GB2086483A - Plant vaporizing a secondary fluid using heat of compression of a primary fluid. - Google Patents

Abstract

Air and water mist mixture is compressed, e.g. by jet type compressor 2, and fed into a receiver where dry steam is generated using the heat of compression, at or above a critical minimum temperature level. After superheating by diffusion with said compressed air, the steam may be directed via outlet 3 to an expansion engine. Receiver 1 also acts as a reservoir for the water supplied to air compressor 2. A modified plant may be used for jet propulsion. <IMAGE>

Description

SPECIFICATION Improvements in or relating to heat engines In a conventional steam generating plant, the vaporization of fluid in its boiler is induced by heat derived from combustible or atomic fuel, applied to said boiler. Internal combustion engines also burn fuel to produce heat which they convert into mechanical work. This dependency on heat derived from fuel limits the use of such plants and engines, according to the availability of the fuel.

This invention has for its object a process for improving thermal plants and use in partly thermal plants, avoiding their dependency on heat obtained from fuel combustion or atomic reaction or similar sources, and plants employing said process.

Above the region of 250"F the evaporation of water increases more rapidly than its temperature and it is assumed that other evaporating liquids probably behave in a similar general manner. Steam plants working at high evaporation temperatures may, therefore, be efficient enough to employ new heat sources.For example, it could be deduced that adapted internal combustion engines, such as gas turbine engines, ram or turbo jets and two orfour stroke piston engines might enlist steam formation at a suitably high temperature as their source of power simply by using the heat of the air compressed by their air pressurizing means to effect such steam formation, e.g. by mixing a proportion of atomized water continuously or at intervals respectively, with said hot compressed air; or that ordinary steam turbine plants could employ compressed air as their heat source, using either a conventional steam generator or a mixed steam and compressed air system and a mechanical air compressor driven for example, by the plant's low pressure turbine, or a jet type unit, the adiabatic efficiency or which can be improved by adding feed water to its air supply, thus at least further enhancing the performance of said plants.

According to one aspect of the invention the process consists in the compression of a primary fluid, such as air, the utilization of said compressed primary fluid to heat and vaporize a secondary fluid, for example water, at a predetermined temperature, and the expansion of the vapour so generated our a mixture of it and said primary fluid, in a device or devices, such as a nozzle or/and a turbine, or/and heat transference from any of said fluids or fluid mixture in a heat exchanger.

According to another aspect of the invention, the process consists in the compression of a primary fluid, such as air, in a jet type compressor, at a pressure determined partially by the average density of said primary fluid and a heavy secondary fluid mixed with it, mixing said heavy secondary fluid with the primary fluid during its entrainment by said compressor, to increase the delivery pressure of said fluid mixture, optionally the recovery, cooling and recycling of said secondary fluid from said compressed mixture, and the expansion of said compressed mixture or/and the remaining pressurized primary fluid in a device or devices, such as a nozzle or/and a turbine, or/and the transfer of heat from any of said fluids or storage of said compressed primary fluid.

Reference will now be made to the accompanying drawing illustrating different embodiments of this invention.

The example shown in Figure 1 comprises a vessel 1 containing and operating to vaporize water and pass most of the vapour and compressed air, which is fed into said vessel, to heat said water and superheat said vapour and mixed with it, by a jet type air compressor 2, through an outlet pipe 3 to utilization in for example, an expansion device, such as a heat engine, or a condenser, such as a heat exchanger. The vessel 1 operates at a temperature sufficiently high to ensure a vaporization pressure or rate above the rise in said temperature necessary to achieve said pressure or vapour formation rate i.e.

250 degrees Fahrenheit or above. Some water is passed from vessel 1 by a pipe 4 and mixed with the air entrained by air compressor 2 via a dust filter 5, to cool said air compressor and incease its efficiency by increasing the density, by humidifying said air, of the fluid delivered by said compressor, which is operated by a portion of the vapour and air mixture, directed to it by conduit 6, from vessel 1. A clack 7 prevents the return of fluid to air compressor 2 upon stoppage of this compressor, from vessel 1 through its air supply line, but this is an optional provision.

Compressed air can be supplied to vessel 1 or directly by pipe 8 to air compressor 2, by an auxiliary air compressor or an air vessel not shown, when starting the working cycle of the plant and its air compressor. If desired, cold feed water can be mixed with the air entrained by air compressor 2, thus avoiding the need for an alternative supply means for vessel 1. Instead of the arrangement shown in the drawing, the compressed air may be fed into vessel 1 at a point below its water level or passed through a heat exchanger, for example a multitubular or coiled tube such unit incorporated in said vessel and acting to heat it and its contents and possibly to superheat its vapour separately. In this latter method of operation, the compressed air leaving the heat exchanger could be expanded through a separate device or mixed with the vapour in vessel 1.

A process according to the invention therefore, further consists in the separate utilization of the generated vapour and the used pressurized primary fluid.

Superheating of the vapour from vessel 1 may be preferred to be carried out by a heat exchanger embodied for this purpose and fed with said vapour and the hot air leaving air compressor 2. This superheater would be interposed in the air delivery line between vessel 1 and air compressor 2, which may also be required to be replaced by a mechanical unit, or embodied in vessel 1 or in an equivalent assembly perhaps provided, such as a coiled tube or multitubular air and water fed boiler. A coiled tube vessel fed with water could be enclosed in a hot chamber with its superheater and heated by compressed air led into said chamber from e.g. air compressor 2. The provision to mix water with the air entrained by this air compressor is not essential to its operation and might be omitted in this example.

Waste heat may be recuperated in the cycle by directing exhaust vapour or its condensate back into air compressor 2 for example, in e.g. turbine or heat exchange installations.

It may be advantageous to use a volatile secondarky fluid in vessel 1, such as liquid air or nitrogen or liquid carbon-dioxide or one of the various refrigerant liquids in common use, boiling at a comparatively low temperature. Said secondary fluid might, in other examples, be oil fuel or liquid hydrogen, the vapour from which could finally be burnt in the combustor of a heat engine, which could also receive the spent air or primary fluid, discharged to expansion from an appropriate boiler unit not mixing said vapour and said primary fluid for heating.

To facilitate starting the working cycle of the apparatus, air compressor 2 or clack 7 may incorporate an overflow or bypass to atmosphere, which could be opened during said starting period, to release excess air.

The hot primary fluid fed into vessel 1 would preferably be discharged into said vessel through a diffuser, such as a tube coil perforated throughout its length, placed in said vessel above or below its water level.

The primary fluid may be merely exhaust vapour when the plant employs a closed working fluid circuit or a mixture of vapour and a different gaseous medium. The liquid air possibly present in vessel 1 would itself be heated by the airfed into said vessel, any of said liquid air lost by vaporization being perhaps replaced by condensation of said primary fluid, an effect which may be encouraged by with- drawing heat from said liquid air by a small cryostat.

The process may be used by gas turbine engines, jet propulsion units and adapted internal combustion piston engines merely by substituting for example, water for the oil fuel normally supplied to these engines. This water would be vaporized by the air or superheated exhaust vapour primary fluid compressed in such engines and the mixture of steam and primary fluid expanded to drive the engine and generate useful energy. Water could be condensed from their exhaust mixture and recyled through the engines, in suitable examples. Adapted internal fuel combustion engines and hybrid units of various other kinds may employ the process, similarly.At the operating temperature of such examples, the expansion ofthe primary fluid and vapourwould exceed any condensing of said primary fluid caused by its heat loss to the secondary fluid, thus said mixture could either increase in volume without a corresponding pressure drop or increase in pressure at its existing volume, depending on the kind of installation concerned.

The delivery pressure of air compressor 2 is largely dependent on the density of the mixture of air and water entrained by said air compressor; it is practical therefore, to increase its efficiency and reduce its power fluid requirement by increasing said density, e.g. by increasing the water content of said mixture.

Referring again to Figure 1, this apparatus may employ a cycle in which the water in vessel 1 is continuously cooled by circulating it through a radiator 9 and is not allowed to boil, thus increasing the effective density of the mixture under compression in air compressor 2 by reducing the evaporation of its water content. Compressed air mostly would be passed from vessel 1 through pipe 3 to utilization or storage and by conduit 6 to air compressor 2, in this example. Alternatively, the water supplied to air compressor 2 may be derived from another source and this water passed from vessel 1 to utilization in a hydraulic motor or device or waste, the radiator 9 being unnecessary perhaps, in this instance. The water could be circulated through radiator 9 by a pump or convection. A water filter may be provided in the waterfeed line of air compressor 2.The plant may also function as a fluid pump by exhausting either its air orwaterto e.g. waste. Various hydraulic and gaseous fluids could be pumped in this way. The compressed air, which is cooled by the cold water mixed with it during its compression, debouching through pipe 3, can be reheated by leading it through radiator 9 or a similar device fed with said air and the hot water from vessel 1. If a volatile liquid, such as liquid air, replaces the water in vessel 1, radiator 9 may be additional to a cryostatic cooling means embodied to regulate the temperature of said liquid air.

The air compressor 2 can be equipped with a cooling jacket fed with the cold secondary fluid for mixing with the air entrained by said air compressor prior to said mixing, which may be carried out by a spray or an atomizing arrangement. Any of this liquid left in mist form in the gases led to pipe 3, could be removed by passing said gases through a filter incorporated in the inlet of said pipe.

Waste heat from an embodied cryostat or cooling device can be utilized in heat exchangers operating to reheat or/and superheat the gases conveyed through pipe 3.

The secondary fluid lost from vessel 1 by vaporization, may be replaced by the first fluid condensed in said vessel, providing the temperature of said first fluid is not excessive upon its admission to said vessel, without appreciable heat withdrawal or application respectively, from and to said secondary fluid.

Some of the first fluid may be fed into vessel 1 at a point or points below its secondary fluid level to enhance said first fluid condensation by the cooling action of the secondary fluid.

Superheating ofthe mixture debouching through pipe 3 is additional to any such heating of the vaporized secondary fluid in vessel 1. Optionally, said mixture may be superheated by directing some of the not compressed primary fluid through a bypass into pipe 3, or this superheating may be induced by a heat exchanger to which said mixture could be led, heated by compressed air fed to it by a jet type air compressor operated by the superheated mixture itself, the mixed superheated fluid and air leaving said heat exchanger being utilized for power generation.

A process according to the invention therefore, still further consists in the utilization for power generation purposes, of a mixture of the primary fluid and the vaporized secondary fluid with additional compressed air used to superheat the mixed primary fluid and secondary fluid vapour.

A perforated baffle 10 prevents the excessive heating of the water in vessel 1 by the primary fluid, and increases the superheat.

A supply of water to vessel 1 through a pump or an ordinary injector may be used to replace the water evaporated from said vessel, which may also need to be thermally insulated, for example by the employ ment of a double wall separated by an air space or a space from which the air is evacuated, in its construction, where desired.

The air compressor 2 may be preferred to be operated by some of the superheated mixture, where such a superheating provision exists, but the invention furthermore comprehends the use of a gas generator unit in accordance with my United Kingdom specification No. 1,100,903 to compress the primary fluid feeding vessel 1, or even the relative wind in a jet propulsion unit embodiment, or the momentum of recycled exhaust fluid, detrained for example, by an embodied turbine.

Even in embodiments in which the water in vessel 1 is prevented from boiling, some vaporization of the water mixed with the primary fluid under compression would occur in practice, and such installations would therefore function at least partially by the vaporization of the secondary fluid by the heat of the primary fluid. This may have to be taken into account in the design of such plants working at high pressure, where this vapour formation may be considerable, if the removal of said vapour is required.

The secondary fluid lost from vessel 1 by vaporization may be replaced by the primary fluid condensed in said vessel, providing the temperature of said primary fluid is not excessive upon its admission to said vessel, without appreciable heat withdrawal or application respectively, from and to said secondary fluid. Some of the primary fluid may be fed into vessel 1 art a point or points below its secodaryfluid level, to enhance said primary fluid condensation by the cooling action of the secondary fluid. Recycled secondary fluid vapour can be condensed similarly in vessel 1,which may thus function both as an evaporator or boiler and as a condenser so replacing the evaporated secondary fluid.The preheating of vessel 1, for example by an oil or gas burner or an electric heater, to raise the temperature of its secondary fluid to boiling point before starting the plant's working cycle, may be advantageous where said fluid is of low volatility.

In an adapted internal combustion engine, its exhaust fluid could be passed into a condenser in which some of said fluid would be liquefied and the remainder re-entrained by the engine. Alternatively, a portion of its exhaust fluid would be re-entrained directly through a suitable bypass and the remainder only of said fluid led into a condenser for liquefaction or partial liquefaction or no condensation of said exhaust fluid may be required. In such an engine, the secondary fluid could be either mixed with the entrained or the re-entrained primary fluid, such as said bypassed exhaust fluid or re-entrained such fluid, for example by a spray, atomizer or a carburettor or by condensation only to mist, or injected by a pump, directly into the engine's cylinder(s) or heat expansion chamber(s).Desirably, the heating of the secondary fluid in said cylinder(s) or heat expansion chamber(s) (e.g. adapted flame or combustion chambers) by the compressed primary fluid, would be enough to superheat its vapour and to equal or exceed the minimum operating temperature level to obtain a greater vapour generation than the condensation of said primary fluid due to its heat loss, which is necessary in the engine's working cycle to produce useful work. The direct injection of secondary fluid into the hot compressed primary fluid in the cylinder of a piston such engine would, owing to said greater vapour generation, promote a sudden pressure rise in said cylinder to drive its piston during the engine's power stroke, similar to the explosion of an oil or gas fuel and air mixture in said cylinder.No electric ignition equipment is necessary although the use of electric heating plugs in the cylinders of piston engines could improve their starting characteristics. An exception to the methods of secondary fluid feed disclosed, is a thermal engine according to my United Kingdom Patent application No. 7920585, using the process by adaptation. In such an engine its fuel boiler(s) would be supplied with the secondary fluid. Heat could be removed from a condenser by a circulating fluid e.g.

air or water, and recuperated in the cycle by utilizing it to reheat the recycled primary fluid. The best proportion of secondary fluid could be found by actual experiment and would depend on factors, such as its pre-injection temperature, its volatility and specific heat and the heat available in the compressed primary fluid for its vaporization. In open circuit engines, the secondary fluid could be preheated in a cylinder or compressor cooling jacket or in a heat exchanger heated by the engine's exhaust fluid or by electrical means, prior to its delivery to e.g. its injector. Minimum operating temperature requirements would, in this and other instances, vary according to the volatility of the secondary fluid employed.

As I have described previously, similar or different primary and secondary fluids can be used in the plants utilizing the process, it also being practical to employ any gaseous medium as said primary fluid.

Examples having closed working fluid circuits and using an involatile secondaryfluid, such as water, may require a provision to maintain the operating temperature of said fluid against any heat loss to earth, atmosphere or the like via their fabric.

The air compressor 2, Figure 1 can deliver its mixture of fluids to a power generator, such as a turbine, which may or may not be the only power generator embodied, placed between it and vessel 1, said air compressor possibly being powered by all the gases from said vessel or replaced by a gas generator unit according to my British Patent specification No. 946,443. The air compressor 2 may vaporize the water supplied to it and this would be the method of operation of said gas generator unit.

The outlet 3 and the inlet of air to air compressor 2 is unnecessary in the appropriate examples.

The entrainment of fluid by air compressor 2 or the like, for cooling purposes, is not essential in all the plants disclosed with reference to Figure 1, it being practical to reduce the primary fluid compression work by cooling said compressor or/and said fluid, exclusively by any of the other heat exchange or dissipation methods referred to.

The invention renders practicable new kinds of two stroke piston engines having no cylinder scavenging means and merely provided with an exhaust port or ports in each cylinder, for the release of the excess secondary fluid vapour, the vapour remaining in said cylinder(s) being used as the engine's primary fluid; and new four stroke cycle such engines in which the exhaust ports of their cylinder(s) act also as the primaryfluid inlets, and their exhaust valve(s) remain open during both the exhaust and the inlet strokes of the pistons, to allow said working.

Refrigerative cooling methods may be applied to separate secondary fluid vapour condensers of adapted internal combustion engines using the process, waste heat from the refrigerator advantageously being recuperated, for example by utilizing said heat to warm piston engine cylinders or for primary fluid reheating or secondary fluid vapour superheating purposes.

The employment of jet type primary fluid compressors, such as the unit 2, Figure 1, avoids the energy loss consequent with the use of mechanical such fluid compressors, which must be driven by some means, thus improving the overall efficiency of the plant, in the relevant cases.

The characteristics of steam formation from its liquid at different temperatures are well known to anyone with a good knowledge of the art.

In the second example Figure 2, air is compressed by a single stage primary fluid compressor 11 and, with secondary fluid premixed with said air, is passed into a heat expansion chamber 12 in which said secondary fluid is fully or partially vaporized by heat passed to it by said compressed air. The compressed air and steam mixture is then mostly expanded through an outlet constituted by nozzle 13, to produce a thrust reaction. Any secondary fluid not vaporized in chamber 12 is passed from the bottom of said chamber by a pipe 14 into a vessel 15 from which it returns, under its own pressure, to a nozzle 16, which sprays said fluid into the air stream entering compressor 11.Some of the mixed steam and air products are led from the chamber 12 by a conduit 17 to the single power nozzle 18 of compressor 11 and is expanded through said nozzle into the compression duct 19 ofsaid compressor, which is cooled by jacket 20 placed around said duct and supplied with cooling air through a vent 21. This cooling air is drawn through jacket 20 by an ejector nozzle 22 connected to said jacket by a pipe 23 and arranged around nozzles 13 so as to form a second jacket which heats said nozzle 13, thus recovering the heat passed to said cooling air. The cooling air is ejected from nozzle 22 and may produce extra thrust.

Secondary fluid can be sprayed by several nozzles into all the stages of a compressor having a plurality of stages and replacing the single stage unit 11.

Alternatively, the secondary fluid may be pressurized by a pump or its vaporization may be reduced by also cooling chamber 12, for example by an extension of jacket 20 enclosing said chamber.

Optionally, the compressor 11 may be cooled by the secondary fluid, which may be permitted to boil, before said fluid's passage, possibly as wet vapour, to nozzle 16. The assembly may be insulated to stop unwanted heat losses to e.g. atmosphere. If the secondary fluid is liquid air, jacket 20 may receive its coolant from a heating jacket placed around nozzle 13, said coolant perhaps being circulated by a pump, or from vessel 15. The vessel 15 may be cooled by a refrigerator or a cryostat, waste heat from which could be utilized to superheat the gases ejected through nozzles 13 and 22, for example, by passing hot refrigerant fluid through heating jackets placed and acting to heat extensions of said nozzles.

By supplying compressor 2, Figure 1 with primary fluid and secondary fluid derived from independent sources, the example in said Figure would be enabled to pump both said fluids.

In the operation of the plant shown in Figure 1, with liquid air secondary fluid, liquid oxygen may be formed in vessel 1, since the liquid nitrogen content of said secondary fluid may boil away owing to its lower boiling temperature. This liquid oxygen and nitrogen vapour could be led away for utilization.

A process according to the invention thus also comprehends its use for the distillation of liquid oxygen and nitrogen vapour from the secondary fluid, concurrent with the inclusion in said process of a provision for the earlier removal of impurities, for instance water vapour and carbon-dioxide, from the air for liquefaction entrained by compressor 2, Figure 1.

It is advantageous to himidify the air compressed by air compressors 2, Figure 1 and 11, Figure 2, since a wet mixture is compressed more easily than a dry gas, but it is practical to inject the secondary fluid, by a suitable pressurizing device, directly into chamber 12, Figure 2, where so preferred. The secondary fluid also increases the density of a wet mixture. Such humidifying of said air or even the specific cooling of the said air compressors is, however, non-essential in the working cycle of the embodiments concerned, in either case.

The air compressor nozzle 18, Figure 2 might be arranged as an ejector drawing the secondary fluid from vessel 15 and exhausting said fluid and the mixture led to said nozzle from chamber 12, into air duct 19, the nozzle 16 being omitted.

Another plant would comprise the construction shown in Figure 2, but the secondary fluid or some of it, would be fed buy a pump or its own pressure, into a heat exchanger, such as a multitubular or a coiled tube unit, placed in chamber 12 and operating to heat said fluid and pass its vapour, at pressure, to nozzle 18 or the like, instead of the mixture normally led by conduit 17 to said nozzle from chamber 12, i.e.

in lieu of same.

Claims (12)

1. A method of fluid pressurizing, transfer, generating and utilizing consisting in the compression of a primary fluid, such as air, the use of said compressed primary fluid to heat and vaporize under pressure a secondary fluid, for example water, at or above a minimum temperature level where the evaporation of said secondary fluid increases more rapidly than its temperature, and the conveyance of any one or more of the pressurized or generated and pressurized fluids to or in immediate utilization, for example in carrying thermal or mechanical loads, to store or discharge, e.g. to waste or super-heating.

2. A method according to Claim 1, including the immediate utilization of a pressurized generated mixture of the primary fluid and the secondary fluid vapour.

3. A method according to either preceding claim, including the compression of the primary fluid or a mixture of the primary and secondary fluids, by either a mechanical or a jet type compressor, ram action, the momentum of recycled exhaust such fluid or fluid mixture, a gas generator unit or even combined such compression means.

4. A method according to Claim 3, including the partial operation of a jet type primary fluid compression means, by the admixture of secondary fluid to the primary fluid, for the purpose of increasing the effective mean density of said primary fluid under compression and its humidity.

5. A method according to any preceding claim, employed in a closed or open circuit heat engine working, as appropriate, according to either a continuous or an intermittent cycle.

6. A method according to any preceding claim, employed in the heat engines described with referpence to Figures 1 and 2 of the drawings.

7. A method according to any preceding claim, employed in the heat engine plant described with reference to Figure 1 of the drawings, specifically including the generation of pressurized nitrogen vapour and liquid oxygen fluids from a liquid air secondary fluid.

8. A method according to any preceding claim, employed in the heat engine described with reference to Figure 1, including the superheating of the secondary fluid vapour or mixture of such vapour with the primary fluid.

9. A method according to Claim 8, including the superheating of the mixture of secondary fluid vapour and the primary fluid, by the admixture thereto of additional hot compressed air.

10. A method according to any preceding claim, including the preheating of the secondary fluid.

11. A method according to any preceding claim, including the use of some of the energy of the pressurized fluid or fluids to perform the primary fluid compression work.

12. A fluid pressurizing, generating, transfer and utilizing plant substantially as hereinbefore described with reference to and as illustrated in Figures 1 or 2 of the accompanying drawings.