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WO2011064458A2 - Procédé et agencement permettant de commander une salle de classage - Google Patents

Procédé et agencement permettant de commander une salle de classage Download PDF

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Publication number
WO2011064458A2
WO2011064458A2 PCT/FI2010/050973 FI2010050973W WO2011064458A2 WO 2011064458 A2 WO2011064458 A2 WO 2011064458A2 FI 2010050973 W FI2010050973 W FI 2010050973W WO 2011064458 A2 WO2011064458 A2 WO 2011064458A2
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WO
WIPO (PCT)
Prior art keywords
screen
rotational speed
pulp
parameter
screening
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/FI2010/050973
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English (en)
Other versions
WO2011064458A3 (fr
Inventor
Petri Harju
Sami Siik
Jussi Pakarinen
Pasi HEINÄMÄKI
Simo Kiero
Risto Ljokkoi
Hannu Rönkönharju
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Andritz Oy
Original Assignee
Andritz Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Andritz Oy filed Critical Andritz Oy
Publication of WO2011064458A2 publication Critical patent/WO2011064458A2/fr
Publication of WO2011064458A3 publication Critical patent/WO2011064458A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G9/00—Other accessories for paper-making machines
    • D21G9/0009—Paper-making control systems
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp
    • D21D5/023—Stationary screen-drums
    • D21D5/026—Stationary screen-drums with rotating cleaning foils
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp
    • D21D5/06—Rotary screen-drums

Definitions

  • the present invention relates to a method and arrangement for controlling/monitoring a screening process and a screen during screening of fiber suspen- sion in a screening apparatus having a screen drum for dividing the feed fiber suspension into reject and accept and a rotor, in which the driving power for the rotor or the screen drum is an electric motor, the rotational speed of which is adjusted by means of a frequency converter.
  • the first principle in screen sorting is forcing the fiber suspension through a perforated or slotted screen plate, where the holes or slots have such a size that individual fibers pass through and impurities remain on the screen plate. A precondition for this is that the fiber bundles have been adequately separated from each other and the reject is removed efficiently in order to avoid clogging of the screen plate.
  • Essen- tial in screening is that the fibers and impurities can travel in the fiber suspension independently of each other.
  • Consistency of the fiber suspension is of importance in this connection.
  • Continuous dispersing of the fiber network on the surface of the screen plate is essential in order to prevent flocked fibers and fibers attached to impurities from entering the reject flow.
  • the fiber suspension is forced to be exposed to the effect of shearing forces either by vibrating the screen or by creating an adequate turbulence by means of suitable rotor solutions.
  • the proportions of axial flow (from the inlet to the reject outlet), cross-flow on the screen plate surface and tangential flow are decisive in view of separating efficiency. Also the size and the pattern of the holes or slots are decisive in view of separating efficiency.
  • the parameters used for the regulation and sizing can be divided to pulp parameters, machine parameters and running parameters and operational values.
  • pulp parameters directly measurable are feed consistency, temperature and pH and periodically determinable kappa, fiber length and shive content of the feed.
  • the machine parameters are mainly constant, such as the type of the screen drum and the rotor, the area of the screening surface and these cannot be influenced during the operation of the screen.
  • the wearing degree can be mentioned, which is understood mainly as the wearing of the rotor and the screen as function of time.
  • Measurable running parameters include feed, accept and reject flow and reject dilution liquid flow as well as the rotational speed of the rotor or the screen drum.
  • characteristics can be calculated for the screen, such as flow-reject ratio, reject dilution ratio and slot speed.
  • the operational values of the screening apparatus comprise the motor's input power, torque and pressures in the accept and reject conduits, pressure difference (such as pressure difference between feed and accept, pressure difference between feed and reject), which are measured during the run, and the consistency of the reject and the accept, which are measured more rarely.
  • pressure difference such as pressure difference between feed and accept, pressure difference between feed and reject
  • Separation efficiency can be determined by means of the shiver content of the feed and the accept.
  • US-patent 6165370 discloses a system, where a pressure transducer monitors the pressure difference over the screen drum in a pressure screen. Also the accept amount is monitored. The operator sets the threshold value for the pressure difference as a function of accept flow amount. When the operator notices that the pressure difference threshold value has been exceeded, he can start the required corrective actions for decreasing the pressure difference. He can adjust the system to decrease the accept flow amount, to increase the reject flow amount or to completely close the accept flow. Each of the measures is planned to remove the particles that clog " the screening surface. When the threshold value of the pressure difference as a function of accept flow amount is actively adjusted, the number of un- needed corrective measures started by the system can be reduced.
  • GB-patent 1584715 presents a method where the pressure difference between the feed and discharge of the screen is measured.
  • the screening surface of the screen is cleaned by means of vanes fixed in a shaft.
  • the shaft is rotated by a motor, the speed of which is regulated based on pressure difference. If the pressure difference rises over a certain level, the speed increases, and if the pressure difference decreases below a certain level, the rotational speed of the motor decreases.
  • the aim is to reduce the energy consumption for obtaining the desired screening result.
  • An increase in the speed of vanes sweeping the screening surface breaks the pulp fiber network that hampers the screening.
  • GB-patent 2035824 discloses an ar- rangement for removing material that has accumulated on the screen surface.
  • the rotor of the screen is run at a speed that varies according to at least one physical parameter of the fiber suspension, which may be pressure, flow amount or the concentration of the fiber suspension. A deviation from a predetermined value changes the speed of the rotor.
  • the concentration of the fiber suspension is measured at the discharge of reject or accept, because a change therein indicates clogging of the screen surface.
  • Corresponding screen adjustment methods are disclosed also in patent publications WO 83/01969 and EP 1689931.
  • An object of the present invention is to eliminate above mentioned problems and provide an automatic adjustment and control system for a screen, where the operation of the screen is adjusted anticipatorily so that its drifting outside a safe operational range and into a disturbance condition is prevented as efficiently as possible and thus the operation of the apparatus without disturbing interruptions is ensured, and thus premature wearing of the apparatus is reduced.
  • the present invention relates to a method of controlling/monitoring a screening process by means of an automatic system during screening of fiber suspension in a screening apparatus having a screen drum for dividing the feed fiber suspension into reject and accept and a rotor, in which the driving power for the rotation of the rotor or the screen drum is an electric motor, the rotational speed of which is adjusted by means of a frequency converter based on pulp parameters, machine parameters and running parameters.
  • Essential for the invention is that pulp parameters and/or running parameters of the screen are measured and based on the measurement results the operational value's functional dependence on the rotational speed in relation to a pulp parameter and/or running parameter is determined for each screen, when the operational value is motor input power, torque, accept flow pressure, reject flow pressure, pressure difference, reject consistency and/or accept consistency, and the rotational speed is adjusted anticipatorily according to these dependences by means of an automatic system so that the screen operates within an optimal operational value range that is deter- mined based on said dependence .
  • the invention also relates to an arrangement for controlling/monitoring a screening process by means of an automatic system during screening of a fiber suspension in a screening apparatus.
  • the invention is based on the idea that the operational values and operational capacity of the screen room and an individual screen room apparatus, such as a pressure screen or other apparatus are dependent on the pulp parameters and running parameters. For these, a functional dependence has been developed, where an op- erational value is a response that can be anticipatorily influenced by measuring pulp , and running parameters and adjusting the rotational speed of the motor.
  • the rotational speed is adjusted by means of a frequency converter based on measured parameters of the pulp, the apparatus and the running mode, when the design effect of these on the operational values of the screen is known during operation of the screen, and for each screen is determined a well runnable design dependence of the operational value on the rotational speed in relation to the pulp parameter and/or running parameter.
  • Design means that the effect of a change in a pulp or running parameter on the operational value during the operation of the apparatus is known.
  • the functional dependence of an operational value on said parameters is known and when during a run the value of said parameter for some reason changes, it is known how the operational value will change.
  • the apparatus does not tolerate a change in a pulp parame- ter, and its screening surface is getting clogged. However, the runnability is to be maintained.
  • the automatic system of the apparatus increases the rotational speed of the motor so that the operational value remains within an optimum range, whereby e.g. power input or pressure difference may remain unchanged.
  • machine parameters are taken into account, which comprise the type of the screen drum and the rotor, the area of the screen, its position in the screening process or the wear degree of the apparatus, which now can be anticipated and the data utilized.
  • the machine parameters cannot be changed during a run, but said operational value dependence is determined individually for each screen, which has a certain machine parameter combination, such as a certain motor type, a type of opening of the screen drum's screening surface. These parameters can be changed during shutdown. Wear rate obtained as a function of time when the operational values are changing indicates the operational capacity of the apparatus.
  • the automatic system of the apparatus continuously measures one or more pulp, apparatus and running parameters and anticipa- torily adjusts the operational value of the apparatus to an optimal range by changing the rotational speed, based on known functional dependence.
  • Pulp parameters comprise feed consistency of the pulp suspension, temperature, pH, Kappa, fiber length, type of slurry and shiver content of the feed.
  • Running parameters comprise the feed flow amount of the fiber suspension, i.e. the production (volume/time unit, such as l/s, m3/min, or weight/time, such as kg/s) or the feed dilution liquid flow or the reject flow amount.
  • the operational values of the apparatus/screening room i.e. power input, torque, pressures in accept and reject conduits, pressure difference (such as between the feed conduit and the accept conduit, between the feed and reject conduit) and the accept and reject consistencies, can be dimensionally calculated anticipatorily by measuring pulp parameters and running parameters and preferably also machine parameters.
  • the functional dependence of the operational value of the apparatus on the rotational speed at a certain pulp pa- rameter or running parameter value when the operational value is the motor power input, torque, pressure, pressure difference, reject and/or accept consistency, as mentioned in the above.
  • the apparatus is run with this certain pulp or running parameter value and the rotational speed is changed based on this dependence so that the apparatus will remain within a desired advantageous operational value range.
  • Figure 1 illustrates an optimum adjustment of a screen, such as a pressure screen, by means of a frequency converter.
  • an operational value 1 such as motor power input
  • the functional dependence of an operational value 2 is determined with three different pulp, machine or running parameters, e.g. with three different feed consistency values (three curves marked with reference 1 ).
  • the functional dependence of an operational value 2, such as pressure difference between the feed and the accept, on the rotational speed is determined with a certain pulp and/or running pa- rameter value, e.g. with two different feed consistency values (two curves marked with reference 2).
  • Typical pulp and running parameters include feed consistency and production amount.
  • the operational values of a screen are, as shown in Figure 1 , curvilinearly function-dependent on a pulp or running parameter, such as production consistency level and feed con- sistency level, as well as the rotational speed of the motor.
  • the dependence illustrated in the figure shows that with a frequency converter the apparatus can be run with minimum energy consumption by reducing the rotational speed of the rotor by means of the frequency converter as long as the power input of the apparatus decreases. At a turnover point the apparatus has reached the limit of its operational capacity.
  • the runnability of the apparatus can be improved in a possible disturbance situation or the runnability can be standardized by increasing the rotational speed of the motor during a required time.
  • the present invention allows determining the conditions that enable the running of the apparatuses at low circumferential speeds.
  • the aim is to run the screening room at minimum load and minimum energy consumption and to ensure good runnability - no production losses caused by the screening room.
  • This regulation that is based on the use of a frequency converter further clearly enables the running with both higher consistency and higher production level.
  • the prior art is based on the idea that by measuring the operational values created by the apparatus, such as output, pressure difference, reject/accept consistency, it is possible to measure a forthcoming failure condition of the apparatus and after that by taking corrective measures (a change in the rotational speed of the rotor (rpm), additional dilution) to restore the good running condition of the apparatus or at least to prevent significant clogging.
  • the aim is to restore an apparatus that is clogged or is being clogged back to running condition - a direct feed back control. That is, the apparatus has drifted over the operational values of its rated range unforeseeably.
  • a func- tional dependence in accordance with the invention on said parameters exists for the operational values. Based on this dependence, the screen can be run in a desired way preventing it from drifting into disturbance situations.
  • the method according to the invention also allows monitoring the wearing of the parts of the screening apparatus in an advantageous way.
  • a reference point is measured for the apparatus at an average rotational speed recognized to be suitable (e.g. 1500 rpm) and the input power is measured at start-up of the apparatus.
  • the power decreases during operation due to wearing of the apparatus.
  • the wearing of the apparatus can be monitored by measuring at certain intervals (e.g. once per day) the reached input power at said rotational speed (e.g. 1500 rpm), when the pulp and/or running parameters are at set values.
  • the power that is reached decreases in time compared to the above-mentioned reference point.
  • the power that is reached is so low that it indicates wearing of the apparatus or decrease in operational capacity due to some other reason.
  • the situation requires replacement of the interior parts of the apparatus, such as the rotor or the screen drum, or other service.
  • This adjustment method allows arranging the replacement of the parts of the apparatus and the repair in an improved way.
  • the apparatus is preferably run at as low rotational speed as possible and thus at minimum energy level based on functional dependence.
  • the parts of the apparatus wear its capability to operate within the set pulp and running parameter values weakens in time, i.e. its runnability is impaired.
  • the apparatus is drifting outside its optimum operational value range at said rotational speed.
  • the risk caused by wearing is compensated by increasing the rotational speed, because the optimum operational value range is transferred based on functional dependence.
  • the automation system of the apparatus takes care of the increase of the rotational speed.
  • the rotational speed is adjusted also based on internal wearing of the apparatus.
  • Figure 1 illustrates graphically the functional dependence of an operational value of the screen on the rotational speed of the motor in accordance with the invention
  • Figure 2 illustrates a screen known per se, in the operation of which the present invention can be applied
  • FIG. 3 illustrates schematically an embodiment according to the invention
  • Figure 4 illustrates a control result according to the invention
  • Figure 5 illustrates schematically a control method according to the invention
  • Figure 6 illustrates monitoring of the wearing degree of the screen in time
  • Figure 7 illustrates the input power of the screening apparatus in time.
  • FIG. 2 illustrates an exemplary screen that typically can be operated according to the method of the present invention.
  • the screen 10 comprises the following parts: an outer casing 12, an inlet conduit 13 for pulp and outlet conduits 14 for accept and 15 for reject therein, a stationary screen drum 17 and therein an essentially cylindrical rotary rotor 16.
  • the apparatus further comprises a ro- tatable shaft 20 and as a driving force a motor 19, the rotational speed of which is regulated by means of a frequency converter.
  • the power transmission from the motor to the rotor is effected by means of either belt drive and/or a gear.
  • the operation of the apparatus according to the figure is essentially such that the fiber suspension is fed via conduit 13 into the apparatus, wherein it is passed into a gap between the screen drum 17 and rotor 16.
  • the accept flown through the apertures on the surface of the screen drum is discharged from conduit 14, and the pulp that has flown to the lower end of the gap between the screen drum 17 and rotor 16 and thereout is discharged from reject conduit 15.
  • Heavy reject is discharged from conduit 11.
  • Dilution water for reject is led via line 21.
  • Figure 2 shows that the surface of rotor 16 on the side of the screen drum 17 is provided with rotor elements 18 in form of protrusions.
  • the rotor elements can be like those described in US-patent 5000842, as shown in the figure, whereby the protrusions on the casing surface of the rotor are mainly formed of front surfaces facing the flow, preferably surfaces parallel to the rotor casing surface and rear surfaces that descend towards the rotor casing surface.
  • the rotor elements can also be similar to those of WO- publication 2009040464, whereby a rotor element is mainly formed of a front surface facing the flow, an upper surface and a descending trailing surface that is curved and has side edges that at least along a part of their length converge towards the back point of the element.
  • Figure 2 illustrates just one preferred screen construction that can be used in accordance with the present invention, and the invention is not limited thereto.
  • the rotor of the screen can e.g. be mounted directly on the shaft of the driving motor. Further, instead of a rotor the rotating part can be a screen drum when the rotor is stationary.
  • Figure 3 illustrates schematically a screen 30 and conduits connected thereto and adjusting devices therein for applying the method according to the invention. In this case, consistency adjustment and frequency converter regulation 38 are used as required.
  • the fiber suspension is fed by means of a pump 31 via conduit 32 to the screen, where the screening surface 33 divides the suspension into an accept fraction 34 and a reject fraction 35.
  • a functional dependence according to Figure 1 of an operational value on the rotational speed in relation to feed consistency has been determined for the screen.
  • the feed line 32 is. additionally provided with consistency measurement 36 and dilution liquid conduits 37 for adjusting the feed consistency and maintaining it at a set value. If it is desired to run the apparatus at low energy consumption, the rotational speed is decreased by means of a frequency converter and the consistency is kept essentially at the set value by measuring the consistency and reacting quickly to a possible consistency increase by adding dilution liquid. It is preferable to use a precise consistency meter that can be mounted essen- tially in the vicinity of the pump 31 and to the discharge side thereof and add dilution liquid as requires as quickly as possible.
  • the screen's inner consistency can be measured at the reject side by means of a meas- uring device 39 or at the accept side by means of a measuring device 40.
  • the measuring device 39 is connected to dilution liquid conduits for diluting the reject if needed in the reject space, should the consistency exceptionally increase.
  • the accept can be diluted in the accept space.
  • Figure 4 illustrates consistency adjustment during operation of the apparatus according to prior art (unbroken line) and according to the present invention (broken line).
  • a problem of the prior is, as already mentioned, even remarkable deviations from the set value, which can cause disturbances in the screening process and which require oversizing of the apparatus.
  • also consistency adjustment is performed anticipatorily, whereby high peaks of the prior art can be prevented. This can be reached by means of precise consistency measurement and dilution, if needed. Further this is assisted by continuous adjustment of rotational speed according to the invention, whereby it is possible to react to consistency changes also by changing the rotational speed, by increasing it as the consistency increases. This way it is possible to keep the consistency value close to the set value continuously. There is no need to oversize the apparatus for wide varia- tions in consistency values, but a low deviation of consistency values is adequate for sizing margin.
  • Figure 5 illustrates in form of block diagram, an anticipatory automatic control method and arrangement according to the invention.
  • Pulp parameters and/or run- ning parameters in conjunction with the apparatus as well as operational values are measured at various rotational speeds and the measuring signals are received by the automatic system of the apparatus.
  • the machine parameter data has also been entered into the adjustment system.
  • the regulator device performs multivariable-based function calculation. Typical measurements include feed consistency or output and as operational value the input power of the screen.
  • the regulator device calculates and determines for the screen the functional dependence of the operational value on rotational speed in relation to a pulp parameter and/or running parameter when the operational value is motor input power, torque, accept flow pressure, reject flow pressure, pressure difference, reject consistency and/or accept consistency.
  • the regulator device determines limit values, between which the operational value, such as power, is to be during operation of the apparatus according to a desired mode, for maintaining continuous runnability of the apparatus.
  • the adjustment system correspondingly changes the rotational speed for maintaining a good operational parameter value in view of operation.
  • the operational value range is influenced by the desired mode of the apparatus.
  • the mode to be optimized can be energy.
  • the adjustment system changes the rotational speed so that the input power is at minimum energy level with the parameter values in question.
  • the mode to be optimized can preferably also be the runnability of the apparatus.
  • the automatic system itself handles the change of mode from the minimum energy level for ensuring runnability, whereby the apparatus due to e.g. wear increases the rotational speed for raising the obtained power.
  • the operation of the apparatus is adjusted anticipatorily and thus drifting to disturbance conditions and stoppages is minimized and even prevented.
  • the apparatus resists even a remarkable disturbance peak e.g. in consistency, because due to the adjustment of rotational speed the apparatus reacts quickly, before drifting to the actual disturbance condition.
  • the apparatus can be run at maximum production.
  • the invention allows higher feed consistency than before, whereby maintaining the consistency is the aim to be optimized.
  • An operational value such as pressure dif- ference
  • the adjustment system returns it to an advantageous value by changing the rotational speed.
  • An increasing pressure difference indicates that the flow through the screening surface is getting disturbed as the internal consistency of the apparatus increases.
  • the adjustment system increases the rotational speed for eliminating these initial signs of clogging.
  • the adjustment system decreases the rotational speed and thus also the required power.
  • the apparatus is capable of maintaining stabile conditions in view of consistency during the process, because the adjustment system detects and eliminates any possible consistency deviations in an early stage.
  • the apparatus is capable of adjusting itself via the adjustment system and there is no need for personnel to perform these adjustments.
  • the adjustment system of the apparatus anticipates a changing situation and automatically regulates the rotational speed and if needed also pulp and running parameters so that the apparatus operates at proper parameter values and operational value range.
  • a pulp parameter, feed consistency adjustment is performed so that the fiber suspension is diluted, if the consistency increases in an undesired way from the set consistency value.
  • the operation of the apparatus is controlled by means of feed forward control and not feed back control as in prior art, where an adjustment is performed only when a disturbance situation has occurred.
  • Figure 6 illustrates the wearing in time of parts of the apparatus.
  • the apparatus is typically run continuously at the same rotational speed of the motor, e.g. 1500 rpm.
  • the speed is so high that pressure shocks and ma- jor friction forces cause wearing of the apparatus.
  • the control system according to the invention allows running the apparatus at as low a rotational speed as possible, in the range of proper operation of the apparatus, and thus at minimum energy level.
  • the average rotational speed is for instance 1200 rpm, which is essentially lower than in prior art. Thereby pressure shocks and friction forces remain lower and thus the wearing of the apparatus is slower, as shown in Figure 6.
  • Figure 7 illustrates the decrease in the input power of the apparatus in time, as the apparatus wears.
  • the method according to the invention also allows monitoring the wearing of the parts of the apparatus in an advantageous way.
  • the power decreases during operation due to wearing of the apparatus.
  • the wearing of the apparatus can be * monitored by measuring aLcertain intervals (e.g. once per day) the reached input power at said rotational speed (e.g. 1500 rpm), when the pulp and/or running parameters are at set values.
  • the power that is reached decreases in time compared to the above-mentioned reference point, as illustrated in Figure 7.
  • the power that is reached is so low that it indicates wearing of the apparatus or decrease in operational capacity due to some other reason.
  • the situation requires replacement of the interior parts of the apparatus, such as the rotor or the screen drum,
  • the automatic system is capable of diagnosing the condition of the apparatus with regard to wearing degree.
  • the rotational speed is regulated also based on internal wear of the apparatus.
  • the rotational speed is increased as the wearing degree increases, but on the other hand the apparatus can be run at minimum energy level, whereby the rotational speed is increased only to an extent that is necessary for ensuring the runnability of the apparatus.
  • the apparatus has worn to the extent when regulation measures can not improve the runnability but replacement of parts is required.
  • running at minimum energy level extends the service life of the apparatus and its parts.
  • the invention allows anticipatory acting on the operational values by means of ad- justing control.
  • By means of the invention it is in most cases possible to prevent the drifting of an individual apparatus/screening room to a disturbance condition and to optimize the desired process effect: minimum energy consumption, high consistency, good quality, high production, good runnability, maintainability, wear resistance, etc.
  • the invention enables changing the sizing of a screen room/screen and other equipment in the screen room.
  • the screen room as a process and the apparatuses used therein can be designed for a higher consistency and a greater capacity compared to existing applications.
  • the invention enables optimum running pf an individ- ual apparatus of the screening room and the screening itself e.g. at minimum energy level.
  • the invention enables better runnability, disturbance resistance and wearing resistance as well as longer replacement interval for a screen drum and a rotor.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
  • Combined Means For Separation Of Solids (AREA)
  • Preliminary Treatment Of Fibers (AREA)

Abstract

La présente invention concerne un procédé et un agencement permettant de réguler un procédé de classage et/ou un classeur au moyen d'un système automatique pendant le classage d'une suspension fibreuse dans un appareil de classage possédant un tambour de classage permettant de diviser la suspension fibreuse en rejetés et en acceptés et un rotor. La puissance d'entraînement pour le rotor ou le tambour de classage est un moteur électrique dont la vitesse de rotation est régulée au moyen d'un convertisseur de fréquence à base des paramètres de pâte à papier, de machine et d'exploitation. Les paramètres de pâte à papier et/ou d'exploitation du classeur sont mesurés et pour chaque classeur, une dépendance fonctionnelle d'une valeur opérationnelle sur la valeur de rotation est déterminée par rapport au paramètre de pâte à papier et/ou du paramètre d'exploitation basé sur les résultats de la mesure, lorsque la valeur opérationnelle est la puissance d'entrée du moteur, le couple, la pression de l'écoulement des acceptés, la pression de l'écoulement des rejetés, la différence de pression, la cohérence des rejetés et/ou des acceptés. La vitesse de rotation est ajustée de façon anticipée en fonction de ces dépendances au moyen du système automatique de sorte que le classeur fonctionne dans une plage de valeurs opérationnelles optimales qui est déterminée sur la base de ladite dépendance.
PCT/FI2010/050973 2009-11-30 2010-11-29 Procédé et agencement permettant de commander une salle de classage Ceased WO2011064458A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20090455A FI20090455A7 (fi) 2009-11-30 2009-11-30 Menetelmä lajittamon säätämiseksi
FI20090455 2009-11-30

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WO2011064458A2 true WO2011064458A2 (fr) 2011-06-03
WO2011064458A3 WO2011064458A3 (fr) 2011-07-28

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019055973A3 (fr) * 2017-09-18 2019-05-09 International Paper Company Procédé et appareil de commande de système de fractionnement de fibre
CN113950551A (zh) * 2019-06-14 2022-01-18 福伊特专利有限公司 确定制造纤维料幅的机器的抽吸辊子的污染的方法和装置

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2035824A (en) 1978-11-17 1980-06-25 Wikdahl L Fibre-suspension screen apparatus
GB1584715A (en) 1976-06-03 1981-02-18 Tampella Oy Ab Method and apparatus for classifying a suspension
WO1983001969A1 (fr) 1981-11-24 1983-06-09 Nils Anders Lennart Wikdahl Procede permettant d'empecher l'obturation d'un dispositif de filtration
US5000842A (en) 1987-04-30 1991-03-19 A. Ahlstrom Corporation Method and apparatus for treating fiber suspension
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