Bharat Heavy Electricals (BHEL) is setting up a facility to assess low cycle fatigue effects in rotors required for coal-based thermal power plants.
With this, India may soon manufacture its own super alloy steam turbine rotors for efficient coal-based thermal power plants.
Improving technologies to increase efficiency of coal-based thermal power plants requires use of nickel-based super alloy materials as against chrome-based steels widely used now.
The nickel-based alloy 617M has been selected by the Indian Advanced Ultra Super Critical (AUSC) consortium.
The lack of experimental data on performance of alloy 617M rotors hinders effective usage of this alloy in the Indian AUSC power plant. To overcome this challenge, the Department of Science & Technology under Clean Energy Research Initiative has supported a project to BHEL (R&D), Hyderabad for establishment of High Temperature Spin Test Rig (HTSTR).
It will be the first facility in the country for experimental validation of the design of AUSC steam turbine rotor relating to creep-fatigue damage (deterioration of metals and alloys subjected to a cyclic thermo mechanical load at elevated temperature) and will also be the only one-of-its-kind in India in terms of establishing a real size engineering experimental set-up.
It will subject the turbine rotor segments of weight up to 9,000 kg to various damage conditions similar to that in the plant operation, like high temperatures up to 800 degree celsius, high speed up to 3,600 revolutions per minute, followed by long term steady state operation and controlled heating and cooling.
The facility will enable design validation of 800 MW AUSC steam turbine rotors for certifying the long term performance of super alloy monometallic and bimetallic welded rotor with a total of 2,000 startups (hot+warm+cold) and 1,00,000 hours of total steady state operation. This is achieved through accelerated testing within 200 cycles and 10,000 hours respectively.
A unique test protocol for accelerated testing is formulated by the BHEL team with guidelines of ASME standards. Two rotor segments – monometallic (alloy 617M) and bimetallic welded portions (alloy 617M and 10 chrome) of actual steam turbine rotor -- will be subjected to equivalent operating conditions over its guaranteed timeline by increasing temperatures and achieving desired thermal gradients within the rotors during the heating and cooling operations.
The test protocol and its visualisation software are registered under the Indian Patents and Copyrights Act.
