Materials-development projects for advanced ultra-supercritical(A-USC) power plants with steam temperatures of 700℃ and above have been performed in order to achieve high efficiency and low CO_2 emissions in Europe, ...Materials-development projects for advanced ultra-supercritical(A-USC) power plants with steam temperatures of 700℃ and above have been performed in order to achieve high efficiency and low CO_2 emissions in Europe, the US, Japan, and recently in China and India as well. These projects involve the replacement of martensitic 9%–12% Cr steels with nickel(Ni)-base alloys for the highest temperature boiler and turbine components in order to provide sufficient creep strength at 700℃ and above. To minimize the requirement for expensive Ni-base alloys, martensitic 9%–12% Cr steels can be applied to the next highest temperature components of an A-USC power plant, up to a maximum of 650℃. This paper comprehensively describes the research and development of Ni-base alloys and martensitic 9%–12% Cr steels for thick section boiler and turbine components of A-USC power plants, mainly focusing on the long-term creep-rupture strength of base metal and welded joints, strength loss in welded joints, creep-fatigue properties, and microstructure evolution during exposure at elevated temperatures.展开更多
Since the reform and opening up, the construction in all aspects of our country has achieved a rapid development, and especially the development of the industrial construction is also more prominent, so that each big ...Since the reform and opening up, the construction in all aspects of our country has achieved a rapid development, and especially the development of the industrial construction is also more prominent, so that each big city rapidly moves forward. But in the development at the same time, some of the issues are inevitable. The rapid development of the cities has attracted a large population, and there are more and more large factories, so that there is more and more pollution in the life and production, which brings greater security risks to the human life and health, and let the cities more difficult to manage. So how to solve these problems and make the cities develop better is a problem worth pondering.展开更多
The mountainous region of Fthia, identified with the Valley of Sperchios River, in Central Greece, is rich in small watercourses and generously blessed with water and abundant water falls. The geographical configurati...The mountainous region of Fthia, identified with the Valley of Sperchios River, in Central Greece, is rich in small watercourses and generously blessed with water and abundant water falls. The geographical configuration of Olympus and Fthia＇s mounts and the hydraulic singularities of drained lakes Askouris in Olympus, favour the installation of series of sustainable small hydroelectric plants. The present action consists of a serious effort towards the systematic sustainable small hydropower exploitation of Fthia＇s and Olympus hydraulic potential, including the Archimedean hydropower perspectives of Sperchios River.展开更多
Excitation system is one of the significant elements affecting the dynamic performance of electric power systems. The power engineering as area of science and industry is subjected to rapid modernization, which is cau...Excitation system is one of the significant elements affecting the dynamic performance of electric power systems. The power engineering as area of science and industry is subjected to rapid modernization, which is caused by technological progress. However, not all elements of the power system are developing simultaneously. The old type of elements sometimes is sufficient to adapt old system to the new operational conditions. The work developed and proposed in this paper deals with analysis of possible optimization of synchronous generator＇s excitation system. Authors examined influence of excitation system＇s parameters to the dynamics of transient processes in the power system. Authors investigated optimal parameters of excitation system of the Kegums hydro power plant. For optimization of parameters objective functions were used. The problem of the mutual influence of excitation systems of neighbor power plants was investigated. Investigation of transient processes using developed model proved that optimization of excitation parameters improves efficiency of regulation of excitation system, damping of active power oscillation and in some cases can prevent out-of-step condition.展开更多
文摘Materials-development projects for advanced ultra-supercritical(A-USC) power plants with steam temperatures of 700℃ and above have been performed in order to achieve high efficiency and low CO_2 emissions in Europe, the US, Japan, and recently in China and India as well. These projects involve the replacement of martensitic 9%–12% Cr steels with nickel(Ni)-base alloys for the highest temperature boiler and turbine components in order to provide sufficient creep strength at 700℃ and above. To minimize the requirement for expensive Ni-base alloys, martensitic 9%–12% Cr steels can be applied to the next highest temperature components of an A-USC power plant, up to a maximum of 650℃. This paper comprehensively describes the research and development of Ni-base alloys and martensitic 9%–12% Cr steels for thick section boiler and turbine components of A-USC power plants, mainly focusing on the long-term creep-rupture strength of base metal and welded joints, strength loss in welded joints, creep-fatigue properties, and microstructure evolution during exposure at elevated temperatures.
文摘Since the reform and opening up, the construction in all aspects of our country has achieved a rapid development, and especially the development of the industrial construction is also more prominent, so that each big city rapidly moves forward. But in the development at the same time, some of the issues are inevitable. The rapid development of the cities has attracted a large population, and there are more and more large factories, so that there is more and more pollution in the life and production, which brings greater security risks to the human life and health, and let the cities more difficult to manage. So how to solve these problems and make the cities develop better is a problem worth pondering.
文摘The mountainous region of Fthia, identified with the Valley of Sperchios River, in Central Greece, is rich in small watercourses and generously blessed with water and abundant water falls. The geographical configuration of Olympus and Fthia＇s mounts and the hydraulic singularities of drained lakes Askouris in Olympus, favour the installation of series of sustainable small hydroelectric plants. The present action consists of a serious effort towards the systematic sustainable small hydropower exploitation of Fthia＇s and Olympus hydraulic potential, including the Archimedean hydropower perspectives of Sperchios River.
文摘Excitation system is one of the significant elements affecting the dynamic performance of electric power systems. The power engineering as area of science and industry is subjected to rapid modernization, which is caused by technological progress. However, not all elements of the power system are developing simultaneously. The old type of elements sometimes is sufficient to adapt old system to the new operational conditions. The work developed and proposed in this paper deals with analysis of possible optimization of synchronous generator＇s excitation system. Authors examined influence of excitation system＇s parameters to the dynamics of transient processes in the power system. Authors investigated optimal parameters of excitation system of the Kegums hydro power plant. For optimization of parameters objective functions were used. The problem of the mutual influence of excitation systems of neighbor power plants was investigated. Investigation of transient processes using developed model proved that optimization of excitation parameters improves efficiency of regulation of excitation system, damping of active power oscillation and in some cases can prevent out-of-step condition.
