Processes for producing energy-dense biomass for combustion

摘要

This invention provides processes to convert biomass into energy-dense biomass for combustion, alone or in combination with another solid fuel. Some embodiments provide processes for producing energy-dense biomass from cellulosic biomass, comprising extracting the feedstock with steam and/or hot water to produce an extract liquor containing hemicellulosic oligomers, dissolved lignin, and cellulose-rich solids; separating the extract liquor, to produce dewatered cellulose-rich solids; hydrolyzing the dewatered cellulose-rich solids, thereby removing a portion of the cellulose, to produce intermediate solids (with higher energy density) and a hydrolysate; drying the intermediate solids to produce energy-dense biomass; and optionally recovering fermentable sugars from the hydrolysate. The energy-dense biomass may be pelletized into biomass pellets, which may have a similar energy density as torrefied pellets from wood. The hemicellulosic oligomers may be further hydrolyzed to produce additional fermentable sugars. The fermentable sugars may be fermented to ethanol or another product.

主权项

1. A process for producing energy-dense biomass and fermentable sugars from cellulosic biomass, said process comprising:
(a) providing a feedstock comprising cellulosic biomass; (b) extracting said feedstock with steam and/or hot water under effective extraction conditions to produce an extract liquor containing each of hemicellulosic oligomers, lignin, and cellulose-rich solids, wherein said extracting is conducted with no added acid or with one or more added acids selected from the group consisting of sulfuric acid, sulfurous acid, sulfur dioxide, acetic acid, formic acid, or oxalic acid, and combinations thereof; (c) washing said cellulose-rich solids using an aqueous wash solution, to produce washed cellulose-rich solids and a hydrolysate; (d) separating said cellulose-rich solids from said hydrolysate; (e) mildly hydrolyzing said washed cellulose-rich solids with enzymes, thereby removing a portion of cellulose contained in said washed cellulose-rich solids, to generate intermediate solids; (f) drying said intermediate solids to produce energy-dense biomass; and (g) recovering fermentable sugars from said hydrolysate.