Device for steam reforming of hydrocarbons

The invention relates to a system for the steam reforming a hydrocarbon. Plants of this type are, for example, in mobile use in fuel cell powered Motor vehicles for the steam reforming of liquid entrained Methanol used by the fuel cell for the provide necessary hydrogen, without a larger Hydrogen storage to need. For this application, is a compact version of the system called for, with relatively realize low weight and minimum effort leaves. Furthermore, for the motor vehicle application, a rapid response of the system to load changes desired purpose turn a compact design is low. Other desirable Properties just are such mobile systems a high efficiency and low cost control and regulation, thereby achieving high system reliability leaves.

There are systems of the aforementioned kind is known, in where to achieve a compact design, certain plant components are integrated into a respective common component. So are described in the publications JP 62138306 A, JP 63021203 A and JP 63040701 A describes reforming systems, in which of the reforming reaction by leading reformer and a upstream evaporator integrated in a common reactor component are, the further a burner is assigned, in which a fuel is burned under kindling to the evaporator direct heat. In addition it can be provided to Reformer for heating by the hot combustion gases of the burner.

When in the patent US 5,516,344 disclosed reformer the reformer together with a downstream CO shift converter integrated in a common component, is associated with a burner supplied one, combustible mixture under ignition burns. With the hot Combustion gases are then among other things the reformers and the CO shift converter heated up.

In the published patent application JP 07126001 A is a plant of described initially mentioned type, the modular reactor a includes the plate stack type. This includes modular reactor integrates an evaporator, a reformer and a CO oxidizer, these three system components in series in a stack transversely one behind the other in the form of a first group plate layers are arranged. the evaporator is a burner upstream, in which a supplied mixture is burned ignition. The hot combustion gases be parallel to the reforming gas through a second group plate layers of a heat exchanger structure forming plate stack passed, the with those of the first group alternate, and heat characterized the evaporator, the reformer and the CO oxidizer on.

In the patent US 4,746,329 is a methanol reforming reactor with a cylindrical structure consisting of several radially successive Annuli disclosed. On the underside of Reactor cylinder is a burner unit of a catalytic burner can be formed. The hot burner exhaust be the radially outermost annulus upwards out and then deflected in the radially inwardly adjacent the annular space, where in thermal contact with a radially inner subsequent Reforming annulus are. Here, an upper cover Part of the reforming space on the outer, the combustion gas leading beyond annular spaces, so that in this area a lower operating temperature prevails. This cooler, upper Reforming space area serves as a CO shift unit. To the Reforming room joins the inside of an evaporator annulus which in turn radially inwardly over a cylindrical wick adjacent to an internal tempering, in which the combustion gases by the downward flow of the second outermost annular space are deflected in the lower cylinder region. As fuel for the burner unit is the hydrogen-containing anode gas a fuel cell system. The combustion exhaust gases therefore contain water vapor from which to escape the combustion gases on the upper cylinder end face at least a portion is supplied to the evaporator.

In the published patent application DE 38 03 080 A1 a reformer to produce hydrogen, carbon monoxide and Carbon dioxide-containing synthesis gases from hydrocarbon Feedstocks and an operating method therefor known with which the starting materials initially a least stage primary reforming, then a partial oxidation, then another, secondary reforming and Finally, a carbon monoxide conversion are subjected. there the waste heat from the exothermic carbon monoxide conversion for used the primary steam reforming, including the appropriate primary reforming stage and the CO shift stage via a heat conductive partition wall in thermal contact are.

The invention is the technical problem of providing a plant of the type mentioned above, the comparatively a high efficiency and also for the mobile Use sufficient in fuel-cell vehicles has momentum with little control and regulation expense and the very compact and with relatively little effort can build.

The invention solves this problem by providing a System with the features of claim 1. This system includes a reactor unit of the plate stack type or tube type or a combined of both types type, the least an evaporator, a prereforming, a main reformer, a CO removal unit, and a catalytic burner unit contains in integrated form. With the presence these components can be a reforming conversion with high achieve efficiency, wherein the concentration of the reformate gas Carbon monoxide contained by the CO removal unit can be limited to a desired value. The integrated Formation of these system components in the common modular reactor creates the conditions for a high dynamic range of the system, so that they in a satisfactory manner to changes in load can react, such as those for the operation of motor vehicles are typical. The operational behavior of the system is further characterized favorably influenced, on the one hand, the evaporator and the Main reformer with the catalytic burner unit and the other part the prereforming unit to the CO removal unit Directors on a thermally conductive separation medium in thermal contact to stand.

In a further developed according to claim 2 system includes the Burner unit at least two catalytic burner, of which the one with the evaporator and the other to the main reformer to form each of a module with heat exchanger structure in Thermal contact is. The modular design of the evaporator / Nitro component and favors the main reformer / burner component a flexible, modular design of the reactor unit.

In a further developed according to claim 3 includes the system Prereforming as two stages as the CO removal unit, with the latter from a CO shift stage and one of these downstream CO oxidation stage composed. In this form the CO oxidation stage with the first prereforming and the CO shift stage to the second prereforming per a module with heat exchanger structure. This modular design favors in turn, to an increased extent when using together with the evaporator / burner and the main reformer / burner module the designed claim 2 system, a compact, modular design of the reactor unit and thus the plant a total of. In this case, in a further embodiment of this Modular construction the respective four modules according to claim 4 adjacently arranged. In a further embodiment This measure is in accordance with claim 5 thermally insulating Separation elements between successive modules are provided.

In a further developed according to claim 6 plant are in oxidation / prereforming module and / or the shift stage / prereforming module Heating channels are provided through which hot combustion exhaust gas carried out the catalytic burner unit can be to heat these modules active.

Advantageous embodiments of the invention are in the drawings shown and described below. in this connection show:<dl tsize="7"><dt>Fig. 1</dt><dd>a schematic longitudinal section through a reactor unit the plate stack type for a system for the steam reforming a hydrocarbon,</dd><dt>FIG. 2</dt><dd>a schematic longitudinal sectional view of a further reactor module the plate stack type for a plant for Steam reforming of a hydrocarbon,</dd><dt>Fig. 3</dt><dd>a plan view of a modular reactor for the Fig. 1 and 2 usable single disc and</dd><dt>Fig. 4</dt><dd>a plan view of a built-up according to FIG. 1 reactor unit.</dd></dl>

The reactor unit shown schematically in Fig. 1 from Plate stack type is suitable as a central part of a plant for Steam reforming of a hydrocarbon, in particular a mobile system for the steam reforming of methanol in mobile use in a fuel cell powered vehicle, to the level necessary to fuel hydrogen from liquid to produce methanol carried. In the modular reactor are an evaporator 1, a downstream thereof prereforming with a first prereforming 2 and one of these downstream second prereforming 3, a subsequent to the second prereforming stage main reformer 3 4, a main reformer downstream CO removal unit downstream from a CO shift stage 5 and one of these CO oxidation stage 6 and two catalytic burner 7, 8 are integrated.

Here, the catalytic burner 7 is connected to the evaporator 1 in thermal contact by these two system components of a corresponding evaporator / burner module 9 are formed, the a Plate stack structure with a heat exchanger structure has, wherein a plurality of parallel layers of the evaporator 1 on the one hand and the burner 7 on the other hand, in alternating sequence are arranged and thus each have a thermally conductive Plattenwandung are in thermal contact. The evaporator / burner module 9 has a burner inlet 10 with associated distribution channel to the parallel burner layers and an evaporator inlet 11 with associated distribution channel for supplying methanol and Water to the parallel evaporator layers.

At the evaporator / burner module 9 a oxidation / prereforming module includes 12 which, in turn a plate stackup has with heat exchanger structure in which two Groups each have next, parallel among themselves plate layers via thermally conductive plate walls in thermal contact to stand. The group belongs plate layers the first prereforming 2, while the other group plate layers the CO oxidation stage 6 represents. Matching has the oxidation / prereforming module 12 an air inlet 13 with an associated distributor channel the CO oxidation stage 6 and one of the CO oxidation stage 6 laxative reformate 14 with associated Collecting channel, said air inlet 13 and the reformate 14, the evaporator / burner module prevail. 9 Also leads a connecting channel 15 with verdampferseitigem collection channel and vorreformierungsseitigem distribution channel from the evaporator 1 to the first Prereforming. 2

Adjoining the oxidation / prereforming module 12, a shift stage / prereforming module 16 of which likewise as a plate stack with a heat exchanger structure of two Groups alternating, via respective plate walls in thermal contact standing board layers is constructed. It forms the group plate layers the second prereforming 3, while the other group plate layers the CO shift stage 5 forms. A connecting channel 17 with appropriate inlet-outlet-collecting channel and Distribution channel leads from the output of the first prereforming 2 to the input of the second prereforming stage 3, and a further connecting channel 18 leads from the outlet of the CO shift stage 5 for input of the CO oxidation stage. 6

At the shift stages / prereforming module 16 includes itself Reformer / burner module 19 to, in turn, in the form of a disk stack assembly with a heat exchanger structure, wherein the two groups plate layers to one another via corresponding Plate walls are in thermal contact. The one group over the next Plate layers forms the main reformer 4, while the other group plate layers the associated catalytic burner 8 forms. The reformer / burner module 19 is associated with a connecting channel 20 from the outlet the evaporator side burner 7 to the inlet side of the reformer-side Burner 8 leads, while the intermediate modules 12 and 16 passes. Through the connecting channel 20, the two catalytic burner 7, 8 connected in series. About a 20a in the connecting channel 20 debouching inlet may additionally oxygen-containing gas and optionally also for fuel the reformer-side burner 8 metered into the connecting channel 20 will. The combustion exhaust gas exits the reformer side catalytic burner 8 via an exhaust outlet 21 with associated Collecting duct. A connecting channel 22 with inlet- Collecting duct and outlet-plenum leads from Main reformer 4 for CO shift stage 5, and a further connecting channel 23 with inlet-outlet-collecting channel and Distribution channel leads from the second prereforming 3 to the main reformer. 4

Fig. 2 shows another reactor unit, which in their construction substantially corresponds to that of Fig. 1, for functionally similar elements use the same reference numerals are. The reactor unit of FIG. 2 differs from that of FIG. 1 in that the various modules 9, 12, 16, 19 not directly but with the interposition of a respective thermally insulating plate 24, 25, contiguous 26th Thereby the evaporator / burner module 9 from the oxidation / prereforming module 12, this turn from the shift stages / prereforming module 16 and this in turn by the reformer / burner module 19 thermally decoupled.

As can be seen, the two modular reactor of FIG. 1 and 2 a particularly compact design while integrating all for the steam reforming of methanol or advantageous another hydrocarbon with high efficiency Components in the form of an evaporator 1, a two-stage Prereforming 2, 3, a main reformer 4, a two-stage CO removal unit 5, 6 and each of a catalytic Burner 7, 8 for evaporator 1 and main reformer 4. Each Module 9, 12, 16, 19 may consist of an individually definable number are constructed of plate laminations, so that by simple Modifications optimum adaptation to the respective Application is possible and different performance classes for each of the integrated into the modular reactor plant components be realized. In addition to the illustrated modules 9, 12, 16, 19 the plate stack type using an alternative functional same modules tube type for one or more the modules 9, 12, 16, 19 is possible.

Instead of the illustrated design of the modules 9, 12, 16, 19, in which the stack of plates each have a plate layer of a plant component with a plate layer of the other plant component the module alternates and therefore the ratio of the number the disc layers for the two components substantially 1: 1, are modified as needed modules with any other ratio of the board layer number of the respective System components used.

A further modification of the modular reactor shown in Figs. 1 and 2 is within the CO removal unit provide a multi-stage designed CO oxidizer. at a further variation not shown, are in the oxidation / prereforming module 12 and / or in the shift stage / prereforming module 16 Heizplattenschichten integrated with the hot combustion exhaust gas of the catalytic burner unit 7, 8 can flow through them.

The compact design of the modular reactor has only a minor Footprint and has due to the low surface comparatively low heat losses. The result is a high Efficiency of the system, which also contributes that the waste heat the CO oxidation stage 6 and the CO shift stage 5 for heating the Prereforming stages 2, is used 3rd By disk stack assembly and the arrangement of the various functional components the plant act self-regulatory mechanisms that maintain the control and regulation burden on the system and at the same low ensure a high reliability of the system. Due to the low volume of the reactor module and the short Gas flow paths having the reactor unit and thus the plant total a relatively high dynamics and rapid Heating behavior during cold starting, as especially for the mobile use in fuel-cell vehicles is desirable because the there typical, rapid load changes, as the total mass of the reactor unit is relatively low and Also integrated heating elements in the form of the catalytic burner are. The modular construction enables easy upscaling on each performance of each desired Investment.

Fig. 3 shows a plan view of a heat exchanger plate 27, as defined in the modular reactor of FIGS. 1 and 2 for the evaporator / burner module 9 and in largely similar design is suitable for the other modules. At the opposite Plate narrow sides are three openings 28, 29, 30, 31, 32, 33 provided, respectively coincident openings of the stack successive plates to form corresponding inlet or outlet channels or distribution or collecting ducts in alignment overlap. In the disk 27 of Fig. 3 forms the central to 29, 32 pair of opposite openings of a part relevant collection and distribution channel, for example, of the evaporator 7 and acts as a fluid inlet or fluid outlet. The fluid through the inlet passes into the plane of the plate 27 and there flows along a provided on the panel support and Manifold structure 34 to the opposite outlet, wherein by flowing along the other side of the plate medium For example, the hot burner exhaust gas, enters into thermal contact. The rest, in Fig. 3 thick framed subscribed openings 28, 30, 31, 33 and the plate edge 35 form gas-tight connections, with which the other media in the plate package the relevant can plate layer happen. These openings 28, 30, 31, 33 For example, part of the burner inlet 10, the Reformatgasauslasses 14, the air inlet 13 for the CO oxidation stage 2 and the connecting channel 20 from the evaporator side Brenner 7 be the reformer-side burner. 8

Fig. 4 shows a top view of the compact reactor unit of Fig. 1 with its plate stack design, which in this view two inputs and outlets 36, 37 on a stack face end and another input or outlet 38 at the opposite stack face end can be seen. In addition, the extension of corresponding to the disk stack structure in order to form Inlet or outlet channels or distribution or collecting channels 39, 40, indicated by dashed lines 41. Further, one of the inner Connecting channels indicated 42 in phantom. The remaining Inlets and outlets also open at the stack ends and are in the view of FIG. 4 of the inputs or outlets shown 36, 37, 38 masked.