Radar succeeds with difficult level measurement

The new Rosemount Guided Wave Radar technology has proved reliable in monitoring a turbulent liquid propane surface level.

Liquid propane is used as a refrigerant in various industrial chemical plants: a standard process problem is monitoring the level of propane liquid in the accumulator tanks, to control the re-circulation process and ensure the propane supply is not exhausted.

Because of surface turbulence, low dielectric constant and temperature variations in the liquid, level measurement has historically been unreliable in this application.

Faced with this problem, engineers from Emerson Process Management applied the latest Guided Wave Radar (GWR) based level measurement system, the Rosemount Model 3300.

This was felt to be more reliable technology for this application, because it has proved tolerant of liquid density changes and surface turbulence in other similar process vessels.

With GWR, the radar signal is sent down a probe, and one of the Rosemount standard probe designs is coaxial in construction, concentrating the measurement into a specific defined area, almost like a stilling well.

This increases the signal to noise ratio of the surface signal, when working with such low and variable dielectric fluids.

The test site had a probe length of 1.5 metres, and was installed through a flange on an existing process connection on the side of the tank.

The propane level was detected immediately, and the measurement system has made what are reported to be accurate measurements for several months.

The plant management regard this as a persistent problem that has now been eliminated.

The site instrument engineer was enthusiastic: "Emerson worked with us, presented a Rosemount radar solution, and now our control system can work as per design for the first time".

The Rosemount 3300 series radar level transmitter has the sensitivity to handle difficult interface measurement requirements, such as occur within tanks with boiling or agitated surfaces.

It is designed for monitoring and tracking both surface level, and interface levels, where two liquids separate into immiscible layers.

The enhanced sensitivity required for such interface measurement duties enables the Rosemount 3300 to perform where the interface to be detected is difficult to define.

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