METHODE ET DISPOSITIF POUR L'OBTENTION DE MATERIAUX FIBREUX

METHOD AND DEVICE FOR OBTAINING FIBROUS MATERIALS

Abrégé anglais

ABSTRACT OF THE DISCLOSURE:
Method for obtaining fibrous material from raw
vegetable materials comprising the following steps. The raw
material is reduced into splinters and soaked into lye at 50°
to 80°C for a period of 40 to 60 min. and then the surplus lye
is removed. The splinters are then heated at 200 to 500°C for
a period of 120 to 1200 sec. at atmospheric pressure to remove
the dampness. Finally, the treated material is washed,
defibred and sorted. There is also disclosed a device which
comprises a reactor pipe having perforations at the top and into
which a screw conveyer, having a hollow perforated shaft, is
mounted for rotation. The reactor pipe has a feed hopper at one
end and an outlet at the other end feeding into a vessel. The
reactor pipe is surrounded by a steam chamber wherein steam is
introduced which comes from the reactor pipe into which boiling
takes place, the steam passing through the perforated part of
the reactor. There is a line connection between the chamber
and the bottom of the feed hopper and another line connection
between it and the hollow shaft.

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A method of obtaining a fibrous material from a
vegetable raw material comprising the following successive steps:
- reducing said raw material into splinters and
soaking them in lye at substantially 50°C to 80°C, for a period
of substantially 15 to 60 min., and removing surplus lye from
said splinters;
- heating said splinters at substantially 200°C to
500°C for substantially 120 to 1200 sec. at atmospheric pressure
to remove dampness, and
- washing, defibring and sorting the fibrous material
thus obtained.
2. A device for obtaining a fibrous material from a
vegetable raw material, comprising:
- a horizontally disposed reactor having a raw material
feeding means at one end, an outlet means at the other end, said
reactor being perforated along the top portion thereof between
said feeding means and said outlet means in a heating zone
thereof, and wherein said reactor otherwise defines a closed
reaction chamber;
- a rotary screw conveyor having a perforated hollow
shaft mounted in said reaction chamber for moving the material
being treated through said reaction chamber;
- a shell mounted over said heating zone of said
reaction chamber to define a steam chamber therebetween, and
means heating said steam chamber;
- first steam line means interconnecting said steam
chamber and said raw material feeding means and second steam line
means interconnecting said steam chamber and said hollow shaft
thereby defining a closed steam cycle;

- a vessel below said reactor, fluid transfer means
between said vessel and said reactor outlet means, and means to
wash treated material from said screw conveyor at said outlet
means to send it into said vessel.
3. A device as claimed in claim 2, wherein said
washing means is a warm water supply.
4. A device as claimed in claims 2 or 3, wherein said
feeding means is a hopper.
5. A device as claimed in claims 2 or 3, wherein said
reactor is perforated along about one third of its periphery.
6. A device as claimed in claims 2 or 3, wherein
said means heating said steam chamber is an electrical resistance
heater.

Description

1~)44408
The present inyention relates to ~ method and to a
device for obtaining f~brous materials from vegetable raw
materials.
Throughout the world methods and devices are known for
obtaining fibrous materials through classical methods (sulphite, or
more specifically boiling of wood particles in an aqueous solution
of sodium base, natron, sulphate etc.) and chemical agents
(Ca(H SO3)2; NaOH; (NaOH~Na2S t Na2CO3) etc.) for delignifying.
The process flow diagrams are based on continuously operating
devices. It is characteristic, in all methods for delignifying
and for continuously operating devices for boiling, that they
operate u`nder high pressure and heat with steam at maximum
temperature 180 - 190C. This requires the installations to be
adapted for respective working pressure of 10 to 15 atm. The most
essential parts in these installations are the input and the
outlet seals which ensure continuous supply of raw materials and
output of the material boiled without affecting the working pres~
sure in the device. Besides, in the reactors of these devices,
the liquid is supplied (lye for boiling) at a wood to liquor ratio
of 1:6 to 1:8 (wood:lye).
One of the well known continuously operating devices -
; consists of one, two or several horizontal pipes in which there
are screw conveyers for conveying the material. At the begin-
s ning of the topmost and at the end of the lowest pipes, the seals ~ ~~
mentioned are located for supplying raw materials and for drawing
off the boiled material. The device operates when supplying lye ^
~ to the pipes, heating with direct steam at 180-190C and pres-
s sure 10-12 atm. The duration of the boiling process is 20-25 min.
, Out of all devices operating at atmospheric pressure,
one is known for obtaining semi-cellulose according to the cool-
alkaline method. This device consists of an inclined pipe with
a screw conveyer which pipe is half full of lye at a wood to
- 1 -
, . . - . . .

- ~044408
liquor ratio of 1;6~
The process is carried out at atmospheric pressure
and normal temperature. No duration time is defined.
Another device consists of horizontal pipes with screw
conveyers and a pump for forced circulation of the lye for
boiling supplied durin~ the process of boiling. The process
takes place at atmospheric pressure and 100C. This device is
used for obtaining fibrous materials from straw. The duration
of the boiling is not fixed, either~
The above methods for delignifying with devices for
boiling have the following disadvantages:
The delignifying methods are applied at 180-190C, the -
chemicals are supplied at a wood to liquor ratio of 1:6 to 1:8, -~
`3 pressure 10-12 atm. for 20-40 min. These conditions are provided
in the respective devices with continuous operation, heated with
steam which creates that pressure, which makes input and outlet
x seals absolutely necessary, as well as a special device for
providing that pressure. With devices operating at atmospheric
pressure and normal temperature or at 100C, it is absolutely
necessary to use lye for boiling in the boiling pipes for an
extended length of time. These devices are suitable for boiling
of annual and herb pla`nts and leaf wood for obtaining semi-
`~ cellulose.
. It is a purpose of the present invention to provide a
method for obtaining fibrous materials basically boiling the raw
`~ materials and to a device to carry out the method.
More specifically, the method of the invention comprises
the following successive steps. The raw material is reduced into
B splinters and is soaked in ly~e at substantially 50C to 80C for
a period of substantially ~ to 60 min. Surplus lye is then
~- removed from the splinters. Thereafter, the splinters are heated
at substantially 200C to 500C for substantially 120 to 1200 sec.
., .
- 2 -

16)444~8
at atmospheric pressure to remove dampness. Finally, the
fibrous material thus ob~ained is washed, defibred and sorted.
It is also within the purview of the invention to
provide a device for carrying out the aforesaid method. It com-
prises a horizontally disposed reactor having a raw material
feeding means at one end and an outlet means at the other end.
The reactor is perforated along the top portion between the
feeding means and the outlet means in a heating zone; otherwise,
the reactor defines a closed reaction chamber. A rotary screw
conveyer having a perforated hollow shaft is mounted in this
reaction chamber and serves to move the material being treated
through the reaction chamber. A shell outwardly surrounds the
heating zone of the reaction chamber to define a steam chamber
therebetween, a heater being provided to heat the steam chamber.
First steamline means interconnects the steam chamber and the
raw material feeding means while a second steam line means
interconnects the steam chamber and the hollow shaft to thereby -
define a closed steam cycle. There is provlded a vessel below .- ---
the reactor which is connected to the reactor outlet means while
further means is provided to wash the treated material from the ~-
~, screw conveyor at the outlet means to drive the treated material
into the vessel.
, With the above device in mind, while the material is
in the high temperature heating zone, steam is produced which
3 does not exert any pressure because, in this zone, the reactor
~' is perforated. Steam is formed in the steam chamber between thereactor and the shell and is then directed to the bottom of the
.
feeding hopper to heat the material before it enters the heating
- zone. Similarly,-steam is drawn off from the steam chamber and
is conducted into the screw conveyer hollow shaft. Thus, steam
moves through a closed cycle without creating any pressure due `
.. . . .
to the system being open. The consumption of chemicals depends
,, , ., , ~ , . . . . .

1044408
on the raw material, the duration o~ the boiling process and the
degree of boiling.
By appropriately combining the consumption of chemicals,
the temperature, the retention time of the raw material in the
heating zone, the degree of boiling can be regulated and hence
the output of fibrous materials.
This method can be applied to all kinds of vegetable
raw materials used for obtaining fibrous materials.
A device made according to the invention, for carrying
out the above method, is shown in Fig. 1. It consists of a
horizontal screw conveyer 2, mounted on a thick-walled pipe shaft
3, perforated with openings 8 between the turns of the screw con-
veyer. Shaft 3 is located in a thick wall reactor pipe 4 perfora-
ted in its upper part up to 1/3 of its circumference and having,
; at the front end, a feeding hopper 1, immovably fixed, and at
the rear end an outlet pipe 12 connected with a vessel 13
receiving warm water from pipeline 11. The reactor 4 is located
-~ inside a larger diameter pipe or heater 5 surrounded lengthwise
by an electrical resistance heater 7. Between both pipes, a
space 9 is formed, out of which a steam line 6 runs which is con-
nected with the hopper 1, and a steam line 10 which is con-
i nected with the shaft 3 of the screw conveyer 2.
The advantages of this method are the following ones:
~ - the mèthod for delignifying is applied through
j soaking the raw material beforehand and the surplus lye for
1 boiling is squeezed out
-~ - temperature 200-500C
.~
.~1i. - atmospheric pressure
- duration 120-1200 sec. -~
These conditions are provided by the device with con- - -
7 tinuou~ operation which is an open system because the steam from
- the boiling lye does not create pressure in the reactor, leaves
~, .

1~)444~8
the reaction space and moves in a closed cycle Therefore steam
does not enter the ~tmosphere and thus does not pollute the
environment. The fibrous material obtained is in a much lighter
colour as compared to that obtained by other methods. The
output is 52-87%. The fibrous material has comparatively high
physical-mechanical qualities. Finally, heating may be performed
by electric heaters.
The invention is embodied in the following examples
which are described with respect to the enclosed diagram of a
device adapted for the practical carrying out of the process.
Example l
Wood splinters are soaked in lye for boiling (solution
of NaOH in concentration of 60-9Og/l), depending on the planned
consumption of active alkalis (8-20% in ratio to the absolutely
dry material), at 50-80C for 15-60 min. The surplus lye is
squeezed out and taken back to be used again. Through the feeding
hopper, the soaked splinters fall on the screw-conveyer 2 of the
reactor 4 which takes them and conveys them to the high
temperature zone (200-500C) where boiling for 120-1200 sec. takes
place and steam comes off. In this zone, the reactor is perforated
in its upper part, as aforesaid, and the steam goes into space 9
~ between the reactor 4 and the heater 5, from where through pipe 6
; it is led to the bottom of feeding hopper l to heat the incoming ~ -
j material, and through pipe 10 to be conveyed to shaft 3 of screw
`~ conveyer 2, if necessary. Through openings 8 of the shaft 3,
steam passes back into the zone where boiling takes place. Almost
, dry, the boiled material enters the hot water vessel 13, supplied
through pipe ll which serves to remove the splinters off the turns -
, of the screw-conveyer.
Example 2 -
Example 2 is carried out exactly as example l but
instead o wood splinters, straw slices undergo treatment.
.~ .
. ~ 5
,'", ~
', .

1~)44408
Example 3
Example 3 is carried out analogically to example 1 but
the active alkalis NaOH ~ Na2S (sulphate lye) calculated as Na2O
are 8% as compared to the absolutelv dry material.
Example 4
_ . _
Example 4 is carried out analogically to example 3 but
the active alkalis are 10% as compared to the absolutely dry
material.
Example 5
Example 5 is performed as example 3 but the active
`~ alkalis are 17% as compared to the absolutely dry material. Yi
.~ Example 6
. Example 6 follows exactly example 1 but the lye for
, boiling is monosulphitic (Na2 SO3 : Na2 CO3=4:1).
~ The output of fibrous materials from vegetable raw
: .materials obtained according to the above examples and their
properties are given in table 1.
,l
:
J,
: .:
.,. : ,'. .
~ ' .
~ ~ , ' ' ''' ~.
''~ ' ":
~, ' . .'~' :
': ' ' ''~ '
.,~ .' .
., .

~444~8
h-rl O h O O1~ 0 0
~ ~ Gq S~ bD ~-- ~ ~ ~
. . H h ~ ~ ~ 0~ ~
.~
a~ N U~ ~ O u~ O
O C) rl C) C~ O ~ ~ ~ ~
a~ ~1) Gq 5:~ ~ ~ ~ ~ .. ..
V-rl h ~ ~0 N C`J N N
h I . I
~5 OD bJ~ a~ d t~ N ~D
~3 ~ ~ O ~ ~ h
~ h-,l 0 ~ O u~
E a~ ~1 ~ ` r~ ~ ~
h +' ~ ~ ~ N u~ h
,Q i ~,-,1 h t~ ~ t-- t-- 0
O P. ~ ~D
~ .~ . V~
u~ &~ * *
r~
U~ U~
h ~ O qD o
'~ a) ~ . .
:." ~o P. ~ c~l~' - ~ ~ .
h :~ ~ o a~ ~D
.. ~ O
~- O '
O bO ' .''
~Cd ~ .
~`, H ,~ ~ ~ N N N N C\J
~`' O Iq Q . . .,
O ~ ~ . ':','.,
rl rl ~1 . , ~ UO~ UO~ .. ,,,., :,.
y .~ ~o ~$ ov
., . C) . .
~i Q)-rl h ~ N . . .;
0 . P ~ -rl S~ ~0 ~0 ' ~00~ ~0
O 0 ~1 07 0 ~ ~ ~ . ,
~1 0 I ~ d-rl Q-rl O O O O O O O O O O . .
. O ~ h ,~ h ,~ h ~ h ,s: h ~
,D ~ ~ ~ ,-
o 3 I qP~ ::
a) .,~ ~; ~
,al ~ E3 h Gq ~ '::
~ ~ ~ tq h r
'.4j rOI ~ ~1 12l ~ h blJ ~
~ I ~ d o a) ~ O ....
;~ rl h 3~ O ~1 ~ m P: p~ - ~ :
t~ ~ h ~q
., ~ ~ ~ ~ '
, ~ V 1~ ____ __ . .
., - .
., '', '~
, ' . .
.~ p~ ' .