SE524226C2 - An apparatus for treating a gas flow - Google Patents

Abstract

The invention concerns a device for treatment of a gas flow, comprising at least one body 3, at least one first opening 4, 4' for entrance of an incoming gas flow to said body 3 and at least one second opening 5, 5' for the exit of an outgoing gas flow from said body 3, wherein said body 3 is provided with a plurality of gas flow passages 11a, 11b arranged to permit heat exchange between the gas flows in adjacent passages. The invention is characterized in that the device comprises at least one distribution section 26, 26' in communication with the first opening 4, 4' and with the gas flow passages 11a, 11b to distribute the incoming gas flow to the gas flow passages 11a, 11b, and at least one gas flow passage section 27, 27' including said gas flow passages 11a, 11b, which passage section 27, 27' primarily is adapted to permit heat exchange and to cause a conversion in the composition of the gas.

Description

524 226 gg; A conventional physical structure of a catalytic converter, such as e.g. described in US 3,885,977, is the honeycomb ceramic monoite having parallel, open channels. The catalytic material is deposited on the walls of the channels of the honeycomb structure.

As the gas flows from one end to the other, the catalytic conversion takes place. This type of construction generally works well provided that the temperature of the device is above the ignition temperature. In cold start situations, however, the harmful compounds flow through the channels without conversion.

In order to reduce the amount of harmful compounds released during cold start, it is a well known technique to use adsorption traps, i.e. depositing a material in addition to the catalysts that adsorbs and retains cold hydrocarbons and / or nitrogen oxides until the catalyst reaches the ignition temperature. This is shown e.g. in WO 95/18292. A problem with this technique when applied to the conventional construction described above is that the desorption temperature of most compounds is generally lower than the temperature required for conversion. Thus, a significant portion of the harmful compounds will still flow through the channels without being converted. Another way to solve the problem of cold converters is to introduce electric heating, as described e.g. in WO 92/14912. However, it is difficult to carry out the heating quickly enough and the costs for components and energy are high.

This type of electric heating can also be a safety hazard (electricity, fire).

Another important factor is the pressure drop across the purification device because energy is needed to overcome the gas flow resistance of the device. For example, an increased pressure drop across a car engine purifier may result in increased fuel consumption.

An interesting technique that has been proposed later is the combination of a catalytic purifier and a heat exchanger that allows heat exchange between the incoming gas and the outgoing gas. With this technology, it is possible to utilize the heat in the exhaust gases in a more efficient way, which is an advantage under most, if not all, operating conditions. EP 1 016 777 describes a construction consisting of a corrected metal strip which is folded and laid on itself to a bundle which forms gas flow passages between the folds. However, the shape of the metal strip correction forms a number of small passages within each larger passage between the folds, and as incoming gas flow enters the larger passages from its side, most of the gas will fl waste in the small passages located closest to the side from which the gas matades. In other words, the gas enters the bundle from the side and due to the difficulty of flowing across the larger passages, the gas flow will not be distributed within the width of the larger passages. This leads to a gas flow distribution which will, by and large, be -a-qu 10 15 20 25 30 35 .nu n. Non-uniform. Although this construction is in principle interesting, the uneven distribution of the liquid over the catalyst can lead to an insufficient conversion, a smaller and a large pressure drop. Furthermore, efficient heat exchange and to over the construction. metal structures are generally prone to degenerate in the harsh environment of an exhaust stream.

DESCRIPTION OF THE INVENTION An object of the present invention is to provide an apparatus for treating a gas flow which, compared with the prior art, converts the gas more efficiently and exhibits a lower pressure drop. This object is achieved by the technical features found in the characterizing part of claim 1. Subsequent claims contain advantageous embodiments, further developments and variants of the invention.

The invention relates to a device for treating a gas flow, comprising at least one body, at least a first opening for entry of an incoming gas flow into said body and at least a second opening for exit of an outgoing gas flow from said body, said body being provided with a a plurality of gas flow passages arranged to allow heat exchange between the gas flows in adjacent passages.

The invention that the distribution section communicating with the first opening and characterized by the device comprises at least one gas flow passage for distributing the incoming gas flow to the gas flow passages, and at least one gas flow passage section including the gas flow passages, which passage section is primarily adapted to accommodate a gas flow passage. the gas composition. An advantageous effect of this feature is that an improved gas flow distribution is achieved which makes it possible to utilize both the potentially available surfaces inside the gas treatment device in a more efficient manner, and to lower the pressure drop across the structure. A more efficient use of the surfaces can be used, for example, to achieve further conversion (eg purification) of the gas, to reduce the space required for the device by making it smaller, and to make the device cheaper by reducing its content of catalytic material for a given degree of conversion.

In an advantageous embodiment of the invention, the distribution section is adapted to distribute the incoming gas flow within the individual gas flow passes. In this way, the gas fate will not only be distributed among the various fate passages, but also within the individual passages which further increase the potential efficiency of the device. Preferably, the distribution section is adapted to provide a substantially uniform gas flow within the individual gas flow passages. In a second advantageous embodiment of the invention, the distribution section forms a part of the body. Preferably, the distribution section | connection to the second opening to also direct the outgoing gas flow out of the gas flow passages. Such a device makes it possible to give the device a compact design. In addition, it makes it possible to carry out heat exchange also in the distribution section.

In a third advantageous embodiment of the invention, the gas flow passages extend substantially parallel to each other, and further, the main direction of the gas flow in a main direction of the gas flow is in that gas flow passage is substantially the opposite to adjacent gas flow passage. This makes it possible to achieve a countercurrent heat exchanger process for the highest possible efficiency.

In a fourth advantageous embodiment of the invention, the body comprises a strip folded into a zigzag structure, and spacers are arranged between the folds of the zigzag structure in such a way that a distance is achieved between two folds facing each other in the zigzag structure, and the gas flow passages are thereby formed between the folds of the zigzag structure, and said spacers are arranged to facilitate the distribution of the incoming gas flow in the distribution section.

This arrangement allows the gas to flow freely across the gas flow passages and thus be distributed within the width of the passages. An advantageous effect due to the creation of the gas flow passages of a folded strip through the use of spacers is that it is a flexible system and that it offers many possibilities for arranging the distribution section. Another advantageous effect is that there is increased freedom in the design of the surface of the strip; the surface may, for example, be substantially non-patterned to reduce the flow resistance.

In a fifth advantageous embodiment of the invention, the body comprises a strip folded into a zigzag construction, and the surface of the strip has at least in part a three-dimensional pattern, preferably corrections, and said three-dimensional pattern is arranged to give rise to contact points and gaps between two folds which facing each other in the zigzag structure, and the gas fate passages are thereby formed in the gaps between the folds of the zigzag structure, and the surface of at least one of two folds facing each other differs from said three-dimensional pattern in the distribution section in such a way as to facilitate distribution of the incoming gas flow. This arrangement also allows the gas to flow freely across the gas flow passages and thus be distributed within the width of the passages. An advantageous effect of the distribution section of a folded strip through the use of different kinds of surface patterns is that of the creation of the gas flow passages and the construction contains fewer parts. In a sixth advantageous embodiment of the invention, the distribution section and the gas flow passage section form separate units which are arranged together in such a way that the gas can flow from one section to the other, preferably the distribution section and the gas flow passage section are connected to each other.

In this way, the sections can be produced individually, which makes it possible to optimize the production process and make it more cost-effective.

In a seventh advantageous embodiment of the invention, the distribution section comprises a wall structure forming at least a first channel to which the incoming gas flow is fed, and a plurality of other channels extending from said first channel and which other channels are open to the gas flow passages intended for an incoming gas flow. This enables a simple construction and a good distribution of the incoming gas flow. Preferably, said first channel is closed to the gas flow passages. As a result, the incoming gas is forced to flow via the other channels, which leads to an even more uniform distribution. In a further development, the wall structure forms a plurality of third channels which are open to the gas fate passages intended for an outgoing gas flow, preferably said third channels are formed between said second channels using common walls. This is an advantageous way of conducting the gas because heat exchange can also take place in the distribution section, and because no additional walls are needed.

In an eighth advantageous embodiment of the invention, the distribution section comprises a zigzag-shaped wall structure forming a first and a second set of channels, a set on each side of said zigzag structure, said first set of channels being open to the gas flow passages intended for an incoming gas flow and said second set of channels are open to the gas flow passages intended for an outgoing gas flow, and wherein the incoming gas flow is fed to the first set of channels. This design also enables a simple construction and a good distribution of the incoming gas flow.

In a ninth advantageous embodiment of the invention, the distribution section has a substantially unchanged cross-section in at least a certain direction. Thereby it is possible the section extrusion which is a cost effective to produce through production process.

Preferably, the distribution section and the gas flow passage section are made of a ceramic material, and the sections are connected to each other by sintering. This gives an advantageous construction because a ceramic material, compared to metal, has a lower 10 15 20 25 30 35 - u -. ,, 5 material cost, a lower production cost, a lower thermal expansion, a better adhesion of wash-coat and has a lower thermal mass per wall volume. A structure made of a ceramic material is also less prone to degenerate in the harsh environment that an exhaust gas flow constitutes.

In a tenth advantageous embodiment of the invention, the body has a substantially cylindrical shape, preferably the body has the general shape of a circular cylinder, and the body comprises an inner cavity extending in the longitudinal direction of the body, and at least one first or second opening is directed towards said cavity so that the gas flow is at least partially directed via said cavity. An advantageous effect of that design is that the device requires less space. A further advantage, especially in a vehicle exhaust purification application, is that the device can be designed with a long and narrow physical shape which can be arranged with its longitudinal axis in line with the exhaust pipe. By distributing the gas flow passages around the inner cavity and / or along the longitudinal axis of the body, this design enables a small pressure drop and advantageous packing properties.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the following drawings, in which: Figure 1 in a top view shows an example of a method of producing and building a gas treatment apparatus in accordance with a first advantageous embodiment of the invention. Figure 2 shows in more detail the first embodiment of the invention in accordance with Figure 1. Figure 3 shows, in an exploded perspective view, a second advantageous embodiment of the invention, Figure 4 shows a schematic cut-away view of a variant of the second advantageous embodiment of the invention. the invention according to Figure 3, Figure 5 shows a cross-sectional view AA according to Figure 4, Figure 6 shows a cross-sectional view BB according to Figure 4, Figure 7 shows a cross-sectional view CC according to Figure 4, Figure 8 shows a cross-sectional view DD in according to Figure 4, Figure 9 shows a cross-sectional view AA in accordance with Figure 4 of an alternative variant of the second advantageous embodiment of the invention. Figure 10 shows a cross-sectional view BB in accordance with Figure 4 corresponding to the variant shown in Figure 9, and Figure 11 shows a further development of the second embodiment of the invention in accordance with Figures 3 and 4. | DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows in a top view an example of a method of producing and building a gas treatment device in accordance with a first advantageous embodiment of the invention. A strip 1 is folded into a zigzag structure 2. Spacers in the form of corrugated plates 9 are arranged between the folds 10 of the zigzag structure 2 in such a way that a distance is achieved between two folds 10 facing each other in the zigzag structure 2. This distance makes it possible to feed a gas mellan gap between the folds 10. The corrugated plates 9 are arranged to leave a certain central space free of spacers. This free space forms part of a distribution section 26 which will be described in more detail with reference to figure 2. The zigzag construction 2 can be formed into bodies of different geometric shapes, depending on, for example, the application of the device. In Figure 1, the zigzag structure 2 forms a body 3 in the shape of a bundle.

The body 3 is placed in a housing 6 enclosing the body 3, and the housing 6 is provided with a first opening 4 for entry of an incoming gas flow into the body 3 and a second opening 5 for exit of an outgoing gas flow from the body 3. Seals 7 prevent gas from flowing under or over the body 3. In order to adapt the body 3 to effect a conversion in the composition of the gas, preferably at least a part of the surfaces of the body 3 which are in contact with the gas flow is coated with a catalytic material.

Figure 2 shows in more detail the first advantageous embodiment of the invention in accordance with Figure 1. In order to make it clearer, the zigzag construction is partly unfolded. Depending on the arrangement of the corrugated plates 9, a plurality of gas flow passages 11a, 11b are formed between the folds 10 in the body 3. Each other of said gas flow passages 11a, 11b is open towards the first opening 4; referred to as the gas flow inlet passages 11a. The second passages, the gas flow outlet passages 11b, are open to the second opening 5. The incoming gas is fed via the first opening 4 into the distribution section 26 in which it is divided into two main flows with opposite directions (left and right seen from the direction of the the incoming gas flow) and enters the inlet passages 11a in each of the gas fl passage passages 27. At both ends of the housing 6 the gas flow reaches a reversing chamber 13 where the gas leaves the inlet passages 11a and enters the outlet passages 11b through which the gas flows and leaves the second opening 5. A countercurrent heat exchange is thus allowed between adjacent gas flow passages.

Inside the first opening 4, the distribution section 26 is located, in which section the corrugated plates 9 are arranged to facilitate the distribution of the incoming gas flow over the width of the gas flow inlet passages 11a. As mentioned above, in this case the distribution section 26 is formed by a cavity in the presence of plates 9, so that the incoming gas can easily flow across the inlet passages 11a. Thereby, the gas flow can be distributed uniformly over the width of the individual inlet passages 11a. When the gas in a gas flow passage section 27 comprising the corrugated plates 9. Thus passes the distribution section 26, the device enters a distribution section 26 and two gas flow passage sections 27. In addition, the device comprises two reversing zones in the form of reversing chamber 13. Since the construction of the distribution section 26 in Figure 2 is similar inside if both the first opening 4 and the second opening 5, the distribution section 26 also facilitates the transport of the outgoing glass flow out of the outlet passages. This feature reduces the pressure drop across the structure.

The spacers are not limited to corrugated plates 9, but may for example comprise a mesh. Furthermore, the spacers may exhibit filtration properties for removal of particulate matter. Filtration material can also be placed in the space between the folds 10.

As an alternative to spacer means, the surface of the strip 1 may have a three-dimensional pattern, preferably corrugations, arranged to give rise to contact points and gaps between two folds 10 facing each other in the zigzag construction 2.

The frequency of the corrugations can e.g. be different between adjacent folds 10.

Alternatively, the phase position of the corrugations may be shifted between adjacent folds 10.

The gas flow passages 11a, 11b are thereby formed in the gaps between the folds 10.

Preferably, said three-dimensional pattern extends over an area of the folds 10 corresponding to the area covered by the corrugated plates 9 in Figures 1 and 2.

The distribution section 26 can thus be placed inside the first opening 4 in a similar manner as shown in figure 2. In this distribution section 26 the surfaces of the folds 10 can be designed to differ from the three-dimensional pattern, whereby the surfaces can for instance be substantially unpatterned, so that no or only a few contact points are created in the distribution section 26. The effect of this arrangement is similar to that of the distribution section 26 and thereby the gas kan fate described above, i.e. the incoming gas can easily flow across the inlet passages 11a in is distributed uniformly across the width of the inlet passages 11a.

A second advantageous embodiment of the invention is shown in Figures 3 to 10. In this embodiment, the distribution section and the gas flow passage section form separate units which are connected to each other. Figure 3 shows, in an exploded perspective view, the structure of a body 3 comprising a distribution section 26, two gas flow passage sections 27 and two reversing zones in the form of reversing chambers 13. Each passage section 27 is provided with a plurality of gas flow passages 11 and, compared to the thin walls u n. aau nan-u n 10 15 20 25 30 35 524 226 9 defining the gas flow passages 11, relatively thick support walls 33 dividing the gas flow passage section into a number of sectors. The body 3 has the shape of a circular cylinder and comprises an inner cavity 20 which extends in the longitudinal direction of the body. The incoming gas flow is fed into the body 3 via the inner cavity 20 and the outgoing gas flow leaves the body 3 via its periphery. These flow processes are further described below.

Figure 4 shows a schematic cut-away view of a variant of the second embodiment, the body 3 consisting of two lower bodies which have been connected to each other, and each lower body having a structure in accordance with Figure 3. The body 3 has also been provided with surrounding equipment for direct the gas to and from the body 3. Figures S, 6, 7 and 8 show cross-sectional views AA, BB, CC and DD, respectively, in accordance with Figure 4.

The structure of the distribution section 26 is not shown in Figure 4, but in Figure 5.

The incoming gas flow is fed into the body 3 through the first opening 4 into the inner cavity 20. The second end 23 of said cavity 20, opposite to that of the first opening 4, is closed which has the effect that the incoming gas fl is forced through the the first openings 4 'of each distribution section 26. As can be seen in Figure 5, the distribution section 26 consists of a wall structure forming (as an example) four first channels 29 which communicate with the inner cavity 20 via the first openings 4' and to which the first ducts 29 the incoming gas flow is fed.

The wall structure further forms a plurality of second channels 30 (in the case it is as an example five in each direction) extending from each of said first channels 29.

As can be seen in Figure 6, the gas flow passage section 27 is provided with a plurality of gas flow passages 11a, 11b. Each second of these passages forms an inlet passage 11a, intended for an incoming gas flow, and each second passage forms an outlet passage 11b, intended for an outgoing gas flow. Said second channels 30 (Figure 5) are open to the gas flow inlet passages 11a, while said first channels 29 are closed to all gas fl passages 11a, 11b through the ends of the support walls 33. In order to make it possible to use thinner support walls 33 and thereby reduce the amount of construction material in the body, the direct passage from the first channels 29 to the gas flow passages 11a, 11b can be closed by means of blocking means, for example thin plates, or by plugging suitable parts of the passages. When the incoming gas flow is fed through the first openings 4 'into the first channels 29, the gas is forced to be distributed into the second channels 30. From the second channels 30 the gas flow is fed to the inlet passages 11a. allowing the gas to flow to change direction and flow back to the distribution section 26 via the outlet passages 11b. The wall structure forming the first channels 29 and the second channels 30 in the distribution section 26 also forms a plurality of third channels 32 (in the figure there are as an example five in each direction) between said second channels 30 using common walls. These third channels 32 are open to the gas flow outlet passages 11b. Two sets of said third channel 32 open into a common fourth channel 34. In Figure 5 it can be seen that the distribution section 26, as an example, is provided with four fourth channels 34. The outgoing gas flow enters said third channels 32 from the outlet passages 11b and leaves the distribution section 26 via said fourth channels 34 and a second opening 5 'into an outlet channel 35 in the periphery of the body 3. At the end of the body 3, opposite to that of the first opening 4, the outlet channels 35 are combined into a common second opening 5 for the exit of the outgoing gas flow from the body 3.

Figure 7 shows a cross-sectional view of the section comprising the reversing chamber 13. As a variant, the reversing chamber 13 could be divided into a number of sectors. Figure 7 also shows the inner cavity 20 and the outlet channels 35. Figure 8 shows a cross-sectional view of a boundary plate 24 located between two lower bodies. Such plates 24 can be used to stabilize the structure. As an alternative to what is shown in Figure 4, the boundary plate 24 may form the end of the reversing chambers 13 of two adjacent lower bodies.

In order to direct the gas to the body 3, a pipe (eg an exhaust pipe) is preferably inserted through the first opening 4 all the way to the second end 23 of the inner cavity 20.

By providing the tube with the openings around its circumference at a position corresponding to the position of the distribution section (s) 26, the gas is allowed to flow into the distribution section (s) via the first openings 4 '. A pipe provided with openings can also be inserted through the second opening 5 in order to direct the gas away from the body 3. Such inserted pipes can be used to stabilize the structure.

Figures 9 and 10 show an alternative variant of the second embodiment of the invention.

The principle of this variant is similar, but the distribution section and the gas flow passage section have different internal shapes. Figure 9 shows a cross-sectional view A-A in accordance with Figure 4 of the alternative distribution section 26 ', and Figure 10 shows a cross-sectional view B-B in accordance with Figure 4 of the alternative gas flow passage section 27'.

Referring to Figure 9, the distribution section 26 'includes a zigzag wall structure forming a first set of channels 40 and a second set of channels 41, a set on either side of said zigzag structure.

The first set of channels 40 is open via the first openings 4 'towards the inner cavity 20 and towards the gas flow passages which are intended for an incoming gas flow; the inlet passages 11a. The second set of channels 41 are open to the gas flow passages intended for an outgoing gas flow; the outlet passages 11b, now »5 15 20 25 30 35 524 226: sgefgvw 11 and towards the outlet ducts 35. The presence of the gas flow passages 11a, 11b is shown in figure 10, each second passage forming an inlet passage 11a and each second passage forming an outlet passage 11b similar ways mentioned earlier. In this variant of the invention, the gas flows in a similar manner as described above; it enters the inner cavity 20 via the first opening 4, reaches the first set of channels 40 via the first openings 4 ', flows through the inlet channels 11a to the reversing chamber 13 where it changes direction and flows through the outlet channels 11b to the second set of channels 41 , and passes the other openings 5 'into the outlet channels 35.

An advantage of using more than one lower body, as exemplified in Figure 4, is that the incoming gas flow can be divided into a plurality of smaller gas flows which increase the efficiency of the device and lower the pressure drop across the structure. Of course, more than two lower bodies can be arranged together. Other arrangements are also possible, an example being to provide only one gas flow passage section 27 adjacent to the distribution section 26, and thus block the other side of the distribution section 26. This arrangement can be used to achieve a higher mechanical stability of the structure. Another alternative is to reverse the direction of the gas flow so that the gas enters the body 3 via the outlet channels 35 and leaves the body 3 through the first opening 4.

As can be seen from Figures 3 to 10, both the distribution section 26, 26 'and the gas flow passage section 27, 27' have a substantially unchanged cross-section in the longitudinal direction of the body. This means that these sections can be produced by extrusion, which is a cost-effective production method that is suitable for both metal and ceramic materials. Preferably, all sections / parts of the structure are made of a ceramic material and connected to each other by sintering. This provides a durable construction. In order to achieve a heat exchange effect between the inlet and outlet passages, the walls separating the passages must be reasonably thin. For a ceramic material, a wall thickness of about 0.1 mm would provide a rapid heat transfer through the wall compared to the heat transfer from the gas to the wall. An example of a suitable ceramic material is cordierite.

As for the alternative variant of the second embodiment shown in Figures 9 and 10, it is possible to produce / extrude the distribution section 26 'and the gas flow passage section 27' in one piece so that the first set of channels 40 forms part of the inlet passages 11a and the second set of channels. 41 forms part of the outlet ducts 11b. The cavity 20 and the distribution section 26 'may in such a case be arranged by inserting a tube provided with the inner openings to holes along the periphery as described previously. Another tube provided with openings from the distribution section 26 'may be provided on the outside of the duct / passage structure.

A further development of the second embodiment of the invention (Figures 3 and 4) is the adaptation of the device for removing particulate matter in the gas. Figure 11 schematically shows the principle of a gas flow filtration section 36 arranged between a gas flow passage section 27 and the section forming the reversing chamber 13. Although the design of the reversing chamber 13 may be the same as described above, in this case it has a different function which will be described below. Both the passage section 27 and the filtration section 36 are provided with gas flow inlet passages and gas fate outlet passages 11a, 11b as described above. Plugs 37 close the outlet passages 11b to the reversing chamber 13. The walls 39 between the passages 11a, 11b in the filtration section 36 show a porous structure through which gas can pass but not particles (larger than a certain size), which will be at least partially deposited in the reversing chamber 13. These walls 39 thus act as filters. As a result of the plugs 37, a pressure builds up in the reversing chamber 13. The gas flow in the inlet passages 11a is thus forced through the walls 39 in the filtration section 36 into the outlet passages 11b back to the passage section 27, as indicated by arrows in Figure 11. In principle, the filtration process could be performed in the passage section 27 , but porous walls in this section would impair the heat exchanger properties. After a certain time, the filtration walls 39 and the reversing chamber 13 need combustion of the soot. Depending on the heat exchanger properties of the invention, the heat generated in this process can be efficiently utilized by preheating the incoming gas in the gas flow passage section 27. As an aid in this FEQEHEFEFES QEDOITI process, a heat loop may be placed in the reversing chamber 13. In conventional ceramic particle filters in the soot combustion process in the filtration channels and takes up useful filter volume. According to Figure 11, the ash 38 may instead be at least partially accumulated in the reversing chamber 13. In some applications, the volume of the reversing chamber 13 is sufficient to accumulate ash 38 during the life of the gas treatment device. In other cases it is possible to provide the reversing chamber 13 with emptying means, such as an opening which is closed during normal operation.

The filtration section 36 shown in Fig. 11 is easily adapted to fit between the gas flow passage section 27 and the section forming the reversing chamber 13 shown in Figs. 3 and 4. Furthermore, the basic design of the filtration section 36 is the same as for the passage section 27. a certain direction and can therefore be produced by extrusion, be made of a ceramic material, and be connected to other ceramic 1. sonen. o sno-na o 10 15 20 25 30 35 13 1 n ~ n. c u. 'won u now I n ao-u a sections by sintering. The plugs 37 can be arranged by conventional means during or after the extrusion process. Of course, the filtration section 36 can be adapted for use with the alternative gas flow passage section 27 'shown in Figure 10.

Although the use of the ash accumulating reversing chamber 13 is advantageous, it is also possible to use the filtration section 36 without the reversing chamber 13, t 11a or by exchanging, for example, also by plugging the inlet passages the reversing chamber 13 towards a delimiting plate 24.

An advantage of the use of a countercurrent heat exchanger in the treatment of a gas flow in accordance with the invention is that the heat can be used very efficiently.

In addition to the amount of heat contained in the incoming gas, heat can be supplied to the gas from exothermic reactions in the body, preferably by using a catalytic material which has been coated on at least a part of the surfaces of the body which are in contact with the gas. The heat can also be supplied by an external source such as a heat generator preferably arranged in the reversing zone. Since the outgoing gas flow during its transport from the reversing chamber 13 to the second opening 5,5 'can transfer a large part of its heat to the incoming gas flow from the first opening 4,4' to the reversing chamber 13, only a small part of the supplied heat to leave the body 3 with the outgoing gas flow and thus be lost. Good heat economy is especially important if the incoming gas flow is relatively cold so that the temperature may fall below the previously described ignition temperature for the catalyst. An example of this is when the device is applied to purify the exhaust gases of a diesel engine.

The heat exchange process in accordance with the invention is also very useful in temperature transition situations, such as when purifying exhaust gases during a cold start situation.

In such an application of the invention, the body 3 is preferably provided with both a catalytic material and an adsorption / desorption substance applied to at least a part of the surfaces in the body 3 which are in contact with the gas flow. Said substance preferably adsorbs hydrocarbons and / or nitrogen oxides at or below a first temperature and releases them at or above a second temperature which is higher than the first temperature.

As the exhaust gases enter the cold body 3, heat will be transferred from the gas to the material contained in the body 3. The first part of the heat exchanger surfaces, i.e. the material in or near the distribution section 26 located closest to the first opening 4,4 ', heats up rapidly while the part near the reversing chamber 13 heats up slowly.

Since the body is arranged to allow heat exchange between adjacent passages, the heat exchange surfaces closest to the second opening 5.5 'will also heat up rapidly. A gas flow which passes the device shortly after start-up will thus undergo a first hot zone at the entrance to the body 3, a zone with successively decreasing a - weapon v - .vunna a 1 10 15 20 25 30 35 n 524 226 a - ne.- e -man oopvn o 14 temperature (the inlet passages 11a), a zone of successively increasing temperature (the outlet passages iib) and a second hot zone before exiting the body 3. Compounds adsorbed on adsorption / desorption substances applied to surfaces in the first hot zone will relatively fast to desorb, but will be adsorbed again on substances applied to colder surfaces near the reversing chamber 13. Since the temperature also increases with time near the reversing chamber 13, the compounds will desorb again.

This time, however, the compounds will be transported to zones with higher temperatures. By appropriate body design and selection of catalytic material and adsorbents / desorbents, the temperature in at least the hottest zone will be above the catalytic light-off temperature so that the compounds are converted efficiently. and reduce the amount of adsorption- to improve the heat economy / desorbents and catalysts required, the body surfaces to which catalysts for the purpose and said substances should be applied can be carefully selected. For example, catalysts for oxidation of HC and CO and reduction of NO, can be applied mainly in the hotter zones of the body (in or near the distribution section 26) and adsorbents / adsorbents can mainly be applied in the colder zones (in or near the reversing chamber 13).

In order to control the temperature of the gas flow in the body, the device preferably comprises one or more of the following: a heat generator arranged in the body (preferably arranged in the reversing chamber), heat sinks arranged in the body, devices for introducing cooling air into the body, and / or a system to control the composition of the incoming gas flow. Said system preferably comprises a device for introducing oxidizing substances, such as air, into the incoming gas flow, and / or a device for introducing oxidizable substances, such as hydrocarbons, into the incoming gas flow.

Depending on the heat exchanger properties of the device, the heat generated in the induced chemical reactions can be handled efficiently.

If the device is arranged in connection with an engine, said system for controlling the composition of the incoming gas flow preferably comprises a device for controlling the operation of the engine, which operation in turn can affect the composition of the incoming gas flow. For example, by mixing additional amounts of fuel into one or more of the cylinders, fuel, i.e. hydrocarbons, are introduced into the exhaust gas to be purified in the gas treatment device.

Thus, the distribution section (s) are primarily adapted to distribute the incoming gas flow to the gas flow passages, the passage section (s) are primarily to allow the composition of the gas, and the filtration section (s) are primarily adapted for adapted heat exchange and effect a conversion. 226 15 in a filtration section.

The invention is not limited to the embodiments described above, but a number of modifications are possible within the scope of the appended claims. For example, the reversal zone may be way. the reversing chamber 13 with transfer passages, e.g. holes, between gas flow inlet- designed on different An example is to replace the passages and the gas flow outlet passages.

Furthermore, the first embodiment of the invention is not limited to the variant shown in Figures 1 and 2. The zigzag construction 2 can e.g. be designed in accordance with other geometric structures. An example is to distribute folds 10 uniformly around an inner cavity so that the zigzag structure 2 assumes the shape of a circular cylinder with a longitudinal inner cavity. The gas can thus be fed to the body via the cavity. A variant of this is to form a discrete distribution of folds around the cavity, a number of lower bodies being arranged around the cavity. The shape of the distribution section 26, i.e. the shape of the corrugated plates 9, can also be modified to suit different applications. Seen in the direction of the incoming gas flow, the distribution section 26 may, for example, be tapered or expanding.

Regarding the second embodiment of the invention, it is possible to use a conventional monolith with a large number of narrow flow passages (and provided with the inner cavity 20) as an alternative to the gas d passage passages 27, 27 'shown in Figures 6 and 10. each of the gas flow passages in Figures 6 and 10 could in such a case be exchanged for a number of narrower passages side by side. With a suitable design, this arrangement would provide a more stable construction and have only a marginal effect on the heat exchange (depending on the extra material content in the body required for the extra walls). However, it would increase the pressure drop and require more material.

Claims (1)

An apparatus for the catalytic treatment of a gas stream, comprising at least one body (3), at least a first opening (4, 4 ') for the entry of an incoming gas stream to said body (3) and at least one second opening (5, 5 ') for exiting an outgoing gas flow from said body (3), said body (3) being provided with a plurality of 11b) arranged to allow heat exchange between the gas flows in adjacent passages, the device gas flow passages (11a) comprising at least one distribution section (26, 26 ') communicating with the first opening (4, 4') and with the gas flow passages (11a, 11b) for distributing the incoming gas flow to the gas flow passages (11a). , 11b), and (27, 27 ') gas flow passages (11a, 11b), which passage section (27, 27') is primarily adapted to at least one gas flow passage section including said to allow heat exchange and to effect a conversion in the composition of the gas, known as that the body (3) has a substantially cylindrical shape and that the body (3) comprises an inner cavity (20) extending in the longitudinal direction of the body (3), and that said at least one first (4, 4 ') or other (S, 5') opening is directed towards said cavity (20) so that the gas flow is at least partially directed via said cavity (20). Device according to claim 1, characterized in that the body (3) has the shape of a circular cylinder. characterized in that the distribution section (26, 26 ') is adapted to distribute the incoming Device according to claim 1 or 2, hence, the gas flow within the individual gas flow passages (11a, 11b). Device according to claim 3, characterized in that the distribution section (26, 26 ') is adapted to provide a substantially uniform gas flow inside the individual gas flow passages (11a, 11b). Device according to any one of the preceding claims, characterized in that the distribution section (26, 26 ') forms a part of the body (3). Device according to any one of the preceding claims, characterized in that the distribution section (26, 26 ') communicates with the second opening (5, 5') in order to also direct the outgoing gas flow out of the gas flow passages (11a, 11b). . Device according to any one of the preceding claims, characterized in that the gas flow passages (11a, 11b) extend substantially parallel in relation to each other. Device according to claim 7, characterized in that the main direction of the gas flow in a gas flow passage (11a, 11b) is substantially the opposite to the main direction of at least one of the gas flows in adjacent gas flow passages (11b, 11a). Device according to claim 8, characterized in that said gas flow passages (11a, 11b) form inlet passages (11a) intended for an incoming gas flow and outlet passages (11b) intended for an outgoing gas flow, and that a reversing zone (13) is provided so that gas entering the reversing zone (13) from the inlet passages (11a) is allowed to change direction and flow back through the outlet passages (11b). Device according to claim 9, characterized in that the reversing zone comprises a reversing chamber (13). Device according to one of the preceding claims, characterized in that the body (3) comprises a strip (1) which is folded into a zigzag construction (2) and (10) of the zigzag construction (2) in such a way that a distance is achieved between two spacers (9) are arranged between the folds folds (10) facing each other in the zigzag structure (2), and that the gas flow passages (11a, 11b) are thereby formed between the folds of the zigzag structure (2), and that said spacers (9) are arranged to facilitate the distribution of the incoming gas flow in the distribution section (26). Device according to any one of claims 1-10, characterized in that the body (3) comprises a strip (1) which is folded into a zigzag construction (2), and that the surface of the strip (1) has at least partially a three-dimensional pattern, preferably corrugations, and that said three-dimensional pattern is arranged to give rise to contact points and gaps between two folds (10) facing each other in the zigzag structure (2), and that the gas flow passages (11a, 11b) are thereby formed in the gaps between the folds (10). ) of the zigzag structure (2), and that the surface of at least one of two folds (10) facing each other differs from said three-dimensional pattern in the distribution section (26) in such a way that the distribution of the incoming gas flow is facilitated. Device according to claim 11 or 12, characterized in that a housing (6) provided with said first opening (4) and said second opening (5) encloses the zigzag structure (2). Device according to one of Claims 1 to 10, characterized in that the distribution section (26, 26 ') and the gas flow passage section (27, 27') form separate units which are arranged together in such a way that gas can flow from one section to the other. preferably the distribution section (26, 26 ') and the gas flow passage section (27, 27') are connected to each other. Device according to claim 14, characterized in that the distribution section (26) comprises a wall structure forming: at least a first channel (29) to which the incoming gas flow is fed; and a plurality of second channels (30) extending from said first channel (29) and which second channels (30) are open to the gas flow passages (11a, 11b) intended for an incoming gas flow. Device according to claim 15, characterized in that said first channel (29) is closed to the gas flow passages (11a, 11b). claim 15 or 16, the wall structure forms a plurality of third channels (32) open to the Device according to characterized in that the gas flow passages (11a, 11b) intended for an outgoing gas flow are preferably said third channels (32) formed between said second ducts (30) using common walls. Device according to claim 14, characterized in that the distribution section (26 ') comprises a zigzag-shaped wall structure forming a first and a second set of channels (40, 41), a set on each side of the zigzag-shaped structure, said first set of channels (40 ) are open to the gas flow passages (11a, 11b) which are intended for an incoming gas flow and said second set of channels (41) are open to the gas flow passages (11a, 11b) which are intended for an outgoing gas flow, and wherein the incoming gas flow is fed to the first set of channels (40). Device according to one of Claims 14 to 18, characterized in that the distribution section (26, 26 ') has a substantially unchanged cross section in at least a certain direction. Device according to claim 19, characterized in that the distribution section (26, 26 ') is produced by extrusion. Device according to one of Claims 14 to 20, characterized in that the distribution section (26, 26 ') and the gas flow passage section (27, 27') are made of a ceramic material, and in that the sections are connected to one another by sintering. Device according to any preceding claim, characterized in that (36), filtration section (36) is primarily adapted to remove particulate matter from the device, comprising at least one filtration section which gas. Device according to any one of the preceding claims, characterized in that at least a part of the surfaces of the body (3) which are in contact with the gas flow are coated with a catalytic material. Device according to any one of the preceding claims, characterized in that at least a part of the surfaces of the body (3) which are in contact with the gas flow are coated with an adsorption / desorption substance. Device according to any one of the preceding claims, characterized in that the device comprises means for controlling the temperature of the gas flow in the body (3), said means comprising one or more of the following: - a heat generator arranged in the body (3) , - cooling fins arranged in the body (3), - devices for introducing cooling air into the body (3), - a system for controlling the composition of the incoming gas flow. Device according to claim 25, characterized in that said system for controlling the composition of the incoming gas flow comprises one or both of the following: - a device for introducing oxidizing substances, such as air, into the incoming gas flow, - a device for introducing oxidizable substances, such as hydrocarbons, into the incoming gas stream. Device according to claim 25, characterized in that the device is arranged in connection with an internal combustion engine, and that said system for controlling the composition of the incoming gas flow comprises a device for which operation in to control the operation of the internal combustion engine, in turn affects the composition of the incoming gas flow. Device according to one of the preceding claims, characterized in that the device is adapted to purify the exhaust gases from an internal combustion engine, preferably in a mobile application.