|
(11) | EP 1 793 034 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||
| (54) | A system for causing mechanical processing of a fibre suspension |
| (57) The present invention encompasses a system and a pulp for sale in order, within mutually
subsequent and temporally separate treatment steps (N, T) to cause mechanical processing
of a fibre suspension of cellulose fibres and water in excess in order thereby to
create the preconditions for a straightening out of in any event a portion of the
cellulose fibres occurring in a fibre suspension (f1) and/or to "roughen up" the fibres
for an increase of a fibre-related tensile index (D1 to D2). A first treatment step (N) is related to a paper pulp manufacturing first installation (1), and a second treatment step (T) is related to a papermaking second installation geographically separate from one another. The first treatment step is activated for a first mechanical processing of a first fibre suspension (f1) in order to form a second fibre suspension (f2) and which second fibre suspension will be utilised so as to create a pulp for sale (PM). More particularly, the present invention discloses that the mechanical processing within said first processing step (N) is particularly adapted to straighten out the fibres, while the mechanical processing within said second processing step (T) is particularly adapted to "roughen up" the fibres. |
TECHNICAL FIELD
[0001] The present invention relates in general to a system for causing the mechanical processing of a fibre suspension within mutually subsequent and temporally separate processing steps.
[0002] The term fibre suspension is taken in this application to signify a suspension of a cellulose fibre and int. al. water, with water in a considerable excess.
[0003] The system is particularly intended to be able to create the preconditions in order, in a straightening of in any event a portion of the "curved" cellulose fibres occurring in a fibre suspension in papermaking in order thereby to be able to make for an increase of the tensile index of the fibres.
[0004] The term "the tensile index of the fibres or fibre suspension" or "a tensile index relating to fibres" is taken to signify the tensile index which a paper pulp sheet or a paper sheet will display when produced, by a selected processing and a selected drying of the fibres which relate to the pertinent fibre suspension.
[0005] Thus, an increase, or alternatively a decrease, of the pertinent tensile index will of course imply that the fibre-related tensile index of a fibre suspension is to be compared with the tensile index of another fibre suspension, in accordance with the above-disclosed definition.
[0006] The following description relates to the tensile index of the fibres and it should be observed that, instead of tensile index, the "form factor" of the fibres could also be used, since a selected tensile index value relates to a corresponding form factor value, and vice versa.
[0007] The present invention may be considered as constituting a direct further development of the method and the apparatus for processing of a paper pulp which is more closely illustrated and described in Swedish Patent Application number 03 02579-8 or corresponding European Patent Application number 03 024783.7.
[0008] It is also previously known in the art that fibres, in particular cellulose fibres, may for practical reasons be divided into "short fibres" and "long fibres" and the following description and application is intended to take into consideration principally the utilisation of "long fibres" but it should, however, be understood that the basic preconditions of the present invention may also be utilised on "short fibres".
[0009] It will be obvious to a person skilled in the art that, within the concept of "short fibres" there also occur long fibres while short fibres occur in excess.
[0010] The value of the hereafter utilised fibre-related "tensile index" depends int. al. on the form factor of the fibres, individual fibre strength, applicable bonding strength between individual fibres and other known criteria, but the following description principally takes into consideration substantially the form factor of the fibre and an assumed simpler relationship (however not a purely linear function) between a tensile index value and a form factor value.
BACKGROUND ART
[0011] It is thus previously known in the art that fibres in logs and in wood for papermaking consist of straight fibres and that these fibres, in the form of different fibre suspensions, are curved and folded by the selected production method for the paper pulp.
[0012] The invention is then based on a system for causing mechanical processing of fibre suspensions within mutually subsequent and temporally separate processing steps in order thereby initially to create the preconditions for a straightening of in any event a portion of the cellulose fibres occurring in the fibre suspension, for an increase of the value of a fibre-related tensile index.
[0013] More particularly, the prior art discloses that a first fibre suspension processing step is to be related to a first paper pulp making plant and then before a drying section associated with the plant.
[0014] In an application within the production of a bleached paper pulp, the first processing step should be oriented after a bleaching section.
[0015] Preferably, the solid fibre content of the fibre suspension should be adapted to a value which is suitable and adapted for the papermaking. For certain practical applications, the fibre concentration may be selected to be as low as between 1 and 6 %.
[0016] A second processing step intended for a fibre suspension is to be related to a second papermaking plant.
[0017] The practical application of the present invention is based on the situation that the first plant is geographically separate from the second plant and, to such an extent that a paper pulp produced via said first plant, a so-called pulp for sale, from a first fibre suspension with a first fibre-related tensile index, and after drying and packing or baling must be transported from the first plant to the second plant using one or more transportation means. These transportation means may then be designed in order to make for the transport of packed paper pulp bales by lorry, boat or other transport means from a paper pulp factory to a paper factory.
[0018] If the paper pulp were to be produced in other form, other transportation means may naturally be required.
[0019] More particularly, the present invention is based on the circumstance that, within said first plant and a first processing step included therein, a first fibre suspension with a fibre-related tensile index, is to be activated for a first mechanical processing in order thereby to be able to form a second fibre suspension with a second, higher fibre-related tensile index, and said second fibre suspension will be utilised within the drying section of a paper pulp forming machine or first plant in order to create said paper pulp.
[0020] The system according to the present invention is further based on the circumstance that, within said second plant and a second processing step included therein, there is to be created, from said paper pulp, a third fibre suspension with a third fibre-related tensile index, where said third fibre suspension is to be activated for a second mechanical processing in order thereby to be able to form a fourth fibre suspension with a fourth (a higher) fibre-related tensile index, and which fourth fibre suspension will be utilised, within a drying section of a papermaking machine or second plant in order thereby to create finished paper.
[0021] Said fourth fibre suspension is, in a per se known manner, to be distributed over a wire section of a papermaking machine in order for forming a paper web which is caused to pass subsequent drying section in order finally to occur as a finished paper.
[0022] The state of the art also includes the contents in:
Page D.H, "The mechanism of strength development of dried pulps by beating"; Svensk
Papperstidning, vol 88, no. 3, 21 February 1985, pages R30 - R35.
Here, various theories are shown and described for causing mechanical processing or
beating of a produced paper pulp, and this article ascertains that an unbeaten, dried
paper pulp contains fibres which have become distributed within the paper pulp and
that these fibres occur as curved in different manners, such as displaying undulating
form, and are entangled with one another.
[0023] These circumstances become a consequence of the production methods for the paper pulp and a utilised mechanical processing and/or a beating which is characteristic of the occurring tensile index when the paper pulp, as a fibre suspension, is allowed to dry in a drying section.
[0024] The article ascertains that these undulating and curved fibres will be incapable of absorbing tractive force stresses or are, in any event, incapable of absorbing high force stresses.
[0025] More particularly, it is ascertained in the article that a load distribution relating to a form factor and a tensile index for a sheet formed from a paper pulp with curved and disordered fibres will be unsatisfactory and that the tensile limit occurring will be low.
[0026] By treating and improving paper pulp in a mill and thereby increasing the swelling capability, and by subjecting the fibres to stretching, it has proved that a sheet, formed from such a stock and treated paper pulp, gives a higher load distribution and higher stretch limit.
[0027] The article deals with different aspects of treating a dried paper pulp before, in water diluted form as a fibre suspension, it arrives in a papermaking machine for producing paper.
[0028] The present invention has for its object to benefit from the disclosures which this article presents, but also presents other disclosures in order to be able to increase the load distribution and be able to increase the stretch limit and tensile index.
[0030] This document shows and describes a process for treating a bleached sulphite chemical paper pulp and where the process includes delignification of chips for a lignin cellulose material within a sulphite process until a defibration point is reached.
[0031] The actual bleaching of the fibre material will, in such instance, take place with the aid of a chlorine-free bleaching process which will then comprise a first bleaching step, under the utilisation of a chlorine-free oxidation in the presence of a base.
[0032] The chemical paper pulp which is treated by such means is characterised by a high degree of brightness and a high stretch limit.
[0033] It should, naturally, be testified that the publication, on page 20, lines 27 to 37, discloses that a mechanical processing or beating shall be able to take place either within the papermaking proper or in association with the papermaking process, but the beating intimated here implies that a "complete" mechanical processing or beating is carried out.
[0035] This publication shows and describes a lignocellulose material which has been given improved properties in terms of water absorption capacity, strength, dewatering capacity and beatability and particularly discloses that the fibre walls of the fibres included in the paper pulp are to be provided with a proportion of an anionactive polyelectrolyte.
[0036] As a result of prior art processes, paper pulp is produced, also designated pulp for sale, in paper pulp factories and this paper pulp is packed as "pulp for sale" such as, for example, in bales and is transported as such a "pulp for sale" to a papermaker.
[0037] If the paper pulp producer and the papermaker were located very close to one another, for example within the same factory area, the properties associated with the present invention will be totally unnecessary since the requisite prior art complete mechanical processing or beating of the paper pulp can either then "be related" to the paper pulp manufacture or to the papermaking, without the basic preconditions for the present invention in that the produced paper pulp, is to be transported, so that during storage and transport, the pulp will be able to be subjected to liquid evaporation and further drying.
[0038] The present invention is based on the circumstance that, within the plant for paper pulp production, the produced paper pulp is to be mechanically processed, in a first mill installation in order thereby to raise the quality of or increase the tensile index of the produced paper pulp.
[0039] The mechanical processing, in this first disclosed mill installation, is of course power and energy consuming, but power and energy available for this purpose are quite simply available at the otherwise energy-demanding paper pulp production, for which reason measures intended to improve the structure and tensile index of the pulp for sale will not need any further additional major investments.
[0040] According to the present invention, the paper pulp manufacturer will thus be able to deliver a packed paper pulp, such as in the form of bales or by other means, which is mechanically processed into a semi-manufactured product more adapted and ready for the papermaker.
[0041] When the improved paper pulp has been delivered to the papermaker, the initial task for the papermaker, in a so-called pulper, or agitator where a predetermined paper pulp is dissolved in a predetermined quantity of water, to form a third fibre suspension with a third fibre-related tensile index, in order thereafter in a second mechanical processing stage to prepare or beat the third fibre suspension into a fourth fibre suspension displaying a fibre-related tensile index for supplying to the wet or wire section of the paper machine.
[0042] It may be assumed that, for certain practical applications , this second mechanical processing will require less power and energy than the first mechanical processing, and this corresponds closely with the circumstance that a papermaker needs less power and energy for the production of paper from a received pre-treated paper pulp.
[0043] The prior art further discloses that each mechanical processing of one and the same fibre suspension so as to display increasingly higher fibre-related tensile index may be divided into two mutually subsequent sequences which, in any event theoretically and in association with the significative characteristics of the present invention, should be considered as separate from one another.
[0044] The first sequence is based on, via a first energy supply, mechanically straightening out the curved and/or folded fibre structure which the system for paper pulp manufacture generates by causing the individual curved fibres within a fibre suspension to be pressed through gaps in a utilised mill installation or plant.
[0045] The second sequence is based on, via an additional or second supply of energy, mechanically "roughening up" the surface of the individual straightened fibres so that neighbouring fibres may secure to and catch in one another and that the thus roughened up fibres create the preconditions for an increased water absorbing capability.
[0046] The first sequence is intended to create the initial preconditions for slightly increasing the fibre-related tensile index, while the second sequence is intended to create the preconditions for causing the fibres to catch in one another in order more directly to contribute to an additional increase of the fibre-related tensile index.
[0047] The expression "roughening up" and similar expressions is taken to signify that a straight or straightened fibre is subjected to an additional processing within a mill installation so that "projections" are formed on the outer surfaces of the fibres, such a treated fibre having a structure corresponding to the structure of a trunk portion of a spruce.
[0048] As regards the second papermaking installation, it will be obvious that this encompasses a pulper, for production of a third fibre suspension, a second mill installation for a second mechanical processing for production of a fourth fibre suspension, a papermaking machine with its allocated wet or wire section, a drying section and a section for rolling up a paper web, and where all of these sections offer, from the selected construction, different limited preconditions which in turn will, in different ways, limit the structure of and quality of produced paper.
[0049] It is thus well-known in the art that a papermaker looks for access to different selected structures for utilised paper pulps in order, by such means, to be able increasingly to utilise the functions of the papermaking machine for a finished paper with altered and improved structures and qualities.
BRIEF OUTLINE OF THE PRESENT INVENTION
TECHNICAL PROBLEMS
[0050] Taking into account the circumstance that the technical considerations which a person skilled in the art must make in order to be able to offer a solution to one or more technical problems is, on the one hand, initially a necessary insight into the measures and/or the sequence of measures to be adopted and, on the other hand, a necessary selection of the means required, in view hereof the following technical problems are likely to be relevant in the evolution of the subject matter of the present invention.
[0051] Taking into account the state of the art, as described above, it should probably therefore be seen as a technical problem to be able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order, in a first mechanical processing step of a fibre suspension, to create an adapted tensile index-increase in relation to a fibre-related tensile index related to a first fibre suspension intended for the treatment, produced within a plant for the production of a paper pulp.
[0052] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a paper pulp to be pre-prepared as regards a current fibre-related tensile index so that the paper pulp can be directly adapted to a papermaking installation, where this installation, with its sections, may produce, in a simple manner, a paper with predetermined criteria.
[0053] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to offer, from one and the same paper pulp producing installation, paper pulps of mutually different structures and fibre-related tensile index, where selected criteria may be directly adapted to a selected papermaking installation, and directly to take into consideration criteria relating to the installation int. al. as regards available pulping, selected mixture of short fibres and long fibres, bleached or unbleached paper pulp, criteria related to a unit mechanically processing the fibre suspension, with int. al. respect on power as well as an available papermaking installation.
[0054] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a first energy-consuming treatment level for the fibre-related tensile index of the paper pulp within the papermaking installation and a second energy-consuming remaining and well adapted second treatment degree for the fibre-related tensile index of the paper pulp within the papermaking installation.
[0055] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause the first treatment degree to be adapted to the energy requisite principally for straightening of the fibres and the fibre structure and possibly to some extent in order to "roughen up" the fibres.
[0056] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause said first treatment step to treat a first fibre suspension disclosed from the papermaking towards and to a selected tensile index value relating to a second fibre suspension and where this tensile index value is to be associated with a value adapted for a subsequent papermaking installation.
[0057] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause said mechanical processing, within said first treatment step, principally to be adapted in order to create a straightening out of in any event the major proportion of the cellulose fibres occurring in a first fibre suspension and that a mechanical processing, within said second processing step, is caused to be adapted so as to supplement said straightening out sequence and final "roughening up" of the fibres within the third fibre suspension towards its fourth fibre-related tensile index.
[0058] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause said first treatment step to be carried out with the aid of a plurality of series-related and/or parallel-related mechanical processes such as via a plurality of mills within a mill installation or plant.
[0059] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a mechanical processing, within said first processing step, to be driven somewhat past a straightening out of the fibres and then to a roughening up of the fibres to an adapted first degree which does not harmfully affect the drying within the papermaking process or which only to a slight extent harmfully affects the drying within the papermaking process and that the second processing step is to be adapted only to final "roughening up" of the fibres to a second and final degree.
[0060] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a difference, between said first degree and said second degree, to be adapted to a selected capacity and construction for said second treatment step and for a high degree of efficiency and/or effectivety for a mechanical processing utilised therein, such as in a mill installation.
[0061] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause the feed, to a pulper within said second plant, int. al. of a plurality of paper pulps with mutual short fibres and long fibres and where in any event a selected proportion of long fibres is to be treated in accordance with the foregoing.
[0062] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause the value of the fibre-related tensile index for a first fibre suspension disclosed from the papermaking process to be selected to be as high as the first installation can produce, which in practice should fall within the limit value of 10-80 kNm/kg.
[0063] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a fibre-related tensile index increase, within the first processing step, to be selected and/or adapted to criteria depending upon the subsequent second treatment step, for a mechanical processing selected there.
[0064] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a selected tensile index increase within the first processing step to be selected to be more than 5 % and less than 300 %, such as for example more than 10 % and less than 200 %.
[0065] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a tensile index increase to be selected to be less than 40 kNm/kg and in any event to exceed 5 kNm/kg.
[0066] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a fibre-related tensile index increase, within the second processing step, to be selected with or without additives, such as paper chemicals, to more than 10 % and less than 300 %, such as selected to less than 200 % or to less than 100 %.
[0067] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a paper pulp to be pre-treated with a mechanical processing with the result that in any event only a minor proportion of the fibres will be roughened up via the first mechanical processing step, within the paper pulp producing installation, and where a fibre-related tensile index will in such instance display a value of between 10 and 80 kNm/kg.
[0068] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order to cause a fibre-related tensile index to be is directly adapted to preconditions valid for a paper machine and adapted to previously set requirements on a paper produced therefrom.
[0069] There resides a technical problem in being able to realise the importance of, the advantages associated with and/or the technical measures and considerations which will be required in order, via a first processing step of a first fibre suspension with a first fibre-related tensile index to cause the processing of said first fibre suspension to a second fibre suspension with a second fibre-related tensile index, where the latter tensile index value is to be associated with a value corresponding to a selected papermaking installation.
SOLUTION
[0070] In such instance, the present invention takes as its point of departure the prior art as disclosed by way of introduction, a system in order, within mutually subsequent and temporally separate processing steps to mechanically process a fibre suspension, of cellulose fibres and int. al. water in excess, in order thereby to create the preconditions for a straightening out of in any event a part of the cellulose fibres occurring within the fibre suspension and/or to "roughen up" the fibres for an increase of a fibre-related tensile index where a first processing step is related to a paper pulp producing first installation, and before a drying section, and where a second processing step is related to a papermaking second installation and before a drying section, and moreover said first installation is geographically separate from said second installation to such an extent that a paper pulp produced via said first installation from a fibre suspension with a fibre-related tensile index and after drying and packing must be transported from the first installation to the second installation with the aid of transportation means.
[0071] The first processing step is to be activated for a first mechanical processing of a first fibre suspension with a first fibre-related tensile index, to a second fibre suspension with a second fibre-related tensile index, where said second tensile index should be adapted to be higher than said first tensile index and said second fibre suspension will be utilised in order to create said paper pulp.
[0072] Within said second installation there is created from the paper pulp a third fibre suspension with a third fibre-related tensile index which, via the second mechanical processing is activated for a second mechanical processing of said third fibre suspension in order to form a fourth fibre suspension with a fourth fibre-related tensile index which should be adopted to be higher than said third tensile index, where upon said fourth fibre suspension is distributed over a wire section allocated to a papermaking machine for the formation of a paper web and passage through a drying section for the formation of a finished paper.
[0073] In such a system, the present invention discloses that said first mechanical processing, within said first processing step, is principally to be adapted so as to create a straightening of in any event a major proportion of the cellulose fibres occurring in the first fibre suspension to a second fibre suspension, and that said second mechanical processing, within said second processing step, is to be adapted in order finally to "roughen up" the fibres within the third fibre suspension, towards its fourth fibre-related tensile index.
[0074] It also falls within the scope of the present invention that said first processing step be able to be carried out with the aid of a plurality of series-related and/or parallel-related mechanical processings, such as via mills within a mill plant.
[0075] It is further disclosed that the mechanical processing within said first processing step be able to be driven past a straightening of the fibres and then to a roughening up of the fibres to an adapted first degree and that the second processing step is to be adapted to "roughen up" the fibres to a second and final degree.
[0076] The difference between said first degree and said second degree is to be able to be adapted to the capacity and construction of said second treatment step and for a high degree of efficiency and/or effectivety of a mechanical processing utilised there, such as within a mill plant.
[0077] A pulper, within said second installation is to be fed with paper pulps with short fibres and long fibres and where in any event the proportion of long fibres has been treated in accordance with the foregoing.
[0078] The value of the fibre-related tensile index for the first fibre suspension should be selected as high as the first installation can produce, which in practice may fall within the limit values of 10-80 kNm/kg.
[0079] A fibre-related tensile index increase, within the first processing step, should be selected and/or adapted to criteria depending upon the subsequent second processing step for a selected mechanical processing.
[0080] A tensile index increase within the first processing step should be selected to be more than 5 % and less than 300 %, such as for example more than 10 % and less than 200%.
[0081] A selected tensile index increase may be selected to be less than 40 kNm/kg and exceed 5 kNm/kg.
[0082] A fibre-related tensile index increase within the second processing step should with or without additives be selected to be more than 10 % and less than 300 %, such as for example less than 200 % alternatively less than 100 %.
[0083] The present invention also discloses a produced paper pulp or a pulp for sale where said paper pulp is treated with a mechanical processing with the result that in any event a small proportion of the fibres are roughened up to a first degree, via a first mechanical processing step, within a paper pulp producing installation and where a fibre-related tensile index should have a value of 10-80 kNm/kg.
[0084] More particularly, the paper pulp should display a fibre-related tensile index which is adapted to the preconditions applicable for a papermaking machine and on previously set requirements on a paper web produced thereby.
[0085] The paper pulp should via said first treatment step of a first fibre suspension with a first fibre-related tensile index be processed to a second fibre suspension, with a second fibre-related tensile index, where the latter tensile index value should directly associate to a value corresponding to a selected papermaking installation.
ADVANTAGES
[0086] Those advantages which may principally be deemed to be characteristic of the present invention and the specific significative characterising features disclosed thereby are that there have hereby been created the preconditions, within a first treatment step, within a paper pulp producing first installation to allocate a paper pulp a previously determined tensile index and where the value of the tensile index of this paper pulp can and should be associated with the tensile index which is particularly suitable for a second processing step within a papermaking installation.
[0087] Hereby, the paper pulp in the form of pulp for sale will be structured and allocated a tensile index which will be directly adapted to a second processing step, which is related to the papermaking installation and criteria for manufactured paper web.
[0088] That which principally be deemed as characterising a system according to the present invention is disclosed in the characterising clause of appended Claim 1 and that which may principally be deemed as characterising a paper pulp or a pulp for sale thus produced is disclosed in the characterising clause of appended Claim 14.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0089] One currently proposed embodiment, displaying the significative characterising features associated with the present invention will now be described in greater detail hereinbelow for purposes of exemplification and with reference to the accompanying Drawings. In the accompanying Drawings:
Fig. 1 is a perspective view of a paper pulp manufacturing first installation of per se previously known construction with unambiguously determined and dimensioned functional steps and capacity, which has been supplemented with a first mechanical processing step in order thereby to create the preconditions for a straightening of in any event a part of the cellulose fibres occurring in a fibre suspension for an increase of their fibre-related tensile index, in accordance with the present invention;
Fig. 2 shows a paper manufacturing installation of per se previously known construction and with unambiguously determined and dimensioned functional steps and capacity and within which installation a manufactured paper pulp or pulp for sale produced according to Fig. 1 is utilised;
Fig. 3 shows a more complete process overview of an installation according to Fig. 1;
Fig. 4 shows in graphic form a relationship between tensile index values, in kNm/kg and corresponding form factor values in % for a selected fibre suspension;
Fig. 5 shows in graphic form a relationship between form factor values in % and that energy in kWh/tonne which is required in a mechanical processing;
Fig. 6 shows in graphic form a tensile index increase (kNm/kg) in dependence on a supplied power or speed in a supplied mill installation for two different fibre suspensions, obtained from two different paper pulp manufacturing first installations; and
Fig. 7 shows in graphic form the water absorbing capability (WRV) of a fibre in dependence upon the structure of the roughened up surface, related to supplied energy (kWh/t).
DESCRIPTION OF PREFERRED EMBODIMENT
[0090] It should by way of introduction be emphasised that, in the following description of one currently proposed embodiment which displays the significative characterising features associated with the invention and which is clarified as a result of the figures illustrated in the accompanying Drawings, we have selected terms and a specific terminology with the intention in such instance of primarily clarifying the inventive concept as herein disclosed.
[0091] However, in this context it should be observed that expressions selected here should not be seen as restricted exclusively to the terms utilised and selected here but it should be understood that each such selected term is to be interpreted so that it in addition encompasses all technical equivalents which function in the same or substantially the same manner in order in such instance to be able to attain the same or substantially the same intention and/or technical effect.
[0092] With reference to the accompanying Drawings, Fig. 1 thus shows schematically and in certain detail the basic preconditions of the present invention relating to a paper pulp manufacturing installation 1.
[0093] Fig. 1 illustrates, at reference numeral "A", that the requisite soft wood has been cut and transported to a paper pulp manufacturing installation 1; "B" illustrates the utilisation of a barking drum; "C" shows a chipping machine; "D" a cyclone; "E" a chip screen; "F" a chip storage; "G" a mixture of chips and cooking liquid; "H" a cooker; "I a blowing tank; "J" a wash filter; "K" a screen; "L" a wash filter; "M" a bleaching tower; "N" a first mechanical treatment step significative of the invention; "O" a paper pulp producing machine; "P" a wire section associated with the paper pulp machine "O"; "Q" a drying section intended for the paper pulp machine and "R" equipment for packing produced paper pulp "PM" in bales "R1".
[0095] The major reference "S" is intended to illustrate that a paper pulp "R1" is mixed int. al. with water in a unit or pulper, while reference designation "T" illustrates a second mechanical treatment step; "U" a papermaking machine; "V" a wire section; "X" a drying section intended for a paper web with drying cylinders; "Y" a hot dryer; "Z" a glazing stack and "A1" a reel for a finished paper.
[0096] The paper pulp "PM" packed in bales "R1" is also designated "pulp for sale" regardless of whether it is extent in an internal or external debiting or invoicing.
[0097] The system disclosed according to the invention is based on a cooperation between Figs. 1 and 2. The system is intended, within mutually subsequent and temporally separate treatment steps, to mechanically process a fibre suspension such as from cellulose fibres and int. al. water in excess, in order thereby to create the preconditions for a straightening of in any event a part of the cellulose fibres occurring in the fibre suspension and/or to "roughen up" the fibres for an increase of a fibre-related tensile index.
[0098] Fig. 2 illustrates that a first paper pulp bale "R1" comprises paper pulp "PM" with long fibres, a second paper pulp bale "R2" comprises paper pulp with short fibres and that further ingredients "R3" are added to the pulper "3" in a selected mixture.
[0099] It should further be observed that, in Fig. 3, there is illustrated a supply of sawmill chips "B1" and that the chip storage "F" and the cooking "H" are followed by a screening "H1" and that an oxygen gas bleaching "M1" is followed by a pulp storage "M2", a bleaching "M3", a pulp storage "M4" and a screening "M5".
[0101] The plant 1 also encompasses an installation for thin liquor or lye "H10" with an evaporation "H11" for the formation of thick lye "H12".
[0102] The thick lye "H12" is fed to a soda boiler "H13" which via the generation of steam "H14" drives a steam turbine "H15" for the generation of electric power "H16" and press steam "H17".
[0103] Green liquor "H20" is fed to a mixer "H21" and via a lime burning "H22" and a lime kiln "H23" white liquor is created for the cooker "H".
[0104] A first treatment step "N" is related to a paper pulp manufacturing first installation 1 and oriented before a drying section "O" and a second treatment step "T" is related to a papermaking second installation 2 and before a wire and drying section "X".
[0105] Said first installation 1 is geographically separate from said second installation 2 to such an extent that a, via said first installation, produced paper pulp "R1", a so-called pulp for sale "PM" from a fibre suspension with a fibre-related tensile index and after drying "X" and packing "R" must be transported from the first installation 1 to the second installation 2 with the aid of transportation means (not shown).
[0106] The first treatment step "N" is to be activated for a first mechanical processing of a first fibre suspension "f1" with a first fibre-related tensile index "D1" to a second fibre suspension "f2" with a second fibre-related tensile index "D2" where said second tensile index "D2" is here adapted to be slightly higher than said first tensile index "D1".
[0107] It falls within the scope of the present invention principally that the first fibre suspension "f1" is that fibre suspension which the paper pulp installation 1 produces after the screen "K", a wash filter "L" and, where necessary, a bleaching tower "M", but there is nothing to prevent the introduction of a mechanical processing between them.
[0109] Within said second installation 2 there is created int. al. from the pulp for sale "R1" a third fibre suspension "f3" with a third fibre-related tensile index "D3", which via the second mechanical treatment "T" is activated for a second mechanical processing of said third fibre suspension "f3" in order to form a fourth fibre suspension "f4" with a fourth fibre-related tensile index "D4", adapted to be higher than said third tensile index "D3".
[0110] Said fourth fibre suspension "f4" is distributed over a wire section "V" allocated to a papermaking machine for passage as a paper web through a drying section "X", "Y" for the formation of a finished paper "A1".
[0111] More specifically, the present invention discloses that said mechanical processing within said first processing step "N" is primarily to be adapted so as to create the straightening of in any event a predominant proportion of the cellulose fibres occurring from the first fibre suspension "f1".
[0112] Said mechanical processing "T" within said second processing step 2 is to be adapted in order finally to "roughen up" the fibres within the fourth fibre suspension "f4", with its fourth fibre-related tensile index "D4".
[0113] More specifically, it is disclosed that said first processing step "N" may be carried out with the aid of a plurality of series-related and/or parallel-related mechanical processings such as mills within a mill installation.
[0114] The invention further discloses that the first mechanical processing within said first processing step "N" should be able to be driven beyond a straightening of the fibres towards a roughening up of the fibres to an adaptive first degree and that the second treatment step "T" is to be adapted in order to "roughen up" the fibres to a second degree, a final degree.
[0115] The difference between said first degree and said second degree is adapted to the capacity and construction of said second treatment step "T" and for a high degree of efficiency and/or effectivety for the mill installation utilised there.
[0116] Pulp for sale is supplied to a pulper "S" within said second installation 2, with short fibres "R2" and long fibres "R1" and where in any event the proportion of long fibres is to be treated in accordance with the foregoing.
[0117] The value of the fibre-related tensile index for the first fibre suspension "f1" is selected as high as the first installation 1 can produce, which in practice may fall within the limit values of 10-80 kNm/kg.
[0118] A fibre-related tensile index increase within the first processing step "N" is selected and/or adapted to criteria dependent upon the subsequent second treatment step "T", for a selected mechanical processing.
[0119] The present invention discloses that a tensile index increase within the first treatment step "N" is to be selected to be more than 5 % and less than 300 %, such as for example more than 10 % and less than 200 %.
[0120] A tensile index increase within the first treatment step "N" may be selected to be less than 40 kNm/kg and exceed 5 kNm/kg for production engineering consequences.
[0121] A fibre-related tensile index increase within the second treatment step "T" may be selected to be more than 10 % and less than 300 %, such as for example less than 200 % preferably less than 100 %.
[0122] The invention moreover encompasses a pulp for sale "PM" produced in the installation 1, and said pulp for sale "R", "R1" is treated with a mechanical processing which results in any event in a minor proportion of the fibres being roughened-up via a first mechanical processing step "N" within a paper pulp producing installation 1, where a fibre-related tensile index has increased, for example from a value of 10-50 kNm/kg to a value of 20-80 kNm/kg.
[0123] A second fibre-related tensile index "D2" is adapted to preconditions valid for a papermaking machine 2 and pre-set requirements on a paper "A1" produced thereby.
[0124] Via said first processing step "N", a first fibre suspension "f1" with a first fibre-related tensile index "D1" is processed to a second fibre suspension "f2" with a second fibre-related tensile index "D2" where the latter tensile index value approximates a value corresponding to a selected papermaking installation 2.
[0125] Fig. 4 graphically illustrates a fibre-related relationship between a tensile index value, related to kNm/kg (20.0 to 70.0) and a percentage disclosure of a corresponding form factor value, related to 83 to 87 %.
[0127] Fig. 5 graphically illustrates a fibre-related relationship between form factor values in percentage 83 to 87 % and requisite energy for an increase of the form factor depending upon supplied energy in a mechanical processing in kWh/tonne.
[0128] Said graph is intended to illustrate that for lower form factor values and/or tensile index values a slight or no energy is required within the treatment step "N" and where a straightening of the fibres takes place up to values between 25 and 50 kWh/tonne, in particular slightly over the value of 25 kWh/tonne.
[0129] Thus, a supplied low energy gives in this respect a high yield as regards the increase of the form factor value.
[0130] If energy is supplied in addition, a roughening up of the fibres takes place with a relatively slight increase of form factor or tensile index values.
[0131] The invention is based on the feature that the extra energy within treatment step "N" should be moderate and be obtained from "H16".
[0132] An excessively far driven supply of extra energy to the treatment step "N" will result in the fibres sucking up water and in such instance impeding the drying in the drying section "Q".
[0133] If the present invention is now considered as illustrated above, it will be obvious that the additional supply of energy in the treatment step "N" must take place with careful considerations.
[0134] If energy is supplied in excess, a roughening up of the fibres and thereby an increased ability for water absorption takes place, which calls for increased drying which in practice entails an undesirable reduction in production output speed.
[0135] Practical trials demonstrate that the additional supply of energy, according to Fig. 7, may lie between 20.0 and 30.0 kWh/tonne without harmfully affecting the drying of the paper pulp within the drying section "Q".
[0136] At this supplied energy amount, there will be obtained an acceptable straightening out of the fibres and a well-adapted roughening up of fibre structures.
[0137] Normally, it may be assumed that the tensile index "D2" for the fibre suspension "f2" is corresponded to by the tensile index "D3" for the fibre suspension "f3" in a production of paper pulp via the drying section "Q" but if the paper pulp becomes the object of flash drying there is to be expected a deterioration of the tensile index values between tensile index "D2" and D3".
1. A system intended for a sequential mechanical processing of a fibre suspension containing
cellulose fibres, comprising:
a. a first installation (1) with a first treatment step (N) for processing a first fibre suspension (f1) in order to straighten out at least a portion of the cellulose fibres occurring in this first fibre suspension in order to form a second fibre suspension (f2),
a1. a drying section (R) in order to cause drying of the second fibre suspension (f2) processed within the first treatment step (N);
a2. equipment (R) packaging straightened and dried cellulose fibres;
b. transportation means for transportation of packed cellulose fibres (R1) in accordance with "a2" above from said first installation (1) to a second installation (2);
c. a second installation (2) with a pulper ("S") in which has been created a third fibre suspension (f3) from packed cellulose fibres in accordance with "a2" above and with an addition of int. al. water;
c1. that said second installation (2) comprises a second treatment step (T) processing said third fibre suspension (f3) in order further to straighten out at least a portion of the cellulose fibres occurring in this third fibre suspension (f3) to a fourth fibre suspension (f4);
c2. that said processed fourth fibre suspension (f4) is adapted to be fed to a machine (T-Z) for manufacturing of paper (A1),
where said first (1) and said second (2) treatment steps consist of mutually subsequent and temporally separate treatment steps for a successive increase of a fibre-related tensile index, said first treatment step (N) being related to a paper pulp manufacturing installation and before a drying section (R) while said second treatment step (T) is related to a papermaking installation and before a drying section (Y), and moreover said first installation (1) is geographically separate from said second installation (2) to such an extent that a paper pulp (R1) produced via said first installation (1) must be transported from the first installation (1) to the second installation (2) with the aid of said transportation means, said first treatment step (N) being adapted to create a first mechanical processing of said first fibre suspension (f1) with a first fibre-related tensile index (D1), to a processed second fibre suspension (f2) with a second fibre-related tensile index (D2), that within said second installation (2) a third fibre suspension (f3) is created from said transported paper pulp by said pulper ("S"), with a third fibre-related tensile index (D3) which, via said second mechanical processing step (T) creates a fourth fibre suspension (f4) with a fourth fibre-related tensile index (D4), said fourth fibre suspension (f4) being distributed over a wire section (V) allocated to a papermaking machine as a paper web for passage through a drying section (X, Y) for formation of a finished paper (A1; PB), characterised in that the first treatment step (N) allocated to said first installation (1) comprises a mill installation adapted, with the aid of one or more series-related and/or parallel-related mechanical processings, to create a second fibre suspension (f2) with a second tensile index (D2) with a fibre structure passing a state for only straightening of the cellulose fibres to a state in order to "roughen up" the fibres, that the second treatment step (T) allocated to said second installation (2) is adapted to mechanically create cellulose fibres from a third tensile index (D3) to a fourth tensile index (D4), that a difference between said third tensile index (D3) and said fourth tensile index (D4) is adapted to an available capacity and construction of said second treatment step (T) and towards a high degree of efficiency and/or effectivety and that, to said pulper ("S") within said second installation (2) there are supplied paper pulps (R1, R2, R3) with a selected distribution between long fibres and/or short fibres.2. The system as claimed in Claim 1, characterised in that the value of the second fibre-related tensile index (D2) is selected as high as the
first installation (1) can produce, which in practice will fall within the limit values
of 10-80 kNm/kg.
3. The system as claimed in Claim 1, characterised in that a fibre-related tensile index increase within the first treatment step (N) is selected
and/or adapted to criteria depending upon the subsequent second treatment step (T)
for a mechanical processing selected there.
4. The system as claimed in Claim 1 or 3, characterised in that a tensile index increase within the first treatment step (N) is selected to be more
than 5 % but less than 300 %.
5. The system as claimed in Claim 4, characterised in that a tensile index increase is selected to be more than 10 % and less than 200 %.
6. The system as claimed in Claim 1, 3, 4 or 5, characterised in that a tensile index increase is selected to be less than 40 kNm/kg and exceed 5 kNm/kg.
7. The system as claimed in Claim 1, characterised in that a cellulose fibre-related tensile index increase within said second treatment step
(T) is, with or without additives (paper chemicals), selected to be more than 10 %
and less than 300 %.
8. The system as claimed in Claim 7, characterised in that the tensile index increase is selected to be less than 200 %.
9. The system as claimed in Claim 7, characterised in that the tensile index increase is selected to be less than 100 %.
10. The system as claimed in Claim 1, characterised in that, to a pulper ("S") within said second installation (2) there are supplied paper pulps
with short fibres and long fibres and where in any event the proportion of long fibres
is treated towards increased tensile index (D2) in said first installation (1).
11. The system as claimed in Claim 1, characterised in that the value of the fibre-related tensile index (D1) of the first fibre suspension (f1)
is selected to be as high as the first installation can produce, which in practice
may fall within the limit values of 10-80 kNm/kg.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description
Non-patent literature cited in the description
- PAGE D.HThe mechanism of strength development of dried pulps by beatingSvensk Papperstidning, 1985, vol. 88, 3R30-R35 [0022]