DE102011014824A1 - Multi-fuel pyrolysis system for generating electrical power for e.g. mobile device, has pyrolysis reactor which pyrolyzes liquid, gaseous hydrocarbon mixtures or gas mixtures, and diesel fuel by anaerobic catalytic reaction - Google Patents

Abstract

A multi-fuel pyrolysis system (1) comprises pyrolysis reactor (21, 22) which pyrolyzes fuels chosen from oxygenated fuels e.g. alcohols, bioolen, biodiesel and pyrolyseolen, liquid, gaseous hydrocarbon mixtures or gas mixtures, preferably fuels e.g. diesel fuel by anaerobic catalytic reaction, and fuel cells(s) are connected downstream of the pyrolysis reactor. An independent claim is included for usage of multi-fuel pyrolysis system.

Description

The present invention relates to a pyrolysis system comprising a pyrolysis reactor in which a catalyst is arranged. Downstream of this pyrolysis reactor is a fuel cell, which can be supplied and operated with a hydrogen-containing gas mixture generated by the pyrolysis reactor. The pyrolysis reactor is capable of producing hydrogen-containing gas mixtures from a wide variety of fuels. In this case, the pyrolysis reactor is operated in two stages, with an anaerobic catalytic pyrolysis step, in which a hydrogen-containing gas is generated from the fuels used, alternating with an aerobic regeneration step of the catalyst. The pyrolysis reactor is thus preferably operated intermittently.

The object of the present invention is to specify a pyrolysis system with which hydrogen-containing gas mixtures can be produced in a simple and cost-effective manner, which can be converted into electrical energy and / or heat in a subsequent fuel cell. The system should be as cost-effective as possible, have a simple structure, furthermore, the generated gases should have a high hydrogen concentration. It is also an object of the present invention to provide a method for generating electrical energy and / or heat.

This object is achieved with the pyrolysis system according to claim 1 and with respect to the method for generating electrical energy and / or heat with the features of claim 9. Claim 15 describes possible uses. The respective dependent claims represent advantageous developments.

• a) mindestens einen Katalysator aufweisenden Pyrolysereaktor, der mittels anaerober katalytischer Pyrolyse von Brennstoffen, ausgewahlt aus der Gruppe bestehend aus flüssigen oder gasförmigen Kohlenwasserstoffen, sauerstoffhaltigen Brennstoffen (z. B. Alkoholen, Bioölen, Biodiesel, Pyrolyseölen), flüssigen oder gasförmigen Kohlenwasserstoffgemischen oder Gasgemischen, bevorzugt Kraftstoffen, insbesondere Dieselkraftstoff, die Herstellung eines Wasserstoff enthaltenden Gasgemisches und/oder eines Wasserstoff enthaltenden Gasgemisches mit Crackprodukten aus dem Brennstoff ermoglicht, wobei die anaerobe Katalyse intermittierend mit einer aeroben Regeneration des Katalysators durchgeführt wird, sowie
• b) dem Pyrolysereaktor nachgeschaltet mindestens eine Brennstoffzelle, die mit dem von dem mindestens einen Pyrolysereaktor erzeugten Wasserstoff enthaltenden Gasgemisch betrieben wird,

umfasst.According to the invention thus a multi-fuel pyrolysis system for generating electrical energy and / or heat for stationary and mobile applications is specified, the

• a) at least one catalyst-containing pyrolysis reactor obtained by anaerobic catalytic pyrolysis of fuels selected from the group consisting of liquid or gaseous hydrocarbons, oxygen-containing fuels (eg alcohols, bio-oils, biodiesel, pyrolysis oils), liquid or gaseous hydrocarbon mixtures or gas mixtures, preferably fuels, in particular diesel fuel, the production of a hydrogen-containing gas mixture and / or a hydrogen-containing gas mixture with cracking products from the fuel allows, wherein the anaerobic catalysis is carried out intermittently with an aerobic regeneration of the catalyst, and
• b) downstream of the pyrolysis reactor, at least one fuel cell which is operated with the gas mixture containing hydrogen produced by the at least one pyrolysis reactor,

includes.

The inventive pyrolysis system thus consists essentially of two juxtaposed components, namely a pyrolysis reactor and a fuel cell downstream of the pyrolysis reactor. The pyrolysis reactor in this case has a catalyst. In anaerobic operation of the pyrolysis reactor, a hydrogen-containing gas mixture or a gas mixture with cracking products from the fuel is produced by means of the catalyst from the fuels used. In this step, carbon-rich residues are deposited on the catalyst, which must be removed from the catalyst after a certain time. This is done by an aerobic regeneration step of the catalyst during which oxygen or an oxygen-containing gas mixture is brought into contact with the catalyst. In this case, a conversion of the carbon-rich deposits on the catalyst to carbon monoxide or water-gas-containing gas mixtures. By such operation of the pyrolysis reactor, a complete utilization of the fuel used is possible.

In a preferred embodiment, the pyrolysis reactor comprises a housing in the interior of which the catalyst is arranged, wherein the catalyst comprises a support, which is at least partially coated with an alloy containing iron and nickel.

It is likewise advantageous if the pyrolysis system comprises at least one combustion device and / or device which is produced by catalytic oxidation of fuels, anode off-gas from the fuel cell and / or hydrogen-containing gas mixtures from the pyrolysis reactor and / or from CO generated by aerobic regeneration of the catalyst -containing gas generates heat. The heat generated in this case can be used for example to support the evaporation of fuels, but it is also possible to use the heat generated externally as useful heat. For the first case, it is particularly preferred if the combustion device or the device passing through catalytic oxidation of fuels produces heat, in thermal interaction with the at least one pyrolysis reactor. The combustion device may be upstream or downstream of the pyrolysis reactor, but it is also possible to integrate the combustion device into the pyrolysis reactor so that a structural unit is provided between the pyrolysis reactor and the combustion device.

In a further advantageous embodiment of the at least one combustion device and / or device which generates heat by catalytic oxidation, a heat exchanger and / or heat storage connected downstream of the heat z. B. can be transferred to a heating system. This embodiment is particularly suitable when the heat is to be discharged from the pyrolysis system into an external system, such as a heating system. However, the resulting heat can also z. T. or completely used to vaporize liquid fuels or preheat fuels before feeding into the pyrolysis.

The efficiency of the pyrolysis system can be further increased if a membrane for separating hydrocarbon gases and hydrogen gas is arranged between the at least one pyrolysis reactor and the at least one downstream fuel cell. The hydrocarbon gases can thus be separated from the gases leaving the pyrolysis system and fed, for example, again to the pyrolysis reactor. Thus, a fuel cell is almost exclusively supplied with (almost) pure hydrogen, so that on the one hand the highest possible efficiency of the fuel cell is ensured and, on the other hand, no waste products, such as, for example, unusable hydrocarbon gases, are lost.

Additionally or alternatively, it is also preferred if the anode compartment of the fuel cell has a gas return for the anode offgas in the pyrolysis reactor. Since also in the anode offgas u. U. still hydrocarbons or hydrogen gas may be present, it is preferable to recirculate this anode exhaust gas into the pyrolysis reactor and / or the combustion device, so that optionally still present usable fuels or fuel fragments can be subjected to a pyrolysis or thermally recovered in the combustion device ,

A preferred embodiment of the present invention provides that the gas recirculation of the anode off-gas takes place actively. In this embodiment, the gas recirculation has a pump, with which the gas can be sucked from the anode compartment of the fuel cell and fed to the pyrolysis system. For this purpose, any known from the prior art gas pump, which can be actively operated for example. Very particularly preferred, however, are jet pumps based on the Venturi principle. These pumps can be operated passively, so that no external energy input for operating these pumps is necessary. For example, the pump may be operated by the flow of fuel supplied to the reactor. The negative pressure created by the flow of fuel in the venturi of the jet pump can be used to draw the anode off-gas from the anode compartment of the fuel cell and feed it to the pyrolysis reactor along with the flow of fuel fed into the pyrolysis reactor. It is particularly preferred if gaseous fuels are introduced into the reactor, for example propane. In this case, for example, the pressure of the propane in the propane reservoir, for example, a propane cylinder and the mass ratio between anode exhaust gas and the propane stream, is sufficient to reliably operate a jet pump. This mass ratio is not given in alternative methods for hydrogen production.

Preferred embodiments of the catalyst provide that the molar ratio between iron and nickel is between 3: 1 and 1: 5, preferably between 1: 2 and 1: 4, in particular between 1: 2.8 and 1: 3.2.

Further advantageous here is when the total content of nickel and iron, based on the carrier between 0.5 and 15 wt .-%, preferably between 1 and 10 wt .-%, particularly preferably between 2.5 and 7.5 wt. -% is.

In particular, the material of the carrier is selected from the group consisting of ceramic materials, in particular silicon dioxide, silicon carbide, aluminum oxide, silicates, in particular aluminosilicates, zeolites, cordierite and / or metals.

It is likewise advantageous if the catalyst is present in the form of a powder, a granulate, a honeycomb, a foam, a mesh or a sheet.

Preferred membranes which can be arranged between pyrolysis reactor and fuel cell are formed from materials which comprise materials selected from the group consisting of ceramic materials, metals and metal alloys, in particular PdAg and / or PdCu alloys.

According to the invention, various types of fuel cell can be preferably used. In particular, a high-temperature polyelectrolyte membrane (HT-PEM) fuel cell, a low-temperature polymer electrolyte membrane (NT-PEM) fuel cell, a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC) or an alkaline Fuel cell (alkaline fuel cell, AFC) in question.

According to the invention, a method for generating electrical energy and / or heat with a pyrolysis system described above is also specified. In the method according to the invention, by means of the at least one pyrolysis reactor by anaerobic catalytic pyrolysis of fuels, a hydrogen-containing gas mixture and / or a hydrogen-containing gas mixture is produced with cracking products, the gas mixture is introduced into the at least one fuel cell and converted into electrical energy and / or heat.

A preferred embodiment of the method provides that the pyrolysis system has a pyrolysis reactor, which is operated intermittently in anaerobic catalytic pyrolysis and aerobic regeneration, wherein the gas mixture formed during the anaerobic catalytic pyrolysis hydrogen-containing gas mixture and / or hydrogen containing cracking products in the at least one Fuel cell is abandoned and converted into electrical energy and / or heat.

By the operation described in the foregoing, additional material costs can be saved. This allows a very cost-effective system can be realized.

In a likewise preferred alternative embodiment, the pyrolysis system has at least two pyrolysis reactors which are operated in alternating operation so as to ensure continuous production of hydrogen-containing gas mixtures and / or hydrogen-containing gas mixtures with cracked products which are continuously introduced into the at least one fuel cell and introduced into electrical energy and / or heat are converted.

Furthermore, it is advantageous if the pyrolysis system has a membrane arranged between the at least one pyrolysis reactor and the at least one fuel cell for separating hydrocarbons and hydrogen gas, wherein the hydrogen separated by the membrane is fed into the at least one fuel cell and the hydrocarbons are introduced into the at least one Pyrolysis reactor are recycled. By such a measure, the efficiency can be significantly increased.

It is likewise preferred if the anode offgas of the anode of the at least one fuel cell is returned to the at least one pyrolysis reactor. This also makes it possible to significantly increase the efficiency.

In the event that the pyrolysis system has a combustion device and / or at least one catalytic oxidation device, it is preferred if it generates heat at least temporarily during the duration of the anaerobic catalytic pyrolysis operation of the at least one pyrolysis reactor, the heat being transferred to the surface by thermal interaction at least one pyrolysis reactor is transmitted.

• – Kraft-Warme-Kopplung
• – Kraft-Warme-Kalte-Kopplung
• – Herstellung synthetischer Kraftstoffe
• – Abgasnachbehandlung
• – Mobile Vorrichtung zur Erzeugung von elektrischer Energie (bspw. als Ladegerät fur Batterien im Camping- und Freizeitbereich, in Automobilen und Yachten, etc.)
• – Bordstromversorgung von Kraftfahrzeugen (APU's)
• – Unterbrechungsfreie Stromversorgung (USV)
• – Notstromversorgung in Hutten, Hausern, Kliniken, etc.

According to the invention, uses of the pyrolysis system according to the invention are also indicated. These are:

• - power-heat-coupling
• - Power-warm-cold-coupling
• - manufacture of synthetic fuels
• - Exhaust gas aftertreatment
• - Mobile device for generating electrical energy (eg. As a charger for batteries in the camping and leisure, in automobiles and yachts, etc.)
• - On-board power supply of motor vehicles (APU's)
• - Uninterruptible power supply (UPS)
• - Emergency power supply in hatches, houses, clinics, etc.

The present invention will be explained in more detail with reference to the following embodiments, without limiting the present invention to the particular parameters and embodiments shown there.

In pyrolysis hydrocarbons are thermochemically cleaved at temperatures between 500 and 1000 ° C. The decomposition produces solid carbon and a product gas which, depending on the fuel and the reaction condition, contains a high concentration of hydrogen. The decomposition takes place without the addition of oxygen or other reactants, but only under the action of heat. The decomposition of the resulting gases is highly dependent on pressure and temperature. 1 shows the thermodynamic equilibrium on the example of propane at different temperatures. At ambient pressure and temperatures> 900 ° C, the product gas may contain up to 98% hydrogen. At higher operating pressure (10 bar), the hydrogen concentration drops to <90%. Regardless of the operating parameters and the medium used, the product gas contains methane. The residual methane content depends on the operating pressure and the operating temperature.

2 shows schematically the operation of a pyrolysis system according to the invention 1 , Shown are two pyrolysis reactors 21 and 22 , which can be supplied with air or propane in the case shown. In 2 (1) becomes the pyrolysis reactor 21 supplied with propane and pyrolyzed this case to hydrogen gas-containing pyrolysis gas. During the pyrolysis reactor 21 pyrolyzed, simultaneously becomes the pyrolysis reactor 22 regenerated by adding an oxygen-containing gas, in this case air, to the pyrolysis reactor 22 is abandoned. This produces a CO and / or CO ₂ -containing exhaust gas. Not shown is the pyrolysis system downstream fuel cell.

In 2 (2) becomes the mode of operation of the pyrolysis reactors 21 . 22 compared to in 2 (1) shown in reverse, ie the pyrolysis reactor 21 is supplied with air while in the pyrolysis reactor 22 Propane is given up. Both pyrolysis reactors 21 and 22 but are identical. By alternation of the illustrated operation thus intermittently a pyrolysis reactor 21 . 22 operated in a pyrolysis step (anaerobic step) and an aerobic regeneration step.

During the above-mentioned individual process steps, ie pyrolysis or regeneration, essentially the reactions explained in the following proceed:
For example, during pyrolysis, propane is catalytically decomposed to hydrogen, methane, and carbon. The produced carbon settles on the catalyst and has to be burned off with air in a second step. For a continuous, hydrogen-rich gas flow therefore z. B. two reactors 21 . 22 which alternately pyrolyze and regenerate (as in 2 shown). However, more than two reactors according to the in 2 shown principle operated in parallel.

The catalyst is present as a metal oxide after regeneration and is not active in this state. The catalyst is reduced at the beginning of the pyrolysis.

3 shows the qualitative time course of a pyrolysis cycle with propane. At the beginning of the pyrolysis, the catalyst is reduced by the propane and then by the hydrogen and carbon monoxide formed. The stored oxygen during the regeneration is discharged from the reactor in the form of CO and CO ₂ . When the catalyst is reduced, the CO and CO ₂ concentrations decrease and the hydrogen concentration continues to increase.

At the beginning of the pyrolysis, the catalyst is reduced (see CO and CO ₂ peak). The drop in CO and CO ₂ signals the end of the reduction.

If the product gas during pyrolysis in fuel cells (for example, in NT-PEM (low-temperature polymer electrolyte membrane) or HT-PEM (high-temperature polymer electrolyte membrane) fuel cells) should be used, the CO peak to Beginning of the pyrolysis be buffered. In addition, a high hydrogen concentration can also be achieved at the switching point (see 4 ). The regeneration cycle must always be shorter than the pyrolysis cycle. The reactor must then be regenerated with a high air flow. The burning off of the carbon is exothermic, as a result of which the temperatures in the reactor rise sharply. The constantly changing operating conditions and the high temperatures (> 950 ° C) occurring during regeneration pose a major challenge for the catalytic converter.

There is currently no commercially available catalyst suitable for a pyrolysis system. However, the catalyst used in the invention is thermally stable over time. In the development of the catalyst was dispensed expensive precious metals, as an active component was therefore a Nickel alloy applied, which was applied to a silica carrier. The composition of the active component, the preparation method and the carrier have a great influence on the gas composition and the stability of the catalyst.

The following describes by way of example the preparation and the composition of the catalyst which can be operated with a wide range of starting materials.

• • Herstellung einer Losung aus:
• – 60,88 g Ni(NO₃)₂ × 6H₂O
• – 28,15 g Fe(NO₃)₃ × 9H₂O
• – 88 g Zitronensaure
• – aufgefüllt mit 53,6 g H₂O
• • Imprägnierung des SiO₂-Trägers mit der Losung
• • Trocknung
• – 2 Tage bei 25°C
• – 1 Tag bei 88°C
• – 10 Stunden bei 100–120°C
• • Kalzinierung
• – 4 Stunden bei 600°C

As a carrier of the catalyst SiO _{2 is used} with a low surface area (carrier of Alfa Aesar, low surface). The active components of the catalyst are Fe and Ni. The molar ratio between Fe and Ni is 1/3. The catalyst was prepared as follows (data refer to the coating of 500 g of SiO ₂ ).

• • Production of a solution from:
• 60.88 g of Ni (NO ₃ ) ₂ .6H ₂ O
• 28.15 g of Fe (NO ₃ ) ₃ .9H ₂ O
• - 88 g of citric acid
• - filled with 53.6 g H ₂ O.
• • Impregnation of the SiO ₂ carrier with the solution
• • drying
• - 2 days at 25 ° C
• - 1 day at 88 ° C
• - 10 hours at 100-120 ° C
• • Calcination
• - 4 hours at 600 ° C

4 shows the gas composition during pyrolysis in a two-reactor system, such as. In 2 is shown. The two pyrolysis reactors pyrolyze and regenerate fully automatically alternately. The hydrogen concentration is always> 80% by volume and the carbon monoxide concentration always <1% by volume. The product gas can be converted into electricity directly in an HT-PEM fuel cell without gas purification.

The pyrolysis temperature is 750 ° C in both reactors. The pyrolysis time is 10 minutes each. The hydrogen concentration (right ordinate) is also at the switching point large 80 vol .-%. The carbon monoxide concentration (left ordinate) is always less than 0.6% by volume.

The novel pyrolysis system has already been successfully tested with many fuels and fuels. The tests have shown that the developed pyrolysis system is "multi-fuel suitable". As a result, many application and application options are conceivable (see, for example, Scheme in 5 ). The possible applications are described in detail below.

With the novel pyrolysis system, it is possible for the first time to convert various fuels or fuels in a system into a hydrogen-rich product gas or a synthesis gas. The composition of the product gas is determined by the fuel and fuel used. Gaseous and liquid fuels that contain no oxygen compounds can be converted into a hydrogen-rich product gas in the pyrolysis system. Pyrolysis offers an alternative to conventional reforming processes in the stationary and mobile sectors (Autothermal reforming (ATR), steam reforming (SRF), partial oxidation (CP _ox )).

• • kostengünstiger Katalysator (keine Edelmetalle),
• • einfacher Aufbau,
• • Fur die Pyrolyse wird kein Wasser benötigt. Es entfallen Komponenten, wie Dl-Wasserpatrone, Wasserpumpe, etc.
• • kein Biofilm in Rohrleitungen nach längeren Stillstandzeiten,
• • hohe Wasserstoffkonzentration (Gaszusammensetzung basierend auf Experimenten mit Propan bei 1,2 bar und 700°C): H₂ > 80 Vol.-%, CO < 1 Vol.-%, Rest Methan),
• • keine Gasreinigung erforderlich; das Produktgas kann direkt in eine Hochtemperatur-Brennstoffzelle geleitet und verstromt werden;
• • Das Pyrolysesystem kann durch eine Gasfeinreinigung erweitert werden, dadurch kann das Produktgas in eine Niedertemperaturbrennstoffzelle geleitet werden. Geeignete Gasfeinreinigung: Methanisierung.
• • Die Gaszusammensetzung der Pyrolyse bietet Vorteile bei der Gasfeinreinigung mittels Methanisierung. Da das Pyrolysegas nur geringe Mengen an CO₂ enthält (< 0,5 Vol.-%), treten Folgereaktionen (CO₂-Methanisierung) nur im sehr geringen Umfang auf, dadurch kann auf eine aufwandige Temperaturregelung verzichtet werden (zum Vergleich: CO₂-Gehalt bei der Reformierung > 10 Vol.-%).
• • Bei der Verbrennung des Methans im Brennstoffzellenabgas (CH₄-Konzentration bis 20 Vol.-%, ist in der Brennstoffzelle inert und kann deshalb nicht direkt in Strom und Wärme umgesetzt werden) entsteht sehr viel Warme. Die Pyrolyse ist deshalb sehr gut für stationäre KWK-Anwendungen einsetzbar.
• • Die überschussige Warme kann zudem zur Nutzung von stationaren KWKK(Kraft-Warme-Kalte-Kopplung)-Anwendungen eingesetzt werden.

The advantages of the pyrolysis system according to the invention are in particular

• • inexpensive catalyst (not precious metals),
• • easy construction,
• • No water is needed for the pyrolysis. It accounts for components such as DI water cartridge, water pump, etc.
• • no biofilm in pipelines after prolonged downtime,
• High hydrogen concentration (gas composition based on experiments with propane at 1.2 bar and 700 ° C.): H ₂ > 80% by volume, CO <1% by volume, balance methane),
• • no gas cleaning required; the product gas can be passed directly into a high-temperature fuel cell and converted into electricity;
• • The pyrolysis system can be extended by a gas fine cleaning, thereby the product gas can be led into a low-temperature fuel cell. Suitable gas fine cleaning: methanation.
• • The gas composition of pyrolysis offers advantages in gas purification by means of methanation. Since the pyrolysis contains only small amounts of CO ₂ (<0.5 vol .-%), follow-up reactions (CO ₂ methanation) occur only to a very small extent, this can be dispensed with an expensive temperature control (for comparison: CO ₂ Content during reforming> 10% by volume).
• • In the combustion of methane in the fuel cell exhaust gas (CH ₄ concentration to 20 vol .-%, is inert in the fuel cell and therefore can not be directly converted into electricity and heat) is very much warm. Pyrolysis is therefore very suitable for stationary CHP applications.
• • The excess heat can also be used for the use of stationary CHP (power-heat-cold-coupling) applications.

example 1

Methane pyrolysis (2 reactors) with high-temperature PEM fuel cell for stationary CHP (combined heat and power) application

6 shows a methane pyrolysis system 1 with high-temperature PEM fuel cell 3 for the production of electricity and heat. The pyrolysis system 1 was designed for 6 kW _th (thermal energy) and 1.3 kW _el (electrical energy). The pyrolysis system 1 includes two reactors 21 . 22 , which alternately pyrolyze and regenerate, as well as a fuel cell 3 , The intermittent operation of the two reactors 21 . 22 is in 6 shown left and right, with the different modes of operation of the two reactors 21 . 22 are reflected. The heat can z. B. be buffered in a hot storage. The pyrolysis system 1 also has a combustion device 4 on. In addition, the anode compartment has 31 the fuel cell 3 via a gas recirculation 32 , via the anode offgas into the combustion device 4 can be returned. However, it is also possible for the anode offgas to be in the pyrolysis reactor 21 or 22 jerk out. How out 6 can be seen, the burner, both the anode offgas from the anode gas recycle 32 , as well as CO-rich gas after regeneration, for example, from the reactor 22 , fed and burned. The resulting heat is coupled into the system, such as the heat storage 5 (Hot water tank) supplied.

Advantages:

• • simple construction, fewer components are needed compared to conventional reforming; This can save costs.
• • lower control effort (compared to the reforming process) due to the simple power supply;
• • Use of standard gas burners possible. The burner does not have to be designed for several operating conditions (1st stationary operation: low gas, high inert content, 2nd start: operation with pure fuel), as in the case of reforming.

Example 2

Methane pyrolysis (1 reactor) with high-temperature PEM fuel cell for stationary CHP (combined heat and power) application

This in 7 illustrated pyrolysis system 1 can be designed to continuously generate heat and intermittently generate electricity. For this purpose, the pyrolysis system can be applied to a reactor 1 be reduced. The overall system 1 can be significantly simplified compared to operation with two reactors. It can be very well integrated into existing heating systems where heat is primarily generated. The additional electricity can be fed into the power grid (electricity generating heating). The pyrolysis system 1 also has a combustion device 4 on. In addition, the anode compartment has 31 the fuel cell 3 via a gas recirculation 32 , via the anode offgas into the combustion device 4 can be returned. However, it is also possible for the anode offgas to be in the pyrolysis reactor 21 or 22 recirculate.

Advantages:

• • The system can be compared to the one in 6 shown system again greatly simplified; fewer components are required (heat exchanger, valves, sensors, etc.).
• • easy integration into existing heating systems;
• • no water and no gas cleaning necessary;
• • The system can be easily scaled up and down.

The pyrolysis system generates a lot of heat due to the relatively high methane content (about 20% by volume). By means of the modification according to the invention, higher electrical efficiencies can be achieved.

The efficiency of a propane pyrolysis system 1 can be improved by the downstream of a membrane reactor (see 8th ). A large part of the hydrogen (permeate) is from a membrane 6 separated and to the fuel cell 3 directed. The methane and the residual hydrogen (retentate) are returned to the pyrolysis reactor 21 directed. This requires the system 1 at the same hydrogen power (fuel cell inlet 3 ) less propane, the efficiency can be significantly increased.

In addition, the gas recirculation has a jet pump 7 which may be, for example, a Venturi nozzle. The jet pump can also be operated with the pyrolysis reactor supplied propane gas (not shown), so that the retentate can be reliably fed to the pyrolysis reactor for re-pyrolysis.

Advantages:

• • The electrical efficiency can be significantly increased compared to the "classic" pyrolysis with 2 reactors:
• - Increased efficiency (el.) By approx. 7-8%
• - Efficiency comparable to ATR ⁶
• • The fuel cell is powered by pure hydrogen. The use of nearly all fuel cell types is possible.
• • A jet pump can be used to save compressor performance. In the event that z. B. LPG is used as a fuel, the bottle pressure is sufficient to compress the recirculated volume flow from the membrane to the operating pressure and supply them to the pyrolysis reactor.

The return of the residual methane in the pyrolysis process, the electrical efficiency can be significantly increased. Another way to simplify the system is to return the anode off-gas. This possibility is as an alternative to 8th in 9 shown.

Advantage:

It can be dispensed with an expensive membrane reactor.

• • Das System muss vor allem kostengunstig sein.
• • einfaches System, keine aufwändigen Regelstrategien etc. -> passive Kuhlung;
• • robust;
• • außentauglich, unempfindlich gegenüber Umgebungseinflüssen.

The pyrolysis can also be used for mobile applications, such as a charger in the leisure and camping (see 10 ). The system should therefore be designed according to the following criteria:

• • The system must be cost-effective.
• • simple system, no elaborate control strategies etc. -> passive cooling;
• • robust;
• • suitable for outdoor use, insensitive to environmental influences.

10 shows a flow diagram of a propane-pyrolysis system 1 for mobile applications. The pyrolysis reactor 21 is designed so that hydrogen and electricity can be produced over a defined time. The power can then serve, for example, for charging a battery or directly as a power supply for various consumers.

The pyrolysis system does not involve complex control strategies, the propane flow is set to a fixed value. The maximum pyrolysis time is set over the catalyst volume.

11 shows by way of example the gas composition during a propane pyrolysis with an in 10 illustrated pyrolysis system. The pyrolysis could be operated stably for two hours, the Hydrogen concentration drops to 80% by volume. The methane concentration increases to 20 vol .-%. The CO concentration decreases after the reduction (onset of pyrolysis) to 100 ppm.

The product gas can be passed into an HT-PEM fuel cell without gas purification and converted into electricity. By incorporating a methanation catalyst, the CO concentration can be reduced to <20 ppmv and then even passed into an NT-PEM fuel cell and converted into electricity. The methanation catalyst can be easily integrated into a heat exchanger. Since the product gas contains only a small amount of CO ₂ , can be dispensed with a complex temperature of the methanation. The inlet temperature does not have to be precisely adjusted, as in the reforming process, since the catalyst does not have to be very selective in this case.

For the pyrolysis system can be heated by a standard, simple burner. For this purpose, a laboratory burner is sufficient, which sucks the combustion air itself. In steady state operation (pyrolysis), the anode off gas of the fuel cell is directed into an oxidation catalyst which provides the heat of reaction for the pyrolysis reactor. After completion of the pyrolysis, the reactor is regenerated via an air stream. The regeneration gas may still contain CO, the exhaust gas is passed after the regeneration in the oxidation catalyst. There, the CO is oxidized with the supplied air to CO ₂ . In addition, the pyrolysis reactor is kept at temperature, after the regeneration can be restarted directly with the pyrolysis.

Advantages:

• • easy construction;
• • no elaborate control strategies, passive cooling, no heat integration necessary (for example, evaporation of water, etc.), fixed propane flow;
• • all catalysts, pyrolysis, oxidation catalyst and methanation do not contain precious metals -> cost effective;
• • Process components can be kept to a minimum compared to reforming.
• • It has been shown that material costs can be reduced by up to 60% compared to an ATR system.

12 shows a sketch of the pyrolysis reactor 2 including start burner 4 , Oxidation catalyst 7 for providing the endothermic reaction heat and optionally the methanation 8th to reduce the CO to <20 ppm.

The pyrolysis reactor 21 has an integrated start burner 4 up and concentric around this burner 4 built up. Directly around the burner chamber, the pyrolysis closes 7 at; further outside is an oxidation catalyst 7a educated.

The pyrolysis system can be very simple, the individual segments consist of concentric tubes. The methanation 8th can be integrated into the heat exchanger, such as coiled tubing. Also conceivable is a planar system, which is hochskalierbar in stack construction.

Biogas, oxygen-containing fuels and fuel gases and product gases after fuel evaporators, which provide the heat for the evaporation process, for example by means of partial oxidation, can be converted in the pyrolysis reactor to a synthesis gas.

The pyrolysis of biogas and the pyrolysis of pre-evaporated fuels and fuels is readily possible. In the pyrolysis reactor, these feedstocks are converted to a synthesis gas.

The experiments were carried out with vaporized diesel fuel and with synthetic biogas mixtures (variation proportion CH ₄ / CO ₂ ). The methane content in the biogas is between 45 and 70 vol .-% and the proportion of carbon dioxide between 25 and 55 vol .-%. The gas composition depends on various parameters, such as substrate composition and operation of the digester.

In 13 the temperature profile and the gas composition during the pyrolysis and subsequent regeneration of a synthetic biogas mixture (75 vol .-% CH ₄ and 25 vol .-% CO ₂ ) can be seen. The hydrogen concentration increases during pyrolysis to> 60 vol .-%. The methane content drops to 15 vol .-% and the carbon monoxide content rises to about 20 vol .-%. The carbon dioxide contained in the biogas reacts with the attached carbon to carbon monoxide (Boudouard equilibrium). As a result, longer pyrolysis times can be achieved. Compared to propane pyrolysis, the pyrolysis time could be doubled with biogas at a constant volume flow. As in 13 can be seen, the regeneration time is shortened by the Boudouard reaction.

After pyrolysis, the product gas can be passed directly into a solid oxide fuel cell (SOFC), Molten Carbonate Fuel Cell (MCFC) and converted into electricity. The pyrolysis reactor can also be used as a pre-reformer for use in MCFC's or SOFC's. For use in HT-PEM or NT-PEM fuel cells, the pyrolysis reactor must be followed by a gas cleaning or gas fine cleaning.

Advantages:

• High hydrogen concentration;
• • inexpensive catalyst (not precious metals);
• • easy construction;
• • No water is needed for the pyrolysis. It accounts for components such as DI water cartridge, water pump, etc .;
• • no biofilm in piping after prolonged downtime;
• • The product gas can be fed directly into a high-temperature fuel cell (SOFC, MCFC) and converted into electricity.

Lignocellulose-containing biomass can be converted into a synthesis gas in a gasifier. The gas composition is highly dependent on the type of gasifier.

• 1) Daten eines Güssing-FICFB-Vergasers
• 2) Daten eines Bioflow-Vergasers
• 3) mehrere Daten von CHOREN und FZ Karlsruhe

Table 1 shows the gas composition of different gasification processes. Table 1 Low Temperature Atm. Steam Blown Fluidized Bed Gasifier Low Temperature Press Oxygen Blown Fluidized Bed Gasifier High Temperature Press Oxygen Blown Entrained Flow Gasifier H ₂ % 35-45 23-28 29-35 CO % 22-25 16-19 35-44 CO ₂ % 20-23 33-38 17-22 CH ₄ % 9-11 10-13 <1 N ₂ % <1 <5 <5

• 1) Data from a Güssing FICFB carburetor
• 2) Bioflow carburettor data
• 3) several data from CHOREN and FZ Karlsruhe

The wood gas after the biomass gasifier contains, depending on the gasification process, up to 13 vol .-% methane. The methane can be converted to H ₂ and C in a subsequent pyrolysis reactor. The CO ₂ contained in the wood gas reacts with the attached C to CO (Boudouard equilibrium). As a result, the pyrolysis time can be significantly extended.

The gas composition is strongly influenced by the temperature. In 14 is the thermodynamic equilibrium shown in the pyrolysis of wood gas as a function of temperature. The simulation was carried out at 1 bar, the wood gas at the inlet of the pyrolysis reactor has the composition: H ₂ : 45 vol.%, CO: 25 vol.%, CO ₂ : 20 vol.%, CH ₄ : 10 vol. -% and corresponds to the gas composition according to the biomass gasifier from Güssing (see Table 1).

The CH ₄ and CO ₂ concentrations decrease with increasing temperature. At the same time, the H ₂ and CO concentrations increase. With a subsequent pyrolysis reactor, the H ₂ and CO concentrations can be increased.

The synthesis gas can be used, among other things, for the production of synthetic fuels. Especially the generation of liquid fuels offers advantages due to the good storability. For example, the synthesis gas can be converted to liquid fuels via the Fischer-Tropsch synthesis. Other possibilities include methanol synthesis or DME synthesis (see 15 ).

Through the pyrolysis reactor, the H ₂ - and CO concentration can be increased and thus the yield of liquid fuels. In addition, the ratio of CO and H ₂ on the reaction conditions in the pyrolysis reactor, temperature and pressure, can be changed. In addition, the wood gas can be mixed with various fuels, such as propane, ethanol, biogas, thereby the H ₂ / CO ratio can be adapted to the required fuel production.

Claims (15)

Multi-fuel pyrolysis system ( 1 ) for the production of electrical energy and / or heat for stationary and mobile applications, comprising a) at least one catalyst-containing pyrolysis reactor ( 21 . 22 ) obtained by means of anaerobic catalytic pyrolysis of fuels selected from the group consisting of liquid or gaseous hydrocarbons, oxygen-containing fuels (eg alcohols, biools, biodiesel, pyrolysis oils), liquid or gaseous hydrocarbon mixtures or gas mixtures, preferably fuels, in particular diesel fuel, the production of a hydrogen-containing gas mixture and / or a hydrogen-containing gas mixture with cracked products from the fuel, wherein the anaerobic catalysis is performed intermittently with an aerobic regeneration of the catalyst, and b) downstream of the pyrolysis reactor at least one fuel cell ( 3 ) operated by the gas mixture produced by the at least one pyrolysis reactor. Pyrolysis system ( 1 ) according to the preceding claim, characterized in that a) the at least one pyrolysis reactor ( 21 . 22 ) comprises a housing inside which the catalyst is arranged, the catalyst comprising a support which is at least partially coated with an alloy containing iron and nickel, b) the pyrolysis system ( 1 ) at least one combustion device ( 4 ) and / or a device which is obtained by catalytic oxidation of fuels, anode fuel gas from the fuel cell ( 3 ) and / or hydrogen-containing gas mixtures from the pyrolysis reactor ( 21 . 22 ) and / or generates heat from the CO-containing gas generated by aerobic regeneration of the catalyst, c) the at least one combustion device ( 4 ) and / or a device that generates heat by catalytic oxidation, a heat transfer medium and / or heat storage ( 5 ), which can transfer the heat into a heating system, d) between the at least one pyrolysis reactor ( 21 . 22 ) and the at least one downstream fuel cell ( 3 ) a membrane ( 6 ) is arranged for the separation of hydrocarbon gases and hydrogen gas and has a gas recirculation of the hydrocarbon gas in the pyrolysis reactor, e) the anode space ( 31 ) of the fuel cell ( 3 ) via a gas recirculation ( 32 ) for the anode off-gas into the pyrolysis reactor ( 21 . 22 ) and f) the gas pressure guide a pump ( 7 ), in particular a jet pump, for the return of the anode off-gas and / or hydrocarbon gas. Pyrolysis system ( 1 ) according to the preceding claim, characterized in that the catalyst has a molar ratio between iron and nickel between 3: 1 and 1: 5, preferably between 1: 2 and 1: 4, in particular between 1: 2.8 and 1: 3.2 having. Pyrolysis system ( 1 ) according to one of the two preceding claims, characterized in that the total content of nickel and iron, based on the carrier between 0.5 and 15 wt .-%, preferably between 1 and 10 wt .-%, particularly preferably between 2.5 and 7.5% by weight. Pyrolysis system ( 1 ) according to one of claims 2 to 4, characterized in that the material of the carrier is selected from the group consisting of ceramic materials, in particular silicon dioxide, silicon carbide, alumina, silicates, in particular aluminosilicates, zeolites, cordierite and / or metals. Pyrolysis system ( 1 ) according to one of claims 2 to 5, characterized in that the catalyst is in the form of a powder, a granulate, a honeycomb, a foam, a network or a sheet. Pyrolysis system ( 1 ) according to one of claims 2 to 6, characterized in that the membrane ( 6 ) is selected from the group consisting of ceramic materials, metals and metal alloys, in particular PdAg and / or PdCu alloys. Pyrolysis system ( 1 ) according to one of the preceding claims, characterized in that the fuel cell ( 3 ) a high-temperature polyelectrolyte membrane (HT-PEM) fuel cell, low-temperature polymer electrolyte membrane (NT-PEM) fuel cell, a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC) or an alkaline fuel cell (alkaline fuel cell, AFC). Method for generating electrical energy and / or heat with a pyrolysis system having at least one pyrolysis reactor ( 1 ) according to one of the preceding claims, in which by means of the at least one pyrolysis reactor ( 21 . 22 ) generates by anaerobic catalytic pyrolysis of fuels, a hydrogen-containing gas mixture and / or a hydrogen-containing gas mixture with cracking products, the gas mixture in the at least one fuel cell ( 3 ) and converted into electrical energy and / or heat. Method according to the preceding claim, characterized in that the pyrolysis system ( 1 ) a pyrolysis reactor ( 21 ), which is operated intermittently in anaerobic catalytic pyrolysis and aerobic regeneration, wherein the gas mixture formed during the anaerobic catalytic pyrolysis hydrogen-containing gas mixture and / or hydrogen containing cracking products in the at least one fuel cell ( 3 ) and converted into electrical energy and / or heat. Process according to claim 9, characterized in that the pyrolysis system ( 1 ) at least two pyrolysis reactors ( 21 . 22 ), which are operated in alternating operation, so that a continuous generation of hydrogen-containing gas mixtures and / or hydrogen-containing gas mixtures is guaranteed with cracking products, which continuously into the at least one fuel cell ( 3 ) and converted into electrical energy and / or heat. Method according to one of claims 9 to 11, characterized in that the pyrolysis system ( 1 ) via a between the at least one pyrolysis reactor ( 21 . 22 ) and the at least one fuel cell ( 3 ) arranged membrane ( 6 ) for the separation of hydrocarbons and hydrogen gas, which passes through the membrane ( 6 ) separated hydrogen into the at least one fuel cell ( 3 ) and the hydrocarbons in the at least one pyrolysis reactor ( 21 . 22 ) and / or the combustion device ( 4 ) and thereby the efficiency can be significantly increased. Method according to one of claims 9 to 12, characterized in that the anode offgas of the anode of the at least one fuel cell ( 3 ) into the at least one pyrolysis reactor ( 21 . 22 ) and / or the combustion device ( 4 ) is recycled and thereby the efficiency can be significantly increased. Method according to one of claims 9 to 13, characterized in that the pyrolysis system ( 1 ) via at least one combustion device ( 4 ) and / or at least one catalytic oxidation device which, at least temporarily, at least during the duration of the anaerobic catalytic pyrolysis operation of the at least one pyrolysis reactor ( 21 . 22 ) Produces heat, the heat being generated by thermal interaction with the at least one pyrolysis reactor ( 21 . 22 ) is transmitted. Use of a pyrolysis system according to any one of claims 1 to 8 as a module for - power-heat-coupling - Power-heat-cold-coupling - manufacture of synthetic fuels - Exhaust gas aftertreatment - Mobile device for generating electrical energy (eg. As a charger for batteries in the camping and leisure, in automobiles and yachts, etc.) - On-board power supply of motor vehicles (APU's) - Uninterruptible power supply (UPS) - Emergency power supply in huts, houses, clinics, etc.

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