Variable Area Rope Breaker

The VARB™ is a non-intrusive passive device designed to break a pulverized fuel rope. The resultant homogenized flow into a splitter results in equalized distribution to all burners. The VARB is used to break ropes ahead of 2 way, 3 way or 4 way splits.


Key Benefits

The purpose of a Greenbank VARB device is to break the rope (the tight formation of coal dust in air) and diffuse the PF which is a common condition when transporting coal from mills to burners. This is particularly useful for many older power stations which often have one or two large pipes coming from the mill that split to deliver fuel to 6 or 8 burners. Due to rope formation, coal does not split as equally as the air at these pipe junctions, which results in poor fuel to air distribution.

By applying the Greenbank Customized VARB™ System the client can correct and optimize performance of low NOx burners via their fuel / air diet. Also with improved fuel flow you can enhance combustion efficiency burning more carbon and by design reduce unwanted emissions. In summary the Greenbank VARB system offers massive potential in the enhancement and performance improvement on front wall boilers that experience poor combustion.


Further tangible benefits which could also be gained using Greenbank's Coal Flow Balancing Technologies are:

Higher Combustion Efficiency

  • Stable Combustion Process
  • Reduction in flame length
  • Elimination of flame detachment occurrences.
  • Reduced pipe erosion.

Reduced Carbon-in-Ash

  • Reduction of wasted coal / energy
  • Salable ash
  • Reduction of disposal and land fill waste

Reduction of NOx

  • A function made possible by lowering secondary air levels under stable operating conditions.
  • Minimum (but safe) Transport Velocity
  • Reduction in volume of air required
  • Reduction of pressure of air required
  • Removal of Riffles
  • Potential higher coal throughput per mill.

Improved Fineness of PF particles

  • Up to 7% improvement expected passing 75µ.
  • Further reduction in erosion in PF pipes

The combination of accurate on-line measurement and good distribution at splitters will enable the station engineers to maximize the benefits listed above.

Types of VARBs™

OPG's H-VARBH-VARB on Mill 2AThere are two main VARB products, the VARB and the H-VARB. A third, S-VARB [Special VARB], has been designed for dealing with more aggressive spinning or rotating flows after bends in the vertical plane or on slight inclines. The VARB [Standard VARB] is designed for spinning or rotating flows after bends in the vertical. The H-VARB or Horizontal VARB is designed primarily for horizontal pipes and involved with lifting PF off the bottom of pipes.