Prime-mover dynamo plants – Fluid-current motors
Reexamination Certificate
1999-08-13
2001-08-28
Waks, Joseph (Department: 2834)
Prime-mover dynamo plants
Fluid-current motors
C290S043000, C405S078000
Reexamination Certificate
active
06281597
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to hydroelectric generating apparatus and the method of installing the same. More specifically this invention relates to the retrofitting of hydroelectric generating apparatus to pre-existing gated spillways typically found at navigation locks and dams such as those on the Ohio River, USA.
DESCRIPTION OF RELATED ART
Hydroelectric power installations utilizing turbine generator sets that are lowered into or raised from their operating position are known. For example, U.S. Pat. Nos. 4,143,990 and 4,207,015 to F. J. Atencio disclose different versions of movable hydroelectric generator sets. U.S. Pat. No. 4,289,971 to Ueda discloses a turbine generator unit that may be raised or lowered for attachment to a fixed draft tube. U.S. Pat. No. 4,319,142 to Mayo discloses a hydraulic turbine installation which is movable between an operating position and a raised flood passing position, but which cannot, due to it's length, be raised high enough to clear debris during a flood event. Furthermore, due to its very heavy weight, it could not be raised with the crane which pre-exists at many of the potential projects.
U.S. Pat. No. 4,755,690 to Obermeyer discloses a hydroelectric generating module which can be raised or lowered in front of a pre-existing outlet gate on a dam.
U.S. Pat. No. 4,804,855 to Obermeyer discloses a matrix of hydromotive machines which may be hydraulic turbine generator sets. A shortcoming of these designs is that they fail to disclose any means of reducing the number of cables connected to the modules.
U.S. Pat. No. 5,825,094 to Hess discloses a hydroelectric generating module which could theoretically be raised or lowered into a bulkhead slot. A shortcoming of this design is that lowering or raising of the module under flow conditions, as may be required in an emergency, would require lifting forces beyond the capacity of the pre-existing crane system. The down pull is due to the bottom horizontal and near horizontal surfaces of the water inlet tubes, which are subject to full head pressure on their upper surfaces and are subject to a much lower pressure on their lower surfaces due to the high velocity of the water passing under the unit with the module partially raised. The flap valves for controlling the flow through the turbines would interfere with the pre-existing radial gate normally located a very short distance downstream from the pre existing stop log slot. This interference, which could occur in both the partially raised position as well as the lowered operating position, would require that the module be installed too far upstream to utilize the existing bulkhead service crane. Further disadvantages of this design are the small trash rack area that would result in low overall efficiency and the lack of trash handling means that would result in frequent plant outages due to floating debris. Yet a further disadvantage of this design is extra weight of the totally superfluous water passageways upstream of the turbine distributors, a feature which reduces hydraulic efficiency by preventing any reduction in the already high trash rack velocities when some of the units are shut down. Yet a further disadvantage of this design is that the bottom horizontal member of the water passageway extends so far upstream that if the module were used as an emergency closure device, the resulting hydraulic down pull could damage or destroy the crane system. Yet a further disadvantage of this design is the lack of integrity of the draft tube assembly which would be subject to damage by vibration, ice and debris while contributing nothing to the strength of the structure as a whole.
PCT International publication number WO 98/11343 to Winkler discloses an array of turbine generator sets which may be lifted independently of the draft tubes. Such an arrangement is not applicable to the large US navigation locks and dams which require that all equipment including draft tubes be raised to pass high flows.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a hydroelectric generating module comprised of the following components; One or more turbine generator sets, a plurality of water passageways comprising a lower portion of the bulkhead, and an upper water retaining structural portion of the bulkhead. The module is installed by increasing the height of the existing crane, and providing on the crane rails of said pre-existing crane a trash rake which may be used to clear debris from the screens in front of the turbine generators as well as used as a control location to start and stop individual turbine generating sets and operate a trash gate mounted along the top edge of the module.
According to another aspect of the invention, the discharge of each vertical column of generators is controlled by a slide gate at the draft tube exit. Such draft tube gates are preferably operated by hydraulic cylinder within said gates thus leaving the space above the gates unobstructed for passage of trash.
According to another aspect of the invention, the upper portion of the module provides an accessible enclosure for electrical equipment while being short enough in the upstream/downstream direction to be raised up between the pre-existing crane way bridge girders to pass debris during maximum flood flows, while the lower portion of the module extends from near the radial gate at the downstream end as far upstream as center of gravity constraints permit, resulting in an economic runner size and excellent hydraulic efficiency. Said upper portion serves as an integral structural component of the module and contributes significantly to the strength of the module as a whole, especially during lifting.
According to a further aspect of the invention a vertical columnar structure is provided at each end of the module to provide access to the module from each end, to provide a lifting point, and to provide access and mounting means for retractable bulkhead slot wheels.
Yet another aspect of the invention is a means for discharging water in excess of turbine capacity in such a manner as to augment energy production. Such means may be a spillway gate at the top of the module or a roller gate, for example, discharging from an intermediate elevation, or a combination of both.
Yet another aspect of the invention is the provision of a lip or jump above the draft tube exits configured to direct excess flows over the draft tubes in a nearly horizontal or preferably slightly upward direction, thus causing a reduction in effective tailwater elevation and an increase in net head across the turbines.
Yet another aspect of the invention is an auxiliary lifting means which can be used to lift the module out of the spillway flow path if the main pre-existing crane is out of service. The auxiliary lifting means is so configured that it can be used to lift a module on either side of or underneath the pre-existing main lifting crane. Such lifting means may be hydraulic strand jacks, for example, mounted on a cart that can be lifted over the module lifting emergency bulkhead crane by the associated auxiliary crane or that can pass through or around the module lifting emergency bulkhead crane.
Yet another aspect of the invention is the location of a seal and flow separation edge across the bottom of the module from pier to pier so as to provide neither excess buoyancy nor excess down pull during use of the turbine module as an emergency closure device. Such a seal may be used in conjunction with an air vent downstream of said seal to prevent the formation of a vacuum and unstable flow conditions under the portion of the module downstream of the seal.
Yet another aspect of the invention is the inclination of the turbine generator units in the downstream direction. Said inclination creates a more uniform velocity distribution through the turbine resulting in improved efficiency and compensating for the lower plant cavitation coefficient associated with the slightly higher turbine setting. Said inclination also reduces the hydraulic down
Dum Thomas
Obermeyer Henry K.
Sambs Wolfgang
Syndicated Technologies, LLC.
Waks Joseph
LandOfFree
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