Hydrogen power generation system for generating electricity from hydrogen using hydrogen carrier material and method for operating hydrogen power generation system.

Abstract

A hydrogen power generation system for generating electricity from hydrogen using a hydrogen carrier material includes: a reaction chamber arranged to generate an H2 gas stream by converting the hydrogen carrier material, wherein the reaction chamber includes an inlet arranged to receive the hydrogen carrier material; an output conduit for discharging the H2 gas stream; a fuel cell arranged to generate electrical energy by converting hydrogen; the output conduit arranged to supply the H2 gas stream from the reaction chamber to the fuel cell; the system further includes: a humidity determination unit arranged to determine the humidity level of the H2 gas stream; a water supply device for supplying H2O to the reaction chamber; and a water vapor control device arranged to control the water vapor level in the reaction chamber in response to the determined humidity level, wherein the generated H2 gas stream comprises hydrogen and water vapor.

Description

Technical Field

[0001] The present invention relates to a hydrogen power generation system for generating electricity from hydrogen using a hydrogen carrier material. The present invention also relates to a method for operating a hydrogen power generation system according to the present invention. Background Art

[0002] Hydrogen power generation systems using hydrogen carrier materials to produce hydrogen are known. The hydrogen carrier material can be a liquid hydrogen carrier material, such as methanol and formic acid. The hydrogen generation system includes a carrier storage tank for storing the hydrogen carrier material and a reaction chamber arranged for generating an H2 gas stream by converting the hydrogen carrier material, wherein the H2 gas stream comprises hydrogen. The reaction chamber includes an inlet arranged for receiving the hydrogen carrier material from the carrier storage tank. The system also includes an outlet conduit for discharging the H2 gas stream from the reaction chamber. In the case of converting formic acid in the reaction chamber, an H2 gas stream containing hydrogen and carbon dioxide gases is generated.

[0003] Alternatively, the output conduit of the hydrogen generation system can be directly coupled to the fuel cell. The fuel cell is configured to generate electricity by converting hydrogen. The output conduit supplies an H2 gas stream from the reaction chamber to the fuel cell.

[0004] Generally, fuel cells require a certain desired humidity level internally for efficient operation. The fuel cell generates electricity while simultaneously forming water by converting hydrogen and additional oxygen within the fuel cell according to the reaction scheme H₂ + 2O₂ -> 2H₂O. The fuel cell's output (gas) stream contains water in the gaseous phase, which is used (at least partially) and returned to the fuel cell inlet to maintain the desired humidity level inside the fuel cell. The output gas stream typically additionally contains residual hydrogen and / or oxygen that were not converted within the fuel cell. The vapor content from the output gas stream needs to be separated from any residual hydrogen and / or oxygen in the output gas stream before it is introduced into the fuel cell. For vapor separation, a NAFION membrane is used, which is a relatively expensive component. Additionally, control over the vapor transfer rate through the NAFION membrane to the fuel cell is limited.

[0005] Furthermore, it is desirable to provide a system for generating electricity from hydrogen using a hydrogen carrier material, which is capable of easily controlling both the hydrogen content and the water (or vapor) level in the gas stream. Summary of the Invention

[0006] According to a first aspect of the present invention, a hydrogen power generation system for generating electricity from hydrogen using a hydrogen carrier material is provided, the system comprising:

[0007] The reaction chamber is configured to generate an H2 gas stream by converting a hydrogen carrier material.

[0008] The reaction chamber includes an inlet arranged for receiving hydrogen carrier material;

[0009] An output conduit is used to discharge the H2 gas stream from the reaction chamber;

[0010] A fuel cell, which is arranged to generate electricity by converting hydrogen;

[0011] Furthermore, an output duct is arranged to supply H2 gas flow from the reaction chamber to the fuel cell;

[0012] The system also includes

[0013] A humidity determination unit is arranged to determine the humidity level of the H2 airflow;

[0014] A water supply device for supplying H2O to the reaction chamber; and

[0015] A water vapor control device is arranged to control the water vapor level in the reaction chamber in response to a determined humidity level, and

[0016] The generated H2 gas stream includes hydrogen and water vapor.

[0017] According to another aspect of the present invention, a method for operating a hydrogen power generation system according to the present invention is provided, the method comprising the following steps:

[0018] The hydrogen carrier material is received in the reaction chamber;

[0019] Water is received in the reaction chamber;

[0020] The reaction chamber generates an H2 gas stream by converting a hydrogen carrier material, wherein the H2 gas stream includes hydrogen and water vapor;

[0021] A humidity determination unit that determines the humidity level of the H2 airflow;

[0022] A water vapor control device that controls the water vapor level in the reaction chamber in response to a determined humidity level;

[0023] A fuel cell that generates electricity by converting hydrogen supplied to the fuel cell by an H2 gas stream.

[0024] The hydrogen power generation system of the present invention has the advantage that it can generate an H2 gas flow for a fuel cell using a system containing hydrogen and a suitably controlled water vapor concentration. The water vapor concentration can be suitably controlled within a target vapor concentration range by the hydrogen generation system. The hydrogen generation system controls hydrogen formation by converting the hydrogen carrier material, thereby controlling the hydrogen concentration of the H2 gas flow. Water is supplied to the reaction chamber by a water supply device. A water vapor control device is arranged to control the water vapor level in the reaction chamber in response to a determined humidity level. The water vapor level in the reaction chamber determines the humidity level of the H2 gas flow.

[0025] In this embodiment, the water vapor control device controls the water vapor concentration of the H2 gas stream by appropriately controlling at least one of the internal pressure of the reaction chamber and the reaction temperature of the reaction chamber. The internal pressure of the reaction chamber and the reaction temperature of the reaction chamber affect the evaporation process of water within the reaction chamber, thereby controlling the water vapor concentration of the H2 gas stream leaving the reaction chamber. The reaction temperature is the temperature within the reaction chamber where hydrogen is formed.

[0026] In one embodiment, a water vapor control device is arranged to control the humidity level of the H2 stream within a target vapor concentration range. In a preferred embodiment, a target vapor concentration range is selected for the fuel cell.

[0027] In the embodiments, the hydrogen carrier material is a liquid at room temperature.

[0028] In certain embodiments, the hydrogen carrier is selected from formic acid and methanol, and mixtures thereof. In a preferred embodiment, the hydrogen carrier is formic acid.

[0029] In one embodiment, the hydrogen generation system further includes a fuel cell arranged to generate electricity by converting hydrogen; and an output conduit arranged to supply an H2 gas stream from the reaction chamber to the fuel cell.

[0030] In this embodiment, the water vapor control device includes at least one of the following:

[0031] The pressure control unit is used to control the internal gas pressure of the reaction chamber; and

[0032] Temperature control unit, used to control the reaction temperature in the reaction chamber.

[0033] In one embodiment, the steam control device includes a central control unit to control at least one of the pressure control unit and the temperature control unit.

[0034] In one embodiment, the pressure control unit includes a pressure valve disposed at the output duct of the H2 gas flow to control the internal gas pressure of the reaction chamber.

[0035] In this embodiment, the water supply device includes at least one of the following:

[0036] A gas supply unit is arranged to provide a gas flow including water vapor to the reaction chamber;

[0037] A water supply unit, arranged to provide a liquid flow including water to the reaction chamber; and

[0038] The system includes a carrier storage unit for storing a hydrogen carrier composition containing a hydrogen carrier substance and water, wherein the inlet of the reaction chamber is arranged for receiving the hydrogen carrier composition containing water from the carrier storage unit.

[0039] In a particular embodiment, as a water supply device, a combination of at least two of a gas supply unit, a water supply unit, and a hydrogen carrier composition is used, the hydrogen carrier composition being disposed inside a carrier reservoir, which, in addition to the hydrogen carrier substance, also includes a certain amount of water.

[0040] In this embodiment, the hydrogen carrier material is liquid at room temperature, and a water vapor control device is arranged to control the surface liquid level of the reaction mixture within the reaction chamber. Specifically, the water vapor control device controls the surface liquid level of the reaction mixture to maintain it within a predetermined height range. In this way, overflow of the reaction chamber can be prevented. The water vapor control device can select at least one of the internal gas pressure of the reaction chamber and the reaction temperature of the reaction chamber to maintain the surface liquid level within the predetermined height range.

[0041] In this embodiment, the H2 gas stream comprises hydrogen and water vapor. The H2 gas stream may additionally contain other reaction products. In this example, when formic acid is converted, carbon dioxide is additionally formed, which exits the reaction chamber in the H2 gas stream.

[0042] In this embodiment, the humidity determination unit includes at least one of the following:

[0043] The sensor is positioned at the output conduit of the H2 flow; and

[0044] A liquid level sensor unit is arranged to sense the surface liquid level of a liquid reaction mixture containing a hydrogen carrier substance in a reaction chamber, wherein a humidity determination unit is arranged to calculate a humidity level based on the measured surface liquid level.

[0045] The liquid reaction mixture contains a hydrogen support material and water. In a specific example, the liquid reaction mixture may also contain a catalyst for catalyzing the conversion reaction of the hydrogen support material.

[0046] In the example, the humidity determination unit can determine the humidity level based on the known supply of liquid hydrogen carrier material and water to the reaction chamber, while the surface liquid level remains substantially constant.

[0047] In another example, the humidity determination unit can determine the humidity level based on the known outflow rate of the H2 gas stream containing hydrogen including water vapor from the reaction chamber, while the surface liquid level remains substantially constant.

[0048] In one embodiment, the humidity determination unit is arranged to provide a signal to the water vapor control device for indicating the humidity level.

[0049] In one embodiment, the system includes a carrier storage for storing hydrogen carrier material, wherein the inlet of the reaction chamber is arranged to receive hydrogen carrier material from the carrier storage.

[0050] In this embodiment, the hydrogen carrier material has a freezing temperature between 0 and 20 degrees Celsius. Preferably, the hydrogen carrier material is formic acid.

[0051] In a particular embodiment, the hydrogen generation system also includes a refrigeration control unit for controlling the water supply to the carrier storage unit in response to a measured ambient temperature.

[0052] In one embodiment, the hydrogen generation system also includes a conduit for delivering a water supply to a carrier storage device.

[0053] In one embodiment, the hydrogen generation system also includes a temperature sensor arranged to measure the ambient temperature.

[0054] In an embodiment, the hydrogen generation system further includes a water concentration determination unit for determining the water concentration of a hydrogen carrier composition containing a hydrogen carrier substance and a certain amount of water in a carrier storage container.

[0055] In an embodiment, the water concentration determination unit may be a sensor for sensing the water concentration of the hydrogen carrier composition, and may be an input device for receiving a signal indicating the water concentration of the hydrogen carrier composition, such as an input signal provided by the operator of the system.

[0056] In an embodiment, the water vapor control step includes controlling at least one of the internal air pressure of the reaction chamber and the reaction temperature of the reaction chamber in order to control the humidity level of the H2 gas flow.

[0057] In this embodiment, the water vapor control device controls the humidity level of the H2 airflow within a target vapor concentration range.

[0058] In this embodiment, the target vapor concentration range is the dew point range from -70°C to 100°C at 1 bar. Preferably, the target vapor concentration range is the dew point range from 0°C to 80°C at 1 bar, and more preferably, the dew point range from 30°C to 60°C at 1 bar.

[0059] In an embodiment, the hydrogen generation system further includes a fuel cell, and the method further includes the step of the fuel cell generating electrical energy by converting hydrogen, wherein hydrogen is supplied to the fuel cell by an H2 gas stream.

[0060] In one embodiment, when the humidity level of the H2 gas stream is below the target vapor concentration range, the internal pressure decreases and / or the reaction temperature increases; and when the humidity level of the H2 gas stream is above the target vapor concentration range, the internal pressure increases and / or the reaction temperature decreases.

[0061] In this embodiment, the temperature of the H2 gas stream supplied to the fuel cell is maintained above the dew point level of the H2 gas stream during delivery to the fuel cell. This prevents any loss of water vapor during delivery to the fuel cell.

[0062] In an embodiment, the reaction mixture is an aqueous solution containing formate.

[0063] In the embodiments, the reaction mixture additionally contains a catalyst.

[0064] In a particular embodiment, the catalyst comprises a complex of the following formula:

[0065] M(L) n (I)

[0066] in,

[0067] M is a metal selected from Ru, Rh, Ir, Pt, Pd and Os, preferably Ru;

[0068] n is in the range of 1 to 4;

[0069] L is a carbene or a ligand containing at least one phosphorus atom, the phosphor atom being bonded to the metal via a complex bond. The phosphorus ligand further comprises at least one aromatic group and a hydrophilic group, wherein...

[0070] If n>1, each L can be different from the other L;

[0071] The complex of formula (I) may optionally contain other ligands and be provided in the form of salts or neutral.

[0072] In this embodiment, the reaction temperature range of the reaction chamber is 20 to 200 degrees Celsius and / or the internal pressure in the reaction chamber is 1 to 1200 bar. Preferably, the reaction temperature range is 40 to 150 degrees Celsius.

[0073] Preferably, the partial pressure of the hydrogen is in the range of 0.5 to 600 bar.

[0074] Optionally, the partial pressure of carbon dioxide is in the range of 0.5 to 600 bar.

[0075] Preferably, the total internal pressure of the reaction chamber is in the range of 0.1 to 16 bar.

[0076] In another aspect of the invention, a hydrogen generation system for producing hydrogen using a hydrogen carrier material is provided, the system comprising:

[0077] The reaction chamber is configured to generate an H2 gas stream by converting a hydrogen carrier material.

[0078] The reaction chamber includes an inlet arranged for receiving hydrogen carrier material;

[0079] An output conduit is used to discharge the H2 gas stream from the reaction chamber;

[0080] The system also includes

[0081] A humidity determination unit is arranged to determine the humidity level of the H2 airflow;

[0082] A water supply device for supplying H2O to the reaction chamber; and

[0083] A water vapor control device is arranged to control the water vapor level in the reaction chamber in response to a determined humidity level.

[0084] The generated H2 gas stream includes hydrogen and water vapor, and

[0085] The H2 gas flow is suitable for providing fuel for fuel cells.

[0086] In another aspect of the invention, a method for operating a hydrogen generation system according to the invention is provided, the method comprising the following steps:

[0087] The hydrogen carrier material is received in the reaction chamber;

[0088] Water is received in the reaction chamber;

[0089] The reaction chamber generates an H2 gas stream by converting a hydrogen carrier material, wherein the H2 gas stream includes hydrogen and water vapor;

[0090] A humidity determination unit that determines the humidity level of the H2 airflow;

[0091] A water vapor control device that controls the water vapor level in the reaction chamber in response to a determined humidity level;

[0092] The H2 gas flow is suitable for supplying fuel to fuel cells.

[0093] In another aspect of this disclosure, a hydrogen generation system for producing hydrogen using a hydrogen carrier material is provided, the system comprising:

[0094] A carrier storage device for storing hydrogen carrier substances;

[0095] A reaction chamber arranged to generate an H2 gas stream by converting a hydrogen carrier material, wherein the H2 gas stream comprises hydrogen, and wherein the reaction chamber includes an inlet arranged to receive the hydrogen carrier material from a carrier storage unit.

[0096] An output conduit is used to discharge the H2 gas stream from the reaction chamber;

[0097] The system also includes:

[0098] A water supply device for supplying H2O to a carrier storage container; and

[0099] A refrigeration control unit is arranged to control the supply of water from the water supply device to the carrier storage unit in response to a measured ambient temperature.

[0100] The refrigeration control unit controls the water supply from the water supply device to the carrier storage container to prevent or limit the freezing of the hydrogen carrier material within the carrier storage container. When the measured ambient temperature decreases, such as below a predetermined threshold, the refrigeration control unit can control the water supply from the water supply device to the carrier storage container to increase the water concentration of the hydrogen carrier composition containing the hydrogen carrier material and water. Preferably, the hydrogen carrier material and water form a homogeneous mixture.

[0101] In this embodiment, the hydrogen carrier material has a freezing temperature between 0 and 20 degrees Celsius. Preferably, the hydrogen carrier material is formic acid.

[0102] In a particular embodiment, the hydrogen generation system also includes a refrigeration control unit for controlling the water supply to the carrier storage unit in response to a measured ambient temperature.

[0103] In one embodiment, the hydrogen generation system also includes a conduit for delivering a water supply to a carrier storage device.

[0104] In one embodiment, the hydrogen generation system also includes a temperature sensor arranged to measure the ambient temperature.

[0105] In an embodiment, the hydrogen generation system further includes a water concentration determination unit for determining the water concentration of a hydrogen carrier composition containing a hydrogen carrier substance and a certain amount of water in a carrier storage container.

[0106] In an embodiment, the water concentration determination unit may be a sensor for sensing the water concentration of the hydrogen carrier composition, and may be an input device for receiving a signal indicating the water concentration of the hydrogen carrier composition, such as an input signal provided by the operator of the system. Attached Figure Description

[0107] The accompanying drawings are provided to illustrate currently preferred, non-limiting exemplary embodiments of the device of the present invention. The above and other advantages of the features and objects of the invention will become more apparent and will be better understood from the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0108] Figure 1 The system according to this disclosure is shown;

[0109] Figure 2 : Showing from Figure 1 System components;

[0110] Figure 3 : Showing from Figure 1 A top view of the system's components;

[0111] Figure 4A and Figure 4B The method according to this disclosure is shown.

[0112] Figure 5 Another system according to this disclosure is shown. Detailed Implementation

[0113] System 1 is configured to produce hydrogen via the dehydrogenation of formic acid. System 1 includes a reaction vessel 3, an inlet conduit 13, a pump 15, and a temperature control arrangement 17. The reactor vessel 3 includes a reaction chamber 5 defined by a reactor wall 7. The reactor wall 7 includes a lower sidewall 27 and an upper sidewall 23. The upper sidewall 23 is provided with a gas outlet opening 25 for allowing hydrogen from a reaction mixture comprising formic acid and a catalyst to exit the reaction chamber 5 via the gas outlet opening 25. The exit of hydrogen from the reaction chamber 5 can be limited by a pressure valve arrangement 31. The pressure valve arrangement 31 is configured to control the internal pressure of the reaction chamber 5 by controllably allowing a flow of hydrogen from the reaction chamber 5 through the pressure valve arrangement 31. The lower sidewall 27 includes a mixture outlet opening 11 located at the center of the bottom side of the reactor vessel 3.

[0114] Reactor vessel 3 is arranged to contain a reaction mixture of catalyst, formic acid, and water in reaction chamber 5. Reactor vessel 3 includes a mixture inlet opening 9 for allowing the reaction mixture to enter reaction chamber 5 via the mixture inlet opening 9. In reaction chamber 5, a fixed flow mechanism 29 is disposed at or near reactor wall 7. The flow mechanism 29 extends substantially along the entire height of reaction chamber 5. In embodiments of system 1, it is conceivable that the flow mechanism extends only along the lower half of the height of reaction chamber 5.

[0115] The reactor vessel 3 is provided with an additional inlet opening 21, which is arranged to introduce formic acid from the carrier reservoir 35 into the reactor vessel 3 to form a reaction mixture. The carrier reservoir 35 is coupled to the fluid flow rate to the reaction chamber 5 via an additional pump 37. The additional pump 37 is arranged to pump formic acid from the carrier reservoir 35 into the reaction chamber 5.

[0116] The reactor wall 7 comprises a plastic coated with polytetrafluoroethylene (PTFE) on the side facing the reaction chamber 5. This serves to thermally insulate the reactor vessel 13 and shield the reaction mixture from the influence of the plastic in the reactor wall 7, which could otherwise degrade the catalyst present in the reaction chamber 5. The reactor wall 7 also includes a replaceable wall element 33. The replaceable wall element 33 comprises metal for locally reinforcing the reactor wall 7. The replaceable wall element 33 is coated with PTFE on the side facing the reaction chamber 5, serving to thermally insulate the reactor vessel 13 and shield the reaction mixture from the influence of the metal in the replaceable wall element 33, which could otherwise otherwise degrade the catalyst present in the reaction chamber 5. In embodiments of System 1, it is contemplated that, in addition to the replaceable wall element 33, or as an alternative to the replaceable wall element, the reactor wall is locally reinforced by fixed wall elements.

[0117] Inflow conduit 13 is connected and coupled to the fluid flow rate through the mixture inflow opening 9 to the reaction chamber 5. Inflow conduit 13 is arranged such that the reaction mixture is introduced into the reaction chamber 5 in use via the mixture inflow opening 9 in a predetermined direction having a tangential component T to agitate the reaction mixture in the reaction chamber 5 during use. In other words, the reaction mixture is introduced in a direction along the reactor wall 7, wherein the introduction direction has a tangential component T.

[0118] Pump 15 is connected and coupled to control the flow rate of fluid through mixture inlet 9 and mixture outlet 11 to reaction chamber 5. Pump 15 is configured to draw mixture from reaction chamber 5 through mixture outlet 11 and introduce mixture into reaction chamber 5 through inlet conduit 13 and inlet opening 9.

[0119] Temperature control arrangement 17 is connected and coupled to the fluid flow to pump 15 and is arranged to heat and / or cool the reaction mixture drawn from reaction chamber 5. Temperature control arrangement 17 is also arranged to cool and / or heat a portion of the reaction mixture present in temperature control arrangement 17 to a predetermined temperature in the range of 70 to 150 degrees Celsius before that portion of the reaction mixture is introduced into reaction chamber 5 via inflow conduit 13.

[0120] System 1 includes a control unit 41, a measuring unit 43, and a humidity determination unit 45. The control unit 41 is connected and coupled to the temperature control arrangement 17, the pump 15, and the measuring unit 43. The control unit 41 is configured to control the temperature control arrangement 17 and the pump 15 based on the temperature of the reaction mixture present in the reaction chamber 5 and / or the temperature control arrangement 17 during use, as measured by the measuring unit 43.

[0121] System 1 also includes a water supply device for supplying H2O to reaction chamber 5. The water supply device can be implemented as a gas supply unit arranged to supply a gas flow including water vapor to reaction chamber 5. The water supply device can also be implemented as a water supply unit arranged to supply a liquid flow including water to reaction chamber 5. Control unit 41 is arranged to control the gas supply unit and / or the water supply unit to controllably supply water to reaction chamber 5.

[0122] Alternatively or additionally, the carrier reservoir 35 of system 1 stores a formic acid composition containing formic acid and water at a certain concentration. The supply of the formic acid composition containing water to reaction chamber 5 is used as a water supply device. Therefore, the supply of formic acid and water to reaction chamber 5 is controlled by controlling pump 37.

[0123] System 1 also includes a water vapor control device arranged to control the water vapor level in the reaction chamber in response to a determined humidity level. The water vapor control device may include a pressure valve arrangement 31 for controlling the internal pressure of the reaction chamber and a temperature control arrangement 17 for controlling the reaction temperature in the reaction chamber. Specifically, the water vapor control device also includes a control unit 41 for controlling the pressure valve arrangement 31 and the temperature control arrangement 17 for controlling the water vapor level in the reaction chamber.

[0124] Method 101 is arranged for generating hydrogen by converting a hydrogen carrier material (such as by dehydrogenation of formic acid). Method 101 includes the step of providing formic acid 103 into the reaction chamber 5. Additionally, method 101 includes the step of providing water 105 into the reaction chamber 5.

[0125] In an embodiment of method 101, when the formic acid stream is a formic acid mixture containing formic acid and water of a predetermined concentration, the provision of water 105 and formic acid 103 can be performed in a single step 104. In an alternative or additional embodiment of method 101, the provision of water can be performed in step 105 independently of the step of providing formic acid 103 into the reaction chamber 5.

[0126] In other words, formic acid and water can be supplied to the reaction chamber 5 during different steps to allow the formic acid 103 and the water 105 to be stored separately and supplied to the reaction chamber 5 independently.

[0127] Step 105, which provides the water, can be implemented by a gas supply unit that supplies a gas stream including water vapor to the reaction chamber; and can also be implemented by a water supply unit that supplies a liquid stream including water to the reaction chamber. In a specific embodiment, both the gas supply unit and the water supply unit can be used to supply water to the reaction chamber 5.

[0128] In another embodiment, step 105 of providing the water can be combined with the step of providing water in the formic acid stream 104.

[0129] Method 101 also includes a step 107 of converting the hydrogen carrier material, such as by dehydrogenation of formic acid, to form a hydrogen-containing gas stream. The H2 gas stream leaves the reaction space 5 via the gas outlet opening 25 and reaches the outlet conduit 26.

[0130] Method 101 further includes step 109, whereby the humidity determination unit 45 determines the humidity level of the H2 airflow. In this example, a humidity sensor is coupled to the output duct 26 to measure the humidity level of the H2 airflow. The humidity sensor sends a signal to the control unit 41 indicating the humidity level of the H2 airflow.

[0131] In another example, a surface level sensor is located in reaction chamber 5 and is arranged to measure the liquid surface level of the reaction mixture in reaction chamber 5. Humidity determination unit 45 determines the humidity level of the H2 gas flow based on the measured surface level (height). The operation of the surface level sensor is further explained in the examples section below.

[0132] Method 101 further includes step 111, in which a signal from humidity determination unit 45 is provided to control unit 41 to control at least one of the internal gas pressure of the reaction chamber and the reaction temperature of the reaction chamber in order to control the humidity level of the H2 gas flow. Therefore, step 111 may include controlling the internal gas pressure of reaction chamber 111a, and may include controlling the reaction temperature of reaction chamber 111b, or may include a combination of steps 111a and 111b. Control unit 41 can determine which of steps 111a and 111b to use in any combination. Specifically, control unit 41 may select steps 111a and 111b based on other desired properties of the H2 gas flow (such as hydrogen production flow rate) and based on properties of the reaction chamber and the reaction mixture (such as the operating temperature of the reaction chamber).

[0133] For example, the internal pressure of the reaction chamber is controlled by pressure valve arrangement 31. Pressure valve arrangement 31 is controlled by control unit 41 to control the actual internal pressure to the target internal pressure when adjustment is required. The target internal pressure of the reaction chamber is determined by control unit 41 and selected to control the humidity level of the H2 airflow.

[0134] Alternatively, the internal pressure of the reaction chamber can be controlled in any other suitable manner to control the humidity level of the H2 gas flow.

[0135] In this example, as indicated above, the reaction temperature of the reaction mixture in reaction chamber 5 is controlled by temperature control arrangement 17. Temperature control arrangement 17 is controlled by control unit 41 to maintain the reaction temperature at a target reaction temperature if adjustment is required. The target reaction temperature of the reaction chamber is determined by control unit 41 and is selected to control the humidity level of the H2 gas flow.

[0136] In this example, step 111b may include step 205, which involves drawing the provided catalyst and formic acid from the reaction chamber 5 via pump 15. Subsequently, during heating and / or cooling step 207, the reaction mixture drawn during step 205 is heated and / or cooled to the target reaction temperature via temperature control arrangement 17. As described, the target reaction temperature is determined by a control unit and selected to control the humidity level of the H2 gas flow.

[0137] Following the heating and / or cooling during step 207, the heated and / or cooled mixture is introduced into the reaction chamber 5 through the inlet opening 9 during step 209. During introduction step 209, the mixture is introduced into the reaction chamber 5 in a predetermined direction having a tangential component T to facilitate agitation of the mixture in the reaction chamber 5 during use. In other words, the mixture is introduced along the reactor wall 7, wherein the introduction direction has a tangential component T.

[0138] Alternatively, the reaction temperature of the reaction mixture can be controlled in any other suitable manner to control the humidity level of the H2 gas stream.

[0139] In a specific example, the reaction mixture within reaction chamber 5 contains a catalyst comprising a complex of the following formula.

[0140] M(L)n(I)

[0141] in,

[0142] M is a metal selected from Ru, Rh, Ir, Pt, Pd and Os, preferably Ru;

[0143] n is in the range of 1 to 4;

[0144] L is a carbene or a ligand containing at least one phosphorus atom, the phosphor atom being bonded to the metal via a complex bond, the phosphorus ligand also containing at least one aromatic group and a hydrophilic group, wherein if n>1, each L can be different from another L;

[0145] The complex of formula (I) may optionally contain other ligands and be provided in the form of salts or neutral.

[0146] exist Figure 5 In the same document, another system 100 is disclosed. System 100 is based on system 1 and includes [the following components / components]. Figure 1 The same components as System 1 shown in the figure. In embodiments, System 100 may or may not have a humidity determination unit 45, a water supply device, and a water vapor control device, as described with respect to System 1.

[0147] The system 100 additionally includes a refrigeration control unit 55 and a water supply device 51 for supplying H2O to the carrier storage unit. The water supply device 51 may be a water storage unit and a valve for controllably supplying water from the water storage unit to the carrier storage unit 35.

[0148] The refrigeration control unit 55 is configured to control the water supply from the water supply device 51 reservoir in response to the measured ambient temperature.

[0149] System 100 may also include an ambient temperature sensor for measuring ambient temperature. In the example, when the ambient temperature drops below a threshold temperature, the refrigeration control unit 55 can select the amount of water supplied by the water supply device 51 to the carrier storage.

[0150] The refrigeration control unit 55 can, for example, calculate, based on a determined volume of the formic acid mixture within the carrier storage 35, how much water needs to be added to the carrier storage 35 to form a formic acid mixture with a sufficient water concentration to prevent the stored formic acid mixture from freezing. The freezing temperature of the formic acid mixture containing water is generally known to those skilled in the art.

[0151] In one embodiment, the refrigeration control unit 55 may be part of the control unit 41.

[0152] In an embodiment, the system 100 further includes a water concentration determination unit for determining the water concentration of a hydrogen carrier composition containing a hydrogen carrier substance and a certain amount of water in the carrier storage 5.

[0153] exist Figures 1 to 5 In each of the disclosed embodiments, systems 1, 100 may additionally include a fuel cell arranged to generate electricity by converting hydrogen, wherein an output conduit 26 is arranged to supply an H2 gas stream from reaction chamber 5 to the fuel cell. The H2 gas stream is maintained at a temperature above the dew point of the H2 gas stream between reaction chamber 5 and the fuel cell to prevent water vapor loss from the H2 gas stream.

[0154] The following non-limiting examples are provided to illustrate the invention.

[0155] Example

[0156] As an example of the present invention in operating system 1, formic acid is supplied from carrier reservoir 35 to reaction chamber 5 at a flow rate of 0.73 l / min. Reaction chamber 5 has a reaction temperature of 95 degrees Celsius and an internal pressure of 12 bar. The reaction temperature of 95 degrees Celsius and the internal pressure of 12 bar determine the water vapor level of the gas above the liquid reaction mixture inside reaction chamber 5. Simultaneously, the flow rate of water vapor leaving the reaction chamber is 2.03 kg / hr (water vapor level at a dew point of 95 degrees Celsius at 12 bar or 39.17 degrees Celsius at 1 bar).

[0157] If reaction chamber 5 contains too much water, such as an excess of 2 liters, then for a certain period of time, the reaction temperature is maintained at 100 degrees Celsius and the internal pressure is maintained at 10 bar to provide a water vapor flow rate of 2.88 kg / hr leaving the reaction chamber (water vapor level or dew point at 100 degrees Celsius at 10 bar, or 46.14 degrees Celsius at 1 bar). The water vapor level is determined by the reaction temperature and internal pressure, provided that sufficient water is present in the reaction mixture to form water vapor in the reaction chamber under the conditions described.

[0158] A little over two hours later, the excess 2 liters of water had been removed from the reaction chamber.

[0159] This estimate is based on calculations of vapor pressure in a gas mixture containing 50% hydrogen and 50% carbon dioxide (each by weight).

[0160] Stabilization conditions

[0161] The relevant factor is the surface liquid level of the reaction mixture within the reaction chamber. This means that if the surface liquid level increases, the amount of water entering the reaction chamber will be higher than the amount leaving. The surface liquid level can be lowered by increasing the reaction temperature or decreasing the internal pressure.

[0162] The stabilization conditions assume that the supply flow rate of formic acid into the reaction chamber is equal to the conversion rate of formic acid under the stated reaction conditions.

[0163] Output value

[0164] For a system that converts formic acid and delivers an H2 gas stream to a fuel cell, the typical output value is:

[0165] <![CDATA[H2 gas flow]]> Minimum value Maximum value airflow 0slpm 1000slpm <![CDATA[H2 output]]> 50% of the volume 50% of the volume Dew point level (1 chin below) 20 degrees Celsius 90 degrees Celsius Temperature 20 degrees Celsius 90 degrees Celsius pressure 3 bars 16 bars

[0166] The dew point level of the H2 gas stream is determined by the reaction temperature and the internal pressure of the reaction chamber.

[0167] Dynamic process

[0168] The primary objective is to achieve a constant surface liquid level (which means a constant volume of water) in the reaction chamber. During startup conditions, the reaction temperature is relatively low.

[0169] Assume a constant water supply is used with a formic acid composition comprising 99 wt% formic acid and 1 wt% water. Therefore, the internal pressure needs to be kept low to prevent the surface liquid level in the reaction chamber from rising above a certain threshold during start-up conditions, and / or the supply flow rate of the formic acid composition needs to be kept low during start-up conditions.

[0170] When the reaction chamber reaches the operating temperature (>60 degrees Celsius), the control unit selects settings to achieve stabilization conditions.

[0171] Monitor the surface liquid level (the horizontal height in the reactor) over time. If it changes over time, for example, if the surface liquid level decreases, the reaction temperature should decrease and the internal pressure should increase. The operating window is between 90 and 110 degrees Celsius, and the internal pressure is between 5 and 16 bar. This allows the system to reach a dew point level between 40 and 90 degrees Celsius (below 1 bar). During delivery to the fuel cell, the temperature of the H2 gas stream to the fuel cell is maintained above the dew point level of the H2 gas stream to prevent any loss of water vapor during delivery to the fuel cell. Preferably, under operating conditions, the H2 gas stream must be maintained at at least 50 degrees Celsius to prevent any loss of water vapor.

[0172] The time required to reach a stable state depends on the degree to which the surface liquid level deviates from the desired surface liquid level. Depending on the volume of the reaction chamber and the start-up conditions (T, p), it can typically take anywhere from a few minutes to several hours.

[0173] Determination of water concentration in H2 gas flow

[0174] This can be achieved by measuring the humidity of the H2 gas stream, for example, before the fuel cell. Humidity sensors are commercially available. Another method to determine the humidity level is by measuring the temperature of the H2 gas stream. This usually gives a good indication of the gas's maximum dew point. If the output is thermally isolated from the reaction chamber, the dew point of the H2 gas stream can be monitored using a simple temperature sensor.

[0175] A preferred method for determining the water concentration of the H2 gas stream is by using the surface level of the reaction mixture within the reaction chamber. A floating element is used to determine the height of the surface level. Alternatively, a radar system can be used to determine the surface level in the reactor. Another option is to use temperature sensors to measure the surface level. A temperature difference exists at the interface between the gas and fluid. This allows multiple temperature sensors to be placed in the walls of the reaction chamber, and the height of the surface level can be measured based on the temperature distribution within the reaction chamber.

[0176] If the surface liquid level remains stable, one can calculate how much water leaves the reaction chamber and, consequently, how much water enters the reaction chamber based on the reaction temperature and internal pressure.

[0177] Freezing point of formic acid composition

[0178] The freezing points (fp) of formic acid compositions containing formic acid and a certain amount of water are shown in the table below:

[0179]

[0180] Table: Freezing Points of Various Formic Acid-Water Mixtures

[0181] The molar fraction of water in a formic acid composition containing formic acid and water can be adjusted according to the measured ambient temperature to prevent the formic acid composition from freezing at the ambient temperature.

[0182] Those skilled in the art will understand that any block diagram herein represents a conceptual diagram of an illustrative unit or module that embodies the principles of the invention.

[0183] Although the principles of the invention have been explained above with reference to specific embodiments, it should be understood that this description is merely illustrative and not intended to limit the scope of protection defined by the appended claims.

Claims

1. A hydrogen generation system configured to generate hydrogen using a hydrogen carrier material, said hydrogen carrier material being liquid at room temperature, said system comprising: A reaction chamber, configured to generate an H2 gas stream by converting the hydrogen carrier material. The reaction chamber includes an inlet arranged for receiving the hydrogen carrier material; An output conduit for discharging the H2 gas stream from the reaction chamber; A liquid level sensor unit is arranged to sense the surface liquid level of the liquid reaction mixture including the hydrogen carrier material in the reaction chamber; A humidity determination unit is arranged to determine the humidity level of the H2 airflow based on a sensed surface liquid level. A water supply device for supplying H2O to the reaction chamber; and A water vapor control device is configured to control the water vapor level in the reaction chamber in response to a determined humidity level, wherein the humidity level is determined by the reaction temperature and internal pressure, provided that sufficient water is present in the liquid reaction mixture to form water vapor in the reaction chamber, and the generated H2 gas stream comprises hydrogen and water vapor.

2. The system according to claim 1, wherein, The water vapor control device is configured to control the water vapor concentration of the H2 gas flow by controlling at least one of the internal air pressure of the reaction chamber and the reaction temperature of the reaction chamber in response to the determined humidity level, so as to affect the evaporation of water in the reaction chamber and control the humidity level of the H2 gas flow.

3. The system according to claim 1 or 2, wherein, The steam control device is configured to control the surface level of the liquid reaction mixture in the reaction chamber to maintain the surface level within a predetermined height range.

4. The system according to claim 1 or 2, wherein, The hydrogen carrier material: Selected from formic acid and methanol and mixtures thereof; or It is a formate.

5. The system according to claim 1 or 2, wherein, The steam control device includes at least one of the following: A pressure control unit for controlling the internal pressure of the reaction chamber; and A temperature control unit is used to control the reaction temperature in the reaction chamber.

6. The system according to claim 5, wherein, The pressure control unit includes a pressure valve disposed at the output duct of the H2 gas flow to control the internal gas pressure of the reaction chamber.

7. The system according to claim 5, wherein, The steam control device includes a central control unit to control at least one of the pressure control unit and the temperature control unit.

8. The system according to any one of claims 1-2 and 6-7, wherein, The water supply device includes a gas supply unit arranged to provide an airflow including water vapor to the reaction chamber.

9. The system according to any one of claims 1-2 and 6-7, wherein, The water supply device includes a water supply unit arranged to provide a liquid flow including water to the reaction chamber.

10. The system according to any one of claims 1-2 and 6-7, wherein, The system includes a carrier storage container for storing a hydrogen carrier composition comprising the hydrogen carrier substance and water, wherein the inlet of the reaction chamber is arranged for receiving the hydrogen carrier composition containing water from the carrier storage container.

11. The system according to any one of claims 1-2 and 6-7, wherein, The system includes a carrier storage unit for storing the hydrogen carrier material, wherein the inlet of the reaction chamber is arranged to receive the hydrogen carrier material from the carrier storage unit.

12. The system according to claim 11, wherein, The hydrogen carrier material has a freezing temperature between 0 and 20 degrees Celsius, and / or the hydrogen generation system further includes a freezing control unit for controlling the water supply to the carrier storage in response to a measured ambient temperature.

13. The system according to claim 12, wherein, The hydrogen generation system also includes conduits for delivering water to the carrier storage.

14. The system according to any one of claims 1-2 and 6-7, comprising a fuel cell, said fuel cell being arranged to generate electrical energy by converting hydrogen, wherein, The output conduit is arranged to supply the H2 gas flow from the reaction chamber to the fuel cell.

15. A method for operating a hydrogen generation system according to any one of claims 1 to 14, the method comprising the steps of: Water and a hydrogen carrier substance are provided in the reaction chamber, the hydrogen carrier substance being liquid at room temperature; The reaction chamber generates an H2 gas stream by converting the hydrogen carrier material. The liquid level sensor unit senses the surface liquid level of the liquid reaction mixture containing the hydrogen carrier material within the reaction chamber; The humidity determination unit determines the humidity level of the H2 airflow based on the sensed surface liquid level; The water vapor control device controls the water vapor level in the reaction chamber in response to the determined humidity level, wherein the humidity level is determined by the reaction temperature and the internal pressure, provided that sufficient water is present in the reaction mixture to form water vapor in the reaction chamber under the conditions described above, and the H2 gas flow comprises hydrogen and water vapor.

16. The method according to claim 15, wherein, The water vapor control step includes controlling at least one of the internal air pressure of the reaction chamber and the reaction temperature within the reaction chamber, in order to affect the evaporation of water from the liquid reaction mixture within the reaction chamber and thereby control the humidity level of the H2 gas flow.

17. The method according to claim 16, wherein, The water vapor control device controls the humidity level of the H2 airflow within the target vapor concentration range.

18. The method according to claim 17, wherein, The target vapor concentration range is a dew point range of -70°C to 100°C at 1 bar, or a dew point range of 30°C to 60°C at 1 bar.

19. The method according to claim 15 or 16, further comprising the steam control device controlling the surface level of the liquid reaction mixture in the reaction chamber to maintain the surface level within a predetermined height range.

20. The method according to claim 15 or 16, wherein, The hydrogen carrier material: Selected from formic acid and methanol and mixtures thereof; or It is a formate.

21. The method according to any one of claims 15-18, comprising the following steps: The fuel cell generates electricity by converting hydrogen supplied to the fuel cell by the H2 gas stream.

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