Method for producing hydrogen-containing gas

Abstract

The present invention provides a method for starting up a reactor to produce a hydrogen-containing gas and thereafter maintaining the reactor at an operating temperature, wherein a fuel cell is fluidly connected to the reactor downstream of the reactor and to a catalytic afterburner upstream of the catalytic afterburner, the method comprising the steps of storing the hydrogen-containing gas in a container, opening the container and releasing the hydrogen-containing gas from the container, reacting the released hydrogen-containing gas mixed with an oxygen-containing gas, preferably air, in the catalytic afterburner to produce heat and heated exhaust gas, and introducing the heat and / or heated exhaust gas into the reactor to heat the reactor to an operating temperature, and when the temperature of the reactor is at or above a predetermined temperature, supplying fuel to the reactor to produce the hydrogen-containing gas and introducing the produced hydrogen-containing gas into the catalytic afterburner to further heat the reactor, wherein during start-up the hydrogen-containing gas bypasses the fuel cell, and then when the reactor reaches an operating temperature the hydrogen-containing gas flows through the fuel cell before being introduced into the catalytic afterburner. The present invention further provides a system for reforming a fuel.

Description

[Technical field]

[0001] The present invention relates to a method for starting up a reactor for producing hydrogen-containing gas, and a system for such production, which is designed to decompose a substance to release hydrogen, which can be used, for example, by a fuel cell to generate electricity. [Background technology]

[0002] Hydrogen generation electric systems for producing hydrogen using a hydrogen carrier material are generally known. The hydrogen carrier material may be a liquid hydrogen carrier material, such as methanol and formic acid. The hydrogen generation system comprises a carrier reservoir for storing the hydrogen carrier material and a reaction chamber arranged to generate a H2 gas stream by converting the hydrogen carrier material, the H2 gas stream comprising hydrogen. The reaction chamber comprises an inlet arranged to receive the hydrogen carrier material from the carrier reservoir. The system further comprises an output conduit for discharging the H2 gas stream from the reaction chamber. When the formic acid is converted in the reaction chamber, a H2 gas stream containing hydrogen gas and carbon dioxide gas is generated.

[0003] Optionally, the output conduit of the hydrogen production system may be directly coupled to a fuel cell arranged to generate electrical energy by converting hydrogen, the output conduit providing a flow of H2 gas from the reaction chamber to the fuel cell.

[0004] US20180337416 discloses a portable energy generating device that converts formic acid into released hydrogen, alleviating the need for hydrogen tanks as a hydrogen source for fuel cell power. A drawback of the described device and method is that it is an early stage design.

[0005] There are still some problems to be solved or systems to be improved in order to bring this technology to market. A drawback of the energy generation system described above is that, by design, it produces low quality gas, which results in poor applicability. Another drawback is that the efficiency needs to be improved. A further drawback is that the system cannot be easily used for scale-up for larger applications.

[0006] Thus, there is a need for processes and systems for generating electrical power that are flexible, portable, and easy to commercialize. Additionally, there is a need for systems that produce higher purity hydrogen-containing gases. Summary of the Invention

[0007] It is an object of the present invention to provide a method for starting up a reactor for producing a hydrogen-containing gas and subsequently maintaining the reactor at an operating temperature. A fuel cell is fluidly connected downstream of the reactor and upstream of a catalytic afterburner. The method includes the steps of: - storing a hydrogen-containing gas in a container; - opening the container and releasing the hydrogen-containing gas from the container; - reacting the released hydrogen-containing gas mixed with an oxygen-containing gas, preferably air, in a catalytic afterburner to produce heat and heated exhaust gases; - introducing heat and / or heated exhaust gas into the reactor to heat the reactor to an operating temperature; - when the temperature of the reactor is equal to or greater than the predetermined temperature, supplying fuel to the reactor to generate a hydrogen-containing gas and introducing the generated hydrogen-containing gas into a catalytic afterburner to further heat the reactor; During start-up, the hydrogen-containing gas bypasses the fuel cell, and then, once the reactor reaches operating temperature, the hydrogen-containing gas flows through the fuel cell before being introduced into the catalytic afterburner.

[0008] By using hydrogen stored in the system itself, no additional heat source needs to be used to start the process. Furthermore, converting hydrogen to generate electricity, for example in a fuel cell, is less efficient than catalytic combustion of hydrogen. Thus, starting the process using, for example, a catalytic afterburner instead of an electric heater significantly improves the overall efficiency of the system. Once the operating temperature of the reactor is reached, the operating temperature can be maintained by directing hydrogen-containing gas from the reactor through the fuel cell to the catalytic afterburner. The fuel cell can generate electricity for an external load.

[0009] The present invention also relates to a system for starting up a reactor for producing a hydrogen-containing gas. It is therefore a further object of the present invention to provide a system for cracking fuel, comprising a vessel for storing a hydrogen-containing gas, a reactor for producing a hydrogen-containing gas, a catalytic afterburner for combusting the hydrogen-containing gas from the vessel and / or from the reactor mixed with an oxygen-containing gas such as air to produce heat and exhaust gases, the catalytic afterburner being in fluid communication with the reactor and the vessel, means for supplying the oxygen-containing gas such as air to the catalytic afterburner, and means for supplying heat from the catalytic afterburner to the reactor.

[0010] It is also an object of the present invention to provide a system for reforming a fuel, the system comprising: a vessel for storing a hydrogen-containing gas, the vessel being a reactor for producing the hydrogen-containing gas; a catalytic afterburner for combusting the hydrogen-containing gas from the vessel to generate heat and exhaust gases, the catalytic afterburner in fluid communication with the vessel, means for supplying air to the catalytic burner, and means for supplying heat from the catalytic afterburner to the reactor.

[0011] The system described above is, in particular a fuel cell fluidly connected downstream of the reactor and fluidly connected upstream of a catalytic afterburner; a bypass directly fluidly connecting the reactor to the catalytic burner; a bypass valve that allows switching between directly fluidly connecting the reactor to the catalytic afterburner and fluidly connecting the reactor to a fuel cell.

[0012] These systems allow convenient implementation of the methods according to the invention, which may be under manual control, partially automatic control or fully automated.

[0013] The system may include a temperature sensor disposed with the reactor to detect a temperature of the reactor. The system may be configured to control a bypass valve based on the detected reactor temperature. The temperature sensor measurement may act on the bypass valve directly or via a controller of the system. For example, the controller, e.g., a processor or microchip, may be configured to receive the detected reactor temperature from the temperature sensor and control the bypass valve based on the received temperature. The controller may control the bypass valve to switch from supplying hydrogen-containing gas directly to the catalytic afterburner to supplying hydrogen-containing gas from the reactor to the fuel cell, which creates catalytic afterburning to maintain an operating temperature in the reactor.

[0014] Alternatively or additionally, such a controller may be configured to control fuel inlet to the reactor, for example, when a predetermined threshold temperature is reached at which the reactor is capable of producing hydrogen-containing gas. In this manner, automatic start-up from a low temperature, through a predetermined temperature, up to the operating temperature of the reactor can be performed.

[0015] It will be appreciated that the predetermined temperature and the operating temperature may be selected based on the fuel reforming process being carried out in the reactor, including parameters such as fuel type, catalyst type, and pressure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the present invention.

[0017] The present invention therefore relates to fuel cell technology. For example, when a fuel cell system starts up from a low temperature to generate electricity, a heat input is required for the production of hydrogen. At start-up, the reactor is not warm enough to produce hydrogen gas, so for start-up, hydrogen from a storage container is used. As a storage container, the reactor itself can be used or a separate container can be used. The hydrogen is released over time, preferably by using a pressure regulator or a valve. This hydrogen is then mixed with an appropriate amount of air, preferably by injecting hydrogen into an air stream, for example, via a gas splitter (e.g., a tube(s) with multiple small holes). The formed mixed exhaust gas / air mixture passes through a catalytic afterburner, where hydrogen and oxygen react to produce mainly heat and water (steam). The increased temperature of the catalytic afterburner improves the efficiency of the catalyst, so that once the catalyst starts up, it continues to operate itself as long as fuel and oxygen are present. The advantage of this method is that the reactor can be fully heated from the catalytic afterburner, so that, for example, during the start-up of the reformer, an electric heater is not needed.

[0018] The primary function of the catalytic afterburner is to generate heat to heat and maintain the reformer at the optimum reaction temperature. This is done by burning hydrogen-containing exhaust gas from the fuel cell and converting it into heat. For example, depending on the stoichiometry of the fuel cell, up to 20% to 40% of the hydrogen produced in the reformer is not converted to electricity, and this gas can be catalytically combusted in the catalytic afterburner using a catalyst, e.g., a metal foam coated with a catalyst, such as a platinum-coated FeCr alloy foam.

[0019] Catalytic afterburners can advantageously operate at higher temperatures (e.g., in the range of 250°C to 400°C) and with lower purity hydrogen-containing gas than fuel cells. Fuel cells typically operate at about 70°C, which may be insufficient to heat the reactor to the desired operating temperature. Furthermore, CO may be present in the hydrogen-containing gas from the vessel and / or reactor, which can rapidly reduce the effectiveness of the fuel cell by damaging the fuel cell's catalytic membrane. However, catalytic afterburners are not degraded by CO or by moisture or water droplets in the gas supplied to them. While fuel cells generally required additional purged hydrogen gas for efficient operation, catalytic afterburners can convert substantially all of the hydrogen supplied to them by adjusting the oxygen feed.

[0020] In a catalytic afterburner, a gas stream of hydrogen-containing gas is mixed with a stream of oxygen-containing gas, such as air, and the mixture is catalytically combusted to produce heat and exhaust gases. In contrast, the gas streams are separated in a fuel cell, with the hydrogen-containing gas fed to one side of a membrane and the oxygen-containing gas fed to the other side of the membrane.

[0021] The step of reacting the released hydrogen-containing gas intermixed with an oxygen-containing gas, preferably air, in a catalytic afterburner to produce heat and a heated exhaust may include intermixing the hydrogen-containing gas with the oxygen-containing gas and feeding the resulting mixture to the catalytic afterburner. This mixing may occur before the gas streams are introduced into the catalytic afterburner, although it is also envisioned to mix them within the catalytic afterburner upon introduction thereto.

[0022] Preferably, the catalytic afterburner is the only burner used in the present process.

[0023] The reformer does not need to be heated to its optimum operating temperature so that it can convert formic acid to hydrogen. At lower temperatures, the fuel, e.g., formic acid, is already converted. Thus, the amount of hydrogen that needs to be stored is sufficient to heat it to a temperature that can convert enough fuel to maintain a steady hydrogen supply to the catalytic afterburner to further increase the temperature of the reformer. Thus, the amount of hydrogen stored, and the associated size of the storage vessel, is not very large and still contains all the hydrogen gas required to fully heat the reformer to its optimum operating temperature.

[0024] The predetermined temperature may be equal to or less than the operating temperature.

[0025] For example, the operating temperature is in the range of 90°C to 130°C, preferably 90°C to 110°C, and more preferably 100°C.

[0026] For example, the predetermined temperature is at least 50°C and / or is in the range of 40°C to 90°C, preferably 50°C to 80°C.

[0027] When the system is shut down, the hydrogen storage vessel is preferably refilled with hydrogen produced in the reformer, which is still functional due to its residual heat. This hydrogen is preferably then used in the next start-up sequence.

[0028] The hydrogen-containing gas is stored in a vessel. Preferably, the vessel is the reactor. Alternatively, the vessel is a separate vessel. This requires additional space, but in some cases is the preferred option.

[0029] Preferably, the fuel cell is fluidly connected downstream of the reactor and upstream of the catalytic afterburner. In a fuel cell, the chemical energy of a fuel (e.g., hydrogen) and an oxidant (e.g., oxygen) is converted into electricity in an electrochemical cell via a pair of oxidation-reduction reactions. A fuel cell can continuously generate electricity as long as fuel and oxygen are supplied.

[0030] There are many types of fuel cells, but they all consist of an anode, a cathode, and an electrolyte that allows ions, often positively charged hydrogen ions (protons), to move between the two sides of the fuel cell. At the anode, a catalyst causes an oxidation reaction in the fuel, producing ions (often positively charged hydrogen ions) and electrons. The ions move through the electrolyte from the anode to the cathode. At the same time, electrons flow through an external circuit from the anode to the cathode, producing direct current electricity. At the cathode, another catalyst reacts the ions, electrons, and oxygen to form water and possibly other products. Fuel cells are classified by the type of electrolyte they use and by differences in start-up times, ranging from one second for proton exchange membrane fuel cells (PEM fuel cells, or PEMFCs) to 10 minutes for solid oxide fuel cells (SOFCs). Because individual fuel cells generate a relatively small electrical potential of about 0.7 volts, the cells are "stacked," or arranged in series, to generate enough voltage to meet the requirements of the application. In addition to electricity, fuel cells produce water, heat, and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions. The energy efficiency of fuel cells is generally between 40-60%.

[0031] Preferably used fuel cells are proton exchange membrane fuel cells (PEMFC), phosphoric acid fuel cells (PAFC), solid acid fuel cells (SAFC), alkaline fuel cells (AFC), high temperature fuel cells or power storage fuel cells, more preferably proton exchange membrane fuel cells (PEMFC), even more preferably low temperature proton exchange membrane fuel cells (PEMFC).

[0032] Advantageously, there is a bypass that fluidly connects the reactor directly to the catalytic burner. Advantageously, the vessel in which the hydrogen is stored is a separate vessel and is located within the bypass.

[0033] The heat of the hotter exhaust gas from the catalytic burner is preferably transferred to the cooler liquid in the reactor. Advantageously, the heated exhaust gas is introduced into a heat exchanger to transfer heat to the reactor in order to heat the reactor to a desired temperature. More preferably, more heat exchangers are used to heat the reactor to a desired temperature.

[0034] Advantageously, in the method of the present invention, during start-up, the hydrogen-containing gas bypasses the fuel cell, and thereafter, when the reactor reaches an operating temperature of at least 50° C., the hydrogen gas flows through the fuel cell before being introduced into the catalytic afterburner.

[0035] In some cases, it may be preferable to use an electric heater to partially heat the reactor to a temperature where the fuel can be converted to a hydrogen-containing gas. This can be useful the very beginning when the entire method and system is started. When first started, there is always some hydrogen present to start the reactor.

[0036] Preferably, the hydrogen-containing gas is mixed with an excess of air, so that a mixture having less than 15% hydrogen, more preferably less than 10% hydrogen, even more preferably less than 4% hydrogen is produced prior to reaction in the catalytic afterburner. The catalytic afterburner is most preferably operated by mixing the exhaust gas with an excess of air to produce a mixture having less than 4% hydrogen and maintaining it below the LFL at ambient pressure. Preferably, the hot air produced after catalytic combustion is passed through a radiator to heat a heat transfer liquid. This liquid can then be used to keep the reformer at the appropriate temperature.

[0037] Preferably, the process according to the invention provides the fuel as a liquid fuel and introduces the fuel together with the catalyst into the reactor to provide a mixture of liquid fuel and catalyst in the reactor, which has the advantage that separation of gas from liquid is better since the reaction is taking place early in the process.

[0038] In another embodiment, the method of the present invention provides for introducing the mixture of liquid fuel and catalyst removed from the reactor into a second heat exchanger located outside the reactor and outside the catalytic afterburner, the second heat exchanger being fluidly connected to the first heat exchanger by a closed water loop; where - the water in the closed water loop is heated by the exhaust gases in a first heat exchanger, - the heated water in the closed water loop flows to a second heat exchanger to transfer heat to the liquid fuel and catalyst mixture; The heated mixture of liquid fuel and catalyst is returned to the reactor, thereby heating the reactor.

[0039] In a further embodiment, the method of the invention provides the possibility that air is transported directly through the reactor, preferably via one or more pipes, thereby heating the reaction mixture, or a heat exchanger is placed inside the reactor, which heats the reaction mixture. More preferably, the pipes have a small diameter to create a large surface on which the heat exchange can be carried out more quickly. A further possibility is that the heat exchanger is outside the reactor, and the reaction mixture is pumped through this heat exchanger and heated to the desired reaction temperature. In another alternative configuration, a combination of heat exchangers is used, and a heat exchange transport liquid, for example a water loop, is used.

[0040] To supply hydrogen to the fuel cell, formic acid is preferably used as the hydrogen source in the reactor, and thus the fuel supplied to the reactor is preferably formic acid. Formic acid is a relatively non-toxic chemical. It is one of the main products formed in biomass processing and can be a convenient hydrogen carrier for fuel cells designed for portable power generation and use. Decomposition of formic acid to hydrogen is a promising way to solve the difficulties of hydrogen gas storage, which has severely limited the hydrogen economy. A sustainable cycle can be envisioned in which formic acid is used to supply hydrogen.

[0041] To store hydrogen, hydrogen and CO2 are added together to form formic acid. To release hydrogen, the formic acid is decomposed into hydrogen and CO2 in a reactor. The hydrogen storage density of formic acid is relatively high. Because formic acid is low in cost, non-flammable, readily available as an exhaust from fuel cells, and contains only water and CO2, automobiles or other devices or systems requiring electricity built on formic acid technology can be environmentally friendly. The system is less likely to explode or catch fire. This technology can be used independently or integrated with electric vehicles to provide instant power so that long battery charging times can be avoided.

[0042] The present invention further relates to a system for reforming a fuel, the system comprising: a vessel for storing a hydrogen-containing gas; a reactor for producing a hydrogen-containing gas; a catalytic afterburner for combusting the hydrogen-containing gas from the vessel and / or from the reactor to generate heat and exhaust gases, the catalytic afterburner in fluid communication with the reactor and the vessel; means for supplying air to the catalytic afterburner; and means for supplying heat from the catalytic afterburner to the reactor.

[0043] Alternatively, the present invention provides a system for reforming a fuel, the system comprising: a vessel for storing a hydrogen-containing gas, the vessel being a reactor for producing the hydrogen-containing gas; a catalytic afterburner for combusting the hydrogen-containing gas from the vessel to produce heat and exhaust gases, the catalytic afterburner in fluid communication with the vessel, means for supplying air to the catalytic burner, and means for supplying heat from the catalytic afterburner to the reactor.

[0044] In a preferred embodiment, the fuel cell is fluidly connected downstream of the reactor and upstream of the catalytic afterburner.

[0045] In another embodiment, the means for supplying heat from the catalytic afterburner to the reactor comprises a first heat exchanger for heating the reactor by transferring heat from the exhaust gas, the first heat exchanger being located externally away from the catalytic afterburner.

[0046] Preferably, the bypass fluidly connects the reactor directly to the catalytic burner. The vessel for storing hydrogen is preferably a separate vessel and is located within the bypass.

[0047] The system according to the present invention further preferably comprises a bypass valve that allows switching between directly fluidly connecting the reactor to the catalytic afterburner and fluidly connecting the reactor to the fuel cell.

[0048] The system according to the invention further preferably comprises an electric heater for partially heating the reactor to a temperature at which the fuel can be converted into a hydrogen-containing gas. This can be useful at the very beginning when the whole method and system is started. When first started, there is always some hydrogen present to start the reactor.

[0049] Preferably, the system according to the invention further comprises a reactor equipped with one or more inlets for introducing liquid fuel and catalyst so that the reactor can be filled with a mixture of liquid fuel and catalyst.

[0050] In a further preferred embodiment, the system further comprises: a pump for removing the mixture of liquid fuel and catalyst from the reactor; a second heat exchanger for receiving a mixture of liquid fuel and catalyst, the second heat exchanger being located outside the reactor and outside the catalytic afterburner; a closed heat transfer liquid loop fluidly connecting the first heat exchanger and the second heat exchanger; Therefore, the system: - heating a heat transfer liquid in a closed heat transfer liquid loop by heat exchange with exhaust gas in a first heat exchanger; - transferring heat from the heated heat transfer liquid to a mixture of liquid fuel and catalyst in a second heat exchanger; - introducing the heated mixture of liquid fuel and catalyst back into the reactor, thereby heating the reactor.

[0051] Preferably, the heat transfer liquid is water, glycol, or oil. [Brief description of the drawings]

[0052] The following non-limiting drawings further illustrate the invention. [Figure 1] A system and method for starting up a reactor for producing a hydrogen-containing gas is presented, where the reactor is used for hydrogen storage. [Diagram 2] A system and method for starting up a reactor for producing a hydrogen-containing gas is presented, in which a storage vessel is used for hydrogen storage.

[0053] In FIG. 1, a tank (1) is used to store a fuel, for example formic acid. The fuel is fed to the reactor (2) via a pump (3). The pressure in the reactor is regulated via a back pressure regulator (4). Via a valve (5), the hydrogen coming from the reactor can be transported to the fuel cell (6) or bypassed directly to the catalytic afterburner (7). The catalytic afterburner receives the exhaust gas from the fuel cell (6), which contains some unconverted hydrogen, via a check valve (8) that prevents the gas from returning to the fuel cell (6). In the catalytic afterburner (7), a catalyst is present to convert the hydrogen into heat by means of an oxygen-containing gas, for example air, entering the reactor via an inlet (9). The generated heat is transported to the reactor (2) via a heat exchanger (10), where a heat transfer liquid is heated with the hot gas present in the catalytic afterburner (7). Via a pump (11), the heat transfer liquid is pumped to a heat exchanger (12) where heat is transferred to the catalyst present in the reactor (2).

[0054] In Figure 2, there is an additional storage vessel (13) for storing hydrogen-containing gas. Hydrogen is fed to the storage vessel from the reactor (2) via valve (5). The stored hydrogen from the storage vessel (13) may be fed to the catalytic afterburner (7) via valve (14). The main advantage of having the additional storage vessel (13) is the flexibility it provides in the process, more hydrogen can be stored and the reactor system can be kept under pressure, although if the reactor is used as a storage vessel, the design may be a volume reducer.

[0055] The following non-limiting examples are provided to illustrate the invention. To enable automated implementation of the method of the invention, various system components, including the bypass valve (V1), the proportional valve (V2), the fuel supply (P1), and the heat transfer liquid pump (P2), can be coupled to a controller. For example, the system may include a temperature sensor coupled to the reactor and a controller configured to control the bypass valve based on a temperature signal received from the temperature sensor. The system may be configured to implement the method of the invention, and may be an automated method.

[0056] Example 1: Control procedure - Reactor used as storage vessel A number of situations were computer modeled to test the operation of the invention. In this first adjustment, the assumed starting condition is the reactor at 10° C. and the pressure inside the reactor is 15 bar. At start-up, the bypass valve (V1) is switched from the fuel cell to the catalytic heater and no gas flow passes through the fuel cell. The catalytic heater blower is then started and the catalytic block is preheated as needed (may be required during winter). The back pressure regulator (BPR) is opened slightly to the point where the H2 flow is sufficient to operate the catalytic heater to the point where the required H2 flow is achieved. The valve is opened more gradually to compensate for the pressure drop in the reactor. The heat transfer liquid pump (P2) is started to transfer heat from the catalytic afterburner to the reactor. When the reactor reaches its operating temperature of 100° C., the bypass valve is switched back to the fuel cell and the proportional valve (or back pressure regulator) is closed. Now, the formic acid feed is started (P1) and the reactor can start producing more H2 (and CO2). The gas evolution brings the pressure back up to its pre-designated operating point, in this case 15 bar. Once the reactor is back to its operating pressure, the backpressure regulator can be opened again and gas can pass through the fuel cell.

[0057] No special shutdown procedures were required to shut down the reactor because it was already under pressure and was large enough to store all the hydrogen needed to then start up again.

[0058] Example 2: Control Procedure - Using an External Reservoir. Variation 1 In this adjustment, the starting conditions assumed are the reactor being at 10° C., the pressure inside the reactor being 15 bar, and there is 1000 nL of H 2 stored in a storage vessel at a pressure of 15 bar.

[0059] At start-up, the bypass valve (V1) was switched from the fuel cell to the catalytic heater to prevent gas flow from passing through the fuel cell. The catalytic heater blower was started. The proportional valve (V2) was opened slightly to the point where the required H2 flow was achieved. Optionally, the back pressure regulator could be opened to use the H2 (and therefore pressure) from the reactor as well. The valve was opened more gradually to compensate for the pressure drop in the storage vessel. The heat transfer liquid pump (P2) was then started to transfer heat from the catalytic afterburner to the reactor. When the reactor reached its operating temperature of 100°C, the bypass valve was switched back to the fuel cell and the proportional valve was closed. The formic acid feed was then started (P1) and the reactor started to produce more H2 (and CO2). If the H2 in the reactor was used, the gas evolution increased the pressure back to its operating point of 15 bar, otherwise gas was immediately transferred to the fuel cell by opening the back pressure regulator.

[0060] To shut down the fuel cell, the bypass valve (V1) from the reactor to the storage vessel was opened. More formic acid was added to the reactor to generate more H2 and CO2 with the residual heat left in the reactor. Once the storage vessel reached the correct pressure, the formic acid feed was stopped and the valve from the reactor to the storage vessel was closed.

[0061] The inventors have found that the advantage of using a separate storage vessel is that during shutdown, the residual heat still remaining in the reactor is used to generate the H2 needed to start the reactor again. If the reactor itself is the storage vessel, there is a downtime between the start-up state and the operating state to bring the reactor back up to the operating pressure as a result of depressurizing the reactor to vent the gases. To return to the operating point, extra gas must be generated to build up the pressure, and this gas cannot be used by the fuel cell. Only when the pressure is high enough again does the extra gas generated pass through.

[0062] Example 3: Control Procedure - Using an External Reservoir. Variation 2 In this preparation, the same conditions and procedures as in Example 2 were used, but here the storage pressure was higher than the operating pressure. The storage volume was reduced in proportion to the pressure compared to Example 2. This worked very well as long as the storage vessel itself and the equipment around the storage vessel (temperature sensor, pressure sensor, level sensor, valves, etc.) were adapted to the higher pressure. The inventors calculated that the equipment downstream of the storage vessel could remain the same as in Example 2.

[0063] Example 4: Control Procedure - Using an External Reservoir. Variation 3 During start-up of the reactor, it is possible to start the conversion of small amounts of formic acid already at reactor temperatures lower than the normal operating temperature of the reactor. The following procedure was tested:

[0064] At start-up, the bypass valve (V1) was switched from the fuel cell to the catalytic heater to prevent gas flow from passing through the fuel cell. The catalytic heater blower was started. The proportional valve (V2) was opened slightly to the point where the required H2 flow was achieved. Optionally, the back pressure regulator could be opened to also use the H2 (and therefore pressure) from the reactor. The valve was opened more gradually to compensate for the pressure drop in the storage vessel. The heat transfer liquid pump (P2) was then started to transfer heat from the catalytic afterburner to the reactor. Once the reactor reached a predefined threshold temperature, for example 80°C, a small amount of formic acid was added to the reactor, producing a small amount of H2 and CO2 to slow down the consumption of the gas in the storage vessel. The formic acid feed could be gradually increased with the reactor temperature, since it was also possible to convert more formic acid if the reactor temperature was increased. In other words, the pumping of fuel to the reactor could be increased as the reactor temperature increased from the predefined temperature to the normal operating temperature. When the reactor reached its operating temperature of 100°C, the bypass valve was returned to the fuel cell and the proportional valve (or back pressure regulator) was closed. The reactor now produced more H2 (and CO2). Gas evolution caused the pressure to rise back to its operating pressure. With the reactor back to its operating pressure, the proportional valve (or back pressure regulator) was reopened and the gas was allowed to pass to the fuel cell.

[0065] Example 5: Various variations of initial start-up of reactor system The system was filled with hydrogen in the storage vessel during shutdown in the previous example, which means that for the very first start-up, there is still no H2 available. Different options were modeled to find the best solution for this situation.

[0066] Solution 1: The reactor was heated electrically and since this was the first start-up, the batteries present in the system were also empty. Therefore, an external power source was used.

[0067] Solution 2: Filled the storage vessel with hydrogen from an external hydrogen bottle. This was a fairly practical solution to the very first start-up problem.

[0068] Solution 3: The catalytic heater (and the rest of the system) was started with hydrogen from a bottle. During shutdown, the storage vessel was filled as described in the shutdown procedure above.

Claims

1. 1. A method for starting a reactor for producing a hydrogen-containing gas and thereafter maintaining said reactor at an operating temperature, wherein a fuel cell is fluidly connected to said reactor downstream of said reactor and to a catalytic afterburner upstream of said catalytic afterburner, said method comprising: - storing a hydrogen-containing gas in a container; - opening the container and releasing the hydrogen-containing gas from the container; - reacting the released hydrogen-containing gas mixed with an oxygen-containing gas in a catalytic afterburner to produce heat and heated exhaust gases; - introducing said heat and / or said heated exhaust gas into said reactor to heat said reactor to said operating temperature; - when the temperature of the reactor is equal to or higher than a predetermined temperature, supplying fuel to the reactor to generate a hydrogen-containing gas, and introducing the generated hydrogen-containing gas into the catalytic afterburner to further heat the reactor; A method wherein during start-up, a hydrogen-containing gas bypasses the fuel cell, and then, once the reactor reaches operating temperature, the hydrogen-containing gas flows through the fuel cell before being introduced into the catalytic afterburner.

2. 10. The method of claim 1, comprising the following features: - the operating temperature is in the range of 90°C to 130°C, - the predetermined temperature is in the range of 40°C to 90°C; - the predetermined temperature is equal to or less than the operating temperature; The method is characterized by at least one of the following:

3. 10. The method of claim 1, wherein the heated exhaust gas is introduced into a heat exchanger to transfer heat to the reactor to heat the reactor to a predetermined temperature.

4. 10. The method of claim 1, wherein the hydrogen-containing gas is mixed with an excess of an oxygen-containing gas such that a mixture having less than 15% hydrogen is produced prior to reaction in the catalytic afterburner.

5. 10. The method of claim 1, wherein the fuel is a liquid fuel and the fuel is introduced into the reactor along with a catalyst to provide a mixture of liquid fuel and catalyst within the reactor.

6. 10. The method of claim 1, wherein the fuel supplied to the reactor is formic acid.

7. 10. The method of claim 1, wherein the catalytic afterburner is the only burner used in the method.

8. The method of claim 1 , wherein the vessel is a reactor.

9. The method of claim 1 , wherein the containers are separate containers.

10. 10. The method of claim 9, wherein a bypass fluidly connects the reactor directly to the catalytic afterburner, and the vessel is disposed within the bypass.

11. 1. A system for reforming a fuel, comprising: a container for storing a hydrogen-containing gas, said container being the reactor for producing said hydrogen-containing gas or being a separate container in addition to the reactor for producing a hydrogen-containing gas; a catalytic afterburner in fluid communication with the reactor and the vessel for combusting the hydrogen-containing gas from the vessel and / or from the reactor mixed with an oxygen-containing gas to produce heat and exhaust gases; - means for supplying said oxygen-containing gas to said catalytic afterburner; - means for supplying heat from said catalytic afterburner to said reactor; a fuel cell fluidly connected downstream of said reactor and fluidly connected upstream of said catalytic afterburner; a bypass directly fluidly connecting the reactor to the catalytic afterburner; a bypass valve that allows switching between directly fluidly connecting the reactor to the catalytic afterburner and fluidly connecting the reactor to the fuel cell; a temperature sensor coupled to the reactor; - a control device configured to control the bypass valve based on a temperature signal received from the temperature sensor, in order to implement the method according to any one of claims 1 to 10.

12. The system of claim 11 , wherein the container is the separate container and is located within the bypass.

13. 12. The system of claim 11, wherein the reactor comprises one or more inlets for introducing liquid fuel and catalyst so that the reactor can be filled with a mixture of liquid fuel and catalyst.

14. 12. The system of claim 11, wherein the means for supplying heat from the catalytic afterburner to the reactor comprises a first heat exchanger for heating the reactor by transferring heat from the exhaust gas, the first heat exchanger being located externally, separate from the catalytic afterburner.

15. The system comprises: a pump for removing the mixture of liquid fuel and catalyst from the reactor; a second heat exchanger for receiving a mixture of liquid fuel and catalyst, the second heat exchanger being located outside the reactor and outside the catalytic afterburner; a closed heat transfer liquid loop fluidly connecting said first heat exchanger and said second heat exchanger, Therefore, the system - heating the heat transfer liquid in the closed heat transfer liquid loop by heat exchange with the exhaust gas in the first heat exchanger; - transferring heat from the heated heat transfer liquid to the mixture of liquid fuel and catalyst in the second heat exchanger; - introducing said heated mixture of liquid fuel and catalyst back into said reactor, thereby heating said reactor.

16. The system of claim 11 , wherein the catalytic afterburner is the only burner in the system.

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