GB2119447A - Vapourising systems in jet propulsion or gas turbine engines - Google Patents

Abstract

A jet propulsion unit or a gas turbine unit includes a fluid boiler system, e.g. fuel boilers 4, operating to generate, under pressure, a vapour for at least partial use as the motive fluid. The boilers 4 are heated by hot tail pipe 3, around which they are coiled and are fed with liquid fuel through their lower ends and branch pipes 5, their vapour passing through their top ends to the combustion air compressor. Optionally, these boilers operate in combination with fuel boilers, e.g. the exhaust manifold heated unit 6, located elsewhere in the plant or even generate both fuel vapour and water steam quantities, which are finally mixed. <IMAGE>

Description

SPECIFICATION Improvements in or relating to, jet propulsion units In my previous designs for jet propulsion units and gas turbine engines employing for example, pressurized fuel vapour to compress or help compress the air fed into their combustors, the fuel boilers producing said fuel vapour are located only in or in manifolds downstream of the combustor zones of these plants. This limits the design of such units and engines to comparatively simple constructions having a low operating efficiency.

The object of the present invention is primarily, to improve the overall efficiency of such jet propulsion units and gas turbine engines, by utilizing alternative fuel boiler placings and arrangements.

According to a principal aspect of the invention, a jet propulsion unit or a gas turbine engine employing pressurized fuel vapour to compress or help compress the air feeding its combustor, comprises fuel boiler means positioned upstream or/and around hot assemblies placed downstream of its said combustor and deriving heat from a source or source, such as said assemblies, existing at said positions.

This invention is an improvement over the jet propulsion units and gas turbine engines described in my United Kingdom Patent Specification No. 7920585 and the systems and methods disclosed therein.

By increasing the choice of fuel boiler locations, multiple such boiler systems are rendered practical for use in these power plants and their employment as vapour superheaters, fuel preheaters, air compressor coolers, and the like, additional to their normal use exclusively as vapour generators.

Several examples will now be described with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic representation of a multiple fuel boiler system including two fuel boilers positioned around and heated by a tail pipe receiving the gas leaving the engine's combustor.

Fig. 2 is a diagrammatic axial section of a fuel boiler system including a fuel boiler placed around and heated by an air ejector receiving the hot gas leaving the engine's combustor.

Fig. 3 is a diagrammatic axial section of a ram air heated fuel boiler system placed in the engine's air entraining tube.

Fig. 4 is a diagrammatic representation of an alternative fuel boiler positioned around a tail pipe cum exhaust manifold, according to the invention.

In my aforementioned Patent Specification, I have described the placing of fuel boilers in or around the flame tubes of the plants and in their gas exhaust or discharge manifolds only. The use of the pressurized fuel vapour generated by these boilers is also exclusively as the motive fluid of the jet type air compression systems of these plants and as their fuel.

In other projected plants employing ram air heated fuel boilers, the use of the fuel vapour produced by these boilers, i.e. apart from its utilization for combustion purposes, is confined to feeding air compressor driving turbines. Such methods furthermore, are restricted by their disclosure only on hypersonic jet propulsion units.

The first example is a jet propulsion unit which exhausts the combustion gas produced in its combustor 1 Fig. 1, which may consist of one or more combustion tubes or chambers, through a manifold 2 and a tail pipe 3. Two convolute tubular boilers 4 in close contact with and heated by pipe 3, are supplied at one end and by branch pipes 5 with pressurized liquid fuel, such as oil fuel, which is vaporized and the vapour passed from the opposite end of said boilers to utilization in effecting compression of the air for combustion fed to combustor 1. Suitably shaped synthetic ruby, sapphire or ceramic brickwork may be provided to help conduct the heat from pipe 3 to the fuel boilers 4 and encase said boilers or they may employ square section tube for example, for this purpose. One or a multiplicity of such fuel boilers may alternatively replace the two units 4.A similar fuel boiler 6, heated by manifold 2, supplements the vapour supply by boilers 4.

Instead of the coiled tube fuel boilers 4, 6 or the like, the fuel boilers shown in Fig. 4 may be incorporated. Said fuel boilers comprise, in the top half of Fig. 4, an annular zig zag tube 7 and in the lower half of the figure, a ring of tube vaporizers 8 disposed longitudinally around tail pipe cum exhaust manifold 3 and connected at their opposite ends to an annular fuel supply pipe and an annular vapour collector 9. Both these boilers may be modified to suit for example, their placing in or around manifold 2, by tapering these assemblies.

The second example shows a coiled tube boiler 10 placed around and heated by an air ejector tube 11 in Fig. 2. The air tube 11 receives air drawn through vents 1 2 and combustion gas, which is the motive fluid displacing said air, expanding via a nozzle 1 3 from combustor 1 through said air tube. Optionally, the nozzle 13 may incorporate and be cooled by a similar fuel boiler heated by said nozzle and supplementing the vapour supply by fuel boiler 10.

The fuel boiler 14 Fig. 3 of the third example, is a coiled tube placed in the combustion air entrainment tube 1 5 of a jet propulsion unit and heated by ram air entering said tube 1 5. To obtain fuel vaporization at for example, sonic speed, a volatile liquid fuel, such as butane, may be supplied to boiler 14, but it is also practical to utilize said boiler assembly merely to preheat a heavier fuel supplied to a boiler unit placed for example, in the engine's combustor or in its air compressor, or to further heat said heavier fuel, for example by electrical means, following its partial heating in boiler 14, to induce its vaporization.

Gaseous fuel, such as butane, propane, hydrogen or liquid fuel vapour derived from e.g.

boilers 4 Fig. 1 , fed tb any of the fuel boiler assemblies described with reference to the drawings would only be superheated in these assemblies.

Fuel boilers, preheaters or superheaters of various other construction, such as multitubular units similar to fire tube steam boilers, fuel jackets positioned in or/and around combustion air compressors and nozzles, fuel supplied heat exchangers of any suitable design so acting, and the like, may be embodied in the manner I have described, to advantage.Another fuel boiler arrangement would comprise an ejector nozzle or nozzles, similar in design and method of operation to that of ordinary paint spray such nozzle(s), functioning partially as power nozzle(s) of a jet type combustion air compressor feeding the engine's combustor and supplied with hot air or combustion gas or a mixture of these fluids, led under pressure to said nozzle(s) from e.g. said combustor, and as their motive fluid, and liquid fuel or preheated such fuel, which would be vaporized by diffusion with said hot media and, with said motive fluid or hot media, expanded into the appropriate air compression duct(s) of said air compressor, leading to said combustor.

When the fuel boilers placed upstream or/and downstream of the power plant's combustor zone operate in combination with a fuel boiler or boilers, which might also alternatively form fuel preheater(s) or fuel vapour superheater(s), located in said combustor zone, the former units constitute only a part of the complete fuel boiler assembly.

The fuel boiler arrangements described may be employed to supply pressurized fuel vapour to operate both jet type and mechanical air compressors of jet propulsion units and gas turbine engines of various kinds, including driven fan and so called bypass jet propulsion units having either air compressor system, to advantage, it being possible to obtain a much greater fuel vaporization and consequently, an increased thrust or power output from comparable power plants using the present improved design.

By preheating the liquid fuel and superheating its vapour said fuel can be utilized more economically for the purpose of compressing the airfor combustion for example, giving a further improved overall efficiency in the plant.

Typical embodiments of the present invention employing mechanical combustion air compressors may comprise jet propulsion units according to any of the examples disclosed in United Kingdom Patent Specification No.

1,392,675 modified to incorporate my fuel boiler system, possibly at least combined with or including a combustor zone located such fuel boiler assembly.

A medium, such as water/methanol mixture, might be fed to for example, one of the boilers of a multiple fuel boiler system, the vapour so generated being mixed with the fuel vapour leaving the remaining fuel boilers, for cooling purposes in the combustor or economy of fuel vapour utilization in the air compressor of the plant.

Coiled tube fuel boilers receiving liquid fuel or the like, may optionally be fed with such fuel by pipe connections to the bottom of each coil and pass their vapour through similar pipe connections to the top of each said coil. In further coiled tube fuel boilers, the fuel vapour would be passed from each end of the coil forming the boiler and liquid fuel fed by a pipe connection, for example pipe 1 6 Fig. 3, to the bottom of the middle coil of said boiler, e.g. boiler 14 Fig. 3.

Since this invention is for power plants primarily according to my aforementioned Specification No. 7920585, said plants may employ a thermal cycle in accord with my copending United Kingdom Patent Application No.

8132375, as an alternative source of power. It also being practical to start the working cycle of such plants by first operating them on an internal combustion cycle and later feeding the secondary fluid to their boilers.

A specific closed circuit jet propulsion unit embodiment of such a plant comprises essentially the apparatus shown in Fig. 2, but in which secondary fluid vapour, such as water steam, directed to nozzle 1 3 from boiler 10, compresses the air drawn through vents 12. The mixture of said vapour and compressed air being then cooled in the divergency of tube 11 by boiler 10, which acts as a heat exchanger, and said vapour condensed, the condensate being fed back into boiler 10, for example by an ordinary injector, and the cooled air expanded via pipe 1 7 through vents 12. Due to its cooling and the condensation of its vapour content, the mixture in tube 11 is at a reduced pressure and a positive forward thrust is developed by the vapour jet expanding through nozzle 13, in excess of said mixture pressure.To help cool the air under compression in tube 11 and so reduce the air compression work, at least some of the vapour condensate can be mixed, for example by a ring of sprays, with the air stream entering said tube. Conversely, air may be excluded from tube 11 or a gas, such as carbondioxide, substituted for it. In the former case, only a portion of the vapour cooled in tube 11 may be condensed to liquid, the remaining uncondensed said vapour being passed back to vents 12; but not necessarily so. The boiler feed injector could be operated either by steam from boiler 10 or vapour from tube 11 or a jet pump, perhaps operated optionally by air or gas derived from said tube, may replace said injector. Other working cycles could employ a jet type compressor operated by air and steam mixture from boiler 10 or even compressed air or gas from tube 11, to feed the condensate and perhaps any air or gas left in said tube, into said boiler; or the vapour compressed in said tube may not be cooled to a liquid state or only partially so and said cooled vapour, possibly mixed by a spray device with its condensate portion or liquid led for cooling purposes or to increase the mean density of said vapour, from boiler 10, and any air or gas working fluid, fed back into said boiler in which, owing to its high pressure and cooling it, said vapour, would liquefy, by e.g. said jet type compressor. Turbine driving such examples would include a turbine or turbines interposed in any of the working fluid streams and rotating for example, an airscrew or a fan displacing ambient air.The boiler 10, which, in the appropriate examples, would pass mixed air or gas and vapour fluid to nozzle 13, necessarily functions at a critical working temperature below which the unit's thermal cycle is ineffective.

Although the use of combustor located fuel boilers is disclosed only on embodiments of this invention, the employment of such fuel boilers to supply pressurized fuel vapour to drive turbo air compressors effecting the compression of for example, the combustion air of jet propulsion units and gas turbine engines according to this invention, does not exclude their possible exclusive use for this latter purpose and the supply of fuel vapour for combustion to the combustors of such units or engines of alternative design.

Conversely, ram air heated fuel boilers of the kinds disclosed may exclusively or combined with, for example, tail pipe or combustor located and heated such boilers, supply pressurized fuel vapour to jet type air compressors for use as the motive fluid of said air compressors in effecting the combustion air compression and as combustible fuel.

Suitably enclosed powdered similar heat conductive material or metals, such as sodium, tin, zinc, aluminium or alloys, which would melt at the working temperature of the fuel boilers, might replace the brickwork described surrounding said fuel boilers. The latter materials have the advantage that they would convey heat by convection, when molten. The invention however, also comprehends the placing of the fuel boilers 4 Fig. 1 in tail pipe 3 and their direct heating by the combustion gas flowing through said pipe, which might embody a recess or recesses for housing said boilers or such units replacing them, for example the alternative fuel boilers shown in Fig. 4.

The fuel vapour superheating, in another example, is accomplished by mixing said vapour in a conduit or an ejector not shown, with combustion gas derived from the combustor or from the combustion of some of said vapour by admitting compressed air to said conduit or e.g.

atmospheric air to said ejector, which could be powered by the fuel vapour. Preferably, the fuel vapour superheater would be a gas generator unit in accord with my United Kingdom Patent Specification No. 946,443 and powered by some of the superheated vapour or this vapour mixed with the combustion gas effecting its superheating in said unit, which would increase the pressure of the superheated vapour or mixture for delivery.

Liquid air or oxygen can be supplied to the combustors of examples through sprays variously located, e.g. in said combustors or in the air supply tubes of the air compressors feeding them with their combustion air, to ensure maximum fuel combustion capability at high altitudes or in space.

Turbine equipped embodiments for example, may drive airscrews, fans or the like, either directly or through power transmission devices, such as a gearbox or an electric, pneumatic or a hydraulic torque unit incorporated in the apparatus.

My aforementioned Patent Specification No.

7920585 is published under the Serial Number 2021201.

According to the invention, a jet propulsion unit or a gas turbine engine further comprises boiler means, such as described for use as fuel vaporizers, adapted to vaporize a secondary fluid, such as water, the vapour so generated being utilized, under pressure, to compress a primary fluid, for example air, utilized to heat said boiler means vaporizing said secondary fluid.

In modififications of the various methods disclosed for vaporizing fuel or superheating its vapour by mixing said fluids with combustion gas, water steam or fuel vapour generated, for example, in one of the boilers 4 Fig. 1, may replace said gas as the heat source.

The invention may be applied to many designs of jet propulsion units and gas turbine engines, for instance such units and engines including fuel vapour or mixed such vapour and combustion gas or water steam driven turbines or other kinds of mechanical power units, such as piston engines so driven, producing auxiliary or main power are contemplated. Furthermore, the utilization of fuel vapour or said mixtures in this way is understood to not be restricted to use exclusively with such plants according to this invention. Either a part or the whole of said fluids could be fed to said mechanical power units, which could exhaust directly into the combustor of the plant or through the power nozzle or nozzles of its, said plant's jet type air compressor, into said combustor.In all cases the use of the fuel boilers placed elsewhere than in the zone of the combustor could increase the effective internal volume of the combustor and render practical a reduction in its size and weight.

The absence of or reduced heat loss to the fuel boilers of the appropriate gas turbine engine examples, from the combustion products feeding their turbines, would also give a higher thermal efficiency in these engines.

The vents 12 Fig. 2 can serve as breathers communicating with the ambient atmosphere, in all air breathing examples. In "closed system" jet propulsion such units, the cooled compressed fluid passed from tube 11 may advantageously be expanded through a second heat exchanger acting to reheat said fluid, by carrying out a part of the cooling of the compressed mixture in said tube or by cooling e.g. the hot condensate leaving it, during its passage back to vents 12, in the relevant cases. Inert gas, such as nitrogen, can advantageously replace the air working fluid in such units.

The ejector fuel boiler systems described may alternatively employ hot air, perhaps in compressed form, as their heating and operating medium. The combustion air compression in all such examples, would only be partially effected by the fuel vapour. Such hot air fuel boilers could be incorporated in my hot air powered jet type air compressors and related systems, e.g. that shown in Fig. 2.

During very high speed flight, the liquid fuel might advantageously be vaporized only by the ram air heated fuel boilers disclosed, for example by the such unit 14 Fig. 3, to fully cool said air.

The iongitudinal and lateral attitude control of an aircraft equipped with any of the jet propulsion units described, during ordinary flight or e.g. when landing or taking off vertically, could conveniently be achieved by regulating the fuel supply to and therefore, the thrust exerted by such embodiments of either main or auxiliary kind suitably placed in its airframe, or/and by the rotation of their thrust nozzles or even the complete engines which, in this last instance, could be mounted on trunnions or on gimbals, and like means.

In other systems, a liquid metal fuel, such as heated sodium, lithium or potassium is supplied to the fuel boiler(s), possibly also employing water injected either directly into said fuel boiler(s) or the combustors or into the air fed into the combustors, as an oxidant. These latter methods would utilize a working cycle in which a hydroxide of the metal and hydrogen would be formed by the reaction of the liquid metal and water mixture, the hydrogen so produced being ignited or self ignited and burnt in the combustors, so producing steam, and the mixture of steam and hydroxide being ejected from the combustors to use, e.g. in exerting thrust or partially as recycled oxidant.It is practical furthermore, to superheat the mixture of hydroxide and hydrogen produced in one fuel boiler section by feeding it into another such boiler section and to heat the fuel boiler or boilers partially or exclusively by the heat generated by the reacting metal fuel and water supplied to said boiler(s), heat from the walls of which or obtained from any other source by a preheater, could be passed to the fuel and to the water oxidant prior to their admission to these boiler(s), which would act partly as reaction vessel(s) in these examples and may merely be simple chamber(s) heated solely by the fuel oxidation, which may or may not be complete therein, effected by the injected water.

The utilization of the mixture leaving the fuel boiler(s), for example to feed an air compressor driving turbine or thrust nozzles, such as are disclosed in the aforementioned Specification No.

1.392,675, before the combustion of its hydrogen content is anticipated, as also is the use of my method of directly injecting both a liquid metal fuel and its oxidant water into reaction vessels and the utilization of said mixture, with or without the combustion of the hydrogen, in heat engines which are not embodiments of the present invention, such as two and four stroke internal combustion piston and rotary engines employing, as appropriate, air or exhaust mixture inspiration or, in said two stroke cycle engines only, merely the reuse of the said mixture left in their cylinders after the exhaust emission, no cylinder scavenging being necessary, and steam type engines of single or double acting piston and cylinder kind employing direct fuel and water injection into their cylinders, which could be provided with reaction chambers or cavities at their end(s), or into separate reaction vessels feeding said mixture to their cylinders. This however, does not preclude the possible usage of at least some of the metal fuel vapour from fuel boilers as a propellant or as the motive fluid of auxiliary power plants or the like, and the injection of the metal fuel into air compressor power fluid supply conduits acting as fuel boilers and in which oxidation of said fuel could occur due to its mixing with combustion products conveyed by said conduits, containing water steam, or the supply of fuel and oxidant water or vapour to the ejector nozzle fuel boilers disclosed.The fuel and water supply to the fuel boilers or the combustors may or may not be in finely divided form and can be pressurized by any of the means used to feed oil fuel into the fuel boilers of appropriate embodiments, such as a mechanical pump system or ordinary injectors operated by some of the fluid generated in the fuel boilers. Water steam used as an oxidant can be obtained for example, from one of the boilers 4 Fig. 1. In two stroke piston engines such steam could, by admitting it under its own pressure to their cylinders, also scavenge said cylinders, to which it could be led from an exhaust gas heated boiler, a cylinder cooling system or the like. The steam chests of adapted steam engines could act as their reaction vessels and be fed with metal fuel and oxidant in continuous or intermittent fashion.

The air cooling of reaction vessels is practicable.

Vessels, such as ships, can be jet propelled by ejecting the propulsion fluid of adapted aircraft engine embodiments, through a nozzle or tail pipe system, for example rearwards, below the water level.

Hybrid power plants partly employing my hot tube or chamber working cycle are practical and preferably may utilize synthetic sapphire or ruby or such material filled, encased or coated venturi tubes or chambers, inclusive of hollow turbine blade assembly formed such tubes.

Finally, I provide fluid boiler means, such as I have described with reference to any of the drawings, operating to cool an air compressor or the like, and generate the pressurized vapour or steam employed to power or drive said compressor, from which the compressed fluid and perhaps said vapour or steam is passed to utilization, for example in a turbine, a thrust producing nozzle or tail pipe or/and a combustor.

Preferably, the heat withdrawal from the compressor is in two stages, to a circulating molten metal coolant and thence to the fluid boiler means.

Liquid metal fuel is stored under fuel or oil vapour and heated by the former medium which, in this method, is bypassed, for example from a fuel boiler or a turbine exhaust manifold, for said purpose. Other methods for heating the metal, which are to maintain this fuel in a liquid state, are the provision of an electric heating device immersed in it or a heat exchanger fed with hot air or combustion products and acting to maintain its operating temperature.

My Specification 8035184 is now proceeding under Application No. 81 32375 (Publication serial No. 2086483).

In closed system examples according to Fig. 2, condensed vapour or mixture fed back into boiler 10 from tube 11, which is closed by line 18 in this instance, is evacuated from said tube by pipe 1 9.

Claims (11)

1. A jet propulsion unit or a gas turbine engine inclusively comprising fluid boiler means, such as extra or alternative oil fuel boilers placed upstream or/and downstream of the said unit's or engine's combustor and operating, separately or in combination with combustor positioned such boilers, to generate fuel vapour, under pressure, for utilization partially as the motive fluid of said plants' combustion air compression devices or their driving means, as hereinbefore described with or without direct reference to the drawn examples provided.

2. Plant according to Claim 1, comprising fluid boiler means operating to generate vapour or mixed vapour quantities, such as water steam and fuel vapour mixture, or/and to superheat said vapour media or/and to preheat the liquid medium or media supplied to said vapour generating section of said means, said superheating optionally being effected by an ejector air or combustion gas mixer diffusing these fluids with said vapour quantities, for said purpose, in the former case said vapour fuel being partly burnt in said air, or by a gas generator unit in accordance with my U.K. Patent Specification No. 946,443.

3. Plant according to Claim 2, comprising fluid boiler means utilizing, in continuous operation, heat derived directly or indirectly from combustion products or from compressed combustion air, pressurized air, vapour, inert gas or mixture working fluids, electrical heating devices or/and at least partially, ram said air fluids, or from combinations of such sources.

4. Plant according to Claim 3, comprising fluid boiler means operating to generate a vapour quantity or quantities for utilization, as motive fluid, in jet type or mechanical fluid compressor systems effecting the compression of the air for combustion or the working fluid, said vapour being liquid fuel or/and non-fuel liquid derived, said means being placed for example, forward or/and rearward of the combustor, in said position(s) and in said combustor, or in said working fluid compressor assemblies, in other instances said vapour being hydrogen, butane, propane or mixed media, merely superheated, or any alternative gaseous fuel.

5. Plant according to Claim 4, comprising fluid boiler means consisting of one or more combustion air compression fluid jets also acting to heat and vaporize liquid fuel, which may be an additional such fuel quantity, mixed with said fluid jet(s) and to feed the products of this process and said combustion air into the combustor, said means, in specific instances, having a provision to oxidize or partly oxidize a metal such fuel by diffusing water or water steam, which latter fluid may form said jet(s), with said metal fuel quantity, said fluid jet(s) comprising combustion gas, hot air, fuel vapour, said water steam or a mixture of hot air and combustion gas.

6. Plant according to Claim 4, comprising combustor placed fuel boiler means acting to generate vapour for utilization as motive fluid in combustion air compressor driving turbines.

7. Jet propulsion plant according to Claim 4, comprising ram air heated fuel boiler means operating to generate vapour for utilization in jet type combustion air compressors, as their motive fluid.

8. Plant according to Claim 4, comprising fluid boiler means as hereinbefore described with reference to Fig. 2 of the drawings.

9. Fluid boiler means according to Claims 4, 6 or 8, comprising one or more liquid fuel fed assemblies having, in the appropriate instances, a provision also for the injection or admission thereto of oxidant liquid or vapour and operating to to vaporize said fuel or/and to oxidize or partly oxidize a liquid metal such fuel quantity, the products of these processes thereafter being utilized, said liquid metal and its oxidant feed being either continuous or intermittent, said liquid fuel being partly or exclusively a metal quantity, such as sodium, heated by fuel vapour, combustion gas, hot air or electrical means to a liquid state prior to its use, said oxidant media optionally being preheated or vaporized by said I means, said oxident vapour alternatively being combustion products derived.

10. Plant according to any preceding Claim, comprising fluid boiler means consisting of one or more additional or alternative tubular, multitubular, fluid jacket, mixing nozzle, air compressor conduit, simple chamber or heat exchange units, such as those described with reference to Fig. 4, incorporated in air or other working fluid compressor nozzles or systems, combustors, tail pipes or manifolds, air or other working fluid ejectors and nozzles or in combinations of these devices, said tubular fluid boiler means optionally comprising square section tube or being encased in heat conductive material, in one instance, molten at its operating temperature and transferring heat by convection, said several fluid boiler units being connected as a multiple assembly or in series, said tubular fluid boiler units constructed as coils, having end or/and centre coil fluid feed.

11. A jet propulsion unit or a gas turbine engine incorporating a fluid boiler means designed, constructed and operating substantially as hereinbefore described with reference to Figs. 1 to 4 of the accompanying drawings.