FABRIC FILTER BAGSFABRIC FILTER BAGS

Content•Filter media for dedusting•Fibers & Technologies •Type of Bags• Needle Felts •Woven Fabrics •Comparison between Needle Felt & Woven Fabric•Bags Manufacturing•Final & Surface treatment•Bag properties & Tests•Bag Failures•Applications•Advanced Technology

Filter media for dedustingTextile filter media starting from fibersTextile Technologies usually applied: Spun bonding Spun laced Thermal bonding Chemical bonding Warp-weft weaving Needling

yarn→ assembling→ twisting→ warping→ weaving→ tentering (water repellent, acid resist, germ resist, antistatic) → cutting→ inspection→ warehousing

Fibers & Technologies •Polyester •Polyacrylic (homopolymer & copolymer)•Metaramid (Nomex, Conex) •Polyimide (P84®) •PPS (polyphenylene sulphide) •PCT (polycyloexilentereftalate)•Polypropylene (PP)•Polytetrafluoroethylene (PTFE) •Glass •Polyamide (PA)

Type of Bag Materials

Needle felts

A pulse-jet baghouse generally filters more air per cloth area (higher air-to-cloth ratio) than a shaker or reverse-air unit.Felted bags should not be used in high humidity situations, especially if the particles are hygroscopic (these particles have an affinity to absorb moisture and thus become sticky).Clogging or blinding could result in such situations.

Felted filters are usually used in pulse-jet baghouses

Staples Scrims Needle Loom state felt

NeedleFelts processing

Woven Fabrics Woven filters have open spaces around the fibers. The weave design used will depend on the intended application of the woven filter. Different weaving patterns increase or decrease the open spaces between the fibers. This will affect both fabric strength and permeability. A tight weave, for instance,has low permeability and is better for the capture of small particles at the cost of increased pressure drop.

The true filtering surface for the woven filter is not the bag itself, but the dust layer or filter cake. The bag simply provides the surface for capture of larger particles. Particles are collected by impaction or interception as the open areas in the weave are closed. This processis referred to as sieving.

Woven Fabric Features

Comparison between Needle Felt & Woven Fabric

> Baghouse Operating Type> Abrasion Resistance Needed> Resistance to Cleaning Energy> Gas Stream Chemistry> Air-to-Cloth Ratio

Development of Woven Fabric

Woven or Felt Selection Considerations

• Fibre glass <260° C• Homopolymer Acrylic (PAN) <130° C• Surface Foam Coated PAN <130° C• Polyphenylene Sulfar (PPS) <190° C• Blended PPS and PAN <135° C• Chemical Treatments

Development of Needled Fabrics• Homopolymer Acrylic(PAN) <130° C• Polyphenylene Sulfar (PPS) <190° C• PPS With surface Treatments <190° C• PPS with PTFE encapsulation <190° C• PPS with Blended or capped webs (P84) <190° C• PTFE (PTFE) <260° C

Bags ManufacturingLongitudinal cutting

Stitched Seam Thermowelded Seam

Tubing

Bags ManufacturingBag Top Design Bag Bottom Design

Surface treatment & Final Finishing

Needled Fabric with untreated surface

Needled Fabric with Singed surface

Commonly Treatment

standard heat settingflame singed on one side or on both sidesantibacterial impregnation*antistatic effect by steaming aluminium onto the dust sideantistatic by the admixture of stainless steel fibres according to DIN 54 345antistatic by the admixture of epitropic fibres according to DIN 54 345antistatic by the admixture of stainless steel + epitropic fibres according to DIN 54 345flame retardant Polyesterflame retardant impregnationsurface protection against sparks by a carbon fleece needled onto the dust sidesurface protection against sparks by a microporous foam coating carbon powdersmoothening of the dust side by calendering: light, medium & strongmicroporous foam coating on the dust side, for abrasive dust + high temperaturemicroporous stratification of Polyamideimpregnation that renders the pleating of needlefeltsoleophobic, hydrophobic, antiadhesive treatment giving resistance to acids and alkalisdeep coating on Teflon® basis giving resistance to acids and alkalisdeep coating on Teflon® basis giving resistance to acids and alkalismicroporous surface coating on Teflon® basis providing resistance to acids and alkalis and facilitating the cleaning of the filter bagsmicroporous PTFE membrane

Available Treatment List:

Bag properties & Tests

Bag Properties TestWeight ASTM D3776Construction A. Yarn Count ASTM D3775 B. Type of Weave ASTM D579Thickness ASTM D1777Tensile Strength ASTM D5035Mullen Burst ASTM D3786Permeability ASTM D737Organic Content (LOI) ASTM D578MIT Flex ASTM D2176Filtration Performance ASTM D6830Width ASTM D3774Water Repellency ASTM D2721Surface Resistance STM 11.11Volume Resistance STM 11.12Two-Point Resistance STM 11.13

Bag FailuresHydrolyses Bumping Cage Effect Misalign Blow pipe

Thermal Effect Pinching Lengthening Flow abrasion

Poor Seam Pinholes Top Abrasion Clean side Contamination

Applications (Cement Plant)QUARRYING / GRINDING

HOMOGENIZATION

Raw Material

ApplicationsCoke Mill

Cement Kiln

ApplicationsCement

Packing / Shopping

Advanced Technology

Questions