Heat exchanger control system for Citech units

Midland-ACS uses smart positioning with HART protocols for heat exchange systems control in the harsh environment of gas turbine heat recovery systems destined for the Al Shaheen oil field in Qatar

UK manufacturer Midland-ACS, has developed a control system capable of operating in the harsh environment of the gas turbine heat recovery systems destined for the Al Shaheen oil field in Qatar.

Working closely alongside Citech, formerly Alstom Energy Systems, the Midland-ACS design was chosen by the gas turbine heat recovery specialist, to control its innovative adjustable cylindrical damper design.

The Citech heat exchangers are designed specifically for use on the Maersk Oil operated Al Shaheen field offshore facilities, as part of a USD5 billion project to increase the output of the Qatar Al Shaheen oil field to 525,000 barrels per day, from its current level of 240,000 bpd.

Typically used in oil refineries, a total of 9 large bore cylinders, complete with three control panels, were provided to Citech to lift their cylindrical damper on the heat exchangers.

Manufactured to be Zone 1 (EExd) compliant with ATEX approved electrics, the cylinders have a bore of 160mm and a stroke of 916mm, lifting vertically to control each damper.

Made from an epoxy coated steel barrel and incorporating the hollow 316 stainless steel piston rod housing the linear transducer, the cylinders can operate in temperatures ranging from -20C to +80C.

Each bank of 3 cylinders is controlled by a separate control panel.

The linear transducers contained within the cylinders manage the stroke in the damper cylinder to control the heat exchange process.

Boosters used in conjunction with Smart positioners give a fast speed of operation.

The smart positioners also incorporate HART protocol.

HART or 'Highway Addressable Remote Transducer' protocol was chosen for its 1200 baud Frequency Shift Keying (FSK) process to superimpose high resolution digital information onto a conventional 4 to 2OmA analogue signal.

This allows both intelligent digital field devices and current generating physical actuation signals to integrate seamlessly in a wider automation system.

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