DT301 helps mill improve measurement accuracy, Solutions!, Online Exclusives, January 2004

DT301 HELPS MILL IMPROVE MEASUREMENT ACCURACY

Having trouble obtaining accurate pulp density measurements? You’ll want to learn about how Stora Enso’s Nymölla, Sweden plant improved measurement accuracy, and significantly lowered steam consumption, by using Smar’s DT301 Digital Transmitter.

The Stora Enso plant located in Nymölla, in southern Sweden, is a facility that handles the entire papermaking process, from preparation of pulp through to the end product of fine paper. They are also the first customer in the Scandinavian countries to use digital transmitter (DT) technology from Smar International. Founded in Brazil in 1972, Smar now has subsidiaries in regions around the world and representatives in 60 countries.

Stora Enso chose the DT301 Intelligent Concentration/Density Transmitter, developed for the continuous, online measurement of liquid concentration and density in industrial processes. Its pioneer technology consists of a capacitive type differential pressure transmitter coupled to a pair of pressure repeaters immersed in the process. A temperature sensor located between the two pressure repeaters is used to compensate the temperature variations in the process fluid. Dedicated software, by means of an algorithm, calculates the fluid density. Depending on the industrial process, density may be expressed in Brix degree, Gay-Lussac degree, Baumé degree, Plato degree, or concentration.

DT301 installed at Stora Enso-Sweden

Designed for process control applications, these 2-wire transmitters generate a 4-20 mA signal proportional to the concentration/density. Digital communication for remote calibration and monitoring is also provided.

Working at Nymölla
For pulp treatment, the Nymölla mill uses a sulphite boiler and measure liquors in several places in the production. Previously, they used the same concept of differential pressure, but measured with a pressure transmitter.

The differential pressure transmitter has the high side on one point of a heat exchanger and the low on the other point. There is no temperature compensation. To prevent blocking of the capillaries tubes to the transmitter, they required a constant purge of water in the process. However, black liquor still created blockage in the tubes and a signal error in the density reading.

Using the DT301, the mill now saves 180 kg per hour of steam. The total cost savings in lower steam consumption over the course of a year is estimated to US$16,000. Storo Enso realized that the accuracy of the DT is much higher and they can now get a signal directly in Baumé, which was previously estimated. Overall, they have higher performance in the process, improved control of the quality and significant financial savings.

The production was running in a cycle of 8 hours production and 8 hours of cleaning with condensate. With implementation of the DT, they expect to cut production time spent with the cleaning process—and save costs associated with the increased cycle of productivity hours.

The application experience with the DT was so successful that Stora Enso has placed an additional order for four units through Beving Elektronik, the Swedish representative.

For more information, contact the Smar International representative nearest you—visit http://www.smar.com/contactus.asp.