INEOS Chlor select fieldbus for storage tanks

An on-going programme of regeneration at their site on the banks of the River Mersey has given INEOS Chlor the opportunity to make the first real inroads into the expanding world of fieldbus.

In the beginning, fieldbus was just an idea that appeared to offer an enviable range of benefits.

Now, it is a fully realised option and INEOS Chlor have stepped into the growing world of fieldbus - determined to exploit to the full all of the tangible benefits it brings.

Having dipped their toes in the water with some earlier tests and investigations, they felt confident enough to trust, and hence incorporate, fieldbus technology when developing the plans for a new plant.

INEOS Chlor is one of the major chlor-alkali producers in Europe and an acknowledged global leader in chlorine derivatives; consequently, production of chlorine itself is a significant part of their business model.

When it became apparent that the existing production facility, although still in use, was reaching the end of its economical working life and would need to be replaced, investment in a more up-to-date and cost effective manufacturing facility was clearly warranted.

The key raw material for chlorine production is salt - a resource for which the Cheshire area is well known.

The salt is mined by dissolving it in water to form brine, which is then simply piped "up the road" to the INEOS Chlor site at Runcorn for processing.

The old facility employed mercury-cells in the electrolysis of brine to create chlorine but modern improvements in technology have enabled production to move over to a newer and more environmentally-friendly membrane process.

The Genesis Project required the building of a large, two-stream chlorine plant, which was in the process of commissioning during Q2 2006.

Field instrumentation for control of these plants was chosen to embody fieldbus, as this would simplify and speed up the production of diagnostic information.

Earlier pilot projects had investigated the technology and the results were found to be very encouraging.

Consequently, the engineering team was keen to make the most of the diagnostic capabilities of fieldbus.

Automation is now a common byword, because staff can manage more processes more efficiently if they are not having to chase all over the plant to isolate the cause of a fault condition.

The improved ability to pinpoint fault conditions from a control station reduces diagnostic time and hence potential downtime.

At the core of their management system is the Emerson DeltaV, which was chosen for its known compatibility with Foundation fieldbus and Emerson previous experience in this field.

MTL-Relcom fieldbus products were already known and trusted by the local design team and so it needed little encouragement from Emerson with regard to compatibility to reinforce the decision to stay with this choice.

Field wiring was based upon the use of MTL-Relcom Megablock wiring hubs.

Located on DIN rail in small GRP enclosures around the plant, they provide a simple means of marshalling local connections from the individual field instruments and bringing them onto the bus.

The Megablocks have the advantage of allowing individual devices to be unplugged without disrupting the rest of the segment, while performing the important task of protecting the bus from accidental short-circuits in the spur wiring.

Trunk connections can easily be looped onwards to other Megablocks and, when the end of the bus is reached, a Foundation fieldbus terminator can simply be added to complete the job.

Back in the control room the DeltaV IO takes charge, aided by the MTL-Relcom FPS-I fieldbus power conditioners.

The latter provide redundant power conditioning for individual fieldbus networks from bulk DC supplies, while also terminating the fieldbus trunks at the host end.

The individual IPM power modules have galvanic isolation between input supplies and the output segments, are alarmed for instant recognition of a component failure and are "hot swappable" without interrupting operation.

All of this maximises up-time and helps in the diagnosis and recovery of faults that occur in even the best managed and maintained facilities.

While it is still early days to evaluate the long term benefits of this new system to INEOS Chlor, the integration of sound engineering judgement, innovative fieldbus technology and a solid management system must be a good beginning.

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