Humidification & humidity control in paper & pulp production
Humidity control in the paper industry is essential to control the moisture loss of the paper after drying. Once produced and reeled, the paper can be exposed to ambient conditions at the end of the paper machine for considerable periods of time. Exposed surfaces of the paper will change in moisture content dependent on the ambient humidity, leading to problems during the slitting and wrapping processes.
Low humidity, below 50%, causes the paper to shrink, curl and lose dimensional stability making the reel of paper unusable and in turn very costly to the manufacturer. To stop this from occurring, the typical humidity level required is 55%rH. When this level is maintained the moisture in the paper maintains not only the flexibility of the product but also its stability during production and packing.
Low humidity in the slitting area will cause moisture losses to occur; these losses will take place very quickly. However, damage to the paper may not be seen at this stage as the tension on the paper prevents any curl or dimensional change being seen.
Changes to the paper in the slitting process will show at the sheeting stage because the tension has been taken off the paper and it is now free to change its shape.
When humidity is below 45%RH static electricity will be generated, which can cause packing issues and prevent a risk to staff from unexpected shocks.
- Arjowiggins, France
- Ceisa Packaging, France
- Portucel Soporcel, Portugal
- Fabrica Nacional de Moneda Y Timbre
- Rizla, UK
- Duni Paper Mills AB, Sweden
- Holmen Paper Mills AB, Sweden
- Modo Holmen Paper AB, Sweden
- Metsa Tissue as, Slovakia