Method of treating lignocellulosic biomass to produce cellulose
AssigneePureVision Technology, Inc.
InventorRichard C. Wingerson
Life of this patent
Estimating the term…
Abstract
A multi-function process is described for the separation of cellulose fibers from the other constituents of lignocellulosic biomass such as found in trees, grasses, agricultural waste, and waste paper with application in the preparation of feedstocks for use in the manufacture of paper, plastics, ethanol, and other chemicals. This process minimizes waste disposal problems since it uses only steam, water, and oxygen at elevated temperature in the range of 180° C. to 240° C. for 1 to 10 minutes plus a small amount of chemical reagents to maintain pH in the range 8 to 13. An energy recuperation function is important to the economic viability of the process.
Claims23
A method of treating lignocellulosic biomass to produce purified cellulose containing less than 20% lignin, said method comprising the steps of:
- providing a lignocellulosic feedstock having an average constituent thickness of at most 1″;
- introducing said feedstock into a pressure vessel having at least two reaction zones;
- maintaining said feedstock in the pressure vessel for a residence time;
- heating said feedstock in a first reaction zone to a temperature of from about 180° C. to about 240° C. to dissolve hemicellulose;
- removing said dissolved hemicellulose from the heated feedstock
- transferring said heated feedstock from said first reaction zone to a second reaction zone;
- subjecting said transferring feedstock to a counterflow of hot wash water of pH of from about 8 pH to about 13 pH to create residual solids containing cellulose and a wash water containing dissolved materials;
- and
- separating the residual solids containing purified cellulose from the filtered wash water, wherein said separated cellulose contains less than 20% lignin.
The method of treating lignocellulosic biomass according to claim. 17, further comprising the steps of:
- (a) measuring temperatures and pressures in flash tanks and heat exchangers to produce temperature and pressure data;
- (b) processing temperature and pressure data to provide control signals;
- and
- (c) actuating variable nozzles controlling liquid flow into flash tanks based upon the control signals.
A method of treating lignocellulosic biomass containing lignin to produce purified cellulose, said method comprising:
- providing a lignocellulosic feedstock;
- introducing said feedstock into a pressure vessel having at least two reaction zones;
- heating said feedstock in a first reaction zone to a temperature of from about 180° C. to about 240° C;
- removing hydrolized hemicellulose from the heated feedstock;
- transferring said heated feedstock from said first reaction zone to a second reaction zone;.
- subjecting said feedstock in said second zone to a counterflow of hot wash water containing dissolved oxygen and having a pH of at least 11 to produce residual solids containing cellulose and a wash water containing lignin and other extractives;
- and
- separating the residual solids containing purified cellulose from the filtered wash water, wherein the separated cellulose contains less than 20% lignin.
Dependencies are inferred from the claim text.