Dryer fabrics

Dryer fabrics are utilised as the medium to transport the paper web through the 

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Other Disposable Applications. There are many other disposable appHcations for spunbonded fabrics including fiber bale wrap, metal core wrap, wipes, and clothes dryer fabric softener sheets. 

A reverse-wipe appHcation is seen ia the clothes dryer fabric softener sheet whereia the spunbonded fabric is coated with a complex combination of compounds that are released iato the environment of a hot clothes dryer to soften and perfume the clothes, as weU as provide an antistatic quaHty. The spunbonded sheet, which must be made of polyester or nylon for temperature resistance, provides a simple and cost-effective medium to store the chemical compounds prior to release ia the dryer. 

The application of very high-permeability dryer fabrics in the paper industry made it possible to introduce air through the fabrics. Therefore, the above-mentioned blowing rolls and the hot air ducts below (or above) the felt rolls between the cylinders became very popular. These systems provide better crossflow ventilation, which in turn results in more uniform and higher mass-transfer rates. 

The advantages of dryer fabrics can be summarized [23] as (1) increased drying capacity, (2) uniform moisture profile, (3) improved runnability and easier cleaning, (4) increased running life, (5) no fiber shedding, and (6) elimination of felt dryers. 

E. Barber. Xerium Dryer Fabric Cleaning, www.xerium.com [consulted in 2011]. 

Synthetic forming, press and dryer fabrics to best customize the fabrics to the requirements of application for uniform dewatering, smooth web surface structure and long lifetime... 

In the dryer section the dryer fabric has to ensure the undisturbed web transfer through the section, to enhance contact heat transfer from the cyhnder surface to the web and to reduce web shrinkage in CD. 

Safe, fast installation. All dryer fabrics are joined on the paper machine. 

Fig. 6.25 Cross section of a dryer fabric for high speed machines (source Voith).

Before the invention of man-made fibers, dryer fabrics were made from natural materials such as cotton. 

Advances in chemistry saw the invention of polyesters and polyamides. These materials could be spun and formed into monofilaments. Polyester quickly became the preferred choice for dryer fabrics. 

State of the art dryer fabrics are made from either polyester based polymer derivatives or polyphenylene sulfide (PPS). PPS material is inert to the environmental conditions encountered in a paper machine. This material would be used for the construction of fabrics running on the hotter, more humid machines, e.g. packaging machines. 

Dryer fabrics comprise machine direction (warp) yams and cross machine direction (weft). These yarns may comprise monofilament, multifilament, spun, plied (twisted) etc. Figure 6.25 shows a dryer fabric suitable for high speed, state of the art paper machines. 

Dryer fabrics may also be produced by Hnking a series of alternating left- and right-handed spiral monofilaments. The spirals are Hnked together by a connecting monofilament Figure 6.26 shows a spiral fabric design. 

Dryer fabrics are woven as a continuous, flat fabric The machine direction warp yarns are held on canister spools at the back of the loom and passed through a series of reeds and sheds (spacers and pattern makers). During the weaving process sheds are raised and lowered according to the desired final weave pattern. 

The fabric is removed from the loom and relaxed and stabilised through the use of heat and tension. A typical heat setting temperature is 180-200 °C for dryer fabrics. The tension is set according to the running tension on the paper machine section to which the fabric will be applied. 

Dryer fabrics typically range between 1.2 and 2.5 mm in thickness, depending on the fabric design required for the application. Their weight is typically 800-1500 g... 

Dryer fabrics are typically supplied through the application range GOcfm to around 100 cfm. 

The state-of-the-art dryer section for a high-speed paper machine has a singletier configuration with steam heated cylinders in the top row and suction rolls in the bottom row. The paper web is always supported by the dryer fabric and runs jointly around the drying cyHnders and suction roUs (Fig. 6.55). In the top row the paper web is pressed against the drying cyHnders by the dryer fabric. In the bottom... 

In the field of dryer fabrics excessive air entrainment at high machine speeds had to be reduced without losing drying capacity by decreased air permeability of... 

Bottiglieri, Pushing performance limits with dryer fabrics. Solutions November 2003. 

Performance of Spray Dryer/Fabric Flltar System for SO2 Absorption... 

Huang, H., Allen, J.W., and Livengood, C. D., 1988, Combined Nitrogen Oxides/Sulfur Dioxide Control in a Spray-Dryer/Fabric-Filter System, ANL/ESD TM-8, Argonne National Laboratory, Argonne, IL, November. 

Use Level 200-500 ppm (continuous applic.), 5-10% (on dryer fabrics) Environmental Biodeg. 

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