U.S. patent application number 10/528025 was filed with the patent office on 2006-06-15 for process and arrangement for replacing intra-fiber liquid in fibers with a replacement liquid.
Invention is credited to Tommy Iversen, Mikaei Lindstrom, Marco Lucisano, Asa Samuelsson, Birger Sjogren, Lars Sjostrom, Hannes Vomhoff.
Application Number | 20060124259 10/528025 |
Document ID | / |
Family ID | 20288995 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060124259 |
Kind Code |
A1 |
Samuelsson; Asa ; et
al. |
June 15, 2006 |
Process and arrangement for replacing intra-fiber liquid in fibers
with a replacement liquid
Abstract
A process and apparatus for replacing intra-fiber liquid in
fibers by a replacement liquid, includes compressing the fiber cake
to express a substantial quantity of intra-fiber liquid to the
space between the fibers; forcibly supplying replacement liquid to
the fiber cake during the compression thereby replacing the
intra-fiber liquid from the space between the fibers and letting
the fibers expand while supplying additional replacement liquid.
The invention gets rid of or significantly reduces the content of
contaminating material in not only the areas between the fibers in
a fiber cake but also in the fiber wall pores and the lumen and
replaces this liquid by a replacement liquid.
Inventors: |
Samuelsson; Asa; (Stockholm,
SE) ; Sjogren; Birger; (Haninge, SE) ;
Vomhoff; Hannes; (Taby, SE) ; Sjostrom; Lars;
(Tyreso, SE) ; Lucisano; Marco; (Stockholm,
SE) ; Lindstrom; Mikaei; (Saltsjo-Duvnas, SE)
; Iversen; Tommy; (Djursholm, DE) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET
2ND FLOOR
ARLINGTON
VA
22202
US
|
Family ID: |
20288995 |
Appl. No.: |
10/528025 |
Filed: |
September 16, 2003 |
PCT Filed: |
September 16, 2003 |
PCT NO: |
PCT/SE03/01443 |
371 Date: |
October 6, 2005 |
Current U.S.
Class: |
162/60 ; 100/125;
19/200; 210/767; 68/21 |
Current CPC
Class: |
D21C 9/10 20130101; D21C
9/007 20130101; D21C 9/06 20130101 |
Class at
Publication: |
162/060 ;
210/767; 068/021; 100/125; 019/200 |
International
Class: |
D21C 9/02 20060101
D21C009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 2002 |
SE |
0202733-2 |
Claims
1-18. (canceled)
19. Process for replacing liquid inside the fiber walls with a
replacement liquid adapted to modify the properties of the fibers,
comprising the following steps; compressing a fiber cake to such a
degree that a substantial quantity of the liquid inside the fiber
walls is expressed into the space between the fibers and partially
out of the fiber cake, forcibly supplying the replacement liquid to
the fiber cake during the compression into the space between the
fibers and thus displacing the original liquid inside the fiber
walls from the space between the fibers and letting the fibers
expand while supplying additional replacement liquid which is thus
further absorbed by the expanding fibers.
20. Process according to claim 19, wherein the replacement liquid
contains chemical treating agent.
21. Process according to claim 19, wherein the replacement liquid
is acid or basic for fast acid or base treatment of the pulp
fibers.
22. Process according to claim 19, wherein the replacement liquid
contains bleaching chemical.
23. Process according to claim 19, wherein the replacement liquid
contains delignifying agent.
24. Process according to claim 19, wherein the replacement liquid
contains process catalyst.
25. Process according to claim 19, wherein the replacement liquid
contains chelating agent.
26. Process according to claim 19, wherein the replacement liquid
contains fluorescent tracer.
27. Process according to claim 19, wherein the replacement liquid
contains metal ions.
28. Process according to claim 19, wherein the replacement liquid
contains cationic or anionic polymer.
29. Process according to claim 19, wherein the replacement liquid
contains dyeing substance.
30. Process according to claim 19, wherein the replacement liquid
contains inorganic substance.
31. Arrangement for replacing liquid inside fiber walls with a
replacement liquid comprising a device (1,4,4a,5,5a) for
compressing a fiber cake in such a degree that a substantial
quantity of liquid inside the fiber walls is expressed to the space
between the fibers and partially out of the fiber cake, a first
device (6,8,9) for forcibly supplying the replacement liquid to the
fiber cake during the compression and a second device (7,14) for
supplying the additional replacement liquid immediately after the
device for compression arranged in an expansion area where the
fibers are allowed to expand after the compression while absorbing
the replacement liquid.
32. Arrangement according to claim 31, wherein the device for
compressing the fiber cake (1,4,5) comprises a rotating compression
roll (4) and a press (5) arranged opposite the compression roll (4)
with a press nip in which the fibers are fed and the device (6) for
forcibly supplying the replacement liquid to the fibers during the
compression is a compressible fabric (6) with liquid permeability
only in the thickness direction arranged as a moving closed loop in
at least partly contact with the compression roll (4) where at
least a part of the closed loop in the press nip is in contact with
the compressed fibers and a device (7,14) for supplying replacement
liquid to the compressible fabric (6).
33. Arrangement according to claim 31, wherein the device for
compressing the fiber cake (1,4,5) comprises a rotating compression
roll (4a) and a press (5a) arranged opposite the compression roll
(4a) with a press nip in which the fibers are fed and the device
(8,9) for forcibly supplying the replacement liquid to the fibers
during the compression comprises radial holes (8) in the
compression roll (4a) and a pressurized replacement liquid
container (9) arranged in the compression area to supply
pressurized replacement liquid through the holes (8) from the
inside of the compression roll (4a) into the fibers in the
compression area.
34. Arrangement according to claim 32, wherein the second device
(7) supplying the replacement liquid is a trough with its bottom
opening (13) just after the press nip.
35. Arrangement according to claim 32, wherein the second device
(14) supplying the replacement liquid is a replacement liquid
reservoir defined by a part of the interior of the closed loop of
the compressible fabric (6) and a part of the envelope surface of
the compression roll (4)
36. Arrangement according to claim 35, wherein the replacement
liquid reservoir (14) is arranged just before the closed loop goes
into contact with the compression roll (4).
37. Arrangement according to claim 35, wherein the replacement
liquid reservoir is arranged after the closed loop leaves contact
with the compression roll.
38. System characterized in that it comprises more than one
arrangement according to claim 31, in series.
39. Arrangement according to claim 31, wherein the replacement
liquid is cleaner liquid.
40. Arrangement according to claim 31, wherein the replacement
liquid contains chemical treating agent.
41. Arrangement according to claim 31, wherein the replacement
liquid is acid or basic for fast acid or base treatment of the pulp
fibers.
42. Arrangement according to claim 31, wherein the replacement
liquid contains bleaching chemical.
43. Arrangement according to claim 31, wherein the replacement
liquid contains delignifying agent.
44. Arrangement according to claim 31, wherein the replacement
liquid contains process catalyst.
45. Arrangement according to claim 31, wherein the replacement
liquid contains chelating agent.
46. Arrangement according to claim 31, wherein the replacement
liquid contains fluorescent tracer.
47. Arrangement according to claim 31, wherein the replacement
liquid contains metal ions.
48. Arrangement according to claim 31, wherein the replacement
liquid contains cationic or anionic polymer.
49. Arrangement according to claim 31, wherein the replacement
liquid contains dyeing substance.
50. Arrangement according to claim 31, wherein the replacement
liquid contains inorganic substance.
Description
[0001] The present invention is generally directed to a process and
an arrangement for replacing intra-fiber liquid in fibers with a
replacement liquid.
BACKGROUND OF THE INVENTION
[0002] It is well known that cooked or digested materials such as
wood pulp fibers or textile fibers such as cotton fibers and other
fibers with pores in their fiber walls, are containing various
chemicals or substances that are less desirable or eligible. To get
rid of or at least lessen their contents various methods of washing
fibers have been used.
[0003] The original method used for fiber washing is
dilution-extraction. It consists of diluting a fiber slurry with a
weaker liquid and subsequently thicken it and raising the
consistency.
[0004] Diffusion has also been used for washing fibers where wash
liquid is mixed with the fibers and at some time later, up to a few
hours, is displaced.
[0005] Vacuum washers have also been used where the liquid content
of the fibers are extracted by an applied vacuum while being
subsequently replaced by a wash liquid.
[0006] Another method is by using pressure washers. The principle
is to apply mechanical pressure on the fiber cake using screws,
rolls or a horizontal belt or the like. The thickness of the fiber
cake is gradually reduced and the liquid is expressed.
[0007] Due to their special nature, fibers also contain liquid
inside the fiber wall and also in the lumen. This liquid is
henceforward called intra-fiber liquid. So far, the methods used to
eliminate the liquid in fiber cakes have only aimed to substitute
the liquid contained in pores between the fibers, henceforward
called inter-fiber liquid, and not the substantial amount of
intra-fiber liquid. To get rid of a substantial amount of the
intra-fiber liquid very high pressures are needed. A desired
consistency is well over 40%. This level is usually depending on
the type of fiber used. In the state of art sufficiently high
pressures have for different reasons not been used. High energy
consumption and excessive stress in the machinery used are probable
reasons. This has also led to that the liquid in the fiber wall
pores and lumen have not been the object of attention for the
professionals in the field. With today's technology it is however
possible to build washers which manage high strain without
breaking. Since the content of contamination such as lignin
fragments in the fiber wall is so significant there is much to gain
to get rid of this content or at least significantly reduce it.
This will provide a pulp of higher and more uniform quality.
[0008] Thus it is an object of the present invention to get rid of
or significantly reduce the content of contaminating material not
only in the area between the fibers in a fiber cake made of
cellulosic, textile, or other fibers, but also in the fiber wall
pores and inside the lumen and replace this liquid with a
replacement liquid.
[0009] This is achieved according to the present invention by a
process having the following steps; compressing the fiber cake to
such a degree that a substantial quantity of the intra-fiber liquid
is expressed into the space between the fibers and partially out of
the fiber cake, forcibly supplying the replacement liquid to the
fiber cake during the compression into the space between the fibers
and thus removing the intra-fiber liquid from the space between the
fibers, and letting the fibers expand while supplying additional
replacement liquid which is thus further absorbed by the expanding
fibers.
[0010] It is in another preferred embodiment of the invention
suggested that the replacement liquid is cleaner liquid.
[0011] In many cases it is interesting to further treat the fibers
with different substances. To introduce them into not only the area
between the fibers but also in the fiber wall and lumen would be a
great advantage as it will provide a pulp fibers of higher and more
uniform quality and fiber properties previously not possible.
[0012] Thus it is also an object of a preferred embodiment of the
present invention to introduce substances for treatment of the
fibers not only into the area between the fibers in cellulosic,
textile or the like fibers but also into the fiber wall and
lumen.
[0013] It is in another preferred embodiment of the invention thus
suggested that the replacement liquid contains chemical treating
agent.
[0014] It is in another preferred embodiment of the invention
suggested that the replacement liquid is acid or basic for fast
acid or base treatment of the pulp fibers.
[0015] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains bleaching
chemical.
[0016] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains delignifying
agent.
[0017] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains process
catalyst.
[0018] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains chelating agent.
[0019] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains fluorescent
tracer.
[0020] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains metal ions. 5 It is
in another preferred embodiment of the invention suggested that the
replacement liquid contains cationic or anionic polymer.
[0021] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains dying substance to
dye the fibers.
[0022] It is in another preferred embodiment of the invention
suggested that the replacement liquid contains inorganic
substance.
[0023] The object is also achieved according to the present
invention by an arrangement comprising a device for compressing the
fiber cake to such a degree that a substantial quantity of
intra-fiber liquid is expressed to the space between the fibers and
partially out of the fiber cake, a first device for forcibly
supplying the replacement liquid to the fibers during the
compression and a second device for supplying the replacement
liquid immediately after the device for compression arranged in an
expansion area where the fibers are allowed to expand after the
compression while absorbing the replacement liquid.
[0024] It is in another preferred embodiment of the invention
suggested that the device for compressing the fibers comprises a
rotating compression roll and a press arranged opposite the
compression roll with a press nip in which the fibers are fed and
the device for forcibly supplying the replacement liquid to the
fibers during the compression is a compressible fabric with liquid
permeability only in the thickness direction arranged as a moving
closed loop in at least partly contact with the compression roll
where at least a part of the closed loop in the press nip is in
contact with the compressed fibers.
[0025] It is in another preferred embodiment of the invention
suggested that the device for compressing the fibers comprises a
rotating compression roll and a press arranged opposite the
compression roll with a press nip in which the fibers are fed and
the device for forcibly supplying the replacement liquid to the
fibers during the compression comprises radial holes in the
compression roll and a pressurized replacement liquid container
arranged in the compression area to supply pressurized replacement
liquid through the holes from the inside of the compression roll
into the fibers in the compression area.
[0026] It is in another preferred embodiment of the invention
suggested that the second device supplying the replacement liquid
is a trough which has a lower opening at an outlet from the device
for compressing the fibers.
[0027] It is in another preferred embodiment of the invention
suggested a system where more than one arrangement are arranged in
series.
[0028] It needs to be mentioned that the word liquid in this
application should be interpreted rather broad and not only mean
liquids as such. Thus it is our meaning that it also should include
suspensions, dispersions and the like.
[0029] Above and other objects of the present invention will appear
from the following description of species or forms of embodiment,
and from the accompanying drawings.
[0030] In the drawings
[0031] FIG. 1 is a schematic side view of an arrangement according
to the present invention;
[0032] FIG. 2 is a schematic side view of a second embodiment of an
arrangement according to the present invention;
[0033] FIG. 3 is a schematic side view of a third embodiment of an
arrangement according to the present invention;
[0034] FIG. 4 is a schematic side view of a fourth embodiment of an
arrangement according to the present invention;
[0035] FIG. 5 is a view of part of the embodiment showed in FIG.
4;
[0036] FIG. 6 is a graph showing the intra-fiber and inter-fiber
liquid content of fibers as a function of the compression
pressure;
[0037] FIG. 7 is a schematic flow chart of the process of the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0038] FIG. 7 is illustrating a process according to the invention
having the following steps; compressing a fiber cake to such a
degree that a substantial quantity of the contaminated intra-fiber
liquid is expressed to the space between the fibers and partially
out of the fiber cake. At the same time a replacement liquid is
forcibly supplied to the fiber cake during the compression and
displacing the intra-fiber liquid from the space between the
fibers. This means that the residual contaminated liquid is greatly
diluted and getting even more so when in an expansion phase the
fibers expand while supplying additional replacement liquid which
liquid is thus further absorbed by the expanding fibers. The whole
process means that an exchange or replacement has taken place where
the replacement liquid has replaced the contaminated liquid not
altogether but in such a degree that the content of the contaminant
in the treated fibers is diluted in a high degree.
[0039] According to FIG. 1, a device according to the present
invention generally comprises a belt or wire 1 on which a fiber
cake 12 is transported along a predestinated route by motor-driven
transport rolls 2 and 3 arranged in parallel with and on each side
of a compression roll 4. The compression roll 4 is directly or
indirectly driven by a motor. The compression of the fibers takes
place between the rotating compression roll 4, which is
transversally arranged on the side of the wire 1 where the fibers
are placed, and a shoe or roll press 5 arranged on the opposite
side of the wire 1 from the compression roll 4 in such a manner
that a press nip results where the fibers are compressed and
deliquefied. The compression is among other things depending upon
how close the compression roll 4 and the press 5 are to each other,
i.e. the size of the press nip. Since the compression roll 4 is
arranged slightly lower than the transport rolls 2, 3, the wire 1
with the fiber cake is wrapped along a section of the compression
roll 4. Due to this roll wrap there is some deliquefying of the
fibers before the main compression area which is the press nip
between the compression roll 4 and the press 5. A compressible
fabric 6 is arranged as a closed loop on the envelope surface of
the compression roll 4 to be rotated together with the roll 4
between it and the fiber cake. The fabric 6 is permeable to liquid
by way of pores arranged in its thickness direction resulting in a
permeability in the thickness direction exclusively. Immediately
after the oppositely arranged compression roll 4 and the press 5 a
replacement liquid trough 7 is arranged. The trough 7 has a lower
opening in its bottom through which the compressible fabric 6 is
transported and thus being compressed expands and sucks up
replacement liquid. This "liquid filled" area of the compressible
fabric is then by way of the rotation of the compression roll 4
transported to the beginning of the roll wrap area and further on
to the compression area again where the replacement liquid is
pressed out of the pores and into the fiber cake. The replacement
liquid is thus displacing the contaminated liquid and at the same
time starting to be absorbed by the fiber wall pores and the lumens
by way of convection. The wire 1 with the compressed fibers is
transported through the lower opening 13 of the trough 7 just after
the compression roll 4 and being relieved from the compression
pressure, the fibers expand while sucking up even more of the
replacement liquid from the trough 7. This expansion phase reduces
the concentration of the contamination in the fiber cake both
between the fibers and in the fiber wall and lumen as the
replacement liquid eventually finds its way there through
diffusion. The expansion of the fiber cake usually takes more than
0.5 seconds. To maximally make use of this time it is preferred if
the time the fiber cake is in contact with the replacement liquid
in the trough is more than 0.5 seconds. To further reduce the
contamination content in the fiber cake a second step or even more
steps, of this compression-expansion process could be used in which
two or more arrangements according to the invention are arranged in
series. This would make it possible to further process the fibers
supplying different kinds of replacement liquids for different
purposes such as washing, bleaching and so on in a system.
Suggestions as to what kinds of replacement liquids are possible to
use are made later in this description.
[0040] FIGS. 2 and 3 disclose embodiments of the present invention
similar to the embodiment showed in FIG. 1. In these embodiments
the trough 7 is substituted by a replacement liquid reservoir 14
defined by a part of the interior of the closed loop of the
compressible fabric 6 and a part the envelope surface of the
compression roll 4. This reservoir 14 is in FIG. 2 arranged just
before the closed loop goes into contact with the compression roll
4 and in FIG. 3 after the closed loop leaves contact with the
compression roll 4. The replacement liquid is added to the inside
of the closed loop. This arrangement has the advantage that the
pores of the compressible fabric 6 are filled from the inside,
preventing the occurrence of air in the pores which would hinder
the flow out of the pores in the compression phase.
[0041] A further improvement in these embodiments is a second
reservoir 16 defined by a part of the exterior of the closed loop
of the compressible fabric 6 and a flow restrictor 15 which forms a
narrow slit with the fabric in the bottommost part of the reservoir
14. The flow restrictor collects the liquid that flows through the
compressible fabric 6 and avoids unnecessary flow of replacement
liquid. This second reservoir 16 is in the embodiment of FIG. 2
arranged just before the closed loop goes into contact with the
compression roll 4 and in FIG. 3 after the closed loop leaves
contact with the compression roll 4. Even though it is not shown in
the figures it is of course possible to include a trough 7 in these
embodiments just like the trough 7 in the embodiment shown in FIG.
1.
[0042] In a different embodiment of the invention according to
FIGS. 4 and 5 the compression roll 4 is substituted for a
compression roll 4a which is formed as a roll shell with radial
holes 8 in the same manner as in the compressible fabric 6 in the
first embodiment. The compressible fabric is in this way
superfluous. A pressurized replacement liquid container 9 supplies
the liquid to the compressed fiber cake in the compression area in
the press nip while the replacement liquid trough 7 is still
present to supply liquid during the expansion phase. The press 5a
can in this case also be of a shoe press or roll press type.
Indicated in FIGS. 2 and 3 are a shoe press comprising an
impermeable shoe press belt 10. The belt 10 is moving through the
container 9 at the same speed as the compression roll 4a. In the
compression area the belt 10 is on the side not in contact with the
wire 1 influenced by a support pressure and thus acting as a
counter support for the forces applied by the compression roll 4a
while also balancing pressure from the pressurized replacement
liquid container 9 on the compression roll 4a. This support
pressure is in this embodiment supplied by a pressurized liquid,
preferably hydraulic oil, in a chamber 11 closed by the belt
10.
[0043] The liquid in the replacement liquid trough 7 and supplied
by the first device for forcibly supplying the replacement liquid
is usually cleaner liquid but can in yet another alternative
embodiment of the invention contain chemical treating agents. Such
treating agents can be acid or basic liquid for the acid or base
treatment of the fibers, inorganic substances, bleaching chemicals,
process catalysts, chelating agents, tracer substances such as
fluorescent substances, metal ions for substituting e.g. Ca-ions in
the fibers for Na-- or Mg-ions, and cationic polymers to prevent
release of anionic substances from the fibers or anionic polymers
to get a bulking effect on the fibers (including native
polymers).
[0044] FIG. 6 discloses a graph showing the intra-fiber liquid and
inter-fiber liquid content of fibers as a function of the
compression pressure. The graph is taken from Laivins, G. V.,
Scallan, A. M. (1993): "Removal of water from pulps by
pressing--Part 1: Inter- and Intra-wall water", Tappi Engineering
Conference, 741-747 and clearly shows that the instant effect on
the content when a pressure is applied mostly influence the
inter-fiber content. At between 0.5 and 1.0 MPa the removed
intra-fiber liquid is finally becoming dominant over the
inter-fiber liquid. This usually corresponds to a dryness
(consistency) of between 30 and 40%. The real impact of the
compression on the liquid content in the fiber wall is thus only
obvious at higher pressures or dryness percentages.
[0045] The operation of the described device is henceforward
explained (see FIG. 7). Fibers with contaminants are fed onto the
belt or wire 1 as a fiber cake. The wire 1 with the fiber cake is
transported by the transport rolls 2 and 3 preferably as a
continuous conveyor. When the wire 1 and the fiber cake are coming
into contact with the compression roll 4 with the fabric 6 the
fiber cake is thus pre-deliquefied somewhat by the roll wrap caused
by the endless wire 1 and fiber cake being wrapped around a sector
of the compression roll 4. The fiber cake is thereafter transported
into the main compression area of the press nip between the
compression roll 4 and the press 5. There liquid is pressed out of
the fibers and the fiber wall pores and fiber lumens and partially
out of the fiber cake. At the same time the fabric 6 is compressed
and replacement liquid in its pores is pressed out and to a large
extent is pressed through the fiber cake. This means that the fiber
cake during the compression at the same time is fed replacement
liquid that washes through it and displaces the contaminated liquid
between the fibers released from the fiber walls. The press nip is
such that the compression corresponds to a consistency of well over
40%, preferably over 50% at which a substantial amount of the
intra-fiber liquid is removed. As soon as the fiber cake has passed
the press nip it is transported through the opening in the bottom
of the replacement liquid trough 7. Since the pressure on the fiber
cake 12 is released, the fibers expand and absorb additional
replacement liquid.
* * * * *