Analysis
The system is running above 100 oC, percentage of the vapour is beyond 10%, Hydrolysis to Polyester fiber is very strong. Volatile component from the hot coal powder contains Sulfur Oxide (SOx) attacks polyester molecule in particular the temperature below dewpoint.
Solution
ST Filter designed a new Filtermedia for this application:Scrim: 50%homopolymeric Polyacrylonitrile (DT)+50%Polyester (PE)
Fiber: 46%homopolymeric Polyacrylonitrile (DT)+46%Polyester (PE)+8%Stainless steel fiber
Polyester fibre gives the enough textile strength for the material as well as saving cost, while DT fiber contributes the chemical resistance against Hydrolysis and acid attacks.
Weight: 570g/m2In order to increase textile strength.Resistance value: <104¦¸. This figure is well below the maximum permissible resistance value of <108¦¸,which is stipulated for conductive filter materials. Permanent static dissipation by Stainless steel fiber even the filer bags are broken.
Section of the anti-static needlefelt
Surface treatment:
Heat seating¡ª180¡ãC shrink for 10 minutes. Thermally stable at a continuous operating temperature of 130¡ãC.
Singed ¡ªhelp the flow coal powder easy to remove from the surface of the bag.
Filter bag making: Tube body welding, cuff and bottom stitching by PTFE yarn. Since continuous temperature of DT is 125¡ãC, while the pick temp of the system is 130¡ãC, so DT yarn is not suitable. PE yarn is not suitable due to Hydrolysis and acid attacks. PPS yarn may oxidate while Hydrolysis may effect Aramid yarn.
So PTFE Yarn is recommended as the most suitable yarn. ST Filter¡¯s innovative Tube Welding technology saves the bag making cost for customer. PTFE yarn stitching on cuff snap ring and bottom reinforcement ensure the stitching tightly even the filter bags broken.Welding tube technology, ensure the lowest emission rate