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Valmet's Improved Systems Increase Dewatering, Reduce Vacuum Needs

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The combination of Valmet Hard Coating Solid and the perforated Valmet Uhle Box Cover have proven to increase dewatering at current vacuum levels, or reduce vacuum needs at many mills.

Valmet Hard Coating Solid
Valmet Hard Coating Solid (earlier known as SolidCoat) dewatering elements are hard-coated stainless steel components that cover the full width of the machine line. The surface of the components is solid, uniform and continuous without harmful joints on the fabric contacting surface. These dewatering elements are an excellent alternative when a mill is seeking energy savings, better paper quality and reliability.

Technology Behind The New Coating
Valmet Hard Coating Solid comprises two layers - a metallic bond layer and a ceramic layer - over the stainless steel body being coated. The metallic bond layer is fourth generation HVAF applied ~100% dense corrosion resistant metal (less than 0.1% void volume). This layer acts as a transitional bond layer between the ceramic layer and the vacuum element body, as well as a corrosion resistant barrier. It improves bonding of ceramic to steel and prevents corrosion for optimum cover life.

The ceramic layer has engineered surface properties to maximize wear resistance and surface cleanliness. The optimized wear resistance is 1200-1300 HV3. The ceramic powders and sealing compounds are proprietary materials developed by Valmet.

Valmet Hard Coating Solid is used on new and existing machines at many locations, including uhle box covers, transfer suction box covers, vacuum forming boards, and many more. It is designed for gentle fabric contact, withstands all process chemicals and is thermal shock / impact resistant.

Valmet Uhle Box Cover
The perforated Valmet Uhle Box Cover coated with Valmet Hard Coating Solid is an effective and straight-forward solution to increase dewatering and reduce energy consumption in the press section. The sheet undergoes a long dwell time in the vacuum zone, increasing the felt dewatering at a lower vacuum level than a traditional slotted cover. The friction between the cover and the felt is decreased.

The Valmet Uhle Box Cover is recommended for mills with energy savings targets or runnability issues in the press section, especially if there is too much water for the 1st press to handle. Mills running board grades where the main part of the dewatering is done with uhle boxes find the Valmet Uhle Box Cover valuable, especially if they are using or want to use seamed felts. Mills making heavier paper grades, where the use of uhle boxes is essential for machine performance, are also choosing Valmet Uhle Box Cover to improve their operations.

  • Using the perforated Valmet Uhle Box Cover, mills can expect cost savings and benefits through:
  • Increased dewatering
  • Better runnability
  • Better profiles
  • Lower friction and lower press drive load
  • Longer felt lifetime and longer felt change intervals

Source: Valmet 


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