Coal

The 1,456-MW Brunner Island coal-fired plant has implemented advanced environmental improvements in order to be a good neighbor to the residents of south central Pennsylvania. For example, between 2006 and 2010, PPL invested more than $860 million in pollution control upgrades for air, water, and solid waste treatment at the facility.

Owner/operator: Mirant Corp. Dickerson Generating Station, a 50-year-old facility servicing Maryland and Washington, D.C., was recently upgraded with a flue gas desulfurization system and a unique draft system that allows an electrostatic precipitator and a baghouse to share flue gas cleanup chores on each unit. In addition, state-of-the-art equipment monitoring and diagnostics keep plant reliability high for this baseload unit.

Unit 2 at J-POWER’s Isogo Thermal Power Station entered commercial service in July 2009. The 600-MW ultrasupercritical unit joins an earlier, similar plant built in 2002. Together, these two new plants replaced 1960s-vintage coal-fired plants and doubled power generation from the small project site. In addition, the new unit improves the plant’s gross thermal efficiency to about 45% while reducing air emissions to those of a gas-fired combined-cycle plant.

Adding two 615-MW supercritical pulverized coal units to the 1,135-MW Oak Creek Power Plant is part of We Energies’ ongoing master plan to “Power the Future” of Wisconsin well into the 21st century. The new Elm Road Unit 1 went into service in February, and Unit 2 is expected to start operations during the fourth quarter of 2010. With operations marked by high efficiency and low emissions, these new units will provide large amounts of cleaner energy to the Great Lakes area.

Located in a semi-arid region, this “Texas tough” coal-fired power plant uses a number of smart practices to increase water-use efficiency. For example, a pipeline was constructed to send blowdown water from nearby Plant X for treatment and recycling at the 1,080-MW Tolk Station, making both plants “zero-discharge” facilities. For its environmental stewardship and superior plant operations, the Powder River Coal Users’ Group named Tolk Station its 2010 Plant of the Year.

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Environmentalists renewed their attacks on coal-fired power development in 2010. At the same time, Congress dithered on cap-and-trade legislation while the Environmental Protection Agency marched forward rules to reduce carbon emissions from coal-fired power plants. Couple the regulatory uncertainty with lean economic times that have flatlined electricity demand growth plus low natural gas prices, and the result is predictable: New coal-fired plant construction is in the doldrums.

In the heart of corn country, Archer Daniels Midland is using seed corn that is no longer suitable for planting, along with coal, to power its 180-MW Clinton cogeneration plant. The cogeneration plant, which began operations in 2008, supports ADM’s Clinton corn processing plant, one of the largest corn wet mills in the world. It also supports ADM’s facility that produces renewable plastic from corn sugar. Firing up to 20% biomass along with coal, the new cogeneration plant is capable of providing 100% of the steam and electrical power needs of both facilities.

What’s in a name? Would coal ash labeled as “special” hazardous waste be as easily recycled as that labeled nonhazardous waste?

At the end of June, Xcel Energy fired up a demonstration project that integrates a 4-MW parabolic trough solar technology with an existing 44-MW coal-fired power plant.

Scuttling a high-profile “public nuisance” lawsuit, a federal appeals court has reversed a lower court ruling that required the Tennessee Valley Authority to accelerate plans to install pollution controls at four TVA coal-fired power plants to reduce the amount of pollution blowing into western North Carolina, saying the lower court decision could lead to other public nuisance suits that would wreak havoc on federal and state regulatory regimes for combating air pollution.

Saying they have “grave concerns” about the agency’s two-option proposal to regulate coal combustion ash, 31 members of the House Energy and Commerce Committee have urged the Environmental Protection Agency to continue to regulate coal ash as a non-hazardous waste, saying an EPA proposal to designate it as a “special” hazardous waste eligible for reuse would lead to costly and unnecessary management and disposal requirements.

An Environmental Protection Agency proposal to tighten sulfur dioxide and nitrogen oxides limits in 31 states and the District of Columbia to address transported air pollution fails to give utilities and state air regulators sufficient time to develop rules and install controls, according to American Electric Power Co. Officials from the EPA and New Jersey-based Public Service Enterprise Group said utilities already had begun making investments to cut emissions and they believed the agency’s compliance schedule could be met.

Many claim that wind generation is beneficial because it reduces pollution emissions and does not emit carbon dioxide. This isn’t necessarily the case. When wind is introduced into a generation system that uses carbon technologies to back up the wind, it actually reduces the energy efficiency of the carbon technologies.

Every power engineer must have a firm grasp of the rudiments of how fuel is processed to produce electricity in a power generation facility. With this article, we conclude our three-part series on the essentials of recovering heat from flue gas to dry and process coal, with the goal of improving overall plant operating efficiency.

Progress Energy has incorporated online combustion optimization/tuning to eliminate furnace reducing atmospheres at its Asheville Plant. The optimization project utilized individual burner airflow measurement and continuous burner coal flow measurement to adjust burner air/fuel ratios. The result: significantly improved boiler combustion.

While the U.S. awaits congressional action on a cap-and-trade program that could possibly be limited to just the utility sector, Canada is moving, starting in 2011, to phase out older coal power plants and replace them with natural gas–fired plants. The announcement, made this June by Environment Minister Jim Prentice prior to the G8 and G20 summits, could have serious implications for coal-fired generators in the country.

When heat exchanger tubes—sometimes numbering a thousand or more per unit—begin to crack or wear, the effects can lead to a cascade of subsequent failures in adjacent tubes. If too many tubes are plugged, heat exchanger effectiveness is compromised, and power generation may be curtailed. If conventional mechanical plugs are used, they can break loose, leak, and fail. At that point, the replacement of a very costly heat exchanger is imminent.

Stacks at power generating stations may be low maintenance, but they are not no maintenance. The cost of preventing corrosion may be as little as $10,000, but the cost of repair or replacement could be many times that or even put your plant out of commission until the stack problem is corrected.

Luminant used remnants of the ill-fated Twin Oaks and Forest Grove plants (which were mothballed more than 30 years ago) to build the new two-unit 1,600-MW Oak Grove Plant. Though outfitted with equipment from those old plants, Oak Grove also sports an array of modern air quality control equipment and is the nation’s first 100% lignite-fired plant to adopt selective catalytic reduction for NO_x control and activated carbon sorbent injection technology to remove mercury. For melding two different steam generators into a single project, adopting a unique and efficient “push-pull” fuel delivery system, assembling a tightly integrated team that completed the project on time and within budget, and for completing what was started almost four decades ago, Oak Grove Power Plant is awarded POWER magazine’s 2010 Plant of the Year award.

With commercial operation of Madison Unit 3, Cleco Power now claims bragging rights for owning the largest 100% petroleum coke–fired circulating fluidized bed power plant in North America. For using readily available fuel in an environmentally attractive manner, adopting fuel-flexible combustion technology, balancing the utility’s generation portfolio, and adopting an innovative fuel-handling system design, Madison Unit 3 is the winner of POWER’s 2010 Marmaduke Award for excellence in operation and maintenance. The award is named for Marmaduke Surfaceblow, the fictional marine engineer and plant troubleshooter par excellence.

The amount of air leaking into the boiler envelope is difficult to estimate. Traditional methods of measuring oxygen at the furnace exit and economizer exit do not account for all types of air leakage. By using molar calculations and total airflow measurement, a good approximation of the total air in-leakage rates of a boiler can be quickly determined using station instruments.

Catalysts used in selective catalytic reduction (SCR) systems in utility boilers provide high NO_x removal efficiencies that routinely exceed 90%. A major co-benefit of applying SCR to coal-fired power plants is that the SCR catalyst also oxidizes the vapor phase mercury from an elemental form to a soluble ionic form, which can be readily captured in a downstream flue gas desulfurization process. Mitsubishi Heavy Industries and Cormetech have developed an advanced SCR catalyst technology with high mercury oxidation activity capable of achieving 95% oxidized mercury over a wide range of operating conditions.

The competitive push for more efficient power generation prompted the management of East Kentucky Power Cooperative’s Spurlock Station to provide training and to implement standardized work processes in order to achieve higher productivity. To that end, Spurlock’s management collaborated with salaried and hourly personnel to design and implement work process optimization. Two years later, their proactive, operations-driven culture is promoting continuous improvement at this facility.

Eliminate waste in coal, gas, or nuclear power plant construction through a holistic application of lean principles.

When it is completed, later this summer, the UK’s Drax Power Station biomass facility will become the largest dedicated cofiring project of its kind in the world. As U.S. coal-fired generators come under increasing pressure to cut emissions and take advantage of incentives to promote power generation from renewables, Drax offers an example of what is possible.

Fogging systems have been successfully used in the material-handling industry for more than 30 years to control explosive dust at transfer points. Today, fogging systems are an EPA Best Demonstrated Technology for subbituminous coal preparation plants.

At the opening ELECTRIC POWER 2010 plenary session, both the keynote speaker’s address and discussion among the Power Industry Executive Roundtable participants pointed to the renewed appeal of natural gas and proposed cap-and-trade legislation as being potential game-changers for the U.S. power industry.

The 2010 Powder River Basin Users’ Group (PRBCUG) commemorated its 10th anniversary with 354 registered members (210 of whom were from operating companies) for its three-and-a-half-day annual meeting in Baltimore this May. The meeting’s Grand Sponsor was Benetech and its Plant Professionals group.

In an unusual two-option proposal that drew clashing views from green groups and power plant operators, the Environmental Protection Agency has proposed regulating coal combustion ash either as a nonhazardous waste subject to tougher management and disposal requirements or as a "special" hazardous waste that would have similar controls but still be eligible for recycling and reuse in products such as Portland cement.