FI103482B - A method and apparatus for controlling the grinding of a refiner - Google Patents

Description

103482

FIELD OF THE INVENTION The present invention relates to a new type of method and apparatus for controlling grinding of a wafer refiner, wherein the grinding control of the grinding material is effected by changing the pressure of the wafer refiner. The solution according to the invention can be utilized, for example, in milling wood pulp and other fibrous materials.

The disk refiner typically comprises two adjacent and opposed flour disks, one or both of which rotate. The face-to-face surfaces of the refiner discs are adapted to handle the abrasive article, which is mainly fed from the center of the discs and extends from the inside out between the refiner discs and exits therefrom into the enclosure surrounding the device.

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For example, when milling wood chips or wood pulp, where wood is fed between the milling discs in the center, the wood chips or wood pulp contains water. In addition, water is usually added during milling.

20 When steam is introduced into the blade of a fast rotating disc refiner, a mixture of wood chips or a mixture of wood pulp and water is generated. Large amounts of steam are produced because during the defibration process, energy is produced which is only partially consumed in the defibration process itself. Large amounts of vapor generated affect the milling pressures in the blade gap, as do the pressures. them in the refiner feed and in the refiner housing.

The prior art will be described below with reference to the accompanying figure 1, which illustrates the refining process and the forces acting on it.

Figure 1 shows a prior art refining process and the forces acting on it. The stator disk is denoted by 1, the rotor disk is denoted by * · ·; at 2 and the shaft bearing is designated 3. The forces are represented by arrows.

· ...: The vapor pressure between the blades causes the axial force of the refiner 4. In the same direction, the axial compression force exerted on the material to be refined by the blade 5. These forces are counteracted by the compressive force 6 and the axial loading force 7 of the refiner.

The pressure power 6 of the refiner cavity in high-consistency refining can be controlled by adjusting the steam outflow pressure from the refiner feed and the refiner housing, but 103482 2 steam pressure 4 in the blade range cannot be adjusted by the refiner in operation without affecting

5 In order to control the mechanical handling of the fiber with the blade brushes, it must be possible to control the flow of pulp and steam generated in the blade gap. Indeed, refiner blades are often designed so that the steam generated during refining has a sufficient flow volume in the blade groove.

In particular, the amounts of steam produced by grinding with high energy consumption are high, and it is known to form special "selectivity" for the steam in the rotor blade. Such a solution is described, for example, in Finnish Patent Publication FI-73256, Fig. 2. The selective groove effectively removes the blast-furnace steam produced by grinding.

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The dimensioning of the selective groove is based on the grinding conditions. Production, engine power, pulp consistency and other factors influence the size and barrier of the selective groove. The size of the groove and the embankment are critical factors affecting the milling pressure of the blade.

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A groove that is too large or too low will result in an excessive drop in steam pressure between the blades. This results in a reduction in blade pitch and an increase in refining power. The increased refining force results in a sharper refining and excessive breaking of the fiber to be refined. In practice, the grinding conditions vary e.g. that- : ·. . 25 production requirements and pulp quality requirements. Especially reject grinding. fluctuations in grinding conditions are a major disadvantage, making it difficult to design the • • · #j I # steam grooves in the grinding blade.

• · · .. The above difficulties are exacerbated by efforts to reduce energy consumption • ·: 30 in milling. Lower energy consumption is achieved by increasing refinement; the force of the blades by controlling the grinding so that the blade gap is reduced by, for example, increasing the volume of the steam grooves in the blade or by reducing the barrier in the steam groove.

35 A smaller blade spacing, in turn, causes increased fiber breakage and thus' ·. ·: Blade design seeks to find the best compromise between energy consumption and pulp quality, ie fiber length.

3, 103482

When grinding harder than usual and / or aiming for lower energy consumption, the refiner blade has a narrow operating range and even small changes in the process can easily cause large deviations in pulp quality. Therefore, adjusting the blade pressure would be a significant contribution to improving the control of high consistency grinding.

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It is an object of the present invention to provide an arrangement for controlling grinding of a disk refiner which solves the above problems and rectifies the deficiencies. To achieve this, the method according to the invention is characterized in that the blade refiner blade pressure is controlled by adjusting the steam outflow from the blade to the mass discharge end by a blade pressure control and externally movable dam mounted on the refiner blade. Further, the device according to the invention is characterized in that the device has externally movable dams for controlling the steam outflow from the blade gap by changing the size of the openings in the outer groove of the steam groove so that the grinding control from the blade to the discharge end of the pulley by means of movable dams for blade pressure control.

In the method according to the invention, the control of the grinding of a material to be ground, such as wood chips, wood fibers or other paper pulp, is accomplished by varying the blade gap pressure. Correspondingly, the blade refiner blade pressure is adjusted by varying the steam outflow from the blade gap. In the method according to the invention, a blade gap is mounted at the discharge end of the pulp: '. 25 pressure control member.

• · • · · • •. · ». The invention will now be described in detail with reference to the accompanying drawings, in which: Fig. 1 illustrates a prior art refining process and the forces acting on it, Fig. 2 illustrates a steel segment in FI patent 73256, and Fig. 1 structure of the disc refiner high-pressure regulator ·: ··· according to the invention.

1 i i i i i ·. Figure 1 is described above. The solution according to the invention will now be described below. Thus, FIG. 3 illustrates an embodiment of the solution of the invention.

• ·

Figure 3 illustrates the structure of a disc intermediate pressure regulator according to the invention. In the solution according to the invention, the stator disc is denoted by numeral 4 103482 and the rotor disk is denoted by 2. The adjusting device according to the invention has a steam groove 8 on the outer periphery of the stator disc 1 of the disc refiner.

It is known that the transport of steam between blades from the inside of the blade to the outer periphery is achieved by a selective groove in the rotor blade 2. At the end of the selective groove, the steam is discharged into the steam groove 8 on the periphery of the stator blade 1. The outer wall of the steam groove 8 has equally spaced openings through which the blade gap discharges steam into the refiner housing. The openings in the outer wall can be realized, for example, by means of a closure ring 9 with evenly spaced openings. 10 There may be, for example, 3-5 openings in the outer wall.

The solution according to the invention comprises externally movable dams 10, by means of which the flow of steam can be adjusted by changing the size of the openings in the outer wall of the steam groove 8. In this way, the vapor pressure at the blade gap and thereby the blade gap size can be adjusted independently of other grinding parameters, e.g.

Alternatively, the grinding adjustment can be accomplished by controlling the blade gap pressure, and thus the blade gap size, by automatically adjusting the height of the outflow dams 10, controlled by pressure or temperature.

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The solution of the invention can be used to control the vapor pressure of the high-consistency refiner blade. Correspondingly, the solution of the invention can also be used to control the flow of liquid from the blade consistency blade gap.

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Claims (8)

A method for controlling grinding of a wafer refiner, wherein the grinding control of the material to be milled is effected by varying the blade gap blade pressure, characterized in that the blade refiner blade pressure is controlled by changing the steam outflow from the blade to the bulk discharge end 2. Förfarande enligt patentkrav 1, kännetecknat av att träflis eller trämassa an-vänds vid malningen. Method according to Claim 1, characterized in that wood chips or wood pulp are used in the grinding 10. 3. Anordning för att styra malningen i en skivraffinör, omfattande en statorskiva, ·,: (1), en rotorskiva (2), samt yttre periphery av statorskivan (1) et ängspar (8), som. ' , möjliggör ängflöde mellan Betten i en tangential riktning, kännetecknad av att an-; läggningen har frän utsidan flyttbara fördämningar (10), med vilka ängflödet regie- »I i; i; ras genomic attländer storleken av öppningar i ängsparets (8) yttervägg sä att mal- * «I: · '25 ningen av ämnet som scall malas styrs genomic picture trycket mellan Betten ä attycycle mellan skivrafFmörens bett regleras genome attänd »· V: Betten account massans utmatningsände med flyttbara fördämningar (10) monterade mellan raffinörens bett för att styra trycket mellan Betten. • t • · • · < A device for controlling grinding of a disc refiner, comprising a stator disc (1), a rotor disc (2), a stator disc (1) on the outer periphery of a vapor groove (8), which enables steam flow in a sharp tangential direction, characterized in that (10) for adjusting the steam flow by changing the size of the openings in the outer wall of the steam groove (8) so that the grinding control of the grinding material is accomplished by varying the blade mill blade pressure by adjusting the by guiding movable dams (10). 4. Anordning enligt patentkrav 3, kännetecknad av att ängtransporten mellan •. Bettin inifrän bettet accounts den yttre peripheral genomförs med et selective spär utformat 'rotorbettet (2) spänder fränän av av selective spär utärär (8) loudbettets (1) peripheral, stem ypptervägg med jämna genome luck änga avgär mellan Betten account raffmörhuset. Device according to Claim 3, characterized in that the transport of the vapor from the inside of the blade to the outer periphery of the blade is effected by means of a selective groove in the rotor blade (2) so that steam is discharged from the selective groove steam (8), the outer wall of which has evenly spaced openings through which the v-blade discharges steam into the refiner housing. Device according to Claim 4, characterized in that the openings in the outer wall: T: 30 are formed by means of a closure ring (9) with evenly spaced openings. • · .... 5. Anordning enligt patentkrav 4, kännetecknad av att öppningama i ytterväggen utförts med en förslutningsring (9) som har öppningar med jämna mellanrum. 35, 103482 6. Anordning enligt patent krav 4 eller 5, tandecknings av att det finns 3-5 lessons and ytterväggen. Device according to Claim 4 or 5, characterized in that there are 3-5 openings in the outer wall. 7. An patent for a patent patent 3, 4, 5 eller 6, a turn-off of an att maling 5 regimen of a trickle-down sequence Betten and samtidigt även auxiliary styrs genome att automatically adjusting the hose utfödesfördämningama (10) under styming av trycket. Apparatus according to claim 3, 4, 5 or 6, characterized in that the grinding control is implemented such that the blade pressure, and also the blade nozzle, is controlled by automatically controlling the outflow dams (10) controlled by the blade pressure. height. Device according to Claim 3, 4, 5 or 6, characterized in that the grinding control is carried out in such a way that the pressure of the blade gap and also the size of the blade gap are controlled by automatically adjusting the height of the outflow dams (10). 10 1. Förfarande för att styra malningen i en skivraffinör, vid vilket malningen av ämnet som skall malas styrs genom attára trycket mellan skivraffinören bett, kännetecknat av att trycket mellan skivrafiEinörens bett regleras genen attàet utsidan Flytt-bar fördämning (10) monterad mellan raffinörens bett för att styra trycket mellan 15 Betten. 8. Anordning the patent patent craven 3, 4, 5 eller 6, turning the att 10 malningen regleras sa att trycket mellan Betten och samtidigt även stetted styrs genome att automatically adjusting the temperature (10) under styming temperature. t I • • • · · ♦ · · · · · · «« «♦ ♦ ♦ ♦ I * * ♦ ♦ ♦ ♦ I I