Vacuum lters lters
Vacuum lters Vacuum ltration is a well established technique used in industrial dewatering. Metso has successfully delivered and installed many hundreds of rotary vacuum lters covering a wide eld of applications. All rotary vacuum lters operate on a similar principle.
A pressure dierential between the surface and inside of the drum (or disc) is applied by means of vacuum. This pressure dierential causes transport of liquid through the ltration surface while the lter medium arrests solid particles and a cake is formed. As the drum rotates,
the cake rises above the slurry level in the lter tank and air is drawn through the cake, forcing out liquid. The liquid (ltrate) exits the lter through the internal piping and the vacuum head.
giam 2 4 6
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8 10
2 3
12 14 16 18
1. Top Feed Drum Filter 2. Drum Filter 3. Disc Filter 4. Belt Drum Filter
20 22
4
24 26 28 30
1
2
3
4
2
5 6 7 8 910
3
4 5 6 7 8 9100
2
3
4 5 6 7 8 91000
2
3
4 5 6 789
Comparison o suitable equipment or dierent particle size distribution and residual moisture.
Principal components o the drum flter model TF 1. Drum 2. Drum drive 3. Support Frame 4. Tank 5. Vacuum Head 6. Agitator
The range o rotary vacuum flters incorporates two basic design principles:
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5 6
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High vacuum air lowrates
The Metso lters are specially designed for high vacuum operation allowing very high air owrates. This results in: – higher capacities – lower cake moisture – extended application range Integrated components
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3
Pressure dierential causes transport o liquid through the fltration surace while the flter medium arrests solid particles and a cake is ormed.
Modularized components and equipment results in: – exibility in machine conguration – features may be added or altered to accommodate process changes – construction from proven, standard components – simplied maintenance and parts replacement – lower equipment and operating costs
2 Vacuum lters
Options and accessories for TF and TFF lters Wire winding attachment For certain applications lter cloths are held onto the drum by means of wire. The wire winder automatically feeds cloth attachment wire onto the drum as part of the normal procedure of cloth replacement. The device has a simple mechanical construction and includes drive motor and gearbox. – adjustable to suit all drum diameters and lenghts – feed wire drum may be placed in any location near the lter – adjustable wire tensioning brake on guide wheel – manual vari-speed drive as optional extra
1. Wire guide wheel 2. Guide trolley and main beam 3. Drive motor assembly 4. Idler sprocket assembly 5. Trolley drive chain 6. Feed wire drum and support trestle
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3
2
4 5
6
Snap blow cake discharge system 1
5
2
A short duration pulse of compressed air injected into each lter sector immediately prior to the cake discharge point provides for: – positive discharge of thick or sticky cakes cleaning of lter cloth
– short pulse inhibits blow back of ltrate into dry cake 3
4
Position and duration of the air pulse is adjustable. Pulses may be either supplied on a continuous or intermittent basis as required. Drum drive
– thyristor controlled vari-speed drive – limit switch overload protection – continuous torque transmitter and overload protection. 1. 2. 3. 4. 5.
Induction transmitter Control box Cog wheel on drum drive shaft Sector at cake discharge point Solenoid valve and air connection to vacuum valve
Construction materials
Depending upon application drum lters are available in carbon steel and stainless steel.
Cake washing Spray bars may be tted to wash the cake in the dewatering zone. Typically, the wash liquor joins the primary ltrate; however separate discharge of liquor and primary ltrate is possible.
Cake washing For lower moisture cake requirements a sealed hood may be tted to pass superheated steam through the cake in the dewatering zone.
Cake repulper Where the downstream process dictates, the drum lter may be tted with water/liquor spray bars and cake repulping screw. The screw is driven by a separate motor and gear reducer. The screw shaft is mounted in antifriction bearings and sealed using mechanical (standard) or hydraulics means. Drum lter with repulper attachments.
Vacuum lters 3
Standard features model TF Drum – – – – –
rugged all welded steel construction diameters from 1200 to 3620 mm “Snap in” replacable segment grids inspection/access manhole, drain and vacuum leakage “tell-tale” Selection of four drainage systems with capacities up to 350 m3/ min at max. 18 m/s ow velocity which minimizes internal pipe wear and reduces friction losses – two separate drainage pipes per drum sector, to prevent liquid “pu” back when using snap-blow cake discharge.
Drum drive – standard 4-pole AC-motor, integral gear reducer and manual speed variator – standard drum speed range 0.2 to 1.0 rpm – rubber compression pad to absorb shock loads on start-up
Support rame – standard steel section all welded support frame – one piece drum drive trestle bolted to the support frame
High capacity drum l ter. (Note the size of vacuum head)
– two piece support facilitates vacuum head removal or inspection
– drum lifting bracket at valve end to facilitate simple vacuum head removal
Tank – steel all welded construction bolted to the support frame – independent from drum, drum drive, agitator and vacuum head
Vacuum head Central lubricator – automatic grease lubrication to vacuum head and bearings
– thick (30 mm) cast iron alloy or HD polyethylene wear ring and mating housing to allow for remachining – three adjustable pressure springs for positive sealing between head and wear ring – selection of heads to match each liquid drainage system
Drum support shat assembly – full length shaft to support drum, vacuum head and internal drainage tubes – “ringfeeder” tensioning element connection to drum heads – selection of three systems depending upon lter size, vacuum head and machine capacity
Agitator – – – – – –
TF 3042 Rotary Drum Filters during shop assembly
all welded “Y” blade construction for positive stirring rotation eccentric to the drum shaft for full depth slurry stirring minimum clearance between drum and tank increasing drum clearance to allow for cake build- up easy access to vacuum head pivot support plate attachment allows mechanism to be swung out of the tank for maintenance and inspection – standard 4-pole AC-drive motor and gear reduction box – drive motor, gear box and lower crank bearings are protected from spillages by removable inspection covers. 4 Vacuum lters
Belt drum lter model BTF Cake discharge systems Belt drum lters, model BTF, are identical in all respects to the TF range with one fundamental exception: cake discharge. With the belt drum lter the cloth is removed from the drum after the dewatering zone and passes over the cake discharge system before washing and return to the drum prior to the cake pickup zone. The three key system features of the belt drum lter are thus: • cake dishcarge • cloth washing • cloth tracking
In many applications the simple ‘break roller’ system, where the cloth is passed over a small diameter roller, is sucient to eectively ‘break’ the cake away rom the cloth or discharge.
Cloth washing system Cloth washing increases the capacity of the lter and extends the cloth ser vice life by preventing blinding. After passing the cake discharge system the cloth is washed over its full width by two high pressure sprays, one above and one below the cloth. Wash water is conned by a soft rubber curtain and collected for separate discharge through a launder.
Cloth tracking system Cloth tracking is achieved by means of a single hinged guide pulley mounted in spherical roller bearings after the cloth passes from the washing system. The guide pulley is positioned by pneumatic diaphragm cylinders activated by optical or pneumatic sensors at each side of the cloth. Correct cloth tension is maintained by adjustable counterweights acting via levers to the cake discharge system. The cloth tracking system
– maintains cloth position within a few mm – eliminates need for special cloth edgings – provides self-adjusting cloth tensioning
1. Cake discharge system counter weight and lever arms 2. Pneumatic diaphragm cylinder 3. Cylinder tensioning spring 4. Optical or pneumatic cloth edge sensor 5. Guide pulley
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Vacuum lters 5
For more dicult cakes an ‘air-knie’ may be appropriate. The ‘air-knie’ consists essentially o two hardened steel (or other wear material) lips. The leading lip is proud o the ollowing one and together they orm a slot across the ull cloth width. Compressed air rom an air blower or high pressure an is injected into the knie tube and exits rom the slot onto the back o the cloth. This cake discharge system is very eective or thin and/ or sticky cakes.
A combination roller and ‘air-knie’ discharge system is also available or dicult applications. This type o discharge, in which the clearances between the ‘air-knie’ lips and the cloth is adjustable, avoids wear and replacement o the knie lips in abrasive duties. In addition there are oten benefts in cloth cleaning by reduction in wash water consumption.
Top feed drum lters model TFF The top feed drum lter, model TFF, is especially suited for dewatering slurries containing coarser solid fractions. The top feed principle promotes segregation of the coarser particles in the feed box forming a “precoat” which results in a high ltration rate cake. Our capability to incorporate very high capacity vacuum heads and internal drum drainage systems into the TFF design results in high machine capacities and lower moisture cake. Standard eatures include:
– special seal between feed box and drum prevents leakage of feed and reduces mechanical wear of lter cloth – snap-blow cake discharge Optional eatures:
– high pressure water, air or water/air mixture cloth cleaning between cake discharge and feed point.
System supply Typical vacuum lter system with ltrate pump and vacuum receiver. 1. Vacuum receiver 2. Moisture trap (Normally used for aggresive ltrate only) 3. Vacuum pump 4. Liquid separator 5. Silencer 6. Filtrate pump 7. Floor drain For plants without a ltrate pump: 8. Drain line from vacuum tank (barometric leg) 9. Water lock
2. 1. 5. 6.
7.
3.
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8. 9. 6 Vacuum lters
Dimensions or drum vacuum flters - Internal ow TF, BTF, TFF L H
W1 D
H
W2
Model TF/BTF/TFF
1206 1212 1218 1812 1818 1824 1830 2418 2424 2430 2436 2442 3030 3036 3042 3048 3054 3060 3636 3642 3648 3654 3660 3666
Vacuum lters 7
A
D
mm
600 1200 1800 1200 1800 2400 3000 1800 2400 3000 3600 4200 3000 3600 4200 4800 5400 6000 3600 4200 4800 5400 6000 6600
W3
W1 BTF mm
W2 TFF mm
W3
H
mm
L TF mm
mm
mm
1200 1200 1200 1800 1800 1800 1800 2400 2400 2400 2400 2400 3000 3000 3000 3000 3000 3000 3600 3600 3600 3600 3600 3600
1600 2200 2800 2500 3100 3700 4300 3260 3860 4460 5060 5660 4480 5080 5680 6280 6880 7480 5160 5760 6360 6960 7560 8160
1600 1600 1600 2200 2200 2200 2200 2850 2850 2850 2850 2850 3630 3630 3630 3630 3630 3630 3910 3910 3910 3910 3910 3910
2200 2200 2200 2700 2700 2700 2700 3500 3500 3500 3500 3500 4310 4310 4310 4310 4310 4310 4600 4600 4600 4600 4600 4600
1600 1600 1600 2200 2200 2200 2200 2850 2850 2850 2850 2850 3630 3630 3630 3630 3630 3630 3910 3910 3910 3910 3910 3910
1600 1600 1600 2300 2300 2300 2300 2865 2865 2865 2865 2865 3480 3480 3480 3480 3480 3480 4075 4075 4075 4075 4075 4075
Filter area m2
2.2 4.5 6.8 6.8 10.0 14.0 17.0 14.0 18.0 23.0 27.0 32.0 29.0 34.0 40.0 46.0 52.0 57.0 41.0 48.0 55.0 61.0 68.0 75.0
Weight excl.pulp TF ton
1.2 2.0 2.8 3.9 4.2 4.5 4.8 8.8 9.1 9.5 9.7 10.0 9.8 10.9 12.0 13.1 14.2 15.3 11.5 12.5 13.5 14.5 15.5 16.5
Weight excl.pulp BTF ton
1.3 2.1 2.9 4.5 4.8 5.2 5.6 9.7 10.0 10.4 10.6 10.9 10.3 11.5 12.7 13.9 15.1 16.3 13.0 14.0 15.0 16.0 17.0 18.0
Weight excl.pulp TFF ton
0.8 1.6 2.2 4.4 4.7 5.0 5.4 5.2 6.0 6.8 7.6 8.4 10.7 11.2 – – – – 9.0 9.5 – – – –
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Metso Minerals (Sweden) AB
Norrängsgatan 2, SE-733 38 Sala, Sweden, Phone: +46 224 374 00, Fax: +46 224 169 50
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Metso Minerals Industries, Inc.
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1th oor, DLF Building No. 10, Tower A, DLF Cyber City, Phase - III, Gurgaon - 122 002, India, Phone: +91 124 235 1541, Fax: +91 124 235 1601
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Av. Los Conquistadores 2758, - Piso 3, Providencia, Santiago, Chile, Phone: +56 2 370 2000, Fax: +56 2 370 2039
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www.metso.com E-mail:
[email protected]
Metso Corporation, Fabianinkatu 9 A, P.O. Box 1220, FI-00101 Helsinki, Finland, tel. +358 20 484 100, fax +358 20 484 101, www.metso.com Subject to alteration without prior notice
Brochure No. 1583-03-11-MBL/Sala-English
© 2011 Metso Minerals
Printed in Sweden
