Efficiency of operation of a T-250/300–240 turbine without moving blades of last stages of the low-pressure cylinder

The results of detailed computations performed for actual electric and heat loads, pressure in the condenser, and other operating parameters are used to consider the changes in the efficiency of operation of a T-250/300–240 turbine after the removal of moving blades of the last stages of the low-pressure cylinder. It is shown that the expediency of running the turbine with removed blades should be determined proceeding from the expected modes of operation of the cogeneration plant in question for the whole year. __________ Translated from élektricheskie Stantsii, No. 11, November 2005, pp. 47–52.     

Calculating the thermally stressed state of the high and medium pressure rotors of a T-250/300-240 turbine in the labyrinth seal zone

The temperature and thermally stressed state of the high and medium pressure rotors of the T-250/300-240 district heating steam turbine are calculated, taking into account the concentration of stresses in the neighborhood of the thermal grooves in labyrinth seals. “Critical” zones in the turbine rotors, within which thermal stresses limit the rate of startup, are determined. Some practices for reducing the temperature stresses are suggested. __________ Translated from élektricheskie Stantsii, No. 1, pp. 32–37 (2008).     

Effect of Operating Conditions of a T-250/300-240 Turbine on the Level of Wetness in the Stages of the Low-Pressure Cylinder

The operation of the low-pressure turbine part in variable condensing and extraction regimes is analyzed. The effect of steam parameters at the inlet to the low-pressure part (in the lower extraction chamber) and of operation of the regulating stage of the LPP on the level of wetness in the low-pressure stages is determined. It is shown that the moving blades of the last stages of cogeneration turbines operate under heavier erosion conditions than in condensing turbines. This is one of the main causes of their intense erosion wear. __________ Translated from Elektricheskie Stantsii, No. 6, June 2005, pp. 27 – 32.     

Extending the time-to-overhaul of T-250/300-240 turbines built by the ural turbomotor plant and managed by Mosénergo

The paper discusses the condition of 19 turbines operated by the publicly owned joint-stock company Mosénergo, which have exhausted their time to overhaul (220,000 hours, 600 starts). An extension in the time-to-overhaul of all 19 turbines to 300,000 hours or 900 start ups with the condition that a number of mandatory measures be taken is an acknowledged possibility, based on calculations performed and analysis of damage sustained. A number measures, which have themselves been positively recommended for certain turbines, are examined, and a procedure is presented for evaluating the effectiveness of their implementation. __________ Translated from élektricheskie Stantsii, No. 6, pp. 4–8 (2006).     

Estimating the quality of metal in cast working blades made of the nickel alloy ChS88U-VI

Results are presented from a study of the metal in the working blades for a gas turbine power system made of the nickel alloy ChS88U-VI in its initial heat treated state. It is found that cooled working blades in the first and second stages meet the engineering requirements, while large uncooled blades in the third and fourth stages deviate from the specifications for a turbine system in terms of their macrostructure and mechanical properties. Translated from élektricheskie Stantsii, January 2009, No. 1, pp. 28–34.     

Erosion Wear Caused by Coarse Particles in the Flow-Through Part of the Medium-Pressure Stage of T-250/300-240 Turbines

The problem of erosion wear of the first stages of IPC-1 of T-250/300-240 turbines by solid particles is briefly described. It is shown that solid particles arriving at the flow-through part of intermediate-pressure cylinders form as a result of decomposition of an oxide film in the convective superheater piping of supercritical boilers. Fracture of the oxide film is intensified due to the temperature mode of the boiler and changes in the water chemistry. A general picture of wear of the flow-through part including guide and moving blades, shroud seals, and elements of the peripheral zone of the first intermediate-pressure stages by solid particles is presented. Wear of the flow-through part reduces the service life of the blading to two interrepair periods and substantially worsens the efficiency of operation of the intermediate-pressure part. The mechanism of motion of solid particles in the flow-through part is described and the ways to decrease the wear by removing solid particles from the hot reheat line, shutoff valves, and the first intermediate-pressure stage are considered. The latter method has been realized in the form of a protection system containing continuous or periodic double-loop blow. The first loop extracts a steam sample with solid particles from the steam-in box and the second loop removes solid particles from the increased blade clearance of the first stage into a separator-accumulator from which the cleaned steam is returned to the nearest extraction of the turbine. The operating experience of such a system confirms its expedience.