AKAS: Automatic Knife Advance System for Precoat Filters
For all precoat knife discharge rotary drum vacuum filters (RDVFs) it is important that the knife advance system operates accurately and steadily so that the optimum usage of precoat material on the precoat filter can be attained.
This latest design of knife discharge system has been developed by Filtration Services following many years of practical experience with earlier mechanical, hydraulic and electro-mechanical assemblies. All Filtration Services precoat filters benefit from this unique AKAS System. But, you don’t need to buy a new machine to benefit from this unique knife advance system. We can adapt it to suit most existing precoat filter assemblies (e.g. Stockdale, Paxman, Dorr-Oliver, Eimco etc) and install it on site.
Filtration Services Ltd utilise the latest design and engineering techniques to provide high quality solutions for all areas of the filtration industry.
Background – The Development Of AKAS
A high advance rate causes the knife to remove too much of the precoat bed as well as the surface filter cake on the precoat filter; this is wasteful of precoat material and reduces the overall filtration cycle time unnecessarily. Too slow an advance, and the surface filter cake layer does not get fully removed, the precoat surface is not refreshed and the overall filtration rate and, therefore, throughput decreases rapidly.
With increasing pressure on processing plants to improve efficiency and reduce wastage, Filtration Services Ltd has developed a precoat filter knife system that regulates the rate of knife advancement to the speed of rotation of the drum.
This ensures that the knife advances synchronously with the rotation of the drum and removes an even thickness of filter cake at all times.
How Does It Work?
An electronic pulse is received by the AKAS panel on each complete drum rotation. This initiates the ‘advance’ signal to the knife drive stepper motor. Any variation in drum speed, due to changes in material filterability or desired throughput is monitored. The knife remains synchronous to the drum.
The Knife Advance Control Panel Incorporates A Touch-Screen HMI With The Following Features:
- Easy knife advance / retract operation
- Simple commissioning
- Numerical and graphical display of the position of the precoat knife relative to the drum
- Easy configuration of the knife advance rate (in increments of 5 microns per drum revlolution)
- Knife advance delay option (of 2 to 10 drum revolutions)
- Forward and reverse limit alarms
- Motor frequency tuning facility
- Graphical and numerical diaplay of precoat thickness
- PIN number ‘lock’ facility to prevent unauthorised changes to settings
- 4 recipe options available so that settings can be adjusted at the press of a button.
The maximum knife travel is governed by ‘forward stop’ and ‘reverse stop’ limit switches which are interlinked through the control panel. The control panel can be located close to the precoat filter (RDVF) or operated remotely if preferred.