Ansaldo Energia has 100 years’ experience in the design, manufacturing and installation of steam turbines. It has supplied about 700 steam turbines worldwide with a total capacity of nearly 100 GW. Dedicated R&D and Service organizations assist Clients with continuous product improvements, combined with the traditional reliability and robustness of Ansaldo Energia products: the result is a unique and balanced value package based on innovation and reliability. Ansaldo Energia has a comprehensive portfolio of 50 Hz and 60 Hz non-reheat and reheat steam turbines ranging from 40 MW to 1000 MW for conventional steam cycles, combined cycles and cogeneration applications. In addition Ansaldo Energia offers a complete line of geothermal steam turbines from 20 MW to 150 MW.
Ansaldo Energia steam turbines are based on a modular concept to reduce technical risk and manufacturing time and ensure high reliability. Each model is a combination of well-proven, pre-engineered modules of different sizes, to provide a broad range of power ratings and applications. Several different material options are available to meet different steam conditions up to the most advanced ultra supercritical parameters (600°C/620°C).
Over the years of its technological history, Ansaldo Energia has designed both impulse and reaction steam turbines.
Today Ansaldo Energia steam turbines are based on reaction technology, while the impulse design is maintained in geothermal and small-size steam turbines.
All blades have 3D airfoil design to maximize stage efficiency, achieving 92% of efficiency in the HP section and 94% in the IP section.
The development of longer last stage blades is one of the most effective solutions to achieve a compact and a highly efficient turbine design.
A family of modern last stage blades up to 48” is available, with free standing or coupled solution, to satisfy any cooling condition and back pressure requirements.
Generally, Ansaldo Energia steam turbines for reheat applications have separate HP, IP and LP sections to deliver the highest possible sustained efficiency and good thermal flexibility.
For output up to 350 MW, a compact, combined, single flow IP/LP solution is available, thanks also to the use of the welding technique used for the IP/LP rotor.
The HP inner casing of reheat turbines has a shrink ring design that does not require any massive horizontal flange. The shrink rings hold the two half inner casings together to form a symmetrical, light geometry with uniform mass distribution. They are assembled or removed by heating them with annular gas burners.
The advantages of this solution are:
In addition to the traditional downward exhausts for single and double flow configurations, low pressure modules are available for single flow axial exhaust or double flow side exhaust to the condenser.
Axial and side exhaust modules, developed primarily for combined cycle applications, allow installation of the turboset on low foundations, minimising overall foundation costs and reducing the overall height of the machine building.
Ansaldo Energia uses the welding technique for rotor manufacturing, in which the rotors are built from forged disks and welded together using a combination of tungsten inert gas and submerged arc processes in a dedicated rotor welding shop.
This technique allows the use of different materials for HP, IP and IP/LP rotors, providing high temperature resistance at the hot end and high toughness at the cold end, and allowing large LP rotors to be manufactured from smaller forgings.
Moreover welded rotors have better thermal flexibility, which is a significant advantage for startup, shut-down and load changes.
Today’s medium and large power generation steam turbines are mainly reheat type with regenerative feed water cycle and possible district heating applications.
Ansaldo Energia offers three steam turbine models, specifically designed to satisfy all possible Client requirements in terms of operating conditions, performance and reliability, including steam turbines for ultra supercritical applications.
Steam turbines for reheat and non-reheat combined cycles must be easy to adapt to different gas turbine configurations (number and models) and steam conditions delivered by various heat recovery steam generators. Ansaldo Energia offers four steam turbine models able to meet the full range of Client requirements and all specific site conditions.
These turbines, either back pressure or condensing, with or without controlled extractions, are used in industrial, desalination and district heating power plants. As it is basically the process that dictates the steam parameters and therefore the turbine design, each cogeneration steam turbine is a unique product, tailored to the specific needs of the Client.
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