Moving bed biomass fractionation system and method

Abstract

Countercurrent extraction of lignocellulosic biomass such as trees, grasses, shrubs, and agricultural residues or waste involves the separation of cellulose fibers from other constituents, for subsequent use in the manufacture of paper, plastics, ethanol, and other industrial chemicals. Systems and methods involve continuous, multiple processing steps that may include chemical reactions with mixing at elevated temperature and / or pressure, efficient reagent or solvent utilization, filtration at elevated temperature and / or pressure, controlled discharge of liquid and solid products, and energy recuperation.

Description

BACKGROUND OF THE INVENTION[0001]Embodiments of the present invention relate to systems and methods for the fractionation of lignocellulosic biomass into its components, including extractives, hemicellulose, lignin, and cellulose.[0002]Natural cellulosic feedstocks typically are referred to as “biomass”. Many types of biomass, including wood, paper, agricultural residues, herbaceous crops, and lignocellulosic municipal and industrial solid wastes have been considered as feedstocks for the manufacture of a wide range of goods. These biomass materials consist primarily of cellulose, hemicellulose, and lignin bound together in a complex gel-like structure along with small quantities of extractives, pectins, proteins, and ash. Due to the complex chemical structure of the biomass material, microorganisms and enzymes cannot effectively attack the cellulose without prior treatment because the cellulose is highly inaccessible to enzymes or bacteria. This inaccessibility is illustrated by th...

AI Technical Summary

Benefits of technology

"The present invention provides methods and systems for the continuous, countercurrent fractionation of lignocellulosic biomass to increase product yields. The techniques involve elevated temperature and pressure to minimize processing time, and the efficient use of chemical reagents and solvents. The process includes feeding the biomass into a pressurized reaction vessel, injecting a wash liquid into the vessel, and discharging the wash liquid and processed biomass. The system can also include a simulated moving bed system for the countercurrent fractionation of biomass. The technical effects include improved product yields, reduced hemicellulose removal, and increased efficiency of the process."

Problems solved by technology

Due to the complex chemical structure of the biomass material, microorganisms and enzymes cannot effectively attack the cellulose without prior treatment because the cellulose is highly inaccessible to enzymes or bacteria.

This inaccessibility is illustrated by the inability of cattle to digest wood with its high lignin content even though they can digest cellulose from such material as grass.

Commercial processes for producing cellulose pulp from wood generally depend on inorganic chemicals as the extracting agent and do not yield lignin as a valuable byproduct.

If a large proportion of white liquor is used in connection with the impregnation, this exposes fibers to the aggressive effect of the white liquor, with carbohydrates degradation and loss of fiber strength.

The separation of cellulose from other biomass constituents is difficult, in part because the chemical structure of lignocellulosic biomass is so complex.

Biomass is widely recognized as a potential raw material for the production of transportation fuel and industrial chemicals, but an economically competitive commercial biorefinery has yet to be devised.

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