U.S. patent application number 11/887325 was filed with the patent office on 2009-10-01 for paper machine, especially a tissue paper machine.
This patent application is currently assigned to SCA Hygiene Products GmbH. Invention is credited to Bruno Dexler, Josef Heintz, Martin Wiens.
Application Number | 20090242157 11/887325 |
Document ID | / |
Family ID | 34963103 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090242157 |
Kind Code |
A1 |
Heintz; Josef ; et
al. |
October 1, 2009 |
Paper Machine, Especially a Tissue Paper Machine
Abstract
In a tissue paper making machine downstream the yankee-cylinder
(9) and upstream the tambour roll (14) a spark detector (13) is
provided in the vicinity of the paper web running to the winding-up
section (4) in order to detect sparks of glowing fibers or fiber
conglomerates, which can be enrailed by the high speed run of the
paper web and can be transferred to the paper roll (15) where the
sparks are trapped between the paper web windings of the paper
mill. Knowledge of this fact offers the possibility to avoid fire
in the mother-roll storage.
Inventors: |
Heintz; Josef; (Kirrweiler,
DE) ; Wiens; Martin; (Heidelberg, DE) ;
Dexler; Bruno; (Burstadt, DE) |
Correspondence
Address: |
YOUNG & THOMPSON
209 Madison Street, Suite 500
ALEXANDRIA
VA
22314
US
|
Assignee: |
SCA Hygiene Products GmbH
Mannheim
DE
|
Family ID: |
34963103 |
Appl. No.: |
11/887325 |
Filed: |
April 1, 2005 |
PCT Filed: |
April 1, 2005 |
PCT NO: |
PCT/EP2005/003449 |
371 Date: |
November 9, 2007 |
Current U.S.
Class: |
162/263 |
Current CPC
Class: |
D21F 11/145 20130101;
D21G 9/0063 20130101; D21F 11/14 20130101; D21G 9/0009
20130101 |
Class at
Publication: |
162/263 |
International
Class: |
D21F 7/00 20060101
D21F007/00 |
Claims
1. Paper machine, especially tissue paper machine, comprising in
downstream direction at least one head box (1), at least one
forming section (2), at least one drying section (3) and downstream
of the most-downstream drying section a winding-up section (4)
including a winding-up roll (14) for forming a paper roll (mother
roll) (15), characterized in that behind the most downstream drying
section (3) or at least upstream the winding-up section (4) a spark
detector (13) is provided in the vicinity of the paper web (W)
running to the winding-up section (4).
2. Paper machine according to claim 1, characterized in that in a
tissue paper machine the spark detector (13) is provided downstream
the yankee cylinder (9).
3. Paper machine according to claim 1, characterized in that
cleaning air jet means (23) is provided, wherein the air jet
thereof is directed to the spark detector (13).
4. Paper machine according to claim 1, characterized in that the
spark detector (13) is combined with a web run-guiding means (18)
stabilising the web run.
5. Paper machine according to claim 4, characterized in that the
web run-guiding means (18) comprises at least one guiding surface
(20) behind which a space (21) is provided surrounded at least
partly by a casing (19), in which an air-inlet-opening (22) is
provided such that air sucked in by an under pressure created by
the web run is directed to the spark detector (13) for cleaning
purpose.
6. Paper machine according to claim 1, characterized in that the
spark detector (13) is provided downstream a web measuring means
(12).
7. Paper machine according to claim 2, characterized in that
cleaning air jet means (23) is provided, wherein the air jet
thereof is directed to the spark detector (13).
8. Paper machine according to claim 2, characterized in that the
spark detector (13) is combined with a web run-guiding means (18)
stabilising the web run.
9. Paper machine according to claim 3, characterized in that the
spark detector (13) is combined with a web run-guiding means (18)
stabilising the web run.
10. Paper machine according to claim 2, characterized in that the
spark detector (13) is provided downstream a web measuring means
(12).
11. Paper machine according to claim 3, characterized in that the
spark detector (13) is provided downstream a web measuring means
(12).
12. Paper machine according to claim 4, characterized in that the
spark detector (13) is provided downstream a web measuring means
(12).
13. Paper machine according to claim 5, characterized in that the
spark detector (13) is provided downstream a web measuring means
(12).
Description
TECHNICAL FIELD
[0001] The present invention relates to the technical field of
paper making and especially tissue paper making and the field of
the paper machine itself.
BACKGROUND ART
[0002] If tissue paper is to be made out of pulp, the process
essentially comprises [0003] a forming that includes the headbox
and the forming wire section, [0004] b the drying section (TAD
(through air drying)) or conventional drying on a yankee cylinder)
that also usually includes the crepe process essential for tissues,
[0005] c typically the monitoring and winding section.
[0006] Paper can be formed by placing the fibers, in an oriented or
random manner, on one or between two continuously revolving wires
of a paper making machine while simultaneously removing the main
quantity of water of dilution until dry-solids contents of usually
between 12 and 35% are obtained.
[0007] Drying the formed primary fibrous web occurs in one or more
steps by mechanical and thermal means until a final dry-solids
content of usually about 93 to 97%. In the case of tissue making,
this stage is followed by the crepe process which crucially
influences the properties of the finished tissue product in
conventional processes. The conventional dry crepe process involves
creping on a usually 4.5 to 6 m diameter drying cylinder, the
so-called yankee cylinder, by means of a crepe doctor with the
aforementioned final dry-solids content of the raw tissue paper
(wet creping can be used if lower demands are made of the tissue
quality). The creped, finally dry raw tissue paper (raw tissue) is
then available for further processing into the paper product or
tissue paper product according to the invention.
[0008] Instead of the conventional tissue making process described
above, the use of a modified technique is possible in which an
improvement in specific volume is achieved by a special kind of
drying within process section b and in this way an improvement in
the bulk softness of the thus made tissue paper is achieved. This
process, which exists in a variety of subtypes, is termed the TAD
(through air drying) technique. It is characterized by the fact
that the "primary" fibrous web (like a nonwoven) that leaves the
forming and sheet making stage is pre-dried to a dry-solids content
of about 80% before final contact drying on the yankee cylinder by
blowing hot air through the fibrous web. The fibrous web is
supported by an air-permeable wire or belt (or TAD-fabric) and
during its transport is guided over the surface of an air-permeable
rotating cylinder drum (TAD-cylinder). Structuring the supporting
wire or belt makes it possible to produce any pattern of compressed
zones broken up by deformation in the moist state, also named
moulding, resulting in increased mean specific volumes and
consequently leading to an increase in bulk softness without
decisively decreasing the strength of the fibrous web. Such a
pattern is fixed in the area of the TAD-cylinder.
[0009] A tissue paper is defined as a soft absorbent paper having a
low basis weight. One generally selects a basis weight of 8 to 30
g/m.sup.2, especially 10 to 25 g/m.sup.2 per ply. The total basis
weight of multiple-ply tissue products is preferably equal to a
maximum of 65 g/m.sup.2, more preferably to a maximum of 50
g/m.sup.2. Its density is typically below 0.6 g/cm.sup.3,
preferably below 0.30 g/cm.sup.3 and more preferably between 0.08
and 0.20 g/cm.sup.3.
[0010] The production of tissue is distinguished from paper
production by the its extremely low basis weight and its much
higher tensile energy absorption index (see DIN EN 12625-4 and DIN
EN 12625-5). Paper and tissue paper also differ in general with
regard to the modulus of elasticity that characterizes the
stress-strain properties of these planar products as a material
parameter.
[0011] A tissue's high tensile energy absorption index results from
the outer or inner creping. The former is produced by compression
of the paper web adhering to a dry cylinder as a result of the
action of a crepe doctor or in the latter instance as a result of a
difference in speed between two wires ("fabrics"). This causes the
still moist, plastically deformable paper web to be internally
broken up by compression and shearing, thereby rendering it more
stretchable under load than an uncreped paper.
[0012] Moist tissue paper webs are usually dried by the so-called
Yankee drying or the through air drying (TAD).
[0013] The fibers contained in the tissue paper are mainly
cellulosic fibres, such as pulp fibers from chemical pulp (e.g.
Kraft sulfite and sulfate pulps), mechanical pulp (e.g. ground
wood), thermo mechanical pulp, chemo-mechanical pulp and/or
chemo-thermo mechanical pulp (CTMP). Pulps derived from both
deciduous (hardwood) and coniferous (softwood) can be used. The
fibers may also be or include recycled fibers, which may contain
any or all of the above categories. The fibers can be treated with
additives--e.g. softeners, such as quaternary ammonium compounds,
and binders, such as conventional dry-strength agents or
wet-strength agents used to facilitate the original paper making or
to adjust the properties thereof. The tissue paper may also contain
other types of fibers, e.g. regenerated cellulosic fibres or
synthetic fibers enhancing, for instance, strength, absorption,
smoothness or softness of the paper.
[0014] Tissue paper may be converted to the final tissue product in
many ways, for example, by embossing or laminating it into a
multi-ply product, rolled or folded. Such products may be paper
towels, paper napkins, paper handkerchiefs, facials etc.
DISCLOSURE OF INVENTION
[0015] The inventor recognized that by increase of environment
temperature in special areas of the paper machine especially behind
the most downstream drying section, e.g. yankee cylinder, sparks
from fibers or fiber conglomerations may be caused and by the high
speed web-run these sparks may be entrained and transported to the
winding section and are trapped between the winding layers of the
paper web and cause glowing fire nests within the paper roll
(mother roll). If this mother roll then is stored in a mother-roll
storage room and the glow within the mother roll develops to a fire
there is a high risk that fire destroys the whole content of the
storage.
[0016] It is the problem (object) of the present invention to avoid
this and to take care that such a disaster can be avoided.
[0017] This problem is solved by a paper making machine according
to claim 1 in which behind the most downstream drying section, or
at least upstream the winding-up section a spark detector is
provided in the vicinity of the paper web running to the winding-up
section.
[0018] If then the presence of sparks as described above is
detected by the detector there exists not only a possibility to
remove formation of the fiber sparks but to store the corresponding
mother roll separate from the mother roll storage in a safe area at
least for a safety while.
[0019] Preferably in a tissue paper machine the spark detector is
provided downstream the yankee cylinder where most probably sparks
may appear.
[0020] In order to avoid malfunction of the spark detector if
soiled by paper dust and other environment debris, cleaning air jet
means is provided, wherein the air jet thereof is directed to the
spark detector.
[0021] According to another possibility the spark detector is
combined with a web run-guiding means stabilising the web run.
There the spark detector is positioned close to the running paper
web so that sparks safely can be detected.
[0022] In order to avoid extra cleaning air jet means the web
run-guiding means comprises at least one guiding surface behind
which a space is provided surrounded at least partly by a casing,
in which an air-inlet-opening is provided such that air sucked in
by an under pressure created by the web run is directed to the
spark detector for cleaning purposes.
[0023] Nevertheless, this system may be combined with a cleaning
air jet means.
[0024] A preferred location for the spark detector is downstream a
web measuring means, where basis weight and water content of the
web is measured. This is a place where paper web-stabilisation can
be kept as short as possible and no other means has to be installed
there.
[0025] By the invention the spark detector remains clean and it is
not necessary to take care for special cleaning for which the
machine run would have to be interrupted. Anyway, in spite of the
presence of spark detector for instance between the yankee cylinder
and the winding-up section a good paper web stability is
maintained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 shows schematically an embodiment of a tissue paper
machine, and
[0027] FIG. 2 shows enlarged in comparison to FIG. 1 a paper web
guiding foil containing a spark detector.
EMBODIMENTS OF INVENTION
[0028] In FIG. 1 is schematically illustrated a tissue paper
machine comprising a headbox 1, a forming section 2 a drying
section 3 and a winding-up section 4. Reference number 5 denotes a
forming fabric and the reference number 6 downstream thereof a felt
guiding the paper web W from the forming section 2 to the drying
section 3. There is a pick-up roll 7 transferring the paper web
from the forming section 2 to the felt 6. Reference number 8
denotes a forming roll. In the drying section 3 is provided a
yankee-cylinder 9 partly surrounded by a drying hood 10. A creping
blade 11 removes the yankee-cylinder coated with a special chemical
agent from the circumferential surface of the yankee-cylinder. From
there the paper web W is guided to a measuring device 12 where for
instance the moisture content and the basis weight of the paper web
is measured. Behind, e.g. downstream the measuring device a spark
detector 13 is provided in the vicinity of the paper web, from
where the paper web is guided to the winding-up section where the
paper web is wound up a tissue tambour roll 14 forming from the
paper web a paper roll as a so-called mother-roll 15. Especially
such sparks may be present and created when fiber material possibly
combined with dust and paper lumps probably combined with the
chemical agent by which the yankee-cylinder is coated fill the
space between the dryer hood 10 and the yankee-cylinder 9. This
result in friction, which could cause higher temperatures leading
to the fiber sparks. The paper web W runs in FIG. 1 according to
arrow 16 from right to left.
[0029] The spark detector 13 is illustrated in more detail as one
embodiment in FIG. 2. It is not necessary to use a spark detector
in this way. The single spark detector may be placed anywhere
downstream the yankee-cylinder and upstream the tambour 14. It is
necessary to ensure that the detector is kept clean, which can be
done by a positive air jet directed to the detecting part 17 of the
spark detector 13.
[0030] In the special embodiment illustrated in FIG. 2 the spark
detector 13 is combined with a paper web run-guiding device (foil)
18 which comprises a closed casing 19 being provided with guiding
surfaces 20 for stabilising the high speed paper web run. Such
guiding means are used anyway in the paper making machine and it is
possible to form the guiding means in the manner illustrated in
FIG. 2 and combine the guiding device 18 with the spark detector
13. By the run of the paper web W along the guiding surfaces 20 a
sub pressure is created in the space 21 of the casing and via an
opening 22 in the vicinity of the spark detector 13 air is sucked
into the space 21 along the dotted lines in FIG. 2. Thus, the
sensing part 17 of the spark detector 13 is kept clean during the
operation of the paper machine so that the operation of the paper
machine has not to be interrupted for cleaning the spark detector
13. In this manner the spark detector 13 is disposed in the
vicinity of the paper web W and sparks of glowing fibers of fiber
conglomerations can be detected when being transported on top of
the paper web W and wound into the mother-roll 15.
[0031] Separately or in addition a positive air jet device 23 may
be provided in the wall 24 of the casing 19. The air jet is
directed to the sensing part 17 of the spark detector 13, which is
illustrated by the dotted line. The means for supply of air to this
device 23 is not illustrated and may be any known air supply
means.
[0032] In such a way it is not necessary to provide the spark
detector immediately upstream the tambour 14, where normally less
space is present because the distance between the yankee-cylinder 9
and the tambour shall be kept as short as possible for stabilising
the paper web.
[0033] When afore mentioned sparks are detected it is possible on
the one hand to stop the machine and to take care for cancelling
the creation of such sparks. On the other hand one knows that such
sparks were possibly trapped by the paper web windings in a
specific mother-roll and it is possible to separate this
mother-roll from the normal mother-roll storage in order to avoid a
big damage by fire within the mother-roll storage.
[0034] The casing 19 may be a simple, steel box as illustrated
schematically in FIG. 2.
* * * * *