This research project contains process modelling and full-scale evaluation of new segment design in a refiner for paper industry.


In manufacturing of High Yield Pulps from wood chips, the thermomechanical pulps (TMP) or chemithermomechanical pulps (CTMP) fibres are separated. This from the wood structure in intense treatments of friction, shear and compression in a narrow gap between rotating, patterned discs, segments, in a refiner.

The approach we will use in this project is to develop new methods (measurement, testing and simulation/modelling techniques) that can be used in the research area of mechanical pulping and other contexts. In order to study the refining process at particle level (deformation, steam, generation, collision, friction etc) we will use particle based modelling methods which is an emerging field of engineering with a large audience. It will be important for future research and develop deepend understanding for the refining process.

We will develop measurement and testing techniques that can be applied to both wood and other materials. Modelling will be an essential tool to understand the mechanics and rheology of the refiner process owing to the difficulties of measuring in the challenging environment in the refiner. Modelling is also the future of product development: and essential to manufacturing 2.0 and to any engineer actively involved in product development.

The main question will be; How is energy transferred from the refiner segments to the wood chips and fibres?

The purpose of the refiner segment design is to introduce forces to the pulp and to transport the three-phase-mixture of steam, water and fibre materials from the inlet to the discharge. To facilitate the fiber separation the chips are pretreated by steam at pressurized conditions, TMP or CTMP. As an application a new segment design willl be studied for small refining gaps, based on research at FSCN during the past ten year period.

In conclusion the scientific objectives of the project will be;

1. understanding the rheological basis of the differences in energy transfer efficiency that are seen when segment designs are compared.

2. from the ability to simulate different disturbances, find explanations of instability/stability when operating at small refiner gaps by using particle based methods, coupled CFD-DEM and experimental data.

Solving these questions will enable the projects technical objective , which is to increase efficiency in energy transfer between the refiner segments and the fiber material by 30% and at the same time stabilize refining at small refiner gaps.


Project period


Project leader

Birgitta Engberg


010-142 88 97

Project members

Per Engstrand


010-142 86 49

Johan Persson


010-142 78 94

Jan-Erik Berg


010-142 84 15