The Development of Large Pressurized Fluid Bed Steam Dryers from Fundamental Research to Industrial Plants

Abstract

Large industrial drying of particulate material (water evaporation 5 to 100 t/h) in air causes air pollution, and uses large energy supply. If the drying instead takes place in a closed system, under pressure in its own vapor, it will be possible to recover nearly 100% of the supplied energy as the energy leaves the dryer as a steam, which can be used as process steam for other purposes or be recompressed and used as an energy source for the same dryer. This will make it a heat pump dryer. Using the steam from the dryer means that air pollution with dust and volatile organic components (VOCs) will be fully avoided. That was the vision for the development over seven years starting with fundamental research followed by a pilot plant and a prototype. The ambitious goal has been reached. Thirty dryers have been built or are under construction. One dryer is currently evaporating 70 ton/h water saves 200 tons coal per day and does the drying without air pollution.

Keywords:

• CO₂ reduction
• Drying in steam
• Large industrial drying
• No air pollution
• Pressurized drying

ACKNOWLEDGMENTS

The authors want to thank Danisco A/S for having the vision to see the possibilities in a new drying technology and for supporting the development. Special thanks are due to Dr. Rud Frik Madsen, Director for Development, Danisco. Thanks are also due to the engineers, who worked scientifically, intensively, and enthusiastically through the years of development: Bjarne Winstrøm-Olsen (M. Sc., Danisco), Jørgen Borreskov (B. Sc., Danisco), Kåre Dinesen (M. Sc.).