Pulp Paper & Logistics
EMERSON 25
Despite the dusty conditions the 5408 has required less maintenance and downtime, leading to improved productivity
radar transmitters based on FMCW technology maximise their signal strength, enabling them to accurately and reliably measure low dielectric media.
Case study: the Södra Cell mill Typical examples of how advanced non-contact radar technology is helping pulp producers to meet their toughest level measurement challenges can be seen at the Södra Cell mill at Värö in Sweden. The mill is one of the world’s most modern pulp production facilities, producing around 700,000 tons of high-quality, chlorine-free softwood pulp and 1.6 TWh of energy annually. The company was facing two demanding level measurement challenges, which it solved by installing advanced non-contacting radar transmitters from Emerson. The first challenging application
temperature and pressure. Non- contacting radar transmitters are suitable in these applications as they do not need to compensate for density, high temperatures or pressure changes.
Solids measurement Measuring the level of solids and powders – in lime silos, for instance – have an uneven material surface that creates false
signal reflections. By using a signal processing algorithm that merges surface peaks, the latest radar transmitters based on FMCW technology are able to overcome this challenge and provide a high degree of accuracy.
Dust generation Non-contacting radar transmitters usually handle dust well, but a heavy layer can clog
the antenna and block the signal. The latest devices overcome this with an integrated air purging system that cleans the antenna.
Dielectric constant A low dielectric constant – such as in the lime powder used in pulp production – means that much of the energy from pulse radar transmitters is absorbed, so less is reflected. Non-contact
required the level measurement of very fine lime powder stored in 27 metre high silos. As the powder piles up inside, the material tends to form in towers beneath the inlet. In addition, the powder covers everything with a fine layer that is prone to build-up, making it difficult to measure the level with any degree of accuracy. Other challenging factors include the long distance to be measured and the powder’s low dielectric constant. Södra had tried using mechanical devices, ultrasonic technology and radars, but their performance was affected by clogging. With the majority of non-contacting radar devices, 4
May/June 2019
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