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Title:
FUEL TANK INERTING
Document Type and Number:
WIPO Patent Application WO/2017/207069
Kind Code:
A1
Abstract:
The present invention relates to an air separation module for an aircraft inerting system. The air separation module comprises an inlet for receiving a source of air, a first outlet for exhausting nitrogen enriched air and a second outlet for extracting oxygen or oxygen rich air. The air separation module also comprises at least one magnet configured to induce a magnetic field between the inlet and outlets, thereby providing a motive force to oxygen passing through the air separation module to divert oxygen modules toward the second outlet. In use, the oxygen separation can be adjusted by using a feedback system. Advantageously, whilst the air separation module described herein provides an alternative to existing modules, it can also be of benefit as an additional system.

Inventors:
PANKAJ, Shireesh (L3-701, Bramha Sun City,Wadgaon Sheri, Pune 4, 411014, IN)
GUPTA, Swarnim (502 Tower 2, Gera Trinity,Trinity, Kharadi, Pune 4, 411014, IN)
JOSHI, Mahesh Prabhakar (Flat No. 104, Chintamani Building,Prasoon Dham, Survey No. 32,Thergaon, Pune 3, 411033, IN)
MASSEY, Alan Ernest (18 Summerfields, LocksheathSouthampton, Hampshire SO316 NN, SO316 NN, GB)
BIRADAR, Pradeep (Gera Skyvilla, Tower 3,Penthouse 12, Near Eon IT Park,,Kharadi, Pune 4, 411014, IN)
Application Number:
EP2016/067458
Publication Date:
December 07, 2017
Filing Date:
July 21, 2016
Export Citation:
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Assignee:
EATON LIMITED (554 Abbey Park, Southampton RoadTitchfield, Hampshire PO14 9ED, PO14 9ED, GB)
International Classes:
B64D37/32
Attorney, Agent or Firm:
EATON IP GROUP EMEA (Route de la Longeraie 7, 1110 Morges, 1110, CH)
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Claims:
Claims

1. An air separation module for an aircraft inerting system, the air separation module comprising:

an inlet for receiving a source of air,

a first outlet for exhausting nitrogen enriched air and

a second outlet for extracting oxygen or oxygen rich air, and

at least one magnet configured to induce a magnetic field between the inlet and outlets thereby providing a motive force to oxygen passing through the air seperation module to divert oxygen modules toward the second outlet.

2. An air separation module as claimed in claim 1, wherein the at least one magnet comprises a plurality of magnetic elements. 3. An air separation module as claimed in claim 1 or 2, wherein the at least one magnet is configured to provide at least a first substantially constant magnetic field and at least a second magnetic field which is varied in use.

4. An air separation module as claimed in claim 3, wherein the first substantially constant magnetic field is a permanent magnetic field, which optionally in use provides a continuous rate separation action in the air separation module.

5. An air separation module as claimed in claim 3 or 4, wherein the second magnetic field is an electromagnetic field, which is optionally selectively or variably used to provide additional separation when additional capacity or higher purity of nitrogen enriched air is required.

6. An air separation module as claimed in any preceeding claim, wherein the at least one magnet comprises at least one permanent magnet and at least one electromagnet.

7. An air separation module as claimed in claim 6, wherein the at least one permanent magnet comprises an array of permanent magnets and the at least one electromagnet comprises an array of electromagnets.

8. An air separation module as claimed in any preceding claim, wherein the air separation module further comprises a duct extending from the inlet to the first outlet, the duct including a permeable duct wall. 9. An air separation module as claimed in claim 8, wherein the at least one magnet is disposed around the duct.

10. An air separation module as claimed in claims 8 or 9, wherein a conduit surrounds the duct, and the conduit being in communication with the second outlet.

11. An air separation module as claimed in any preceding claim, wherein the magnetic field is formed in a plurality of regions along the longitudinal length of the air separation module

12. An aircraft fuel tank inerting system comprising an air separation module as claimed in claims 1 to 11 and at least one feedback system is provided to adjust the oxygen separation during use, the feedback system includes at least one sensor and a controller.

13. An aircraft fuel tank inerting system as claimed in claim 12, wherein the air separation module or the inerting system further comprises a compressor for pressurising the air supply to the air separation module. 14. An aircraft fuel tank inerting system as claimed in claims 12 or 13, wherein the air separation module receives air from aircraft cabin air, and optionally the inerting system or air separation module comprises arrangements conditioning the air.

15. An aircraft comprising at least one fuel tank and an inerting system claimed in claims 12 to 14.

Description:
Fuel Tank Inerting

This invention relates to aircraft fuel tank inerting systems and air separation modules for use in such systems.

Aircraft fuel tanks are now subject to fuel tank flammability requirements (FAR25.981b}. As a result, a common approach to meeting this requirement is to provide an "inerting system" which is effective in reducing the flammable gas within the ullage space which exists above the fuel within each fuel tank. For example, inerting systems may comprise a system in which Nitrogen Enriched Air

(NEA} is generated by an On Board Inert Gas Generating System (OBIGGS} which is then pumped into the fuel tanks. Such systems generally utilise an Air Separation Module which generates NEA by passing air (for example bleed air] through a hollow-fibre permeable membrane.

It will be appreciated that the provision of any inerting system carries a direct weight and/or space penalty for the aircraft (which may result in decreased range and/or fuel efficiency}. Accordingly, there is an ongoing desire to provide improved or alternate inerting systems.

As such, the Applicants have proposed an alternative aircraft fuel inerting system and an air separation unit for use in an aircraft fuel system in UK Patent Application GB1522523.8 (the contents of which is incorporated herein by reference}. The fuel inerting system and air separation module of GB1522523.8 utilise a paramagnetic pump to separate oxygen from air.

Oxygen is a paramagnetic substance which is drawn towards areas of higher magnetic field strength. In contrast nitrogen, carbon dioxide and most hydrocarbon fuels are repelled by stronger magnetic fields. Thus, the applicants have recognised that this effect may be utilised to provide a selective motive force to oxygen in a fuel tank inerting system. By a selective motive force it will be understood that the embodiments of the invention seek to apply a motive force selectively to oxygen molecules in the gas of a fuel system but not to other components of the gas such as nitrogen or hydrocarbons (such as fuel vapours}. The applicants have now identified further improvements and features for use in an inerting system or air separation module which utilises paramagnetic separation of oxygen.

According to an aspect of the invention, there is provided an air separation module for an aircraft inerting system, the air separation module compromising:

an inlet for receiving a source of air,

a first outlet for exhausting nitrogen enriched air and

a second outlet for extracting oxygen or oxygen rich air, and

at least one magnet configured to induce a magnetic field between the inlet and outlets thereby providing a motive force to oxygen passing through the air seperation module to divert oxygen modules toward the second outlet.

Typically, the at least one magnet may comprise a plurality of magnetic elements. For example at least one array of magnetic elements.

The magnet may be configured to provide at least a first substantially constant magnetic field and at least a second magnetic field which may be varied in use. The first substantially constant magnetic field may be a permanent magnetic field. The second magnetic field may be an electromagnetic field.

The substantially constant magnetic field may provide a continuous rate separation action in the air separation module. The variable magnetic filed may be selectively or variably used to provide additional separation when additional capacity or higher purity of NEA is required. Thus, in an embodiment the at least one magnet may provide at least one permanent magnet and at least one electromagnet. The at least one permanent magnet may comprise an array of permanent magnets. The at least one electromagnet may comprise an array of electromagnets.

The air separation module may further comprise a duct extending from the inlet to the first outlet. As such a flow of air may be passed through the duct during use. The duct may include a permeable duct wall, for example a perforated duct wall. The at least one magnet may be disposed around the duct such that oxygen or oxygen enriched air is draw out of the duct through the duct wall. An conduit, for example an annular or substantially annular passageway, may surround the duct for receiving oxygen or oxygen enriched air. The conduit may be in communication with the second outlet.

In some embodiments the magnetic field may be formed in a plurality of regions along the longitudinal length of the air separation module (which it will be appreciated may generally corresponds to the longitudinal direction of the duct}. Thus, the magnet may provide a plurality of sections in the longitudinal direction.

The applicants have recognised that it may be advantageous to have the capability of providing a variable magnetic field along the longitudinal length of a system. For example it may be desirable to provide a gradient to the magnetic field or to pulse the magnetic field. For example, the field could be graduated by using sections along the length of the air separation module or by providing a plurality of air separation modules in series.

According to a further aspect of the invention, there is provided an aircraft fuel tank inerting system comprising an air separation module in accordance with an embodiment and at least one feedback system is provided to adjust the oxygen separation during use. The air supply to the air separation module may be pressurized. Accordingly, the air separation module or inerting system may further comprise a compressor, for example a turbocharger or supercharger, for compressing the air prior to the air being provided to the inlet of the air separation module.

The feedback system may include at least one sensor for example to measure the oxygen content or flow rate of the output of the air separation module. The feedback system may include a controller for controlling the operating speed of the compressor.

The air separation unit may receive air from aircraft cabin air. As such the inerting system or air separation module may further comprise arrangements for conditioning the air. For example filters may be provided for dust removal and/or biological waste. Dehumidification arrangements may be provided to reduce the moisture content of the air.

The skilled person will appreciate that whilst the air separation module, in accordance with embodiments of the invention, may provide an alternative to existing air separation modules; it may also be of benefit as an additional system. For example embodiments of the invention could be used to either reduce load on the existing inerting system or to allow increased efficiency of the inerting system during peak demand (for example during the descent phase of an aircraft operation}.

According to a further aspect of the invention, there is provided an aircraft comprising at least one fuel tank and an inerting system in accordance with an embodiment of the invention. Whilst this invention has been described above, it extends to any inventive combination or sub-combination of the features set out above, in the formal description or the claims or the drawings. By way of example only, embodiments of the invention will now be described in detail with reference to the accompanying drawings in which:

Figure 1 is a schematic representation of an aircraft including a fuel system having a fuel inerting system;

Figure 2 is a schematic representation of the paramagnetic effect on a gas

Figure 3 is schematic block diagram representing an inserting system in accordance with an embodiment;

Figure 4, is an external view and a longitudinal cross section of an air separation module in accordance with an embodiment.

Figure 5 is an exploded representation of a section of the air separation unit in accordance with an embodiment.

Figure 6 is a representation of a fuel tank inerting system including a feedback loop in accordance with an embodiment; and Figure 7, shows an air separation unit in accordance with a further embodiment of the invention;

Figure 8 is a transverse cross section through the air separation module of figure 7; Figure 9 is a detailed representation of features of an air separation module in accordance with an embodiment; and

Figure 10 is a detailed cross section of an air separation module in accordance with an embodiment illustrating the operational principle.

A typical fixed wing aircraft 1 is illustrated schematically in figure 1. The aircraft includes a fuel system 10 having a plurality of fuel tanks 12. The tanks 12 are which are vented via vent tanks 13. The vent tanks allow air to be drawn into the fuel tank as the fuel is consumed and as a result of changes in the external atmospheric pressure (for example in ward venting during decent of the aircraft}. An inerting system 100 is provided in fluid communication with the fuel tanks to reduce the flammability of the gas within the ullage space above the fuel.

Embodiments of the invention are based upon the paramagnetic effect in which certain substances, including oxygen, are attracted towards higher magnetic fields strengths. This effect is illustrated schematically in Figure 2 which shows how air may freely flow between magnetic field generating elements (represented by poles

N and S] when the magnetic field is not present. However, when the magnetic field is present, oxygen is attracted to the magnetic field between the poles. Other substances which are repelled by stronger magnetic fields, such as nitrogen and hydrocarbons, are repelled from the air gap between the poles.

As shown in the diagram of figure 3, embodiments of the invention relate to the design of an air separation module, intended to separate Oxygen and nitrogen from air. Specifically, this embodiments of the invention relate to a modular design of air separation system, to be used in aircrafts or other similar applications. Embodiments system has multiple sections of magnetic field, which can be assembled sequentially based on requirement. A representative image of three stage air separation module is shown in figure 4. The air separation module 200 in accordance with embodiments has sections for air inlet 250, followed by regions of magnetic field, and two outlet ducts 260, 270. The central three regions of the module have magnetic field induced either through permanent magnets of electromagnets. The section 280 is a representation of wires (used to create magnetic field], and the further region 210 is a core duct which is shown in further detail in figure 5.

The magnetic field generated is between the two slots 220, 230. The induced magnetic field attracts oxygen in the outer zone and nitrogen is repelled into the innermost tube 210 (perforated tube}. The perforations are intended for air to pass through.

Based on specific requirements, multiple such modules can be placed sequentially. To enhance the separation efficiency, the magnetic field strength in each region can increased sequentially. A gradient magnetic field could also be introduced in the system. Additionally, pulsating magnetic fields/ variable fields is also a possibility depending on the purity of the nitrogen required.

Construction of the same could also be realised using permanent magnets.

2

As shown in Figure 6, embodiments of the invention may be utilised in an intelligent system by the addition of feedback loops. This leads to increase in system efficiency and air supply based on need. The air circulation for magnetic separator (Paramagnetic pump] is governed by a compressor (say, a supercharger}. The paramagnetic pump sits at the suction side of supercharger. The nitrogen enriched air parameters, specifically purity and flow-rate, can be measured. Based on requirement (dependent on stage of flight], the rpm of supercharger and strength of magnetic field can be varied. The feedback provided can lead to variation in nitrogen enriched air quality, thus completing the feedback loop. An alternate embodiment of an air separation module 300 in accordance with the invention is shown in figure 7. The module includes sections for air inlet 350, followed by regions of permanent magnetic field or porous magnets 305 and electro-magnet field 306 and two outlet ducts 360, 370. The central three regions have magnetic field induced either through permanent magnets or electromagnets. The section 380 is a representation of wires (used to create magnetic field], and the darker region 310 is representative of core, a detailed cross section through which is shown in Figure 8.

In preferred embodiments at least one section comprises permanent magnet and at least one further section comprises electromagnets. The permanent magnet separates gas all the time at constant rate. While electro magnets can provide additional capacity and purity, required during different phases of flight (e.g. descent of flight}. As best seen in the transverse cross section of figure 8, the magnetic field generated is between the two slots 320, 330. The resulting induced magnetic field attracts oxygen in the outer zone and nitrogen is repelled into the innermost tube 310. The inner tube is provided with perforations which are intended for air to pass through.

The basic operation of an embodiments so shown in figure 9. Air entering through the inlet 450 includes both nitrogen molecules N and oxygen molecules O. A magnetic field M is generated in an outer region of the air separation module and attracts oxygen molecules O though the perforated wall of the inner duct into an outer annular generally annular and coaxial passageway within the magnetic field region M. At the distal end of the air separation module from the inlet the inner passage is exhausted via a one outlet 470 and the outer region through a separate outlet 460. Due to the magnetic field effect the gas exiting the outlet 460 is oxygen rich and the gas exiting the outlet 470 is nitrogen rich. A detailed construction of an embodiment is shown in figure 10. The major components of the air separation unit are an inner "Axel" 510 and outer "stator" 550. Both components are formed with profiled projections which are configured to receive respective windings 515, 555 so as to allow the provision of electromagnets. As shown schematically, in use the windings form a magnetic field, illustrated by field lines M and extending across the annular space between the inner and outer components. The result of the magnetic field M is that nitrogen molecules N are repeller towards the inner bore and oxygen molecules O are attracted into the annular passageway between the components. Based on requirement, multiple air separation modules in accordance with embodiments can be placed sequentially. To enhance the separation efficiency, magnetic field in each region can increased sequentially. Gradient magnetic field could also be introduced in the system. Additionally, pulsating magnetic fields/ variable fields is also a possibility depending on the purity of the nitrogen required.

The advantages of the embodiment of the invention may for, example, include: no moving parts

reduction in weight

- ability to perform in low temp and pressure environment - modularity to expand the system

low power consumption (as compared to membrane based ASMs] higher efficiency (>95%] as compared to membrane (>90%]

longer life

- no wear and tear of components

intelligent system with feedback control Although the invention has been illustrated above with reference to its preferred embodiments, it will be appreciated that various changes and modifications may be made without departing from the scope of the invention as defined in the appended claims.