Chemical Engineering June 2021 - 25

Cover Story
Part 1
Process Analytical
Technology Advances
Developments in laser technology and significantly increased computing power are making
process analyzers available for new applications and even for closed-loop control
Wolfgang
Lubcke
Endress+Hauser
IN BRIEF
INTRODUCTION TO PAT
TRENDS IN PROCESS
ANALYSIS
COSTS VERSUS
BENEFITS
EXAMPLES OF PAT
APPLICATIONS
OUTLOOK -
THE FUTURE IS
DIGITALIZATION
rocess analytical technology (PAT)
has undergone rapid development
in recent years. Further developments
in laser technology, the miniaturization
of optical and electronic components
and the implementation of complex
chemometrics models (Figure 1) now enable
novel and robust field instruments that
can analyze even diverse mixtures of substances
in a highly selective manner.
This article presents an overview of PAT,
and describes some of the applications and
benefits of these technologies. It also addresses
some of the misconceptions about
cost and reliability issues.
P
Introduction to PAT
I wonder if Paul Gmelin had any idea of the
success story he had initiated in the chemical
process industries (CPI). At the beginning
of the 20th century, the workers in the
physical laboratory of the Badische Anilinund
Soda Fabrik (BASF) in Ludwigshafen,
Germany, was faced with a major challenge:
During experiments on ammonia synthesis,
it became apparent that the large gas flows
had to be monitored in terms of their composition.
Gmelin then developed the socalled
pipe analyzer. Using online analysis,
this analyzer made it
possible to measure
the ratio of the nitrogen
and hydrogen
gases during the synthesis,
and thus control
the ammonia production
process.
In 1913, GmeSpectrometer
lin
received a patent
for his pipe analyzer
- and modern
PAT was born. After
that, PAT slowly but
surely began its triumphant
advance.
This is because PAT
24
Fibreoptics
Endress+Hauser
FIGURE 1. Thanks to technology advances, the complexity of analytical instruments is
being reduced. Color measurements, for example, can now be performed with the compact
field device (right) that contains everything - spectrometer, probe and electronics
for data processing
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JUNE 2021
can be used to measure chemical properties,
the composition of mixtures, their
concentrations and their desired or undesired
changes. PAT therefore brings the
laboratory to the process, and offers decisive
advantages over offline analysis. This
is because traditional offline quality control
requires that samples have to be taken and
transported to a quality laboratory for analysis.
Several hours may pass before the results
become available, and this delay prevents
results-based process control. PAT
delivers results in or near real time. As a
result, PAT enables continuous monitoring
of production processes, as well as an optimized,
target-product-oriented production.
Over the years, PAT has become more
and more an established discipline, and is
now widely used throughout the CPI. Today,
PAT encompasses more than 80 different
measuring methods that are used on liquids,
solids and gases (see Table 1 for a
small selection). Just to clarify, " analytical
technology " is a term that refers to both
laboratory analysis and process analysis,
whereas PAT refers to process analysis. The
spectrum ranges from simple measurement
methods, such as conductivity, viscosity
and pH, through photometry, paramagnetic
Windows controller
Integrated through
standardized digital
protocol
Color measurement
ALL in one process
* Spectrometer
* Probe
Optical probe in process
Data processing
Four-wire
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Chemical Engineering June 2021

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