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Cooking of Cellulose and Residues on a Pilot Scale

The pilot digester is a central component of the process within the pulp and paper industry, and its flexibility is crucial for meeting various requirements and needs that may arise in production conditions. At RISE, we have dedicated significant resources to develop and enhance our digester, resulting in a high degree of flexibility and efficiency


Over the years, we have worked intensively to develop and refine our methods and equipment for simulating all commercial cooking methods used within the industry. This includes methods for sulfate cooking, sulfite cooking, and other common techniques. We have placed great emphasis on ensuring that our digester can replicate real production conditions as accurately as possible to provide credible and useful results.

RISE has extensive experience in working with various digester systems and has a deep understanding of their function and characteristics. We have conducted extensive research and development in both sulfate and sulfite cooking, and our work spans the entire spectrum of the process, from raw material pretreatment to the final pulp.

By continuously engaging in improvements in digester technology and processes, we always strive to be at the forefront of the industry and to offer our customers the most efficient and innovative solutions. We are dedicated to supporting the growth and development of the pulp and paper industry by providing reliable and high-quality services and expertise.

Samples of wood chips and cooking liquor from the factory are used to mimic the existing digester in the laboratory environment under controlled conditions. These digesters can also function as reactors in biorefinery investigations.

Wood chips from different wood species and of various sizes can be cooked simultaneously in the same digester under identical process conditions while being kept separate. Variations of process parameters such as time, temperature, concentration of cooking liquors, and cooking methods can be implemented. During the cooking process, both removal and addition of cooking liquors can be performed. Both batch and continuous cooking can be simulated.

The digester consists of a digester body and nine accumulators for cooking liquors. It can be filled with up to 10 kg of wood chips, providing enough pulp for subsequent process steps such as bleaching and papermaking, among others.

The cookery is ideal for wood examinations and can be used for warranty runs.

Wood variations:

  • Firewood
  • Tree part (root - top)
  • Age (juvenile -mature)
  • Chemical composition
  • Dimensions
  • Forest rot
  • Storage rot
  • Dryness
  • Size distribution
  • Impurities
  • Density
  • •Brightness

Wood handling

  • Firewood and firewood storage
  • Debarking
  • Chipping
  • Chip storage
  • Wood chip screening
  • Bark content
  • Wood content in bark fraction
  • Dry-raw density


  • Chipping
  • Chip storage
  • Wood chip screening
  • Lignin
  • Hemicellulose
  • Alkaline hydrolysis
  • Continuous boiling
  • Batch boiling
  • Dangerous smelly pollutants
  • Laundry
  • Straining


Within the analysis domain, various measurements and assessments are conducted to carefully evaluate the properties of the produced pulp. Some of the most important analyses include:

Kappa Number

ISO Brightness
Kraft Lignin
Fibre Dimensions

By performing these analyses carefully and regularly, one can ensure consistent production quality and identify any areas for improvement within the pulp and paper industry.


RISE offers a report that includes data in Excel format and relevant images and diagrams. It is carefully compiled using standard methods for the conducted analyses. The report also includes an assessment of measurement uncertainty to ensure the reliability of the presented results. All relevant parameters significant to the specific analysis are included to provide a comprehensive picture of the situation. Additionally, detailed comments and explanations are provided to offer further insight and understanding of the presented data.

Standard Report (Quotation):

RISE provides a comprehensive report where results are presented in a clear manner through concise but informative sections with clear diagrams and tables. This report structure is designed to make it easy for customers and stakeholders to quickly grasp the presented results without having to delve into extensive texts.

In-depth Report (Quotation):

If desired, there is an option for a more detailed report on quotation where RISE has the capacity to create a more detailed scientific report based on the results and background information provided by the customer. This report may include an in-depth analysis of data, extensive discussions on methodology and results, as well as a thorough assessment of relevant factors and contexts. By utilizing the latest research and expertise in the field, RISE can provide a thorough understanding of the observed results and their implications.


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Cooking of Cellulose and Residues on a Pilot Scale

Field measurements



There is also the possibility to conduct fibre line surveys directly on-site at the mill. These surveys may encompass various aspects of the fiber line processes and efficiency to identify any areas for improvement or optimize existing processes.

We offer tailor-made solutions depending on the customer's needs and specific goals. By conducting surveys on-site at the mill, we gain a deeper understanding of the current situation and can provide more precise recommendations and actions to improve the production process.

If you are interested in fibre line surveys or would like more information on how we can assist, please feel free to contact us. We look forward to discussing your needs and challenges to find the best solutions for your operation.


Price on tender

Delivery time

The delivery of results is scheduled based on our order backlog and the scope as well as the complexity of your assignment. We aim to ensure that your results are delivered on time, taking into account the specific requirements of your project. Thank you for your understanding and patience as we work to provide you with the best possible service.

Supports the UN sustainability goals

6. Clean water and sanitation
7. Affordable and clean energy
8. Decent work and economic growth
9. Industry, innovation and infrastructure
11. Sustainable cities and communities
12. Responsible consumption and production
13. Climate action
14. Life below water

Contact person

Mats Westin

Forsknings- och utvecklingsingenjör

+46 10 722 32 49

Read more about Mats

Contact Mats
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Lars Sundvall

Contact person

Lars Sundvall

Gruppchef Processteknik

+46 70 526 52 21

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