Vacuum filters. Established for industrial dewatering

Transcription

1 Vacuum filters Established for industrial dewatering

2 Vacuum filters

3 Vacuum filters Vacuum filtration is a well established technique used in industrial dewatering. Metso has successfully delivered and installed many hundreds of rotary vacuum filters covering a wide field of applications. All rotary vacuum filters operate on a similar principle. A pressure differential between the surface and inside of the drum (or disc) is applied by means of vacuum. This pressure differential causes transport of liquid through the filtration surface while the filter medium arrests solid particles and a cake is formed. As the drum rotates, the cake rises above the slurry level in the filter tank and air is drawn through the cake, forcing out liquid. The liquid (filtrate) exits the filter through the internal piping and the vacuum head. giam Top Feed Drum Filter. Drum Filter. Disc Filter. Belt Drum Filter Comparison of suitable equipment for different particle size distribution and residual moisture. Principal components of the drum filter model TF. Drum. Drum drive. Support Frame. Tank. Vacuum Head 6. Agitator 6 Pressure differential causes transport of liquid through the filtration surface while the filter medium arrests solid particles and a cake is formed. The range of rotary vacuum filters incorporates two basic design principles: High vacuum air flowrates The Metso filters are specially designed for high vacuum operation allowing very high air flowrates. This results in: Higher capacities Lower cake moisture Extended application range Integrated components Modularized components and equipment results in: Flexibility in machine configuration Features may be added or altered to accommodate process changes Construction from proven, standard components Simplified maintenance and parts replacement Lower equipment and operating costs Vacuum filters

4 Options and accessories for TF and TFF filters Wire winding attachment For certain applications filter 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 lengths Feed wire drum may be placed in any location near the filter Adjustable wire tensioning brake on guide wheel Manual vari-speed drive as optional extra. Wire guide wheel. Guide trolley and main beam. Drive motor assembly. Idler sprocket assembly. Trolley drive chain 6. Feed wire drum and support trestle 6 Snap blow cake discharge system. Induction transmitter. Control box. Cog wheel on drum drive shaft. Sector at cake discharge point. Solenoid valve and air connection to vacuum valve A short duration pulse of compressed air injected into each filter sector immediately prior to the cake discharge point provides for: positive discharge of thick or sticky cakes cleaning of filter cloth short pulse inhibits blow back of filtrate into dry cake 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. Construction materials Depending upon application drum filters are available in carbon steel and stainless steel. Cake washing Spray bars may be fitted to wash the cake in the dewatering zone. Typically, the wash liquor joins the primary filtrate; however separate discharge of liquor and primary filtrate is possible. Cake washing For lower moisture cake requirements a sealed hood may be fitted to pass superheated steam through the cake in the dewatering zone. Cake repulper Where the downstream process dictates, the drum filter may be fitted with water/liquor spray bars and cake re pulping screw. The screw is driven by a separate motor and gear reducer. The screw shaft is mounted in anti friction bearings and sealed using mechanical (standard) or hydraulics means. Drum filter with repulper attachments. Vacuum filters

5 Standard features model TF Drum Rugged all welded steel construction Diameters from 00 to 60 mm Snap in re placable segment grids Inspection/access manhole, drain and vacuum leakage tell-tale Selection of four drainage systems with capacities up to 0 m / min at max. 8 m/s flow velocity which minimizes internal pipe wear and reduces friction losses Two separate drainage pipes per drum sector, to prevent liquid puff back when using snap-blow cake discharge. Drum drive Standard -pole AC-motor, integral gear reducer and manual speed variator Standard drum speed range 0. to.0 rpm Rubber compression pad to absorb shock loads on start-up Support frame Standard steel section all welded support frame One piece drum drive trestle bolted to the support frame 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 Central lubricator Automatic grease lubrication to vacuum head and bearings High capacity drum filter. (Note the size of vacuum head) Vacuum head Thick (0 mm) cast iron alloy or HD polyethylene wear ring and mating housing to allow for re machining Three adjustable pressure springs for positive sealing between head and wear ring Selection of heads to match each liquid drainage system Drum support shaft assembly Full length shaft to support drum, vacuum head and internal drainage tubes Ring feeder tensioning element connection to drum heads Selection of three systems depending upon filter size, vacuum head and machine capacity Agitator 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 -pole AC-drive motor and gear reduction box Drive motor, gear box and lower crank bearings are protected from spillages by removable inspection covers. TF 0 Rotary Drum Filters during shop assembly Vacuum filters

6 Belt drum filter model BTF Belt drum filters, model BTF, are identical in all respects to the TF range with one fundamental exception: cake discharge. With the belt drum filter 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 pick-up zone. The three key system features of the belt drum filter are thus: cake discharge cloth washing cloth tracking Cloth washing system Cloth washing increases the capacity of the filter and extends the cloth service 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 confined 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 Cake discharge systems In many applications the simple break roller system, where the cloth is passed over a small diameter roller, is sufficient to effectively break the cake away from the cloth for discharge. For more difficult cakes an air-knife may be appropriate. The air-knife consists essentially of two hardened steel (or other wear material) lips. The leading lip is proud of the following one and together they form a slot across the full cloth width. Compressed air from an air blower or high pressure fan is injected into the knife tube and exits from the slot onto the back of the cloth. This cake discharge system is very effective for thin and/or sticky cakes.. Cake discharge system counter weight and lever arms. Pneumatic diaphragm cylinder. Cylinder tensioning spring. Optical or pneumatic cloth edge sensor. Guide pulley A combination roller and air-knife discharge system is also available for difficult applications. This type of discharge, in which the clearances between the air-knife lips and the cloth is adjustable, avoids wear and replacement of the knife lips in abrasive duties. In addition there are often benefits in cloth cleaning by reduction in wash water consumption. 6 Vacuum filters

7 Top feed drum filters model TFF The top feed drum filter, 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 filtration 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 features include: special seal between feed box and drum prevents leakage of feed and reduces mechanical wear of filter cloth snap-blow cake discharge Optional features: high pressure water, air or water/air mixture cloth cleaning between cake discharge and feed point. System supply Typical vacuum filter system with filtrate pump and vacuum receiver... Vacuum receiver. Moisture trap (Normally used for aggresive filtrate only). Vacuum pump.. Liquid separator. Silencer 6. Filtrate pump 7. Floor drain For plants without a filtrate pump: Drain line from vacuum tank (barometric leg) 9. Water lock Contact you local Metso office for further information about vacuum filters Vacuum filters 7

8 Metso Sweden AB Norrängsgatan, SE-7 8 Sala, Sweden, Phone: , Fax: Metso Minerals Industries, Inc. 7 Pleasent Valley Road, York, PA 70, USA, Phone: Metso Minerals (South Africa) (Pty) Ltd. Private Bag X006, Isando, Johannesburg,600, South Africa, Phone: , Fax: Metso Minerals (Australia) Ltd. Level, 0 Hay Street, West Perth, WA 600, Australia, Phone: , Fax: Metso Minerals (India) Pvt Ltd th floor, DLF Building No. 0, Tower A, DLF Cyber City, Phase - III, Gurgaon - 00, India, Phone: +9, Fax: Metso Perú S.A. Calle Nro., Urb. Industrial Vulcano, Ate, Lima 0, Peru, Phone: + 66, Fax: Metso Minerals (Chile) S.A. Av. Los Conquistadores 78, Piso, Providencia, Santiago, Chile, Phone: , Fax: Metso Brasil Indústria e Comércio Ltda. Av. Independência, 00 Éden, Sorocaba-SP - Brazil, Phone: minerals.info@metso.com Metso Corporation, Fabianinkatu 9 A, P.O. Box 0, FI-000 Helsinki, Finland, tel , fax , Subject to alteration without prior notice Brochure No ESBL/Sala-English 0 Metso Printed in Sweden