US20030070964A1

US20030070964A1 - Method for reforming liquid hydrocarbon mixtures

Info

Publication number: US20030070964A1
Application number: US10/264,391
Authority: US
Inventors: Andreas Docter; Norbert Wiesheu
Original assignee: DaimlerChrysler AG
Current assignee: Daimler AG
Priority date: 2001-10-05
Filing date: 2002-10-04
Publication date: 2003-04-17
Also published as: JP2003137507A; EP1304310A3; DE10149060A1; EP1304310A2

Abstract

A method for reforming a liquid hydrocarbon mixture, in which the hydrocarbon mixture is initially completely vaporized before it is contacted with the gaseous reactants and caused to undergo reaction. Usable as a reformer system in this context is a device which has at least two reforming chambers composed of a vaporization chamber and at least one reaction chamber, and in which a metering device for liquid hydrocarbons is provided in the region of the vaporization chamber, and an introducing device for gaseous reactants is provided in the region between at least two of the reforming chambers. The present invention allows liquid hydrocarbon mixtures to be reformed without the formation of unwanted residues such as tar or soot.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 101 49 060.7, filed Oct. 5, 2001, which is incorporated by reference herein.

BACKGROUND

The present invention relates to a method for reforming hydrocarbon mixtures which are liquid under normal conditions and to a device for carrying out this method. Moreover, the present invention relates to the use of this device in vehicles with fuel cells.

It is, in principle, known from the related art to reform hydrocarbon mixtures by steam reformation, partial oxidation, or autothermal reformation and, moreover, to obtain a hydrogen-containing gas by adding water or water-containing mixtures. In this context, the reformation usually takes place in a reactor in which, in addition to the educts, there are present catalysts which assist the reforming process.

However, in the reformation of hydrocarbon mixtures, the problem arises that the hydrocarbon mixtures fed to the reforming reactor (hereinafter called “reformer”) are difficult to reform completely, in particular, without producing residues. In many reforming methods and reformers of the prior art, residues and deposits arise which are detrimental to the course of the reforming process. These deposits contain cracking products of the hydrocarbons, in particular, elemental hydrocarbon, for example, soot or tar. These residues then result in damage to the catalyst with serious disadvantages for its effectiveness and service life, or even in the clogging of the reformer.

The related art, in general, attempts to deal with this problem by preparing or conditioning the hydrocarbon-reactant mixture to be reformed as homogeneously as possible.

For example, Unexamined German Laid-Open Patent Application DE 14 42 991 A1 (Chemical Construction Corp.) describes a continuous method for reforming naphtha which avoids the formation of unwanted residues and deposits containing elemental carbon such as soot or tar. In this context, the three reactants naphtha, water vapor and air are initially vaporized separately from each other, then combined at a temperature of at least 535° C. and fed to a gas conditioning chamber, where part of the naphtha is already converted. In this context, the dwell time of the reaction mixture in the conditioning chamber is critical and needs to be adjusted accurately since excessive dwell times result in the formation of unwanted residues. To complete the reaction, the reaction mixture is fed from the conditioning chamber to a catalytic reforming unit. The reforming reaction proceeds nearly quantitatively and, above all, without the formation of unwanted residues. However, this method has the disadvantage of extremely high temperatures and of an uneconomical, efficiency-reducing use of thermal energy. Above all, however, the dwell times of the reaction mixtures in the conditioning chamber, which have to be adjusted accurately, are a disadvantage because this makes it impossible to use the method under constantly changing load conditions, for example, in automotive applications.

Unexamined German Laid-Open Patent Application DE 199 55 892 A1 (Daimler-Chrysler) describes a method for reforming a hydrocarbon mixture having long-chain hydrocarbon components which allows the hydrocarbons to be converted without producing residues. In the process, the hydrocarbon mixture is preferably sprayed into a first reaction chamber together with an oxygen-containing gas where it is already partially converted in a non-catalytic manner. Then, this first reaction product and a water-containing reactant which can contain additional hydrocarbons are mixed and catalytically reformed in a second reaction chamber. Also described is a reactor which is suitable for carrying out the method. The method and the reactor allow continuous operation, nearly residue-free conversion of the hydrocarbons as well as thermal and spatial separation of the individual steps of the reforming reaction. The latter aspect allows the individual steps of the reforming reaction to be carried out at the optimum temperature, respectively.

A further approach for overcoming the residue problem described is disclosed by Unexamined German Laid-Open Patent Application DE 199 56 378 A1 (DaimlerChrysler), which proposes a method for introducing consumables for reforming a hydrocarbon mixture in which the supply, mixing and heating of the consumables take place successively in a multi-stage system, the heating being accomplished through the supply of the hot consumables itself. In this manner, a hydrocarbon mixture which is introduced into this hot substance flow is nearly instantly brought to a very high temperature, thereby avoiding the disadvantageous, delayed vaporization of the individual hydrocarbon fractions. Also described is a reactor which is suitable for carrying out the method.

SUMMARY OF THE INVENTION

The cause for the formation of the unwanted residues mentioned is considered to be the nonuniform vaporization of the hydrocarbons contained in the hydrocarbon mixtures. Thus, for example, gasoline is essentially composed of a mixture of linear, branched and cyclic alkanes with 7 to 10 carbon atoms which for the most part have boiling points below 135° C. and Diesel fuel is composed of alkanes of the same kind but with higher boiling points in the range of 180 to 370° C. When mixtures of that kind are vaporized, then the hydrocarbons vaporize in the order of their boiling points, namely the hydrocarbon with the lowest boiling point first and the hydrocarbon with the highest boiling point last. In a subsequent reaction with a reactant as, for example, oxygen, the hydrocarbons will then also react in turn, that is, according to their boiling points: the low-boiling ones first, the high-boiling ones last. As a consequence, there is a surplus of reactants, for example, oxygen, for the vaporized hydrocarbons at the beginning of the reaction, the supply of reactants and the conditions of reaction constantly changing in the course of the reaction, and a lack of reactants existing toward the end of the reaction. This results in inhomogenous conditions in the reaction chamber. While the conditions can be oxidizing (combustion) at the beginning, they can be pyrolytic (thermal decomposition) or even reductive (hydrogenation) in some regions of the reaction chamber toward the end of the reaction. This results in the disadvantageous formation of cracking products. In this context, the formation of very high-molecular, low-volatility hydrocarbon compounds such as tar or even the formation of particulate products such as elemental carbon (soot) are particularly disadvantageous.

Therefore, it is an object of the present invention to provide a reforming method for hydrocarbon mixtures which are liquid under normal conditions in which the hydrocarbon mixtures are converted nearly quantitatively and essentially without the formation of unwanted residues. Moreover, it is an object of the present invention to provide a device for carrying out the method.

The present invention is based, in part, on a recognition that an optimum mixture preparation, i.e., an optimally homogenized mixture of hydrocarbon and reactant, can only be achieved if all components to be mixed are present in gaseous form. This means, in particular, that the hydrocarbon mixture to be reformed, which is liquid under normal conditions, is preferably completely vaporized before it is mixed with the reactants, namely, under conditions in which essentially no pyrolysis occurs.

A first subject matter of the present invention is a method for reforming a liquid hydrocarbon mixture, including the following method steps: Initially, the liquid hydrocarbon mixture is supplied continuously and in metered quantities. In the following second method step, the liquid hydrocarbon mixture is essentially completely vaporized, but substantially without decomposition.

After that, the vaporized hydrocarbon mixture is contacted with at least one gaseous reactant. Subsequently, the obtained gaseous mixture of hydrocarbons and reactants is caused to undergo reaction. Then, the reaction mixture obtained in the process can be contacted with at least one reactant again subsequently caused to undergo reaction. These method steps can be repeated as often as desired or required. In the following final method step, the obtained reformate gas is directed toward its intended use.

In this context, a liquid hydrocarbon mixture is understood to be a mixture which is essentially composed of one or more hydrocarbons and which is liquid under normal conditions (normal pressure=1013 mbar; normal temperature 273 K). Examples of this include commercial fuels such as gasoline or Diesel fuel.

Suitable methods for supplying the hydrocarbon mixtures continuously and in metered quantities are described, for example, in non-prepublished German Patent Applications P 10020089.3 (DaimlerChrysler) and P 10020088.5 (DaimlerChrysler), which are incorporated by reference herein. In this context, suitable methods also include those operating in a high-frequency, discontinuous manner, so-called “quasi-continuous methods”. In these methods, the time intervals between two substance supply operations are in each case so short that the resulting discontinuous substance flow is perceived by the used reactor as continuous because of the inertia of the reactor.

In the context of the present invention, “supply in metered quantities” is understood, as used herein, to mean that an exactly measured quantity of the liquid hydrocarbon mixture is supplied.

In the context of the present invention, “essentially complete vaporization” is understood, as used herein, to mean that more than 98 percent by weight, preferably more than 99 percent by weight, in particular, 100 percent by weight of the liquid hydrocarbon mixture is converted from the liquid state to the gaseous state.

“Vaporization substantially without decomposition” is understood, as used herein, to mean that the vapor phase at the outlet of the vaporization chamber has essentially the same chemical composition as the liquid phase at the inlet thereof. Preferably, more than 98 percent by weight, in particular more than 99 percent by weight, and very particularly 100 percent by weight of the two phases should have the same chemical composition. In the present invention, the term “vaporization” is strictly distinguished from the terms “conversion to gas” or “gasification”. These terms, as used herein, are understood to refer to the chemical conversion of solids to gases.

Under normal pressure, vaporization without decomposition can be achieved according to the present invention at maximum temperatures of 600° C. in the vaporization chamber. Preferably, however, the temperatures are in the range from 200 for 500° C. and, in particular, in the range from 300 for 400° C. When the reformer is operated under pressure, the boiling temperatures of the hydrocarbon mixtures are correspondingly higher. In this case, the temperatures in the vaporization chamber have to be selected such that they are closer to the upper limits of the temperature ranges specified above.

Within the scope of the reforming method described herein, the reactants include, for example, water, air or other oxygen-containing gas mixtures and pure oxygen, preferably water and air. In the present invention, these reactants are used in gaseous form. In particular, this means for the reactant water that it is used in the form of water vapor.

The product of the reforming method described herein is the so-called “reformate gas”. This is a H2-rich gas which contains or can contain further reaction products such as CO2 and CO but also impurities as, for example, N2, originating from the educts as well as H2O. According to the present invention, the content of hydrocarbons that are not or only partially converted is low after the completion of the reformation and is less than 2 percent by weight, preferably less than 1 percent by weight, in particular less than 0.1 percent by weight.

Finally, the reformate gas is directed toward its intended use. This means that, if necessary, it is also subjected to one or more cleaning steps or aftertreated in another way before it is finally put to its intended use, for example, as fuel for a fuel cell.

In the method according to the present invention, the liquid hydrocarbon mixtures used are reformed nearly quantitatively and essentially without the formation of unwanted residues such as tar or soot. However, the method according to the present invention has further advantages.

For instance, due to the gaseous state of all educts of the reforming reaction, it is possible to achieve a particularly good intermixing and a particularly good heat transfer from the at least one gaseous reactant to the hydrocarbon mixture when mixing the educts. This results in a particularly homogenous preparation of the reaction mixture. As already mentioned, this has beneficial effects on the minimization of secondary cracking reactions during reformation and, consequently, on the formation of unwanted residues.

In the method according to the present invention, the required energy input can advantageously be further reduced if the gaseous reactants are heated, for example, using the waste heat of a reformate gas consumer arranged downstream, for example, a fuel cell. In this case, kind of a combination of heat and power exists which, as is generally known, has an particularly high efficiency.

Further advantages of the present invention will be mentioned at the appropriate places in the description below.

In a preferred embodiment of the method according to the present invention, the liquid hydrocarbon mixture is vaporized by adding thermal energy. For the vaporization, it is, in principle, sufficient to supply at least the enthalpy of vaporization of the hydrocarbon mixture, however, it is further preferred to supply at least the thermal energy that is required for the reforming reaction.

Like any chemical reaction and any chemical method, the reforming method of the present invention can also be carried out or operated only within a certain temperature range, the operating temperature range. In this context, it is a further advantage of the present invention that the inventive method can be carried out at relatively low temperatures. The suitable operating temperature range according to the present invention, of course, depends on the pressure used which can be ambient to several 10 bar, as desired or required. Moreover, the operating temperature does not need to be the same in all reaction chambers but can vary from reaction chamber to reaction chamber. When the reformer is operated at ambient pressure, then the operating temperature can be up to 1000° C. Preferably, however, it is 300 to 900° C. and, in particular, 400 to 800° C. This means, first of all, a lower energy input and, secondly, has a beneficial effect on the minimization of secondary cracking reactions during reformation because no pyrolysis reactions take place yet at the low operating temperatures according to the present invention.

To reach a suitable operating temperature during the starting phase, in which no sufficiently warm gaseous reactants are present yet, the required thermal energy is preferably supplied by at least one heating element for electrical heating.

When or after a suitable operating temperature is reached, the required thermal energy is then supplied to the system, preferably by at least one of the gaseous reactants.

The method according to the present invention is a continuous method. In the process, a substance flow directed from the vaporization chamber to the reaction chamber/chambers is generated. In a preferred embodiment of the method according to the present invention, vortex motions are produced in this substance flow to assist, on one hand, in the transfer of heat between the heat sources (electrical heating or gaseous reactants) and, on the other hand, in the homogeneous mixing of the hydrocarbon mixture with the gaseous reactants.

A particularly preferred embodiment of the method according to the present invention consists in an autothermal control of the method. In this context, the following method steps are provided: Initially, the liquid hydrocarbon mixture is supplied continuously and in metered quantities. Then, the liquid hydrocarbon mixture is essentially completely vaporized, but substantially without decomposition. In a third method step, the vaporized hydrocarbon mixture is contacted with water vapor, and the resulting mixture is at least partially reformed in a fourth method step. Subsequently, the obtained at least partially reformed mixture is contacted with an oxygen-containing gas mixture, preferably air, and the reformation is completed in the following sixth method step. After that, the obtained reformate gas is directed toward its intended use.

A further, particularly advantageous embodiment of the method according to the present invention consist in that the liquid hydrocarbon mixture is steam-reformed. In this context, the following method steps are provided: Initially, the liquid hydrocarbon mixture is supplied continuously and in metered quantities. Then, the liquid hydrocarbon mixture is essentially completely vaporized but without decomposition and contacted with water vapor in a third method step. Subsequently, the obtained gaseous hydrocarbon-water vapor mixture is caused to undergo reaction. After that, the obtained reformate gas is directed toward its intended use.

A second subject matter of the present invention is a device for carrying out the method according to the present invention. The device includes a reformer system having at least two reforming chambers which are arranged in a vessel and which include a vaporization chamber and at least one reaction chamber. Provision is made for a metering device for liquid hydrocarbon mixtures as well as for an introducing device for gaseous reactants. The metering device is provided in the region of the vaporization chamber and the introducing device is provided in the region between at least two of the reforming chambers. Of course, the device is especially suitable for carrying out the inventive method mentioned above but can, in principle, be used in other methods as well.

The device according to the present invention includes a reformer system, the reformer system featuring at least two reforming chambers which are arranged in a vessel and which include a vaporization chamber and at least one reaction chamber. Moreover, provision is made for a device for introducing liquid hydrocarbon mixtures continuously in metered quantities (hereinafter called “metering device”) as well as for a device for introducing gaseous reactants (hereinafter called “introducing device”). The device according to the present invention has the feature that the metering device is provided in the region of the vaporization chamber and that the introducing device is provided in the region between at least two of the reforming chambers.

A suitable metering device is described, for example, in non-prepublished German Patent Applications P 10020089.3 (DaimlerChrysler) and P 10020088.5 (DaimlerChrysler), which have already been mentioned above. In this context, suitable devices also include those operating in a high-frequency, discontinuous manner, so-called “quasi-continuous devices”. These devices generate a discontinuous substance flow in which the time intervals between two supply operations are in each case so short that the resulting discontinuous substance flow is perceived by the used reformer system as continuous because of the inertia of the reformer system.

In the context of the present invention, “introduction in metered quantities” is understood to mean that the metering device allows precise adjustment of the hydrocarbon flow, that is, of the amount of hydrocarbon that is introduced into the vaporization chamber per unit of time.

Due to the arrangement of the metering device in the region of the vaporization chamber and of the introducing device in the region between at least two of the reforming chambers, the metering device and the introducing device are spatially separated, which creates the condition for the hydrocarbon mixture to be introduced separately and to be essentially completely vaporized before it is contacted with one of the reactants.

A further advantage of the present invention consists in that the device according to the present invention permits the inventive method to be carried out continuously or at least quasi-continuously. Also possible are relatively high flow velocities in the reformer as well as a very fast adjustment of the reformer system to changing requirements, such as changes in load or the like, by introducing the hydrocarbon in metered quantities. These advantageous are useful, in particular, in mobile applications, for example, in fuel cell powered vehicles.

Another advantage of the present invention consists in the small amount of technical effort required for its implementation. This involves relatively low costs.

In a preferred embodiment of the device according to the present invention, at least one of the introducing devices is provided between the vaporization chamber and a first adjoining reaction chamber arranged downstream.

Moreover, it is preferred if the vaporization chamber is in heat-conductive contact with a first adjoining reaction chamber arranged downstream. In this manner, the gaseous reactant entering between the vaporization chamber and the reaction chamber can heat the vaporization chamber from its back, provided that the reactant has a sufficiently high temperature, thus supplying the vaporization chamber with the thermal energy required for vaporization. The first reaction chamber adjoining the vaporization chamber is also heated at the same time.

It is even more preferred if all reforming chambers adjoining each other are in heat-conductive contact with each other. This allows optimum utilization and distribution of the thermal energy that is input into the reformer system or released.

To assist the mixing of the substances moving in the device according to the present invention and, thus, to produce as homogeneously prepared as possible a mixture in the reformer, it is preferred in another embodiment of the inventive device that an device for swirling the substance flow (hereinafter called “swirling device”) is provided in at least one reforming chamber, preferably in all reforming chambers. These swirling devices may be members with permeable openings or interstices through which the substance flow can move, forming turbulences.

In this context, “substance flow” is understood herein to refer to the flow of all substances moving in the reformer system. These substances include, for example, the introduced liquid hydrocarbon mixture, the vapor thereof, the introduced gaseous reactants, the reaction products and all resulting mixtures.

To assist the distribution of the thermal energy input into the reformer system, that is, the transfer of heat from the warm substance flows to the substance flows to be heated, in a further, also preferred embodiment of the inventive device provision is made for the swirling device to be composed of a heat-conductive material, preferably of metal or metal alloys.

It is even more preferred if the swirling device is composed of metal wire, in particular, of knitted or woven metal wire meshes. In this case, the permeable openings are formed of the interstices between the wire meshes. These knitted or woven metal wire meshes have the advantage of having a large surface area, allowing a particularly good swirling and a particularly good heat exchange.

In an even more preferred embodiment, the mean diameters of the permeable openings of the swirling device (in the case of knitted wire meshes, for example, these are the mesh apertures) increase in the direction of flow. This takes into account the fact that the volume of the substance flow increases in the direction of flow due to the introduction of gaseous reactants. In this manner, impairments of the substance flow, such as stoppages or even reversals of the desired direction of flow, are advantageously avoided.

In an even more preferred embodiment of the present invention, provision is made for at least one heating element for electrically heating the reactor vessel. The heating element preferably includes one or more resistance heaters, in particular, one or more glow plugs.

When one or more glow plugs are used, it is possible to use, for example, commercial glow plugs. Examples of these are glow plugs which are used for the starting of Diesel engines.

The heating element for electrical heating is preferably arranged in the region of the swirling device; however, if the swirling device is electrically conductive, the heating element for electrical heating must be electrically insulated to avoid a short-circuit. In particular, commercial, heat-conductive ceramic tubes are suitable as insulation.

The heating element for electrically heating the reactor vessel can, in principle, be arranged in the swirling device in any useful way. It/they is/are advantageously arranged in such a manner that all reforming chambers can be heated at the same time. This advantageous arrangement makes it possible to supply thermal energy to all separately supplied educts of the reforming reaction.

A third subject matter of the present invention is the use of the device according to the present invention in vehicles with fuel cells. In this context, preference is given to the use in fuel cell systems for the propulsion of the vehicles. Also preferred is the use in fuel cell systems for additional supplying vehicles with electric energy, in particular, in so-called “auxiliary power units, APUs”. Also possible is the use in fuel cell systems which provide for a combined use of the inventive device for propulsion and for additional supply of electric energy.

BRIEF DESCRIPTION OF THE DRAWINGS

The teaching of the present invention can be embodied and refined in different ways. In this regard, reference is made to the claims and to the following description of three exemplary embodiments of the present invention with reference to the Figures, in which: [0054]
FIG. 1[0055] a schematically shows a device according to the present invention, in which three reforming chambers are arranged in series, and in which the metering device and the introducing device are arranged in such a manner that they spatially separated and perpendicular to each other.
Fig. 1[0056] b schematically shows a variant of the inventive device according to FIG. 1a which features an extended inlet pipe;
FIG. 2 schematically shows a device which is analogous to the inventive device from FIG. 1[0057] a but which has only two reforming chambers arranged in series; and
FIG. 3 schematically shows a device according to the present invention, including a heating element for electrically heating the reformer system during the starting process. [0058]

DETAILED DESCRIPTION

Device [0059] 1, which is schematically shown in FIG. 1a, is used for the autothermal reformation of liquid hydrocarbon mixtures. Device 1 includes a reactor vessel 2 in which three reforming chambers 3 are arranged in series. The reforming chambers include a vaporization chamber 4 as well as two reaction chambers 5. Moreover, the device features an insulation 8 arranged between the wall of reactor vessel 2 and the boundaries of the reforming chambers 3 as well as swirling devices 9.
In the present exemplary embodiment, swirling devices [0060] 9 are composed of woven metal wire meshes whose mesh aperture increases in the direction of flow.
The hydrocarbon mixture to be reformed is introduced into [0061] reactor vessel 2 via a metering device 6 and exists the reactor vessel via an outlet line 10 subsequent to flowing through reforming chambers 3. Therefore, the metering device and outlet line 10 are located at opposite sides of reactor vessel 2. Subsequent to entering reactor vessel 2, the hydrocarbon mixture initially reaches vaporization chamber 4. There, it is heated and essentially completely vaporized but without decomposition. Via introducing device 7, which is arranged in the region between vaporization chamber 4 and first reaction chamber 5, at least one gaseous reactant, preferably water vapor, is fed to the reformer system. The gaseous reactant heats vaporization chamber 4 from its back and first reaction chamber 5 from its front, and mixes with the vaporized hydrocarbon mixture, during which a further heat transfer takes place between the gaseous reactant and the hydrocarbon mixture up to their thermal equilibrium. The intermixing and heat distribution are assisted by swirling device 9. However, the intermixing and heat distribution also take place already in the intermediate space between vaporization chamber 4 and reaction chamber 5, as well as between the two reaction chambers 5.
Then, the resulting reaction mixture enters [0062] first reaction chamber 5 and is subjected to a first reforming step there. A second introducing device 7 is arranged in the region between first and second reaction chambers 5. Via this second introducing device 7, at least one gaseous reactant, preferably air, is fed to the reformer system as well. This gaseous reactant heats both first and second reaction chambers 5 and mixes with the reaction mixture that has formed in first reaction chamber 5. The reaction mixture resulting in the process is subjected to a second reforming step by which the reforming reaction is completed. Finally, the resulting reformate gas exists reaction vessel 2 via outlet line 10.
In FIG. 1[0063] a, reforming chambers 3 are separated from each other by an intermediate space, respectively. However, it is also possible for the reforming chambers, for example, to immediately adjoin each other or, for example, to be interconnected via pipe systems or, for example, via a heat-conductive dividing wall. In the region of these intermediate spaces, provision can also be made for swirling devices analogous to 9.
In the present exemplary embodiment from FIG. 1[0064] a, all reforming chambers 3 are in heat-conductive contact with each other, and all reforming chambers have heat-conductive swirling devices 9. Because of this, the reaction enthalpy released during the exothermic partial reforming reaction can be dissipated, remains in reactor vessel 2 at least partially, thus contributing to the heating of the reactor vessel. Insulation 8 is used to assist in retaining the thermal energy. In this manner, the thermal energy (i..e. heat) released during the exothermic partial reforming reaction can be used not only for the endothermic partial reforming reaction, but also for vaporization. This embodiment of the device according to the present invention permits a reforming process that is optimized in terms of heat transfer and allows the inventive reforming method to be carried out in a particularly economical manner in terms of heat, which represents a further advantage of the present invention.
[0065] Variant 19 of device 11, which is shown in Fig. 1b, is also used for used for the autothermal reformation of liquid hydrocarbon mixtures. In contrast to device 11, variant 19 has an extended inlet pipe 20 which, in the case shown, reaches up to the intermediate space between vaporization chamber 4 and first reaction chamber 5. This inlet pipe is preferably composed of a heat-conducing material.
The reactant entering through introducing [0066] device 7 is uniformly distributed in vaporization chamber 4, supplying it with at least the energy that is required for vaporizing the liquid hydrocarbon mixture. Inlet pipe 20 is composed of a heat-conductive material. Because of this, inlet pipe 20 is heated as well so that the liquid hydrocarbon mixture that is fed via inlet pip 20 can vaporize therein essentially completely, but substantially without decomposition. In this variant, the heat transfer from the gaseous reactant to the hydrocarbon mixture takes place as in a heat exchanger. The advantage of variant 19 consists in that a mixing of the hydrocarbon mixture with the gaseous reactant prior to the essentially complete vaporization of the hydrocarbon mixture is better prevented.
The [0067] device 11, which is schematically shown in FIG. 2, is used for the steam-reforming of liquid hydrocarbon mixtures. Device 11 is constructed analogously to device 1 but, in contrast, has only two reforming chambers, namely vaporization chamber 12 and reaction chamber 13. Moreover, only one introducing device 14, through which water vapor can be supplied, is provided in the region between vaporization chamber 12 reaction chamber 13.
[0068] Device 15, which is schematically shown in FIG. 3, represents a preferred embodiment of the device according to the present invention, including tow glow plugs 16, which are also shown schematically. In this exemplary embodiment, the glow plugs are arranged in the reactor vessel in a such manner that all reforming chambers can be electrically heated at the same time. The reforming chambers contain woven metal wire meshes as swirling devices 17 so that there is a risk of a short-circuit. Therefore, glow plugs 12 are covered with insulators 18 for electrical insulation which, in the present exemplary embodiment, are heat-conductive ceramic tubes.
With regard to their spatial extent, the arrangements composed of heating elements for [0069] electrical heating 16 and insulators for electrical insulation 18 are, of course, dimensioned in such a manner that they do not take up the entire width of the reforming chambers because otherwise they would spatially isolate certain regions of the reforming chambers, preventing the gaseous reactants from flowing into these regions. Rather, said arrangements are spatially dimensioned in such a manner that they allow the gaseous reactants supplied via introducing device 19 to spread in a substantially unhindered manner over the entire surface of reforming chamber boundaries 20. In the case of the exemplary embodiment from FIG. 3, the arrangement including glow plug 16 and ceramic sleeve 18 is designed to have a nearly circular cross-section so that the gaseous reactants supplied via introducing device 19 can flow past the arrangements without difficulty.
[0070] Device 11, which is shown in FIG. 3 and has heating elements for electrical heating, can, of course, also be implemented in an analogous manner a with device which, as shown in FIG. 2, has only two reforming chambers and is used, for example, for steam reformation.

Claims

What is claimed is:

1. A method for reforming a liquid hydrocarbon mixture, comprising:

(a) supplying the liquid hydrocarbon mixture continuously and in metered quantities;

(b) vaporizing the liquid hydrocarbon mixture so as to achieve essentially complete vaporization and so as to produce a vaporized hydrocarbon mixture substantially without decomposition;

(c) contacting the vaporized hydrocarbon mixture with at least one gaseous reactant so as to produce a gaseous hydrocarbon-reactant mixture;

(d) causing the gaseous hydrocarbon-reactant mixture to undergo a reforming reaction so as to produce a reformate gas; and

(e) directing the reformate gas toward an intended use.

2. The method as recited in claim 1 further comprising performing steps (a) through (d) at least a second time before performing step (e).

3. The method as recited in claim 1 wherein the vaporizing includes supplying thermal energy.

4. The method as recited in claim 3 wherein, during a starting phase of the vaporizing, the thermal energy is supplied by at least a heating element.

5. The method as recited in claim 3 wherein the thermal energy is supplied by at least one of the gaseous reactants after an operating temperature is reached.

6. The method as recited in claim 3 wherein the thermal energy is supplied in a quantity sufficient for the causing of the reforming reaction.

7. The method as recited in claim 1 further comprising producing a vortex motion.

8. The method as recited in claim 1 wherein the liquid hydrocarbon mixture is autothermally reformed and wherein the at least one gaseous reactant includes water vapor and the gaseous hydrocarbon-reactant mixture includes a gaseous hydrocarbon-water vapor mixture.

9. The method as recited in claim 8 wherein the causing of the gaseous hydrocarbon-reactant mixture to undergo a reforming reaction so as to produce a reformate gas includes the steps of:

at least partially reforming the hydrocarbon-water vapor mixture so as to produce an at least partially reformed mixture;

contacting the at least partially reformed mixture from with an oxygen-containing gas mixture; and

completing the reformation so as to produce a reformate gas.

10. Wherein the oxygen-containing gas mixture includes air.

11. The method as recited in claim 1 wherein the liquid hydrocarbon mixture is steam-reformed and wherein the at least one gaseous reactant includes water vapor and the gaseous hydrocarbon-reactant mixture includes a gaseous hydrocarbon-water vapor mixture.

12. A reformer device for reforming a liquid hydrocarbon mixture, the reformer device comprising:

at least two reforming chambers disposed in a vessel, the at least two reforming chambers including a vaporization chamber and at least one reaction chamber;

a metering device configured to meter a liquid hydrocarbon mixture, the metering device disposed in a first region of the vaporization chamber;

an introducing device configured to introduce gaseous reactants, the introducing device disposed between two of the at least two reforming chambers.

13. The device as recited in claim 12 wherein the introducing device is disposed between the vaporization chamber and a first adjoining reaction chamber downstream of the vaporization chamber.

14. The device as recited in claim 12 wherein the vaporization chamber is in heat-conductive contact with a first adjoining reaction chamber arranged downstream of the vaporization chamber.

15. The device as recited in claim 12 wherein each of the at least two reforming chambers is in heat-conductive contact with an adjoining reforming chamber.

16. The device as recited in claim 12 further comprising a swirling device configured to swirl a substance flow in at least one reforming chamber.

17. The device as recited in claim 16 wherein the swirling device includes a heat-conductive material.

18. The device as recited in claim 17 wherein the heat-conductive material includes one of a metal and a metal alloy.

19. The device as recited in 16 wherein the swirling device includes metal wire.

20. The device as recited in claim 19 wherein the swirling device includes one of a knitted wire mesh and a woven metal mesh.

21. The device as recited in claim 16 wherein the swirling device includes a plurality of permeable openings and wherein a mean diameter of the openings increases in a direction of flow.

22. The device as recited in claim 12 further comprising at least one heating element.

23. The device as recited in claim 22 wherein the at least one heating element includes an electrical resistance heater.

24. The device as recited in claim 23 wherein the electrical resistance heater includes a glow plug.

25. The method as recited in claim 1 wherein the intended use includes a use by a fuel cell of a vehicle.

26. The method as recited in claim 25 further comprising operating the fuel cell for a propulsion of the vehicle.

27. The method as recited in claim 25 further comprising operating the fuel cell for supplying the vehicle with electric energy.

28. The method as recited in claim 27 wherein the electrical energy is supplied for an auxiliary power unit of the vehicle.