Heated catalyst and internal combustion engine provided with same

Abstract

The invention relates to a heated catalyst (2) for an exhaust gas aftertreatment device or a reformer which is designed to convert a fuel using an oxidizing agent, wherein the heated catalyst (2) has a housing (25) which has an inlet (21) and an outlet (22), wherein the inlet (21) is designed to supply the oxidizing agent and the outlet (22) is designed to discharge a product gas, and wherein the heated catalyst (2) also contains a catalyst carrier (5) arranged in the housing (25), wherein a fuel plate (6) is arranged on one side of the catalyst carrier (5) and is designed to supply the fuel to the catalyst carrier (5), and a perforated plate (4) is arranged on a side of the catalyst carrier (5) opposite the fuel plate (6) and is designed to supply the oxidizing agent to the catalyst carrier (5), wherein the perforated plate (4) has a plurality of through-holes (41) which are fewer in number and / or have a smaller surface density and / or a smaller diameter in at least one first zone (421) of the perforated plate (4) and which are greater in number and / or have a larger surface density and / or a larger diameter in at least one second zone (422).

Description

[0001] FRIESE GOEDEN

[0002] Patent Attorneys PartGmbB Widenmayerstraße 49 80538 Munich

[0003] Our reference number: 32032 PWO GO

[0004] Applicant: Fraunhofer-Gesellschaft eV

[0005] Heating catalyst and combustion engine equipped with it

[0006] The invention relates to a heating catalyst for an exhaust aftertreatment device or a reformer, which is configured to react fuel with an oxidizing agent, wherein the heating catalyst has a housing which has an inlet and an outlet, wherein the inlet is configured to supply the oxidizing agent and the outlet is configured to discharge a product gas, and wherein the heating catalyst further comprises a catalyst support arranged in the housing, wherein a fuel plate is arranged on one side of the catalyst support, which is configured to supply the fuel to the catalyst support, and a perforated plate is arranged on one side of the catalyst support opposite the fuel plate, which is configured to supply the oxidizing agent to the catalyst support.

[0007] A heating catalyst is known from WO 2020 / 193595 Al. A partial stream of exhaust gas from an internal combustion engine and / or fresh air is fed to the heating catalyst. Fuel is also supplied to the heating catalyst. The fuel is either completely oxidized at the heating catalyst, producing a hot gas. In other operating conditions, the fuel can be partially converted at the heating catalyst, producing a product gas in the form of a reformate or synthesis gas, which has a lower light-off temperature at an oxidation catalyst compared to the unmodified fuel. The hot gas or the product gas is fed to a component of an exhaust aftertreatment system, for example, a three-way catalyst, an SCR catalyst, an oxidation catalyst, or an NOₓ catalyst. x-storage catalyst or a particulate filter. The heated catalyst allows the exhaust aftertreatment system to be brought up to operating temperature quickly after a cold start. Furthermore, a particulate filter can be regenerated by applying heat, regardless of the engine's operating condition.

[0008] The well-known heating catalyst has the disadvantage that the catalyst support and / or the fuel plate can be destroyed by high thermal stress or hotspots under certain operating conditions. Conversely, under lower load conditions, individual areas can cool down, leading to the formation of deposits or coking.

[0009] Based on the prior art, the invention is therefore based on the objective of increasing the operational reliability and service life of a heating catalyst.

[0010] According to one aspect of the present description, a heating catalyst is defined. The heating catalyst can, in some embodiments, be designed and intended to raise the temperature of an exhaust aftertreatment system or to supply thermal energy to an exhaust aftertreatment system. The exhaust aftertreatment system can, in some embodiments, be selected from a three-way catalyst, an SCR catalyst, an oxidation catalyst, a NOx storage catalyst, and / or a particulate filter. The exhaust aftertreatment system can contain at least one of the aforementioned elements. In other embodiments, the exhaust aftertreatment system can also contain several of the aforementioned elements. In still other embodiments, elements can be combined; for example, a particulate filter can also serve as an SCR catalyst through appropriate coating.The heating catalyst can be configured and designed in other forms to raise the temperature of a reformer and supply thermal energy to it. The reformer can be configured and designed to convert chain hydrocarbons into branched hydrocarbons or to produce pure hydrogen from a methanol-water mixture, releasing carbon dioxide in the process.

[0011] The oxidizing agent supplied to the heating catalyst can, in some designs, be or contain exhaust gas. In other designs, the oxidizing agent can be or contain ambient air.

[0012] The exhaust gas from an internal combustion engine can be discharged via an exhaust pipe and fed to the exhaust aftertreatment system. The heating catalyst can have a housing with an inlet and an outlet. The inlet can be connected to an exhaust pipe in such a way that at least a portion of the exhaust gas flowing in the exhaust pipe can be fed into the housing through the inlet. Furthermore, the outlet can be connected to an exhaust pipe in such a way that hot gas or product gas generated in the heating catalyst can be discharged from the housing and fed into the exhaust pipe. In some designs, the inlet can be connected to the exhaust pipe above the outlet when viewed in the direction of exhaust gas flow.

[0013] The housing of the heating catalyst can contain a catalyst support. The catalyst support can be, for example, a metal, a ceramic, or a sheet metal structure. The catalyst support can be a porous body through which products or reactants can flow. In some embodiments, the catalyst support can be a sheet metal structure or composed of a plurality of sheet metal parts. The catalyst support can be provided with a catalytically active coating, which may, for example, contain platinum and / or rhodium. However, the invention does not teach the use of a specific catalytically active material as a solution principle. In some embodiments, the catalyst support itself can consist of or contain a catalytically active material.

[0014] A fuel plate can be arranged on one side of the catalyst support. The fuel plate is designed and intended to distribute the supplied fuel across its surface so that it can be directed to the catalyst or the catalyst support. A perforated plate can be arranged on the opposite side of the catalyst support from the fuel plate. The perforated plate is designed and intended to direct the oxidizing agent supplied via the inlet, for example, exhaust gas and / or ambient air, to the catalyst support. The perforated plate can have multiple through-holes through which the exhaust gas, or optionally another oxidizing agent, can flow to the catalyst support. The gaseous oxidizing agent and the fuel are thus supplied to the catalyst support from opposite directions and react there.In some embodiments of the invention, the sides of the catalyst carrier opposite the fuel plate and the perforated plate can each be the sides with the largest surface area.

[0015] The heating catalyst can be designed and configured in some versions to operate in two states. Either the oxidizer and fuel can be supplied stoichiometrically or superstoichiometrically, resulting in complete or near-complete oxidation of the fuel. The exothermic oxidation reaction produces a hot gas, consisting primarily of CO2 and H2O in addition to N2, which is released at high temperature through the outlet into the exhaust system. The heat introduced in this way can directly heat the exhaust aftertreatment system, or at least one component thereof.

[0016] In the second operating state, the oxidizer and fuel are fed to the catalyst support at substoichiometric rates. The exothermic reaction that occurs here is sufficient to vaporize the fuel on the fuel plate and partially react it at the catalyst. This produces a product gas in the form of a reformate or synthesis gas, which generally contains shorter-chain hydrocarbons than the fuel and can therefore have a lower light-off temperature. The product gas can be oxidized at individual components of the exhaust aftertreatment system to generate heat directly in a particulate filter or a catalyst.

[0017] The control or regulation of the first or second operating state is achieved on the one hand by the amount of oxidizer supplied and on the other hand by the amount of fuel supplied. In operating states of the internal combustion engine that do not require additional heating of the exhaust aftertreatment system, the heating catalyst can also be deactivated. For this purpose, the fuel supply and / or the exhaust gas supply can be interrupted. Alternatively, in operating states of the internal combustion engine that do not require additional heating of the exhaust aftertreatment system, the heating catalyst can be put into a low-power standby state. For this purpose, the fuel supply and / or the exhaust gas supply can be throttled.

[0018] The present disclosure further describes a fuel plate equipped with a transport device and usable as part of a heating catalyst. The transport device can have multiple channels located on the side of the fuel plate facing the catalyst support. Fuel exiting the fuel line and wetting the fuel plate is distributed across the plate by the channels located within it. The channels can be interconnected for this purpose. In some embodiments, the channels can form a continuously branching network. This allows the fuel to be distributed evenly across the surface of the fuel plate from one or more outlets. For this purpose, the channels can be at least partially open towards the catalyst support, allowing for fuel vaporization.Depending on the internal combustion engine, the fuel used can be gasoline or diesel, a synthetic fuel, a biogenic fuel, DME or OME, or even an alcohol or a liquefied petroleum gas. The even distribution of the fuel reduces or prevents deposits and coking.

[0019] In some embodiments, the heating catalyst may also contain a porous molded body. This molded body may be made of a woven, knitted, nonwoven, or foam material and may be positioned between the catalyst support and the fuel plate. In some embodiments, the molded body may be bonded to the fuel plate. In some embodiments, the molded body may be made of a metal or alloy. This allows, in a first step, a coarse distribution of the fuel onto the fuel plate through the channels described above. In a second step, the fuel can be absorbed from the channels by the molded body or by the capillary forces acting within it and transported towards the catalyst support. This results in a more uniform distribution of the fuel.The present disclosure further describes a heating catalyst which also includes a porous molded body arranged between the catalyst support and the fuel plate. The molded body is provided with a transport device comprising a plurality of channels, which are incorporated into the side of the molded body facing the fuel plate and are at least partially open towards the fuel plate. Fuel exiting the fuel line and wetting the fuel plate is distributed through the channels in the molded body. The channels may be interconnected for this purpose. In some embodiments, the channels can form a continuously branching network. This allows the fuel to be distributed evenly from one or more outlets across the surface of the molded body or the fuel plate.

[0020] For this purpose, the channels to the catalyst support can be at least partially open, allowing fuel vaporization. Depending on the internal combustion engine, the fuel used can be gasoline or diesel, a synthetic fuel, a biogenic fuel, DME or OME, an alcohol, or a liquid gas. The even distribution of the fuel reduces or prevents deposits and coking. The shaped element can simultaneously serve as the catalyst support or as an additional element for fuel distribution.

[0021] In some designs, channels or transport devices can be present both in the fuel plate and in the porous molded body.

[0022] In some embodiments, the fuel plate may have at least one bore extending from the side of the fuel plate facing away from the catalyst support to the side facing the catalyst support, and opening into a first channel. The bore may be configured and designed to be connected to a fuel line on the side of the fuel plate facing away from the catalyst support, so that the fuel flows through the bore into the first channel. The first channel may be configured and designed to distribute the fuel across the width of the fuel plate. In some embodiments, the bore may have a cross-section that increases in size from the line to its opening in the first channel. In some embodiments, the bore may have a conical cross-section.This can reduce the flow velocity of the incoming fuel, thus preventing overflow.

[0023] In some embodiments, the fuel plate can have multiple bores extending from the side facing away from the catalyst support to the side facing the catalyst support, each opening into a first channel or each opening into a first channel facing the corresponding bore. Multiple fuel inlets allow for more precise power control over a wider range and / or with greater accuracy in some embodiments, by supplying fuel either through one or multiple bores, thus ensuring that only a portion of the fuel plate or the entire plate is wetted with fuel. In some embodiments, the number of bores can range from 1 to approximately 6 or from approximately 2 to approximately 4.

[0024] In some designs, the cross-sectional area of ​​the channels can decrease along their length. The cross-sectional area of ​​the channel can therefore be larger near the bore through which the fuel enters, and smaller at greater distances from the bore. This is partly because fuel evaporates during transport through the channels, thus reducing the amount transported. It is also because the channels branch along their length, so that at greater distances from the bore, several channels are available for fuel transport, each carrying a smaller quantity than channels located upstream.

[0025] In some designs, the fuel can be transported through the channels by gravity. In this case, the installation position of the heating catalyst is chosen so that the fuel plate is inclined relative to the vertical. In some designs, the fuel plate can be approximately vertical, i.e., it forms an angle of inclination of approximately 80° to 100° or 85° to 95° with the horizontal. This ensures the simple transport of the fuel through the channels of the fuel plate.

[0026] In some designs, the fuel can be transported through the channels by capillary action. For this purpose, the channels have a cross-section tailored to the respective fuel quantity, allowing the corresponding capillary forces to develop. This ensures fuel transport regardless of the installation position.

[0027] In some embodiments, the cross-sectional area of ​​the channels can be designed along their length such that the fuel propagation speed in the horizontal direction is greater than the fuel propagation speed in the vertical direction. This ensures that the full width of the fuel plate is utilized at all output power levels of the heating catalyst and that power control is managed via the vertical propagation. This can further reduce coking or deposits. In some embodiments, the width of the channels can decrease along their length. This reduces the cross-sectional area of ​​the channels along their length, as described above.

[0028] In some designs, the depth of the channels can decrease along their length. This design also serves to reduce the cross-sectional area of ​​the channels along their length. In this case, manufacturing can be carried out with a single milling cutter while maintaining a constant channel width. This cutter cuts less deeply into the material as the channel length increases, thus simplifying the manufacturing process.

[0029] In some versions, the channel width can decrease from approximately 5 mm to approximately 0.5 mm along its length. In other versions, the channel width can decrease from approximately 3 mm to approximately 0.8 mm along its length. This cross-sectional area is sufficient to cover a thermal power range of approximately 5 kW to approximately 50 kW in a compact design. Furthermore, the heating catalyst can optionally be operated in a standby mode, in which the thermal power is between approximately 50 W and approximately 1 kW, without significant deposits or coking forming.

[0030] In some versions, the depth of the channels can decrease along their length from approximately 1 mm to approximately 0.05 mm. In other versions, the depth of the channels can decrease along their length from approximately 0.7 mm to approximately 0.1 mm. This allows for simple manufacturing by milling or primary forming, or by forming processes such as embossing.

[0031] In some designs, the first channel of the heating catalyst can be inclined at approximately 20° to 30° to the horizontal. This allows for reliable fuel transport by gravity. At the same time, the fuel flows slowly enough to ensure uniform wetting of the fuel plate without dry spots or liquid accumulation, thus preventing coking and hotspots and enabling reliable operation.

[0032] In some designs, a number of secondary channels can branch off from the first channel, inclined at approximately 40° to 90° to the horizontal when the heating catalyst is installed. This ensures rapid branching of the channels across the surface of the fuel plate, resulting in uniform wetting.

[0033] In some embodiments, the fuel plate may have a portion of its surface without channels. This portion may be a circular segment located at the lower edge of the fuel plate when viewed in its installed position. The circular sector may have a height of approximately 10% to 40% or 15% to 35% of the fuel plate's radius.

[0034] In some designs, the total length of the channels is chosen such that the fuel supplied during partial load operation is completely vaporized before reaching the end of the channels. In such an operating condition, only a portion of the catalyst support or a portion of the fuel plate is wetted by the fuel vapor or liquid fuel. This allows the temperature in the portion wetted by the fuel vapor to be kept high enough to prevent coking. Under higher power demand, an increasingly larger quantity of fuel can be supplied, which wets an increasingly larger portion of the fuel plate, until at full load the channels or the entire fuel plate is completely wetted.

[0035] In some embodiments, the secondary channels can have multiple first and second longitudinal sections and multiple branching points along their course, with the first and second longitudinal sections initially diverging and then converging between adjacent branching points. This allows the length of the secondary channels from their source at the first channel to their outlet at the end of the fuel plate to be increased, thus extending the flow time. This ensures that the fuel evaporates completely and does not collect in liquid form at the bottom edge of the fuel plate, where it could lead to coking and contamination. In some embodiments, the entire fuel plate can be wetted.

[0036] In some configurations, adjacent first and second longitudinal sections can form an angle of approximately 70° to approximately 110°. In other configurations, adjacent first and second longitudinal sections can form an angle of approximately 80° to approximately 100°. In still other configurations, adjacent first and second longitudinal sections can form an angle of approximately 85° to approximately 95°. Between two adjacent branching points, the second channels thus run approximately in the shape of a rectangle, a square, or a rhombus. At the branching points, a backflow of liquid fuel can occur, further reducing the flow rate through the channels to allow sufficient time for fuel vaporization.

[0037] In some embodiments, the transport device or the channels on the fuel plate can be designed in such a way that a horizontal component of the propagation velocity v is present at all operating points. L1 the amount of fuel metered onto the fuel plate is greater than a vertical component of the propagation speed v L2 of the fuel metered onto the fuel plate. The measurement of the propagation speeds is carried out with diesel fuel at room temperature, whereby the wetting behavior of the fuel plate is optically recorded using a camera.

[0038] In some implementations, the ratio of the horizontal component of the propagation speed v can be L1 of the fuel metered onto the fuel plate to the vertical component of the propagation speed v L2The amount of fuel metered onto the fuel plate can be between approximately 1.05 and approximately 6.5 or between approximately 1.1 and approximately 5.5. In some embodiments, the ratio of the horizontal component of the propagation velocity v can be L1 of the fuel metered onto the fuel plate to the vertical component of the propagation speed v L2 The relationship between the fuel metered onto the fuel plate and the power output of the heating catalyst follows a logarithmic curve. This allows for optimization of the reaction surface area, enabling the fuel plate to operate with only one fuel inlet hole. This simplifies the control of the heating catalyst.

[0039] The present disclosure further describes a perforated plate with multiple through-holes, suitable for use as part of a heating catalyst. The perforated plate can have multiple through-holes, with a lower number, lower areal density, and / or smaller diameter in a first zone. Furthermore, the perforated plate can have at least a second zone with a larger number, higher areal density, and / or larger diameter of through-holes. The areal density is defined as the number of through-holes per unit area. In some embodiments, the second zone can have a larger area than the first zone.

[0040] The stoichiometry of the reaction taking place in the catalyst support can be influenced by the number and / or diameter and / or area density of the through-holes in the perforated plate. For example, in one area of ​​the fuel plate opposite the first zone of the perforated plate, the fuel can be evaporated substoichiometrically, and then oxidized superstoichiometrically in one area of ​​the catalyst support opposite the second zone. This can prevent or at least reduce overheating and / or scaling or coking of the fuel plate and / or the catalyst support.

[0041] If the perforated plate has a first and a second zone in which the number and / or diameter and / or area density of the through-holes differ, the first zone can be positioned above the second zone when the heating catalyst is installed. This allows the fuel to initially vaporize substoichiometrically without overheating the catalyst support. A larger quantity of oxidizing agent can then be added to the second zone, enabling complete fuel conversion.

[0042] In some embodiments, the perforated plate can have a third zone in which the through-holes are designed to generate a flushing flow in the fuel-free edge region. This prevents dead zones in the catalyst support or on the fuel plate. In some embodiments, the through-holes can be arranged in rows that run approximately horizontally when the heating catalyst is installed. In other embodiments, the through-holes can be arranged in rows that run at approximately 0° to approximately 15° or approximately 0° to approximately 8° to the horizontal when the heating catalyst is installed.

[0043] In some embodiments, the through-holes of one row can be offset from those of an adjacent row. In some embodiments, the offset can be maximal, meaning that the through-holes of one row lie above the spaces between the through-holes of an adjacent row. This feature has the effect of enabling maximum backflow over the catalyst support and good mixing of the product gas.

[0044] In some versions, the perforated plate may have a fourth zone without through-holes. In some versions, when the heating catalyst is installed, the fourth zone may be located below the second zone.

[0045] In some embodiments, the diameter of the through-holes can range from approximately 2.0 mm to approximately 2.6 mm. In other embodiments, the diameter of the through-holes can range from approximately 2.3 mm to approximately 4 mm. In still other embodiments, the diameter of the through-holes can range from approximately 2.6 mm to approximately 3.7 mm. This allows the stoichiometry to vary in different areas of the catalyst support.

[0046] In some embodiments, the perforated plate can be designed such that a proportion of between approximately 1% and approximately 40% or a proportion of between approximately 5% and approximately 27% of the mass flow rate of the oxidizing agent flows through the through-holes of the first zone. In some embodiments, the perforated plate can be designed such that a proportion of between approximately 50% and approximately 97% or a proportion of between approximately 60% and approximately 94% of the mass flow rate of the oxidizing agent flows through the through-holes of the second zone. In some embodiments, the perforated plate can be designed such that a proportion of between approximately 0% and approximately 20% or a proportion of between approximately 2% and approximately 15% of the mass flow rate of the oxidizing agent flows through the through-holes of the third zone.In some embodiments, the perforated plate can be designed such that a proportion of between approximately 0% and approximately 2% or a proportion of between approximately 0% and approximately 1% of the mass flow of the oxidizing agent passes through the fourth zone of the perforated plate. This means that the fourth zone preferably has no through-holes, so that, except for unavoidable leakage, no oxidizing agent is introduced into the fourth zone.

[0047] In some embodiments, the heating catalyst can be equipped with the fuel plate described and a conventional perforated plate known per se. In other embodiments, the heating catalyst can be equipped with the perforated plate described here and a conventional fuel plate known per se. In still other embodiments, the heating catalyst can have both the perforated plate and the fuel plate described here. In this way, the heating catalyst can be adapted in a variety of ways to the respective intended use, the exhaust aftertreatment system, and the internal combustion engine.

[0048] In some embodiments, this refers to an internal combustion engine with at least one catalytic converter. In some embodiments, this refers to a motor vehicle or a vessel with an internal combustion engine and at least one catalytic converter. A motor vehicle within the meaning of this description can be a passenger car or a truck for use on paved roads. Furthermore, a motor vehicle within the meaning of this description can also be construction machinery, for example, a dump truck, a wheel loader, an excavator, a crane, or any other construction machinery known per se.

[0049] The invention will be explained in more detail below with reference to figures, without limiting the general concept of the invention. This will show

[0050] Figure 1 shows a schematic representation of the integration of a heating catalyst into an exhaust pipe.

[0051] Figure 2 shows a fuel plate in the .

[0052] Figure 3 shows a perforated plate in view together with the fuel plate in the installed position, which is covered by the perforated plate and the catalyst carrier.

[0053] Figure 4 shows a perforated plate in a view

[0054] Figure 1 illustrates the integration of a heating catalyst 2 into an exhaust pipe 3. Figure 1 shows a longitudinal section through a short part of the exhaust pipe 3 with the heating catalyst 2 attached to it.

[0055] The heating catalyst is designed and intended for use with an internal combustion engine (not shown). The internal combustion engine can be, for example, a diesel engine or a gasoline engine. The internal combustion engine generates an exhaust gas flow 35, which is discharged in the exhaust pipe 3.

[0056] An exhaust flap 7 is located in the exhaust pipe 3, the rotation angle of which can be influenced within the exhaust pipe 3 by means of an actuator 70. The exhaust flap 7 generates exhaust back pressure, thus causing upstream ram pressure and downstream negative pressure. The exhaust flap 7 is installed between the inlet 21 and the outlet 22 of the heating catalyst 2. In other embodiments, a pressure difference between the inlet 21 and the outlet 22 can also be generated by a device other than an exhaust flap 7, for example, the turbine of a turbocharger.

[0057] The heating catalyst 2 has a housing 25, which has an inlet 21 and an outlet 22. By partially closing the exhaust flap 7, an overpressure is generated at the inlet 21, which causes a partial flow 351 of the total exhaust gas flow 35 to enter the housing 25 of the heating catalyst 2 through the inlet 21. Thus, the partial flow 351 of the exhaust gas through the housing 25 of the heating catalyst 2 can be influenced by the position of the exhaust flap 7. The partial flow passes through the housing 25 of the heating catalyst 2 and is partially or completely converted. The products leave the housing 25 via the outlet 22 downstream of the inlet 21. The product 352 can be a hot gas or a reformate, or... containing a synthesis gas which serves to supply thermal energy to an exhaust gas aftertreatment device not shown in Figure 1.In some versions, instead of the exhaust flap 7, another device can be used which creates a pressure difference between inlet 21 and outlet 22, for example the turbine of an exhaust gas turbocharger.

[0058] Inside the housing 25 is a catalyst support 5. The catalyst support 5 can contain or consist of a porous material, for example, a porous molded body, a knitted fabric, a braid, a nonwoven fabric, a woven fabric, a knitted fabric, or a sheet metal structure. The catalyst support 5 can either be catalytically active itself or be provided with a catalytically active coating.

[0059] A fuel plate 6 is located on one side of the catalyst carrier 5. A perforated plate 4 is located on the opposite side of the catalyst carrier 5. The perforated plate 4 has a plurality of through-holes 41 through which the exhaust gas or the partial flow 351 can enter the catalyst carrier 5. The exhaust gas supplied to the catalyst carrier 5 in this way serves as an oxidizing agent. If the residual oxygen content of the exhaust gas is too low, ambient air can also be supplied to the heating catalyst. An embodiment of the perforated plate 4, which can be used in at least some embodiments of the heating catalyst, is explained in more detail in connection with Figures 3 and 4.

[0060] A fuel plate 6 is arranged on the opposite side of the catalyst support 5. Fuel is supplied to the fuel plate 6 via a fuel line 62, which is connected to an optional fuel pump 65. The fuel plate 6 is designed and intended to distribute the fuel within the plane defined by the fuel plate 6, so that it can be vaporized there by the application of heat and supplied to the catalyst support 5 in gaseous form. After the fuel has reacted at the catalyst or the catalyst support 5, it leaves the heating catalyst 2 as product gas 352. One possible embodiment of a fuel plate 6, which can be used in at least several embodiments, is explained in more detail with reference to Figure 2.

[0061] Figure 2 illustrates one embodiment of a fuel plate 6 in more detail. Figure 2 shows a top view of a fuel plate. As can be seen from Figure 2, the fuel plate 6 in the illustrated embodiment is approximately circular. In other embodiments, the fuel plate can also be polygonal. The perforated plate 4 and / or the catalyst carrier 5 and / or the housing 25 can optionally also be polygonal in this case. The heating catalyst 2 and / or the fuel plate 6 are designed and intended to be oriented approximately vertically when the heating catalyst is in operation. Thus, gravity acts within the plane defined by the fuel plate 6. Figure 2 shows the side of the fuel plate 6 facing the catalyst carrier 5.

[0062] As can be seen in Figure 2, a plurality of channels 61 are incorporated into the fuel plate 2. The channels 61 serve as a transport device that distributes the applied fuel within the plane defined by the fuel plate. This uniform distribution prevents overheating in certain areas of the catalyst support as well as the formation of coking or deposits due to cold spots. The channels 61 shown in Figure 2 thus result in a uniform temperature distribution within the heating catalyst.

[0063] The channels 61 comprise at least one first channel 611, which originates from a bore 63. The bore 63 extends as a through-bore from the side of the fuel plate facing away from the catalyst support 5 to the side facing the catalyst support 5. The bore 63 is connected to the fuel line 62, so that the fuel, which is supplied by the optional fuel pump 65, can exit the bore 63. The exiting fuel is received by the first channel 611. As shown in Figure 2, the fuel plate in the illustrated embodiment has two first channels 611a and 611b, which are arranged symmetrically to the bore 63. In other embodiments, a larger number of bores and / or a larger or smaller number of first channels 611 may be present.

[0064] In the illustrated embodiment, the first channel 611 is inclined at approximately 20° to 30° to the horizontal in the installed position of the heating catalyst 2. This causes the fuel to flow through the first channel 611 by gravity.

[0065] A plurality of second channels 612 branch off from the first channel 611, which, in the installed position of the heating catalyst 2, are inclined at approximately 40° to approximately 90° to the horizontal. In the illustrated embodiment, the second channels 612 essentially run vertically downwards, although they have further structures to reduce the flow velocity, as described below. Due to the basic direction, which is essentially vertical downwards, the fuel is distributed evenly along the fuel plate, both in width and height. The channels 611 can be designed such that, at partial load, the fuel is already completely vaporized before it reaches the end of the second channels 612. In this respect, only a portion of the fuel plate 6 is actually used for fuel vaporization.With higher power output and higher fuel supply, an increasingly larger area is put into operation until the fuel reaches the ends of the second channels 612 or has completely evaporated shortly before.

[0066] Furthermore, it is evident that the second channels 612 possess optional structures for reducing the flow velocity. For this purpose, the second channels 612 are subdivided into a plurality of first and second longitudinal sections along their course. The second channels 612 also exhibit a plurality of branching points. Between adjacent branching points, the first and second longitudinal sections initially diverge and then converge. Starting from the branching point above, the first and second longitudinal sections diverge. After a predetermined length, the channel makes a bend, so that the subsequent longitudinal sections again converge towards the downstream branching point.

[0067] In some embodiments, adjacent first and second longitudinal sections can have an angle of approximately 70° to approximately 110°. In the illustrated embodiment, the first and second longitudinal sections form an angle of approximately 90°, thus forming approximately a square. In other embodiments, the first and second longitudinal sections can also form a rectangle or a rhombus. By varying the inclination, the influence of gravity can be controlled, so that the flow velocity of the fuel in the second channels 612 can be slowed down or increased. The angle between adjacent first and second longitudinal sections, as well as their length and the number of branching points, can be optimized in computer simulations to create an optimal flow field on the fuel plate for a specific heating catalyst in a specific application.

[0068] Furthermore, it is evident that the width of the first channels 611 decreases starting from borehole 63. This takes into account the fact that the entire supplied fuel quantity must be transported at the beginning of the first channels 611a, 611b. As the length of the first channel 611 increases, more and more fuel is discharged into the second channels 612, so that the transported fuel quantity decreases. For this, only a smaller cross-section of the first channel 611 is required. Alternatively or additionally, the depth of the channels 61 can also decrease along their length. In some embodiments, the width of the first channel 611 can vary at a constant depth, whereas the second channels 612 have a constant width at a continuously decreasing depth.

[0069] Figures 3 and 4 illustrate one embodiment of a perforated plate 4. Figure 3 shows the perforated plate in a view together with the fuel plate, which is concealed by the perforated plate and the catalyst carrier in its installed position. Figure 4 shows the perforated plate 4 alone. The perforated plate 4 has a plurality of through-holes 41 through which the oxidizing agent is supplied to the catalyst carrier 5. Exhaust gas or ambient air can be used as the oxidizing agent. As can be seen in Figure 3, the through-holes 41 are arranged in rows that run approximately horizontally. Deviations of up to approximately 15° can still be considered horizontal for the purposes of this description.

[0070] Furthermore, the through-holes 41 of a row 412 are optionally offset from the through-holes 41 of an adjacent row 411. This can improve the backflow over the catalyst support and / or the mixing of the product gas.

[0071] Figure 3 further shows four reaction zones 421, 422, 423, and 424. In each reaction zone, the number and / or diameter of the through-holes is optimized so that different fuel / air ratios develop in different zones of the catalyst support to enable optimized operation of the heating catalyst. In some embodiments of the invention, the size and design of the reaction zones 421, 422, 423, and 424 can be adapted to the specifications of the fuel plate to enable optimized operation of the heating catalyst. In some embodiments of the invention, more or fewer reaction zones may also be present. As explained above, the heating catalyst can be operated in two different operating states, the first operating state enabling the production of a hot gas and the second operating state enabling the production of a product gas in the form of a reformate or...a synthesis gas is made possible. In the first operating state, the first zone 421, which is included in the fuel inlet through bore 63, can be configured as an evaporation zone. There, at a fuel / air ratio X of approximately 0.1 to approximately 0.3, a temperature of approximately 380° to approximately 685°C can develop.

[0072] The second zone 422 can be used as the main oxidation zone, where the fuel / air ratio X is approximately 4.5 and a temperature of approximately 550°C to approximately 900°C can develop.

[0073] The optional fourth zone 424 can be used as a calming zone. In some versions, neither fuel nor oxidizer is supplied to this zone. However, since reactions continue to occur on the catalyst applied to the catalyst support, any remaining hydrocarbons in the hot gas can be further oxidized in the fourth zone to keep them away from downstream components of the exhaust system.

[0074] In the second operating state, the first zone 421 can again be used as an evaporation zone, although with a fuel / air ratio X of approximately 0.01 to 0.1, a lower temperature of approximately 300° to approximately 500° can be established. The perforated plate shown is designed such that a proportion of between approximately 5% and approximately 27% of the mass flow of the oxidizing agent flows through the through-holes of the first zone.

[0075] The second zone 422 serves for further vaporization and partial oxidation or reforming to produce a product gas. Due to the greater number and / or the larger diameter of the through-holes compared to the first zone, the fuel / air ratio X here is approximately 0.1 to approximately 0.2, resulting in a temperature of approximately 380° to approximately 600°. The illustrated perforated plate is designed such that a proportion of between approximately 60% and approximately 94% of the mass flow of the oxidizing agent passes through the through-holes of the second zone.

[0076] The optional fourth zone 424 can be used as a settling zone. In some embodiments, neither fuel nor oxidizer is supplied in this zone. However, since reactions continue to occur on the catalyst applied to the catalyst support, the product gas in the fourth zone can be optimized and / or catalyst slip can be avoided.

[0077] The switching between operating states is achieved on the one hand by the amount of oxidizer or exhaust gas supplied, which can be adjusted, for example, by the position of the exhaust flap 7. On the other hand, the fuel quantity can also be controlled or regulated. Due to the different number and / or size of the through-holes 41, a different fuel / air ratio X is established in the first zone 421, the second zone 422, and the fourth zone 424, so that the fuel is converted over the entire surface of the catalyst carrier 5 or the fuel plate 6 without coking or deposits forming in cold areas or individual areas overheating and damaging the catalyst.

[0078] Figure 3 further illustrates a third zone 423. Within the third zone 423, the through-holes 41 are designed to generate a flushing flow in the fuel-free edge region of the fuel plate. This prevents dead zones in the heating catalyst 2. The perforated plate shown is designed such that a proportion of between approximately 2% and approximately 15% of the mass flow of the oxidizing agent flows through the through-holes of the third zone.

[0079] Naturally, the invention is not limited to the embodiments shown. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Insofar as the claims and the foregoing description define "first" and "second" embodiments, this designation serves to distinguish between two similar embodiments without establishing a hierarchy.

Claims

Claims 1. Heating catalyst (2) for an exhaust aftertreatment device or a reformer, which is configured to react fuel with an oxidizing agent, wherein the heating catalyst (2) has a housing (25) which has an inlet (21) and an outlet (22), wherein the inlet (21) is configured to supply the oxidizing agent and the outlet (22) is configured to discharge a product gas (352), and wherein the heating catalyst (2) further comprises a catalyst support (5) arranged in the housing (25), wherein a fuel plate (6) is arranged on one side of the catalyst support (5), which is configured to supply the fuel to the catalyst support (5), and a perforated plate (4) is arranged on one side of the catalyst support (5) opposite the fuel plate (6), which is configured to supply the oxidizing agent to the catalyst support (5), characterized in thatthat the perforated plate (4) has a plurality of through holes (41), which in at least a first zone (421) of the perforated plate (4) have a smaller number and / or a smaller area density and / or a smaller diameter and which in at least a second zone (422) have a larger number and / or a larger area density and / or a larger diameter .

2. Heating catalyst (2) according to claim 1, characterized in that the second zone (422) has a larger area than the first zone (421).

3. Heating catalyst (2) according to claim 1 or 2, characterized in that in the installation position of the heating catalyst (2) the first zone (421) is located above the second zone (422).

4. Heating catalyst (2) according to claims 1 to 3, characterized in that the perforated plate (4) has a third zone (423) in which the through-holes (41) are arranged to generate a flushing flow in the fuel-free marginal area.

5. Heating catalyst (2) according to claims 1 to 4, characterized in that the through-holes (41) are arranged in rows (411, 412) at least in the second zone (422), which in the installation position of the heating catalyst (2) extend at about 0° to about 15° to the horizontal.

6. Heating catalyst (2) according to one of claims 1 to 4, characterized in that the through-holes (41) are arranged in rows (411, 412) at least in the second zone (422), which in the installation position of the heating catalyst (2) extend at about 0° to about 15° to the horizontal, wherein the through-holes (41) of a row (412) are offset against the through-holes (41) of an adjacent row (411).

7. Heating catalyst (2) according to one of claims 1 to 6, characterized in that the perforated plate (4) has a fourth zone (424) in which no through holes (41) are present.

8. Heating catalyst (2) according to one of claims 1 to 7, characterized in that the diameter of the through-holes (41) is between about 2.0 mm and about 2.6 mm or between about 2.3 mm and about 4.0 mm or between about 2.6 mm and about 3.7 mm.

9. Heating catalyst (2) according to one of claims 1 to 8, characterized in that the perforated plate (4) is configured to allow a proportion between about 1% and about 40% or a proportion between about 5% and about 27% of the mass flow of the oxidizing agent through the through-holes (41) of the first zone (421).

10. Heating catalyst (2) according to one of claims 1 to 9, characterized in that the perforated plate (4) is arranged so that a proportion between about 50% and about 97% or a proportion between about 60% and about 94% of the mass flow of the oxidizing agent flows through the through-holes (41) of the second zone (422).

11. Heating catalyst (2) according to one of claims 1 to 10, characterized in that the perforated plate (4) is arranged to allow a proportion between about 0% and about 20% or a proportion between about 2% and about 15% of the mass flow of the oxidizing agent to flow through the through-holes (41) of the third zone (423).

12. Heating catalyst (2) according to claims 1 to 11, characterized in that the perforated plate (4) is arranged such that a proportion between about 0% and about 2% or a proportion between about 0% and about 0.5% or a proportion of about 0% of the mass flow of the oxidizing agent flows through the fourth zone (424) of the perforated plate (4).

13. Internal combustion engine with at least one heating catalyst (2) according to any one of claims 1 to 12.

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