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BHS Autopress for processing poor filtering and/or hazardous materials:

• up to 40 bar g dewatering pressures
• gas tight and fully automatic
• no cake cracking
• excellent cake washing
• gas blowing and cake squeezing for dewatering
• Combined filter and dryer
• Easily cleaned (CIP)
• SIP options available

The BHS-Autopress can be used for separating moderate to poor filtering suspensions efficiently. Media that need to be treated in closed machines for reasons of sterility, toxicity and workplace hygiene are separated safely and reliably. If required, you may also treat the cake by washing, extraction, pressing blow-out and drying. Low cake thickness, complete filtration without heel volume and an exceptionally low level of residual moisture in the predried cake ensure extremely high throughput rates. The highly efficient cake washing process occurring in the BHS Autopress produces an absolutely pure product without intermixing. The encapsulated version (for pharmaceutical products and in GMP design) can also be used for filtering toxic or volatile media.

Criteria

The BHS Autopress is made up of the following principal compo-nents:

• horizontal stack of filter plates
• movable filtration housing
• scraper

Technical Description

The horizontal stack of filters consists of a headpiece and a foot, the filter plates and the flexible spacers. The filter plates, spacers and foot are provided with bores for the plate anchors, suspension inlet, filtrate and plate stack venting. The filter plates are configured in such a way that the filtrate is able to pass from opposing plate sides through the two plate channels. Flexible spacers separate the suspension chamber from the filtrate chamber. These permit mechanical expression of the plate stack and, in turn, of the filter cake. The filtration housing forms a pressure-tight enclosure around the plate stack. It is relocatably mounted on two anchoring rods, making it movable. In the closed position, the filtration housing is located over the plate stack. The annular gap between housing and plate stack is sealed off by a membrane. The stack is sealed off from the outside at the headpiece and at the foot. The plate stack can be exposed by moving the housing. The product chamber is enclosed by a housing which may, depending on requirements, be configured on splashproof, vapour or pressure-tight design. The capability of CIP cleaning is also given by installing spray lances and spherical head nozzles.

Filtration

The suspension is pumped into the gaps between the plates. Filtration takes place as a result of the pressure difference prevailing on both outer sides of the filter plates. Filter cake builds on both plates and grows towards each other, completely filling the gap.

Filter Cake Washing

Once the cake has formed, it is washed; starting from one plate side through the entire cake to the opposing side. When the washing process has been completed, the cake can be blown out by compressed gas. Applying hydraulic pressure to the end plates will additionally squeeze the cake.

Filter Cake Drying

In a similar way to the cake washing process, the cake can also be blown dry from the filtrate and suspension side.

Filter Cake Discharge

The plate stack, and with it the filter cake, is exposed by moving the housing. The cake is discharged by gravity (under its own weight) and/or mechanically by scraper knives.

Criteria

The BHS-Autopress can be used to good effect where the following criteria need to be met on the process side:

• Batchproduktion
• Several consecutive process steps
• Closed gastight production
• Workplace hygiene and safety
• Fully automatic handling

Applications

The main fields of applications are:

• Management of waste water and residual substances
• Chemical industry
• Dyestuffs
• Beverage industry
• Food industry
• Pharmaceutical industry

In general:

Thanks to its design, the Autopress is able to meet the following demands:

• Filtration suspensions containing solvents
• Filtration of poor to average filtering suspensions
• Filter cake from 5-15 mm
• Use of pressure filtration up to 10 bar
• Temperatures up to 200 °C
• Dewatering through mechanical expression up to 40 bar
• Filter cake drying
• Permanent cleaning (CIP, sterilisation)
• Toxic and highly flammable products
• Precoat filtration

Related Articles

• Clean-in-Place Operations for Thin-Cake Filtration Technologies
• Evaluating thin-cake pressure filtration using the BHS Autopress technology