MXPA99007135A - Dust extracting installation on machine producing crepe paper - Google Patents

Abstract

The invention concerns a machine for the continuous production of crepe paper, comprising a drying cylinder (12), a blade (20), and a reel winder (24), the paper sheet after dying being unstuck from the cylinder with a blade and wound on the reel winder, with a dust extracting installation. The invention is characterised in that means (30) forming a water curtain for controlling and entraining the fibre particles suspended in the air is arranged, transversal to the unwinding direction of the paper sheet, under the sheet between the cylinder (12) and the reel winder (24). The water curtain (30) is preferably provided with air extracting means (64, 66) and means for blowing highly pressurised or compressed air (56, 74) for collecting the major part of the fibre and dust masses generated by the action of the creping blade (20).

Description

INSTALLATION FOR EXTRACTING DUST FROM A CREPE PAPER PRODUCING MACHINE Description of the invention? The invention relates to an installation for removing dust in a crepe paper machine. The invention relates more particularly to a machine for the continuous manufacture of crepe paper, of the type in which the sheet, after formation, draining and optionally partial drying, is applied on a suitably heated drying cylinder. After drying, the sheet is detached from the cylinder by means of a corrugating blade, which scrapes the surface of the cylinder according to an appropriate angle. The blade, so detached and undulating, is guided longitudinally towards a winder. Cellulose cotton or tissue paper is thus manufactured for domestic or sanitary uses, such as toilet paper, cleansers, handkerchiefs, napkins, etc. The corrugating blade, which scrapes the cylinder, allows the blade to be detached and the formation of wavy lines. This causes the release of dust and paper fibers in a more or less important amount, according to the quality of the paste, the degree of dryness reached by the sheet or, eventually, the incorporation of release agents intended to improve the softness A part of this dust and these fibers tends to follow in the path of the paper, which, due to its great velocity, drags with it a layer of air, along each of its two faces. This mass of moving air carries a lot of dust. However, still a larger amount of powder or piles of fibers tends to be released at the level of the corrugation blade, in an area that is between the detached sheet of paper and the cylinder, below its two surfaces. The dust thus released tends to accumulate on the paper production facility, and the construction in which the installation is contained. This tends to create unfavorable environmental conditions for operators working around the machine or in the vicinity of construction. In addition, the dust and fiber detached form a highly flammable material that runs the risk of catching fire with the smallest spark likely to appear between the corrugating blade and the drying cylinder particularly, or in any other area of the machine or the construction in which it accumulates. The drying cylinder is generally provided with a heating hood, which is another potential source of inflammation of the dust accumulated in the installation.

Finally, these undesirable fibrous particles can disturb the operation of the machine or affect the quality of the paper produced. In order to limit the dispersion of the powder, it has been proposed to confine the installation itself to prevent the dust from dispersing throughout the construction. Covers have been placed on the parts of the machine between the heating cylinder and the winder, as well as on the coil itself. Inside these enclosures, they have been provided with suction hoods to create a favorable air circulation. These means are relatively effective to prevent dust from leaking into the machine room and therefore avoid the risk of fire. However, the accumulation on the machine itself of the dust and detached fibers continues to be an important problem to be solved. Of course, the accumulation of dust is particularly important in an area located in the vicinity of the corrugating blade, and just below it. It has already been proposed in US-A-5,011,574, a machine for crepe paper production, which is provided with a device for dust removal with suction, where the air intakes are placed in the immediate vicinity of the corrugating blade. Another document, EP-A-0,310,161, describes and represents a device designed to suck the dust transported by the air layer following the movement movement of the paper sheet. The document US-A-5,466,298, describes a device for removing dust from the sheet of paper, in which the compressed air is blown very close to one of the faces of the sheet of paper, to counteract the dragging of the air mass following the path of the paper sheet. When mixed with the compressed air, this air mass is stopped, and then aspirated by an adjacent suction device. The set of these techniques, although they allow to diminish the amount of dust that is released around the installation or that accumulates on the machine, needs the treatment and the elimination of the dust of very large masses of air. The enclosures have the drawback of being very difficult to control. In particular, they are easily clogged by the aggregates of the powder or fibers. Furthermore, due to their punctual action, they do not provide a global solution to the problems created by the formation of dust due to the paper curling operation. To provide a solution to the problems created by the production of powder created when the paper is corrugated, the invention proposes an installation for extracting dust on a machine of the type described above. It is characterized in that it comprises a means that forms a curtain of water to capture and drag the fibrous particles in suspension in the air, arranged transversely to the direction of movement of the sheet of paper, under the sheet between the cylinder and the winder . The application of such a device has numerous advantages. In effect, it is of great efficiency in the dragging of the fibrous particles in suspension, particularly when the circulation of the water along the wall is turbulent. It also allows the evacuation of the most important heaps, and avoids the formation of accumulations susceptible to disturb the operation of the machine. According to other characteristics of the invention: the means forming the wall of water comprises a substantially vertical wall, and a means of feeding water with a spillway positioned so as to form a continuous, homogeneous and permanent water film throughout of the wall; The medium that forms the water curtain is placed under the corrugating blade. It allows, thus, to directly capture the dust and the piles of fibers produced at this level; a collector for the reception and evacuation of the liquid that drains from the wall, is placed under the latter to clean a passage of air; it is advantageously constituted of a pile in which the bottom is inclined to allow the liquid to flow towards the recovery pit of the white waters; It is placed under the wet part and the press section in front of the drying cylinder. This collector is provided with water sprinkler ramps, which allow to evacuate the piles of fibers that fall from the water curtain; the means are provided to generate a circulation of air towards the lower part, at least in the area surrounding the medium that forms the curtain of water, these means also favor the uptake of the fibrous particles in suspension in the air; in particular, a means for generating a circulation of air in the vicinity of the lower face of the paper sheet, to cause the detachment of the air jets following the movement movement of the sheet of paper, this means is constituted by a member for injection of compressed air or high pressure, arranged in the vicinity, and below the blade; - another means to generate the air circulation, and at the same time ensure the evacuation of a part of the particles in suspension, is constituted by a suction enclosure placed behind the curtain of water, so that it sucks the air that is found in the enclosure delimited by the water curtain, a separating partition with the wet part of the machine, the cylinder and the floor, and that comes particularly from the passage between the wall and the collector; and, particularly in a facility comprising in a manner known per se, a pit with a grate for recovering waste from the paper, an air injection member is placed under and at a distance from the water curtain, and is oriented towards the lower part to drag the movement of the air along the curtain of water towards the pit with a grid. In this hypothesis, a suction hood of air is placed below the air injection member. In this last case, the solution of the invention is particularly effective to evacuate towards the pit with grid, the paper waste from a voluntary or non-breaking of the sheet; an aerodynamic guide without contact with the sheet, and located below it, is generally designated by the term "sheets" is placed immediately below the blade cutting blade, and extends towards the thickness measurement scanner. This arrangement ensures a great stability of the blade, despite the injection of air in the vicinity. This support preferably comprises a part rotating around a transverse axis to open a passage to the grate pit, in case of its use, and the cutting blade to detach the sheet from the heating cylinder, in order to replace it or to clean the corrugating blade. Other characteristics and advantages of the invention will appear from the reading of the detailed description that follows, for the understanding of which, reference will be made to the attached drawings in which: Figure 1 is a schematic sectional view of a part of an installation for the continuous manufacture of crepe paper according to the teachings of the invention; - Figure 2 is a perspective view illustrating an embodiment of a means forming the water curtain according to the invention. FIG. 1 shows a part of the installation 10, for the continuous production of crepe paper. More particularly, the installation shown is the dry section downstream of a paper machine with a drying cylinder 12 of the type known under the name "Yankee". The drying cylinder 12 is in rotation, in the clockwise direction, considering Figure 1, around its transverse axis Al. a pressure cylinder 14, applies to the still wet sheet, on the outer cylindrical surface 16 of the drying cylinder 12, a ramp of Spray 17, shown upstream, previously deposits a layer of appropriate adhesive. The sheet of paper then follows the movement of the cylinder, first according to an upward trajectory. A heating hood 18, which covers the upper part of the cylinder 12, causes the sheet to dry together with the cylinder. This is dried to a dryness of about 95%, and is transformed into a sheet of paper, which needs to be detached from the cylinder 12. For this, a corrugating blade 20, also called scraper, rests against the outer surface 16 of the cylinder 12. The sheet of paper thus detached from the cylinder and corrugated, is then guided longitudinally forward in the direction of a winder 24, which makes it possible to form rolls 26 of paper. The guide means 23 of the blade are provided below the blade 20, and have the function of stabilizing equally. These means 23 are advantageously constituted by the non-contact aerodynamic guides, located above the blade, also called "blades", and extend downwards after the cutting blade 19 of the blade, placed above the corrugating blade. In the installation shown, the "leaves" 23 comprise an upper part in the form of a shoe 23 'placed immediately below the cutting blade 19, followed by a rotating part 23"around a transverse axis. a passage, and continue to peel off the blade of the cylinder, cutting by means of the blade 19, or when it comes to changing the corrugating blade or cleaning it. This opening also allows to evacuate the sheet, until the production is resumed. The paper curling operation 22 causes the formation of a lot of paper dust and detached fibers, especially in an area below the paper sheet 22, and below the cylinder 12. The dust and heaps of other materials are likewise produced by the cleaning blade 32, located below with respect to the point of blade flaking. According to the teachings of the invention, the installation 10 comprises an area 28, in which an air circulation is established which allows a large part of the produced dust to be guided in the direction of a water curtain means forming a trap for the powder 30. This area 28 is delimited at its top and back by the paper sheet 22. Behind the corrugating knife 20, the area is delimited by the cylindrical surface 16, from which the sheet 22 has been detached. This surface 16 is cleaned by the cleaning blade 32, which is positioned behind the corrugating blade 20, and its function is to eliminate all traces of paper remaining on the cylinder 12 after the paper sheet 22 'is shed. Just below the cleaning blade 32, the water curtain means 30 is placed. The water drains along the front face of a wall 26, with a generally vertical orientation, which further delimits the air circulation zone 28 backwards. The wall can be made with a plate of sheet metal or a plastic material, preferably polished or smooth, in order that it does not present any roughness capable of retaining the fibrous particles dragged by the water of the water curtain towards the lower part , after its capture by the same. The water curtain means 30, is more particularly represented on FIG. 2, in which a horizontal feed channel 31 can be seen, which extends along an upper edge 33 of the wall 36. This channel 31, which is filled with water, conveniently purified water, overflows over the entire length by a rear edge 35, which forms a landfill, which is bent towards the lower part, so as to pour a curtain of water on the rear surface 34 of the wall 36. In order to improve the quality of the runoff, and to facilitate the formation of a homogenous and turbulent film, the lower edge of the drain is serrated. In fact, a turbulent film with a flow rate between 5 and 10 pvV-hour, per meter of length of the machine, seems to be a favorable condition to avoid the accumulation of fibers or pieces of paper. The wall 36 is not flat, it is convex on its lower part 38, which bends backwards. This tilts an accumulated dust evacuation collector, and cleans a passage 58 for air. This manifold 40 is constituted by a liquid receiver, in which the bottom 44 is inclined and oriented towards the wet part of the paper machine. It comprises a spray chute 42, advantageously fed with purified water, which helps the evacuation of the piles. The latter is located below the lower part 38 of the wall 36, so that the collector 40 extends behind the wall 36. In an appreciable way, in the extension of the wall 36, and behind it, find the entrance 46 of a pit with a grate 48, for the recovery of paper waste produced when the sheet is broken voluntarily or not. The grate pit 48 can also catch a portion of the fibers detached from the paper by the corrugating blade 20, unless they have a weight that is sufficient to not be carried by the air circulating around the corrugating blade 20.

Behind the air circulation zone 28, there is a transverse catwalk 50, which extends * above the grid pit 48, and below the paper sheet 22, which is guided towards the winder 24. This gangway 50, which allows the intervention of the operators in the machine, comprises a parapet provided with a vertical, smooth plate 52, which delimits behind, the air circulation area 28. The gangway 50 allows operators to intervene in a space 54 located appreciably below the sheet of paper 22, and behind the circulation zone 28. In accordance with the teachings of the invention, means are provided for establishing currents and flow in the circulation zone 28. air flow that allows to guide the dust, particularly in the middle direction of the water curtain 30. In this way, a first air flow is created from the upper part to the lower part, in this air circulation area 28, grac A first air injection chute 56 placed immediately below the corrugating blade 20, and which injects compressed or overpressured air towards the lower part, between the paper sheet 22 and the water curtain 30. This air is induced in a large amount that comes from the sides of the machine. The flow of air created by the first air injection chute 56 also makes it possible to detach, at least partially, the bursts of air circulating along the lower face 70 of the paper sheet 22, for example. the fact of the displacement of the latter. The arrangement of the aerodynamic support 23, immediately behind the blade 19, allows an effective action of the air injection device 56. Without this means, the blade would lose stability and it would be necessary to limit the mass of air injected. In the lower part of zone 28, two air aspiration zones are created. The first of these is intended to create an important air flow, in the passage 58 of reduced section, placed between the lower part 38 of the wall 36 of the water curtain and the collector 40. For this, a partition 62 is placed. vertical, behind the wall 36, so as to delimit an enclosure 60 closed appreciably, which is bounded longitudinally backwards by the wall 36, behind the partition wall 62, and which is bounded vertically towards the top by the cylinder 12 and towards the bottom by the upper face 44 of the manifold 40. This chamber 60 is kept underpressured with respect to the air circulation area 28, thanks to a suction hood 64. In this way, an important aspiration is created through the passage 58, under the water curtain between the air circulation zone 28, and the rear enclosure 60. The suction hood also has the function of removing the dust particles and the humidity generated at the level of this enclosure. It is attached to the vacuum source by an appropriate separator to remove solid particles, essentially fibrous, and liquids entrained in the air flow. The air flow through the enclosure is between 1000 and 3000 m3 / hour per meter in length. As can be seen in the figures, the lower part 38 of the wall 36 of the trap 30 is convex and curves backwards, so that the flow of air flowing from the upper part towards the lower part tends to adhere to the contour of the wall 36, although the dust transported by this air flow tends to be picked up by the water film or curtain, which runs off along the rear face 34 of the trap 30. When the water of the The water curtain reaches the bottom of the wall 36, is poured over the evacuation manifold 40, and further forms a water barrier through a door 58, through which a large part of the air flow circulates. . As can be seen in figure 1, a second suction hood 66 is placed at the level of the inlet 46 of the grid pit 48. Located a little further down in the circulation area 28, and behind it, allows to recover the part of the air flow that was not sucked by the rear enclosure 60. It also allows to vacuum the dust in suspension in the grate 48. The installation according to the invention comprises means to create , in the air circulation zone 28, a flow of air that flows appreciably in the opposite direction with respect to the displacement of the paper sheet 22, so as to prevent the dust from being drawn out of this circulation zone. For this purpose, we can note that the sheet 52 positioned along the parapet of the footbridge 50, delimits with the sheet of paper 22, a door 72 between the air circulation zone 28, and the space 54 delimited above the footbridge 50. The length of the upper edge of this plate 52, which is opposite the lower face 70 of the paper sheet 22, is placed a second ramp 74 for projection of compressed or overpressured air, so that it projects the air in the direction of the interior of the air circulation area 28. More particularly, the air is projected towards the bottom and backwards, appreciably in the direction of the water curtain. In combination with the underpressure effect created by the suction of air in the lower part of this zone 28, a circulating air current is thus established, at the level of the door 72, along the lower face 70 of the sheet of paper 22, after the rear space 54 in the direction of the air circulation zone 28, that is to say in the opposite direction of the displacement of the paper sheet 22. In this way, this air current causes a detachment of the bursts of air. air normally directed to follow the displacement of the paper sheet 22, these air bursts are diverted inwards, and towards the lower part of the air circulation zone 28, to be sucked through the passage 58 or through a second suction device 66. The cleaning of the circulation zone 28, therefore, allows a large part of the dust created by the corrugation of the paper to be recovered by the water curtain 30, and evacuated by the collector. evacuation 40. With regard to the devices that only use the air suction hoods to evacuate the dust, we can, in this way, reduce in a very important way the volume of air that needs to be circulated, the volume of air that it must necessarily be treated so as not to discharge the dust into the atmosphere. This represents a significant economic advantage. Therefore, the water curtain 30, which is realized here in the form of a film, which drains appreciably on a vertical wall, can be realized by following other equivalent techniques. A dust recovery and evacuation system, such as the one described, also has the advantage of being adaptable to an existing installation. It is also compatible with the known confinement devices of the installation. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Claims (12)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property.

1. A machine for the continuous manufacture of crepe paper of the type comprising a drying cylinder, a scraper blade, and a winder, the paper sheet, after drying, is detached from the cylinder by the blade and placed on a roll by the winding machine, with an installation for extraction of the dust, characterized in that a medium that forms a stream of water to capture and drag the fibrous particles in suspension of the air, is placed transversely to the direction of displacement of the sheet of paper, under the ho between the cylinder and the winder.

The machine according to claim 1, characterized in that the means comprises a vertical wall appreciably, and • a means of feeding water with a spillway positioned so as to form a film on one side of the wall.

3. The machine according to claim 1, characterized in that the runoff of water along the wall is turbulent.

4. The machine according to one of the preceding claims, characterized in that the means is placed below and in the vicinity of the corrugating blade.

5. The machine according to claim 4, characterized in that a liquid collector, preferably provided with a water spray ramp, is placed below the wall, to clean an air passage.

The machine according to one of the preceding claims, characterized in that it comprises means for creating a circulation of air towards the lower part, at least in the area surrounding the medium, so as to favor the uptake of the fibrous particles.

The machine according to one of claims 4 to 6, characterized in that it comprises a means for injecting compressed or overpressured air, arranged in the vicinity of and under the blade, to create an air current in the vicinity of the lower face of the sheet of paper, behind the blade, and cause the detachment of the bursts of air following the movement of movement of the sheet of paper.

8. The machine according to one of claims 4 to 7, characterized in that it comprises a hood for spraying air and fibrous particles placed along the wall, behind the surface, so as to suck the air into the wall. enclosure delimited by the wall, a partition wall vertical, the cylinder and the floor, which comes particularly from the passage.

The machine according to one of claims 4 to 8, which comprises, in a known manner, a pit with a grate for recovering waste paper, characterized in that it comprises an air injection means, placed under the medium and at a distance from the same, oriented towards the lower part, to drag the movement of the air along the middle towards the pit with grid.

The machine according to one of claims 4 to 8, which comprises, in a known manner, a pit with a grate for recovering waste paper, characterized in that it comprises a suction hood of air, and fibrous particles placed on the medium of air injection.

The machine according to one of the preceding claims, comprising a blade cutting blade, placed above the corrugating blade, characterized in that it comprises an aerodynamic guide without contact with the blade, which extends after the blade cutting the sheet and below it.

12. The machine according to the preceding claim, characterized in that the support comprises a part rotating around a transverse axis to open a passage evacuation of the sheet in the event of the latter being shed by the cutting blade, instead of the corrugating blade .