Process optimisation for streamlined polymerisation
Polymers are everywhere, and in the modern world, many of them are manmade: materials such as polyethylene, nylon and PVC are part of our daily experience. EU-funded researchers have developed solutions to make polymer production in the chemical industry more efficient and more sustainable.
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“The Coopol project was dedicated to process intensification,” says Peter Singstad of Cybernetica, a Norwegian company specialising in process control systems that was involved in this three-year endeavour. Although industrial polymer production has evolved a lot over the past 100 years, there is room for improvement, he explains.
Coopol was launched in March 2012 in a bid to upgrade industrial polymerisation processes through real-time optimisation. It developed and upgraded software to give manufacturers more control over the transformations taking place in the large vessels — known as reactors — that are currently used to make polymers. It also delivered concepts for innovative sensors designed to monitor the process, and contributed significant advances to the development of a radically different type of reactor.
Achieving peak performance
Many polymers are produced in batches, Singstad explains. “This means that you have a large vessel, you fill the reactants in, and you make the reactions run,” he says. In many cases, substances can be added while the reaction is in progress — but this doesn’t mean that the process that unfolds is necessarily as efficient as it could be.
The composition of the feed material, the operating conditions and the environment are never exactly the same, and therefore variations in reactor conditions and product properties will occur. To achieve the required quality in the shortest time possible without wasting energy or materials, it pays to know how to compensate for the variations.
To reach this level of control, manufacturers need ongoing updates on the status of the process and precise calculations of any adjustments that may be needed. “We can play around with two main variables,” Singstad explains. “One is how rapidly we feed the reactants, and the other is the temperature in the reactor.”
Coopol proposed a combination of hardware and software developments to address the optimisation challenge. Focusing on the particular case of emulsion polymerisation as a representative example, it developed a concept for innovative sensors that could be used to keep tabs on the conditions inside the reactor, complementing the data already provided by existing instrumentation.
Direct measurements are available for variables such as temperature and flow rate, Singstad notes. “Unfortunately, what we can detect is not what we want to measure,” he adds. “What we really need to know is how the composition of the reaction mixture is evolving and how much of the material has already converted to a polymer. Sophisticated software is used to infer this information from the data at our disposal.”
A predictive approach
The data and the indirect measurements derived from it are considered alongside information from elaborate mathematical models that predict what is going on inside the reactor, enabling the controls to take automatic corrective action as necessary. The approach was successfully trialled on a reactor at a BASF pilot plant, Singstad reports.
Coopol also looked into the possibility of producing polymers in a continuous stream rather than in individual batches, Singstad adds. This method would make it possible to run polymerisation processes in smaller reactors where they could be controlled with even greater precision. The project developed an experimental tubular reactor that successfully demonstrated the principle, he notes.
Coopol ended in February 2015, having delivered new tools that are already available to customers as an upgrade to an existing model predictive control system commercialised by Cybernetica, along with leads for new instrumentation and reactors that may soon take polymerisation another step ahead. Work on the mathematical models created by Coopol continues in Recoba, a new EU-funded project dedicated to batch processes for the production of emulsion polymers, steel, and silicon metal.