Filtration Services Ltd

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.

Tipping Pan Filter

Possibly one of the simplest filtration units used in industry today, the tipping pan filter is ideal for batch processing rapid-settling, fast-filtering crystalline suspensions. The tipping pan filter is ideal for small batch applications where dedicated equipment and batch integrity is essential.

The tipping pan filter is an open-topped vessel which is fitted with a false base, drainage grids and filter medium. The solid-liquid suspension is fed onto the surface of the pan and, at the same time, vacuum is applied to the base of the pan. The vacuum assists in dewatering the suspension thereby producing a filter cake on the filter medium.

The filtered liquid [filtrate] is collected from the base of the pan through a special valve assembly. The filter cake can be washed in the pan as many times as is required by the process to achieve the desired product purity. Once the washing stage has completed, the pan is inverted and the filter cake is discharged.

The unit can be enclosed (as below) and if required can be supplied with the vacuum pump and filtrate receiver. We have a small pilot-scale tipping pan available for hire (subject to availability).

Rotary Drum Vacuum Filter

The basic principle of the rotary drum vacuum filter has been around for over 100 years and is one of the oldest types of filters used for solid and liquid separation. The rotary drum vacuum filter is used for a number of different applications such as the filtration of bulk or fine chemicals, pharmaceuticals, pigments, foods, bulk minerals, sludge dewatering, wastewater treatment, and biofuels. The list is not exhaustive. The rotary drum vacuum filter is a versatile filter that is reliable, continuous and requires minimal operator effort/attention. It is also available in wide range of sizes and choices from lab and pilot scale to full production scale.

Filtration Services Ltd is at the forefront in the design and manufacture of rotary drum vacuum filters and has developed advancements which have improved efficiency and helped in reducing costs. One such advancement is the Automatic Knife Advance System (AKAS) which is used to optimise precoat usage on a rotary drum vacuum filter.

Filtration Services offer bespoke manufacture and design of the rotary drum vacuum filter to meet both your site-specific requirements and the exacting standards of today’s industry.

Rotary Drum Vacuum Filter – ROTAVAC™

The Filtration Services’ Rotavac™ rotary drum vacuum filter (RDVF) is particularly suited for applications where large amounts of liquids and solids need to be separated continuously and with minimal operator input.

The Rotavac™ rotary drum vacuum filter is available in a variety of sizes, from 0.8m² up to 60m² filtration area, and in a range of solids discharge configurations. A rotary drum vacuum filter operates continuously with the solids and liquid being discharged at steady, predictable rates. The units require little or no manual intervention, being simple to operate and maintain.

Rotavac One - Pilot Scale Filter Station

The Rotavac One is our complete, compact pilot scale filter station.

The Rotavac One comprises of:

• 1.3m² skid mounted rotary drum vacuum filter (RDVF)
• Filtrate receiver
• Filtrate pump
• Vacuum pump
• Blower (scraper discharge version only)
• Local control panel

With a small 2m x 1m footprint, the unit is easy to install and operate. The filter is ideal for small volume applications, process validation pilot-scale trials.

Two filter versions are available: Rotavac One S, scraper discharge and Rotavac One P, precoat discharge.

Scaper discharge filters are used where the solids being filtered form a good filter cake that discharges easily from the drum surface.

Precoat discharge are used, primarily, on applications where the liquid is the ‘product’ and the solids are gelatinous in nature.

• Stainless Steel Construction
• Pilot-Scale Trials
• Process Validation
• Small Volume Applications
• Quick and Easy Installation
• Complete Filtration Plant
• Easy Cleaning and Maintenence
• User Friendly and Simple to Operate

Rotavac Lab - Lab Scale Rotary Drum Vacuum Filter

The Rotavac Lab is our lab scale rotary drum vacuum filter. The Rotavac Lab scale filter is generally used for product evaluation tests, or as a preliminary step towards pilot scale and full scale equipment trials. The unit is a fully functional and representative lab scale rotary drum vacuum filter and filtration system. It can be used to validate the suitability of this type of continuous vacuum filtration equipment.

Key Points

• Stainless Steel Construction
• Scale-Up Trials
• Filter Media Evaluation
• Validation Tests
• Precoat Automatic Kinfe Advance System (AKAS)
• Precoat Optimisation
• Separation Efficiencies
• Filtration Flux Rate Profiles