Tissue, towel and paper manufacturing and converting produces a significant amount of airborne dust. Paper dust, if allowed to reach higher concentration, is a nuisance, fire and health risk. Dust Control and Exhaust Systems have been proven as the best way to contain and remove the dust from the machine room. The primary function of a dust control system is to cut the amount of airborne dust particles to improve the environment for the employees, prevent operation and maintenance problems that lead to poor sheet quality and frequent downtime for cleaning and lower dust accumulation on the flat surfaces.
Airtherm offers custom Dust Control and Collection Systems for new and existing paper machines and rewinders. An Airtherm Dust Control system uses custom pick-up hoods to improve the dust collection effectiveness. Once the dust is in the conveying air, it is removed from the airstream before exhausting either to the atmosphere or back into the building. Airtherm offers three types of dust collectors; a baghouse, a rotary drum filter and a wet venturi scrubber.
Optional vacuum methods, floor treatments, air bars, sheet stabilizing foils, sheet cleaners, broke/trim handling systems, ionization bars and exhaust enclosures for dust containment are available to optimize the control system performance. Isolation valves, spark detection and suppression systems are also available for increased hazard protection.
Vacuum Methods – There has been a concerted effort to encourage vacuuming of dust around the manufacturing and rewinder machines instead of using the traditional “blowdown” method with compressed air. Blowing down a machine “launches” a large amount of dust into the air resulting in a cloud that simply sends the dust to settle somewhere else. Using a powerful vacuum system first removes the bulk of the dust from easy accessible surfaces. Tight, hard-to-reach spots can then be cleaned with crevice tools or minimal compressed air pressure to do the job. There are several ways to use vacuum cleaning:
Floor Treatments – Floor mounted collectors come in two different styles:
Air Bars – Strategically placed air dispensers that motivate dust towards a desired collection area. Air bars come in several styles:
Sheet Stabilizing Foils – Full sheet width or partial foils; static or dynamic designed to control sheet flutter, floppy edges, sheet spreading or simply an alternative to an idler roll to support the sheet. Sheet Stabilizers have been successfully used to tackle control issues on machines with speeds up to 6,000 FPM and sheet widths of up to 200″.
Sheet Cleaners – Includes dynamic stabilizing foils to dislodge the surface dust from the sheet and an exhaust hood to convey the dust laden air into the collection system. Ionization bars mounted upstream of the sheet cleaner can improve cleaning of even the toughest dust deposits.
Broke/Trim Handling Systems – Injector type or direct conveying with the use of a chopper fan, the systems design allows it to carry continuous or chopped trim ribbons from the machine to a pulper or baler. Designs for high-speed systems up to 7,000 FPM with various sheet weights and trim ribbon widths are available.
Ionization Bars – Used for eliminating static charges that hold the dust on the sheet. These bars allow for more thorough removal of dust in the sheet. When combined with a compressed air knife, the neutralizing ions cover a greater distance for even better performance.
Exhaust Enclosures – Custom fabricated enclosures for dust and fume capture are stainless steel, painted mild steel or aluminum and include full width exhaust. The enclosures are single thickness or insulated and include access doors, viewing windows, lighting and sprinkler systems.
Isolation Valves – Flow activated, passive inlet isolation valves are used to protect downstream work areas and processes from exposure to flame and pressure through the inlet duct if a deflagration (explosion) occurs in a dust collector.
Spark Detection and Suppression Systems – For an added level of safety, a spark detection and suppression system is available. In general, these systems might not be specifically required by the NFPA or insurance providers, but add increased fire and deflagration hazard protection.