Interface measurement with OPTIFLEX

Tankfarm at Onyx

Interfaces can now be measured up to a distance of 20m with OPTIFLEX, the guided radar (TDR) from KROHNE. Until recently the maximum length of the double cable and therefore the possibility of measuring interfaces was restricted to 8m due to physical reasons.

Tests at Onyx, Norway?s leading waste management and recycling company have been successfully completed. For measuring interfaces two reflections have to be evaluated. On the one hand the level pulse and on the other hand the interface pulse has to be analysed, which will, as a matter of course be absorbed by the product.

The double cable as well as the coax version provide a stronger focused pulse and therefore a bigger signal amplitude than common level devices. OPTIFLEX features a 2 GHz bandwidth, which is approximately twice as high as normal and produces considerably slimmer pulses and allows detection of interfaces to a minimum layer thickness of 50mm.

Interface measurement in high tanks

KROHNE also offers a solution to reliably detect interfaces even in bigger tanks. As OPTIFLEX offers a relatively high dynamic, the opportunity arose to use a single cable for interface measurement. After successful laboratory tests, the excellent results were confirmed during field tests at Onyx in Norway. The Onyx rig is meant to separate oil and water. Both products are filled in the tank as mixed products, for example as remnant after cleaning the tanks of crude oil vessels, and remain there until the oil has separated from the water and further cleaning processes can be executed.

The tests at Onyx were carried out with both a single and a double cable in order to be able to compare the readings. During both tests Onyx received two distinct reflections ? one from the oil surface, the second from the interface oil / water. The signal progression of both sensors was almost identical. As long as the interface is clearly defined, an interface measurement with the guided radar of OPTIFLEX and a mono cable fully satisfies the customer?s needs. Due to the fact that containers of sizes comparable with those at Onyx are typically used as storage tanks and don?t show strong emulsions, OPTIFLEX with a 4mm mono cable up to a sensor length of 20m can be used for measuring interfaces reliably.

Information: KROHNE Messtechnik GmbH & Co. KG, Thomas Zimmerling,
E-Mail: TZimmerling@krohne.de

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