Thursday 18 March 2010

Advanced control reduces hydrogen venting and increases fuel supply to onsite boilers

Emerson’s PlantWeb™ architecture enables INEOS Chlor to reduce fuel costs by £3 million a year at British chlorine plant

Emerson Process Management’s PlantWeb™ digital architecture is helping the INEOS Chlor plant at Runcorn (GB) reduce annual fuel costs by approximately £3 million (ca €3.4m). Using PlantWeb’s advanced control and predictive maintenance technologies, INEOS Chlor has been able to reduce venting of hydrogen gas and instead use it as a fuel to heat onsite boilers for power generation.

INEOS Chlor is one of the major chlor-alkali producers in Europe and a global leader in chlorine derivatives. Its Runcorn operation uses two methods of chlorine production: mercury cell electrolysis, and a newer Membrane Chlorine Plant (MCP) process. Hydrogen is a by-product of both methods.

Their automation team reduced purchased-fuel costs by developing a control strategy that directs more of the excess hydrogen to the plant's boilers while preventing wide variations in hydrogen gas pressure that could lead to boiler trips or equipment damage.

To implement this strategy, they took advantage of the flexibility and superior control capabilities of Emerson's PlantWeb architecture, including the DeltaV™ digital automation system.

“The great thing about the DeltaV system is the wide range of programming function blocks available and the ability to write customised code when that would help us reach our goals,” explained Philip Masding, Process Control Manager, INEOS Chlor. “The DeltaV system itself is extremely flexible and powerful and allows you to do pretty much whatever you want so long as you have the imagination to take advantage of its capabilities.”

Instrumentation that is also part of the PlantWeb architecture provides accurate measurement and control essential to the new control strategy's success. Emerson's Rosemount® pressure and flow devices and Fisher® intelligent valves are used throughout the compressor, boiler and chlorine processing plants. These devices are networked using Foundation fieldbus, and Emerson’s AMS™ Suite predictive maintenance software and AMS ValveLink® software tool are used to monitor instrument status and verify the valves are working properly, without stiction that could adversely affect control.

The INEOS Chlor team also implemented a new monitoring system to automatically calculate venting totals and costs based on actual gas prices. Hydrogen venting has been reduced by 90%, with the resulting increase in hydrogen available as fuel saving approximately £3 million a year in natural gas costs. The improved control has also prevented 10 or more boiler trips and dozens of events that would have exposed manufacturing equipment to potentially damaging high pressures.

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