Emerson Exchange 365

by Walt Boyes

Roberto Gorbarán, instrument and electrical supervisor for Petrobras’ Zarate polystyrene plant, is a serial presenter at Emerson Exchange. Over the past ten years, he has presented a number of papers on the improvements the Zarate plant has made to increase performance and availability.

He, along with Fabian Robin, flow application consultant for Micro Motion and Rosemount Flow, presented a simple story of how to solve a really large problem. Petrobras had, by using the diagnostic tools and other capabilities of PlantWeb and AMS suite, reduced plant shutdowns from ten days to three days in the last four years, but management wanted even more improvement. And those improvements demanded better quality measurements.

Unfortunately, taking any of the more than 40 Coriolis mass flow meters that are in use in Zarate, and other flow meters as well, out of service and sending them to calibration labs at interval was impossible. Meter verification and calibration would have to be done in house, in situ.

With help from Emerson, Petrobras designed a simple calibration cart. “Consisting of two Micro Motion ELITE meters, one 2-in. and one 0.5-in.,” said Robin, “a set of hand valves and a 1700 Micro Motion transmitter, the cart is taken to a point close to the meter. A bypass converter is installed to re-route the product flow around the meter, and the meter is hooked in series with the cart. Flow from the fire and gas water system is passed through the Master Meter on the Micro Motion cart and then through the meter.

The 475 handheld is used to read locally, and a laptop running the AMS SNAP-ON for Micro Motion meter verification was implemented to permit calibration traceability.

Gorbarán said, “This reduced average calibration time to three hours from ten, and improved the quality of calibration considerably. We also increased the time between calibrations, and now we can get advanced diagnostics.”

Now, he said, “we can even check the calibration of flow meters as varied as Coriolis and ultrasonic open channel flow meters.”

“Petrobras gets a reliable calibration in less time,” added Robin. "The AMS SNAP-ON has improved plant performance by making diagnostics easily available. This has made the maintenance routine more efficient, and allows better calibration traceability, and better documentation and certification.”

“The skid is just one tool,” Gorbarán said. “PlantWeb has lots of tools for us to use in our journey to continuous improvement.”