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Successful investment and initial startup of a field flow fractionator

In order to be able to reliably and quickly respond to future problems in the broad field of fibre analysis and process control, PTS acquired for its research and services area a fractionator from the firm Valmet (see Figure 1) for its laboratories in Heidenau during the final quarter of 2017 within the scope of an investment grant as part of the INNO-KOM investment programme of the German Federal Ministry for Economic Affairs and Energy. The instrument was put into operation in December 2017 and has been available for laboratory operation ever since. This fractionator complies with the latest state-of-the-art requirements and consists of a tank that separates fibres and other constituents in the suspension according to their hydrodynamic behaviour in a flow field, a light absorption detector, a camera for evaluating constituents of printing inks and a camera for analysing fibre morphology.

Figure 1: Fibre fractionator from Messrs. Valmet (Source: Valmet)

The individual constituents of a pulp suspension are therefore evaluated during measurement with respect to their dimensions, deformation and external fibrillation. At the same time, the actual fractionation process is recorded in a video sequence that can later be analysed on the basis of adapted settings depending on the problem definition. This allows conclusions, among other things, to be drawn on the flocculation behaviour as a function of the additive added or as a function of the retention system. If need be, a total of as many as five fractions per measurement can also be physically collected in cups for more extensive subsequent analysis (refer to Figure 2).

Figure 2: Fractionated pulp suspension (Source: Valmet)

In this context, the spectrum of suspensions to be measured is extremely diverse. Not only pulp suspensions, but also regenerated fibres, microfibrillated cellulose, synthetic fibres and of course samples of recycled fibre pulp can be measured as well. The device is equipped with a special feature for the latter. The “ink” camera installed in the instrument can be used to quantify both dirt specks as well as dissolved and undissolved ink, thus making the rapid evaluation of a deinking process possible, since ink constituents can be determined right in the suspension itself.

In addition to answering standard analytical questions regarding fibre morphology, the fractionator can also help to increase the productivity of different processes by optimising the use of raw materials, improving sustainability and reducing production costs.