FI98389C - Method and apparatus for collecting and removing dust released from a web by a paper machine or similar or post-processing device - Google Patents

Description

98389

A method and apparatus for collecting and removing dust detached from a web on a paper machine or the like or a post-processing device. an after-treatment device for collecting and removing dust and the like detached from the web, wherein the space around the dust generating device or the like is encapsulated in a housing structure at least on one side of the web and dust and the like are removed from the enclosure 15 with the exhaust air.

The invention further relates to a device for collecting and removing dust and the like detached from a web by a paper machine or the like or a post-treatment device, which device comprises a housing structure formed around the dusting object at least on one side of the web, the housing structure being provided with an exhaust air duct for removing dust and the like.

25 In paper machines, a boundary layer of air is usually formed on both sides of a web moving at a fairly high speed, which carries with it »·> • · 4 ··· 4 dust detached from the web fiber and its fillers. Dust spreads • · **! partly in the environment, partly also on the web roll. In addition, dust and dirt adhere to the surface of the paper path • ♦ <• · after papermaking, e.g.

30 debris and fibers from the drying section of the paper machine.

One significant source of dust is the slitting process and dust problems • ·: * ·· also occur in the manufacture of tissue paper, especially in the case of scraper crepe, where a paper web is removed from the surface of a steam-heated Yankee cylinder with a scraper blade, releasing 35 particularly large amounts of dust. which the paper web attracts and spreads to its environment.

2 98389 Dust and dirt cause problems in further processing, eg printing, because keeping the printing rollers clean is essential for print quality.

5 In addition, dust spreads to the environment both at the factory and during further processing and may have occupational health hazards as it may contain various filler particles.

It is known from the prior art to prevent the spread of dust e.g. solutions in which the dusty object is encapsulated, the purpose of the enclosure being to limit the harmful dust to its place of origin. Enclosures can be designed in two main ways. Either the entire machine can be placed inside the housing or the dusty part of the machine or device can be placed inside the housing. Inside the housing, dust is removed with an off-15 inch through the exhaust air duct. This usually creates a vacuum inside the housing, which can cause paper web runnability problems, e.g. flutter. The enclosure principle and the dimensioning of air flows are known from several basic works in the field, such as the publications Industrial Target Ventilation, VTT / Helsinki 1982, and Air Conditioning at Workplaces 20, Pohjola Insurance Company 1979.

However, the encapsulation arrangements do not remove the dust entrained by the surface air flow of the web, nor the dust adhering to the surface of the web. For example, static electricity may attach dust to the surface of track I "25.

The object of the invention is therefore to provide a solution in which the transport of dust and dirt »» · with the web out of the enclosed space is eliminated or at least minimized. • · · · · · · · · · · · · · · · · · · · · .

30::: It is also an object of the invention to provide a solution by which the runnability problems caused by the vacuum inside the housing can be eliminated. . Tua.

In order to achieve the above and later objects, the method according to the invention is mainly characterized in that in the method the space provided with the housing structure is compacted in the direction of travel of the web from the exit side by an air curtain jet extending substantially the entire width of the web.

The device according to the invention, in turn, is mainly characterized in that the device further comprises a blowing device for sealing the space with the housing structure with an air curtain jet, that the blowing device is located on the exit side of the web from the housing structure in the web direction.

10

According to the invention, an air jet extending across the web is blown against the web, which air curtain closes the vacuum space inside the housing. The air jet seals the enclosed space against the web, significantly reduces the effect of web speed on the flows, and directs loose particles into the exhaust air stream.

The air curtain adjusts the vacuum of the enclosure to the desired level and, in addition, can remove loose fibers from the surface of the web.

According to a further advantageous feature, with the air curtain jet and on the guide surface of the device, the air flow accompanying the web can be turned towards the exhaust air flow, whereby the deaeration is made more efficient.

According to another advantageous additional feature, the static electricity is removed from the web and the static electricity is removed by means of a static electricity remover, whereby the dust particles attached to the paper web are also released by the action of the static electricity.

In the arrangement according to the invention, the vacuum of the vacuum space is measured 30 and the air curtain blowing is adjusted on the basis of the measurement result so that; :: that the vacuum in the room remains such that it does not cause driveability problems. In this connection, it can also be taken into account, for example, that with different cutters and winders the web speed varies periodically, e.g. 0 ... 35 m / s depending on the winding phase, and the pumping effect caused by this periodicity can be compensated by air curtain blowing. The device according to the invention is suitable for use in various applications with paper machines or the like, e.g. in connection with dust extraction of scrapers at the end of the drying section, after-treatment devices, e.g. with a slitter and / or tissue machine scraping scraper and other suitable and dirt cause problems.

In the following, the invention will be described in more detail with reference to the figures of the accompanying drawing, the details of which are not intended to limit the invention in any way.

Figure 1 schematically shows an arrangement according to the invention applied in connection with a slitter.

Figure 2 schematically shows a blowing device according to the invention.

In Fig. 1, the slitter is indicated by reference numeral 10 and the track guide rollers by reference numerals 11,12. The web W runs in the direction indicated by the arrows Sw. The area of the slitter 10 is encased in a housing structure 13, which enclosure can, if necessary, be formed as its own separate housing 13, or suitably located machine frame structures can be used as part (s) of the housing. In connection with the housing 13, an exhaust air duct 14 is arranged, into which a suction flow is arranged by the fan 15, whereby the space inside the housing 13 becomes vacuum.

• · · • · · • · In Fig. 1, arrows J denote schematically the air flows flowing in the space inside the housing 13 • · * ··· *.

According to the invention, a blowing device 20 is arranged on the outlet side of the web W of the housing 13, by means of which air blood is blown towards the web W; a jet extending substantially the entire width of the web W. Blowing ···. * J *. the air duct of the device 20 is denoted by reference numeral 21 and the associated fan by reference numeral 22. The measuring device 24 measures the vacuum of the space inside the housing 13 and the control and control devices 23 35 control the fan 22 of the blowing device 20 and thus according to the obtained measurement results 5 98389 so that the vacuum inside the housing 13 remains desired.

Fig. 2 shows in more detail a blowing air device 20 arranged 5 to seal the housing 13 on the discharge side of the web W from the housing 13. The blowing device 20 comprises a nozzle opening 25 from which an air jet P extending across the web is blown. The air duct of the device 20 is indicated by the reference number 21. The air flow guide surface 27 is formed in the device 20, by which the air flow Jw accompanying the paper web W, which often contains a lot of dust and dirt, is turned towards the exhaust air duct 14. The device 20 can also advantageously be provided with a static a direction of arrow Q in accordance removed static electricity from the web W surface, wherein the static electricity effects and 15 bonded tuksesta dust particles are released, and the transport of the web W is prevented air curtain P with ilmaverhopuhalluksella P air flow also is reversed, and thus towards the outlet air duct 14 (Figure 1). Through the exhaust air duct 14, the dust is led by means of the exhaust air for further treatment.

20

The device 20 according to the invention extends substantially in the transverse direction of the web W over its entire width.

... The blowing speed of the air curtain blowing P depends on the basis weight of the web and the support 25 and can be 20 ... 80 m / s, preferably 30 ... 50 m / s, e.g.

% · · • * For webs weighing 150 ... 180 g / m2. The blowing direction may be oblique to the direction of travel of the web «· * ··· 'and its angle α with respect to the direction of travel S of the web may be 30 ° .. .90 °, preferably 40 ° ... 50 °.

The invention has been described above only in some of its preferred applications; with reference to examples, the details of which, however, are not included in the invention; intended to be narrowly constrained.

Claims (8)

A method of a paper machine or equivalent, or of a post-processing device for such a collection and removal of dust and the equivalent discharging from the tap (W), in which method the space around the device (10) forming dust or the like is surrounded having a case structure (13) at least from one side of the web (W) and removing dust and the corresponding from within the space having a case structure (13) with the outlet air in the form of an outlet air stream 10 via an outlet air duct (14), characterized in that: the space provided in the process with a case structure (13) is sealed in the running direction of the web (W) from the exit side with an air curtain beam (P) extending substantially over the width of the web (W). 15 2. A method according to claim 1, characterized in that the air stream containing the dust and the equivalent that comes with the web (W) is pivoted with the air curtain beam (P) towards the outlet air duct (14) and that with the air curtain beam (P) the dust and the corresponding fixed to the web (W). Method according to Claim 1 or 2, characterized in that during the process static electricity is removed from the web (W) to release dust which is attached by dissemination of static in electricity before the air curtain blowing (P). «4» »· * · tt · I 4. Procedure according to any of the preceding claims, characterized - • M, ···, signed therefrom, that the negative pressure inside the case construction 4 · · * (13) is measured and based on the measurement results. the strength of the air curtain (P) is adjusted to maintain the vacuum at the desired level. 9,38,389 (13) is provided with outlet air duct (14) for removing dust and correspondingly from the outlet air duct, characterized in that the device further comprises a blower (20) for sealing the space provided with a case structure (13) having an air curtain beam (P) and a blowing device (20) located on the exit side of the web (W) from the space construction of the web (13) in the running direction of the web (W). 6. Apparatus according to claim 5, characterized in that the blower device (20) comprises a means for removing static electricity to remove static electricity on the surface of the web (W) and thus releasing dust bonded to the web (W) by mediation. of static electricity. Device according to claim 5 or 6, characterized in that the blower (20) comprises a control surface (27) for pivoting about the air stream (Jw) running with the web (W) towards the outlet air duct (14). Apparatus according to any one of claims 5-7, characterized in that the device comprises a measuring device (24) for measuring the negative pressure in the interior space of the housing (13) with the case-i; the construction and control and control means (23) for controlling; ; the strength of the air curtain blowing (P) and by mediating this pour »1 ·. 25 at the desired level. • «•» · k · i · »Il • Λ Ψ% I •) f ί J ·« • 4 • 1 • <· «« 0 # 4 f I <