DE10111259A1 - Hydrogen containing gas supply unit comprises a vaporizer, a reformer, a catalytic burner and a unit for the selective oxidation of carbon monoxide - Google Patents

Abstract

An arrangement for producing a hydrogen containing gas from a hydrocarbon, for supplying a vehicle fuel cell, comprises a vaporizer, a reformer, a catalytic burner and a unit for the selective oxidation of carbon monoxide in the hydrogen containing gas. The selective oxidation unit (13) and the catalytic burner (14) have a heat transfer contact to the reformer (9, 11). The combustion gas for the burner contains gases from a cathode and/or anode chamber of the fuel cell.

Description

The invention relates to a device for generating a hydrogen-containing gas from a coal water serstoff, according to the closer in the preamble of claim 1 defined art.

JP 08-301601 shows a combination of one two-part reformers, the two parts of Re formers around an intermediate chamber for conversion tion of carbon monoxide are arranged. In the cam mer for converting carbon monoxide is under Add water that comes from the reformer the gas contained carbon monoxide via a water gas Shift reaction oxidized to carbon dioxide, whereby au in addition, hydrogen is produced again.

JP 11260387 A is a selective oxidation stage known, which is a combination of catalytic downstream burner and reformer. The se The selective oxidation stage is done via a cooler  in the heat management of a heat transfer circuit involved. As the ideal function of the selective Oxidation a comparatively low temperature of about 200 ° C is required, the selective oxide tion level to this ideal operating temperature cools while in the area of the burner and the refor far higher temperatures. As Beson Unity of the above structure can also ge will see that the burner in the japani writing at least partially by means of exhaust gases the fuel cell, which with the by building generated hydrogen-containing gas is supplied, be is drivable.

JP 11021103 and JP 11043304 also show superstructures in which all elements for Operation of the gas generation system around a burner are ordered. The burner ensures an energy Gie supply of the entire gas generation system.

The general state of the art is also said to the DE 197 27 581 A are referred, which one Construction from selective oxidation stage and reformer shows, this in a thermally conductive contact stand each other in the exothermic Oxi dation level arising energy, i.e. the endothermic working reformer, is feedable.

The above-mentioned embodiments of a gas generator system or the heating of a reformer in egg Nem gas generation system all have the disadvantage that they are comparatively large and space-consuming Have structure, and that they for safe and the same constant start of the reformer, and especially the  selective oxidation level are not suitable. Übli This is why the gas generator is started another cold startable reactor for Generation of hydrogen is required, which for example as a partial oxidation state or the like can be trained.

In normal operation, the energy must then be provided lung, which for the reforming reactions in the Reformer is required through the selective oxidati onsstufe, this much more oxygen or air be performed as for the oxidation of the in the Re carbon monoxide actually present would be dig. This will add additional gas provided hydrogen oxidized. Due to this fact, an additional production of Hydrogen needed, which is why the reformer turned out larger must be placed or its catalyst loaded higher becomes, which in turn, the life of the catalyst negatively influenced. The overall energetic effect degrees, the lifespan and / or the space requirement of systems of this kind change into disadvantages liger way.

It is therefore the object of the invention to produce a gas system, especially with regard to energy supply care of the reformer, so that the in energy present in the system is ideal for generating hydrogen-containing gas is used, and that about it offers a very small and compact structure, which is space-saving in corresponding systems, for example driven by a fuel cell bene motor vehicles, can be integrated.  

According to the invention, this task is characterized by the drawing part of claim 1 mentioned features ge solves.

The fact that the at least one reformer in both a heat transfer contact with the device selective oxidation as well with the at least one catalytic burner, you can ensure who that at least one reformer is always ideal with Heat is supplied. Especially in the event of a cold start can research the whole of the catalytic burner thermal energy until the be necessary temperature is available and the refor and the selective oxidation stage the.

In addition to a structural simplification of the erge So there are also advantages in terms of ver direction drive.

During normal operation of the system, the ka talytic burner with the exhaust gases from the Ka and the anode compartment of the fuel cell ben. This can in the exhaust gases of the fuel cell in the form of hydrocarbon and hydrogen residues available energy also for heating the refor be used. When starting the device for Generation of the hydrogen-containing gas can also which is carried over the cathode chamber of the fuel cell air or oxygen flow to operate the pre direction are used, so that here further help energy to provide a corresponding kompri mated air or oxygen flow can be saved can.  

The device according to the invention therefore decides advantages in terms of the required construction space, management and energy use on.

In a particularly favorable embodiment of the Er invention is the reformer, the institution for selection ven oxidation and the catalytic burner in one a type of plate heat exchanger gate arranged.

In particular, the heat transfer between the individual elements as well as the requirements regarding the This further optimizes installation space.

He further advantageous embodiments of the invention give themselves from the remaining subclaims as well those shown below with reference to the drawing Embodiments.

It shows:

Figure 1 shows a possible structure of the device according to the invention for generating a hydrogen-containing gas.

Fig. 2 shows an alternative embodiment of the device for generating a hydrogen-containing gas; and

Fig. 3 shows a reactor unit with reformer, catalytic cal burner and devices for selective oxidation.

Fig. 1 now shows a possible structure of a Vorrich processing for generating a hydrogen-containing gas from a hydrocarbon material for supplying an internal cell 1.

The fuel cell 1 has a cathode compartment 2 and an anode compartment 3 . Of course, the fuel cell 1 can be designed in the usual form as a fuel cell stack, which then each has several of these rooms, which, however, can be connected in the manner of a parallel connection with respect to their gas flows to form a "room".

When operating the fuel cell 1 4 oxygen or oxygen-containing gas, such as. B. air, introduced into the cathode compartment 2 , while a line 5 hydrogen-containing gas from the device for generating the hydrogen-containing Ga ses are passed to the anode compartment 3 .

In the following, the well-known ore will now generation of a hydrogen-containing gas from a coal hydrogen, for example a liquid coal hydrogen, such as methanol or the like become.

In order to simplify the illustration, some of the subcomponents that are not absolutely necessary in the gas generation system are dispensed with and it is playfully assumed that a mixture of water and methanol is supplied to a evaporator 7 in the region of a line 6 . The evaporator 7 evaporates the mixture of water and hydrocarbon and feeds it via line 8 to a first reformer 9 . In the reformer 9 , the substances to be fed are reformed so that a hydrogen-containing gas is produced from the hydrocarbon / water mixture by means of a water-gas shift reaction. Via a further line 10 , this mixture, which is only partially converted in the region of the reformer 9, is passed into a second reformer 11 , in which, according to an identical or similar reaction, the conversion of the mixture into a predominantly hydrogen-containing gas follows. The line 10 does not have to be designed explicitly as a separate line element, as shown here, but it can also be a two-stage reformer which includes the first reformer 9 and the second reformer 11 in one unit, the two reformers then are in the flow direction of the gas or reformate one after the other.

From the reformer 11 , the reformate, which due to the processes known per se in the reformers has a comparatively high proportion of carbon monoxide, enters a device 13 for selective oxidation of the carbon monoxide. This is briefly referred to below as selective oxidation state 13 . From this selective oxidation stage 13 , the gas passes via line 5 to the anode compartment 3 of the fuel cell 1 . In the area of line 5 , a fine purification of the gas, not shown here, can be carried out, which, however, is not absolutely necessary for the basic principle of the structure. To provide the energy in the area of the first reformer 9 is the thermal energy generated by the selective oxidation of carbon monoxide in the selective oxidation stage 13 , since this selective oxidation is exothermic.

A catalytic burner 14 serves to provide the energy in the area of the second reformer 11 . The water catalytic burner 14 is supplied via line 15 with the exhaust gases from the cathode compartment 2 and the anode compartment 3 of the fuel cell. The exhaust gas from the cathode compartment 2 supplies the oxygen required for the combustion, while the exhaust gas from the anode compartment 3 generally contains a comparatively large amount of hydrogen and the reformers 9 , 11 do not fully convert hydrocarbon, which, at least during normal operation the device, contain sufficient energy to supply the second reformer 11 with the required thermal energy via the catalytic burner 14 .

The hot exhaust gases from the catalytic burner are then conducted via line 16 to the evaporator 7 in order to use their remaining energy content here to evaporate the liquid hydrocarbon or water. In the start-up phase of the fuel cell system and under correspondingly poor conditions, it may be necessary here for a further, optional burner 17 , which, for example, can also be configured as a catalytic burner, to be used in the region of the line 16 . To supply this burner 17 , additional fuel can then optionally be supplied, for example in the form of the liquid hydrocarbon. This optional supply of fuel is indicated at various possible points by the dashed units with the reference number "18".

The structure described now offers the very favorable possibility that the first reformer 9 , which is supplied with energy via the selective oxidation stage 13 , can be operated at a temperature which is comparatively low for reforming, for example at approximately 200 ° C., since this represents the ideal operating temperature for the selective oxidation state 13 . In the area of the second reformer 11 , the hydrogen / water mixture not yet reformed in the first reformer 9 can then be "reformed", this reformer, which is heated by the catalytic burner 14 , being operated at correspondingly higher temperatures.

Fig. 2 shows a similar structure, but here the only reformer 9 is formed together with the selective oxidation stage 13 and the catalytic burner 14 as a structural unit in heat-conducting contact with each other.

Otherwise, there are comparable components and the same reference number as in FIG. 1 was used for the respectively comparable components and lines. The structure should be traceable analogous to the structure mentioned above.

However, the conduit 15 is divided, in the illustrated construction in a line 15 a, which feeds the exhaust gas from the cathode chamber 2 of the fuel cell 1 in kata lytic burner 14, and a line 15 b, from the anode chamber 3 to the catalytic burner 14, on. In addition, a line 15 b 'is provided for supplying the burner 17 with residues from the exhaust gases of the anode space 3 of the fuel cell 1 . The burner 17 is seen in this construction according to FIG. 2 for supplying the evaporator 7 with thermal energy, but it can also be omitted here, as in FIG. 1. As in FIG. 1, however, there are also the optional points 18 for the subsequent introduction of fuel, for example in the form of the hydrocarbon, if this should be necessary, for example, in the starting phase or depending on the operational management of the fuel cell 1 .

In addition, the structure according to FIG. 2, in a form not shown, can have a reforming stage in the area of the line 12 and a fine cleaning for the refor mat in the area of the line 5 .

In Fig. 3, a reactor 19 can now be seen, which represents a principle indicated possibility of construction from the catalytic burner 14 , the reformer 9 and the selective oxidation stage 13 shown in FIG. 2.

The reactor 19 is constructed in the manner of a plate heat exchanger, this having three independent rooms, each of which is made up of sub-rooms connected in parallel. The rooms are arranged and interconnected in the manner shown here, with one of the reformers 9 , as an endothermic unit, always being arranged between two of the heat-supplying, exothermic units, i.e. the device for selective oxidation 13 and / or the catalytic burner 14 is. A temperature profile running across the individual rooms will be set in the reactor so that the ideal supply of the components with their most favorable temperature remains guaranteed.

Of course, it would be conceivable here to implement a structure which is oriented analogously to the structure according to FIG. 1 and in which in one area of the reactor reformer 9 and selective oxidation stages 13 are arranged, in the other area being rich of the reactor then reformer 9 or 11 and catalytic burner 14 could be arranged. The interconnection of the individual subchambers with each other would have to adapt accordingly here.

In addition to the very favorable embodiment when using such a reactor 19 in terms of the space required in the device for generating what was hydrogen-containing gas, there is a very good efficiency of the system, particularly when an anode lambda of the fuel cell 1 does not correspond to the operating conditions can or may be adapted to the energy requirements of the evaporator 7 .

In addition, overall a smaller reformer 9 , 11 or a lower load on the catalyst present in the reformer 9 , 11 is possible in the system, since less hydrogen has to be converted to provide the energy in the area of the selective oxidation stage 13 . Since this hydrogen therefore does not have to be generated in the area of the reformer 9 , 11 , the energy requirement of the overall system can also be reduced, since a not inconsiderable amount of energy would be necessary for the production of this hydrogen in the endothermic reformer 9 , 11 .

In particular, when the system is cold started, when the reactor 19 is used, the reformer 9 and the selective oxidation stage 13 can be heated directly via the burner 14 , which is very favorable for the time until the gas generation system can be started and for the emissions generated in this period effect. In addition, the energy contained in the hot gas stream can be used much better in this case, since it is used "not only" for heating the evaporator 7 , but also for heating the reactor 19 . As a consequence of this very favorable behavior with regard to cold starting, the use of cold-startable reforming components, such as the partial oxidation stage known for example from the prior art, for generating a hydrogen-containing gas can be dispensed with, so that system costs, system weight and installation space of the system can be further improved.

Claims (8)

1. Device for generating a hydrogen-containing gas from a hydrocarbon, for supplying a fuel cell, in particular in a motor vehicle, with at least one evaporator, at least one reformer, at least one catalytic burner and at least one device for the selective oxidation of gas in the hydrogen-containing gas Contained carbon monoxide, characterized in that the device ( 13 ) for selective oxidation and the at least one catalytic burner ( 14 ) have a heat-transferring contact with the at least one reformer ( 9 , 11 ), the combustion gas for the catalytic burner ( 14 ) Exhaust gases from a cathode ( 2 ) and / or anode space ( 3 ) of the fuel cell ( 1 ). 2. Device according to claim 1, characterized in that the reformer ( 9 ), the device ( 13 ) for selective oxidation and the catalytic burner ( 14 ) are arranged in a reactor constructed in the manner of a plate heat exchanger ( 19 ). 3. Apparatus according to claim 2, characterized in that in the reactor ( 13 ) the spaces for the reformer ( 9 ), the device ( 13 ) for selective oxidation and the catalytic burner ( 14 ) are each arranged in parallel to each other in kind that that each of the reformers ( 9 ) on one side one of the devices ( 13 ) for selective oxida tion and on the other side one of the catalytic burner ( 14 ) in a thermally conductive contact. 4. Device according to claim 1, characterized in that the reformer into two sub-reformer (9, 11) be divided is the first in the flow direction of a coming from the evaporator (7) gas stream part reformer (9) a heat transferring contact with said means ( 13 ) for selective oxidation, and wherein the in the direction of flow of the gases to the first of the partial reformer ( 9 ) to the closing second partial reformer ( 11 ) has a heat-transferring contact with the catalytic burner ( 14 ). 5. Device according to one of claims 1 to 4, characterized in that the exhaust gas from the fuel cell ( 1 ), if necessary, further fuel ( 18 ) can be supplied. 6. The device according to claim 6, characterized in that the fuel can be supplied in the form of the hydrocarbon  is. 7. Device according to one of claims 1 to 7, characterized in that a device for fine cleaning of the gases is arranged between the device ( 13 ) for selective oxi dation and the fuel cell ( 1 ). 8. Device according to one of claims 1 to 8, characterized in that the evaporator ( 7 ) can be heated by the exhaust gases of the at least one catalytic burner ( 14 ).