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Dec 25 - McClatchy-Tribune Business News Formerly Knight Ridder/Tribune
Business News - Pam Zubeck The Gazette, Colorado Springs, Colo.
When people flip the switch in their Colorado Springs homes, they just want the lights to come on. They don't think about the 160 people who staff the plants around the clock to assure that a pinhole in a pipe doesn't cause a blowout that could shut down a plant for days. To fully appreciate energy, you must dig deeper They don't think about the constant monitoring of environmental devices to keep the plants in compliance with federal and state regulations. They don't think about a 10-year planning process designed to identify repairs and maintenance needs that, if miscalculated, could allow a major component failure, costing ratepayers millions of dollars in purchased power. But the 160 people who run Drake and Nixon think about those things. It's their job to run the plants that supply 73 percent of the power Colorado Springs Utilities delivers to its 190,000 customers. The rest comes from gas, hydro, wind and purchased power. Coal-burning Drake, at 256 megawatts, and Nixon, at 208 megawatts, provide the city its most economical power, costing a fraction per megawatthour, about $12, compared with other sources. Together, that's enough electricity for the plants to light more than 4.6 million 100-watt light bulbs per hour. After making the 300-mile journey from the mine, the hard, black lumps of coal are converted into invisible energy that lights buildings, powers computers and runs toasters. "We're not creating anything," Drew Rankin, Springs Utilities energy supply general manager, said. "We're just converting it." Here's how that happens: Baseball-sized chunks of coal are dumped into a bunker that feeds them into a pulverizer where the coal is blended with air and ground by giant ball bearings into a fine powder. "The reason we do that is because coal only burns on the surface," said Drake plant manager Gary Klein. "We want to extract all the energy from the coal as soon as we put it into the furnace." Blown into the furnace with fans, the powder burns to 3,000 degrees, heating waterfilled tubes that line the boiler. The water boils, rising into a steam drum 30 feet long and 15 feet in diameter made of 6-inchthick steel. There, water converts to steam that's superheated as it runs through pipes inside the boiler to remove water vapor. When it reaches the turbine, the steam is 1,000 degrees and has built up 1,450 pounds of pressure per square inch, about 40 times that of an inflated car tire. "Now we've got the pressures and temperatures we're striving for," Klein said of the process that happens in a matter of minutes. The steam jets onto about 1,500 1- to 3-inch blades inside the turbine that act like pinwheels. That step transfers heat energy to mechanical energy, which, in turn, powers the generator. The generator consists of a 15- to 20-ton shaft wrapped with wire turned by the turbines, which creates 13,800 volts of electricity. A transformer then boosts voltage to 115,000 volts at Drake, in downtown Colorado Springs, and 230,000 at Nixon, about 20 miles south of the city, to push it to Springs Utilities' customers. "The higher the voltage, the less the losses along the way," Rankin said. Before being delivered to customers, transformers reduce voltage to 115 and 220 volts. The steam that drove the turbines cools in a few minutes, and the process begins anew. The cooling process sends plumes of harmless condensation rising from the plants, often visible for miles on cold winter days. "The challenge is to utilize that resource and minimize the impact on the environment," Rankin said. Coal plants in Colorado face hundreds of regulations designed to protect air quality, although carbon dioxide -- the nation's primary global warming agent -- is not regulated. Power plants emit 40 percent of all carbon dioxide pollution in the United States, and officials, power companies and scientists are debating how, or whether, to regulate those emissions. For now, regulators only measure emissions. Drake releases 2.4 million tons of carbon dioxide annually, and Nixon spews 1.7 million million tons. Utilities officials caution the figures must be viewed in perspective. A 2000 state report, the most recent available, which measured emissions statewide in 1997, reported that utilities pumped 42 million tons of carbon into the air from burning fossil fuels, or about 47 percent of the state's total of 89.1 million tons. Gas engines added 21.9 million tons and residences, 7.6 million tons. Padgett noted that while carbon dioxide has been blamed for contributing to global warming, it is not considered a health issue like regulated pollutants are, among them sulphur dioxide and nitrous oxide. While standards generally vary depending on a plant's age, Drake and Nixon conform to roughly the same requirements. Drake's oldest turbine dates to 1963, while Nixon was built in 1980. Both rarely exceed the limits, said Mike Brady, utilities' technical services supervisor. For example, during the first half of 2006, Drake deviated from the standard for three six-minute periods. The city hasn't been fined for an environmental issue at Drake in at least a decade, and Nixon has brought only one fine during that time. Earlier this year, the city paid an $8,750 penalty for a 2004 episode that was fixed in one day. "In the last at least 10 years we've gotten this one fine for an event that happened in 2004 for a period of less than six hours on one day," said Dave Padgett, manager of environmental services. The plants' low emissions levels are tied, in part, to the low-sulfur coal it burns. But both plants produce plenty of ash, removed from the atmosphere by baghouses equipped with thousands of 30-inch-long fabric sacks that capture the burned coal's ash. The sacks are emptied twice a day, and the tons of ash carted to a disposal area near Nixon. There are other ways to get rid of it, though, such as mixing it into concrete, and Springs Utilities recently issued a request for proposals to buy it. All of these efforts don't come cheap. Baghouses cost the city $9 million to $18 million for initial investment, and the low nitrous oxide burners, $10.3 million. To run environmental protection systems at the two plants costs the utility $1.4 million annually. More cost is coming. Scrubber devices to reduce sulfur dioxide, which will be added at Drake in coming years, will cost millions. To keep the plants humming at top efficiency requires scheduled maintenance biannually. For one of Drake's units, that four-week break came in October and November. Next spring, another Drake unit and one at Nixon will get the once over. "We schedule outages in time blocks when we can most accommodate that," Rankin said. That means doing it in the spring and fall when demand is low and purchased power is the cheapest. The downtime gives crews time to look for problems, such as worn out parts, and fix them. "It's like putting your car on 70 mph for 335 days," Rankin said. "After that you'll probably find some things." Last year, Drake ran 335 days without a rest. After an hours-long shutdown, it was up and running again. During scheduled maintenance, workers inspect turbines for eroded blades and the baghouse's filters, the goal being to find and fix things that compromise a plant's efficiency and integrity or install new components to boost both. This go-round, Drake's unit got a new "step-up" transformer to replace a 40-year-old one that was expected to fail in the next five years. The replacement not only makes a failure unlikely, it makes the system less susceptible to interruptions, Klein said. Those kinds of parts aren't available on short notice. The recently installed model was ordered 18 months ago. The alternative -- shutting down the unit while waiting -- would cost utilities $90 million in purchased power, Rankin said. He said Drake has outperformed expectations by every measure. It generated 300,000 more megawatt-hours than expected last year, saving ratepayers $12 million compared with purchasing power from other producers.
KEEPING THE PLANT SHIPSHAPE: Drake Power Plant's outage, fromthrough, allowed more than 500 work orders to be completed. Many were scheduled in advance with parts ordered months ago. Others were discovered during inspection. The work included: -- Boiler overhaul, including a comprehensive inspection, replacement of expansion joints and replacement of more than 420 high-pressure boiler generating tubes. -- Bottom ash hopper water-cooling system rebuilt. -- Original 40-year-old transformer replaced with a stepup transformer that will increase the secondary voltage from 34,500 volts to 115,000 volts to provide a more stable electrical system. -- High-pressure turbine steam-chest valve assembly replaced, involving detail work to achieve valve clearances measured to the thousandth of an inch. -- Internal wood structural components in the cooling tower replaced. -- All cooling-tower basin joints cleaned, reconditioned and regrouted to ensure cooling-tower process water doesn't seep. -- Twenty-year-old control system replaced after being engineered, planned and installed by utilities personnel, which provided technicians with valuable hands-on knowledge of the system they'll maintain for the next 30 years. Utilities saved $250,000 by not contracting the control-system work. Source: Colorado Springs Utilities |
When people flip the switch in their Colorado Springs homes, they just want the lights to come on