Filtration EquipmentPresented by

Shruti Biyani 13DYE1002 Pranav Kachhawah 13DYE1004 Tushar Kukreja 13DYE1003 Meet Patel 13DYE1001

Filtration • Filtration may be defined as the separation of solid from a fluid by

means of a porous medium that retains the solid but allows the fluid to pass.

• The suspension of solid and liquid to be filtered is known as the slurry. The porous medium used to retain the solids is described as the filter medium.

• The accumulation of solids on the filter is referred to as the filter cake, while the clear liquid passing through the filter is the filtrate.

Type of Filtration systems Batch Filtration• Usually performed under constant pressure with a pump that moves the

broth or liquor through the filter.• Filter cake will build-up as filtration proceeds and resistance to broth flow

will increase.

Continuous filter • Continuous filter gives higher throughput while operating at lower

pressure differential.• In large –scale operation, continuous operation is sometimes desirable and

it may be necessary to filter slurries containing a high proportion of solids.

Industrial Filter• Nutsche Filter • Rotary Drum Filter Vacuum filters

• Pressure Leaf Filters • Filter PressPressure filters

• The perforated basket centrifuge• Tubular centrifuge

Centrifugal filters

Nutsche Filter • Industrial version of Buchner funnel. Closed batch filtration under pressure

or vacuum.• Nutsche Filters are well suited for handling flammable, toxic, corrosive and

odor-noxious materials since they are autoclaved and designed for use in hazardous environments when extremely safe operation is required.• The Nutsche in its full configuration consists of four major components: The vessel The Filter Floor and Filtering Medium The re-slurry arms for cake washing and smoothing The cake discharge mechanism

Feed Inlet

Filtrate Outlet Cake Discharge Outlet

Filtering MediumReslurry Paddle/Smoothing Arms

Emergency by-pass

Advantages DisadvantagesMinimum floor space Cakes are slow to form

Minimum risk of environmental hazard from toxic, flammable or volatile cakes.

When cake is sticky and does not part readily from the filter medium.

When the cake tends to crack smoothing avoids the wash liquid, air or gas purge from by-passing.

When product deteriorates during long downtime.

Reslurry washing, being more efficient than in-situ washing.

When the process chain is continuous.

Nutsche Filters are typically used in Paints, Dyes and Pharmaceuticals and waste water treatment.Nutsche filters can be fabricated in materials like Hastelloy , stainless steel, mild steel, and mild steel with rubber line, polypropylene fibre-reinforced plastic (PPFRP).

FILTER PRESS• Filter Press are separation devices used for solid or liquid separation that

work on feed pressure or squeeze pressure to reduce liquid content in process or waste slurries or to reduce solid content in a product.• A Filter press consists of a series of horizontally arranged vertical filter

chambers each covered with synthetic woven material. Applications Dyestuff Dyestuffs, Intermediates for Dyes, Optical whitening agents,

Pigments etc.Metallurgy Zinc, Copper, Nickel, Gold, Platinum, Silver Nonferrous metals.Pollution Effluent Treatment, Sludge Dewatering.Food Fruit juice, Squash, Strach & Glucose, Fats EdibleOil, Glycerin

• Advantages:

– Simple design and operation – Low maintenance cost – Large filtration area with small floor area – High pressure operation possible – Suitable when cake or liquid are products

• Disadvantages:

– Continuous assembling and dismantling required, so heavy on labor cost

Centrifuge• A centrifuge consists of a basket in which mixture of solid and liquid,

or mixture of two liquids is rotated at high speed so that it is separated into its constituents by the action of centrifugal force. • Filtering centrifuges use centrifugal force to pass a liquid through a

filtration media, such as a screen or cloth while solids are captured by the filtering media.• Filtering centrifuges primarily deal with perforate basket, pusher and

peeler centrifuges.

The perforated basket centrifuge

• A vessel about 1m. in diameter and its outer wall is perforated. It is mounted on a vertical shaft by means it can be rotated at a high speed. An outer casing with an outlet collects the liquid thrown out from the basket through the holes.

The pusher-type centrifuge

• It has an axially mounted cylindrical basket and a filtering screen made of trapezoidal bars. The slurry is fed into the narrower end of the basket and a reciprocating piston pushes the cake formed on the screen forward but the stroke of the piston stops just short of the broader end of the basket. • This enables a thick layer of cake to remain at the discharge end

which serves as a rim to prevent short-circuiting of the feed slurry. This way, the discharged wet cake comes out with minimal liquid content.

Slurry

Solid DischargeLiquid Discharge

Peeler centrifuge

• The high rotation speed provides high centrifugal force that allows the suspended solid in feed to settle on the inner surface of drum. The washing processes are performed at the same rotational speed and in same centrifuge vessel.• The unique feature of Peeler Centrifuge Horizontal Peeler Centrifuge

is the constant basket speed which allows all operations like feeding drying discharging to be carried out at full basket speed.• The solids are discharged by being peeled from the basket by a knife

edge and then dropped into a discharge chute which carries them out of the basket.

Advantages Disadvantages

Perforated basket centrifuge Very compact, High concentration slurries

Batch process, High labour Cost

Pusher-type centrifuge Continuously operated apparatus Constant feed flow, not suitable forhigh viscosity feed

Peeler centrifuge Batch and continuous centrifuge processes

Very high capital cost, sharp peeler may damage filter medium.

Centrifuges are successfully used in Food Stuff, Pharmaceutical, Plastic, Organic & Inorganic Chemicals Industry for separating solids from solid liquid slurry with 5 to 50% solids contents and particle size ranging from 2 microns to 10 mm.

Factors Considered for Filter Selection

• Nature of slurry and cake formed (cake resistance) • Solid concentration in the feed • Desired throughput • Physical properties of filtrate (viscosity, corrosiveness, etc.) • Need of cake washing • Cake dryness • Contamination of solids by filter aid • Valuable product (solid, liquid, both or neither)

Desired Properties of Filter Media •Must retain the solids (clear filtrate) • Must not plug or blind • Must be chemically resistant • Must be physically strong to withstand process conditions • Must permit clean cake discharge • Must not be exorbitantly costly

Typical Industrial Filter Media• Canvas cloth (woven or non-woven) • Woolen cloth • Metallic cloth (Monel or stainless steel) • Nylon • Polypropylene • Polyesters