Rotary Filters Verteil Information

8/18/2019 Rotary Filters Verteil Information

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Types of Rotary Filters

Characteristics and Typical Applications of Rotary Filters

Modern Filtration

in the Process

Industry

BOKELAFiltration Seminar

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/ 2 0 1 4

www.bokela.com

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BOKELA Filtration Seminar

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Types of Rotary Filters

RotaryDisc Filter

RotaryDrum Filter

Hi-Bar Disc Filter

Pannevis

Vacuum

Filters

Continuous

Pressure

Filters

Pan Filter

Hi-Bar Oyster Filter(Drum Filter)

HorizontalBelt Filter


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Typical Product / Process Characteristics andRequirements on Filtration in the Chemical Industry

• crystallization products:resulting in hard particles with regular shape

• precipitation products:resulting in amorphic, weak particles with irregular shape (approx. 50 -60% of all products )

• high amount of fines with x < 10 µm (esp. at precipitation products)

• particles sensitive against mechanical stress (cracking of particles)

• not finished crystallisation danger of post- crystallisation

• viscous liquids

• high slurry temperatures

• extreme pH-values

• corrosive, toxic or reactive products

Typical product / process characteristics


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Typical Product / Process Characteristics and

Requirements on Filtration in the Chemical Industry

• high specific throughput even in case of fine solids

• highly efficient cake wash

• low consumption of wash liquor (and /or steam)

• sharp separation of filtrates

• clear filtrate

• low moisture in cake

• prevention of

- post- crystallisation

- crystallisation of unwanted components

• low consumption of air/gas

• no emissions

• reliable and flexible operation in case of changing productcharacteristics (e.g. particle size distribution)

• high availability of equipment

• good access and easy cleaning of equipment

• low maintenance effort, convenient operation

Typical requirements on filtration results andfiltration equipment


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Types of Rotary FiltersHorizontal Belt Filter

Larox/Pannevis belt filter

Characteristics of belt filters

• horizontal filter area

• filtration in direction of gravity

• low filter area per footprint i.e. high floor space demand

• excellent cake washing

• poor tolerance to changes in feed rate concentration

(danger to be flooded)

• high consumption of fresh water

• belt exchange needs long time and causes high cost

• filtration areas up to 250 m² (depending on design)

• belt width up to 4 m (depending on design)


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Belt filter with rubber transporter beltcloth and transporter belt are continuously moving

feeding

clothwashing

cake washing

filtercloth

rubbertransporter belt

vacuum boxunderneath transporter belt

cloth trackingsystem

Delkor belt filter

frame

cake discharge

material: NR, EPDM, PES

lifetime: 4- 6 years

cost: 30 – 40 % of filter cost

rubber transporter belt


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Belt filter with reversing trough shaped vacuum trays & continuously moving cloth

return stroke(trays are vented)

vacuum tray

vacuum stroke(trays are evacuated)

Larox/Pannevis RT belt filter type

cloth • Filter areas: up to 65 m²

• Belt speed: up to 5 cm/sec

• Cake thickness: 30 – 100 mm

• Typical application products:chemical products, foodproducts, pharmaceuticalproducts, pigments,hydrometallurgicalconcentrates, minerals,fine coal slurries


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Advantages and Disadvantages of Belt Filters

pro contra

can handle large variations in feed rate, in

combination with measurement of cakethickness, PSD etc (speed control)

high capital costs

excellent if washing of filter cake is requiredlarge footprint area, high building cost

(around 0.5 m² filter area / m² footprint)

low maintenance difficult belt alignment

simple mechanical design low specific solids throughputs

easy to operate critical cake discharge

very good cloth cleaning vacuum loss due to leakage / sealing problems

sensitive to variation of slurry content

sensitive to efficiency / dosage of flocculants

sensitive to tightening of vacuum sealing

filter cloth change needs long time and causes

high cost


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Types of Rotary FiltersPan Filter

Characteristics of pan filters

• horizontal filter area

• filtration in direction of gravity

• filtration of coarse materials

• very thick filter cakes up to 150 mm

possible

• medium filter area per footprint

• excellent cake washing

• filtration areas up to 70 m²

• pan diameter up to 10 m


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Types of Rotary FiltersRotary Drum Filter

Variants of drum filters

• Method of cake discharge

- Compressed air blow backwith scraper

- belt discharge

- roller discharge

- precoat with knife discharge

• top-feed drum filter

• Single cell (cell-less) drum filter

• inner drum filter

• drum filter with steam hood

• drum filter with press belt / roller

Drum filter with belt discharge

Drum filter with compressedair blow back

Eimco


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Types of Rotary FiltersRotary Drum Filter

Advantages and Disadvantages of Drum Filters

Pro contra

relatively low capital costscan not handle extremely highproportion of fines in feed (moisture,throughput)

compact design and small footprint area(around 1 m² filter area / m² footprint)

lower specific solids throughputcompared to disc filter

tolerant to variable feed rate, solidsconcentration and PSD

critical for overdosage of flocculant(accepts decrease of flocculant dosage)

effective cake washing (i f required) needs agitator in the trough

relatively low operating costs

low maintenance

uniform cake across the full drum width

self-controlling operation

self-aligning control valve(reduced risc of vacuum leakage)

exchangeable filter cells (BOKELA design)


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Types of Rotary FiltersRotary Disc Filter

Characteristics of disc filters

• highest throughput per unit

• most compact design

• very large filter area per footprint

i.e. smallest floor space demand

• tolerant to changes in feed rate

• complete cake discharge with

modern disc filters

• filtration areas up to

300 m²• disc diameter up to 5,6 m


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Types of Rotary FiltersModern High Performance Disc Filter

Boozer L-Type (44 m²/disc)

Boozer ME-Type (20 m²/disc)

• filtration area: AF = 22 - 308 m²

• segments per disc: 20 – 30

• high performance due to excellent hydraulic

• complete cake discharge

• trough design for “no agitator operation”

• Modern control philosophy


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Types of Rotary FiltersNew Generation Disc Filters – New Design

• Up to 100 % more throughput capacity

• 2 to 4 % less residual moisture in cake

• Up to 100 % higher pressure difference at cloth

• Higher filter speed (up to 4 to 5 rpm)

• 100 % cake discharge

• High operational reliability and flexibility• Minimum maintenance and operating costs

• Larger diameters of discs (up to 5.6 m)

Improvements - New Generation Disc Filters


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Types of Rotary FiltersRotary Disc Filter

Advantages and Disadvantages of Disc Filters

pro contra

most compact design and lowest footprintarea (approx. 2 m² filter area /m² footprint)

inadequate for cake washing

lowest capital costsoperational problems if no level

control available (older types )

high specific solids throughputsinadequate discharge without snap-blow system (older types )

low residual cake moisture (only for moderndesign)

older type filters require moremaintenance and attendance

very effective cake discharge system(up to 100 %) by using snap blow system

older types need agitators in trough

variations in feed flow rate acceptable

uniform cake over segments if number ofsegments > 20/disc

low maintenance

low operating costs


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Types of Rotary FiltersContinuous Pressure Filters – Hi-Bar Drum Filter

Drum/Disc Filter

• Filter installed in pressurevessel

• Pressure Difference:∆p = < 14 bar

• High temperature filtration:T < 220 °C

• Counter-pressure filtration

• Filtration Area:1 m² –81 m²

• Extremely low moisturecontent with Hi-Bar SteamPressure Filtration

Hi-Bar Oyster Flter with exchangeable filter cells and

steam cabin for steam pressure filtration

filter area: 4 m²


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Types of Rotary FiltersContinuous Pressure Filters

Advantages and Disadvantages of Continuous Pressure Filters

pro contra

compact design and low footprint area high invest cost

filter type: drum or disc sluice system required for dischargeof filter cake out of the vessel

highest specific solids throughputs

lowest residual cake moisture

excellent cake wash

filtration at high pressures andtemperatures

variations in feed flow rate acceptable

closed system


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Characteristics of Continuous Rotary Filters

specificthroughput

moisturecontent

cakewashing

processadaptability

footprint

operationcost

invest-cost

Belt filter 0 + ++ + - 0 -

Drum filter+ +/0 + ++ + + +

Disc filter ++ + - + ++ + ++

Pan Filter + + ++ 0 0 + +

Hi-Bar ++ ++ + + ++ ++ -

particle size [µm]

0,1 1 10 100 1000 10000

drum filter

belt filter

pan filterdisc filter


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Types of Rotary FiltersDynamic Cross Flow Filters – DYNO Filter

Hi-Bar Oyster Flter with exchangeable filter cells and

steam cabin for steam pressure filtration

filter area: 4 m²

Characteristics of DYNO Filter

• cross flow produced by rotors(high & constant cross f low velocity u)

• Modular construction

• Limited filter area < 12 m²/unit

• Separation of solid particles > 0.01 µm

• Purification of liquids even with very lowparticle concentration of < 1 ppm

• Thickening and classification even athigh concentrations

• High end-concentrations

• Dead end filtration: absolute clearfiltrate

• Counter current washing

• Hermetically sealed process

• Continuous operation


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Types of Rotary FiltersDYNO Filter

Advantages and Disadvantages of Dynamic Cross Flow Filters

pro contra

high & constant cross flow velocity u over thefilter medium

higher invest cost as conventionalcross flow systems

various filter media available limited filter area < 12 m²/unit

highest end concentrations application restricted to

small to medium feed rates

thickening even at high feed concentrations cooling required for products

sieve filtration i.e. separation of low

concentrated coarse particles from high

concentrated dispersions and suspensions

sensitive to temperature(due to energy input by rotors)

difficult to separate products:- Slimy, jelly smooth particles,

- Newtonian, plastic or thixotrope suspensions

Counter-current washing

filtration at high pressures & temperatures

hermetic closed system – no air contact

Rotary Filters Verteil Information

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