EP0569273B1 - Paper humidifier - Google Patents

Abstract

The present invention relates to a paper rehumidifier, of the type comprising means (54, 55, 56) for driving a paper web (P) over a predetermined path on the inside of an enclosure (8), into which open nozzles (36, 37) for spraying a humidifying mist. According to the invention, the enclosure (8) is leak-proof and communicates, at a point remote from the spray nozzles (36, 37), with the inlet of a suction device (41), the outlet (43) of which opens onto the outside of the enclosure. This suction device preferably consists of a fan (41) communicating with the enclosure (8) by way of a blister remover (48). The invention is used particularly in lines for the printing of newspapers or other publications, for the rehumidification of the printed paper at the exit of the drier. <IMAGE>

Description

The present invention relates to a paper rehumidifier, of the type comprising means for driving a strip of paper, on a predetermined path, inside a sealed enclosure into which open spray nozzles of a humidifying mist and which communicates , at a point distant from the spray nozzles, with the inlet of a suction device, the outlet of which opens outside the enclosure.

Rehumidifiers of this kind are found in printing chains for newspapers, books or other printed publications on paper. Placed downstream of a dryer from which a continuous width of printed paper extracted with a slight undulation due to the non-uniformity of drying, such a rehumidifier has the function of restoring the width of its width to its initial smooth appearance, by impregnating it , over its entire surface, of finely sprayed water in the form of a mist in pressurized air.

A humidifier of this type is known, described in application AU-B-417,609 (FMC CORPORATION), but which does not make it possible to extract the excess drops of water in the enclosure with the desired efficiency.

It turns out that the use of rehumidifiers of this type suffers from a major drawback due to the fact that the accumulation of fog inside the enclosure and its contact with the walls thereof, leads to the formation of drops of water which, falling on the width of printed paper while scrolling, can stain it to the point of rendering the printed publications produced unfit for sale.

The present invention proposes to remedy this drawback and, to do this, it relates to a rehumidifier of the type specified in the introduction, which is characterized in that the inlet of the suction device communicates with the enclosure through '' a demister, which will intercept the droplets of water suspended in the fog before expulsion of the latter out of the rehumidifier. Such an apparatus therefore makes it possible to homogenize the humidifying mist around the paper; moreover, the air outlet the suction device being rid of its excess water can be advantageously recycled to humidify the paper stocks awaiting printing, without discomfort for the staff since it avoids an increase in the humidity of the closed environment of the rehumidifier , which could be extremely inconvenient for service personnel.

By being suitably placed with respect to the nozzles and to the path of the paper, the suction device associated with the demister will circulate the spray mist inside the enclosure and will quickly extract it from it, after completion of its paper rewetting task. This results in a sharp reduction in the residence time of the mist in the enclosure and a minimization of its contacts with the walls of the latter, for a notable reduction, or even a total disappearance, of the formation of the drops of water which are at the origin of the faults found in current rehumidifiers.

Advantageously, the suction device is a fan.

In a preferred embodiment, simple in design, the demister consists of a conduit lined internally, and over its entire section, with a three-dimensional lattice of entangled metal fibers, this conduit being, on one side, connected to the entry of the suction device and opening, on the other side, on the lower part of the enclosure, away from the path of the paper strip and above a tray, which collects water dripping from the demister.

Alternatively, the duct also opens laterally, in an area between the inlet of the suction device and the lower part of the enclosure.

According to another characteristic of the invention, the enclosure is delimited in the lower part by a floor provided with two narrow slots which are substantially parallel for the inlet and the outlet of the paper strip respectively, and the spray nozzles are arranged in two. rows extending on either side of the same slot, the inlet of the suction device communicating with the lower part of the enclosure on the side of the second slot, opposite to the first slot.

Preferably, the two rows of nozzles extend on either side of the inlet slot of the paper strip, and the opening through which said inlet of the suction device communicates with the enclosure extends in the same direction and over at least the same length as the rows of nozzles.

All of these provisions ensure uniform rewetting of the width of paper over its entire width as well as over the entire length of its travel path inside the sealed enclosure.

Advantageously, the enclosure has a vault-shaped ceiling connecting without dead space to the adjoining walls of the enclosure.

The risks of water droplets depositing on the interior walls and the ceiling of the enclosure, licked by the moving fog, are thus minimized.

The drops of water which would nevertheless form on contact with the walls and the ceiling of the enclosure, could moreover run down along these sparing the width of paper and could be collected in the lower part of the enclosure by a bowl preferably constituting the floor of the latter.

According to a complementary characteristic of the invention, each of the entry and exit slots of the paper web in and out of the enclosure is bordered, on its two sides, by two respective ramps insufflation of dry air, which by forming air knives coming to lick the web in movement through each of the slots, guarantee in all circumstances a perfect seal along the latter.

• la figure 1 est une vue de côté, avec arrachement partiel, de ce réhumidificateur ;
• la figure 2 est une vue en coupe de ce même réhumidificateur, faite selon la ligne II-II de la figure 1 ;
• la figure 3 est une vue en coupe faite selon la ligne III-III de la figure 1 ; et
• la figure 4 est une représentation agrandie d'un détail de la figure 2.

A rehumidifier according to a preferred embodiment of the present invention will now be described in more detail, but only by way of nonlimiting example, with reference to the appended drawings in which:

• Figure 1 is a side view, partially broken away, of this rehumidifier;
• Figure 2 is a sectional view of the same rehumidifier, taken along line II-II of Figure 1;
• Figure 3 is a sectional view taken along the line III-III of Figure 1; and
• FIG. 4 is an enlarged representation of a detail of FIG. 2.

The rehumidifier illustrated in Figures 1 to 3, externally has the shape of a cabinet 1 constructed from metal beams, such as 2a, 2b, 2c, assembled to each other in the form of a higher parallelepiped frame and deep than wide. Metal sheets, joined to the beams 2a to 2c, define the rear wall 3, the side walls 4,5 and the ceiling 6 of the cabinet 1, which, with a floor 7, produced in the form of a rectangular bowl, delimit an enclosure 8 closed at the front by a pivoting door 9 with vertical hinges 10.

The cabinet 1, thus formed, is integral with a hollow base 11, by which it rests on the ground S and the door 9 extends downward to close this base 11 at the front, each of the side walls 11a of which, 11b is further pierced with a respective window 12 or 13, the usefulness of which will be seen later.

According to the invention, the enclosure 8 is waterproof. To do this, the joining of the sheets 3, 4, 5, 5 and 6 to the beams 2, as well as the assembly of the latter between them, is done using continuous weld beads, possibly doubled by gaskets. . For the same purpose, the door 9 is internally lined with a rubber sealing flange 15 which, after closing the door, is compressed between the latter and the periphery of the front opening of the cabinet 1; finally, the vertical walls, such as 16, of the bowl 7 constituting the floor of the enclosure 8, are fixed by their upper end, and for example by means of bolts, in a continuous seal 17 retained in profiles in U 18 themselves welded to the beams 2a which delimit the base of the enclosure 8, as can best be seen in the detailed view of FIG. 4.

This figure also shows, in conjunction with Figure 1, that the bowl 7 is supported, by its bottom 19, on large screws 20 carried, in two rows, by brackets 21 welded to the inside of the side walls 11a, 11b of the base 11 of the cabinet 1, these support screws reinforcing the mounting of the bowl.

We can also observe in these same figures that two passages 22 communicating the interior space of the base 11 with the enclosure 8 are formed in the bottom of the bowl 7. Each of these passages 22 is delimited, from an opening 23 in the bottom 19 of the bowl, by two sections of vertical walls 24.25, made integrally with the latter and substantially parallel to the side walls 4.5 of the cabinet, each of them having at its upper end a lip 26.27 folded down and outwards from the passage 22. The two lips 26, 27 of the wall sections 24, 25 respectively support two rectangular flaps 28, 29 articulated around axes 30, 31 substantially parallel to said wall sections. Spiral springs, not shown, urge the two flaps 28, 29 against respective lugs such as 32 and 33, which point inside the bowl 7, from two vertical walls facing the latter closing the two passages 22 at their ends. It should also be noted that the wall sections 24.25 delimiting the two passages 22, as well as the flaps 28.29 which they carry, are applied against the above-mentioned vertical walls of the bowl 7 by means of fittings. not shown. Returning to FIGS. 1 and 4, it will also be noted that, on each of these walls, the pins 32, 33 are positioned so as to maintain the two flaps 28, 29 converging upwards. Thus, in each pair, the flaps 28, 29 define beyond their support pins 32, 33, a narrow slot 34 or 35 covering the entire length of the bowl 7 in the direction of the depth of the cabinet 1.

Referring simultaneously to FIGS. 1 to 3, it can also be seen that two parallel rows of five spray nozzles 36 and 37 are installed inside the bowl 7, on either side of the most located slot 34 on the left when the door 9 of the cabinet 1 is opened (figure 2). The nozzles 36 or 37, uniformly spaced in each row, are supported by means of fixing brackets, such as 38, respectively by a vertical side wall 16 and the bottom 19 of the bowl 7. They are also directed towards the inside of the enclosure 8, in a substantially vertical orientation. Ducts, such as that shown in FIG. 4 under the reference numeral 39, connect each of the nozzles 36, 37 to a not shown source of compressed air charged with water, which can be housed inside the base 11 of the cabinet 1, each of the conduits 39 passing through the bottom 19 of the bowl 7 by a sealing ring 40.

The rehumidifier, exemplified in FIGS. 1 to 3, is according to the invention equipped with a fan, here a centrifugal fan of the traditional type, represented under the reference 41, with its volute 42, its vertical discharge chimney 43 and its motor. 44. The discharge chimney 43 can be connected to a paper storage workshop, to ensure regular humidification. As can be seen in FIG. 3, the fan 41 is supported, in the upper part and outside the cabinet 1, by lugs 45, fixed to the vertical beam 2b constituting the right rear angle of the latter. The axial suction duct 46 of the fan 41 runs horizontally along the right side wall 4 of the cabinet 1 and is connected, by an elbow 46a and through a screened opening 47 made in the middle of this wall 4, to a demister 48 s extending along the latter, inside the enclosure 8.

As can be seen in FIGS. 2 and 3, the demister 48 is constituted by a three-dimensional lattice 49 of tightly entangled metallic fibers, retained over the entire width of the side wall 4 of the enclosure, inside and over the whole of the section of a conduit defined between this wall 4 and a partition 50 secured to the vertical beams 2b which support it. The fiber lattice 49, which extends from the top of the wall 4, rests on a mesh 49a stretched between the latter and the partition 50, above and at a distance from a tank 51 opening into 52 on the bowl 7 constituting the floor of the enclosure 8. At its base, the partition 50 delimits a wide opening 53 which makes the enclosure 8 communicate with the demister and, through the latter and the screen opening 47, with the conduit suction 46 of fan 41.

The partition 50 also delimits, along its walls vertical lateral 53 ', 53'', lateral openings located between the mesh 49a and the upper beams 2c, which make the enclosure 8 communicate with the duct 46 through a part of the demister 48.

The rehumidifier which has just been described is intended to be incorporated, at the outlet of a dryer, in a paper printing chain, such as a rotary chain for the production of newspapers or other printed publications. The continuous width of printed paper P, coming from the dryer and scrolling at uniform speed under the action of conventional drive means not shown, enters the rehumidifier and is extracted therefrom, respectively by the left side windows 12 and right 13 of its base 11. Inside the rehumidifier, the width P enters the enclosure 8 through the left slot 34 of its floor 7, bordered by the nozzles 36, 37, and leaves it through the right slot 35 following a path defined by three crazy rollers 54,55,56.

These idler rollers 54,55,56, with axes substantially parallel to the slots 34,35, have, like the latter, a length barely greater than the width of the standard paper webs used for printing on rotary presses. Two of them 54, 56 are mounted inside and on the base 11c of the base 11, the first between the left side wall 11a of the latter and the vertical plane of the first slot 34 of the bowl 7 and the second 56 between the vertical plane of the second slot 35 of the latter and the right side wall 11b of the base 11 of the cabinet 1. The third roller 55 is in turn supported, at 55a and 55b (Figure 1), by two horizontal upper beams 2c of the frame of the cabinet 1, in the upper part of the enclosure 8, under the ceiling 6 of the latter, which assumes the shape of a triangular section vault with rounded apex 6a oriented in the same sense that the roller 55. As can be seen in FIG. 2, the right flank 6b of the vaulted ceiling 6 of the enclosure 8 is connected without discontinuity to the partition 50 of the latter, and its left flank 6c extended by a deflector plate 57 of the same slope joining the left side wall 5 of the enclosure inte 8. It will also be specified that the roller 55 is positioned between the two vertical planes above 34.35 paper input and output slots of the paper width.

Before launching the actual printing process, the operator, after having opened the door 9 of the rehumidifier giving access to both the enclosure 8 and inside the base 11, will be able to easily set up the width of paper P, coming from the dryer, on its travel path inside the enclosure 8 (arrows A in FIG. 2), by passing it successively through the left lateral light 12 of the base 11, under the roller 54 , through the slot 34 entering the enclosure, above the roller 55, then through the outlet slot 35, under the roller 56 and through the right lumen of the base 11 from where the width P will be introduced in the next functional unit of the printing chain. For the manual execution of this preliminary operation, the paper web will be advanced at slow speed or in spurts by the drive means integrated in the printing chain. The operator will also have the possibility of temporarily removing the two pivoting flaps 28, 29 defining each of the slots 34 and 35, to more easily engage the width of paper P in the enclosure 8 and bring it out of the latter.

The continuous printing process can then be triggered from a central control console which is not shown and, as soon as the first printed section of the web of paper is extracted from the dryer, the operator puts the rehumidifier into operation. Each of the nozzles 36 and 37 then sprays into the enclosure 8, a diverging jet of fine water droplets suspended in pressurized air, as shown in broken lines in Figure 2. The gathering of these jets, emitted on either side of the entry slot 34 of the width, produces, on each side of the rising strand thereof, a humidifying mist effectively impregnating from its two faces the width of printed paper, which is thus rewetted.

At the same time, the fan 41 will create inside the enclosure 8 a depression sufficient to set the fog in motion, in particular in the channel defined, on one side, by the width P and on the other by the left side wall 5, the vaulted ceiling 6 and the partition 50 of the enclosure, the fog being then sucked in by the wide lower opening 53 and by the side openings 53 ′, 53 ″ of the demister 48 to be driven through the latter and ejected outside the rehumidifier by the discharge chimney 43 of the fan.

The movement, thus produced, of the fog inside the enclosure 8, advantageously standardizes the rehumidification of the width of paper P over its entire width, but above all its expulsion out of the enclosure, which is then ensured by the fan 41 , reduced to the minimum necessary for this rehumidification operation the residence time of the fog inside the enclosure. This added to the fact that the channel in which the fog moves is devoid of any dead space, in particular thanks to the presence of the deflector plate 57 and to the vaulted shape of the ceiling 6 of the enclosure 8, has appreciable consequences. to reduce to a large extent the deposit of water drops on all of the walls delimiting the enclosure. Any drops of water formed can also flow down both the inclined sides 6b, 6c of the ceiling 6 and along the vertical walls 5 and partition 50 of the enclosure 8, to be collected in the bowl 7 and without coming into contact with the width of the paper printed in scrolling, which comes out clean and smooth from the rehumidifier.

Furthermore, the demister 48, placed upstream of the fan 41, intercepts the water droplets present in the rehumidification mist before it is ejected into the enclosed room in which the printing chain is installed or in a paper storage workshop. , this having the advantageous effect of maintaining the ambient humidity level at a bearable level for the service personnel or for the paper stored. Indeed, it is important not to over saturate the work premises with water and it can be very useful to keep the stored paper at a high degree of humidity, before printing. The water thus captured then drips into the tank 51 to be collected also by the bowl 7 which can be emptied regularly by means of a discharge pipe with non-stop valve. represented.

It goes without saying that the flow rate of the spray nozzles 36, 37 of the mist as well as that of the fan 41 for extracting the latter from the enclosure, will have to be adjusted according to various parameters such as the nature of the paper to be rewetted. , its grammage, its running speed inside the enclosure, etc ...

In this regard, it has been observed that for the spraying flow rates and pressures of the nozzles 36, 37, usually used, the jets produced by compressed air charged with water droplets alone were sufficient to produce, in the vicinity of the 34.35 slots, the seal required for the proper conduct of the rehumidification process described above. To guarantee such a seal however in all circumstances, the rehumidifier according to the invention is provided inside the enclosure 8 and on each side of each of the slots 34, 35, with respective ramps of insufflation of dry air, as shown at 58 and 59 in FIG. 4 in connection with the entry slot 34 of the width P. The ramps 58.59, consisting of tubes 60.61, each provided with nozzles 62.63, are fixed by supports, such as 64, on the folded upper lips of the wall sections of the bowl 7 and are oriented parallel to the slots which they border. The nozzles 62,63 of the two twin ramps, associated with each slot 34,35, further converge upwards along the width of paper P. Each of the tubes 60,61 is also connected, by a conduit (not shown) passing through the bottom of the bowl 7 in a sealed manner, to a source of compressed air housed in the base 11.

Thus, if necessary, the ramps 58, 59 can be put into service so that the jets of dry air under pressure, produced by their nozzles 62, 63 arranged in tight rows, form air knots directed towards the one and the other of the faces of the width along each of the slots 34, 35 of the floor 7 of the enclosure 8, and, in this way achieve the desired seal at each of these, without modifying the degree of humidity inside the enclosure 8.

Claims (10)

1. A paper remoistening apparatus of the type comprising means (54, 55, 56) for driving a strip of paper (P) along a predetermined path within a sealed enclosure (8), into which nozzles (36, 37) for spraying a moistening mist open, said enclosure (8) commmunicating at a place remote from the spray nozzles (36, 37) with the inlet of a suction device (41) having its outlet (43) opening outside the enclosure, characterized in that the inlet of the suction device (41) communicates with the enclosure (8) through a droplet separator (48).
2. The remoistening apparatus according to claim 1, characterized in that the suction device comprises a fan (41).
3. The remoistening apparatus according to claim 1 or 2, characterized in that the droplet separator (48) comprises a duct (4, 50) fitted internally and over its entire cross-section with a three-dimensional mesh (49) of entangled metal fibres, said duct being, on one side, connected to the inlet of the suction device and opening, on the other side, into the bottom portion of the enclosure (8), away from the path of the strip of paper (P) and above a tank (51).
4. The remoistening apparatus according to claim 3, characterized in that the duct (4, 50) further comprises side openings (53', 53'') in a region located between the bottom portion of the enclosure (8) and the suction device (41).
5. The remoistening apparatus according to any of claims 1 to 4, characterized in that the enclosure (8) is limited in its bottom portion by a floor (7) provided with two generally parallel narrow slots (34, 35) for the strip of paper (P) to come in and out, respectively, and the spray nozzles (36, 37) are disposed in two rows extending on each side of one same slot (34), with the inlet of the suction device (41) communicating with the bottom portion of the enclosure on the side of the second slot (35) opposite to the first slot.
6. The remoistening apparatus according to claim 5, characterized in that the two rows of nozzles (36, 37) extend on each side of the inlet slot (34) of the strip of paper.
7. The remoistening apparatus according to claim 5 or 6, characterized in that the bottom opening (53), through which said inlet of the suction device (41) communicates with the enclosure (8) extends in the same direction and at least over the same length as the rows of nozzles (36, 37).
8. The remoistening apparatus according to any of claims 1 to 7, characterized in that the enclosure (8) has a vault-shaped roof (6) connecting without any dead space to the adjacent walls (5, 50) of the enclosure.
9. The remoistening apparatus according to any of claims 1 to 8, characterized in that the enclosure (8) has a pan-shaped floor (7).
10. The remoistening apparatus according to any of claims 1 to 9, having its enclosure (8) limited in the bottom portion thereof by a floor (7) provided with two slots for the strip of paper (P) to come in and out, respectively, characterized in that each of said slots (34, 35) is bordered on its two sides by two respective dry air blowing ramps (58, 59).

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