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Softflow PLC

Actionable Insight using Aquidata’s Softflow PLC.

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The Challenge

While the requirements around fiscal metering are heavily regulated, there are no similar constraints around the metering data from non-fiscal plant streams commonly used to provide an insight into, or to control, the performance of the process plant. Many older assets in the North Sea have therefore used the platform Distributed Control System (DCS) to carry out rudimentary plant metering. It is generally the case however that these systems do not carry out the measurement calculations to the commonly required and recognised standards, and they tend to use a simplified version of the equivalent calculations that would be carried out by a dedicated fiscal grade flow computer. While fit for purpose in some circumstances, this can pose a problem around accuracy, traceability, and consistency of measurement, rendering the information less useful to the various engineering groups who rely on this data.


Our Solution

During an upgrade of their offshore measurements system we worked with our client to extend the coverage of their non-fiscal plant measurement and migrate existing measurement streams from their legacy DCS to a new SoftFlow installation. Softflow is Aquidata XL’s flow computing solution that provides stream and station flow measurement and control on an industry standard PLC platform.

For this application, Softflow was used to process 22 new metering streams with directly connected I/O, and 109 metering streams using legacy I/O already routed to the DCS with raw measurement data now handed off digitally to Softflow. Calculated data was then handed back to the DCS for indication and control, preserving the functionality of the legacy DCS systems. The final application included support for DP, Ultrasonic, Vortex, Turbine, and Coriolis streams, with additional functionality provided to drive two liquid sampling systems operating in either time or flow proportional mode.

The resulting system provides a high density measurement solution that would be impossible to achieve using conventional flow computer technology at an equivalent cost and within the same physical space constraints.

The Proof

Following introduction of the upgraded metering system the engineering and management user groups have seen a step change in the accuracy and availability of their metering and quality measurement information, and hence their understanding of how the process plant behaves has increased.

The upgraded system also allows users to reliably find the information they need to diagnose operational incidents using both fixed reports and also by constructing their own queries to pull data for any period and in any combination. This facility was used to good effect to identify a set of conditions where flow parameters exceeded design conditions causing gas breakout to occur in the Coriolis stream resulting in disruption of the metered values.  Having clearly established what was happening a solution was devised to prevent further occurrence of the problem.

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