Pulp dryers - rebuilding for added value

“We conduct many small and medium-sized rebuilds on existing pulp dryers, and we get many large assignments in which the entire dryer is essentially rebuilt from scratch. Increasing production is the most common reason for such projects, but they can also be aimed at reducing dust formation or streamlining the workload for operators, for example. Wear and outdated technology are further reasons for a dryer to be rebuilt,” says Project Manager Kari Koski.

A concept tailored to each customer

Valmet’s Airborne Dryer concept is module-based, and can be adapted for each customer and each dryer, whether the dryer is relatively new or old, large or small.

Valmet Booster Dryer offers extreme flexibility in expansions.

A typical rebuild may consist of replacing or adding blow boxes, fans and end towers to increase the drying capacity. The conversion may also include upgrading to automatic tail threading to minimize downtime. The dryer can also be upgraded with smart technology that reduces dust formation and increases runnability.

Valmet has several booster dryer solutions to increase production capacity.

“All rebuilds are quite different,” comments Koski. “For example, we might replace fans, steam coils and access hatches, or automate tail threading. A rebuild might also entail building new drying decks in the upper part to increase evaporation capacity or improve heat recovery. No matter what the issue is, we can make any dryer maximally competitive with the latest innovations.”

An important task for Valmet is to reduce customers’ investment and operating costs. All conversions and upgrades are therefore tailored to keep the project’s total costs to a minimum, while the technology added must provide the lowest possible operating costs.

Booster dryers – increased production via a space-efficient solution

You may have several reasons to rebuild a dryer, the most common being to increase your production capacity. With Valmet’s Booster Dryer solutions, pulp output can be increased with a targeted extension that is placed on top of, after or inside the existing dryer. The one you choose will depend on your particular needs.

Adding a Booster Dryer extension on top of or after the dryer can be done on almost any pulp dryer. On the other hand, if you want to add capacity inside the dryer, space must be reserved for this during the original planning when it is built. It is thus already prepared for a capacity increase, which is easy to do when needed. An additional advantage with this solution is that there is no need to increase the dryer’s physical size or footprint. Because of the extreme flexibility it offers, and as each project is unique, there has been great interest in the Valmet Booster Dryer for expansions.

Kari Koski, Project Manager at Valmet.

Rebuilding and upgrading of "non-Valmet" dryers

It isn’t just Valmet’s dryers that are being rebuilt and further developed.

“More and more assignments involve rebuilds of non-Valmet dryers. The mill wants to keep the dryer frame but upgrade it with selected parts from the Valmet Airborne Dryer technology. Customers are well acquainted with our expertise and technical innovation,” says Koski. “Such an assignment is especially stimulating, because we have the confidence to develop a technical solution that is not originally our own. To do this, we start with a feasibility study in which we thoroughly analyze the existing dryer and then carefully develop our plan. This lays the foundation for a successful end result.”

When the unexpected happens

A conversion project can be especially demanding when the work is carried out while the dryer is in operation. Planning and project management are therefore very important. Kari Koski explains: “Careful planning and proactive project management are of great importance for the project to run smoothly and well. We have extensive experience of carrying out renovations and planning the work to minimize downtime.”

But even if everything is prepared and planned in detail, unexpected things can happen.

“Regardless of whether it’s on a weekday, a Saturday evening or a holiday, we always act quickly. We earn our customers’ trust, and we ensure this trust is well managed,” concludes Koski.

Text Kristofer Sjöblom and Hugh O’Brian
Photos Lars Berggren and Hannes Frigård