Significant increase in white liquor production through recausticizing upgrade at Mondi Štětí

After discussing the customer’s needs and targets in detail, Valmet offered to deliver a comprehensive recausticizing upgrade including a new green liquor cooler, a centrifuge system including conveyors and chutes, a causticizer with agitator, a rebuild of an old Valmet PDW filter including a new compressor and a new control system, and a total rebuild of a competitor CD filter with new internals, a new compressor, and a new control system. Both filters were supplied with Valmet’s tailor-made filter bags. In addition to the technology, Valmet supplied advisory services during the installation and startup as well as training and maintenance support for the mill’s staff.

Filter conversion kit enables a significant white liquor production increase

Recausticizing is a series of complex processes that all affect one another – meaning it is often challenging to quantify the impact of individual improvements on the outcome. This time, however, the most important single improvement included in the recausticizing upgrade was inevitably the CD filter conversion.

Valmet has since 2014 successfully delivered conversion kits for competitor filters enabling a production increase of around 25-35 % higher than the original design while also leading to increased availability, easier maintenance and lower spare part cost. At Mondi Štětí, the filter conversion led to outstanding results.

“The design capacity of the mill’s current CD filter was 2800 m3/d, and we expected to experience a new capacity of around or a little bit above 4000 m3/d. It’s fair to say that we were all pleased about the actual result: the maximum new capacity during test run was as much as 4879 m3/d and around 4600 m3/d during the first week,” explains Christian Mitander, Project Manager at Valmet.

Good cooperation leads to success

The commissioning and start-up of the newly upgraded and installed equipment went smoothly with Valmet’s on-site support. Christian Mitander says that the project is a good example of what can be achieved through good cooperation with the customer but also within Valmet.

“Due to the complexity of the project, we could really use the expertise and strengths of the entire project team. Thanks to the commitment and can-do attitude of everyone involved, we were able to deliver results beyond expectations.”

“As the customer, we valued the detailed planning of the project and the highly skilled and experienced Valmet personnel – their ability to make rational decisions also under stressful circumstances during the brownfield installation kept the wheels rolling. We hope to continue the good cooperation in the future and look forward to the next projects with Valmet,” says Rostislav Holovčák, Area Manager, Recausticizing, at Mondi Štětí mill.