Control system migration without disruption

Paul Boughton
An agri-chem business giant's four-year programme to replace its process control systems delivered operational efficiencies and production flexibility - without business disruption.

Syngenta is one of the world's leading agribusinesses specialising in crop protection and seeds. At the Huddersfield Manufacturing Centre (HMC), in the UK, its range of active ingredients manufacturing operation is reliant on a number of complex process control systems to run the production on the site.

Looking to replace legacy process control systems can be a daunting task. But Syngenta, with the expertise of Siemens Industry Automation, has successfully completed a four year control system replacement programme at its Huddersfield Manufacturing Centre on time, on budget and, crucially, without disruption to its production targets.

Nearing obsolescence

The issue facing the Huddersfield process control management was the realisation that four of the six main plant control systems were reaching a stage of obsolescence. They were dealing with increasing incidents when spares were in short supply; plant failure rates were on the rise and, indeed, the impending withdrawal of technical support for certain plant control systems to help the site operate was a major looming concern. This powerful combination of factors made the site management draw up plans for a long-term replacement programme for the existing HMC process control systems which would alleviate the legacy and future support issues once and for all.

The team turned to Siemens Industry Automation as a solution partner which could offer both proven project implementation expertise, as well as the PCS7 process control system solution that could support the site's manufacturing needs for future decades.

As a manufacturer, the critical point underpinning any planned migration to a new control system is the necessity to do so without disrupting existing production schedules.

Mick Pearson, Syngenta's Process Control Systems Manager at Huddersfield highlights this concern: "The replacement programme was an enormous challenge to the process control team on site at Huddersfield. It was deemed essential for the site's continued operation, but nonetheless, it still presented a real planning challenge for everyone, particularly with the requirement that production had to continue without disruption following any changes. These are multi-stage batch chemical processes, some with continuous operation, and we could not afford for the new control system changes to interfere with our production operations."

At the planning stage, the Syngenta team worked alongside Siemens to draw up the strategy which would support the phased approach to replacing the identified four systems over a defined time period.

Ian Heathcock from Siemens Industry Automation says there were a number of key factors to consider. "Along with the Syngenta management team, we had to ensure that at all stages we could minimise resistance to the planned changes and facilitate learnings so that we had complete buy-in to the plan from the people who ultimately would operate the new control systems - the plant operators themselves. We also had to ensure that the new technology specified was an evolution when compared to the old system, so a balance was achieved between utilising modern process control systems such as our PCS7 and ensuring the operators could see the benefits a new control system would bring in terms of operational efficiencies.".

Phased replacement

Timing was critical to the success of the phased replacement programme with switchover to the new control systems only able to take place during the annual shutdown period. These dates were not flexible and the result of missing a deadline for changeover was that the project would be delayed for another 12 months, putting back the entire project and placing HMC's ongoing manufacturing processes at risk.

The phased approach commenced with the smallest sized control system of the four targeted for change. This saw the replacement of a 20 year old plant control computer at the site's Fusilade plant. The low-risk strategy of starting small allowed the Siemens and Syngenta teams to work in partnership to clearly define what was required, without the enormous combined pressures of trying to replace all four process control systems simultaneously.

Liaising closely, the teams took a number of weeks to define the processes required by the new plant control, such as validating the necessary actions and sequences used in the production cycle. Investment was also made in writing the software for the new system and the collaborative approach involved testing schedules with Syngenta's on-site control team travelling to Siemens' Manchester base to trial the new system. Such hands-on training was integral to the longer-term strategy of operator buy-in and gave the Syngenta team the knowledge and expertise on a first-hand basis which would be required to support the new control system when it went live on day one. .


With more than 15 years since the last major control system replacement at Huddersfield, the Syngenta team was a little nervous when the first phase switchover took place. However, the meticulous planning and potential problem-solving work undertaken by the two teams beforehand paid dividends, and the first control system was implemented on time during shutdown and, crucially, without any production downtime on site.

Having successfully managed the first phase of the overall programme, thoughts turned to phase two. This involved the replacement of a 15 year old plant computer on the site's Reglone process plant. The team approach from phase one was continued and the efficiencies and learnings from the first smaller-scale project helped determine, underpin and drive forward the actions for the second phase.

Subsequent phases, that have seen the final two legacy process control systems replaced, followed the planning, testing and implementation template created at the first stage. This approach has proven to provide Syngenta with cumulative and significant time and cost savings across such a substantial four year project.

Mick Pearson sums up the project from Syngenta's point of view: "The sense of achievement is fantastic. The four new control systems have been replaced and are operating superbly, bringing the business operational efficiencies, production stability we wanted and removing future system support issues. All production quotas have been delivered and the product quality maintained. We have worked alongside Siemens who brought with them the significant project expertise we required, backed by the PCS7 process control solution that meets the flexible and scalable control needs we will need into the future. We now have plant control systems that are more reliable, are cheaper to run and give us more opportunity to both analyse the processes better and then to optimise them. The proof of the success is in the performance, and we have not experienced any production breakdowns in the four years since the inception of the switchover programme."

Process improvements

Going forward, and in keeping with the site's strategic approach and the investment made in ensuring the Syngenta operators were fully behind the new systems, the process control team are continually seeking process improvements and cost efficiencies.

Indeed, software changes implemented in-house are now routine and frequent, allowing the production process to react to the changing needs of the business. The ability now to carry out software changes and introduce new I/O online is contributing to reducing any unnecessary downtime.

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