Control system offers reliability at multi-product chemical plant

Paul Boughton

A chemical manufacturing giant has replaced its problematic control system with a new solution which offered increased output, improved reliability together with reduced complexity of operation.

When a multi-national specialist chemical manufacturer wanted to replace an increasingly problematic existing control system at one of its UK manufacturing sites, it was attracted to the advantages provided by the Siemens PCS7 OS control system. It not only sought to solve existing process control reliability and legacy issues, but the new system also offered a compatible and flexible solution for its future needs, together with a speedy migration timescale.

Degussa Evonik is a chemicals manufacturer and has long established links with Siemens and system integrator QSI who worked together to provide the engineering resource for this project. Indeed, the three companies have worked together on many control system and instrumentation projects within Degussa.

The background to the implementation of the PCS7 OS control system sprung from Degussa's need to replace an obsolete and unreliable control system operating in one of its production buildings at its Seal Sands site on Teeside.

The facility is a 'multi-purpose multi-Product' plant producing active ingredients for the pharmaceutical industry. Increasingly, Degussa was finding it problematic and expensive to support the legacy control system with, for instance, the batch manager failing when multiple batches were run through the plant and the supporting communications also proving unreliable.

Another issue with the existing system was that it was based on a now ageing UNIX hardware and software platform which led to ongoing development issues and limited availability of expertise to rectify matters both within Degussa and from external suppliers. Crucially, this lack of support would also hamper required changes when it came to manufacturing new products.

The challenge was to therefore find a control system for the production building that would meet a number of criteria including: increasing manufacturing output by optimising the batch manager operations, improving the overall reliability of the production process, reducing the complexity of the system, optimising the levels of expertise and experience that would work with any new system, installing it quickly and without undue impact on existing operations and, allowing, Degussa the ongoing flexibility to carry out process modifications as their production demands required into the future.

After an extensive review carried out by Degussa and QSI in the form of a FEED study, the decision was taken to implement the Siemens PCS7 OS solution as it offers answers to the requirements posed by Degussa's needs. A solution was selected which entailed maintaining the existing production building controllers in situ, but replacing the SCADA front end with the new PCS7 OS control system. The advantage of this approach was that it required only limited modification to the legacy controller configuration, while implementing the complete replacement of the graphics and batch manager. Improving the reliability of both of these areas, which was one of the key elements that had to be addressed. This solution was beneficial both from a cost point of view, as well as enabling a swift and timely system migration which saw the PCS7 OS swapped over and tested within a three week period - minimising any potential production disruption.

The PCS7 OS now offers Degussa a number of advantages going forward. As an integrated product within the PCS7 range, the company will benefit from ongoing system developments, improvements and upgrades ensuring it continues to deliver at optimum levels. Importantly for Degussa the complete system is driven from a single source of supply via Siemens. Tools within the system also provide for a proceduralised approach to software development for future expansion of the production building in question. To support the Degussa workforce, training courses are provided so that they are well versed in the PCS7 OS system and this ongoing commitment will ensure it reaches maximum potential for delivery. Reliability issues in the production building have now been solved and Degussa has seen both an improved availability and an increase in throughput, which Degussa are hoping to quantify over the next few campaigns.

Jeremy Hands for QSI says: "This is an integrated solution that is actively supported and developed by Siemens. It was installed quickly with minimal disruption to the existing operations, and It now means that Degussa's previous unreliable production experience with the building in question has been addressed. We are now moving forward with Degussa looking at a number of new projects. Looking to the future, as Siemens continue to develop the capability of PCS7, further upgrades can be easily and swiftly implemented giving Degussa peace of mind that their chosen route is the right one not only for the present, but also for their changing needs into the future."

Julian Lightwing, project manager at Degussa Evonik, says: "The implementation of this system will play a pivotal role in helping us overcome our reliability issues at this particular production facility. We are also confident that by partnering with Siemens we will reap the benefit of future system developments which can be easily added to the PCS7 solution."

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