EP0092678A2 - Appareil et procédé pour indiquer la longueur de fibres - Google Patents

Appareil et procédé pour indiquer la longueur de fibres Download PDF

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Publication number
EP0092678A2
EP0092678A2 EP83102884A EP83102884A EP0092678A2 EP 0092678 A2 EP0092678 A2 EP 0092678A2 EP 83102884 A EP83102884 A EP 83102884A EP 83102884 A EP83102884 A EP 83102884A EP 0092678 A2 EP0092678 A2 EP 0092678A2
Authority
EP
European Patent Office
Prior art keywords
stock
orifice
chamber
fiber
length
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.)
Withdrawn
Application number
EP83102884A
Other languages
German (de)
English (en)
Other versions
EP0092678A3 (fr
Inventor
Donald W. Danforth
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.)
Bematec SA
Bolton Emerson Americas Inc
Original Assignee
Bolton Emerson SA
Bolton Emerson Americas Inc
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 Bolton Emerson SA, Bolton Emerson Americas Inc filed Critical Bolton Emerson SA
Publication of EP0092678A2 publication Critical patent/EP0092678A2/fr
Publication of EP0092678A3 publication Critical patent/EP0092678A3/fr
Withdrawn legal-status Critical Current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
    • D21G9/0018—Paper-making control systems controlling the stock preparation
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
    • D21D1/002—Control devices
    • 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
    • D21F1/0009—Regulating the freeness of the pulp

Definitions

  • the present invention relates to apparatus and methods for testing length of fibers in paper stock or pulp.
  • continuous digesters have replaced batch digesters, i.e. wood chips and chemicals are continuously introduced to, and pulp is delivered from, a complex system of vessels, piping, etc.
  • batch digesters i.e. wood chips and chemicals are continuously introduced to, and pulp is delivered from, a complex system of vessels, piping, etc.
  • a problem is encountered inasmuch as several species of wood are utilized and it is essential to segregate resulting pulp according to species, i.e. a pulp made from softwood must be segregated from pulp made from sawdust, etc.
  • the principal object of this invention is to provide such an apparatus and method so that a signal is generated to inform the operator when a pulp interface passes, or that stock is refined to the correct fiber length and quality.
  • a prior patent which more closely relates to measuring fiber length is U.S. Patent 3,873,416 to Forgacs of March 25, 1975 but the device requires the stock to be substantially diluted rather than at operating consistency in the paper making system.
  • the Forgacs device works on a continuous flowing stream principle and not on a sampling sequence and makes use of a fractionating screen which is vertically oriented and vibrates.
  • an apparatus and method for monitoring the length of fibers in refined paper stock, or in unrefined paper pulp is provided, wherein the read-out is achieved periodically, while the fibrous slurry is in the paper making system at operating consistency.
  • the measurement chamber of the freeness tester can be exposed to ambient atmospheric pressure, rather than to negative pressure, and a constant level head box used between the stock line and the tester as in the Myers Patent 2,734,378 of February 14, 1956.
  • a significant feature of this invention is that instead of using a meshed screen, or a slotted plate, the fiber length indicator disclosed herein makes use of an imperforate plate extending across a measurement chamber and having at least one orifice, or hole, of predetermined area or configuration and of predetermined cross dimension, or diameter, substantially equal to the relative length of the fiber to be detected as of changed species or as of desired relative length.
  • the upstanding container When change of pulp species in a pulp line is to be detected the upstanding container has its lower end directly connected into the system, with no by-passing or re-. sort to laboratory manual testing.
  • the fiber length indicator, or detector automatically and periodically cycles through intake measure and discharge with the electric probes, or other level sensing means, in the measurement chamber repeatedly signalling "correct” as long as the predetermined set intake time signals that the fiber length of the species is flowing. When another pulp species interface is encountered, it will result in fibers of a different length so that the read-out will be "incorrect length".
  • a meshed screen, or multiperforated plate corresponding to a screen, such as used in a freeness tester will not function as the partition across the measurement chamber of the fiber length indicator because the stock being measured is of high consistency or density and cannot be screened in the normal sense.
  • a single orifice is sometimes preferred, but multiple such orifices of similar, or different, diameters such as four have usually been found preferable.
  • the range of orifice diameters depends on the length of fibers to be measured and may range from one millimeter for extremely fine, synthetic fiber to about twenty millimeters for relatively unrefined rag fiber.
  • the fiber length indicator of the invention may have a variety of replaceable plates, each with at least one orifice of different configuration, or area to accomplish "coarse tuning", the fine tuning being accomplished by the operating variable of differential pressure across the orifice. Over a reasonable range, the same orifice can differentiate different fiber lengths depending on the driving force, the best operation appearing to be from 0.5 to 1.5 psi.
  • a paper stock system 20 is shown diagrammatically in Figure 1, the system including a beater 21, valve 22, stock conduits 23, pump 24, conduit 25, and a stock refiner 26 of the disc, Jordan or "Claflin" type.
  • the refiner 26 discharges into a conduit 27, conduit 27 having a fiber length indicator 28, according to the invention, installed therein, with a control system such as shown in Figure 7 or Figure 11.
  • Conduit 27 includes a valve 29 and discharges back into the beater 21 or elsewhere as desired.
  • the fiber length indicator 28 includes an upstanding stock container 31, similar to the above mentioned “Drainac” freeness tester, and connected directly to a paper, or pulp, conduit 27, which forms a part of stock system 20, and contains paper stock, or pulp 32, at operating consistency so that it is of relatively high consistency and has not been diluted for laboratory or by-pass testing.
  • the stock container 31 is divided, intermediate of its height, by an orifice plate 33, to form an-upper portion 34, which is the measurement chamber, and a lower portion 35, the lower end 36 of the lower portion 35 being connected to the stock, or pulp, supply 27 to receive the stock, or pulp, 32 therefrom, at operating consistency.
  • the orifice plate 33 is not a meshed, perforate screen, but instead is of imperforate material, such as metal, and includes at least one orifice 37 formed by the rim 38 in the plate.
  • the orifice 37 is preferably cylindrical and is of predetermined diameter substantially equal to the relative length of the fibers, such as 39, to be monitored in the measurement chamber 34.
  • the orifice 37 could be of other shapes, configurations or cross sectional areas, such as triangular so long as its cross dimension is of predetermined width corresponding to the predetermined relative length of the fiber to be measured, but a cylindrical orifice is found much preferable.
  • fiber slurries represent a range of fiber lengths from several millimeters to less than one millimeter with distribution similar to a probability curve.
  • the shorter fibers pass the orifice while the longer fibers do not until eventually sufficient long fibers collect to prevent further passage.
  • the volume of the stock passing the orifice is a measure of relative fiber length, other conditions being equal.
  • the slurry is not dewatered as a result of passing through the orifice.
  • plates each with a different sized orifice can be substituted in the fiber length indicator of the invention until a particular sized orifice, in the preset intake time indicates the desired relative length of fiber to meet the standards, or production requirements,, of the processing plant. Thereafter, the same plate and orifice will repeatedly be cycled to monitor production and indicate any variation in quality revealed by a change of relative length of fiber in the slurry.
  • the tubular, cylindrical orifice 37, in each plate 33, has a diameter which is within the range of about twenty millimeters for rag fibers suitable for roofing felt base to one millimeter for highly refined flax pulp suitable for cigarette tissue.
  • the diameter illustrated is about one millimeter for highly refined flax pulp suitable for cigarette tissue, or for fine synthetic fibers.
  • FIG 3 an orifice plate 41, similar to plate 33 is shown, wherein the rim 42 forms a substantially cylindrical orifice 43 of about twenty millimeters in cross dimension, or diameter, for use in measuring fibers in relatively unrefined rag pulp suitable for roofing felt base.
  • an orifice plate 44 is shown which is similar to plate 33 and 41 except that it is formed with a plurality of identical orifices, such as five, designated 45, 46, 47, 48 and 49, which may be circular, triangular, square, or other configurations of relatively uniform cross dimension. Multiple orifices, of similar or different diameters, can be used to average out the testing of the fiber length measurement results.
  • an orifice plate 51 is shown having an orifice 52 of variable area, configuration and cross dimension together with means 53 for varying the same.
  • the orifice 52 may be formed as a camera shutter or preferably, as shown, by a pair of oppositely disposed, sliding gate's 54 and 55 each with a V-shaped cut out 56 or 57 therein and actuated from outside the container, during operation by suitable push rods 58 or 59.
  • the orifices such as 37, 43, 45 and 52 are preferably of the standard type formed in thin plate with a downstream and upstream sharp square edge. They are not designed to create a jet but more properly might be designated holes or apertures.
  • a baffle, or target plate 61 is provided at a spaced distance above each orifice such as 37 to spread out and dampen any jet of paper stock or pulp up into the measurement chamber 34.
  • the target plate 61 is preferably the lower end of a cylindrical, solid rod 62 supported from above, to avoid interference with incoming material.
  • a set of orifice plates such as 33, 41, 44 or 51, each with an orifice of different diameter, and perhaps totalling ten to twenty plates in the set, may be provided with each fiber length indicator 28.
  • the plates are each seated in a plate recess 63 at the split 64 so that the upper portion 34 may be released and hinged rearwardly on hinge 65 to permit replacement of the plates in the set and refastened by bolt 66.
  • the container 31 is not only separable at mid-height 64, but the upper portion is preferably a transparent tube seated on annular gasket 70.
  • Slurry level sensing means 67 is provided within the upper portion, constituting the measurement chamber 34, and formed by at least one, and preferably by both a lower electric probe 68, and an upper electric probe 69. Other suitable slurry level sensing means may be used.
  • a differential pressure controller using a sensor 71 ( Figure 11) is included-in the system 20 to ensure precision of control conditions.
  • a differential pressure is essential (of the order of 1 psi) and while one can substract pressure in the measurement chamber 34 from the line or stock pressure in stock or pulp line 27, the gauge 93 avoids arithmetic error and makes the system simpler and more foolproof.
  • a check valve 72 ( Figure 5) may be incorporated with each orifice plate to prevent upstream passage anywhere through the plate except through the orifice but to permit ready downstream passage through the plate during the exhaust cycle back into the stock line.
  • a dump valve 73 ( Figure 7) may also be provided to facilitate discharge from the measurement chamber 34 through an auxiliary opening during the exhaust cycle.
  • a water valve 74 provides dilution water from a supply conduit 75 to flush out the parts and assure that all fibers are returned to the pipe line 27.
  • a fiber length indicator 28 is shown, connected into a paper stock, or paper pulp line 27 containing the high consistency liquid 32 to be measured, which may be at any line pressure, with the line pressure not affecting differential pressure.
  • the liquid 32 is directed into the upstanding open top tube 76 centrally located in the upstanding open top tube 77 so that it will flow over the rim 78 and into the discharge 79.
  • the hydraulic head, or pressure remains constant as the liquid is guided out of the bottom 81 of tube 76, into the lower portion 35 of container 31, by conduit 82.
  • An automatic control means 83 includes the air input tube 84 having one end 85 in chamber 34 and leading to a source of air pressure 86 such as mill air. It also includes the air exhaust tube 87, having one end 88 in chamber 34 and leading to the atmosphere or preferably to a source of negative air pressure 89.
  • the automatic timing means 91 is connected to the two probes, or electrodes 68 and 69 and the read out means is designated 92.
  • the automatic control means includes a cycle timer 93 of known construction, connected by suitable electric circuits and to conductors 94 and 95 to the purge or dump valve 73, conductors 96 and 97 to the water dilution valve 74, conductors 98 and 99 to the electrodes 68 and 69 and conductors 101 and 102 to the air input valve 103 and the air exhaust valve 104 to actuate the same by suitable solenoids as programmed.
  • the automatic control means 83 is similar to the control means disclosed in the above mentioned U.S. Patents 3,186,215 of June 1, 1965 and 3,538,749 of November 10, 1970 in which the freeness tester disclosed therein is automatically cycled through intake, measure and exhaust.
  • a suitable plate 33 having at least one orifice 37 with a cross dimension and area capable of passing fibers of substantially the correct relative length desired, is installed in the seat or recess 63, the indicator 28 closed and the cycle timer 93 actuated.
  • the cycle timer then cycles the measurement chamber 34 through intake, measure and exhaust by opening air exhaust valve 104 to negative pressure or atmosphere, thereby enabling the fibers in the stock or pulp line to attempt to pass through each orifice 37 into the chamber 34.
  • a predetermined set intake time for the cycle is established by the cycle timer so that if no stock passes through the orifice to reach lower probe 68 before expiration of the set intake time, "blow down" or exhaust is-initiated and the read out signal "too long” is displayed at 92. This is the situation illustrated in Figure 8.
  • the differential pressure between stock line pressure and measurement chamber pressure is indicated by the differential pressure gauge 71 ( Figure 11) and controlled. by the automatic control means 83 to be about 1 psi as compared to about 7 psi in the freeness tester of my said patents.
  • the check valve 72 in each orifice plate enables the one way return of stock from the chamber 34 back into the stock line 27 during the blow down or exhaust cycle and the dump valve 73 also enables rapid clearance of chamber 34 during exhaust.
  • the cycle timer 93 is programmed to supply flush water through valve 74 to clear the plate and orifice of fibers or fibrous mats during the exhaust cycle also.
  • a constant hydraulic head in the open inner tube or container 76 in the arrangement of Figure 7, assures that any variations in stock line pressure do not affect measurement in the container 31 shown in that view.
  • Intake time may be about ten seconds and exhaust time also about ten seconds and the fiber length indicator may be cycled at any desired intervals to provide a read out of exact fiber length passing through stock, or pulp line 37 and to warn the operator that a different type pulp is passing by the indicator.
  • a precise control of the quality of stock produced by refiners such as 26 is obtained by periodically measuring fiber length in a stock line 27 with a fiber length indicator 28, and periodically measuring freeness in the stock line 27 with a freeness tester 105, such as the " D rainac" of above mentioned prior patents U.S. 3,538,749 and 3,186,215.
  • the freeness tester 105 shown in dotted lines in Figure 1, and the fiber length indicator 28 are shown as both connected to a control system such as illustrated in F ig- ure 7, including the control means 83 and a circuit 106 to the drive means 107 of the refiner so that refining effect is controlled automatically to compensate for any variations in fiber length or freeness.
  • a control system such as illustrated in F ig- ure 7, including the control means 83 and a circuit 106 to the drive means 107 of the refiner so that refining effect is controlled automatically to compensate for any variations in fiber length or freeness.

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  • Paper (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)
EP83102884A 1982-03-24 1983-03-23 Appareil et procédé pour indiquer la longueur de fibres Withdrawn EP0092678A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US36130082A 1982-03-24 1982-03-24
US361300 1982-03-24

Publications (2)

Publication Number Publication Date
EP0092678A2 true EP0092678A2 (fr) 1983-11-02
EP0092678A3 EP0092678A3 (fr) 1984-10-17

Family

ID=23421484

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83102884A Withdrawn EP0092678A3 (fr) 1982-03-24 1983-03-23 Appareil et procédé pour indiquer la longueur de fibres

Country Status (6)

Country Link
EP (1) EP0092678A3 (fr)
JP (1) JPS59655A (fr)
AU (1) AU568806B2 (fr)
BR (1) BR8301528A (fr)
CA (1) CA1203599A (fr)
FI (2) FI830951L (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE342574C (de) * 1921-01-30 1921-10-20 F R Poller Fa Vorrichtung zum Pruefen des Mahlungsgrades von Papierstoff
US2734378A (en) * 1956-02-14 Tinttfd
US3330151A (en) * 1963-01-22 1967-07-11 Defibrator Ab Apparatus for testing and recording the freeness of fiber suspension
US3538749A (en) * 1969-03-06 1970-11-10 Bolton Emerson Control for freeness tester
US3846231A (en) * 1972-07-25 1974-11-05 Westvaco Corp Apparatus for determination of the magnitude of total specific energy absorbed by a sample of pulp stock
US3873416A (en) * 1970-11-27 1975-03-25 Alkibiadis Karnis System for the continuous measurement of the weight-average fiber length of a pulp

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2734378A (en) * 1956-02-14 Tinttfd
DE342574C (de) * 1921-01-30 1921-10-20 F R Poller Fa Vorrichtung zum Pruefen des Mahlungsgrades von Papierstoff
US3330151A (en) * 1963-01-22 1967-07-11 Defibrator Ab Apparatus for testing and recording the freeness of fiber suspension
US3538749A (en) * 1969-03-06 1970-11-10 Bolton Emerson Control for freeness tester
US3873416A (en) * 1970-11-27 1975-03-25 Alkibiadis Karnis System for the continuous measurement of the weight-average fiber length of a pulp
US3846231A (en) * 1972-07-25 1974-11-05 Westvaco Corp Apparatus for determination of the magnitude of total specific energy absorbed by a sample of pulp stock

Also Published As

Publication number Publication date
FI830951A0 (fi) 1983-03-22
FI831006A0 (fi) 1983-03-24
BR8301528A (pt) 1983-12-06
EP0092678A3 (fr) 1984-10-17
AU1290283A (en) 1983-09-29
CA1203599A (fr) 1986-04-22
FI831006L (fi) 1983-09-25
JPS59655A (ja) 1984-01-05
FI830951L (fi) 1983-09-25
AU568806B2 (en) 1988-01-14

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Inventor name: DANFORTH, DONALD W.