Radar Level Measurement for Cryogenic Tank Storage

If you are unfamiliar with cryogenic processes such as those found liquefied natural gas (LNG) plants, then you may be unaware of some of their unique challenges. One big one is overfill prevention and inventory measurement for cryogenic storage tanks. A cryogenic tank is not opened during operation and normally not accessed for maintenance purposes during its entire operating lifespan.

A 4:35 YouTube video, Inventory Measurement Solutions for Full Containment Cryogenic Storage Tanks highlights some measurement challenges and how radar level measurement helps to solve them.

Level measurements are required not only for accurate inventory measurements, but also for overfill prevention. For this overfill safety application, the level measurement devices must be periodically proof tested to verify that they are working correctly and can provide the sensing signal for the safety instrumented function (SIF) to take the tank to a safe state should the demand occur. Tank farm operators need accurate and reliable tank gauging systems that minimize operating and maintenance costs throughout the lifecycles of the tanks.

The video highlights a world-leading Swedish company in small-scale LNG handling. Any unplanned downtime results in a million-dollar loss. A Rosemount Tank Gauging System provides level measurement, average temperature, temperature profile, roll-over prevention, leak detection and cool-down control for cryogenic and refrigerated storage in full-containment tanks. These tank gauging systems replace the traditional approach of high maintenance and difficult to proof test mechanical gauges.

A Rosemount 5900S non-contacting radar level gauge provides certified custody transfer accuracy, better inventory management, reliable loss control data, and is certified for use in API 2350 overfill safety applications up to SIL 3. Non-contacting radar level measurement is the fastest growing tank gauging technology used in cryogenic applications.

Three of these radar gauges are typically used for level measurement and voted (2-out-of-3 in the SIF logic solver) overfill prevention. Emerson’s Victoria Lund Mattsson describes the several different types of temperature measurements needed in these full-containment tanks and the LNG solution addresses the different types. These temperature measurements are needed for volume calculations and stratification monitoring.

These Rosemount 2240S multi-input temperature transmitter is with Rosemount 566 and Rosemount 614 spot temperature sensors to provide the data from measurement points a various parts of the tanks. Sensors are available for cool-down control procedures and leak detection.

These levels and temperatures as well as density profile measurements feed the Rosemount TankMaster Inventory Management software to provide operations with overviews, configuration, setup and service. It calculates volume and mass for inventory and custody transfer for these full-containment cryogenic and refrigerated tanks.

From a safety standpoint, these radar tank gauges can be proof tested remotely from the control room. This avoids the need of the traditional approach to climb the tanks and test locally at the gauge.

Watch the video and visit the Tank Gauging System section on Emerson.com for more on this solution for cryogenic applications. You can also connect and interact with other tank gauging and level measurement experts in the Measurement Instrumentation group in the Emerson Exchange 365 community and/or at the Sept. 23-27 Emerson Exchange conference in Nashville.

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