When UPM Fray Bentos decided to replace its aging Kappa Brite Analyzer after over 10 years of sterling service they again chose Valmet and in 2019 installed the latest online analyzer Valmet Kappa QC. The UPM Fray Bentos mill, located on the banks of the River Uruguay, produces 1,3 million tons/annum of bleached kraft pulp. The end product, UPM Euca, is a versatile fiber made from plantation-grown eucalyptus. It is used to create clean, soft and smooth tissue products but also provides good surface and optical properties for printing and writing end uses. Quick refinability, high brightness and good cleanliness make it a choice for several specialty paper types.
New measurement opportunities
According to Inés Eluén, Process Manager, the Kappa and brightness measurements from Kappa Brite were usually accurate and reliable, but it was approaching end-of-life resulting in difficulties to purchase the spare parts. “We took the change as an opportunity to add further value: increase the frequency of kappa and brightness results as well as measure shives and fiber morphology along the fiberline. We aim to provide our customers with very clean pulp of stable brightness all the time, so brightness measurements need to be very accurate, with a small standard deviation and as frequent as possible. But in addition, we wanted the analyzer to identify and measure very small, semi bleached shives which are difficult to detect, even to the human eye. This was a challenge during equipment selection: some analyzers were not able to detect such shives at all,” says Eluén.
We wanted the analyzer to identify and measure very small, semi bleached shives which are difficult to detect, even to the human eye. This was a challenge during equipment selection: some analyzers were not able to detect such shives at all. Inés Eluén, Process Manager
Selecting the right analyzer
Gastón Cubas, Development Engineer, takes up the story, “A couple of years before changing the equipment we began evaluating different alternatives available in the market with the focus and interest to monitor shives and fiber morphology. In this sense, we performed a preliminary evaluation of the Fiber & Shives module offered by the Valmet Kappa QC. We sent samples to customer installations in Finland and the results were promising. In addition, we had the opportunity to confirm some valuable mill references of this equipment (one of them in our company) of good performance and reliability for Kappa number and brightness measurements as well as some experience with shive monitoring. When the time came to decide on supplier and technology, Valmet met all our needs and expectations, technically and commercially.”
Kappa, brightness and shive control
The Kappa Analyzer performs key measurements in the four stage, A/D-Eop-D-P, bleach plant. Measuring sequentially, the analyzer is fed by four samplers automatically extracting pulp from the process before first D stage, before second D stage, before last P stage and final product going to bleached pulp towers. Measurement data from the analyzer plus inline sensors are combined with settings given by the operator to carry out the various calculations required for each of the process stages and provide setpoints for the chemical controllers. “Kappa and brightness results are used in the same way as with previous analyzer to control bleaching. The shive measurements in the initial bleaching stages serve to monitor cooking process issues and are now easier to follow up. It is now possible to prevent short shive outbursts and control shives more efficiently in the fiberline. If something reaches the final product, it is easier to detect and segregate. Before, we needed more manual measurements to achieve the same result. We now have a better understanding of the effect of different process parameters on shives, as we get constant feedback from the process.” declares Eluén. “The shive measurements correlate very well with the kappa measurements throughout the process and have a very good correlation with the shives measured in the final product. This can allow us to forecast final product shives, which we are still following up,” adds Rainer Pauls, Fiberline Supervisor.
Good pre-planning guaranteed a smooth startup
For Inés Eluén a trouble free startup was essential, “Our project team including production, laboratory, R&D and technical department all had the chance to share expectations with Valmet and discuss about the goals at several stages from beginning to end of the project. Based on our request that start-up should be trouble-free for production, significant pre-work was done in order to reduce start-up time requirements. Before sending the analyzer to our site, pre-calibration curves were produced at the Valmet factory with selected pulp samples from our mill. A representative from UPM was able participate and our laboratory team had the opportunity to discuss results and comment on curves.”
Installation on the run
“Our project team discussed deeply about the best possible moment to perform installation and start-up and considered that it would be better to start-up the new analyzer during mill stable running rather than at a shutdown. The change was planned one channel at a time, which allowed us to continue monitoring and controlling quality along the rest of the process in the meantime. Valmet supported our strategy and worked together with us. The result of such team work was a very smooth, easy and fast start-up. We did not need to face blind process periods or worry about declassed product or tons of extra laboratory measurements at a rush. Our lab was able to focus its resources on calibration fine-tuning, one step at a time, and production could trust the results from the analyzer almost from the beginning,” reports Eluén.
“The analyzer has had an excellent performance from the first start with no notable failures or errors, achieving high availability and suitable maintenance level. As far as correlation is concerned, the pre-loaded curve in Finland had a very close correlation, and, in the short term, it was possible to reach excellent correlation values. Valmet support from the point of view of the project engineering was excellent, thus allowing the milestones set in the schedule to be met perfectly,” states Ramiro Zapata, Maintenance and Planning Engineer.
“Compared to laboratory measurements, the analyzer provides far more data and quicker feedback regarding the process. It allows online control of process parameters. The shive and fiber morphology measurements are providing further insights regarding the effects of our raw material and processes on pulp quality. Quality at our mill is at a very good level,” concludes Eluén.