Patent Application
20120125555
The invention relates to a device for producing a pulp web, such as a paper, board, or tissue web.
In the production of pulp webs, there is generally the problem that the pulp web, which is sometimes very damp during the production process, has to be dried gently in order to obtain the desired paper quality. This is why dryer sections are used with a plurality of heated drying cylinders arranged in one or two rows on which the paper web rests, where the hot surfaces of the drying cylinders cause the water in the paper web to evaporate slowly. Here, however, there is the problem on the one hand that the still very damp paper web sticks slightly to the surface of the drying cylinders, particularly at the desired fast machine speed, and the overall length of the production device or production machine is greatly extended by the large number of drying cylinders arranged one after the other in a row.
In view of this problem area, impingement drying devices were suggested in the state of the art (see for example DE 199 44 266 A1, EP 1 156 155 A2, DE 10 2007 038 133 A1 or DE 10 2007 026 931 A1), where an impingement dryer with a blower hood is provided to apply a dry medium, for example hot air, to the pulp web in order to remove more water at times from the damp pulp web.
As a result of the invention, a device is created for producing a pulp web which allows efficient drying of the pulp web while requiring less installation space.
This is achieved by means of a device with the characteristic features in claim 1. Further embodiments of the invention are described in the dependent claims.
As the two impingement drying units lie adjacently opposite one another according to the invention, that is to say with the front sections adjacent to one another and facing one another, respectively, where their longitudinal axes—either essentially parallel or essentially at an angle of 90° to one another for example—extend at an angle of approximately 45° to the horizontal plane, the installation space, which is generally available vertically above and below the device, and the horizontal installation space are used uniformly in the vertical plane upwards and downwards and in the horizontal plane. In addition, web transfer from the first to the second drying unit can be effected very gently in the variant with the longitudinal axes running in parallel to one another. In addition, it is possible to receive the web very gently with the front impingement drying unit in the transport path (in which the impingement drying device is located) by placing this front impingement drying unit in the transport path on a slant, e.g. in the direction of the transport path (=to the rear); here the pulp web is generally fed horizontally from a preceding device in the transport path to the impingement drying device so that there is an obtuse angle of 135° facing to the rear between the horizontally fed pulp web and the longitudinal axis of the front impingement drying unit in the transport path on account of the essentially 45° angle of its longitudinal axis, and this obtuse angle does not cause any severe deflection of the pulp web. In this case, the rear impingement drying unit in the transport path slants accordingly by 45° in the opposite direction to the transport path (forwards) or by 45° in the direction of the transport path (to the rear); in the former case, web transfer can be effected particularly gently; the pulp web is generally carried onwards essentially horizontally by the impingement drying device so that there is also an obtuse angle of approximately 135° between the longitudinal axis of the rear impingement drying unit in the transport path if this is slanting forwards and the pulp web that is carried onwards horizontally. The first and the second slanting impingement drying units and their slanting longitudinal axes are essentially on a vertical plane; the same applies to any further drying units that are arranged at a corresponding slant and follow the first and second impingement drying units.
According to the invention, the pulp web is also supported in the area of the impingement surfaces on one side or only from one side by the corresponding supporting fabric of the respective impingement drying unit, which achieves effective drying because the impingement medium impinges directly onto the pulp web. Here, for example, the impingement dryer in each of the impingement drying units is directed towards the side of each of the two impingement surfaces facing away from the supporting fabric in each case.
As described above, the impingement dryer of the respective impingement drying unit can have a hood mounted above the respective impingement surface in which an impingement medium, in particular hot air for example, is blown onto the pulp web supported by the supporting fabric. Hoods of this kind can be provided per impingement surface on both sides of the pulp web so that impingement medium can be applied to both of its sides. The impingement dryer is designed preferably in such a way that the impingement medium is applied to at least the sides of all impingement surfaces that are not covered by the supporting fabric because greater efficiency is achieved if the impingements medium impacts the pulp web directly than if there is still a supporting fabric in between.
In addition, the respective impingement dryer can be designed in such a way that the impingement medium is also applied to the side of the pulp web that is covered by the supporting fabric; if the supporting fabric is completely closed, the effect is then practically the same as that of a drying cylinder (only heat transfer to the pulp web); if the supporting fabric has holes or perforations, there are also convection effects on the side of the impingement surface covered by the supporting fabric.
The impingement drying device according to the invention can have several pairs of first and second impingement drying units that are arranged in succession in the direction of the transport path of the pulp web and adjacent to one another. In a preferred embodiment, the impingement drying device has a further one to three impingement drying units in addition to the first and second impingement drying units, where the longitudinal axes of all impingement drying units run essentially parallel to one another and the longitudinal axes of the top impingement drying units run essentially in parallel to one another and the longitudinal axes of the bottom impingement drying units run essentially parallel to one another with an angle of approximately 90° between the longitudinal axes of the top and the bottom longitudinal axes (arrows nested inside one another). If the first impingement drying unit in this case is the foremost of the impingement drying units in the transport path, the respective uneven (e.g. the third and/or fifth) impingement drying unit again also extends in the same way as the first; this means that the front sections of the first and every other impingement drying unit point in the same direction in relation to the respective longitudinal axis in each case. In a preferred embodiment, the front section of all uneven impingement drying units are arranged essentially on the same vertical level; the same also applies preferably to the front sections of all even impingement drying units.
The impingement surfaces of the impingement drying units preferably run symmetrically to their respective longitudinal axis. The impingement surfaces can be shaped to be level, but they can also be curved, particularly in a convex curve. Furthermore, the impingement surfaces can extend in parallel to the longitudinal axis of the respective impingement drying unit; if the impingement surface is curved, the tangent at the apex of the impingement surface can run in parallel to the longitudinal axis in this case. The impingement surfaces and their respective apex tangents extend at an angle of less than 90°, advantageously less than 45°, preferably less than 30°, especially preferably less than 15°, in relation to their respective longitudinal axis.
It is particularly preferable if the impingement drying device is arranged immediately after a press in the device because the pulp web has a high water content immediately after passing through the press so that impingement drying there can be utilized to particularly good effect. The impingement drying device or an additional impingement drying device, which is designed according to the invention, is arranged accordingly immediately after a coating head, which treats the paper with some kind of media, such as size or impregnating material, so the paper therefore also has higher wetness again.
In a preferable embodiment of the device according to the invention, the respective impingement drying device is followed immediately by drying cylinders arranged one behind the other in a horizontal row (single-row design) or in two rows one above the other, each arranged horizontally one behind the other (two-row design).
On the supporting fabric side there may also be suction devices, also combined suction/blow devices, in order to hold the pulp web closely on the supporting fabric, where suction devices and blow devices can be arranged alternately, for example, in the suction/blow device in the pulp web longitudinal direction.
Moreover, the respective impingement drying unit can be equipped with pulp web deflection rolls that have a perforated roll shell and to which suction is applied. Suction through these rolls can be applied either indirectly via a suction box or directly through the roll shaft.
In the following, the invention is explained on the basis of embodiment examples and referring to the figures. In the drawing:
The same reference numerals are used in the figures for the same components.
In the device 1 according to the invention for producing a pulp web 1, as shown in
The device 1 has an impingement drying device 5 located in the transport path Tw, which in turn has: a first elongated impingement drying unit 7 and a second elongated impingement drying unit 9 adjacent to the first. Each of the impingement drying units 7, 9 has two impingement surfaces 11, 13 and 15, 17, respectively, which are arranged on opposite sides of the longitudinal axis L of the corresponding impingement drying unit 7, 9 and each of which has its own supporting fabric 19, 21 that supports the pulp web 3 from one side only. The supporting fabric 19, 21 of the respective impingement drying unit 7, 9 is guided over four respective deflection rolls 23′, 23, 25 and 27′, 27, 29 in a rectangular shape in each case, where this rectangle is formed by two triangles with the same base side and whose apexes point in opposing direction (kite shape).
Both impingement drying units 7, 9 have a front (end) section 31 and 33, and a rear (end) section 35, 37, respectively, viewed in their longitudinal direction L in each case, where the front sections 31, 33 face one another and are mounted adjacent to one another, respectively, and at approximately the same height, which also corresponds approximately to the height of the horizontal elongation or longitudinal elongation (longitudinal axis VL) of the device 1. In the bottom impingement drying device shown in
In this kite shape formed by deflection rolls 23′, 23, 25 and 27′, 27, 29, respectively, the supporting fabric 19 and 21 of the first and second impingement drying unit 5, 7, respectively, circulates in a largely convex shape, i.e. there are only convex deflection points apart from the straight sections between the deflection rolls 23′, 23, 25, 27′, 27, 29, and no concave sections.
In addition, each of the impingement drying units 7, 9 has an impingement dryer 39, 41 each with four bottom dryers 39′, 39″, 39′″, 39IV and 41′, 41″, 41′″, 41IV, respectively. Here, one of the bottom dryers 39′, 39″ and 41′, 41″, respectively, is each arranged directly opposite the side of each impingement surface 11, 13 and 15, 17, respectively, facing away from the respective supporting fabric 19 and 21, respectively, where the bottom dryers have a hood inside which an impingement medium (hot air) can be applied directly to the pulp web 3 in the area of the impingement surface 11, 13, 15, 17.
On the side of each impingement surface 11, 13, 15, 17 facing the supporting fabric 19 and 21, respectively, one of the bottom dryers 39′″, 39IV, 41′″, 41IV is mounted with a hood inside which the impingement medium can be applied to the pulp web 3 indirectly through the supporting fabric 19, 31 in the area of the impingement surface 11, 13, 15, 17. If the supporting fabric has a closed design here, e.g. in the form of a non-perforated plastic belt or a non-perforated metal strip, the impingement medium only effects heating of the supporting fabric 19, 31 so that drying of the pulp web 3 is caused by heat conduction only. In a preferred embodiment, the respective supporting fabric 19, 31 is perforated so that the impingement medium can also act on the pulp web 3 directly through the supporting fabric 19, 31 in places; however this direct action in places should be understood as being indirect through the supporting fabric within the context of the invention.
The longitudinal axis L of the first impingement drying unit 7 and the longitudinal axis of the second impingement drying unit 9 are arranged essentially parallel to one another and at an angle of inclination α of 35°-55°, preferably 40°-50°, more preferably approximately 45°, in relation to a horizontal plane HE. The first and the second impingement drying units, 7, 9 are arranged, as described above, with their front sections 31, 33, viewed in their longitudinal direction L, facing one another and adjacent to one another, respectively, where they extend from their respective front section 31, 33 in their respective longitudinal direction in opposite directions (both vertically and horizontally). In this case, the bottom, first impingement drying unit 7 in
The rear deflection roll 25 and 29, respectively, viewed in longitudinal direction L of the respective impingement drying unit 7, 9, is designed as a suction roll, where suction can be applied to the inside by means of an external suction box 25′, 29′. Suction can also be applied to the suction roll directly via a hollow suction roll shaft. The respective supporting fabric 19 and 21, respectively, of the first and second impingement drying unit 7 and 9, respectively, runs in a convex arrangement in the transport path between the two respective impingement surfaces.
The device 1 also has a press section 43 with a split press 45, which contains two press rolls 49, 51 facing one another and forming a press gap 47 in between. The damp pulp web 3 is guided through the press gap 47 and the moisture is pressed out as a result. Immediately after it the paper web 3 is guided to the first impingement drying unit 7 of the impingement drying device 5. The transfer point to and point of reception 53 at the first impingement drying unit 7 are located in the unit's front section 31, right at the front deflection roll 23 which has a suction device exactly at the transfer point 53 in order to hold the pulp web 3 securely on the deflection roll 23 by suction.
The pulp web 3 runs successively through the impingement surfaces of the first impingement drying unit 7 and reaches a release point 55 of the first impingement drying unit 7 where the pulp web 3 is carried away from the first impingement drying unit 7; this release point 55 is also located in the front section of the first impingement drying unit 7.
The reception point 57 at which the pulp web 3 enters the second impingement drying unit 9 lies immediately adjacent to the release point 55 of the first impingement drying unit 7, in its front section 33, formed in this case at the front deflection roll 27′, which is fitted for this purpose with a suction device at the reception point 57. The pulp web 3 then runs successively through the impingement surfaces 17, 15 of the second impingement drying unit 7, to then be transferred at a release point 59 also located in the front section 33 of the second impingement drying unit 7, to a drying section 61 of the device arranged immediately following it.
In the section between the front deflection roll 27′ and the subsequent middle deflection roll 27 in web running direction a suction device in the form of a suction box 63, 65 is arranged on the side of the respective supporting fabric 19, 21 facing away from the pulp web 3 with which suction is applied to the pulp web 3 in the direction of the supporting fabric 19 and 21, respectively, assigned in each case in order to stabilize the passage of the web.
The drying section 61 has a plurality of drying cylinders 67 arranged one behind the other in a single row in the horizontal plane along the longitudinal axis VL, between which deflection rolls 69 are arranged underneath in a row parallel to the row of drying cylinders. The pulp web 3 is guided alternately in a meandering path over the drying cylinders 67 and the deflection rolls 69. The drying section 61 is divided, for example, into several drying groups, where
Groups with two rows of drying cylinders arranged parallel to one another may also be mixed with single rows of drying groups.
The impingement drying device according to the invention, for example the impingement drying device 5 described above on the basis of
In the embodiment shown in
The third impingement drying unit 73 is arranged immediately adjacent to the second impingement drying unit 9; it has an extended design, where its longitudinal axis L runs parallel to the longitudinal axes L of the first and second impingement drying units, 7, 9; it extends from a front (end) section 77, slanting downwards and to the rear (in the direction of the transport path Tw); its front section 77 lies on approximately the same height level as the front sections 31, 33 of the first and the second impingement drying units 7, 9.
The fourth impingement drying unit 75 is arranged in the transport path immediately adjacent to the third impingement drying unit 73; it has an extended design, where its longitudinal axis L runs parallel to the longitudinal axes L of the first to the third impingement drying units 7, 9, 73; it extends from a front (end) section 79, slanting upwards and forwards (in the direction of the transport path Tw); its front section 79 lies on approximately the same height level as the front sections 31, 33, 77 of the first to the third impingement drying units 7, 9, 73.
The third and the fourth impingement drying units 73, 75 have the same individual components as the first and second impingement drying units 7, 9, which means that each have their own supporting fabric 81, 83 that runs along a rectangular loop in a kite shape defined by deflection rolls 85′, 85, 87, and 89′, 89, 91, respectively; in addition, they each have two impingement surfaces 93, 95 and 97, 99, respectively, and one impingement dryer 101, 103 which acts both on the sides facing away from the respective supporting fabric 81, 83 and on the sides of the impingement surfaces 93, 95 and 97, 99, respectively, facing the respective supporting fabric 81, 83 by having a respective hood arranged there inside which an impingement medium is applied to the respective side of the impingement surfaces 93, 95, 97, 99.
In its front section 77, the third impingement drying unit 73 has both a reception point 105 and a release point 107, at which the pulp web 3 is transferred from the release point 59 of the second impingement drying unit 9 directly to the third impingement drying unit 73 and the pulp web 3 is transferred from the third impingement drying unit 73 directly to the fourth impingement drying unit 75, respectively, which is provided with a reception point 109 for this purpose in its front section 79. In its front section 79, the fourth impingement drying unit 75 also has a release point 111 at which the pulp web 3 is transferred from the fourth impingement drying unit 75 and thus from the impingement drying unit 5 to the drying section 61 which follows.
The reception points 105 and 109 of the third and fourth impingement drying units 73, 75, respectively, are also located exactly at the front deflection rolls 85, 89, where these are equipped with a suction device at the respective reception point 105, 109.
At all of the impingement drying units 7, 9, 73, 75 shown in
In
In the embodiment shown in
The first impingement drying unit 7 is arranged immediately after a press section 43 and immediately before a drying section 61 in web running direction (pulp web path).
With regard to their structural details, the impingement drying units 7, 9 are otherwise the same as the embodiments described previously according to
In the embodiment shown in
In a preferred embodiment, the impingement drying unit 5 has an even number of impingement drying units.
Further advantages of the invention are, for example, as follows: as the front section seen in longitudinal direction of the respective impingement drying unit is preferably designed as tapering towards its longitudinal end, the impingement drying units whose front sections face one another can be arranged closely beside one another at the front. Also the rear section of the respective impingement drying unit, viewed in longitudinal direction, preferably has a tapered shape so that it can be accommodated in a space-saving arrangement.
| Number | Date | Country | Kind |
|---|---|---|---|
| A1107/2009 | Jul 2009 | AT | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AT2010/000229 | 6/23/2010 | WO | 00 | 1/16/2012 |
