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Pulp refining


This study concerns the development of a device measuring the concentration and analysing the lignocellulosic pulp refining used in the paper pulp, cardboard and fiberboard industries.

In the fiberboard panel and paper industries, a quality inspection of the pulp preparation is necessary. This inspection is generally based on two essential parameters : the concentration and the refining degree.

Most refining analysers currently available are based on the percolation principle : the fattening is stated by an index established from the passage time limit of an air or water volume through a pulp layer with or without differential pressure.

This index proves to be relevant for most industrial applications since it carries out the synthesis of a set of parameters (size of the fibres, granulometric distribution, fibrillation, ..) which, considered separately, are very hardly exploitable or expensive to carry out a quality inspection.

In order to be able to exploit the measurements of pulp refining analysers, it is necessary to carry out beforehand concentration measurements. Generally, these devices are adjusted for the analysis of pulp having a defined concentration ; the refining degree is determined by means of tables calculated to that purpose.

The Agricultural Engineering Department developed a measuring method and conceived the principle of a device, hereafter called by the initials CSR, capable of carrying out a quality inspection of the pulp on line or punctual at different posts or steps of the pulp manufacturing.


This feasibility study aims at analysing the project’s viability, as for its technical and economic aspects. A patent study including an anteriority research and a costs and possibilities analysis concerning the patent complete the techno-economic study. It shows the patent potential of the method.

The experimental phase put forward the possibilities of the method and the processes used, but the installation and tests on the definitive device will only take place after reception of the manufacturer’s equipment (ITDI).

Description of tasks

In order to carry out this study, it was necessary to take an interest in the problems met by the enterprises concerned by the concentration and lignocellulosic pulp refining measures and by the devices available on the market.

Concerning the measuring devices available on the market, a survey was carried out among manufacturers in order to obtain :
- all the possible technical information on the methods and functioning principles of the devices, novelties, etc. ;
- the prices and sale conditions, special offers, discount, price reduction, etc. ;
- the characteristics of the circuits and distribution means.

Besides this step, the CRA-W carried out : the patent study, the techno-economic feasibility study, the preliminary study of the measuring principle and the specifications.

Results obtained

The market identified by the survey shows that the future of equipments measuring the concentration and analysing the refining is based on automated processes, with on line data management in order to obtain an automatic and reliable inspection of manufacturing processes.

The survey identified the specialized manufacturers as well as the most used products industrially having more or less the same functions as CSR. The analysis of the selling price for the device has been carried out.

The survey counted an important potential of producers and users of lignocellulosic fibres susceptible of being interested in the device : 35 in Belgium, 150 in France, 330 for the EU.

The process and measuring method made it a polyvalent device, capable of analysing at high speed a whole sample coming from different preparation steps or from different sampling posts (recycling water, pulp and grinding up devices, etc.).

The device carries out simultaneously on a same pulp sample, concentration and refining degree measurements with interactive correction of the measurements. A special process makes it possible to carry out, also on a same sample, an assessment of the fattening level imputable to a fermentation, that is, to a development of micro-organisms in the pulp.

The fattening measurement being closely dependent on the concentration, the data of the CSR integrates all its fluctuations with precision, since the measurements are carried out on the same sample.

The measurements are carried out by data acquisition of continuous mass loss.
In order to determine the refining degree, the data acquisition registers the initial speed of water elimination of the pulp.

In order to determine the concentration, the mass of humid pulp, for a given percolation time limit, makes it possible to calculate the mass of dry matter via correlations by type of pulp. To determine the fattening imputable to a fermentation, the double measurement process assesses the difference of percolation time limit. The difference between the signals of refining degree determines a pulp fermentation index imputable to a development of micro organisms in the pulp. Over a certain level, the device is going to take it into account to take several steps appropriate to the application : biocide injection, partial or total emptying of the recycling water volume.

This characterisation of the pulp therefore generates three signals, usable at different manufacturing posts, in order to regulate on line, parameters such as the concentrations of the ingredients, the refining duration, if need be the cooking parameters, the optimization of the biocide dosage, the inspection of recycling waters.


IDTI Industrial Technologies Integration, Ministry of the Walloon Region - DGTRE General Directorate of Research and Industry

CRAW off coordinator

TEMMERMAN Michaël (Attaché scientifique)
Département Génie rural
Chaussée de Namur, 146
B-5030 Gembloux
Téléphone direct :62 71 57
Téléphone département :+ 32(81) 61 25 01
Fax département :+ 32(81) 61 58 47
E-mail :temmerman@cra.wallonie.be


  • SPW - DG Technologies de la recherche et de l'énergie
  • IDTI Intégration des Technologies industrielles
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