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Steam Turbine Construction |
We offer Steam Turbines in various advanced constructions keeping in mind the constant changing market requirements and customer’s preferences. These Industrial Steam Turbines are available in following features:
Turbine Casing - The turbine casings are horizontally split at centre line and this facilitates easy assembly, maintenance and replacement of parts. Proper tightness of the mating surfaces is ensured through high-accuracy finish and using metal-to-metal contact with a sealing compound.
Turbine Rotor - The design approach uses a rotor which is integral to the shaft and supported on both ends. The fully-assembled rotor is dynamically balanced. The thrust bearing and emergency over-speed governor are provided on the non-drive end of the rotor shaft. The thrust collar is integral to the rotor shaft.
Governor Valve - The smaller units have options of single or multi-inlet (usually three) governing valves. However, larger units are provided with multi-inlet valves, as standard feature, which offer better part-load characteristics.
Stop and Emergency Valve - The stop-and-emergency valve is fail-safe and is hydraulically-operated with high-pressure oil supplied from control oil-system of the unit.
Radial Bearings - The radial bearings are generally white-metal-lined sleeve-bearings with horizontal split for low-speed operations. For high-speed operation larger units, tilting pad-type bearings are used.
Thrust Bearing - A thrust bearing of tilting pad-type with standard design is fitted on non-drive end of rotor shaft. The thrust bearing has equal thrust capacity in both axial directions.
Speed Reduction Gear - Speed-reducing gear is generally mounted on turbine base-plate. The high-speed gears are precision-machined, hardened and ground to achieve long operating-life. Lubricating oil from the lubricating oil system is used for cooling the gears. The main oil-pump is mounted on the free end of the low-speed gear.
Blades - The blades are made of alloy steel of X22CrMoV121 for steam temperature exceeding 300 Deg. C (suitable up to 550 Deg. C) or X20Cr13 for steam temperature lower than 300 Deg. C. Generally, ‘’T‘’ types of blades with shroud plate fitted to the periphery of the blades, which are used to provide sealing and imparting additional strength. For larger blades like in low-pressure condensing stages, damping wire is provided. Special care is given to the stress analysis.
Nozzles - Nozzles are manufactured from stainless steel. The first-stage nozzles are fixed into groove in the casing/nozzle chest and welded (for high-pressure applications). The nozzles for subsequent stages are fitted/welded into diaphragms, which are then fixed into grooves located between the stages. These diaphragms split near the horizontal centre-line, for easy removal and maintenance.
Gland Seals - The gland seals generally used are metallic labyrinth-packing for external gland-seals (where rotor comes out of the casings) as well as for inter-stage gland-seals. The length of external labyrinth-packing depends upon the level of turbine exhaust-pressure.
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