DE1815307A1 - Method and device for controlling the nature of paper stock to be fed to a headbox - Google Patents

Description

PATENT ADVOCATE

7 STUTTGART 1, MOSERSTRASSE 8 TELEPHONE (0711) 244003

Dec. 17, 1968 - BE 251 -

BELOIT CORPORATION,
1, St. Lawrence Avenue, Beloit, Wisconsin 535H * USA ™

Method and device for control the nature of the stock to be fed to a headbox

The invention relates to a method and apparatus for controlling the nature of stock which is supplied to the headbox is fed to a paper machine »If there are paper stocks of different consistencies in a corresponding one Number of storage containers, the paper stock is made from each container in the required proportion of one Main stock chamber, where a mixture takes place until the final paper stock of the desired consistency is created » The paper material passes from the main material chamber via a flow control valve into a cleaning device around the paper material

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from dirt, fiber knots and the like «before he is fed to the headbox of the paper machine »The temperature of the paper stock is set before it enters the cleaning device measured, and also the pressure drop in the paper stock as it passes through the cleaning device certainly. These pressure and temperature values of the paper stock are used to determine and generate control signals to control the Monitor stock feed to the cleaning device and thereby the properties of the paper stock fed to the headbox to keep on the desired predetermined conditions * '

The invention is thus related to headbox systems with a cleaning device to remove dirt and fiber knots from the paper stock before it is finally used flows towards the headbox of the paper machine «In the embodiment according to the invention described below the cleaning device has a cylindrical screen arrangement mounted with a vertical axis, which are at a radial distance from one another extending inner and outer screen parts or »drums, so that a chamber for receiving between these screen parts of the material of the desired consistency is created, from which the material is discharged to the outlet of the cleaning device will. Means are provided within the cleaning device to reduce the pressure drop either between the inlet and outlet in the device or between the sieve arrangement of the device to eat.

Up to now, the control of the nature of the paper stock fed to the head of a paper machine has been carried out on the basis periodic manual sampling of different states of the paper stock flowing into the head box »Die Information obtained through such periodic sampling was used to determine those rule or control tables that had to be changed to achieve the desired material properties. With the sampling carried out periodically by hand, could

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ultimately the desired properties of the casserole box can be achieved on the forming screen flowing paper stock. However, the length of time between sampling and manual readjustment in the paper stock feed system leads to a considerable amount Change in the paper stock emerging from the head box »

The aim of the present invention is to provide a method and a device in a paper stock delivery system in order to automatically to determine various essential properties of the paper stock for the generation of sampling signals, which are automatic to generate regulation or control signals with which the various required actuating devices of the control system are changed so that the paper stock emerging from the headbox is the same Maintains quality »

For this purpose, according to the invention, an inflow or »delivery system for paper stock which is relatively simple in construction and easy to maintain at one at the same time high efficiency and a reliable way of working « According to the invention, a method for the continuous analysis of various changes in properties is also provided of the paper stock flowing from a rotating pump of the system to the headbox and a method for precise measurement of the pressure drop via the cleaning device connected in front of the headbox in the flow path.

The measurement of the pressure drop of the paper stock flowing through the cleaning device can be carried out in various ways. One possibility is to measure the at the inlet and outlet of the cleaning device or at the immediate Proximity of its existing pressure and in comparing the pressure readings to determine the exact pressure drop between the inlet and outlet. Another option is to attach

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Pressure tools inside the cleaning device, namely in the immediate vicinity upstream in front of and downstream behind the sieve parts *

The result obtained by the pressure gauges is preferable calibrated for reading in cm water column or fractions thereof (or kp / cm), with which the pressure difference is represented, the one above the cleaning device or above the sieve plates consists. As soon as the flow directed towards the sieve plates reaches a continuity for a certain mechanical setting has only the consistency or the quantity and quality of the paper stock fed to the cleaning device create a change of state in the system that leads to a changed pressure drop

It has been found that with fixed mechanical conditions within the cleaning device, ie certain material flow, the consistency of the flowing back or circulating paper stock can be brought to the desired liquid level by adding heavy paper stock into the system · This is done while observing the changes in the pressure drop across the cleaning device »

According to the invention, these pressure changes are used to generate continuous sampling signals, which are then combined with other important available data or measurement results are fed to a computing device. The computing device generates various control signals to automatically regulate the various control devices in the inflow system and to operate and the desired paper stock properties at the output of the system to achieve and maintain.

The invention is illustrated below with reference to one in the figures Embodiment explained in more detail «

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* 1 shows a schematic overview of an inflow system for paper stock according to the invention, while

Fig. 2 shows a cleaning device according to the invention partially in a vertical section.

Referring to Fig. 1, a stock flow system 100 includes a paper stock cleaning device 10, from which the paper stock in the desired consistency is fed to a head box 101 is supplied «The pressure drop between that in the cleaning device 10 inflowing stock and the paper stock leaving the cleaning device is measured by a pressure measuring cell 102 sensed, which via lines 10J5 and 104 with the inlet or » with the outlet of the device 10 is in communication. According to the invention taking place continuous determination of the pressure drop in which the cleaning device 10 flowing through Paper stock provides important information on further use for regulating the nature of the paper stock flowing into the headbox 110. Although according to the illustration the pressure measuring cell 102 is in communication with the inlet and outlet of the device 10 via its supply measuring lines also independent pressure gauges within the cleaning device be arranged to measure the pressure drop at the required points within the device

A pulp suspension with the required properties is collected in a main chamber 106. Multiple paper trays 107 * 108, 109 and 110 supply the main chamber 106 with Paper stock of various properties, which is mixed there to form the suspension with the desired properties. The reservoir 107 is connected to the main chamber 106 via a flow control valve 111 and a flow meter 112 Connection · In the same way, the storage container 108 is connected to the main chamber via a valve Ilj5 and a flow meter 114 · The storage container 109 protrudes via a control valve 115 and a flow meter 116 and the storage container 110 a valve 117 and a flow meter 118 in communication with the main chamber 909831/0218

The control valves 111, Ilj5 and 115 as well as II7 are each with Actuators lila, Ilj5a, 115a or * ll? A equipped, over which the amount of paper stock flowing through the valve is set will. The actuators lila, Ilj5a, 115a and 117a stand with a Computing device 120 in connection »

The computing device 120 continuously evaluates various parameters of the control system and generates control signals for the actuating devices, so that the paper stock delivered to the headbox 110 steadily maintains the desired properties. All are for this purpose Quantity measuring devices 112, 114, 116 and II8 with a measuring tap line 121, 122, 12j5 or »124 which are sent to the computing device 120 are connected and continuously supply measurement data, e.g. about those from the individual storage containers I07 to 110 to the Main chamber I06 amount of paper stock dispensed (volume).

Stock of the predetermined consistency is now from the exit the chamber I06 is supplied to a flow control valve 126, which is connected to the arithmetic unit 120 via a line 127 via a Actuator 126a is operated. The outlet side of the control valve 126 is connected to a flow meter 128, which in turn in connection with the computing device 120 via a display line 129 stands »The output side of the flow meter 126 is connected to a vane pump IJO via a line 1J51» Also a water tank 132 is connected to the vane pump I30, in which the white water dripping underneath the forming wire of the paper machine collects. The water tank 132 is via a Line 13J5 connected to the IJO vane pump. The water tank 132 is via a line 134 and a flow control valve I36, its actuating device 136a via line 137 to the computing device 120 is connected, steam is supplied. By regulating the amount of steam fed into the sieve drainage water in container 132, the Keep the temperature of the paper stock within a predetermined value range.

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The output side of the pump 130 is connected via a line Γ59 a temperature sensor 138 in connection, the temperature of the Paper stock and continuously emits temperature test signals from this point of the feed system. The electrical output of the temperature sensor is again in connection with the computing device 120 via a line 138a, while the paper stock is connected to a Flow meter 148 as well as to a control valve 141 is passed on «, the control valve 141 is via a line 140 with the Input side of the vane pump I50 in connection with »The line 140 with the control valve 141 thus forms a circulation path or return path for excess paper pulp conveyed from the pump I30 » The control valve 141 comprises ein.Stellgerät 141a, which is electrically with a headbox control 142 via line 142 in connection stands. The headbox control is connected via a line 144 to the headbox 101 in order to have a predetermined Sensing material level or a predetermined pressure within the headbox and the pressure level within a predetermined The flow line 144 is connected to a control valve 146 with which the overflow is switched off the overrun box 101 is controlled. The actuator 146a assigned to the control valve 146 is electrically connected to the overrun control 142 in connection · The electrical output of the overrun control 142 is connected to the computing device 120 via a line 147 ©

The paper stock flowing through the meter 128 becomes the Cleaning device 10 and from there the headbox 101 fed.

In the operating state, the flow meters 112, 114, 116, 118, 128 and 148 as well as the overrun control 142, the temperature sensor 138 and the differential pressure measuring cell 102 generate continuous test signals which are fed to the computing device 120.The computing device generates continuous control signals for actuating the various actuating devices, the are assigned to the control valves in the system _#

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A preferred embodiment according to the control system The cleaning device 10 associated with the invention is shown in Pige 2. The cleaning device 10 includes a Standing part 11, which carries a main housing 12 of approximately circular outline »is in the vicinity of the upper part of the housing 12 an inlet for receiving a fiber suspension, e.g. paper stock, intended. The substance enters a chamber 15 within the housing 12, from where the desired proportion of substance through a Sieve drum 16 passes through and is collected in an outlet chamber 17 The sieve drum 16, an inner sieve drum 18, a support member 19 arranged between the screen drums 16 and 18 and a ring element 20 form a cylindrical screen assembly 22 which has the shape of a double-walled tube. The outer cylindrical screen drum 16 surrounds uiter support on the ring-> element 20 with radial spacing concentrically the cylindrical screen drum 18 «

The support member 19 has the task, the screening drums 16 and 18 the to give the necessary rigidity against the pressure of the inflowing material to be screened. The substance fills the chamber 15 and flows over the cylindrical Sieve arrangement 22 into a chamber 25 lying radially inside the sieve arrangement 22 »Therefore, the desired proportion of substance, which has flowed into the chamber 25, pass the sieve 18, collect in the outlet chamber 17 and flow from there through a main outlet 27.

The heaviest unusable material fractions are eliminated in several processes, mainly by centrifugal force collected in a receiving chamber 28 and then discharged via an outlet 29. Another unusable part of the substance, the heavier one is than the desired proportion of substance, is excreted by gravity and sinks to the bottom of the chamber 15. The bottom of the chamber 15 forms a channel 30 to which an outlet 3I is connected is. Another channel 33 is at the bottom of the chamber 25 to the portion of the substance that cannot be used for processing

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take up the top of the screen assembly 22 in the chamber An outlet 34 is connected to the channel 33 and absorbs the unusable material that has accumulated there «

One or more rotatably arranged wing blades 35 extend on the outside axially directly along the surface of the screen arrangement 22 »In a preferred embodiment of the According to the invention, there are several blades 35 at equal intervals on the circumference of the sieve arrangement 22 «The blades 35 are in rotary motion to clean the surface of the sieve drum 16 of material parts that would otherwise clog the sieve Some of the undesired material components removed from the sieve drum 16 are deposited on the floor of the chamber 15 in the channel 30 fall and are discharged through the outlet 31, while others unwanted pieces of fabric carried away in suspension over the screen assembly and finally collected in the channel 33 and through the Outlet 34 are discharged.

Similarly, there are equidistant ones Wing blades 37 radially inside the sieve drum 18 in the vicinity of the surface thereof. The blades 37 are also in a rotating motion to remove unusable material from the To remove inner surface of the sieve drum 18 which would otherwise clog the sieve. These parts of the substance are in the gutter collected and discharged through outlet 34.

The housing 12 of the cleaning device 10 consists of an upper part 40 and a lower part 41, which are secured by several screws 42 are connected to one another at the flanges 43 and 44. the outlet chamber 17 communicating with an main outlet 27 is formed by a spiral housing 45, the largest diameter of which at outlet 27 lies “On one side of the volute there is a concentric opening 46 in a plane perpendicular to its axis, which with the cavity between the Screen drums 16 and 18 of the screen assembly 22 in direct connection stands. 909831/02 18

Inside the lower part 41 of the housing there is a concentrically molded hub that protrudes into the area of the upper part 40. A sleeve 49 is mounted concentrically inside the hub 48, in which a shaft 50 is rotatably supported in bearings 51 * 5 ^> 53 and 54 * retaining caps 56 and 57 are mounted on the upper and lower ends of sleeve 49, respectively, to secure bearings 51, 52, 53 and 54 and shaft 50 therein. A cover 60 closes the upper end of the hub 48, and a seal 61 lies between the shaft and the wall of a passage opening in the cover 60.

A flap 64 is detachably connected to the upper free end of the shaft 50 via a wedge spring 65. A cap nut 66 screwed onto the shaft 50 holds the puddle 64 in place. One or more, indicated by broken lines arms 68 extend from a fixed to the flange 64 ^R:; ng 69 radially outwards. Each of these arms 68 carries one of the wing blades 55. One or more arms 70 are also attached to the ring 69, each of which carries one of the wing blades 37. The wing blades 35 or 37 can be permanently or detachably connected to the associated arm *

The wing blades 35 have extensions or extensions 72 which engage in a stiffening ring 73 lying radially outside of the wing blades. This stiffening ring 73 is connected to all blades 35 and serves to prevent axial (or longitudinal) bending of the blades, which would result in a gap between the blades 35 and the lower part of the sieve drum 16. The blades 37 have lugs 75 »with which a stiffening ring 76 radially is connected within the blades »The ring 76 serves essentially the same purpose as the ring 73 ·

The upper part of the housing 12 is provided with an inlet channel 80, which is designed as a spiral housing. The spiral housing 80 has an opening in its radially inner region, which with communicates with the interior of the housing 12 in order to supply the pulp suspension to be cleaned to the housing 12.

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A cover 82 is on the upper portion 40 of the housing 12 fastened with the aid of several screws 83 and nuts 84. in the Cover 82 has a threaded connector 85 for any pipe »

The lower end of the shaft 50 extends into the stator housing 11 and is connected to a multiple V-belt pulley 89, which via several V-belts 90 with a suitable Drive is connected «

Although individual outlets 29 »31 and 3k are provided in the illustrated embodiment of the invention, this type of construction is not binding be provided, which take up or remove the unusable material fractions that are otherwise taken up by the outlet J> ~ L »In the same way, the housing 12 can have several outlets in connection with the chamber 25, in order to remove unusable material parts from it»

According to the invention, the cleaning device 10 includes a pressure measuring cell 200 which is located within the spiral housing-shaped outlet chamber 17 is arranged to print the fabric on the output side of the device 10 to measure «Zv / ei further pressure measuring cells 201 and 202 are immediately next to or on the inner or» arranged outer sieve parts. The cells 201 and 202 can be connected in parallel so that they have an average pressure indicate the prevailing for the initial input of the cleaning device Pressure is decisive. With an independent arrangement, the measuring cells are able to measure the pressure drop across the inner sieve drum and also to determine the pressure drop on the outer sieve drum

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The accuracy of the measurement of the pressure drop in the cleaning device 10 is preferably maintained in the range of 0.00127 kg / cm (12.7 mm water column) in order to allow the pulp delivery system works with the best possible efficiency »Die Druckmeßgeräte preferably consist of membranes pre-tensioned with air pressure with a diameter of approx. 50 mm and are either at the inlet and outlet of the cleaning device or located at the Sieve arrangement arranged. The pressure drop sensed by the measuring cells in the cleaning device then becomes one commercially available differential pressure cell supplied. In such a differential pressure cell with zero point suppression takes place a compensation for the greater part of the pressure drop and a further remaining pressure drop can be recorded or can process the signal further, which now only contains the upper range of the measured variable component in shows on a greatly enlarged scale. This upper variable area can mathematically be used as a puncture of changes in the amount of fiber, the texture and composition of the fibers and expressed in changes in temperature when the flow is constant »

By recording and displaying this Druckdlfferentiäls and using the original signal to further control the Method Jn such that the main valve (stuffgate) for the The material is fed to the machine via a loop or return system The machine can be controlled by continuously sensing various influencing variables in the system monitor «Is the pressure differential expressed in mathematical terms?

P (p) dt = K ₁ - ^ p £ ^ W + K ₂ -! - I as + K ₃ - ~~ | Λ T

where Q, = flow rate of the fiber suspension (constant) W - change in amount of fiber (consistency) S = change in fiber type and composition (geometric Shape, surface quality and also fiber type)

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T = changes in temperature t = time

Kl ₄ , K2, K3 = constant

The method and device described above are based on the assumption that the flow of material to the headbox is constant and can also be kept in this state (if necessary by means of corrections), since the pressure drop across the cleaning device can be determined empirically for any given flow value. The variables which cause the pressure drop in the cleaning device for a specific hydraulic and mechanical arrangement are determined beforehand by experiments the shape of the fibers (slenderness ratio, length _# surface, material type, etc. ") normally remain during a Papierherstellungsverfärens within a certain quality ~ or range of values constant addition, the amount of material or" fiber content within the suspension (consistency) are controlled to predetermined material properties to maintain * the The invention thus provides a method and a device for determining changes in the consistency of the fiber quantity to an extent that has not previously been considered feasible. "

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Claims (1)

PATENT ADVOCATE 7 STUTTGART I ₁ MOSEKSTRASSE 8 TELEPHONE (0711) 244003 Beloit Corporation, Beloit, Wisconsin, USA December 17, 1968 - BE Fat e nt ans prUche 1 »Process for controlling the quality of the paper stock listed in the headbox of a paper machine, characterized in that the paper stock is a cleaning device (lo) is supplied that the in the cleaning device (10) located paper stock a headbox (101) that the pressure drop of the paper stock is measured as it passes through the cleaning device and that the consistency of the cleaning device fed paper stock as a function of the pressure drop measured during its passage through the cleaning device is controlled » 2 * Method according to claim 1, characterized in that the the cleaning device (10) supplied flow rate of the Paper stock is measured that the measured pressure drop of the paper stock flowing through the cleaning device processed mathematically with the measured flow rate and thus the properties and the amount of the cleaning device fed paper stock are monitored « 2, method according to claim 2, characterized in that the Temperature of the paper stock fed to the cleaning device is measured and the measured temperature together with the measured pressure drop and the measured flow rate are processed computationally in order to determine the properties of the dem To regulate the paper stock fed to the headbox. 909831/0218 4 _# Method according to one of the test sprays 1 to J5, characterized in that several material flows (ΐογ-llo) differing from one another by different consistencies are fed to a common container (1O6) * » that the material flows in the common container (10β) are mixed in order to form a paper stock of the desired consistency, that the paper stock of the desired consistency is passed through a flow control device (126 _ß 141), that the temperature of the paper stock as it passes through the flow control device it is measured (138) that the paper stock is fed to the cleaning device (10), that the pressure drop of the paper stock as it passes through the cleaning device is measured (102), that the paper stock is off. the cleaning device is fed to a headbox (101), that when the paper stock passes through the flow control device measured temperature x ^ ert and that when passing through the Cleaning device (10) measured pressure drop processed computationally v / ground, and that the flow of material in the direction of the headbox is controlled as a function of the computationally processed measured values. 5 · Device for carrying out the method according to one of the preceding Claim ©, characterized in that the cleaning device (1O) for cleaning the fiber-containing material fed to the headbox (101) of a paper machine from a housing (12) consists of arranged at a perpendicular distance from each other Inlet (14) and outlet (1?), Also from a sieve arrangement (22) inside the housing for cleaning and sorting the raw paper stock flowing through the stream, and that in the cleaning device first (200) and second (201, 202) pressure gauges are arranged at a distance from one another in such a way that the first Pressure measuring device is upstream of the second pressure measuring device and thereby a display for the pressure drop between them is created « 909831/0218 6 »Device according to claim 5» characterized in that the housing (12) of the cleaning device (10) has a number of openings, one of which forms an inlet and the others a plurality of outlets, that a cylindrical sieve arrangement (22) on inner and outer sieve parts (18, 16) which are arranged at a radial distance from one another and form a sieve chamber that a 'spiral-shaped space (45) is provided essentially concentrically to the housing (X2) with a lateral, with the sieve chamber in connection standing opening (46) in a plane perpendicular to the axis of the spiral housing, the spiral housing space (45) having a portion protruding outward from the housing which forms an outlet (27) for a useful portion of the paper stock, the first and second blades - ■ blades (55 » 37) are provided so that they can rotate concentrically inside the housing immediately adjacent to the inner or outer screen parts (18, 16) d, to prevent clogging of the sieve parts, further. Drive means (90, 50, 64) for the rotation of the blades are arranged within the housing, and that first and second pressure gauges (200, 201, 202) are arranged within the housing to measure the pressure drop in the paper stock between the inlet (14) and that Outlet (17), which stirs the usable proportion of substance. 7. Device according to claim 6, characterized in that the first and second pressure measuring devices (201, 202) in the housing are arranged so that the pressure drop across the cylindrical screen arrangement is measured * 8 »Device according to claim 6, characterized in that the first pressure measuring device (200) of the wall of the spiral housing (45) and a second pressure measuring device (201) in the area of the inner Sieve part (18) is arranged to determine the pressure drop of the paper stock flowing through the sieve part, while a third pressure measuring device (2θ2) directly on the outer screen part (16) is arranged to determine the pressure drop of the paper stock flowing through this wire part 909831/0218 AT- 9 »Device according to one of claims 5 to 8, characterized by an inflow system (100) for monitoring the consistency and quantity of the headbox (101) of a paper machine supplied paper stock, with a plurality of storage containers (107-110) for paper stock of different consistencies, a main chamber (106) for receiving the paper stock, each with a flow rate regulator arranged between a storage container and the main chamber (ill, 115 * 115 * H7)> by the amount discharged from each reservoir into the main chamber To control paper stock, further by a downstream of the main chamber (106) arranged flow regulator (126, 141) and a sensor (1 ^ 8) to determine the temperature of the Volume regulator of flowing paper stock, through a cleaning device (10) connected to the volume regulator (126, 141), by first and second pressure measuring devices (200, 201, 202) arranged in the cleaning device, measuring the pressure drop at the Cleaning device and by a computing device based on the measured values of the pressure drop and the temperature of the paper stock responds and the volume controller (ill, 113 · * ♦) at the output of each Reservoir (107, 108. ♦ «) monitored and thereby the consistency of the stock supplied to the main chamber (106). 909831/0218