Patent Application
20130292945
The present invention relates generally to turbine assemblies useful for harnessing hydroelectric energy. More particularly, the present invention relates to improved in-conduit turbines and hydroelectric power systems.
Hydroelectric energy refers to the generation of energy from the flow, current, or velocity of water. This type of energy is different from hydroenergy, which traditionally refers to power generated using dams (impoundment or run-of-river). Because hydroelectric energy relies on the velocity of water, these energy systems can be placed into sources of flowing water with minimal infrastructure or environmental impacts. As a result, hydroelectric power is considered cutting-edge waterpower.
To harness hydroelectric energy, turbines typically operate in rivers, oceans and tidal settings. By way of example, in rivers, turbines can be installed for applications that harness energy from such settings as in-stream, free-flow, open-river or hydroelectric run-of-river. As other examples, in ocean and tidal settings, turbines harness ocean power and tidal power, respectively.
These turbines may be loaded onto a barge, which is well equipped with cranes to facilitate the raising and lowering of individual turbines and power generating units that accompany them. In other examples, these turbines may be integrated into an in-conduit hydroelectric power generator.
Unfortunately, previous designs of hydroelectric power generators suffer from certain drawbacks. By way of example, previous designs employ a mechanism of attaching turbine blades to other components of a turbine with fasteners that results in a relatively higher amount of force being placed on the fasteners. This typically results in relatively poor load distribution throughout the blade-attachment mechanism. Further, given such limitations, prior designs are unable to use a wider variety of materials to construct certain components of a hydroelectric power generator.
What is therefore needed are designs and assembly methods for fastening blades to other components of a turbine that provide less stress on the fastening mechanism, stabilize a turbine during rotation, and allow for a wider variety of materials to be used in constructing certain components of a turbine used in a hydroelectric generators.
In view of the foregoing, in one aspect, the present invention provides novel systems and methods for increasing efficiency and power output of in-conduit hydroelectric power systems and turbines.
In one aspect the present invention discloses a turbine. The turbine includes: (1) a central longitudinal shaft configured to rotate on a central axis perpendicular to a direction of fluid flow; (2) a plurality of substantially circularly arcing blades designed to be coupled to the shaft, and each of the substantially circularly arcing blades having defined at one end one or more blade apertures; (3) a fastening sub-assembly including fasteners and the fastening sub-assembly used for coupling the substantially circularly arcing blades to the shaft; and (4) wherein, in an assembled configuration of the turbine, a sweep of the arcing blades defines a substantially spherical shape when the arcing blades rotate with the shaft, each end of the substantially circularly arcing blades extends outwardly from the shaft such that a plane defined by each of the blades is not parallel to the central axis and when the fastening sub-assembly couples the arcing blades to the shaft, the fasteners pass through one or more blade apertures. In one embodiment of the present invention, each end of the substantially circularly arcing blades extends outwardly from the shaft such that a plane defined by each of the blades is not parallel to the central axis. Preferably, the turbine includes another fastening sub-assembly, such that the fastening sub-assembly and another fastening sub-assembly are designed to be disposed at opposite ends of the shaft and couple opposite ends of the substantially circularly arcing blades to the shaft. More preferably, each of the fastening sub-assembly and another fastening sub-assembly includes a hub plate having defined therein hub apertures such that the fasteners are designed to pass through the hub apertures. Even more preferably, each of the fastening sub-assembly and another fastening sub-assembly includes an auxiliary plate having defined therein auxiliary apertures such that the fasteners are designed to pass through the auxiliary apertures.
In preferred embodiments of the present invention, in an assembled configuration of the turbine, each of opposite ends of the substantially circularly arcing blades is sandwiched between the corresponding hub plate and the corresponding auxiliary plate, and a first portion of each of the fasteners is on one side of each of the substantially circularly arcing blades, and a second portion of each of the fasteners is on the other side of each of the substantially circularly arcing blades. In an assembled configuration of the turbine, corresponding ones of the blade apertures, the hub apertures and the auxiliary apertures may align such that the fasteners fasten corresponding ones of the hub plate, the auxiliary plate and the substantially circularly arcing blades. The turbine may further include opposing shaft couplers for securely affixing each of the fastening sub-assembly and another fastening sub-assembly to the shaft.
Each of the substantially circularly arcing blades may include, along a substantial length, an airfoil cross-section. In certain embodiments, the substantially circularly arcing blades define a nominal solidity that is between about 15% and about 30%. Preferably, an angle between the plane defined by each of the substantially circularly arcing blades and the central axis of the shaft is a value between about 10 degrees and about 45 degrees. The substantially circularly arcing blades may be made from composite, plastic or metal.
In another aspect, the present invention discloses a power generating system. The power generating system includes: (1) a turbine, comprising (a) a central longitudinal shaft configured to rotate on a central axis perpendicular to a direction of fluid flow, (b) a plurality of substantially circularly arcing blades designed to be coupled with the shaft, and each of the substantially circularly arcing blades having defined at one end one or more blade apertures, (c) a fastening sub-assembly, including fasteners and the fastening subassembly used for coupling the substantially circularly arcing blades to the shaft, and (d) wherein, in an assembled configuration of the turbine, a sweep of the arcing blades defines a substantially spherical shape when the arcing blades rotate with the shaft, and when the fastening sub-assembly couples the arcing blades to the shaft, the fasteners pass through the one or more blade apertures; and (2) a generator capable of being operatively coupled to the shaft of the turbine and, during an operational state of the power generating system, the generator generates power from rotation of the turbine caused by a fluid impinging on the blades. In one embodiment of the present invention, each end of the substantially circularly arcing blades extends outwardly from the shaft such that a plane defined by each of the blades is not parallel to the central axis.
In preferred embodiments of the present invention, the power generating system further includes a turbine further comprising another fastening sub-assembly, such that the fastening sub-assembly and another fastening sub-assembly are designed to be disposed at opposite ends of the shaft and couple opposite ends of the substantially circularly arcing blades to the shaft. Each of the fastening sub-assembly and another fastening sub-assembly may include a hub plate having defined therein hub apertures such that the fasteners are designed to pass through the hub apertures. Each of the fastening sub-assembly and another fastening sub-assembly may include an auxiliary plate having defined therein auxiliary apertures such that the fasteners are designed to pass through the auxiliary apertures.
In preferred embodiments of the inventive power generating system, each of opposite ends of the substantially circularly arcing blades is sandwiched between the corresponding hub plate and the corresponding auxiliary plate, in an assembled configuration of the turbine. Furthermore, in this embodiment, a first portion of each of the fasteners is on one side of each of the substantially circularly arcing blades, and a second portion of each of the fasteners is on the other side of each of the substantially circularly arcing blades. Preferably, in an assembled configuration of the turbine, corresponding ones of the blade apertures, the hub apertures and the auxiliary apertures align such that the fasteners fasten corresponding ones of the hub plate, the auxiliary plate and the substantially circularly arcing blades.
In yet another aspect, the present invention discloses an electric power generating system. The electric power generating system includes: (1) a conduit for conveying a fluid; (2) a turbine disposed inside the conduit, comprising (a) a central longitudinal shaft configured to rotate on a central axis perpendicular to a direction of fluid flow, (b) a plurality of substantially circularly arcing blades designed to be coupled with the shaft, and each of the substantially circularly arcing blades having defined at one end one or more blade apertures, (c) a fastening sub-assembly including fasteners and the fastening subassembly used for coupling the substantially circularly arcing blades to the shaft; and (d) wherein, in an assembled configuration of the turbine, a sweep of the substantially circularly arcing blades defines a substantially spherical shape when the substantially circularly arcing blades rotate with the shaft, and when the fastening sub-assembly couples the substantially circularly arcing blades to the shaft, the fasteners pass through the one or more blade apertures; and (3) a generator capable of being operatively coupled to the shaft of the turbine and, during an operational state of the power generating system, the generator generates power from rotation of the turbine caused by a fluid impinging on the blades. In one embodiment of the present invention, each end of the substantially circularly arcing blades extends outwardly from the shaft such that a plane defined by each of the blades is not parallel to the central axis. Preferably, the diameter of a cross section of the conduit is a value that is between about 12 inches and about 144 inches.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention is practiced without limitation to some or all of these specific details. In other instances, well-known process steps have not been described in detail in order to not unnecessarily obscure the invention.
Conduit 102 is equipped with flanges 104a and 104b disposed on each end. Flanges 104a and 104b may be used to bolt upstream or downstream additional conduits, including those that are fitted with additional electric power generating systems (not shown to simplify illustration). A cross section of conduit 102 preferably has a diameter that is a value between about 12 inches and about 144 inches. A cross section of conduit 102 is preferably circular, though in alternate embodiments of the present invention, it may be of an oval shape. Conduit 102 and its components may be composed of any rigid material that does not absorb water or any other fluid used to generate energy by fluid flow.
At a bottom end, conduit 102 has defined therein an aperture 106 capable of receiving and having pass therethrough a shaft 117 of turbine assembly 116. A mounting plate 110 is attached (preferably by welding or some other conventional method known to those skilled in the art) to the outside surface of a bottom end of conduit 102. Though not shown, mounting plate 110 also has defined therein an aperture, which aligns with aperture 106. In preferred embodiments of the present invention, mounting plate 110 is disposed below a shim (not shown to simplify illustration) having an exterior planar surface and an inner cylindrical surface for mating with the external cylindrical surface of conduit 102.
A first bearing 112, capable of receiving and having pass therethrough shaft 117 of turbine assembly 116, is attached to mounting plate 110. At a bottom end, shaft 117 is preferably grooved and capped with a snap ring (not shown to simplify illustration) or the like capable of stabilizing shaft 117.
At a top end, conduit 102 has defined therein an aperture 108 below flange 114 that is large enough to allow turbine assembly 116 (described in further detail below with reference to
Generator-plate assembly 118 is disposed above conduit 102. At a bottom end, generator-plate assembly 118 includes three-vaned cylindrical spacer 126 disposed below circular attachment plate 122. Circular attachment plate 122 includes a circular plate 132 attached at a bottom end, preferably by bolting, to an annular seal 128. Using the same attachment mechanism, circular attachment plate 122 attaches to circular flange 114. In this configuration, a top end of three-vaned cylindrical spacer 126 is connected to a bottom end of circular plate 132, preferably by bolting, and a bottom end of three-vaned cylindrical spacer 126 is connected to circular attachment plate 122, preferably by welding, holding cover plate 124 in place atop turbine assembly 116 during operation of the inventive electrical power generating systems. Alternate embodiments of the present invention include a spacer with any plurality of shapes or number of vanes capable of coupling circular attachment plate 122 to conduit 102 and holding cover plate 124 in place.
At a top end, circular plate 132 has defined therein a circular plate aperture 134 capable of receiving and having pass therethrough a top end of shaft 117 of turbine assembly 116. Disposed above circular plate aperture 134 is a second mounting block 136, having defined therein an aperture capable of receiving and having pass therethrough a top end of shaft 117 of turbine assembly 116 for smooth rotation of the shaft.
The components of circular attachment plate 122 are preferably made from any rigid material known to those skilled in the art, except annular seal 128 is preferably made from a compressible material, such as an elastomer (e.g., rubber), capable of sealing the attachment between circular plate 132 and flange 114. In certain embodiments of the present invention, circular plate 132 is of a relatively flat configuration, as shown in
At a top end of circular attachment plate 122, a second bearing 138, capable of attaching to and having pass therethrough an upper end of shaft 117, attaches to second mounting block 136. Thus, when electric power generating system 100 is in an assembled state, a lower end of shaft 117 passes through a first bearing 112, and an upper end of shaft 116 passes through a second bearing 138. In preferred embodiments of the present invention, first and second bearings 112 and 138 include spherical roller bearings producing only rolling friction for smooth rotation of shaft 117 during rotation of turbine assembly 116. In alternate embodiments of the present invention, first and second bearings 112 and 138 use sleeve bearings or other sliding friction arrangements, facilitating rotation of the inventive turbine assembly 116 during operation. The present invention recognizes that bearings 112 and 138 enable electric power generating system 100 to operate safely, reliably and durably to produce electricity with a fluid flow rate through conduit 102 of as little as between about 3 feet/second (“fps”) and about 4 fps.
Generator sub-assembly 120 is disposed above circular attachment plate 122. Generator sub-assembly 120 includes an annular spacer 140, a shaft-coupling device 144, an annular rim 142 attached to a first mechanical lift tab 146a, and a generator 148 attached to a second mechanical lift tab 146b. At a bottom end of generator 148 is an upper shaft 149 capable of being connected to shaft-coupling device 144.
Annular rim 142 includes a series of fasteners, preferably bolts or the like, that extend downward around an outer periphery. These fasteners are received by corresponding apertures, defined on a top end of annular spacer 140. Similarly, annular spacer 140 includes at a bottom end a series of fasteners, preferably bolts or the like, that extend downward around an outer periphery. These fasteners are received by corresponding apertures of circular plate 132, thus coupling generator sub-assembly 120 to the other components of the inventive electric power generating systems.
Housed within annular spacer 140 is shaft-coupling device 144, capable of coupling generator 148 to turbine assembly 116. Shaft-coupling device 144 attaches at a bottom end to a top end of shaft 117, and at a top end to a bottom end of generator shaft 149. Generator shaft 149 is coupled to a bottom end of generator 148. When an inventive electric power generating system is in operation, shaft-coupling device 144 transfers torque from rotation of turbine 116 to generator 148. Generator 148 is any generator capable of converting mechanical energy received from operation of turbine assembly 116 to electrical energy. Generator 148 may produce direct or alternating current and single-phase or 3-phase, synchronized 120 VAC or 240 VAC, or the like, and/or may be converted from one to the other, depending upon the power grid requirements.
A first mechanical lift tab 146a is attached to annular rim 142, and a second mechanical lift tab 146b is attached to generator 148. Those skilled in the art will recognize that when the inventive electric power generating system 100 is in an assembled state (shown below in
Blades 250 are of a substantially circularly arcing configuration. In preferred embodiments of the present invention, when the inventive turbine assembly is in operation, blades 250 preferably sweep a spherical area. In alternate embodiments, blades 250 sweep a non-spherical, or somewhat oval, area (e.g., a blade-swept area that is taller than it is wide, or is wider than it is tall) when the inventive turbine assembly is in operation. Preferably, blades 250 are of a constant radius, though in alternate embodiments of the present invention, blades 250 are of a variable radius.
Blades 250 include a blade end 252 with one more blade apertures, each capable of receiving a fastener 258 therethrough. In certain embodiments of the present invention, blade end 252 is fabricated as part of each blade 250. In alternate embodiments, blade end 252 is fabricated separately and attached to each blade 250 by any method known to those skilled in the art. In such embodiments, blade end 252 may be composed of a different material or materials than blade 250.
When inventive turbine assembly 216 is in an assembled state, blades 250 are spaced, preferably evenly, around a shaft. In preferred embodiments of the present invention, the angle between the plane defined by each of blades 250 and the central axis of a shaft is a value that is between about 5 degrees and about 45 degrees, more preferably a value that is between about 10 degrees and about 30 degrees. In certain embodiments of the present invention, blades 250 extend such that a plane defined by them is not parallel to a shaft.
Preferably, each end of blades 250 extends outwardly from a shaft. According to preferred embodiments of the present invention, sufficient clearance around the blade-swept area of blades 250 is provided to avoid undue compression of fluid at turbine-sweep boundaries.
In preferred embodiments of the present invention, blades 250 are characterized along a substantial length by an airfoil cross-section. In certain of these preferred embodiments of the present invention, the airfoil cross-section conforms to the recognized NACA 20 standard, which is well known to those skilled in the art. Regardless of the airfoil cross-section shape, the airfoil cross-sections are selected to provide the inventive turbines with improved hydrodynamics and efficiency for generating power.
While
It is noteworthy that the present invention contemplates turbine shapes that are slightly or somewhat oval in cross-section. In such embodiments, the inventive turbine assemblies used in an electric power generating system may employ a conduit that has a correspondingly oval cross-section.
Fastening sub-assembly 232 (described below in more detail) attaches blades 250 via blade ends 252 to hub plate 254. Hub plate 254 is preferably of a relatively flat configuration and includes a receiving portion 262 for attachment of each of blade ends 252. As shown in
Hub plate 254 also has defined at or near its center an aperture capable of receiving and having pass therethrough a shaft (e.g., shaft 117 of
As shown in
Associated fasteners 258 and immobilizers 260 are designed to facilitate attachment of blades 250 to hub plate 254. In this embodiment, fasteners pass through corresponding apertures of blade end 252, hub plate 254 and auxiliary plate 256. Although preferred embodiments of the present invention contemplate use of auxiliary plate 256 to stabilize attachment of blades 250, alternate embodiments of the present invention do not contemplate use of auxiliary plate 256.
The fastening sub-assembly configuration employed by the present invention realizes certain advantages over previous designs. For example, previous designs utilize fasteners that attach to blades in an orientation perpendicular to a turbine's axis of rotation, typically by fastening into an end edge of a blade without passing through the blade. By contrast, the present invention employs a mechanism whereby a fastener will pass through a blade in a configuration that is relatively parallel to a turbine's axis of rotation. As a result, the present invention provides significantly lower blade to hub plate stresses, such that less force is directly applied to the fasteners. These fasteners serve indirectly to create substantial friction between blade ends 252 and hub plate 254, such that loads are directly transferred from blade ends 252 to hub plate 254. In other words, the present invention realizes an increase in shear loads and a decrease in tension loads when compared to previous designs, resulting in better load distribution throughout the blade attachment sub-assembly. Not only does this provide a design that stabilizes the inventive turbine assembly during rotation, it also allows for a greater versatility in blade materials. In particular, certain desired composite materials (e.g., a fiberglass composite or a carbon fiber composite), which could not be used to manufacture previous turbine assembly designs, represent preferred embodiments when manufacturing inventive turbine assemblies.
Generator-cap assembly 318 is disposed above turbine assembly 316 and conduit 302. Specifically, a flat surface is formed by a cover plate 322, which is coupled to flange 314 of conduit 302. At the end of shaft 317, a bearing 338 is attached, which is disposed beneath a generator 348. Generator 348 mounts to and rotates with the distal end of shaft 317. As shown in
Two or more inventive electric power generating systems may be installed at defined intervals (in series) within and along a water-conveying conduit for increased power generation. To this end, flange 304 may be used to couple to upstream or downstream conduits including additional electric power generating systems (not shown to simplify illustration). Likewise, those skilled in the art will recognize parallel arrangements of two or more hydro-electric power generation systems may be installed within branches of a water-conveying conduit for increasing power generation.
Although illustrative embodiments of this invention have been shown and described, other modifications, changes and substitutions are intended. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure, as set forth in the following claims.
