Control-valve diagnostics cut costs at Iggesund

Iggesund Paperboard, part of the Swedish Holmen Group, is using Emerson's Fisher control-valve diagnostic technology for predictive maintenance.

The Iggesund pulp and paperboard mill has an annual capacity of 330,000 tonnes of Invercote, a multi-layered solid bleached board.

To maximise availability, the plant has moved away from scheduled maintenance of control valves to the predictive-maintenance approach.

At the mill, diagnostic information from Fisher Fieldvue digital valve controllers is delivered to Emerson AMS Suite predictive maintenance software for access by plant personnel.

The AMS Valvelink software application delivers the valve-health data, enabling plant personnel to eliminate unplanned shutdowns, reduce inventory of new valves and spare parts and decrease maintenance time.

The Fieldvue real-time diagnostics, accessible online, give a fast and accurate insight into the health of the valves.

The Valvelink software can be used to quiz the Fieldvue devices for additional information or to run advanced diagnostic tests.

Travel-deviation alerts are a primary indicator of control-valve problems.

Tommy Nielsen, the site control-valve specialist, said: 'The travel-deviation alert is triggered when the control valve has not moved to its required position within a certain period of time.

'This alert can indicate many potential faults, such as an increase in friction, air leaks, mechanical faults or a physical blockage.

'Other alerts that we find useful are the cycle counter and the travel counter.

The cycle and travel counter alerts can determine control-loop stability since both can indicate that the loop may be oscillating.

Oscillations can cause poor control and can, in extreme circumstances, lead to the loop being put into manual control.

Poorly tuned loops can lead to quality issues, excessive raw-material usage, an increase in energy consumption and premature valve wear.

The maintenance department at Iggesund is employing these two alerts to improve the overall performance of the mill.

Fisher valves with Fieldvue digital valve controllers are key components of Emerson PlantWeb digital plant architecture, which networks process automation systems and instrumentation to provide efficient operations and predictive-technology driven maintenance for process facilities worldwide.

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