Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/78—Controlling or regulating not limited to any particular process or apparatus
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
  • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
  • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
  • D21B1/30—Defibrating by other means
  • D21B1/32—Defibrating by other means of waste paper
  • D21B1/325—Defibrating by other means of waste paper de-inking devices
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
  • D21C5/02—Working-up waste paper
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/10—Bleaching ; Apparatus therefor
  • D21C9/1026—Other features in bleaching processes
  • D21C9/1052—Controlling the process
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
  • D21F1/70—Pulp catching, de-watering, or recovering; Re-use of pulp-water by flotation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/64—Paper recycling

Definitions

• the invention relates to a method for the carrying out of a flotation, bleach and/or dispersion process serving for the manufacture of fiber or paper while using one or more method stages in which process steps defined by pre-settable chemical and physical routines are carried out and process optimizations are made in dependence on measured values and characteristic value formed therefrom, optionally while using state models.
• the accepted stock that is the pulp suspension
• the reject which is flotation foam which as a rule still contains small parts of the pulp suspension
• flotation cells can, for example, be used here and serve in particular for the removal of contaminants, in particular printing ink particles, from paper pulp suspensions, in particular suspensions of waste paper. Further typical contaminants are, for example, stickies (particularly sticky substances).
• microflotation for example, filling materials and grain particles are regained from paper or cardboard machine sieve filtrates .
• de-inking flotation printing inks and other hydrophobic (water-repelling) particles such as adhesive are removed from the waste paper suspension with the aid of air bubbles and suitable process chemicals.
• Flotation is as a rule characterized by the fact that air and possible aids (e.g. soaps, surfactants) are added to the suspension and the air bubbles are given the opportunity to rise to the top in a reaction vessel with the adhering contaminants.
• air and possible aids e.g. soaps, surfactants
• the overflow rate can amount to up to 80% due to a high content of printing ink and ash.
• the overflow rate for suspensions also depends in particular on the respective portion of oil-based printing inks in addition to the ash content of the respective suspension, with suspensions with a high portion of oil-based printing inks resulting in particular with newspaper and magazine paper and such with a low portion of oil-based printing inks in particular in laser printing and office waste.
• the parameters of influences which affect the flotation process can be divided into parameters which are based on the raw material and which cannot be influenced such as the kind of ink particle, ash content, etc. and into parameters which can be influenced by a technical process in the flotation such as reject volume, air content, bubble size, chemicals, etc.
• the individual process steps that is for example flotation, dispersion and bleaches
• a corresponding optimization comprises, for example, the adjustment of a certain nominal whiteness or a certain loss amount (yield).
• a combination of a plurality of target values has, as a rule, not yet existed. It is in particular not available at present when a plurality of process steps running successively are present within one stock preparation.
• this object is satisfied in that at least the measured values of at least one method stage, which relevantly affect the target values of the respective end product of the method, are detected online and/or in that the characteristic values determined from the measured values of at least one method stage are evaluated online and used directly or indirectly for the control or optimization of at least one process, with characteristic values being formed in dependence on the starting material or raw materials and/or on the chemicals, auxiliary materials, energies and/or materials and emissions to be disposed of, which are added in at least one method stage.
• Such a method can be used advantageously in particular in the regulation of a flotation plant, whereby this can be accordingly optimized in particular with respect to the maintenance of a constant quality (e.g. whiteness, brightness, specks of contaminant or ash content), the maintenance of a constant solid material loss and/or a minimization of operating costs with constant quality (e.g. by modification of the soap dosage and the solid material loss).
• a constant quality e.g. whiteness, brightness, specks of contaminant or ash content
• a constant solid material loss e.g. by modification of the soap dosage and the solid material loss
• the determination of the characteristic values from the online measured values can in particular be carried out using mathematical or economic algorithms.
• At least one of the following values is preferably detected for the determination of at least some of the measured values and characteristic values: measurable parameters such as ash content, consistency, optical properties, specks of contaminant, printing ink residues, pH values, temperatures, flows, currents, powers, filling levels, use of auxiliary materials and/or stickies in the inflow, accepted stock and/or reject and/or values (characteristic values) calculated from the measurable parameters such as whiteness increase, reaction or throughflow times, specific work, solid material loss and/or ash loss and/or economic values such as cost of chemicals, of auxiliary materials, of water, of raw materials, of energy, of loss and/or of waste disposal which put the technological and economic values into relationship.
• measurable parameters such as ash content, consistency, optical properties, specks of contaminant, printing ink residues, pH values, temperatures, flows, currents, powers, filling levels, use of auxiliary materials and/or stickies in the inflow
• accepted stock and/or reject and/or values characteristic values
• the values considered in the regulation can thus, for example, be divided up into four categories: technological, measurable parameters, technological characteristic values determined with the aid of calculation operations from the technological measured values, economic characteristic figures, which can, for example, be expressed in “DM of chemicals per point of whiteness gain”.
• the maximization, minimization and/or maintaining constant of the production volumes, of the mechanical and/or optical properties and/or of the costs of the operating materials, raw materials and/or finished materials can be pre-set as the target values.
• At least one of the following process parameters is appropriately influenced: air content of the paper pulp suspension in at least one method stage, in particular in a primary stage and/or in a secondary stage, bubble size, chemicals and/or the like.
• At least two method stages and/or at least two processes can be combined with one another and be put together to form a respective jointly controlled and jointly optimized module.
• a compressed or reduced number of characteristic values formed in a respective module can expediently be used for the control of one or more processes.
• At least some of the target and characteristic values are transformed to a uniform base by means of a computing unit.
• the price per unit quantity can be selected as the uniform base.
• At least one of the following parameters is pre-set as the target values: constant optical properties (e.g. whiteness), constant ash quantity, minimum and/or constant specks of contaminant, minimum losses, minimum use of chemicals and/or minimum energy input.
• At least some of the target values is advantageously weighted prior to their use for the control and optimization of the process(es), with it being of advantage if the weighting takes place via an evaluation in accordance with cost aspects and/or via the carrying out of a cost optimization.
• At least one of the following values is detected for the determination of at least some of the measured values and characteristic values: consistencies, ash concentrations, filling levels, overflow quantities, residual amounts of printing ink, residual amounts of peroxide, temperatures, pH values, dispersing work, fiber dimensions, chemical doses, dwell times, optical properties, mechanical properties.
• An electronic control and/or regulation device is preferably used to carry out the process. Such a control and/or regulation device then has the software required for the relevant process optimization.
• a cost optimization is preferably repeatedly carried out by means of the control and regulation device while taking the respective technological know-how into account.
• the relevant cycle time can lie, for example, in an order of magnitude of some seconds, for example in a range from around 3 to around 10 seconds. However, other cycle times are also possible depending on the respective circumstances.
• the determination of at least some of the measured values and characteristic values is carried out via at least one sensor, in particular at least one sensor for the measurement of whiteness, online contamination, consistency, flow and/or level.
• a one-stage laboratory flotation cell of the kind described above can respectively be used, for example, as a trial machine for the optimization of the regulation of a flotation plant.
• Raw material 100% newspaper/magazine with 12% ash content (predominantly non-flammable paper filling materials).
• the material is treated in a flotation cell such that the whiteness potential present is economically utilized, with a whiteness of, for example, 56% ISO resulting.
• a foam overflow of, for example, around 8% has to be set, with this value being given in relation to the solid material, that is in “% oven dry”. If the ash content of the raw material changes to 20%, for example by more magazines containing filling materials, then the overflow must be increased, for example, to 13% oven dry.
• Raw material office waste.
• the raw material should likewise again have an ash content of, for example, 12%. This can, however, reach the technically meaningful whiteness with an overflow, for example, of just 5% oven dry due to the different printing ink composition. As a consequence of the better, more expensive raw material, this is even higher at 72% ISO. If the ash content of the raw material changes to, for example, 20%, then the overflow is regulated to, for example, 8% oven dry.
• the respective parameters can be converted in particular to a uniform base (cost per quantity).
• the goals to be achieved can, for example, be the following:
• a weighting of the targets is carried out, for example, via the evaluation in accordance with cost aspects and via the carrying out of a cost optimization.
• the know-how described further below can be verified in the relevant plant and integrated in the regulation, with the regulation constantly carrying out a cost optimization taking the technological know-how into account, for example according to a cycle time of around 3 up to around 10 seconds.
• the detection of the individual parameters can take place using commercial sensors (e.g. sensors for the measurement of whiteness, online-specks of contaminant, consistency, flow and/or level) and/or in combination with special sensors or sensors to be newly developed.
• commercial sensors e.g. sensors for the measurement of whiteness, online-specks of contaminant, consistency, flow and/or level
• special sensors or sensors to be newly developed e.g. sensors for the measurement of whiteness, online-specks of contaminant, consistency, flow and/or level
• the further possible machines include, for example, washers.
• Costs for hydrogen peroxide, caustic soda, water glass and/or the like have to be taken into account, for example, in the costs for the relevant bleaching chemicals.
• the respective loss costs can in turn be determined from the respective costs per quantity and the relevant loss percentage points. The same also applies, for example, in connection with any sodium dithionite used.
• the gain in whiteness in the individual bleaching stages is not proportional to the bleaching chemical quantities used.
• the bleaching potential of fibers is limited. Printing inks and ash (anorganic constituents) cannot be bleached. These rather maintain a certain graying level.
• the temperature in the heating coil must be increased by, for example, 35° C.
• the temperature in the heating coil must be increased by, for example, 35° C.
• around 0.3 tonnes of saturated steam are, for example, consumed per tonne of pulp.
• the specific saturated steam costs then result for the saturated steam consumption present.
• the specific energy of the dispersion amounts, for example, to around 80 kWh/t.
• the relevant costs per quantity result from the respective kWh price.
• the more specific energy is used in the dispersion the smaller (less visible) the specks of contaminant become. If, however, a lot of specks of contaminant are present in the inflow, then the graying (whiteness loss) is also stronger. It is also possible that these particles are not removed at high printing ink concentrations, but are rubbed even deeper into the pulp.
• the possible parameters include, for example, the following:
• the flotation 1 is run with different losses, whereby a larger loss of whiteness results in the dispersing means in the event of low losses since more printing inks are present.
• the subsequent bleach results in both cases in the same increase in whiteness.
• More losses are naturally run in the flotation 2 from the material which was run with a higher yield in flotation 1 . Nevertheless, not all printing inks can be removed since the dispersing means has kneaded these into the material in part.
• the whiteness deficit can only be compensated by an additional reductive bleach.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7655173

Family Applications (1)

Country Status (4)

Cited By (5)

Families Citing this family (9)

Family Cites Families (6)

• 2000
  • 2000-09-06 DE DE2000143893 patent/DE10043893A1/de not_active Withdrawn
• 2001
  • 2001-08-17 EP EP01119933A patent/EP1186706A3/de not_active Withdrawn
  • 2001-09-05 US US09/947,425 patent/US20020056531A1/en not_active Abandoned
  • 2001-09-05 CA CA 2356586 patent/CA2356586A1/en not_active Abandoned

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