Hydrogen generation power system for producing electricity from hydrogen using a hydrogen carrier material, and method of operating the hydrogen generation power system

Abstract

1. A hydrogen generation power system for producing electrical power from hydrogen using a hydrogen carrier material, comprising: a reaction chamber arranged to generate an H gas stream by converting the hydrogen carrier material, the reaction chamber having an inlet arranged to receive the hydrogen carrier material and an output conduit for outputting the H gas stream; and a fuel cell arranged to produce electrical energy by converting hydrogen, the output conduit being arranged to supply the H gas stream from the reaction chamber to the fuel cell, the system further comprising: a humidity determining unit arranged to determine a humidity level of the H gas stream; water providing means for providing H O to the reaction chamber; and water vapor control means arranged to control the water vapor level in the reaction chamber in response to the determined humidity level, wherein the generated H gas stream comprises hydrogen and water vapor.

Description

[Technical Field]

[0001] The field of the invention relates to hydrogen generation power systems that use hydrogen carrier materials to produce electricity from hydrogen. The field of the invention further relates to methods of operating hydrogen generation power systems according to the invention. [Background technology]

[0002] Hydrogen generation power systems that produce hydrogen using a hydrogen carrier material are commonly known. The hydrogen carrier material can be a liquid hydrogen carrier material, such as methanol or formic acid. The hydrogen generation system includes a carrier reservoir for storing the hydrogen carrier material and a reaction chamber configured to convert the hydrogen carrier material to produce an H gas stream, the H gas stream containing hydrogen. The reaction chamber includes an inlet configured to receive the hydrogen carrier material from the carrier reservoir. The system further includes an output conduit for outputting the H gas stream from the reaction chamber. When formic acid is converted in the reaction chamber, an H gas stream containing hydrogen gas and carbon dioxide gas is produced.

[0003] Optionally, the output conduit of the hydrogen generation system can be directly coupled to a fuel cell configured to produce electrical energy by converting hydrogen, and the output conduit provides a flow of H gas from the reaction chamber to the fuel cell.

[0004] Generally, fuel cells require a specific desired humidity level within them to operate effectively. Fuel cells produce electricity by converting hydrogen gas and additional oxygen gas within the fuel cell, forming water, according to the reaction scheme H + 2O → 2H O.

[0005] The output (gas) stream of a fuel cell contains water in the gas phase, and the output gas stream is used (at least in part) and returned to the inlet of the fuel cell to maintain the humidity level within the fuel cell at a desired humidity level. Typically, the output gas stream also contains residual hydrogen and / or oxygen that was not converted within the fuel cell. Before introducing the steam into the fuel cell, it is necessary to separate the steam component from the output gas stream from the hydrogen and / or oxygen remaining in the output gas stream. To separate the steam, a Nafion membrane is used, which is a relatively expensive component. Furthermore, there is limited control over the rate of steam transport through the Nafion membrane to the fuel cell.

[0006] It would further be desirable to provide a system for producing electrical power from hydrogen using a hydrogen carrier material, which system allows for easy control of both the hydrogen content and water (or steam) level of the gas stream. Summary of the Invention

[0007] According to a first aspect of the present invention, there is provided a hydrogen generation and power system for producing electrical power from hydrogen using a hydrogen carrier material, the system comprising: a reaction chamber configured to produce a stream of H gas by converting a hydrogen carrier material, The reaction chamber includes an inlet positioned to receive a hydrogen carrier material; an output conduit for outputting a flow of H2 gas from the reaction chamber; a fuel cell arranged to produce electrical energy by converting hydrogen; an output conduit positioned to deliver a flow of H2 gas from the reaction chamber to the fuel cell; The system is a humidity determination unit arranged to determine the humidity level of the H2 gas stream; water providing means for providing H2O to the reaction chamber; water vapor control means arranged to control the water vapor level within the reaction chamber in response to the determined humidity level; The produced H2 gas stream contains hydrogen and water vapor.

[0008] According to another aspect of the present invention, there is provided a method of operating a hydrogen generation power system according to the present invention, the method comprising: receiving a hydrogen carrier material in a reaction chamber; receiving water in a reaction chamber; a reaction chamber generating a H2 gas stream by converting a hydrogen carrier material, the H2 gas stream comprising hydrogen and water vapor; a humidity determination unit determining a humidity level of the H2 gas flow; a water vapor control means for controlling the water vapor level within the reaction chamber in response to the determined humidity level; The fuel cell produces electrical energy by converting hydrogen supplied to the fuel cell by the H2 gas stream.

[0009] The hydrogen generation power system of the present invention has the advantage that an H2 gas stream can be produced by a system containing hydrogen and a water vapor concentration suitably controlled for fuel cell use. The water vapor concentration can be suitably controlled within a target water vapor concentration range by the hydrogen generation system. The hydrogen generation system can control the formation of hydrogen by converting a hydrogen carrier material, thereby controlling the hydrogen concentration in the H2 gas stream. Water is provided into the reaction chamber by a water providing means. The water vapor control means is arranged to control the water vapor level in the reaction chamber in response to the determined humidity level. The water vapor level in the reaction chamber determines the humidity level of the H2 gas stream.

[0010] In an embodiment, the water vapor control means controls the water vapor concentration of the H gas stream by suitably controlling at least one of the internal gas pressure of the reaction chamber and the reaction temperature of the reaction chamber. The internal gas pressure of the reaction chamber and the reaction temperature of the reaction chamber affect the water evaporation process within the reaction chamber, thereby controlling the water vapor concentration of the H gas stream exiting the reaction chamber. The reaction temperature is the temperature within the reaction chamber at which hydrogen gas is formed.

[0011] In one embodiment, the water vapor control means is arranged to control the humidity level of the H2 stream within a target vapor concentration range. In a preferred embodiment, the target vapor concentration range is selected for the fuel cell.

[0012] In one embodiment, the hydrogen carrier material is a liquid at room temperature.

[0013] In certain embodiments, the hydrogen carrier material is selected from formic acid and methanol, and mixtures thereof. In a preferred embodiment, the hydrogen carrier material is formic acid.

[0014] In one embodiment, the hydrogen production system further comprises a fuel cell arranged to produce electrical energy by converting hydrogen, and an output conduit arranged to supply a flow of H gas from the reaction chamber to the fuel cell.

[0015] In one embodiment, the water vapor control means comprises: a pressure control unit for controlling the internal gas pressure of the reaction chamber; and a temperature control unit for controlling the reaction temperature of the reaction chamber.

[0016] In one embodiment, the water vapor control means comprises a central control unit for controlling said at least one of the pressure control unit and the temperature control unit.

[0017] In one embodiment, the pressure control unit comprises a pressure valve disposed in the output conduit of the H2 gas flow to control the internal gas pressure of the reaction chamber.

[0018] In one embodiment, the water providing means comprises: a gas supply unit arranged to provide a gas flow comprising water vapor to the reaction chamber; a water supply unit arranged to provide a liquid flow comprising water to the reaction chamber; The system includes a carrier reservoir for storing a hydrogen carrier composition comprising a hydrogen carrier material and water, and the inlet of the reaction chamber is positioned to receive the hydrogen carrier composition comprising water from the carrier reservoir.

[0019] In certain embodiments, the water providing means is a combination of at least two of a gas supply unit, a water supply unit, and a hydrogen carrier composition disposed in a carrier reservoir, the hydrogen carrier composition including a certain amount of water in addition to a hydrogen carrier material.

[0020] In one embodiment, the hydrogen carrier material is liquid at room temperature, and the water vapor control means is configured to control the surface level of the reaction mixture in the reaction chamber. Specifically, the water vapor control means controls the surface level of the reaction mixture to maintain the surface level within a predetermined height range. In this way, overflow of the reaction chamber can be prevented. The water vapor control means 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 level within the predetermined height range.

[0021] In one embodiment, the H gas stream comprises hydrogen and water vapor. The H gas stream may further contain other reaction products. In one example, as formic acid is converted, carbon dioxide is also formed and exits the reaction chamber in the H gas stream.

[0022] In one embodiment, the humidity determining unit comprises: a sensor disposed in an output conduit of the H2 flow; a level sensor unit arranged to sense a surface level of the liquid reaction mixture containing the hydrogen carrier material in the reaction chamber, and a humidity determination unit arranged to calculate the humidity level based on the measured surface level.

[0023] The liquid reaction mixture comprises a hydrogen-carrying material and water. In certain embodiments, the liquid reaction mixture may further comprise a catalyst to catalyze the conversion reaction of the hydrogen-carrying material.

[0024] In one embodiment, the humidity determining unit can determine the humidity level based on a known supply of liquid hydrogen carrier material and water to the reaction chamber while the surface level is held substantially constant.

[0025] In another embodiment, the humidity determination unit can determine the humidity level based on a known exit rate of the H gas flow with hydrogen gas containing water vapor from the reaction chamber while the surface level is held substantially constant.

[0026] In one embodiment, the humidity determining unit is arranged to provide a signal indicative of the humidity level to the water vapour control means.

[0027] In one embodiment, the system includes a carrier reservoir for storing a hydrogen carrier material, and the inlet of the reaction chamber is positioned to receive the hydrogen carrier material from the carrier reservoir.

[0028] In one embodiment, the hydrogen carrier substance has a freezing temperature of 0-20° C. Preferably, the hydrogen carrier substance is formic acid.

[0029] In certain embodiments, the hydrogen generation system further comprises a freeze control unit for controlling the water supply to the carrier reservoir in response to the measured ambient temperature.

[0030] In one embodiment, the hydrogen generation system further comprises a conduit for delivering a water supply to the carrier reservoir.

[0031] In one embodiment, the hydrogen production system further comprises a temperature sensor positioned to measure the ambient temperature.

[0032] In one embodiment, the hydrogen generation system further comprises a water concentration determining unit for determining the water concentration of a hydrogen carrier composition in the carrier reservoir, the hydrogen carrier composition including a hydrogen carrier material and an amount of water.

[0033] In one embodiment, the water concentration determination unit may be a sensor for sensing the water concentration of the hydrogen carrier composition, or may be an input device for receiving a signal indicative of the water concentration of the hydrogen carrier composition, such as by an input signal provided by an operator of the system.

[0034] In one embodiment, the step of controlling the water vapor includes controlling at least one of an internal gas pressure of the reaction chamber and a reaction temperature of the reaction chamber to control the humidity level of the H2 gas flow.

[0035] In one embodiment, the water vapor control means controls the humidity level of the H2 gas stream within a target vapor concentration range.

[0036] In one embodiment, the target vapor concentration range is a dew point range of -70°C to 100°C at 1 bar. Preferably, the target vapor concentration range is a dew point range of 0°C to 80°C at 1 bar, more preferably a dew point range of 30°C to 60°C at 1 bar.

[0037] In one embodiment, the hydrogen production system further includes a fuel cell, and the method further includes the step of the fuel cell producing electrical energy by converting hydrogen supplied to the fuel cell by the H2 gas stream.

[0038] In one embodiment, if the humidity level of the H2 gas stream is lower than the target vapor concentration range, the internal gas pressure is reduced and / or the reaction temperature is increased, and if the humidity level of the H2 gas stream is higher than the target vapor concentration range, the internal gas pressure is increased and / or the reaction temperature is reduced.

[0039] In one 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 transport to the fuel cell, thereby preventing loss of water vapor during transport to the fuel cell.

[0040] In one embodiment, the reaction mixture is an aqueous solution comprising a formate salt.

[0041] In one embodiment, the reaction mixture further comprises a catalyst.

[0042] In certain embodiments, the catalyst is M(L)n (I) and a complex of the formula: M is a metal selected from Ru, Rh, Ir, Pt, Pd, and Os, preferably Ru; n is in the range of 1 to 4; L is a carbene or a ligand comprising at least one phosphorus atom, the phosphorus atom being bound to the metal by a complex bond, the phosphorus ligand further comprising at least an aromatic group and a hydrophilic group, and when n>1, each L may be different from another L; The complexes of formula (I) optionally contain other ligands and may be provided in salt form or may be neutral.

[0043] In an embodiment, the reaction temperature range of the reaction chamber is 20 to 200°C and / or the internal pressure of the reaction chamber is in the range of 1 to 1200 bar. Preferably, the reaction temperature range is 40 to 150°C.

[0044] Preferably, the hydrogen partial pressure is in the range of 0.5 to 600 bar.

[0045] Optionally, the partial pressure of the carbon dioxide is in the range of 0.5 to 600 bar.

[0046] Preferably, the total internal gas pressure in the reaction chamber is in the range of 0.1 to 16 bar.

[0047] In another aspect of the present invention, a hydrogen generation system for producing hydrogen using a hydrogen carrier material is provided, the system comprising: a reaction chamber configured to produce a stream of H gas by converting a hydrogen carrier material, The reaction chamber includes an inlet positioned to receive a hydrogen carrier material; an output conduit for outputting a flow of H gas from the reaction chamber; The system is a humidity determination unit arranged to determine the humidity level of the H2 gas stream; water providing means for providing H2O to the reaction chamber; water vapor control means arranged to control the water vapor level within the reaction chamber in response to the determined humidity level; the produced H2 gas stream comprises hydrogen and water vapor; The H2 gas stream is suitable for fueling a fuel cell.

[0048] In another aspect of the present invention, there is provided a method of operating a hydrogen production system according to the present invention, the method comprising: receiving a hydrogen carrier material in a reaction chamber; receiving water in a reaction chamber; a reaction chamber generating a H2 gas stream by converting a hydrogen carrier material, the H2 gas stream comprising hydrogen and water vapor; a humidity determination unit determining a humidity level of the H2 gas flow; and a water vapor control means for controlling the water vapor level within the reaction chamber in response to the determined humidity level; The H2 gas stream is suitable for fueling a fuel cell.

[0049] In another aspect of the present disclosure, a hydrogen generation system is provided that produces hydrogen using a hydrogen carrier material, the system comprising: a carrier reservoir for storing a hydrogen carrier material; a reaction chamber configured to generate a H2 gas stream by converting a hydrogen carrier material, the H2 gas stream comprising hydrogen, the reaction chamber having an inlet configured to receive the hydrogen carrier material from a carrier reservoir; an output conduit for outputting a flow of H gas from the reaction chamber; The system is a water supply means for supplying H2O to the carrier reservoir; and a freeze control unit arranged to control the supply of water by the water supply means to the carrier reservoir in response to the measured ambient temperature.

[0050] The freeze control unit controls the supply of water to the carrier reservoir by the water supply means to prevent or limit freezing of the hydrogen carrier material in the carrier reservoir. When the measured ambient temperature drops, such as below a predetermined threshold, the freeze control unit can control the supply of water to the carrier reservoir by the water supply means 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.

[0051] In an embodiment, the hydrogen carrier substance has a freezing temperature of 0 to 20° C. Preferably, the hydrogen carrier substance is formic acid.

[0052] In certain embodiments, the hydrogen generation system further comprises a freeze control unit for controlling the water supply to the carrier reservoir in response to the measured ambient temperature.

[0053] In one embodiment, the hydrogen generation system further comprises a conduit for delivering a water supply to the carrier reservoir.

[0054] In one embodiment, the hydrogen production system further comprises a temperature sensor positioned to measure the ambient temperature.

[0055] In one embodiment, the hydrogen generation system further comprises a water concentration determining unit for determining the water concentration of a hydrogen carrier composition in the carrier reservoir, the hydrogen carrier composition including a hydrogen carrier material and an amount of water.

[0056] In one embodiment, the water concentration determination unit may be a sensor for sensing the water concentration of the hydrogen carrier composition, or may be an input device for receiving a signal indicative of the water concentration of the hydrogen carrier composition, such as by an input signal provided by an operator of the system. [Brief explanation of the drawings]

[0057] The accompanying drawings are used to illustrate presently preferred, non-limiting, exemplary embodiments of the device of the present invention. These and other advantages of the features and objects of the present invention will become more apparent and the invention will be better understood from the following detailed description when read in conjunction with the accompanying drawings.

[0058] [Figure 1] 1 illustrates a system according to the present disclosure. [Figure 2] The elements of the system in Figure 1 are shown. [Figure 3] 2 shows a top view of the elements of the system of FIG. 1. [Figure 4A-4B] 1 illustrates a method according to the present disclosure. [Figure 5] 1 illustrates another system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0059] System 1 is configured to produce hydrogen by dehydrogenation of formic acid. System 1 includes a reaction vessel 3, an inlet conduit 13, a pump 15, and a temperature control device 17. Reaction vessel 3 includes a reaction chamber 5 surrounded by a reactor wall 7. Reactor wall 7 includes a lower wall 27 and an upper wall 23. Upper wall 23 includes a gas outlet 25 for allowing hydrogen from a reaction mixture containing formic acid and a catalyst to exit reaction chamber 5 via gas outlet 25. The output of hydrogen from reaction chamber 5 can be limited by a pressure valve device 31. Pressure valve device 31 is configured to control the internal pressure of reaction chamber 5 by controllably allowing hydrogen gas flow originating from reaction chamber 5 to pass through pressure valve device 31. Lower wall 27 includes a mixture outlet 11 located at the center of the bottom of reaction vessel 3.

[0060] Reaction vessel 3 is positioned to hold a reaction mixture of catalyst, formic acid, and water in reaction chamber 5. Reaction vessel 3 includes a mixture inlet 9 for allowing the reaction mixture to enter reaction chamber 5 via mixture inlet 9. In reaction chamber 5, a fixed flow organ 29 is provided at or near reactor wall 7. Flow organ 29 extends along substantially the entire height of reaction chamber 5. In one embodiment of system 1, it is contemplated that the flow organ extends along only the lower half of the height of reaction chamber 5.

[0061] The reaction vessel 3 is provided with a further inlet 21 arranged for introducing formic acid from a carrier reservoir 35 into the reaction vessel 3 to form a reaction mixture. The carrier reservoir 35 is coupled for fluid flow to the reaction chamber 5 via a further pump 37. The further pump 37 is arranged to pump formic acid from the carrier reservoir 35 into the reaction chamber 5.

[0062] Reactor wall 7 comprises plastic coated on the side facing reaction chamber 5 with polytetrafluoroethylene to insulate reaction vessel 13 and protect the reaction mixture from the plastic of reactor wall 7, which may degrade catalyst present in reaction chamber 5. Reactor wall 7 further comprises replaceable wall element 33. Replaceable wall element 33 comprises metal to locally reinforce reactor wall 7. Replaceable wall element 33 is coated on the side facing reaction chamber 5 with polytetrafluoroethylene to insulate reaction vessel 13 and protect the reaction mixture from the metal of replaceable wall element 33, which may degrade catalyst present in reaction chamber 5. In one embodiment of system 1, it is contemplated that the reactor wall is locally reinforced with fixed wall elements in addition to, or as an alternative to, replaceable wall element 33.

[0063] An inlet conduit 13 is communicatively coupled for fluid flow to the reaction chamber 5 via the mixture inlet 9. The inlet conduit 13 is arranged such that the reaction mixture in use is introduced into the reaction chamber 5 via the mixture inlet 9 in a predetermined direction having a tangential component T of the agitation 39 of the mixture in use in the reaction chamber 5. In other words, the reaction mixture is introduced in a direction along the reactor wall 7, the introduction direction having a tangential component T.

[0064] Pump 15 is fluidly coupled for fluid flow to reaction chamber 5 via mixture inlet 9 and mixture outlet 11. Pump 15 is positioned to withdraw mixture from reaction chamber 5 via mixture outlet 11 and introduce mixture into reaction chamber 5 via inlet conduit 13 and inlet 9.

[0065] A temperature controller 17 is fluidly coupled to the pump 15 for fluid flow and is arranged to heat and / or cool the reaction mixture withdrawn from the reaction chamber 5. The temperature controller 17 is further arranged to cool and / or heat a portion of the reaction mixture exiting the temperature controller 17 to a predetermined temperature in the range of 70-150°C prior to introducing the portion of the reaction mixture into the reaction chamber 5 via the inlet conduit 13.

[0066] The system 1 comprises a control unit 41, a measurement unit 43, and a humidity determination unit 45. The control unit 41 is communicatively coupled to the temperature controller 17, the pump 15, and the measurement unit 43. The control unit 41 is arranged to control the temperature controller 17 and the pump 15 in response to the temperature of the reaction mixture in use present in the reaction chamber 5 and / or the temperature controller 17, as measured by the measurement unit 43.

[0067] The system 1 further comprises water providing means for providing HO to the reaction chamber 5. The water providing means may be embodied as a gas supply unit arranged to provide a gas flow comprising water vapor to the reaction chamber 5. The water providing means may be embodied as a water supply unit arranged to provide a liquid flow comprising water to the reaction chamber 5. The control unit 41 is arranged to control the gas supply unit and / or the water supply unit to controllably supply water to the reaction chamber 5.

[0068] Alternatively or additionally, the carrier reservoir 35 of the system 1 stores a formic acid composition containing formic acid and water at a specific concentration. The supply of the formic acid composition containing water to the reaction chamber 5 is used as a water providing means. Therefore, by controlling the pump 37, the supply of formic acid and the supply of water to the reaction chamber 5 are controlled.

[0069] The system 1 further comprises a water vapor control means arranged to control the water vapor level in the reaction chamber in response to the determined humidity level. The water vapor control means may comprise a pressure valve device 31 for controlling the internal gas pressure of the reaction chamber, and a temperature controller 17 for controlling the reaction temperature of the reaction chamber. In particular, the water vapor control means further comprises a control unit 41 for controlling the pressure valve device 31, and the temperature controller 17 for controlling the water vapor level in the reaction chamber.

[0070] Method 101 is configured for hydrogen production by converting a hydrogen carrier material, such as by dehydrogenation of formic acid. Method 101 includes providing the formic acid 103 to the reaction chamber 5. Additionally, method 101 includes providing water 105 to the reaction chamber 5.

[0071] In one embodiment of method 101, providing the water 105 and the formic acid 103 may be performed simultaneously in step 104 when the formic acid stream is a formic acid mixture containing formic acid and a predetermined concentration of water. In an alternative or additional embodiment of method 101, providing the water may be performed in step 105 independently of providing the formic acid 103 to the reaction chamber 5.

[0072] In other words, formic acid and water can be provided to the reaction chamber 5 during different steps to allow the formic acid 103 and the water 105 to be stored separately and fed independently to the reaction chamber 5.

[0073] The step of supplying water 105 may be embodied by a gas supply unit that supplies a gas flow containing water vapor to the reaction chamber, or by a water supply unit that supplies a liquid flow containing water to the reaction chamber. In certain embodiments, both the gas supply unit and the water supply unit may be used to supply water to the reaction chamber 5.

[0074] In another embodiment, the step of providing water 105 can be combined with the step of providing water to the formic acid stream 104.

[0075] The method 101 further includes a step 107 of converting the hydrogen carrier material, such as by dehydrogenating formic acid, thereby forming a gas stream containing hydrogen. The H gas stream exits the reaction space 5 via a gas outlet 25 into an output conduit 26.

[0076] The method 101 further includes a step 109 of determining, by the humidity determination unit 45, a humidity level of the H2 gas flow. In one embodiment, a humidity sensor is coupled to the output conduit 26 to measure the humidity level of the H2 gas flow. The humidity sensor sends a signal to the control unit 41 indicative of the humidity level of the H2 gas flow.

[0077] In another embodiment, a surface level sensor is provided in the reaction chamber 5 and positioned to measure the liquid level of the reaction mixture within the reaction chamber 5. The humidity determination unit 45 determines the humidity level of the H gas stream based on the measured surface level (height). The operation of the surface level sensor is further described in the Examples section below.

[0078] The method 101 further includes step 111 of controlling at least one of the internal gas pressure of the reaction chamber and the reaction temperature of the reaction chamber in response to a signal from the humidity determination unit 45 provided to the control unit 41 to control the humidity level of the H gas flow. Thus, step 111 may include controlling the internal gas pressure of the reaction chamber 111a and controlling the reaction temperature of the reaction chamber 111b, or may include a combination of steps 111a and 111b. The control unit 41 may determine which of steps 111a and 111b to use in any combination. Specifically, the control unit 41 may select steps 111a and 111b depending on other desired attributes of the H gas flow, such as the hydrogen production flow rate, and attributes of the reaction chamber and the reaction mixture, such as the operating temperature of the reaction chamber.

[0079] In one embodiment, the internal gas pressure of the reaction chamber is controlled by a pressure valve device 31. The pressure valve device 31 is controlled by a control unit 41 to control the actual internal gas pressure, if adjustment is necessary, to a target internal gas pressure. The target internal gas pressure of the reaction chamber is determined by the control unit 41 and selected to control the humidity level of the H gas flow.

[0080] Alternatively, the internal gas pressure of the reaction chamber can be controlled in any other suitable manner to control the humidity level of the H2 gas stream.

[0081] In one embodiment, the reaction temperature of the reaction mixture in reaction chamber 5 is controlled by temperature controller 17, as described above. Temperature controller 17 is controlled by control unit 41 to control the reaction temperature, if adjustment is necessary, to a target reaction temperature. The target reaction temperature of the reaction chamber is determined by control unit 41 and selected to control the humidity level of the H gas stream.

[0082] In this embodiment, step 111b may include step 205 of withdrawing the provided catalyst and the formic acid from the reaction chamber 5 by the pump 15. The reaction mixture withdrawn during step 205 is then heated and / or cooled by the temperature controller 17 during step 207 of heating and / or cooling to the target reaction temperature. As previously mentioned, the target reaction temperature is determined by a control unit and selected to control the humidity level of the H gas stream.

[0083] After the heating and / or cooling in step 207, the heated and / or cooled mixture is introduced into the reaction chamber 5 via the inlet 9 in step 209. During the introducing step 209, the mixture is introduced into the reaction chamber 5 in a predetermined direction having a tangential component T of the agitation 39 of the mixture in use in the reaction chamber 5. In other words, the mixture is introduced in a direction along the reactor wall 7, the introduction direction having a tangential component T.

[0084] Alternatively, the reaction temperature of the reaction mixture may be controlled in any other suitable manner to control the humidity level of the H2 gas stream.

[0085] In certain embodiments, the reaction mixture in reaction chamber 5 comprises: M(L)n (I) The catalyst includes a complex of the formula: M is a metal selected from Ru, Rh, Ir, Pt, Pd, and Os, preferably Ru; n is in the range of 1 to 4; L is a carbene, i.e., a ligand containing at least one phosphorus atom, which is bound to the metal by a complex bond, the phosphorus ligand further containing at least an aromatic group and a hydrophilic group, and when n>1, each L may be different from another L; The complexes of formula (I) optionally contain other ligands and may be provided in salt form or may be neutral.

[0086] 5, another system 100 is disclosed. System 100 is based on system 1 and includes the same components as system 1 shown in FIG. 1. In an embodiment, system 100 may or may not include the humidity determining unit 45, water providing means, and water vapor control means as described with respect to system 1.

[0087] The system 100 further comprises a freeze control unit 55 and a water supply means 51 for supplying H2O to the carrier reservoir 35. The water supply means 51 may be a water reservoir and a valve for controllably supplying water from the water reservoir to the carrier reservoir 35.

[0088] The freezing control unit 55 is arranged to control the supply of water by the water supply means 51 to the carrier reservoir in response to the measured ambient temperature.

[0089] The system 100 may further comprise an ambient temperature sensor for measuring the ambient temperature. In one embodiment, if the ambient temperature drops below a threshold temperature, the freeze control unit 55 may select the amount of water to be supplied to the carrier reservoir by the water supply means 51.

[0090] The freezing control unit 55 can calculate, for example, based on the determined volume of formic acid mixture in the carrier reservoir 35, how much water needs to be added to the carrier reservoir 35 to form a formic acid mixture having a water concentration sufficient to prevent freezing of the stored formic acid mixture. The freezing temperature of a formic acid mixture containing water is commonly known to those skilled in the art.

[0091] In an embodiment, the freeze control unit 55 may be part of the control unit 41 .

[0092] In an embodiment, the system 100 further comprises a water concentration determining unit for determining the water concentration of the hydrogen carrier composition in the carrier reservoir 5, which contains a hydrogen carrier material and an amount of water.

[0093] 1-5, the system 1, 100 may further include a fuel cell arranged to produce electrical energy by converting hydrogen, and an output conduit 26 is arranged to supply the H2 gas stream from the 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 the reaction chamber 5 and the fuel cell to prevent loss of water vapor from the H2 gas stream.

[0094] The following non-limiting examples are provided to illustrate the present invention. [Example]

[0095] As an example of the present invention for operating system 1, formic acid is fed 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° C. and an internal pressure of 12 bar. The reaction temperature of 95° C. and internal pressure of 12 bar determine the water vapor level of the gas above the liquid reaction mixture in reaction chamber 5. At the same time, the flow rate of water vapor exiting the reaction chamber is 2.03 kg / hr (at a water vapor level of 95° C. dew point at 12 bar, or 39.17° C. dew point at 1 bar).

[0096] If the reaction chamber 5 contains excess water, such as 2 liters of excess water, the reaction temperature is maintained at 100°C and the internal pressure at 10 bar for a period of time to provide a flow rate of 2.88 kg / hr of water vapor exiting the reaction chamber (at a water vapor level, i.e., a dew point of 100°C at 10 bar, or a dew point of 46.14°C at 1 bar). The water vapor level is determined by the reaction temperature and internal pressure, provided that there is sufficient water in the reaction mixture to form water vapor within the reaction chamber at those conditions.

[0097] After just over two hours, 2 liters of excess water was removed from the reaction chamber.

[0098] This estimate is based on calculations of the vapor pressure of a gas mixture containing hydrogen gas and carbon dioxide gas (50% by weight of each).

[0099] Steady state What is relevant is the surface level of the reaction mixture inside the reaction chamber. This means that if the surface level rises, the amount of water entering the reaction chamber is greater than the amount of water leaving the reaction chamber. The surface level can be lowered by increasing the reaction temperature or reducing the internal pressure.

[0100] Steady state assumes that the feed rate of formic acid to the reaction chamber is equal to the conversion rate of formic acid at the reaction conditions.

[0101] Output Value For a system that converts formic acid and delivers a H2 gas stream to a fuel cell, typical system output values ​​are shown below. [Table 1]

[0102] The dew point level of the H2 gas stream is determined by the reaction temperature and the internal pressure of the reaction chamber.

[0103] Dynamic Processes The first goal is to achieve a constant surface level (meaning a constant amount of water) in the reaction chamber. During start-up conditions, the reaction temperature is relatively low.

[0104] Using a formic acid composition having 99% by weight formic acid and 1% by weight water, assuming a constant water supply, the internal pressure must be kept low and / or the feed flow rate of the formic acid composition is kept low during start-up conditions to prevent the surface level within the reaction chamber from rising above a certain threshold during start-up conditions.

[0105] Once the reaction chamber reaches operating temperature (>60° C.), the control unit selects a set point to achieve steady state.

[0106] The surface level (height of the water level inside the reactor) is monitored over time. If it changes over time, for example, if the surface level decreases, the reaction temperature must be lowered and the internal pressure must be increased. The operating range is 90-110°C with an internal pressure of 5-16 bar (gauge pressure). This allows the system to reach a dew point level between 40-90°C (1 bar). The temperature of the H2 gas stream to the fuel cell is maintained above the dew point level of the H2 gas stream during transport to the fuel cell to prevent water vapor loss during transport to the fuel cell. Preferably, the H2 gas stream should be kept at at least 50°C under operating conditions to prevent water vapor loss.

[0107] The time it takes to reach steady state depends on how far the surface level deviates from the desired surface level, and can typically take from a few minutes to a few hours depending on the volume of the reaction chamber and the starting conditions of the reaction chamber (T, p).

[0108] Determining water concentration in H2 gas stream This can be achieved, for example, by measuring the humidity in the H2 gas stream before the fuel cell. Humidity sensors are commercially available. Another way to determine the humidity level is to measure the temperature of the H2 gas stream. This is usually a good indication of the maximum dew point of the gas. If the output is thermally isolated from the reaction chamber, the dew point of the H2 gas stream can be monitored with a simple temperature sensor.

[0109] A preferred method for determining the water concentration in the H2 gas stream is to determine the surface level of the reaction mixture in the reaction chamber. A float 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 a temperature sensor to measure the surface level. A temperature difference exists at the gas-fluid interface. This allows multiple temperature sensors to be placed on the walls of the reaction chamber, and the height of the surface level can be determined based on the temperature distribution in the reaction chamber.

[0110] If the surface level remains stable, the amount of water leaving and entering the reaction chamber can be calculated based on the reaction temperature and internal pressure.

[0111] Freezing point of formic acid composition The freezing points fp of formic acid compositions containing formic acid and an amount of water are shown in the table below. [Table 2]

[0112] Depending on the measured ambient temperature, the mole fraction of water in a formic acid composition containing formic acid and water can be adjusted to prevent freezing of the formic acid composition at the ambient temperature.

[0113] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative units or modules embodying the principles of the invention.

[0114] While the principles of the present invention have been described above in connection with specific embodiments, it should be understood that this description is made by way of example only and does not limit the scope of protection determined by the appended claims.

Claims

1. A hydrogen generation system configured to produce hydrogen using a hydrogen carrier material that is liquid at room temperature, the system comprising: By converting the hydrogen carrier material, H ２ a reaction chamber configured to generate a gas stream, the reaction chamber including an inlet configured to receive the hydrogen carrier material; The reaction chamber ２ an output conduit for outputting the gas flow; optionally a fuel cell arranged to produce electrical energy by converting hydrogen, said output conduit arranged to supply said H2 gas stream from said reaction chamber to said optional fuel cell; a level sensor unit positioned to sense a surface level of a liquid reaction mixture containing the hydrogen carrier material within the reaction chamber; Based on the sensed surface level, ２ a humidity determining unit arranged to determine the humidity level of the gas stream; The reaction chamber is filled with H ２ a water providing means for providing O; water vapor control means configured to control the water vapor level within the reaction chamber in response to the determined humidity level; Equipped with the humidity level is determined by a reaction temperature and an internal gas pressure under conditions where sufficient water is present in the reaction mixture to form water vapor within the reaction chamber; The generated H ２ the gas stream comprises hydrogen and water vapor; system.

2. The water vapor control means ２ 2. The system of claim 1, configured to control the water vapor concentration of the H2 gas stream in response to the determined humidity level to control the humidity level of the gas by controlling at least one of the internal gas pressure of the reaction chamber and the reaction temperature of the reaction chamber to affect evaporation of water in the reaction chamber.

3. A system as described in claim 1 or 2, wherein the water vapor control means 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 hydrogen carrier material is selected from formic acid and methanol, and mixtures thereof; or formic acid or formate, The system according to any one of claims 1 to 3.

5. The water vapor control means a pressure control unit for controlling the internal gas pressure of the reaction chamber, the pressure control unit optionally comprising a pressure valve disposed in the output conduit of the H2 gas flow to control the internal gas pressure of the reaction chamber; a temperature control unit for controlling the reaction temperature in the reaction chamber; and the water vapor control means optionally comprises a central control unit for controlling the at least one of a pressure control unit and a temperature control unit; The system according to any one of claims 1 to 4.

6. a gas supply unit arranged such that the water providing means provides a gas flow comprising water vapor to the reaction chamber; The system according to any one of claims 1 to 5, comprising:

7. A system described in any one of claims 1 to 6, wherein the water providing means comprises a water supply unit arranged to provide a liquid flow containing water to the reaction chamber.

8. A system described in any one of claims 1 to 6, wherein the system comprises a carrier reservoir for storing a hydrogen carrier composition comprising the hydrogen carrier material and water, and the inlet of the reaction chamber is positioned to receive the hydrogen carrier composition comprising water from the carrier reservoir.

9. 9. The system of claim 1, wherein the system comprises a carrier reservoir for storing the hydrogen carrier material, and the inlet of the reaction chamber is positioned to receive the hydrogen carrier material from the carrier reservoir.

10. the hydrogen carrier material has a freezing temperature of 0 to 20°C; and / or the hydrogen generation system further comprising a freeze control unit for controlling water supply to the carrier reservoir in response to a measured ambient temperature. The system of claim 9.

11. The system of claim 10 , wherein the hydrogen production system further comprises a conduit for delivering the water supply to the carrier reservoir.

12. 12. A method for operating a hydrogen production system according to any one of claims 1 to 11, said method comprising: providing a hydrogen carrier material and water that are liquid at room temperature in a reaction chamber; The reaction chamber converts the hydrogen carrier material to produce H ２ generating a gas flow; a level sensor unit sensing a surface level of the liquid reaction mixture containing the hydrogen carrier material in the reaction chamber; A humidity determination unit determines the H based on the sensed surface level. ２ determining a humidity level of the gas stream; a water vapor control means for controlling the water vapor level within the reaction chamber in response to the determined humidity level, the humidity level being determined by a reaction temperature and an internal gas pressure under conditions where sufficient water is present in the reaction mixture to form water vapor within the reaction chamber, and the generated H2 gas stream comprises hydrogen and water vapor; Optionally, the fuel cell comprises: ２ producing electrical energy by converting hydrogen supplied to said fuel cell by a gas stream; A method comprising:

13. The method of claim 12, wherein the step of controlling the water vapor comprises controlling at least one of the internal gas pressure of the reaction chamber and the reaction temperature within the reaction chamber to affect evaporation of water within the reaction chamber, thereby controlling the humidity level of the H2 gas stream; Optionally, the water vapor control means controls the humidity level of the H2 gas stream within a target vapor concentration range. The method of claim 12.

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