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Drying Technologies

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Wood chips and many other high moisture sources of biomass must be dried and milled prior to conversion to densified fuel pellets, co-firing with coal to produce power, or otherwise converted to bioenergy using thermal methods. Up to 75% of the energy used by pellet mills is consumed for drying and particle size reduction (aka comminution). Drying and comminution can add $25 - $30 per ton to the cost of non-densified small-particle biomass fuels and feedstocks.

We are addressing the need by developing new data sets for drying parameters specific to biomass feedstocks and physical process model-predictive dryer control strategies / algorithms that can be incorporated into industrial control systems. Prior research results from Forest Concepts' studies suggest that dryer residence time can be reduced by more than half, and that energy consumption can be reduced by one-third with more optimal feedstock comminution, dryer design, and dryer operation.

Selected Related Publications

Advances in Woody Biomass Drying by Taking Advantage of Surface Properties

Lanning C.J, Fridley, J.L.. 2012. Advances in Woody Biomass Drying by Taking Advantage of Surface Properties. ASABE Paper No. 12-1337119. St. Joseph, MI: American Society of Agricultural and Biological Engineers.

Advances in Woody Biomass Drying by Taking Advantage of Surface Properties

Abstract:

Comprehensive models for grain drying have been derived using critical data available from literature dating back to Shedd's 1953 work on pressure drop. Although dryer design data for grains and many industrial materials are known, Forest Concepts has developed data and evidence that biomass feedstocks are sufficiently unique that published design data is not applicable. Adaptations of grain models to woody biomass are difficult as many of the coefficients used in the models are unknown. Further, typical grain drying temperatures, around 65°C, are well below the "low" temperature of 100°C often targeted in cellulosic feedstock preparation. Forest Concepts is developing a model to better understand wood biomass drying, particularly in the context of conversion processes. Experimental data shows that the drying rate of Crumbles® precision particles is increased by nearly 100% when compared to equivalent traditional wood particles by taking advantage of biological properties. Checked surface properties of Crumbles® particles expedited diffusion rate of liquid to the wood surface thereby reducing total energy cost of drying. Expedited drying creates an opportunity for smaller dryers at reduced capital cost for equivalent throughput.

Related Patents

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