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Vacuum
Technology in Manufacturing of Rotor Blades for Wind-Power-Generators
In the past, vacuum technology was not used on items as large and with such complicated geometries as wind blades. More recently, it has been found that using vacuum techniques reduced the emission of organic solvent styrene by 95%. Organic solvent styrene causes a number of short and long term health effects. In addition, research shows that using vacuum techniques in wind turbine blade manufacturing results in a better quality blade and lower production costs, leading to an increase in the production of wind energy.
Stages of Production
Resin
Degassing The pressure is maintained at approximately 100 mbar to degas the resin. Vacuum control is required for this step; otherwise the pressure could fall until the boiling point of the resin or resin components is reached. In such a case the pump would be saturated by solvent and resin and could be damaged. The recommended pump is a Sogevac equipped with an open gas ballast valve and GS555 oil.
The Infusion of two half blades Vacuum resin infusion is probably the most dominant processing method for manufacturing wind turbine blades. A vacuum is typically used to draw the mixed material into the mold. The system feeds the vacuum draw with mixed material. During the vacuum-assisted resin transfer molding (RTM) process, fiber reinforcements are placed into a mold, formed into shape, and resins are then applied to the fibers. Research shows that vacuum infusion technology is very effective when producing fiber reinforced polyester. The infusion consists of a migration of the
resin onto fibers also called an infusion mesh. The fibers are sandwiched
between two plastic layers. The
vacuum pump is used to evacuate the space in between the layers and to help
resin migrate though the fibers.
The
required vacuum for infusion is about 10 mbar.
Assembly of the 2 half blades and
baking of the blade The last step of blade production is to connect the two halves of the blade. For long blades, manufacturers use moulds equipped with hydraulic jacks. The final assembly and baking is done at approximately 10 mbar. Attention: High temperature gases come from the mould!
Vacuum
Pumps Used for Production Sogevac pumps are our recommendation for applications
relating to the windmill industry. They
have been found to be robust and extremely reliable for this technology. Single vacuum pumps
at each position or central vacuum systems are used, depending upon
manufacturing preference. Typical pump sizes
for composites applications range from 16 to 300 m³/h. We recommend using
the following accessories to protect the pumps and extend the maintenance
periods: ·
Liquid separator (to stop resin drops from entering the pump) ·
Active charcoal inlet filter (to trap as much solvent as possible) ·
Polyester cartridge inlet filter (to trap charcoal particles from
the first filter) The pumps should to
be equipped with: ·
Manual gas-ballast valve permanently open ·
Oil GS555 / FKM seals ·
No oil filter – there is a risk that it will be clogged by resins
or solvents The pump should have
the maximum oil capacity, so we recommend a standard SV16 (2 l oil capacity)
instead of SV16B (0.5 l). The same is valid for SV25 (instead of SV25B). |
Vacuum Products Canada Inc. www.vpcinc.ca
1-800-269-6030 reachus@vpcinc.ca |
