Coperion GmbH recently supplied and commissioned a wear-protected rotary valve for the RWE Power AG Ville/Berrenrath coal refinery.
The rotary valve type ZXQ has a diameter of 600 mm, and feeds dry lignite into a pneumatic conveying system that transports the material from a new vertical roll mill to the storage silos. The conveying pressure of the system is between 0.9 and 1.1 bar. The rotary valve is designed for a capacity of 60 tph, however a peak performance of approximately 80 tph has been recorded.
Advantages of a rotary valve over screw pumps normally used for feeding include:
- The rotary valve does not constitute a potential source of ignition, as the circumferential speed at normal operating rate is below 1 m/sec.
- The valve is available in a flame resistant version.
- Electrical power savings are possible with a lower operating power requirement of 4 kW compared to approximately 100 kW in the previous system.
- Simple maintenance and long maintenance intervals reduce operating costs further.
- Due to its lightweight design and low operating speeds, the valve only requires a simple compact foundation.
- Lower noise emissions.
- The tightness of the valve makes it suitable for ‘light’, fluidized products such as dry lignite with bulk densities lower than 600 kg/m3, because sealing is achieved by precise gap dimensions.
- The tightness is also equally effective in partial and full load operation, meaning that start up of the mill can be controlled without the problems that previously occurred with insufficient sealing in partial load operation using a screw pump.
The rotary valve includes effective wear protection that safeguards the long-term performance of the valve. Gap and leakage gas flow rates are guaranteed even when temperatures fluctuate. An optimal geometric design is provided to achieve the high filling and emptying levels required by the user for ‘light’ bulk materials that may fluidize with a fluctuating conveying pressure.
Adapted from press release by Katie Woodward
Read the article online at: https://www.worldcoal.com/handling/18112013/coperion_supply_rotary_valve_268/