TECHNICAL FIELD OF THE INVENTION

My invention relates to a novel, revolutionary apparatus and method for the generation of electrical and mechanical power while achieving very low emission rates of nitrogen oxides. More particularly, my invention relates to a power plant driven by ramjet engine thrust modules, and to novel rotors designed to withstand the extremely high tensile stress encountered while rotatably securing such thrust modules. Power plants of that character are particularly useful for generation of electrical and mechanical power at efficiencies substantially improved over power plants currently in widespread commercial use.

BACKGROUND OF THE INVENTION

A continuing demand exists for a simple, highly efficient and inexpensive thermal power plant which can reliably provide electrical and mechanical power. A

variety of medium size electrical and/or mechanical power plants could substantially benefit from a prime mover which provides a significant improvement from currently known efficiencies. Such medium size mechanical or electrical power plants - largely in the 10 to 100 megawatt range - are required in a wide range of industrial applications, including rail locomotives, marine power systems, aircraft engines, and stationary electric power generating units. Power plants in this general size range are also well suited to use in industrial and utility cogeneration facilities. Such facilities are increasingly employed to service thermal power needs while simultaneously generating electrical power.

Power plant designs which are now commonly utilized in co-generation applications include (a) gas turbines, driven by the combustion of natural gas, fuel oil, or other fuels, which capture the thermal and kinetic energy from the combustion gases, (b) steam turbines, driven by the steam which is generated in boilers from the combustion of coal, fuel oil, natural gas, solid waste, or other fuels, and (c) large scale reciprocating engines, usually diesel cycle and typically fired with fuel oils.

Of the currently available power plant technologies, diesel fueled reciprocating and advanced turbine engines have the highest efficiency levels. Efficiencies often range from 25% to 40%, based on net work produced when compared to the energy value of the fuel source. Unfortunately, with respect to the reciprocating engines, at power output levels greater than approximately 1 megawatt, the size of the pistons and other engine components required become almost unmanageably large, and as a result, widespread commercial use of such larger sized reciprocating engine systems has not been accomplished.

Gas turbines perform more reliably than reciprocating engines, and are therefore frequently employed in plants which have higher power output levels. However, because gas turbines are only moderately efficient in converting fuel to electrical energy, gas turbine powered plants are most effectively employed in co-generation systems where both electrical and thermal energy can be utilized. In that way, the moderate efficiency of a gas turbine can in part be counterbalanced by increasing the overall cycle efficiency.

Fossil fueled steam turbine electrical power generation systems are also of fairly low efficiency, often in the range of 30% to 40% . Such systems are commonly employed in both utility and industrial applications for base load electrical power generation.

This is primarily due to the high reliability of such systems . However, like gas turbine equipment, steam turbine equipment is most advantageously employed in situations where both mechanical and thermal energy may be utilized, thus increasing overall cycle efficiency.

Because of their modest efficiency in conversion of fuel input to electrical output, the most widely used types of power plants , namely gas turbines and combustion powered steam turbine systems, depend upon co-generation in industrial settings to achieve acceptable costs of production f or electricity . Therefore , it can be appreciated that it would be desirable to achieve reduced costs of electrical production by generating electrical power at higher overall efficiency rates than is commonly achieved today .

SUMMARY

I have now invented, and disclose herein, improved details for the design of a novel, revolutionary power plant. My power plant design is based on the use of a ramjet engine as the prime mover, and has greatly increased efficiencies when compared to those heretofore used power plants of which I am aware. Unlike many power plants commonly in use today, my power plant design is simple, compact, relatively inexpensive, easy to install and to service, and is otherwise superior to currently operating plants of which I am aware.

My novel power plants have a unique low aerodynamic drag rotor portion. The rotor is preferably constructed utilizing a disc of high strength composite materials. It can be operated at rotating speeds well above those which would induce tensile and compressive strains that would cause materials such as conventional steel or titanium alloys to fail in structures of similar shape.

The aerodynamic design used in my power plant overcomes two important and serious problems. First, at the supersonic tip speeds at which my device operates, the aerodynamic design minimizes drag. Thus, it

minimizes parasitic losses to the power plant due to the drag resulting from the movement of the rotor through an airstream. This is important commercially because it enables a power plant to avoid large parasitic losses that undesirably consume fuel and reduce overall efficiency. Second, the materials design and specification provides the necessary tensile and compressive strength, where needed in the rotor, to prevent internal separation of the rotor by virtue of the centrifugal and centripetal forces acting on the rotor materials.

I have now developed a novel rotor design for use in combination with a ramjet driven power generation system. In one embodiment, the rotor section comprises a solid disc. The rotor section rotates in a housing which uses boundary layer removal via way of air injection on the rotor face.

Attached to the periphery of the rotor are inboard portions of ramjet engine thrust modules. The inboard portions of ramjet engines are situated so as to engage and to compress that portion of the airstream which is impinged by the ramjet upon its rotation about the aforementioned output shaft portions between the inboard

portion of the ramjet engine and the outboard housing wall. I have also provided in my design a feature to insure that a relatively clean airstream (free of the ramjet's own wake turbulence) will be encountered by the rotating ramjet. This is accomplished by rotating the inboard ramjet portion in a supplied air plenum which is oriented generally perpendicular to the aforementioned axis of rotation, and circulating therethrough an airstream which replaces the gases scooped up by the ramjet compression and sweeps away its aerodynamic wake.

Fuel is injected from the interior housing wall, by adding it to the air which is to be captured and compressed at the ramjet inlet. The fuel may be conveniently provided to the ramjet engine combustion chamber through use of fuel supply passageways communicating between the fuel source and the interior housing. The fuel injection ports allow fuel to enter the air stream to be mixed with the inlet air before it arrives at the ramjet engine combustion chamber. The combustion gases formed by oxidation of the fuel escape rearwardly from the ramjet nozzle, thrusting the ramjet tangentially, thus turning the rotor and the output shaft portions. The power generated by the turning shaft may be used directly in mechanical form, or may be

used to power an electrical generator and thus generate electricity.

The unique rotor structure and ramjet structure provided enables this power generation apparatus to operate at supersonic velocities, and preferably, at high supersonic velocities, when compared to prior devices of which I am aware. For example, ramjet operation should proceed in excess of Mach 1, and normally, in excess of Mach 2. For improved performance, preferably, operation of the ramjet should occur in a range from approximately Mach 2 to approximately Mach 4.5. More preferably, operation of the ramjet should occur in the range from about at least Mach 3 to about Mach 4.5 or thereabouts. Most preferably, the operation of the ramjet should occur in the Mach 3.5 range.

Preferably, exhaust combustion gases from the ramjet are substantially separated from the outbound air stream travelling through the supplied air plenum. In my improved cogeneration plant design, the combustion exhaust gas duct is used to collect and discharge the exhaust gas stream to a conduit for transport to a heat exchanger, where the gases may be cooled by way of

heating up a heat transfer fluid, such as water, in which case the production of hot water or steam results. The heat transfer fluid may be utilized for thermal purposes, or for mechanical purposes, such as driving a steam turbine.

Ultimately, the cooled combustion gases are exhausted to the ambient air. However, by way of the unique technique of completely mixing combustion gas in the supersonic shocks between the ramjet inlet ramps, and due to the short residence time in the combustor, my novel power plant minimizes production of nitrogen oxide to emission levels well below those currently achieved in the industry. Further, variations in the air flow configuration and in provision of the fuel supply may be made by those skilled in the art without departing from the teachings hereof. Finally, in addition to the foregoing, my novel power plant is simple, durable, and relatively inexpensive to manufacture.

OBJECTS, ADVANTAGES, AND FEATURES OF THE INVENTION

From the foregoing, it will be apparent to the reader that one important and primary object of the present invention resides in the provision of novel,

improved mechanical devices to generate mechanical and electrical power.

More specifically, an important object of my invention is to provide a ramjet driven power generation plant which is capable of withstanding the stress and strain of high speed rotation, so as to reliably provide a method of power generation at high efficiency.

Other important but more specific objects of the invention reside in the provision of power generation plants as described in the preceding paragraph which:

allow the generation of power to be done in a simple, direct manner; have a minimum of mechanical parts; avoid complex subsystems; require less physical space than existing technology power plants; are easy to construct, to start, and to service; have high efficiency rates; that is, to provide high heat and high work outputs relative to the heating value of fuel input to the power plant; in conjunction with the preceding object, provide lower power costs to the power plant

operator and thus to the power purchaser than is presently the case; cleanly burns fossil fuels; in conjunction with the just mentioned object, results in fewer negative environmental impacts than most power generation facilities currently in use; have a fuel supply design which efficiently supplies a ramjet; have a rotating element with a structure able to withstand the stresses and strains of rotating at very high tip speeds; and which have a rotating element design which provides operation with minimal aerodynamic drag.

A feature of one embodiment of the present invention is the use of a novel aerodynamic design configuration which provides minimal aerodynamic drag at high rotational design tip speeds, thereby enabling the power plant to minimize parasitic losses, with the resulting advantage of high overall cycle efficiencies.

Another feature of the present invention is the use of a high strength rotor structure.

Other important objects, features, and additional advantages of my invention will become apparent to those skilled in the art from the foregoing and from the detailed description which follows and the appended claims, in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing, identical structures shown in the several figures will be referred to by identical reference numerals without further mention.

FIG. 1 provides a cut-away perspective view of the rotating assembly of my novel power plant apparatus, showing rotating output shaft portion affixed to a rotor and rotatably secured therewith, with the rotor having (i) a central hub, (ii) a tapered disc portion, (iii) a and unshrouded thrust module. Additionally, an exhaust combustion gas duct is illustrated.

FIG. 2 is a top plan view with a partial cross section, looking downward at the various components of my power plant.

FIG. 3 is a perspective view showing an enlarged detail of the rotor for my power plant apparatus, showing the location of the integrally constructed ramjet thrust module inboard portion, a central hub, and

a rotating output shaft portions.

FIG. 4 is a cross sectional view, taken as if across line 5-5 of FIG. 4, but showing additional detail with respect to the air injection system used to reduce boundary layer drag on the rotor.

FIG. 5 is a partial cross sectional view, similar to that shown in FIG. 4, but providing still further detail of the air injection system used for simultaneous cooling and boundary layer drag reduction. FIG. 6 is a side view of the rotor construction, showing the use of a non-circular disk with an external segmented cooling cap and integral thrust module, and showing the wall structure which forms the outboard portion of the thrust module as the unshrouded thrust module rotates therein.

FIG. 7 is similar to FIG. 6, but showing only the rotor, thrust module inboard portions, and cooling cap.

FIG. 8 provides a perspective view of the unshrouded thrust module, showing the structural layout which allows cooling.

FIG. 9 is a top plan view of the unshrouded thrust module, further illustrating the layout of the cooling passageways.

FIG. 10 is a perspective view of the rotor cooling caps, showing the location of cooling passageways.

FIG. 11 is a diagrammatic illustration of the operation of a segmented annular gate valve, showing an annular gate valve in a closed position.

FIG. 12 is a diagrammatic illustration of the operation of the segmented annular gate valve first set forth in FIG. 11, showing an annular gate valve in an open position.

FIG. 13 is a side elevation view of a power plant constructed using my supersonic ramjet thrust module in conjunction with a conventional electrical generator set and steam turbine.

FIG. 14 is a plan view of a power plant constructed using my supersonic ramjet thrust module in conjunction with a conventional electrical generator set and steam turbine, as first illustrated in FIG. 13 above.

DESCRIPTION OF INVENTION

Prime Mover for Power Plant

Referring now to the drawing, FIG. 1 depicts a partial cut-away perspective view of my novel power plant 100. Rotating assembly 102 (at respective portions thereof) revolves in close proximity to the fixed inboard housing 104 and to the inner surface 105 of stationary circumferential outboard housing 106, along a central axis C ^L of rotation. As illustrated, the rotating assembly 102 includes an output shaft 108 which provides and defines the axis of rotation. The shaft 108 is affixed to rotor 110 at a central hub 112, and rotatably secured therewith. As is most clearly evident in FIGS. 6 or 7, the rotor 110 is comprised of four basic sections, (i) a central hub 112, (ii) a solid tapered primary disc portion 114, (iii) cooling and protective rotor cap rim segments 116, and (iv) an unshrouded thrust module 118. The ramjet construction and operation provided in my power plant 100 is unique. The unshrouded (or alternately partially shrouded) integral thrust modules 118 must work with the interior wall 105 of the outboard housing 106 in order to achieve compression in incoming air. This is seen in FIGS. 6 and 8, for example, where

the ramjet thrust module 118 inlet includes a first ramp 120 which performs the bulk of compression of inlet air flow 122.

A pair of inlet structures 130, preferably substantially parallel to the spin axis of rotor 110, provides the necessary containment and ramp surface 132 for compression of incoming air along the the ramjet thrust module 118 inlet. However, on the outboard side 134, thrust module has a slot opening defined by first 136 and second 138 inlet walls. These inlet walls, and corresponding trailing edge portions 140 and 142 which form outlet walls, allows the use of the surface 105 of peripheral housing wall 106, and complementary surface 144 (if any) of gate valve 146 as the remaining inlet air compression surface for the ramjet thrust module 118.

The importance of the development of my unique, unshrouded ramjet thrust module 118 will become further evident when the method of starting my ramjet driven power plant 100 is discussed hereinbelow.

Turning now to FIG. 2, the overall structure of the prime mover in my power plant is further illustrated in a partial cross-sectional view. Ramjet thrust module 118 are suitable for oxidizing a fuel supplied thereto and thus creating a propulsive thrust from the exhaust gases 210 which are thereby created. Ideally, ramjet

thrust modules 118 utilize oxygen from the incoming airflow 182 (from an ambient air supply at the plant site) , as an oxidant source. Intake air 182 is preferably provided motor M driven high speed intake fan F, which cleans intake air through an intake air filter AF. Airflow 182 which is not consumed becomes part of the cool air flow and exits the cool air A plenum 350 as described below. Ramjet thrust modules 118 are integrally provided at the outer reaches of rotor 110, so that the propulsive effect of the ramjet thrust modules 118 can be utilized to turn a rotating assembly, including rotor 110, central hub 112, the output shaft 108, so as to allow the ramjets 118, output shaft 108, and rotor 110, to rotate together as a single rotating assembly with respect to stationary circumferential inboard support structure or housing 104.

The rotating assembly 10 (see FIGS. 2 or 4) are rotatably secured in an operating position by a fixed support structure or inboard housing 104 in a manner suitable for extremely high speed operation of the rotating assembly, particularly for operation in the range of 10,000 to 20,000 rpm, or higher. In this regard, suitable inlet side bearings 220, 222, 224, 226, and outlet side bearings 230, 232, 234, and 236, or suitable variations thereof, must provide adequate bearing support for high speed rotation and thrust, with

minimum friction. The detailed bearing and lubrication systems may be provided by any convenient means by those knowledgeable in high speed rotating machinery, and need not be further discussed herein. Inboard housing 104 includes several important features which are provided to reduce aerodynamic drag, particularly on the inboard, solid rotor face portions 240. First, an inlet side inboard housing portion 300 is provided to smooth inlet air flow 182 as it approaches the thrust modules 118. Referring to FIG. 4, a complementary outlet side inboard housing portion 302 is provided to smooth exit flow of sweep air. An inlet side, substantially annular rotor housing 310 with rotor side surface 312, and an outlet side, substantially annular rotor housing 314 with rotor side surface 316 are provided. The solid face portions 240 of rotor 110 rotates so that rotor side surfaces 312 and 316 are in close proximity to rotor solid face portion 240.

Injection air 250 for boundary layer control is provided through a plurality of apertures 252 in the outboard portion 254 of surface 312, and in the outboard portion 256 of surface 316. Air 250 impacts face 240 of rotor and then sweeps outward, cooling rotor cap segments 116, as well as the thrust module 118. Adequate velocity of the air flowing through the boundary layer injection apertures 252 may be determined

by those knowledgeable in the art and to whom this specification is addressed.

The structural design and material systems used for the rotor 110 is critical because of the centrifugal loads induced by the extreme speed with which the rotor turns. The rotor 110 for the proposed power plant are anticipated to optimally turn at speeds between 10,000 and 20,000 rpm. Newly developed metal matrix composites do provide acceptable specific strength characteristics and can survive the required loads. The safety margin available when using such materials can be increased by increasing the material taper ratio, and when using such technique, other materials of construction, including suitable composite carbon devices, become feasible. Preferably, in order to minimize the actual loading to the extent practical, the rotor means should be built with high strength materials in shapes which have large material taper ratios. This basically means that at increasing radial station, (further from the axis of rotation) , the rotor means should become increasingly slender or thin. Fundamentally, reduction of rotating mass results in reduction of the encountered stress operating at the center of rotation.

Attention is now directed to FIGS. 13 and 14, where my power plant is illustrated in conjunction with necessary power generation equipment. Intake air 182

flows past turbine room wall and through fan F as described above, and fuel is consumed in thrust module 118, to provide thrust to turn shaft 108. The shaft 108 acts in conventional fashion to transmit mechanical power to the primary gear-box 400. The gear-box 400 reduces the output shaft 108 speed to a sufficiently low level to accommodate the capabilities of the desired application. In FIGS. 13 and 14, the primary gear-box 400 is connected by shaft 402 to primary electrical generator 404, suited to generate electrical power for transmission to a power grid or other electrical load. However, shaft 402 could be applied directly to do desired mechanical work.

A secondary gear-box 410 from a steam turbine 410 is also shown connected by shaft 406 to generator 404.

Also shown in FIGS. 12 and 13 is the use of combustion exhaust gases 210 from ramjets 118 in a cogeneration system. As shown, the exhaust gases are conveniently collected by an exhaust gas duct 430. The exhaust gas duct 430 substantially surrounds and laterally encloses the through air plenum 350. Exhaust gases 210 are directed slightly outward toward a second housing sidewall 432 due to the rotational motion of the ramjet thrust modules and the direction of their exhaust vector, and are largely collected in exhaust gas duct 430 without substantial cooling of the same by mixing

with the supplied air vent stream passing through plenum 350. The exhaust gases are sent through duct 430 to a heat exchanger 440, through which a secondary working fluid or coolant 442 is circulated. In the usual design, the working fluid 442 will be water. The water can be heated to high pressure steam, and can thereafter be used: (a) to drive a steam turbine, for (i) shaft work or (ii) to drive an electrical generator, or (b) as process heat. The hot exhaust gases 210 from the ramjets 118 flow through heat exchanger 440, thus heating the fluid 442 therein. It may be convenient to design the heat exchanger system 440 as a boiler so that the fluid 442 changes state, i.e., water becomes steam, as it is heated, and in such cases the stream indicated as coolant out will be steam, suitable for use in heating, or in mechanical applications as illustrated with steam provided to a steam turbine 410 to produce shaft work, and thence to a condenser 452, before return through liquid line R to the heat exchanger via pump 454. The turbine shaft 460 may be sent through a gearbox 462 for use as shaft work in electric generator 404.

Turning now to FIGS. 11 and 12, in order to establish the desired internal shock structure in thrust module 118 for startup, the inflow must either be accelerated to a Mach number greater than the design

Mach number and then reduced after starting to the design Mach number, or the throat area must be temporarily increased to "swallow" the shock structure and thus induce startup. Depending upon the contraction ratio and Mach number, it may be impossible to increase the inflow Mach number to a sufficiently high level so as to start the inlet.

However, I have developed an alternative, unique variable geometry mechanism to decrease the through airflow through ramjet 118, thus allowing startup at lower Mach numbers. While the exact requirements can be calculated from this disclosure by those skilled in the art, it must be pointed out that the exact requirements will be based on a set of specific assumptions regarding thrust module size, free stream conditions, and fuel source. Also, component performance levels must be predicted consistent with well established test or theoretical data for the inlet, transition section, combustor, and nozzle. As seen in FIGS. 11 and 12, a series of variable position annular gate valves 146 are provided around the edge of peripheral wall 106. For starting, the annular gate valves 146 are opened in the direction of reference arrow 602 as shown in FIG. 12, forming a gap 603, so that a portion of the incoming air which is being compressed against wall surface 105 can escape outwardly

in the direction of arrows 604 and 606. The unique unshrouded ramjet 118 allows this escapement of bypass air 604 and 606. Once the ramjet 118 has "swallowed" the inlet shock structure, then the gate valve(s) 146 can be closed by actuator 610, as illustrated in FIG. 11. I have shown a hydraulic actuator 610 with shaft 612, mounted by bracket 614. Any convenient mechanical, electrical, or hydraulic actuator may be utilized as convenient for this purpose. Because the ramjet thrust determines the overall power plant output, the thrust from the ramjet is an important figure of merit for overall plant output levels. The ramjet thrust levels and the overall plant output levels increase in direct proportion with the mass captured and processed by the ramjet. Thus, doubling the inlet area and mass capture results in doubling the thrust generated, and thus results in doubling the power output of the system.

The combustor temperature is a critical factor as combustor temperature varies with varying throttle settings. Combustor temperature must be balanced with inflow rate and thrust module materials so as to maintain structural integrity in the combustor walls. To accommodate this design requirement, cast silicon carbide combustion chambers have been utilized as set forth in FIGS. 8 and 9. This combustion chamber is made

of a material with a desirable high temperature capability, selected from candidate materials include hot isostatic pressed alumina, silicon nitride, zirconia, beryllia, and silicon carbide. Ideally, the ramjet combustion chamber 118 is manufactured as a monolithic, solid cast part.

Finally, even though high combustion temperatures are experienced, my design allows extremely low nitrogen oxide output. This is because of the short residence times at the high combustion temperatures, and because the fuel is extremely well mixed. Residence times are determined by various design conditions, but as illustrated, a relatively small flow through residence time of 0.24 microseconds is expected. Fuel injected is being thoroughly mixed in by the shock front, and a well mixed air/fuel front enters the combustion chamber 118. This shock-boundry layer interaction premixing technique is a unique approach for achieving a near perfectly premixed conditions and low nitrogen oxides emission. Thus, nitrogen dioxide emissions are limited by limiting the size of highly non-equilibrium free-radical zones in the combustor. NOx emissions are estimated to be less than 5 ppm, or El is less than 0.5 grams of nitrogen dioxide per kilogram of fuel. The method and apparatus for producing mechanical, electrical, and thermal power as described above

provides a revolutionary, compact, easily constructed, cost effective power plant. The output from this power plant can be used in conjunction with existing power delivery systems, and represents a significant option for reducing air emissions by combustion of clean burning fuels. Further, given the efficiencies, dramatically less fuel will be consumed per unit of electrical, mechanical, or thermal energy generated.

It will thus be seen that the objects set forth above, including those made apparent from the proceeding description, are efficiently attained, and, since certain changes may be made in carrying out the above method and in construction of the apparatus and in practicing the methods set forth without departing from the scope of the invention, it is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, while I have set forth an exemplary design utilizing a tapered disk configuration, other embodiments, such as a tri-rotor or quad-rotor (three or four "spokes," respectively extending from a central hub) are also feasible. Also, note that as taught, for example in FIG. 7, the rotor does not have to be symmetrical, but can be of varying radius to accomodate the thrust module 118 placement.

The present embodiments are therefore to be considered in all respects as illustrative and not as restrictive. Accordingly, the scope of the invention should be determined not by the foregoing description and the embodiments illustrated, but by the appended claims, and consequently all changes, variations, and alternative embodiments which come within the meaning and range of equivalents of the appended claims are therefore intended to be embraced therein.