USEFULNESS AND SIGNIFICANCE OF ENERGY AND MASS BALANCES OF A FLUIDIZED SUPERHEATED STEAM DRYER

Abstract

The key characteristics of a drying method for biomass are, firstly, its ability to control temperature, steam flow and pressure drop and, secondly, its ability to stabilise the material flows, particularly the outgoing moisture content. This paper presents the usefulness and significance of using energy and mass balances to improve the measurements and control systems of a drying system of industrial size in order to fulfil the moisture content requirements for biomass compression. In order to assess the reliability and accuracy of the measurements a series of tests at four different temperature and pressure levels were conducted. By verifying the plant's energy and mass balances the accuracy of the measurements could be determined and the control system was evaluated. The test results are used to determine the energy and mass balances. The control system yields good stability for the pressure drop, the temperature and the gas flow.

Keywords:

• Biomass
• Drying
• Sawdust
• Spouted bed

ACKNOWLEDGMENTS

We thank Professor Bengt Månsson, Karlstad University Sweden, and Professor Göran Lönner, The Swedish University of Agricultural Science, for valuable comments. The work has been done in cooperation with the Värmland Forest Owners Association via affiliated company Nordiskt Rostat Trä, the Sawmills' Research Institute, the Federation of Swedish Farmers (LRF) and the Swedish National Board for Industrial and Technical Development (NUTEK).