ONCE-THROUGH BOILERS

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Urquhart Repowering Project, Beach Island, South Carolina

June 24, 2008 at 7:16 am | Posted in Combined Cycle, Gas Turbine, Power Plant, Repowering | 1 Comment
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Owned and operated by South Carolina Electric & Gas Co.

For many utilities, repowering a 50-year-old coal-fired plant has become an attractive alternative to making expensive environmental upgrades to such a plant reaching the end of its useful life. Repowering is especially attractive if the plant’s existing water and air permits can be “recycled.” South Carolina Electric & Gas Co. was able to do just that at its Urquhart Station a few years ago. By repowering the plant’s older two units and cross-connecting them with Unit 3, the utility boosted Urquhart’s overall efficiency and operating flexibility. Creative engineers found a way to squeeze every dollar of savings from this plant.

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Fish-friendly hydro turbines move center stage

June 24, 2008 at 7:10 am | Posted in Environmental, Power Plant | Leave a comment

Hundreds of U.S. hydro plants come due for license renewal over the next decade, giving river and wildlife advocates an ideal time to push for fish-friendly turbine retrofits. With these new, e-“fish”-ent turbines, early retrofit projects have targeted up to 98% fish-passage efficiency and up to 15% more power output.

The 91,000 MW of hydropower capacity in the U.S. comes from about 180 federal projects and more than 2,000 non-federal projects regulated by the Federal Energy Regulatory Commission (FERC). Although the country has substantial undeveloped hydropower resources, little new construction is expected, and hydropower’s share of the nation’s generation is predicted to decline through 2020, due to a combination of environmental issues, regulatory pressures, and changes in energy economics.

FERC is the lead permitting agency for private hydroelectric plants. The U.S. Fish and Wildlife Service for the eastern part of the country, and the National Marine Fishery Service for the western part, are other agencies that make recommendations on fish mortality goals. In response to the 1986 Electric Consumers Protection Act, these agencies have set their target as “no fish production loss” for all new hydro projects as well as for any projects for which the hydraulic lease is expiring. That last phrase is key, because there are hundreds of plants in the U.S. that must pass through the relicensing minefield over the next decade. About 80% of California’s hydropower is subject to a FERC license, and about half of those facilities—approximately 4,000 MW at 150 projects—are due for license renewal in the next 15 years.

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How fish-friendly turbines work

June 24, 2008 at 7:09 am | Posted in Environmental, Power Plant | 2 Comments

Quantifying the fish injuries caused by a hydroelectric turbine often has been based more on model predictions than actual measurements. Survival rates measured for fish passing directly through a modern large turbine range from 88% to 94%. By comparison, fish bypass system survival rates typically range from 95% to 98% percent and from 95% to 99% percent for a spillway system.

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On-line cleaning of trans.former oil boosts reliability, dielectric properties

June 24, 2008 at 7:08 am | Posted in Power Plant | Leave a comment
A technology called balanced-charge agglomeration (BCA) has proven its ability to restore oil to cleaner-than-new conditions in a variety of applications. BCA accelerates particulate agglomeration and removal of sub-micron material, eliminates the water-holding particles upon which emulsions form, and allows for faster and more complete water removal.

Oil condition data published in 2001 makes reference to the first application of this technology on steam-turbine lube oil. The research trial ran for more than five years and concluded that the lube oil tested at 16 times cleaner than new oil specifications (Figure 1). The technique essentially supercharges the filtration process by electronically removing sub-micron material and products of oxidation together, for removal by standard and proprietary filters.

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Canadian utility mixes oil and water

June 24, 2008 at 7:07 am | Posted in New Construction, New Technology | Leave a comment


NB Power’s (Fredericton, N.B.) 1,050-MW Coleson Cove station has received approval to begin a $475-million refurbishment that includes a fuel switch from heavy oil to Orimulsion, environmental equipment upgrades, and a new pipeline and offshore unloading system to deliver the fuel to the plant. The upgrades to the three identical units at the plant are required to meet new environmental standards that take effect in 2005. Coleson Cove, located in the Lorneville area of west Saint John, currently supplies over 30% of New Brunswick’s electrical power. The upgrade project is scheduled for completion in the fall of 2004.

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Control system upgrades can save big bucks

June 24, 2008 at 7:07 am | Posted in New Technology, Power Plant | Leave a comment

The decision to upgrade powerplant control systems is not a simple one; however, the economic payoff can be substantial. Recent studies by Siemens Westinghouse (Newcastle, UK) indicate that improvements in plant performance thorough controls modernization can be substantial. For a typical 540-MW coal-fired powerplant, instrumentation and controls changes are projected to save a combined $1.8 million per year:

  • Fuel savings during normal operation: 0.4%—or $283,000/yr—is possible, mostly from tighter steam-temperature control, more accurate combustion and oxygen control, and conversion from fixed-pressure to sliding-pressure operation.
  • Fuel savings during startup: 50%—approximately $17,000/yr—is possible. Automated controls enable a plant to adhere more closely to stress limitations.
  • Fuel savings during load ramps: It is possible to achieve load-ramp rates of 5% of MCR/min above 60% load and 3%/min between 35% and 60% load. Improved ramp rates allow the unit to respond faster, thus “catching” higher market prices and reducing load quicker when the market prices drop. Savings are estimated at $532,000/yr.
  • Fuel savings due to reduced forced-outage rates: National Electric Reliability Council data indicate that the average forced outage rate for a coal-fired unit lasts about 20 hours. If a plant can reduce that figure by more intelligent controls, safe run-back to partial loads instead of a trip, and improvements in trip-system reliability, then it can save just over $1 million/yr.

Gas turbine combustors drive emissions toward nil

June 24, 2008 at 7:06 am | Posted in Environmental, Gas Turbine, Low NOx, New Technology, Power Plant | 2 Comments
Best available control technology continues to be ratcheted down to achieve ever-lower NOx emissions. Some dry low-NOx combustors can achieve 9 ppm without post-combustion control, while newer catalytic combustors are operating below 5 ppm NOx.

In the late 1980s, gas turbine original equipment manufacturers (OEMs) began to integrate dry low-NOx (DLN)—also referred to as dry low-emission (DLE)—combustion technology into their product lines to eliminate the need for steam or water injection, which had been the traditional method of NOx control. Many DLN technologies were evaluated, and lean premixed combustion emerged as the most promising approach for near-term application.

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Designing and modifying HRSGs for cycling operation

June 24, 2008 at 7:04 am | Posted in Combined Cycle, Gas Turbine, Power Plant, Steam Turbine | Leave a comment

Designing and operating HRSGs for cycling duty requires close cooperation between the manufacturer and the user. Once HRSGs are in service, a monitoring system should provide a thorough picture of the mechanisms affecting the life and integrity of the boiler.

Today’s heat-recovery steam generators (HRSGs), a vital component in the popular combined-cycle plant, are exposed to more severe duty than merely running at baseload. Deregulation has spurred the development of merchant plants, which are required to start up, load follow, and shut down with minimal notice in response to market conditions. Unless properly designed and operated to withstand this cycling duty, the integrity of the HRSG will be compromised.

Industry professionals need to understand the various damage mechanisms that can result, as well as how to control them. For new projects, damage control begins with the specification of certain design features. Operation and maintenance practices also play an essential role in managing HRSG life, both for new and existing plants. Existing plants also should explore modifications and monitoring programs that can boost the reliability and extend the service life of HRSGs in cycling duty.

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Germany fires up latest supercritical plant

June 24, 2008 at 7:02 am | Posted in Uncategorized | Leave a comment
The new Niederaussem-K 1,050-MW power station—one of the world’s largest and most advanced coal-fired units—was officially put into operation late last year. Niederaussem is a supercritical, lignite-fired powerplant complex west of Cologne, Germany (Figure 2). The first oftwo 150-MW units started up in 1962 and was followed byfour 300-MW units and two 600-MW units.Chancellor Gerhard Schroeder was present at the commissioning and emphasized the role of local-sourced brown coal as a stabilizing factor in the energy mix for Germany.

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