Principle, Construction, Working, Uses, Merits and Demerits of Filter Leaf

Filter Leaf

Principle

• This apparatus consists of a drainage screen covered in filter cloth extending longitudinally.
• It works as a sieve or strainer due to surface filtration.
• The rate of filtration can be increased by applying vacuum or pressure.

Construction

• A leaf filter consists of an outer frame containing a drain screen or grooved plate
• There is no restriction on the shape of the frame, be it circular, square or rectangular
• Filter cloth covering the entire unit
• Filtrate exits through a suction connection on the inside of the frame

Working

• Slurry immerses the filter leaf.
• The outlet has a vacuum system.
• A filter cloth filters the slurry.
• The filtrate finally exits the drainage canal and enters the receiver through the outlet.
• Air is passed through the tunnel to facilitate the removal of cake.

Uses

• Filter is used for filtration of slurries with low solid content, e.g., dilute suspensions, where the solid content is less than 5%.

Merits

• A batch process filter is the simplest type.
• In order to increase the filtration surface area, a number of units can be connected in parallel.
• There is the possibility of obtaining a vacuum or applying pressure up to 800 kilopascals.
• The operation of the filter leaf is relatively inexpensive.
• Cleaning is highly effective.
• Any vessel can be used to filter the slurry.
• Using a vessel of water, you can wash the cake by immersing the filter.

Demerits

• Processes like these are not continuous.
• In most cases, it is used where there are less than 5% solids in the liquid to be filtered.

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