U.S. patent application number 11/922880 was filed with the patent office on 2009-05-07 for method of papermaking.
This patent application is currently assigned to HSP HANBAI KABUSHIKI KAISHA. Invention is credited to Hideo Tachikawa, Hiroshi Tachikawa, Tsugio Tachikawa.
Application Number | 20090114353 11/922880 |
Document ID | / |
Family ID | 37570221 |
Filed Date | 2009-05-07 |
United States Patent
Application |
20090114353 |
Kind Code |
A1 |
Tachikawa; Tsugio ; et
al. |
May 7, 2009 |
Method of Papermaking
Abstract
An inventive method of papermaking can be provided for creating
an optimum wet end environment. In a preferred method, an aqueous
solution of sodium hypochlorite acidified by hydrochloric acid to
have a pH of greater than or equal to 4 and less than 7 and
adjusted to have an effective chlorine concentration of 1,000 to
10,000 ppm, preferably 3,000 to 8,000 ppm is prepared and charged
to a white water pit in a manner to be effective chlorine
concentration therein to greater than or equal to 0.5 ppm. Before a
step of papermaking, it is preferred that aqueous solution sodium
hypochlorite having pH of greater than or equal to 4 and less than
7 is added continuously or intermittently to a raw material water
with the expectation that at breaching a residual chlorine
concentration becomes greater than or equal to 500 ppm.
Inventors: |
Tachikawa; Tsugio; (Hyogo,
JP) ; Tachikawa; Hiroshi; (Hyogo, JP) ;
Tachikawa; Hideo; (Hyogo, JP) |
Correspondence
Address: |
SMITH PATENT OFFICE
1901 PENNSYLVANIA AVENUE N W, SUITE 901
WASHINGTON
DC
20006
US
|
Assignee: |
HSP HANBAI KABUSHIKI KAISHA
Hyogo
JP
|
Family ID: |
37570221 |
Appl. No.: |
11/922880 |
Filed: |
December 14, 2005 |
PCT Filed: |
December 14, 2005 |
PCT NO: |
PCT/JP2005/022941 |
371 Date: |
February 21, 2008 |
Current U.S.
Class: |
162/29 |
Current CPC
Class: |
Y02W 30/648 20150501;
D21C 9/12 20130101; D21C 9/14 20130101; D21C 5/02 20130101; C02F
1/66 20130101; D21F 1/66 20130101; C02F 2103/28 20130101; C02F 1/76
20130101; C02F 2303/04 20130101; C02F 2209/29 20130101; D21H 17/11
20130101; Y02W 30/64 20150501 |
Class at
Publication: |
162/29 |
International
Class: |
D21C 11/00 20060101
D21C011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2005 |
JP |
2005-181533 |
Claims
1. A method of papermaking which comprises subjecting a papermaking
raw water to a treatment of de-lignin and de-inking and adding some
necessary treating agents into a white water wherein in place of
one or more of the treating agents an aqueous solution containing
ions of hypochloric acid or chlorous acid is prepared to have pH of
greater than or equal to 4 and less than 7 and charged continuously
or intermittently into the white water with the expectation that at
the time of charging a residual chlorine concentration is kept at
the concentration of more than 0.5 ppm.
2. A method of papermaking according to claim 1, which further
comprises a step of bleaching a papermaking raw water wherein an
aqueous solution containing ions of hypochloric acid or chlorous
acid is prepared to have pH of greater than or equal to 4 and less
than 7 and charged continuously or intermittently into the white
water with the expectation that at the time of bleaching a residual
chlorine concentration in the papermaking raw water is kept at the
concentration of more than 500 ppm.
3. A method of papermaking according to claim 1, which further
comprises making the white water circulating wherein in place of
one or more of the treating agents an aqueous solution containing
ions of hypochloric acid or chlorous acid is prepared to have pH of
greater than or equal to 4 and less than 7 and charged continuously
or intermittently into the white water with the expectation that at
the time of charging a residual chlorine concentration is kept at
the concentration of less than 20 ppm, preferably less than 10
ppm.
4. A method of papermaking according to claim 1, which further
comprises making the white water circulating wherein an aqueous
solution containing ions of hypochloric acid or chlorous acid is
prepared and charged into the white water with the expectation that
at the time of circulating a residual chlorine concentration in the
white water is kept at the concentration of less than 5 ppm,
preferably 0.1 to 3 ppm.
5. A method of papermaking according to claim 1, which further
comprises making the white water circulating wherein an aqueous
solution containing ions of hypochloric acid or chlorous acid is
prepared and charged into the white water with the expectation that
at the time of circulating a residual chlorine concentration out of
the white water circulating is kept at the concentration of less
than 1 ppm.
6. A method of papermaking according to claim 1, which further
comprises making the white water circulating wherein an aqueous
solution containing ions of hypochloric acid or chlorous acid is
prepared and charged into the white water with the expectation that
according to a value of BOD or COD in a waste water a residual
chlorine concentration in the waste water is kept at the
concentration of more than 10 ppm.
7. A method of papermaking according to claim 6, wherein the waste
water kept at the concentration of more than 10 ppm is re-used for
processing water.
8. A method of papermaking from used paper, wherein number of
bacterium in the circulating white water is controlled to be kept
less than 10.sup.5, preferably 10.sup.4.
9. A method of papermaking which comprises subjecting a papermaking
raw water to a treatment of de-lignin and de-inking, bleaching a
white water, papermaking the white water and then discharging a
waste water treated by necessary treating agents, wherein in place
of one or more of the treating agents an aqueous solution
containing ions of hypochloric acid or chlorous acid is prepared to
have pH of greater than or equal to 4 and less than 7 and charged
continuously or intermittently into the white water in one or more
of the all step, change of oxidation-reduction potential before and
after charging the aqueous solution in the white water and the
waste water is measured and the charging amount of the aqueous
solution is automatically controlled according to the measuring
signal.
10. A method of paper making according to claim 9, wherein pH value
before and after charging the aqueous solution in the white water
and the waste water is measured together with the
oxidation-reduction potential.
Description
THE FIELD OF TECHNOLOGY
[0001] The invention relates to a method which could simplify the
chemical treatment in the paper making and provide an optimum wet
end environment.
THE BACKGROUND OF TECHNOLOGY
[0002] Under upsurge of the concern of the global environment
problem and neutralization of the condition of the paper making,
the feed condition of the pulp raw material is increasing
rigorously. Among them, increment of the mix quantity about DIP or
coated broke, not only causes a lower product rate, lower physical
properties of a wet end concerning filter water or lower paper
quality such as strength and size degree, etc, but also causes the
paper making machine breakdown because of the dirty. In order to
repress the productivity and operability mentioned above, usually
many kinds of chemical agent or chemical in great quantities have
been used, resulting in that the paper making machine become dirty
more.
[0003] Moreover, together with neutralization of the paper making
process, the slime trouble caused by microorganism also increases
immediately and lowering effects of the aluminum sulfate causes the
inclusions such as pitch, anion trash, etc to be accumulated inside
the system continuously. Nowadays, how to deal with the dirty of
the paper making machine has become the hardest problem in raising
productivity and operation. In the system of paper making machine,
the slime trouble caused by microorganism and the inclusions of
pitch, anion trash, etc become main reasons of the dirty.
[0004] Therefore, we usually propose to use organic antibacterial
agent such as slime controlling agent to control the slime trouble.
On the other hand, against the inclusions of the pitch or anion
trash problems, we usually propose to use scale controlling agent
and pitch controlling agent.
[0005] However, in the system of the whitewater circulation in the
paper making factory, during a bleaching process of the pulp, a
reduction bleach agent is remaining therein and processing water is
also coming from a smoke taking off sulfuric device, resulting in
existence of much reductive materials, such as the sodium sulfite,
potassium sulfite with high concentration. Also, latex used for a
binding agent in a coating solution, once be corrupted, makes the
quantity of the germ be increased, and it will produce some
reductive smelling materials, such as hydrogen sulfide, mercaptan
and etc.
[0006] In the system of the processed water, if there are reductive
materials mentioned above, previous antibacterial agents react with
the reductive materials firstly before they react with the
microorganism germ body. Therefore, the antibacterial agents become
not able to play a role. As a result, it will bring some barriers
to the stable operation of the paper making machine. Also, it will
produce such a reductive material as hydrogen sulfide when the
starch and latex, etc are corrupted constantly. Thus, the function
of the antiseptic agents will be obstructed significantly, which is
nowadays a big problem.
[0007] As the antibacterial method on condition of the existence of
the reductive material, we usually choose the chlorite or bromite
(bromous acid salt) to oxidize and decompose the reductive material
first, and then use the previous organic antibacterial agent
(Japanese Patent Kokai Hei 6-142661), or to use the organic
antibacterial agent which is not under the influence of the
reductive material or combination materials mixed with organic
antibacterial agent (Japanese Patent Kokai Hei 7-258002).
SUMMARY OF THE INVENTION
[0008] However, we first use the chlorine series inorganic
antibacterial agent which will make the reductive material oxidized
and decomposed completely, and then use the previous organic
antibacterial agent. Thus, it will remain a lot of effective
chlorine with strong oxidization property, so that the dyestuff
added in the product is oxidized to influence the color phase of
the paper and still decay the metals material such as pipe used
during the white water circulatory system. And the new type organic
antibacterial agent which is difficult to be influenced by the
reductive material, is effective in actual papermaking processes
with 5-20 mg/L reductive material, but when there are reductive
materials with higher concentration, we need to increase the
antibacterial agent with high concentration.
[0009] On the other hand, about the dirty problem of the paper
making machine, we usually use a slime controlling agent, a scale
controlling agent, a pitch controlling agent to deal with it.
However, there are few environments where chemical agents could
play the best role. With increasing the types of the chemical
agent, we need to adjust the management method of the chemical
agent mentioned above.
[0010] In view of the above problems, after our sharp research, the
inventor of this invention found that, if the chlorine series
oxidizing agent represented by an acidic hypochloric acid soda
(acidic sodium hypochlorite) aqueous solution, is added to a white
water after papermaking in the wet end environment, not only a
strong bactericidal effect can be obtained in place of a
conventional antibacterial agent, but also as the scale controlling
agent and pitch controlling agent, there can realized reduction of
the decomposition of the organic and the influence of anion trash
which would be caused by the various admixture. Therefore, a first
object of this invention is to provide a method wherein the
chlorine series oxidizing agent could optimize the environment of
paper making in condition of the acidity.
[0011] With the optimization of the papermaking environment, in the
bleach process before the papermaking process, we can also use the
chlorine series oxidizing series represented by an acidic
hypochloric acid soda aqueous solution for simplifying the control
of the paper making processes. Therefore, a second object of this
invention is to use the same chlorine series oxidizing agent not
only in the papermaking processes but also in the bleach processes.
Also, with the optimization of the papermaking environment, the
possibility of reuse the papermaking drainage also increases.
Therefore, a third object of this invention is to deal with the
papermaking drainage, so that the processed water can be reused as
industrial water.
[0012] Therefore, according to a first aspect of the present
invention is a method of papermaking which comprises subjecting a
papermaking raw water to a treatment, adding some necessary
chemical treating agents into a white water wherein in place of one
or more of the chemical treating agents an aqueous solution
containing ions of hypochlorous acid or chlorous acid adjusted to
have pH of greater than or equal to 4 and less than 7 is prepared
and charged continuously or intermittently into the white water
with the expectation that at the time of charging a residual
chlorine concentration is kept at the concentration of more than
0.5 ppm, more ideal is more than 1 ppm.
[0013] The dilution aqueous solution that contains ions of
hypochlorous acid or chlorous acid, is one containing not only the
hypochlorous acid and chlorous acid, but also their sodium or
potassium salts in an acidic condition and also bromous acid,
hypobromite and their sodium and potassium salt, etc. However, in
this invention, it is preferred to use the sodium hypochlorite
aqueous solution, having a concentration between 1000 ppm-10000
ppm, preferably 3000 ppm-8000 ppm, at a weak acidity scope of pH of
4-6.5, because they can show a strong disinfect property, a strong
organic matter decomposition property, and a strong
diselectrification property of anion trash.
[0014] In this invention, the purpose of adding a hypochlorous acid
solution is not only to control the slime, but also to control the
pitch and the anion trash. Therefore, it is preferable to add an
aqueous solution containing ions of hypochloric acid or chlorous
acid adjusted to have pH 4-7 continuously or intermittently into
the white water after papermaking with the expectation that at the
time of charging a residual chlorine concentration is kept at the
concentration of less than 20 ppm, preferably less than 10 ppm. In
the white water circulatory system, it is preferable to add an
aqueous solution contains ions of hypochloric acid or chlorous acid
to have a pH 4-7 into the circulating white water with the
expectation that at the time of circulating a residual chlorine
concentration in the white water is kept at the concentration of
less than 5 ppm, preferably 0.1 to 3 ppm, and a residual chlorine
concentration out of the white water circulation system is kept at
the concentration of less than 1 ppm. On the other hand, in order
to take the paper making drain in to make re-use after papermaking,
it is preferable to add an aqueous solution containing ions of
hypochloric acid or chlorous acid adjusted to have a pH 4-7 into
the white water with the expectation that according to a value of
BOD or COD in a waste water, a residual chlorine concentration in
the waste water is kept at the concentration of more than 10 ppm.
The waste water kept at the concentration of more than 10 ppm is
re-used for processing water.
[0015] In a case of bleaching a papermaking raw water, an aqueous
solution containing ions of hypochloric acid or chlorous acid
adjusted to have pH of greater than or equal to 4 and less than 7
is charged continuously or intermittently into the white water with
the expectation that at the time of bleaching a residual chlorine
concentration in the papermaking raw water is kept at the
concentration of more than 500 ppm. It can simplify several bleach
steps, and it is easy to manage the medicine control. Moreover,
preferably it can raise the processing effect in the papermaking
mentioned above. The purpose of the bleach process is to simplify
several bleach after de-lignin. However, the inventive bleaching
method can be applied to the wastepaper after de-inking and the
bleaching process may be applied at the same time of de-inking.
[0016] In the bleaching process, the inventive aqueous solution
contains ions of hypochloric acid or chlorous acid can be used, in
place of them it may contain not only the sodium hypobromite, but
also the potassium hypobromite, etc. However, it is preferable to
use an aqueous solution containing 1000-20000 ppm, preferably
3000-10000 ppm of sodium hypochlorite and adjusted to a pH of 4-7,
preferably to a pH of 4.5-6.5. The bleaching process is preferably
carried out at a pulp concentration of 3 to 30 wt. % in the
papermaking raw water. When the concentration of the pulp is high,
it is recommendable to add the solutions which contain the
hypochlorite in many times. At the first stage, it is preferable to
add the first hypochlorite solution of more than 3000 ppm and the
second, the third solution with a lower concentration of
hypochlorite. It is our surprising that the solution containing
ions of hypochlorous acid can not only show a effective disinfect
effect against microorganism within a scope of 4-6.5 of pH, but
also shows a same strong bleach effect as ozone or chlorine
dioxide.
[0017] The present invention is also a method of papermaking which
comprises subjecting a papermaking raw water to a treatment of
de-lignin and de-inking, bleaching a white water, papermaking the
white water and then discharging a waste water treated by necessary
chemical treating agents, wherein in place of one or more of
conventional chemical agents an aqueous solution contains ions of
hypochloric acid or chlorous acid adjusted to have pH of greater
than or equal to 4 and less than 7 is charged continuously or
intermittently into the white water in one or more of the all
steps, measuring change of Oxidation-Reduction Potential before and
after charging the aqueous solution in the white water and the
waste water and finally controlling the charging amount of the
aqueous solution automatically according to the measuring signal.
For example, compared with the calibration curve which is prepared
before, a suitable quantity of the solution can be controlled
according to this comparing signal. In this invention, the solution
containing ions of hypochloric acid or chlorous acid adjusted to
have a pH of weak acid is charged continuously or intermittently.
Therefore, by measuring the oxidation-reduction potential and the
pH, the control accuracy can be raised. Thus, it is more
preferred.
[0018] In a papermaking process after the bleaching process, the
hypochlorous acid can exert the effective microorganism disinfects
effects on condition that the pH is 4-6.5 and the concentration of
the residual chlorine is more than 0.4 ppm. By controlling the
quantity of bacteria less than 10.sup.4, it can exert effect of the
slime control. But in this invention, we have to resolve the
organic compound and pitch, etc and clean the anion trash, so it is
more preferred to set the concentration of the residual chlorine at
0.5-1 ppm. However, if it exceeds 10 ppm, the hypochlorous acid
solution can not be all consumed in the whitewater pit and will
remain in the circulation white water. If remain a little, it will
not influence the environment of papermaking. So we can set the
concentration of the residual chlorine to less than 20 ppm.
[0019] The aqueous solution which contains ions of hypochloric acid
or chlorous acid in the papermaking process can be instead of the
electrolysis aqueous solution that contains ions of hypochloric
acid or chlorous acid. But, it is preferred to use sodium
hypochlorite or sodium chlorite which do not produce chlorine gas,
and having the pH of 4-7 ppm, especially less than 6.5 ppm, and the
concentration between 1000 and 20000 ppm, especially between 3000
and 10000 ppm. The aqueous solution that contains hypochloric acid
can be made by the Steri Mixer made in HSP Co. Ltd at the spot.
When made at the spot and for input, it is preferred to make the
solution having a pH of 4 to 6.5 ppm, and a concentration between
5000 and 20000 ppm, especially between 5000 and 10000 ppm. When
made at the other factory, it must be carried with the tank lorry,
so it is preferred that the pH is from 5 to 6.5 ppm, the
concentration is from 3000 to 8000 ppm.
[0020] Usually, when we make the aqueous solution with high
concentration of sodium hypochlorite under hydrochloric acid
acidity, if the pH descends to less than 4, there will be a
chlorine gas, so we use a dilute hydrochloric acid of less than
30%, more preferably less than 15%, most preferably less than 10%.
To mix with the aqueous solution of sodium hypochlorite of pH 4 to
6.5, more preferably pH 5 to 6 and the concentration of the
effective chlorine of is diluted to from 3000 and 10000 ppm with
water, so that we can produce the aqueous solution of high
concentration sodium hypochlorite which is suitable for white water
without producing chlorine. Especially, when we modulate the acidic
aqueous solution of sodium hypochlorite, it is preferred to make pH
much lowered below a predetermined value with a pH regulator such
as the inorganic agent that do not affect the effective chlorine,
for example KHCO.sub.3, carbonic acid hydrogen potassium or
NaHCO.sub.3, carbonic acid hydrogen sodium.
[0021] As noted above, if we add the aqueous solution that contains
ions of hypochloric acid or chlorous acid, which shows a weak
acidity and the effective chlorine concentration of 1000 to 20000
ppm, more preferably 3000 to 10000 ppm to the white water of the
wet end after the papermaking on condition of acidity. As shown in
FIG. 3, the environment of the wet end of the papermaking can be
improved by the present invention.
[0022] (1) It shows disinfect effect powerfully and need not
addition of the slime controlling agent. And by keeping the
concentration of the remain chlorine to 0.1-3, more preferably than
5 ppm, the papermaking from used paper can be realized, wherein
number of bacterium in the circulating white water is controlled to
be kept less than 10.sup.5, preferably 10.sup.4.
[0023] (2) It makes anions attached to the cellulose to be neutral,
so that the dosage of the paper strengthen agent can be reduced by
a degree of 20-35%.
[0024] (3) Oxidation of the hypochloric acid water can resolve
ester part of the vinyl or acrylic compounds, etc. Thus, the dosage
of the pitch control agents is reduced by a degree of 20-30%.
[0025] (4) It can decompose organic compounds and clean or reduce
the influence of the various admixture anion trash, by which the
effect of the chemical agent added to the breakdown processing can
be improved with maximum
[0026] (5) It can decompose the organic matter such as hydrogen
sulfide etc, so that we can get a good deodorant effect. And
drainage COD can be also reduced by decomposition of the organic
matter.
[0027] (6) By using the chlorine series oxidizing agent which is
represented by acidic sodium hypochlorite solution, we can carry
out the drainage with a further processing, and reuse it as the
industry water.
[0028] (7) By using the inventive chlorine series oxidizing agent
which is represented by acidic sodium hypochlorite solution to
bleach the papermaking raw water after a treatment of de-lignin and
de-inking, it can enhance the effect that mentioned above (1) to
(6), and simplify the whole papermaking processes of the chemical
agent treatment extremely.
[0029] (8) By measuring the redox potential of the aqueous solution
that contains ions of hypochloric acid or chlorous acid adjusted to
be weak acidity before and after discharging, together with the pH,
it can control the total chemical agent management in the
papermaking processes.
[0030] These and other objects and advantages will be apparent from
the drawings and the following description of embodiments according
to the present invention.
BRIEF EXPLANATION OF THE DRAWINGS
[0031] FIG. 1 is a schematic view of a white water circulation
system provided with a hypochlorite water supply system.
[0032] FIG. 2 is a schematic view showing the specific examples of
the control system in the invention.
[0033] FIG. 3 is a view showing mechanism of the method of
papermaking according to the present invention.
[0034] FIG. 4 is a schematic view of the examples of the system in
case of waste paper in the invention.
[0035] FIG. 5 is an outline view of the overall structure of the
best way to deodorize of the paper making equipment in the
invention.
[0036] FIG. 6 is a vertical view of an embodiment of the treatment
room according to the present invention.
[0037] FIG. 7 is a side view of the structure of the treatment room
mentioned above.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] Mixed the 10% dilution hydrochloric acid with the 12% sodium
hypochlorite solution, in the range that the pH is 5-7, dilute the
concentration of the effective chlorine to 3000-10000 ppm with
water, (Sometimes we call it hypochlorous water in the following).
At this time, use the manufacturing device of the aqueous solution
that contains hypochloric acid--Steri Mixer which is made in HSP
Co. Ltd.
EXAMPLE 1
[0039] FIG. 1 is the schematic view of the wet end environment
control system of the white water circulation in the papermaking
process used to a conventional wastepaper raw material. The
whitewater after papermaking in the papermaking machine 100 should
be sent to the whitewater pit 110 first in which the slime can be
treated, then a part of it will be circulated to the stock inlet
150, the other part will be sent to the drainage pit 120. On the
other hand, the pulp raw materials will be sent to the seed box 140
from the de-inking process pit 160, and through the screening pit
130, be sent to the stock inlet 150, finally arrive at the
papermaking machine 100. Here is a white pit 110 in a papermaking
machine 100, but usually there are four papermaking machines in
tandem and there are layout of the white water pit 110(a), (b), (c)
and (d) on every papermaking machine.
[0040] In the hypochlorite water supply system 200, according to
the direction of the arrow 170, the hypochlorous water is supplied
continuously for the white water pit (a), (b), (c) and (d). There
measurement devices D1-D4 are arranged on all pits which is to
measure the concentration of the residual chlorine in the white
water, and the measurement signal 80 is feedback to the water
supply system of the hypochlorous water, and the supply is
adjusted. The measurement device is made up of an
oxidation-reduction potential meter, but it is preferred to use the
meter with a pH meter. We have to prepare a calibration curve based
on change of oxidation-reduction potential caused by a residual
chlorine before and after charging and compare a measuring signal
with the calibration curve to adjust the supply of the hypochlorous
water. Control of the supply may be done. Furthermore, we also can
measure out the residual chlorine at suitable positions in the
whitewater circulatory system.
[0041] As shown in FIG. 2, the hypochlorous water supply system 200
can be made. Namely, from the solution tank 1 with sodium
hypochlorite or sodium chlorite and diluted hydrochloric acid tank
2, through a constant rate pump 3 and 4, the aqueous solution of
the diluted hydrochloric acid and sodium hypochlorite are sent to
the mixer 5 and 6. In addition, industrial water is supplied to the
mixer 5 and 6 from the other channels. Here, the aqueous solution
of the diluted hydrochloric acid and sodium hypochlorite is mixed
with the industrial water to be diluted. So that, the pH is
adjusted to 4-6.5 and the concentration is adjusted to 1000-10000
ppm, more preferably 3000-8000 ppm. The aqueous solution of the
dilute sodium hypochlorite is adjusted in the mixer 5 and 6 and
supplied by the pipe of the whitewater pit 110 or the chest
discharge pit that connect to the water end. At this pipe, there is
provided a generated water header, and a control valve at the
generated water header. The generated water header is used to
adjust the quantity of the aqueous solution of the dilution sodium
hypochlorite to be charged in the whitewater pit of water end or
the chest discharge pit. 10 is a power control panel, it controls
the quantity of the water, the hypochlorous acid soda, the chlorite
soda and the dilute hydrochloric acid that is supplied to the
mixer, and it also control the control valve of the pipe 9 so that
to control the quantity of the hypochlorous acid that supplied to
the whitewater pit 110, drainage pit 120. Furthermore, 7 is the
hypochlorous acid auxiliary tank, 8 is the dilute hydrochlorous
acid auxiliary tank.
[0042] Usually, a measuring device which is used to measure the
concentration of the residual chlorine in whitewater is attached to
the whitewater pit or chest drainage pit, send this measuring
signal to the power control panel 10, so that the input is used to
adjust the amount of dilute aqueous solution of the dilute sodium
hypochlorite or chlorite to be charged in the whitewater pit of
water end or the chest discharge pit. However, it is preferred to
control the concentration of the residual chlorine at a range of
0.1-3 ppm at most 5 ppm in whitewater circulation system, on the
other hand it is preferred to control the concentration of the
residual chlorine under 1 ppm out of the whitewater circulation
system.
[0043] By adjusting the concentration of the residual chlorine
mentioned above, in the papermaking for a waste paper, we can
control the number of the bacteria under 10.sup.5, preferably
10.sup.4. Moreover, it can be found that the concentration of the
residual chlorine does not cause production of a harmful
tri-halomethane.
[0044] In addition, in this example mentioned above, the aqueous
solution containing sodium hypochlorite of 6000 ppm with
hydrochlorous acid is prepared at the spot and used. However, a
high concentration aqueous solution of 3000 to 10000 ppm has a good
nature of storage, so it can be stored in the tank and be used.
EXAMPLE 2
[0045] The kind of the waste paper to be used: the waste paper that
recovered from the office (the first-class and middle-waste are
mixed together), will be bleached as following before
papermaking:
[0046] Analysis and evaluation/whiteness: JIS-P8123 (Hunter
method)
[0047] Residual ink quantity: By using a microscope (10 times) and
image analysis device (LA-525 made by Piaz Company), the area of
ink at the scope of a certain vision is indicated by ratio (%).
[0048] An office waste paper is put into the pulper and dissociated
therein. The condition of the pulper is 4.5% of pulp concentration,
the temperature is 26.degree. C. and NaOH is 1.0%. Then, the waste
paper pulp is dehydrated by the screw press until the pulp
concentration reaches 18%, and the pulp of the waste paper is kept
in an aging tower for 12 hours. Then, dilute the concentration of
the pulp to 3.5% and extract the pulp from the aging tower, then
dedust in the Jonson screen and FN screen, then, clean it in the
extractor. Then, after dehydrated until reach 31% by the screw
press, add the aqueous solution which contains sodium hypochlorite
of 3000 ppm at pH of 5. Then after kneading in the shredder, and
making it stay in the bleach tower, the condition of the bleach
tower is the concentration of the pulp of 29%, temperature of
36.degree. C. and the bleaching time is 10 hours. Then, dilute the
concentration of the pulp to 3.5% and extract the pulp from the
bleach tower and clean in the extractor. After dehydrated until
reach 31% by the screw press, add the aqueous solution which
contains the hypochlorite acid soda and the pH is 5, 3000 ppm, then
kneading in the shredder, and make it stay in the bleach tower. The
condition of the bleach tower is kept at the pulp concentration of
28%, the temperature of 40.degree. C., the bleaching time of 10
hours. Then, dilute to 3.5% after bleach, extract from the bleach
tower and sent it to the machine chest after adjusting the pH.
Then, dedust it by the cleaner after adjusting the concentration of
the pulp, then carrying out the same papermaking process as the
Example 1.
Comparison Example 1
[0049] As Example 2, a pulp material water is subjected to a series
of processes such as alkali processing, dehydrating, aging,
dust-removing, cleaning and dehydrating and reaches to the
concentration of the pulp to 15%. Then, the pulp water is mixed the
sodium hypochlorite by a medicine mixer, and then is subjected to a
process of cleaning. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Whiteness (%) Residual ink quantity (%)
Implementation 183.1 0.002 Comparison 173.8 0.36
[0050] The method in the invention, compared with the method of the
bleach of the hypochlorite at the condition of alkaline after
alkali processing, can give it more whiteness.
EXAMPLE 3
[0051] Put a kraft pulp (the whiteness is 47.2%, the kappa number
is 9.9) with absolute dry mass 80.0 g after the alkali oxygen
bleaching to the plastic bag. Add the 1000 ppm aqueous solution of
sodium hypochlorite at pH of 4.5 after adjusting the concentration
of the pulp until 10% by the ion exchange water, immersed for 60
minutes at the room temperature, as the first stage bleaching.
After diluting the pulp to 3% with the ion exchange water,
dehydrate and clean it with the Buchner funnel. Put the pulp into a
plastic bag, adjust the concentration of pulp to 10% with the ion
exchange water, then add the 3000 ppm solution of sodium
hypochlorite at pH of 5, immersed for 90 minutes at the room
temperature as the second stage bleaching. After adjusting the
concentration of the pulp to 3% by dilute of the ion exchange
water, there form the pulp mat by the Buchner funnel. Then
dehydrate it with the squeeze pulp machine and obtain the (the
concentration of 30.0%) pulp.
[0052] Then, put the pulp mentioned above to a plastic bag, add the
1500 ppm solution of sodium hypochlorite at pH of 6 after adjusted
the concentration to 10% by the ion exchange water. Processed for
180 minutes at normal temperature, then it will be bleached
finally. From this method, we obtain the bleaching pulp having the
whiteness of 80%. Measure the value of the potassium permanganate,
the quantity of the hexenuronic acid of the bleaching pulp and the
PC value of the bleach pulp sheet made by the bleaching pulp that
after 48 hours, and get the result of 3.0-4.0.
Comparison Example 2
[0053] Except using a sodium hypochlorite alkali solution instead
of hypochlorous acid, the operation is carried out in a same manner
as the Example 2. The pulp after dealing with the alkali sodium
hypochlorite solution is not bleached absolutely. Thus, the
whiteness is not well.
EXAMPLE 4
[0054] FIG. 4 is a flow chart of waste paper recycled paper. Put
the 3000 ppm solution of sodium hypochlorite at pH of 5-6 into the
whitewater pit, scum pit and pulp pit, considering the water
quantity therein. And adjust it to make the whitewater pit, the
scum pit to be 20-30 ppm and the pulp pit to be 10-5 ppm.
[0055] In figure, 301 is a hydrochloric acid tank, equipped with
the 10% dilute hydrochloric acid. 302 is a tank of solution of
sodium hypochlorite, equipped with the 10% aqueous solution. Send
the dilute hydrochloric acid and the sodium hydrochlorite aqueous
solution to the reserve tank 307, 308 of the first and the second
high concentration (3000 ppm) of sodium hypochlorite generator 305,
306 (the Steri Mixer made by HSP company) by pump 303, 304. In the
first and second Steri mixer 305, 306, dilute the aqueous solution
of the dilute hydrochloric acid and the aqueous solution of sodium
hypochlorite with a river water to produce the 3000 ppm aqueous
solution of sodium hypochlorite at pH of 5-6.
[0056] This aqueous solution of sodium hypochlorite is sent to the
pulp pit 310 first by the pump 309 and then to the pulper
containing the wastepaper and water. Considering the water 20
quantity and bactericidal effects therein, adjust the concentration
to 10-1 ppm. However, it is preferred to start with the high
concentration at the beginning.
[0057] Then, sent the pulp to the chest tank 311 and 311 and put
the pulp into the papermaking machine 312 from the white pit 313.
Because the white pit is circular, considering the water quantity
and bactericidal effects, put the 3000 ppm aqueous solution of
hypochlorous acid soda into the white pit, and adjust it to 100-10
ppm, especially 30-20 ppm. In addition, for the chest discharge pit
314, it is preferred to do the same disinfection and deodorization
as the pulp pit 1. For the chest tank 311, we can also do the same
process of disinfection and deodorization.
[0058] The drainage that comes from the chest tank 311 and
papermaking machine 312 is recovery at the chest discharge pit 314
and treated at the drainage treatment pit 315. Recycle sludge and
put them to sludge treatment pit 316. Recycle scum go by the sludge
pit 318 by the sludge sent back device 317. On the other hand, emit
the drainage after sludge treatment at the sludge treatment device
316.
[0059] In the scum recovery system that mentioned above,
considering the water quantity and bactericidal effects, put the
3000 ppm acidic aqueous solution of sodium hypochlorite into the
white pit, and adjust the sludge tank to 100-10 ppm, especially
30-20 ppm.
EXAMPLE 5
[0060] FIG. 5-FIG. 7 are schematic views showing best methods for
deodorant the papermaking equipment. In the figure, there is the
12% sodium hypochlorite solution in hypochlorous acid reserve tank
410 and the 9% dilute hydrochloric acid in serve tank 411. The
sodium hypochlorite solution and the dilute hydrochloric acid in
410, 411, which are sent to the auxiliary tank 421, 422 that in
manufacture device 420, which made high concentration sodium
hypochlorite solution through pipelines 414, 415 and pumps 412,
413.
[0061] There, pipelines 423, 424 extending from the auxiliary tank
421, 422 and the pipeline 423, 424 are connected into the generator
425. In the generator 425, mix 9% solution of diluted hydrochloric
acid with 12% solution of the sodium hypochlorite.
[0062] Moreover, there is connected a water pipeline 429 to the
generator 425. There are mounted a filter 4210 and a pressure
reducing valve 4211 in the middle part of the water pipeline 429.
The water that filtrated the inclusions by filter 4210 and reduced
to 0.25 Mpa by the pressure reducing valve 4211 is supplied to the
generator 425. And dilute the hydrochloric acidity aqueous solution
of sodium hypochlorite of high concentration by water to the
available chlorine of 1000-10000 ppm for example 6000 ppm and pH of
5-6.
[0063] In the generator 425 in this example, there can be made 2000
L of acidic high concentration sodium hypochlorite solution having
the concentration of the available chlorine of 6000 ppm and pH of
5-6 per every hour.
[0064] The high concentration sodium hypochlorite solution is
stored in the reserve tank 427 and sent to the scrubber 430 by the
send pump 428. In the scrubber 430, the solution is sprayed to be
the droplet with the average particle size in scope of 10 .mu.m-70
.mu.m by the vibration of ultrasonic and sent to the many spit exit
432 in the treatment room 440 (dealing space) by the blower
431.
[0065] At the entrance 440B of the treatment room 440, there
connected the pipeline 441 that come from the equipment of
papermaking factory. There layout a fans 442 that drove by motor
442A at the middle part of the pipeline 441. The fans 442 transmit
the foul air in the factory into the treatment room 440.
[0066] There is arranged a partition in the treatment room 440, to
make a tortuous path 440D bent-extending from the entrance 440B of
the treatment room 440 to the exit 440C.
[0067] Further, in the exit 440B of the treatment room 440, there
is a photocatalyst deodorant device 443. In the photocatalyst
deodorant device 443, there is installed a vector such as the wire
mesh bearing the photocatalyst. At the same time, there also is
installed a ultraviolet lights (no icon). When the UV-A wave
(wavelength 300 .mu.m.about.400 .mu.m) irradiate the photocatalyst,
such as the film of titanium dioxide, there will be the e.sup.-
(electronic) and h.sup.+ (positive hole) in the film of titanium
dioxide. The h.sup.+ (positive hole) generate to be the OH
(Hydroxy), and decompose the odor ingredients with its oxidation
ability (2 times Oxygen).
[0068] For example, when deodorizing the odor from the papermaking
factory equipment, the dilute hydrochloric acid and sodium
hypochlorite solution is sent to the generator 425, and are mixed,
and at the same time, sent the water without inclusions to the
generator 425 to dilute and make 2000 L per hour of high
concentration sodium hypochlorite aqueous solution with
hydrochloride acidity having available chlorine concentration (6000
ppm) and the pH of 5-6. The high concentration sodium hypochlorite
aqueous solution is sent to the scrubbers 430, through the
ultrasonic vibration, the droplet with the average particle size in
scope of 10 .mu.m-70 .mu.m is sprayed. The droplet with high
concentration sodium hypochlorite solution is sent to the many spit
exit 432 of the treatment room 440 by blower 431, then to be sent
to the treatment room 440.
[0069] On the other hand, when a fan 442 of the pipeline 441 is
driven by a motor 442A, the foul air in the factory is sent to
pipeline 441, and transmitted into treatment Room 440. This air
flows to the export 440C by the crank pathway 440D of the treatment
room 440. This air is deodorized by contacting the droplet with the
high concentration sodium hypochlorite solution, and be sent from
the entrance of treatment room 440 to photocatalyst deodorant
device 443. Finally it will be emitted to the atmosphere after
further deodorizing by the photocatalyst.
THE INDUSTRIAL AVAILABILITY
[0070] To sum up, this invention is effective in the papermaking
not only a used wastepaper, but also for the virgin pulp. However,
in the case of the latter, because the bacteria number, pitch and
organic compounds species are different from the wastepaper pulp,
it is preferred to adjust the concentration of the acidic sodium
hypochlorite aqueous solution considering the status of the
spot.
* * * * *