Research And Analysis On Application Of Blandon Steam Seal In 300mw Steam Turbine

The steam seal used between dynamic and stable parts in steam turbine is a vital component that influences turbine's safe and economical operation. In power plant, the traditional steam seal applied in the turbine flow path system is of backstay-spring comb-finger structure, which mainly used to control the leakage flow. With the damp produced through multilevel throttling expansion works, the leakage of working fluid reduced. But the traditional steam seal has flowing disadvantages: backstay-spring easily works down, comb-finger easily abrades, the aperture between dynamic and stable parts after abrasion always spreads, leakage flow increases and unit efficiency falls. Meanwhile, slice easily destroys the surface of rotation shaft, and induces a perpetuity bend that occurs on the friction part of rotation shaft because of over heated, finally a huge accident happens. So it's neither safe nor economical.Seeking more reasonable and excellent steam seal is always the goal of domestic and oversea turbine specialists. Recent years, several steam seals that exceed traditional backstay-spring comb-finger structure have been invented, for example, adjusted steam seal designed by U.S. Blandon company; alveolate steam seal by Dongfang steam turbine factory; Wangchangchun-touched steam seal by Haerbin steam turbine factory , All these steam seals are gradually applied in the technical reformation of various turbines, which greatly improve the safe and economical effects. Thanks to this, all power plants get great economical advantages.The abrasion of the traditional backstay-spring steam seal of NO.4 steam turbine in Daba power plant brought on following problems: First, the abrasion of the steam seal made the lubricant mixed with water; Second, the abrasion made the libration of the shafting augment; Third, the leakage of the steam made the heat consumption augment; Last, the steam seal replaced affected the safe and economic efficiency of the unit. The text analyzes the problems hereinbefore, and demonstrates the feasibility that using Brandon steam seal replacing the traditional steal seal .The text also brings forward the scheme of the steam seal improving, and makes the calculation and the estimation.The results of rebuilding the structure of the steam seal are showed in the following aspects: the libration situation happening in the unit's startup course becomes better obviously, the phenomena that water exists in the turbine lubricant disappear, which improves the operation security of the unit. When unit runs with 300MW load, the...