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Renin Angiotensin Mechanism.

Perforated Basket Centrifuge.

 

Centrifuge:

  • The equipment used for the process of centrifugation is called a Centrifuge.

  • The centrifuges are of two types as following,

  1. Sedimentation centrifuge:L

  • It is a centrifuge that produces sedimentation of solids based on the difference in the densities of two or more phases of the mixture. 

  1. Filtration centrifuge:

  •  It is a centrifuge in which solids pass through the porous medium based on the difference in the densities of the solid and liquid phases.

Perforated Basket Centrifuge.

Principle:  

  • Perforated basket (bowl) centrifuge is a filtration centrifuge.  

  • The separation is through a perforated wall based on the difference in the densities of solid and liquid phases. 

  • The bowl contains a perforated side-wall.  

  • During centrifugation, the liquid phase passes through the perforated wall, while the solid phase is retained in the bowl.  

  • The solid is removed after cutting the sediment by a blade after stopping the centrifuge. 

Construction:  

  • It consists of a basket, made of steel (sometimes covered with vulcanite or lead) or copper or monel or any other suitable metal.  

  • The basket may have a diameter of 0.90 meters and a capacity of 0.085 meter cube.  

  • The basket is suspended on a vertical shaft and is driven by a motor using suitable power systems such as belt pulleys, water turbines and electric motors.  

  • Surrounding the basket, a casing stationary is provided which collects the filtrate and discharges it at the outlet.

Working:  

  • The material is kept in the basket when the basket is stationary.  

  • Power is applied to rotate the basket and maximum speed must be attained quickly. 

  • The basket runs at 1000 revolutions per minute.  

  • During centrifugation, the liquid passes through the perforated wall, while the solid phase remains in the basket. 

  • The liquid leaves the basket and is collected at the outlet.  The cake is then spun to dry as much as possible.  

  • After a definite period of time, the power is turned off. By applying a brake the centrifuge is stopped.  The basket is brought to rest. 

  • The solid cake is cut using a blade and then unloaded manually.  

Uses:  

  1. Performed basket centrifuge is extensively used for separating crystalline drugs (such as aspirin) from the mother liquor. 

  2. Free flowing product can be obtained because mother liquor is removed completely.  

  3. It is also used for removing unwanted solids from a liquid. For example, precipitated proteins are removed from insulin.  

Advantages:  

  1. The centrifuge is very compact and it occupies very little floor space.  

  2. It can handle slurries with a high proportion of solids and even those having a paste-like consistency.  

  3. The final product has very low moisture content.  

  4. In this method, the dissolved solids are separated from the cake.  

  5. The process is rapid. 

Disadvantages:  

  1. The entire cycle is complicated, resulting in considerable labor costs.  

  2. It is a batch process.  

  3. If the machine is adapted for prolonged operation, there is considerable wear and tear of the equipment.  

Commonly Asked Questions.

  1. Write a short note on Perforated Basket Centrifuge.
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