Couch Roll Double Doctor
Dedicated double doctor effectively removes surface water and debris build-up on the couch roll.
Features/Benefits
- Fewer streaks
- Fewer paper breaks
- Fewer holes
- Fewer cracked edges
- Reduced moisture to the press nip
- Improved couch efficiency
- Reduced maintenance
- Uniform moisture profile
- Increased vacuum box life
- Reduced maintenance
Proven Results
- Reduces water streaks 50%
- Reduces paper breaks 50%
- Removes surface water and build-up of fines and fillers
- Vacuum-effect extracts debris from couch roll holes
An Innovative Solution to an Age-Old Problem
Forget about the traditional rubber wipe used to remove water from the couch roll after the nip. As most papermakers can attest, the rubber wipe does not remove all the surface water, which leaves a seal or surface tension on the couch roll surface, trapping the fines and fillers in the holes of the roll. Kadant Web Systems' engineering team approached this age-old problem from a new perspective, and developed a truly effective solution. The Kadant Web Systems Couch Roll Double Doctor provides a two-phased approach to the problem. First, it removes the initial layer of surface water, creating a vacuum on the underside of the blade. This vacuum extracts the debris and fillers from the couch roll holes, bringing them to the surface. Then, the second doctor removes the remaining surface water, fines and fillers, sending a clean roll back to the nip.
It takes Two Doctors to Effectively Clean the Roll
The Couch Roll Double Doctor is a system that uses a DST doctor in both the first and second position. It is designed to fit within the confines of any couch roll, including arrangements where the wire returns under the roll. The DST doctors provide precise blade-to-roll fit using pneumatic pressure. The conforming of the blade to the roll effectively removes the majority of surface water in the first doctor position and cleans the fines, fillers and remaining surface water in the second position. The support for the primary doctor is designed to allow the fines, fillers and surface water, which are removed by the second blade, to pass through the doctor back and travel down into the save-all pan. The DST doctors can be independently adjusted for correct blade contact which, in conjunction with the ability of the doctors to conform to varying roll conditions, leads to increased blade life, and reduced downtime for blade changes. With both doctors, loading pressure is adjusted through pressure-regulating valves in an independent control station.