U.S. patent application number 10/161508 was filed with the patent office on 2003-12-04 for lignins derived from black liquor.
Invention is credited to Lightner, Gene E..
Application Number | 20030221804 10/161508 |
Document ID | / |
Family ID | 29583459 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030221804 |
Kind Code |
A1 |
Lightner, Gene E. |
December 4, 2003 |
Lignins derived from black liquor
Abstract
Depolymerized lignins contained within black liquor are
transferred to an organic solvent, soluble in organic matter and
insoluble of aqueous sodium compounds contained within the black
liquor. Upon separation of the aqueous sodium compounds from the
organic solvent, saturated with contained depolymerized lignins,
depolymerized lignins are removed from the organic solvent to
result in depolymerized lignins and a separated organic solvent
suitable for recycling. Resulting aqueous sodium compounds are
concentrated by a multiple effect evaporator to provide liquor to
digest wood chips. Whereby depolymerized lignins, substantially
free from sodium compounds, are separated from a black liquor.
Accordingly this invention modifies black liquor without employing
a lime kiln and a recovery boiler, producing a molten smelt.
Inventors: |
Lightner, Gene E.; (Federal
Way, WA) |
Correspondence
Address: |
Gene E. Lightner
706 SW 296th St.
Federal Way
WA
98023
US
|
Family ID: |
29583459 |
Appl. No.: |
10/161508 |
Filed: |
June 3, 2002 |
Current U.S.
Class: |
162/16 ; 162/72;
162/82 |
Current CPC
Class: |
C10J 3/00 20130101; C10J
2300/0973 20130101; Y02P 40/40 20151101; C10J 2300/092 20130101;
C08H 6/00 20130101; C10G 1/04 20130101; D21C 11/0007 20130101; Y02P
40/44 20151101 |
Class at
Publication: |
162/16 ; 162/82;
162/72 |
International
Class: |
D21C 011/00; D21C
011/04; D21C 003/20 |
Claims
What is claimed is:
1. A method to produce lignins substantially free from sodium
compounds, which comprises: providing a black liquor containing
depolymerized lignins, and providing an organic solvent for
extraction, and subjecting said black liquor to extraction by said
organic solvent to form an extractate of said depolymerized lignins
contained in said organic solvent and a raffinate containing sodium
hydroxide and, separating said extractate from said raffinate, and
separating said depolymerized lignins from said extractate to
provide depolymerized lignins free of said organic solvent, and
recycling the heretofore separated organic solvent for extraction
of additional black liquor, and adding an acidic solution to the
heretofore separated depolymerized lignins to form sodium salts and
lignins insoluble within the sodium salts, and separating lignins
heretofore derived from the insoluble sodium salts whereby lignins
substantially free of sodium compounds are obtained from a black
liquor.
2. The method as described in claim 1 wherein said sodium salts are
subjected to a bipolar membrane for a salt splitting operation from
said sodium salts creates sodium hydroxide and creates an acid.
3. The method as described in claim 3 wherein sodium hydroxide is
combined with said raffinate.
4. The method as described in claim 1 wherein said acidic solution
added to said extractate forms gaseous hydrogen sulfide.
5. The method as described in claim 5 wherein the gaseous hydrogen
sulfide is added to said raffinate and reacted with sodium
hydroxide contained within said raffinate to form sodium
sulfide.
6. The method as described in claim 1 wherein the acid is derived
from carbon dioxide contained in a flue gas.
7. The method as described in claim 1 wherein said raffinate is
concentrated within a multiple effect evaporator.
8. The method as described in claim 7 wherein the concentrated
raffinate contains about 40% sodium hydroxide to about 10% sodium
hydroxide.
9. The method as described in claim 7 wherein the concentrated
raffinate is substantially skimmed of tall oil.
10. The method as described in claim 1 wherein said black liquor
contains sodium sulfide.
11. The method as described in claim 1 wherein said black liquor
contains polysulfide polymers.
12. The method as described in claim 1 wherein said black liquor
contains anthroquinone.
13. The method as described in claim 1 wherein said black liquor is
supplied from kraft pulping digestion.
14. The method as described in claim 1 wherein said black liquor is
supplied from soda pulping digestion.
15. The method as described in claim 1 wherein said extraction by
said organic solvent is accomplished by counter flow of said
organic solvent.
16. The method as described in claim 1 wherein said organic solvent
is selected from the group of hydrocarbons, organic halogens and
alcohols including an individual or a combination thereof.
17. The method as described in claim 1 wherein said extractate
creates depolymerized lignins substantially devoid of organic
solvent.
18. The method as described in claim 17 wherein the extractate is
cooled to form depolymerized lignins.
19. The method as described in claim 1 wherein said extractate is
subjected to a centrifuge to obtain organic solvent for recycle,
and depolymerized lignins substantially devoid of the organic
solvent.
20. The method as described in claim 1 wherein said depolymerized
lignins are subject to gasification to produce gasification
products which function as a fuel.
Description
BACKGROUND OF THE INVENTION
[0001] Liquor containing sodium hydroxide is employed to digest
wood chips to produce a pulp and, depolymerize, disperse and
dissolve lignins from the wood to yield a black liquor containing
sodium hydroxide and depolymerized lignins. A recovery boiler is
used to recover the sodium compounds. Lignins contained in
concentrated black liquor, upon combustion, furnishes energy
contained in the lignins to provide steam.
[0002] A state of the art Kraft pulping digestion process employs
white liquor containing sodium hydroxide and sodium sulfide and
creates a black liquor. After concentration of the black liquor, by
means of a multiple-effect evaporator, the concentrated black
liquor is sent to a recovery boiler to produce steam and a molten
smelt containing sodium carbonate. The smelt of melted sodium
compounds flows to a vat where it dissolves into green liquor.
Green liquor, removed from the vat, is slaked by calcium oxide to
convert the sodium carbonate to produce sodium hydroxide. Calcium
oxide, as a result, is converted to calcium carbonate which settles
at the bottom of a white liquor classifier tank. The resulting
calcium carbonate, after substantial separation of adhering white
liquor, is transported to a lime kiln where the calcium carbonate
is converted to calcium oxide. Thus the black liquor recovery cycle
is completed. The pulping operation can be accomplished in batch
form or continuous form, for example, a Kamyr continuous digester.
Accordingly, it is believed, that only a well defined recovery
method has been developed.
[0003] Therefore, an object of this invention is to obviate many of
the limitations and disadvantages of the prior art to digest wood
chips and form a black liquor containing sodium hydroxide.
[0004] This invention relates to a method of recycling a solution
containing sodium hydroxide without using a lime kiln and a
recovery boiler producing a smelt.
[0005] A significant object of this invention is to produce lignins
significantly free of sodium compounds from a black liquor.
[0006] Another object of this invention is to utilize a
multiple-effect evaporator, previously required to concentrate
black liquor, to remove water from liquor containing sodium
hydroxide.
[0007] With the above and other objects in view, this invention
relates to the novel features and alternatives and combinations
presently described in the brief description of the invention.
PHRASEOLOGY APPLIED IN THE INVENTION.
[0008] Wood chips in the presence of white liquor, containing
sodium hydroxide at an elevated temperature, will digest wood chips
to result in cellulose pulp and depolymerize, disperse and dissolve
lignins to form black liquor. Lignins are not well structured
polymers. When a lignin polymer is fractured the term
"depolymerized lignins" is often utilized even though no definite
"lignin monomer" exists. The term "depolymerized lignin" is used
interchangeably to designate lignins. The term lignins is commonly
applied to in a black liquor containing sodium hydroxide and
depolymerized lignins. Sodium sulfide, anthraqinone and polysulfide
polymers, provide catalysts to delignify wood chips.
[0009] Black liquor, when extracted by an organic solvent to
extract depolymerized lignin from the black liquor will form an
extractate of an organic solvent of depolymerized lignin and an
insoluble raffinate. The term "extractate" establishes a function
and the ending ate, such as filtrate. Lignins are prone to self
condensation under acidic conditions. Lignins removed from the
previously formed extractate, with bound sodium compounds, and
mixed with an acidic solution will produce a sodium salt solution
divided from the lignins to produce lignins free of sodium and a
solution of sodium salts. The solution containing sodium salts is
treated in a salt splitting procedure to remove salts and form a
sodium hydroxide solution and an acidic solution. The sodium
hydroxide solution, combined with the raffinate, containing sodium
hydroxide, is evaporated to remove water to concentrate the
solution. The concentrated solution, referred to as an "active
liquor," regularly contains about 40% sodium hydroxide to about 10%
sodium hydroxide. A salt splitting operation often utilizes a
bipolar membrane to remove sodium from the salt and form a sodium
hydroxide solution. As a result sodium hydroxide is created from
the salt. Concentrated liquor thus formed is skimmed of tall oil.
Tall oil resembles a soap having chemically bound sodium. A
multiple-effect evaporator, previously required to concentrate
black liquor, is capable of being applied to remove water from the
solution containing sodium hydroxide to produce "white liquor" for
recycle.
[0010] For supplementary particulars on lignin, for example, refer
to Pulp And Paper Technology, pages 33-36. For information on tall
oil, for example, refer to Kirk-Othmer, Encyclopedia Of Chemical
Technology, Fifth Edition, Volume 23, pages 615-622. Water
splitting is described, in a bulletin provided by Aqualytics, in
which a salt solution is converted to an acid and a hydroxide.
BRIEF DESCRIPTION OF THE INVENTION
[0011] The present invention, in its broadest aspect, is a method
to yield lignins separated from a black liquor containing sodium
hydroxide. This invention defines a method to produce a lignin,
substantially free of sodium compounds, and a liquor made suitable
for reuse to depolymerize, disperse and dissolve additional
lignins. The method comprises: providing a black liquor, and an
organic solvent. The method, depicted herein, originates from a
black liquor containing lignins dispersed and dissolved in a liquor
containing sodium hydroxide. Upon subjecting black liquor to
extraction by an organic solvent, an extractate of lignins
contained within the organic solvent is formed and a raffinate
containing sodium hydroxide is also formed. Consequent to
separating the extractate, with lignins of bound sodium compounds
from the raffinate, and adding an acidic solution, such as one
derived from carbon dioxide contained in a flue gas, to the
extractate forms sodium salts and renders the lignins insoluble
within the extractate. By means of separating the lignins insoluble
within the organic solvent and separating the sodium salts
contained within the organic solvent, an organic solvent for
recycle is obtained. The organic solvent is often selected from the
group of hydrocarbons, organic halogens and alcohols including an
individual or a combination thereof. The neutralized extractate
forms a phase of a solution containing sodium salts and an
insoluble phase of lignins. Separation of the salt phase will
provide lignins substantially free of sodium salts. The salt phase
is subjected to a salt splitting technique to convert to a solution
of sodium hydroxide and an acidic solution.
[0012] Key Features of this Invention are:
[0013] Separating lignins from sodium compounds contained within a
black liquor. Extraction of a black liquor by an organic solvent
creates an extractate containing depolymerized lignins.
[0014] Producing depolymerized lignins, substantially free of
sodium, from a black liquor. Depolymerized lignins, substantially
free of sodium, is suitable to fire boilers to avoid explosions due
to the presence of sodium.
[0015] Recycle substantially all of the sodium compounds as sodium
hydroxide and sodium sulfide.
[0016] Concentrated active liquor, containing sodium hydroxide, is
subjected to recycle for employment to digest wood chips,
depolymerize, disperse and dissolve lignin from wood chips to
create black liquor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Features that are considered characteristic of this
invention are set forth in the appended claims. This invention,
however, both as to its origination and method of operations as
well as additional advantages will best be understood from the
following description when read in conjunction with the
accompanying drawings in which:
[0018] FIG. 1 is a flow sheet denoting the invention as set forth
in the appended claims.
[0019] FIG. 2 is a flow sheet denoting a method to separate tall
oil from a concentrated liquor containing sodium hydroxide
employing a multiple effect evaporator for concentration.
[0020] FIG. 3 is a flow sheet denoting a method for acidifying
lignins to form condensed lignins.
[0021] FIG. 4 is a flow sheet denoting a method of settling the
extractate to form lignins.
[0022] FIG. 5 is a flow sheet denoting a method of centrifugal
division of the extractate to form lignins.
[0023] FIG. 6 is a flow sheet denoting a method for gasification of
lignins
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] The flow diagram of FIG. 1 illustrates the preferred
embodiment of the present invention. In the diagram, rectangles
represent stages or functions of the present invention and not
necessarily separate components. Arrows indicate direction of flow
of material in the method.
[0025] Referring to FIG. 1, black liquor 10, containing
depolymerized lignins and sodium hydroxide, is conveyed to counter
flow extraction stage 12, within the extraction is achieved by
recycled organic solvent 26A to produce a raffinate 16, and an
extractate 14. Extractate 14, is conveyed to a heat exchanger 20
for exchanging heat from extractate 14 to establish heated recycled
organic solvent 26A and cooled extractate 14A to exchange heat to
cooled organic solvent 26. Cooled extractate 14A, containing
insoluble lignins is conveyed to separation of lignins stage 22 to
form cooled recycled organic solvent 26 and lignins 24. Recycled
organic solvent 26A readily dissolves depolymerized lignins from
black liquor 10 and forms extractate 14, containing depolymerized
lignins, transferred within recycled organic solvent 26A, and a
raffinate 16, previously employed as an aqueous sodium hydroxide
liquor for depolymerization of lignins. Accordingly recycled
organic solvent 26A, is utilized to extract lignins from black
liquor 10.
[0026] Separation of lignins stage 22 can be a supplied centrifuge,
settling tank or any equipment utilized to separate insoluble
lignins and form recycled organic solvent. Organic solvent 26 is
ordinarily selected from the group of hydrocarbons, organic cyclic
compounds, organic halogens and alcohols including an individual or
a combination thereof. Pulp washing, composed of weak black liquor,
is customarily combined with black liquor 10.
[0027] Referring to FIG. 2, a flow sheet is portrayed denoting a
method to concentrate a raffinate 16, conveyed to a multiple-effect
evaporator stage 18, to remove water 28, and form concentrated
raffinate 30A, containing tall oil. Concentrated raffinate 30A,
containing tall oil, is conveyed to a skimming tall oil stage 32 to
skim tall oil 34 and form concentrated raffinate 30, substantially
devoid of tall oil. Heretofore skimmed tall oil 34, can be reacted
with an acid to form crude tall oil. Concentrated raffinate 30,
regularly contains about 40% sodium hydroxide to about 10% sodium
hydroxide. Concentrated raffinate 30 is employed to depolymerize,
disperse and dissolve lignins contained within wood chips, to form
additional black liquor 10.
[0028] Referring to FIG. 3, lignins 24 is conveyed to lignins
condensation stage 36 and combined with acid 38, to transform
lignins to self condensation lignins to form condensed lignins
mixture 40 for transport to condensed lignins separation stage 42
to form condensed lignins 40B and additionally separate sodium salt
solution 40A. Lignins condensation stage 36, regularly releases
gaseous hydrogen sulfide 38A which is reacted with sodium hydroxide
to form sodium sulfide.
[0029] Referring to FIG. 4, a flow sheet is portrayed denoting a
method to transport cooled extractate 14A, containing insoluble
lignins, to a settling tank 22A, to settle and provide lignins 24
and cooled organic solvent 26. Cooled extractate 14A is generally
cooled from cooled water obtained from a cooling tower
[0030] Referring to FIG. 5, a flow sheet is portrayed denoting a
method to convey cooled extractate 14A, containing insoluble
lignins, to a centrifugal separation stage 22B, to separate and
provide lignins 24 and cooled organic solvent 26.
[0031] Referring to FIG. 6, a flow sheet is portrayed denoting a
method to convert lignins 24 by steam 48 within gasification stage
46, to produce gasification products 50 to function as a fuel.
* * * * *