Sleeve roll technology

The forming section is the biggest user of vacuum energy on paper and board machine lines. Until now, forming section drainage has relied on gravitation and dragging vacuum elements set along the forming fabric’s journey. Sleeve roll technology does not require vacuum energy, and therefore it saves energy in both the vacuum system and drives of the forming section. Data from production machines shows that the dewatering of the forming section with Sleeve roll technology is effective and that is clearly visible in the power consumption of drives and vacuum pressure. Dewatering on a board gap former has been up to 15 l/s/m, depending on the former speed and the web’s ingoing consistency in the Sleeve roll. A normal plain roll does not remove any water in this position. This results as forming section energy savings from drive power, that have been around 10 - 20% (500 kW) when there is no vacuum before the Sleeve roll.

Embrace efficiency, elevate quality – Choose Sleeve roll technology

Sleeve roll technology introduces a paradigm shift in forming section dewatering efficiency. By embracing compression rather than traditional vacuum-based methods, this innovation offers a range of compelling benefits:

• Energy efficiency: Say goodbye to excessive energy consumption. Sleeve roll's pressing mechanism significantly reduces power requirements, leading to substantial energy savings of up to 20%, which have been achieved in a new gap former installation with Sleeve roll technology. Lower CO2 emissions become a reality, contributing to your sustainability goals. A sustainable choice for both your operations and the environment.
• Enhanced quality: Elevate your product quality to new heights. Noticable formation improvements were seen on hybrid former rebuild with Sleeve roll technology. Pilot trials with hybrid former, board gap former and shoe and blade former with Sleeve roll technology have also demonstrated quality improvements in Huygen, SCT CD, density and dryness. Improved board quality leads to heightened customer satisfaction and market competitiveness.
• Improved performance: Embrace higher production capacities. Sleeve roll technology optimizes dewatering processes, minimizing downtime, and maximizing throughput. In a hybrid former rebuild time efficiency was improved as number of breaks and grade change time were decresed after the rebuild. Also, winder runnability was improved due to more stable dryness in MD and CD direction. In total, a 18% production incease was seen after the rebuild with Sleeve roll technology.

At the core of Sleeve roll's brilliance lies its dewatering principle. The idea is to compress a web between two forming fabrics against a small radius shoe. With this innovative technology the Sleeve roll achieves remarkable dewatering pressure levels of up to 150 kPa. With conventional forming section technologies, dewatering pressure is typically around 15 to 40 kPa, and with a couch roll or HiVac, it is typically around 60 to 70 kPa.

With the basic circle before the shoe of the Sleeve roll, the fabric tension creates moderate pressure. When passing over the variable radius shoe, the dewatering pressure increases steadily toward the maximum compressing pressure. The steadily increasing dewatering pressure in the Sleeve roll shoe causes no defects to the web, even with very low ingoing consistency.

This gentle yet effective approach of the Sleeve roll technology harnesses fabric tension and shoe interaction to gradually escalate dewatering pressure. The outcome? Efficient water removal without compromising paper integrity.

Unlike conventional methods that rely on vacuum systems, Sleeve roll's clever design minimizes friction and eliminates the need for a vacuum in the forming section. This translates to impressive energy savings and contributes to a greener manufacturing process.

Valmet Sleeve Roll Belt

An essential part of Sleeve roll technology is the elastic and durable polyurethane belt rotating around the roll. Valmet Sleeve Roll Belt is designed especially for this roll technology where the belt and forming fabric need to work together. The belt responds to the strict requirements (e.g. hardness, roughness, elasticity) of both the belt oil side and paper side surfaces.