Applied control theory moves out

By Dan Hebert, Senior Technical Editor, PE

YOU AND YOUR company are always looking for innovative ways to improve manufacturing processes, and advanced process control (APC) is a key component of these efforts. Many of your peers share the same APC problems, and an APC solution applied to one process can often be adapted for use in another process. This is why the Applied Control Technology Consortium (ACTC) was created.

The ACTC helps its member companies acquire and apply advanced process control technologies. ACTC members include international process companies GlaxoSmithKline, British Petroleum, and ConocoPhillips. ACTC provides two main services: company specific consulting, and education and technology transfer between industry and academia. ACTC covers both the process industry and mechanism control as used in industries such as aerospace and automotive. This allows technology transfer across different industries.

According to Dr. Andy Clegg, technical consultant at ACTC, “International academic support comes from the University of Strathclyde in Scotland and is facilitated by faculty member and ACTC technical director Professor Mike Grimble.” ACTC has established strong international links with key researchers and users in a wide range of technologies and industries. In particular, close links with the University of Florida provide support for members in the U.S.

“For U.S.-based member companies, Professor Haniph Latchman and Professor Oscar Crisalle of The University of Florida provide company specific services, such as training and consulting,” says Clegg.

The ACTC is managed by Industrial Systems and Control at Strathclyde and is run on a commercial basis. This distinguishes it from similar activities which are usually within a university department and less inclined to maintain their activities beyond any initial funding.

ACTC’s education and technology transfer services are available to all members and are delivered through seminars on new developments in APC; special interest group meetings that focus on specific industrial sectors; training events; custom produced educational notes, technical reports, and software toolboxes; a web-site area; networking to meet fellow engineers and technical managers in a non-competitive forum to appreciate different perspectives, problems, and solutions; and free access to commercial control design packages.

ACTC also produces white papers and case studies. “The ACTC developed genetic algorithms for system identification in a steel-making process,” reports Clegg. “This was deemed to be of sufficient generic interest that it was published as a case study report available to all ACTC members. The ACTC is active in many areas of APC including: model-predictive control; nonlinear control; adaptive and self-tuning control; intelligent control; robust control; and has developed an innovative system for control loop benchmarking.

ACTC’s recent consulting projects include:

• Improved pH control for Paper Manufacturer–The batch make-up of a clay slurry involved regulating pH through the addition of acid. The existing plant control was a simple on-off control, with consequent sawtooth variation in pH and slurry density. The ACTC investigated the use of proportional valves and control to provide finer control. Detailed modeling and simulation were employed to generate correct tuning, valve size, and switching logic to integrate with the existing DCS.
• Automation of Glass Manufacturing Process–A key part of the process was entirely manually controlled, which was restricting automating product changes. The ACTC worked closely with plant engineers and math modelers to derive an effective control strategy for the process which had been deemed uncontrollable. These strategies were tested in simulation and then rolled out to plant usage with minimal re-design.
• Investigation of CHP plant steam pressure instability–Alternate control strategies were investigated to alleviate limit cycles in steam pressure supplying a salt manufacturing process. These limit cycles arose from the combination of existing control strategy and an inappropriate damper actuator. The redesigned control strategy not only eliminated the limit cycles, but also improved the power output of the steam turbine by some 0.5 MW.

ACTC is now also receiving automation industry support from companies like Emerson Process Management, which believes with ACTC that the partnership between industry and academia is most beneficial when theory moves out of the classroom and into the plant. ACTC and Emerson in the UK are now cooperating to expand the use of PlantWeb intelligent instrumentation for machinery condition monitoring, and by applying the AMS Suite of predictive maintenance software for asset management. This will be demonstrated in cooperation with a major UK pharmaceuticals manufacturing plant to illustrate the capabilities and benefits that arise by minimizing unnecessary maintenance.