EP2860312B1

EP2860312B1 - Arrangement of a fiber web production line and method of a fiber web production line

Info

Publication number: EP2860312B1
Application number: EP13187694.8A
Authority: EP
Inventors: Tapio Pitkäniemi; Topi Tynkkynen
Original assignee: Valmet Technologies Oy
Current assignee: Valmet Technologies Oy
Priority date: 2013-10-08
Filing date: 2013-10-08
Publication date: 2019-05-22
Anticipated expiration: 2033-10-08
Also published as: EP2860312A1; CN204238070U

Description

The invention relates to an arrangement of a fiber web production line and to a method in a fiber web production line. Especially the invention relates to an arrangement and to a method of a coating or sizing section of a fiber web production line, in which section the coating or sizing medium is applied on the fiber web by spray means. More especially the invention relates to an arrangement according to the preamble part of claim 1 and to a method according to the preamble part of claim 6.
As known from the prior art in fiber web producing processes typically comprise an assembly formed by a number of apparatuses arranged consecutively in the process line. A typical production and treatment line comprises a head box, a wire section and a press section as well as a subsequent drying section and a reel-up. The production and treatment line can further comprise other devices and sections for finishing the fiber web, for example, a sizer, a calender, a coating section. The production and treatment line typically also comprises a reel-up and at least one winder for winding customer rolls as well as at least one roll packaging apparatus. In this description and the following claims by fiber webs are meant for example paper and board webs.
In production of fiber webs, for example of paper or board webs, sizing is used to alter the properties of a fiber web by adding sizing agents (sizing medium), for example glue chemicals. Sizing can be divided to internal sizing and surface sizing. In internal sizing the sizing agent is added to pulp in the wet end of the fiber web machine before forming. In surface sizing the sizing agent is added onto the surface of the fiber web at the dry end of the fiber web machine.
In production of fiber webs, for example of paper or board webs, in coating, especially the surface of a fiber web is formed with a layer of coating color (coating medium) at a coating station followed by drying. The formation of a coating in direct coating applications can be divided in supplying the coating color onto the web surface, which is called the application of the coating color, as well as in the adjustment of final amount of coating color. In indirect coating applications the adjustment of the color amount is controlled already when supplying the color and therefore an additional adjustment is not needed.
The coating or the sizing of a fiber web typically utilizes a coating device - a coater - or a sizing device - a sizer, which together with for example drying devices following the coater/sizer form the coating / sizing section of a fiber web production line. In connection with the coaters and sizers different kinds of application technology for application of the coating or the sizing medium on the fiber web are employed in prior art arrangements, for example curtain technology or blade application technology or rod application technology or air brush application technology or spray application technology. The present invention relates to spray application technology.
In WO publication 2006/058961 A1 is disclosed a method and arrangement for processing a paper or board web or similar fiber web. In this prior art method a processing mixture is applied on the surface of the web with spray nozzles. In WO publication 02/072953 is disclosed an assembly for treating a moving web of paper of board with web treatment substance which assembly comprises an application chamber located in at close vicinity of the moving web and facing the web and at least one linear nozzle array incorporating at least one nozzle for spraying the web treatment substance on the web. In Fl utility model registration 9401 is disclosed a device for treating a fiber web, which comprises an application device, in particular a spraying device, for applying treatment substance on a moving fiber web.
In US 2005/098291 is disclosed an apparatus for paper making and paper surface enhancement, in which nozzles are located in several rows in cross-direction i.e. in width direction of the paper web.
US 2003/120303 discloses a distribution pipe structure from steel industry, in which the pipes are located within each other and the innermost pipe is for glue and in the two outer pipes there is water for controlling the temperature of the glue and for cleaning the nozzles.
In US 2007/029411 is disclosed an air atomizing nozzle system for medical industry in which substance is distributed to all nozzles by one pipe.
US 2118212 discloses a process and apparatus for coating paper in which several rows of nozzles are used.
The coating and sizing units can be located in different positions in the fiber web production line, for example at a wire section, or at a press section, or at a drying section comprising drying cylinders. However, the typical location is after the pre-dryer section, when the web moisture is typically between 2-12 %. The nozzles or nozzle units of a spray coating or sizing unit are as known from prior art attached to a distributor pipe that extends in cross direction over the width of the fiber web and that delivers the treatment substance to the nozzles. In figure 1 is shown side projection one schematical example of prior art arrangement of spraying device for applying treatment substance on a moving fiber web W. The spraying device according to prior art comprises a distributor pipe 10 extending in cross direction over the width of the fiber web W. The distributor pipe 10 comprises several at a distance in the cross direction spaced apart from each other located nozzles 20 in one row, which nozzles 20 creating one nozzle row 21 are typically supported by a support element 15 extending in the cross direction. Into all nozzles 20 of the nozzle row 21 the treatment substance is supplied via channels 11 from the distributor pipe 10. In this prior art arrangement large changes in application amounts of the treatment substance to be sprayed onto the fiber web W via the nozzles have not been possible without changing the nozzles or without using several successive nozzle rows in the running direction of the web. Typical flow amount window for a nozzle in pressure range 3-12 bar is set point ± 30 %. Typical sizing amount as dry for woodfree copy and special papers is 0.5-1.5 g/m² and for different board grades 1-3 g/m². The prior art arrangement is also problematic in cases in which different substance components are used simultaneously to form the treatment substance since the substances, for example hydrophobic chemicals and color agents may react with each other or with impurities of return-flow and thus plugging may occur for example in the nozzles.
An object of the invention is to create an arrangement in a fiber web production line and a method in a fiber web production line in which the disadvantages of known arrangements and methods relating to changes in application amounts of the treatment substance are eliminated or at least minimized.
An object of the invention is to provide an arrangement of a fiber web production line and a method of a fiber web production line in which problems with treatment substance component reacting with each other creating plugging problems are eliminated or at least minimized.
Further objects of the invention is to provide an arrangement of a fiber web production line and a method of a fiber web production line in which new possibilities of amount adjusting of the treatment substance and of substance component selection are available.
In order to achieve the above objects the arrangement according to the invention is mainly characterized by the features of claim 1 and the method according to the invention is mainly characterized by the features of claim 6.
According to an advantageous aspect of the invention the arrangement of a coating or sizing section of a fiber web production line, in which section a treatment substance, in particular a coating or sizing medium, is applied onto the fiber web by spraying, which arrangement comprises nozzles located in one nozzle row extending in cross-direction i.e. in width direction of the fiber web for spraying the treatment substance onto the fiber web and at least two distributor pipes connected to the nozzles for supplying treatment substance to the nozzles in the one nozzle row and the at least two distributor pipes are each connected to alternate nozzles of the one nozzle row.
The nozzles in the one nozzle row do not necessarily need to be on straight line and center lines of the nozzles, in particular for different distribution pipes, can be offset +/- 20 mm in the nozzle row, advantageously +/- 10 mm. The offset depends on distribution of the nozzles and on desired coverage of the treatment substance on the fiber web.
Advantageously the arrangement comprises two distributor pipes each connected to alternate nozzles of the one nozzle row.
Advantageously the arrangement comprises control means to selectively supply treatment substance from the distributor pipes, for example from only one distributor pipe. The control means are for example arranged as valves before inlet of each distributor pipe. The treatment substance is supplied by one machine circulation via one inlet channel and just before the inlets to the distributor pipes the inlet channel is divided to channels with valves leading to each of the inlets to the distributor pipes. Each distributor pipe may also have a machine circulation of its own, for example in cases where the treatment substances are not to be mixed at this stage, and thus each distribution pipe has own inlet channel, pump and optional valve. In this arrangement the inlet is controlled by the pump or by the optional valve.
The dimensions of the distributor pipes can be same or different. Wet treatment substance amounts applied by nozzles of the distributor pipers vary from 5 g/m² to 50 g/m² and the speed of the fiber web depending on the production line varies from 300 m/min to 2000 m/min and the width of the fiber web from 3 m to 10 m, thus the total inlet amount of treatment substance amount to each distribution pipe varies from 10 kg/min to 1100 kg/min. Desired flow rate at inlet to distribution pipe varies form 2 m/s to 10 m/s and thus needed inside diameter of one distributor pipe, if only one distributor pipe is used, is from 10 mm to 80 mm and thus according to an advantageous feature the inside diameter of each distributor pipe is from 8 mm to 56 mm taking in account that the diameters of the distributor pipes can be different from each other in the arrangement according to the invention.
The feed into each distributor pipe can be from the same or different ends of the distributor pipes. The outlet from each distributor pipe can be from the same or different ends of the distributor pipes. In cases where the feed to the distributor pipes is at different ends and the outlet correspondingly at different ends of the distributor pipes an inclined profile of the spayed substance amount of one distributor pipe caused by pressure loss between the ends of the distributor pipe can easily be corrected.
According to one advantageous feature the outlet flow from one distributor pipe can be led to another distributor pipe and the fresh treatment substance flow to the one distributor pipe.
According to the invention the method of a coating or sizing section of a fiber web production line, in which method a treatment substance, in particular a coating or sizing medium, is applied onto the fiber web by spraying by nozzles located in one nozzle row extending in cross-direction i.e. in width direction of the fiber web for spraying the treatment substance onto the fiber web, characterized in that in the method the treatment substance is supplied to the nozzles by at least two distributor pipes and in the method the treatment substance is supplied by the at least two distributor pipes, which are each connected to alternate nozzles of the one nozzle row, alternatingly to the nozzles of the one nozzle row.
Advantageously in the method the treatment substance is supplied by two distributor pipes alternatingly to the nozzles of the one nozzle row.
According to an advantageous feature of the invention different treatment substances or components of the treatment substance can be supplied via different distributor pipes. By this it is possible to use substances that when reacting with each other before nozzles would cause plugging. Furthermore two-component substances can be used by supplying one component by one distributor pipe and one component by another distributor pipe. The different substances or components of the substance can be for example a combination: color substance -hydrophobic substance, one color substance - another color substance, substances with different viscosity and solids content, water - chemical substance etc.
By the invention the amount of treatment substance can be controlled without any need for changing the nozzles. Also in case the undesired plugging occurs in one distributor pipe the other one can be used.
In the following the invention is explained in more detail with reference to the accompanying drawing in which

Figure 1 shows as side projection one schematical example of prior art.
Figures 2 - 3 show as side projection schematically one advantageous example of the invention.
Figure 4 shows as a longitudinal view in the width direction of a fiber web schematically one advantageous example of the invention.
Figures 5A - 5B show very schematically examples of one nozzle row.

In the figures the corresponding elements, parts and part components of the arrangement are denoted by same reference signs in the figures unless otherwise mentioned.
In figure 1 is shown side projection one schematical example of prior art arrangement of spraying device for applying treatment substance on a moving fiber web W. The spraying device according to prior art comprises a distributor pipe 10 extending in cross direction over the width of the fiber web W. The distributor pipe 10 comprises several at a distance in the cross direction spaced apart from each other located nozzles 20 in one row, which nozzles 20 creating one nozzle row 21 are typically supported by a support element 15 extending in the cross direction. Into all nozzles 20 of the nozzle row 21 the treatment substance is supplied from the distributor pipe 10 via channels 11.
In figures 2 - 3 is shown side projection one advantageous example of an arrangement of a spraying device for applying treatment substance on a moving fiber web W according to the invention. The spraying device comprises two distributor pipes 10A, 10B extending in cross direction over the width of the fiber web W. The spraying device further comprises several at a distance in the cross direction spaced apart from each other located nozzles 20A, 20B in one nozzle row 21, which nozzles 20A, 20B creating the one nozzle row 21 are supported by a support element 15 extending in the cross direction. The two distributor pipes 10A, 10B are alternatingly connected to the nozzles 20A, 20B for supplying treatment substance to the nozzles 20A, 20B in the one nozzle row. Each distributor pipe 10A, 10B are connected to alternate nozzles 20A, 20B of the one nozzle row 21. As shown in figure 2 from distributor pipe 10A the treatment substance is led to nozzles 20A via channels 11A. Each nozzle 20A having its own channel 11A. As shown in figure 3 from distributor pipe 10B the treatment substance is led to nozzles 20B via channels 11AB. Each nozzle 20aB having its own channel 11B.
As shown in figure 4, where feeds and outlets are indicated by arrows, the feed 12A, 12B, into each distributor pipe 10A, 10B is in this example arranged from the same end of the distributor pipes 10A, 10B. Correspondingly in this example the outlet 13A, 13B, as indicated by arrows, from each distributor pipe 10A, 10B from the same of the distributor pipes 10A, 10B The feed 12A, 12B and correspondingly the outlet 13A, 13B of the distributor pipes 10A, 10B can also be at different ends of the distributor pipes 10A, 10B as shown by dashed arrows. From distributor pipes 10A, 10B via channels 11A, 11B correspondingly the treatment substance is supplied correspondingly to the alternate nozzles 20A, 20B to be sprayed onto the passing fiber web.
In figures 5A - 5B is very schematically, not in scale, shown examples of one nozzle row 21. The nozzle row comprises nozzles 20A, 20B located in the one nozzle row. The nozzles can be located offset O +/- 20 mm, advantageously +/- 10 mm. The offset O depends on distribution of the nozzles 20A, 20B i.e. the cross-directional distance between the nozzles and on desired coverage of the treatment substance on the fiber web. The coverage of the treatment substance spray of one nozzle is typically 300 mm on the fiber web and when the distance between two nozzles next to each other is advantageously 50 mm (i.e. 50 mm distribution of the nozzles) and when the nozzles are at an advantageous angle of 7-15 ° in relation to the plane perpendicular of the fiber web surface and at adjacent nozzle a fan creating the treatment substance spray is located about 4 -14 mm above the nozzle center line, a six-fold coverage of the treatment substance on the fiber web W is achieved but the treatment substance sprays are not disturbed by treatment substance sprays of the adjacent nozzles 20A, 20B. The center lines of adjacent nozzles 20A, 20B can be located from 0 to 10 mm from the center line of adjacent nozzle 20B, 20A. The nozzles 20A, 20B, in particular for different distribution pipes 10A, 10B, can thus be offset O +/- 10 mm in the nozzle row 21, when the distribution is 50 mm, and offset O +/- 20 mm, when the distribution is 100 mm, as shown in figures 5A and 5C. In the example of figure 5B center lines of all nozzles 20A, 20B are in the one nozzle row 21 on same straight line.

Reference signs used in the drawing:

10, 10A, 10B distribution pipe
11, 11A, 11B channel from distribution pipe to nozzle
12A, 12B inlet to distribution pipe
13A, 13B outlet from distribution pipe
15 support element
20, 20A, 20B nozzle
21 nozzle row
W web
O offset

Claims

Arrangement in of a coating or sizing section of a fiber web production line, in which section a treatment substance, in particular a coating or sizing medium, is applied onto the fiber web by spraying, which arrangement comprises nozzles (20A, 20B) located in one nozzle row (21) extending in cross-direction i.e. in width direction of the fiber web for spraying the treatment substance onto the fiber web, characterized in that the arrangement comprises at least two distributor pipes (10A, 10B) connected to the nozzles (20A, 20B) for supplying treatment substance to the nozzles (20A, 20B) in the one nozzle row (21) and that in the arrangement the at least two distributor pipes (10A, 10B) are each connected to alternate nozzles (20A, 20B) of the one nozzle row (21).
Arrangement according to claim 1, characterized in that the center lines of the nozzles (20A, 20B), in particular for different distribution pipes (10A, 10B), are offset (O) +/- 20 mm, advantageously +/- 10 mm in the one nozzle row (21).
Arrangement according to any of claims 1 or 2, characterized in that the arrangement comprises two distributor pipes (10A, 10B) each connected to alternate nozzles (20A, 20B) of the one nozzle row (21).
Arrangement according to any of claims 1 - 3, characterized in that the arrangement comprises control means to selectively supply treatment substance from the distributor pipes (10A, 10B).
Arrangement according to any of claims 1 - 4, characterized in that inside diameter of each distributor pipe (10A; 10B) is from 8 mm to 56 mm.
Method for a coating or sizing section of a fiber web production line, in which method a treatment substance, in particular a coating or sizing medium, is applied onto the fiber web by spraying by nozzles (20A, 20B) located in one nozzle row (21) extending in cross-direction i.e. in width direction of the fiber web for spraying the treatment substance onto the fiber web, characterized in that in the method the treatment substance is supplied to the nozzles (20A, 20B) in the one nozzle row by at least two distributor pipes (10A, 10B), and that in the method the treatment substance is supplied by the at least two distributor pipes (10A, 10B), which are each connected to alternate nozzles (20A, 20B) of the one nozzle row (21), alternatingly to the nozzles (20A, 20B) of the one nozzle row (21).
Method according to claim 6, characterized in that in the method the treatment substance is supplied by two distributor pipes (10A, 10B) alternatingly to the nozzles (20A, 20B) of the one nozzle row (21).
Method according to claim 6, characterized in that in the method different treatment substances or components of the treatment substance are be supplied via different distributor pipes (10A, 10B).
Method according to claim 8, characterized in that in the method different substances or components of the substance are selected from the combinations: color substance -hydrophobic substance, one color substance - another color substance, substances with different viscosity and solids content.
Method according to claim 6, characterized in that in the method different amount of the treatment substance is supplied by different distributor pipes (10A, 10B).