Plant control for productivity gains
Situated on the Ayrshire coast, just outside the town of Irvine, GlaxoSmithKline's pharmaceuticals plant is a major producer of primary ingredients for the company. The Irvine facility is the group's major source of the D(-)Amoxicillin side chain, an ingredient that is used globally in antibiotics. In line with most modern pharmaceutical producers, GSK has adopted a policy of automating manufacturing processes where possible. What makes the Irvine plant different is the scale of automation as well as the speed and efficiency with which it has been implemented.
William Melvin is the lead process control engineer responsible for ensuring that new automation strategies are installed and commissioned. 'The main drivers influencing decisions on which part of the various processes will benefit from automation are usually increased output and reduced equipment downtime', he states. Unlike many manufacturers, GSK has adopted something of a strategic approach in its process control decisions, seeking out new and innovative solutions rather than relying on long-established methods. The recent upgrading of the plant's entire Enzyme Precursor Plant (EPP) – an integral part of D(-) amoxicillin production – is just one example of this strategic approach.
rapid rate of change
The previous facility was only about 10 years old, but such is the rate of change in the process control industry that the original control system was obsolete and incompatible with current networking platforms, which use Windows NT.
The plant is a large user of Siemens control equipment and Melvin looked to the same company to provide an automated control solution: the Simatic PCS7, which would increase production yields in the EPP. 'This solution was viewed as innovative,' explains Melvin. 'The system employs new technologies and tools that we saw could improve not only our yields but also the flexibility of control over the manufacturing process.'
As lead process control engineer on the EPP project team, Melvin spent nine months configuring the new system and overseeing the installation.
In implementing the EPP project, GSK had to assess:
As D(-) amoxicillin production is a continuous process, running 24 hours a day, the new process control system had to be ready for changeover during the annual plant shutdown. Melvin and his team could not afford to lose any product capacity while the new system was commissioned. This left them with only two weeks to carry out all of the wiring and bring the system back on line. By using existing I/O, the amount of new wiring was reduced significantly and this contributed to a painless factory acceptance test process that took place over a seven-week period prior to going live.
integration - the big challenge
The first stage in the project was to develop a user requirement specification that incorporated the knowledge and experience gained from earlier automation projects at the plant. Systems integrators Batch Control Systems were called in to develop the customised software required. The system architecture at GSK uses a Profibus DP fieldbus to provide distributed control to the EPP via two Simatic PCS7 systems. These collect data from the 900 remote I/Os on the plant and feed it to a dual server network. Linked to this is an engineering station in the central control room and two, dual screen, clients. Totally integrated automation is achieved by linking the two Simatic PCS7s to GSK's corporate MES system.
Profibus is now used widely for distributed control in pharmaceutical and other batch or continuous process plants around the world and is the largest fieldbus network in the world, in terms of the number of installed nodes. The Ethernet network links the various workstations while a plant-wide fibre optic ring is used for communications across the various installations.
'Communication was an important consideration for us,' explained Melvin. 'Not only did we need a reliable network, we also have to be able to fault-find quickly. Although the networks we have configured may appear complex, they are actually extremely robust.' Melvin's team added a remote diagnostics capability to the system by linking a home PC via PC Anywhere software into the EPP Control Room's client/server architecture. If a plant fault does occur, it is now quicker and easier to diagnose.
future expansion
'We couldn't help but improve output,' states Melvin. 'The new generation of plant control software is far more flexible and powerful. Improvements in fault diagnosis and more accessible information all help us achieve the productivity objective.' Output at Irvine is currently running as much as 4% higher than previously.
A number of factors have been considered for future expansion. The system runs on a common Windows NT platform and the Simatic PCS7 solution provides engineers with the facility to link in almost limitless additional I/O points.
Overall, the new EPP facility at Irvine has provided a more flexible process control system capable of increasing product yields, reliably.