FI95402B - Installation in connection with the turbulence generator in the head box of a paper machine for controlling the pulp flow - Google Patents

Description

95402

Equipment in connection with a paper machine headbox turbulence generator for controlling the mass flow

Anläggning i samband med turbulensgeneratom i inloppslädan av en pappersmaskin för regiering av massaströmmen 5

The invention relates to an apparatus in connection with a turbulence generator 10 of a paper machine headbox for controlling the mass flow.

Paper machine turbulence generators are known in the art, in which the turbulence of the mass flow has been promoted by passing the flow through a stepped tubular structure. The higher the pressure drop and turbulence in the piping, the cleaner the pipes will remain and the more even the flow distribution will be achieved. Therefore, it is advantageous to increase the pressure drop in the flow.

According to the invention, an apparatus is provided in connection with a turbulence generator in the headbox of a paper machine, in which a mass flow control device 20 is arranged in front of the tube coil, consisting of several adjacent plates placed against each other, comprising channels for the mass flow. In adjacent plates, the flow channels in the same positions are aligned and form a single channel assembly. In the solution according to the invention, the pressure drop can be easily adjusted by changing the number of perforated plates to be placed side by side and / or the shape of the holes in the perforated plates 25. With the structure according to the invention, the controlled flow turbulence and flow rate are made sufficiently low, whereby the risk of cavitation is also avoided.

The apparatus according to the invention in connection with a turbulence generator of a paper machine is mainly characterized in that in adjacent perforated plates the shape of the hole is conically tapered with respect to the flow-30 direction, whereby when the perforated plates are placed side by side a channel is formed for the flow.

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The invention will now be described with reference to some preferred embodiments of the invention shown in the figures of the accompanying drawings, to which, however, the invention is not intended to be exclusively limited.

Figure 1 is a schematic representation of the scope of the invention in a paper machine headbox.

Figure 2 shows a longitudinal section of the headbox of a paper machine.

Figure 3 shows the perforated plates 10aj and 10a2 of Figure 2 spaced apart and in partial sectional view.

Figure 4A shows a first embodiment of a perforated plate assembly.

Figure 4B shows another embodiment of a perforated plate assembly.

Figure 4C shows a third preferred embodiment of the perforated plate assembly.

Figure 1 schematically shows a target area of the invention for a paper machine headbox 20 and its turbulence generator. As shown in Fig. 1, the mass flow enters the tubular coil J of the turbulence generator and flows through it into the lip cone K. In order to obtain a sufficient pressure drop in headboxes comprising one tubular coil J, an assembly formed of perforated plates 10a |, 10a7,10a3 ...

25

By using the perforated plate assembly according to the invention, the mass flow rate can also be set low enough to avoid cavitation. Correspondingly, a high turbulence is achieved and thus a good disintegration of the fiber flocs of the pulp. With turbulent flow, the manifold of the turbulent generator also remains clean.

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Figure 2 shows a longitudinal section of the headbox of a paper machine. Each perforated plate 10a ^ 10a ^ 10a ... comprises a plurality of adjacent holes 11a1, 11a2 ...; llbj, l lb2 .- .; l lcj, l lc2____When the plates 10aj, 10a2 ... are placed opposite each other, the holes in the same position in the adjacent plates are cooperative and aligned. Thus, in each of the perforated plates 10a1, 10a2 ... the holes together with the holes in the same position of the adjacent perforated plates form a flow channel assembly D1, D2 ... in which the flow channel is caused to expand and contract gradually in its flow cross-sectional area.

As shown in Fig. 2, the first perforated plate 10aj comprises straight holes 11aj, 11a2, in which the flow channel D has a constant cross section. Subsequent perforated plates 10a2,10a3 (with respect to the flow direction) comprise conical holes 11b, 11bb, 11c1, 11c2 which taper conically with respect to the flow direction.

15 When the flow arrives from one perforated plate to another, the flow arrives at the junction of the perforated plates into the expansion, after which the flow channel D narrows again to expand again when the flow arrives at the third perforated plate 10a3. Thus, in the solution according to the invention, considerable turbulence and pressure drop are achieved before the distribution pipeline J of the turbulence generator. The solution facilitates the piping J of the turbulence generator.

20 staying clean. In addition, causing a pressure drop in the flow and keeping the flow rate low enough also prevents cavitation. The turbulence of the flow is also directly proportional to the desired uniform flow distribution and the desired uniform pulp quality in the lip cone of the headbox of the paper machine and further on the forming wire.

25

In the solution according to the invention, perforated plates are thus placed in the equalization chamber E of the headbox of the paper machine in connection with the distribution piping J of the turbulence generator in front of it with respect to the mass flow direction. The desired flow pressure drop and turbulence is obtained by selecting an appropriate number of perforated plates 10aj, 10a2,10a3 ... with appropriately shrinkable flow channel shapes.

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Fig. 3 shows the perforated plates 10aj and 10a2 of Fig. 2 in an axonometric view and in a partial cross-sectional view spaced apart from each other. The structure according to the invention is advantageous to manufacture. In addition, it offers good control to achieve optimum flow.

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Fig. 4A shows a first way of forming the flow channel D by placing two conical perforated plates 11a2,10a3 ... opposite each other. In this case, the conical holes of the perforated plates are 1 lbj and lie! align and together form an expanding and subsequently contracting flow channel D.

10

Figure 4B shows another preferred way of forming the flow channel D. Adjacent perforated plates 10a4,10a5 each comprise a hole shape 11d3,1 lex comprising a conically shrinkable cross-section in the flow direction and to which the conical shrinkable flow channel portion D 'is bounded by a direct flow channel portion D ".

15

Fig. 4C shows a third preferred way of forming the flow channel D, in which the adjacent perforated plates 10a6, 10a7 comprise a hole shape 11fj.llgj having a first straight channel portion D "\ preferably a channel section D "\

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Claims (3)

An installation in connection with the turbulence generator of the inlet carriage in a paper machine for controlling the pulp flow, wherein the inlet carriage of the paper machine comprises a set of heel plates (108 ^ 1082 ...) which are placed in front of the pipes (J) in the direction of flow. the turbulence generator, in which the whole of the heels (10a1,10a2 .. ·) are placed against each other, whereby the heels (1 lalf 1 lbj, 1 lcx ...; 1 la2,1 lb2, llcj ...) in the same position in the heels cooperate and forming a flow channel whole (D), characterized in that the heel shape (1 lbj, 1 lcj) in adjacent 10 health slices (10a2,10a3) tapered off conically in relation to the flow direction, forming a channel for the flow which narrows expands incrementally as the heel plates (10a2, 10a3) are placed next to each other. An installation according to claim 1, characterized in that there is also a third heel disc (10a4,10a5) comprising a heel shape (ldj.llej), in which there is a conical (D ') channel portion and a straight channel portion (D ") with constant flow cross-section adjacent to it. Installation according to claim 1, characterized in that there is also a third heel plate (1085, 1037) comprising a heel shape with a channel section (D "') with a constant cross-sectional surface, to which is connected a channel section (DB') which narrows of '* conformal and to this is connected a channel portion (D "') of straight constant cross section. 25 - · <· il 1 itM: mm 1 a ia. - -