U.S. patent application number 15/381257 was filed with the patent office on 2017-06-29 for waste paper recycling apparatus.
The applicant listed for this patent is DUPLO SEIKO CORPORATION. Invention is credited to Yoshihisa Higashimoto, Tadashi Terai.
Application Number | 20170183816 15/381257 |
Document ID | / |
Family ID | 59086202 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170183816 |
Kind Code |
A1 |
Terai; Tadashi ; et
al. |
June 29, 2017 |
WASTE PAPER RECYCLING APPARATUS
Abstract
The control unit operates the stirring device sequentially in a
defiberization operating mode, a transition operating mode, and a
dilution operating mode. In the defiberization operating mode, the
stirring blade is rotated at the revolution speed for
defiberization of waste paper in the disaggregating water stored in
the stirring chamber to generate a waste paper pulp slurry. In the
transition operating mode, the dilution water from the water supply
unit is supplied to the waste paper pulp slurry while rotating the
stirring blade at the revolution speed for defiberization to stir
the waste paper pulp slurry. In the dilution operating mode, the
dilution water from the water supply unit is supplied to the waste
paper pulp slurry while rotating the stirring blade at the
revolution speed for stirring, lower than the revolution speed for
defiberization, to stir the waste paper pulp slurry.
Inventors: |
Terai; Tadashi; (Wakayama,
JP) ; Higashimoto; Yoshihisa; (Wakayama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DUPLO SEIKO CORPORATION |
Wakayama |
|
JP |
|
|
Family ID: |
59086202 |
Appl. No.: |
15/381257 |
Filed: |
December 16, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21B 1/32 20130101; Y02W
30/646 20150501; Y02W 30/64 20150501; D21B 1/325 20130101 |
International
Class: |
D21B 1/32 20060101
D21B001/32 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2015 |
JP |
2015-250804 |
Claims
1. A waste paper recycling apparatus comprising: a plurality of
processing units configuring a waste paper processing system; and a
control unit configured to control operation of each processing
unit, wherein one of the processing units is a pulper, the pulper
has a stirring chamber, a stirring device to rotationally drive a
stirring blade in the stirring chamber, and a water supply unit to
supply dilution water to the stirring chamber, the control unit
operates the stirring device sequentially in a defiberization
operating mode, a transition operating mode, and a dilution
operating mode, and disaggregates, in the defiberization operating
mode, the waste paper in a predetermined amount of disaggregating
water stored in the stirring chamber to generate a waste paper pulp
slurry by rotating the stirring blade at the number of revolutions
for defiberization, stirs, in the transition operating mode, the
waste paper pulp slurry by rotating the stirring blade at the
number of revolutions for defiberization while supplying the
dilution water from the water supply unit to the waste paper pulp
slurry in the stirring chamber, and stirs, in the dilution
operating mode, the waste paper pulp slurry by rotating the
stirring blade at the number of revolutions for stirring, in which
the number of revolutions for stirring is lower than the number of
revolutions for defiberization, while supplying the dilution water
from the water supply unit to the waste paper pulp slurry in the
stirring chamber.
2. The waste paper recycling apparatus according to claim 1,
further comprising a concentration detection unit configured to
detect a concentration of the waste paper pulp slurry in the
stirring chamber, wherein the control unit switches the operation
mode with reference to the concentration of the waste paper pulp
slurry detected by the concentration detection unit to switch the
transition operating mode to the dilution operating mode at a
transition termination concentration in transition operation, and
the transition termination concentration is set lower than a
defiberization termination concentration in the defiberization
operating mode and set higher than a dilution termination
concentration in dilution operation in the dilution operating
mode.
3. The waste paper recycling apparatus according to claim 2,
wherein one of the processing units is a waste paper inlet to
charge the stirring chamber with the waste paper, the waste paper
inlet has a weight sensor to measure a waste paper charge amount to
be put into the stirring chamber, the water supply unit has a flow
sensor to measure an amount of water supplied to the stirring
chamber, and the concentration detection unit calculates the
concentration of the waste paper pulp slurry from a weight sensor
measurement and a flow sensor measurement.
4. The waste paper recycling apparatus according to claim 1,
wherein one of the processing units is a waste paper inlet to
charge the stirring chamber with the waste paper, the waste paper
inlet charges the stirring chamber with the waste paper a plurality
of times, the control unit operates the stirring device in a
defiberization preparation operation mode during waste paper
charging operation of the waste paper inlet, and the control unit
roughly tears, in the defiberization preparation operation mode,
the charged waste paper by rotating the stirring blade at the
number of revolutions for rough tearing and spreading, lower than
the number of revolutions for stirring.
5. The waste paper recycling apparatus according to claim 2,
wherein one of the processing units is a waste paper inlet to
charge the stirring chamber with the waste paper, the waste paper
inlet charges the stirring chamber with the waste paper a plurality
of times, the control unit operates the stirring device in a
defiberization preparation operation mode during waste paper
charging operation of the waste paper inlet, and the control unit
roughly tears, in the defiberization preparation operation mode,
the charged waste paper by rotating the stirring blade at the
number of revolutions for rough tearing and spreading, lower than
the number of revolutions for stirring.
6. The waste paper recycling apparatus according to claim 3,
wherein one of the processing units is a waste paper inlet to
charge the stirring chamber with the waste paper, the waste paper
inlet charges the stirring chamber with the waste paper a plurality
of times, the control unit operates the stirring device in a
defiberization preparation operation mode during waste paper
charging operation of the waste paper inlet, and the control unit
roughly tears, in the defiberization preparation operation mode,
the charged waste paper by rotating the stirring blade at the
number of revolutions for rough tearing and spreading, lower than
the number of revolutions for stirring.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2015-250804 filed on
Dec. 24, 2015.
FIELD OF THE INVENTION
[0002] The present invention relates to a waste paper recycling
apparatus that is installed in an office and the like, where waste
paper is generated, to recycle paper.
BACKGROUND OF THE INVENTION
[0003] Conventional waste paper recycling apparatuses are provided
with, for example, a waste paper inlet, a pulper, a deinking unit,
a papermaking unit, a drier, and a control unit to control
operation. The waste paper inlet supplies waste paper as a recycle
material to the pulper. The pulper disaggregates the waste paper to
prepare a waste paper pulp slurry containing waste paper pulp. The
deinking unit prepares deinked pulp by deinking the waste paper
pulp slurry. The papermaking unit produces wet web from the deinked
waste paper pulp slurry. The drier dries the dewatered the wet
web.
[0004] The pulper has a stirring chamber, a stirring blade disposed
in the stirring chamber, and a driving unit to rotationally drive
the stirring blade. The waste paper is stirred in disaggregating
water in the stirring chamber by rotation of the stirring blade for
defiberization and the waste paper pulp slurry thus prepared is
transferred to the next step.
[0005] As illustrated in FIG. 5, a predetermined amount of stirring
water is poured into the pulper (S1) and then waste paper is put
into the pulper (S2). Then, the stirring blade is rotated at 750
rpm for defiberization (S3). Subsequently, dilution water is
supplied under stirring (S4), and at a pulp density of 4 weight %
(S5), the defiberization is stopped (S6).
[0006] JP 2011-219893A describes as follows. For stirring by a
stirring blade, the water level in the stirring chamber, that is,
the level of a liquid containing the waste paper material and water
from a water supply unit is set at a height capable of immersing
the stirring blade. While the number of revolutions of the stirring
blade is increased under stirring, water is supplied from the water
supply unit to immerse the stirring blade in the liquid in the
stirring chamber.
[0007] In the pulper, the stirring blade in the stirring chamber is
rotated at the number of revolutions for defiberization (750 rpm),
and the waste paper is disaggregated in a predetermined amount of
the disaggregating water to prepare a waste paper pulp slurry at a
defiberization concentration (8 weight %). Then, during rotation at
the number of revolutions for stirring (400 rpm), dilution water is
added to dilute the waste paper pulp slurry at a predetermined
concentration (4 weight %). The restriction on the number of
revolutions prevents excessive stirring intensity and thus
restricts waste of power cost and noise.
[0008] Unfortunately, in the course of defiberization operation,
indisaggregated pieces of paper are sometimes attached to the inner
wall of the stirring chamber in the pulper. The attached
indisaggregated pieces of paper may be mixed into the waste paper
pulp slurry during the dilution operation. Papermaking from the
waste paper pulp slurry together with such indisaggregated pieces
of paper causes reduction in quality of resulting recycled paper.
In another case, the mixed pieces of paper are attached to a liquid
level sensor and cause improper liquid level detection in the
stirring chamber.
[0009] In addition, in conventional procedure, a waste paper pulp
slurry at a predetermined concentration is delivered to the
deinking unit in the next step and then inside the stirring chamber
is washed to eliminate the attachment of pieces of paper causing
the above defects before the next defiberization. In the washing,
water is sprayed in the stirring chamber from showerheads facing
the opening of the chamber to wash away the fiber of the waste
paper pulp and the indisaggregated pieces of paper that are
attached to the inner surface of the stirring chamber.
[0010] The showerheads, however, cause increase in complexity and
size of the apparatus configuration and thus cause increase in
costs.
[0011] It is an object of the present invention to provide a waste
paper recycling apparatus that solves the above problems. The
apparatus makes recycled paper of quality not affected even by
mixing a piece of paper attached to an inner wall of a stirring
chamber into a waste paper pulp slurry in the course of dilution
operation, and achieves downsizing of the apparatus by eliminating
washing by spraying water from showerheads.
Disclosure of the Invention
[0012] To solve the above problems, a waste paper recycling
apparatus of the present invention includes:
[0013] a plurality of processing units configuring a waste paper
processing system; and
[0014] a control unit configured to control operation of each
processing unit, wherein
[0015] one of the processing units is a pulper,
[0016] the pulper has a stirring chamber, a stirring device to
rotationally drive a stirring blade in the stirring chamber, and a
water supply unit to supply dilution water to the stirring
chamber,
[0017] the control unit operates the stirring device sequentially
in a defiberization operating mode, a transition operating mode,
and a dilution operating mode, and
[0018] disaggregates, in the defiberization operating mode, the
waste paper in a predetermined amount of disaggregating water
stored in the stirring chamber to generate a waste paper pulp
slurry by rotating the stirring blade at the number of revolutions
for defiberization,
[0019] stirs, in the transition operating mode, the waste paper
pulp slurry by rotating the stirring blade at the number of
revolutions for defiberization while supplying the dilution water
from the water supply unit to the waste paper pulp slurry in the
stirring chamber, and
[0020] stirs, in the dilution operating mode, the waste paper pulp
slurry by rotating the stirring blade at the number of revolutions
for stirring, in which the number of revolutions for stirring is
lower than the number of revolutions for defiberization, while
supplying the dilution water from the water supply unit to the
waste paper pulp slurry in the stirring chamber.
[0021] The waste paper recycling apparatus of the present invention
further includes a concentration detection unit configured to
detect a concentration of the waste paper pulp slurry in the
stirring chamber, wherein
[0022] the control unit switches the operation mode with reference
to the concentration of the waste paper pulp slurry detected by the
concentration detection unit to switch the transition operating
mode to the dilution operating mode at a transition termination
concentration in transition operation, and
[0023] the transition termination concentration is set lower than a
defiberization termination concentration in the defiberization
operating mode and set higher than a dilution termination
concentration in dilution operation in the dilution operating
mode.
[0024] In the waste paper recycling apparatus of the present
invention, one of the processing units is a waste paper inlet to
charge the stirring chamber with the waste paper, the waste paper
inlet has a weight sensor to measure a waste paper charge amount to
be put into the stirring chamber,
[0025] the water supply unit has a flow sensor to measure an amount
of water supplied to the stirring chamber, and
[0026] the concentration detection unit calculates the
concentration of the waste paper pulp slurry from a weight sensor
measurement and a flow sensor measurement.
[0027] In the waste paper recycling apparatus of the present
invention, one of the processing units is a waste paper inlet to
charge the stirring chamber with the waste paper, the waste paper
inlet charges the stirring chamber with the waste paper a plurality
of times, the control unit operates the stirring device in a
defiberization preparation operation mode during waste paper
charging operation of the waste paper inlet, and the control unit
roughly tears, in the defiberization preparation operation mode,
the charged waste paper by rotating the stirring blade at the
number of revolutions for rough tearing and spreading, lower than
the number of revolutions for stirring.
Effects of the Invention
[0028] As described above, according to the present invention, the
transition operating mode is performed between the defiberization
operating mode and the dilution operating mode, and in the
transition operating mode, the dilution water is supplied to the
waste paper pulp slurry while the stirring device is driven to
rotate the stirring blade at the number of revolutions for
defiberization. In the transition operating mode, pieces of the
waste paper attached to the inner wall of the stirring chamber are
incorporated into the waste paper pulp slurry with the rise in the
liquid level in the chamber to be disaggregated by rotating the
stirring blade at the number of revolutions for defiberization.
[0029] This allows restriction on residual rough pieces of the
waste paper in the waste paper pulp slurry in the dilution
operating mode and prevention of reduction in quality caused by the
pieces of paper in a later step of papermaking. In addition, a
strong stirring action is exerted on the waste paper pulp slurry
during the rise in the liquid level in the chamber and thus the
inner chamber wall is effectively washed with the waste paper pulp
slurry to wash out the pieces of paper. Accordingly, washing by
spraying water from the showerheads is not required and thus
downsizing of the apparatus is achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a flowchart illustrating a process flow of a waste
paper recycling apparatus in an embodiment of the present
invention;
[0031] FIG. 2 is a block diagram illustrating the waste paper
recycling apparatus;
[0032] FIG. 3 is a cross-sectional view illustrating a pulper of
the waste paper recycling apparatus;
[0033] FIG. 4 is a schematic view illustrating a configuration of a
papermaking unit of the waste paper recycling apparatus; and
[0034] FIG. 5 is a flowchart in a conventional processing
method.
DESCRIPTION OF THE EMBODIMENTS
[0035] The following will describe embodiments of the present
invention in accordance with the accompanying drawings. As
illustrated in FIG. 2, a waste paper recycling apparatus has a
plurality of processing units configuring a waste paper recycling
system, and the processing units includes a waste paper inlet 1, a
pulper 9, a deinking unit 11, a papermaking unit 13, a drier 14, a
finishing unit 15, a white water tank 100, and a waste deinking
liquid treating apparatus 101. The waste paper recycling apparatus
includes a control unit 700 to control operation of each processing
unit.
[0036] In the present embodiment, the waste paper inlet 1 is to
charge the pulper 9 with waste sheet paper as a recycle material.
The pulper 9 disaggregates waste paper in disaggregating water to
prepare a waste paper pulp slurry containing waste paper pulp.
Details of the waste paper inlet 1 and the pulper 9 are described
later.
[0037] The deinking unit 11 deinks the waste paper pulp slurry in a
deinking chamber 501, and separates and removes a deinked liquid
waste containing solid contents, such as fiber and ink, from the
waste paper pulp slurry. The deinking unit 11 then delivers the
deinked waste paper pulp slurry to the papermaking unit 13 and
supplies the deinked liquid waste from an outlet through a deinking
drainage system 102 to the waste deinking liquid treatment
apparatus 101.
[0038] As illustrated in FIG. 4, the papermaking unit 13 produces
wet web 12 from the deinked waste paper pulp slurry. The
papermaking unit 13 has a papermaking wire 42, composed of a mesh
belt wound on a plurality of rollers 41, and a head box 43 to pour
the deinked waste paper pulp slurry onto the papermaking wire
42.
[0039] The papermaking wire 42 has an endless path composed of an
outward portion from the head box 43 to a drying roller 49
described later, a transition portion covering part of the drying
roller 49, and a return portion from the drying roller 49 back to
the head box 43.
[0040] The outward portion of the papermaking wire 42 is provided
with a drainer 44 and a suction device 45 near the head box 43
below the papermaking wire 42. The drainer 44 wipes water dripping
from a lower surface of the papermaking wire 42 by sliding contact
with the lower surface of the papermaking wire 42. The suction
device 45 sucks water from the wet web 12 via the papermaking wire
42.
[0041] Further, downstream of the suction device 45, a plurality of
squeezing rollers 41a and 41b are located across the papermaking
wire 42. The squeezing rollers 41a and 41b squeeze the wet web 12
on the papermaking wire 42 passing through between both rollers.
Given the water content of the wet web 12 immediately after being
supplied from the head box 43 to the papermaking wire 42 as 100
weight %, the wet web 12 having passed through the squeezing
rollers 41a and 41b has a water content from 60 to 65 weight %.
[0042] The drier 14 is provided with the drying roller 49 to dry
the dewatered wet web 12. The drying roller 49 has a built-in
heating device. A canvas belt 51 having an endless path wound on a
plurality of rollers 50 covers part of the drying roller 49 in part
of the endless path. In the drier 14, the wet web 12 is sandwiched
between the canvas belt 51 and an outer peripheral surface of the
drying roller 49 and the wet web 12 is heated by the drying roller
49 for drying.
[0043] Between the transition portion of the papermaking wire 42
and the canvas belt 51, a calender roller 50a to press the wet web
12 against the drying roller 49 is provided.
[0044] At an outward terminal position of the canvas belt 51, a
scraper 111 releases dry paper 61 thus dried from the drying roller
49 to guide it to the finishing unit 15.
[0045] The finishing unit 15 applies finishing process to the dry
paper 61 obtained by drying the wet web 12 and delivers recycled
paper 62 obtained in the finishing process to a paper holder 63.
The finishing unit 15 is provided with a metallic cutting device 60
and a slitting device 112 to cut the dry paper 61 in predetermined
size.
[0046] The white water tank 100 retains white water, which is
wastewater containing waste paper pulp flowing from the papermaking
unit 13 through a papermaking drainage system 104. The white water
tank 100 recirculates the white water, through white water
recirculation systems 105 and 106, to the respective sections in
the waste paper recycling system. The white water recirculation
system 106 in communication with the pulper 9 supplies white water
as disaggregating water and dilution water to a stirring chamber
901 of the pulper 9.
[0047] The white water tank 100 is connected to water supply piping
108 to supply service water from the source of water supply,
service water piping 107 in this example. The water supply piping
108 is provided with a main valve device 109 for emergency stop
composed of an electromagnetic valve.
[0048] The waste deinking liquid treatment apparatus 101 treats the
deinked liquid waste supplied from the deinking unit 11 through the
deinking drainage system 102 and separates solid components, such
as fiber, ink, and toner of the waste paper pulp, from liquid phase
components.
[0049] As illustrated in FIG. 3, the waste paper inlet 1 is located
above the stirring chamber 901 of the pulper 9 to charge the pulper
9 directly with waste paper as a recycle material remaining in the
form of sheet paper. The waste paper inlet 1 has a position
maintaining unit 203 to maintain the sheet paper in a standing
position. The position maintaining unit 203 is composed of a
vertically open rectangular frame with an upper opening and a lower
opening, and the lower opening serving as an inlet faces an upper
opening of the stirring chamber 901. The lower opening of the
position maintaining unit 203 is covered with a sliding bottom
plate 206 as a bottom portion of the position maintaining unit 203.
The sliding bottom plate 206 is movable in sliding directions to
open and close the lower opening.
[0050] The waste paper inlet 1 includes a weight sensor, not shown,
to measure the weight of the waste paper loaded into the position
maintaining unit 203, in which the weight sensor is composed of a
load cell and the like.
[0051] The position maintaining unit 203 is provided with a
position maintaining auxiliary plate 203a. The position maintaining
auxiliary plate 203a divides a sheet paper loading space of the
position maintaining unit 203 into a plurality of compartments.
[0052] To secure the user safety, a cover 301 is provided to cover
the upper opening of the position maintaining unit 203. The cover
301 is provided with a transparent door 302.
[0053] The pulper 9 has, inside the stirring chamber 901, a
stirring blade 902 and a rotation shaft 903 to rotationally drive
the stirring blade 902 as stirring devices. The rotation shaft 903
is rotatably supported by two upper and lower bearings 905 and 904
placed above the stirring chamber 901. The rotation shaft 903 has a
pulley 906 between the upper and lower bearings 905 and 904. The
pulley 906 is driven by a stirring blade driving motor 922 via a
belt 907 to rotate the rotation shaft 903 and the stirring blade
902. The stirring blade driving motor 922 has a torque sensor
923.
[0054] The stirring chamber 901 has an outlet 908 at the bottom of
the chamber, and the outlet 908 is connected to a transfer unit
909. The transfer unit 909 makes a transfer path to transfer the
waste paper pulp slurry disaggregated in the stirring chamber 901
to the deinking unit 11 and has a tube pump 910 as a transfer
pump.
[0055] The stirring chamber 901 has a water supply unit 911
provided facing its opening to supply dilution water to the
stirring chamber 901. The water supply unit 911 is connected to the
white water recirculation system 106 via a flow sensor 921 composed
of a vortex type flowmeter or a vane type flowmeter. The white
water recirculation system 105 is connected to the transfer unit
909 downstream of the tube pump 910 as a second water supply
unit.
[0056] The stirring chamber 901 is provided in its inside with, as
liquid level sensors to detect the liquid level of the waste paper
pulp slurry, an upper limit liquid level detection sensor 912
corresponding to an upper limit liquid level allowed to be stored
in the chamber, a lower limit liquid level detection sensor 913
corresponding to the position of the stirring blade 902 in the
chamber, and a defined residue liquid level detection sensor 914
corresponding to a defined residue liquid level when a
predetermined amount of the waste paper pulp slurry is stored.
[0057] The control unit 700 has a concentration detection unit 701.
The concentration detection unit 701 calculates the concentration
of the waste paper pulp slurry based on a weight measurement by the
weight sensor and a flow measurement by the flow sensor 921.
[0058] Actions of the above configuration are described below. The
control unit 700 controls the waste paper inlet 1, the pulper 9,
the deinking unit 11, the papermaking unit 13, the finishing unit
15, the white water tank 100 and the waste deinking liquid
treatment apparatus 101, and thereby operates the waste paper
recycling system in each processing unit.
[0059] The sliding bottom plate 206 of the waste paper inlet 1 is
placed in a full closure position, and in this state, the door 302
of the cover 301 is opened to load a bunch of sheet paper into the
frame of the position maintaining unit 203. The sliding bottom
plate 206 is moved in a slide-open direction to open the lower
opening of the position maintaining unit 203. With the opening of
the sliding bottom plate 206, the sheet paper is dropped from the
lower opening, remained in the standing position, into the stirring
chamber 901 of the pulper 9 sequentially for each compartment
divided by the position maintaining auxiliary plate 203a. The
stirring chamber 901 stores a predetermined amount of white water
supplied from the water supply unit 911 as disaggregating
water.
[0060] In the present embodiment, the stirring chamber 901 is
charged with the waste paper a plurality of times by the waste
paper inlet 1, whereas it may be charged with the waste paper at
one time.
[0061] The control unit 700 operates the stirring blade 902 in a
defiberization preparation operation mode during waste paper
charging operation of the waste paper inlet 1.
[0062] In the defiberization preparation operation mode, the
stirring blade 902 is rotated at 200 rpm as the number of
revolutions for rough tearing and spreading, which is slower than
400 rpm as the number of revolutions for stirring, to roughly tear
the charged waste paper.
[0063] In other words, as illustrated in FIG. 1, a predetermined
amount of stirring water is poured into the pulper 9 (S11), and
then waste paper is put into the pulper (S12), followed by rough
tearing (S13), and again charging waste paper (S14), followed by
rough tearing (S15).
[0064] This allows smooth defiberization even when the waste paper
put into the stirring chamber 901 earlier and the waste paper put
into the stirring chamber 901 later are mixed in the stirring
chamber 901.
[0065] In other words, aggregate of the waste paper charged earlier
is loosened and roughly torn into pieces of paper. The waste paper
charged earlier thus does not inhibit immersion of the waste paper
charged later in the disaggregating water. As a result, regardless
of the timing of waste paper charging, the waste paper is roughly
torn prior to defiberization.
[0066] The control unit 700 then operates the stirring device of
the pulper 9 sequentially in a defiberization operating mode, a
transition operating mode, and a dilution operating mode.
[0067] In the defiberization operating mode (S16), the stirring
blade 902 is rotated at 750 rpm as the number of revolutions for
defiberization to disaggregate the waste paper in a predetermined
amount of the disaggregating water stored in the stirring chamber
901. The defiberization operating mode (S16) generates a waste
paper pulp slurry with a defiberization termination concentration
of 8 weight % at the termination of disaggregating operation.
[0068] The termination of disaggregating operation is sensed from a
load measured by the torque sensor 923. The torque decreases with
the progress of defiberization, and the defiberization is defined
to be completed when the measurement by the torque sensor 923
reaches a predetermined value. The termination of disaggregating
operation may also be sensed from a change in temperature of the
waste paper pulp slurry. With the progress of defiberization, the
temperature of the waste paper pulp slurry increases from
15.degree. C. to 20.degree. C. From the increase in temperature
during defiberization, the termination of disaggregating operation
is sensed. The termination of disaggregating operation may also be
sensed by timer control.
[0069] In the transition operating mode (S17), dilution water is
supplied from the water supply unit 911 to the waste paper pulp
slurry of the stirring chamber 901 while the stirring blade 902 is
rotated at 750 rpm as the number of revolutions for defiberization
to stir the waste paper pulp slurry. The waste paper pulp slurry at
the defiberization termination concentration (8 weight %) is then
diluted to the transition termination concentration (6 weight %) at
the termination of transition operation.
[0070] At this point, the control unit 700 calculates a deficiency
of dilution water, i.e., an amount of dilution water required to
make the waste paper pulp slurry at the transition termination
concentration (6 weight %) based on the amount of charged waste
paper, i.e., the amount of waste paper measured by the weight
sensor. The calculated amount of dilution water is then supplied
from the water supply unit 911 to prepare the waste paper pulp
slurry at the transition termination concentration (6 weight %).
The termination of transition operation is sensed by timer control
(S18).
[0071] The termination of transition operation may also be sensed
from a change in concentration of the waste paper pulp slurry. In
other words, the concentration detection unit 701 of the control
unit 700 calculates the concentration of the waste paper pulp
slurry from the weight measurement by the weight sensor and the
flow measurement by the flow sensor 921. When the water supply from
the water supply unit 911 is finished, the control unit 700
recognizes that the waste paper pulp slurry reaches the transition
termination concentration (6 weight %) to switch the transition
operating mode to the dilution operating mode at this transition
termination concentration of the waste paper pulp slurry.
Alternatively, the termination of transition operation may also be
sensed from a measurement by the torque sensor 923.
[0072] The transition operating mode is thus performed between the
defiberization operating mode and the dilution operating mode, and
in the transition operating mode, the dilution water is supplied to
the waste paper pulp slurry while the stirring blade 902 is rotated
at the number of revolutions for defiberization (750 rpm) to
promote defiberization. In other words, pieces of the waste paper
attached to the inner wall of the stirring chamber 901 in the
defiberization operating mode are incorporated into the waste paper
pulp slurry with the rise in the liquid level in the chamber. As a
result, the incorporated pieces of the waste paper are
disaggregated by the stirring blade 902 rotated at the number of
revolutions for defiberization (750 rpm) to be disaggregated into
small size capable of being supplied at least to the deinking unit
11.
[0073] This allows restriction on the residual rough pieces of the
waste paper in the waste paper pulp slurry in the dilution
operating mode and prevention of reduction in quality caused by the
pieces of paper during papermaking of the papermaking unit 13 in a
later step.
[0074] In addition, during the rise in the liquid level in the
chamber, the stirring blade 902 is rotated at the number of
revolutions for defiberization (750 rpm) and a strong stirring
action is exerted on the waste paper pulp slurry to effectively
wash away the pieces of paper attached to the inner chamber wall
with the waste paper pulp slurry and thus the inner chamber wall is
washed. Accordingly, conventional washing by spraying water from
the showerheads is not required and thus downsizing of the
apparatus is achieved.
[0075] In the dilution operating mode (S19), the dilution water is
supplied from the water supply unit 911 to the waste paper pulp
slurry in the stirring chamber 901 while the stirring blade 902 is
rotated at 400 rpm as the number of revolutions for stirring, which
is slower than 750 rpm as the number of revolutions for
defiberization, to stir the waste paper pulp slurry. The waste
paper pulp slurry at the transition termination concentration (6
weight %) is then diluted to the dilution termination concentration
(4 weight %) at the termination of dilution operation.
[0076] The dilution termination concentration (4 weight %) is a
concentration to supply the waste paper pulp slurry to the deinking
unit 11 with the tube pump 910, and the dilution termination
concentration is set in accordance with the specifications of the
tube pump 910. When the concentration of the waste paper pulp
slurry reaches 4 weight % (S20), the dilution operating mode is
finished (S21).
[0077] Then, the stirring blade 902 is rotated to stir the waste
paper pulp slurry while the tube pump 910 of the transfer unit 909
is driven, thereby obtaining the waste paper pulp slurry from the
outlet 908 of the stirring chamber 901 for transfer to the deinking
unit 11.
* * * * *