The Waterpower XVI conference and exhibition convenes in Spokane, Wash., this July. This event features multiple opportunities to learn about new technologies, approaches, and services being used to improve hydro. Here is a sampling of the information that awaits attendees.
The Waterpower XVI conference and exhibition is July 27-30, 2009, in Spokane, Wash. The theme is “New Roles for Hydro in a Changing World.” The focus of the conference’s program and exhibition is new technologies and innovations.
The biennial Waterpower conference is regarded as the hydro industry’s premier technical forum. Technical paper presentations, the traditional backbone of the conference, are supplemented by “mini-conference” symposia, roundtable discussions, and special-interest briefings sessions. Delegates may earn 15 hours of professional development credits.
In addition to the conference program, several meetings, workshops, technical plant tours, and the Hydro Training Institute’s “Hydro Basics” course coincide with Waterpower XVI.
The Waterpwower exhibit hall opens the evening of July 28. More than 250 companies will share their technology and service innovations during the three-day conference.
This article features application of 11 of the many products, services, techniques, and methods that will be on display in the exhibit hall:
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— Synthetic lubricant;
— Laser tracking to measure scroll case;
— Floating fish barrier;
— Overhead stoplog lifting device;
— Rotor pole temperature sensor;
— Fish bypass tower;
— Self-lubricating bearings;
— Oil spill containment system;
— Coating of hollow jet valves;
— Hydrologic forecasting technology; and
— Turbine shaft sealing system.
For more detailed information about all conference events and registration, visit www.waterpowerconference.com.
AEP uses synthetic lubricant at six hydro plants
American Electric Power (AEP) has replaced the oil-based lubricants in equipment at six of its 17 hydro plants with UCON Trident AW hydraulic fluid, says Terry A. Benson, maintenance supervisor for the northern hydro generation division of AEP. This lubricant, manufactured by the Dow Chemical Company and supplied by American Chemical Technologies Inc., is water-soluble, fire-resistant, and heavier than water.
American Chemical Technologies is exhibiting at the Waterpower conference.
AEP is committed to being an environmetally friendly company, Benson says. This commitment drove AEP to choose six plants at which to make the conversion from petroleum-based lubricants to the UCON Trident AW hydraulic fluid. The plants are 4-MW Elkhart in Indiana, 1-MW Mottville in Michigan, 48-MW Racine in Ohio, 22.5-MW Reusens in Virginia, 5-MW Twin Branch in Indiana, and 19-MW Winfield in West Virginia.
The utility’s use of this lubricant varies by plant: Elkhart, trashrake equipment and wicket gate actuator tanks for all three units; Mottville, wicket gate actuator tank for one unit, with the other units scheduled to be converted in the summer of 2009; Racine, ejector container of the trashraking system, with plans to convert the trashrake in the spring of 2009, as well as the tail gate screwjack system gear boxes for one unit, with the other unit scheduled to be converted later this year; Reusens and Winfield, the knuckle-boom crane; and Twin Branch, the trashrake equipment.
UCON Trident AW is a fully synthetic polyalkylene glycol (PAG) lubricant, American Chemical Technologies says. The UCON Trident AW formulation does not contain any chemicals on the Comprehensive Environmental Response, Compensation, and Liability Act (or CERLCA, also known as Superfund) list of hazardous substances. As such, leaks require minimal reporting.
According to the U.S. Fish and Wildlife Service, UCON Trident AW meets requirements as “relatively harmless” or “practically non-toxic” to fish and other aquatic wildlife.
Since the equipment was converted at the six plants mentioned above, AEP has seen no significant change in how the equipment operates. The only exception is the more northern plants (Indiana and Michigan), where equipment operation upon initial start up is slightly sluggish and slow during cold months of the year, Benson says. However, once the fluid warms up, the equipment operates with no noticeable sluggishness, he says.
One drawback to the use of this hydraulic fluid is that it is more expensive than the biodegradable oil AEP uses and nearly twice as expensive as typical hydraulic oil, Benson says. Another added cost for AEP is the company’s requirement to add dessicant breathers for the applications in wicket gate actuator tanks. This equipment is designed to remove condensation formed during temperature changes, Benson says. AEP must perform regular sampling of the lubricant and change the dessicant as needed, which is an added cost, he says.
Laser tracker used to map scroll cases at Bear Swamp
To prepare for replacement of the two pump-turbine runners at Brookfield Renewable Power’s 600-MW Bear Swamp pumped-storage project, a contractor used the FARO Laser Tracker to map the turbine scroll cases. Use of this technology provided a computerized representation of the existing system, which was needed to ensure proper development of the new equipment.
FARO Technologies Inc. is exhibiting at the Waterpower conference.
In August 2008, Brookfield announced that the Federal Energy Regulatory Commission (FERC) approved its license amendment to increase the installed capacity at Bear Swamp, on the Deerfield River in Massachusetts, by 66 MW. The FERC order requires that refurbishment of the generator units begin within two years of the order date and be completed within five years of that date.
To achieve this capacity increase, Brookfield plans to replace the runners in the two modified Francis reversible pump-turbines, manufactured by Hitachi, and to overhaul the generators.
In order to begin work on this upgrade, Brookfield needed accurate measurements of the existing system. The upgraded units will be designed and manufactured using computational fluid dynamics (CFD) technology. For Bear Swamp, the only details available about the scroll case and vanes were contained in paper drawings dating to 1974. Accurate measurements of these structures are vital so that the company chosen to manufacture the new equipment can design both the computer and physical models using model domains that are broader than those traditionally used, says Patrick Scott Moriarty, manager of pumped-storage operations at Bear Swamp.
To gather these measurements, Brookfield contracted with East Coast Metrology in Topsfield, Mass., which used the FARO Laser Tracker.
The FARO Laser Tracker is a portable three-dimensional measurement system, which uses laser technology to measure large parts, tooling, and machinery. The system has a 230-foot-diameter range and accuracy of 0.001 inch, says Debbie L. Thompson, product marketing manager for FARO.
Workers with East Coast Metrology used the FARO Laser Tracker to establish an XYZ coordinate system inside the scroll case and to precisely locate each of the vanes relative to the center of the pump-turbines. Scans of the Bear Swamp equipment resulted in a three-dimensional point cloud measurement, Moriarty says. A point cloud is a collection of data points that do not conform to traditional geometric shapes such as circles or cylinders.
East Coast Metrology needed only one day on site per unit to perform the measurements, Thompson says. This work was conducted during a routine maintenance outage at the plant.
Perhaps more important than the short amount of time required is the accuracy of the measurements, Moriarty says. Although Brookfield considered physical measurements, “We opted against it because of possible inaccuracies due to the human element and the added work to convert the physical measurements into an electronic format,” he says.
Once the measurements were complete, workers constructed surface computer-aided design (CAD) models, which give Brookfield a three-dimensional “as-built” record of the vanes and scroll case.
Floating barrier improves salmon passage rate
With only 35 percent of migrating chinook salmon using the surface corner collector at the 558-MW Bonneville Second Powerhouse on the Columbia River in Washington, the U.S. Army Corps of Engineers needed a way to guide more of these fish to the passage route. The solution: a 720-foot-long, 10-foot-deep floating “wall” across the forebay of the powerhouse. This barrier was designed and manufactured by Worthington Products.
Worthington, headquartered in Canton, Ohio, is exhibiting at the Waterpower conference.
At the 518.6-MW Bonneville First Powerhouse and the Bonneville Second Powerhouse, steelhead and chinook migrating downstream can pass the projects via a surface corner collector. The collector removes 5,000 cubic feet per second of water from the surface. Fish swimming with this flow enter this corner collector and then swim through the 1,800-foot-long concrete channel of the sluiceway to continue their journey downstream.
“We studied the fish and found that about 75 percent of juvenile steelhead used the corner collector, but only about 35 percent of the chinook did,” says Dennis E. Schwartz, chief of operation at Bonneville. Fish that do not use the corner collector must pass via the spillway, juvenile bypass systems, or one of the two powerhouses.
The species of fish in the Columbia and Snake rivers has an effect on usage of the corner collector, Schwartz says. Steelhead and yearling chinook smolt swim in the top third of the water column and thus prefer this surface route. But fall chinook swim deeper, meaning they are not as easily attracted to the surface corner collector.
The Corps needed a way to improve the number of fall chinook using the corner collector. However, the Corps did not have funds available for a major construction project. Instead, personnel looked for an off-the-shelf fish guidance system. One potential option was a floating “wall” that could intercept fish and guide them to the corner collector, away from the powerhouse.
To test this theory, the Corps proposed a $2 million to $3 million prototype study. This study was funded by the Columbia River Fish Mitigation Program appropriated for the Portland and Walla Walla districts.
The Corps chose Worthington Products to design a prototype, which would consist of floatation devices supporting an underwater screen system. For this application, Worthington personnel created a 720-foot-long system that would be positioned in the forebay using cable and concrete anchors. The system is based on Worthington’s BoatBuster-20 floating barrier.
The structure serves as a floating guide wall. A series of 22-foot-long floating units supports a screen made of ½-inch solid plate steel that hangs 10 feet below the water line, at an angle to the current.
Personnel from Advanced American Diving Service Inc. in Portland, Ore., helped Worthington develop and implement the anchoring plan for the floating guide wall. Divers used a global positioning system (GPS) to guide installation of 80 anchor pads and the corresponding 30,000-pound anchors. The structure also includes a boat boom with a cable float and cable to keep watercraft away from the dam.
Installation took place between December 2007 and March 2008, when flows are lower than other times of year.
After a full year of experience, Schwartz says, “We’ve seen a 6 to 10 percent increase in chinook. That’s a significant difference. It translates into millions more fish.”
Electric overhead device lifts stoplogs at Ivanhoe Lake Dam
The Ontario Ministry of Natural Resources (OMNR) uses an electric overhead stoplog lifting device (called a log lifter) developed by Hatch Energy to manipulate stoplogs at Ivanhoe Lake Dam.
Hatch Energy will be in the Waterpower exhibit hall to share details about its electric log lifter.
Ivanhoe Lake Dam, on the Ivanhoe River in northern Ontario, Canada, is a concrete dam built in 1962. The purpose of Ivanhoe Lake Dam is to regulate water levels on Ivanhoe Lake for recreational uses and to prevent flooding of the downstream community of Foleyet.
Ivanhoe Lake Dam is a 10-meter-high reinforced concrete gravity structure with a raised sill and seven 4.27-meter-wide spillway bays that are controlled by stoplogs. Each of the seven spillway bays contains a maximum of six 0.3-meter-deep wood stoplogs and two 0.6-meter-deep steel stoplogs. Installation and removal of these stoplogs occurs frequently during the operating season (from March through November) to provide seasonal control of the water level in Ivanhoe Lake, says Pat Cantin, engineering technologist with the Northeast Regional Engineering Unit of OMNR.
In 1999, OMNR installed a single monorail overhead gantry system equipped with two manual 2-ton hoists. This system was used to maneuver the stoplogs during regular operations as well as during a flood event. However, configuration of the dam presented an obstacle to the use of this system. The dam deck is 2 meters above the first of the eight stoplogs in each spillway bay. During high flow events, this large distance between the dam deck and stoplogs made it difficult and dangerous for personnel to remove and install the stoplogs.
Hatch and OMNR developed the new log lifter in 2006. This machine consists of an electric overhead crane with a lifting beam (called a follower) that is lowered through the stoplog guides and into the flowing water to both remove and install the stoplogs. This follower is equipped with hooks. With most log lifters, these hooks must be manually actuated to remove or install the stoplogs. Then, once a stoplog has been removed from the guides, it must be moved to the storage location on the deck of the dam.
Because of the fast-moving water flowing over the top of the stoplogs at Ivanhoe Lake Dam, one of the greatest risks involved in removing the stoplogs is detecting proper engagement of the follower hooks, Cantin says. The stoplog lifting device features proximity sensors that allow the operator to detect engagement of the follower hooks with the stoplogs. In addition, the device contains independently actuated hooks, to give the operator separate information on each end of the follower.
John Gaffney Construction Company Ltd. fabricated, constructed, and installed the system in 2007. Since that time, the stoplog lifting machine has operated as intended.
Temperature sensors used to measure rotor pole heating
At the 846-MW Rocky Mountain pumped-storage project in Georgia, owners Oglethorpe Power Corporation and Georgia Power have three TWR-100 ThermaWatch Rotor sensors from VibroSystM installed on Unit 3. These sensors are used to detect overheating of the rotor poles.
VibroSystM is exhibiting at the Waterpower conference and can provide details about the technology.
The Rocky Mountain plant began operating in 1995 with three turbine-generating units. In 2006, plant personnel were upgrading Unit 3. This work included a turbine upgrade, and one goal was to increase power from the generator. However, plant personnel were concerned about possible overheating of the rotor poles under the new operating conditions, says Tim Watson, predictive maintenance specialist with Oglethorpe Power.
To monitor this heating and to ensure the existing windings could provide the increased power, a VibroSystM technician installed three TWR-100 sensors in the unit. The sensors were installed at the top, middle, and bottom of the 10-foot-high rotor. It took about one day to install the non-contact temperature probes in the cooling holes in Unit 3, Watson says. The sensors were then connected to the existing air-gap monitoring system at the plant.
The ThermaWatch sensor and the associated signal conditioner provide an on-line temperature reading from both salient and non-salient field poles of large rotating machines. The infrared line-of-sight sensor can measure temperatures from 0 to 200 degrees Celsius. The output from this sensor can be fed into VibroSystM’s ZOOM (Zero Outage On-Line Monitoring) system or any other instrumentation, such as the generator control system, Watson says.
Plant personnel restarted the upgraded unit in early 2007 and began monitoring rotor pole temperature using the three ThermaWatch sensors. Personnel programmed the system to take one measurement per minute during the start-up testing. These measurements indicated acceptable temperatures in the rotor poles, with an average of about 45 degrees Celsius, Watson says.
Once start up of the unit was complete, personnel reprogrammed the system. Now, the ThermaWatch system in Unit 3 constantly monitors rotor pole temperature to ensure it does not reach the alarm setpoint of 100 degrees Celsius. These values also are recorded every hour during normal operation, to provide trends of temperature readings for the upgraded unit.
Oglethorpe Power Corporation and Georgia Power are upgrading the ZOOM system at Rocky Mountain. As part of this upgrade, the utilities plan to install ThermaWatch sensors on the other two turbine-generating units at the plant.
Fish bypass tower to operate at Pelton Round Butte project
In late 2009, Portland General Electric (PGE) will begin operating a new fish bypass/intake structure at its 465-MW Pelton Round Butte Project. This $108 million structure will decrease temperatures in the Lower Deschutes River in Oregon in the summer and restore downstream passage of chinook, steelhead, and sockeye smolts, says Steven Corson, PGE spokesperson.
Barnard Construction of Bozeman, Mt., was the general contractor for construction of the structure, called the selective water withdrawal (SWW) system. Barnard is exhibiting at the Waterpower conference.
The Pelton Round Butte project is jointly owned and operated by PGE and the Confederated Tribes of the Warm Springs Reservation. The project includes three developments, from upstream to downstream: 338-MW Round Butte, 108-MW Pelton, and 19-MW Reregulating Dam. PGE is majority owner and operator of the Round Butte and Pelton dams. The Tribes wholly own the Reregulating Dam.
Round Butte Dam was completed in 1964 and impounds Lake Billy Chinook. Fish passage facilities at the dam consisted of a downstream surface collector, fish ladder, and transport hopper system. These facilities were intended to provide passage (both upstream and downstream) for chinook, steelhead, and sockeye. However, Corson says there were confounding surface currents in the forebay to Round Butte Dam that made it impossible for fish to find the juvenile bypass system.
As a result, in 1966 PGE abandoned use of the juvenile and adult fish passage facilities. To mitigate the effects of a lack of fish passage at the project, in 1968 PGE began funding a hatchery program administered by the Oregon Department of Fish and Wildlife. Under this program, the Round Butte Fish Hatchery was constructed at the base of Round Butte Dam.
Then, in the mid-1990s, PGE commissioned development of computer models of the lake, as well as river temperature and hydraulics. These models were needed to aid in the design of a system that would both meet downstream temperature requirements and provide for fish passage. PGE studied several design concepts for the SWW system.
In June 2005, as part of the process of renewing the Federal Energy Regulatory Commission license for the Pelton Round Butte Project, PGE agreed to spend US$130 million (in 2003 dollars) for fish-related projects over the course of the new 50-year operating period.
There are two goals with regard to operation of the SWW system, Corson says. The first is to provide surface currents within the forebay of Round Butte Dam that will help attract migrating summer steelhead, spring chinook, and kokanee/sockeye smolts. The second is to return the temperature of water in the Deschutes River downstream to pre-dam conditions by allowing withdrawal of water from various levels in the reservoir.
The SWW system is a 273-foot-tall tower with three sections.
The first section is a selective water bottom structure that is submerged to 270 feet deep and anchored directly in front of the existing powerhouse intake, 700 feet upstream from the dam. This section weighs 612 tons and is anchored to the lake bottom. The second section is a 40-foot-diameter vertical steel conduit that connects the bottom section with the top section. The third section is a 1,316-ton selective water top structure that separately sends water to the powerhouse and collects fish.
The water selection feature allows operators to draw cooler water from the bottom of the lake to mix with warmer water as needed to modify temperatures downstream and mimic natural pre-dam conditions. In addition, dam operators can draw warm surface water to keep the reservoir cooler in summer and fall.
Fish captured at the intake structure are sorted by size, pumped from the facility, and piped to a floating fish handling facility. This fish handling facility is located about 150 feet from the top structure, near the west shore of the lake. Trucks then take the fish past all three dams to continue their journey to the ocean.
CH2M Hill of Bellevue, Wash.; EES Consulting of Kirkland, Wash.; and ENSR/AECOM Technology Corp. of Redmond, Wash., designed the tower in collaboration with PGE Engineering. Thompson Metal Fabricators of Vancouver, Wash., fabricated the structure.
Installation of the new SWW system began in the fall of 2007. Barnard Construction served as general contractor and provided all on-shore construction work. Dix Corporation of Spokane, Wash., provided expertise in marine construction and deployment. Associated Underwater Services of Spokane, Wash., provided divers for underwater assembly.
AECOM, Associated Underwater Services, Barnard Construction, CH2M Hill, Dix Corporation, and Thompson Metal Fabricators also are exhibiting at the Waterpower conference.
All three major pieces of the structure were assembled on construction barges in the forebay and are being set in place, Corson says. This work is expected to be complete in late 2009.
The standard for safe downstream passage at the new fish facilities will be 93 percent for the first three to five years, then increase to 96 percent during the remaining license period.
Self-lubricating bearings installed on tainter gate
An inspection performed in the summer of 2008 revealed damage to three spillway tainter gates at the 40-MW Foster Dam, likely caused by high frictional losses in the bronze trunnion bushings of the gates. To reduce the chances of a recurrence, the U.S. Army Corps of Engineers is replacing these bushings with self-lubricating bushings manufactured by Columbia Industrial Products (CIP). CIP will be in the Waterpower exhibit hall.
Foster Dam is on the South Santiam River in Oregon. The embankment-type earthfill dam, built in the mid-1960s, features four 80-ton spillway gates that are about 45 feet wide by 46 feet high. The dam impounds water for a 40-MW hydro project and provides flood control on the river.
During a routine inspection of the gates at the dam in 2008, Corps personnel noticed deformation of the beams that served as the strut arms on three of the four gates. “These deformations appeared to be the result of higher-than-designed frictional losses in the gates’ trunnion bushings due to age,” says Ronald S. Wridge, chief, mechanical design section for the Corps’ Portland District.
Each spillway gate’s two trunnions serve as a pivot point that the gate rotates about when opened. The observed gate damage and a subsequent forensic analysis of the gate design indicated that all three of the damaged gates presented an unacceptable risk of structural failure if they were to operate with the reservoir at full pool, Wridge says.
The Corps determined that two steps needed to be taken to repair the damage and prevent a future recurrence. The first step was to replace the top strut arms of the gates with heavier beams. The second step was to replace the original greased bronze bushings and bronze, graphite-plugged thrust washers with self-lubricating bushings and thrust washers.
“We had three reasons for choosing self-lubricating materials,” says Wridge. “First, trunnion friction will be reduced by upwards of 50 percent. Second, they eliminate or significantly reduce maintenance requirements for the trunnion. And third, this eliminates the environmental issues associated with using grease near a waterway.”
In October 2008, CIP was part of a package of subcontracts awarded for the tainter gate repair work at Foster Dam. CIP was chosen to manufacture the self-lubricating bushings and thrust washers.
CIP manufactures a laminated composite material called CIP Hydro. This material is a medium-weave polytetrafluoroethylene and polyester fabric blend. The resin is polyester, and solid lubricants are added to reduce friction, extend wear life, and improve wet and dry performance.
Because of budget constraints, this first contract applied to only one gate at Foster Dam. Work to repair this gate required that the reservoir be lowered from November 2008 though January 2009, to a level where power generation was impossible. Rehabilitation of this first gate was completed in January 2009, and the gate has returned to unrestricted operation.
The Corps anticipates awarding another contract to rehabilitate the remaining three gates in 2009. The Corps is rehabilitating the fourth, undamaged gate as a precaution against the potential for future deformations.
Oil spill containment structure installed at Peterson plant
When replacing the main generator step-up transformer at its 6-MW Peterson plant, Central Vermont Public Service Corporation included an oil containment system that features a Petro-Pipe manufactured by Solidification Products International (SPI) of Northford, Conn.
SPI will be exhibiting at the Waterpower conference.
This plant, on the Lamoille River in Vermont, began operating in 1948. Because of the age of the existing generator step-up transformer and a recent power uprating of the generator, Central Vermont Public Service needed to replace the transformer. The generator step-up transformer sits on a concrete pad base in a fenced area of the station next to the river, making it important to provide a containment system in the case of an oil leak.
Workers from Engineers Construction Inc. of Williston, Vt., installed the system in the fall of 2008. They attached an impervious liner to the 12-foot-by-12-foot concrete pad base of the transformer, then filled the liner with stones. A berm around the transformer can contain 100 percent of the oil in the transformer, plus a 10 percent allowance for rain. In one corner of the liner, workers installed a Petro-Pipe that ultimately empties into the river.
The Petro-Pipe is a 16-inch-long, 6-inch-diameter cylinder. The cylinder is filled with a patented filter material to about two-thirds of the way up from the bottom. The top of the pipe contains a filter to remove dirt and debris. The cylinder attaches to the impervious liner at Peterson through a system of flanges and gaskets manufactured by SPI.
This pipe serves two functions. First, it lets rainwater drain from the stones and liner. Second, if oil reaches the cylinder, the filter material instantly forms a plug. This plug stops all flow and prevents oil from seeping into the surrounding soil or entering the river. The Petro-Pipe is designed to be used in situations where a vertical drain is not feasible.
Easy maintenance was the main factor in the decision to use the Petro-Pipe at Peterson. “It has a standard replaceable insert,” says Dermot Hughes, substation designer for Central Vermont Public Service. “You just slip in a new one, and you’re good to go.” Plant personnel check the filter monthly and replace it when necessary.
Fortunately, there has been no opportunity to test the containment system. “We’ve never had a catastrophic spill where we could test an oil containment system,” says Hughes. “We hope it never happens.”
Coatings provide smooth surface on hollow jet valves at Yellowtail
To minimize future cavitation damage to the interior of the two hollow jet valves at Yellowtail Dam, the U.S. Department of the Interior’s Bureau of Reclamation had the interior of the valves coated with products from ENECON Corporation. The valves now have a high-quality finish with no signs of cavitation damage or metal corrosion, says Tom Tauscher, facility manager at Yellowtail.
ENECON will be exhibiting at the Waterpower conference.
Yellowtail Dam is on the Big Horn River in Montana. It impounds water for a 250-MW hydro project that began operating in 1966. At the bottom of the dam, two 84-inch-diameter hollow jet valves discharge excess water when releases exceed the capacity of the turbine-generating units. These valves also maintain flow in the river if the reservoir elevation drops below the turbine intakes.
These hollow jet valves had last been recoated in 1988. Since that time, small amounts of cavitation damage had been occurring on the interior of the valves, Tauscher says. In addition, the existing coatings were failing in some areas, resulting in corrosion of the base metal, he says.
In 2008, Reclamation’s Great Plains Regional office awarded a $320,000 contract to Ostrom Painting and Sandblasting Inc. of Rock Island, Ill., to recoat the valves and ring follower gates. Ring follower gates serve as head gates for the hollow jet valves, similar to a gate valve. As part of this contract, Reclamation specified use of two specific products from ENECON. “We selected these materials based on Reclamation testing and experience, as well as the products’ reputation and performance,” Tauscher says.
Ostrom personnel used DuraTough DL from ENECON on the entire interior body of the valve, which is the area most vulnerable to cavitation damage. DuraTough DL is a two-component, 100 percent solids, fluid consistency elasto-ceramic polymer composite coating system. For other interior surfaces, Ostrom used CeramAlloy CL+ [AC] from ENECON. This product is a two-component, 100 percent solids, liquid consistency polymer composite coating system. The function of this coating is to protect equipment from erosion and corrosion.
To prepare for the recoating process, Ostrom personnel dewatered each unit and removed the existing coating systems from the surfaces of the hollow jet valves, downstream face of the ring follower gates, and interior surfaces of the penstocks. The contractor also prepared the surfaces to be recoated, with weld repair of cavitated areas and a full abrasive media blast.
The recoating work on both units was completed in November 2008.
“The project turned out very well, with a high-quality finish,” Tauscher says.
Weather system used to provide hydrologic forecasts
Seattle City Light and the U.S. Army Corps of Engineers use a system provided by 3TIER Environmental Forecast Group to develop forecasts of inflow at their hydro projects. Use of this system gives the two hydro project owners confidence in their forecasts and the decisions made as a result of this data.
Seattle City Light began using this technology in 1999 — when it was still under development at the University of Washington’s Department of Atmospheric Sciences — to establish an inflow forecast system for its Skagit River project, says Wing Cheng, P.E., senior mechanical engineer at Seattle City Light. Ross Reservoir, the main storage reservoir for this project, has a storage capacity of 1.298 million cubic meters, which is used to produce electricity at the 353-MW Ross powerhouse. The Ross powerhouse provides nearly 20 percent of Seattle City Light’s total hydro generating capacity of 1,807 MW. Ross Reservoir is the most upstream of the three in Seattle City Light’s Skagit River project and releases water directly to the 199-MW Diablo and 159-MW Gorge powerhouses.
This inflow forecast system was developed by linking a high-resolution regional weather forecasting model with a distributed hydrology model. The regional model is based on the Pennsylvania State University/National Center for Atmospheric Research mesoscale model, known as MM5. (Mesoscale refers to meteorological phenomena that are about 1 to 100 kilometers in horizontal extent.) The hydrology model is based on the Distributed Hydrology Soil Vegetation Model (DHSVM) developed by the Land Surface Hydrology Research Group of the University of Washington’s Civil Engineering Department. In 2001, 3TIER took over operation of the Skagit forecasting system from the University of Washington.
Cheng says Seattle City Light uses both short- and long-term forecasting technology from 3TIER. The short-term system is web-based, providing a seven-day hourly forecast for both the inflow and weather at several strategic locations within the upper Skagit River drainage basin. The utility’s power dispatchers and real-time power marketers use this forecast to determine the system generating requirements needed to balance the system load requirements within the next two days, Cheng says. The dispatchers also use the forecasts to prepare for operation during severe weather conditions.
The long-term system provides predictions of Ross Reservoir monthly inflow for 12 months, based on the current hydrologic state of the watershed, projected El-Nino Southern Oscillation (ENSO), and Pacific decadal oscillation (PDO). Cheng says power marketers use this forecast to determine the potential power surplus and deficit in order to secure long-term power sales and purchases, and financial analysts use this product to prepare the utility’s revenue forecast.
The Corps, a second user of 3TIER’s forecasting tools, began using them in 2003 to provide information during the winter flood season (November through March), says Lawrence J. Schick, meteorologist with the Corps. The Corps needs to be able to forecast the weather to ensure proper flood control in western Washington, Schick says. The data 3TIER supplies covers five dams: Howard Hanson, Mud Mountain, Ross, Upper Baker, and Wynoochee.
Floods in western Washington usually last only 24 to 48 hours and are very intense, with focused heavy rainfall rates caused by atmospheric river weather patterns, Schick says. For the unique needs associated with these floods, Schick says 3TIER developed a custom product for the Corps. This product is a hydro model calibrated to the affected river basins, driven by a mesoscale weather forecast. This differs from the standard offering in that it provides the greater precision and rapid update cycles (four times a day) needed for quickly changing flood control operations, Schick says.
In the past six years, western Washington has experienced four historic floods. In addition, floods in the region appear to be increasing in both frequency and magnitude, Schick says. The Corps uses the information provided by 3TIER’s model, before and during major rain-producing floods, to make decisions about and assess the risk associated with real-time dam operations and emergency management.
Sealing system reduces leakage at Entracque pumped-storage
To reduce water leakage at one turbine-generating unit at its 1,190-MW Entracque pumped-storage complex in Italy, Enel SpA retrofitted the unit with a split-type HydroSele S cartridge seal from James Walker & Co. Ltd. of the United Kingdom (a division of James Walker Group). This seal features two elastomer-based rotary sealing elements working back-to-back with flush water introduced between them instead of a face sealing arrangement typically used by mechanical seals. Installation of this sealing system solved the leakage problem on the unit, Enel says.
James Walker Mfg. Co. of Glenwood, Ill., also a division of James Walker Group, will be in the Waterpower exhibit hall to share details about the HydroSele cartridge seal system. This system can be used on either Francis or Kaplan units with shaft diameters between 9.8 and 29.5 inches.
When the Entracque complex was completed in 1980, the shaft of Unit 9 was outfitted with a spring-energized conical wedge mechanical seal. This unit is a reversible Francis turbine with a shaft diameter of 680 millimeters (26.8 inches) that runs at 600 revolutions per minute. By 2006, as much as 300 liters of water per minute was leaking past the mechanical seal, causing flooding of the powerhouse. Enel had to change the mechanical seal every three years, which involved having the unit out of service for two months. This was a costly exercise that created an unacceptable loss of generating capacity, Enel says.
In 2006, Enel decided to replace the mechanical seal with the HydroSele system. The innovative feature of the HydroSele system is the way its two sealing elements operate within their housings in a cartridge. The two elements work back-to-back, with filtered water flushed between them at 30 pounds per square inch above the water pressure at the sealing gland. The elements are pressure-balanced and run on a hydrodynamic fluid film that provides high speed capability with a low level of controlled leakage.
Because the system is modular, each component can be designed and precision-manufactured to fit together perfectly around a specific turbine shaft. For example, the complete split-type assembly of outer housing ring, flush ring, inner housing ring, and two sealing elements can be installed without stripping down the housing. This can reduce the amount of time needed for the turbine to be off line during both initial installation and refurbishment.
In 2000, Enel began conducting market research to find a reliable solution to the leakage problem on Unit 9. Eventually, Enel chose the HydroSele system for testing on this unit. Enel personnel then worked with James Walker technical staff to customize the sealing arrangement to this specific application.
Maintenance staff with Enel installed the sealing system on Unit 9 at the Entracque complex during a two-month outage in the spring of 2006.
The new sealing system reduced leakage from this unit to 15 liters per minute, a 95 percent decrease. This eliminated the problems of plant flooding and reduced generation.
The sealing system on Unit 9 continues to operate satisfactorily and has not needed any adjustments, Enel says.
