Case Study

Radar Level Gauging Provides Better Control

Originally developed as a level gauge for marine tankers, the Saab TankRadar Pro is now finding use in a variety of process industries applications. At Casco Products, a Swedish division of Akzo Nobel that manufactures adhesives, impregnated papers and other specialty products, the device is being used to provide realtime measurement of reactants as they fill vessels, and as a quality check of weighscale measurements. The presence of swirling, turbulent surfaces on the liquid volumes complicates accurate measurement; the TankRadar has handled these situations so well that the company is in the process of automating the metering functions, and making the level gauge a key part of the automation scheme.

The new level gauge based on advanced radar technique for non-contact measuring. It is especially designed for the process industry with the market's most advanced signal processing. The sensitivity in a radar level gauge is essential for the possibility of receiving echoes from the surface. Saab says that its product's sensitivity is a thousand times finer than other radar level gauges.

"The TankRadar Pro ensures complete safety, and has proven reliable and easy to install," says Johnny Lundberg, Project Manager at Casco. He is arranging the automation of the company's resin production and has not found any level gauge better adapted to his needs. To be able to measure with high reliability in process tanks a very good signal processing is necessary since the surface is never calm in a tank under operation.

By using a reliable radar level gauge, process handling is safer for both personnel and environment. In addition the user can optimize his processes both economically and technically. Process engineer Magnus Lindström comments on the benefits to be gained by double-checking readings from the weighscales. The company had previously used scales to measure the required amount of raw materials for processing, i.e. urea and formalin. In the event of the scales giving an inaccurate reading, the error would perpetuate along the production line and would not be discovered until the resin emerged as a finished product. "Different kinds of incidents which have led to a lot of extra work can now be prevented or discovered at a very early stage thanks to the TankRadar Pro," says Lindström.

The radar level gauges can be integrated in systems with supervision functions. The level gauge comes in three versions for simple measuring in applications with high hygiene requirements, or where there are corrosive liquids. It is suitable for these kinds of applications because it has no moving parts and never is in contact with the liquid (Figure 1). Measurements are not affected by variations in temperature or pressure, turbulence, evaporation, condensation or liquid properties such as density or dielectric constant.

Figure 1: The TankRadar Pro.

The self-calibrating gauge has software developed by Saab Tank Control for intelligent signal processing, which ensures very fast and reliable measuring. The software, with several advanced logic and memory functions, eliminates the interface effects of echoes within the tank. At Casco, the level gauge provides full control over reactor content by displaying trend data. The data curves show the status of the content, for example blending and boiling, which means that only high standard products now leave the reactor.

The TankRadar gauge was developed in the mid-1970s for marine applications, and later adapted for refineries and tank terminals. Since then, 35,000 gauges have been delivered.

Edited by Nick Basta

For more information: Malcolm Burke Saab Tank Control, Houston, TX. Tel: 1-800-722-2865.

In Sweden: Saab Marine Electronics AB, Box 13045 S-40251 Goteborg, Sweden. Tel: +46-31-337-0000.