Centrifuges Used in Pharmaceutical Manufacturing: A Primer

March 22, 2018
Jigar Patel

Jigar Patel is director of Business Development at Oriental Manufacturers, www.orientalmanufacturers.com, a design and manufacturing company for process equipment and tailor-made fabricated equipment, based in Gujarat, India, j.patel@orientalindia.net.

Four types of centrifuges used in pharmaceutical manufacturing have different features.

An industrial centrifuge is equipment that separates fluid or particles using centrifugal force. Different types of centrifuges are used for separating solids from liquids, liquid-liquid separation, and liquid-liquid-solid separation. This article will describe four types of centrifuges that are used in the pharmaceutical industry.

Horizontal peeler centrifuges

This centrifuge works on the principle of centrifugal force for separating solids from liquids by density difference. Examples include separating salt from water or separating urea from the mixture of unconverted carbamate. The high rotation speed provides the necessary centrifugal force that allows the suspended solids to settle on the inner surface of the drum. All the washing processes are performed at the same rotational speed and in the same centrifuge vessel.

One of its unique features is the constant basket speed, which allows all operations, such as feeding, drying, and discharging, to be carried out at full basket speed. Horizontal peeler centrifuges can be run as batch or continuous processes.

The peeler of this centrifuge is actuated by a hydraulic cylinder and a peeler shaft assembly. It has a blade and mounting arrangement located over the discharge chute so that the scraped cake can fall directly into the discharge chute.

Top discharge centrifuges

These are a cost-effective alternative for pharmaceutical production. Top discharge centrifuges can be easily adapted to product characteristics, making them suitable for a wide variety of products in small to large batches, even those that are difficult to filter. The machine has gentle solids discharge without particle destruction.

This type typically has an automatic clean-in-place (CIP) system and a lossless filter cake discharge. The machinery parts that are in contact with product are easily accessible for cleaning.

Vertical peeler centrifuges

The vertical peeler centrifuge operates under a discontinuous filtration process and is well suited to the efficient separation of pharmaceutical products along with fine and bulk chemicals. This centrifuge is mainly used with small batch sizes and for products that are changed frequently.

There are no crystal breakages as the peeling is performed at a reduced speed. The process housing opens and closes automatically, thus enabling the complete inspection of all components in the process area. A fully automated CIP system carries out the cleaning process and is equipped with the flooding of the process enclosure if necessary.

This centrifuge machinery is suited for separating Amino acids, benzoic acid, benzene, sulphur, calcium hypochloride, hexachlorocyclohexane, insulin, penicillin, and starch, for example.

Inverting filter centrifuges

This filtration system is capable of automatically discharging the collected particulates. It is suitable for filtering process waste and difficult to filter products, with a gentle product discharge that leaves no residual heel. The discharge method does not involve scraping or pressing, which maintains the shape of the particulates. The mechanically operated system eliminates any contamination found in hydraulic systems. It has high spin speeds at maximum basket load and the consumption of the washing medium is comparatively low.

Conclusion

Don't assume that every pharma centrifuge machine has the ‘one size fits all’ approach. Choose the one based on the kind of material that will be processed.

About the Author

Jigar Patel is the director of Business Development at Oriental Manufacturers, a design and manufacturing company for process equipment and tailor-made fabricated equipment, based in Gujarat, India, j.patel@orientalindia.net.