Powerful combo: Magnetostrictive level sensors and wireless transmitters
Truman Arnold Companies (TAC) wanted to keep a close eye on its daily shipments involving more than 1 million gallons of petroleum at its Caddo Mills, TX, terminal. The approach would require very precise tank level measurements communicating via wireless over the tank farm.
The ultimate solution used a combination of MTS Systems Corp . MG Level Plus liquid-level transmitters combined with Siemens Energy & Automation’s wireless control capabilities. “TAC needed a solution that would accurately measure the petroleum, and the MG transmitter provides required accuracy, field replacement, and compatibility with the Siemens wireless control system,” says Lee Aiken, product marketing manager, MTS Sensors.
The TAC petroleum terminal in Caddo Mills, connects the company to the Explorer pipeline, which transports petroleum from the Gulf of Mexico to Indiana. For every 10-day cycle, the terminal receives an average of 200,000 barrels of petroleum that is stored in nine closed-roof storage tanks ranging from 20,000 to 110,000 barrels, with a total storage capacity of 650,000 barrels.
The challenge when moving such a large amount of petroleum products is maintaining accurate control of the process. TAC cannot afford to run out of any of the petroleum products they carry or have inaccuracies during custody transfer. Inaccuracy can result in TAC either paying for product that was not received or by not charging for product that was delivered. For every 0.5% in custody transfer error that TAC endures, the company loses 1,000 barrels of product per cycle at the Caddo Mills terminal. Given the number of terminals that TAC operates, such small inaccuracies can reach into the tens of millions of dollars over a year’s time.
MTS Sensors worked with Siemens to provide TAC with the ability to go wireless. Siemens transceivers and I/O modules work together to create a wireless network for any application.
Eliminating the need to install signal cables from the storage tank into a control room, TAC saved on costs for items such as conduit, wire, installation, and installation time. And because TAC engineers can now monitor all of the tanks without having to leave the central office, they can spend more time focusing on other more productive aspects of their jobs.
TAC engineers found the installation process easy since the MG transmitter and its stainless steel flexible hose allows a single person to carry the transmitter to the top of the tank and install it. The MG transmitter is suitable for vessels from .51 to 18.3 meter height (20 to 720 in.), and is ideal for process control, bulk storage, precision inventory control and product level, interface level, and temperature monitoring.
Modular construction allows the transmitter to be serviced or replaced without having to shut down the tank or process. MTS says the MG series provides 3-in-1 measurement of the product level, interface level, and temperature. Every transmitter is built custom to the application and can operate on either 12 or 24 Vdc via its 4-wire Modbus connection.
—Edited by Peter Welander, process industries editor, PWelander@cfemedia.com ,
Control Engineering Process Instrumentation & Sensors Monthly
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