Wind energy is a new, emerging green energy source holding great importance for its natural availability and non-polluting behaviour. India is fifth in wind power generation capacity after USA, China, Germany and Spain, and has generated 16,000MW from a total of 2,41,000MW of power generated globally in 2011. Premier’s Engineering Division started its 3,000 sq. metre windmill tower manufacturing unit in March 2012 with exclusive, state-of-the-art facilities of world-class columns and booms, rotators, SAW (Submerged Arc Welding) machines, flange facer, easy laser, etc. At present, the wind turbine towers have been developed for smaller capacities of the wind turbines and are now being geared up to manufacture bigger capacity wind turbine towers. Here is a look at the salient features of this project.
CNC Profile Gas Cutting Machine: CNC operated 18 m x 4 m-sized profile cutting machine with two oxy-fuel cutting nozzles.
Cone-Bending Machine: Three-roll, pyramid type, conebending machine being used for plate bending of various thicknesses.
Column and Booms: Having a 4.5 m horizontal and 2.5 m vertical stroke, these column and booms in a total of five work stations are used for semi automation with the best in the world SAW machines made by Lincoln.
Rotators and Idlers: Customised to requirements, heavy capacity rotators with idlers having a wide range of variety, such as long-seam welding, fit-up, blasting and painting, are used.
Flange Facer: Specially designed and manufactured online machining solution facility (flange facer), with hydraulically operated, two-point cutting tools for flange machining of a concrete tower, which maintain very close tolerances.
Easy Laser: An ultra modern laser measuring equipment, with the capacity to check geometrical parameters over 40 m, is used for checking flatness of end flanges.
Blasting Booth: 15 m x 7 m x 5 m-sized blasting booth solely dedicated for the tower.
Painting Booth: 15 m x 8 m x 6 m-sized painting booth having the capacity to paint two towers, 11 metres in length, at the same time.
Worldwide installations of wind energy generating capacity have now reached a total of 2,41,029 MW on average, enough to produce an annual output of more than 4,73,880 billion kW (473.9 Tera Watts) per hour of power, meeting 2.3% of the global electricity demand. The global wind market produced a record-breaking number of installations this year.
In-house Cone-Bending Facility
Brand-new, three-roll, pyramid-type bending machine has been exclusively installed in the tower bay for manufacturing cones of high quality.
Online Machining Solution
A flange facer is used exclusively for on-site machining of flanges in tower manufacturing for maintaining parallelism, face-out and, most importantly, flatness. Easy to handle and transport, the flange facer gets fitted on the tower with the help of hydraulic jacks. Two single-point cutters provided on the arm of the flange facer reduce the cycle time of machining to almost 50%. The finishing observed is similar to that of the machined
surface from the vertical turning lathe.
One-of-its-kind Blasting and Painting Booth
Exclusively customised blasting booth of size 15m x 7m x 5m and painting booth of size 15m x 8m x 6m are a few of the highlights of the tower project. Unlike other projects, the tower is not moved inside the blasting and painting booth on trolleys but motorised PVC-coated rotators, specially procured for blasting and painting, are used for easy handling as well as blasting booth to paint booth line movement.
Tight Check on Quality at Each Stage
At present, the tower is the only product and the longest one, which employs all NDT (Non- Destructive Testing) methods such as DP, MPT, UT and RT. With a complete third-party involvement requirement, in addition to the necessity of quality checks done by the customer, tower manufacturing is a critical and time-consuming procedure. Yet, the Engineering Division has achieved an accuracy level even greater than that mentioned in the customer’s quality plan.
Critical Fitting of Internal Parts
Considering the criticality and importance of the tower in wind turbines, all internal parts that play a major role in the performance of the windmill are fitted before dispatch on the Premier premises. This not only involves the fitting of internal parts but also involves welding 'n' number of bushes of different sizes, creating platforms and strengthening rings, which are more than 11 m in length and inspections such as DP and MPT, which are required for fitting these internal parts.
The accuracies in the tower depend on highly skilled technicians. The straightness for 11 m is ± 2 mm, the flatness for 250 microns varies by 20 microns, face-out varies by ± 0.5, concentricity varies by ± 0.5 and chambering varies within ± 2 mm.
Team ED understands operational difficulties, analyses the problem and comes up with the best-fit solution before any shutdowns or lags in the process occur. Besides employing people in the tower bay who have prior experience, continual developments are also being made such as introducing a multi-point contact spider for controlling cone ovality, adding stage machining to control flatness and introducing a sequential welding method to control distortion.
In India, Tamil Nadu, Maharashtra, Rajasthan and Gujarat are the states where maximum numbers of windmill towers have been installed in the last 10 years. This is expected to lead to a capacity of 52,000 MW by 2020.
Considering the increase of 15% that has happened in the last 10 years, the total windmill manufacturing business is forecasted to increase by 22% in the future.