Pulp Paper & Logistics
ABB 13
freeness readings. In addition to better control, less variability and energy savings, the mill has seen increased production levels and reduced grade change time as a result of the online measurements. The next step would be to close the control loop to automatically run the refiners based on the online measurement by using advanced process controls. Eduardo Izquierdo, the technical
director at FPC Papeles, said: “We are delighted with the online freeness measurement and the support we have received from ABB and MX-Chile, an ABB distributor who helped with installation and support. We look forward to continuing to work with them to achieve higher
levels of process stability, savings and final product quality.”
Fibre morphology and paper strength Freeness is not an absolute measure of the pulp strength. A low freeness value can be produced not only from well- fibrillated fibres, but also from a high concentration of low surface area ray cells with poor bonding potential, or shorter fibres. Thus, the measurement of other fibre properties will help to characterise the pulp better. These include shive content, fibre length, fibre width and shape factor, all of which can be measured with an online instrument. A high shape factor, as illustrated in Figure 4,
means straight fibres and is well correlated with tensile strength and tensile stiffness. It is possible to create a virtual
strength sensor by combining several fibre measurements from an online fibre sensor, in combination with other process measurements. This would provide a prediction of online paper strength every few minutes rather than once per reel. Using such a virtual strength sensor to control paper strength would bring additional value to closed-loop control of paper strength.
Better measurements stabilise consistency and quality With the latest generation
of online instruments, which can characterise the nature of the fibres being used much more thoroughly than manual testing, paper mills can benefit from the improved reliability and higher frequency of online measurements compared to lab testing. In the near future, the use of online and other virtual measurements for advanced process control strategies will enable mills that embrace new technology to leap ahead of their competition with more consistent quality and a stronger product that costs less to produce. * Hakan Osterholm is global
product manager for pulp measurements at ABB.
July/August 2021
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36
