A reaction turbine that runs on condensing steam

Abstract

Reaction turbines work by utilizing the heat released from the condensation of steam and the inherent steam pressure and temperature head. A series of rotors with multiple curved internal passages provide compression boost between successive stages while avoiding excessive self-compression. The compression effect and shock waves generated within these passages result in high levels of condensation, thereby releasing enormous amounts of heat. The resulting hot steam and condensate droplets are ejected tangentially at the rotor circumference, generating thrust. Exhaust steam from the last stage is compressed and pumped back to the engine inlet where it is mixed with the incoming fresh steam, thus completing the system cycle efficiently without the need for large cooling towers for condensation.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Provisional Application No. 63 / 196,375, filed June 3, 2021, the contents of which are incorporated herein.

[0002] The present invention relates to reaction turbines that operate when vapor species condense to form a liquid. [Background technology]

[0003] A conventional steam turbine works by evaporating and condensing water, as described by the Rankine cycle. First, heat from fossil fuel combustion, nuclear reactions, solar radiation, or other sources is added to water in a boiler, raising the temperature of the water until steam is generated. Further heat is then added in a superheater, resulting in very hot, high-pressure steam with no residual water droplets. This superheated steam passes through a turbine, which spins a series of blades to generate shaft power. When power is removed from the system, the steam cools and loses pressure. Eventually, the steam begins to condense, creating large, large water droplets. To prevent these droplets from damaging the delicate turbine blades, the power generation process is stopped and the remaining steam is vented to a cooling tower, which releases the remaining steam heat into the environment, thereby completing the condensation process. The resulting condensed water is then pumped back into the boiler, completing the cycle. Summary of the Invention [Problem to be solved by the invention]

[0004] In this configuration, the system produces power only in the temperature range between the hot superheated steam at the turbine inlet and the cold turbine outlet where condensation begins. The system efficiency in this range is calculated from the basic Carnot relation: the difference between the temperature limits, hot and cold, divided by the temperature of the hot limit. The Carnot efficiency of a basic steam power plant is only about 36%, thereby wasting almost two-thirds of the input fuel.

[0005] The most common way to improve this poor efficiency is to increase the high temperature limit. Unfortunately, although advanced ultra-supercritical plants may eventually reach an efficiency of about 50%, such systems would be very expensive and difficult to operate. Alternatively, the Carnot relations suggest that the efficiency of the plant could be improved by lowering the outlet temperature. Unfortunately, the thermodynamics of the entire plant limit such a temperature reduction to a small level. Therefore, to achieve higher efficiency, the plant's operating modes must be extended beyond the Carnot limit. Specifically, it is necessary to utilize at least a portion of the heat that is lost through condensation in conventional Carnot power plants.

[0006] The basic principle of this process is that the high velocity steam near the exit experiences a large drop in temperature and pressure due to compressibility effects and rarefaction behind the shock wave. A large amount of condensation occurs immediately, releasing a large amount of heat to the remaining steam. This released heat increases the temperature and pressure of the remaining steam, producing more power in the subsequent stages.

[0007] In this way, the total power output is the sum of the electricity generated by the conventional Carnot cycle and the power generated from the heat released during condensation. The overall efficiency is therefore always higher than that of the conventional Carnot process alone. In fact, many operators already use this process to some extent, simply by not stopping the generation exactly at the beginning of condensation. Instead, the generation process continues until about 10% of the steam has condensed, and the resulting damage to the blades is accepted for the sake of fuel efficiency.

[0008] A limiting factor for this technology is that even turbines with the best blade curvatures using state-of-the-art alloys can only tolerate relatively mild levels of agglomeration, so to maximize condensation heat recovery new turbine designs are required that can withstand extreme erosion levels.

[0009] The market for these new turbines is very large. It ranges in size from a few kW to hundreds of MW and includes domestic, automotive, industrial and marine applications. The most important market is power generation, since steam turbines currently provide 89% of the world's electricity. To serve this market, the systems can first be configured as an extension of a conventional steam turbine, replacing a cooling tower. In this configuration, more electricity can be delivered with the same amount of fuel, while at the same time eliminating the need for large amounts of expensive cooling water, which is increasingly scarce. Such a retrofit of existing infrastructure could reduce CO2 emissions by 2030. 2 In the long term, operating near the condensation point would eliminate the need for high levels of superheating, allowing the use of solar, geothermal and other green sources that are insufficient to drive conventional steam turbines. Such systems could therefore meet CO2 emissions standards by 2050. 2 It could potentially be used for zero-emission electricity that meets the standards. [Means for solving the problem]

[0010] The invention is a reaction turbine that operates using the heat released from the condensation of steam and the inherent steam pressure and temperature head. A series of rotors, each containing multiple curved internal passages, provide compression boost between successive stages while avoiding excessive self-compression. The compression effect and shock waves generated within these passages result in high levels of condensation, which releases enormous amounts of heat. The resulting hot water vapor and condensate droplets are ejected tangentially around the rotors, generating thrust. Exhaust steam from the final stage is compressed and pumped back to the engine inlet to mix with the incoming fresh steam. This allows the system to complete the cycle efficiently without the need for large cooling towers for condensation. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a horizontal cross-section of a system having a series of rotors. [Diagram 2] Figure 2 shows a graph of temperature and pressure for one cycle of the system. [Diagram 3] FIG. 3 is a vertical cross-sectional view of the rotor taken along the central axis of the shaft. [Figure 4] FIG. 4 is a vertical cross-sectional view of the rotor perpendicular to the axis of the shaft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In FIG. 1, a reaction turbine is depicted having three rotors within a housing 30, each stage having a rotor. Any suitable number of stages may be used, including a single stage. The system uses a steam source 10, which may be from any suitable source, including the condensing exhaust of a conventional steam turbine, allowing the system to be added to an existing steam power plant. Another option is to feed high pressure steam from a boiler directly into the system, eliminating the need for a superheater or conventional steam turbine components.

[0013] Steam from the inlet source 10 enters the mixing chamber 12. The fresh steam is mixed with steam from conduit 16 that is recycled from the system exhaust. As will be described below, the recycle process results in essentially saturated steam containing a mixture of water droplets and steam. The quality of the recycled steam is therefore less than 100%, similar to the incoming feed steam. Because the pressures, temperatures and qualities of the fresh and recycled steam are very similar, the two streams can be easily combined in the mixing chamber 12. The output of the mixing chamber therefore consists of a homogenous mixture of water droplets and steam, with a steam quality slightly less than 100%.

[0014] Compared to the input steam of a conventional turbine, the output of the mixing chamber is at a relatively low pressure. Therefore, the volume of the output of the mixing chamber is relatively large, which requires a larger flow cross-sectional area than a conventional turbine. The solid shaft 22 has seals 24, 26 on the inlet and outlet sides of the housing 30. The output from the mixing chamber 12 travels through a conduit 14 and enters the housing 30 through a port 18 in the housing. The mixture of steam and liquid droplets fills the volume around the central shaft 22 and spreads to the rotor body. The horizontal partition 28 confines the mixture of steam and liquid droplets between the housing and the first surface of the rotor with a seal formed between the horizontal partition 28 and the first surface of the rotating rotor. Thus, the incoming flow is directed towards the inlet of the rotor. The steam then passes through a flow passage in the rotor that terminates at an outlet nozzle 64. The thrust of the expelled spent steam and liquid droplets causes the rotor to rotate, as will be explained in more detail below.

[0015] The exhaust then enters the space between the downstream side of the rotor, confined by seal 80, and the next vertical partition 84. The exhaust then enters an intercooled compressor 82 and exits downstream of vertical partition 84. The partially compressed exhaust then follows the process steps described above for the first rotor. Exhaust from the second stage then enters the third stage, and so on. FIG. 1 shows three representative stages 32, 34, 36 in the housing 30, although a different number of stages may be used. Each stage has a rotor 50.

[0016] Following conventional turbine practice, the respective ratios of inlet and outlet pressures are approximately the same for all stages. For example, the design pressure ratios at start-up at atmospheric pressure are 3:1 for the first stage, 1:0.3 for the second stage, and 0.3:0.01 for the final stage before compression back to the inlet. Outlets 42, 44, 46 at each stage remove condensate, which can be returned to the boiler for conversion to steam and reuse within the system. The rapidly spinning rotor housing captures liquid droplets in the exhaust, thereby acting as a cyclone separator, and directs the condensate to its respective outlet.

[0017] Once the pressure has dropped to a level where further expansion is not practical, for example below 0.1 atmospheres, the remaining exhaust vapor may be recirculated through conduit 16. The overall recirculation configuration is shown in Figure 1. The process begins with a recycle compressor 88 located after the last power rotor stage 36. The compressed vapor then passes through return line 16 into mixing chamber 12.

[0018] The load is placed across the shaft seal 26 just after the recycle compressor 88. The rotation of the shaft can be utilized for any one of a number of applications. One such application is to have the rotor 22 drive a generator 23 to generate electrical power.

[0019] Additional components are required for the start-up and extended operation of the system. The first such component is a vacuum source to extract air and contaminated steam during start-up. Because large volumes of steam are present, a conventional ejector 90 is a possible vacuum source, but mechanical piston pumps, turbine pumps, and small cooling towers are also alternatives. After sufficient vacuum is obtained, the rotor must be rotated fast enough to generate sufficient compression. Following the conventional Brayton cycle approach, a convenient start-up method is to use an external voltage source to reverse the rotation of the generator, thereby temporarily converting it into a starter motor. Finally, small heat exchangers can be added to the system to aid both in start-up and in improving on-line efficiency. One such heat exchanger 48 is used for the recirculated exhaust stream to capture residual heat and at the same time improve the vacuum. Such heat exchangers are much smaller than the cooling towers of conventional power plants, allowing them to operate on small amounts of water or air in dry environments.

[0020] Figure 2 summarizes the unique thermodynamic cycle of the system shown in Figure 1. The cycle begins with the pressure and temperature of the incoming vapor source 10. Since the vapor is saturated at this point, the "saturation curve" in Figure 2 provides the temperature at any pressure. Water at temperatures above this curve is in the gas phase, and water at temperatures below this curve is in the liquid phase. Although steam is disclosed as the working fluid, other low boiling point fluids such as light hydrocarbons (propane, butane, pentane, hexane), silicone oils, fluorocarbons, etc. can also be used as the working fluid.

[0021] Since one application of the present invention is as an add-on module for conventional commercial steam turbines, representative starting values ​​for pressure and temperature can be obtained from exhaust measurements of each of the existing commercial equipment. Thus, the exhaust pressure at point A is approximately 3.0 atm, and from the saturation curve in Figure 2, the starting temperature is approximately 407K.

[0022] The pressure is then increased by the intercooled compressor 82 and the self-compressing segment of the rotor 50, while the temperature increases from point A to point B along the “Cold Adiabat” of FIG. 2. Heat is then released by condensation caused by impingement in the expansion section of the rotor 50, which will be described later, thereby increasing the temperature isobarically to point C. This process is similar to the compressor and combustor components of the conventional Brayton gas turbine cycle. The hot, high-pressure steam then expands along the “Hot Adiabat” of FIG. 2, terminating at point D. This process step occurs in the expansion section after the rotor 50, as described below. This step is similar to the adiabatic expansion that occurs in the conventional Rankine steam cycle. Thus, the new cycle combines unique parts of both the Brayton steam turbine cycle and the Rankine steam turbine cycle.

[0023] The next three steps in this cycle are unique to the present invention. First, because the exhaust from rotor 50 is essentially stationary when it leaves exit nozzle 64, as described below, the static temperature of the supersonic vapor in the rotor is the stagnation temperature of the resulting essentially stationary exhaust contained within housing 30. The difference between the stagnation temperature from the fixed bed test stand nozzle and the stagnation temperature of the exhaust ejected from the moving rotor is shown as an isobaric drop from point D to point E, which is slightly below the "saturation" curve to account for nucleation effects above the Wilson line. As rotor 50 rotates shaft 22 against load 23, the heat associated with this temperature difference is converted to output work, as seen in FIG. 2.

[0024] Of course, the above analysis does not hold strictly in practice. On the contrary, the flow is not perfectly uniform at every point, so there are local variations in the mixture of droplets and vapor. Also, while the rotor extracts heat to do work, multiple processes occur simultaneously, such as the release of heat during condensation. But the net result is that the above analysis is sufficient to predict the average amount needed at every step.

[0025] Under these considerations, the conditions at point E approach the saturation curve and low temperature adiabatic curve sufficiently to initiate another cycle with point E essentially functioning as the new point A. The above cycle can then be repeated as necessary, with successively lower starting pressures in stages 32, 34 and 36. The end result will be a unique staging capacity, as shown with each successive pressure ratio described in the 3:1 example above.

[0026] After the final stage, the remaining vapor is compressed by recycle compressor 88 and returned to mixing chamber 12 through recycle conduit 16. Using the compact heat exchanger 48 previously described, the temperature of final point E can be cooled to approximately point F on the low temperature adiabatic curve. Simple adiabatic compression then raises the vapor pressure and temperature from point F back to the original conditions of starting point A, which is again the condition of mixing chamber 12.

[0027] Note that the above cycle analysis does not include the removal of condensate in the drain pipes 42, 44 and 46. The removed liquid is not necessary for the calculation of the ideal gas law governing steam behavior. However, when looking at the cycle as a whole, the amount of steam processed at each successive stage decreases as liquid is gradually removed. Thus, the overall energy balance of the complete system is highly favorable, since the compression of the small final exhaust steam mass requires much less work than the work available from the expansion of the much larger initial mass.

[0028] Figure 3 shows the details of a single rotor 50 within one stage. The overall design of this rotor follows de Laval's general rule for optimizing efficiency: introduce the fluid slowly and steadily into the turbine, extract work with minimal losses, and then release the exhaust as slowly and steadily as possible.

[0029] Using the de Laval approach, the first component in Figure 3 is the inlet scoop assembly 60. This assembly consists of a set of blades attached to the central shaft 22, much like a motorboat impeller, that serve to funnel the fluid into the rotor inlet. The scoop opens tangentially to the shaft 22. The upstream side of the scoop is immersed in the relatively stagnant high pressure steam and droplet mixture contained within the housing 30. The downstream side of the scoop is parallel to the shaft 22. As the shaft 22 rotates, the scoop 60 draws in the surrounding mixture and directs the flow parallel to the axis of the shaft 22. The scoop 60 is located close to the central shaft 22, thereby minimizing the scoop velocity and therefore erosion of the scoop due to collisions with water droplets that may become entrained in the working fluid. As a result, this system meets the de Laval ideal inlet conditions.

[0030] The next step in de Laval's overall technology is to extract work with minimal losses. In the present invention, this step involves directing the working fluid through a set of helical internal passages, as described below with respect to Figure 4. The remaining de Laval condition is to exhaust the exhaust with minimal losses. The basic principle of the present invention is that the exit nozzle around the rotor operates like a rocket nozzle. Specifically, maximum efficiency occurs when the exhaust velocity from the nozzle is equal to the rocket velocity and the opposite case occurs, where the exhaust remains stationary in space. The opposite case is to fire the nozzle over a fixed test frame, where the high velocity exhaust wastes maximum kinetic energy and produces no power.

[0031] Therefore, to apply this simple approach to the present invention, the rotor speed of the peripheral exhaust nozzle must be matched to the exhaust velocity of the spent steam. The static and stagnation temperature discussion in the thermodynamic cycle above is shown in Figure 2. However, using standard compressible flow relationships for steam at the above conditions results in supersonic exhaust velocities. Such velocities are necessary for shock condensation, as described below, but also generate severe centrifugal forces on the rotor.

[0032] The rotor design is therefore reduced to achieving extremely high rotational speeds without exceeding the mechanical limitations of the materials used to manufacture the rotor. Figures 3 and 4 show the area of ​​primary concern, near the shaft 22. On the downstream side of the rotor (opposite the inlet mentioned above), the rotor body is essentially solid from the central shaft 22 to the outer periphery, with a greater axial wall thickness near the shaft and tapering towards the outer periphery. This shape follows the well-known design of high speed flywheels used commercially for power storage.

[0033] A similar approach is used upstream of the rotor, but in this case the rotor also includes a passage 60 along the shaft 22 for admitting working fluid into the rotor body. An immediate concern is that the passage cannot support the mass of the rotor, which extends radially from the periphery to the location of the passage.

[0034] The conventional approach to this problem is to take in the working fluid through a hollow central shaft and then rotate the fluid radially outward. Unfortunately, the high flow rates at low pressures required in this invention make the hollow central shaft too large to be practical, and there are also problems with feeding the power from the upstream stage to the downstream stage.

[0035] To avoid this problem, the present invention extends the length of the inlet channel in the upstream direction, and using the definition of Young's modulus, this extended portion 52 provides the additional material needed to support the inlet wall despite the presence of the inlet channel.

[0036] In the space bounded by the upstream and downstream walls, the flow passages run outward from a central plenum 54. From this plenum 54, multiple flow passages extend to outlet nozzles at the periphery. The initial flow passages from the plenum to the periphery are essentially radially outward, commonly referred to as an orange cross section. In this region, unsupported centrifugal loads on the flow passage walls are minimized.

[0037] However, beyond that distance, the path spirals in a plane perpendicular to the axis of rotation 22, as shown in FIG. 4. At this point, the spiral flow path enters a plane parallel to the axis of rotation 22, as shown in FIG. 3. This transition may occur near the throat 68, but this is not a limiting requirement. At this point, the concern is that the centrifugal forces will become large enough to cause the walls of the flow path to collapse. Specifically, the forces will collapse the wall components perpendicular to the radial vector, potentially causing catastrophic failure, while the parallel components will not be damaged. This effect is most severe at the periphery, where the forces are greatest and where the outer walls are essentially completely angular.

[0038] In the present system, to minimize such damage, the normal wall components are formed as catenary arch segments 58. Catenary arches are known to be extremely strong, so the modified walls are able to withstand such unparalleled centrifugal forces. Figure 3 shows a typical catenary curve as one channel begins to spiral out of the reference plane while the second channel emerges from this plane at the exit nozzle.

[0039] The rotor can be formed from two separate discs, with a central passage milled and then the discs joined to create the desired channel passages. An alternative is to use additive manufacturing techniques to form the entire rotor in one step and, with advances in 3-D printing technology, eventually the entire turbine in a single operation. The main advantages of this method are (1) the ability to create prototypes quickly and cheaply, (2) routine manufacturing with inherent quality control, (3) high precision even with complex geometries, and (4) increased strength due to the monolithic construction and printed parts being inherently stronger than machined parts.

[0040] FIG. 4 is a vertical cross-section perpendicular to the shaft 22 of the rotor 50. In FIG. 4, two flow passages are shown extending from the central shaft 22 to the rotor periphery. (With only two flow passages, no plenum is required, and the spiral arm has the inlet of each flow passage and transitions to an axially extending section that leads to the upstream end of the rotor / As mentioned above, the pressure and temperature of the working fluid decrease along these flow passages according to the standard laws of compressible fluid dynamics. As a result, a mixture of vapor and condensed liquid leaves the nozzle at the local ambient pressure in the housing 30, contained by a sealed partition, generating thrust for the rotor 50. In FIG. 1, this configuration can be used for the first stage 32. With the 3:1 interstage pressure ratio mentioned above, the initial input of 3.0 atmospheres is thus reduced to about 1.0 atmospheres.

[0041] This lower output pressure then becomes the input pressure of the second stage 34. However, this lower pressure significantly increases the volume of the working fluid, even after adjustments for condensation, work output, etc. This increase in volume at progressively lower pressures requires increasingly larger diameter flow passages to maintain steady flow, similar to the increasingly larger diameters of successive stages used in conventional bladed steam turbines.

[0042] In this system, to compensate for the increased interstage volume, the number of channels is first increased in successive rotors. For example, the second stage 34 can have six channels instead of the two used in the first stage. Similarly, the third stage 36 can have twelve or more channels, each larger than the channels in the first stage 32. This increase in the number of channels can continue until the channels touch each other and the outer wall of one channel is also the inner wall of the adjacent channel. This arrangement takes into account that the walls of the catenary arch shown in Figure 3 overlap slightly, resulting in different sizes of adjacent channels at a particular radius.

[0043] Increasing the rotor size of successive stages can result in the exit velocity of any stage not matching the peripheral speed of the rotor of that particular stage. Since the exit velocity depends on the pressure ratio, the exit velocities should be nearly equal if the pressure ratios between stages are equal. Unfortunately, making the exit velocities of rotors with different radii between stages the same will result in severe instabilities across the central shaft. For example, the RPM of a 1m diameter rotor with an exit velocity of 300m / sec will drop by half for a 2m rotor. The resulting RPM mismatch leads to extreme vibrations, reduced efficiency, and other problems. An alternative is to vary the operating conditions of the respective rotors, especially the pressure ratios.

[0044] As previously described with respect to FIG. 3, the initial portion of the flow path from the rotating central shaft 22 to the periphery is essentially a simple radial outflow. If this radial outflow were to continue in a straight line to the periphery, the rotor motion would strongly compress the working fluid due to the Coriolis effect. The resulting compression cannot be fully recovered in the nozzle, so the high de Laval efficiency previously mentioned can only be achieved if compression is kept to a minimum. Therefore, just beyond the relatively straight initial section shown in FIG. 4, the flow path is slightly curved, with a sweeping arc towards the periphery. The appropriate value of the curvature of the arc can be calculated by routine experimentation and known techniques.

[0045] FIG. 4 shows further detail of the throat 68, approximately in the middle of the radial section. The throat has a decreasing cross section followed by an increasing cross section. The flow originating from the shaft 22 starts out slow. As the walls converge the flow accelerates, reaching Mach 1 at the narrowest point of the convergence. The flow then continues to accelerate as the passage walls diverge, becoming supersonic.

[0046] In a conventional ideal expansion system, the flow continues to accelerate until the exit pressure matches the ambient pressure and the flow ejects from the nozzle. The static pressure and temperature both decrease along this path. For a vapor stream, the temperature decreases until the static pressure falls below the saturation point, resulting in a supercooled (or undercooled) state. Lacking dust or other nucleation sites, the temperature continues to drop to the Wilson line, where homogeneous nucleation occurs. Rapid droplet growth then occurs, releasing heat and returning the vapor to a temperature just below the saturation curve.

[0047] In the present system, this droplet growth can occur in a downstream expansion zone 70 that is several times the throat diameter in length. The cross-sectional area of ​​the downstream expansion zone 70 increases in the direction of fluid flow. The degree of condensation varies with the expansion rate of the chamber, and is typically no more than about 5%. However, at high expansion rates, the heat release can become so great that the system experiences a "condensation shock" and the flow is thermally cut off. A condensation shock is not a true shock wave, since there is no actual pressure discontinuity in the region moving at high speed through the flow field. Nevertheless, the term shock is used because the system mimics some features of a real shock behavior.

[0048] Condensation shock produces droplets, but the process has low yield and potential for thermal choking, limiting its use. Instead, the system uses other techniques to generate shock waves. Common techniques include under- and over-expansion nozzles, rough channel walls, changes in cross section (from circular to rectangular), strips in the walls, flow along convex Prandtl-Meyer curvatures, and obstructions in the channel (such as wedges, cones, and mitered guides). The principle underlying these processes is that the low pressure region of the induced shock wave is sufficient to cause condensation to occur, even when conditions are insufficient for droplets to form and grow. In the steam turbine industry, this phenomenon is called non-equilibrium condensation. This situation typically occurs downstream of the rotating blades near the turbine exit, where velocities are high and the steam is close to saturation.

[0049] In FIG. 4, induced shock wave condensation occurs at a sharp bend 72 at the end of the first radial flow passage. This sharp convex curvature causes Prandtl-Meyer expansion, resulting in the condensation commonly observed in cockpits and along the following fuselage as supersonic aircraft pass through the sound barrier. To stabilize the flow through the flow passage, miter guide vanes 76 are placed through the sharpest part of the bend. These vanes extend the entire height of the flow passage and also serve to support the upper surface of the flow passage during the additive manufacturing process. In addition, these vanes also increase the stiffness of the assembled rotor. The immediate benefit of this initial induced condensation is some heat generation and recovery, along with the formation of at least some condensation nuclei that seed the subsequent condensation process.

[0050] One such process is the "overexpanded" nozzle 79 just downstream. Overexpansion refers to the nozzle walls 77 diverging to produce a more rapid increase in cross-sectional area than in the ideal expansion case described above. In such a nozzle, the expanding flow first separates from the walls, leaving a penetrating jet surrounded by a relatively stagnant sheath. Shock waves are generated at the interface between the penetrating jet and the surrounding sheath, resulting in a significant amount of condensation.

[0051] The effective length of the resulting condensation zone is typically at least 8 times the diameter of the penetrating jet, so in our case, the effective length of a 500 MW turbine would be several meters, requiring rotor diameters too large for even the largest currently available 3D printing machines.

[0052] To shorten this excess length, smaller tubes 78 are placed in the overexpansion nozzle 79. These smaller tubes 78 have a proportionately shorter effective length, thereby shortening the condensation zone and thereby allowing the condensation process to be completed within a rotor size that is practical and easy to manufacture and use.

[0053] To maximize space utilization, banks of these tubes 78 can be stacked on top of each other in the over-inflated module 79, thereby fully utilizing the available space even in a catenary arch. This arrangement therefore provides a uniform jet flow and avoids wasted space around a single large penetrating jet.

[0054] For ease of manufacturing, the inlets of each individual tube have narrow port constrictions that initiate a small-scale overexpansion process. Assemblies of these tubes can be incorporated as part of an additive manufacturing process or individually into modules that can be inserted around the rotor body. In either case, supports around the tubes seal the assembly, thereby constraining the working fluid to pass through the tubes without leaking around them. Finally, adjacent tubes in an assembly can be staggered lengthwise during manufacturing, providing complementarily spaced nodes of condensation, thereby improving overall flow uniformity.

[0055] Because the output of the tube assembly can contain large amounts of water droplets, filter 75 is placed downstream of tube 78. The filter could be placed across the entire condensation area if desired, but the location shown is particularly effective since it is just beyond the effective length of the high condensation overexpansion zone.

[0056] In summary, flow through the flow passages of each rotor results in the production of power by: (1) introducing a nearly saturated fluid into the rotor, (2) compressing the fluid if the inlet pressure is low compared to the desired outlet pressure, (3) expanding the fluid (adiabatically) to a subcooled state, (4) inducing condensation, preferably by generating a shock wave, (5) increasing the pressure and temperature of the working fluid with heat released by the condensation step, (6) expanding the heated and pressurized fluid to generate work, thereby cooling the fluid and reducing its pressure, (7) removing the condensate, (8) repeating steps 2 through 7 until the fluid is in the desired final state, and (9) returning the high droplet content exhaust fluid to the inlet to mix with the fresh inlet fluid from step 1 and repeat the process.

[0057] The present invention has been described with reference to preferred embodiments. Variations and modifications will be apparent to those skilled in the art and the invention encompasses such variations and modifications.

Claims

1. A rotor comprising: a radially extending first surface and a radially extending second surface spaced apart from the first surface; an end wall extending axially between the first surface and the second surface; at least one inlet and at least one outlet spaced radially outward from the at least one inlet; at least one flow passage extending between the at least one inlet and the at least one outlet, the at least one flow passage having a first cross-sectional area; an expansion chamber in the at least one flow path between the at least one inlet and the at least one outlet, the expansion chamber having a second cross-sectional area greater than the first cross-sectional area, the expansion rate of the cross-sectional area being sufficiently great to induce condensation; Including the rotor.

2. The rotor of claim 1 further comprising a scoop on said first surface, said scoop adjacent said at least one inlet.

3. The rotor of claim 1 further comprising a vane on a surface of the at least one flow passage.

4. The rotor of claim 1 further comprising an obstacle on a surface of the at least one flow passage.

5. The rotor of claim 1 , wherein the at least one flow passage has a first portion and a second helically extending portion extending from the first portion.

6. A rotor as described in claim 5, wherein the first portion has a throat portion, the throat portion having a first portion of decreasing cross-sectional area and a second portion of increasing cross-sectional area, the second portion being downstream of the first portion.

7. The rotor of claim 1, further comprising a plurality of tubes extending within the flow path.

8. A turbine, a housing having a first end wall, a second end wall, and at least one side wall extending between the first end wall and the second end wall; a shaft extending axially through the housing; a first partition dividing the housing into a first chamber and a second chamber, the first partition having an opening; a steam source connected to a first inlet in the first end wall; a rotor coupled to the shaft within each chamber, each rotor having a first surface, a second surface, an inlet, an outlet, and a flow passage extending between the inlet and the outlet; a first conduit within the first chamber, the first end being connected to the first end wall; a first conduit extending axially between the first inlet and the first surface of the rotor within the first chamber; the inlet of the rotor in the first chamber within the first conduit; a second conduit in the second chamber, the second conduit having a first end connected to the first partition and extending axially between the opening in the first partition and the first surface of the rotor in the second chamber; an exhaust port in the housing; The turbine includes:

9. The turbine of claim 8, further comprising a drain line connected to each chamber.

10. A second partition forming a third chamber within the housing, the second partition having an opening; a rotor in the third chamber, the rotor having a first surface, a second surface, an inlet, an outlet, and a flow passage extending between the inlet and the outlet; a third conduit between the opening in the second partition and the first surface of the rotor within the third chamber; The turbine of claim 8 further comprising:

11. The turbine of claim 8, further comprising a conduit extending from the exhaust port in the housing to the steam source.

12. The turbine described in claim 8, wherein the flow path of the rotor has an expansion chamber between the inlet and the outlet.

13. The turbine of claim 12 , wherein the flowpath of the rotor has a helical portion between the inlet and the outlet.

14. A method for driving a rotor, comprising the steps of: introducing the saturated fluid into a radially extending passage within a first rotor, the passage having an inlet and an outlet, the outlet being radially outwardly disposed relative to the inlet; expanding the fluid in the flow passage to a subcooled condition; inducing condensation within the flow passage of the first rotor; increasing the pressure and temperature of the working fluid with the heat released by the condensation step; expanding the heated and pressurized fluid to produce work; and Removing condensation water; A method comprising:

15. The method of claim 14, further comprising returning the high droplet load exhaust fluid to the inlet to be mixed with fresh inlet fluid and repeating the process.

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