DE102006039039A1 - Heating of a catalyst stage mounted downstream of a reformer, comprises feeding of air as heat transfer medium into the reformer through supply line, heating the fed medium by heater and thermally coupling the heated up medium in the stage - Google Patents

Abstract

The heating of a catalyst stage (300) mounted downstream of a reformer, comprises feeding of air as a heat transfer medium into the reformer (100) through a supply line, heating the fed medium by heater (200) and thermally coupling the heated up medium in the catalyst stage using indirect heat transfer by means of bypass-pipeline (320) designed as a helical tube in an area. An outlet pipeline for the reformer product and the bypass-pipeline are controlled by means of a valve arrangement arranged downstream of the catalyst stage. The heating of a catalyst stage (300) mounted downstream of a reformer, comprises feeding of air as a heat transfer medium into the reformer (100) through a supply line, heating the fed medium by heater (200) and thermally coupling the heated up medium in the catalyst stage using indirect heat transfer by means of bypass-pipeline (320) designed as a helical tube in an area. An outlet pipeline for the reformer product and the bypass-pipeline are controlled by means of a valve arrangement arranged downstream of the catalyst stage. The heat transfer medium is fed back into the reformer by a circulatory pump after passing through the catalyst stage. An independent claim is included for a device for heating of a catalyst stage mounted downstream of a reformer.

Description

The The invention is directed to a method for heating at least a reformer downstream catalyst stage, wherein the Reformer a heat transfer medium over at least one Feed line and this by means of at least one heater is heated. The invention is also directed to a device to perform of the method, the device comprising at least one reformer, a feeder associated with the reformer, a feeder associated with the reformer Outlet, a heater associated with the reformer and at least having a reformer downstream catalyst stage.

It is known that by reforming hydrocarbonaceous fuels such as gasoline, diesel, natural gas or LPG, a hydrogen-containing product gas can be produced. For example, methane steam reforming as a major component of natural gas essentially follows the two independent reaction equations CH 4 + H 2 O ⇔ CO + 3H 2 ; .delta.h 0 = 206kJ / mol and CH 4 + 2H 2 O ⇔ CO 2 + 4H 2 .delta.h 0 = 165kJ / mol under heat supply to a catalyst. Such a hydrogen mixture produced in the steam reforming is essentially composed, for example, as follows:
7% CO ₂ , 9% CO, 1% CH ₄ , 27% H ₂ O and 56% H ₂ . Such a gas mixture is unsuitable for use in many fuel cells, since the existing carbon monoxide attacks the catalysts of the fuel cell and significantly reduces the speed of the oxidation necessary for the production of electricity. For this reason, it is necessary to purify the gas mixture before use in such a way that the carbon monoxide content is reduced to 10-100 ppm depending on the downstream fuel cells. This happens in so-called shift converters, whereby the conversion corresponds to the exothermic homogeneous water-gas-shift reaction CO + H 2 O ⇔ CO 2 + H 2 .delta.h 0 = -41kJ / mol expires. In general, in two temperature stages, the high-temperature shift (HT shift), for example on a Fe-Cr catalyst at temperatures between 300-500 ° C and the low-temperature shift (NT shift), for example, on a Cu-Zn Catalyst at temperatures of 200-300 ° C, converted. At the high temperature of the HT shift, the reaction rate of the water-gas reaction is high, but the equilibrium is far left, ie at high carbon monoxide concentrations. In the low temperatures of the NT shift, the equilibrium is more favorable, but here the reaction rate is smaller. After such a shift conversion, the gas mixture contains a carbon monoxide content of about 0.5 to 1%.

In order to further reduce this high carbon monoxide content, in particular for low-temperature PEM fuel cells, a gas-fine purification stage is optionally connected downstream. When using the selective oxidation, the carbon monoxide present in the gas mixture reacts with the addition of oxygen and in the presence of a suitable catalyst to carbon dioxide, according to the reaction CO + ½O 2 ½ CO 2 .delta.h 0 = -283.6kJ / mol

This reaction should proceed as far as possible selectively, ie with as much as possible suppressed hydrogen oxidation H 2 + ½O 2 ⇔ H 2 O Δh 0 = -243.5kJ / mol

At the Start the process are all first Reactors, i. for example reformer and downstream catalyst stage, and heat exchangers at ambient temperature and need be brought to operating temperature. For large systems, this is done by means of Nitrogen, the extra for the startup and shutdown of the plant is maintained. In smaller, especially in fuel cell applications, comes this process out of the question, as a separate N2 supply is not tolerated. The heating of the main reformer is generally not critical, since this over may have direct or indirect heating (for example, a Burner with steam reformer or burner based on oxidation the fuel in autothermal reforming or partial oxidation). In contrast, the heating of the downstream catalytic converter stage is critical in terms of time. in which, for example, the shift reactions or a selective Oxidation takes place.

From the DE 101 32 064 A1 For example, methods for heating reformer downstream catalyst stages are known. In the first variant, water is evaporated in a reformer and passed directly into the downstream catalyst stage. Since the heated water in the catalysts can condense the downstream catalyst stage, only water-insoluble catalyst systems are suitable in this method. In a second variant, air is heated instead of water and introduced into the downstream catalyst stage. In this case, oxygen-insensitive catalysts must be used, since the air has an oxygen content, which could deactivate or even damage the catalysts te. In another variant, the direct heating with flue gas of the reformer burner is finally revealed.

From the DE 199 44 540 A1 is a reactor system known which works with electrical heating means. In this case, a planar, electrically heatable, catalyst-occupied and permeable for a Reaktionseduktstrom heater is provided. In a start-up phase, the reaction-educt stream is passed into the reaction space only over part of an inlet cross-section.

From the DE 100 54 840 A1 Finally, a method and apparatus for starting a reactor in a gas generating system is known. In this case, a hydrocarbon is converted to generate thermal energy, wherein at least a portion of an exhaust gas stream flows into the reactor.

in the The prior art known methods and devices have considerable restrictions result. For example, a significant energy consumption or a restriction the catalysts to be used.

Of the Invention is therefore based on the object to a solution create, which allows one Reformer and at least one downstream catalyst stage effectively to heat up while using conventional catalysts continue possible is.

at a first variant of a method for heating at least a downstream of a reformer catalyst stage of the input described type, the object is achieved by a thermal coupling the heated heat transfer medium in the at least one downstream catalyst stage means an indirect heat transfer solved.

One such process for heating at least one reformer downstream catalyst stage allows a startup of a reformer system in a short time and the use of conventional catalysts in the downstream catalyst stage. This is in particular by achieved that the heated heat transfer medium by means of indirect heat transfer not directly with a catalyst of the downstream catalyst stage is brought into contact. In a direct heat transfer could heated heat transfer medium, depending on the structure and property of the heat transfer medium, for example at least partially condense on the catalyst or in others unintentionally react with the catalyst and accordingly a on this heat transfer medium restrict the function of the catalyst that reacts sensitively or even destroy it. through the method according to the invention Is it possible, the heat generated in a reformer for a Heating a downstream of the reformer catalyst stage use what a resource-saving heating at a high Ensures efficiency of heat generated and existing in the reformer.

A according to the invention first Variant of a device for heating at least one reformer downstream catalytic converter stage of the type described above has at least one heat exchanger for indirect transfer of heat on.

A such device allows an effective execution the first variant of the method for heating at least one a reformer downstream catalyst stage. By means of at least a heat exchanger can be a heated heat transfer medium passed through a reformer downstream catalytic converter stage, without the heat transfer medium in direct contact with the catalyst of the downstream catalyst stage arrives. This allows a Use of conventional catalysts in the downstream Catalyst stage.

at a second variant of a method for heating at least a downstream of a reformer catalyst stage of the input described type, the object is achieved by an at least partially return the heat transfer medium after passing through the at least one downstream Catalyst stages dissolved in the reformer.

One such process for heating at least one reformer Downstream catalyst stage allows heating and starting a Reformersystem in a short time and the simultaneous use of conventional Catalysts in the downstream catalyst stage. this will In particular, achieved in that the heated heat transfer medium after passing through the at least one downstream Catalyst stage is at least partially returned to the reformer. In this case, the heat transfer medium used preferably reused in several cycles, thereby preventing will that any unwanted properties of the heat transfer medium by permanently re-introducing into the system in the downstream Accumulate catalyst level. This allows a use of conventional Catalysts in the downstream catalyst stage.

A second variant of a device according to the invention for heating at least one catalyst stage downstream of a reformer The type described at the beginning has at least one return line for the return of the heat transfer medium into the reformer.

A such device allows an effective execution the second variant of the method for heating at least one a reformer downstream catalyst stage. By means of at least a return can be a heated heat transfer medium after passing through the at least one downstream Catalyst stage are at least partially returned to the reformer. For a permanent new supply of the heat transfer medium is not necessary whereby an accumulation of any unwanted substance components and / or Properties of the heat transfer medium is prevented in the downstream catalyst stage. This allows a Use of conventional catalysts in the downstream Catalyst stage.

at a third variant of a method for heating at least a downstream of a reformer catalyst stage of the input described type, the object is achieved by a preferably alternating Perform a the method steps of the first variant of the method according to the invention and one of the method steps of the second variant of the method according to the invention solved.

One such process for heating at least one reformer Downstream catalyst stage allows for extremely efficient heating and startup of a reformer system in a short time and use conventional catalysts in the downstream catalyst stage. In this case, the invention is particular an alternate execution one of the method steps of the first variant of the method according to the invention and one of the method steps of the second variant of the method according to the invention provided so as to mix the possibly different Heat transfer media to avoid.

A third invention Variant of a device for heating at least one reformer downstream catalytic converter stage of the type described above has at least one heat exchanger for indirect transfer of heat and a return for returning a heat transfer medium into the reformer.

A such device allows an effective execution the third variant of the method for heating at least one a reformer downstream catalyst stage. By means of the heat exchanger for indirect transfer of heat and the return for returning a heat transfer medium in the reformer can in an efficient way optionally different heat transfer media be used, resulting in a high efficiency of the device according to the invention.

Prefers is to the embodiment of the invention in the first variant of inventive method essentially water as the heat transfer medium to the reformer the at least one lead supplied. Will water as the heat transfer medium forwarded, it is possible in the downstream catalyst stage in particular water-sensitive Catalysts to be used because of the indirect according to the invention heat transfer the heated water is not in direct contact with the catalyst the downstream catalyst stage comes and therefore a condensation or any other unwanted reaction of the water in this not to be afraid is.

Farther is to the embodiment of the invention in the first variant of inventive method the heated heat transfer medium in the at least one downstream catalyst stage means at least one, preferably in at least one area as a tube coil trained bypass line thermally coupled. Such a thermal coupling means allows a bypass line a simple passage of a heat transfer medium through the downstream Catalyst stage without in direct contact with the catalyst of Catalyst stage to come. This is for thermal coupling the bypass line, which is an indirect heat transfer from the heated Heat transfer medium allows for the downstream catalyst stage, preferably in at least an area formed as a coiled tubing, so as to the surface and so that the contact surface of the heat exchanger to increase and thus one possible effective heat transfer to enable.

Prefers is in a further embodiment of the invention in the first Variant of the method according to the invention associated with at least one of the downstream catalytic converter stage Reformerproduktzuleitung and at least one bypass line by means of a, preferably the at least one downstream catalyst stage downstream valve arrangement line-controlled. Such Line control by means of a valve arrangement allows a simple flow control of the downstream catalyst stage associated reformer product supply line and the at least one bypass line. By means of such a line control can vary depending on regular operation or after warm-up the reformer product or the heat transfer medium directed into the reformer product supply line or the bypass line become.

In an embodiment The invention relates to the first variant of the device according to the invention a preferably formed in at least one area as a tube coil Bypass line on. Such a bypass line allows a simple passage of a heat transfer medium through the downstream Catalyst stage without this in direct contact with the catalysts the catalyst stage comes. Here is the bypass line, which an indirect heat transfer from the heated heat transfer medium allows for the downstream catalyst stage, preferably in at least a region formed as a coiled tubing, so as by means of a large contact surface a preferably effective heat transfer to enable.

In a further embodiment The invention relates to the first variant of the device according to the invention one of the at least one catalyst stage downstream valve assembly on. In this case, the valve arrangement is preferably the reformer Downstream catalyst stage downstream, so that the valve assembly only with the already cooled Heat transfer media or reformer products comes into contact.

Prefers is the embodiment of the invention in the second variant of inventive method essentially air, preferably ambient air as the heat transfer medium to the reformer the at least one lead supplied. Will air, preferably Ambient air as the heat transfer medium it is possible in the downstream catalytic converter stage in particular air-sensitive, that means especially oxygen-sensitive catalysts, to use because of the return line according to the invention the air after passing through the at least one catalyst stage in the reformer the oxygen concentration of the introduced air permanently reduced, at least not increased further and therefore at least a complete Deactivation of the example, oxygen-sensitive catalysts prevented becomes.

Prefers is in a further embodiment of the invention in the second Variant of the method according to the invention the heat transfer medium by means of a pumping device, preferably a circulating pump at least partially returned. A such at least partial return By means of a pumping device allows in particular a fast and effective return, so that the heat transfer medium only a small amount of heat to the environment. Furthermore, a jam of the heat transfer medium effectively prevented.

In a further embodiment The invention features the second variant of the device according to the invention a pumping device, preferably a circulation pump. Such a pumping device supports the flow of the heat transfer medium within through the heat transfer medium conductive components, components and / or devices.

Finally will preferred in a further embodiment of the invention in the first variant of the method according to the invention additionally one of Process steps of the second variant of the method according to the invention carried out. In such a coupling of both variants of the method according to the invention can be a particularly efficient start-up of a downstream catalyst stage be achieved.

The aforementioned and claimed and described in the embodiments to be used according to the invention Components are subject in size, shape, Design, material selection and technical conceptions none special exceptions, so that in the field of application known selection criteria can apply without restriction.

Further Details, feature and advantages of the subject invention emerge from the dependent claims as well as from the following description of the accompanying drawings, in the - exemplary - a preferred Embodiment of Invention is shown. In the drawing shows

1a a block diagram of an embodiment of the device according to the invention in a first variant of the invention;

1b a sketch of a portion of a downstream catalytic converter stage;

2a a block diagram of an embodiment of the device according to the invention in a second variant of the invention;

2 B a block diagram of another embodiment of the device according to the invention in a second variant of the invention;

3 a block diagram of an embodiment of the device according to the invention in a third variant of the invention.

In 1a is in one embodiment of the device according to the invention in a first variant of the invention for a reformer 100 presented, which is a reformer feed 110 and a reformer exodus 120 having. At the reformer lead 110 are a water supply 104 and a fuel supply line 102 connected. The water supply 104 and the fuel supply 102 ie in particular their flow rates can be controlled by means of valves (not shown). The fuel supply line 102 provides hydrocarbon-based energy carriers such as gasoline, diesel, natural gas or LPG or a mixture of these.

In regular operation, ie after a heating phase, a mixture of hydrocarbon-containing energy carriers and water is the reformer 100 fed.

In the warm-up phase, however, it is provided, only substantially water over the water supply 104 the reformer 100 to provide. The water serves in this case as a heat transfer medium and not as one of the reformeducts. Regardless, the water will be as in regular operation by the reformer 100 , So also passed through the arranged in the reformer catalysts. The fuel supply line 102 is correspondingly closed for the heating phase substantially or at least significantly reduced their flow rate.

To the reformer 100 ie in particular the one or the reformer 100 existing catalysts to heat up, is the reformer 100 with a heater 200 fitted. The heater 200 may be in or out of or in any other way or in the reformer 100 be arranged. To operate the heater 200 becomes the heater 200 by means of an air supply line 202 and a fuel supply line 204 energized to operate the heater within a suitable temperature band. In addition to flame burners or other burner devices, the heater can also be electrically operated. The heater 200 is with the reformer 100 thermally coupled, so that a heat flow W from the heater 200 to the reformer 100 is formed, a heating of the reformer 100 allows.

That of the water supply 104 originating water, which via the reformer supply line 110 in the reformer 100 is initiated is by means of the heater 200 heated up and in the Reformerausleitung 120 directed. To the Reformerausleitung 120 joins one to the reformer product lead 310 and to a bypass line 320 leading division. In regular operation, ie when both water and fuel are fed to the reformer and these in the reformer 100 react to the reformer product, the resulting from the reformer hydrogen-containing reformer product via the reformer product feed line 310 the downstream catalyst stage 300 fed. The catalyst stage 300 For example, it may have a high-temperature shift (HT) shift, a low-temperature shift (NT) shift, and / or a selective oxidation (Sel-Ox) step, or a combination of the steps. The reformer product is usually a hydrogen-containing gas mixture which also contains a proportion of carbon monoxide and is therefore unsuitable for direct use in many fuel cells. The reformer product is therefore in regular operation on the Reformerproduktausleitung 120 through the reformer product introduction 310 in a downstream catalytic converter stage 300 directed. The reformer product supply line 310 leads the reformer product thereby directly through the catalyst of the downstream catalyst stage 300 , wherein in the in the downstream catalyst stage 300 carried out the catalyst stage product via the catalyst stage product discharge 350 is discharged. The catalyst stage product is essentially a hydrogen-rich gas mixture purified by oxidation on the catalyst of carbon monoxide. This is then in regular operation via a valve device 360 in a fuel cell 400 directed. In the fuel cell 400 Then, according to the fuel cell reactions, the energy present in the hydrogenated catalyst step product is converted into electrical energy.

During the heating phase, however, the heated water, which via the Reformerausleitung 120 the reformer 100 leaves, in the bypass line 320 directed. The bypass line 320 provides a bypass to the reformer product supply line 310 is and directs the heated water in the downstream catalyst stage, ie essentially by the catalyst of the downstream catalyst stage 300 in that direct contact of the heated water with the catalyst 332 the downstream catalyst stage 300 is avoided. The heat transfer takes place instead via a heat exchanger 330 , in the present case as a heating coil 340 is trained. Thus, the catalyst 332 the downstream catalyst stage 300 be heated indirectly by means of the heated water, so that damage to the catalyst 332 due to any condensation of the heated water in the catalyst 332 is prevented.

After passing through the heat exchanger 330 ie in the illustrated embodiment after passing through the heating coil 340 , that is now cooled water through the bypass line 320 from the downstream catalyst stage 300 into the valve device 360 directed. In the illustrated embodiment, the valve device 360 the downstream catalyst stage 300 downstream. If, for example, the catalyst stage product discharge 350 by means of the valve device 360 closed and at the same time the bypass line 320 opened, that is from the Reformerausleitung 120 escaping fluid due to in the Reformerpro duktzuleitung 310 resulting back pressure, which as a result of closing the with the Reformerproduktzuleitung 310 in fluidly contacting catalyst stage product discharge 350 is built, through the open and almost backpressure-free bypass line 320 directed. This through the bypass line 320 leading is the predetermined for the heating phase way. After heating, ie after completion of the heating phase, by means of the valve device 360 the bypass line 320 respectively. 320 ' closed and at the same time the Reformerproduktausleitung 350 open. The due to the closure of the bypass line 320 / 320 ' Resulting back pressure in the bypass line 320 will that be the result of the reformer exodus 120 discharged fluid through the Reformerproduktzuleitung 310 in the downstream catalyst stage 300 directed.

Depending on the operating mode, ie either heating phase or regular operation, therefore, via a corresponding adjustment of the valve device 360 that from the reformer 100 and about the Reformerausleitung 120 discharged fluid, which during the heating phase, the heated water as a heat transfer medium and during normal operation is a hydrogen-containing reformer product gas, either in the Reformerproduktzuleitung 310 (in regular operation) or through the bypass line 320 (during the heating phase) are passed. The position of the valve device in the illustrated embodiment is advantageously the downstream catalytic converter stage 300 downstream, because at this position the through the valve device 360 flowing fluids are already cooled. However, it is also conceivable, the valve device 360 in any other possible place, for example between reformers 100 and downstream catalyst stage 300 to arrange.

In 1b is a schematic representation of a portion of a downstream catalyst stage 300 , This has according to the embodiment of the first variant of the invention, a portion of the heated heat transfer medium in the downstream catalyst stage 300 introductory bypass line 320 , one the heat of the heated heat transfer medium into the environment - the catalyst 332 - conductive heating coil 340 and a portion of the cooled heat transfer medium from the downstream catalyst stage 300 conductive bypass line 320 ' on. Bypass line 320 , Heating coil 340 and bypass line 320 ' are conductively connected together in a fluid-conducting manner. The catalyst 332 can be any one for the purpose of the catalyst stage 300 be suitable catalyst such as a Fe-Cr catalyst, a Cu-Zn catalyst or any mixture of different suitable materials. Also, quite generally, is the catalyst 332 not limited to one unit. It is conceivable and practical to use a plurality of identical or different catalysts. This also applies mutatis mutandis to the catalyst of the reformer 100 , Likewise, the catalyst 332 in different forms in the downstream catalyst stage 300 be introduced, for example as a bed.

During the heating phase is via the bypass line 320 the heated water of the downstream catalyst stage 300 fed, but without being in direct contact with that in the downstream catalyst stage 300 existing catalyst 332 to get. The heated water then flows into a heating coil 340 due to the large contact area to the catalyst 332 in particular, an indirect heat transfer of the heat present in the heated water to the catalyst 332 allows. While the catalyst 332 is indirectly heated, the heated water cools during the flow through the heating coil 340 so that the now cooled water over the bypass line 320 ' from the downstream catalyst stage 300 is discharged.

In addition to the described components and / or devices is in the 1b also the reformer product supply line 310 which in regular operation, the reformer product by the catalyst 332 leads. About the catalyst stage product discharge 350 In regular operation, the catalyst stage product discharge is from the downstream catalyst stage 300 discharged.

According to the invention, the guide devices 320 . 340 . 320 ' on the one hand and the guiding devices 310 . 350 on the other hand substantially separated from each other and form for the purposes described different ways within and through the downstream catalyst stage 300 out.

In the embodiment of the device according to the invention in a second variant of the invention according to 2a and 2 B the device has a reformer 100 on, on which a reformer supply line 110 and a reformer exodus 120 are arranged. Again, the reformer supply 110 via a water supply 104 and / or a fuel supply line 102 Water, fuel and / or a water-fuel mixture are supplied. Furthermore, the reformer points 100 a heater 200 on, which by means of an air supply line 202 and a fuel supply line 204 can be supplied with energy. Also in this variant, electrical or other heating devices are conceivable. By means of a heat flow W between the heater 200 and the reformer 100 becomes the reformer 100 heated.

In regular operation becomes the reformer 100 about the reformer supply 110 fed a water-fuel mixture. This is made up of the fuel supply line 102 originating fuel and from the water pipe 104 coming together water. The heated reformer product is then on the Reformerausleitung 120 and about the subsequent reformer product supply line 310 in the downstream catalyst stage 300 initiated. The reformer product supply line 310 leads the reformer product directly through the catalyst of the downstream catalyst stage 300 , wherein in the in the downstream catalyst stage 300 carried out the catalyst stage product via the catalyst stage product discharge 350 is discharged. The catalyst stage product is essentially a hydrogen-rich gas mixture purified by oxidation on the catalyst of carbon monoxide. This is then in ei ne fuel cell 400 directed. In this fuel cell, during normal operation, the energy contained in the catalyst stage product is converted to electrical power. According to the second variant of the device according to the invention, this has a return line 380 on, according to 2a For example, connected to a discharge of a fuel cell via a line divider (for example, in a simple form a tee) or according to 2 B for example by means of a valve device 385 with the catalyst stage product discharge 350 connected is. The valve device 385 is only optional. On an arrangement, when using a pumping device 370 , which is switchable, according to 2a be waived.

As with the device according to variant 1 described, can the water supply 104 or the fuel supply line 102 be regulated, ie in particular the flow rates of the supply lines 102 and or 104 ,

During the heating up becomes the reformer 100 instead of a water-fuel mixture over the fuel supply line 102 Ambient air supplied. Ie in detail that the water supply 104 during the heating phase is substantially closed and the reformer 100 essentially alone via the supply line 104 instead of, for example, fuel gas ambient air is introduced. The ambient air is via the reformer feed line 110 into the interior of the reformer 100 directed. By means of the heater 200 becomes the one in the reformer 100 introduced ambient air heated and the Reformerausleitung 120 or the reformer product supply line 310 in the downstream catalyst stage 300 initiated. The ambient air is directly through the in the downstream catalytic converter stage 300 passed existing catalyst. The ambient air heats up in the downstream catalytic converter stage 300 existing catalyst on. At the same time, the atmospheric oxygen present in the ambient air leads to a partial oxidation of the catalyst and thus to a partial deactivation of the catalyst. The partial oxidation on the catalyst simultaneously leads to a reduction in the proportion of atmospheric oxygen in the ambient air supplied.

According to the invention, the ambient air is either after being passed through a fuel cell 400 (according to 2a ) or directly after discharge from the downstream catalyst stage 300 (according to 2 B ) in the return line 380 directed. For such a return line is preferably a valve device 385 (according to 2 B ), which depending on the state, the ambient air either in the downstream fuel cell 400 or directly into the ambient air, or in the return line 380 passes. The valve device may have different settings, so that, for example, only a partial return of the ambient air can be realized. The valve control can also be arranged at other positions, but it is only optional, since a line control also by means of the pumping device 370 can be realized. The with the return 380 connected pumping device 370 , which is preferably a circulating pump, thereby passes the cooled and oxygen-reduced ambient air back to the fuel supply line 104 from which she returned to the reformer supply line 110 is directed. According to the invention, no or only a small part of fresh ambient air, which has a higher oxygen content, is supplied to the system. The now cooled and oxygen-reduced ambient air is returned to the reformer 100 initiated, reheated in this and then on the Reformerausleitung or the Reformerproduktzuleitung 310 again in the downstream catalyst stage 300 initiated. The heated ambient air heats due to the direct con tact with the catalyst in the downstream catalyst stage 300 this on and is also further oxidized by the catalysts. After a second pass through the downstream catalyst stage 300 the circulating ambient air to a further reduced proportion of atmospheric oxygen, so that the ambient air due to the return line according to the invention to an inert gas, ie to a gas mixture with a low or no oxygen content, is converted.

The ambient air can for a further cycle by means of the pumping device 370 over the return line 380 and the reformer lead 110 the reformer 100 and then about the Reformerausleitung 120 or the reformer product supply line 310 the downstream catalyst stage 300 be forwarded. Another partial deactivation of in the downstream catalyst stage 300 existing catalysts no longer takes place due to the now low concentration of oxygen in the ambient air.

This means that, although the initially oxygen-containing ambient air directly through the catalysts of the downstream catalyst stage 300 is conducted, only a slight partial deactivation of the catalysts takes place and therefore no special, especially oxygen-insensitive catalysts must be used.

Finally, to reactivate the catalysts after the heating phase, it is sufficient - since only a very small volume of the in the downstream catalyst stage 300 existing catalysts was deactivated - a flooding of the catalysts with a hydrogen-containing gas mixture. This may be, for example, the water-fuel gas mixture, which in regular operation via the water supply 104 or the fuel supply line 102 the reformer 100 fed and then the downstream catalyst stage 300 is initiated. This displaces at the same time the previously circulating ambient air, via the valve device 385 (according to 2 B ) leaves the circuit and together with the catalyst stage product from the downstream catalyst stage 300 is directed. The line then becomes for regular operation by means of the valve device 385 (according to 2 B ) and / or by closing the pumping device 370 closed.

In 3 is a reformer in an embodiment of the device according to the invention in a third variant of the invention 100 presented, which is a reformer feed 110 and a reformer exodus 120 having. At the reformer lead 110 are a water supply 104 and a fuel supply line 102 connected. The water supply 104 or the fuel supply line 102 , ie in particular their flow rates, can be regulated by means of valves (not shown). The fuel supply line 102 provides hydrocarbon-based energy carriers such as gasoline, diesel, natural gas or LPG or a mixture of these. However, it can also provide air, in particular ambient air.

Furthermore, the reformer points 100 a heater 200 on, which by means of an air supply line 202 and a fuel supply line 204 can be supplied with energy. By means of a heat flow W between the heater 200 and the reformer 100 becomes the reformer 100 heated.

According to the third variant of the device according to the invention this is with a heat exchanger already described in detail above 330 equipped with a bypass line 320 with the Reformerausleitung 120 connected is. One also with the heat exchanger 300 connected bypass line 320 ' ends in a first valve device 360 , The inventive device according to the third variant also has a return described above in more detail 380 for returning a heat transfer medium in the reformer. This return 380 is according to a preferred embodiment of the third variant of the device according to the invention with a second valve device 385 connected and ends in the fuel supply line 102 , which in turn via the reformer supply 110 in the reformer 100 leads. The second valve device 385 Can in its function with the valve device 360 be compared. Depending on the condition of the valve device 385 can a heat transfer medium in the return line 380 or in the fuel cell 400 or directly into the environment.

In a preferred embodiment, the two variants according to the invention, which in the device according to 3 combined, used alternately. This means that, for example, water as the heat transfer medium via the open water supply line 104 , with simultaneous closure of the fuel supply line 102 , about the reformer supply 110 into the reformer. As already described, the water is in the reformer 100 because of with the reformer 100 coupled heater 200 heated up and gets into the Reformerausleitung 120 , During the heating phase, the heated water is in the bypass line 320 introduced and from this in the heat exchanger 300 led, where an indirect heat transfer of the heat of the heated water to the catalyst of the downstream catalyst stage 300 takes place. Subsequently, the cooled water over the bypass line 320 ' into the valve device 360 directed, which is connected during the heating phase such that it is the cooled water in the valve device 385 leads, which in turn then the cooled water, for example, in the fuel cell 400 or else into another collecting device (not shown) passes.

Alternating to the heating with, for example, water as the heat transfer medium according to the first variant of the invention, heating with air, preferably ambient air, can also be carried out as the heat transfer medium. This is the water supply 104 closed and the fuel supply 102 open. From the fuel supply 102 is now air, preferably ambient air, through the reformer supply 110 in the reformer 100 initiated. Again, by means of the heating device, a heating of the ambient air acting as the heat transfer medium takes place. The heated ambient air is via the Reformerausleitung 120 from the reformer 100 discharged. The valve device 360 is now switched so that the heated ambient air is not in the bypass line 320 but about the reformer product supply line 310 directly into the downstream catalyst stage, that is, passed through the catalyst arranged in the downstream catalyst stage. The heated ambient air heats the downstream catalytic converter stage 300 and then via the catalyst stage product discharge 350 through the valve device 360 into the valve device 385 passed, which the cooled ambient air into the return line 380 passes. Due to the already described above in more detail reactions of the heated ambient air with the catalyst of the downstream catalytic converter stage, which points through the downstream catalyst stage 300 conducted ambient air to a reduced oxygen content. The thus oxygen-reduced ambient air is by means of the pumping device 370 for another cycle back to the fuel supply line 102 passed, from which the ambient air via the reformer supply line 110 in the reformer 100 is directed. This cycle can be repeated as often as desired, for example, the desired temperature of the downstream catalyst stage 300 is reached or alternatively water is used again as a heat transfer medium.

For this purpose, the valve device 385 be switched so that the ambient air is discharged from the system to avoid mixing of the ambient air and the water. This can be done, for example, by means of a discharge into the fuel cell 400 or by means of discharging into the environment or other collecting device (not shown). Subsequently, as described above, the fuel supply line 102 closed and at the same time the water supply 104 opened, so that again water can be used as the heat transfer medium. After the heating of the downstream catalyst stage, the previously used heat transfer media by means of a related position of the valve device 360 and or 385 discharged from the system. It should be noted that on the one hand, the position of the valve device 385 , if available, can be arranged at other suitable positions. In addition, the valve device 385 optional, as a valve function also by means of a special pumping device 370 which is an opening and closing of the return line 380 can effect.

After the start-up, that is after a successful heating, can for the then taking place regular operation on the fuel supply 102 fuel and through water supply 104 an appropriate amount of water is supplied to the reformer.

Further details of the components and devices used in the third variant, the descriptions of the variant 1 and 2 be removed.

100

reformer

102

fuel supply line

104

water supply

110

reformer feed

120

Reformerausleitung

200

heater

202

air supply

204

fuel supply line

300

downstream catalyst stage

310

Reformer product supply

320

Bypass line (hot Area)

320 '

Bypass line (cold area)

330

Heat exchanger

332

catalyst

340

heating coil

350

Katalysatorstufenproduktausleitung

360

valve device

370

pumping device

380

return

385

valve device

400

fuel cell

W

heat flow

Claims (14)

Method for heating at least one Reformer downstream catalyst stage, the reformer a Heat transfer medium over at least a supply line and this fed by means of at least one heater is heated, characterized by a thermal coupling the heated heat transfer medium in the at least one downstream catalyst stage means an indirect heat transfer. Method for heating at least one reformer downstream catalyst stage according to claim 1, characterized by feeding essentially water as the heat transfer medium via the at least one supply line. Method for heating at least one reformer downstream catalyst stage according to claim 1 or 2, characterized by a thermal coupling of the heated heat transfer medium in the at least a downstream catalytic converter stage by means of at least one, preferably formed in at least one area as a tube coil Bypass line. A process for heating at least one reformer downstream catalyst stage according to any one of the preceding claims, ge characterized by a line control of at least one reformer associated discharge and at least one bypass line by means of a, preferably the at least one catalyst stage downstream valve assembly. Device for heating at least one Reformer downstream catalyst stage, at least pointing a reformer, a feeder associated with the reformer, a Reformer associated drain, a reformer associated heater and at least one catalyst stage downstream of the reformer, characterized in that the device comprises at least one heat exchanger for the indirect transfer of Has heat. Device according to claim 5, characterized in that that the heat exchanger a, preferably formed in at least one area as a tube helix Bypass line has. Apparatus according to claim 5 or 6, characterized in that the device comprises one, preferably the at least one catalyst stage Having downstream valve assembly. Method for heating at least one reformer downstream catalyst stage, the reformer, a heat transfer medium over at least a supply line and this fed by means of at least one heater is heated, characterized by an at least partial return the heat transfer medium after passing through the at least one downstream Catalyst stage in the reformer. Method for heating at least one reformer downstream catalyst stage according to claim 8, characterized by feeding of substantially air, preferably ambient air as the heat transfer medium over the at least one supply line. Method for heating at least one reformer Downstream catalyst stage according to claim 9, characterized by an at least partial return the heat transfer medium by means of a pumping device, preferably a circulating pump. Device for heating at least one Reformer downstream catalyst stage, at least having a reformer, a feeder associated with the reformer, a Reformer associated drain, a reformer associated heater and at least one reformer downstream catalyst stage characterized in that the device has at least one return line for returning a heat transfer medium in the reformer has. Device according to claim 11, characterized in that that the device is a pumping device, preferably a circulation pump having. Method for heating at least one catalyst stage downstream of a reformer, wherein the reformer is supplied with a heat transfer medium via at least one supply line and this is heated by means of at least one heating device, characterized by a preferably alternating execution of one of the method steps 1 to 4 and one of the method steps 8th to 10 , Device for heating at least one Reformer downstream catalyst stage, at least having a reformer, a feeder associated with the reformer, a Reformer associated drain, a reformer associated heater and at least one catalyst stage downstream of the reformer, characterized in that the device comprises at least one heat exchanger for the indirect transfer of Warm me and a return for returning a heat transfer medium in the reformer has