Chemical Engineering July 2023 - 40

Sopat
based on existing ISO standards
and literature.
Decision tree
A clear procedure of classifying an
analyzer according to measurement
position is suggested by Minnich [9].
The decision tree (Figure 3) is based
on the critical categories of real-time
(yes or no), in situ (yes or no) and automating
capabilities.
FIGURE 7. The graph shows particle size changes over time
late the instrument from the main
process flow, making it easier to access
and maintain.
When the process flow is intermittent.
In some processes, the
flow may be intermittent or variable,
which can make it difficult to take
accurate measurements. A bypass
can be used to divert a constant
flowrate to the measurement instrument,
ensuring that measurements
are taken consistently.
On the other hand, there are some
clear disadvantages of using a bypass
for the measurements, including
the following:
Delayed response time. The bypass
diverts a portion of the process
flow away from the main line.
When this occurs, there will be a
delay in the response time of the
measurement system. This can result
in slower or less accurate measurements,
especially in processes
where rapid changes in flowrate or
process conditions are common.
Increased complexity and costs.
Adding a bypass to a processmeasurement
system will add additional
components, such as valves,
pumps, flowmeters and tubing.
These components will increase the
complexity and cost of the system.
This also increases maintenance and
makes troubleshooting more difficult
and expensive.
Sopat
Increased risk of contamination.
Depending on the process and the
materials being measured, using a
bypass can increase the risk of contamination
or cross-contamination.
40
This can affect the accuracy and reliability
of the measurements and can
also pose a safety risk.
Reduced flowrate. Diverting a portion
of the process flow away from
the main line can reduce the overall
flowrate, which can have an impact
on the efficiency and throughput
of the process, if the product cannot
be reverted into the main product
stream. That would also lead to
product loss.
It is worth noting that using a
bypass introduces additional complexity
and cost to a process measurement
system, so it is important
to carefully evaluate the benefits
and drawbacks of using a bypass
for your specific application. In general,
a bypass should be used when
it is necessary to achieve accurate
and reliable measurements under
challenging process conditions and
no real inline technologies are available
for this measurement task.
Therefore, the definition of " real inline "
technologies is given below
Based on this clear decision tree,
bypass solutions are not considered
inline. Available in situ technologies,
which are able to be applied in an
industrial environment, such as suspension
polymerization production
(high temperature, high pressure,
explosive atmospheres) are only
available for ultrasound attenuation
spectroscopy, laser backscattering
and inline microscopy.
Particle sizing in polymerization
Real-time particle sizing in suspension
polymerization has become a
crucial tool in the polymer industry
due to its numerous advantages [10]
(Figure 4). First, real-time monitoring
of particle size and distribution enables
better control and optimization
of the polymerization process, leading
to improved polymer quality and
increased productivity and reduced
waste. This can result in higher output
and a reduction in waste, leading
to cost savings. Second, the ability
to monitor and control particle size
and distribution during downstream
processing can also result in more
consistent and higher-quality polymer
products. This can lead to increased
end-user satisfaction, which
can result in higher sales and greater
profits. Finally, real-time particle sizing
provides detailed information
about the polymerization kinetics, including
the nucleation, growth, and
FIGURE 8. The images captured by the camera are processed digitally to remove background noise or
distortion, and to enhance the features of the particles
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