In all wind turbines with hydraulic pitch systems, accumulators are an integrated part of the system as power backup for pitching as well as stopping the turbine. To keep these in shape the precharge pressure of the nitrogen needs to be controlled and recharged if necessary at the scheduled service visits to the turbine.
The way it is done today may generate several issues and frustrations, such as:
- The risk of a standard commercial nitrogen bottle in the hub or nacelle tipping over
- Inaccurate precharge pressure if the recharging is done too fast
- The need to bring more than one nitrogen bottle to the turbine, spending time craning up and down the bottles
- You typically end up returning up to half the gas to your supplier
- It typically takes two service technicians to operate the precharging of the accumulators
Safe and fast O&M with nitrogen precharging by N2B system
Fritz Schur Energy‘s new invention N2B System for precharging hydraulic accumulators is designed to face all these challenges combining a higher degree of safety with less time spent on O&M and better utilization of the gas reserve.
The N2B system consists of a Stationary Booster Unit and the Mobile Top-Up Unit as well as an optional Extender, all of which eases the service for the technicians.
Mobility and safety
The mobile top-up unit is safe to operate - and can be operated by only one person! The pressure bottle is protected in a case able to lie flat on the floor. You only have to enter the desired precharge pressure, and once the equipment is connected to the accumulator the process will continue automatically until the target pressure is reached. The speed of precharging is controlled minimizing the thermal effect and ensuring a more accurate precharge pressure.
Mobile top up unit
The mobile top up unit comes in a hard suitcase offering full protection during craning and use in the nacelle. This is the only equipment necessary for the service engineer when topping up the accumulators. By optional adapters the Mobile Unit can be connected to any type of hydraulic accumulator.
- Mobile equipment - to be used in the turbine topping up the precharge pressure of accumulators
- High-pressure gas vessel in shape of a light weight suitcase
- Easy handling
- Capacity of 300 bar/6,8 litres
Stationary booster unit
The Stationary Booster Unit connects to any size and shape commercial steel bottle. This bottle is the supply unit for the Booster unit, which primary function is to pressurize the mobile top-up unit to 300 bar. The stationary unit and thus the charging procedure is intended to take place in the workshop.
- Stationary equipment - located in service workshop
- Distribution hub of nitrogen from large bottle reservoir to mobile top-up unit
- Capable of emptying reservoir bottles down to 15 bar
- Boosting the pressure on mobile top-up unit to 300 bar
Using the N2B has made it much more effective and safer to fill the accumulators in the turbines. We are very satisfied with the solution from Fritz Schur Energy.