Process for production of lignin, organic acids, organic chemicals, pure co2, and water from kraft black liquor with operational efficiencies

Abstract

An exemplary embodiment of the present disclosure provides a process for generating new products from a kraft mill and improving operational efficiency of a kraft mill through extraction of bioderived organic acids and liquid CO2 from weak black liquor generated during a kraft process, comprising the steps of: filtering a weak black liquor (BL) stream generated in the kraft process downstream from a brownstock washer to remove a first portion of lignin and generate a reduced lignin or de-lignified permeate and a retentate; removing the reduced lignin or de-lignified permeate from the kraft process; processing at least the de-lignified permeate to generate organic acids, liquid CO2, water, and raffinate containing salts; recovering the organic acids and liquid CO2; and returning the raffinate containing salts to the kraft process downstream of a recovery boiler.

What is claimed is: 
     
         1 . A process for obtaining new products from a kraft mill and for improving operational efficiency of a kraft mill through extraction of bioderived organic acids and liquid CO 2  from weak black liquor generated during a kraft process, comprising the steps of:
 filtering a weak black liquor (BL) stream generated in the kraft process downstream from a brownstock washer to remove a first portion of lignin and generate a reduced lignin or delignified permeate and a retentate;   removing the reduced lignin or de-lignified permeate from the kraft process;   processing at least the de-lignified permeate to generate organic acids, liquid CO 2 , water, and raffinate containing salts;   recovering the organic acids, and liquid CO 2 ; and   returning the raffinate containing salts to the kraft process downstream of a recovery boiler.   
     
     
         2 . The process of  claim 1 , further comprising the step of, allowing the retentate of the filtered weak BL stream to remain within the kraft process. 
     
     
         3 . The process of  claim 1 , wherein the processing step further comprises the steps of, passing the reduced lignin or de-lignified permeate through a gas bubbler to generate an aqueous stream and a gas stream;
 passing the aqueous stream through an adsorption column to remove a second portion of lignin from the reduced lignin permeate to generate a delignified BL stream;   passing the delignified BL stream to a crystallizer to precipitate at least a portion of salt in the delignified BL stream to generate a pretreated BL stream.   
     
     
         4 . The process of  claim 3 , wherein the processing step further comprises the steps of:
 passing the gas stream to a liquifying unit configured to liquify the gas stream to liquid CO 2  and storing the liquid CO 2 .   
     
     
         5 . The process of  claim 3 , further comprising the step of regenerating the adsorption column with an acetone-water mixture. 
     
     
         6 . The process of  claim 5 , wherein the processing step further comprises the steps of:
 removing, at least a portion of organic acids in the pretreated BL stream to generate a reduced-acid or acid-lean pretreated BL stream and converting the organic acids to one or more organic chemicals; and   passing the reduced-acid pretreated BL stream through a reverse-osmosis membrane to generate the water and the raffinate containing salts.   
     
     
         7 . A method of obtaining components from a kraft black liquor feedstock, comprising:
 passing a BL feedstock through a NF membrane to remove a first portion of lignin in the BL feedstock to generate a NF permeate;   acidifying, with an acidification unit, the NF permeate to generate an aqueous stream and an off-gas stream including CO 2 ;   filtering, with a filtration unit, the aqueous stream to remove a second portion of lignin from the aqueous stream to generate a delignified BL stream;   removing, at least a portion of organic acids in the pretreated BL stream to generate a reduced-acid pretreated BL stream and a recovered organic acid stream;   passing the reduced-acid pretreated BL stream through a membrane to generate a water permeate and a raffinate comprising salt and recovering the water permeate;   passing the raffinate comprising salt through a membrane electrolyzer to generate an acidic stream and a basic stream; and   liquifying gaseous CO 2  from within the off-gas stream into a liquified CO 2  stream and recovering the liquified CO 2  stream.   
     
     
         8 . The method of  claim 7 , wherein the membrane electrolyzer is a Bipolar Membrane Electrodialyzer (BMED). 
     
     
         9 . The method of  claim 7 , further comprising causing one or more reactions between the at least a portion of the organic acids from the recovered organic acid stream and one or more catalysts to produce organic chemicals. 
     
     
         10 . The method of  claim 9 , wherein the one or more reactions comprise one or more reactions selected from the group consisting of deoxygenation, dehydroxylation, and oligomerization. 
     
     
         11 . The method of  claim 7 , wherein the NF membrane is an alkali-stable NF membrane. 
     
     
         12 . The method of  claim 7 , wherein the first portion of lignin in the BL feedstock comprises at least 93% of lignin in the BL feedstock. 
     
     
         13 . The method of  claim 7 , wherein the filtration unit includes a filter and the aqueous stream passing though the filter has a pH of at least 11. 
     
     
         14 . The method of  claim 7 , wherein the second portion of lignin from the NF permeate comprises at least 3% of lignin in the BL feedstock. 
     
     
         15 . The method of  claim 7 , wherein passing the BL feedstock through a NF membrane further comprises, separating the NF permeate from a retentate, and wherein the BL feedstock is taken from a kraft process and the NF permeate is processed outside of the kraft process and wherein the retentate is returned to the kraft process. 
     
     
         16 . The method of  claim 7 , wherein the acidifying step includes acidifying the NF permeate with H 2 SO 4  to generate the aqueous stream and wherein the off-gas stream includes H 2 S, SO 2 , and CO 2 . 
     
     
         17 . The method of  claim 16 , further comprising scrubbing the off-gas stream with a gas scrubber, wherein scrubbing includes introducing the off-gas stream and the basic stream into the gas scrubber, and generating the gaseous CO 2  stream. 
     
     
         18 . The method of  claim 7 , wherein the removing step includes removing organic acids from the pretreated BL stream with a simulated-moving bed unit, wherein the simulated-moving bed removes at least 90% of organic acids in the pretreated BL stream. 
     
     
         19 . The method of  claim 18 , wherein the simulated-moving bed utilizes a methanol or acetone desorbent.