Test & measurement
On the path tO the prOcess
From lab analyser to compact field instrument
promising future for optical processes in particular. The purpose of process analytics is the optimisation of engineering processes, such as quantitative assessment of the reaction progress. While users are eager to see process analytics deployed on an increasing basis, the solution must be economically feasible and also justify the costs for procurement, commissioning and maintenance. Compared to conventional field instruments
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for measuring parameters such as level, flow, pressure, temperature, pH and conductivity, the costs for complex process analytics are much higher. The investment costs for optical spectrometers can quickly add up to several hundred thousand euros, nearly half of which is swallowed up by commissioning and maintenance. Reducing these costs decreases the economic feasibility threshold, thus satisfying the requirements of the NAMUR roadmap.
n the highly regarded “Process Sensor” roadmap from NAMUR, process analytics has an important role. The current “Process Sensors 2027+” roadmap is an enhancement of previous technology roadmaps that indicates a
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Process analytics provides information about the composition of substances in media in control processes by using a wide range of physical and chemical principles. It forms the critical basis for process optimisation. Laboratory measurement processes have successively evolved in the direction of process analysis measurement methods over several decades. The stated goal of the transfer is to develop compact field instruments equivalent to conventional field instruments. Conductivity and pH measurements, well established for some time now, have become an indispensable aspect of day-to-day plant operations. More technically sophisticated spectroscopic methods still have a long way to go before they will experience broader utilisation in process applications. Dr Monika Heisterkamp and Dr Andreas Meyer, Endress+Hauser, investigate...
OPTICAL PrOCEssEs ArE On THE uP Given the significant amount of data they contain, optical processes such as infrared, UV/VIS or Raman spectroscopy are attractive technologies for process analytics applications. The relatively new Raman spectroscopy technology has captured an increasing percentage of the market over recent years. And for good reason: compared to near infrared (NIR) spectroscopy, the Raman technique delivers significantly greater and more specific information. One particular challenge in analysing the spectra is calibration. Simple process sensors are calibrated to
traceable standards. The difficulty arises when the measurements are application-specific and the concentration of a specific substance in a medium depends on numerous measurement parameters, such as from a spectrum. In this case a so-called multivariate calibration is required, in which regression or chemometric models based on numerous measurements have to be created and regularly verified. Ideally, these models can be pre- built for similar applications and adapted to real applications with just a few measurements.
THE EvOLuTIOn TO fIELD InsTruMEnT The extensive selection of measurement processes makes it possible to manage a wide range of analysis tasks in the lab. Flexibility and a higher degree of automation are the key to being able to efficiently carry out comparable measurement tasks and process samples in greater numbers. Lab information and management systems (LIMS) provide reliable processing and documentation. Generally speaking, such instruments are set up separately, optimised for the lab and not integrated into the process control system. The major downside is that the samples from the process can change while being drawn, during transport and through the
The Memosens Wave CKI50 and Liquiline CM44P transmitter enable robust inline colour measurements, as well as the combination of all relevant parameters for the respective applications.
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corresponding delay. The time lag of several hours or even days means the lab analysis is often no longer
Dr Monika Heisterkamp, director Marketing,
Endress+Hauser Liquid Analysis
Dr Andreas Meyer,
business development manager, Endress+ Hauser Liquid Analysis
current. Operators have no chance to carry out timely corrective measures or regulations while the process is running. Compact field instruments, on the other hand,
are designed especially for direct use in the process. When it comes to ingress and explosion protection, as well as hygiene, their performance is exemplary. They are integrated into the control system and can handle even complex calculations. The requested measurement value is available in real-time and can be regenerated with a repetition rate necessary for the process dynamics and used for control purposes. As an added bonus, the field instrument also supplies the status of the measurement value and the system. That means the measurement unit allows
intervention in the process control system. Since all of the components are integrated into the sensor or transmitter, installation and maintenance requirements are reduced, which can be driven down further through an automatic cleaning or calibration unit. Self- diagnostics simplify operation and, in the best case, provide predictive maintenance information. The integration of internet-capable devices in cyber-physical systems creates further optimisation potential.
sTEP-by-sTEP InTO THE fuTurE Taking the first step in the direction of field instruments often involves a so-called modified laboratory instrument. A somewhat more compact version of a laboratory spectrometer is
August 2022 Instrumentation Monthly
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