Abstract:
A hydroelectric power installation including a pre-existing gated spillway with upstream bulkhead slots and bulkhead service crane and hydroelectric generating modules configured to fit the existing upstream bulkhead slots. Each module including a plurality of turbines, generators, and associated switchgear. The installation may include a trash rake operated on the pre-existing bulkhead service craneway. The hydroelectric installation is configured to meet all of the original navigation project design criteria including generating modules that can be raised above flood water as high as the associated radial gates and that are able to be safely lowered in front of a failed radial gate to serve as the emergency bulkhead the slots for which the modules exclusively occupy.

Description:
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&#39;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 pull due to the vertical component of flow through the turbine intake area while the module is being lowered as an emergency shut off device. 
     Yet another aspect of the invention is the heightening of the existing crane system in combination with the provision of a narrow upper section of the generating module to allow the module to be raised between closely spaced preexisting crane girders. 
     Yet another aspect of the invention is the combination of a rigid upper bulkhead section comprised of one or more tubular sections in combination with the water passageway truss structure of the prior art. Such upper tubular section is well suited to resist in bending the gravity loads of the entire module during lifting operations and provides torsional rigidity about the horizontal axis normal to flow. 
     Yet another aspect of the invention is the placement of the switchgear and controls associated with each of the turbine generator units within one or more of said tubular structures, thus reducing the number of electrical cables which must be connected to the fixed concrete structure and which must articulate or be disconnected during vertical repositioning of the modules. 
     Yet another aspect of the invention is the provision of vertical tubular generating module structural members adjacent each spillway pier which serve as access passageways, means for securing of retractable wheels, ventilation ducts, electrical power conveyance ducts, and as abutments or bulkhead piers for the integral trash gate system. Such bulkhead piers may be extended a safe distance above normal upstream pool elevation to provide safe human access to and egress from the generating modules even under transient high water conditions, while allowing the remaining top surface of the module to function as a controlled or uncontrolled weir for discharge of water. Access portals into said bulkhead piers may be located on top of said bulkhead piers or on their downstream face or both. 
     Yet another aspect of the invention is the provision of a connection point and recess in the upstream face of said vertical tubular members or piers to facilitate proper drooping of the electrical cables upon raising of a module, while avoiding interference with the crane girders between which the pier must extend when fully raised, and resulting in the cables being away from the trash passing spillway portion of the module. 
     Yet another aspect of the invention is a mounting means such as flanges in association with each of the wheel spindles configured to allow positioning and fixing of the module guide wheels from within the vertical tubular structure. This feature permits offloading in the horizontal downstream direction a generating module from a spud barge for example, followed by extension into and securing within the wheel assemblies within the upstream bulkhead slots. 
     According to a further aspect of the invention a mechanical trash raking device is configured to utilize the preexisting crane rails and bus bars. Such trash raking device may be configured to include, for the use of the operator or automatic control system, means for starting and stopping individual or grouped turbine generator sets in order to reduce local water velocity and enhance raking effectiveness, and means for raising and lowering an integral trash gate in order to flush floating debris. Such raking device may be further configured to provide information regarding individual turbine output or inlet pressure to the operator or automatic controller in order to prioritize trash raking effort. Such raking device may be further configured to provide sonar information from a rake mounted, portable or stationary sonar imaging device to the operator or automatic controller. 
     Yet another aspect of the invention is a means of transferring to the pre-existing radial gate located downstream of the generating module the impact load of an errant shipping barge against a generating module. Such load transfer capability provides assurance that an accidental barge impact event does not deform a generating module and thereby obstruct the travel of the associated radial gate which could, in turn, cause a loss of the upstream navigation pool. 
     Yet another aspect of the invention is a tubular structural support extending from the equipment hallway downward to one or more turbines providing mechanical support to said turbines. Said tubular structural support may be used to contain and protect from the surrounding water the means of electrical or mechanical transmission from the turbines. Said tubular support may also be used to support the trash screen structure upstream of the turbines. Said tubular support may be fitted with means for transmitting loads directly to the underlying spillway sill. Said support means are preferably adjustable to allow fitting of a prefabricated module to the existing spillway sill. 
     Yet another aspect of the invention is a debris blocking means below the turbine intake that protects the turbines from debris while being lowered into position but allows flow in a downward direction when the module is being used as an emergency bulkhead to shut off flow. Such means may be a trash screen or an expendable or articulated flap which would block the upward flow of debris into the module intake during lowering but would not resist flow or transmit hydraulic down pull loads to the module. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of one bay of a gated spillway within which a generating module is shown in operating position and the associated preexisting radial gate in it&#39;s raised position. This is the normal power generating configuration. 
     FIG. 2 is a perspective view of one bay of a gated spillway within which a generating module is shown in the raised position and the associated radial gate is shown in the raised position. This is the flood passing configuration. 
     FIG. 3 is a perspective view of one bay of a gated spillway within which a generating module is in the raised position and the associated preexisting radial gate is in the lowered position. This configuration depicts the turbine service position during moderate water flow. 
     FIG. 4 is a cross section view showing a generating module (including a plurality of hydromotive machine, i.e. turbine generators in the lowered operating position and the associated radial gate raised. A mechanical trash rake is shown adapted to the preexisting craneway. 
     FIG. 5 is a detailed cross section of the module depicted in FIG.  4 .(including draft tubes  4 , runner  3 , guide vanes  2  and turbine generator  1 . 
     FIG. 6 is a view facing downstream, partially cut away, of a module in the generating position. Auxiliary roller gates as well as spillway gates are depicted. 
     FIG. 7 is a top plan view, partially cut away, showing the position of a module in a bay. 
     FIG. 8 is a perspective view, partially cut away and without the trash screen assembly, of the upstream face of a module. Pre-existing crane girders  26  are shown in dotted lines for reference purposes relative to the position of the module when raised. 
     FIG. 9 is a sectional elevational view of the module shown in FIG.  8 . 
     FIG. 9A is a sectional elevational view of the module of FIG. 9 being lowered as an emergency shut-off device. 
     FIG. 10 is a sectional elevation of a module in the raised position showing the modified bulkhead service crane. 
     FIG. 11 depicts a bumper arrangement for transferring impact loads from the generating module to the radial gate. 
     FIG. 12 shows a module in the raised position in association with an emergency lifting device and the bulkhead service crane. 
     FIG. 13 shows an emergency lifting device positioned at each end of a raised module. 
     FIG. 14 is a sectional elevation view showing a raised module in association with the emergency lifting device and the bulkhead service crane. 
     FIG. 15 is an elevational view of one of the emergency lifting devices. 
     FIG. 16 is a plan view of one of the emergency lifting devices. 
     FIG. 17 is a sectional elevation view showing an emergency lifting device re-configured to pass under the bulkhead service crane. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The provision of power installations at navigation dams without the need for coffer dams, excavation or new concrete structures can reduce costs by approximately half compared to conventional construction. Installations of the type described herein are subject to rigorous operational criteria including weight limitations imposed by the existing crane and craneway, lifting elevations E above flood water elevations F and lifting reliability dictated by flood conditions, as well as a requirement that any new equipment which occupies the bulkhead slots must perform the emergency shut off function of the bulkheads originally intended for the bulkhead slots and rendered unusable by the presence of the new generating modules. 
     As of the date of this patent application no movable array or matrix type turbine installations have ever been installed at the spillway of a navigation lock and dam in the United States due to the herein described challenging design criteria which this invention addresses in detail. 
     In many locations most of the trash which cannot pass through the turbines is floating. Even conventional power plants with large (7 or 8 meter runner diameter) pit or bulb type turbines with coarse trash screens can lose electrical generation due to debris blockage. Small turbines such as those associated with matrix or array arrangements have finer screens that are even more subject to trash blockage. The spillway gates  18  integral with the generating modules  28  disclosed herein eliminate the need to rake the floating debris, which can thus be simply passed over the top of the modules. A conventional trash rake  29  in its fully retracted position is shown in FIG.  4 . In some cases the act of raking debris out of the water may result in a requirement that the plant operator remove the debris from the river then dispose of the debris at a land fill with certifications that it contains no hazardous waste, which could simply be pieces of pressure treated lumber. 
     At most installations the modules must be taken out of service and raised out of the flow path due to seasonal and storm related flow increases. This may significantly impact annual power generation and project economics. The incorporation of waste gates  17  (FIG.5) or spillway gates  18  allows the module to pass greater total flows and to remain in operation for a greater portion of each year. The average annual number of module lifting operations is also thereby reduced. Careful configuration of the waste gate  17  and it&#39;s spillway  8   b  can reduce the effective tailwater elevation and increase turbine output by recovering a portion of the energy in the waste flow. Referring to FIG. 5, efficient energy recovery requires a smooth approach  8   c  to the waste gate  17  followed by a smooth spillway surface  8   b  and terminating at a draft tube lip  8   a . The energy benefit is derived from the conservation of momentum of the combined waste and turbine flows and from the waste stream acting as an extended diffuser surface for the underlying turbine flow. The low point  8   d  of the draft tube lip  8   a  provides the further benefit of allowing the draft tube to seal against air incursion under low tailwater conditions. The tailwater elevation is designated by the letter “T.” The headwater elevation is designated by the letter “H”. An additional benefit of the waste gate approach surface  8   c  is that it forms a portion of a horizontal cable way  9  which provides support to the turbine assemblies and facilitates electrical connection of the generators  1 . 
     Referring to FIG. 5, there is shown a tubular structural support or column  10  extending from the cable duct  9  or from the equipment hallway  15  in FIG.  9 . An upstream trash screen  12  and trash screen support members  11  are shown in FIGS. 5 and 9. At the bottom of the support column  10  there may be a bearing pad  13  for transmitting loads to sill  24  which is preferably height adjustable. 
     Waste gate piers  14  provide a structural connection between draft tubes  4 , cable way  9 , and switch gear hallway  15 . A vertical columnar structure  19  is provided at each end of the module  28  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 or guide means  38 . A lifting lug or crane attachment means  20  is secured to each column  19 . A cable attachment or feed-through point  21  and associated recess  21   a  in column  19  facilitate proper drooping of electrical cables  22  when the module  28  is raised. 
     FIG. 9 also shows a seal  23  across the bottom of the module  28  extending from pier to pier so as to balance the buoyancy and down-pull forces during use of the turbine module as an emergency closure device. Preferably, the seal is configured so as to provide a distinct and stable flow separation edge. FIG. 9 also shows turbine generator sets comprising generator  1 , guide vanes  2 , and runner  3  attached to a bulkhead assembly comprising access columns  19 , lifting points  20 , horizontal tubular structures  15 ,  15   a ,  15   b  and  15   c , and draft tubes  4 . 
     FIG. 9A shows the module being lowered into position as an emergency shut-off device. Flow lines illustrate the manner in which water flows through the trash screen and beneath the module resulting in a stable flow separation edge at seal  23  without significant down-pull forces under the upstream portion of the module as is represented by the nearly full headwater pressure acting on module surfaces  28   a ,  28   b  and  28   c . Air vent  39  prevents the detrimental formation of a vacuum downstream from seal edge  23 . 
     As illustrated in FIG. 9, the preferred method of electrical connection in the case of submerged individual generators is by means of wires  30  extending through support column  10  to circuit breaker  31  connected to bus bars  33  connected through access column  19  to cables  22 . 
     FIG. 11 shows a generating module in operating position incorporating a load-transfer frame  40  designed to limit deflection of the module in case of impact by a barge, for example. One or more load-transfer devices may be spaced along the length of each module. In the event of a large object striking the module, the load-transfer device  40  operates as a bumper to transfer the force to the radial gate  25  and thereby prevent damage to the module which could prevent raising the module or moving the radial gate. 
     At some projects impact of loose uncontrolled shipping barges against the installed modules is a design consideration. A s described above in connection with FIG. 11, a bumper or load-transfer device  40  may be in corporated into the module structure in order to transfer loads to the radial gate at predetermined locations during such an event. Such a bumper could alternatively be attached to the radial gate  25 . It should be noted that the term “radial gate” is used for convenience because most of the potential structures for the herein described installation utilize mostly radial gates. Other types of preexisting gates downstream of the bulkhead slots may be utilized in an equivalent manner and the claims referring to radial gates are intended to be interpreted broadly to include other gates of equivalent function. 
     A critical aspect of module hydraulic design is the elimination of any horizontal surfaces at a low elevation near the upstream end of the module. With flow under the module , such surfaces would be subject to approximately the full differential between headwater and tailwater. Such a surface 12 feet long ×100 feet wide under 20 feet of head would be subject to a down pull of approximately 750 tons. This figure must be added to a module weight of perhaps 400 tons. The crane loads could be catastrophic under these conditions. Referring to FIG. 9A, the open bottom of the trash screen enclosure permits free flow from above toward the sealing edge  23  of the module. The bottom face of the trash screen enclosure  34  may alternatively be covered with an expendable or articulated cover or with a trash screen. 
     Referring to FIG. 9, water flow through the individual turbines may be started and stopped by means of a slide gate  29  or fixed wheel gate at the downstream end of each draft tube or vertical column of draft tubes. Each such draft tube gate is preferably operated by one or more hydraulic cylinders located inside of or along side of the gate to provide an unobstructed water and debris flow path above. Either the cylinder or the rod may be configured to move with the gate. 
     Referring to FIG. 8 the sides  49  and  50  of the access column  19  are extended downward to secure the lowermost wheel assemblies  38 , while allowing water flow to the outermost turbine situated between sides  49  and  50 . Access doors  52  are provided on the top and downstream faces of the module. 
     In FIG. 12 there is shown a module  28  in the raised position. Also shown in operating position is an emergency lifting device  51 , positioned under the bulkhead service crane  16 . In FIG. 13 there is shown an elevation view facing downstream showing the emergency lifting devices  51  in operating position with the module  28  in the fully raised position. FIG. 14 is a detailed sectional elevation view of a module  28  in the raised position. Multistrand jack  37  is mounted on jack support  40  and powered by hydraulic pump  41 . The jack support travels on rails  42 . Referring to FIG. 15, an elevation view parallel to water flow, multi strand jack  37  sits atop jack support  40 . The device  43  for winding the strands is shown along with the hydraulic pump  41  mounted to working platform  44  which may be accessed by ladder  45 . Located below the multi strand jack  37  is the connector  46  for the lifting strands  47 . The connector  46  is accessed through opening  48 . 
     Referring to FIG. 16, there is shown a top view of the emergency lifting device  51 , and the device  43  for winding the strands. 
     Referring to FIG. 17, an emergency lifting device is shown reconfigured to allow it to pass under the bulkhead service crane  16 . The multi strand jack  37  is shown adjacent to the device  43  for winding the strands  47 . The hydraulic pump  41  is shown on a separated portion of the jack support  40 . Each separated portion of the support remains on rails  42 . 
     Other variants are possible without departing from the scope of this invention.