U.S. patent application number 16/293678 was filed with the patent office on 2019-09-19 for method and system for producing market pulp and products thereof.
This patent application is currently assigned to Buckman Laboratories International, Inc.. The applicant listed for this patent is Buckman Laboratories International, Inc.. Invention is credited to Srinivas Hanumansetty, Philip M. Hoekstra.
Application Number | 20190284760 16/293678 |
Document ID | / |
Family ID | 65818651 |
Filed Date | 2019-09-19 |
United States Patent
Application |
20190284760 |
Kind Code |
A1 |
Hoekstra; Philip M. ; et
al. |
September 19, 2019 |
Method And System For Producing Market Pulp And Products
Thereof
Abstract
Methods and systems are provided for producing market pulp which
include treatment of pulp before pulp drying. An anionically
charged compound and enzyme are used to treat pulp before pulp
drying to improve pulp dewatering performance and efficiency in the
production of market pulp. Market pulp products containing the
treatment compounds are also described.
Inventors: |
Hoekstra; Philip M.;
(Memphis, TN) ; Hanumansetty; Srinivas; (Memphis,
TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Buckman Laboratories International, Inc. |
Memphis |
TN |
US |
|
|
Assignee: |
Buckman Laboratories International,
Inc.
Memphis
TN
|
Family ID: |
65818651 |
Appl. No.: |
16/293678 |
Filed: |
March 6, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62702395 |
Jul 24, 2018 |
|
|
|
62643224 |
Mar 15, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21H 21/24 20130101;
D21H 21/14 20130101; D21C 7/06 20130101; D21C 9/18 20130101; D21C
5/005 20130101; D21H 17/005 20130101; D21F 1/66 20130101; D21H
17/42 20130101; D21C 9/10 20130101; D21H 17/09 20130101 |
International
Class: |
D21C 5/00 20060101
D21C005/00; D21C 9/18 20060101 D21C009/18; D21C 9/10 20060101
D21C009/10; D21H 21/14 20060101 D21H021/14; D21H 17/09 20060101
D21H017/09; D21C 7/06 20060101 D21C007/06; D21F 1/66 20060101
D21F001/66 |
Claims
1. A method for producing market pulp, comprising: forming
cellulosic particulates into pulp; adding at least one anionically
charged compound and at least one enzyme to said pulp to provide
treated pulp; mechanically dewatering said treated pulp to provide
mechanically dewatered pulp; and thermally drying said mechanically
dewatered pulp to form market pulp.
2. The method of claim 1, wherein at least part of said adding of
said enzyme to said pulp occurs prior to said adding of said
anionically charged compound to said pulp.
3. The method of claim 1, wherein about 80% to 100% by weight of
said adding of said enzyme to said pulp occurs prior to said adding
of said anionically charged compound to said pulp.
4. The method of claim 1, wherein the anionically charged compound
is an organic anionically charged compound.
5. The method of claim 1, wherein the enzyme is a hydrolytic
enzyme.
6. The method of claim 1, further comprising bleaching the pulp
after the pulp forming and before the adding of the anionically
charged compound and enzyme to said pulp.
7. A method for producing market pulp, comprising: forming
cellulosic particulates into pulp; adding at least one anionic
surfactant and at least one enzyme to said pulp to provide treated
pulp; mechanically dewatering said treated pulp to provide
mechanically dewatered pulp; and thermally drying said mechanically
dewatered pulp to form market pulp.
8. The method of claim 7, wherein at least part of said adding of
said enzyme to said pulp occurs prior to said adding of said
anionic surfactant to said pulp.
9. The method of claim 7, wherein about 80% to 100% by weight of
said adding of said enzyme to said pulp occurs prior to said adding
of said anionic surfactant to said pulp.
10. The method of claim 7, further comprising bleaching the pulp
after the pulp forming and before the adding of the anionic
surfactant and enzyme to said pulp.
11. The method of claim 7, wherein the anionic surfactant is a
sulfate surfactant, a sulfonate surfactant, a sulfosuccinate
surfactant, or any combinations thereof.
12. The method of claim 7, wherein the anionic surfactant is an
alcohol sulfate, an alcohol alkoxy sulfate, a sulfonate, a dialkyl
sulfosuccinate, an sulfosuccinic acid ester with an ethoxylated
alcohol, or a soluble or dispersible salt thereof, or any
combinations thereof.
13. The method of claim 7, wherein the enzyme is cellulase,
hemicellulase, pectinase, cellobiase, xylanase, mannanase,
.beta.-glucanase, carboxymethylcellulase, amylase, glucosidase,
galactosidase, laccase, or any combinations thereof.
14. The method of claim 7, wherein said forming provides kraft
pulp, sulfite pulp, fluff pulp, dissolving pulp, bleached
chemothermomechanical pulp, or any combinations thereof.
15. The method of claim 7, further comprising bleaching the pulp
after the pulp forming and before the adding of the anionic
surfactant and enzyme to said pulp.
16. The method of claim 7, wherein said mechanically dewatering
comprises screening and pressing of the pulp, wherein drained white
water from said screening is combined with fresh pulp and pumped
with a fan pump to a head box for the screening, wherein said
enzyme is fed into the combined fresh pulp and white water before
entering the fan pump, and said anionic surfactant is fed into said
combined fresh pulp and white water after exiting said fan pump and
before reaching the headbox.
17. The method of claim 7, wherein the anionic surfactant and
enzyme are added to the pulp in a ratio of from about 10,000:1 to
about 1:10.
18. The method of claim 7, wherein the anionic surfactant is added
to the pulp in an amount of from about 0.1 lb./ton dry fiber to
about 10 lb./ton dry fiber, and the enzyme is added to the pulp in
an amount of from about 0.001 lb./ton dry fiber to about 2 lb./ton
dry fiber.
19. The method of claim 7, further comprising unitizing said market
pulp to form unitized market pulp.
20. The method of claim 7, wherein the cellulosic particulates are
hardwood chips, softwood chips, recycled paper fiber, or any
combinations thereof.
21. The method of claim 7, wherein the combination of treating the
pulp with the at least one anionic surfactant and at least one
enzyme before dewatering in the production of market pulp is
effective to provide at least one of the following: (i) increased
pulp free drainage (g/90 sec) to a value which is at least 7.5%
times greater than free drainage value obtained without any
treatment in the pulp; (ii) increased pulp free drainage to a value
which is at least about 3% greater than free drainage value
obtained with using the anionic surfactant individually in the pulp
(without the enzyme); (iii) increased pulp free drainage to a value
which is at least about 10% greater than a free drainage value
calculated as a sum of the free drainage increases obtained from
using the anionic surfactant and enzyme separately and individually
in the pulp; and (iv) reducing pulp water retention value (WRV) to
a value which is at least about 10% less than WRV obtained with
using the anionic surfactant individually in the pulp (without the
enzyme).
22. The method of claim 7, wherein the treating is effective for
increasing obtained free drainage to a value which is at least five
times greater than free drainage value obtained without any
treatment of the pulp.
23. The method of claim 7, wherein the treating is effective for
increasing obtained free drainage to a value which is from about
60% to about 200% greater than free drainage value obtained with
using the anionic surfactant individually in the pulp.
24. A market pulp made by the method of claim 1 containing said
anionically charged compound and said enzyme.
25. A market pulp made by the method of claim 7 containing said
anionic surfactant and said enzyme.
26. A system for producing market pulp comprising: a supply of
cellulosic particulates; at least one pulp forming unit for forming
pulp from said cellulosic particulates; at least one feeding device
for feeding at least one anionically charged compound to said pulp;
at least one feeding device for feeding at least one enzyme to said
pulp to provide treated pulp after addition of both the anionically
charged compound and the enzyme; a mechanical dewatering device for
mechanically removing water from said treated pulp to provide
mechanically dewatered pulp; and a thermal drying device for
thermally removing water from said mechanically dewatered pulp to
provide market pulp.
27. The system of claim 26, wherein said at least one feeding
device for feeding anionically charged compound feeds anionic
surfactant and said at least one feeding device for feeding enzyme
feeds hydrolytic enzyme.
28. The system of claim 26, wherein said pulp forming unit is a
digester capable of receiving at least one chemical for digesting
the cellulosic particulates.
29. The system of claim 26, wherein said mechanical dewatering
device comprises screen and press sections, wherein drained white
water from the screen section is combinable with fresh pulp and
pumpable with a fan pump to a head box of the mechanical dewatering
device, wherein said at least one feeding device for said enzyme is
capable of feeding said enzyme into the combined fresh pulp and
white water before entering said fan pump, and said at least one
feeding device for said anionically charged compound is capable of
feeding said anionically charged compound into said combined fresh
pulp and white water after exiting said fan pump and before
reaching the headbox.
30. The system of claim 26, further comprising a bleaching unit for
bleaching the pulp after the pulp forming unit and before the
adding of the anionically charged compound and enzyme to said pulp
with said feeding devices.
31. The system of claim 26, wherein the first and second feeding
devices being capable of introducing respective first and second
amounts of the anionically charged compound and enzyme to pulp
drawn from the pulp forming unit to provide at least one of the
following: (i) increased pulp free drainage (g/90 sec) to a value
which is at least 7.5% times greater than free drainage value
obtained without any treatment in the pulp; (ii) increased pulp
free drainage to a value which is at least about 3% greater than
free drainage value obtained with using the anionically charged
compound individually in the pulp (without the enzyme); (iii)
increased pulp free drainage to a value which is at least about 10%
greater than a free drainage value calculated as a sum of the free
drainage increases obtained from using the anionically charged
compound and enzyme separately and individually in the pulp; and
(iv) reducing pulp water retention value (WRV) to a value which is
at least about 10% less than WRV obtained with using the
anionically charged compound individually in the pulp (without the
enzyme).
Description
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(e) of prior U.S. Provisional Patent Application Nos.
62/643,224, filed Mar. 15, 2018, and 62/702,395, filed Jul. 24,
2018, which are incorporated in their entireties by reference
herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to the production of market
pulp. More particularly, methods and systems are provided for
producing market pulp which include treatment of pulp with one or
more anionic surfactants or compounds and one or more enzymes
before pulp drying.
[0003] In the pulp making industry, cellulose-containing feed
material has been defibrated chemically, mechanically, or both, and
then typically is washed and at least partly dewatered after such
operations. In pulping processes in which the pulp is chemically
treated, such as by chemical digestion, bleaching, or other
chemical treatments, dewatering can be used to drain water and
separate free chemical from the fibers. Some pulp mills may be
integrated with a paper making plant, wherein the dewatering of the
product pulp may be limited such that slurry pulp or wet laid pulp
can be directly advanced to a papermaking machine at the same
production site. Other pulp mills produce market pulp in
non-integrated production operations. Market pulp can be pulp
product which has been significantly dewatered in the final stages
of pulp processing. Market pulp further may be formed into bales or
rolls of dewatered pulp. The market pulp can be transported to
other locations for later use.
[0004] A particular process for producing market pulp which uses
diverse ionic compounds before pulp drying is described in U.S.
Pat. No. 8,916,024. According to the process of U.S. Pat. No.
8,916,024, pulp is treated with a combination of cationically and
anionically charged compounds before drying, and more particularly,
the treatment involves treating pulp with a combination of at least
one cationic polymer and at least one anionic polymer effective to
form a polyelectrolyte complex in the treated pulp. U.S. Pat. No.
6,706,144 shows a method of dewatering of dewatering an aqueous
cellulosic pulp slurry, which may be a market pulp slurry, wherein
a mixture of one or more nonionic surfactants and one or more
anionic surfactants is added to the slurry.
[0005] The present investigators have realized that the rate at
which pulp dewatering can be accomplished in a pulp mill in the
production of market pulp can significantly affect the overall line
speed and production capacity of the pulp mill or similar
production facility. The present investigators have realized that
there is a need for new methods and systems for producing market
pulp with enhanced pulp-dewatering performance and
efficiencies.
SUMMARY OF THE PRESENT INVENTION
[0006] A feature of the present invention is to provide a method
for producing market pulp with treatment of pulp with one or more
anionically charged compounds and with one or more enzymes to
improve one or more properties of the market pulp or process to
produce the market pulp, such as, improving dewatering performance
and efficiency.
[0007] Another feature of the present invention is to provide a
method for producing market pulp by sequentially adding anionic
surfactant(s) and one or more enzymes to pulp before dewatering to
improve pulp drainage.
[0008] An additional feature of the present invention is to provide
a system for producing market pulp capable of using one or more
anionically charged compounds and one or more enzymes before pulp
drying to improve pulp drainage.
[0009] A further feature of the present invention is to provide a
market pulp comprising dewatered pulp which contains one or more
anionically charged compounds and one or more enzymes from the pulp
treatment method.
[0010] Additional features and advantages of the present invention
will be set forth in part in the description that follows, and in
part will be apparent from the description, or may be learned by
practice of the present invention. The objectives and other
advantages of the present invention will be realized and attained
by means of the elements and combinations particularly pointed out
in the description and appended claims.
[0011] To achieve these and other advantages, and in accordance
with the purposes of the present invention, as embodied and broadly
described herein, the present invention relates, in one embodiment,
to a method for producing market pulp comprising forming cellulosic
particulates into pulp; adding at least one anionically charged
compound and adding at least one enzyme to the pulp to provide
treated pulp; mechanically dewatering the treated pulp to provide
mechanically dewatered pulp; and thermally drying the mechanically
dewatered pulp to form market pulp.
[0012] The present invention further relates to a method for
producing market pulp comprising forming cellulosic particulates
into pulp; adding at least one anionic surfactant and adding at
least one enzyme to the pulp before dewatering; mechanically
dewatering the pulp; and thermally drying the dewatered pulp to
form market pulp.
[0013] The present invention further relates to a system for
producing market pulp comprising a supply of cellulosic fibers; at
least one pulp forming unit for forming pulp from the cellulosic
fibers; at least one feeding device for feeding at least one
anionically charged compound, such as an anionic surfactant, to the
pulp; at least one feeding device for feeding at least one enzyme
to the pulp; a dewatering device for mechanically removing water
from the pulp; and a dryer for thermally removing water from the
pulp to provide market pulp.
[0014] The present invention further relates to a market pulp
comprising dewatered pulp which contains at least one anionically
charged compound and at least one enzyme from the indicated
treatment method.
[0015] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are intended to provide a further
explanation of the present invention, as claimed.
[0016] The accompanying drawings, which are incorporated in and
constitute a part of this application, illustrate some of the
embodiments of the present invention and together with the
description, serve to explain the principles of the present
invention.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a process flow chart for producing market pulp
according to an example of the present application.
[0018] FIG. 2 is a schematic showing a portion of the system in
FIG. 1 which includes a pulp dryer for bleached pulp according to
an example of the present application.
[0019] FIG. 3 is a schematic of a pulp dryer which can be used in
the system shown in FIG. 1 according to an example of the present
application.
[0020] FIG. 4 is a graph showing the amount of water removed (in
grams) from wet pulp over time for several examples, including an
example of the present invention.
[0021] FIG. 5 is a bar graph showing the volume of water drained
(in ml) from wet pulp for three drain times for several examples,
including an example of the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0022] The present invention relates to production of market pulp
which has been treated with one or more anionically charged
compounds and with one or more enzymes to improve pulp dewatering
performance and efficiency thereof and/or other properties. As used
herein, "market pulp" refers to mechanically dewatered pulps which
are thermally dried. The market pulp provides a dry form of product
material which has useful storage stability and can be more easily
shipped and handled than bulkier aqueous forms of pulp product. The
market pulp can be stored, transported, or both for subsequent use
as a process material used in other production processes. The
market pulp optionally can be securely wrapped as a unitized
product for shipping or transport for further processing, such as
papermaking. As an option, market pulp, as referenced herein, can
be a product of a modified type of pulp mill which is adapted
according to options of the present invention for treatment of the
pulp after any bleaching and before final dewatering with the
anionically charged compound(s) and one or more enzymes.
[0023] These treatment additives impact the dewatering performance
in significant and beneficial ways which would not be expected from
the use of either the anionically charged compound and enzyme
individually, and in some options may exceed additive expected
effects from the individual component. The combined treatment of
pulp with the anionically charged compound and enzyme can provide a
synergistic effect on water removal which is much better than
either treatment alone and much better than the additive effect
expected. It has been observed that the high basis weight of some
pulp sheets on a pulp dryer, for example, can be an impediment to
good drainage. It has been found that significant improvements in
dewatering performance at a pulp dryer can be provided in the
production of market pulp by treatment of pulps after digestion or
other mode of defibration, and any bleaching, and before pulp
drying, with the anionically charged compound and enzyme used in
combined treatment of pulps. Treatment of the pulp prior to the
pulp dryer with the combination of the anionically charged compound
and with the enzyme(s), for example, can increase the free drainage
rate of the pulp. Increasing the free drainage rate of the pulp
makes it feasible to increase the production speed and capacity of
the process for producing market pulp. As an option, the pulp
treatment methods and systems of the present invention are not part
of, nor integrated with, a paper making machine.
[0024] Though not desiring to be bound to any theory, enzymes may
provide other mechanisms to improve water removal from the pulp in
the methods and systems of the present invention. The surface of
the fiber is hydrophilic, and so there is a portion of the water in
the slurry that is tightly bound to the fiber surface, and not
easily removed by gravity drainage, nor by applied vacuum, nor by
pressing. A cellulase enzyme, for example, may remove the amount of
tightly-bound water by removing some portion of fibrils from the
fiber surface, thus reducing the effective surface area that can
bind water. The fiber surface also is comprised of hemicelluloses,
in addition to cellulose. These hemicellulose compounds are
especially likely to bind water to the fiber surface. Use of a
hemicellulase enzyme may remove a portion of hemicellulose (xylan
or mannan, for example) from the fiber surface, and thus also
reduce the affinity of water to the fiber.
[0025] The anionically charged compound(s) can be one or more
anionic compounds and/or can be one or more anionic surfactants.
Examples include, but are not limited to, an alcohol sulfate, an
alcohol alkoxy sulfate, a sulfonate, a sulfosuccinate, a
sulfosuccinic acid ester with an ethoxylated alcohol, and any
soluble or dispersible salts thereof, or any combinations thereof.
A sulfonate refers to a salt or ester of a sulfonic acid. A
sulfosuccinate refers to a sulfonate derivative of succinate (e.g.,
a salt or ester of sulfosuccinic acid). For salts thereof, the
counterion can be a metal ion, such as an alkali metal (e.g.,
sodium, potassium). More specific examples include, but are not
limited to, a fatty alcohol sulfate (e.g., C12-18 fatty alcohol
sulfate), an alkyl alcohol sulfate (e.g., C10-C16 alkyl alcohol
sulfate), an ethoxylated alcohol sulfate (e.g., ethoxylated C4-C12
alcohol sulfate), a sulfonated fatty acid alkyl ester, an olefin
sulfonate, a paraffin sulfonate, an alkylbenzylsulfonate, and a
dialkyl sulfosuccinate. Additional examples include dodecyl alcohol
sulfate, hexadecyl alcohol sulfate, dodecyl ethoxy sulfate,
tetradecyl ethoxy sulfate, decylbenzene sulfonate, tetradecyl
benzene sulfonate, tetradecyl sulfonate, octadecyl sulfonate,
3-hydroxy-1-hexadecane sulfonate, 2-hexadecene-1-sulfonate,
dioctylsulfosuccinate sodium salt, or others. The anionically
charged compound can be an anionic surfactant, which is a sulfate
surfactant, a sulfonate surfactant, a sulfosuccinate surfactant, or
any combinations thereof.
[0026] The enzyme component of the enzyme used with the anionically
charged compound(s) to treat the pulp according to this invention
can include, for example, an enzyme having cellulolytic activity,
hemi-cellulolytic activity, pectinolytic activity, or glycosidasic
activity. The enzyme can be a hydrolytic enzyme which has activity
that affects the hydrolysis of fiber (e.g., hydrolytic activity),
such as to accelerate the hydrolysis of a chemical bond. The enzyme
can be, for example, cellulase, hemicellulase, lipase, pectinase,
cellobiase, xylanase, protease, mannanase, .beta.-glucanase,
carboxymethylcellulase (CMCase), amylase, glucosidase,
galactosidase, laccase, or any combinations thereof. A single type
of enzyme or a combination of two or more different types of
enzymes can be used jointly with the anionically charged
compound(s).
[0027] Cellulases generally are enzymes that degrade cellulose, a
linear glucose polymer occurring in the cell walls of plants. The
cellulase enzyme can be, for example, a cellulase, such as an
endo-cellulase, exo-cellulase, cellobiase, oxidative cellulase,
cellulose phosphorylases, or any combinations thereof.
Hemicellulases (e.g., xylanase, arabinase mannanase) generally are
involved in the hydrolysis of hemicellulose, which, like cellulose,
is a polysaccharide found in plants. The pectinases generally are
enzymes involved in the degradation of pectin, a carbohydrate whose
main component is a sugar acid. .beta.-glucanases are enzymes
involved in the hydrolysis of .beta.-glucans which are also similar
to cellulose in that they are linear polymers of glucose.
[0028] The following paragraphs provide examples of enzymes that
can be used alone or in any combination in the present
invention.
[0029] Endo-cellulases that can be used, for example, are
endoglucanase with binding domain (e.g., NOVOZYM.RTM. 476,
Novozymes), endoglucanase enriched with high cellulase units (e.g.,
NOVOZYM.RTM. 51081, Novozymes), or combinations thereof, or other
known or useful endo-cellulases.
[0030] Liquid enzymatic compositions containing cellulases are
available under the names Celluclast.RTM. and Novozym.RTM. 188,
which are both supplied by Novo Nordisk.
[0031] PULPZYM.RTM. product, available from Novo Nordisk, and
ECOPULP.RTM. product, from Alko Biotechnology, are two examples of
commercially available liquid enzymatic compositions containing
xylanase-based bleaching enzymes.
[0032] As a class, hemicellulases can include hemicellulase mixture
and galactomannanase. Commercial liquid enzymatic compositions
containing hemicellulases are available as PULPZYM.RTM. from Novo,
ECOPULP.RTM. from Alko Biotechnology and Novozym.RTM. 280 and
Gamanase.TM., which are both products of Novo Nordisk. The
mannanases can be, for example, endo-mannanases, such as
endo-.beta.-mannanase. Mannanase preparations, for example, are
commercially available, including types which may be manufactured
with the aid of genetically modified microorganisms (e.g.,
Bacillus- and Trichoderma-types).
[0033] Pectinases comprise endopolygalacturonase,
exopolygalacturonase, endopectate lyase (transeliminase),
exopectate lyase (transeliminase), and endopectin lyase
(transeliminase). Commercial liquid enzymatic compositions
containing pectinases are available under the names Pectinex.TM.
Ultra SP and Pectinex.TM.*, both supplied by Novo Nordisk.
[0034] .beta.-glucanases are comprised of lichenase, laminarinase,
and exoglucanase. Commercial liquid enzymatic compositions
containing .beta.-glucanases are available under the names
Novozym.RTM. 234, Cereflo.RTM., BAN, Finizym.RTM., and
Ceremix.RTM., all of which are supplied by Novo Nordisk.
[0035] The enzymes can be commercially obtained in ready-to-use
preparations, from suppliers such as indicated herein or other
suppliers. The enzymes can be a dry powder or granulate, a
non-dusting granulate, a liquid, a stabilized liquid, or a
stabilized protected enzyme, or other forms suitable for addition
to a fiber slurry or similar fiber-containing material. Liquid
enzyme preparations may, for instance, be stabilized by adding
stabilizers such as a sugar, a sugar alcohol or another polyol,
and/or lactic acid or another organic acid according to established
processes. Dry powder forms may be lyophilized and include
substrates.
[0036] The enzyme and anionically charged compound(s) components
can be premixed into a common composition used to treat a pulp, or
they can be separately added. If premixed, an enzyme preformulated
in a liquid composition can be used as the source of the enzyme
combined with the anionically charged compound(s) component. A
cellulolytic enzyme composition can contain, for example, from
about 5% by weight to about 20% by weight enzyme. These enzyme
compositions can further contain, for example, polyethylene glycol,
hexylene glycol, polyvinylpyrrolidone, tetrahydrofuryl alcohol,
glycerine, and/or water, and/or other conventional enzyme
composition additives, as for example, described in U.S. Pat. No.
5,356,800, which is incorporated herein in its entirety by
reference. If enzyme substrates are present with dry powder forms
of the enzymes, the substrates should not adversely interact with
or interfere with the pulp treatment or other papermaking
processes.
[0037] Other suitable enzymes and enzyme-containing compositions
include those such as described in U.S. Pat. Nos. 5,356,800,
4,923,565, and International Patent Application Publication No. WO
99/43780, all incorporated herein in their entireties by reference.
Other exemplary paper making pulp-treating enzymes are BUZYME.RTM.
2523 and BUZYME.RTM. 2524, both available from Buckman Laboratories
International, Inc., Memphis, Tenn.
[0038] The enzyme can be added in an amount, for example, of from
about 0.0001% by weight to about 5% by weight enzyme based on the
dry weight of the pulp, or from about 0.0005% by weight to about
4.5% by weight, or from about 0.001% to about 4% by weight, or from
about 0.005% to about 3.5% by weight, or from about 0.01% to about
3% by weight, or from about 0.05% by weight to about 2.75% by
weight, or from about 0.1% by weight to about 2.5% by weight, or
from about 0.2% by weight to about 1.5% by weight, or from about
0.001% to about 0.1% by weight, or from about 0.005% to about 0.5%
by weight enzyme based on dry weight of the pulp, though other
amounts can be used. These addition amounts of the enzyme relative
to pulp can apply to use of pre-mixtures of the enzyme and
anionically charged compound(s) in a common composition, and also
the other addition options indicated herein for introducing the
enzyme and anionically charged compound(s) separately to pulp
(simultaneously or sequentially). Any amount, percentage, or
proportion of enzyme described herein can be on an active enzyme
basis. For example, an enzyme amount referred to as 1% by weight
enzyme can refer to 1% by weight active enzyme.
[0039] The combination of treating the pulp with at least one
anionically charged compound and at least one enzyme before
dewatering beneficially influences the drainage and dewatering
behavior of the treated pulps. The at least one anionically charged
compound and at least one enzyme, for example, can be added to pulp
sequentially by separate additions thereof at different process
locations or at different times at the same process location, or
they can be added concurrently at least in part at the same process
location (e.g., as separate feeds or as a pre-mixture). As an
option, market pulp can be produced by sequentially adding at least
about 80% up to 100% by weight of the total added amount of the
anionically charged compound after addition of the at least one
enzyme to the pulp before dewatering the pulp. In such an option,
the enzyme is given the opportunity to interact first with the pulp
fibers before interactions are made with the anionically charged
compound. The addition of the at least one anionically charged
compound and at least one enzyme in this sequence can magnify the
enhancements in dewatering performance that can be achieved. As
another option, at least a portion or all of the anionically
charged compound can be added to the pulp before the enzyme is
added to the pulp. With the present invention, compared to pulp
drainage seen without the addition of any anionically charged
compound or enzyme, or using just the anionically charged compound
alone or using the enzyme alone, to the pulp, pulp drainage
performance in the production of market pulp can be significantly
increased, such as by a factor of one, two, or three or more with
processes of the present invention. Further, as compared to use of
only an anionically charged compound alone or the use of an enzyme
alone, to treat the pulp, drainage efficiencies can be
significantly increased, such as by about 60% to about 200%, or
other increases, by the combined addition of at least one
anionically charged compound and at least one enzyme to the pulp.
In addition, drainage rates can be achieved that exceed the sum of
the individual drainage rates obtained from use of the anionically
charged compound alone or the enzyme individually to treat a pulp.
Better drainage in the wire section of the pulp dryer can lead to
reduced moisture of pulp in the press section, and as a result,
steam consumption in the drying section can be significantly
reduced, which can provide energy savings. Further, improvements of
pulp dewatering provided by treatment of digested pulp with the
present invention prior to pulp drying can allow for faster pulp
throughout rates or speeds in the pulp mill, whereby the
productivity of the pulp mill can be increased. A suitable amount
of pulp dewatering may be provided at a reduced total polymer
addition rate as compared to what may be predicted as needed if
using an anionically charged compound alone. Free drainage
properties of the pulps treated with the present invention before
pulp drying can demonstrate good correlations with water retention
properties, such as in terms of water retention values or WRV, of
the treated pulps, which indicates that the treatment can yield
reliable nonrandomized results.
[0040] As an option, the combination of treating the pulp with at
least one anionically charged compound and at least one enzyme
before dewatering in the production of market pulp is effective to
provide at least one of the following:
[0041] (i) increased pulp free drainage (g/90 sec) to a value which
is at least 7.5% greater, or at least 10% greater, or at least 15%
greater, or at least 25% greater, or at least 50% greater, or at
least 75% greater, or at least 100% (one time) greater, or at least
200% (two times) greater, or at least 300% (three times) greater,
or at least 400% (four times) greater, or at least 500% (five
times) greater, than free drainage value obtained without any
treatment in the pulp;
[0042] (ii) increased pulp free drainage to a value which is at
least about 3%, or at least about 10%, or at least about 30%, or at
least about 40%, or at least about 50%, or at least about 60%, or
at least about 75%, or at least about 100% greater than free
drainage value obtained with using the anionically charged compound
(e.g., an anionic surfactant) individually in the pulp (without the
enzyme);
[0043] (iii) increased pulp free drainage to a value which is at
least about 10% greater, or at least about 15% greater, or at least
about 20% greater, or at least about 25% greater, or at least about
30% greater, or at least about 40% greater, or least about 50%
greater, or at least about 60% greater, than a free drainage value
calculated as a sum of the free drainage increases obtained from
using the anionically charged compound (e.g., an anionic
surfactant) and enzyme separately and individually in the pulp;
and
[0044] (iv) reducing pulp water retention value (WRV) to a value
which is at least about 10% less, or at least 15% less, or at least
about 20% less, or at least about 25% less than WRV obtained with
using the anionically charged compound (e.g., an anionic
surfactant) individually in the pulp (without the enzyme). In
calculating the percentage values for (i), (ii), (iii), and (iv),
the denominator values of the fractions are based on the values for
the pulps treated with only one or none of the anionically charged
compound or enzyme, and the numerator values are the absolute
values of the difference between the property value for the dual
treated anionically charged compound/enzyme treated pulp and the
pulp treated with only one or none of the anionically charged
compound/enzyme. Water removal measurements for (i), (ii), (iii),
and (iv) can be obtained using a Mutek DFR-05 drainage/retention
tester. The Mutek DFR-05 drainage freeness retention simulates the
retention and drainage conditions prevailing in a pulp or paper
machine.
[0045] These and/or other effects of the present invention can be
provided by treatment of the pulp with the one or more anionically
charged compounds and one or more enzymes without the need for
co-addition or the co-presence in the pulp under treatment of any
nonionic or cationically charged compounds, such as a nonionic
surfactant, a cationic surfactant, a cationic polymer, or a
cationic flocculant. As an option, a pulp slurry undergoing
treatment with the anionically charged compound and enzyme can be
free or essentially free of nonionic surfactant and/or cationically
charged compounds, since the beneficial effects obtained by the
present invention do not rely on the co-presence of such nonionic
surfactant or cationically charged compounds. With regard to added
nonionic surfactants, as an option, the pulp can be treated with
less than 0.1 kg/metric ton dry fiber, or less than 0.05 kg/metric
ton dry fiber, or less than 0.01 kg/metric ton dry fiber, or less
than 0.001 kg/metric ton dry fiber, or less than 0.0001 kg/metric
ton dry fiber or in the absence of nonionic surfactant, based on
total nonionic surfactants. With regard to added cationically
charged compounds, as an option, the pulp can be treated with less
than 0.1 kg/metric ton dry fiber, or less than 0.05 kg/metric ton
dry fiber, or less than 0.01 kg/metric ton dry fiber, or less than
0.001 kg/metric ton dry fiber, or less than 0.0001 kg/metric ton
dry fiber or in the absence of cationically charged compounds
(e.g., cationic surfactant(s), cationic polymer(s)), cationic
flocculant(s), and the like), based on total cationically charged
compounds.
[0046] The methods of the present invention can be used to improve
dewatering of pulpable materials, including cellulosic pulpable
materials, noncellulosic pulpable materials, recycled paper waste
pulpable materials, or any combinations thereof. As an option, the
cellulosic pulpable materials can be lignocellulosic. The drainage
and dewatering improvements due to the pulp treatment according to
methods and systems of the present invention is not limited to
treating any particular type of pulp and can find application in
all grades of pulp. The treatable pulps can be chemical pulps,
mechanical pulps, or combinations of these types of pulps. As an
option, the treatable pulp is a chemical pulp at least in part. The
treatable pulp can be bleached or unbleached when treated. The
treatable pulp can include, for example, Kraft pulp, dissolving
pulp, fluff pulp, semichemical pulps (e.g., bleached
chemothermomechanical pulp or BCTMP), sulfite pulp, soda pulp,
organosols pulp, polysulfide pulp, or other pulps, and any
combinations thereof. Nonchemical mechanical pulps, such as pulps
mechanically defibrated only, such as by use of disk or conical
refiners only for defibration of feedstock, also can be processed
with the indicated pulp treatment.
[0047] As used herein, "dried pulp" refers to laid, stacked, piled
or otherwise physically accumulated pulp which is sufficiently
dewatered to be exposed to air and unsuspended and non-immersed in
aqueous medium.
[0048] "Anionically charged compound" refers to a compound having a
net negative charge on the molecule in aqueous solution. The
anionically charged compound can be organic or inorganic. "Organic"
means the compound contains at least one C--H bond.
[0049] "Enzyme" refers to a protein that is capable of catalyzing a
chemical reaction.
[0050] "Surfactant" refers to an organic compound which can lower
the surface tension of a liquid, the interfacial tension between
two liquids, or that between a liquid and a solid.
[0051] "Anionic surfactant" refers to a surfactant having a net
negative charge on the molecule in aqueous solution. Accordingly,
the anionic surfactant can have only anionic moieties as the
charged groups thereon or may be amphoteric with a net anionic
charge for the overall molecule.
[0052] "Nonionic compound" refers to a compound that is amphiphilic
and has no charge group at either terminal end group thereof.
[0053] "Nonionic surfactant" refers to a surfactant that is
amphiphilic and has no charge group at either terminal end group
thereof.
[0054] "Cationically charged compound" refers to a compound having
a net positive charge on the molecule in aqueous solution. The
cationically charged compound can be organic or inorganic.
[0055] "Cationic surfactant" refers to a surfactant having a net
positive charge on the molecule in aqueous solution. Accordingly,
the cationic surfactant can have only cationic moieties as the
charged groups thereon or may be amphoteric with a net cationic
charge for the overall molecule.
[0056] "Cationic polymer" refers to a polymer having a net positive
charge on the molecule in aqueous solution. Accordingly, the
cationic polymer can have only cationic moieties as the charged
groups thereon or may be amphoteric with a net cationic charge for
the overall molecule.
[0057] "Kraft pulp" refers to chemical wood pulp produced by
digesting wood by the sulfate process.
[0058] "Fluff pulp" refers to a chemical, mechanical or combination
of chemical/mechanical pulp, usually bleached, used as an absorbent
medium in disposable diapers, bed pads, and other hygienic personal
products. Fluff pulp is also known as "fluffing" or "comminution"
pulp.
[0059] "Dissolving pulp" refers to a higher purity, special grade
pulp made for processing into cellulose derivatives including rayon
and acetate.
[0060] "Bleached chemothermomechanical pulp" or "BCTMP" refers to
bleached CTMP. "CTMP" refers to chemical-mechanical pulp produced
by treating wood chips with chemicals (e.g., sodium sulfite) and
steam before mechanical defibration.
[0061] "Unitize" refers to a process by which a plurality of market
fibers can be bundled or packaged together as a single unitary
product for handling.
[0062] "Defibration" refers to separation of wood fibers by
mechanical means, chemical means, or combinations of both.
[0063] Referring first to FIG. 1, wood chips, or other comminuted
cellulosic or noncellulosic fibrous material, are fed by line 10 to
a continuous digester 12 or one or several batch digesters wherein
the pulp is subjected to the pulping action of pulping liquor fed
thereto by line 14. This option can be described, for example, with
particular reference to a kraft process applied to virgin
lignocellulosic fibrous material, wherein digested and optionally
bleached pulp is treated with an anionically charged compound or
surfactant and enzyme before the kraft pulp is dried and unitized.
It will be understood that the invention also is applicable to
other pulping procedures with appropriate modification to take into
account the treatment of the pulp with anionically charged compound
or surfactant and enzyme before the pulp is dried. As an option, in
the haft process, the active pulping chemicals can be sodium
hydroxide and sodium sulfide, which is also known as white liquor,
and these chemicals can be contained in the pulping liquor fed by
line 14. The digester can operate in batch or continuous manner.
There are generally known variations of the cooking processes both
for the batch and the continuous digesters which can be applied. In
a continuous digester, for example, the wood chips or other
particulated feedstock materials can be fed at a rate which allows
the pulping reaction to be complete by the time the materials exit
the reactor. As an option, delignification may require, for
example, cooking at several hours, such as at about 100.degree. C.
to about 200.degree. C. (266.degree. F. to 356.degree. F.), or
other temperature and cooking time conditions suitable for the
feedstock and digestion chemicals used for digestion. Typically,
the finished cooked wood chips are blown by reducing the pressure
to atmospheric pressure. This releases steam and volatiles. As an
option, after the digestion, the resulting cooked wood pulp
containing residual spent pulping liquor can pass by line 16 to a
brown stock washing zone 18. The washing zone 18 can be used for
washing the digested chips free from entrained spent pulping liquor
and screening out unwanted material. Screening of the pulp after
pulping can be a process whereby the pulp is separated from large
shives, knots, dirt and other debris. The "accept" is the pulp
which can be further processed according to the present invention,
and the material separated from the pulp is "reject." The brown
stock from the blowing can go to washing stages where the used
cooking liquors are separated from the cellulose fibers. Typically,
a pulp mill may have multiple washing stages in series. The spent
pulping liquor, or black liquor 15, may be fed to a recovery and
regeneration zone (not shown), which can be operated according to
conventional methods.
[0064] As an option, the pulp in line 16 can be subjected to
washing in the brown stock washing zone 17, such as, for example,
by successive passage through washers and screens before discharge
of the unbleached pulp 19 from the brown stock washing zone 17 by
line 18. As an option, the unbleached pulp can be bleached at a
bleach plant 22 before the resulting bleached pulp is dried at a
pulp dryer 24 to provide market pulp 26. In the bleach option,
unbleached pulp 19 is fed to a bleach plant 22 through line 20. As
an option, pulp leaving a digester wash unit may retain a dark
brown color due to residual lignin content that it is desired to
bleach out, which can depend on the intended end use. If bleached,
conventional bleaching processes can be used on the pulp. As an
option, in the bleach plant 22, the pulp can be subjected to one or
a plurality of bleaching, caustic extraction, and washing
operations, which can result in further delignified and bleached
pulp of an increased brightness. The bleaching treatment chemicals
can be, for example, oxygen gas, ozone, chlorine dioxide, chlorine,
peroxide, pure acid or a suitable alkali for an extraction step, or
a mixture of these, and possibly other bleaching chemicals or
additives. For example, pairs of chlorine dioxide and caustic
extraction towers followed by pulp washing stages may be used for
bleaching, or other conventional pulp bleaching arrangements may be
applied to the pulp.
[0065] The bleached pulp can be discharged from the bleach plant 22
by line 23 for passage to the pulp dryer 24. As another option, as
indicated by line 21 in FIG. 1, the unbleached pulp can be fed
directly from the washing zone 17 to the pulp dryer 24 without any
intervening bleaching of the pulp. For example, in the case of a
plant designed to produce pulp to make brown sack paper or
linerboard for boxes and packaging, and the like, the pulp may not
need to be bleached to a high brightness. The pulp dryer 24 can
dewater and thermally dry the bleached or unbleached pulp to
provide dried pulp in line 25 which is market pulp. The pulp dryer
24 can include, for example, a mechanical dewatering section and a
thermal drying section, which are described in further details and
illustrations with respect to other figures herein. The market pulp
26 can be in the form of continuous dried pulp sheets, for example,
or other dried forms of pulp discharged from the pulp dryer 24.
[0066] As an option, at least one anionically charged compound and
at least one enzyme are added to treat the pulp before the pulp is
dewatered and dried in pulp dryer 24. As an option, enzyme can be
added to the pulp at feed line 27 and the anionically charged
compound can be added at feed line 28 at the inlet side of the pulp
dryer 24. The addition of at least one anionically charged compound
and at least one enzyme to the pulp before dryer 24 can improve
dewatering performance at the dryer 24. As an option, for bleached
pulp, at least one anionically charged compound and at least one
enzyme can be added to the pulp anywhere after the bleach plant 22
and before dryer 24. As another option, for unbleached pulp, at
least one anionically charged compound and at least one enzyme can
be added to the pulp anywhere after the digester 12 and before
dryer 24. As an option, the anionically charged compound is added
to the pulp no earlier than the addition of the enzyme to the pulp.
As an option, the anionically charged compound is added to the pulp
at times which can partially overlap with the addition times of the
enzyme. As an option, all amounts of the enzyme are added to the
pulp before the addition of all amounts of the anionically charged
compound to the pulp. As an option, about 80% to 100%, or from
about 85% to 100%, or from about 90% to 100%, or from about 95% to
100% by weight, of the total weight amount of enzyme is added to
the pulp prior to the earliest adding of the anionically charged
compound to the pulp. Additional details and illustrations on the
addition of the indicated treatment compounds to the pulp before
the dryer are provided in discussions of other figures herein.
[0067] The market pulp 26 discharged from pulp dryer 24 optionally
can be unitized at station or stations 29. As an option, to unitize
the market pulp, the dried pulp from the pulp dryer is formed into
bales or rolls, or other securable large scale units of the pulp
fibers. The mode of unitization of the market pulp is not
necessarily limited as long as a bale, roll or other bundle of
dried pulp fibers is secured together as a single unitary product
for transport and handling. As an option, continuous dried pulp
sheets can be produced by the pulp dryer which can be formed into
bales or rolls. As an option, continuous dried pulp sheets formed
at a pulp dryer can be cut into pieces and stacked into bales. The
pulp bales can be compressed, wrapped, and tied into secure bundles
for storage and transport. Both sheeted bales and flash dried bales
can be unitized for handling and shipment. As an option, the
unitizing can comprise wire or strap-tying bales of cut sheets of
the dried pulp, or wire or strap-tying flash-dried bales of the
dried pulp. For example, as an option, a unit of about 7 to 9 bales
can be securely wire-tied with 6 to 9 strands of heavy steel wire.
The unitized sheeted bales or flash dried bales of dried pulp
provide unitized market pulp. A sheeted bale may have a weight of
about 250 kg or other weights, which may measure approximately 27
to 32 inches wide, 35 to 37 inches long, and 17 to 18 inches high,
or other dimensions. Flash dried bales that are less densely
pressed also may be provided which may weigh about 195 to about 200
kg, or other weights. Other sizes and weights of bales of dried
pulp may be unitized. As another option, as indicated, market pulp
can be unitized as rolls or reels. For example, rolls of the market
pulp can be formed which may measure from about 7 to about 55
inches in width and from about 58 to 60 inches in diameter, or
other dimensions. The rolls of pulp optionally can be wrapped with
removable cover sheeting, wire or strap tied, or both. As an
option, the market pulp can be stored and/or transported in a
non-unitized or a unitized form to paper mills which are on-site or
off-site with respect to the pulp mill where the market pulp is
produced. The market pulp can be used in paper manufacture, such as
by reslurrying the dried pulp for papermaking processing or other
uses.
[0068] FIG. 2 shows further details on a portion of a bleached pulp
dryer 224 and an associated pulp feeding and pretreatment system
according to an option of the present invention. Bleached pulp is
drawn from one or more bleach towers 222A, 222B at the bleach plant
(e.g., bleach plant 22 in FIG. 1), and transmitted through line 223
to a surge chest 227 and from there to a machine chest 229. The
bleached pulp can be mixed in surge chest 227 until a substantially
uniform dispersion is achieved. The bleached pulp in surge chest
227 can be transmitted to the machine chest 229. The machine chest
229 can be a consistency leveling chest which provides a retention
time for the pulp which can be enough to allow variations in
consistency entering the chest to be leveled out in a generally
known manner. The pulp contents of the machine chest 229 can be
feed into a pulp dryer section 224 via a machine chest pump
231.
[0069] The pulp dryer section 224 can include a mechanical
dewatering section 224A and a thermal drying section (not shown in
this figure). Of these sections, only a portion of the mechanical
dewatering section 224A is shown in FIG. 2 with additional
information on this section and other subsequent processing
sections provided in the discussion of other figures herein. As an
option, the pulp pumped from the machine chest pump 231 can be
mixed and diluted with white water 233 from a white water silo 201
to form a stream of diluted pulp 226. The pulp 226 is pumped by
pump 203 through a centriscreen 235 to a head box 205 from which
pulp is sprayed or otherwise deposited onto wire 207. As an option,
the pump 203 can be a centrifugal pump known as a fan pump. The
pulp 208 collected on the wire 207 is advanced onto a wet press
(not shown) for further dewatering of process water, and then
thermal drying and unitization, which are described in greater
detail with respect to other figures herein. As an option, the
white water silo 201 can form part a white water recirculation loop
including lines 206 and 233 and silo 201, such as shown in FIG. 2,
which is integrated with the mechanical dewatering section 224A of
the pulp dryer 224. For example, filtrate 206, also referred to
herein as the white water, which is drained from the wire 207 can
be recirculated to the white water silo 201 for reuse as the
whitewater 233 combined with fresh pulp to form the combined stream
of pulp 226.
[0070] The treatment of the pulp 226 can include one or more
introduction point or points for each of the at least one
anionically charged compound and at least one enzyme, before the
resulting treated 236 pulp reaches the head box 205 and wire 207.
As an option, the anionically charged compound is added to the pulp
before the enzyme, such as illustrated in FIG. 2. For example, the
enzyme can be added at the inlet side of the fan pump 203 using
feeding device 202, and the anionically charged compound can be
added at the discharge side of the fan pump 203 using feeding
device 204. As an option, this sequence of addition of at least one
anionically charged compound and at least one enzyme can be
provided at other locations between the bleach towers 222A, 222B
and the head box 205 of the mechanical dewatering section 224A. As
indicated, the wet fiber sheet formed from the treated pulp as
collected on the wire 207 can be further drained and mechanically
pressed as part of the mechanical dewatering section, and then the
screened and pressed pulp can be thermally dried, before the
resulting dried pulp is conveyed to a unitizing station or
stations.
[0071] Referring to FIG. 3, as an option, digested and optionally
bleached pulp slurry 323 is combined with white water from a white
water silo 306 and the resulting diluted pulp 326 can be pumped via
a fan pump 303 to head box 305. As an option, enzyme from supply
and feeding device 302 can be added to the pulp 326 at the inlet
side of the pump 303 and anionically charged compound from supply
and feeding device 304 can be added at the outlet side of the fan
pump 303. The at least one anionically charged compound and at
least one enzyme can interact with pulp fibers and contents while
the pulp is fed towards the head box by the pumping action of the
fan pump and before being discharged from the head box onto the
wire or screen for dewatering. The at least one anionically charged
compound and at least one enzyme can interact with pulp fibers
sufficient to significantly improve drainage and dewatering
efficiencies of the pulp on the wire as compared to the same pulp
without at least one anionically charged compound and at least one
enzyme or the pulp treated with only one of at least one
anionically charged compound and at least one enzyme.
[0072] From the headbox 305, the pulp can be sprayed onto wire 307
where the pulp slurry is dewatered and forms a wet sheet of pulp
fiber. As an option, the pulp can be supplied to the headbox at
consistencies between 0.1% and 5% solids, or from about 0.5% to
about 3% solids, or from about 1% to about 2.5% by weight solids.
The pH of the treated pulp supplied to head box 305 can be, for
example, from about 4 to about 9, or from about 4.5 to about 8.0,
and can be controlled within these ranges with addition of pH
modifiers, if desired or necessary. As an option, the pulp can exit
the headbox 305 through a rectangular opening of adjustable height
called the slice, which stream lands and spreads on wire 307. The
wire may be a foraminous continuous metal screen or plastic mesh
which travels in a loop. The wire can be, for example, a flat wire
Fourdrinier, a twin wire former, or any combinations of these. Low
vacuum boxes and suction boxes may be used with the wire in
conventional manners. As an option, the sheet consistency of the
pulp after dewatering on the wire may be for example, from about 2%
to about 35%, or from about 10% to about 30% by weight, based on %
solids content, or other values. Conventional wire or screen
devices for dewatering pulp may be adapted for use in the methods
and systems of the present invention. The filtrate portion 306,
also referred to herein as white water, which is drawn and drains
through the wire 307 can be recirculated to the white water silo
301, as indicated, and then can be combined with fresh pulp 323
before the resulting diluted pulp 326 is pumped to the head box
305.
[0073] The pulp 308 which is collected on wire 307 can be passed
forward to a wet-press section 309. Additional water can be pressed
and vacuumed from the pulp 308 at wet-press section 309. As an
option, press section 309 can remove water from the pulp with a
system of nips formed by rolls pressing against each other aided by
press felts that support the pulp sheet and can absorb the pressed
water. A vacuum box, such as a Uhle box, optionally can be used,
for example, to apply vacuum to the press felt to remove the
moisture so that when the felt returns to the nip on the next
cycle, it does not add moisture to the sheet. As an option, the
pulp sheet can be passed through a series of rotating rolls
("presses") that squeeze out water and air until the fiber
consistency of the pulp sheet is from about 40% to about 50% by
weight. As an option, the pressed pulp can comprise up to about 50%
solids after pressing, or from about 20% to about 45% solids, or
other values.
[0074] The screened and pressed pulp 310 can be moved to a thermal
dryer section 311 for evaporative drying. Heat can be used at
thermal dryer section 311 to remove additional water, such as by
evaporation. As an option, the pulp 310 can be dried in the thermal
dryer section 311 at a temperature in the range of 60.degree. C. to
127.degree. C. (140.degree. F. to 260.degree. F.) to remove more
water. As an option, the thermal dryer can have, for example, a
series of internally steam-heated cylinders that evaporate the
moisture of the pulp as the pulp is advanced over the heated
cylinders. As an option, a pressed pulp sheet can be floated
through a multi-story sequence of hot-air dryers until the
consistency is from about 80% to about 97% by weight consistency,
or from about 85% to about 95% by weight, or other values. As an
option, the dried pulp leaving the pulp dryer has an absolute
moisture content (i.e., total H.sub.2O content based on total
weight of pulp) of less than about 20% by weight, or less than
about 15% by weight, or less than about 10% by weight, or from
about 5% to about 20% by weight, or from about 5% to about 10% by
weight. For example, dried pulp containing 12 total parts by weight
water (all forms) and 100 parts by weight dry pulp fiber has an
absolute moisture content of 10% by weight (i.e.,
12/(12+100)*100).
[0075] The dried pulp 325 exiting the thermal dryer 311 is market
pulp 326. As an option, market pulp 326 provided by the thermal
drying can be in the form of continuous dried pulp sheets. The
market pulp 326 can optionally be unitized at station or stations
327 as in FIG. 1 to obtain a unitized market pulp 329 (e.g., bales,
rolls, or other forms).
[0076] As an option, the indicated at least one anionically charged
compound and at least one enzyme used to treat the pulp to improve
dewatering performance can be water soluble or water dispersible
compounds.
[0077] As an option, inorganic anionic coagulants can be used, such
as polyphosphates, anionic silica sol, or any combinations
thereof.
[0078] As an option, at least one anionically charged compound can
be added to the pulp in processes of the present invention, such as
at the approach to the pulp dryer as illustrated or elsewhere after
any bleaching and before the pulp dryer, in an amount from about
0.1 lb. to about 10 pounds (lb.) anionically charged compound/ton
dry fiber, or from about 0.2 to about 8 lb. charged compound/ton
dry fiber, or from about 0.3 to about 4 lb. anionically charged
compound/ton dry fiber, or from about 0.5 to about 3 lb.
anionically charged compound/ton dry fiber (on a solids/solids
basis).
[0079] The enzyme can be added to pulp in an amount from about
0.001 to about 2 pounds (lb.) active enzyme/ton dry fiber, or from
about 0.01 to about 1.5 lb./ton dry fiber, or from about 0.1 to
about 1 lb./ton dry fiber, or other amounts.
[0080] As an option, at least one anionically charged compound and
at least one enzyme can be added to the pulp in a total amount of
from about 0.2 lb./ton dry fiber to about 12 lb./ton dry fiber, or
from about 0.4 to about 10 lb./ton dry fiber, or from about 0.6 to
about 8 lb./ton dry fiber, or from about 1 to about 6 lb./ton dry
fiber (on a solids/solids basis), or other values. As an option, at
least one anionic compound and at least one enzyme can be added to
the pulp in a weight ratio (w:w) of from about 10,000:1 to 1:10, or
from about 1000:1 to about 1:5, or from about 100:1 to about 1:1,
or from about 10:1 to about 2:1, or other ratios.
[0081] Wood chips suitable for use in the production of market pulp
in the present invention can be derived from hardwood tree species,
softwood tree species, or combinations thereof. Softwood tree
species include, but not limited to: fir (such as Douglas fir and
balsam fir), pine (such as Eastern white pine and Loblolly pine),
spruce (such as white spruce), larch (such as Eastern larch),
cedar, and hemlock (such as Eastern and Western hemlock). Examples
of hardwood tree species include, but are not limited to: acacia,
alder (such as red alder and European black alder), aspen (such as
quaking aspen), beech, birch, oak (such as white oak), gum trees
(such as eucalyptus and sweet gum), poplar (such as balsam poplar,
Eastern cottonwood, black cottonwood, and yellow poplar), maple
(such as sugar maple, red maple, silver maple, and big leaf maple).
These types of woods can be used individually or in any
combinations thereof. As an option, a combination of hemlock and
cottonwood particulates can be used. As an option, the wood chips
to be pulped include virgin wood material, such as at least 50% by
weight up to 100% by weight virgin wood material. As an option,
other pulpable material may be used or included in the feedstock,
such as recycled fiber materials, such as recycled fiber from
post-consumer waste, or non-wood materials, such as grasses,
agricultural residues, bamboo, Bast materials (e.g., Ramie, flax,
hemp), or any combinations thereof.
[0082] In addition to at least one anionically charged compound and
at least one enzyme, the pulps may be treated with one or more
optional additives within the market pulp making system as long as
they do not interfere with the indicated function of at least one
anionically charged compound and at least one enzyme to improve
dewatering performance of the treated pulps. A list of optional
chemical additives that can be used in conjunction with the present
invention include, for example, pH modifiers, dry strength agents,
wet strength agents, softening agents, debonding agents, adsorbency
agents, sizing agents, dyes, optical brighteners, chemical tracers,
opacifiers, dryer adhesive chemicals, and the like. Additional
optional chemical additives may include, for example, pigments,
emollients, humectants, viricides, bactericides, buffers, waxes,
fluoropolymers, odor control materials and deodorants, zeolites,
perfumes, vegetable and mineral oils, polysiloxane compounds, other
surfactants, moisturizers, UV blockers, antibiotic agents, lotions,
fungicides, preservatives, aloe-vera extract, vitamin E, or the
like. Suitable optional chemical additives can be retained by the
pulp fibers and may or may not be water soluble or water
dispersible. As indicated, cationically charged compounds are not
required to be additionally added or present in a pulp treatment of
the present invention which uses at least one anionically charged
compound and at least one enzyme to obtain improvements in
dewatering performance.
[0083] As indicated, the combined treatment of the pulp with the at
least one anionically charged compound and at least one enzyme can
provide significantly higher dewatering performance than when using
either single chemistry treatment. In some options, though
correlation of water retention with free drainage can vary with
ionically charged compound type and application process, free
drainage generally can demonstrate good correlation with water
retention. In some options, increasing the dosage of the ionically
charged compounds in the pulp can slightly reduce WRV and increase
dewatering wherein the improvements ultimately can peak or level
off with progressively increased dosages.
[0084] A market pulp product can be provided that includes the
market pulp or unitized pulp which has at least one anionically
charged compound and at least one enzyme retained at least in part
to the pulp fibers from the indicated treatment method. The market
pulp made in processes according to the present invention can
comprise, for example, from about 0.001 to about 5 pounds (lb.)
anionically charged compound/ton dry fiber, or from about 0.01 to
about 3 lb. anionically charged compound/ton dry fiber, or from
about 0.1 to about 2 lb. anionically charged compound/ton dry
fiber, or from about 0.2 to about 1 lb. anionically charged
compound/ton dry fiber (on a solids/solids basis), and the enzyme
can be contained in the market pulp in an amount of from about
0.000001 lb. to about 1 lb./ton dry fiber or from about 0.00001 lb.
to about 0.1 lb./ton dry fiber.
[0085] In an industrial situation where market pulp is produced, a
large capital expenditure to build a massive steam-operated dryer
usually is needed. Once that is in place, a large amount of energy
is required to remove the water from the pulp. An improvement in
the water removal from the fiber pad, as can be provided by the
present invention, can be leveraged to benefit the producer in
several ways. If a sheet with less moisture enters the dryer, less
steam is required to dry the sheet to the point where it can be
shipped. At the same time, an alternative is to limit the reduction
in steam usage and instead speed up the machine. The benefit then
is an increase in production, which can be provided by the present
invention.
[0086] The present invention will be further clarified by the
following examples, which are intended to be only exemplary of the
present invention. Unless indicated otherwise, all amounts,
percentages, ratios and the like used herein are by weight.
EXAMPLES
Example 1
[0087] Experiments were conducted to compare water drainage of pulp
treated using an anionic surfactant alone, an enzyme alone, and
their combination as added to the pulp and also a separate
combination of the anionic surfactant with a different enzyme, and
water drainage of untreated pulp.
[0088] A laboratory test was conducted for the evaluation. As
indicated, separate experiments were run on pulps to compare the
effects of using the anionic surfactant and an enzyme individually
and in combinations of the anionic surfactant and an enzyme. A
control test also was conducted with no chemical additive used on
the pulp.
[0089] The enzymes used for these experiments were BLX-14303 from
Buckman Laboratories, containing a xylanase enzyme as the active
component ("enzyme X"), and BLX-14350 from Buckman Laboratories,
containing a completely different xylanase enzyme as the active
component ("enzyme Y"). The anionic surfactant was sodium lauryl
ether sulfate (3 moles EO), which was used in an aqueous solution
at a 30% (wt.) concentration of the anionic surfactant. The dosage
rate of anionic surfactant used was 2 g of anionic surfactant/kg
dry fiber pulp. The dosage rate of enzyme, for each of enzyme X and
enzyme Y, was 1 g of enzyme/kg dry fiber pulp.
[0090] The following testing procedure was applied. A slurry of
bleached pulp to be tested was prepared with a consistency of about
1 percent by weight in tap water. Water removal from the slurry was
evaluated using a Mutek DFR-05 drainage/retention tester. A
selected volume of this slurry (500 mL) was added into a chamber
which has a screen at the bottom. Any anionic surfactant and/or
enzyme included in a test sample was pre-mixed with the slurry
before addition to the chamber. The screen was a metallic mesh
screen (mesh size=600 mesh). When the test was initiated, the water
was allowed to drain from the slurry through the screen. The amount
of water that drained freely from the sample, and the rate of
drainage was monitored. No vacuum nor pressure was applied for the
first 30 seconds after initiating drainage from the chamber. At 30
seconds after the drainage is initiated, the testing apparatus
(i.e., a DFR with forced dewatering (controlled mechanical level))
was used to apply pressure to the pad (i.e., the fiber mat
collected on the screen). Again the rate of water being removed
from the pad was measured. At 50 seconds additional pressure was
applied, and at 70 seconds again additional pressure was applied.
This procedure, including the amount of pressure applied at each
stage, mimics the dewatering and pressing that occurs on a paper
machine or on a pulp dryer. Free drainage rates in g/30 sec and
g/90 sec were determined based on the measurements.
[0091] The results of these experiments are shown in Tables 1 and
2. Table 1 below shows raw data from a set of tests, and Table 2
shows the deviations in results for the samples which contained an
anionic surfactant, an enzyme, or both, from the control. The
numbers in Tables 1 and 2 are grams of water drained from a sample.
The result after 30 seconds is free drainage, 30 seconds after
drainage is initiated. The result after 90 seconds is for the total
water removed after free drainage and 3 additional pressings.
TABLE-US-00001 TABLE 1 raw data Time Sample 30 sec. 90 sec. Control
345 385.5 anionic surfactant A (30%) 349 404.5 anionic surfactant A
(30%) + 358 419 enzyme X anionic surfactant A (30%) + 359 420.5
enzyme Y enzyme Y 348.5 387
TABLE-US-00002 TABLE 2 water removal: change vs. control 30 sec. 90
sec. anionic surfactant A (30%) 4 19 anionic surfactant A (30%) +
13 33.5 enzyme X anionic surfactant A (30%) + 14 35 enzyme Y enzyme
Y 3.5 1.5
[0092] These experimental results show that treating a pulp slurry
with the combination of anionic surfactant and enzyme, e.g., a
cellulolytic or hemicellulolytic enzyme, together provides an
unexpected better-than-additive result to improve the removal of
water. It is apparent from the data that the combination provides a
synergistic effect on water removal, much better than either
treatment alone, and much better than the additive effect
expected.
Example 2
[0093] An additional experiment was conducted to compare water
removal from pulp treated using an anionic surfactant alone, an
enzyme alone, and their combination as added to the pulp and also a
separate combination of the anionic surfactant with a different
enzyme, and water drainage of untreated pulp.
[0094] The laboratory test conducted is similar to that shown in
Example 1. Again, separate experiments were run on pulps to compare
the effects of using the anionic surfactant and an enzyme
individually and in combinations of the anionic surfactant and an
enzyme. A control test also was conducted with no chemical additive
used on the pulp.
[0095] The enzyme used for these experiments was a formula prepared
from enzyme NS-51121 available from Novozymes ("enzyme"), which
contains a xylanase enzyme, and an anionic surfactant (sodium
lauryl ether sulfate (3 moles EO) (designated "surfactant"), which
was used in an aqueous solution in a 30% active aqueous formula.
The dosage rate of anionic surfactant used was 2 g of 30% active
formula/kg of dry fiber pulp. The dosage rate of enzyme was 1 g of
enzyme formula/kg of dry fiber pulp.
[0096] The testing procedure applied is as described in Example 1.
A slurry of bleached pulp to be tested was prepared with a
consistency of about 1 percent by weight in tap water. A selected
volume of this slurry (500 mL) was added into a chamber which has a
screen at the bottom. Any anionic surfactant and/or enzyme included
in a test sample was pre-mixed with the slurry before addition to
the chamber. When the test was initiated, the water was allowed to
drain from the slurry through the screen. The amount of water that
drained freely from the sample, and the rate of drainage was
monitored. No vacuum nor pressure was applied for the first 30
seconds after initiating drainage from the chamber. At 30 seconds
after the drainage is initiated, pressure was applied to the pad,
followed by pressure applied again at 50 seconds, and once more at
70 seconds. The rate of water being removed from the pad was
measured. Total water removed from the pad was measured.
[0097] The results of these experiments are shown in FIGS. 4 and 5.
FIG. 4 records the total water removed from the sample through the
90-second test. From the results, the addition of the surfactant
improves water removal, and the application of the enzyme also
improves water removal. The data also show that there is a
difference in the effect from the enzyme compared to that for the
surfactant. The data also demonstrate that with the combination of
enzyme and surfactant, the total water removed is greater than the
benefit that can be achieved with either component alone. Further,
there is some difference in the effect of each component. The
enzyme provides the effect of faster initial ("free") drainage. The
advantage of this effect is that more water is removed prior to the
presses. The surfactant provides the advantage of better water
removal in the pressing. The combination of the two mechanisms
provide the best result.
[0098] These same data are shown in FIG. 5. The total water removed
at the 8-second point shows the effect on initial free drainage.
The total at the 30-second point is the final free drainage. The
positive effect especially of the enzyme is shown. The final
measurement at the 90-second point gives the total water removed.
For reference, the initial total volume of water is 495 mL.
[0099] The benefit of this invention is demonstrated another way in
Table 3. The "final pad consistency" is the percent fiber in the
final pad after pressing. The goal is to maximize the pad
consistency. If less water remains after pressing, less heat and
steam is required to dry the pad to its final specification. A
general rule on a pulp dryer is that a 1 percent increase in pad
consistency entering the drying process results in a 4 percent
reduction in energy required to dry the pad. Addition of surfactant
alone or enzyme alone give similar benefits, but the combination
gives a much better result.
TABLE-US-00003 TABLE 3 final pad consistency % improvement Blank
4.90 -- surfactant only 5.78 18 enzyme only 5.68 16 surfactant +
enzyme 6.06 24
[0100] Again, these experimental results show that treating a pulp
slurry with the combination of anionic surfactant and enzyme, e.g.,
a cellulolytic or hemicellulolytic enzyme, together provides an
unexpected better-than-additive result to improve the removal of
water. It is apparent from the data that the combination provides a
synergistic effect on water removal, much better than either
treatment alone, and much better than the additive effect
expected.
[0101] The present invention includes the following
aspects/embodiments/features in any order and/or in any
combination:
1. The present invention relates to a method for producing market
pulp, comprising:
[0102] forming cellulosic particulates into pulp;
[0103] adding at least one anionically charged compound and at
least one enzyme to said pulp to provide treated pulp;
[0104] mechanically dewatering said treated pulp to provide
mechanically dewatered pulp; and
[0105] thermally drying said mechanically dewatered pulp to form
market pulp.
2. The method of any preceding or following
embodiment/feature/aspect, wherein at least part of said adding of
said enzyme to said pulp occurs prior to said adding of said
anionically charged compound to said pulp. 3. The method of any
preceding or following embodiment/feature/aspect, wherein about 80%
to 100% by weight of said adding of said enzyme to said pulp occurs
prior to said adding of said anionically charged compound to said
pulp. 4. The method of any preceding or following
embodiment/feature/aspect, wherein the anionically charged compound
is an organic anionically charged compound. 5. The method of any
preceding or following embodiment/feature/aspect, wherein the
enzyme is a hydrolytic enzyme. 6. The method of any preceding or
following embodiment/feature/aspect, further comprising bleaching
the pulp after the pulp forming and before the adding of the
anionically charged compound and enzyme to said pulp. 7. A method
for producing market pulp, comprising:
[0106] forming cellulosic particulates into pulp;
[0107] adding at least one anionic surfactant and at least one
enzyme to said pulp to provide treated pulp;
[0108] mechanically dewatering said treated pulp to provide
mechanically dewatered pulp; and
[0109] thermally drying said mechanically dewatered pulp to form
market pulp.
8. The method of any preceding or following
embodiment/feature/aspect, wherein at least part of said adding of
said enzyme to said pulp occurs prior to said adding of said
anionic surfactant to said pulp. 9. The method of any preceding or
following embodiment/feature/aspect, wherein about 80% to 100% by
weight of said adding of said enzyme to said pulp occurs prior to
said adding of said anionic surfactant to said pulp. 10. The method
of any preceding or following embodiment/feature/aspect, further
comprising bleaching the pulp after the pulp forming and before the
adding of the anionic surfactant and enzyme to said pulp. 11. The
method of any preceding or following embodiment/feature/aspect,
wherein the anionic surfactant is a sulfate surfactant, a sulfonate
surfactant, a sulfosuccinate surfactant or any combinations
thereof. 12. The method of any preceding or following
embodiment/feature/aspect, wherein the anionic surfactant is an
alcohol sulfate, an alcohol alkoxy sulfate, a sulfonate, a dialkyl
sulfosuccinate, an sulfosuccinic acid ester with an ethoxylated
alcohol, or a soluble or dispersible salt thereof, or any
combinations thereof. 13. The method of any preceding or following
embodiment/feature/aspect, wherein the enzyme is cellulase,
hemicellulase, pectinase, cellobiase, xylanase, mannanase,
.beta.-glucanase, carboxymethylcellulase, amylase, glucosidase,
galactosidase, laccase, or any combinations thereof. 14. The method
of any preceding or following embodiment/feature/aspect, wherein
said forming provides kraft pulp, sulfite pulp, fluff pulp,
dissolving pulp, bleached chemothermomechanical pulp, or any
combinations thereof. 15. The method of any preceding or following
embodiment/feature/aspect, further comprising bleaching the pulp
after the pulp forming and before the adding of the anionic
surfactant and enzyme to said pulp. 16. The method of any preceding
or following embodiment/feature/aspect, wherein said mechanically
dewatering comprises screening and pressing of the pulp, wherein
drained white water from said screening is combined with fresh pulp
and pumped with a fan pump to a head box for the screening, wherein
said enzyme is fed into the combined fresh pulp and white water
before entering the fan pump, and said anionic surfactant is fed
into said combined fresh pulp and white water after exiting said
fan pump and before reaching the headbox. 17. The method of any
preceding or following embodiment/feature/aspect, wherein the
anionic surfactant and enzyme are added to the pulp in a ratio of
from about 10,000:1 to about 1:10. 18. The method of any preceding
or following embodiment/feature/aspect, wherein the anionic
surfactant is added to the pulp in an amount of from about 0.1
lb./ton dry fiber to about 10 lb./ton dry fiber, and the enzyme is
added to the pulp in an amount of from about 0.001 lb./ton dry
fiber to about 2 lb./ton dry fiber. 19. The method of any preceding
or following embodiment/feature/aspect, further comprising
unitizing said market pulp to form unitized market pulp. 20. The
method of any preceding or following embodiment/feature/aspect,
wherein the cellulosic particulates are hardwood chips, softwood
chips, recycled paper fiber, or any combinations thereof. 21. The
method of any preceding or following embodiment/feature/aspect,
wherein the combination of treating the pulp with the at least one
anionic surfactant and at least one enzyme before dewatering in the
production of market pulp is effective to provide at least one of
the following:
[0110] (i) increased pulp free drainage (g/90 sec) to a value which
is at least 7.5% times greater than free drainage value obtained
without any treatment in the pulp;
[0111] (ii) increased pulp free drainage to a value which is at
least about 3% greater than free drainage value obtained with using
the anionic surfactant individually in the pulp (without the
enzyme);
[0112] (iii) increased pulp free drainage to a value which is at
least about 10% greater than a free drainage value calculated as a
sum of the free drainage increases obtained from using the anionic
surfactant and enzyme separately and individually in the pulp;
and
[0113] (iv) reducing pulp water retention value (WRV) to a value
which is at least about 10% less than WRV obtained with using the
anionic surfactant separately and individually in the pulp (without
the enzyme).
22. The method of any preceding or following
embodiment/feature/aspect, wherein the treating is effective for
increasing obtained free drainage to a value which is at least five
times greater than free drainage value obtained without any
treatment of the pulp. 23. The method of any preceding or following
embodiment/feature/aspect, wherein the treating is effective for
increasing obtained free drainage to a value which is from about
60% to about 200% greater than free drainage value obtained with
using the anionic surfactant individually in the pulp. 24. A market
pulp made by the method of any preceding or following
embodiment/feature/aspect containing said anionically charged
compound and said enzyme. 25. A market pulp made by the method of
any preceding or following embodiment/feature/aspect containing
said anionic surfactant and said enzyme. 26. A system for producing
market pulp comprising:
[0114] a supply of cellulosic particulates;
[0115] at least one pulp forming unit for forming pulp from said
cellulosic particulates;
[0116] at least one feeding device for feeding at least one
anionically charged compound to said pulp;
[0117] at least one feeding device for feeding at least one enzyme
to said pulp to provide treated pulp after addition of both the
anionically charged compound and the enzyme;
[0118] a mechanical dewatering device for mechanically removing
water from said treated pulp to provide mechanically dewatered
pulp; and
[0119] a thermal drying device for thermally removing water from
said mechanically dewatered pulp to provide market pulp.
27. The system of any preceding or following
embodiment/feature/aspect, wherein said at least one feeding device
for feeding anionically charged compound feeds anionic surfactant
and said at least one feeding device for feeding enzyme feeds
hydrolytic enzyme. 28. The system of any preceding or following
embodiment/feature/aspect, wherein said pulp forming unit is a
digester capable of receiving at least one chemical for digesting
the cellulosic particulates. 29. The system of any preceding or
following embodiment/feature/aspect, wherein said mechanical
dewatering device comprises screen and press sections, wherein
drained white water from the screen section is combinable with
fresh pulp and pumpable with a fan pump to a head box of the
mechanical dewatering device, wherein said at least one feeding
device for said enzyme is capable of feeding said enzyme into the
combined fresh pulp and white water before entering said fan pump,
and said at least one feeding device for said anionically charged
compound is capable of feeding said anionically charged compound
into said combined fresh pulp and white water after exiting said
fan pump and before reaching the headbox. 30. The system of any
preceding or following embodiment/feature/aspect, further
comprising a bleaching unit for bleaching the pulp after the pulp
forming unit and before the adding of the anionically charged
compound and enzyme to said pulp with said feeding devices. 31. The
system of any preceding or following embodiment/feature/aspect,
wherein the first and second feeding devices being capable of
introducing respective first and second amounts of the anionically
charged compound and enzyme to pulp drawn from the pulp forming
unit to provide at least one of the following:
[0120] (i) increased pulp free drainage (g/90 sec) to a value which
is at least 7.5% times greater than free drainage value obtained
without any treatment in the pulp;
[0121] (ii) increased pulp free drainage to a value which is at
least about 3% greater than free drainage value obtained with using
the anionically charged compound individually in the pulp (without
the enzyme);
[0122] (iii) increased pulp free drainage to a value which is at
least about 10% greater than a free drainage value calculated as a
sum of the free drainage increases obtained from using the
anionically charged compound and enzyme separately and individually
in the pulp; and
[0123] (iv) reducing pulp water retention value (WRV) to a value
which is at least about 10% less than WRV obtained with using the
anionically charged compound individually in the pulp (without the
enzyme).
[0124] The present invention can include any combination of these
various features or embodiments above and/or below as set forth in
sentences and/or paragraphs. Any combination of disclosed features
herein is considered part of the present invention and no
limitation is intended with respect to combinable features.
[0125] Applicant specifically incorporates the entire contents of
all cited references in this disclosure. Further, when an amount,
concentration, or other value or parameter is given as either a
range, preferred range, or a list of upper preferable values and
lower preferable values, this is to be understood as specifically
disclosing all ranges formed from any pair of any upper range limit
or preferred value and any lower range limit or preferred value,
regardless of whether ranges are separately disclosed. Where a
range of numerical values is recited herein, unless otherwise
stated, the range is intended to include the endpoints thereof, and
all integers and fractions within the range. It is not intended
that the scope of the invention be limited to the specific values
recited when defining a range.
[0126] Other embodiments of the present invention will be apparent
to those skilled in the art from consideration of the present
specification and practice of the present invention disclosed
herein. It is intended that the present specification and examples
be considered as exemplary only with a true scope and spirit of the
invention being indicated by the following claims and equivalents
thereof.
* * * * *