Operational Details

Traditionally rotary drum filters have not been applicable in small to medium volume production applications. This is primarily due to the complicated mechanical construction of a typical filter designs that originally arose from in the CPI. In the design of these existing devices engineering detailing the rotation mechanism, shaft seals, etc. usually made them too expensive to directly "scale-down" to a size that would be appropriate for use in the small to medium volume applications seen in the Pharmaceutical, Fine Chemical, and beverage industries.

The operation of the Disposable Rotary Drum Filter is analogous to all vacuum drum filters. These filters are made up of an inner rotating drum encased in an outer cylinder or half-cylinder (trough). The slurry enters the outer cylinder or trough and settles in the bottom. The level is controlled so that the inner drum's surface is covered to 30% - 35%. The surface of the drum is covered with a filter fabric. A vacuum is pulled on the inside of the drum, pulling filtrate into the inside and depositing the solids on the fabric. The filtrate is pulled into channels in the interior of the drum and routed out of the device. The system is made continuous by rotating the drum. As it rotates out of the liquid, the solids start to dry as air passes though them via the vacuum on the drum. When the drum completes its revolution the surface comes in contact with a scraper or knife blade, which removes the solids that have accumulated. The drum continues rotating back into the slurry and the process starts all over again.

Once the device has reached steady state, the drum is fully covered with the solids cake for the first time, then the device can operate for hours or days taking in slurry and discharging clarified filtrate and dried solids continuously. The main advantage of this over a batch operation being that large amounts of slurry can be processed in a small enclosed device, minimizing manpower, operating space, and HVAC resources.