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Products and solutions, 2007-11-26, 11:00 AM

Precision work

ThyssenKrupp Xervon has completed a particularly delicate task at a PVC production site in Cologne-Merkenich, where the somewhat antiquated process instrumentation and control system was replaced by a modern one. Pre-assembly, connection and commissioning of the new instrumentation and control system were entrusted to the local electrical, measurement and control specialist. ThyssenKrupp Xervon had been awarded the maintenance and various other services for the industrial park on the former site of Wacker-Chemie in Cologne-Merkenich some years ago.

When the control system of a production plant is fully replaced, maximum attention is called for. The control system is the life-line of production and controls all the processes – from the raw material to the finished product. Without control, production grinds to a halt. If therefore the PVC production plant is shut down on a predetermined date so that the new system can be connected up and commissioned, there's no going back and no more putting it off. All the cables and lines have to be laid, and all the circuitry ready. A two-week production shutdown was all that the electrical, measurement and control specialists had in Cologne-Merkenich to detach the various parts of the plant from the old control system and reconnect about 4,200 measuring points during the final critical phase. All other assembly, conversion and installation work had to be completed beforehand while production was still running. ThyssenKrupp Xervon therefore got down to work back in November.

"We re-laid about 20,000 meters of jumper wire, 2,000 meters of control cables and the same quantity again of bus cables," says electrical engineer Peter Kujat, quantifying the huge quantity of materials employed. This was joined by the installation of 50 control cabinets, a multitude of terminal boxes and further conversion, assembly and connection tasks. Peter Kujat's team had to convert precisely 2,205 binary and 347 analog measuring points. They ran cables and lines from the control cabinets in the control room to the various production units and installed a new bus system that bundles the data and passes them on to the control room. This is where the system's nerve center is located. All the data converge here, where they are processed by computers with the new software and displayed on monitors.

To as far as possible exclude potential sources of error in the required multitude of electrical installations in advance, local inspections were conducted for an early check of the already completed assembly work. "This way we could largely ensure that nothing could really go wrong later during connection and commissioning," says Peter Kujat explaining the quality-assuring procedure. The control specialist has been working at the Cologne-Merkenich for over twenty years now and has made many a gifted electrician into an electrical, measurement and control expert. "At an industrial site like this one, very special qualities are called for. It's not enough to just have a wide range of technical skills. Pronounced safety awareness is also essential." The strict explosion protection regulations apply to the whole of production. Access to the plant components, for instance, is only possible with a previously obtained work permit note. For major projects such as shutdowns or conversions, it's a help if you always have access to a pool of experienced manpower – either Xervon's own specialists or long-standing external partner firms.

During the final two-week phase in Merkenich, a Xervon team of twenty to thirty employees worked virtually around the clock in three shifts. Then another team took over for commissioning. "For this we deliberately choose other people, because they are more likely to spot faulty connections or faulty wiring," says the experienced electrical engineer, explaining the team change. "If you've been changing a system over for weeks, you can lose your neutrality and sometimes overlook the obvious."

In fact, however, there were neither faults nor deadline problems. Excellent prospects for the trouble-free running of the two following conversion projects under Xervon's supervision next year and the year after. The PVC manufacturer has divided the modernization of its process instrumentation and control system into three segments. Segment I (polymerization, VC/RVC metering), Segment II (waste water & condensation, drying) in 2008 and Segment III (gasometer, alarm system) in 2009.

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