U.S. patent application number 11/662359 was filed with the patent office on 2009-11-12 for nut cracker.
Invention is credited to Torbjorn Hansson, Tomas Jarnmark.
Application Number | 20090277598 11/662359 |
Document ID | / |
Family ID | 33157508 |
Filed Date | 2009-11-12 |
United States Patent
Application |
20090277598 |
Kind Code |
A1 |
Jarnmark; Tomas ; et
al. |
November 12, 2009 |
Nut Cracker
Abstract
The present invention relates to a device and a method for
increasing the yield, as well as for enabling an increase in
productivity and an increased amount of production, and at the same
time to improve purification of process water and waste water,
respectively by decreasing the waste water flow and the amount of
pollutants in the waste water.
Inventors: |
Jarnmark; Tomas; (Stockholm,
SE) ; Hansson; Torbjorn; (Vallentuna, SE) |
Correspondence
Address: |
MANELLI DENISON & SELTER
2000 M STREET NW SUITE 700
WASHINGTON
DC
20036-3307
US
|
Family ID: |
33157508 |
Appl. No.: |
11/662359 |
Filed: |
September 12, 2005 |
PCT Filed: |
September 12, 2005 |
PCT NO: |
PCT/SE05/01324 |
371 Date: |
November 5, 2007 |
Current U.S.
Class: |
162/190 ;
162/264 |
Current CPC
Class: |
D21F 1/82 20130101; D21H
21/36 20130101; D21H 21/10 20130101 |
Class at
Publication: |
162/190 ;
162/264 |
International
Class: |
D21C 9/00 20060101
D21C009/00; D21F 1/66 20060101 D21F001/66 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2004 |
SE |
0402178-8 |
Claims
1-8. (canceled)
9. A method for rendering the flocculation more effective in the
production of cellulose-based products, comprising the steps: a)
preparing a pulp and water mixture from raw material, fresh water,
and recycled white water from step c); b) ionizing and oxidizing
the pulp and water mixture, wherein the pulp and water mixture
produced in step a) is subjected to ozone gas, and wherein the
ozone gas functions both as an oxidant and as an ionizer chemically
affecting the substances in the pulp to become more reactive and
form larger aggregates rendering the flocculation more effective in
the pulp and water mixture; and c) forming a cellulose-based
product from the ionized and oxidized pulp and producing a white
water, and supplying at least a part of the white water to step a)
as recycled white water.
10. A method according to claim 9, further comprising supplying
retention agents to the pulp and water mixture between step a) and
step b).
11. A method according to claim 9, further comprising supplying
retention agents to the pulp and water mixture between step b) and
step c).
12. A method according to claim 9, further comprising at least
partially subjecting the incoming recycled white water of step a)
to ozone gas.
13. A device rendering the flocculation more effective in the
production of cellulose-based products, comprising: a pulp and
stock preparer; forming equipment in communication with the pulp
and stock preparer, a pulp and water mixture line between the pulp
and stock preparer and the forming equipment arranged to supply the
forming equipment with the pulp and water mixture from the pulp and
stock preparer, at least one recycling line arranged to recycle
white water from the forming equipment to the pulp and stock
preparer; and ionization and oxidation equipment arranged to supply
ozone gas to the pulp and water mixture line, where the ozone gas
functions both as an oxidant and as an ioniozer chemically
affecting the substances in the pulp and water mixture to becomes
more reactive which thereby forms larger aggregates rendering the
flocculation more effective in the pulp and water mixture.
14. A device according to claim 13, further comprising a second
ionization and oxidation equipment arranged to supply ozone gas to
the at least one recycling line.
15. A device according to claim 14, wherein the second ionization
and oxidation equipment is arranged in close connection to the pulp
and stock preparer.
16. A device according to claim 13, wherein the ionization and
oxidation equipment comprises a reactor vessel having an inlet
arranged to receive a pulp and water mixture, an ozone bubbling
inlet arrange to bubble ozone gas in a lower part of the reactor
vessel, a mixer arranged to mix the pulp and water mixture, and the
ozone gas, a first outlet for the ionization and oxidation treated
pulp and water mixture, and second outlets at the upper part of the
reactor vessel arranged to receive any remaining ozone gas.
17. A device according to claim 13, wherein the first ionization
and oxidation equipment is connected to the pulp and water mixture
line in close connection to the forming equipment.
Description
TECHNICAL FIELD
[0001] The present invention relates to a device and a method for
increasing the yield (getting more final product from a given
incoming amount of raw materials and additives), as well as for
enabling an increase in productivity (amount per time unit) and an
increased amount of production (amount of production per given
amount of pollutant to an end recipient), and at the same time to
improve purification of process water and waste water,
respectively, by decreasing the waste water flow and the amount of
pollutants in the waste water. The method comprises increased
recycling (recovery, closing) of process water, in combination with
utilization of substances to be included as materials in an end
product formed, instead of constituting pollutants in the waste. At
the same time, equivalent or improved dewatering properties are
achieved in the production process, thereby enabling increased
productivity and/or amount of end product formed, in relation to
the maximum amount of effluent to the recipient allowed for the
activity.
[0002] These effects are achieved by introducing, in or between any
one or several of the water processing steps of the entire
production, a new step based on an effect that can be achieved by
certain strong oxidizing agents, preferably ozone. The method means
hereby that the oxidizing agent functions both as a type of ionizer
(polarizer) of, as well as a type of catalyst for polarization
between, particles, substances and additives suspended in the
water. The effect is influenced by factors such as the
concentration of oxidizing agent, the degree of installation,
position and order of water flows in the process, mixing methods,
suspension characteristics of pollutants, choice and properties of
chemical additives (retention agents, etc.), dosage of additives
and dosing positions, as well as other parameters. Hence, the said
effect goes beyond prevailing and common effects that can be
achieved by strong oxidizing agents and that are used, to a limited
degree, in this type of industry in order among other things to
kill microbiological cultures, to decompose pollutants comprising
COD and BOD, to bleach substances in the end product, etc., as is
known from FI 110683B, e.g.
[0003] The method results in an economical gain, by decreasing the
discharge of substances (pollutants) in the waste water, instead to
be recycled to the process as raw materials, and by enabling an
increased productivity and/or production capacity by improved
dewatering properties for the web of material formed during
production.
BACKGROUND
[0004] The following background and description focuse on process
water in pulp and paper industries, but the invention is not
limited to the fields of application used to exemplify the
technique and its use. The technique is applicable on other types
of process industries having substances present in the process
water.
[0005] Large amounts of water are used in the production processes
of pulp and paper industries. It is an objective for this sector of
the industry among other things to reduce the amount of pollutants
discharged, as well as the amount of water discharged (waste
water), also meaning that the amount of externally added fresh
water is reduced. There is a strive to achieve this by increasing
the amount substances used in the production, which substances
would otherwise be released in the form of pollutants in order
thereafter to be made subject for further purification,
decomposition and final depositing in the environment.
[0006] This objective arises by a) gradually increased
requirements, established by the authorities and relating to
amounts of pollutant effluents allowed from the process industries,
as well as b) the need for the industry constantly to try to
increase productivity and profitability by increasing the
utilisation of added raw materials, decreasing the amount of
cost-increasing additives, and by trying to increase
production.
[0007] The demands on decreasing of effluents are constantly
raised, both as a consequence of common and constant technical
improvements, but also in order to encourage new technical
improvements with the aim of environmental control and a decreased
environmental impact. Therefore, it is an important and central
issue to the line of business to develop new methods for decrease
of effluents and for improvement of profitability, whenever
compatible.
[0008] As such, decreased effluents give the possibility to
increase production within allowed/authorized effluent limits.
Nowadays, various types of environmental certificates are awarded
if you are below stipulated limits, which may result in marketing
benefits.
[0009] The industry strives to accomplish so called closed systems
in the production process, concerning internal process water, which
means that efforts are made to re-use (recycle) most possible of
the process water, thereby to minimize the amount of waste water
and of course consequently also the amount of added fresh water. In
this context, waste water means material-containing (polluted)
process water that is led to an external purification plant outside
the process plant, and thereafter, after processing, to the
recipient.
[0010] The quality of recycled process water tends always to be
gradually impaired at increased "closing" or re-use (degree of
recycling) in the plant/mill. In turn, this leads to a gradual
quality impairing effect, both on the actual production process and
on the product produced in the plant/mill. This is a central
problem.
[0011] External waste water purification takes place by a
combination of chemical, physical and biological purification
methods. It is of utmost importance to minimize the amount of
pollutants in the waste water as well as the amount of waste water,
in order to minimize investment and operational costs for a
purification plant.
[0012] Generally, it can be said that water treatment and water
purification within pulp and paper industry comprises three
separate steps or parts. The first part is cleaning and treatment
of incoming raw water for the plant. Generally, such water is taken
from a lake or a large stream.
[0013] The second part comprises purification of the internal
process water, and the third part comprises purification of
polluted water that is not intended to be re-used (closed) in the
process and that therefore is led away therefrom as final waste
water.
[0014] Generally, this means that the second step takes place
within the plant and that the third step takes place outside the
plant, in a dedicated waste water purification plant. The measures
for the second step purification (within the plant) could partly be
of the same basic technical nature as the measures undertaken in
the third step, but could also be of totally different nature.
[0015] The pollutants in the form of suspended substances and
acid-consuming substances, leaving the production process by the
waste water, consist to a major part of raw material substances
such as cellulose material and additives. These substances would
have given an increased production yield if they could have been
better kept and utilised as a part of the end product instead of
leaving the plant by the waste water.
[0016] Internal measures to decrease effluents in the form of waste
water for external purification include modifications of the
production processes, in order to generate less effluents, as well
as various methods for recycling internal process water (so called
white water) used in the plant, in order to recycle raw materials
in such water to the produced end product.
[0017] One example of internal purification of water for recycling,
is purification of internal process water around a paper machine.
Paper production requires a lot of water, since the stock (water
plus fibre plus additives, etc.) must be much diluted before it is
lead onto the paper machine wire. Thereafter, the water is drained,
partly on the wire (the strainer screen on which the paper is
formed), and partly in the press section of the paper machine. This
drainage water is loaded with cellulose material and other
suspended materials, as well as dissolved organic and inorganic
substances.
[0018] Fresh water is constantly supplied to the process water
system (which also means that roughly the same amount of water
leaves the system in the form of waste water). The major part of
the process water is recycled to the paper machine. This closing
decreases water consumption and loss of raw materials.
[0019] It is mainly the possibility of effective separation of
substances in the process water that limits the degree of recycling
of the process water. At poor separation of substances from the
process water, or at an increased degree of recycling, accumulation
of materials take place in the process water, and this may lead to
problems in the form of formation of slime, clogging, as well as
impaired production and product qualities.
[0020] Usually, flocculants are charged to increase retention of
materials in the formed product. It is important in this case that
the flocculation results in flocks of material with beneficial
dewatering properties, since the dewatering is of decisive
importance to the productivity of a paper machine.
[0021] Today, purification of the internal process water to be
recycled usually takes place in screens, filters, settling basins
and flotation plants.
[0022] Purification techniques of today, of waste water from the
plant, in external purification plants, are based on a combination
of mechanical, chemical and biological purification steps. By
biological purification (biopuriflcation) is meant the use of
cultures of micro-organisms in order to decompose pollutants and
acid-consuming materials, other bacterial cultures, etc.
[0023] It is also known in a few pulp and paper mills to use ozone
in the last (external) purification step, after extensive
biological treatment. In these cases, ozone is above all used in
large amounts to oxidize high-molecular materials, being very hard
to decompose in a biological purification plant, into substances of
lower molecular size that can thereafter be decomposed in a
subsequent biological purification step.
[0024] It is important to avoid large variations in the load of the
external purification plant, since this has to be dimensioned for a
maximum load, and since variations will, as such, result in
disturbances in the external purification process.
[0025] It should be mentioned that by techniques of today,
purification steps outside the production in the actual plant/mill,
constitute an economical load on the total result for the pulp
and/or paper production.
[0026] In some applications, ozone is also used to kill bacteria,
see FI 110683B e.g. In this application, a method is described of
using ozone to kill micro-organisms in the internal process water
in paper mill.
[0027] There is a constant need for improved purification
techniques in the mills, and the need increases concurrently with a
gradually increased environmental consciousness in terms of more
stringent rules for effluents allowed from the mills. Of special
interest are techniques also having the possibility to improve
purification of process water within the mill (within the
production process), and that allow for increased recycling of
process water at maintained quality for the production process and
for formed products, and thereby decreased requirement of fresh
water supply and decreased waste water discharge.
[0028] If the technique moreover can be formed such that material
separated from the process water in the purification steps can be
recovered as a marketable product, i.e. be completely or partly
recycled in the production process, instead of, as now,
constituting a load on the external waste water purification, then
an economically profitable incentive has been introduced for a
gradual improvement of the purification technique. A cost has been
converted into "profitable" recovery, as well as increased
productivity, i.e. a purification that pays its own cost or even
more.
[0029] Accordingly, there is a need for new technique that improves
the production economy (profitability) of the mills, thereby
ensuring fulfilment of stipulated outlet limits, and also ensuring
quality demands for the production and its product, by fulfilling
at least one/some, preferably all of the following criteria:
a decreasing the amount of waste water b decreasing the need for
incoming raw water (fresh water) c decreasing the need of or the
cost for depositing d recovering of useful/valuable substances from
recycling and waste water, respectively e decreasing loss of raw
materials (otherwise leaving as pollutants in the effluents) f
allowing for increased productivity.
BRIEF DESCRIPTION
[0030] The present application relates to the accomplishment of
chemically affecting the substances in the process water, thereby
becoming more reactive in order to accumulate to form larger
aggregates, so called flocculation, and also so that the substances
will more easily react with chemicals added to improve
flocculation, the now said being achieved by mixing in an oxidizing
agent such as ozone gas in the process water. In the present
invention, an oxidizing agent such as ozone is used for a different
purpose than what has been done previously in the process line. The
oxidizing agent may be ozone or some other oxidizing agent having
an potential of oxidation of preferably above 1.5 V.
[0031] By adding an oxidizing agent such as ozone integrated with
the process, several advantageous effects are achieved.
[0032] As mentioned above, ozone has been used previously in
external purification in order to improve separation of COD. Ozone
has also been used as a bactericide in the internal process water,
and as a bleaching agent. In the present application, ozone is used
to achieve a flocculation, or to render it more effective, of
substances in the flow of fibre pulp as well as in the process
water. By adding ozone as close as possible to the forming step
(the effect will be better the more close to the forming step that
the ozone is added), a larger amount of the substances will be
caught in the network of cellulose, i.e. in the product, and
thereby materials are recovered from the process water, which
materials would otherwise be lost as pollutants, also resulting in
the white water becoming cleaner, such that a larger part of the
white water can be recycled in the short and long circulations.
Besides this, combinatory advantages are attained in that also the
bactericidal properties of the oxidizing agent can be used.
Moreover, by using the bleaching properties of the oxidizing agent,
a possibility is achieved to change the colour of excessive sludge,
thus enabling this to be mixed into the raw material pulp, without
affecting the colour of the end product.
[0033] The result thereof is a decrease in the amount of substances
that leave the production by the waste water, which means an
increased yield in relation to used raw material, as well as a
decreased load on the external purification plant, resulting in an
economical contribution to the pulp and/or paper mill, instead of
becoming a costly problem of depositing.
[0034] The process water quality is also generally improved by
addition of oxidizing agents, preferably ozone, thus enabling
decreased water consumption for the production process for paper
and pulp (increasing the degree of recycling, i.e. increasing the
degree of closing). Bacteria and bacteria growth is reduced,
otherwise leading to odour, formation of slime and disturbances in
substance flocculation.
[0035] The improved flocculation properties that can be achieved by
addition of oxidizing agents, will also result in an improved
function (increased degree of separation) for the mechanical
equipment for treatment of process water, such as screens, filters
and similar. At the same time, the function is also improved for
settling and flotation equipment, intended for separation of
materials from the process water. In particular, it is fragments of
cellulose fibres and other particulate substances that in this way
are more efficiently separated from the process water.
[0036] The flocculation of substances and the process of forming
fibre material into a fibre network, in all steps of the production
processes within pulp and paper industry, is of central importance
to the production result. The addition of an oxidizing agent will
give a beneficial structure of the fibre network during forming of
the network thus increasing retention of substances in the network,
and at the same time, separation of water from the fibre network is
facilitated due to the changed network structure. Thereby,
utilisation of the material is improved (increased retention), as
well as so called runnability (less frequent disturbances during
production) for the various process steps in pulp and paper
production.
[0037] By the measures above, i.e. the oxidation treatment of the
process water, there will be a decrease in the amount of pollutants
constituting a load on the external waste water purification. Still
however, some excessive sludge will be formed in the external
purification step. Since the treatment with an oxidizing agent is
bactericidal, besides being a catalyst for aggregation of the
substances, a recycling to the (paper) production process can take
place by oxidation treatment of this sludge material. The effect
will be bacteria-reduction in the sludge and aggregation of the
substances, to be caught by the production process, in which it is
screened out with the product.
[0038] The treatment with the oxidizing agent is also
colour-reducing, resulting in that the most often darker colour of
the sludge can be reduced to a suitable nuance, as desired.
[0039] A higher dosage of the oxidizing agent will be more
colour-reducing than a lower dosage. This affects the possibility
to recycle the sludge as a part of the products, without affecting
the colour of the material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 shows a schematic drawing of material and water flows
in pulp and paper production, in which an ionization and oxidation
step 12 has been introduced in the process,
[0041] FIG. 2 shows an embodiment example of the mixing-in of ozone
gas according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0042] The invention will now be described in detail, with
reference to the drawings.
[0043] FIG. 1 shows a schematic drawing of material and water flows
in pulp and paper production, in which an ionization and oxidation
equipment 12 has been introduced in the process, preferably just
before the forming equipment 14. Raw materials 1 and water 2 are
supplied to the production process 3. The product 5 is produced and
water vapour 4 and polluted output process water 6 leaved the
production process 3. The output process water 6 is purified in an
external purification plant 7 for waste water, from which one part
leaves as sludge 8 for deposit and/or incineration, and the
purified water 9 is let out to the recipient (i.e. the
environments). Looking closer into the production process 3, it can
be seen that raw material 1 and water 2 are supplied to a pulp and
stock preparer 10. Also recycled process water 15, 20 is supplied
to the pulp and stock preparer, from the storage tank 19 for
white/process water and the forming equipment 14 (preferably a
paper machine), respectively. The pulp/water mixture 11 resulting
form the pulp and stock preparer 10, is thereafter exposed to an
ionization and oxidation step 12 (see FIG. 2). The ionized and
oxidized output water 13 from the ionization and oxidation
equipment 12 is thereafter introduced in the forming equipment 14.
Preferably, the water flow 11, 13 is also treated with retention
agents. In the production line, the distance between the pulp and
stock preparer 10 and the forming equipment 14 can be relatively
large. It is preferred that the ionization and oxidation equipment
12 is situated more or less in direct connection with the forming
equipment 14. The forming equipment 14 produces the paper product 5
by distributing the treated, fibre-carrying water 13 (the pulp
suspension) onto a forming wire. A part 15 of the white water 15,
16 from the forming equipment 14 is recycled directly to the pulp
and stock preparer 10, in the so called short circulation, another
part 16 goes to internal purification equipment 17. Furthermore,
water also leaves as water vapour 4 that is let out. The internal
purification equipment 17 may for example contain various screening
steps and/or flotation steps, in which a part 18 of the water can
be re-used and therefore be sent to a storage tank 19 in order to
be recycled to the pulp and stock preparer 10. The water 6 that
contains a higher concentration of reject material than water 16
and 18, and that is not led to the storage tank for process water
19, is sent to external purification equipment 7 (such as flotation
basins) that separates bio-sludge 8 and water 9 that is considered
to be adequately purified and that is therefore returned to the
environments. Under certain circumstances, parts of the bio-sludge
8 can be returned to the production process 3 at the ionization and
oxidation equipment 12.
[0044] One embodiment example of the mixing-in of ozone is shown in
FIG. 2, i.e. the ionization and oxidation equipment 12 that is
inserted between the pulp and stock preparer 10 and the forming
equipment 14 (see FIG. 1). A pulp/water mixture 11, typically
having a pulp concentration of between 0.5 and 5%, is pumped into a
container 27 (the mixture is normally diluted with internal process
water that in turn contains pulp concentrations of normally below
0.5%). Ozone gas 24 is added to the bottom of the container 27, by
being injected into the container 27 in the form of small bubbles
25, in order thereby to increase contact surfaces against the
pulp/water mixture 11. The ozone gas 24 can be generated by using
an ozone generator. Preferably, a stirrer 23 is positioned inside
the container 27, in order to stir the pulp/water mixture 11 and
further to increase the possibilities for the ozone gas bubbles 25
to react with the substances in the pulp/water mixture 11.
Appropriately, other stirring means for the pulp/water mixture 11,
can be used. The top of the container 27 is provided with outlet
pipes 21, 22 for remaining ozone gas 24 that has passed the
pulp/water mixture 11 without having reacted. The remaining ozone
gas 24 can either be led via pipe 21 to an ozone-destroyer, or it
can be returned to the ozone generator via pipe 22, for re-use in
order thereafter to be recycled to the container 27.
[0045] In order to achieve a result that is as good as possible, it
is preferred for the ozone gas 24 to have a long contact time with
the process water. Therefore, the ozone gas 24 is preferably added
in the above described reactor vessel 27. However, it can also be
added in a longer pipe in which the ozone gas 24 is mixed with the
pulp mixture 11. Preferably, the process water 11 should be stirred
during the reaction time. The dwell time for the liquid 11 in
vessel 27 is a function of the volume of the vessel 27 and the
liquid volume flow through vessel 27. If the concentration of ozone
is high in the ozone gas 24, the contact time may be shorter in
order to achieve the same effect of the ozone gas (the so called Ct
factor, where gas concentration and reaction time is a product
factor that weighs the importance of changes in gas concentration
and reaction time, respectively). Stirring can take place either by
a stirrer 23 in a container 27, or by a so called static mixer in a
pipe through which process water 11 and ozone gas mixture 24 are
pumped. A combination of a container 27 with a stirrer 23 and a
pipe with a static mixer, is also possible. The ozone gas 24 can be
added e.g. by being bubbled 25 into the process water 11, at as
small gas bubbles as possible, in order to achieve a contact
surface with the process water 11 that is as large as possible.
Mixing-in can tale place is e.g. by bubbling equipment, e.g. acting
from the bottom of a container 27 in which the process water 11 is
contained. Mixing-in can also take place via a mixing-in pump such
as a type of turbine pump, or by adding ozone gas 24 into a pipe by
aid of a so called ejector or by a dosing lance. The mixing of the
process water 11 and the added ozone gas 24 should be as good as
possible. If it is desired to recycle parts of the bio-sludge 8
that is separated in the external purification 7 (see FIG. 1),
parts of the sludge 8 can be recycled to the container 27 in which
the ozone gas 24 is added to the process water 11.
[0046] In the brief description above, the principles for the
action of the ozone gas are thoroughly discussed.
[0047] In the description above, the method has been described when
using ozone gas.
[0048] Naturally, other oxidizing agents can be used at greater or
less extent, and in combination. It is also conceivable that the
part of the white water 15 from the forming equipment 14, that is
recycled directly to the pulp and stock preparer 10, is exposed to
an ionization and oxidation step. Furthermore, water 20 from
storage tank 19 can be exposed to an ionization and oxidation step
in direct connection with the pulp and stock preparer 10.
* * * * *