AT513932A1 - Catalyst unit for a high temperature fuel cell system - Google Patents

Abstract

The invention relates to a catalyst unit (10) for a high-temperature fuel cell system with a reforming catalyst (11) for processing a fuel for the fuel cell and an oxidation catalyst (12) for the exhaust gas aftertreatment of the fuel cell, wherein the oxidation catalyst (12) is annular around the cylindrically designed reformer catalyst (11). 11) is arranged. According to the invention, the gas paths of the oxidation catalytic converter (12) and of the reforming catalytic converter (11) are separated by a metal tube (13) accommodating the reforming catalyst (11), the metal tube (13) having a sleeve (14) comprising a housing for the reforming catalytic converter (11). and an inner tube (15) forming the inner wall of the annular oxidation catalyst (12).

Description

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The invention relates to a catalyst unit for a high-temperature fuel cell system with a reforming catalyst for processing a fuel for the fuel cell and an oxidation catalyst for the exhaust gas aftertreatment of the fuel cell, wherein the oxidation catalyst is arranged annularly around the cylindrically designed reforming catalyst.

The catalyst unit described above can be used, for example, in a compact power unit (APU) of a motor vehicle, where it serves to provide electrical and thermal energy.

Thus, for example, from AT 502 131 Bl a catalyst unit for a high-temperature fuel cell system is known, in which a cylindrical reforming catalyst is incorporated in an oxidation catalyst. In this case, a cylindrical reforming catalyst is arranged in a combustion chamber for a flame burner, which is annularly surrounded by an oxidation catalyst. The unused fuel components of the anode exhaust gas are fed together with the cathode exhaust gas into the combustion chamber and post-treated in the oxidation catalyst. The gaseous products after the catalytic conversion reach via peripheral openings of the oxidation catalyst in an annular chamber and leave with the release of heat to a plate heat exchanger, the power generation unit.

From EP 2 255 872 A2, an oxidation catalyst having a plurality of reaction zones is known. The gases to be treated initially flow through a cylindrical, inner catalyst, are then deflected and passed in countercurrent to an annular, outer catalyst region. The two areas are separated by a cylindrical partition. Both the inner catalyst and the outer catalyst have a metallic carrier (mash) layer for the catalytic substance. The illustrated, series connection of several oxidation stages of an oxidation catalyst to increase the efficiency of the device.

The object of the invention is to develop a catalyst unit for a high-temperature fuel cell system of the type mentioned above such that a compact structural unit, in particular for use in an APU, is 2/20, wherein improvements in the heat output are as good as possible Maintenance and care of the unit should be achieved.

This object is achieved in that the gas paths of the oxidation catalyst and the reforming catalyst are separated by a metal catalyst receiving the reformer catalyst, wherein the metal tube has a sleeve which forms a housing for the reforming catalyst, and an inner tube which forms the inner wall of the annular oxidation catalyst , In particular, it is provided that the reforming catalyst is exchangeable used in the annular oxidation catalyst. Despite their compact design, both catalysts are thus fixed in independent housings. The reforming catalyst can thus be easily replaced if necessary.

In order to accelerate and optimize the heat exchange within the catalyst unit, it is provided according to the invention that the oxidation catalyst and / or the reforming catalyst have a metallic catalyst carrier, the sleeve being in thermal contact with the catalyst carrier of the reforming catalyst and the inner tube with the catalyst carrier of the oxidation catalyst.

It is particularly advantageous if the catalyst support of the oxidation catalyst and the catalyst support of the reforming catalyst are connected by welding to the respectively adjacent parts of the metal pipe. By directly welding the substrates in the housing of the reforming catalyst or the oxidation catalyst can be omitted a conventional sealing mat, which hinders the heat exchange. A particular advantage of this embodiment is that the temperature profile of the catalyst unit (axial and radial) can be homogenized by the improved thermal conductivity. The improved heat dissipation in particular hot zones (hot spots) can be prevented in the two catalysts.

According to one embodiment variant of the invention, the gas distributor housing arranged at the beginning of the reforming catalyst (reformermanifold) can have an annular space into which the supply line for the fuel-gas mixture to be treated opens, starting from the annular space radial access openings from the annular space to the inlet surface of the reforming catalyst 3/20. ..- 3 ..-..-..-..-. •. By this measure, the gas flow through the catalyst is achieved.

According to a further embodiment of the gas distributor housing, the axial distance a of the tangential inlet of the supply line for the fuel-gas mixture from the inlet surface of the reforming catalyst to the diameter D of the reforming catalyst, a ratio a: D in the range of 0.2 to 1, preferably from 0 , 3 to 0.6, whereby a desired ring flow on the input side of the reforming catalyst established. The tangential inlet may open into a cylindrical or frusto-conical region of the gas distributor housing.

The invention will be explained in more detail below with reference to partly schematic drawings. Show it:

1 shows a catalyst unit according to the invention for a high-temperature fuel cell system in a three-dimensional, partially cutaway representation,

2 shows a schematic representation of the operating principle and the installation position of the catalyst unit according to FIG. 1, FIG.

3 is a sectional view of the catalyst unit of FIG. 1,

Fig. 4 shows a variant of the catalyst unit of FIG. 1 in a three-dimensional representation.

5 shows a first embodiment variant of a gas distributor housing (reformer manifold) for the reformer catalyst of the catalyst unit in a sectional view along the line V-V in FIG. 6, FIG.

Fig. 6, the gas distributor housing of FIG. 5 in an axial plan view, as well

Fig. 7 shows a second embodiment of a gas distributor housing (Reformermanifold) for the reformer catalyst of the catalyst unit in an axial section. 4/20 4

FIG. 1 shows a catalactic inventive method for a high-temperature fuel cell system (not further described here) with a cylindrical reforming catalyst 11 and an oxidation catalytic converter 12 annularly surrounding the reforming catalyst. The reforming catalyst 11 is used to treat the fuel for the fuel cell BZ (see Fig. 2), which is supplied with an oxidizing agent via the supply line 23 and distributed as homogeneously as possible over the entry surface of the reforming catalyst 11 with a frusto-conical gas distributor housing or reformer manifold 24. The oxidation catalyst 12 is used for exhaust aftertreatment of a starter burner and the fuel cell system.

In the illustrated embodiment, the gas paths of the oxidation catalyst 12 and the reforming catalyst 11 are separated by a reforming catalyst 11 receiving metal tube 13 which is designed in two parts and a sleeve 14 which forms a housing for the reforming catalyst 11, and an outer tube 15, the Inner wall of the annular oxidation catalyst 12 forms. The reforming catalyst 11 can thus be used interchangeably in the annular oxidation catalyst 12.

The oxidation catalyst 12 and / or the reforming catalyst 11 preferably have a metallic catalyst carrier 16, 17, wherein the sleeve 14 of the metal tube 13 is in thermal contact with the catalyst carrier 16 of the reforming catalyst 11 and the outer tube 15 with the catalyst carrier 17 of the oxidation catalyst 12. Thus, far better values for the heat transfer can be achieved than with the use of ceramic substrates, which are usually sealed with a sealing mat to the housing.

Preferably, the catalyst support 17 of the oxidation catalyst 12 and the catalyst support 16 of the reforming catalyst 11 of a metallic wire mesh or a metallic lamellar structure, which are connected by welding to the respective adjacent parts 14, 15 of the metal tube 13.

The sleeve 14 of the reforming catalyst 11 can be interchangeable inserted into the inner tube 15 and the inner wall of the annular oxidation catalyst 12 by means of a clearance, for example in the range of 0.2 mm to 1.5 mm. 5/20 ·· -5

According to the invention the sleeve 14 * of the * Rfefwmerk'atel ysators 11 or the inner tube 15 of the oxidation catalyst 12 has a sealing flange 18, wherein between the sealing flange 18 and the end of the inner tube 15 in a corresponding recess a ring seal 19, for example, a swelling mat is provided , For assembly and disassembly purposes may be formed on the sleeve 14 of the reforming catalyst 11 engaging elements or engagement holes 20 for a trigger tool.

2 shows a schematic overview of the arrangement of the catalyst unit 10 according to the invention, including cylindrical reforming catalyst 11 and annular oxidation catalyst 12 in combination with a high-temperature fuel cell system BZ with the anode side A and the cathode side K.

The fuel F is supplied during the starting cycle by means of a fuel pump 35 to a starter burner 26, the exhaust gases are fed into the annular oxidation catalyst 12 and heat the centrally located reforming catalyst 11. Furthermore, the fuel F is supplied by means of fuel pump 36 of the evaporation unit 37 and introduced into the anode exhaust gas of the recirculation 27, and fed together with the required oxidant, for example air L, by means of compressor 28 to the gas distributor housing or Reformermanifold 24 of the reforming catalyst 11.

The compressor 29 serves to supply the oxidizing agent (e.g., air L) to the cathode side K of the fuel cell system BZ, the oxidizer being passed through a heat exchanger 38 which is exhausted by the exhaust gases of the oxidation catalyst 12. In the starting phase, the starter burner 26 is supplied via the compressor 29 with the required air.

Fig. 3 shows a variant of the catalyst unit 10 according to the invention in an enlarged sectional view. The metal tube 13, which separates the gas paths of the oxidation catalyst 12 and the reforming catalyst 11, consists essentially of the sleeve 14, which forms a housing for the reforming catalyst 11, as well as the inner tube 15, the inner wall of the annular 6/20

Oxidation catalyst 12 forms. The "oil jet" EJichtflaf> 3ch 18 here has a seal 25 to the end face of the inner tube 15.

1, in which both the oxidation catalytic converter 12 and the reforming catalytic converter 11 have a metallic catalyst carrier 16, 17, the gas paths of the two catalytic converters 11 being separated by a metal tube 13 accommodating the reforming catalyst 11 are, which is in thermal contact with the catalyst support 17 of the oxidation catalyst 12 and the catalyst support 16 of the reforming catalyst 11, for example by welding.

FIGS. 5 to 7 show two alternative embodiments for the gas distributor housing 24, which is arranged on the input side of the reforming catalytic converter 11. It serves to distribute the fuel-gas mixture to be treated over the entire inlet surface 30 of the reforming catalyst 11, wherein the feed line 23 for the fuel-gas mixture radially or tangentially with respect to the axis 11 'of the reforming catalyst 11 in the gas distributor housing 24th opens.

In the embodiment variant shown in FIGS. 5 and 6, the gas distributor housing 24 has an annular space 32, into which the supply line 23 for the fuel-gas mixture opens, for example, radially, starting from the annular space 32 radial access openings 33 in the form of a perforated ring are arranged from the annular space 32 to the entrance surface 30 of the reforming catalyst 11, so that the reforming catalyst 11 is applied as uniformly as possible with the mixture of anode exhaust gas, vaporized fuel and oxidant. The Reformermanifold of FIG. 5 and Fig. 6 is characterized by a compact design with low axial height. In tube 34, a measuring device, e.g. a temperature sensor, are introduced into the annulus 32 (see Fig. 6).

7, the axial distance a of the tangential inlet 31 of the supply line 23 for the fuel-gas mixture from the inlet surface 30 of the reforming catalyst 11 to the diameter D of the reforming catalyst 11 has a ratio a: D in the range of 0.2 to 1, preferably from 0.3 to 0.6, so that an optimal annular flow can form in the interior of the Reformermanifolds 24, which generates a homogeneous gas distribution at the inlet surface 30 of the reforming catalyst 11. Advantages are a compact design and low pressure losses. 7/20 • ·· ···················································

Preferably, the gas distributor housing may be made or connected to the inner wall of the annular oxidation catalytic converter by means of welding

Claims (16)

1. Catalyst unit (10) for a high-temperature fuel cell system with a A reformer catalyst (11) for treating a fuel for the fuel cell and an oxidation catalyst (12) for the exhaust gas aftertreatment of the fuel cell, wherein the oxidation catalyst (12) is arranged annularly around the cylindrical reformer catalyst (11), characterized in that the gas paths of the oxidation catalyst ( 12) and the reforming catalyst (11) are separated by a metal pipe (13) receiving the reforming catalyst (11), the metal pipe (13) having a sleeve (14) forming a housing for the reforming catalyst (11) and an inner pipe (15) forming the inner wall of the annular oxidation catalyst (12). Second catalyst unit (10) according to claim 1, characterized in that the reforming catalyst (11) is interchangeable in the annular oxidation catalyst (12) can be used. 3. Catalyst unit (10) according to claim 1 or 2, characterized in that the oxidation catalyst (12) and / or the reforming catalyst (11) comprises a metallic catalyst carrier (16, 17), wherein the sleeve (14) with the catalyst carrier (16 ) of the reforming catalyst (11) and the inner tube (15) with the catalyst support (17) of the oxidation catalyst (12) are in thermal contact. 4. catalyst unit (10) according to claim 3, characterized in that the catalyst support (17) of the oxidation catalyst (12) and the catalyst support (16) of the reforming catalyst (11) are connected by welding to the respective adjacent parts of the metal tube (13). 5. Catalyst unit (10) according to claim 3 or 4, characterized in that the catalyst support (17) of the oxidation catalyst (12) and the catalyst support (16) of the reforming catalyst (11) consist of a metallic wire mesh or a metallic lamellar structure. 9/20 • ···· I · · · ··· · · · ······································· 6. Catalyst unit (10) after a cter response ·! Ws * j / »characterized in that the sleeve (14) of the reforming catalyst (11) by means of a clearance, for example in the range of 0.2 mm to 1.5 mm, in the inner tube (15) of the oxidation catalyst (12) is inserted , 7. catalyst unit (10) according to one of claims 1 to 6, characterized in that the sleeve (14) of the reforming catalyst (11) or the inner tube (15) of the oxidation catalyst (12) has a sealing flange (18), and between the sealing flange (18) and the end of the inner tube (15) an annular seal (19), for example, a swelling mat, is provided. 8. catalyst unit (10) according to one of claims 1 to 7, characterized in that on the sleeve (14) of the reforming catalyst (11) engaging elements or engagement openings (20) are formed for a trigger tool. 9. catalyst unit (10) according to one of claims 1 to 8, characterized in that the oxidation catalyst (12) has a tubular outer wall (21) with exhaust outlet openings (22) in an over the catalyst carrier (17) projecting region. 10. A high temperature fuel cell system catalyst unit (10) comprising a fuel cell reforming catalyst (11) and an oxidation catalyst (12) for the fuel cell exhaust gas treatment, wherein the oxidation catalyst (12) is annularly formed around the cylindrically shaped reformer catalyst (11 ), characterized in that both the oxidation catalyst (12), and the reforming catalyst (11) have a metallic catalyst carrier (16, 17), wherein the gas paths of the oxidation catalyst (12) and the reforming catalyst (11) by a reforming catalyst (11) receiving metal tube (13) are separated, which is in thermal contact with the catalyst carrier (17) of the oxidation catalyst (12) and the catalyst carrier (16) of the reforming catalyst (11). 11. catalyst unit (10) according to claim 10, characterized in that the oxidation catalyst (12) and / or the reforming catalyst (11) a 10/20 10 * metallic catalyst carrier (16, 1-7 ^ waetsenj'wetfehdas metal tube (13) the catalyst support (16) of the reforming catalyst (11) is in thermal contact with the catalyst support (17) of the oxidation catalyst (12). 12. catalyst unit (10) according to claim 11, characterized in that the catalyst carrier (17) of the oxidation catalyst (12) and the catalyst carrier (16) of the reforming catalyst (11) are connected by welding to the metal tube (13). 13. catalyst unit (10) according to one of claims 1 to 12, characterized in that the reforming catalyst (11) on the input side a gas distributor housing (24) which the fuel-gas mixture to be treated over the entire inlet surface (30) of the reforming catalyst (11 ), wherein the supply line (23) for the fuel-gas mixture opens radially or tangentially with respect to the axis (11 ') of the reforming catalyst (11) in the gas distributor housing (24). 14. Catalyst unit (10) according to claim 13, characterized in that the gas distributor housing (24) has an annular space (32) into which the supply line (23) opens for the fuel-gas mixture, starting from the annular space (32) radial Access openings (33) from the annular space (32) to the inlet surface (30) of the reforming catalyst (11) are arranged. 15. Catalyst unit (10) according to claim 13, characterized in that the axial distance a of the tangential inlet (31) of the feed line (23) for the fuel-gas mixture from the inlet surface (30) of the reforming catalyst (11) to the diameter D. of the reforming catalyst (11) has a ratio a: D in the range of 0.2 to 1, preferably 0.3 to 0.6. 16. catalyst unit (10) according to any one of claims 13 to 15, characterized in that the gas distributor housing (24) with the inner wall of the annular oxidation catalyst (12) is made in one piece or connected by welding. 2013 02 04; Lu ipl-lnq A-mti V ·; 11/20 i £ fctertahiitar & * jtrte: