System and method for preparation of solid biomass by torrefaction
First Claim
1. A method for preparing a torrefied biomass fuel, the method comprising:
- extracting moisture from a relatively wet biomass fuel in a dryer to produce a relatively dry biomass fuel;
extracting all remaining moisture from the relatively dry biomass fuel using steam at a temperature of about 482°
C. (900°
F.) to produce a dried biomass fuel;
conveying the dried biomass fuel downward using gravity for subsequent processing;
torrefying the dried biomass fuel to produce the torrefied biomass fuel and torrefaction gases;
venting a gaseous mixture of the steam and the torrefaction gases to a heat exchanger;
heating the gaseous mixture via heat exchange with a flue gas; and
using the heated gaseous mixture to support the extraction of the remaining moisture from the relatively dry biomass and the torrefaction of the dried biomass fuel.
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Abstract
Methods and systems for preparing a torrefied biomass fuel are disclosed. Moisture is initially extracted from relatively wet biomass fuel to produce a relatively dry biomass fuel. Remaining moisture is then extracted from the relatively dry biomass fuel in a final drying stage, using steam at a temperature of about 900° F. The resulting dried biomass fuel is conveyed downward using gravity and undergoes torrefaction, which produces torrefied biomass fuel and torrefaction gases. A gaseous mixture of steam and torrefaction gases is vented to a heat exchanger, where the gaseous mixture is heated by a flue gas, and the heated gaseous mixture is used to support the extraction of the remaining moisture in the final drying stage and to support the torrefaction of the dried biomass fuel. Embodiments disclosed herein efficiently use available energy resources to the benefit of manufacturers, consumers, and the environment.
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Citations
9 Claims
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1. A method for preparing a torrefied biomass fuel, the method comprising:
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extracting moisture from a relatively wet biomass fuel in a dryer to produce a relatively dry biomass fuel; extracting all remaining moisture from the relatively dry biomass fuel using steam at a temperature of about 482°
C. (900°
F.) to produce a dried biomass fuel;conveying the dried biomass fuel downward using gravity for subsequent processing; torrefying the dried biomass fuel to produce the torrefied biomass fuel and torrefaction gases; venting a gaseous mixture of the steam and the torrefaction gases to a heat exchanger; heating the gaseous mixture via heat exchange with a flue gas; and using the heated gaseous mixture to support the extraction of the remaining moisture from the relatively dry biomass and the torrefaction of the dried biomass fuel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification