Device for producing water on board of an airplane

p0001The invention relates to an arrangement for producing water on board an aircraft using one or more fuel cells, wherein a partial or complete integration of a water production unit in the form of one or more high-temperature fuel cells is provided in an aircraft engine drive in such a way that combustion chambers of the aircraft engine are constructed entirely Or partly by the high-temperature fuel cells, and thus the process occurring in the combustion chambers of conventional type is supplemented or completely detached.

p0002From the <patcit id="pcit0001" dnum="EP957026A2"><text>EP 957 026 A2</text></patcit> A power supply unit is known on board an aircraft for substitution of a main power unit, an auxiliary power unit, a Ram Air turbine or a NiCd battery. A fuel cell is used to generate direct current, wherein exhaust air from the aircraft air-conditioning system or aircraft outer air is used for the air supply of the fuel cell. Water for the water supply of the aircraft is extracted from the fuel cell exhaust, the fuel cell exhaust being subsequently discharged to the aircraft environment, which also applies to the hydrogen exiting the fuel cell. Water is produced by means of a condenser arranged in the aircraft outlet.

p0003In the <patcit id="pcit0002" dnum="EP967676A1"><text>EP 967 676 A1</text></patcit> A jet engine is described which has fuel cells integrated into the combustion chambers. In this case, the fuel cells are arranged on the combustion chambers, in contrast to the subject matter of the new main claim which can be seen in the system, in which the combustion chambers are partially or completely replaced by the high-temperature fuel cell (s). In the prior art engine, the process of the engine is only used to operate the fuel cell.

p0004It is therefore an object of the invention to provide an arrangement of the type mentioned at the outset, in which a fuel cell-gas turbine combination for exclusive operation with hydrogen and air oxygen, as an engine and / or as an auxiliary power unit (APU) And compressed air supply to the cabin and to generate electricity.

p0005The object is achieved by the feature combination of claim 1.

p0006Embodiments of the invention are described in the subclaims 2 to 20.

p0007It is thus intended to replace at least one, but preferably a plurality, of combustion chambers with one or more high-temperature fuel cells. In contrast to the said object, however, at least one or more combustion chambers for combustion of a hydrogen-air mixture are obtained. The combustion chambers and high-temperature fuel cells are preferably arranged alternately annularly around the shaft or the shafts of the gas turbine.

p0008The combustion chambers serve the start of the gas turbine and the high-temperature fuel cells, as well as a brief increase in the air throughput of the gas turbine, for example, to the start of an aircraft. In continuous operation, only the thermal energy of the high-temperature fuel cell is used for the generation of the air throughput. The generation of water takes place on the anode side, ie on the hydrogen side in the high-temperature fuel cell. This so-called anode exhaust gas consists of 100% water vapor (hot steam) when the hydrogen is completely converted. This hot steam is passed through a turbine where it is cooled by expansion and thus thermal energy is converted into rotational energy of the turbine shaft. This rotational energy is used in a compressor,

p0009In a further process stage, the water vapor is finally condensed out. Pure H is obtained₂O, ie distilled water. This water is supplied to the different consumers or treated to a drinking water via a salting-up unit. The accumulated gray water is collected in a collecting container, as is the water fraction discharged during the dehydration of black water. The water quantities are evaporated in an evaporator operated with the waste heat of the water condensation process and fed together with the steam fraction not required for water production from the anode exhaust gas of the high-temperature fuel cell before the second turbine stage of the gas turbine. On the air side, outside air and / or exhaust air is sucked in via a so-called fan. This fan is driven in normal operation by the second turbine stage, during the starting process by an electric motor. The air conducted through the fan is first precompressed in a downstream compressor and then further compacted in a further compressor for the combustion chambers and the air side of the high-temperature fuel cell. The thermal energy introduced via the combustion chambers or the high-temperature fuel cell first drives the first turbine stage and after the above-described supply of gray water into the hot exhaust air stream, the second turbine stage. The number of compressor and turbine stages as well as the number of combustion chambers and the high-temperature fuel cells can be varied as desired for different types, depending on the requirements. The thermal energy introduced via the combustion chambers or the high-temperature fuel cell first drives the first turbine stage and after the above-described supply of gray water into the hot exhaust air stream, the second turbine stage. The number of compressor and turbine stages as well as the number of combustion chambers and the high-temperature fuel cells can be varied as desired for different types, depending on the requirements. The thermal energy introduced via the combustion chambers or the high-temperature fuel cell first drives the first turbine stage and after the above-described supply of gray water into the hot exhaust air stream, the second turbine stage. The number of compressor and turbine stages as well as the number of combustion chambers and the high-temperature fuel cells can be varied as desired for different types, depending on the requirements.

p0010The advantages of the arrangement according to the invention consist in a<ol><li>(A) flexibility against short-term performance requirements,</li><li>B) high integration of the individual process steps,</li><li>(C) high purity of the water obtained,</li><li>D) high efficiency of the system and in one</li><li>E) Weight reduction.</li></ol>

p0011An embodiment according to the invention is shown in the drawing, the sole figure showing a water generation system which has a tank 1 for liquid hydrogen. Thus, an application in a so-called "cryopanel" is particularly advantageous. As can be seen in the drawing, a high-temperature fuel cell 7 partially replaces a combustion chamber 7a of an aircraft engine 2. The high-temperature fuel cell 7 is supplied with pure hydrogen on the anode side and air is supplied to the combustion chamber 7a during the combustion chamber 7a. At least the hydrogen supply can be regulated or completely deactivated. The high-temperature fuel cell 7 is followed by at least one single-stage or multi-stage turbine 16 on the anode side, The thermal energy of the anode exhaust gas 35 is converted into rotational energy. Fuel cells of the oxide oxide (SOFC) type or the molten carbonate fuel cell (MCFC) or of a type comparable in power and temperature level can be used.

p0012The high temperature fuel cell 7 is followed by a condensation process 18, which condenses out water from a part of the anode exhaust gas 35 of the fuel cell 7. Furthermore, the high-temperature fuel cell 7 can be pressurized on both sides on the air side or on the oxygen side, on the one hand, and on the other hand on the fuel side or hydrogen side, the same or else different pressures being permissible on the anode side and on the cathode side. The use of liquid or gaseous hydrogen is possible. Liquid hydrogen 1 can be evaporated before entering the high-temperature fuel cell 7 or combustion chamber 7a, whereby the evaporator 17 can be operated with the process heat of the anode-offgas condenser 18. A particular embodiment of the inventive arrangement is that, The evaporator 17 is arranged annularly around the condenser 18 or circularly within the condenser 18 and is designed as a tube bundle heat exchanger. Here as well, at least a part of the condensation process 18 can be operated with cooling air 19.

p0013It is possible to collect used water as well as unnecessary condensate in a container 32. The air 20 heated in the condensation process 18 is advantageously used for evaporation of the gray water in a separate container 33, A pump 37, a filter being provided for the retention of solids and suspended matter from the gray water. Water is removed from the condensation process 18 in a distilled quality and is distributed in such a way that the galleys 23, the handwashing basins 24 and the showers 25 are supplied with distilled water with a drinking water 22 generated by the addition of salt 23 as well as the WCs 27 and the air humidification 26 The turbine stages 8, 9 can operate both the compressor stages 5, 6 and the fan 11, whereby the compressor stages 5, 6 pressurize both the high-temperature fuel cell 7 and the combustion chamber 7a on the air side. The air throughput 3 of the fan 11 can be used either for an engine for propulsion or for an APU for pressurizing the compressed air systems and / or the air conditioning system. For this purpose, a fan 11 with a first compressor stage 5 and a second turbine stage 9 as well as a second compressor stage 6 and a first turbine stage 8 are coupled to each other and run on coaxial shafts with different rotational speeds. The number of the coaxial shafts running in one another is arbitrarily designed.

p0014The sewage is collected in a collecting tank 28, partially or completely dehydrated 30 and the water fraction thus obtained is fed to the gray water collecting tank 32. It is of particular advantage,<ul><li>That the arrangement can also be operated without delivery of water to a water system,</li><li>That both the combustion chambers as well as the high-temperature fuel cells can be operated separately, also in any combinations with one another, and</li><li>In the case of separate operation of combustion chambers or high-temperature fuel cells 7, individual combustion chambers or high-temperature fuel cells can be switched off.</li></ul>