Study On Decontamination Construction Technology Of1000MW Ultra Supercritical Air-cooling And Coal-fired Unit

In the21st century, the development of ultra supercritical power generation technology accelerates the step of construction of ultra supercritical unit. In October2006, the Chinese first ultra supercritical unit Yuhuan1000MW power plant successfully put into commercial operation, by the end of2009, there were twenty-one1000MW ultra supercritical units in operation and twelve units under-construction, thus the Chinese became possess the ultra supercritical units most country in the world. The advantage of ultra supercritical unit is high efficiency, low pollution and low cost, and it already became the dominant direction of current thermal power plant construction. As the most practical, feasible, reliable coal-fired power generation technology to reduce carbon dioxide emissions, the ultra supercritical units is the only road to realize low carbon power in our country.By large number of technical studying and engineering practicing on ultra supercritical unit, besides the part of boiler, turbine high temperature material, pump and valve, our country has basically formed the overall design, manufacture and operation for ultra supercritical units. We have established a complete set of design system for ultra supercritical unit, and is gradually narrowing the gap with foreign advanced level.In recent years, there are several1000MW units in operation and under-construction in china. The supercritical pressure coal-fired units accounted the proportion of domestic installed capacity larger and larger. Because the supercritical pressure coal-fired unit(600MW to1000MW) capacity is larger, once the unit happens to accident, it will be a serious threat to power grid safety, that can cause great influence on the national economy and the people’s living, directly and indirectly economic loss will be inestimable. Especially, the accident of bursting of boiler tube and leakage in600MW supercritical unit and above often occurs in operation that can brings security risks and economic losses to the power plant. Besides the reason of equipment manufacture, material misuse, and the improper methods of commissioning and operation, the debris in pressure pipelines with the process of installation and construction of the unit is the important reason for supercritical pressure coal-fired unit accident, such as the Harbin Boiler Factory and Dongfang Boiler Factory tube bursting of platen superheater of problem, all because tube blockage and overpressure in platen superheater then caused the tube bursting. The bursting tube of water-cooled wall also appeared in several600MW supercritical pressure units. At present, the debris blockage caused bursting of tube is a high frequency problem during commissioning and operation of supercritical pressure units. The collecting box debris blockage caused bursting of tube is nearly accounted50%, that is knowing after analyzing and studying on the situation about bursting of boiler pipe of11boiler of Shantou, Taicang, and Changshu supercritical unit. In28,Octobor,2006, the Chinese first ultra supercritical unit Huneng Yulin power plant through168h full load trial operation and entered commercial operation, by studying on four times bursting of boiler pipe during the unit starting, it prove that the key reason of debris blockage in boiler throttle coil can caused tube flow reduction and overpressure which finally lead to bursting of tube. The feature of design throttle coil in ultra supercritical unit is to balance the tube flow, if want to remove the kind of hazards, it must ensure clean inner tube and collecting box, which can make promotion to water quality and commissioning progress during commissioning and initial operation of the unit. Therefore, study on decontamination construction technology about1000MW ultra supercritical air-cooling and coal-fired unit, which can provide positive meaning for long period, safety and high efficency operation of the unit.In this paper, after deep studying on effective precaution measures to prevent bursting of boiler tube in decontamination construction technology during installation,commissioning and operation of the world’s first1000MW ultra supercritical air cooling and coal-fired units Huadian Ningxia Lingwu power plant project phase Ⅱ,it has found the key points of control precaution technical measures of decontamination construction technology of1000MW ultra supercritical air cooling and coal-fired units, which can provide the basis for the safety operation and reasonable maintenance of the unit, to ensure that the unit long period, safety and high efficency operation, and also has the high reference value in the same engineering construction.