US20170183816A1

US20170183816A1 - Waste paper recycling apparatus

Info

Publication number: US20170183816A1
Application number: US15/381,257
Authority: US
Inventors: Tadashi Terai; Yoshihisa Higashimoto
Original assignee: Duplo Seiko Corp
Current assignee: Duplo Seiko Corp
Priority date: 2015-12-24
Filing date: 2016-12-16
Publication date: 2017-06-29
Also published as: CN106917310B; JP2017115259A; CN106917310A

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.

Description

CROSS REFERENCE TO RELATED APPLICATION

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

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

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.
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.
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).
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.
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.
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.
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.
The showerheads, however, cause increase in complexity and size of the apparatus configuration and thus cause increase in costs.
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

To solve the above problems, a waste paper recycling apparatus of the present invention includes:
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.
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
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.
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,
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.
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

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.
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

FIG. 1 is a flowchart illustrating a process flow of a waste paper recycling apparatus in an embodiment of the present invention;

FIG. 2 is a block diagram illustrating the waste paper recycling apparatus;

FIG. 3 is a cross-sectional view illustrating a pulper of the waste paper recycling apparatus;

FIG. 4 is a schematic view illustrating a configuration of a papermaking unit of the waste paper recycling apparatus; and

FIG. 5 is a flowchart in a conventional processing method.

DESCRIPTION OF THE EMBODIMENTS

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.
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.
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.
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.
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.
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.
Further, downstream of the suction device 45, a plurality of squeezing rollers 41 a and 41 b are located across the papermaking wire 42. The squeezing rollers 41 a and 41 b 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 41 a and 41 b has a water content from 60 to 65 weight %.
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.
Between the transition portion of the papermaking wire 42 and the canvas belt 51, a calender roller 50 a to press the wet web 12 against the drying roller 49 is provided.
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.
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.
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.
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.
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.
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.
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.
The position maintaining unit 203 is provided with a position maintaining auxiliary plate 203 a. The position maintaining auxiliary plate 203 a divides a sheet paper loading space of the position maintaining unit 203 into a plurality of compartments.
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.
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.
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.
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.
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.
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.
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.
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 203 a. The stirring chamber 901 stores a predetermined amount of white water supplied from the water supply unit 911 as disaggregating water.
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.
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.
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.
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).
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.
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.
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.
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.
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° C. to 20° 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.
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.
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).
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.
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.
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.
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.
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.
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).
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.

Claims

What is claimed is:

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

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

6. The waste paper recycling apparatus according to claim 3, wherein