The industrial centrifuge plays an integral role in the production of more things than one would initially expect. It is a commonly used tool in the food and agricultural sector, At pharmaceutical and biotechnology companies, for environmental management, and in the chemical industry. The word industry conjures up images of combination and creation—adding materials together to produce a final product. However, the separation of materials is just as important as the combination of materials. We can't create a new product until we have pure reactants to work with. This is especially important in the pharmaceutical and biotechnological realms, where reactant purity is essential to the production of a product that is safe for human consumption. This is where the centrifuge comes in. The centrifuge is used to separate heterogeneous mixtures into components varying by density.
Principle of centrifugation - how a centrifuge works
The industrial centrifuge rotates at a high speed, with many revolutions per minute (rpm). This rotation introduces a centripetal force inward, and a relative centrifugal force outward. This relative centrifugal force is hundreds of times greater than the force of gravity we feel on earth. We know from everyday experience that a heterogeneous mixture of solid in liquid, when given enough time, will separate due to gravity and result in a sediment at the bottom of the container. The same principle is at work inside the industrial centrifuge, but the high centrifugal force causes the separation to occur within minutes.
Types of industrial centrifuge
Depending on the industry and application, a company will choose one of two main centrifuge types, sedimentation and filter.
One of the two main types of industrial centrifuges is the sedimentation centrifuge. In the sedimentation centrifuge the higher density particles are forced to the outer edges of the container where they force a closely packed pellet. These centrifuges can be used in the pharmaceutical industry for production or analysis of drugs. There are several types of sedimentation centrifuges: the hydrocyclone, the tubular bowl, the chamber bowl, the imperforate basket, the disk stack separator, and the decanter. All these centrifuges have different separation capacities based on their architecture and speed limits.
The second main type of industrial centrifuge is the filter centrifuge. In filter centrifuges there is a filter which catches particles and prevents them from following the rest of the mixture outward as the centrifuge spins. A couple of examples of filter centrifugation in the food industry includes the production of pulp-free orange juice and the removal of water from washed salads prior to packaging. There are several types of filters that are used for the filter centrifuge, such as filter cloth, wire mesh or perforated plate filter, or the slot screen. The filter cloth is used in the peeler centrifuge as well as the inverting filter centrifuge and the pendulum centrifuge. The wire mesh is known as the worm screen centrifuge. The slot screen is used for the pusher centrifuge.
The centrifuge in the pharmaceutical industry
The most important thing for the pharmaceutical industry to achieve is the creation of consistently pure batches of active pharmaceutical ingredients (APIs). The moisture content is important for concentration and storage, and it is especially critical to avoid any cross-contamination with other ingredients. The industrial centrifuge is commonly used in the pharmaceutical industry to dry out the API into a layer cake of material. A basket centrifuge is the tool used to do this. A basket centrifuge is a horizontal centrifuge with a large basket filter. As the centrifuge spins it also filters the API so that water or other solvents run through the pores of the filter and the solid API builds up on the inside of the basket because it is too large to fit through the pores. This process is also called deliquefying. Additional wash steps can be completed before the final drying of the API layer cake. It is important that the cake remain at a thickness of about one inch or less in order to ensure proper washing and drying during the centrifuge process. Many times the centrifuge is equipped with an inflow of nitrogen gas to create an inert atmosphere to protect the API from cross contamination and unwanted reactions. These industrial centrifuges are created with cleanliness in mind, and are easy to clean and decontaminate between batches.
Other applications for industrial centrifuges
Other uses for the industrial centrifuge include the recovery of cells in biotechnology and the recovery of valuable pharmaceutical reactants and products. Centrifugation is used for wastewater treatment and sewage processing. It is used to remove particulates like metal shavings from industrial lubricants. It is important for the isolation of valuable synthetic materials throughout the manufacturing process. The centrifuge makes it possible for many materials to be manufactured on the industrial scale because it allows for the rapid separation of mixtures. There are different types of centrifuges for different applications, and the optimal rpm varies among mixtures, but the basic principle of centripetal acceleration is useful for all applications. We can create great things when we understand fundamental physical laws and engineer tools to capitalize upon them.
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