Turbine erection in India
By Partha Pratim Basistha15 January 2018
Competition is becoming severe in India’s wind power sector. It has necessitated deployment of newer cranes and advanced transportation solutions with higher levels of efficiency and reliability for faster and safer completion of wind power projects.
Suzlon India’s wind power project at picturesque Agar in Madhya Pradesh, Central India, is one of those sites.
Suzlon India is developing a 29.4 MW wind power project on a greenfield site at Agar. The client is Indian state-owned oil upstream major Oil India. Its venture into the wind power business is a nascent part of its business diversification programme.
The company now wants to reap profits fast before the power tariff rates dive further through rapid commissioning of the projects. Oil India selected Suzlon India to erect twelve turbines each of 120 metres hub height. Each tower has a power generation capacity of 2.1 MW. There are plans to erect ten more towers adding upto 20 MW.
Speaking to International Cranes and Specialized Transport, Rahul Patil, site in charge at Suzlon India on the Agar wind power project, says, “As project completion schedule is very tight, our prime objective is to have higher availability of equipments for minimal project downtime. We are ensuring this through specialized project vendors having the right equipment, delivering higher productivity.”
Suzlon India hired Mumbai-based heavy lift specialist Amrik Singh & Sons to lift the tower sections, turbines and blades. Amrik Singh is executing the job using a brand new 650 tonne capacity Sany SCC 6500A lattice boom crawler crane at the Agar site.
At the time of ICST’s visit the fifth tower under the package was being erected. The crane was acquired in February 2017 and prior to Agar, it worked at Ambauchawas site nearby, erecting four towers with similar hub heights.
“Another Sany SCC6500A, belonging to Amrik Singh, acquired in April 2017, has been brought to Agar from Inox India’s wind power project site nearby,” informs Manish Sharma, senior service manager at Sany India.
Sharing an overview of the crane configurations for the Agar tower erection work, Jasbir Singh, operator of the SCC 6500A engaged in erecting the fifth tower, says, “The parts of the wind mill tower are heavy for the higher hub heights involved. Further, the job has to be carried with very high levels of precision with higher equipment availability. This is given the high wind speeds in the area of 6 metres per second. Based on these factors, we have looked to position the crane with the right boom and supporting configurations.”
The main boom configuration has been kept at 126 m plus a 12 m fixed jib @ 15 degrees for nacelle erection. The boom configuration has been kept the same for erecting the various sections of the towers. The counterweight was kept at 200 tonnes while the super lift counterweight is at 150 tonnes for boom-up. The derrick boom was kept at 36 m. Reeving was sixteen falls of 28 mm rope for the derrick boom. On the main hoist six falls were used in the main boom with each fall at 16 tonnes. The hook weight was 150 tonnes.
In this crane configuration the SCC 6500A was lifting the four steel fabricated sections of the bottom of the tower onto the concrete foundation. Each of these bottom sections weighed 47.6 tonnes. Next were the three intermediate sections at 45.7 tonnes each. This was followed by erection of two 19 tonne intermediate sections.
After that a 37 tonne intermediate shell section was placed on the 19 tonne intermediate section. This was followed by erection of another two 29.1 tonne intermediate shell sections.
When it came to the nacelle, at 80 tonnes, it was one of the heaviest in the world, according to Suzlon. Working radius when lifting the nacelle was kept between 19 and 20 m.
Following that the crane lifted the 18 tonne rotor hub with its three 8 tonne and 47.5 m-long blades to make a 97 m diameter rotor star. For the rotor hub erection the lifting radius was kept to a maximum of 22 m and it was performed in a single lift.
Transportation and safety
The blades were taken to the site from the base project depot on Goldhofer extendable trailers. Extensive route surveys had to be carried out to do this. Telescopic trailers were chosen for the transportation because of the many curves in the road from Suzlon’s plants to the base depot and then further on to the project site.
Commenting on the job, Rahul says, “The cost of hiring a telescopic trailer is less per blade transportation and the requirement for skilled manpower in the crew is also modest. The turning radius required at the wind farm sites is minimal. Further, the transit times required to deliver the blades are less when compared to mechanical trailers. Overall, extendable trailers come with many of the latest features, including steering axles.”
For safe project execution, very high levels of safety parameters were laid down for the main and the supporting cranes involved in the tower erection jobs. Suzlon appointed a third part agent to carry out health, safety and environmental checks on the cranes. In accordance with this, thorough inspection of the crane is being carried out to check the working of the safe load indicators, alarm systems etc.
The ability of the cranes to optimally perform at the permissible wind speed is also checked. Followed by the examination, a fitness certificate is given to the cranes. Operators with government approvals and valid licence are only allowed to operate the cranes working at wind power sites.