PAT Creative instrumentation cuts costs and boosts performance

An integrated strategy combining process analytical technology (PAT) and process control has tangible benefits for both products and processes. The emphasis is on online methods, but choosing the right methodology is crucial.

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Chemists and engineers use process analytical technology (PAT) to monitor and improve their processes. The tools have evolved over time, but the objective stays the same: to observe and understand chemical and physical changes, and then use process automation to maintain critical variables within predefined limits.

Different types of process require different types of PAT. Large-scale production of chemicals and fuels takes place in continuous plants that have been optimized over many years, with sophisticated control and management. Understanding of the chemical and physical processes involved is generally advanced, allowing mathematical modeling to support the design of new plants.

Very different are the 85 percent of plants that operate batchwise. Production volumes here are substantially lower, and the value of the products—fine chemicals and pharmaceuticals—generally much higher. Many batch plants are designed to handle a variety of products. The products themselves are often highly complex, and the processes not completely understood.

An integrated approach combining PAT and process control can provide major competitive advantages, especially in the batchwise production of custom products. The goals are:

• increased productivity through maximization of material flows and yields, and minimization of resource consumption;
• reduction of engineering margins without compromising safety;
• greater operational flexibility;
• higher quality and fewer customer complaints;
• integrated diagnostics and remote control; and
• improved integration with plant data networks.

Choosing the right method

“If more than one analysis is performed per day, PAT is normally more cost-effective,” says Dr. Stefan Stieler from BIS Prozesstechnik in Frankfurt am Main/Germany. “Process analytical systems run on weekends and holidays without the need for extra shifts. Data acquisition is ongoing, and the risk of errors when samples are taken is virtually eliminated.”

In principle, nearly every analytical method used in the lab can also be used in the process. “About 70 measurement techniques are available,” says Stieler (see table). “But PAT will only meet future expectations if the right analysis equipment is deployed in the right place.”

Industrial trends

PAT is used widely in large-scale chemical production for quality assurance and to guarantee plant safety. As new technologies are introduced and solutions become more versatile, pilot plants can take advantage of PAT, and the technology will play an increasingly important role in ongoing optimization of cost, energy and raw material efficiency.

The pharmaceutical industry is a leading driver for the development of flexible ap-proaches to production based around PAT. Though production volumes tend to be small, quality standards are very high, with enormous regulatory burdens, and there is also political pressure to cut costs. PAT developed for pharmaceuticals can also be applied to batch processes in fine chemicals manufacture.

The life sciences industry requires special solutions. The Biotechnology Measurement and Control Working Group at Dechema says that PAT should be directed primarily at concrete tasks, and that priorities include:

both new and established types of sensors offering modularity, support for non-invasive, real-time measurements, and especially simplicity;

process analysis capability to calibrate and model the process and measurement techniques;

solution-oriented product and process integration based on Quality by Design and support for full process automation; and

compatibility with IT infrastructure.

A lot of work remains to be done to provide the sensors which users need. The list includes sensors for:

• state of hygiene and cleaning;
• metabolomic, proteomic and transcriptomic biomarkers;
• cell wellness;
• microorganism identification;
• concentration measurement in textures; and
• morphology of biostructures.

IR, NIR, fluorescence, impedance, mass and Raman spectroscopy are of particular interest for biotechnology. Techniques involving fiber optic technology, immunoassays, biosensors (chips), electrophoresis, software sensors (virtual sensors) and calorimetry are currently under development. Even the technology for common measurements such as pH continues to evolve.

R&D trends

Optical molecular spectroscopy has become the PAT “workhorse” in recent years, with miniaturization and cost reduction continuing. The next step will be to use optical spectroscopy as an imaging tool, such as for tomography in reaction engineering. Complex techniques such as mass spectroscopy and NMR spectroscopy may become standard in the future, and there will also be developments in particle analysis.

Users are looking for low-cost solutions, and especially Atex-compliant devices. Technology based on MEMS (Micro Electro Mechanical System) has produced promising developments in miniature spectrometers. Synergy between semiconductor technology and IT has also allowed the miniaturization of gas chromatography, and advances in ion mobility spectrometers are expected.

Modern process control and PAT systems generate mountains of data. Multivariate data analysis is widely used to extract meaningful information from this data, but requires significant effort in calibration. Chemometric systems now being developed promise to generate qualitative models without calibration.

Promoting PAT

It is essential to continue the development of PAT so that companies, especially SMEs, have access to the tools they need to remain competitive.

As living standards and wages in developing countries rise, western companies are losing the advantage they gained a decade ago by moving their manufacturing operations to low-cost countries. Experts believe that the cost advantage of employing people from engineer level upwards in eastern Europe is now less than one-third compared to western countries, and in China only 50 percent. The difference can be made up through smarter manufacturing—which is where PAT comes in. Despite its economic potential, however, PAT has generally lacked coordinated support. Recently this situation has changed, thanks in large part to the PAT Initiative run by the US Food and Drug Administration (FDA). Along with other pharmaceutical industry strategies including QbD (Quality by Design) and PQLCI (Product Quality Life Cycle Implementation), the PAT Initiative has changed a long-standing perception among policymakers that PAT is a purely internal tool for cost reduction.

Now, politicians and academics as well as industrialists have begun to promote and support a common approach to process optimization in response to raw material shortages and rising labor costs. In Europe, and particularly in Germany, cheaper and higher-quality pharmaceuticals are now seen to have significant social relevance, while reducing energy consumption is important in protecting the environment.

The scientific community has now taken up this challenge. Namur, an international user association of automation technology in process industries, for instance, has encouraged the development of instrumentation since the 1950s and continues to be an important platform for PAT. The German Chemical Society (GDCh) and Dechema have joined forces to set up a PAT working group.

For years, the US has had an annual PAT conference which attracts around 500 experts from the research, vendor and user communities. The first European equivalent, EuroPACT, took place for the first time in Germany in 2008, and was a big success. However, experts agree that educational institutions in Germany still lack the breadth and depth needed to adequately address the complexity of PAT.

This article is based on the trend report “Process Analytical Technology” in the run-up to ACHEMA 2009. The complete trend report is available via the InfoClick.

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