Technical Information

Steam Turbines

Mitsubishi Power has developed various highly efficient and highly reliable in-house technologies for its steam turbine lineup.

High-efficiency Blades

By combining various technologies, such as blade profile design optimization using 3D software, we are able to reduce secondary flow and friction losses. We also optimize the steam flow path based on steam conditions, allowing a highly efficient flow path customized for each steam turbine. Integral Shroud Blade(ISB) and Continuous Cover Blade (CCB) are used in the low pressure section. The blade root, blade profile and shroud are designed as a single body, thus allowing easier assembly. During operation, the blades come into contact with each other, greatly increasing vibration damping and reducing blade tip leakage losses, resulting in higher efficiency and reliability.

Welded Rotors

Welded rotors are manufactured using high creep strength material in the high temperature region, and high toughness material in the low temperature region. These two materials are welded into a single rotor for use in high/low-pressure single rotor turbines. We have extensive experience in the use of this welding technology to manufacture highly reliable rotors for steam turbines, and the technology will also be practical in the development of rotors for 700°C class turbines in the future.

Sealing Technology

We have different types of cutting-edge sealing technologies, such as abradable seals, leaf seals, ACC (active clearance control) seals, and others. These sealing technologies are applied according to the turbine design requirements, help to minimize steam leakage losses, and improve turbine efficiency by minimizing the clearance between the stator and rotor.

High-temperature Technology

To increase power generation efficiency, we have been investing in R&D to develop turbines that can operate at higher temperature steam conditions. Materials designed for high temperature usage have been developed by us and are used in components, such as the rotor, casing, and main valves. We have already manufactured and successfully commissioned several steam turbines that operate at 600/620°C and are among the industry leaders for high temperature technology development. Currently, we are striving to develop the next generation of A-USC (advanced ultra super critical) steam turbines that can operate in the 700°C range and have been investing in R&D to develop high temperature-resistant Ni-based alloys and welded rotors using Ni-based alloys.
A-USC steam turbine technology is based on the 600°C class USC technology and is developed as a national project in Japan to allow inlet steam conditions above 700°C and employ two (2) stages of reheating so as to achieve a target plant net efficiency (HHV) of more than 46%. Knowledge gained from the development of A-USC technology will also be used to raise operating temperatures and efficiencies in GTCC bottoming cycles.

Exhaust Direction and Arrangement

We will propose the most suitable turbine arrangement by considering the restrictions of the site and the customer' s requirements.
Turbine exhaust can be designed for axial, downwards, sideways or upwards ^*1 directions.
For GTCC plants, steam turbines for C-G-S ^*2 and C-S-G ^*3 power trains can also be designed.
In the case of a C-G-S power train, the use of a clutch between the generator and turbine can reduce the required capacity of the auxiliary boiler for start-up.

Upward exhaust is available for small/mid-sized turbines used in geothermal power plants,etc.
C-G-S power train: Gas turbine (C) - Generator (G) - Steam turbine (S) in single shaft arrangement.
C-S-G power train: Gas turbine (C) - Steam turbine (S) - Generator (G) in single shaft arrangement.

In-house Test Facilities

We have fullyequipped in-house test facilities to carry out inspections and tests for steam turbines (ex. full-scale land down-scale low pressure rotor test facilities, high speed balance test facility, GTCC in-house plant test facility,etc.), and verify newly developed technologies. Results from the tests are analyzed and reflected back into the design process to ensure the quality and reliability of steam turbines that we supply.

Operability

We are able to meet a range of customer plant operation requirements, such as pure sliding pressure operations and compound fixed/sliding pressure operations.
We also study the possibility of reducing the minimum load, reducing start-up time, and increasing the load ramp rate so as to provide a turbine with the optimal operating range for the customer' s plant requirements.
Upon the customer' s request, the turbine operation can be remotely monitored 24 hours a day, and immediate assistance can also be provided in the event of any trouble occurring during operation.
In addition, we are also pushing ahead with the development of next generation IoT technology for remote and autonomous monitoring of plant equipment, which will allow plant engineers to analyze and detect anomalies at an early stage. Through the use of such technology, time intervals between regular inspections and plant availability can be increased.