WO1999036687A1

WO1999036687A1 - An improved apparatus for power and clean water production

Info

Publication number: WO1999036687A1
Application number: PCT/AU1999/000031
Authority: WO
Inventors: Peter Lawrence Murphy; Terry Howard Solomon; Danh Thanh Trinh
Original assignee: Thermal Energy Accumulator Products Pty. Ltd.
Priority date: 1998-01-15
Filing date: 1999-01-15
Publication date: 1999-07-22

Abstract

An apparatus (10) for producing motive power, said apparatus (10) comprising: a mixing chamber (14) being adapted to receive and intimately mix a gas (15) and a conditioning liquid (17) so as to produce a wet gas (19); a turbine (16A) being operatively coupled to the mixing chamber (14); and a pump (16B) being operatively coupled to the turbine (16A) whereby, in use, a flow of the wet gas (19) from the mixing chamber (14) can be expanded through the turbine (16A) which thus provides the motive power and an exhaust wet gas (19) from the turbine can be further exhausted of its heat energy whilst increasing the torque on the turbine (16A).

Description

AN IMPROVED APPARATUS FOR POWER AND CLEAN WATER PRODUCTION

The present invention relates generally to an apparatus and method for producing motive power and relates particularly, though not exclusively, to an apparatus and method for producing motive power and clean water via a turbine and pump.

A conventional gas turbine consists of a plurality of turbine blades fixed to and radially extending from an axial shaft. The blades and shaft are rotationally housed within a turbine housing through which superheated gas is passed. The superheated gas impacts with the aerofoiled blades thereby rotating the axial shaft so as to provide motive power .

It is well understood that with the conventional gas turbine : i) the turbine relies on a dry superheated gas with any liquid causing damage to the turbine blades and other internal components of the gas turbine; ii) the superheated dry gas can reach high temperatures and thus relatively expensive high temperature alloys are required; iii) in the combustion process some form of cooling is essential, generally by the introduction of cooling air to the combustion chamber, so that temperatures will not be reached such that there will be failure of the turbine materials and consequently this introduces heat and energy losses in the overall gas turbine efficiency; iv) the turbine power output decreases with increasing temperature of air entering the combustion chamber (normally the ambient temperature) , the air being less dense at high temperature which thus reduces the mass flow rate of the system; v) the conventional method for cooling the inlet air is by forced cooling, such as the use of refrigerated chillers, and as a result, this has certain disadvantages and limitations, in particular, in producing an overall high cost system; vi) the operating pressure of the conventional gas turbine is considered to be low with high operating temperature ; and vii) exhaust emissions of nitrogen oxides (N0_X) are generally controlled by incorporating N0_X burners to reduce the emissions.

It is also well understood that with a conventional internal combustion engine such as a petrol spark ignition engine or diesel compression ignition engine: i) the combusted gas can reach high temperatures and thus relatively expensive high temperature alloys are required; ii) in the combustion process some form of cooling is essential, generally by circulating cooling water around the engine casing and other engine parts, so that temperatures will not be reached such that there will be failure of the engine materials and consequently this introduces heat and energy losses in the overall engine efficiency; iii) the performance of the conventional internal combustion engine is affected by the ambient air temperature, the engine power output decreasing with increasing temperature of the air entering the combustion chamber; iv) the operating pressure is considered to be low with high operating temperature; v) exhaust emissions are generally controlled by incorporating emission control devices such as a catalytic converter; and vi) it is not possible to also produce from the internal combustion engine clean water as a secondary product from salty or contaminated water introduced to the engine . An intention of the present invention is to provide an apparatus and a method for producing motive power and/or clean water that is relatively energy efficient.

According to one aspect of the present invention there is provided an apparatus for producing motive power, said apparatus comprising: a mixing chamber being adapted to receive and intimately mix a gas and a conditioning liquid so as to produce a wet gas; and a turbine being operatively coupled to the mixing chamber whereby, in use, a flow of the wet gas from the mixing chamber can be expanded through the turbine which thus provides the motive power.

According to another aspect of the present invention there is provided an apparatus for producing motive power, said apparatus comprising: a mixing chamber being adapted to receive and intimately mix a gas and a conditioning liquid so as to produce a wet gas; a turbine being operatively coupled to the mixing chamber; and a pump being operatively coupled to the turbine whereby, in use, a flow of the wet gas from the mixing chamber can be expanded through the turbine which thus provides the motive power and an exhaust wet gas from the turbine can be further exhausted of its heat energy whilst increasing the torque on the turbine.

Generally the apparatus further comprises a heat exchanger adapted to receive and cool an exhaust wet gas from the pump. Thus, the apparatus is designed to produce motive power and clean water. According to a further aspect of the present invention there is provided a turbine for producing motive power, said turbine being adapted to receive and intimately mix a gas and a conditioning liquid so as to produce a wet gas within or adjacent the turbine whereby, in use, a flow of the wet gas can be expanded through the turbine which thus provides the motive power.

Preferably, the turbine is a boundary-layer turbine which operates effectively with the wet gas, the turbine having a plurality of discs fixed axially to a shaft which is journalled within a sealed casing.

The conditioning liquid is effective in both lowering the temperature of the combustion gas and providing a wet gas which improves the performance of the boundary-layer turbine in adhering to the discs of the turbine . The relatively low temperature of the wet gas does not require expensive materials in the turbine such as those superalloys and ceramics used in conventional gas turbines. The conditioning liquid is also effective in combining with the combustion gas to reduce discharge of environmentally damaging emissions including carbon monoxide and nitrogen oxides .

According to yet another aspect of the present invention there is provided a pump adapted to couple to a shaft of a turbine, the pump being designed to accept an exhaust of the turbine and to increase torque on the turbine shaft by further utilising the energy in a conditioning liquid which together with a gas is mixed to produce a wet gas which is received in the turbine.

Preferably the pump is a boundary layer pump which operates effectively with the wet gas, the pump having a plurality of discs fixed axially to the turbine shaft which is journalled within a casing. More preferably the casing is open at an outer circumference to facilitate expulsion of the pumped wet gas to the heat exchanger for removal of contaminants or to a holding or waste or other receptacle. Generally the discs of the pump are of a similar diameter and greater in number compared to the discs of the turbine.

Typically, the gas is a combustion gas. Generally, the combustion gas is effective in partly causing a phase change in the conditioning liquid which thus releases its latent heat and produces a significant increase in pressure within the mixing chamber. Alternatively, the gas is heated by a heat exchange with a source of waste heat such as a combustion gas. Additionally, the gas may be taken from a low temperature heat source, such as exhaust gas from a combustion engine, so as to heat and mix with the conditioning liquid to provide the wet gas at a desirable temperature and pressure.

Thus, the mixing chamber is effective in producing a wet relatively high pressure gas which optimises the performance of the turbine. Optimum performance of the turbine is achieved as a consequence of the : i) wet gas being effective in maximising the drag and adhesion effect on the turbine discs; ii) relatively high temperature of the wet gas; iii) relatively high pressure of the wet gas; and iv) utilisation of further energy in the wet gas by the pump.

Typically, the apparatus further comprises a combustion chamber being operatively coupled to the mixing chamber and designed to receive air and a fuel which when burnt within the combustion chamber produce the combustion gas. The combustion chamber is operated at a stoichiometric or excess air to fuel mixture ratio to ensure complete combustion of the fuel and thus minimise discharge of environmentally damaging emissions including unburnt fuel. Generally, the apparatus also includes an air compressor coupled to tήe combustion chamber so that the air received by said chamber is compressed, the air compressor being driven by a compressor shaft operatively coupled to the turbine.

In one example, the apparatus further comprises a heat exchanger coupled between the turbine and the air compressor so that exhaust gas from the turbine can preheat air being fed to the air compressor prior to its burning with the fuel in the combustion chamber.

Generally, the mixing chamber includes an injection mechanism which is designed to receive the conditioning liquid and to inject it into said chamber in the form of relatively fine atomised droplets.

Typically, the mixing chamber is one of a plurality of mixing chambers each being connected to one of a number of inlet nozzles of the turbine, said nozzles being spaced circumferentially about the sealed casing of the turbine.

Generally, the one combustion chamber provides the combustion gas to all of the plurality of mixing chambers. Alternatively, the combustion chamber is one of a plurality of combustion chambers each coupled to each of the plurality of mixing chambers, respectively. In this alternative example the apparatus is designed so that each of the combustion and mixing chambers sequentially cycle about the turbine in a clockwise or anti-clockwise direction with combustion in the combustion chamber, mixing in an adjacent mixing chamber, and expansion of the wet gas in an adjacent turbine .

In one example the apparatus for producing only motive power is a "closed cycle" including a condenser coupled between the pump and the mixing chamber, the condenser being designed to cool and thus at least partly condense the exhaust gas of the pump so that said condensed exhaust gas can be recirculated to the mixing chamber as the conditioning liquid.

In another example the apparatus for producing motive power and clean water is an "open cycle" where the conditioning liquid is salty or contaminated water which becomes steam in the mixing chamber with the flow rate of the conditioning liquid being determined so that it maintains a steam condition on its expulsion from the pump into a heat exchanger wherein the solids in suspension are separated from the water vapour thereby allowing the water vapour to condense the clean water for collection in a water storage tank.

Preferably, the apparatus also includes a generator or electric motor operatively coupled to an output shaft of the turbine. Alternatively or additionally, the apparatus includes a flywheel arrangement operatively coupled to the output shaft, the flywheel designed to store the motive power within energy storage means such as batteries.

According to yet a further aspect of the present invention there is provided a method of producing motive power comprising the steps of: producing a wet gas by the intimate mixing of a gas and a conditioning liquid; and expanding the wet gas through a turbine and the pump so as to provide the motive power.

Typically, the intimate mixing of the gas and the conditioning liquid occurs within a mixing chamber.

Alternatively, mixing of the gas and conditioning liquid takes place within or adjacent the turbine wherein the gas and conditioning liquid are introduced into the turbine together as a single stream or separately as two (2) streams . Typically, the temperature of the gas is from between 1200 to 1500°C for combustion gas and between 400°C to 500°C for exhaust gases. Generally, the temperature of the wet gas fed to the turbine is reduced to from between 180°C to

1000°C, said wet gas being released from the mixing chamber at a high pressure. It will be appreciated that the temperature and pressure of the wet gas will vary depending on the type and quantity of fuel and conditioning liquid used.

Typically, the conditioning liquid is a non-combustible liquid at the temperature of the mixing chamber. More typically, the conditioning liquid is water so that wet steam is formed in the mixing chamber. Generally, the fuel is natural gas, liquefied natural gas (LNG) , liquefied petroleum gas (LPG) or a solid fuel such as coal. The combustion gas, being the combustion products of air and the fuel, includes carbon monoxide, carbon dioxide, any excess oxygen, unburnt fuel, and nitrogen oxides.

Wet gas is to be understood as the gas having been partially wetted by the conditioning liquid. It will be appreciated that the resultant viscosity and adhesion of the wet gas is critical to optimising the turbine performance in both increasing the power or "drag effect".

In order to facilitate a better understanding of the nature of the present invention several possible embodiments of an apparatus for producing motive power via a turbine will now be described in some detail, by way of example only, with reference to the following drawings in which:

Figure 1 is a schematic of an apparatus for producing motive power via a turbine; Figure 2 is a schematic of the apparatus of Figure

1 together with a heat exchanger; Figure 3 is a schematic of a further apparatus for producing motive power including multiple mixing chambers;

Figure 4 is a schematic of another apparatus for producing motive power incorporating multiple combustion chambers and mixing chambers;

Figure 5 is a schematic of yet another apparatus for producing motive power including multiple turbines;

Figure 6 is a schematic of the apparatus for producing motive power and clean water; Figure 7 is a schematic of yet a further apparatus for producing motive power;

Figure 8 is a schematic of an apparatus for producing motive power including a flywheel arrangement;

Figure 9 is a cross-sectional view of an apparatus for mixing dry and wet fractions of a compressible fluid.

As illustrated in the accompanying drawings, there is provided various embodiments of an apparatus for producing motive power shown generally as 10 comprising a combustion chamber 12, a mixing chamber 14, a gas turbine 16A, a pump

16B and an air compressor 18. Additionally the apparatus 10 may include a heat exchanger 20, a condenser 22, and/or means for producing power or motion 24 including a generator, electric motor or flywheel/battery arrangement.

The combustion chamber 12 is substantially of conventional construction and can operate with a wide variety of fuels . Most common liquid and gaseous hydrocarbons fuels can be used, as long as the fuel flow rate and delivery pressure can be adjusted to achieve the correct air/fuel ratio. The gas turbine 16 can burn with low carbon/hydrogen ratio, such as the short-chain hydrocarbons and alcohol, as well as more conventional fuels. Examples of fuels are: natural gas, LNG (liquefied natural gas) , LPG (liquefied petroleum gas) , solid fuels such as coal, and any other suitable combustible fuels. The combustion chamber 12 is designed to operate at the peak performance level. That is, the combustion chamber 12 is designed at the stoichiometric air/fuel mixture ratio for complete combustion so as to minimise carbon monoxide (CO) and any unburnt hydrocarbon emissions. The temperature within the combustion chamber 12 should be at the maximum temperature with the combustion temperature typically ranging from between 1500 to 2000°C. Major reductions of nitrogen oxides (NO_x) levels are expected as a result of improvements in combustion chamber 12 design and operating conditions including variable cooling and dilution of air to control the quenching of the flame, pre-mixing and pre- vaporising combustion chambers. High temperature superalloys or ceramic materials are used as liners inside the combustion chamber 12 so as to allow the maximum combustion temperature . These ceramic materials have already been developed for use in high temperature combustors and heat exchangers .

The gas turbine 16A relies on the fluid properties of a wet mixture gas in order to maximise its power output. This wet mixture is achieved by the mixing chamber 14. Gas at an elevated temperature such as a combustion gas produced by burning a natural gas at 1200 to 1500°C and compressed air at 4 to 5 Bar is mixed with a conditioning liquid such as water to create the wet gas mixture. The wet gas is then applied to the nozzle of the boundary-layer gas turbine 16A. The wet gas expands and in doing work on the turbine 16A produces mechanical energy. Exhaust gas from the turbine 16 as shown in Figure 1 is released to the pump 16B at its centre surrounding the shaft. Depending on the operating conditions the type of conditioning liquid injected to the mixing chamber 14 is selected so that the performance of the turbine 16 can be maximised by the additional operation of the pump in power output and efficiency. Generally the conditioning liquid injected into the mixing chamber 14 is water. The combustion gas for example at 1200 to 1500°C (consisting of carbon monoxide CO, carbon dioxide C0₂, excess 0₂, unburnt hydrocarbons, nitrogen oxides as N0_X and other small constituents of gases) passes through the mixing chamber 14 where the water is injected by an injection mechanism device to intimately mix therewith. The temperature of the combustion gas is reduced to a level depending on the amount of water injected which also depends on the fuel burning and the turbine 16 load characteristics.

Typically, the temperature of the combustion gas is reduced to between 180 to 1000°C by the injection of water. In turn the water is heated and converted to steam with high vapour pressure being created within the mixing chamber 14. The state of steam is preferably unsaturated where excess water is injected. Therefore, the temperature, pressure and degree of wetness of the wet gas entering the turbine 16 can be controlled by injected water.

Water may be introduced to the mixing chamber 14 in the form of fine atomised droplets via an injection mechanism device

(not shown) thus allowing the water to be intimately mixed or reacted with the combustion gas from the combustion chamber 12.

The wet gas 19 preferably has a wet molecules mixture, for example water droplets, for maximising turbine 16 performance in power or "drag effect" and efficiency. That is, the boundary-layer drag turbine 16 in the form of a bladeless turbine 16 is designed to handle a wet mixture.

The important implication of the mixing chamber 14 using a conditioning liquid, typically water, is that the overall turbine 16 performance in turbine 16 power output and efficiency are significantly improved. Furthermore, environmentally damaging exhaust emissions are significantly reduced.

The turbine 16A is of a boundary-layer drag turbine type which consists of a set of flat steel discs fixedly mounted on a shaft and rotating within a sealed casing (not illustrated) . The wet gas entering with high velocity at the periphery of the discs flows between adjacent discs in free spiral paths, and escapes through exhaust ports at the centre of the discs. The gas turbine 16 depends upon the fluid properties of adhesion and viscosity wherein the attraction of the wet gas to the faces of the discs and the resistance of its particles to molecular separation combines in transmitting the kinetic energy of the wet gas to the discs and the shaft.

The pump 16B is of a boundary layer drag type which consists of a set of flat steel discs fixedly mounted on the turbine shaft and rotating within a casing which is open at the outer circumference (not illustrated) . The wet gas entering at low to moderate velocity at the centre of the discs around the shaft flows outward between the discs in free spiral paths and is expelled through the open outer circumference of the pump. The pump 16B depends upon the rotation of the shaft and the fluid properties of adhesion and viscosity wherein the attraction of the wet gas to the faces of the discs and the resistance of its particles to molecular separate combines in transmitting the kinetic energy of the wet gas to the discs of the shaft.

Thus, the apparatus 10 for producing motive power is a rotary, continuous internal combustion motor where the fuel is supplied to a combustion chamber 12 and burnt lean with an excess of air. The hot combustion gas then pass through the mixing chamber 14 where the conditioning liquid, typically water, is injected to produce the wet gas such as a wet high pressure steam. The high pressure steam or wet gas then expands and passes through the turbine 16A and the pump 16B which generates power.

The gas turbine 16A inlet temperature can be controlled to a working temperature that most metallic alloys can handle without the need for highly advanced and relatively expensive superalloys. In reducing the temperature of the combustion gas there is no loss in the overall energy because some of the energy taken from the combustion gas is used in the conversion of water to steam. Thus, the apparatus 10 for producing motive power utilises substantially 100% of the available energy output. Furthermore, the boundary-layer turbine 16 which includes "blades" in the form of flat discs has much lower manufacturing cost than a conventional bladed gas turbine having blades in aerofoil shape constructed of superalloy or ceramic materials.

Another feature of the apparatus 10 is that the pressure can be controlled by the water or conditioning liquid injection to give the maximum turbine performance. That is, the pressure of the combustion gas can be increased as in the wet gas to for example a steam vapour 160 Bar (saturated steam) pressure at the required operating temperature. By way of comparison, in a conventional gas turbine air is pre- compressed to about 4 to 5 Bar prior to entering a combustion chamber.

It is understood that when the combustion gas from the combustion chamber 12 passes through the mixing chamber 14 some of the CO gas is reacted with water to form C0₂ thus reducing the level of CO being released to the atmosphere . Similarly, it is understood that when the combustion gas from the combustion chamber 12 passes through the mixing chamber 14 some of the nitrogen oxides forming as NO_x are reduced by the water injection inside the mixing chamber 14 thus reducing the level of N0_X gases being released to the atmosphere. This is an advantage in contributing to a reduction in acid rain which is associated with high levels of N0_X in the atmosphere .

When water is injected into the mixing chamber 14 as the conditioning liquid it has certain advantages. Firstly, steam (heated water) has relative high latent heat, energy storage capacity, expansion factor and heat transfer characteristics. Furthermore, wet steam can include water droplets which benefit in maximising the turbine 16 performance as discussed above.

As further illustrated in the apparatus 10 of Figure 1 there is provided a High-Speed Generator (HSG) 24 having been under development for some time for handling high rotational speeds typically up to 100000 RPM. The gas turbine 16 is coupled directly to a high-speed alternator which produces a high frequency AC output. This AC output is rectified by inverters to provide a DC output which is the suitable for an electric motor.

The apparatus 10 also includes the standard multi-stage air compressor 18 which can be used in conjunction with the gas turbine 16. It is possible that an alternative air compressor using the boundary-layer turbine technology can be utilised.

Figures 2 to 8 illustrate variations on the apparatus 10 for producing motive power as depicted in Figure 1 and described above. In all embodiments of the invention the fuel, air, combustion gas, conditioning liquid, wet gas, and gas emission process streams are represented by the numerals 11, 13, 15, 17, 19, and 21 respectively.

Figure 2 illustrates the gas turbine 16 using pre-warm air for enhancing the combustion process. Heat from the exhaust gas of the turbine 16 is used to heat up the ambient air via the heat exchanger 20 before the warm air enters the combustion chamber 12. The heat exchanger 20 is typically of a fin-type with an air ducting system arrangement.

Figure 3 shows another embodiment of the apparatus 10 incorporating three (3) mixing chambers 14A to 14C. The number of mixing chambers 14 required can vary and depends largely on the turbine 16 load, type of fuel burnt, required operating pressure and temperature thus providing optimum performance for the turbine 16. The mixing chambers 14A to 14C are usually located immediately adjacent the turbine 16 inlet nozzles (not shown) and are designed to operate independent of each other. This provides flexibility in operation for controlling pressure and temperature of the wet gas entering the turbine 16. In a typical arrangement each of the mixing chambers 14A to 14C is designed to be opened or closed simultaneously or separately in a required sequence for maximising the turbine 16 performance for a given turbine 16 load.

Figure 4 illustrates a further example of the apparatus 10 now including three combustion chambers 12A to 12C and three (3) mixing chambers 14A to 14C. The number of combustion chambers 12 and mixing chambers 14 can vary and once again depends on the turbine 16 load, type of fuel burnt, required operating pressure and temperature thus providing optimum performance for the turbine 16. This apparatus 10 is designed so that each combustion chamber 12 can be operated independently from each other thus providing flexibility in operation for controlling pressure and temperature of the wet gas entering the turbine 16 similar to a conventional internal combustion engine. Operation of the combustion chambers 12A to 12C is designed with a cycle time for example combustion chamber 12A is in operation for combustion, combustion 12B is in operation for mixing with a conditioning liquid such as water, whilst combustion chamber 12C is in operation to supply high pressure and temperature wet gas generally steam to the turbine 16.

Figure 5 depicts a typical arrangement of the apparatus 10 using two (2) gas turbines 16A, 16B. The number of turbines 16 required can vary and the turbines 16 may be connected in a series or parallel depending on the turbine 16 load, type of fuel burnt, required operating pressure and temperature thus providing optimum performance for the turbine 16. The exhaust gas from the first turbine 16A typically at a temperature of between 400 to 500°C is mixed in the second mixing chamber 14B where the conditioning liquid which is usually water is injected prior to the wet gas entering the gas turbine 16B. This embodiment using multiple turbines 16 is designed to maximise the energy extraction from the fuel and conditioning liquid thus increasing turbine 16 power out and thermal efficiency significantly. The exhaust gas from the second turbine 16B is typically low in temperature and pressure being released to atmosphere.

Figure 6 illustrates another embodiment of the apparatus 10 including two (2) turbines 16A, 16B. Once again, the number of turbines 16A and 16C and pumps 16B required can be varied and/or the turbines 16A and 16C and pumps 16B connected in series or parallel depending on the turbine 16A and 16C load, type of fuel burnt, required operating pressure and temperature thus providing optimum performance for the turbine 16A and 16C and the pump 16B. The exhaust gas from the first turbine 16A is typically at a temperature of 400 to 500°C and is mixed in the second mixing chamber 14B where the conditioning liquid which is usually water is injected prior to the wet gas entering the turbine 16A. The exhaust gas from the second turbine 16B is in this example then proceeds through the pump 16B and then condensed to liquid via the condenser 22. The condenser 22 is typically in the form of a heat exchanger. In one example the wet gas exhaust from the pump 16B enters the condenser at a temperature sufficient to ensure the exhaust is in the form of steam (typically around 110°C to 130°C depending on the level of salt and other contaminants in the water) . The solids in suspension are separated from the liquid steam in condensation and clean water is collected at the bottom of the condenser 22. The water in this example is selected for its salt or other contaminant content before its introduction to the apparatus in order that it be cleaned consequent upon its passage through the apparatus and in particular its passage through condenser 22.

In another example the wet gas exhaust from the pump 16B enters the condenser at a temperature around or below ambient temperature and partially or substantially condensed to liquid. The condensate is then recycled by pumping back to the mixing chamber 14A in the apparatus or is collected for storage or waste. The water in this other example is substantially free from salt and other contaminants when introduced to the apparatus.

This other embodiment using multiple turbines 16A and pumps 16B and 16C is designed to maximise the energy extraction from the fuel and conditioning fluid thus increasing power output and thermal efficiency significantly. The condenser 22 is generally a closed circuit design via a shell-tube type heat exchanger for removing heat to ambient. The condenser 22 can however be a plate or open system.

Figure 7 shows a further embodiment of the apparatus 10 for producing motive power using an electric motor 24. In this example the turbine 16 drives an electrical generator which in turn powers an electric motor. A shaft of the electric motor drives the wheels of a vehicle.

Figure 7 is also a schematic diagram of a two-shaft apparatus 10 including a single gas turbine 16A and pump 16B. The two-shaft design features the compressor 18 driven by a compressor turbine, both mounted on the same shaft, and a separate power turbine 16A and pump 16B mounted on the output shaft.

Figure 8 illustrates the apparatus 10 for producing motive power in conjunction with a flywheel/battery arrangement 24. To reduce fuel consumption at part load and to improve response to speed control changes, flywheels are incorporated. In this embodiment the gas turbine 16 is mechanically coupled to the flywheels. This system combines fossil-burning units and an energy storage system. The apparatus 10 is designed so that the fuel-burning unit such as natural gas operates under nearly steady-state conditions which allows the turbine 16 to operate at its maximum efficiency level, and to meet the fluctuating power requirements of the vehicle by coupling the engine's output to an energy storage system such as batteries, hydraulic accumulators or flywheels. Energy is stored during periods when the power unit's steady state output is greater than the vehicle requirements, for example at low speed in traffic, and the stored energy is then used to supplement the power unit output when this is less than the vehicle requirements, such as when accelerating.

The mixing chamber 14 plays a very important function in the operation of the apparatus 10.

Figure 9 shows a sectional view of one example of a mixing apparatus 30 for mixing dry and wet fractions of a compressible fluid, in this example the refrigerant gas. The mixing apparatus 30 comprises a mixing chamber 50 together with an inlet and an outlet head 52, 54 respectively. The mixing chamber 50 is tubular with externally threaded portions 56A/B formed at each end thereof. An annular recess 58A/B is formed adjacent each of the threaded portions 56A/B, the annular recess 58 A/B designed to seat an O-ring seal 60 A/B respectively.

The inlet head 52 is generally cup-shaped with a centrally located dry fraction inlet aperture 62 and four (4) wet fraction inlet apertures 64 disposed circumferentially thereabout. The dry and wet inlet apertures 62, 64 are designed to receive a dry and wet fraction, respectively, of the refrigerant gas. Each aperture 62, 64 includes an internal thread and is configured to threadably receive a conventional nozzle fitting (not shown) . The nozzle fitting for the wet fraction inlet aperture 64 has a relatively fine orifice which effects atomisation of the wet fraction refrigerant. The wet fraction inlet apertures 64 are directed inwardly at an angle of approximately 15° relative to an axis of the dry fraction inlet aperture 62.

A perimeter wall 66 of the inlet head 52 is threaded internally complementary to the external thread 56A/B formed on each end of the mixing chamber 50. The inlet head 52 thus threadably connects to the mixing chamber 50 with the O-ring seal 60A providing an appropriate seal.

The outlet head 54 is also generally cup-shaped but with a conical-frustum shaped bottom wall 68 formed continuous with an internally threaded perimeter wall 70. The bottom wall includes four (4) outlet apertures 72 directed inwardly at an angle of approximately 30° to an axis of the mixing chamber 50. The outlet head 54 threadably connects to the mixing chamber 50 in a similar manner as the inlet head 52.

The mixing chamber 50 together with the inlet and outlet heads 52, 54 are configured to provide intimate mixing of the dry and wet fractions of the refrigerant gas . This is essential in the effective operation of the turbine or pump 16A or 16B to effect the attraction of the fluid to the faces of the turbine or pump discs. This together with the resistance of the wet fluid particles to molecular separation combines in transmitting the kinetic or velocity energy of the motive fluid to the discs and shaft of the turbine or pump 16A or 16B. Furthermore, the temperature of the refrigerant gas exhausted from the turbine or pump 16A or 16B is relatively low being close to its saturation point so that the cool load required is minimised.

Now that numerous possible embodiments of the present invention have been described in some detail it will be apparent to those skilled in the art that the described apparatuses and methods for producing motive power via a turbine have at least the following advantages: (i) the apparatuses and methods have relatively high thermal efficiencies in the order of two (2) to three (3) times that of a conventional gas turbine;

(ii) they produce relatively low levels of environmentally damaging emissions including CO, NO_x, hydrocarbons, and unburnt fuel;

(iii) the apparatuses are relatively inexpensive to manufacture and maintain and exhibits relatively low running costs; (iv) the apparatuses for producing motive power are relatively lightweight for any given power output and produces relatively low vibration and noise levels; (v) they do not require cooling water or other cooling fluids in maintaining low gas turbine temperatures; (vi) the apparatus and method when applicable to a motor vehicle provide good fuel economy at part loads and respond well to speed control changes;

(vii) the production of a wet gas via the mixing chamber optimises the performance of the boundary-layer gas turbine which operates on a wet gas so as to produce the maximum power effect through liquid drag and adhesion in an elevated temperature and pressure context; (viii) the temperature of the wet gas at the outlet of the mixing chamber can be controlled so that relatively inexpensive medium to high temperature alloys can be used; (ix) in the combustion process no cooling is required so there is no waste of energy, the phase change process of the conditioning liquid being carried out at the mixing chamber by converting the conditioning liquid into vapour, generally water and steam respectively, with no heat and energy losses; (x) the turbine efficiency is further improved because of an increase in total mass flow as a result of the conditioning liquid, typically water, being added to the mixing chamber;

(xi) the mixing chamber creates high operating pressure characteristics together with high operating temperature;

(xii) the turbine efficiency is improved by the inclusion of the pump as a result of the maximised use of the latent heat energy in the wet stream combined with the boundary layer adhesion and viscosity effects; (xiii) the system produces a higher level of torque as a result of the inclusion of the pump;

(xiv) the selection of salty or contaminated water as the conditioning liquid facilitates the production of clean water as a product of the apparatus .

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. For example, the gas and conditioning liquid can be directly or separately introduced into the turbine itself without the necessity of a mixing chamber. The introduction of the gas and conditioning liquid may be via a nozzle or other aperture arranged in parallel or series . The conditioning of the gas by the conditioning liquid then occurs within or adjacent the turbine. The flow rate and temperature of the conditioning liquid can be controlled to optimise the operation of the apparatus according to whether or not clean water is to be produced in addition to motive power. In another example the conditioning liquid can be a refrigerant liquid which can achieve a gaseous phase change at a low temperature typically less than 60°C thereby enabling the use of stored or circulated solar heat energy to energise the apparatus. Such example is typically a "closed system" whereby the refrigerant liquid is continuously recycled and not discharged to atmosphere.

All such variations and modifications are to be considered within the ambit of the present invention the nature of which is to be determined from the foregoing description.

Claims

CLAIMS ;

1. An apparatus for producing motive power, said apparatus comprising: a mixing chamber being adapted to receive and intimately mix a gas and a conditioning liquid so as to produce a wet gas; and a turbine being operatively coupled to the mixing chamber whereby, in use, a flow of the wet gas from the mixing chamber can be expanded through the turbine which thus provides the motive power.

2. An apparatus for producing motive power, said apparatus comprising: a mixing chamber being adapted to receive and intimately mix a gas and a conditioning liquid so as to produce a wet gas; a turbine being operatively coupled to the mixing chambe ; and a pump being operatively coupled to the turbine whereby, in use, a flow of the wet gas from the mixing chamber can be expanded through the turbine which thus provides the motive power and an exhaust wet gas from the turbine can be further exhausted of its heat energy whilst increasing the torque on the turbine.

3. An apparatus as defined in claim 2 further comprising a heat exchanger adapted to receive and cool an exhaust wet gas from the pump.

4. A turbine for producing motive power, said turbine being adapted to receive and intimately mix a gas and a conditioning liquid so as to produce a wet gas within or adjacent the turbine whereby, in use, a flow of the wet gas can be expanded through the turbine which thus provides the motive power.

5. A turbine as defined in claim 4 which is a boundary-layer turbine which operates effectively with the wet gas, the turbine having a plurality of discs fixed axially to a shaft which is journalled within a sealed casing.

6. A pump adapted to couple to a shaft of a turbine, the pump being designed to accept an exhaust of the turbine and to increase torque on the turbine shaft by further utilising the energy in a conditioning liquid which together with a gas is mixed to produce a wet gas which is received in the turbine.

7. A pump as defined in claim 6 which is a boundary layer pump which operates effectively with the wet gas, the pump having a plurality of discs fixed axially to the turbine shaft which is journalled within a casing.

8. A pump as defined in claim 7 wherein the casing is open at an outer circumference to facilitate expulsion of the pumped wet gas to the heat exchanger for removal of contaminants or to a holding or waste or other receptacle.

9. An apparatus, turbine or pump as defined in any one of the preceding claims wherein the gas is a combustion gas.

10. An apparatus, turbine or pump as defined in any one of claims 1 to 8 wherein the gas is taken from a low temperature heat source, such as exhaust gas from a combustion engine, so as to heat and mix with the conditioning liquid to provide the wet gas at a desirable temperature and pressure.

11. An apparatus as defined in any one of claims 1 to 3 further comprising a combustion chamber being operatively coupled to the mixing chamber and designed to receive air and a fuel which when burnt within the combustion chamber produce the combustion gas .

12. An apparatus as defined in claim 11 wherein the combustion chamber is operated at a stoichiometric or excess air to fuel mixture ratio to ensure complete combustion of the fuel and thus minimise discharge of environmentally damaging emissions including unburnt fuel .

13. An apparatus as defined in claim 11 or 12 also including an air compressor coupled to the combustion chamber so that the air received by said chamber is compressed, the air compressor being driven by a compressor shaft operatively coupled to the turbine.

14. An apparatus as defined in claim 13 further comprising a heat exchanger coupled between the turbine and the air compressor so that exhaust gas from the turbine can preheat air being fed to the air compressor prior to its burning with the fuel in the combustion chamber.

15. An apparatus as defined in claim 1 or 2 wherein the mixing chamber includes an injection mechanism which is designed to receive the conditioning liquid and to inject it into said chamber in the form of relatively fine atomised droplets .

16. An apparatus as defined in claim 15 wherein the mixing chamber is one of a plurality of mixing chambers each being connected to one of a number of inlet nozzles of the turbine, said nozzles being spaced circumferentially about the sealed casing of the turbine.

17. An apparatus as defined in claim 2 wherein the apparatus for producing only motive power is a "closed cycle" including a condenser coupled between the pump and the mixing chamber, the condenser being designed to cool and thus at least partly condense the exhaust gas of the pump so that said condensed exhaust gas can be recirculated to the mixing chamber as the conditioning liquid.

18. An apparatus as defined in claim 2 wherein the apparatus for producing motive power and clean water is an "open cycle" where the conditioning liquid is salty or contaminated water which becomes steam in the mixing chamber with the flow rate of the conditioning liquid being determined so that it maintains a steam condition on its expulsion from the pump into a heat exchanger wherein the solids in suspension are separated from the water vapour thereby allowing the water vapour to condense the clean water for collection in a water storage tank.

19. An apparatus as defined in claim 1 or 2 further including a generator or electric motor operatively coupled to an output shaft of the turbine.

20. An apparatus as defined in claim 19 also including a flywheel arrangement operatively coupled to the output shaft, the flywheel designed to store the motive power within energy storage means such as batteries.

21. A method of producing motive power comprising the steps of: producing a wet gas by the intimate mixing of a gas and a conditioning liquid; and expanding the wet gas through a turbine and the pump so as to provide the motive power.

22. A method as defined in claim 21 wherein the intimate mixing of the gas and the conditioning liquid occurs within a mixing chamber.

23. A method as defined in claim 21 wherein mixing of the gas and conditioning liquid takes place within or adjacent the turbine wherein the gas and conditioning liquid are introduced into the turbine together as a single stream or separately as two (2) streams.

24. An apparatus, turbine or pump as defined in any one of claims 1 to 20 wherein the conditioning liquid is a non-combustible liquid at the temperature of the mixing chamber .

25. An apparatus, turbine or pump as defined in claim 24 wherein the conditioning liquid is water so that wet steam is formed in the mixing chamber.