GB2110305A - Apparatus for vaporising a liquid by hot compressed gas to produce power - Google Patents

Abstract

In the single cylinder four stroke piston engine shown, a gas, for example air, drawn into cylinder 3 is compressed and water is sprayed into the compressed gas by injector 9. The water is immediately flashed into steam, giving a sudden pressure rise in cylinder 3 which drives its piston downwards, thus turning the engine's crankshaft. The mixture is finally exhausted from cylinder by pipe 10 to atmosphere or alternatively, via pipe system 12 into a condenser 6, which recovers water from said mixture, and fresh air or mixture led back from said condenser is again admitted to said cylinder. A mechanical pump 7 driven by the engine, supplies the water under pressure intermittently to injector 9. An embodiment incorporating a jet-pump compressor and a turbine instead of the piston/cylinder engine is described, Fig. 3 (not shown). <IMAGE>

Description

SPECIFICATION Improvements in thermal power plants This invention relates to improvements in thermal power plants and more particularly to such plants which generate and utilize vapour.

It is well known that in power plants of this kind the vapour is usually generated by a boiler and is fed to a mechanical power generator, such as a reciprocating engine or a turbine, either of open circuit or condensing type, which it drives. In such power plants according to, for example by British specification No. 1,085,116, waste heat is recovered from the vapour passing to expansion from the mechanical power generator by feeding this vapour back into the boiler which necessarily forms a bulky, expensive and heavy part of the apparatus rendering this kind of power plant, which has an excellent thermal efficiency, comparatively unsuitable for use in, for example, motor vehicles or aircraft.

To overcome this disadvantage, in the present apparatus the boiler has been eliminated from the plant by adapting the internal combustion engine in its several forms to function as a vapour driven power plant by injecting for example a liquid, such as water, into the high temperature compressed air generated during these plants' working cycle and utiiizing the heat of this air to convert said liquid into vapour at high pressure which, mixed with said compressed air, is employed to produce energy.Condensation of this vapour after its expansion in the engine may be effected merely by adiabatic further expansion of the mixture in a suitable condenser vessel to atmospheric pressure and temperature, the condensate being re-used, but in most examples only partial condensation of the liquid is required, the remaining portion of the vapour mixed with the expanded air being returned to the engine or remaining in the engine's working fluid circuit, or a fully open circuit system may be used. In some cases a closed circuit arrangement in which the air is replaced by vapour given off by the liquid, which is of suitable volatility to permit this, may be employed.

According to an aspect of this invention an adapted internal combustion engine, such as a two or four stroke cycle heavy oil piston type power plant or a gas turbine engine, is characterized by the fact that an incombustible liquid, such as water, replaces the oil fuel normally injected into the engine and is converted into vapour at high pressure in the engine's combustion chamber or chambers by heat derived from the air or vapour replacing it, compressed in said combustion chamber(s) and expanded to generate power.

According to the invention, a thermal power plant comprises one or more cylinders or expansion chambers receiving a gaseous fluid, such as air, means to compress said gaseous fluid and diffuse a liquid, for example water, which is vaporized by the heat of said compression, therein, and a provision to utilize the gaseous mixture in the carriage of mechanical or/and thermal loads.

The invention will now be described in more detail with reference to the examples which are of a non-limitative nature, since this invention may be applied to various designs of power units, shown in the accompanying drawings, in which: Figure 1 is an elevation diagram of a four stroke cycle piston type vapour engine of single cylinder design in accordance with the invention, Figure 2 is an eievation diagram of a single cylinder two stroke cycle piston type vapour engine according to the invention, and Figure 3 is a diagrammatic plan view of a vapour turbine engine having a jet type compressor system.

Referring to Figure 1, air is drawn through air filter 1 and pipe 2, into cylinder 3 through an inlet valve in head 4 by the downward movement of a piston in said cylinder and after closure of said valve is compressed by the upward movement of said piston to a high pressure and temperature. A small quantity of water led by a pipe 5 from a condenser 6 to a pump 7 is forced by said pump through a pipe 8 and nozzle 9 and is sprayed in finely divided form into the hot compressed air in cylinder 3 at the end of its piston's upward stroke or perhaps slightly before this event, and is turned into steam at a high pressure which, with this air, forces the engine's piston downwards in said cylinder during the power stroke of the engine and, after its expansion in this cylinder, is passed through a second valve in head 4 and exhaust pipe 10 to atmosphere and partly to condenser 6, where water is condensed out of the mixture, during the following upward exhaust stroke of said piston. The second valve then closes and the cycle described starts again. The engine's piston drives fly wheel 11 through a crankshaft and a connecting rod. A pipe assembly 12 upon closure of valves 13 and 14 in respectively, pipes 2 and 10, converts the engine into a closed circuit unit in which all the exhaust fluid is led to condenser 6 which has a breather vent 1 5 communicating with atmosphere. Pump 7 is driven by the engine's crankshaft at half its speed by gears (not shown).

If desired, by a suitable modification of the timing and the cams operating the valves in head 4 both these valves may act as both inlet and exhaust valves and be in the open position throughout the exhaust and the following inlet strokes of the piston, or a single valve so arranged may replace the two valve system described.

Alternatively, the embodiment shown in Figure 1 may be designed to function as a two stroke cycle unit using crankcase compression or an engine driven or an exhaust gas driven air compressor to feed air into the cylinder which would not require any valves in its head 4 in this case. Conventional starting motors could rotate the crankshaft when starting either embodiments.

Condenser 6 may be constructed like a motor vehicle radiator and be cooled by a fan driven by a belt and pulley from another pulley on the hub of fly wheel 11, or a refrigerator may be used for this purpose, waste heat from which could be passed e.g. by a jacket provided on cylinder 3 and fed with the fluid from the hot side of said refrigerator, to the walls of this cylinder.

The embodiment according to Figure 1 could, in place of the two valves described, have a single sleeve valve either of oscillating or reciprocating kind. By designing this valve so that its ports pass completely over the ports which would be provided in cylinder 3, both during said sleeves upward and during its downwards motion, the sleeve could be driven by conventional gears and a crank from the engine's crankshaft at a quater of this shaft's speed i.e. the sleeve's driving crank would rotate at said quarter engine shaft speed.

To improve the vaporization of the injected water, nozzle 9 may be located to inject its fluid into an ante-chamber, such as a so called Acro air cell, provided in head 4 and communicating with cylinder 3 by means of a suitable duct.

The example illustrated in Figure 2 differs mainly from the vapour engine shown in Figure 1 in that it functions on a two stroke working cycle and is a closed circuit unit in which the exhaust vapour leaving the exhaust port of cylinder 3 is directed by manifold 1 6 into condenser 6 in which said vapour is condensed by a refrigeration coil 1 7. Engine driven compressor 18 recompresses the refrigeration gas led to it from coil 1 7 and feeds it under this pressure and at a high temperature into a jacket 1 9 placed round cylinder 3 which is heated by said hot gas which is finally passed through a valve 20 back into coil 1 7 where it expands to a low pressure and temperature.The vapour remaining in cylinder 3 is re-compressed during the upstroke of the engine's piston. Water pump 7 is driven at engine speed.

Because of the absence of an effect such as Diesel knock in the vapour cylinders of engines according to Figures 1 and 2, a much higher compression ratio could be employed than that used with heavy oil engines of similar type, giving an improved thermal and overall efficiency in these units. Higher speeds may also be used.

The final example shown in Figure 3 comprises at jet type compressor 21 acting to compress vapour and feed it at a comparatively high temperature due to this compression, into a chamber 22 from which, after said vapour is mixed with water injected into it by nozzles 9 which are fed by pump 7 and turned into steam, the efflux is led to a turbine 23 from which it exhausts by way of pipe 26 into condenser chamber 6 in which it expands and some of it is condensed to water and the remaining vapour passed back to compressor 21 through the connecting pipe shown. A pipe to convey any condensate from the exhaust manifold of turbine 23 into condenser 6 may be included.Pump 7 is driven by turbine 23 and obtains its water from condenser 6 which is cooled by the refrigeration coil 1 7 placed in it, of a refrigerator similar, except that its compressor 1 8 is electrically driven, to the unit in Figure 2. Waste heat from this refrigerator is passed to the vapour feeding chamber 22 by a heat exchanger 24 fed with the hot compressed refrigeration gas by compressor 1 8. Heat exchanger 24 may be positioned upstream of compressor 21, if preferred. Vents 15 and 25 in respectively, condenser 6 and the inlet manifold of compressor 21, communicate with atmosphere.

Spraying the water into the suction side, either by pump 7 or at atmospheric pressure, of compressor 21 may render chamber 22 unnecessary. Vent 25 may also not be required with water injection by atmospheric pressure, in this arrangement. The water may be fed to nozzles 9 continuously or by a pulsating action. Corresponding to the rise in the pressure of the vapour in the cylinders of the piston engines described upon injection of the liquid, expansion of the fluids in chamber 22 increases their kinetic energy and total power. A compound or a triple expansion turbine with exhaust re-heat by combustion gas, atomic or electrical heating means could to advantage be used with these embodiments working at high pressure, for example, a pressure in the region of 800 Ib per square inch.

All three embodiments would function equally well as open circuit air breathing units having no condenser 6, but a supply of water to pumps 7 would be needed. Vents 1 5 could serve as fillers for condensers 6 which may require drain cocks or plugs also and, perhaps, water level indicators, strainers and lubricating oil separators. Distilled water may advantageously be used as the liquid which might be heated e.g. electrically or by waste heat from the refrigerators, prior to its injection, to increase its volatility, but with a fully closed circuit the use of liquid air, nitrogen or carbon-dioxide or similar agents as the liquid may be practical if suitable provision for thermal insulation and refrigeration means to prevent boiling of this liquid in condensers 6 is made.Some waste heat from the refrigerator may necessarily be passed to atmosphere in this case.

The compressor 21, Figure 3 is a jet type unit in accord with my British specification No. 946,443, but may be a compressor of some other kind, such as a mechanical unit driven by turbine 23 through a long shaft.

Condensers 6, Figures 1,2 or 3 are merely vessels collecting and containing the condensate water and with a large enough reserve capacity to permit the adiabatic expansion of the exhaust fluid led into them. Condensers constructed like radiators would have to have a similar capacity.

In the application of this invention, the refrigerator compressor 18, Figure 3 might be driven by turbine 23 which itself may incorporate a reduction gear box and an auxiliary gear drive to ancillary equipment such as said compressor and water pump 7 and a lubrication oil pump. The crank cases of the piston engines described with refrence to Figures 1 and 2 may additionally incorporate breather vents which might act also as fillers for pouring lubricating oil into these crank cases, but it would be possible to employ a mechanical lubrication system in which instance a separate oil tank connected to oil feed and scavenge pumps driven for example, through gear trains by these engines' crank shafts with these embodiments. Non-condensing examples may require a water supply tank.

Connecting pipes 5 and 8, Figure 3 carry the water to and from respectively, pump 7.

Although this invention is disclosed on piston and turbine engines it may be applied to various designs of power plants, e.g. where a steam piston engine replaces turbine 23, without detracting from its substance.

When starting the working cycle of the embodiments shown in Figures 2 and 3 and the embodiment according to Figure 1 when this latter engine is arranged with a partly closed circuit, from cold, since no vapour would be present in condensers 6, air would be inspirated through vents 1 5 and 25.

Although the embodiments described with reference to Figures 1 to 3 are disclosed as mechanical power generating plants, these plants may be adapted as hot vapour generating units for use as, for example, heat product units or plants.

Provision, such as a water jacket around condenser 6, Figure 3 or the radiator system referred to concerning the examples according to Figures 1 and 2, to replace the heat extracted from the working fluid, may be essential in particular examples of such plants. This would be possible owing to the subatmospheric temperature of the expanded vapour in said condenser and radiators which would pass heat from the water jacket and from atmosphere respectively, to said vapour, in these instances. Turbine 23, Figure 3 may not be included. The hot vapour would be led under pressure from the exhaust systems of the piston engines, or from chamber 22 or the exhaust side of turbine 23, Figure 3 of the appropriate third example, for utilization in heat exchangers and the like.

Combined mechanical power and hot vapour generating embodiments are practical.

A plurality of expansion chambers, e.g. a ring of such chambers, can be substituted for the single chamber 22, Figure 3.

Considering the lower temperature of the expanded vapour in condensers 6, Figures 1,2 or 3 in heat generating plants this vapour could be utilized for refrigeration or freezing purposes. In a plant specifically designed for refrigeration or freezing the heat produced could be wasted to atmosphere and condenser 6 might take the form of a tube coil or any other required shape An ordinary pressure reducing valve or device would be necessary in the vapour circuit immediately upstream of condensers 6 of hot vapour or refrigeration or freezing embodiments to lower the pressure of the vapour entering said condensers.

In the Claims of novelty to follow, the expression "thermal power plant" applies to all embodiments described, and the expression "incombustible liquid" will include noncombusting liquids, such as liquified butane or carbon-dioxide contained in another system, with their vapour under pressure in the condensers 6, Figures 1, 2 and 3, which would have no vents to atmosphere in this case and might employ in all examples air or water cooling methods, but could be connected to a gas supply source for replacing any such working fluids lost by leakage, and used in closed circuit embodiments instead of water for the injection purposes.

Claims (8)

1. A thermal power plant comprising one or more cylinders or expansion chambers receiving a gaseous fluid, such as air, means to compress said gaseous fluid and diffuse a liquid, for example water, which is vaporized by the heat of said compression, therein, and a provision to utilize the gaseous mixture in the carriage of mechanical or/and thermal loads.

2. A thermal power plant according to Claim 1, wherein the gaseous fluid for compression is uncondensed vapour or a mixture of such vapour and air, either left in its cylinder(s) or/and returned from an associated condenser fed with said plant's exhaust mixture or at least a portion thereof, thereto or to its expansion chamber(s).

3. A thermal power plant according to either preceding claim, wherein adiabatic expansion combined in particular instances with refrigeration, is employed to condense to a liquid state a portion of the exhaust vapour leaving the power plant for re-use as the injected liquid.

4. A thermal power plant according to any preceding claim, wherein the liquid is pre-heated by, for example, waste heat from the refrigerator or by electrical means before its injection.

5. A thermal power plant according to any one of Claims 1, 3 or 4 or, as appropriate, Claim 2, employing an open, partially open or a fully closed circuit system for its working fluid.

6. A piston type thermal power plant according to any preceding claim, wherein the liquid is injected into an ante-chamber or chambers from which it passes through a connecting duct system in partially atomized form into the engine's cylinder or cylinders.

7. A mechanical power generator driving thermal power plant, such as an adapted gas turbine engine, or a hot vapour generating plant with or without a such mechanical power generator, according to any one of Claims 1 to 5, wherein waste heat from its refrigeration unit is utilized to pre-heat the compressed gaseous fluid feeding its expansion chamber or chambers.

8. A thermal power plant constructed and arranged to function substantially as herein described with reference to any of Figures 1, 2 or 3 of the accompanying drawing.