with its retaining flange. U.S. Patent 3,692,497 Fig. 10 shows a catalytic purification device which includes means for preventing rotation of the catalyst has within a cylindrical housing, creating an abrasive effect with a resultant Damage is prevented or reduced. However, damage can occur from other causes. During the operation of the catalytic cleaning device for the exhaust gases, high operating temperatures occur, which can reach up to 800 ° C and higher, for example. It is well known that many substances expand with increasing temperature the end. Since different materials expand at different rates, the housing and expansion takes place of the catalyst by different amounts. The device according to US Pat. No. 3,441,381 holds a sufficient level Connection between the housing and the catalyst during radial expansion at elevated temperatures upright, but there is a longitudinal expansion also on. This expansion in the longitudinal direction has the effect that the retaining flanges no longer firmly against the end faces of the catalytic converter. There are two undesirable effects. First, some of the exhaust enter the area between the housing and the catalytic converter and is therefore not of the catalytic effect subject. Second, vibration of the catalytic converter can damage the ends of the catalytic converter, which abut the retaining flanges. The US-PS 3> 692

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shows a device for preventing longitudinal movement of the catalytic converter within a cylindrical housing. However, this patent is primarily concerned with passage of the catalyst through the splash at the housing outlet and needs a slight longitudinal movement as a result of vibrations or impacts on the cleaning device not to prevent. Therefore, the teaching of the cited patent is not with certainty a Damage to the end faces of the catalytic converter is prevented, which occurs because these end faces as a result vibrations during operation at high temperatures against the retaining flanges.

The present invention relates to a catalytic gas purification device of the type previously described and includes expandable and / or elastic ceramic Fiber elements to prevent the undesirable consequences that would otherwise result from differences in thermal Expansion of various components of the device and as a result of mechanical shocks that the device during exposed to operation.

According to the present invention is an expandable and / or elastic ceramic fiber element between an end face of the catalytic converter and the associated retaining flange arranged. Preferably, a ceramic fiber element and a retaining flange are next to each end face of the Catalyst provided, although they can only be provided next to one of the two end faces. The ceramic The fiber element is preferably placed under compressive stress between the retaining flange and the adjacent one during installation

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Front side of the catalyst used. Enlarged during operation at higher but fluctuating temperatures the distance between the retaining flange and the face of the catalytic converter as a result of the differences in the thermal expansion of the individual components, with the ceramic Fiber element expands to make contact with the retaining flange and the face of the catalytic converter substantially maintain all operating conditions. In the description that follows, the expandable element will be used sometimes referred to as an elastic element. These ceramic Paser elements are in their shape and The choice of material is designed in such a way that, when it expands, a compensation for the differences in the thermal Thermal expansion between the catalyst and the housing is made possible. Therefore, over the entire operating temperature range the catalytic gas cleaning device maintain a considerable contact pressure of the desired size on the catalyst and thus prevents damage to the catalytic converter that would otherwise result from touching the face of the catalytic converter with the retaining flange in the event of vibration of the gas cleaning device during operation at high Temperatures could occur. In addition, the expandable ceramic fiber elements in conjunction with the prevent Retaining flanges allow the exhaust gases to pass into the space between the catalytic converter and the housing over the entire operating temperature range thereby ensuring that substantially all of the exhaust gases flow through the catalytic converter. the ceramic fiber elements can also be used in cooperation with other elements between the End of the catalyst and the retaining flange are arranged.

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Although the expandable and / or elastic ceramic Pasereleraente according to the invention without an elastic, flexible one Element can be used which surrounds the catalyst within the housing, and further without a Means to allow either a rotational movement or an appreciable longitudinal movement of the catalytic converter within the housing To prevent this, the expandable and / or elastic ceramic fiber elements are also suitable for use with such facilities, which are preferably in the gas cleaning device are provided.

Further features and advantages of the present invention emerge from the following description in conjunction with the drawings. Show it

Figure 1 shows a section through a catalytic according to the invention Gas cleaning device and

Figures 2 and 3 enlarged partial sectional views of the section A-A of Figure 1, which represent preferred embodiments of an elastic element, which according to the invention can be provided in the catalytic gas cleaning device.

The catalytic gas cleaning device 10 shown by way of example in FIG. 1 has a cylindrical central section 12 and frustoconical end sections 14 and 16 on. An inlet conduit 18 is formed integrally with the frustoconical end portion 14, while an outlet conduit 20 is made in one piece with the frustoconical end portion 16. The lines 18 and allow the connection of the catalytic gas cleaning device 10 to an exhaust gas source, for example

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emerges from an internal combustion engine. The exhaust gases can be mixed with oxygen, which for example the exhaust gases before they enter the line 18, is supplied by an air source.

The central portion of the catalytic gas purification device 10 comprises a metal housing 22, which is preferably cylindrical, the diameter in the The order of magnitude is between about 5 and 20 cm, while the length of the housing is in the order of magnitude between about 5 and JO cm. The frustoconical end sections 14 and 16 adjoin the gas inlet and gas outlet ends of the housing 22 and are thus through, for example Welding connected. The end sections can also have a non-circular cross section.

The frustoconical end portion 14 is dimensioned such that that there is a distribution or a passage of the exhaust gases over the entire or substantially the entire cross section sbere I of the inflow part of the housing 22 allows so that the exhaust gases in all or substantially enter all inlet openings 24 of the gas flow channels 26 in the one-piece catalytic converter 28, which within of the housing 22 is arranged and which has a cross section which is slightly smaller than that of the housing 22 is. The inlet openings 24 are distributed over the entire or substantially the entire area of the inlet-side end face 30 of the porous, ceramic-bonded Oxidation catalyst 28.

The frustoconical end portion 16 has similar ab-

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measurements like the frustoconical end section 14 and is therefore designed such that it allows the free exit of the gas from the flow channels 26 through the exit openings 32 on the outlet-side end face 34 of the catalytic converter 28. As a result of such Free gas flow out of the flow channels, the formation of a noticeable back pressure is avoided.

The outer surface 40 of the catalytic converter 28 is preferably provided with a coating 43, for example from Piberfax cement, a fibrous aluminum silicate, is made, which creates the pores on the outer surface of the catalyst are closed and also receive a protective coating will. Between the inner surface 38 of the housing 22 and the outer surface 40 of the catalytic converter 28 is a space 36 of substantially uniform width. This intermediate space 36 extends completely around the catalytic converter 28 over the entire length of the same. In the preferred embodiment of the invention is in the space 36 a resilient, pliable element 42 is provided and under pressure between the inner surface 38 of the housing 22 and the outer surface 40 of the catalytic converter 28. The elastic, flexible element 42 can, for example consist of a corrugated, gas-permeable metal arrangement, such as a corrugated metal mesh, as it is is described in U.S. Patent 3,441,381. An annular retaining flange 44 extends within the housing 22 radially inward, around the gap of the annular space 36 between the inner wall 38 and the edge-side area of the inlet-side To bridge the end face 30 of the catalytic converter 28.

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The retaining flange 44 represents a continuous shut-off around the circumference of the catalytic converter 28 to a flow to prevent the uncleaned exhaust gas into the space 36 »without too large a number of inlet openings 24 block. It is desirable that some inlet ports 24 be blocked in order to allow the elastic Element 42 and the housing 22 to insulate against the heat of reaction of the treated exhaust gases and the heat to be retained in the catalytic converter. In the embodiment shown in the drawings, the annular flange is 44 integral with the frustoconical end section 14 formed and can consist of a thin, short splash, which is essentially a uniform thickness and has radial extension and which is made by the inner end of the frustoconical end portion 14 is bent sufficiently so that the radial annular flange 44 is formed, the plane of which is essentially normal runs to the main axis of the housing. The gap 356 can, for example, have a thickness of the order of magnitude of 3 mm, while the annular flange 44 is can extend inward from the housing by an amount on the order of 6 mm.

A corresponding annular flange 44 extends radially inward from housing 22, around gap 36 on the outlet-side end face 34 of the catalytic converter 28 to bridge. This flange 44 also forms a continuous barrier on the circumference of the catalytic converter 28 to to prevent gas flow through the space 36,

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without the outlet openings 32 of too large a number of To close flow channels 26 in the catalytic converter 28. The annular flange 44 can also be integral with the frustoconical end portion 16 may be formed and can consist of a thin, short flange with a substantially uniform thickness and radial extension, which by bending the inner end of the frustoconical End portion is formed. This output side annular flange 44 extends inwardly from inner surface 38 of the housing a corresponding amount, like the annular end flange 44 on the input side, and its plane is also essentially perpendicular to the housing axis .

The elastic, flexible element 42 has an irregular or ribbed surface on both sides equipped and is preferably corrugated. The element 42 closely surrounds the catalytic converter 28 and stands in contact with the inner surface 38 of the cylindrical housing 22 to absorb mechanical shocks and differences in the thermal expansion of the metallic housing wall and to balance the ceramic carrier of the catalytic converter 28 in the radial direction. Preferably there is the element 42 made of a corrugated metal knitted fabric, which has a considerably greater flexibility and elasticity than for example has a corrugated metal sheet. Preferably, when installing the element 42 in the catalytic Gas cleaning device 10 this subjected to compressive stress. The squeezed, wavy knit ensures a greater number of points of contact with the catalytic converter 28 and therefore results in improved absorption of shocks as well as an improved compensation of the

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Thermal expansion. A device can be provided for a rotational movement of the catalytic converter 28 within of the housing to a minimum, as described, for example, in US Pat. No. 3,692,497 is.

A substantially annular, expandable and / or elastic ceramic fiber element 48 is arranged between the inlet-side flange 44 and the inlet end J> Q of the catalytic converter 28. A second expandable and / or elastic ceramic fiber element 48 lies between the outlet-side flange 44 and the outlet-side end of the catalytic converter 28. The elements 48 compensate for differences in thermal expansion in the longitudinal direction between the metallic housing 22 and the ceramic carrier of the catalytic converter. In addition, the ceramic fiber elements 48 absorb shocks, particularly during the operation of the catalytic gas cleaning device 10 at high temperatures. The flanges 44 according to FIG. 1 preferably extend from the inner surface 38 slightly further radially inward than the ceramic fiber elements 48, in order to allow untreated exhaust gases to pass through the expandable elements and thus through the annular space 36 between the housing 22 and the catalytic converter 28 to prevent.

FIG. 2 shows a ceramic fiber element 48 which has a first cup-shaped section 48a as well as has a second cup-shaped portion 48b. The sections 48a and 48b preferably each consist of a ceramic fiber material. Since this material is proportionate is impermeable to untreated exhaust gases,

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The sections 48a and 48b block the passage of these gases through the intermediate space 36, so that essentially all of the untreated exhaust gases flow through the catalytic converter 28. According to FIG. 2, the cross sections of the sections 48a and 48b are L-shaped. The sections 48a and 48b can protrude about 6 mm from the housing 22 in the radial direction of the L next to the flange 44 inward. The total thickness of this area of the L-section of both sections 48a and 48b between flange 44 and inlet-side end face 30 of catalytic converter 28 can be approximately 2.5 ram. The ceramic fiber material of sections 48a and 48b can consist of an aluminum oxide-silicon dioxide fiber material, such as a Thermotec ceramic fiber board.

According to an advantageous embodiment of the invention the second or inner cup-shaped element 48b is sufficiently soft or elastic to adhere to unevenness of the adjacent end face of the catalytic converter 28 or its coating 43 to adapt to an effective seal to ensure against gas penetration. The outer cup-shaped element 48a can be relatively solid or be designed to be less elastic than the element 48b in order to ensure a reliable axial gripping of the catalytic converter and the exertion of a relatively large axial or longitudinal force against the catalytic converter to enable. The inner element 48b can be more elastic than the outer element 48a, for example at least twice as elastic to produce the desired sealing and holding effect. For example, element 48b can only be about half as stiff as element 48a.

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In order to further improve the capture of the catalytic converter 28, the element 42 can optionally have a greater length have than the catalytic converter 28, so that when assembling according to FIG. 1, the element 42 is slightly in the longitudinal direction is compressed, with it on the expandable element 48 either directly according to Figure 2 or against an intermediate piece is applied.

Although Figure 1 is a preferred embodiment of the Illustrates the invention in which a retaining flange 44 and an expandable ceramic fiber element 48 are both at the inlet end as well as at the outlet end of the catalyst 28 are provided, a satisfactory catalytic gas purification device can be obtained achieve which only with a single flange and a single expandable ceramic fiber element provided that the single expandable ceramic fiber element has sufficient elasticity has to hold the catalyst 28 in place at elevated operating temperatures. If a single flange and a single ceramic fiber element are used, they are preferably adjacent the gas outlet end 34 of the catalyst 28 arranged, since the gas flow through the catalyst tends to move the same in this To cause direction and the ceramic fiber element acts as a damping element.

FIG. 3 shows a 'modified embodiment' according to which the frustoconical end section 14 opens into an annular flange 44a, which extends radially outwards towards the inner surface 38 of the housing 22 extends, is in contact with the ceramic fiber element 48 and then in the longitudinal direction outwards with the formation of an edge

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Section 14a extends, which rests against the housing 22. Thus, the flange 44a extends radially from the housing 22 towards the inside, as also applies to the flange 44 of FIG.

The cleaning device according to the invention can, apart from the oxidation catalyst 28, which is designed as a one-piece, refractory element, consist of ferrous or non-ferrous metals, which are suitable for the high temperatures that occur during operation, for example up to 800 ° C and higher . The oxidation catalytic converter 28 applied to a carrier can consist of a one-piece, rigid carrier structure, with cordierite, for example, being used as the carrier. The channels 2.6 can have a cross section which is, for example, trapezoidal, rectangular or hexagonal and are formed by corrugations and essentially horizontal layers of the carrier arrangement. An activated, refractory metal oxide, for example an aluminum oxide from the gamma family or of the activated type, can be provided on the surface of the gas flow channels 26. The metallic component of the oxidation catalyst can be carried on the active refractory metal oxide. For example, the metal catalytic component may include a platinum group metal, a base metal, or combinations thereof attached to the active refractory metal oxide. As an alternative to this, the catalytic metal can also be applied directly to the carrier surfaces.

The one-piece, skeletal support for the oxidation catalyst used in connection with the present invention is used is characterized by a large number of flow channels which extend through the carrier extend. The applied catalyst is in the cleaning

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device applied in such a way that the one-piece support skeleton the main part of the cross-sectional area of the Reaction zone occupies, there being a narrow space between the support and the wall of the cleaning device is. The one-piece support skeleton is preferably shaped in such a way that it enters the reaction zone of the housing of the cleaning device fits, and the catalyst applied to the one-piece support is related in the longitudinal direction attached to the cellular gas flow channels, d. that is, the flow channels generally extend Direction of gas flow, so that the gases pass through the cleaning device during their passage Flow channels for Hessen. The flow channels need each other not to extend in a straight line through the catalyst arrangement, but can have deflection arrangements.

The skeletal support assembly preferably consists of a substantially chemically and relatively catalytically inert rigid Pestkörpermaterial which its shape and strength at high temperatures, for example up zu'etwa 1100 ⁰ C and more, maintains. The carrier expediently has a low coefficient of thermal expansion, good resistance to thermal shock conditions and low thermal conductivity. The carrier can be metallic or ceramic or consist of a combination arrangement

exist. Although the carrier is made of glass ceramic can, it is preferably unglazed and can be formed substantially completely crystalline, the absence a noticeable proportion of a vitreous or amorphous matrix, such as that found in porcelain materials is present, matters. Furthermore, the skeletal support can have considerable available porosity

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in contrast to the essentially non-porous porcelain which is used for electrical applications, for example for the production of spark plugs, is used and which by a relatively low available Porosity is characterized. While the outer surface area such arrangements is in the order of magnitude of 0.001 to 0.01 m / g, the flow channels are included, the entire surface is preferably several times larger, so that a large part of the catalytic reaction can take place in the larger pores.

Including the geometric surface area of the carrier of the walls of the gas flow channels is often about 0.5 to 6 and preferably 1 to 2.5 m per diameter of the support. The channels which extend through the one-piece body or the skeletal arrangement can have any shape and have a size that is compatible with the desired geometric surface and should be large enough to allow the gas mixture of exhaust gas and oxygen-containing gas to freely pass through. The channels may run parallel or substantially parallel and extend through the carrier from an inner side thereof on the other hand, wherein the channels are preferably separated from one another by thin walls. The channels can also have many different directions and even communicate with one or more of the adjacent channels. The inlet openings of the channels can be distributed essentially over the entire end face or cross section of the carrier be which has the first contact with the gas to be purified. A preferred skeletal arrangement consists of one

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or more of the following substances, namely cordierite, codierite alpha aluminum oxide, Zircon-mullite, spodumene, alumina-silica-magnesia, being in place the preferred materials for the carrier are sillimanite, magnesium silicate, zircon, petalite, alpha aluminum oxide and aluminosilicates are possible *

The gas flow channels of the catalytic converter, which is a one-piece Has skeletal ceramic carrier can have thin walls which have a relatively large surface area. The channels can have a certain cross-sectional shape or have multiple cross-sectional shapes from a variety of cross-sectional shapes and sizes. the Channels can, for example, have a trapezoidal, rectangular, have square, sinusoidal or circular cross-section, so that the cross-sections of the carrier is arranged in a uniform pattern, which can be referred to as a honeycomb, wave or grid pattern. The walls of the cellular channels are generally of a thickness that is sufficient to achieve a one-piece body high strength is required, with the wall thickness mostly in the range between 0.05 and 0.25 mm (2 to 10 mils) lies. With this wall thickness, the arrangement can have approximately 16 to 400 or more gas inlet openings for the flow channels

per cm and a corresponding number of gas flow channels, preferably about 24 to 80 gas inlets

and flow channels per cm. The open area of the cross-section can be greater than 60 # of the total cross-section. The size and dimensions of the one-piece skeletal refractory support according to the invention can vary widely Boundaries are changed.

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In the preferred embodiment of the catalyst the refractory metal oxide is on the one-piece skeletal support as continuous or discontinuous thin deposit is applied, preferably about 0.001 to 0.025 mm (0.0004 mm thick) up to 0.001 inch). Such a catalytically active oxide can be a calcined, refractory metal oxide be, which has a porous structure and a relatively has a large internal pore volume and a large total surface area. Generally amounts to the total surface area of the active refractory metal oxide at least about 25 m / g. Such oxides can be obtained by separating the water from the hydrate of the oxide by calcining at temperatures usually from about 150 ° C to 800 ° C. The preferred active metal oxides include Elements made of aluminum oxide from the gamma family or of the activated type, which, for example, by precipitation a water-containing aluminum oxide gel and then drying and calcining to remove the water of hydration to form the active alumina.

When the arrangement is in operation, the exhaust gases come from an internal combustion engine, for example one with a spark plug and reciprocating pistons working internal combustion engine a motor vehicle or forklift truck, which are combustible, air pollutants such as hydrocarbons, oxidized hydrocarbons and carbon monoxide contained, at high speed from the exhaust of the machine and are mixed with an amount of oxygen, which is necessary for the combustion of the combustible components, preferably with an oxygen content,

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which exceeds the stoichiometric amount required for combustion. The oxygen can be present in the exhaust gases as a result of the combustion of a lean fuel mixture, or oxygen can be supplied to the exhaust gases, for example in the form of air. The oxygen-containing exhaust gases enter the inlet 18 of the catalytic gas cleaning device 10 at an elevated temperature and flow through a multiplicity of flow channels 26 which extend through the oxidation catalytic converter 28. The gaseous mixture comes into contact with the active catalyst component within the macropores of the porous applied catalyst and on the surface of the flow channels 26, the temperature of the applied catalyst usually being between 150 ^° C. and 700 ^° C., so that the combustible, air-polluting Fractions in less harmful gases, such as COp and HpO, are oxidized. The gases cleaned in this way then pass from the gas cleaning device 10 via the outlet line 20 either directly into the atmosphere or into a connection line from which they exit into the atmosphere. During this process, the catalytic converter element is held stationary within the housing 22.

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Claims (1)

74-64 June 9, 1975 Claims 1 · Gas cleaning device with a housing which delimits an enclosed space and with a gas inlet and a gas outlet, which is in communication with the enclosed space by a ceramic arrangement arranged in the enclosed space, which has a one-piece, skeletal structure and has a number of gas inlets (24), a number of gas outlets (j52) and gas flow paths (26), which extends from the gas outlets through the skeletal structure to the gas outlets extend, wherein the ceramic arrangement is arranged in the housing with the formation of a gap (j56) is, by a first flange (44) adjacent the periphery of a first end of the ceramic assembly is arranged and bridges the gap between the housing (22) and the ceramic arrangement, and by a first expandable ceramic fiber element (48) which is placed under compressive stress between the first flange (44) and the ceramic assembly is used to create an elastic connection between the first flange (44) and the ceramic assembly over the operating temperature range of the assembly. 2. Device according to claim 1, characterized in that the ceramic fiber element has a first section (48a), which is arranged next to the first flange (44, 44a), and a second section (48b), which lies next to the ceramic arrangement. - 21 509851/1016 J. Device according to claim 2, characterized in that the first section and the second section
of the paser element each cup-shaped
are. 4. The device according to claim 2, characterized in that the first section (48a) and the second section (48b) of the ceramic paser element each have one
Have an L-shaped cross-section. 5. Device according to claim 1, characterized in that the ceramic fiber element (48) is made of an aluminum made of minium oxide-silicon dioxide fiber material. 6. The device according to claim 1, characterized by an elastic element (42) which the ceramic arrangement surrounds and arranged in the space (j56) between the ceramic arrangement and the housing (22) is. 7. Device according to claim 1, characterized in that the first splash (44) next to the gas outlet openings £ 52) of the ceramic arrangement. 8. The device according to claim 7 *, characterized in that the «rste splash (44) and the gas outlet (16)
are integrally formed. 9. Device according to claim 8, characterized in that the gas outlet (16) consists of a frustoconical section, the wider end of which is on the housing
(22) and then to train the - 22 509851/1016 first flange (44) is directed radially inward. 10. Apparatus according to claim. 8, characterized in that the gas outlet (16) consists of a frustoconical Section consists, the wider end of which is bent radially outwards to the first Plansch (44) to form, which rests on the housing (22). 11. The device according to claim 1, characterized by a second flange (48) which is arranged next to the circumference of the second end of the ceramic arrangement and bridges the gap 06) between the housing (22) and the ceramic arrangement, and by a second expandable ceramic fiber element (48) inserted under pressure between the second flange (44) and the ceramic assembly to provide a resilient connection between the second flange (44) and the ceramic assembly over the operating temperature range of the assembly, 12. The device according to claim 1, characterized in that the catalyst of said ceramic Arrangement is worn. IJ. Device according to Claim J5, characterized in that that the second section (48b) of the ceramic fiber element lying next to the ceramic arrangement is more elastic than the first section (48a) lying next to the flange (44). - 23 509851/1 Π 1 6 Blank page