What does Dust coating W?
The preconditioning acts as a layer between filter media fibres and dust cake. It prevents the dust particles from adhering onto and/or penetrating into the structure of the filter media and clogging it.
It operates as a „lubricant“ between the dust particles to avoid encrusting of the dust cake and enables sufficient regeneration of the filter media.
It reduces the pore size of the filter media and avoids the dust particles to bleed through. Dust coating W removes the filtration from the depth of the filter media to the preconditioned fibre surface.
How to apply Dust coating W?
First of all the extraction system with unused filter elements will be started with clean air without dust (ideal
filtration velocity < 60m3/m2/hr.). The system will be adjusted to the nominal air volume and the actual pressure drop will be measured (approx. 100 Pa).
Now Dust coating W is fed into the air stream (approx. 5-10 gr./m² filter area) whilst the pulse-jet cleaning system is turned off. The pressure drop must be kept under control and should raise to approx- 350 – 800 Pa. at nominal air volume, depending on the final operational pressure drop allowable for the installation. For extraction systems with unfavourable and uneven distribution of the air flow we recommend to apply more Dust coating W in order to make sure that the whole filter area will be covered properly.
Now the dust can be fed to the system. The extraction system should run without pulse-jet-cleaning until a pressure drop of approx. 1600 Pa is reached.
Whilst the pulse-jet-cleaning starts you have to make sure it operates with lowest possible pressure.
The cleaning system should be adjusted in order to keep the pressure drop always above 1000 Pa. In order to maintain this pressure drop even at different dust loads it is recommended to operate the cleaning system by a „Delta-P Control“ (cleaning on demand).
If all these precautions are fulfilled it can be expected, that the preconditioning with Dust coating W must be carried out only once during the commissioning of the system.
What else must be considered?
Unfavourable factors like too high a/c-ratios
- bad design of the dust hopper / bin
- uneven distribution of the cleaning energy might create higher pressure drops.
This can be compensated by actions like:
- carry out the preconditioning-process again after a certain
- additional pulse jet cleaning while the van is turned off (off-line cleaning)