Tuesday, January 18, 2011

Valves improve throughput and reduce variability

Enhanced butterfly valves help plant avoid six unplanned shutdowns and save an estimated €450,000.

INEOS Chlor, a major European producer of chlor-alkali and chlorine derivatives, reduced process variability by 5 per cent at its plant in Runcorn (GB), by replacing traditional butterfly valves with Fisher® Control-Disk™ valves from Emerson Process Management. The reduced variability enabled the plant to increase throughput, avoid several unplanned shutdowns that could have cost as much as 450,000 Euros, and achieve a 96 per cent Overall Equipment Effectiveness rating for the unit where the valves were installed.

Emerson’s Fisher Control-Disk valves
improve throughput & reduce variability
at INEOS Chlor plan
“For a plant this size, even a modest reduction in variability can have a significant payback," said Barry Makepeace, INEOS Chlor control & instrumentation engineer. "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.”

The Runcorn plant had previously used traditional butterfly valves to control the temperature and flow of cooling water to the 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 up to 75,000 Euros.

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

Working with Emerson valve experts, INEOS Chlor replaced four traditional butterfly valves with the new Fisher Control-Disk design. Its effective control range (between 15 per cent and 70 per cent of travel) approaches that of a segmented ball valve. Tighter, more reliable valve control enabled plant operators to optimise temperature set points and avoid at least six unplanned shutdowns.

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