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3D imaging technology boosts the use of mill broke in paper industry

Tue, 04/05/2011 - 7:18am
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Savon Sellu Oy’s mill in Kuopio is a major producer of semi-chemical fluting for corrugated board. Using Numcore’s device, the mill measures the mass flow from the mixing tank with the goal of identifying impurities which may affect the process at an early enough stage and changing the process parameters accordingly, thereby avoiding potential breaks. Savon Sellu Oy

A measurement device developed by Numcore Oy is based on impedance tomography produces a 3-D image in real time from the inside of pipelines and tanks used by the process industries. The pulp and paper industry is one segment that could benefit greatly from the technology. Numcore was recently awarded the ATIP 2010 Innovation Trophy in France for the most innovative paper technology company.

Numcore Oy develops new-generation measurement devices providing 3D imaging based on impedance tomography and the calculations and result reporting necessary for them. The company’s products can be used for solving problems and boosting efficiency in paper, mining, chemical and food industry processes. In terms of paper industry, Numcore has for now focused on optimizing the use of mill broke. The dosing of broke is an important stage in the paper manufacturing process, as broke is constantly generated, and fluctuations in dosing, particularly in coated broke, may disrupt the wet-end process.

The measurement device is being used as part of a pilot in a few paper and corrugated board mills and is connected to, in addition to the mills’ own monitoring systems, Numcore’s IT system. The device was realized as a CoreApus flow-through sensor with electrodes that continuously measure the electric conductivity differences in the various phases of the flowing mass.

The 3D image produced by the device can only be generated, however, using inverse calculation, i.e. highly advanced mathematical modelling, which is where Numcore’s core knowledge lies.

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Numcore’s measuring device based on impedance tomography is integrated with the paper mill’s process. The entire unit includes, in addition to the sensor, the voltage feed and measuring unit and the application for analysing the measuring results. Numcore Ltd

“The pilot devices are highly important product development tools for us, as the measuring data they generate allows us to precisely pinpoint the actual correlation between changes in mass flow and specific production problems. This has helped us to develop the modelling such that the data generated by the measuring device can be used to directly regulate the production process and boost its efficiency,” explains Jukka Hakola, Numcore’s vice president of sales and marketing.

Close inspection of broke dosing

One of the pilot mills is Stora Enso’s Veitsiluoto paper mill in Kemi, Finland, where Numcore’s measuring device has been installed in the broke dosing stage of Paper Machine 5, which manufactures magazine paper. The broke consists of both base paper and coated broke.

“Here we can regulate the refining and total amount of broke as well as the proportion of base and coated paper broke to an extent that the quality of the base paper and the runnability of the paper machine improve,” says Jukka Hautamäki, process development manager, Veitsiluoto Mill, Stora Enso.

He says immense demands are being placed on the measuring device, because the machine’s runnability was already very good.

“Numcore’s technology is simple to use and it was easy to install the sensor in the process. The sensor generates approximately 20 indices, which are displayed on the operator’s monitor and can be integrated alongside other machine parameters in our Savcor Wedge process analysis system. This allows us to seek correlations between, for example, the brightness of a base paper and the degree of refinement in specific broke.”

In the spring, progressive tests involving gradual changes to broke refining will be carried out. The changes will be compared with indices generated by the measuring system, with the quality of the base paper and with the runnability of the machine.

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Stora Enso’s Veitsiluoto Mill in Kemi is the northernmost paper mill in the world. Numcore’s measurement device has been installed in the dosing process of the PM5 magazine paper machine, where the refining and total amount of broke as well as the proportion of base and coated paper broke can be regulated to an extent that the quality of the base paper and the runnability of the paper machine improve. The ultimate goal is to use the device for automatic broke dosing. Stora Enso Oyj

“In the tests, we will work the machine to an extent that we will be able to see what the measurement device actually sees. The tests will be conducted until the end of April, at which time we will be able to see how well the device meets the special demands of our production processes. The ultimate goal is to use the device for automatic broke dosing,” says Hautamäki.

Major savings possible

Another pilot mill is Powerflute Savon Sellu Oy in Kuopio, which manufactures corrugated board. There, Numcore’s device measures the mass flow from the mixing tank.

“Thanks to the measuring device, we have already noticed that certain changes in mass flow clearly correlate with breaks that happen later on in the process. If we can determine as early as possible that there is the risk of an impurity in the process which will later on lead to a break, we are more efficiently able to regulate the process and thus avoid the break,” says the mill’s operations manager, Martti Laatikainen.

According to him, the mill is particularly concerned with changes in the amount of broke and variations in the amount of fines in the pulp.

“If the device helps us to find out the causes of breaks, it would bring us major annual savings. For that reason we were happy to take part in the development work for the measuring device,” says Laatikainen.

Numcore

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