At the end of this module, you will be able to:
- Describe the function of a press felt
- Explain the importance of proper felt cleaning and conditioning
- Identify and describe the equipment used for wet felt cleaning and conditioning
- Describe the function/ purpose of the wet felt cleaning and conditioning equipment
- Describe the best practice locations for wet felt uhle boxes and showers
- Describe the different shower types
The following key questions are answered in this module:
Why are press felts usually replaced?
Press felts are usually replaced because they have either filled with contaminants or have compacted to the point that their dewatering capacity is insufficient
How many showers and uhle boxes are typically used on each press felt?
A typical system utilizes 3 or 4 showers on each wet felt, followed by one or two uhle boxes
Where are the lubricating showers installed in press felt runs?
A lube shower is usually installed ahead of each uhle box to help reduce wear on the felt and box cover, and also act as a seal at the uhle box. They should spray into the ingoing nip.
Why are high pressure needle jet showers on press felts oscillated from front to back?
They are oscillated in the cross-machine direction to evenly distribute the water and prevent damage to the felts; these showers should be interlocked to shut off if the oscillator or press section stops
Where are uhle boxes typically positioned?
Uhle boxes are usually located on the face- or sheet-side of the felt after the press nip and all major showers
Below is a transcript of the video sample provided for this module:
Press felts do not typically wear out. Instead, they are usually replaced because they have either filled with contaminants or have compacted to the point that they're dewatering capacity is insufficient. It is the job of the Felt Cleaning and Conditioning System to maintain the felts void volume and caliper or thickness. This allows the felt to absorb and to then release water uniformly during press operation.
Use the additional resources and links below to learn more about this topic: