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It may be concluded that the Master Cycle offers an excellent opportunity to gain a heat rate improvement in the range of 4 percent (or an efficiency improvement in the range of 2 percentage points) at economic viable capital cost compared with a single reheat cycle. Furthermore, there is no impact on the thermal flexibility of the plant and the erosion and corrosion problems of the last stages of the LP turbines disappear.
The barrier of 50 percent net efficiency can be broken with a steel-based (and seawater-cooled) power plant operating at maximum steam temperatures in the range of 1,112°F. This result demonstrates the effectiveness of developments along the Carnot track.
The additional cost of the 800MW MC is approximately 40 million euro compared to a single reheat plant, resulting in a very short payback time of the additional investment, even when a risk premium is added. The additional output of the MC is 40 MW for the same fuel input, resulting in specific investment costs of 1,150 euro/kW, similar to the average specific
The simple sliding, pressure-controlled T-turbine is important as a decentralized source of bleed steam, resulting in important savings of space and piping for steam bleeds.
Further, the T-turbine is important as a feed pump drive, which paves the way for one 100 percent feed pump and reduces the need for electric auxiliary power by 30 percent. The balancing motor guarantees the correct speed of the feed pump.
Most technical departments of the turbine companies we have been in contact with recognize the new ideas of the Master Cycle, but the market departments are still asking for the market possibilities.
Therefore, despite the many technical advantages, the success of the MC can only be guaranteed if other power generators than DONG Energy show their interest. We strongly encourage those power generators interested in improving efficiencies of coal-fired power generation to contact us and we will share our experience with them.
Editor’s note: This paper, PWR2010-27369, was printed with permission from ASME and was edited from its original format. To purchase this paper in its original format or find more information, visit the ASME Digital Store at www.asme.org.
Frank Drinhaus has a master’s degree in mechanical engineering from the Technical University Braunschweig, Germany, in 1994. He has worked more than 15 years as a thermodynamic engineer, responsible for heat balance calculations on boilers, steam and gas turbines. He has worked for DONG Energy since 1998 in the performance analysis and process calculation department, mainly performing thermodynamic process calculations and performance testing of USC coal-fired power plants, as well as CCGT power plants.
Sven Kjaer has comprehensive theoretical and practical experience in design and thermodynamics of super critical, coal-fired power plants. He has driven development of DONG Energy’s supercritical power plants since the beginning of the 1980s and invented a modified double reheat steam cycle, named the Master Cycle, offering higher efficiency at an affordable cost. Kjaer has a master’s degree in mechanical engineering from the Technical University of Denmark and has worked with DONG Energy since 1979.
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