DE10143656B4 - A method of generating energy in a cracking reactor fuel cell fuel cell system and apparatus for carrying out the method - Google Patents

Abstract

A method of generating energy in a cracking reactor fuel cell fuel cell system comprising the steps of:
a. Feeding at least one hydrocarbon into a cracking reactor having at least a first cracking chamber and at least one second cracking chamber in the absence of oxygen;
b. Endothermic cracking of the hydrocarbon in the cracking reactor with the exclusion of oxygen in carbon and a hydrogen-containing gas mixture and removal of the hydrogen-containing gas mixture;
c. Interrupting the feed of the hydrocarbon into the cracking reactor;
d. Supplying water vapor or a combination of water vapor and air into the cracking reactor;
e. Gasifying the in crack step b. obtained carbon with water vapor or a combination of water vapor and air to a carbon monoxide and hydrogen-containing gas mixture and further use of the gas mixture thus obtained in the fuel cell system;
Feeding the in cracking step b. obtained hydrogen-containing gas mixture in the fuel cell and oxidizing the hydrogen in the fuel cell with the production of heat and electrical energy, wherein ...

Description

object This invention is a method for generating energy in a fuel cell system with cracking reactor and fuel cell and a device for carrying out the method.

It are already a variety of methods and devices for the production of fuels, in particular of hydrogen as most environmentally friendly fuel for fuel cells for recovery of electrical energy and heat by electrochemical reactions between the fuel and atmospheric oxygen been proposed.

• (a) „solid oxid fuel cells" (SOFCs),
• (b) „molten carbonate fuel cells" (MCFCs),
• (c) „phosphoric acid fuel cells" (PAFCs),
• (d) „alkaline fuel cells" (AFCs), und
• (e) „solid polymer fuel cells" (PEFCs).

In the prior art, a total of five types of fuel cells are known:

• (a) solid oxide fuel cells (SOFCs),
• (b) molten carbonate fuel cells (MCFCs),
• (c) "phosphoric acid fuel cells" (PAFCs),
• (d) "alkaline fuel cells" (AFCs), and
• (e) solid polymer fuel cells (PEFCs).

The Use of hydrogen in the low-temperature fuel cells PEFC and AFC as fuel cause a very high purity of the Hydrogen, since the operation of PEFCs by carbon monoxide and the of AFCs is affected by carbon dioxide.

• 1. Dampfreformierung, d.h. die endotherme katalytische Umsetzung mit Wasser,
• 2. Partielle Oxidation, d.h. die teilweise Umsetzung des Brennstoffes mit Sauerstoff und/oder Luft zu einem wasserstoffreichen Gasgemisch,
• 3. Autotherme Reformierung, d.h. eine Kombination aus Dampfreformierung und partieller Oxidation mit gleichzeitiger Zugabe von Wasser/Wasserdampf und Sauerstoff bzw. Luft, und
• 4. Cracken, d.h. endotherme Spaltung von organischen Verbindungen.

Currently about 90% of hydrogen is produced from fossil fuels of all kinds. The most preferred source of hydrogen is natural gas. From the various available hydrogen-containing organic compounds, such as hydrocarbons, the required hydrogen can be obtained, for example, by the following four process principles:

• 1. steam reforming, ie the endothermic catalytic reaction with water,
• 2. Partial oxidation, ie the partial conversion of the fuel with oxygen and / or air to a hydrogen-rich gas mixture,
• 3. Autothermal reforming, ie a combination of steam reforming and partial oxidation with simultaneous addition of water / steam and oxygen or air, and
• 4. Cracking, ie endothermic cleavage of organic compounds.

details can on pages 302 to 317 of the monograph Fuel Cells and Their Applications are taken from Karl Kordesch and Günter Simader, which of the VCH Verlagsgesellschaft mbH, Weinheim, Germany, 1996 was published.

It is known that steam-reforming of hydrocarbons, particularly methane as the main constituent of natural gas, can produce a hydrogen-containing product gas. Industrial steam reforming technology typically includes a desulfurization unit and a high temperature reactor (800 to 900 ° C) that includes a catalyst. Since, depending on the reaction parameters of pressure, temperature and water vapor excess, after the reforming stage, concentrations of CO are above 10% by volume, two further reaction stages are often connected downstream in order to reduce the carbon monoxide content and to obtain further hydrogen, the so-called shift converters. The conversion takes place after the exothermic homogeneous water gas reaction CO + H ₂ O → CO ₂ + H ₂ Δ _R H ⁰ = -41 kJ / mol in two temperature stages, the high-temperature shift (HT shift) on a Fe / Cr catalyst at temperatures between 330 and 500 ° C and the low temperature shift (TT shift) on a CuZn catalyst at 190 to 280 ° C. Thereafter, the hydrogen-rich gas mixture still contains a carbon monoxide content of about 0.5-1%.

in the Result of the industrial steam reforming of natural gas is one Product gas containing about 75% of hydrogen and to 25% consists of carbon dioxide.

Especially for the Use of the generated hydrogen in a PEFC fuel cell proves the production of hydrogen by steam reforming insofar as disadvantageous, since such a high proportion of carbon monoxide in the product gas leads to inactivation of the catalysts in fuel cells and consequently a costly removal of carbon monoxide from the product gas obtained is required.

As mentioned can these disadvantages in hydrogen production by thermal or catalytic cracking of hydrogenated organic compounds be avoided.

there In particular, the choice of the catalyst used is important. To select a suitable catalyst have already been some Studies on the suitability of certain catalysts carried out. So were e.g. from palladium, rhodium, nickel, cobalt or iron alumina-based catalysts for their activity and stability for the cleavage process and tested the regeneration step. It turned out that all of the aforementioned catalysts in principle for the production of hydrogen suitable, but they have a long-term activity for improvement.

The product gas of cracking that occurs in the we consists essentially of H ₂ and CH ₄ may, after leaving the cracking reactor still contain traces of CO and CO ₂ , resulting from the regeneration of the cracking chamber. The carbon monoxide in the product gas is due to partial oxidation of the catalyst during the regeneration process. Since the partially oxidized catalyst is again reduced immediately at the beginning of the cleavage, consequently, carbon monoxide will also be formed at the beginning of a catalytic cleavage with a freshly regenerated catalyst.

In The fuel cell itself may be due to the flow path decreasing hydrogen partial pressure of the present in the gas mixture Hydrogen not complete be exploited, but only a certain proportion (fuel utilization factor), which is often about 80% of the hydrogen offered.

Even though is already known, deposited on the fixed bed catalyst carbon by burning to heat to use, the heat is generated directly on the catalyst and therefore can not readily due to the relatively poor thermal conductivity of catalyst beds too be guided to another place.

Of further it is desirable the resulting in the reactor chamber in the catalytic cleavage or unreacted methane, or in the methanation resulting methane also for the production of hydrogen for the fuel cell to use. Because the performance of a fuel cell immediately is dependent on the hydrogen content of the fuel cell supplied product gas is it also desirable the hydrogen content compared Product gases from known in the art come, to increase further.

In the patent DE 690 30 651 describes an electrochemical reactor with a multicomponent solid-state membrane for a continuous process for transporting oxygen, from one oxygen-containing gas to another gas reactant consuming oxygen, which is said to facilitate inter alia the electrocatalytic conversion of light hydrocarbons to synthesis gas.

A method for improving the desulfurization step in fuel cell power generation processes, in which petroleum products are used as starting fuels and fuels, as well as the desired diversification of the fuels used is in DE 690 09 432 disclosed.

In DE 199 31 104 is reported about a device for generating hydrogen gas, said device being provided on board a motor vehicle.

A reaction bed for a catalytic cracking plant of hydrocarbons is out DT 24 53 089 known. Here, two identical reaction vessels are connected together so that they can be operated in push-pull, with one vessel performing a cracking cycle while the other vessel performs a burning or regeneration cycle. The cycle time is limited by the stored energy. The carbon deposited in the cracking cycle is cleaned off or reacted with oxygen in the regeneration cycle and then leaves the cracking system without further thermal utilization.

in the State of the art are no solutions to known the aforementioned problems. The object of the invention is therefore, in providing a method and apparatus for generating electrical energy and heat in a total fuel cell system, wherein the resulting product gas has an increased hydrogen content and the fuel utilization factor is increased.

• a. Zuführen mindestens eines Eduktes in einen Crackreaktor mit mindestens einer ersten Crack-Kammer und mindestens einer zweiten Crack-Kammer unter Ausschluß von Sauerstoff;
• b. Endothermes Spalten des Eduktes in dem Crackreaktor unter Ausschluss von Sauerstoff in Kohlenstoff und ein wasserstoffhaltiges Gasgemisch und Abführen des wasserstoffhaltigen Gasgemisches
• c. Unterbrechen der Zuführung des Eduktes in den Crackreaktor;
• d. Zuführen von Wasserdampf oder einer Kombination aus Wasserdampf und Luft in den Crackreaktor;
• e. Endothermes Vergasen, bzw. kombiniertes endothermes Vergasen und exothermes Verbrennen des in Crack-Schritt b. erhaltenen Kohlenstoffs mit Wasserdampf bzw. Wasserdampf/Luft zu einem Kohlenmonoxid und Wasserstoff enthaltenden Gasgemisch und Weiterverwendung des so erhaltenen Gasgemisches in dem Brennstoffzellen-Gesamtsystem;
• f. Zuführen des in Crack-Schritt b. erhaltenen wasserstoffhaltigen Gasgemisches in die Brennstoffzelle und Oxidieren des Wasserstoffes in der Brennstoffzelle unter Gewinnung von Wärme und elektrischer Energie.

The invention therefore relates to a method for generating electrical energy and heat in a cracking reactor and fuel cell fuel cell system comprising the following steps:

• a. Feeding at least one educt into a cracking reactor having at least a first cracking chamber and at least one second cracking chamber in the absence of oxygen;
• b. Endothermic cleavage of the educt in the cracking reactor with the exclusion of oxygen in carbon and a hydrogen-containing gas mixture and removal of the hydrogen-containing gas mixture
• c. Interrupting the feed of the educt into the cracking reactor;
• d. Supplying water vapor or a combination of water vapor and air into the cracking reactor;
• e. Endothermic gasification, or combined endothermic gasification and exothermic burning of the in cracking step b. obtained carbon with water vapor or water vapor / air to a carbon monoxide and hydrogen-containing gas mixture and further use of the resulting gas mixture in the fuel cell system;
• f. Feeding the in cracking step b. obtained hydrogen-containing gas mixture in the Brenn substance cell and oxidizing the hydrogen in the fuel cell with the production of heat and electrical energy.

The invention thus relates in particular to a fuel cell system in which the hydrogen processor is based on the thermal or additionally catalytic cracking of hydrocarbons (eg natural gas, methane, propane, butane, LPG, gasoline, fuel oil, diesel etc.), alcohols, aldehydes and organic acids (> C ₂ ) based. This can produce a product gas with a high hydrogen content.

The invention preferably relates to two embodiments of the method according to the invention, the hydrogen production process of which is based on thermal or additionally catalytic cracking. The product gas is used in a fuel cell, where electrical power and heat are generated. The two exhaust gas streams, the anode exhaust gas (H ₂ , N ₂ , CH ₄ , H ₂ O) and the cathode exhaust gas (air, N ₂ , O ₂ , H ₂ O) are preferably used in-process in the overall system.

in principle is the procedure for all fuel cell types except for the direct methanol fuel cell used. The method is also suitable in principle for a wide power range from a few watts to a few hundred kW and for a variety of Mobile, portable and stationary applications.

An essential feature of the method according to the invention for fuel cell system is the process of hydrogen production via the thermal or catalytic cracking of liquid or gaseous fuels, with propane initially serving as an example in the following. At high temperatures, eg above 800 ° C, propane is decomposed on a catalyst into its constituents carbon and hydrogen: C ₃ H ₈ → 3C + 4H ₂ Δ _R H ⁰ = 103.8 kJ / mol.

The generated gas mixture then consists of over 90% hydrogen, the rest is almost exclusive Methane, an intermediate of the cracking process, which stops the operation a fuel cell practically not affected.

About this procedurally simple process can be done without complex and elaborate Gas purification processes can be represented as a hydrogen quality even for the Use in a membrane fuel cell (PEFC) is suitable. The Hydrogen production by catalytic cracking may therefore occur in a very inexpensive System running become.

The Cracking system is preferably in batch operation with at least two Reactors or in a reactor system with at least two crack chambers driven, one or more of which are in the cracking cycle, while the other or the others simultaneously from the accumulated carbon getting cleaned.

The Cleaning the chambers can be done in several ways. The easiest way is first the exothermic burning off of the carbon with atmospheric oxygen, such as in U.S. Patent 3,962,411. However, this leads to high thermal Loads on the catalysts.

According to the invention this is done by an endothermic gasification of the solid carbon with water vapor or a combined combustion / gasification with a mixture of water vapor and air. This results in a synthesis gas of CO and H ₂ (possibly also CH ₄ , CO ₂ and N ₂ ), the energy content can be used for example in the burner, the reactors to the required for cracking or steam gasification temperatures of about 800 heats up to 900 ° C.

One important advantage of this procedural concept is the Avoidance of high regeneration temperatures during cleaning, what has a very positive effect on the life of the catalysts.

During the Cracking process and the Wasserdampfregenerierung provides the burner the needed Heat of reaction, the heat loss as well as the heat available for water evaporation, as far as these are not due to heat recovery or heat integration of the process can be delivered.

When Alternative can also use external electric heating become. When using catalysts on electrically conductive metal honeycomb can these are also brought directly to the operating temperature by passage of current or held. Also conceivable is a combination of both heating methods, in which can be quickly electrically heated for commissioning, and a burner is used for further operation.

Although the process according to the invention can be operated in a single-chamber cracking reactor, in particular one or more intermediate storages can be used in which the gas discharged from the cracking chamber can be stored and, if necessary, purified via a gas purification stage, fed to the fuel cell, In a preferred embodiment of the method according to the invention, a method in which a cracking reactor with at least one first chamber and at least one second chamber is used, wherein at the beginning of the process in step a. the first chamber is filled continuously with the educt, in the first chamber filled in this way the endothermic cleavage according to step b. is performed, the supply of the educt into the first chamber according to step c. is interrupted, according to step d. Water vapor or a water vapor / air mixture is supplied into the first chamber and the gasification step e. is performed in the first chamber. At the beginning of step c, the feed of the educt is switched from the first chamber to the second chamber. In the second chamber, the process steps a. till B. performed while in the first chamber, the process steps d. and e. be carried out for gasification / combustion of the deposited carbon. After removing the carbon in step e. In the first chamber, the cycle is carried out anew and it can again be fed to the educt of the first chamber, wherein in each case in step b. formed hydrogen-containing gas mixture is discharged to the fuel cell.

at this embodiment The method is a continuous supply of fuel gas to the fuel cell without buffering enabled.

Especially preferred is a multi-chamber cracking reactor system with at least used three chambers, whose chambers in at least two chamber groups subdivided as described above and wherein in the chamber groups the steps a. to e. be carried out offset in time.

at Fuel cells, where carbon monoxide acts as a catalyst poison, becomes the fuel cell supplied hydrogen-containing gas mixture preferably before the feed into the fuel cell of an intermediate treatment for lowering subjected to the carbon monoxide content.

In a variant of the method according to the invention this is done in step e. formed carbon monoxide and hydrogen containing gas mixture for producing the in the process, preferred in process steps b. and e. required heat energy used.

at this embodiment The content of carbon monoxide is already relatively low. Because too The content of carbon dioxide is very low, therefore, that of the fuel cell supplied hydrogen-containing gas mixture before being fed into the fuel cell Be subjected to methanation, in which the carbon monoxide and the carbon dioxide is converted into methane.

If in a second embodiment of the method in step e. educated, essentially carbon monoxide and hydrogen gas mixture in step b. discharged hydrogen-containing Gas mixture is added to increase its energy content, is that supplied to the fuel cell hydrogen-containing gas mixture before being fed into the fuel cell a shift conversion treatment, and optionally a further fine cleaning to reduce the Subjected to carbon monoxide.

at all embodiments of the method, the in step b. discharged hydrogen-containing gas mixture supplied to a memory from which in turn the hydrogen-containing gas mixture of the fuel cell supplied becomes.

Prefers becomes in step a. of the process, the starting material used in the cracking reactor in gaseous form Condition, preferably added in an inert gas atmosphere. That in step a. used Starting material is preferably selected from lower alkane, alkene and alkyne hydrocarbons, alcohols, Aldehydes, ketones and organic acids with up to 30, preferably 20 carbon atoms or mixtures thereof.

Height Reaction rates and / or lower temperatures for cracking can through the use of catalysts can be achieved. In recent years are studies on the catalytic cracking of light Hydrocarbons, mostly propane, butane, LPG, natural gas and fuel oil has been performed. The studies showed that materials based on Pd, Rh, Ru, Ni, Co and Fe are best for this application are suitable. There are so far in the literature however, no lifetime studies on real catalysts at Cracking of hydrocarbons has been made. Furthermore also show the carbon particles formed during the cracking process a certain catalytic activity for the cracking process on (autocatalysis). There are no commercial catalysts for cracking to date for the production of hydrogen, since this process is not yet is used. The catalysts are made by the cracking process and the subsequent cleaning step considerably thermally and mechanically loaded, so that commercially available catalysts, the the o.a. Materials are not stable to the cycle. thats why from the inventors a special, stabilized noble metal catalyst has been developed over several hundred cycles (cracking and regeneration) without measurable Degradation was tested.

In contrast to the prior art according to US Pat. No. 5,899,175, the product gas mixture when carrying out the process according to the invention contains no condensates at room temperature ren constituents. The arrangement of the catalyst, ie the void volume in the region of the catalyst must allow the deposition of the carbon, so that no unacceptably high back pressure can build up. This can be done, for example, with a catalyst bed, but other geometries are possible, such as coated heat exchangers, coated with catalyst material metallic or ceramic carrier, eg honeycomb carrier (Honeycombstrukturen) etc.

For higher energy utilization of the gas used is the anode exhaust gas in 1 is preferably admixed with the educt stream fed to the cracking catalyst or in 2 for producing the in the process, particularly preferably in the process steps b. and e. required heat energy used in the burner.

The endothermic catalytic columns and the endothermic catalytic Gasification is preferred according to the invention in a temperature range from 500 to 1000 ° C, preferably from 700 to 1000 ° C and especially preferably 800 to 900 ° C done while the thermal splitting takes place at much higher temperatures.

The The present invention is also directed to an apparatus for carrying out the Method according to one of the preceding claims.

The method according to the invention will be explained further with reference to the following two embodiments. This concerns in 1 showed a fuel cell system with cracking and methanation while that in 2 shown method relates to a fuel cell system with cracking, shift conversion and CO fine cleaning.

This in 1 shown fuel cell system is in principle suitable for various applications in the mobile, portable and stationary. The fuel is fed to the cracker system and disproportionated in one of the chambers at high temperatures on a catalyst in its constituents carbon and hydrogen, if necessary. Also CO and CO ₂ (when using oxygen-containing fuels). The catalyst increases the reaction rate, or allows the operation of the system at lower temperatures, but in principle is not essential.

The product gas, consisting essentially of H ₂ and CH ₄ , may still contain traces of CO and CO ₂ resulting from regeneration of the cracking chamber after leaving the cracking reactor. Both carbon monoxide and carbon dioxide can be almost completely converted to methane with hydrogen in the following methanation stage. The carbon monoxide is a strong catalyst poison for a membrane fuel cell (PEFC). Since CO adsorbs on the anodic noble metal catalyst platinum, it would deactivate it after a short time. PEFC systems therefore require fuel gases with a very low CO content, which can just be represented by the cracker without otherwise complex CO fine cleaning alone with a simple methanation. The methanation requires no complicated regulation.

The fuel gas then consists almost entirely of hydrogen and methane, which is a harmless inert gas for the fuel cell. For the use of an alkaline fuel cell (AFC), which is sensitive to CO ₂ , the product gas is therefore also ideally suited. For PAFC and SOFC can be dispensed with the methanation, the PAFC tolerated because of their operating temperature of 200 ° C up to about 1 vol .-% CO, for the SOFC is carbon monoxide even a fuel gas.

The product gas (hydrogen and methane) is now converted into electricity in the fuel cell. It creates electrical energy and heat. However, a fuel cell can not fully utilize the fuel hydrogen in a gas mixture, but only a certain proportion due to the hydrogen partial pressure decreasing along the flow path, as indicated by the fuel utilization factor, which is often about 80% of the offered H ₂ .

The remaining hydrogen remaining in the exhaust gas is in this embodiment ( 1 ) of the system, together with the inert methane (anode exhaust gas), are then preferably first passed through a condenser to reduce the water content of the anode exhaust gas and then returned to the cracking reactor. The hydrogen returns as a component of the product gas to the fuel cell, while the methane is split in the cracking reactor in carbon and hydrogen.

On This way is inventively despite the for gas mixtures inevitable fuel utilization factor of a Fuel cell through the return of the Anode exhaust a nearly more complete Sales of hydrogen in the reactant for power generation reached.

The likewise moist cathode exhaust gas, consisting of unreacted atmospheric oxygen, atmospheric nitrogen and water vapor, is preferably first also passed through a condenser before it is released into the environment. The water of the two capacitors is collected and then stands for the steam gasification of the Koh lenstoffs in the cracking reactor and, if necessary, for the humidification of the fuel cell gases available.

The carbon accumulated in the reactor during the cracking cycle is completely or partly gasified by the steam, which is preferably produced from the condensate. But it can also be supplied from the outside water for the regeneration step. This results in a synthesis gas mixture with high CO and H ₂ content with a significant calorific value, which can be used for the supply of the burner. The energy content of the synthesis gas is sufficient in principle for the supply of the cracking system.

For the complete regeneration the reactor chamber, i. the complete removal of the accrued Carbon, it may be necessary to steam the gasification to combine with a combustion of carbon with air.

• – Vollständige Vergasung mit Wasserdampf,
• – Kombinierte Regeneration durch Vergasung mit Wasserdampf und Verbrennung mit Luftsauerstoff, wobei Wasserdampf und Luft dabei gleichzeitig, nacheinander oder in zyklischer Folge eingebracht werden können,
• – Kombinierte Regeneration durch Vergasung mit Wasserdampf und Verbrennung mit Luftsauerstoff und mit Brennerabgas, wobei Wasserdampf, Luft und Abgas dabei gleichzeitig, nacheinander oder in zyklischer Folge eingebracht werden können.

In this way, according to the invention, the energy content of the deposited carbon via the synthesis gas production can be used for the heat supply of the system. The use of the deposited carbon may alternatively be carried out as follows:

• Complete gasification with steam,
• Combined regeneration by gasification with water vapor and combustion with atmospheric oxygen, water vapor and air being introduced simultaneously, successively or in cyclical sequence,
• - Combined regeneration by gasification with water vapor and combustion with atmospheric oxygen and with burner exhaust gas, whereby water vapor, air and exhaust gas can be introduced simultaneously, successively or in a cyclic sequence.

By the regeneration with water vapor, or the combined regeneration With water vapor, atmospheric oxygen and / or burner exhaust gas is a Lowering of the reactor temperature compared to a cleaning by pure combustion of the carbon with atmospheric oxygen and thus achieved protection of the catalysts.

This in 2 shown fuel cell system with cracking, shift conversion and CO fine cleaning is in principle suitable for various applications in the mobile, portable and stationary area. The fuel is again fed to the cracker system and disproportionated in one of the chambers at high temperatures, for example on a catalyst in its constituents carbon and hydrogen, if necessary. Also CO and CO ₂ (when using oxygen-containing fuels). In contrast to the first system, however, the synthesis gas (CO and H ₂ ) of the other chambers obtained simultaneously by gasification of the carbon with water vapor is mixed after leaving the cracking reactor system and fed to a shift conversion down to about 200 ° C. Here a part of the CO reacts with water vapor to CO ₂ and additional hydrogen. Subsequently, the gas mixture still contains about 0.3 to 1 vol .-% CO, which can then be reduced in a gas fine purification stage, such as a selective oxidation state, to the permissible for the membrane fuel cell CO contents of eg 20 ppm. For PAFC and SOFC, respectively, future PEFC developments with high CO tolerance can be dispensed with the gas fine cleaning, the PAFC tolerated due to their operating temperature of 200 ° C up to about 1 vol .-% CO, for the SOFC carbon monoxide is even a fuel gas.

The Product gas corresponds to the invention by this process in its composition practically that of a reformate, i. the Product gas, which is produced by steam reforming of the educt would. So can also from higher Hydrocarbons, such as e.g. Fuel oil or diesel, a reformatgasähnliches Gas mixture with hydrogen contents of depending on the starting material 70 to 80% be generated.

A nitrogen content of almost 50%, as is customary in the autothermal reforming or the partial oxidation of hydrocarbons, does not occur in this process. If necessary, in the case of pure water vapor gasification of the deposited carbon, only the low N ₂ content by the PROX of approximately 5% must be taken into account. In the combined regeneration by gasification and combustion (water vapor, flue gas and air), the nitrogen content may be correspondingly higher.

The Product gas (hydrogen and methane) is in turn in the fuel cell to electricity and heat implemented. The remaining, unreacted hydrogen is then like in the first system, if necessary, first via the condenser to reduce passed the water content and then fed to the burner. Of the Water content of the cathode exhaust air is also reduced in the condenser. The condensate is preferred for the Gasification of the deposited carbon used. That here resulting synthesis gas mixture is mixed with the product gas of the reactors, which are in the cracking cycle, mixed.

• – Das Produktgas weist einen hohen Wasserstoffanteil von ca. 70 bis 80% (je nach verwendetem Brennstoff) auf, was zu einer höheren Leistung der Brennstoffzelle führt.
• – Die Vergasung des abgeschiedenen Kohlenstoffs findet mit geringeren Wassermengen statt (S/C-Verhältnis oder Steam to Carbon ratio ca. 1), zusätzliches Wasser wird für die Shiftkonvertierung benötigt, was zu einem S/C-Verhältnis von etwa 2 für den Gesamtprozess führt. Damit wird deutlich weniger Energie für die Wasserverdampfung benötigt, als dies bei einer konventionellen Dampfreformierung mit üblicherweise S/C = 3 der Fall ist.
• – Üblicherweise werden die Schwefelanteile des Brennstoffs vor der Entschwefelung in einem ZnO-Bett durch die Zugabe eines Wasserstoffstroms zu H₂S umgewandelt. Die Integration der Entschwefelungsstufe in den Verlauf des Gasprozesses ist vorteilhaft, da keine Wasserstoffzugabe zur Erzeugung von H₂S aus den Schwefelkomponenten des Brennstoffs mehr erforderlich ist.
• – Das Anodenabgas der Brennstoffzelle, welches Reste von Methan und Wasserstoff enthält, also brennbare Gase, die nicht in der Brennstoffzelle genutzt werden können, wird zum Brenner zurückgeführt und so energetisch sinnvoll zur Erhöhung des Wirkungsgrades des Gesamtsystems eingesetzt.

This hydrogen generation process has the following set of advantages:

• - The product gas has a high hydrogen content of about 70 to 80% (depending on the fuel used), resulting in a higher performance of the fuel cell.
• - The gasification of the deposited coals Substance takes place with smaller amounts of water (S / C ratio or steam to carbon ratio approx. 1), additional water is required for the shift conversion, which leads to an S / C ratio of about 2 for the entire process. This requires significantly less energy for water evaporation than is the case with conventional steam reforming with usually S / C = 3.
• Typically, the sulfur components of the fuel are converted to H ₂ S prior to desulfurization in a ZnO bed by the addition of a hydrogen stream. The integration of the desulfurization in the course of the gas process is advantageous because no hydrogen addition to produce H ₂ S from the sulfur components of the fuel is required more.
• - The anode exhaust gas of the fuel cell, which contains residues of methane and hydrogen, ie combustible gases that can not be used in the fuel cell, is returned to the burner and so energetically useful to increase the efficiency of the overall system.

In 3 is a total fuel cell system according to the interconnection of the invention 1 described, which consists of a cracker q) and a fuel cell p) and is fed as fuel natural gas. The cracking system q) consists here of the cracking chambers d) and s), the burner i) for energy supply, the heat exchangers e) and f) to use the exhaust heat and to use the heat of the gas leaving the chambers, the methanation reactor g) for gas purification , the fuel cell p) and the valves 1 ) to 10) for controlling the gas and water flows.

The two chambers d) and the methanation reactor g) are heated by the burner i) to the temperature necessary for the process. After reaching the temperature, one of the chambers d) with the by the compressor b) promoted natural gas stream, which is desulfurized in the desulfurization stage c), via the valve 1 ) supplied with the natural gas. The hydrogen-rich product gas leaving the chamber then transfers heat to a cooling medium r), for example water, in the heat exchangers e) and f), and passes through the opened valve 5 ) is fed to the methanation reactor g) for removal of carbon monoxide.

Of the Hydrogen of the purified product gas is in the fuel cell p) reacted together with atmospheric oxygen into electricity and heat. Before entering the fuel cell p) is the oxygen-containing If necessary, humidify the gas in a gas humidifier m).

The in the fuel cell p) not completely reacted product gas as well as the originating from the regeneration synthesis gas are mixed and the burner i) supplied to the power supply. Optionally, the performance of the burner can be increased by adding natural gas.

While natural gas is cracked in chamber d), regeneration of the carbon deposited in a preceding cracking cycle takes place in chamber s). The chamber s) is to water over the valve 4 ) and the deposited carbon is gasified with the water, ie converted into a synthesis gas consisting of H ₂ , CO and CO ₂ . The synthesis gas leaving the reactor s) then transfers heat to a cooling medium r) in the heat exchangers e) and f), for example

Water, and is over the valves 8th ) and 9 ) to the burner i) for supplying power to the system. During the regeneration cycle, the valves are 2 ) and 6 ) closed. Before starting the steam gasification in reactor d) chamber s) is purged with natural gas. This will be valve 4 ) and natural gas through the valve 2 ). The gas produced in the purge cycle is delivered through the valves 8th ) and 9 ) is also fed to the burner i), or in another embodiment, subjected to a gas purification step to remove carbon monoxide and supplied to the fuel cell for use.

It is also possible the deposited carbon in a regeneration step through to gasify a water / air mixture, so to clean the chamber again and then begin cracking again in the cleaned chamber.

After flushing chamber s) with natural gas chamber d) is subjected to the regeneration phase and in chamber s) a hydrogen-rich gas for the fuel cell p) is produced. This will be valve 8th ) closed and valve 6 ) open.

a)

Pump / compressor to the air supply of the burner and

of the Fuel cell.

b)

Pump / compressor for the Fuel gas and the cracking gas

c)

desulphurization the cracking gas

d)

cracking reactor

e)

Exhaust gas heat exchanger to use the exhaust heat in the

high temperature range

f)

Exhaust gas heat exchanger and product gas / regeneration gas

heat exchangers. Uses the remaining exhaust heat and

that cools Product gas and the regeneration gas off

the Reactors.

G)

methanation

H)

pump for condensate / regeneration water

i)

burner

k)

combustion chamber for receiving the reactors and the

Heat exchanger

l)

insulation of the combustion chamber

m)

humidifier for the Cathode air of the fuel cell

(Optional)

O)

condensate for product water of the

fuel cell

p)

fuel cell

q)

Crack system with two reactors

r)

fluid for heat exchangers e) and f)

s)

cracking reactor

1)

Valve for cracking gas Reactor A

2)

Valve for cracking gas Reactor B

3)

Valve for air and / or water reactor A

4)

Valve for air and / or water reactor B

5)

Valve for the methanation of the product gas of

reactor A

6)

Valve for the methanation of the product gas of

reactor B

7)

regeneration exhaust from reactor A

8th)

regeneration exhaust from reactor B

9)

Valve to the fuel gas supply

10)

Valve to the air supply of the burner

Claims (16)

Method for generating energy in a total fuel cell system with cracking reactor and fuel cell, which comprises the following steps: a. Respectively at least one hydrocarbon in a cracking reactor with at least a first cracking chamber and at least one second cracking chamber in the absence of oxygen; b. Endothermic splitting of the Hydrocarbon in the cracking reactor with the exclusion of oxygen in carbon and a hydrogen-containing gas mixture and discharging the hydrogen-containing gas mixture; c. Interrupting the feed of the Hydrocarbon in the cracking reactor; d. Feeding from Steam or a combination of water vapor and air in the Cracking reactor; e. Gasifying the in crack step b. received Carbon with water vapor or a combination of water vapor and air to a carbon monoxide and hydrogen-containing gas mixture and further use of the resulting gas mixture in the overall fuel cell system; Feeding the in crack step b. obtained hydrogen-containing gas mixture into the fuel cell and oxidizing the hydrogen in the fuel cell with the production of heat and electrical energy, wherein at the beginning of the process in step a. the first chamber is filled with the hydrocarbon, in the so filled first chamber the endothermic cleavage according to step b. is carried out, the feeder of the hydrocarbon in the first chamber according to step c. is interrupted, according to step d. Water vapor or a combination of water vapor and air in the first chamber is supplied and the evaporation step e. is performed in the first chamber, in which at the beginning of step d. in the first chamber hydrocarbon is fed into the second chamber and in the second chamber, the process steps b. to e. be performed, in which, after evaporation of the carbon in step e. in the first chamber, Hydrocarbon is fed back to the first chamber and the cycle again carried out can be, and in each case in step b. formed hydrogen-containing gas mixture is discharged to the fuel cell. The method of claim 1, wherein preferably a Multi-chamber cracking reactor with at least three chambers is used, its chambers in at least two chamber groups as in claim 1 and in the chamber groups the steps a. to e. time offset become. Method according to one of the preceding claims, in the hydrogen-containing gas mixture supplied to the fuel cell before the feeder into the fuel cell of an intermediate treatment for lowering the carbon monoxide content is subjected. Method according to one of claims 1 to 3, wherein each in step e. formed, carbon monoxide and hydrogen-containing Gas mixture for producing the in the process, preferably in the process steps d. and e. required Heat energy used becomes. The method of claim 4, wherein the fuel cell supplied hydrogen-containing gas mixture before being fed into the fuel cell a methanation treatment for lowering the carbon monoxide content is subjected. Method according to one of claims 1 to 3, wherein each in step e. formed, carbon monoxide and hydrogen-containing Gas mixture in step b. discharged hydrogen-containing gas mixture is mixed. Method according to Claim 6, in which the said Fuel cell supplied hydrogen-containing gas mixture before being fed into the Brenstoffzelle a shift conversion treatment, and optionally a fine cleaning for lowering the carbon monoxide content is subjected. Method according to one of the preceding claims, wherein that in step b. dissipated hydrogen-containing gas mixture is supplied to a storage, from which the hydrogen-containing gas mixture is supplied to the fuel cell. Method according to one of the preceding claims, wherein in step a. the hydrocarbon used is the cracking reactor in the gaseous state, is preferably supplied in an inert gas atmosphere. Method according to one of the preceding claims, wherein in step a. the hydrocarbon used consists of lower alkane, Alkene and alkyne hydrocarbons, alcohols, aldehydes, ketones and organic acids with up to 30, preferably 20 carbon atoms or mixtures thereof selected becomes. Method according to one of the preceding claims, wherein in step b. the endothermic cleavage in the presence of a catalyst, preferably a metal catalyst is performed. The method of claim 11, wherein as a catalyst a Pd / gamma alumina catalyst is used. The method of claim 11, wherein as a catalyst a palladium, ruthenium, nickel, cobalt and / or iron solid phase catalyst is used. Method according to one of the preceding claims, wherein the anode exhaust gas for producing the in the process, preferably in the Process steps d. and e. required heat energy is used or the hydrocarbon fed to the cracking catalyst is mixed. Method according to one of the preceding claims, wherein one endothermic columns and the endothermic gasification in a temperature range of 500-1000 ° C, preferred from 700 to 1000 ° C and more preferably from 800 to 900 ° C. Apparatus for carrying out the method according to one of the preceding claims with a cracking reactor having at least one first cracking chamber and having at least one second cracking chamber (d; s), a burner (i) for supplying energy, at least one heat exchanger (e; f) to use the exhaust heat and to use the heat of the gas flows leaving the chamber, a methanation reactor g) for gas purification, a fuel cell p) and connecting lines with valves ( 1 ; 2 ; 3 ; 4 ; 5 ; 6 ; 7 ; 8th ; 9 ; 10 ) for the management and control of the gas and water flows.