CENTRIFUGING( PURIFIER AND CLARIFIER)

OIL TREATMENT



Both fuel oils and lubricating oils require treatment before passing to  the engine. This will involve storage and heating to allow separation of water present, coarse and fine filtering to remove solid particles and also centrifuging.

The centrifugal separator is used to separate two liquids, for example oil and water, or a liquid and solids as in contaminated oil. Separation is  speeded up by the use of a centrifuge and can be arranged as a continuous process.     

1. Where a centrifuge is arranged to separate two liquids it is known as a 'purifier'. 

2.  Where a centrifuge is arranged to separate impurities and small amounts of water from oil it is known as a 'clarifier'.

Liquids with a specific gravity or relative density difference can be separated in a settling tank by the effect of gravity clearly in a standing vessel the acceleration cannot be altered  to enhance the separation force but by subjecting the operation to centrifugal forces it can be enhanced.


✓ To operate the centrifuge as a purifier

1. It is first brought up to operating speed, supplied with fresh water to form the water seal and then the oil to be purified is delivered to the distributor by the inlet pump.  

2. As the oil passes down the distributor it is rapidly brought up to the rotational speed of the purifier by the radial vanes provided for this purpose. The oil passes from the distributor through the space between the bottom plate and bowl to the supply holes. 

3. From the supply holes the oil is fed to the spaces between discs through the distribution holes in the discs. 

4. Separation and clarification takes place between the discs, water and sludge moving radially outwards pass along the under surface of the discs and the purified oil moving radially inwards passes over the upper surface of the discs. Water and sludge are eventually discharged at (a) and the purified oil at (b).



✓  To operate centrifuge as a clarifier

1. No water seal is provided and the bottom plate and discs have no supply and distribution holes. 

2. Discharge of the clarified oil takes place at (b), sludge and solids collect upon the bowl wall. 

3. Since there is no water seal in a clarifier more bowl space is available for the oil, hence there will be available a greater centrifugal settling force due to the increased radii. 

4. Figure shows a centrifuge arranged for clarification. 


✓ Compare PURIFIER and CLARIFIER




Purifier    

a. Remove water and suspended 

 Solids particles from oils from oil 

b. Two outlets water and clean oil  

c. Gravity disc on top 

d. Blind disc on the top of disc stack . 

e. Sealing water required 

 Clarifier

a. Remove finer and lighter particles 

b. one outlet for clean oil

c. No gravity disc only sealing ring 

d. Blind disc at bottom

e. Sealing water not required


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