Here’s another guest post by me, Chris Womack. Custody transfer is today’s topic—specifically, improving level and temperature measurement of crude oil for custody transfer, while minimizing cost and disturbances to current operations.
Even more specifically, when Italy’s SIOT (Società Italiana per l’Oleodotto Transalpino S.p.A.) sought to update the aging radar-based level gauges that monitored its 32 storage tanks—and 35 million tons of crude oil—near Trieste, the company knew it couldn’t rely on the legacy 1960s-era cabling and shielding any longer.
But replacement would cost about €1 million ($1.31 million US) for the signal cabling alone. And laying new cable and trays could impede the terminal’s day-to-day business.
As Emerson’s Lena Hansson lays out for an article in the May-June issue of Tank Storage magazine, the Emerson team working with SIOT suggested sticking with radar level devices, but switching to wireless communication—even though the tank farm’s location is sometimes subject to strong “bora” winds, rain, sub-zero temperatures, and other inclement conditions. What’s more, the tanks are dispersed across a pretty wide area, sometimes 300 meters from one another.
To fit SIOT’s particular circumstances, the Emerson team recommended Rosemount TankRadar Rex gauges at each tank equipped with 12″ still-pipe array antennas, and connected through data acquisition units to the nine-spot temperature sensors already in place. For wireless communication, the team recommended Smart Wireless THUM Adapters through a wireless network established using two redundant Smart Wireless Gateways in the control center. The digital control system would then communicate with the Gateways using Modbus.
Initially, SIOT was skeptical of wireless. It’d had a bad experience with the technology, so the company wanted to try the new set-up on two tanks before upgrading the whole site.
So, with the Emerson team in daily communication, SIOT gave it a shot. “The test turned out as well as expected despite the worst bora in years stressing the system during commissioning,” says Massimo Diminish, SIOT technical assets manager, in the Tank Storage article.
Now that the company is satisfied with its new technology, it’ll soon expand wireless level and temperature monitoring to the whole 30-tank site. And that’s how to upgrade a tank farm’s level gauges inexpensively, but without sacrificing function.