Paper Technology International 2024 - Journal - Page 21
PAPERTECHNOLOGYINTERNATIONAL
e.g., pH levels, electrochemical charges, steric stability,
and conductivity. Unfavorable process conditions
signi昀椀cantly increase the risk for deposition, slime, and
scaling and lead to increased deposit build-up, resulting
in defects, spots, holes, and hole breaks.
These were some examples of how, in papermaking,
everything impacts everything. Harmonizer can encompass
comprehensive chemistry application status and performance data,
e.g., using Kemira’s patented technologies for real-time measuring
and monitoring in the papermaking process.
In addition, soft sensors can be used to enrich the data
with measurements that are not possible to measure directly
online. For example, many critical quality measurements are done
in the laboratory and the data is available infrequently and with a
delay, such as strength properties of board, ash content or paper
caliper, bulk or opacity. Modern computational technologies can
calculate the missing metrics from online data tags in real time.
These so-called soft sensors make the predicted quality values
available immediately, constantly, and accurately, providing even
more insights for the mill’s experts to make decisions. Harmonizer
provides a platform to ef昀椀ciently utilize data sources to automate the
construction of soft sensors in a novel manner, which saves time
and helps deliver superior performance.
Generating value for paper and board production
Better visibility into the harmony of the papermaking
process can support the ongoing operative production optimization
in multiple ways. The use cases can vary from physical issues to
different running conditions. Harmonizer can also help to ensure
process stability in situations where disharmony can quickly appear,
e.g. after grade changes or shutdowns.
In addition, the service enables knowledge sharing and
aids the operators in gaining a better understanding of the overall
process and how the different variables and dependencies in the
papermaking system impact production. Over time, the visualization
of the process harmony and analysis of the root causes can reveal
previously unknown cause-and-effect relationships behind process
disturbances. With these insights, Harmonizer can also help create
a uniform way of running the papermaking process at the mill,
leveling out differences between operator shifts and supporting the
implementation of best practices from different operator shifts.
The service can be built and tested of昀氀ine before building
online connectivity. This allows end users at the mill site to evaluate
the tools with their historical process data before online deployment.
Case study 1.
Revealing previously unknown cause-and-effect
relationships behind process disturbances
Sometimes, deviations in the papermaking process
escalate into severe production and quality disturbances in minutes.
Harmonizer can shed light onto the quickly emerging process
disruptions.
It can reveal previously unknown cause-and-effect
relationships behind these types of disturbances by making visible
how different process parameters are in昀氀uenced by each other and
how changing conditions and the identi昀椀ed disharmony in one area
impact other areas. Process experts are, of course, familiar with
many of these impacts, but especially with unexpected process
disturbances, the comprehensive harmony model can provide novel
insights and allow users to understand the phenomena in more
depth.
In this case, Harmonizer revealed how a sudden drop in
the retention polymer dosage immediately impacted the production
of a board machine (highlighted in Figure 2). The harmony model
shows that the dosing deviations quickly impacted the ash content,
the basis weight, and the opacity of the 昀椀nal paper, leading to issues
with quality. The problems start to accumulate even after a short
drop in the polymer dosing.
As the disturbances only last for less than 10 minutes at a
time, the board machine operators were simply unaware of many
of the incidents earlier, and especially of their full impact on the
production process. Harmonizer brought these sudden changes
in the process behavior to the operators’ attention for corrective
measures and, at the same time, increased understanding of which
process parameters are directly impacted by the sudden changes in
the process conditions.
The model also revealed how such deviations contributed
to the risk for breaks (shown with red diagonal lines in Figure 2),
further supporting the work of the operators.
Figure 2: The impact of a sudden drop in retention polymer
dosing.
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