Fuel cell system comprising a cleaning apparatus, and method for operating a fuel cell system of this kind
Patent Information
- Application Number
- PCT/EP2026/051133
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-18
- Filing Date
- 2026-01-19
- Publication Date
- 2026-08-27
Smart Images
Figure EP2026051133_27082026_PF_FP_ABST
Abstract
Description
[0001] R.416559
[0002] - 1 -
[0003] Description
[0004] Fuel cell device and method for operating such a fuel cell device
[0005] State of the art
[0006] From WO 2018 / 060439 A1, a fuel cell device with at least one fuel cell unit for the electrochemical conversion of at least one carbon-containing fuel into at least one product fluid and with at least one electrochemical separator arranged downstream of the fuel cell unit for separating the product fluid into at least one end product and at least one oxidizable component has already been proposed.
[0007] Disclosure of the invention
[0008] The invention relates to a fuel cell device with at least one fuel cell unit for the electrochemical conversion of at least one carbon-containing fuel into at least one product fluid and with at least one electrochemical separator arranged downstream of the fuel cell unit for separating the product fluid into at least one end product and at least one oxidizable component.
[0009] It is proposed that the fuel cell device includes a separator control unit for adjusting the residual proportion of the at least one oxidizable component remaining in the at least one end product. The fuel cell device is preferably intended for stationary power generation and preferably has a rated electrical output between 1 kW and 1 GW. The fuel cell unit preferably comprises at least one R.416559
[0010] - 2 -
[0011] Fuel cell, preferably a plurality, in particular more than 100, of identical fuel cells, which are in particular arranged in one or more stacks. The at least one fuel cell is preferably designed as a solid oxide fuel cell, alternatively as a molten carbon fuel cell, as a polymer electrolyte fuel cell, or the like. The at least one fuel cell unit is designed, for example, for the electrochemical conversion of methane, methanol, dimethyl ether, another hydrocarbon, or a hydrocarbon-containing mixture, in particular natural gas or biogas, as fuel. The at least one fuel cell preferably comprises at least one fuel electrode, which is in particular designed as an anode, at least one oxygen electrode, which is in particular designed as a cathode, and at least one intermediate electrolyte.The electrolyte is preferably oxygen-conducting, or alternatively or additionally proton-conducting. The at least one fuel electrode is preferably designed for direct contact with the fuel and for the discharge of the product fluid. The oxygen electrode is preferably designed for direct contact with an oxygen-containing fluid, in particular ambient air and / or an oxygen-containing industrial gas, and for the discharge of an oxygen-side exhaust gas. The product fluid preferably comprises carbon dioxide and / or water as the end product. The product fluid can, for example, include intermediate products such as molecular hydrogen and / or carbon monoxide and / or residual fuel as oxidizable components.
[0012] The electrochemical separator preferably comprises at least one electrochemical cell, and in particular a plurality of electrochemical cells. The at least one electrochemical cell of the electrochemical separator preferably comprises at least one intermediate electrode, which is preferably configured as a cathode, at least one final product electrode, which is preferably configured as an anode, and at least one electrolyte arranged between the electrodes, which is preferably oxygen-conducting. The at least one intermediate electrode and the at least one final product electrode are preferably connected in parallel via a fluid connection to a fluid outlet of the fuel electrode of the at least one fuel cell. The intermediate electrode and the final product electrode can be made of the same material or of different materials. In particular, the R.416559
[0013] - 3 -
[0014] The intermediate product electrode and / or the final product electrode are made of the same material as the fuel electrode of the fuel cell unit. The intermediate product electrode is preferably designed to reduce final products of the product fluid and to discharge (further) oxidizable components of the product fluid. The electrolyte of the electrochemical separator is preferably designed to transfer oxygen from the intermediate product electrode to the final product electrode. The final product electrode is preferably designed to oxidize oxidizable components and convert them into final products. An intermediate product outlet of the intermediate product electrode is preferably connected to a recirculation line of the fuel cell device to feed the oxidizable components back into a fuel supply of the fuel cell device.An end-product outlet of the end-product electrode of the separator is preferably connected to an output unit of the fuel cell device for the output of at least one end product.
[0015] The separator control unit preferably comprises at least one actuator for setting at least one process parameter of the separator and at least one control unit for controlling the actuator. A control unit is understood to be, in particular, a unit with at least one control electronics unit. "Control electronics" is understood to be, in particular, a unit with a processor unit and a memory unit, as well as an operating program stored in the memory unit. The separator control unit particularly preferably includes a voltage control unit for setting an electrical operating voltage of the separator as a process parameter. The electrical operating voltage is preferably the electrical potential difference between the product electrode and the intermediate product electrode. Preferably, the separator control unit also includes a temperature control unit for setting an operating temperature of the separator as a process parameter.Preferably, the separator control unit includes a flow control for setting the operating temperature of the separator and / or a spatial velocity of the product fluid as process parameters. In the simplest case, the voltage control, temperature control, and / or flow control can be configured as an actuator for setting the operating voltage, operating temperature, and / or spatial velocity, or as a subordinate control loop (R.416559).
[0016] - 4 -
[0017] The separator control unit is designed to stabilize the operating voltage, operating temperature, and / or flow velocity specified by the separator control unit. The separator control unit is preferably configured to maintain the residual fraction of at least one oxidizable component at the end-product outlet and / or downstream of the separator below a predetermined threshold by means of voltage control, temperature control, and / or flow control. The separator control unit is preferably configured to maintain the at least one oxidizable component, and in particular all oxidizable components, at the end-product outlet below 5%, preferably below 1%, and in particular below 0.05%, with respect to volume, mass, and / or amount of substance.The separator control unit is preferably designed to adjust the voltage, temperature, and / or flow rate such that an end-product fluid is discharged at the end-product outlet, which consists of at least 99%, preferably at least 99.5%, and particularly preferably at least 99.9% of the at least one end product or of end products, in particular carbon dioxide and / or water, with respect to volume, mass, and / or amount of substance. Preferably, the separator control unit includes at least one sensor for detecting the composition of the end-product fluid discharged at the end-product outlet. The sensor can be configured to detect the concentration of the at least one end product and / or the at least one oxidizable component. In an advantageously cost-effective embodiment, the sensor is configured as a lambda probe to detect the at least one oxidizable component.The sensor can be located at the end product outlet or downstream of the end product outlet. Preferably, the control unit is designed to control the voltage regulation, the temperature regulation, and / or the flow regulation depending on the sensor, and / or to assign a preferred setpoint to the voltage regulation, the temperature regulation, and / or the flow regulation depending on the sensor.
[0018] The term "intended" is to be understood in particular as specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function is to be understood in particular as the object fulfilling and / or executing this specific function in at least one application and / or operating state. R.416559
[0019] - 5 -
[0020] The inventive design allows for advantageously precise control of the separator and achieves an advantageously high purity of at least one end product. In particular, the fuel cell device can isolate the end product for further use and provide it with adjustable purity. Furthermore, advantageously high fuel utilization can be achieved, and in particular, an afterburner can be dispensed with.
[0021] It is further proposed that the fuel cell device includes the aforementioned voltage control to adjust the residual fraction by means of the electrical operating voltage of the electrochemical separator. Preferably, the control unit is designed to increase the operating voltage to reduce the residual fraction below a predetermined maximum threshold. Preferably, the control unit is designed to increase the operating voltage when the residual fraction falls below a predetermined minimum threshold, in order to reduce the electrical power consumed by the at least one electrochemical separator. The minimum and maximum thresholds can be identical or different values.Preferably, a relationship between the operating voltage to be set and the achievable residual fraction, particularly as a function of the operating temperature and / or the velocity of space as parameters, is stored in a memory of the control unit. This relationship can be stored, for example, as a calculation rule, a table, or a characteristic curve, particularly a characteristic map. In a further embodiment, the control unit is designed to optimize, i.e., minimize, the electrical power consumption of the separator for a given residual fraction by determining the electrical current associated with the operating voltage as a function of the mass flow of at least one oxidizable component at a fluid inlet of the end-product electrode and / or the operating temperature. The embodiment according to the invention allows the residual fraction to be set advantageously precisely and, in particular, advantageously energy-efficiently.
[0022] It is further proposed that the at least one fuel cell device should have at least one output connected to the at least one separator-R.416559
[0023] - 6 -
[0024] The output unit comprises the essentially pure output of at least one end product containing at most the residual fraction of the at least one oxidizable component set by the separator control unit. "Essentially pure" shall be understood to mean, in particular, a pure substance with a purity of at least 95%, preferably at least 99%, and most preferably at least 99.5%, based on volume, mass, and / or amount of substance. If the fuel cell device is designed for a fuel in which several end products are contained in the product fluid, the output unit preferably comprises at least two separate output elements, in particular one output element for each end product, in order to output at least one, preferably several, and in particular all, of the end products in an essentially pure form.Alternatively, the output unit comprises at least one output element for the essentially pure output of one of the end products and at least one output element for the output of a mixture of the remaining end products. The output unit preferably comprises at least one output element for the output of at least essentially pure carbon dioxide. For example, the output unit more specifically additionally comprises at least one output element for the output of essentially pure water. The design according to the invention allows the end products of the electrochemical reaction by the fuel cell unit to be advantageously made available for further use.
[0025] It is further proposed that the separator control unit comprise at least one temperature control, in particular the one already mentioned, with at least one separator temperature control element for setting the operating temperature of the electrochemical separator. The separator temperature control element can be arranged directly on the separator, for example in the form of an electric heating element, a heat sink, or the like, or arranged upstream of the separator to temperature-control the separator indirectly via the product fluid. For example, the separator temperature control element is designed as a heat exchanger or as a coolant injection system to temperature-control, and in particular cool, the product fluid upstream of the separator. The coolant injection system is preferably designed to introduce a coolant, in particular liquid water, into the product fluid and to cool it by evaporation. The control unit is preferably designed to R.416559
[0026] - 7 -
[0027] The operating temperature of the separator, particularly in conjunction with temperature control of other components of the fuel cell device, such as the fuel cell unit, a reformer of the fuel cell device, a fluid delivery unit of the fuel cell device, or the like, can be set. The design according to the invention allows the operating temperature to be advantageously set independently of other components of the fuel cell device, particularly the fuel cell unit. In particular, advantageously precise control of the residual proportion of oxidizable components can be achieved.
[0028] Furthermore, it is proposed that the temperature control system includes at least one end-product return line connected to the at least one electrochemical separator for feeding at least a portion of the at least one end product back into the fuel and / or the product fluid. The end-product return line is preferably designed to feed back water as an end product. For example, the end-product return line is connected to the coolant injection to use the water recovered as an end product for cooling the product fluid. Alternatively, the end-product return line is connected to the fuel feed and / or the recirculation line to introduce water, particularly upstream of the reformer, into the fuel, especially for steam reforming, cooling, and / or adjusting the oxygen-carbon ratio of the fuel.The design according to the invention allows the fuel cell device to be operated in a resource-saving manner.
[0029] It is further proposed that the temperature control system comprises at least one heat exchanger as a separator temperature control element, which is arranged fluidically between the fuel cell unit and the at least one electrochemical separator. For clarity, this heat exchanger is hereinafter also referred to as the separator heat exchanger. A primary side of the separator heat exchanger is preferably connected to a fluid outlet of the fuel electrode of the fuel cell unit to cool the product fluid before it enters the separator. Preferably, a secondary side of the separator heat exchanger is connected as a preheater to an oxygen supply.
[0030] - 8 -
[0031] The secondary side is connected to the fuel cell unit. Alternatively, the secondary side is connected as a preheater to a fuel supply to the fuel cell unit or to an external cooling circuit. Preferably, the intermediate product electrode and the end product electrode of the separator are connected in parallel via a fluid outlet of the separator heat exchanger. The temperature control preferably comprises a secondary-side fluid control element, in particular a valve, a pump, a fan, a compressor, or the like, to adjust, and in particular regulate, the operating temperature of the separator via a flow through the separator heat exchanger. The design according to the invention allows for advantageously simple adjustment of the separator's operating temperature.
[0032] Furthermore, it is proposed that the temperature control system comprises at least one heat exchanger arranged downstream of an outlet of the at least one electrochemical separator. Preferably, the temperature control system comprises at least one heat exchanger arranged downstream of an intermediate product outlet of the intermediate product electrode. For clarity, this heat exchanger is hereinafter also referred to as the intermediate product heat exchanger. Preferably, the primary side of the intermediate product heat exchanger is connected to the intermediate product outlet. Preferably, the primary side of the intermediate product heat exchanger is arranged in the recirculation line to cool the portion of the product fluid being recirculated. Preferably, a secondary side of the separator heat exchanger is connected to the oxygen supply to the fuel cell unit as a preheater.Alternatively, the secondary side is connected to the fuel supply to the fuel cell unit to form a recuperator or to an external cooling circuit. The temperature control preferably comprises a secondary-side fluid control element, in particular a valve, a pump, a fan, a compressor, or the like, to set a fluid temperature of the portion of the product fluid to be regenerated by means of a flow through the intermediate product heat exchanger. Preferably, the temperature control includes at least one heat exchanger arranged downstream of the end-product outlet of the electrochemical separator. For the sake of clarity, this heat exchanger will also be referred to as end-product R.416559.
[0033] - 9 -
[0034] The primary side of the end-product heat exchanger is preferably connected to the end-product outlet to cool the at least one end product. The end-product heat exchanger is particularly preferably designed as a condenser, especially a gas-liquid separator, to separate end products with different boiling points and / or sublimation points, particularly carbon dioxide and water, and preferably to supply them, at least substantially pure, to different output elements of the output unit. A secondary side of the end-product heat exchanger is preferably connected to the oxygen supply to the fuel cell unit as a preheater. Alternatively, the secondary side is connected to the fuel supply to the fuel cell unit or to an external cooling circuit as a preheater.The temperature control preferably comprises a secondary-side fluid control element, in particular a valve, a pump, a fan, a compressor, or the like, to set a fluid temperature of the discharged portion of the product fluid via a flow through the end-product heat exchanger. The inventive design with an end-product heat exchanger allows for the advantageously energy-efficient further separation of different end products. The inventive design with an intermediate-product heat exchanger allows the separator's operating temperature to be advantageously maintained at a high level, while the risk of damage to downstream components, in particular a recirculation pumping unit, can be advantageously minimized.
[0035] It is further proposed that a secondary side of the heat exchanger, in particular the separator heat exchanger, the intermediate product heat exchanger, and / or the final product heat exchanger, be arranged upstream of an oxygen inlet of the fuel cell unit. The oxygen inlet is preferably a fluid inlet of the oxygen electrode of the fuel cell unit. The secondary side of the heat exchanger is preferably arranged in the oxygen supply of the fuel cell device to the fuel cell unit. The secondary side of the separator heat exchanger and the secondary side of the intermediate product heat exchanger are preferably arranged in fluidically parallel branches of the oxygen supply. The secondary side of the final product heat exchanger is preferably located upstream of the secondary side of the R.416559
[0036] - 10 -
[0037] The separator heat exchanger and / or the intermediate product heat exchanger are arranged in the oxygen supply. Preferably, the oxygen supply comprises at least one oxygen preheater for tempering the oxygen-containing fluid before it enters the fuel cell unit. The oxygen preheater is preferably arranged downstream of the end-product heat exchanger and / or the intermediate product heat exchanger. The oxygen preheater is preferably arranged parallel to the separator preheater in terms of fluid flow. The design according to the invention advantageously minimizes heat loss.
[0038] It is further proposed that the fuel cell device comprises at least one preheating heat exchanger, the primary side of which is arranged downstream of an oxygen outlet of the fuel cell unit. The oxygen outlet is preferably a fluid outlet of the oxygen electrode. Preferably, the at least one oxygen preheater and / or at least one fuel preheater is designed as a preheating heat exchanger. The primary side of the fuel preheater and the primary side of the oxygen preheater are preferably connected in parallel to the oxygen outlet. The secondary side of the fuel preheater is preferably arranged in the fuel supply. The secondary side of the oxygen preheater is preferably arranged in the oxygen supply.Preferably, the temperature control comprises at least one fluid control element, in particular a control valve downstream of the oxygen outlet, to adjust the flow ratio of the oxygen preheater and the fuel preheater. The design according to the invention advantageously allows sufficient preheating of the fuel and / or the oxygen-containing fluid to be achieved independently of the separator's operating temperature.
[0039] It is further proposed that the fuel cell device comprises at least one additional electrochemical separator, which is fluidically connected in series with the at least one electrochemical separator. The at least one additional electrochemical separator is preferably designed analogously, and in particular identically, to the electrochemical separator and comprises R.416559.
[0040] - 11 -
[0041] In particular, an intermediate product electrode, a final product electrode, and an intermediate electrolyte. The further electrochemical separator is preferably arranged downstream of the final product electrode of the electrochemical separator. The fluid outlets of the respective intermediate product electrodes of the separators are preferably connected in parallel to the recirculation line. Alternatively, a fluid outlet of the intermediate product electrode of the further separator is connected to a discharge line separate from the recirculation line, for example, to an exhaust outlet of the fuel cell device. The electrochemical separators are preferably designed for a staged separation of the product fluid.Preferably, an electrochemical separator is provided for the coarse separation of the product fluid, particularly by means of a relatively low operating voltage, and a further electrochemical separator is provided for a subsequent fine separation of the product fluid, particularly by means of a relatively high operating voltage. The respective remaining fraction at the exit of the respective end-product electrode is an asymptotically decreasing function of the corresponding operating voltage. The control unit is preferably designed to adjust the operating voltage depending on the desired fraction. The electric current associated with the operating voltage is a function of the mass flow of the at least one oxidizable component at the entry point of the respective end-product electrode.Preferably, the control unit is designed to allow a relatively large residual fraction during coarse separation in order to keep the operating voltage and the associated electric current low. Preferably, the control unit is designed to reduce the residual fraction from the coarse separation below a predetermined threshold during fine separation, in particular by selecting a higher operating voltage than in the fine separation. Due to the dependence of the electric current on the mass flow rate of the at least one oxidizable component, the electric current per operating voltage is lower in fine separation, where the mass flow rate has already been reduced by the coarse separation, than in coarse separation. Depending on the selected ratio of the operating voltages and the residual fraction to be achieved, the absolute value of the electric current in fine separation can be greater, less, or equal to / equal to that in coarse separation.By the invention according to version R.416559.
[0042] - 12 -
[0043] With this design, an advantageously low residual fraction can be achieved, especially with a simultaneously advantageously low electrical power consumption by the separators.
[0044] It is further proposed that the dispensing unit comprises at least one carbon dioxide dispensing element for dispensing at least substantially pure carbon dioxide, particularly in the gaseous, liquid, solid, or supercritical state. The carbon dioxide dispensing element can be configured as a connection for an external transport line or as a filling machine for filling external storage containers, transport containers, tank trucks, or the like. The design according to the invention advantageously provides pure carbon dioxide for further use.
[0045] It is further proposed that the dispensing unit comprises at least one water dispensing element for dispensing at least substantially pure water, particularly in liquid form. The water dispensing element can be configured as a connection for an external transport line or as a filling machine for filling external storage containers, transport containers, tank trucks, or the like. The design according to the invention advantageously provides pure water for further use.
[0046] Furthermore, it is proposed that the fuel cell device comprises a multi-stage water separator unit for the separate provision of water as an end product from at least one other end product, in particular carbon dioxide. Preferably, the water separator unit comprises the end-product heat exchanger as a first stage. Preferably, the water separator unit comprises at least one further stage with a further water separation element, which is arranged downstream of a gas outlet of the end-product heat exchanger. The further water separation element is preferably designed as an air-cooled condenser, the secondary side of which preferably includes a fan for conveying ambient air, in particular independently of the oxygen supply.A water outlet of the first stage and a water outlet of at least one further stage are preferably connected in parallel via fluid technology to the water dispensing element and / or the end-product return line. A gas outlet of at least one R.416559.
[0047] - 13 -
[0048] The further stage is preferably connected to the carbon dioxide output element. The design according to the invention allows for an advantageously high purity level of the carbon dioxide, in particular more than 99.5% based on volume, mass and / or amount of substance. Furthermore, the purity level of the water and the carbon dioxide can advantageously be adjusted independently of each other.
[0049] It is further proposed that the at least one electrochemical separator be fluidically connected according to the countercurrent principle. Preferably, a fluid outlet of the intermediate product electrode and a fluid inlet of the final product electrode are arranged on the same side of the separator. The inventive design allows for advantageously effective and efficient separation of the final products and the intermediate products.
[0050] Furthermore, a method for controlling a fuel cell device according to the invention is proposed, wherein in at least one process step a remaining residual proportion of the at least one oxidizable component in the at least one end product is adjusted. Preferably, the fuel cell unit converts the fuel into the product fluid. Preferably, the control unit adjusts the electrical operating voltage of the at least one electrochemical separator such that the proportion of the product fluid at the end product electrode is converted in such a way that it consists of at least 99%, preferably at least 99.5%, and particularly preferably at least 99.9%, based on volume, mass, and / or substance content, only of the at least one end product, in particular a mixture of carbon dioxide and water.Preferably, the water and carbon dioxide are separated by the end-product heat exchanger, in particular by the multi-stage water separation unit, and fed, at least substantially, in a pure form to the separate output elements of the output unit and / or the end-product return line. The control unit preferably regulates the flow through the end-product heat exchanger such that the water is condensed. Preferably, the control unit uses the separator heat exchanger R.416559.
[0051] - 14 -
[0052] The control unit preferably sets an operating temperature of the at least one separator via the intermediate product heat exchanger and / or the end-product return line by cooling the product fluid coming from the fuel cell unit using a portion of the oxygen-containing fluid and / or a portion of the water present as the end product. Preferably, the control unit also sets a fluid temperature of the portion of the product fluid coming from the at least one separator by cooling it using a further portion of the oxygen-containing fluid and / or the water present as the end product. Preferably, the control unit adjusts the flow through the oxygen electrode of the fuel cell unit depending on the air volumes required for cooling the intermediate product heat exchanger and / or the separator heat exchanger.Preferably, the control unit adjusts the flow ratio of the oxygen preheater and the fuel preheater to achieve an operating temperature of the fuel cell unit and, in particular, the reformer.
[0053] In at least one process step, the control unit adjusts the residual fraction of the at least one end product by means of at least one operating parameter, in particular the operating voltage, the operating temperature, and / or the space velocity of the electrochemical separator. Preferably, the control unit selects a value of the operating parameter depending on a purity level of the at least one of the end products, which is specified, for example, by a user. Preferably, the control unit adjusts the operating voltage of the at least one separator to achieve the specified purity level of the water and / or the carbon dioxide. Preferably, the control unit also adjusts a cooling capacity of the end-product heat exchanger and / or the subsequent stage of the multi-stage water separator unit to achieve the specified purity level of the carbon dioxide.
[0054] The design according to the invention allows the operating temperature of the separator to be advantageously set independently of other components. Furthermore, the operation of the fuel cell device can be advantageously adapted flexibly to different demands. In particular, the fuel cell device can be operated in such a way that advantageously few [unclear] components are required.
[0055] - 15 -
[0056] Waste materials, especially exhaust gases, are produced during the process. In particular, the fuel cell device can be operated advantageously in a resource-efficient and climate-friendly manner, especially in a climate-neutral way.
[0057] The fuel cell device and / or the method according to the invention are not / should not be limited to the application and embodiment described above. In particular, the fuel cell device and / or the method according to the invention may, to achieve a functionality described herein, have a different number of individual elements, components, process steps, and units than the number specified herein. Furthermore, values within the specified limits of the value ranges stated in this disclosure shall also be considered disclosed and freely usable.
[0058] Drawings
[0059] Further advantages become apparent from the following description of the drawings. The drawings illustrate four exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.
[0060] They show:
[0061] Fig. 1 shows a schematic circuit diagram of a fuel cell device according to the invention with an electrochemical separator,
[0062] Fig. 2 shows an extended schematic circuit diagram of the fuel cell device according to the invention with a temperature management system based on heat exchangers.
[0063] Fig. 3 shows an extended schematic circuit diagram of an alternative embodiment of the fuel cell device with an R.416559
[0064] - 16 -
[0065] Water injection for temperature control of a fluid inlet of the electrochemical separator,
[0066] Fig. 4 shows an extended schematic circuit diagram of a further alternative embodiment of the fuel cell device with water injection for temperature control of a fluid outlet of the electrochemical separator and
[0067] Fig. 5 shows a schematic circuit diagram of an additional alternative for the design of the fuel cell device with several electrochemical separators.
[0068] Description of the exemplary implementations
[0069] Figures 1 and 2 show a fuel cell device 10a with an electrochemical separator 14a. Figure 1 shows a simplified section of the fuel cell device 10a to explain the operation of the electrochemical separator 14a. Figure 2 shows an extended circuit diagram of the fuel cell device 10a to explain the fluidic connections and the integration of the electrochemical separator 14a into the fuel cell device 10a, in particular into a thermal management system of the fuel cell device 10a.
[0070] The fuel cell device 10a comprises at least one fuel cell unit 12a (see Figure 2) for the electrochemical conversion of at least one carbon-containing fuel into at least one product fluid. The electrochemical separator 14a is provided for separating the product fluid into at least one end product and at least one oxidizable component. The at least one end product is preferably not further oxidizable and is, for example, carbon dioxide and / or water. The oxidizable component can be a residue of the fuel and / or an intermediate of the fuel, in particular carbon monoxide or molecular hydrogen. During regular operation of the fuel cell unit 12a, the at least one oxidizable component typically constitutes between 5% and 25%, preferably between 10% and 20%, and particularly between 13% and 17%, of the total volume of the product fluid.
[0071] - 17 -
[0072] The electrochemical separator 14a is arranged downstream of the fuel cell unit 12a. The fuel cell device 10a preferably comprises at least one fuel exhaust line 70a to discharge the product fluid from the fuel cell unit 12a and supply it to the electrochemical separator 14a. The separator 14a preferably comprises a plurality of electrochemical cells, which are connected electrically in series and fluidically in parallel, particularly for common operation. For clarity, the separator 14a is functionally represented here by a single electrochemical cell. The separator 14a preferably comprises an intermediate product electrode 74a and a final product electrode 76a, which are spaced apart from each other by means of a gas-tight and oxygen-conducting electrolyte. The intermediate product electrode 74a and the final product electrode 76a are preferably connected fluidically in parallel to the fuel exhaust line 70a.
[0073] The fuel cell device 10a preferably comprises an intermediate product discharge line 66a, which is connected to an intermediate product outlet of the intermediate product electrode 74a. The intermediate product electrode 74a is preferably designed to chemically reduce the product fluid and thereby increase the proportion of oxidizable components of the product fluid in the intermediate product discharge line 66a. The fuel cell device 10a preferably comprises a product discharge line 72a, which is connected to an end-product outlet of the end-product electrode 76a. The end-product electrode 76a is preferably designed to oxidize the product fluid and thereby reduce the proportion of oxidizable components of the product fluid in the product discharge line 72a, in particular to keep it below a predetermined threshold value.Preferably, the separator 14a is designed to discharge a fluid at the end product outlet which consists of more than 99%, in particular more than 99.9%, exclusively of end products that are not further oxidizable, in particular carbon dioxide and water.
[0074] The fuel cell device 10a comprises at least one output unit 16a for the essentially pure output of at least one end product. The output unit 16a is preferably located downstream of the product discharge line R.416559.
[0075] - 18 -
[0076] The fuel cell device 10a comprises a water separator unit 38a for separating water from at least one other end product, in particular carbon dioxide. An inlet of the water separator unit 38a is preferably connected to the product discharge line 72a. A water outlet of the water separator unit 38a is preferably connected to the water discharge element 36a. A gas outlet of the water separator unit 38a is preferably connected to the carbon dioxide discharge element 34a.
[0077] The fuel cell device 10a comprises a separator control unit for adjusting the residual proportion of the oxidizable component in the at least one end product. The separator control unit includes at least a voltage control for adjusting the residual proportion of the at least one oxidizable component by means of an electrical operating voltage of the electrochemical separator 14a. The voltage control preferably comprises at least one voltage adjusting element 82a, which is connected to the intermediate product electrode 74a and the end product electrode 76a. The voltage adjusting element 82a is preferably designed as an adjustable voltage source, or alternatively as a DC-DC converter. Preferably, the achievable residual proportion is stored in a memory of the separator control unit as an asymptotically decreasing function of the adjustable operating voltage of the electrochemical separator 14a.Preferably, the separator control unit is designed to increase the operating voltage if the residual fraction exceeds a predetermined threshold. Preferably, the separator control unit is designed to decrease the operating voltage if the residual fraction is below the threshold, in order to minimize the electrical power consumption of the electrochemical separator 14a in order to reach the predetermined threshold. Preferably, the voltage control element 82a is designed to provide, in particular continuously, different voltages within a range of 0.1 V and 1 V, and especially at least between 0.5 V and 0.6 V. The separator control unit preferably includes at least one sensor 86a for monitoring.
[0078] - 19 -
[0079] of the residual fraction of the at least one oxidizable component. The separator control unit is preferably designed to adjust the voltage control element 82a as a function of a measured value from the sensor 86a. The sensor 86a is preferably designed to detect the concentration of the at least one oxidizable component. The sensor 86a is, for example, configured as a lambda probe, in particular a broadband lambda probe. The sensor 86a is preferably arranged in a gas line downstream of the water separator unit 38a. Alternatively, the sensor 86a is arranged in the product discharge line 72a or directly at the end-product outlet of the electrochemical separator 14a.
[0080] Figure 2 shows the integration of the electrochemical separator into the fluid management system of the fuel cell device 10a. The fuel cell unit 12a preferably comprises a plurality of solid oxide fuel cells, which are connected in series electrically and in parallel fluidically, particularly for common operation. For clarity, the fuel cell unit 12a is functionally represented here by a single fuel cell. The at least one fuel cell unit 12a preferably comprises at least one fuel electrode 46a and one oxygen electrode 44a, which are spaced apart by means of an electrolyte, in particular an oxygen-conducting one. The fuel cell device 10a preferably comprises at least one oxygen supply 40a, which is connected to an oxygen inlet of the oxygen electrode 44a and is provided for supplying the oxygen electrode 44a with an oxygen-containing fluid, in particular ambient air.The fuel cell device 10a preferably comprises at least one fuel supply 42a, which is connected to a fuel inlet of the fuel electrode 46a and is provided for supplying the fuel electrode 46a with the fuel. The fuel cell unit 12a is designed to convert the fuel into the product fluid and the oxygen-containing fluid into an oxygen-side exhaust gas. The fuel cell device 10a preferably comprises at least one oxygen exhaust gas line for discharging the oxygen-side exhaust gas via an exhaust air outlet 54a, in particular via a chimney. The oxygen exhaust gas line preferably comprises an oxygen discharge branch 48a and a further R.416559.
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[0082] Oxygen discharge branch 50a, which are connected in parallel via fluid technology to an oxygen outlet of the oxygen electrode 44a and in particular to the exhaust air outlet 54a.
[0083] The intermediate product discharge line 66a connected to the electrochemical separator 14a is preferably designed as a recirculation line. The intermediate product discharge line 66a preferably opens into the fuel supply 42a and is intended to feed the at least one still oxidizable component back into the fuel.
[0084] The water separator unit 38a is preferably designed in multiple stages. The water separator unit 38a preferably comprises, as a first stage, an end-product heat exchanger 22a, the primary side of which is connected to the product discharge line 72a and the secondary side of which is connected to the oxygen supply 40a. The water separator unit 38a preferably comprises, as a further stage, an electric water separator 78a in the form of an air-cooled condenser, which is connected to a gas outlet of the end-product heat exchanger 22a.
[0085] The separator control unit preferably comprises at least one temperature control for setting an operating temperature of the electrochemical separator 14a. The temperature control unit comprises at least one separator heat exchanger 18a, which is arranged fluidically between the fuel cell unit 12a and the electrochemical separator 14a. A primary side of the separator heat exchanger 18a is preferably arranged in the fuel exhaust line 70a. A secondary side of the separator heat exchanger 18a is preferably arranged upstream of the oxygen inlet of the fuel cell unit 12a. The secondary side of the separator heat exchanger 18a is preferably arranged in a separator cooling branch 56a of the oxygen supply 40a, which runs fluidically parallel to a main branch 58a of the oxygen supply 40a.The temperature control comprises at least one fluid actuating element 24a, preferably a control valve, particularly in the form of a gas damper, upstream of the separator heat exchanger 18a, in order to regulate the flow through the separator heat exchanger 18a, particularly on the secondary side. This is shown in R.416559.
[0086] - 21 -
[0087] The fluid control element 24a associated with the separator heat exchanger 18a is preferably arranged in the separator cooling branch 56a.
[0088] The temperature control system comprises at least one intermediate product heat exchanger 20a, which is connected downstream of the intermediate product outlet of the electrochemical separator 14a. A primary side of the intermediate product heat exchanger is preferably arranged in the intermediate product discharge line 66a. A secondary side of the intermediate product heat exchanger 20a is preferably arranged upstream of the oxygen inlet of the fuel cell unit 12a. The secondary side of the intermediate product heat exchanger 20a is preferably arranged in a recirculation cooling branch 60a that is fluidically parallel to the main branch 58a of the oxygen supply 40a. The temperature control system comprises at least one fluid actuating element 26a, preferably a control valve, in particular in the form of a gas damper, upstream of the intermediate product heat exchanger 20a, in order to regulate the flow through the intermediate product heat exchanger 20a, in particular on the secondary side.The fluid control element 26a associated with the intermediate product heat exchanger 20a is preferably arranged in the recirculation cooling branch 60a.
[0089] The temperature control system comprises at least the end-product heat exchanger 22a, which is connected downstream of the end-product outlet of the electrochemical separator 14a. The secondary side of the end-product heat exchanger 22a is preferably arranged upstream of the oxygen inlet of the fuel cell unit 12a. The temperature control system comprises at least one fluid control element 28a upstream of the end-product heat exchanger 22a to regulate the flow through the end-product heat exchanger 22a, particularly on the secondary side. The fluid control element 28a associated with the end-product heat exchanger 22a is preferably a central fluid delivery unit, more preferably a blower or a compressor, for conveying the oxygen-containing fluid through the oxygen supply 40a to the fuel cell unit 12a and to the exhaust outlet 54a.A branch of the separator cooling branch 56a and the recirculation cooling branch 60a from the main branch 58a of the oxygen supply 40a is preferably arranged downstream of the end product heat exchanger 22a. R.416559.
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[0091] The fuel cell device 10a comprises at least one pre-temperature heat exchanger 32a as an oxygen preheater, the primary side of which is arranged downstream of the oxygen outlet of the fuel cell unit 12a. The primary side of the oxygen preheater is preferably arranged in the further oxygen discharge branch 50a. A secondary side of the oxygen preheater is preferably arranged in the main branch 58a. Preferably, the fuel cell device 10a comprises at least one oxygen control element 80a, in particular a control valve, which is arranged in the main branch 58a downstream of the branch of the separator cooling branch 56a and the recirculation cooling branch 60a. The oxygen control element 80a is preferably designed to regulate the flow through the oxygen preheater. The separator cooling branch 56a preferably opens back into the main branch 58a downstream of the oxygen preheater.The recirculation cooling branch 60a preferably opens downstream of the oxygen control element 80a and upstream of the oxygen preheater back into the main branch 58a.
[0092] The fuel supply 42a preferably comprises a fuel supply control element 62a for setting the rate at which fresh fuel is fed into the fuel cell unit 12a. The recirculation line 66a preferably opens into the fuel supply 42a downstream of the fuel supply control element 62a. The fuel supply control element 62a can be configured as a valve or as a fluid conveying unit, in particular a blower or compressor, as shown here. The fuel cell device 10a preferably comprises a recirculation conveying unit 64a for setting the rate at which the product fluid is fed back into the fresh fuel. The recirculation conveying unit 64a is preferably configured as a blower or compressor.The recirculation pumping unit 64a can be arranged, as shown here, in the fuel supply 42a downstream of an outlet of the recirculation line 66a in the fuel supply 42a or in the recirculation line 66a. The recirculation pumping unit 64a is preferably arranged downstream of the intermediate product heat exchanger 20a with respect to the fuel or the recirculated product fluid. The fuel cell device 10a comprises at least one pre-temperature heat exchanger 30a as a fuel preheater, the primary side of which is located downstream at the oxygen outlet of the fuel R.416559.
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[0094] The fuel cell unit 12a is arranged. The primary side is preferably arranged in the oxygen discharge branch 48a. The fuel cell device 10a preferably comprises at least one exhaust control element 52a, which is shown here by way of example arranged in the further oxygen discharge branch 50a in order to adjust the flow ratio of the oxygen discharge branch 48a and the further oxygen discharge branch 50a. A secondary side of the fuel preheater is preferably arranged in the fuel supply 42a. Preferably, the fuel preheater is arranged downstream of the recirculation pumping unit 64a. Depending on the intended fuel, the fuel supply 42a can include a reformer 68a, which is preferably arranged downstream of the fuel preheater.
[0095] Figures 3 to 5 show further embodiments of the invention. The following descriptions and drawings are essentially limited to the differences between the embodiments, whereby with regard to identically designated components, in particular components with the same reference numerals, reference may also be made to the drawings and / or the description of the other embodiments, especially Figures 1 to 2. To distinguish the embodiments, the letter a is appended to the reference numerals of the embodiment in Figures 1 to 2. In the embodiments of Figures 3 to 5, the letter a is replaced by the letters b to d.
[0096] Figure 3 shows a fuel cell device 10b with at least one fuel cell unit 12b for the electrochemical conversion of at least one carbon-containing fuel into at least one product fluid. The fuel cell device 10b comprises at least one electrochemical separator 14b arranged downstream of the fuel cell unit 12b for separating the product fluid into at least one end product and at least one oxidizable component. The fuel cell device 10b includes a separator control unit for adjusting the residual proportion of the at least one oxidizable component remaining in the at least one end product. A temperature control of the separator control unit preferably includes a water injection system 88b. The water injection system 88b preferably opens into a [missing information - likely a reference to a specific component or component] on the fuel cell [missing information - likely a specific component].
[0097] - 24 -
[0098] Unit 12b is connected to the fuel exhaust line 70b of the fuel cell device 10b. The water injection unit 88b is designed to cool the product fluid by evaporating the water within the product fluid. Preferably, the fuel cell device 10b includes the water injection unit 88b instead of a separator heat exchanger 18a as shown in Figure 2. Alternatively, a combination with the separator heat exchanger 18a is also conceivable, wherein the water injection unit 88b can open into the fuel exhaust line 70b upstream or downstream of the separator heat exchanger 18a. A supply to the water injection unit 88b is preferably connected to a water outlet of a water separator unit 38b of the fuel cell device 10b. The temperature control comprises at least one fluid actuating element 24b, preferably a pump, or alternatively or additionally a control valve, to set a water supply rate to the product fluid.
[0099] Regarding further features of the fuel cell device 10b, reference is made to the description of Figures 1 and 2.
[0100] Figure 4 shows a fuel cell device 10c with at least one fuel cell unit 12c for the electrochemical conversion of at least one carbon-containing fuel into at least one product fluid. The fuel cell device 10c comprises at least one electrochemical separator 14c arranged downstream of the fuel cell unit 12c for separating the product fluid into at least one end product and at least one oxidizable component. The fuel cell device 10c includes a separator control unit for adjusting the residual proportion of the at least one oxidizable component remaining in the at least one end product. A temperature control of the separator control unit preferably includes a water injection system 88c. The water injection system 88c preferably opens into an intermediate product discharge line 66c of the fuel cell device 10c connected to the separator 14c.The water injection system 88c is designed to cool a portion of the product fluid fed back into the fuel by evaporating water within the product fluid. Preferably, the fuel cell device includes the water injection system 88c instead of an intermediate product heat exchanger 20a as shown in Figure 2. Alternatively, a combination with the intermediate product heat exchanger 20a is also conceivable, wherein the water injection system R.416559.
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[0102] The water injection system 88c can open upstream or downstream of the intermediate product heat exchanger into the intermediate product discharge line 66c. A supply for the water injection system 88c is preferably connected to a water outlet of a water separator unit 38c of the fuel cell device 10c. The temperature control system comprises at least one fluid control element 26c, preferably a pump, or alternatively or additionally a control valve, to adjust the water supply rate to the intermediate product discharge line 66c. The water injection system 88c can be combined, as shown here, with a separator heat exchanger 18c or with a water injection system 88b as shown in Figure 3, wherein in the latter case each of the water injection systems 88b, 88c preferably comprises its own fluid control element 24b, 26c.
[0103] Regarding further features of the fuel cell device 10c, reference is made to the description of Figures 1 to 3.
[0104] Figure 5 shows a fuel cell device 10d with at least one fuel cell unit (not shown here) for the electrochemical conversion of at least one carbon-containing fuel into at least one product fluid. The fuel cell device 10d comprises at least one electrochemical separator 14d, 90d arranged downstream of the fuel cell unit for separating the product fluid into at least one end product and at least one oxidizable component. Preferably, the fuel cell device 10d comprises at least two electrochemical separators 14d, 90d connected in series, namely a first separator 14d and a further separator 90d. The electrochemical separators 14d, 90d are of analogous, and in particular identical, construction. An intermediate product electrode 74d and an end product electrode 76d of the first separator 14d are preferably connected fluidically to a fuel exhaust line 70d of the fuel cell device 10d.An intermediate product electrode 92d and an end product electrode 94d of the further separator 90d are preferably connected in parallel via fluid flow to an end product outlet of the end product electrode 76d of the first separator 14d. An intermediate product outlet of the intermediate product electrode 74d of the first separator 14d and an intermediate product outlet of the intermediate product electrode 92d are preferably connected in parallel via fluid flow to an intermediate product discharge line 66d of the fuel cell device 10d. EinR.416559.
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[0106] The end product outlet of the end product electrode 94d of the further separator 90d is preferably connected to a product discharge line 72d of the fuel cell device 10d.
[0107] The fuel cell device 10c comprises a separator control unit for adjusting the residual proportion of the at least one oxidizable component remaining in the at least one end product. The separator control unit preferably includes a separate voltage control element 82d, 84d for each separator 14d, 90d, in order to operate the separators 14d, 90d independently of one another with different operating voltages. The first separator 14d is preferably designed for a coarse separation of the product fluid into the at least one end product and the at least one oxidizable component. The further separator 90d is preferably designed for a fine separation of the product fluid into the at least one end product and the at least one oxidizable component. An electric current associated with the operating voltage is a function of a mass flow of the at least one oxidizable component at the respective end product electrode 76d, 94d.The mass flow at the inlet of the end-product electrode 76d of the first separator 14d is still relatively large compared to the mass flow at the inlet of the end-product electrode 94d of the second separator 90d. The first separator 14d is preferably operated at a lower operating voltage, for example, less than 0.4 V, than the second separator 90d in order to keep the electrical power consumption of the first separator 14d low. The second separator 90d can advantageously be operated at a higher operating voltage than the first separator 14d, for example, between 0.5 and 0.6 V, since the mass flow has already been reduced by the first separator 14d, so that a preferably lower residual fraction of the oxidizable component can be achieved with a preferably low electrical power consumption.
[0108] Regarding further features of the fuel cell device 10d, reference is made to the description of Figures 1 to 4. In particular, the fuel cell device 10d can be combined with any of the embodiments shown in Figures 2 to 4.
Claims
R.416559 - 27 - Claims 1. Fuel cell device (1 Oa; 10b; 10c; 10d) with at least one fuel cell unit (12a; 12b; 12c) for the electrochemical conversion of at least one carbon-containing fuel into at least one product fluid and with at least one electrochemical separator (14a; 14b; 14c; 14d, 90d) arranged downstream of the fuel cell unit (12a; 12b; 12c) for separating the product fluid into at least one end product and at least one oxidizable component, characterized by a separator control unit for adjusting the residual proportion of the at least one oxidizable component remaining in the at least one end product.
2. Fuel cell device (10a; 10b; 10c; 10d) according to claim 1, characterized in that the separator control unit comprises at least a voltage control to adjust the residual fraction by means of an electrical operating voltage of the electrochemical separator (14a; 14b; 14c; 14d, 90d).
3. Fuel cell device (10a; 10b; 10c; 10d) according to claim 1 or 2, characterized by at least one output unit (16a; 16b; 16c) connected to the separator (14a; 14b; 14c; 14d, 90d) for the essentially pure output of the at least one end product with at most the residual proportion of the at least one oxidizable component set by the separator control unit.
4. Fuel cell device (10a; 10b; 10c; 10d) according to one of the preceding claims, characterized in that the separator control unit comprises at least one temperature control with at least one separator temperature control element for setting an operating temperature of the electrochemical separator (14a; 14b; 14c; 14d, 14d). R.416559 - 28 - 5. Fuel cell device (10b; 10c; 10d) according to claim 4, characterized in that the temperature control comprises at least one end product return line connected to the at least one electrochemical separator (14b; 14c; 14d, 90d) for feeding at least a part of the at least one end product back into the fuel and / or the product fluid.
6. Fuel cell device (10a; 10c; 10d) according to claim 4 or 5, characterized in that the temperature control comprises at least one heat exchanger (18a; 18c) which is arranged fluidically between the fuel cell unit (12a; 12c) and the at least one electrochemical separator (14a; 14c; 14d, 90d).
7. Fuel cell device (10a; 10b; 10c; 10d) according to one of claims 4 to 6, characterized in that the temperature control comprises at least one heat exchanger (20a, 22a; 20b, 22b; 22c) which is arranged downstream of an outlet of the at least one electrochemical separator (14a; 14b; 14c; 14d, 90d).
8. Fuel cell device (10a; 10b; 10c; 10d) according to one of claims 6 or 7, characterized in that a secondary side of the heat exchanger (18a, 20a, 22a; 20b, 22b; 18c, 22c) is preferably arranged upstream of an oxygen inlet of the fuel cell unit (12a; 12b; 12c).
9. Fuel cell device (10a; 10b; 10c; 10d) according to one of the preceding claims, characterized by at least one pre-tempering heat exchanger (30a, 32a; 30b, 32b; 30c, 32c), the primary side of which is arranged downstream at an oxygen outlet of the fuel cell unit (12a; 12b; 12c).
10. Fuel cell device (10d) according to one of the preceding claims, characterized by at least one further electrochemical separator (90d) which is fluidically connected in series with the at least one electrochemical separator (14d). R.416559 - 29 - 11. Fuel cell device (1 Oa; 10b; 10c; 10d) according to one of the preceding claims, characterized by an output unit (16a; 16b; 16c) with at least one carbon dioxide output element (34a; 34b; 34c) for outputting at least substantially pure carbon dioxide.
12. Fuel cell device (1 Oa; 10b; 10c; 10d) according to one of the preceding claims, characterized by at least one output unit (16a; 16b; 16c) with at least one water output element (36a; 36b; 36c) for outputting at least substantially pure water.
13. Fuel cell device (10a; 10b; 10c; 10d) according to one of the preceding claims, characterized by a multi-stage water separator unit (38a; 38b; 38c) for providing water as an end product separately from at least one further end product, in particular carbon dioxide.
14. Fuel cell device (10a; 10b; 10c; 10d) according to one of the preceding claims, characterized in that the at least one electrochemical separator (14a; 14b; 14c; 14d, 90d) is fluidically connected according to the countercurrent principle.
15. Method for controlling a fuel cell device (10a; 10b; 10c; 10d) according to one of the preceding claims, wherein in at least one process step a remaining residual proportion of the at least one oxidizable component is incorporated into the at least one final product.