Fuel cell device, fuel cell system and method

Abstract

The invention is based on a fuel cell device, in particular an SOFC fuel cell device, with at least one fuel cell unit (10a; 10b), and with at least one process air supply unit (12a; 12b) which is designed to supply at least one oxygen-containing process air (14a; 14b) to the fuel cell unit (10a; 10b), with at least one desulfurization unit (18a; 18b) which is designed to desulfurize a process gas (16a; 16b), in particular before it is fed into the fuel cell unit (10a; 10b), with at least one compressor (20a; 20b) which is designed to supply the process gas (16a; 16b) to the desulfurization unit (18a; 18b). A heat exchanger unit (22a; 22b) arranged between the compressor (20a; 20b) and the desulfurization unit (18a; 18b) is proposed, which is designed to cool the process gas (16a; 16b).

Description

State of the art

[0001] A fuel cell device, in particular an SOFC fuel cell device, has already been proposed, comprising at least one fuel cell unit, and at least one process air supply unit which is configured to supply at least one oxygen-containing process air to the fuel cell unit, at least one desulfurization unit which is configured to desulfurize a process gas, in particular before it is fed into the fuel cell unit, and at least one compressor which is configured to supply the process gas to the desulfurization unit. Disclosure of the invention

[0002] The invention is based on a fuel cell device, in particular SOFC fuel cell device, with at least one fuel cell unit, and with at least one process air supply unit which is designed to supply at least one oxygen-containing process air to the fuel cell unit, with at least one desulfurization unit which is designed to desulfurize a process gas, in particular before it is fed into the fuel cell unit, with at least one compressor which is designed to supply the process gas to the desulfurization unit.

[0003] A heat exchanger unit arranged between the compressor and the desulfurization unit is proposed, which is designed to cool the process gas.

[0004] The inventive design of the fuel cell device advantageously provides high efficiency, since, in particular, the heat exchanger unit allows the thermal energy of the process gas to be used to preheat the process air and / or to heat water in a water circuit. Advantageously, low complexity can be achieved, since additional components, such as an external auxiliary heating unit, can be dispensed with. Advantageously, high operational reliability can be provided, since, in particular, effective desulfurization can be ensured by cooling the process gas.

[0005] The fuel cell device is preferably designed as a solid oxide fuel cell, in particular SOFC (Solid Oxide Fuel Cell). Preferably, a plurality of fuel cell devices are connected as a fuel cell stack. The fuel cell device preferably has at least one fuel cell unit. It is conceivable for the fuel cell device to have a plurality of fuel cell units, in particular connected in parallel with regard to a process gas and process air supply. Preferably, the at least one fuel cell unit of the fuel cell device is designed to generate electrical energy and thermal energy. Preferably, the fuel cell unit is designed to generate the electrical energy by cold combustion, in particular oxidation, of the process gas in a redox reaction with the oxygen from the process air.The fuel cell unit preferably has at least one anode, at least one cathode and at least one membrane, in particular separating a cathode chamber and an anode chamber. It is conceivable for the fuel cell unit to have at least one reformer unit which is designed to generate hydrogen from the fuel. The process gas is preferably in the form of a fluidic fuel, in particular natural gas. Alternatively, the process gas could also be in the form of hydrogen or a comparable fuel. A “process gas” is to be understood in particular as a fluidic fuel which is designed to carry out a redox reaction with oxygen. A “process air” is to be understood in particular as oxygen-containing ambient air. The term “designed” is to be understood in particular as specially programmed, designed and / or equipped.The term "an object being configured for a specific function" should be understood in particular to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state. A "fuel cell unit" should be understood in particular as a functional unit configured to generate electrical energy at least in a chemical reaction between a process gas and oxygen-containing process air.

[0006] The process air supply unit is preferably designed to supply the process air to the fuel cell unit, in particular continuously. The process air supply unit preferably has at least one air filter, in particular an air particle filter. In particular, the air filter is designed to filter particles from the process air. The process air supply unit preferably has at least one compressor, which generates a process air flow for a continuous supply of process air to the fuel cell unit. The process air supply unit preferably has at least one process air supply element. The process air supply element could, for example, be designed as a pipe or a shaft or the like. The process air supply element preferably forms at least one process air supply channel.Preferably, the process air supply element is configured to fluidically connect the fuel cell unit to the air filter and / or the compressor. Preferably, the process air supply unit is configured to conduct the process air. Preferably, the process air supply unit is fluidically connected to the heat exchanger unit.

[0007] The fuel cell device preferably has at least one process gas supply unit. The process gas supply unit is preferably designed to supply the process gas to the fuel cell unit, in particular continuously. The process gas supply unit preferably has at least one compressor, in particular a gas booster. The compressor is preferably designed to generate a process gas pressure which is designed to move the process gas into the fuel cell unit, in particular to accelerate it. The process gas supply unit preferably has at least the desulfurization unit. The desulfurization unit is preferably designed to desulfurize the process gas, in particular by means of a cold desulfurization process. The process gas supply unit preferably has at least the heat exchanger unit.The heat exchanger unit is preferably designed to extract at least a large part of the thermal energy introduced into the process gas by the compressor. The heat exchanger unit is preferably designed at least as a cooling unit. It is conceivable that the heat exchanger unit alternatively or additionally has cooling fins. The heat exchanger unit could be designed to transfer the thermal energy of the process gas to ambient air and / or process air and / or to water and / or coolant and / or the like. It is conceivable that the heat exchanger unit has at least one heat exchanger with multiple functional areas and / or with multiple heat exchangers. For example, at least one of the heat exchangers could be designed to transfer the thermal energy to ambient air for cooling the process gas.For example, the or a further heat exchanger could be configured to transfer the thermal energy for cooling the process gas to water, in particular heating water. For example, the or a further heat exchanger could be configured to transfer the thermal energy for cooling the process gas to process air. It is conceivable for the heat exchanger unit to have further heat exchangers which are configured to transfer the thermal energy of the process gas to a further fluid and / or solid body and thereby cool the process gas. It is conceivable for the heat exchanger unit to have at least one distribution unit which is configured to supply the process gas flow completely or partially to at least one of the heat exchangers and / or functional areas. The heat exchanger unit is preferably arranged along a flow direction of the process gas between the compressor and the fuel cell unit.The heat exchanger unit is preferably arranged along the flow direction of the process gas between the compressor and the desulfurization unit. The desulfurization unit is preferably arranged along the flow direction of the process gas between the compressor and the fuel cell unit. The process gas supply unit preferably has at least one process gas supply element. The process gas supply element could, for example, be designed as a pipe or a shaft or the like. The process gas supply element preferably forms at least one process gas supply channel. The process gas supply element is preferably designed to fluidically connect the fuel cell unit to the compressor and / or the desulfurization unit and / or the heat exchanger unit. The process gas supply unit is preferably designed to conduct the process gas.The term "at least to a large extent" is to be understood as meaning, in particular, at least 55%, advantageously at least 65%, preferably at least 75%, particularly preferably at least 85%, and particularly advantageously at least 95%. "Heat energy" is to be understood as meaning, in particular, thermal energy, which is expressed as a temperature difference relative to a fluid or solid to which the thermal energy is to be transferred and / or relative to an ambient temperature.

[0008] The exhaust gas unit is preferably designed to direct the exhaust gas away from the reaction unit. In particular, the exhaust gas is at least substantially formed as the oxidized process gas. The exhaust gas preferably has thermal energy which is generated by the redox reaction in the fuel cell unit. In particular, the heat introduced into the fuel cell unit by the redox reaction is formed as waste heat. The exhaust gas unit preferably has at least one exhaust gas element. The exhaust gas element is preferably designed as an exhaust pipe or an exhaust shaft or the like. The exhaust gas element preferably forms at least one exhaust gas duct. In this context, “at least substantially” should be understood to mean in particular that a deviation from a predetermined value deviates by in particular less than 25%, preferably less than 10% and particularly preferably less than 5% of the predetermined value.

[0009] It is further proposed that the heat exchanger unit be configured to transfer the thermal energy of the process gas to the process air in at least one operating state. Advantageously, a high level of operational reliability can be provided since, in particular, the preheating of the process air makes it possible to provide a function even at very low ambient temperatures, since, for example, an air filter does not ice over. Preferably, the at least one operating state is designed at least as a start-up process of the fuel cell device. Preferably, the heat exchanger unit has at least one first heat exchanger which is configured to transfer the thermal energy of the process gas to the process air. Preferably, the first heat exchanger is designed as a gas-to-gas heat exchanger.Preferably, the first heat exchanger is configured to transfer the thermal energy from the process gas to the process air, at least when the ambient temperature falls below a critical value. The critical ambient temperature is preferably -5°C. It is conceivable that the critical ambient temperature depends on the process gas and / or a design of the fuel cell device and / or other influencing factors. A person skilled in the art will therefore determine the critical ambient temperature on a case-by-case basis. The critical ambient temperature is therefore in particular a maximum of 5°C, preferably a maximum of 0°C, preferably -5°C and, for example, -10°C. For example, the heat exchanger could be configured to transfer the thermal energy from the process gas to the process air, at least during a start-up process.A "critical ambient temperature" is to be understood in particular as a temperature of the ambient air below which process air must be preheated in order to ensure operation of the fuel cell device. A "start-up process" is to be understood in particular as at least one operating state in which the fuel cell unit at least substantially has an operating temperature, in particular less than 100°C, preferably less than 75°C. In particular, the start-up process follows a deactivated state of the fuel cell device and / or a standby mode and / or cleaning / maintenance mode and / or a comparable mode in which at least the temperature of the fuel cell unit is reduced compared to normal operation.

[0010] Furthermore, it is proposed that the heat exchanger unit has at least one pipe coil which carries the process gas and is arranged in a process air stream in the process air supply unit. Advantageously, a low-cost construction can be provided since, in particular, the pipe coils can be easily manufactured and the manufacture and / or purchase of a cost-intensive heat exchanger can be dispensed with. Preferably, the first heat exchanger of the heat exchanger unit is formed by the at least one pipe coil. Preferably, the first heat exchanger of the heat exchanger unit is designed to transfer the thermal energy of the process gas to the process air at least substantially via the at least one pipe coil. Preferably, the first heat exchanger has a plurality of pipe coils. Preferably, the pipe coils have at least substantially a constant radius of curvature.The pipe coils are preferably arranged along a rotational axis. The rotational axis of the pipe coils is preferably arranged at least substantially parallel or perpendicular to a flow direction of the process air. Alternatively, the pipe coils could also be arranged spirally and / or meanderingly and / or serpentinely and / or in a comparable arrangement. The pipe coils preferably run at least partially at least substantially along the process air supply element of the process air supply unit. The pipe coils are preferably designed to transfer the thermal energy from the process gas to the process air. Alternatively, it is conceivable that only one or only some of the pipe coils are arranged in the process air flow. For example, at least some of the pipe coils could be arranged outside the process air flow.

[0011] It is further proposed that the compressor, in particular a drive unit of the compressor, is arranged at least partially in the process air inflow in the process air supply unit. Advantageously, a particularly high level of efficiency can be provided because, in particular, the compressor, in particular the drive unit of the compressor, is arranged at least partially in the process air flow. The compressor preferably has at least one stator and one rotor, which is designed to generate a fluid pressure in the process gas. The stator is preferably arranged on a housing of the compressor. The housing is preferably arranged at least partially in the process air flow. The housing preferably has cooling fins on an outer side, which are designed to transfer thermal energy from the compressor to the process air. In particular, the outer side is arranged on a side of the housing opposite the rotor.The compressor preferably has at least one drive unit, which has at least one electric motor. It is conceivable for the compressor and the drive unit to be arranged entirely within the process air flow. It is conceivable for only the electric motor of the drive unit to be arranged within the process air flow. For example, a fan of the drive unit could be configured to cool the electric motor via the compressor of the process air supply unit.

[0012] It is also proposed that the heat exchanger unit be configured to transfer the thermal energy of the process gas to water in a water circuit in at least one operating state. A high degree of efficiency can advantageously be provided since, in particular, the thermal energy of the process gas can be used to heat the water in the water circuit. The operating state is preferably designed as a controlled operation, in particular at least substantially at an operating temperature, of the fuel cell unit. The water circuit preferably has at least one hot water storage tank and / or one hot water consumer. It is conceivable that the hot water circuit is designed as a customer water network, in particular an external one. The heat exchanger unit preferably has at least one second heat exchanger, which is configured to transfer the thermal energy to the water in the water circuit.The second heat exchanger is preferably designed as a gas-to-liquid heat exchanger. The second heat exchanger is preferably arranged at least substantially thermally decoupled from the first heat exchanger. The heat exchanger unit preferably has at least one distributor unit configured to supply the process gas to the first and / or second heat exchanger. The distributor unit preferably has at least one control flap. The control flap is preferably configured to supply the process gas stream to the first and / or second heat exchanger.

[0013] In addition, a fuel cell system, in particular a prefab fuel cell system, with at least one fuel cell device is proposed. Advantageously, a high level of efficiency can be achieved, since, in particular, the thermal energy of the process gas can be used to preheat the process air and / or to heat water in a water circuit. Advantageously, a low level of complexity can be achieved, since, in particular, additional components such as an external auxiliary heating unit can be dispensed with. Preferably, the fuel cell system comprises at least the water circuit. Preferably, the fuel cell system comprises at least one water reservoir. Preferably, the fuel cell system comprises at least one fuel cell device. In particular, the fuel cell system comprises further components deemed appropriate by those skilled in the art, such as line elements, seals, valves, pumps, and / or the like.The fuel cell system preferably has at least one control and / or regulating unit configured to control at least one process gas supply, in particular as a function of the ambient temperature, in the first and / or second heat exchanger. A "control and / or regulating unit" is understood in particular to mean a unit with at least one control electronics unit. A "control electronics unit" is understood in particular to mean a unit with a processor unit and a memory unit, as well as with an operating program stored in the memory unit.

[0014] In addition, it is proposed that, depending on at least one ambient temperature and / or a temperature in the fuel cell, the thermal energy of the process gas is transferred to the process air and / or to the water in the water circuit. A high level of efficiency can advantageously be provided since, in particular, the thermal energy of the process gas can be used to preheat the process air and / or to heat water in a water circuit. Preferably, the process air is preheated at least by the drive unit of the compressor and / or the compressor by the process air flowing around the drive unit of the compressor and / or the compressor. Alternatively or additionally, the process air is preheated by at least partially supplying the first heat exchanger of the heat exchanger unit with the process gas.Preferably, the process air is preheated by the process gas when the ambient temperature falls below a critical level. Preferably, the water in the water circuit is preheated when the ambient temperature exceeds the critical level.

[0015] Furthermore, it is proposed that the process air be preheated in such a way that ice formation is prevented at least on the air filter of the process air supply unit by setting a process air inflow temperature greater than 0 °C. Advantageously, high operational reliability can be provided, since, in particular, the thermal energy of the process gas can be used to preheat the process air and / or to heat water in a water circuit, thereby ensuring operation at very low temperatures. Ice formation is preferably prevented by preheating the process air in every operating state in such a way that the process air temperature is greater than 0 °C.

[0016] The fuel cell device according to the invention, the fuel cell system according to the invention, and the method according to the invention are not intended to be limited to the application and embodiment described above. In particular, the fuel cell device according to the invention, the fuel cell system according to the invention, and the method according to the invention may have a number of individual elements, components, units, and method steps that differs from the number stated herein to fulfill a functionality described herein. Furthermore, in the value ranges specified in this disclosure, values within the stated limits are also to be considered disclosed and can be used arbitrarily. drawing

[0017] Further advantages will become apparent from the following description of the drawings. The drawings illustrate two exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0018] They show: Fig. 1 a schematic representation of a fuel cell system with a fuel cell device and with a water circuit, Fig. 2 a schematic representation of the fuel cell device with a desulfurization unit and a heat exchanger unit, Fig. 3 a schematic representation of the heat exchanger unit, Fig. 4 a schematic representation of an arrangement of a compressor in the process air supply and Fig. 5 a schematic flow diagram of a method for operation. Description of the embodiments

[0019] The Fig. 1 shows a fuel cell system 36a. The fuel cell system 36a is designed as a prefab fuel cell system. The fuel cell system 36a has a fuel cell device. It is conceivable that the fuel cell system 36a has multiple fuel cell devices. The fuel cell devices are connected in parallel with respect to a process gas supply and a process air supply. The fuel cell device is designed as an SOFC (Solid Oxide Fuel Cell) fuel cell. The fuel cell system 36a has a water circuit 28a. The water circuit 28a has a hot water storage tank and / or a hot water consumer. Alternatively, the fuel cell system 36a could be configured to be connected to a customer water network.

[0020] The Fig. 2 shows the fuel cell device. The fuel cell device has a fuel cell unit 10a. The fuel cell unit 10a has an anode. The fuel cell unit 10a has a cathode. The fuel cell unit 10a has a membrane. The membrane is configured to separate a process gas 16a in an anode chamber and an oxygen-containing process air 14a in a cathode chamber. The fuel cell device has a process air supply unit 12a. The process air supply unit 12a is configured to supply the oxygen-containing process air 14a to the fuel cell unit 10a. The process air supply unit 12a has a process air supply element. The process air supply element is designed as a pipe or a shaft or the like. The process air supply unit 12a has a fan. The fan is configured to continuously supply the process air 14a to the fuel cell unit 10a.The blower is fluidically connected to the process air supply element. The process air supply unit 12a has an air filter 30a. The air filter 30a is designed as an air particle filter.

[0021] The air filter 30a is configured to filter the process air 14a. The air filter 30a is fluidically connected to the process air supply element. The fuel cell device has a process gas supply unit 38a. The process gas supply unit 38a is configured to supply the process gas 16a to the fuel cell unit 10a. The process gas 16a is embodied as natural gas. Alternatively, the process gas 16a could also be embodied as hydrogen or a comparable process gas deemed appropriate by a person skilled in the art. The fuel cell unit 10a is configured to generate electrical energy and thermal energy in a chemical reaction between the process gas 16a and the process air 14a. The chemical reaction is embodied as a redox reaction. It is conceivable that the fuel cell unit 10a has a reformer unit.The reformer unit could be configured to reform hydrogen from the process gas 16a, for example, natural gas. The fuel cell unit 10a could be configured to subsequently convert the hydrogen reformed in the reformer unit into electrical energy and thermal energy.

[0022] The fuel cell device has a desulfurization unit 18a. The desulfurization unit 18a is configured to desulfurize the process gas 16a to a large extent before it is fed into the fuel cell unit 10a. The desulfurization unit 18a is fluidically connected to the process gas supply unit 38a. The desulfurization unit 18a is configured to desulfurize the process gas 16a in a cold desulfurization process. The fuel cell device has a compressor 20a. The compressor 20a is fluidically connected to the process gas supply unit 38a. The compressor 20a is configured to supply the process gas 16a to the desulfurization unit 18a. The desulfurization unit 18a is arranged along a flow direction of the process gas 16a between the compressor 20a and the fuel cell unit 10a. The compressor 20a heats the process gas 16a during operation.

[0023] The fuel cell device has a heat exchanger unit 22a. The heat exchanger unit 22a is arranged along the flow direction of the process gas 16a between the compressor 20a and the desulfurization unit 18a. The heat exchanger unit 22a is configured to cool the process gas 16a upstream of the desulfurization unit 18a along the flow direction of the process gas 16a. The heat exchanger unit 22a is configured to transfer the thermal energy of the process gas 16a to the process air 14a in one operating state. The operating state is configured as a start-up process. The first operating state has an ambient temperature of less than -5°C. The heat exchanger unit 22a is configured to transfer the thermal energy of the process gas 16a to water in the water circuit 28a in a further operating state. The further operating state is configured as a control operation.The heat exchanger unit 22a has a first heat exchanger 40a. The first heat exchanger 40a is configured to transfer the thermal energy of the process gas 16a to the process air 14a. The first heat exchanger 40a is designed as a gas-to-gas heat exchanger. The heat exchanger unit 22a has a second heat exchanger 42a. The second heat exchanger 42a is designed as a gas-to-liquid heat exchanger. The second heat exchanger 42a is configured to transfer the thermal energy of the process gas 16a to water in the water circuit 28a. The heat exchanger unit 22a has a distribution unit 44a. The distribution unit 44a is configured to supply the process gas 16a to the first heat exchanger 40a and / or the second heat exchanger 42a. The distribution unit 44a could be designed as a multi-way valve or a control flap or the like.

[0024] The Fig. 3 shows the first heat exchanger 40a of the heat exchanger unit 22a. The first heat exchanger 40a has a plurality of tube coils 24a. The tube coils 24a are arranged in a meandering pattern. Alternatively, the tube coils 24a could also be arranged in a spiral or similar manner. The tube coils 24a are configured to guide the process gas 16a. The tube coils 24a are configured to transfer the thermal energy of the process gas 16a to the process air 14a. The tube coils 24a are configured to cool the process gas 16a. The tube coils 24a are arranged in the process air flow in the process air supply unit 12a. The tube coils 24a run perpendicular to a flow direction of the process gas 16a. Alternatively, the tube coils 24a could also run parallel to the flow direction of the process air 14a.

[0025] The Fig. 4 shows a schematic flow diagram of a method for operating the fuel cell device.

[0026] In at least one method step 32a, the thermal energy of the process gas 16a is transferred to the process air 14a and / or to the water of the water circuit 28a depending on an ambient temperature and / or a temperature in the fuel cell unit 10a. If a critical ambient temperature is undershot, the thermal energy of the process gas 16a is transferred to the process air 14a in the first heat exchanger 40a of the heat exchanger unit 22a. Above the critical ambient temperature, the thermal energy of the process gas 16a is transferred to the water of the water circuit 28a in the second heat exchanger 42a of the heat exchanger unit 22a. It is conceivable that, depending on the ambient temperature, a portion of the process gas 16a is passed into the first heat exchanger 40a, thereby preheating the process air 14a.It is conceivable that a portion of the process gas 16a is directed to the second heat exchanger 42a, thereby heating the water in the water circuit 28a. Alternatively or additionally, the process air 14a flows around the drive unit of the compressor 20a and / or the compressors 20a. This preheats the process air 14a. This cools the drive unit and / or the compressor 20a.

[0027] In at least one method step 34a, the process air 14a is preheated such that ice formation is prevented at least on the air filter 30a of the process air supply unit 12a by setting a temperature of the process air inflow greater than 0 °C. The process air 14a is preheated by the drive unit and / or the compressor 20a by the process air 14a flowing around the drive unit and / or the compressor 20a. Alternatively or additionally, depending on the ambient temperature, thermal energy is transferred to the process air 14a through the first heat exchanger 40a of the heat exchanger unit 22a. By preheating the process air 14a, a minimum temperature of the process air 14a is ensured so that no ice is formed.

[0028] In the Fig. 5 shows a further embodiment of the invention. The following descriptions and the drawings are essentially limited to the differences between the embodiments, whereby with regard to components with the same designation, in particular with regard to components with the same reference numerals, reference is also made to the drawings and / or the description of the other embodiments, in particular to the Fig. 1 to 4. To distinguish the embodiments, the letter a is added to the reference numerals of the embodiment in the Fig. 1 to 4. In the examples of the Fig. 5, the letter a is replaced by the letter b.

[0029] The Fig.5 shows a schematic representation of an alternative fuel cell device. The alternative fuel cell device has a fuel cell unit 10b. The alternative fuel cell device has an alternative process air supply unit 12b. The process air supply unit 12b is configured to supply process air 14b to the fuel cell unit 10b. The fuel cell device has a process gas supply unit 38b. The process gas supply unit 38b is configured to supply a process gas 16b to the fuel cell unit 10b. The process gas supply unit 38b has a compressor 20b. The compressor 20b is configured to compress the process gas 16b. The compressor 20b has a drive unit 26b. The drive unit 26b has an electric motor. The drive unit 26b of the compressor 20b is arranged in a process air stream of the process air supply unit 12b.The drive unit 26b is configured to transfer thermal energy to the process air. Alternatively or additionally, the compressor 20b is arranged in the process air inflow in the process air supply unit 12b. It is conceivable for the alternative fuel cell device to have a heat exchanger unit 22b configured to supply thermal energy of the process gas 16b to the process air 14b and / or water of a water circuit 28b.

Claims

[1] Fuel cell device, in particular SOFC fuel cell device, with at least one fuel cell unit (10a; 10b), and with at least one process air supply unit (12a; 12b) which is designed to supply at least one oxygen-containing process air (14a; 14b) to the fuel cell unit (10a; 10b), with at least one desulfurization unit (18a; 18b) which is designed to desulfurize a process gas (16a; 16b), in particular before being fed into the fuel cell unit (10a; 10b), with at least one compressor (20a; 20b) which is designed to supply the process gas (16a; 16b) to the desulfurization unit (18a; 18b), characterized by a heat exchanger unit (22a; 22b) arranged between the compressor (20a; 20b) and the desulfurization unit (18a; 18b), which is designed to cool the process gas (16a; 16b). [2] Fuel cell device according to claim 1, characterized bythat the heat exchanger unit (22a; 22b) is designed to transfer the thermal energy of the process gas (16a; 16b) to the process air (14a; 14b) in at least one operating state. [3] Fuel cell device according to one of the preceding claims, characterized by that the heat exchanger unit (22a; 22b) has at least one pipe winding (24a; 24b) carrying the process gas (16a; 16b), which is arranged in a process air stream in the process air supply unit (12a; 12b). [4] Fuel cell device according to one of the preceding claims, characterized by that the compressor (20b), in particular a drive unit (26b) of the compressor (20b), is arranged in the process air inflow at least partially in the process air supply unit (12b). [5] Fuel cell device according to one of the preceding claims, characterized bythat the heat exchanger unit (22a; 22b) is designed to transfer the thermal energy of the process gas (16a; 16b) in at least one operating state to a water of a water circuit (28a; 28b). [6] Fuel cell system (36a; 36b), in particular prefab fuel cell system, with at least one fuel cell device according to one of the preceding claims. [7] Method for operating the fuel cell device according to one of claims 1 to 5, characterized by that, depending on at least one ambient temperature and / or a temperature in the fuel cell unit (10a; 10b), the thermal energy of the process gas (16a; 16b) is transferred to the process air (14a; 14b) and / or to the water of the water circuit (28a; 28b). [8] Method according to claim 7, characterized bythat the process air (14a; 14b) is preheated in such a way that ice formation is prevented at least on the air filter (30a; 30b) of the process air supply unit (12a; 12b) by setting a temperature of the process air inflow of greater than 0 °C.

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