Note: Descriptions are shown in the official language in which they were submitted.
t
~~~~~~.6
PULP MAKING DEVICE
Field Of Invention
This invention relates to the manufacture of pulps
from cellulosic materials like wood, waste papers and
non-wood plants, more particularly to the method for
making such pulps using a material feeding system and
the pressure of a liquid stream with or without
chemicals and temperatures.
Background Of Invention
(a) Prior and General State of the Art
Broadly speaking, pulps from wood and non-wood
plants containing mainly cellulosic materials such as '
fibres, and the glue-like binding material lignin are
made in 3 categories viz. mechanical., semi-chemical and
chemical. For making purely mechanical pulps such as
groundwood (GWD), pressurized groundwood (PGW), refiner
mechanical pulp (RMP), and thermo mechanical pulp (TMP)
grinders/refiners are used to defibre these materials by
brute force with or without temperature and atmospheric
pressure. F'or manufacturing semi-chemical pulps such as
chemi-mecYianical pulp (CMP), chemi-thermomechanical pulp
(CTMP), and ultra high yield sulphite (UHYS), and
1
~0~8~.~6
,:..
chemical pulps like kraft and sulphite, different
suitable chemicals are used under high temperature and
pressure (except for CMP). For making pulp out of waste
papers, normally pulpers are used with water and with or
without temperature and chemicals.
Higher temperature helps in mechanical defibering
of cellulosic materials by softening the lignin and/or
inter-fibre bonding. From wood both grinders and
refiners dislodge the fibres which are mostly oriented
along the length of the wood, at random basis i.e. not
necessarily along the length of the fibres. So a
substantial amount of fibres are cut, causing thereby
dower strength of the pulp in general. The presence of
high level of uncut and undamaged fibres in the pulp
stock is one of the prerequisites for making a strong
pulp. Softening temperature of dry lignin ranges from
127 -193 deg.C: Dry birch xylan and pine glucomannan
(both are hemicelluloses, another component of wood);
soften at 167 deg.C and 181 deg.C respectively.
However, sorption of water by lignin and hemicellulose
j
causes pronounced decrease of the softening temperature
- in some cases, to as low as 54 deg.C. Softening
points of both dry and moist lignins or hemicelluloses
have been shown to correlate with the temperature at
which the~sample develops adhesive properties. Sorbed ° ~.
water is considered to act as a low molecular weight
2
2~9~j~.~
diluent in plasticizing the polymer chains and lowering
the glass transition temperature at which a "plastic"
becomes tacky. Cellulose softens at temperatures greater
than 230 deg.C. In contrast to lignin and hemicellulose,
sorption of water by the Cellulose has negligible effect
on the softening temperature. The difference is
probably due to the crystalline nature of cellulose and
indicates that the water does not plasticise individual
cellulose chains at the molecular level - See D.A.I.
l0 Goring, in Consolidation of the Paper Web (F. Bolam,
Ed.), British Paper and Board Makers Association (1966),
pp. 555 - 575, "Thermal Softening, Adhesive Properties
and Glass Transitions In Lignin, Hemicellulose and
Cellulose".
Previous studies have indicated that both for
spruce, a softwood and birch, a hardwood there appears
to be 2 broad wood-softening gradual transition zones of
an S-curve viz. 20 - 70 deg.C and 120 - 180 deg.C - See
S. Lagergren et al:, Svensk Papperstidn. Vol. 60 (1957).
20 pp. 632 - 644, "Studies on the Interfibre Bonds of
Wood". So, even with water temperature at less than'100
deg.C good defiberization of the wood and also non-wood
plants can be achieved with suitably applied water jet
showers for pressure-application, lowering thereby the
overall cost of making pulps.
3
20~8~.~~
(b) Deficiencies Of the Prior Art
The pulp and paper industry generally uses
equipments like, and systems for refiners, grinders, .
digesters and pulpers to make pulps. These types have
the disadvantage of being expensive because of not only
high capital cost but also for the high consumption of
power, heat and chemicals (where applicable) under
pressurized and non-pressurized conditions. Moreover,
for the production of each kind of mechanical, semi-
1.0 chemical, chemical or waste paper pulp different kind of
initial pulping/defibering equipments are needed.
i
Another device for the disintegration of wood
subjects; inside a drum, the body of wood to liquid jet
at a delivery pressure of from about 4,000 psi to about
60,000 psi as described and illustrated in United States
Patent No. 4,723,715, dated Feb. 9, 1988, and in
Canadian Patent No. 1 246 375, dated Dec. l3, 1988,
both granted to Mazurkiewich for "Disintegration Of
Wood". This device has several disadvantages. While this
j 20 can disintegrate the wood by water jet pressure; it uses
ver hi h ressure e. 10,000 si with a nozzle orifice
Y g p g~ p
diameter of about 0.6 mm to make fibres, being thereby
expensive to make pulp, more so because of this device's .
i inabilityto disintegrate more than one wood log at one
time. At such high water jet pressures, the pulp quality
4
2~985~~
is likely to be relatively low (no pulp test data given
in Mazurkiewich). Moreover, for a certain jet pressure,
the maintenance of optimum constant distance from the
water. nozzle to the wood log surface being continuously
disintegrated is very important for the uniform quality
of the pulp being produced. However, in Mazurkiewich
though some attempt has been made to correct this
process-deficiency by the use of few staggered nozzles,
it is not good enough for wood logs of different
diameters to warrant the production of uniform quality
pulp. This device is also incapable of processing
habitually uncompacted waste papers and non-wood
cellulosic materials to make uniform quality pulps
because of its use of high pressure blasting water jets
making these materials flying all over in the material
feeding and operating set-up described in Mazurkiewich.
It is preferable to have one basic pulp making
device which will be capable of making different kinds
of uniform quality pulp from different fibre sources
using less expensive equipments and infrastructurs, and
less power, heat and chemicals. The'present invention
relates to a pulp making device to produce such pulps at
lower cost.
Summary Of~ Invention
5
2~~$~~~
The present invention consists of a pulp making
device suitable for manufacturing economically high
quality mechanical, semi-chemical and chemical pulps
from various cellulosic materials. In one aspect of 'the
invention the wood logs, preferably barked, being
carried over by a conveyor pile up on an inclined floor
so that the length-wise logs are sloped towards and
pressed against the suitably spaced retaining bars. Just
behind these bars, there are a series of suitably spaced
horizintal, and parallel to the wood logs shower
headers, each one containing a number of nozzles. The
water nozzle showers, with a delivery pressure of less
than 4,000 psi and temperature preferably not exceeding
100 deg.C mainly for softening the lignin, dislodge the .
fibres gently along the fibre length, thus causing least
damage to the fibres. These showers, preferably being
fan shaped, overlap each other to some extent at the
edges. This arrangement, combined with the sweeping
action of the oscillating shower header containing a
series of nozzles, disintegrates a certain rectangular
sized patch of wood. The neighbouring nozzles at the
sides, top and bottom also work on the same principle
disintegrating thereby, by their combined action, the
whole front part of the wood pile facing the nozzles.
Because of the sloped body of the conveyor frame and the
steep inclination of the floor which \is preferably
filled up with logs up to the topmost nozzle header
6
2~98j16
height, the wood logs at the front continue to butt
against the retaining bars, and thus maintain the
distance between the continuously disintegrating wood -
surface and the nozzles practically constant, an aspect
which is important and preferable for manufacturing
uniform quality good pulp. The pulp thus produced can be
collected to a receiving tank by flowing through the
floor-openings and over both sides of the log pile.
These floor openings also allow materials such as small
wood pieces, stones, loose bark pieces to go through to
be out of the operating floor.
In another aspect of the invention, suitable
pulping and bleaching chemicals can be added to the
shower water, preferably hot, the pulp thus produced
being processed by the industry-norm procedures to
attain target quality.
In another embodiment of the invention, the waste
papers and non-wood cellulosic materials, in uncompacted
pile or loose form can also be processed to pulp using
the same basic operating principle as for wood logs, but
with some modifications such as the configuration of the
inner space of the device, the location of the shower
headers, orientation of nozzle showers, spacing of
retaining bars, slope and design of the floor.
7
2fl98~~.G
In another aspect of the invention, the wood
material can be of any other dimension such as chips.
These ones, waste papers and non-wood cellulosic
materials could also be defibered under pressurized
conditions in a confined vessel using higher than 100
deg.C temperature and above atmospheric pressure for
these spray pulpings.
Summary Of Drawings
The invention, as exemplified by preferred
ZO embodiments, is described with reference to the drawings
in which:
Figure 1 is a perspective view of an embodiment of
a wood material feeding and processing device, along
with spray headers, nozzles, and retaining bar set-up of
the invention;
and
Figure 2 is the detailed view of the spray~headers
with nozzles and retaining bar set-up;
and
20 Figure 3 is the detailed view of a triangular
8
~~~8~~~
shaped retaining bar, and fan-shaped spray showers just
overlapping at the edges;
and
Figure 4 is the detailed view of the log from which
the fibres are being dislodged, the surface of the log
generally keeping a constant distance from the nozzle;
and
Figure 5 is the perspective view of an embodiment
of a waste paper and non-wood plant materials processing
device, along with spray header, retaining bar set-up,
slope at floor and ceiling, and particularly narrowing
configuration on all sides from front to the back - of
this invention;
and
Figure 6 is the side-view line diagram of the
processing device Figure 5, with the slope at top~and
bottom, and narrowing configuration from front to the
end;
i : and
9
,.: ','... _... ~. : ..:.;.. ..-.';,,,. - , . , . . '' '~:;.. .. ,".'r . , ~.
~; ~:' , . ~::: , ,~, ,.:. i ~, j.-~~:. . .. -~, ~~.. ~.., '..; : . . .
1
Figure 7 is the detailed view of the spray headers
with nozzles and retaining bar set-up.
Detailed Description
Referring to the Figures 1, 2, 3 and 4, the
embodiment of the invention shown, a material feeding
device comprises a conveyor with rollers 10. this
conveyor is of belt type, or may be of other suitable
types. The sloped body of the conveyor frame 12 delivers
the materials such as logs 16 to the platform floor 14
ZO which is also sloped, preferably using the natural
gravitational force. This platform, preferably with
walls l8 on both sides to contain the feeding materials,
has a floor with rectangular openings 14 which may also
be of other configurations. Under this platform there is
a channel 20 leading to a holding container to collect
pulp, small wood pieces, stones and the like.
This material feeding device has retaining bars 24,
i
behind which there are oscillating shower headers 22
containing shower jets 26. These headers are preferably
t
parralel to each other being spaced at suitable
distances so that their fan shaped oscillating jet
t
! showers, as a whole, cover the entire front surface of
a
A
the feed materials. The orientation of these headers may
a
also be of other configurations. The retaining bars are
y,,,. . . . ,.:,...~ ' ~.~. ~:,'.. . w.~. ,;~ ~:..~,~~ . ;';~ , ,'.~,'~ ~.
,~~~' .,, '.: . ,..... ,.,::'.,: ,..
2~9~~16
of triangular design 24, but may be of other suitable
designs also. These suitably spaced bars are straight
for most of the bottom part and are sloped at the top
part, but may be of other designs and spacings also to
accomodate the incoming materials for disintegration to
best advantage.
The shower jets 26 are preferably of the models
which will produce fan-shaped sprays 28, but these may
be of some other suitable models also. The distance 32
between the shower jets and the materials being
disintegrated is kept fairly constant by the retaining
bars 24 for relatively uniform and sweeping
disintegration 30 of wood or some other cellulosic
materials which are being processed.
When a piece of wood is subjected to pressurized
water jet showers at elevated temperature, the water
being all around the target wood-piece area, the lignin-
softening temperature is lowered. So, by applying the
water jet showers, preferably being fan-shaped and
oscillating, at suitable temperature~along the length of
logs, in which direction most of the fibres are
oriented, strong, relatively undamaged and uncut fibres
are dislodged gently thereby making a very good
mechanical pulp. This process will continue until the
whole log or the fibrous material being processed is
11
2~98~~.~
used up. Suitable chemicals may also be added with this
water for additional delignification and/or bleaching,
if needed.
Referring to the Figures 5, 6 and 7 for pulping
waste papers and non-wood plants, the embodiment of the
invention shown, a preferably rectangular opening 52 of
the device through which these materials 54 are fed
preferably to full capacity. The opening 52 may be also
of other configuration. Overhead shower headers 22,
shower heads 26, sprays 28 and triangular straight
retaining bars 25, preferably being on under-the-ceiling
location, generally operate similarly as described
previously for Figures 1, 2, 3 and 4> The two sides 44
of this device are preferably upright, the top 40 and
platform/bottom 42, however, preferably being slopy.
Both sides of 44, top 40 and bottom 42 - all gradually
narrow towards the end 48, 50 - thus providing a
gradually shortening confined space as the materials
being processed travel towards this end 48, 50 from the
~~ front 52. The platform 42 with its tapered
configuration 46 towards the end has'preferably'circular
openings 56 through which the disintegrated materials
along with other smaller-than-opening particles can pass
through.
When the materials 54 to be processed are fed by a
. , 2~98~.16
conveyor with rollers similar to 10 in Figure 1 -
through the opening 52 preferably filling up this
opening fully, the platform of the device being slopy
and the sides being tapered, the materials will be
filled up to the ceiling from front 52 to end 48, 50,
butting against the retaining bars 25. The entire top
surface of the material-mass will be subjected to
overlapping fan-shaped oscillating showers 28, similar
to 28 in Figure 4, and the materials coming in contact
with these showers will be disintegrated. These
dislodged materials being of small size and being
carried out by the shower-water, will percolate down to
the bottom and, by passing through the platform-openings
56 will go out of the system for further industry-norm
processing. Being pushed by the materials behind in the
slopy platform preferably by gravity, the entire
material-mass will be continuously disintegrated,
exposing new surfaces to be worked upon at top and be
pushed forward until the narrowed-down tip end of this
material-mass is also disintegrated in the relatively w
small place at the end. The platform openings 56 near
the end 50 may be of different configuration than the
rest - to allow the bigger non-cellulosic, and not-
suitably-disintegrated cellulosic particles to pass
through for collection and processing separately than
the rest of the regular properly disintegrated
materials.
13
20~~~~.6
The overall approach is that the energy and
temperature are applied, with least possible waste,
exactly where these are needed most viz. directly on
the surface of the cellulosic materials for
disintegration - minimizing thereby a lot of middleman- ~
waste of these items, such as idle powers of refiners,
grinders, pulper motors along with their wasting of
these items due to their inherent processing design
shortcomings.
Furthermore, in case of semichemical or chemical
2~98J~.6
temperature preferably not exceeding 100 deg.C is
applied. This pulp is equivalent to first stage thermo
mechanical pulp (TMP) or pit groundwood (GWD) pulp,
followed by industry-norm pulp processing steps, using
chemicals also, if needed. When a debarked black spruce
log was subjected to along-the-fibre sprays of hot water
at 85 deg.C and 950 psi water header pressure, a
mechanical pulp was produced. The nozzle used was Brooks
1/4 US9510 @ 4.7 USGPM at 950 psi. This first stage pulp
had 698 Canadian Standard Freeness (CSF) with 27.6-8
rejects using a 0:20 mm (0.008 inch) slotted flat screen
plate; and the screened pulp had Kajaani L weighted av.
of 1.42 mm and W weighted av. of 2.17 mm.
When a disintegrated spruce mechanical pulp came in
contact with a Mg-base liquor of 6.27 total S02 at 90
deg.C and atmospheric pressure, the Kappa No. of this
pulp at 10~ consistency started to drop down from
initial 139 (0 min.) to 134 (1 min.), 127 (3 min.) and
111 (5 mina) indicating such Kappa No. reduction
tendency, over time, of the disintegrated cellulosic
fibres when surrounded by suitable liquors) even at
atmospheric pressure and less than 100 deg.C
temperature.
For making semi-chemical pulps and for pulp
bleaching: Similar conditions for making mechanical
t;
- ~p~g~l~
pulps as mentioned previously, are applied, plus
suitable chemicals preferably with the jet shower water
are used, followed by preferably dewatering and tower-
retention with additional chemicals, if needed - the
pulp thus produced being equivalent to first stage
chemi-mechanical pulp (CMP), ready for further industry-
norm processing and bleaching treatments.
For producing chemical pulps: All above, followed
by preferably another delignification step using pulping
chemicals, and/or oxygen or ozone, plus industry-norm
pulp processing steps. As the starting raw material is
in disintegrated fibre-form now, this delignification
i
step would be relatively mild for temperature-pressure-
chemical applications, compared to the industry-norm
practices - thus resulting in overall low cost and good
pulp quality - for the production of chemical pulps in
this way.
s
For some situations, other non-log wood materials
such as chips and sawmill wastes can also be defibered
in a confined space by using this spray technology. Also
wood materials of any shape and size, waste papers and
non-wood cellulosic materials can be defibered under
pressurized conditions in a confined vessel using higher
than 100 deg.C and above atmosphericpressure for
pulping by such sprays.
16
2~~~~~.6
Although only two embodiments of the present
invention have been described and illustrated, the
present invention is not limited to the features of
these embodiments, but includes all variations and
modifications within the scope of the claims.
17
a
:' ' .
~
' y:
.. . :r ~ ;;
.. . ,. ~, ,. , , ~ , . , . A.. . ~~ ~ v , . . .,
