FR2503205A1 - SYSTEM AND METHODS FOR SUPPLYING MULTIPLE PULSE EXTRUSION DIES FOR PAPER MACHINES - Google Patents

Abstract

MULTI-LINE FEEDING METHOD AND SYSTEM FOR EXTRUDING THE PULP IN A PAPER MACHINE FOR FORMING THE CONTINUOUS BAND OF PULP. A DIE CHAMBER 20, COVERING THE ENTIRE WIDTH OF THE MACHINE, WITH A PULP CURRENT IN SUSPENSION AND A FLUID CURRENT FREE OF PULP, THIS CHAMBER WITH OR NOT INCLUDING A RIGID INTERMEDIATE BULKHEAD 24, THE TWO CURRENTS SUPERIMPOSED TO THE EXIT FROM CHAMBER 21 TO FORM A CONTINUOUS BAND OF DOUGH; IF THERE ARE TWO CURRENTS OF DOUGH, A THIRD CURRENT FREE OF PASTE, THIS CHAMBER WITH OR NOT INCLUDING A RIGID INTERMEDIATE BULKHEAD 24, THE TWO CURRENTS SUPERIMPOSING THE OUTPUT OF CHAMBER 21 TO FORM A CONTINUOUS BAND OF PASTE; IF THERE ARE TWO CURRENTS OF DOUGH, A THIRD CURRENT FREE OF DOUGH BUT ESSENTIALLY CONTAINING FILTER WATER IS DIRECTED TO THE INTERVAL BETWEEN THE FIRST TWO CURRENTS TO FORM A MULTI-LAYER BAND; THERE ARE AS MANY LAYERS OF FIBROUS MATERIAL AS THERE ARE ROWS OF DIFFUSERS 28 AT THE ENTRY TO THE CHAMBER, ONE ROW 30 DELIVERING THE FILTERING WATER TO FORM THE FIBER FREE LAYER.

Description

The invention is based on a multiple feed system

  extrusion of the dough into a paper machine, particularly

  type described in US Patent No. 3,923,593.

  This known multi-die extrusion die system for paper machine is used for the manufacture of a continuous web of fibrous material having several layers or thicknesses (for example two or three). Such a system comprises for this purpose, in one case, an intermediate partition, and in the other case, two intermediate partitions, the role of which is to separate between them the expected flow channels

  for the different suspensions of fibrous matter (in short, pasta).

  In both cases it is expected that the intermediate partition (s) will be

  tend directly to the exit slot of the die. Such

  partitions, in a first zone which originates at the end of

  are made in the form of rigid walls. These are then extended by flexible intermediate partitions constituted by sheets, whose ends, as indicated above, are located directly in the exit slot of the die. This provision is

  to prevent the different streams of dough from mixing with one another

  that the formation of the sheet to be made begins. It is therefore desirable, as a general rule, that the different layers (for example the upper layer and the lower layer) are clearly distinguishable

  from each other in the finished dough strip. There may be differences

  eg fiber quality and / or colors.

  A disadvantage characterizing the known arrangement lies in this

  during the fact that along the flexible intermediate partition

  stalled by a leaf, areas of instability may form in

  the dough streams, which determines the formation of vortices. Those-

  These are the reasons why, immediately after the exit of

  However, there is a certain amount of mixing of the various doughs by dies or feed nozzles. It follows that the different layers forming the final strip are no longer distinguishable

  each other to the desired extent.

  Another disadvantage of known feed systems from a paper machine lies in the fact that by adopting an intermediate partition formed by a flexible sheet the risk of a break can never be totally eliminated. Such a flexible intermediate partition therefore constitutes a certain escape from risks with regard to operational failures. In this connection, we must also take into account

  because in a multi-sector supply it can occur

  suddenly - most often unintentionally - a strong fall

  pressure between two adjacent flow channels, for example by

  a failure of a feed pump. This presents a risk of rupture or wrinkling for the sheet-shaped intermediate partition. The invention is based on the problem of producing a multiple die feed for the extrusion of dough sheets in a paper machine, which is of simplified construction, reliable operation and more particularly avoids disadvantage that

  have flexible intermediate partitions in the form of leaves.

  This problem is solved by a particular combination of means

  which will be described later. In this description, the term

  fibrous fra che "means that it is a suspension of fibers obtained

  when preparing the dough from a chemical dough,

  and / or waste paper, and possibly filler or filling material. According to the foregoing, the expression "from liquid free of fresh fibrous material" is understood to mean that this liquid contains in all cases fibrous materials and / or fillers such as those contained in the wastewater and / or filtering of the paper machine, and therefore it is not possible to obtain, from

  of this liquid, a layer (or a jet) in the paper that is to be

  quer. It is first of all necessary to explain the invention by taking as an example a feed with a double extrusion die of the dough; in this case, only one of the two feed systems that distribute the liquids over the width of the machine will be loaded into paste. On the other hand, the other

  feeding system will receive a liquid free of fibrous material

  preferably in filtering water which, as a general rule, is

  holds as overflow or overflow.

  Thus, the two liquid streams will be arranged so that, with respect to the screen (on which they will be directed in order to form a strip of dough), it is first the stream of dough and then the water

filtering that hit the sieve.

  By this means, it is first formed, according to the conventional mode, a continuous strip of fibrous material, through which then passes the filter water. Thus, the matter in fine particles or filling that

  is in the filter water is retained in the band of

  fibrous. As a result, a continuous band formed of a single -3-

  layer of peat with a high content of fine particles and filling material

  wise. It is essential to note that, under these conditions,

  can give up, in a supply of multiple dies for the extrusion

  pulp sheets, to a strict separation of the two streams of

  liquid to the exit slot of the dies. For this purpose, it is

  it is possible that each of the supply systems comprises a plenum section capable of forming a fluid stream that is essentially tranquilized, that is to say free of vortices (at least the larger ones),

  and covering the entire width of the machine. These areas of tranquillization

  preferably be made in such a way that the Chamber of Finance

  has a rigid and shortened intermediate partition (contraindicating

  the known mode of construction), which extends between the end

  admission and approximately (for example) the middle of this chamber of

  -border. However, it is also possible to realize the total

  without intermediate partition and insert the stilling section

  upstream of this chamber of dies. If, for example, the system of

  The supply consists of a tubular distributor or collector

  given a row of small distribution pipes distributed over the entire width of the machine, it is possible to arrange, between the end of each small distribution pipe and the inlet of the die chamber, a channel of tranquilization, preferably in the form of a diffuser to

polygonal section.

  In each case, the two fluid streams flow directly

  and between the straightening sections and the exit slot, that is to say without there being a partition wall between these two currents. Admittedly, there is a partial mixture before the fluid streams hit the sieve. However, this mixture is surprisingly low, especially if one is careful to maintain the same

  flow velocities in these two fluid streams.

  Another advantage stems from the fact that in the event of

  from one of the two feed pumps there is a quick and trouble-free equalization of the pressure between the zones of the two currents

  of fluid. In the event that the presence of an inter-

  rigid and shortened median, it will be useless to design it so that it can withstand high differential pressures. The system

  pulp supply can therefore be achieved at a relative cost price.

reduced.

  The invention will be used in the first place where, up to

  In fact, problems arise in the manufacture of paper because of the sometimes particularly high content of the filtering water in fine particles and fillers. It is known to send back

  much of this filter water - after adding

  very fresh - in the diet of a friend. But in this case the content

  in fine particles and fillers can become so high

  (especially when certain qualities of waste paper are used as raw material), it becomes impossible to obtain the desired quality of paper made. It is then necessary to extract a greater fraction of filtering water (compared to what is otherwise necessary) of the circuit, this

  which increases the load imposed on the filtering plant of the manufacturer

  than paper. All these problems are now solved thanks to the presence

the invention.

  An even more important concept of the invention lies elsewhere.

  in that the knowledge thus acquired can also be used in the manufacture of continuous strips of fibrous multi-layer material (for example for multi-layer toilet paper or even

  for cardboard). In this case, the feed according to the invention will be made

  with three feed systems in order to obtain a two-layer product. For this purpose, the two layers could be constituted by the same material or by two different materials. Feeding in pfte would always have two streams of matter separated from each other

  intermediate liquid stream, which would be free of

  breuse fra che che. In this case too, we can preferably use

  filtering water. This is the case (as in the first example

  crit) a partial mixture of the filtering water stream with the two

  pastes of dough. However, this mixture is so minimal that, in each case, it is certain to separate the two streams between them, and this not only up to the exit slot of the dies, but also until the veins of paste together meet the filter or

  sieve. It is thus also possible to obtain that the two streams of separated pulp

  by the filter water meet the surface of the filter or sieve while they are at a determined distance from each other, so that the first layer is already preformed when the dough stream intended to form the second layer occurs. By this means, the invention

  is particularly advantageous if it is applied in a pa-

  pier designed for the manufacture of continuous strips of multilayer paste

  according to German Patent Application No. 31 12 966.8-27.

  Even in facilities for the manufacture of products - 5 -

  multilayer, the feeding system according to the invention is of

  truction simpler than that of the corresponding feeding systems

  known. Similarly, if, however, provision is made for

  in the chamber of the sectors, these partitions will also be connected

  curved and preferably rigid, and as indicated above it is useless to provide them with dimensions calculated for strong

differential pressures.

  We will now describe some examples of the realization of the in-

  invention with reference to the accompanying drawing, in which:

  FIGURE 1 is a schematic diagram of a power plant

  double die extrusion system, with the relevant circuits

  rents for the circulation of filtering water;

  FIGURE 2 is a diagram showing a power plant

  triple extrusion dough die assembly, with adjacent members of a double sieve type paper machine and circuits for filter water;

  FIGURE 3 is a diagram showing a power plant

  FIG. 4 is a front view taken in the direction of the

arrows IV of Figure 3.

  If we first refer to Figure 1, we see on this

  a double extrusion die feed system for pulp, designated as a whole by reference numeral 10, which forms part of

  an integral part of a paper machine, as well as part of the longitudinal filter.

  dinal usually scheduled. From this filter, the drawing shows only the band

  endless sieving or filtering apparatus 11, a transverse cylinder 12,

  fixed support devices 13 and a bowl 14 for collecting

filtering water.

  The dough supply system 10 has two outer walls.

  15 and 16 which extend, in the usual manner, over the entire width of the paper machine. These walls 15, 16 define a chamber

  with a die 20 and converge towards each other in the direction of a cy-

  transverse liner 12 above which they form a die exit slot 21. Therefore, the die chamber 20 is divided only

  in the area of the intermediate partition 24 into a lower channel Oe cir-

  25 and an upper circulation channel 26. A tubular collector

  re admission 27 disposed transversely to the machine to

  paper is connected according to the classic mode via

  numerous small distribution pipes 28 at the lower circulation channel.

  In a similar manner, a tubular intake manifold 29 is connected by a number of small distribution manifolds.

  at the upper circulation channel 26, which are arranged at

  equal intervals across the width of the paper machine.

  The suction lines 32 and 33 of two feed pumps 34 and 35 are connected to a tank 31 containing the filter water. In the suction line 32 further opens a supply line

  36 in fresh paste. Therefore, the feed pump 34 represses itself

  In the known mode a fresh suspension of fibers in a pipe 37

  which opens into the lower flow channel 25 of the feed system.

  10. On the other hand, the other feed pump 35 delivers water

  filtering without the addition of fresh paste through the

  pick 38 in the upper flow channel 26.

  The purpose of the intermediate partition 24 is to guarantee, in each of the two flow channels 25 and 26, equalization of the speeds in the transverse direction along the path that the currents carry out from

  the entrance of the small pipes 28 and 30. In other words, in the ter-

  minal of the intermediate partition 24 the two fluids are tranquilized

  and free of swirls. Under these conditions, we can direct them

  directly, one over the other, beyond the end (preferably tapered) of the intermediate partition 24, to the outlet slot 21 and beyond to and on the endless conveyor belt 11 forming a filter. Therefore,

  these currents mix very weakly and only in the

  do not of their separation surfaces. On the endless band of filtering, sen-

  similarly to conventional paper machines, it forms

  from the fibrous suspension a continuous strip of paper,

  that the filter water is discharged through the filter down into the bowl 14. In the initial part of the formation zone of the continuous web of paper, the newly formed paper sheet is covered by the water of This filtration water then passes through the paper web and also the screen 11 to flow downwards. In this case, the paper sheet acts as a filter layer and therefore retains a fraction of

  solid particles contained in the filter water.

  The filtering water retained in the bowl 14 returns via a pipe 39 into the tank 31 where the filter water is collected. This

  tank 31 is flanked by a complementary reservoir 40 in which

  sinks the overflow of the tank 31. The content of this reservoir complements

  40 can feed, through a pump 41, a thickener, a filter -7-

  or other similar device, in order to allow the recovery of

  solid particles found in the overflow filter water. These

  particles may possibly be added, via

  42, with filtering water sucked by the feed pump 35.

  Figure 2 shows a triple dough extrusion die system 100 for the manufacture of a double dough continuous band.

  layer. In the exemplary embodiment shown, the triple supply chain

  The process operates in conjunction with a dual filter paper machine. CEL

  it actually has a first filter band 101 that passes

  around a transverse cylinder 102 and then, together with a second

  filter strip 103, around a production cylinder 104. There is also provided a bowl 105 in two parts to collect the water

  filtering element, which comprises an intermediate partition 106.

  of this bowl 105 has its own drainage pipe or

  107 or 108. These respectively open into separate tanks 109, 110 each provided with a feed pump 111 or 112, supply lines 113 or 114 for fresh dough and a pipe

  114 or 116 feeding system triple extrusion die 100.

  The other parts of the paper machine conform to the art

  previous current and therefore they have been omitted from the drawing.

  The supply system 100 also comprises two convergent outer walls 95 and 96 which delimit a spinneret chamber 120, and also form an exit slot 121 of the spinneret, provided with an adjustable curtain 122, as well as a perforated plate 123 at the entrance end of the chamber. There are further provided two intermediate partitions 124 which correspond in all their details to the intermediate wall 24 of Figure 1. This assembly forms in the entrance area of the chamber

  with triple die 120 three superimposed flow channels 125, 126 and 127.

  Each of these flow channels is associated with a tubular distributor,

  as shown in reference numbers 128, 129 and 130.

  In the two external tubular distributors 128 and 130 de-

  closes the pressure lines 116 or 115 already cited, which serve

  to convey the suspension of soft dough. The tubular distributor

  On the other hand, 129 will be supplied with filter water without the addition of fresh water. For this purpose, the two filter water tanks 109 and are connected to an additional feed pump 117 that can be communicated at will with one and / or the other of these tanks by acting on This pump 117 pumps the filter water into a pipe 119 which leads to the tubular distributor 129. In case of need,

  this filter water can be supplemented with solid particles of

  ration (analogous to what was indicated at 42 in Figure 1).

  In the feed system 100 the fluid streams are of

  edge guided by channels 125, 126 and 127 where they are tranquilized. In-

  subsequently, these fluid streams are directed forward, but in the absence of any partitions between them, so that, henceforth, the dough streams initially guided through the current channels 125, 127 are

  separated from each other by the flow of filtering water which is

  to be them. In the area of die exit 12 first opens the

  dough stream exiting the channel 125 and settling on the filter web.

  trante 101, where a strip of dough is formed very quickly. At the same time

  the upper dough stream (i.e. the one exiting the channel 127) par-

  comes into the wedge-shaped entrance slot which is formed on the forming cylinder 104 by means of a part of the upper filtering band 103 and on the other hand of the lower filtering band 101, on which

  has already formed the fiber layer. we thus obtain, from.-

  upper stream of paste, a second layer of fibrous paste. The cylinder

  of training 104 preferably comprises a massive and im-

  permeable to water. In this case, the dewatering of the second layer is carried out exclusively through the first filtering band 101, thus through the first fibrous layer previously formed, which acts in this case.

  case as a filter layer. In other words, this layer is in con-

  to retain a large part of the fine solid particles and the

  filling material or charge driven on the one hand by the current su.

  paste (through the channel 127), and on the other hand by the current

  medium or intermediate filter water (through channel 126).

  In general, it will be ensured that the average height of the intermediate channel 126 is smaller than the average height of the outer channels 125 and 127. Thus, the thickness of the filtering water stream which drives the streams of dough will be chosen so that it is as small as possible. On the path leading to the exit slot 121 and on the two separation surfaces a portion of the filter water is gradually mixed on the one hand with a stream of dough and on the other hand with the other stream of dough. The filtering water flow will therefore become thinner and thinner. However, it must remain active as

  separation layer to the area where the first layer of paste is

  breuse is formed on the lower filter 101.

  As shown in FIG. 2, it may be advantageous to cause the upper outer wall 95 to protrude in length and, to some extent, the lower outer wall 96 to the

of the exit slot 121.

  Figures 3 and 4 of the drawing show an alternative embodiment

  triple feed system. In this set 60, the

  The condition of the die chamber 80 (including the exit slot 61) is free of intermediate partitions. Instead of these it is planned,

  to obtain the tranquilization of the fluid currents, that each small

  the distribution pipe 81, 82 and 83 opens into a dry diffuser.

  polygonal arrangement (71, 72, 73) (connecting piece whose section varies from the round shape to the polygonal shape). In this connection, a typical example is shown in which the output section

  diffusers is polygonal in shape. However, can consider from

  very many embodiments (see German Patent No. 2,007,308). he

  broadcasters (71, 72, 73), who belong to one of the

  readers 84, 85, 86, are directly joined together along a row that extends over the entire width of the machine; in other words, that

  the thickness of the intermediate wall 70 is reduced to zero.

  Thanks to this provision, broadcasters constitute in their

  set of tranquilization channels which, therefore, can

  butcher directly into the die chamber 80 free of bulkheads

  intermediates. In Figure 3, the small distribution pipes 81, 82 and 83 and the diffusers 71, 72, 73 are arranged in parallel.

  between them. Instead of this provision, it could also be

  the tubings with respect to each other, as shown in Figure 2. Similarly, the arrangement of the outer walls 75 and 76 can

  vary from that shown in Figure 3; for example, we

  similar to that shown in Figure 2, adopt a

  substantially symmetrical position to that of the small distribution pipes.

Posted.

- 10 -

Claims (12)

-R E V E N D I C A T I 0 N S-   A multi-die feeding system (10; 60:) of a paper machine of the kind comprising: a) a die chamber (20; 80; 120) defined by two outer walls (15,16; 76, 95,   96) which converge towards one another and   tooth between an inlet end and an exit slot of the dies (21; 121); b) at least two separate devices (27, 29; 84,   85, 86; 128, 129, 130) for delivering to the room   dies (20; 80; 120) of different fluids.   these devices being so arranged   so that at least two streams of fluids   the entire width of the machine are   through the die chamber, characterized in that: c) at least the zone of the die chamber (20;; 120) which is upstream of the slot of   output (21; 61; 121) in the direction of flow.   is free from intermediate bulkheads   fluid streams, and d) one of these fluid streams, to which fresh paste is added, is guided in the direct vicinity of a fresh dough-free fluid stream.   through the die chamber (20; 80; 120).   2. Feeding system by dies according to the cation 1, of the kind comprising:   a) at least one intermediate partition (24; 124)   in the die chamber (20; 120) which   tends parallel to the flow direction of the fluids and over the entire width of the chamber to   sectors, so as to form at least two   flow streams (25,26; 125,126; 128,129) directed towards the outlet slot (21; 121), and b) at least two adjacent flow channels (25;   26; 125, 126, 127) comprising distributed systems   tins (27, 29; 128, 129, 130) for discharging the fluid, characterized in that the at least one intermediate partition (24) - he -   or 124) which originate at the inlet end of the die chamber (20, 120) extends or extends over a   part of the total length of this room.   3. Feeding system by dies according to the   2, characterized in that the intermediate partition or partitions (24; 124) extend only to the central zone   the die chamber (20; 120).   4. Feeding system by dies according to one or   the other of Claims 2 and 3, characterized in that the   or the intermediate partitions (24; 124) are only   in the form of rigid partitions.   5. Feeding system by dies according to the   1, characterized in that the whole of the flow chamber   (80) is free of intermediate partitions.   6. Feeding system by dies according to the   5, characterized in that each of the feedback systems   81, 81, 82, 85, 83, 86) comprises a row of plenum channels (71; 72; 73) arranged side by side on   the whole width of the machine, so that the   its intermediate (70) formed between each pair of adjacent channels of tranquilization progressively thins out in the direction of flow.   7. Feeding system by dies according to the   6, characterized in that the stilling channels   (71; 72; 73) consist of diffusers with lygonale.   8. Feeding system by dies according to some   according to Claims 1 to 7, characterized in that   Fluid free of fresh dough consists of filter water.   9. Feeding system by dies according to any one   than Claims 1 to 8, characterized in that one   adds to the fluid free from the aforementioned fresh pulp solid ways of recovery, including solids under   form of fine particles and / or filler.   10. Feeding system by dies according to any one   Claim 1 to 4, 8 or 9, comprising two   intermediate partitions (124) and three flow channels (125,126,127), characterized in that the fluid-free fluid is delivered to the intermediate flow channel (126). - 12 - fresh pasta.   A process for preparing a continuous dough web in which a suspension fiber stream is directed by a dies feed system (10 ;, 60; 100) to the web forming device. the continuous web of a paper machine, the suspension fiber stream being first directed through a quenching sector (25: 71, 73; 125, 127) to a die exit slot (21; 61, 121), this method being characterized in that   that one also directs towards the exit slot of   (21; 61; 121), in an area adjacent to the suspension fiber stream, a fluid stream free of fibrous material, such that at least in an area upstream of the exit slot of the dies, the direction of flow, the two aforementioned currents are constrained   to flow in a single channel free of inter- médiiaires.   12. Process for preparing a multi-layer dough strip   in which a plurality of suspension fiber streams of different kinds of fibers are directed by a die feed system (60; 100) to the continuous web forming device paper machine, such that in the first place the different streams of suspended fibers are directed separately through a plenum (71, 73 ;, 127) and then to a die exit slot (61; 121), said method being further characterized by directing a coolant-free fluid stream in a region (72; 126) between the suspended fiber streams to the exit slot of the dies (121), so that   less in an area upstream of this slot   suspended fibers and the flow of fluid between them is directed through a single channel free of intermediate partitions.