Centrifuge solution for Renagel production process

Two new vertical centrifuges, supplied by Thomas Broadbent, of Huddersfield, UK, to the Haverhill operations of Genzyme, have helped this leading international biotech company make significant increases in the production of its kidney drug Renagel.

Following successful first phase processing, Genzyme was keen to move to large-scale production and expanded its output five-fold, using a new large-scale production plant. Due to its relative fragility and hygroscopic nature, however, Renagel is extremely difficult to dewater, and for the original process design, Thomas Broadbent provided an appropriate and cost-effective solution for separating gel from the reaction solvent.

Following initial investigations with existing Broadbent centrifuges on site, the Series E machine was chosen because of its ability to work automatically, operate on a semi-continuous basis and handle gel without damaging the structure - an effect that could produce fines and compromise downstream processes. The Series E's ability to operate over a wide range of speeds enables the gel to be separated without overcompaction and extrusion, while maximising product recovery. This is achieved at a relatively low centrifugal force of 600G.

The machines are built to GMP standards, and to achieve this, the necessary design improvements included superior surface finishes and the flush fitting of pipe connections to the internal face of the centrifuge lid - features which substantially improve CIP (clean in place) performance.

Commenting on the success of the project, Peter Thomas, director of facilities development for Genzyme said: 'Broadbent was chosen for its proven track record on this particular product, and its positive approach to solving customer problems.'

The Broadbent Series 'E' stainless steel centrifuge uses a 440l, 1250 x 710mm basket. The system incorporates a fully regenerative main drive and a compact and innovative electric 'plough' discharge mechanism. This automatically controlled system, which covers the full depth of the unit, directs solids through the bottom opening of the basket and discharge chute. Feed slurry is controlled by a non-contacting sensor and a distributor for maximum solids load and good balance.

All functions are controlled by a fully automatic programmable logic control system, complete with intrinsically safe input/output circuits for use in hazardous areas. A 380mm diameter inspection window, complete with internal wiper, is incorporated in the opening cover to provide good visibility into the machine during the processing cycle, while a flameproof lamp illuminates all internal areas.