Offering a variety of services for the pulp drying process, including workshop reconditioning services, rolls, roll covers as well as roll maintenance and upgrade services, industrial equipment supplier Valmet aims to improve pulp drying performance at customer sites around the world.

Valmet roll covers and maintenance global technology manager Ulla Kanerva explains that there are about 300 pulp drying lines in operation globally, with 120 of them being Valmet’s own installed base.

“With our expertise and know-how, we are, however, totally capable of servicing competitor equipment as well. With Valmet’s services, our customers can maximise the availability of their pulp dying,” states Kanerva.

Further, owing to its long experience in the services business, Valmet’s specialists have solved many customer challenges.

Valmet says its services are designed to meet its customers’ needs throughout the entire life cycle of their pulp drying line, securing stable running with minimum unplanned shutdowns.

As such, its solutions enhance energy efficiency, cost efficiency, material efficiency and safety, thereby improving the sustainability of customer operations.

To further boost sustainability, Valmet offers a variety of cost-effective reconditioning services that also help to diminish the carbon footprint of pulp producers.

Valmet workshop services global technology manager Jarmo Viitaharju notes, for example, that when a rotor is reconditioned, its screening performance is “as good as if it [were] new”. Its capacity is also brought back to the “desired level”, maintaining operational efficiency.

“By choosing reconditioning instead of manufacturing a new rotor, CO₂ emissions are reduced by 3.7 t  per unit,” states Viitaharju.

Additionally, the process saves 90% of the steel material required for production, reducing demand for raw materials as well as the environmental impact.

Cleaning Shower Upgrade

In a case study, Valmet found that suction rolls have the tendency of drawing pulp into the suction box internals and into the space between the suction box and the shell.

This additional mass can limit suction roll dewatering capacity and impede the rotation of the shell, which, in turn, necessitates greater driving power.

A Valmet customer’s mills struggled with a short roll change interval, of just a year, as a result of pulp mass accumulation in the suction box. To improve the situation, Valmet proposed and delivered a suction box cleaning shower upgrade. In the upgrade, the suction roll was equipped with an additional shower that clears excess paper pulp, reducing the need for maintenance and cleaning.

Following the upgrade, roll running time was extended from 12 to 24 months. Other benefits were longer maintenance intervals, improved energy efficiency and suction box dewatering, reduced moisture variation and extended axial seal life.

According to Valmet, in pulp production, quality and reliability are the key to profitability.

In 2023, a new pulp drying line was established at a joint venture between Austrian company Lenzing and Brazilian company Dexco, LD Celulose’s mill in Brazil, immediately leading to an “extraordinary achievement”.

The pulp drying line ran over 270 days without any web breaks. In addition to having the right machine design to handle the unique properties of the dissolving pulp, roll covers played an important role in the successful startup.

The pulp drying line was equipped, for example, with Valmet Press Roll Cover VT rubber covers on the wire turning roll and second press roll in a combi press, as the Valmet Press Roll Cover VT composite cover on the shoe counter roll.

Valmet concludes that the Valmet Press Roll Cover VT has been successfully applied in many greenfield pulp drying lines’ shoe counter rolls, reaching running times of as long as seven years.