Paper Technology International 2024 - Journal - Page 137
PAPERTECHNOLOGYINTERNATIONAL
C
Controlling entrained air
in paper machine systems
Bret Magness, Business Development Manager - ECHOWISE®, Buckman
INTRODUCTION:
The presence of foam in a paper machine system can be a problem. But the presence of foam can be an indicator of the much
more costly problem of entrained air. ECHOWISE® provides real-time visibility into this problem and sheds light on how it can negatively
impact papermaking operations. More importantly, ECHOWISE® used with closed loop control provides a means to eliminate these
negative impacts.
Foaming in the wet end of a paper machine is an obvious
problem that is regularly treated through the application of defoamer
chemistries. Foam buildup, as shown in Figure 1, can lead to
problems like carry around on the forming wire, slipping issues on
walking surfaces, and surface deposition. But the visual presence
of foam is a lagging indicator of a problem that can have even
greater consequences; that problem is entrained air. Entrained air
will impact a paper machine in much the same way as 昀椀nes or 昀椀ller
loading. When trained air is high, drainage will be slowed. When
entrained air is varying, the drainage will move up and down on the
machine. This drainage variability can lead to draw breaks, sheet
moisture variability, and other product quality issues.
Most times, defoamer chemistries are applied at a dosage
level that will eliminate the visual presence of foam in the wet end of
the paper machine. These chemistries can be costly and, depending
on many machine conditions and other factors, can have varying
degrees of effectiveness. A defoamer application methodology
based on visual foam provides a downward shift in the threshold of
both foam and entrained air but retains the base variability in both
conditions that is caused by changes in furnish coming to the paper
machine.
Figure 1: Foam buildup on a paper machine.
This unseen, underlying variability in entrained air levels
can cause the paper machine issues mentioned above along
with excessive spending on defoamer chemistries. The question
then moves to, if foam is a lagging indicator of this entrained air
variability, what metric can the papermaker use to get ahead of the
issue?
What Is Ackumen™ ECHOWISE® Technology
ECHOWISE technology from Buckman provides real time,
continuous, non-invasive entrained air measurement. ECHOWISE
equipment can be installed in one of two forms. The ECHOWISE
100, as seen in Figure 2, can be plugged into an existing sample tap
on a paper machine to pull a continuous process sample through the
sensor and then return the sample to the process.
Figure 2: ECHOWISE® 100
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