Control-Disk valves improve throughput at INEOS Chlor 19 January 2011

Engineers at INEOS Chlor's Runcorn plant are reporting process variability reduced by 5% since replacing traditional butterfly valves with Emerson's enhanced Fisher Control-Disk valves.

Barry Makepeace, INEOS Chlor control and instrumentation engineer, says this improvement has, in turn, enabled the plant to increase throughput, avoid several unplanned shutdowns that could have cost as much as 450,000 Euros, and achieve a 96% OEE (overall equipment effectiveness) rating.

"For a plant this size, even a modest reduction in variability can have a significant payback," comments Makepeace. "The Control-Disk valve applications not only saved us money, but also enabled us to optimise process control without sacrificing flow capacity or needing to re-pipe," he adds.

The Runcorn plant had been using traditional butterfly valves to control temperature and flow of cooling water to primary condensers. Tight control is essential because, if the condensers' temperature is too low, there will be residual chlorine in the system, which has to be removed. If the temperature is too high, there is an increased risk of a safety trip or plant shutdown. Each trip and subsequent unplanned shutdown can cost INEOS Chlor 75,000 Euros.

Standard butterfly valves have a small control range and a large deadband, which reduced their ability to respond to temperature changes. In 12 months, the plant had experienced 23 trips, leading to a significant loss of production.

Working with Emerson valve specialists, INEOS Chlor replaced four butterflies with the Fisher Control-Disk design. Its effective control range (between 15% and 70% of travel) approaches that of a segmented ball valve. Tighter, more reliable valve control enabled plant operators to optimise temperature setpoints and avoid at least six unplanned shutdowns.

Brian Tinham

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