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ERC takes lead in optimizing China’s coal-fired power plants



Engineers from Lehigh's Energy Research Center are installing the center's boiler-optimization software at the Pan Shan coal-fired power plant outside Beijing, China.

China, long the world’s most populous nation, now also leads the globe in the consumption of coal. Coal accounts for 75 percent of China’s total power generation, and the Chinese according to some reports are opening a new coal-fired power plant at the rate of almost one per week.

The growing use of coal, coupled with massive industrialization across China, has caused severe pollution that led the government to shut down industries and restrict auto traffic during last summer’s Olympic Games in Beijing.

At the same time, says Edward Levy, the director of Lehigh’s Energy Research Center (ERC), China has invested in modern power-plant equipment and is seeking Western expertise in making its power plants run more efficiently and cleanly.

Some of that expertise is coming from the ERC itself. The research center last summer joined forces with a Chinese company to demonstrate the effectiveness of Boiler OP, a combustion optimization technology, at a large coal-fired power plant near Beijing.

Boiler OP was developed by ERC researchers in the mid-1990s and has been implemented since then at more than two dozen U.S. power plants. The technology gathers test data on the effects of boiler operating conditions on power plant efficiency and pollutant emissions. It then integrates the data with neural networks, expert systems and other artificial intelligence techniques to determine the combinations of boiler operating conditions that give the best power plant efficiency and the lowest rates of emissions of air pollutants such as nitrogen oxide. Nitrogen oxide, often referred to as NOx, reacts with sunlight to cause smog, which harms lung tissue.

“China’s new power plants are very sophisticated,” says Levy. “They combine the best of the West and the best of the East. But although several hundred power plants in the U.S. use various forms of combustion optimization, the concept is only now starting to catch on in China.

“Boiler OP is one of the first combustion optimization approaches to be tried out in China.”

A team of ERC engineers, led by ERC associate director Carlos Romero, has overseen the implementation of Boiler OP at a 600-megawatt unit of the five-year-old Pan Shan power plant. The Lehigh team has made two trips to the plant since June 2008 and will return in March 2009 to install the Boiler OP software and train Pan Shan personnel in its use. Other team members include ERC senior research scientist Harun Bilirgen and ERC research scientist Zheng Yao.

Pan Shan is owned by a large Beijing-based utility company. The ERC is working on the Pan Shan project with the XiAn JieHua Environmental Protection Science and Technology Company of Xian, China, which provides engineering services to the Chinese power generation sector.

Analysis of the data generated to date, says Romero, shows that Boiler OP will enable Pan Shan to reduce NOx emissions by more than 20 percent while improving power plant thermal efficiency.

An integrated system

Boiler OP was developed by engineers from the ERC and the Potomac Electric Power Co. to help meet federal limits on NOx emissions from power plant boilers.

The Boiler OP technology, which can be applied to gas-, coal- or oil-fired boilers, achieves efficiency improvements and NOx reductions by systematically adjusting a dozen or more boiler control settings. Among other things, these control the amount of air that is introduced with the coal, the manner in which the coal and air are mixed, and the position and shape of the flame zone in the boiler.

ERC engineers have developed separate software programs that work in tandem with Boiler OP, says Romero. One program automates the analysis of data. Another integrates data with artificial intelligence techniques and enables plant operators to modify boiler settings in real time in response to data.

The configuration of the optimized boiler control settings and the design of the Boiler OP software, say ERC engineers, must be customized to each individual power-plant boiler.

“No two power plants run the same,” says Bilirgen. “Even two boilers that are side by side at the same power plant might run completely differently.”

Another challenge to combustion optimization is the fact that coal heating value and other properties vary from one type of coal to another. This affects the efficiencies of combustion and the levels of NOx emissions which can be obtained from a given boiler.

Applications beyond coal

Over the years, Boiler OP has been improved with refinements to its optimization and artificial intelligence techniques.

“We are constantly adding new capabilities to Boiler OP,” says Levy.

In 2006, Boiler OP became one of the first combustion optimization technologies to be used with an oil-fired power plant when it was applied to a 350-megawatt unit of the PALM power plant in Tuxpan, Mexico. The software succeeded in improving the plant’s boiler efficiency as well as reducing its emissions of total suspended particles.

Boiler tuning techniques developed at the ERC have also succeeded in reducing levels of mercury and other pollutants emitted by power plants.

The ERC’s initial contact with the Pan Shan power plant was facilitated by Yao, who earned his M.S. in mechanical engineering from Lehigh in 2004. Before coming to Lehigh, Yao had worked as a controls engineer in the Chinese power generation sector.

Once the Pan Shan project is completed in the spring of 2009, says Levy, the ERC plans to pursue projects with other Chinese utilities that have expressed an interest in utilizing Boiler OP.

--Kurt Pfitzer


Posted on Monday, January 12, 2009

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