U.S. patent application number 11/748814 was filed with the patent office on 2008-01-31 for method and apparatus for loading fibers or cellulose which are contained in a suspension with a filler.
Invention is credited to Reinhard Gather.
Application Number | 20080023161 11/748814 |
Document ID | / |
Family ID | 35840399 |
Filed Date | 2008-01-31 |
United States Patent
Application |
20080023161 |
Kind Code |
A1 |
Gather; Reinhard |
January 31, 2008 |
METHOD AND APPARATUS FOR LOADING FIBERS OR CELLULOSE WHICH ARE
CONTAINED IN A SUSPENSION WITH A FILLER
Abstract
The present invention provides a method for the loading of
fibers or cellulose included in a suspension with a filler by way
of a chemical precipitation reaction, wherein the fibers or
cellulose are provided in the form of a suspension having a
predetermined solids concentration. Carbon dioxide is added to the
fibers or to the cellulose in the form of a suspension. The fibers
or the cellulose in form of a suspension to which carbon dioxide
has been added are mixed with milk of lime or slaked lime, such as
in at least one reactor, thereby triggering and extensively, such
as completely, concluding the chemical precipitation reaction.
Inventors: |
Gather; Reinhard; (Neustadt,
DE) |
Correspondence
Address: |
Todd T. Taylor;Taylor & Aust, P.C.
P.O. Box 560
142 S. Main Street
Avilla
IN
46710
US
|
Family ID: |
35840399 |
Appl. No.: |
11/748814 |
Filed: |
May 15, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/EP05/11498 |
Oct 27, 2005 |
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11748814 |
May 15, 2007 |
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Current U.S.
Class: |
162/63 ;
162/157.6; 162/243 |
Current CPC
Class: |
D21H 11/16 20130101;
D21H 17/70 20130101; D21H 17/675 20130101 |
Class at
Publication: |
162/063 ;
162/157.6; 162/243 |
International
Class: |
D21H 11/16 20060101
D21H011/16; D21H 17/70 20060101 D21H017/70 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2004 |
DE |
10 2004 060 405.3 |
Claims
1. A method for loading one of a plurality of fibers and cellulose
included in a suspension with a filler by using a chemical
precipitation reaction, said method comprising the steps of:
providing one of the plurality of fibers and the cellulose in a
form of the suspension having a predetermined solids concentration;
adding carbon dioxide to one of the plurality of fibers and the
cellulose in said form of the suspension; and mixing one of the
plurality of fibers and the cellulose in said form of the
suspension to which carbon dioxide has been added with one of a
milk of lime and a slaked lime, thereby triggering and extensively
concluding the chemical precipitation reaction.
2. The method in accordance with claim 1, wherein said mixing step
occurs in at least one reactor.
3. The method in accordance with claim 2, wherein said carbon
dioxide is added to the suspension in at least one unit which is
located upstream from said reactor in a process sequence.
4. The method in accordance with claim 3, wherein said at least one
unit is heated.
5. The method in accordance with claim 3, wherein said carbon
dioxide is added to the suspension under an influence of a
plurality of shear forces.
6. The method in accordance with claim 3, wherein said carbon
dioxide is added to the suspension by utilizing a plurality of
mixing effects.
7. The method in accordance with claim 6, wherein said carbon
dioxide is added to the suspension by utilizing at least one
stationary mixing system.
8. The method in accordance with claim 6, wherein said carbon
dioxide is added to the suspension in at least one stationary
mixer.
9. The method in accordance with claim 8, wherein said carbon
dioxide is added to the suspension in said at least one stationary
mixer under an influence of a plurality of flow turbulences.
10. The method in accordance with claim 6, wherein said carbon
dioxide is added to the suspension by utilizing at least a
partially driven mixing system.
11. The method in accordance with claim 10, wherein said carbon
dioxide is added to the suspension in at least one agitator.
12. The method in accordance with claim 5, wherein said carbon
dioxide is added to the suspension in a pump disperger.
13. The method in accordance with claim 1, wherein the chemical
precipitation reaction is completely concluded.
14. The method in accordance with claim 1, wherein at least one of
said step of adding said carbon dioxide and said step of mixing
with one of said milk of lime and said slaked lime occurs
continuously.
15. The method in accordance with claim 1, wherein said mixing step
occurs in at least one reactor, said carbon dioxide being added to
the suspension in said reactor where a blending of the suspension
with one of said milk of lime and said slaked lime is
staggered.
16. The method in accordance with claim 15, wherein said step of
adding said carbon dioxide and said step of mixing with one of said
milk of lime and said slaked lime occurs in a batch operation.
17. The method in accordance with claim 1, further comprising the
step of adding water to the suspension prior to adding said carbon
dioxide.
18. The method in accordance with claim 1, wherein said mixing step
occurs in at least one reactor, further comprising the step of
adding water into said reactor at least one of prior to, during,
and after adding one of said milk of lime and said slaked lime.
19. The method in accordance with claim 1, further comprising the
step of degassing the suspension using a degassing unit prior to
said step of adding said carbon dioxide.
20. The method in accordance with claim 1, wherein said carbon
dioxide is added to the suspension under pressure.
21. The method in accordance with claim 1, wherein said carbon
dioxide is added to the suspension at least one of as pure carbon
dioxide and as flue gas.
22. The method in accordance with claim 1, wherein the suspension
one of is produced by dissolving one of a cellulose and a waste
paper using additives in at least one pulper and is supplied to the
loading process as a non-dried pulp.
23. The method in accordance with claim 22, wherein said non-dried
pulp is from another pulp mill.
24. The method in accordance with claim 1, wherein said mixing step
occurs in at least one reactor, further comprising the step of
measuring a plurality of reaction parameters in said at least one
reactor, said plurality of reaction parameters being utilized if
necessary to adjust the chemical precipitation reaction.
25. The method in accordance with claim 24, wherein said plurality
of reaction parameters includes at least one of a pH-value, a
temperature, a dwell time, a throughput of the suspension, and one
of said milk of lime and said slaked lime.
26. The method in accordance with claim 25, wherein said pH-value
of the suspension as measured at an end of the chemical
precipitation reaction is compared with a desired value and a
deviation is one of reduced and removed through at least one of a
plurality of correcting variables including an addition of one of
said milk of lime and said slaked lime, an addition of said carbon
dioxide, and a throughput of the suspension.
27. An apparatus for loading one of a plurality of fibers and
cellulose included in a suspension with a filler by using a
chemical precipitation reaction, said apparatus comprising: at
least one reactor configured for being that in which one of the
plurality of fibers and the cellulose in a form of the suspension
to which carbon dioxide has been added is mixed with one of a milk
of lime and a slaked lime such that the chemical precipitation
reaction is triggered and largely concluded, one of the plurality
of fibers and the cellulose being in said form of the suspension
having a predetermined solids concentration, the apparatus being
configured for: adding carbon dioxide to one of the plurality of
fibers and the cellulose in said form of the suspension; and mixing
one of the plurality of fibers and the cellulose in said form of
the suspension to which carbon dioxide has been added with one of
said milk of lime and said slaked lime, thereby triggering and
extensively concluding the chemical precipitation reaction.
28. The apparatus in accordance with claim 27, wherein said reactor
is configured such that the chemical precipitation reaction is
completely concluded.
29. The apparatus in accordance with claim 27, further comprising
at least one unit located upstream from said reactor in a process
sequence, said at least one unit configured for being that in which
carbon dioxide is added to one of the plurality of fibers and the
cellulose in said form of the suspension.
30. The apparatus in accordance with claim 27, wherein said at
least one unit is heated.
31. The apparatus in accordance with claim 30, wherein said at
least one unit which is located upstream from said reactor in said
process sequence includes at least one pump disperger configured
for producing shear forces during said addition of carbon dioxide
to the suspension.
32. The apparatus in accordance with claim 30, wherein said at
least one unit which is located upstream from said reactor in said
process sequence includes at least one stationary mixing system
configured for causing a plurality of mixing effects during said
addition of said carbon dioxide to the suspension.
33. The apparatus in accordance with claim 32, wherein said
stationary mixing system includes at least one stationary
mixer.
34. The apparatus in accordance with claim 33, wherein said at
least one stationary mixer includes a supply line through which the
suspension flows and which produces a plurality of flow
turbulences, at least over a plurality of segments, during said
addition of said carbon dioxide to the suspension.
35. The apparatus in accordance with claim 30, wherein said at
least one unit which is located upstream from said reactor in said
process sequence includes at least one partially driven mixing
system which produces a plurality of mixing effects during said
addition of said carbon dioxide to the suspension.
36. The apparatus in accordance with claim 35, wherein said at
least one partially driven mixing system includes at least one
agitator.
37. The apparatus in accordance with claim 27, wherein said at
least one reactor includes at least one supply line configured for
supplying carbon dioxide to one of the plurality of fibers and the
cellulose in said form of the suspension at least one of prior to
and at the same time as one of said milk of lime and said slaked
lime is supplied.
38. The apparatus in accordance with claim 27, further comprising
at least one supply line configured for adding water at least one
of prior to said addition of said carbon dioxide and at least one
of prior to, during, and after adding one of said milk of lime and
said slaked lime.
39. The apparatus in accordance with claim 27, further comprising
at least one degassing unit configured for degassing the suspension
prior to said addition of said carbon dioxide.
40. The apparatus in accordance with claim 27, further comprising a
pressure generating unit configured for adding pressurized carbon
dioxide to the suspension.
41. The apparatus in accordance with claim 27, further comprising
at least one pulper configured for producing the suspension one of
by dissolving one of a cellulose and a waste paper using additives
and through a supply of a non-dried pulp.
42. The apparatus in accordance with claim 27, wherein said reactor
includes at least one system configured for measuring a plurality
of reaction parameters and for adjusting if necessary the chemical
precipitation reaction.
43. The apparatus in accordance with claim 42, wherein said
plurality of reaction parameters includes at least one of a
pH-value, a temperature, a dwell time, a throughput of suspension,
and one of said milk of lime and said slaked lime.
44. A fiber web comprising: a filler; and one of a plurality of
fibers and a cellulose in a form of at least one suspension
including said filler, one of said plurality of fibers and said
cellulose configured for being loaded with said filler using a
chemical precipitation reaction by: providing one of said plurality
of fibers and said cellulose in said form of said at least one
suspension having a predetermined solids concentration; adding
carbon dioxide to one of said plurality of fibers and said
cellulose in said form of said at least one suspension; and mixing
one of said plurality of fibers and said cellulose in said form of
said at least one suspension to which carbon dioxide has been added
with one of a milk of lime and a slaked lime, thereby triggering
and extensively concluding the chemical precipitation reaction.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of PCT application No.
PCT/EP2005/011498, entitled "METHOD AND DEVICE FOR LOADING FIBERS
OR CELLULOSE CONTAINED IN A SUSPENSION WITH A FILLER", filed Oct.
27, 2005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method as well as to an apparatus
for loading of fibers or cellulose contained in a suspension with a
filler by way of a chemical precipitation reaction, wherein the
fibers or cellulose are provided in the form of a suspension having
a predetermined solids concentration.
[0004] 2. Description of the Related Art
[0005] In the production of fibrous webs, especially paper or
cardboard webs fillers, especially precipitated calcium carbonate
(PCC) or disintegrated or ground calcium carbonate (GCC) represent
conventional substances which are used to reduce the fibrous
material content as well as to improve the optical characteristics
of the web.
[0006] The commercially available PCC or GCC fillers are bulk
materials which are produced in special manufacturing facilities
which may be satellite plants of a paper or cardboard plant. An
on-line production of PCC however has never been considered, or is
never considered in the paper or cardboard industry because of the
special process characteristics which are associated with the
production of PCC. Instead, PCC or GCC are transported as bulk
material or in the form of a suspension to the paper or cardboard
plants.
[0007] Loading of fibers or cellulose contained in a suspension
with an additive, for example a filler, may for example occur
through a chemical precipitation reaction, in other words
especially through a so-called "Fiber Loading.TM." process as
described in the U.S. patent document U.S. Pat. No. 5,223,090 A. In
said "Fiber Loading.TM." process at least one additive, especially
a filler is deposited onto the moistened fiber surfaces of the
fibrous material. In this context the fibers may for example be
loaded with calcium carbonate. To accomplish this calcium oxide
and/or calcium hydroxide is added to the moist, disintegrated
fibrous material in such a way that at least a portion associates
itself with the water which is contained in the fibrous material.
The thus treated fibrous material is subsequently supplied,
preferably in a shear field with carbon dioxide.
[0008] A method which is based on and at the same time improves
upon the method described in the aforementioned U.S. patent
specification for loading of fibers contained in a suspension is
known, for example from the German disclosure document DE 102 04
254 A1. The fibers which are loaded with a precipitant are ground
in order to produce precipitant product particles having maximum
dimensions in the range of approximately 0.05 to approximately 5
.mu.m, wherein the creation of the crystalline precipitant product
particles occurs in an online process in the stock preparation
line.
[0009] In addition a method and an apparatus for loading fibers
which are contained in a suspension with a filler by way of a
chemical precipitation method are known from the German disclosure
document DE 101 07 448 A1. In this scenario the suspension
containing the fibers is fed into a pump disperger and is treated
in said disperger with shear forces in order to break larger fiber
agglomerates into smaller ones or even into individual fibers. At
the same time the pump disperger is used as a reactor for the
chemical precipitation reaction.
[0010] In addition a method for the production of cellulose for
subsequent use in the production of a fibrous web, especially a
paper or cardboard web is known from the German disclosure document
DE 101 20 526 A1. The cellulose obtained in a cellulose production
process is initially loaded with an additive through a chemical
precipitation reaction, preferably in accordance with the already
mentioned U.S. patent document U.S. Pat. No. 5,223,090. The already
loaded cellulose is then dried and made available for subsequent
use or shipment.
[0011] The methods described in the current state of the art all
distinguish themselves in that the milk of lime [CA(OH).sub.2;
slaked lime suspended in water; unslaked lime; lime hydrate, slaked
lime], or the slaked lime is initially brought into contact, or in
other words is mixed with the fibers or the cellulose contained in
the suspension and characterized in that the carbon dioxide is then
added when the chemical precipitation reaction is triggered.
[0012] The disadvantage of these cited methods consists especially
in that they offer only a low degree of effectiveness since the
milk of lime or the slaked lime, cover the surfaces of the fibers
or the cellulose, thereby blocking access of the carbon dioxide.
The chemical precipitation reaction on the surfaces becomes
possible only after the supplied carbon dioxide has penetrated the
layers of milk of lime or slaked lime. This impedes particularly a
loading of the interior fiber surfaces (lumen). Consequently only a
small portion of the precipitated calcium carbonate (PCC) is
adhered on the surfaces. The remaining calcium carbonate (PCC) is
free.
[0013] What is needed in the art is an improved method of the type
described at the beginning which, on the one hand assures a
chemical reaction that is as fast and as complete as possible and
on the other hand assures an efficient loading of the fiber
surfaces (inside and outside) or of the cellulose. In addition, an
improved apparatus of the type described at the beginning is needed
which permits the relevant chemical reaction to be carried out
continuously, efficiently and economically.
SUMMARY OF THE INVENTION
[0014] The present invention provides a method wherein carbon
dioxide is added to the fibers or the cellulose in the form of a
suspension, and the fibers or the cellulose in form of a suspension
to which carbon dioxide has been added are mixed with milk of lime
or slaked lime, such as in at least one reactor, thereby triggering
and extensively, such as completely, concluding the chemical
precipitation reaction.
[0015] Through the addition of carbon dioxide and by depositing it
on the fibers or on the cellulose material in form of a suspension
prior to adding milk of lime or slaked lime a chemical reaction
which is as complete and fast as possible can be achieved on the
one hand and an efficient loading of the fiber surfaces (inside and
outside) or of the cellulose on the other hand. When adding milk of
lime or slaked lime the chemical reaction occurs immediately,
thereby influencing the loading process very positively.
Integration to the greatest possible extent and encasement of the
fibers, inside as well as outside, or of the cellulose with calcium
carbonate is achieved.
[0016] In particular, the loaded cellulose can--as supported by the
already mentioned disclosure document DE 101 20 526
A1--subsequently be dried and be made available or prepared for
shipment for subsequent use. The cellulose material can be made
available for subsequent use or shipped in the form of bales, rolls
or the like. The cellulose itself can for example be manufactured
in accordance with the sulphate and/or sulphite method.
[0017] During the fiber loading process the milk of lime or the
slaked lime reacts to the introduction of carbon dioxide such, that
crystalline structures are formed.
[0018] The shape of the forming conglomerates can be influenced
partially by the volume of carbon dioxide and the speed of
introducing the carbon dioxide and by the system temperature and
possibly also substantially by the prevailing flow conditions. Two
basic types can be determined under the microscope: the rather rod
shaped or the flat or round shaped structures. The shape of the
structure is especially significant with certain specialty papers.
Cigarette paper, for example, requires rod-shaped structures in
order to guarantee the necessary opacity at a defined porosity.
[0019] There are at least two methods regarding process related
aspects: the carbon dioxide is added to the suspension in a unit
which is located upstream from the reactor in the process sequence
and which can be heated, or the carbon dioxide is added to the
suspension in the reactor where the blending of the suspension with
the milk of lime or the slaked lime can be staggered. Both methods
offer individual advantages.
[0020] In the first method the suspension receives a massive carbon
dioxide treatment prior to the chemical reaction. The fibers enrich
themselves with carbon dioxide on the inside and arrive practically
"pre-loaded" in the actual reaction vessel. The same applies of
course also to the cellulose. There, the calcium carbonate which is
being formed deposits itself around the respective surface of the
fibers or the cellulose. An additional improvement of the loading
process is also made possible by the inventive method characterized
in that the fibers or the cellulose themselves are "saturated" with
carbon dioxide. Regarding the pending precipitation reaction the
milk of lime or the slaked lime, therefore comes into contact
already with the surfaces which are activated by the educt carbon
dioxide. The precipitation reaction can therefore run its course in
a shorter period of time and, above all, completely. The first
method also permits continuous adding of the carbon dioxide and/or
continuous mixing with milk of lime or slaked lime.
[0021] The second method basically offers the same advantages,
however it is disadvantageous that the addition of the carbon
dioxide and the mixing process with the milk of lime or the slaked
lime can occur only in batch operation. The output volume in this
second method is therefore accordingly reduced wherein however
investment and even operational costs can be saved due to a
simplified system design.
[0022] Also, the first method offers a plurality of variations:
[0023] the carbon dioxide can be added to the suspension under the
influence of shear forces, such as in a pump disperger; [0024] the
carbon dioxide can be added to the suspension by utilizing mixing
effects, such as in a stationary mixing system, especially a
stationary mixer; [0025] the carbon dioxide can be added to the
suspension in at least one stationary mixer under the influence of
flow turbulences, wherein the flow turbulences may be utilized
during a possible injection of carbon dioxide into a supply line;
and/or [0026] the carbon dioxide can be added to the suspension by
utilizing at least one at least partially driven mixing system such
as in an agitator
[0027] All aforementioned design variations possess an exemplary
character and in addition distinguish themselves through a high
efficiency level regarding the chemical reaction.
[0028] With regard to the adjustment of an optimum consistency of
the suspension at a predetermined solids concentration, it can be
advantageous if water, for example fresh water and/or white water,
is added to the suspension prior to the addition of the carbon
dioxide. This allows the consistency of the suspension to be varied
within certain limits.
[0029] In addition it can also be advantageous if water, for
example fresh water or white water, is added into the reactor
itself prior to and/or during and/or after the addition of milk of
lime or slaked lime. This allows a subsequent adjustment of the
suspension's consistency.
[0030] Additional designs provide that the suspension is degassed
by way of at least one degassing unit prior to the addition of the
carbon dioxide and/or that the carbon dioxide is added to the
suspension under pressure. Both specified designs contribute
positively to a successful loading of the fibers or the cellulose
in the course of the chemical reaction.
[0031] The carbon dioxide can be added to the suspension as pure
carbon dioxide and/or as flue gas. The flue gas can be taken for
example from boilers or power plants. Both methods support the
loading process, wherein the utilization of flue gas is generally
probably more cost efficient.
[0032] Due to economic and ecological reasons the suspension is
produced by dissolving cellulose or waste paper with additives in
at least one pulper, or is supplied to the loading process as a
non-dried pulp which is also known as so-called "never dried pulp"
for example from another pulp mill.
[0033] In order to ensure that the loading process proceeds
reliably according to the method, the reaction parameters are
measured in at least one reactor and if necessary are utilized for
the control of the chemical precipitation reaction. The reaction
parameters which are relevant for a reliable and optimum process
progression include at least the pH-value, the temperature, the
dwell time, the throughput of suspension and/or milk of lime or
slaked lime. At least the pH-value of the suspension as measured at
the end of the reaction can be compared with a desired value and
any deviation is ideally reduced or removed through at least one of
the following correcting variables: addition of milk of lime or
slaked lime, addition of carbon dioxide, throughput of suspension
and/or the like.
[0034] The present invention also provides an apparatus for loading
of fibers or cellulose which are contained in a suspension with a
filler by way of a chemical precipitation reaction, wherein the
fibers or cellulose are provided in the form of a suspension having
a predetermined solids concentration. This apparatus is
characterized in that at least one reactor is provided in which the
fibers or the cellulose in form of a suspension to which carbon
dioxide has been added are mixed with milk of lime or slaked lime,
thereby triggering and extensively, such as completely, concluding
the chemical precipitation reaction.
[0035] The inventive method and the inventive apparatus can also be
applied in a suitable manner in the production of a fibrous web,
especially a paper or cardboard web, wherein at least fibers or
cellulose in the form of a suspension which were loaded according
to the inventive method were utilized for the production of said
web.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of embodiments of the invention taken
in conjunction with the accompanying drawings, wherein:
[0037] FIG. 1 is a schematic depiction of an apparatus for loading
fibers which are contained in a suspension with a filler by way of
a chemical precipitation reaction; and
[0038] FIG. 2 is a schematic depiction of an additional apparatus
for loading fibers which are contained in a suspension with a
filler by way of a chemical precipitation reaction.
[0039] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate embodiments of the invention, and such
exemplifications are not to be construed as limiting the scope of
the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0040] Referring now to the drawings, and more particularly to FIG.
1, there is shown a schematic depiction of a device 1 for loading
fibers 2.1 or cellulose 2.2 which are contained in a suspension 3
with a filler 4 by way of a chemical precipitation reaction,
wherein the fibers 2.1 or the cellulose 2.2 in form of a suspension
3 are made available with a pre-determined solids concentration
c.
[0041] The apparatus 1 includes reactor 5 in which the fibers 2.1
or the cellulose 2.2 in form of a suspension 3 to which carbon
dioxide 6 has been added are mixed with milk of lime or slaked lime
7, thereby triggering and extensively, such as completely,
concluding the chemical precipitation reaction. The carbon dioxide
6 can be added to the suspension 3 as pure carbon dioxide and/or as
flue gas.
[0042] In the example of apparatus 1 depicted in FIG. 1 the
addition of the carbon dioxide 6 and mixing of the milk of lime or
slaked lime 7 occurs in batch operation.
[0043] The reactor 5 includes at least one supply line 8 for carbon
dioxide 6 so that the carbon dioxide 6 can be supplied to the
fibers 2.1 or to the cellulose 2.2 in form of a suspension 3 prior
to and/or at the same time as the milk of lime or the slaked lime 7
is supplied via a line 9. The filler 4 in this scenario is calcium
carbonate.
[0044] In addition a supply line 11 is provided for water 10 which
can be added prior to the addition of carbon dioxide and/or prior
to and/or during and/or after the addition of milk of lime or
slaked lime 7.
[0045] In addition, a degassing unit 12 for the purpose of
degassing the suspension 3 prior to adding of the carbon dioxide 6,
as well as a pressure generating unit 13 for the purpose of a
pressurized addition of carbon dioxide 6 to the suspension 3, are
provided. The known and purely schematically depicted degassing
unit 12 is connected to the reactor 5 by way of a line 14 whereas
the known and also purely schematically depicted pressure
generating unit 13 is connected to the reactor 5 via the already
present line 8.
[0046] A pulper 15 which is known in the state of the art is
provided in order to produce the suspension 3 by way of dissolving
cellulose or waste paper through the use of additives. The
production of the suspension 3 can of course also occur through a
supply of non-dried pulp.
[0047] In addition, the reactor 5 includes at least one system 16
to measure the reaction parameter and if necessary to adjust the
chemical precipitation reaction. The relevant reaction parameters
include at least the pH-value, the temperature, the dwell time, the
throughput of suspension and/or milk of lime or slaked lime. A
system of this type 16 including measuring devices and actuators or
control elements are generally known and are therefore indicated
merely exemplary.
[0048] In the implementation of the inventive method the reaction
parameters can be in the following value ranges: pH-value of the
suspension in the reactor between 6 and 11, preferably between 7
and 10; temperature of the suspension in the reactor between
approximately -15 and approximately 120.degree. C., preferably
between approximately 20 and approximately 90.degree. C.; dwell
time of the suspension in the reactor between 0.5 minutes and
approximately 4 hours, preferably between 3 minutes and
approximately 1 hour.
[0049] The throughput of the suspension and/or the milk of lime or
slaked lime depends substantially upon the size of the reactor and
cannot therefore be easily quantified.
[0050] FIG. 2 illustrates a schematic depiction of an additional
apparatus 1 for loading fibers 2.1 or cellulose 2.2 which are
contained in a suspension 3 with a filler 4 by way of a chemical
precipitation reaction.
[0051] This device 1 is essentially based on the apparatus
described in FIG. 1, so that reference is made to said apparatus
regarding basic components and their description.
[0052] The apparatus 1 also includes a reactor 5 in which the
fibers 2.1 or the cellulose 2.2 in form of a suspension 3 are mixed
with milk or lime or slaked lime 7 thereby triggering and largely,
such as completely, concluding the chemical precipitation reaction.
A supply line 9 is provided for the addition of milk of lime or
slaked lime 7 into the reactor.
[0053] In contrast to the embodiment in FIG. 1, this example
includes a unit 17 which is located upstream from the reactor 5 in
the process sequence and which can be heated and in which carbon
dioxide 6 is added to the fibers 2.1 or to the cellulose 2.2 in
form of a suspension. For this purpose the unit 17 includes at
least one supply line 8 for carbon dioxide 6. The possible heating
of the unit 17 in a known manner allows for a direct influence upon
the reaction temperature of the subsequent chemical reaction.
[0054] The carbon dioxide 6 can be added to the suspension 3 as
pure carbon dioxide and/or as flue gas. The filler in this instance
is then calcium carbonate.
[0055] In the example of the apparatus 1 in FIG. 2, the addition of
the carbon dioxide 6 and mixing with the milk of lime or slaked
lime 7 therefore occurs continuously.
[0056] The unit 17 which is located upstream from the reactor 5 in
the process sequence includes at least one pump disperger 18 which
produces shear forces during the addition of carbon dioxide 6 to
the suspension 3 via the at least one supply line 8. A pump
disperger 18 of this type is constructively and functionally
already cited for example in the German disclosure document DE 101
07 448 A1. The content of said document is therefore included into
the present description by way of reference.
[0057] In an additional arrangement the unit 17 which is located
upstream from the reactor 5 in the process sequence can also
include at least one stationary mixing system--for example a
stationary mixer or a supply line through which the suspension
flows--which causes mixing effects during the addition of the
carbon dioxide to the suspension. In addition it can also include
at least a partially driven mixing system, for example an agitator,
which produces mixing effects while the carbon dioxide is added to
the suspension. Such arrangements are well known to the expert so
that there is no need for a detailed description.
[0058] The apparatus 1 also includes a degassing unit 12 for the
purpose of degassing the suspension 3 prior to the addition of the
carbon dioxide 6, as well as a pressure generating unit 13 for the
purpose of a pressurized addition of carbon dioxide 6 to the
suspension 3. The known and purely schematically depicted degassing
unit 12 is connected to the reactor 5 by way of a line 14, whereas
the known and also purely schematically depicted pressure
generating unit 13 is connected to the reactor 5 via the already
present line 8.
[0059] A pulper 15 which is known in the state of the art is
provided in order to produce the suspension 3 by way of dissolving
cellulose or waste paper through the use of additives. The
production of the suspension 3 can of course also occur through a
supply of non-dried pulp.
[0060] In addition, the reactor 5 again includes at least one
system 16 to measure the reaction parameter and to possibly make
adjustments to the chemical precipitation reaction. The relevant
reaction parameters include at least the pH-value, the temperature,
the dwell time, the throughput of suspension and/or milk of lime or
slaked lime. A system of this type 16 including measuring devices
and actuators or control elements are generally known and are
therefore indicated merely as an example.
[0061] The apparatus 1 therefore is ideally suited for the
production of a fibrous web in the production of which at least
fibers 2.1 or cellulose 2.2 in the form of at least one suspension
3 were used which were loaded in accordance with the inventive
method while utilizing the inventive apparatus 1.
[0062] In conclusion it can be said that an improved method as well
as an improved apparatus of the type described at the beginning are
provided by the current invention which, on the one hand assures a
fast and an as complete as possible chemical reaction and on the
other hand assures an efficient loading of the fiber surfaces
(inside and outside) or of the cellulose.
[0063] While this invention has been described with respect to at
least one embodiment, the present invention can be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains and which fall within the limits of
the appended claims.
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