Patent Application
20170226913
The invention relates to a mounting mat for holding a ceramic substrate of a pollution control element or a chemical reactor, the pollution control element or chemical reactor comprising more than one substrate. The invention also relates to a pollution control element or chemical reactor comprising such a mounting mat and the invention relates to a method of assembling a pollution control element or chemical reactor with such a mounting mat.
Pollution control devices may be employed on for example motor vehicles, ships or other engines, e.g. stationary industrial engines, to control atmospheric pollution. Such devices may include catalytic converters and diesel particulate filters or traps. Catalytic converters typically contain a ceramic monolithic structure which supports the catalyst (e.g. a catalyst carrier or element). Diesel particulate filters or traps are typically wall flow filters which have honeycombed monolithic structures typically made from porous crystalline ceramic material (i.e., filter element). Each of these devices usually has a metal housing (typically stainless steel) in which the pollution control element or several pollution control elements is or are contained. A mat comprising ceramic fibers is typically used to mount and protect the pollution control element within the housing. Ceramic monolithic structures coated with a catalyst can also be used in chemical reactors, specifically in flow-through reactors for reaction in the gas phase.
US 2001/0030355 A1 discloses a catalytic converter cartridge comprising multiple square, rectangular or other flat sided catalyst coated substrates, each substrate of which has each of its flat sides covered by a compressible mat material. These multiple mat covered substrates or modules are arranged into a multiple module array enclosed within a metal shell with each module preferably separated from adjacent modules by sheet metal spacers. In addition to the mats and the metal spacers corner assembly aids, which may be left in place as the metal spacers, are foreseen.
DE 30 46 921 A1 discloses a catalytic converter comprising multiple flat sided substrates having a rectangular cross section. In order to hold the substrates in place, rigid L-shaped holding elements are provided that are positioned on both ends of the substrate. The holding elements provide additional holding edges extending perpendicular to the respective holding element.
WO2012084609A1 discloses a chemical reactor utilizing multiple ceramic substrates as carrier for the catalyst.
In view of the above prior art there is still a need for a mounting mat that enables building a simpler pollution control element or chemical reactor and providing a simplified method for assembling a pollution control element or chemical reactor. There is also still a need for a simpler pollution control element or chemical reactor itself.
The present invention provides a mounting mat for holding a substrate of a pollution control element or chemical reactor. The pollution control element or chemical reactor comprising more than one substrate, wherein the substrate comprises a front face, a rear face and at least three flat side faces extending between the front and the rear face, and wherein the mounting mat is shaped such that it covers at least partially an edge enclosed by two flat side faces (enclosed edge).
Enclosed edge in the sense of the invention is the edge that is enclosed by the two flat side faces that are covered by the mounting mat in a preassemble stage. Adjacent edge in the sense of the invention is the edge that is enclosed by a flat side face that is covered by a mounting mat and a flat side face that is not covered by a mounting mat in a preassembled stage. Preassembled stage means the stage when the mounting mats are already attached to the substrates but the substrates with mounting mats are not yet integrated into a housing.
A pollution control element according to the invention can be an element used in e.g. motor vehicles, ships or other engines, such as e.g. stationary industrial engines for example gas turbines, to control the atmospheric pollution. Examples for pollution control elements can include catalytic converters and diesel particulate filters. Other examples can be selective catalytic reduction elements or chemical reactors including substrates, e.g. ceramic substrates. A chemical reactor according to the invention is a system for carrying out chemical reactions. If for these chemical reactions catalysts are needed, it can be possible to use ceramic substrates inside the chemical reactor carrying the catalysts for the reaction.
Pollution control elements usually comprise a substrate. Chemical reactors may comprise substrates as well. Catalytic converters for example comprise a flow-through substrate, e.g. a ceramic flow-through substrate. Diesel particulate filters typically comprise wall-flow filters which have honeycombed monolithic structures, for example made from porous crystalline ceramic materials.
Especially when the pollution control element or the chemical reactor comprises more than one substrate the holding and sealing function gets more complex compared to systems with only one substrate, since holding and sealing does not only need to be performed between a substrate and a housing of a pollution control element or chemical reactor but also between two substrates.
The invention relates to substrates that comprise a front face, a rear face and at least three flat side faces extending between the front and the rear face. In most of the cases, the substrates comprise four flat side faces. But the invention is not limited to those embodiments with four side faces. The front and the rear face are those faces of the substrate that are oriented substantially perpendicular to the flow of gas inside the substrate. In other words they either face the entering gas flow or they face the exiting gas flow of the substrate. The side faces are oriented substantially parallel to the flow of gas inside the substrate and they may be oriented substantially perpendicular to the front and the rear face. The invention is not limited to the above described substrates. It is also possible that the side faces are oriented in an angle not perpendicular to the front and/or the rear face. It is also possible that the front and the rear face are oriented in an angle other than 90° relative to the flow of gas inside the substrate.
According to the invention the side faces are substantially flat or plain in a geometrically sense. That means that two flat side faces enclose an edge, wherein the enclosed edge is defined as an essentially linear line joining the two flat side faces. It is of cause possible that the enclosed edge comprises—due to manufacturing reasons—a slightly rounded shape, which extends in a linear direction. The side faces may comprise any suitable shape such as for example rectangular or square.
According to the invention the mounting mat is shaped such that it covers—at least partially—an edge enclosed by two flat side faces. Instead of having a mounting mat for each flat side face, the mounting mats are shaped such that they may cover more than only one flat side face. This may reduce the number of mounting mats needed for one pollution control element or chemical reactor. If less mounting mats are needed, less steps for assembling a pollution control element or chemical reactor are needed as well. This saves time and costs in the production process. Covering the enclosed edge at least partially means that the mounting mat may extend from the front face to the rear face and cover the entire enclosed edge. It is also possible that the mounting mat only extends partially between the front and the rear face. For example it is possible that the mounting mat does not extend completely up to the edge between side face and front/rear face. Such a configuration helps that in the assembled stage (substrate inside a housing) the mounting mat does not swell out of the housing. Another possibility is that more than one, e.g. two mounting mats are arranged parallel to each other each mat covering the enclosed edge partially.
According to one aspect of the invention, the mounting mat is a non-woven mounting mat comprising inorganic fibers. Generally all commonly known mounting mats can be used that are flexible and heat-resistant and that are able to hold the substrate of the pollution control element or chemical reactor in place and to seal the area around a substrate to isolate the substrate. Commonly known mounting mats comprise ceramic and/or glass fibers. The mounting mats may be intumescent mats or non-intumescent mats. If they are intumescent mats they may also include blowing agents like vermiculite or graphite. In order to compress the mounting mats, binders may be used and/or they may be compressed by mechanical processes such as for example needling.
According to another aspect of the invention the substrate is a ceramic substrate. Any known ceramic substrates may be used for the invention. Depending on the application of the substrate it may for example provide a flow-through characteristic or a wall-flow characteristic. They may comprise a catalyst coated on the substrate or integrated into the substrate.
If the pollution control element is a catalyst carrier, the substrate may be a catalyst coated ceramic substrate or a ceramic substrate including catalyst like acting particles, like vanadium pentoxide. The ceramic substrate may in this case for example comprise titan dioxide with vanadium pentoxide and wolfram oxide. If the pollution control element is a diesel particulate filter, the substrate may comprise silicium carbide, aluminium titanat or cordierite. If the substrate is a honeycomb catalyst, it may comprise titanium oxide, tungsten oxide and vanadium pentoxide. The required mechanical strength of the substrate may be achieved by adding for example glass fibers.
The substrate according to the invention may comprise four flat side faces that extend between the front and the rear face and the substrate may comprise a squared cross section. The four flat side faces may all comprise the same shape. They may be rectangular or square. It is also possible that at least two of the four flat side faces comprise the same shape.
The mounting mat may be shaped such that it covers at least partially two flat side faces (2-side wrapped substrate) and at least partially the edge enclosed by the two flat side faces of the substrate (enclosed edge). All possible configurations are meant to be claimed where the mounting mat covers at least partially two flat side faces and at least partially the edge between the two flat side faces. The mounting mat may for example extend along the entire width of two flat side faces from the enclosed edge up to each adjacent edge and along the entire length of the substrate from the front face towards the rear face. Another option is that the mounting mat according to the invention extends over the edge between two flat side faces (enclosed edge) along the entire length of the substrate but only covers parts of the width of the substrates and therewith of the two flat side faces, e.g. from the enclosed edge towards the middle of the flat side faces. It is also possible that one side face is covered completely and the other side face is covered partially.
The mounting mat may be shaped such that it covers at least partially three flat side faces (3-side wrapped substrate) and at least partially the two edges enclosed by two respective flat side faces of the substrate (enclosed edge). All possible configurations are meant to be claimed where the mounting mat covers at least partially three flat side faces and at least partially the two edges between two respective flat side faces. The mounting mat may for example extend along the entire width of three flat side faces from the enclosed edges to the adjacent edges and along the entire length of the substrate from the front face towards the rear face. Another option is that the mounting mat according to the invention extends over the two edges between three flat side faces (enclosed edges) along the entire length of the substrate but only covers parts of the two outer flat side faces. It is also possible that one or two of the flat side faces are covered completely and the remaining side faces are covered partially.
According to another embodiment of the invention the mounting mat may cover the entire two or three flat side faces (2-side wrapped or 3-side wrapped substrates) that enclose an edge up to the adjacent edges of the substrate. The entire flat side faces means that the mounting mat extends substantially over the entire surface of the flat side faces from the front face to the rear face and from the enclosed edge to the adjacent edges. The mat may thereby extend exactly from the front to the rear face and from one edge between two flat side faces to the other edge between two flat side faces. It is also possible as already pointed out above to leave a space at each edge of the front and the rear face in order to avoid the mat being squeezed out when being assembled with the substrate in a housing.
The 2-side wrapped substrates and the 3-side wrapped substrates can be used as preassembled components in the production process of pollution control elements or chemical reactors. With those preassembled components it is possible to assemble all kind of different pollution control configurations, e.g. different ways of arranging substrates in rows. For doing that only a minimum amount of different components is needed: a) the substrate, b) a mounting mat shaped such that it at least partially covers two flat side faces and at least partially the edge between them and c) a mounting mat shaped such that it at least partially covers three flat side faces and at least partially the two edges between two respective flat side faces. The reduced number of different parts needed reduces the complexity of the whole production process. It reduces the number of process steps and the complexity of handling parts during the assembly process. All these facts reduce the costs of the process and make the process more reliable since the risk for potential operator mistakes is also reduced.
It is also possible that the mounting mat only extends up to a defined width or distance before an adjacent edge. This space or receiving portion, where a flat side face of the substrate is not covered with a mounting mat, may for example be used as a receiving portion for a mounting mat or a part of an adjacent substrate of the pollution control element or chemical reactor.
The mounting mat may also extend over the adjacent edge and be placed in an above described receiving portion, when being assembled. The part of the mounting mat extending over the adjacent edge may be used for additional sealing purposes.
The invention also relates to a pollution control element or chemical reactor comprising more than one substrate as well as a mounting mat as described above.
According to one embodiment of the invention the pollution control element or chemical reactor may comprise four substrates arranged in two rows of two substrates. According to another embodiment of the invention, the pollution control element or chemical reactor may comprise nine ceramic substrates arranged in three rows of three substrates. These two configurations are commonly used configurations of substrates in pollution control systems. For theses configurations the below is a way to calculate the needed number of preassembled components (2-side wrapped and 3-side wrapped substrates).
If preassembled components of 2-side wrapped substrates and 3-side wrapped substrates exist, the following is a way to calculate the number of 2-side wrapped and 3-side wrapped substrates needed: when z is the number of substrates in a row and the number of rows; when x is the number of 3-side wrapped substrates and when y is the number of 2-side wrapped substrates, x is equal to 2 times z and y is equal to (z−2) multiplied with z.
All other configurations are possible as well such as for example u numbers of substrates in a row and v rows of substrates. When v is>then 2 the number of 2-side wrapped and 3-side wrapped substrates can be calculated as follows: when x is the number of 3-side wrapped substrates and when y is the number of 2-side wrapped substrates, x is equal to u+v and y is equal to u times v−x.
The invention can also include systems, with only one row of substrates. The invention can also include systems with at least one substrate that is entirely wrapped with one mat (e.g. 4-side wrapped). And the invention can also include systems with at least one substrate that is not wrapped with a mounting mat at all.
The invention also relates to a method for assembling a pollution control element or chemical reactor, the pollution control element or chemical reactor comprising more than one substrate, the method comprising the following steps:
a) providing more than one substrate, wherein the substrate comprises a front face, a rear face and at least three flat side faces extending between the front and the rear face;
b) providing a mounting mat according to any of the claims 1 to 8;
c) wrapping the mat around the substrate such that it covers at least partially an edge enclosed by two flat side faces of the substrate and fastening it;
d) repeating step c) as often as substrates are needed to assemble the pollution control element or chemical reactor;
e) placing the wrapped substrates next to each other so that all substrates' flat side walls are placed next to a mounting mat and
f) placing the substrates inside a housing.
Fastening of the mounting mat can for example be done by means of an adhesive. It is possible to apply the adhesive while assembling the pollution control element or chemical reactor. The adhesive may be applied in the form of a liquid adhesive, e.g. while assembling the pollution control element or chemical reactor. The adhesive may also be applied in the form of a tape, e.g. a double sided tape. The tape may include a liner. Therefore it would be possible to have a mat with a tape and a liner as a component for assembling the pollution control element or chemical reactor.
All typical methods for placing a substrate inside a housing may be used, such as for example stuffing, placing the substrates into the housing and closing the housing around the substrates followed by welding the housing etc.
The invention will now be described in more detail with reference to the following Figures exemplifying particular embodiments of the invention:
Herein below various embodiments of the present invention are described and shown in the drawings wherein like elements are provided with the same reference numbers.
As a next step of the method for assembling a pollution control element or chemical reactor, the preassembled components (wrapped substrates) are placed next to each other such that all substrates' flat side walls are placed next to a mounting mat, either a portion of a mounting mat 3 fixed to that specific substrate or a portion of a mounting mat of an adjacent substrate. One possibility of doing that has been described with reference to
Finally all substrates 2 with the mounting mats 3 wrapped around them are placed inside an adequate housing 6. The placing inside of a housing can be done with all generally known methods for placing a substrate 2 in a housing 6, such as stuffing, canning, closing the housing around the substrates with fastening it e.g. by welding.
The following is a way to calculate the number of 2-side wrapped and 3-side wrapped substrates needed, when you have a pollution control element or chemical reactor with the same number of rows as you have substrates in one row (squared assembly):
when z is the number of substrates in a row and the number of rows; when x is the number of 3-side wrapped substrates and when y is the number of 2-side wrapped substrates, x is equal to 2 times z and y is equal to (z−2) multiplied with z.
For the assembly shown in
z=3 therefore
x=2×3=6 (3-side wrapped substrates 2′″) and
y=(3−2)×3=3 (2-side wrapped substrates 2″).
For configurations that are not square and if the number of rows is higher than 2 the following equation can be used to calculate the number of 2-side wrapped and 3-side wrapped substrates:
u is the number of substrates in a row
v is the number of rows
x is the number of 3-side wrapped substrates
y is the number of 2-side wrapped substrates
x=u+v and
y=u*v−x.
For the assembly shown in
u=4 and
v=3 therefore
x=4+3=7 (3-side wrapped substrates 2′″) and
y=4*3−7=5 (2-side wrapped substrates 2″).
Depending on the tolerances of the substrates and the shapes of the mounting mats it is possible, that after placing wrapped substrates next to each other, a space or spaces in between the substrates/mounting mats exist, that needs to be sealed. A possible area for such a space may be the area, where four wrapped substrates or preassembled components touch each other. In order to seal this space, it is possible to use an additional piece of sealing materiel—e.g. narrow Interam™ band from roll. This material may for example be cut from a roll into the right length/width to sufficiently seal the space. The advantage of using an additional material for sealing purposes is that a space, for example in the centre may be filled and sealed perfectly.
Instead of using a separate piece of sealing material a preassembled component as shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 14183508.2 | Sep 2014 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US15/48062 | 9/2/2015 | WO | 00 |
