Patent ID: 8246750
Filing Date: 2012-08-21
Classification: C13K

Abstract:
1. A method for extracting C 5 sugars including pentose or C 6 sugars including hexose from a slurry of cellulosic material comprising cellulose, water, and optionally acid, the method comprising the steps of: feeding the slurry of cellulosic material comprising cellulose, water, and optionally acid to a first stage via an inlet at a top of a vessel; exposing the slurry in the first stage to a first temperature between 130° C. and 190° C. for a first period of time ranging between 10 minutes and 120 minutes; extracting liquid comprising pentose or hexose from the slurry in the first stage; passing the slurry to a counter-current wash stage; feeding water to the counter-current wash stage via a first recycle loop; exposing the slurry in the counter-current wash stage to a second temperature between 100° C. and 170° C. for a second period of time ranging between 30 minutes and 120 minutes; passing the material through a pass-through zone; passing the slurry to a second stage; exposing the slurry in the second stage to a third temperature between 150° C. and 190° C. for a third period of time ranging between 30 minutes and 240 minutes while lowering the pH, wherein the slurry in the second stage obtains a soup-like consistency; feeding acid or base to the second stage via a second recycle loop, wherein the second recycle loop passes through a heat exchanger; and removing the slurry from the vessel, wherein the slurry comprises lignin.