FI66447B - MEDELST AONGA UPPVAERMD TORKCYLINDER - Google Patents

Description

1 66447

STEAM HEATED HEATING CYLINDER I - HEDELST ÄNGA UPPVÄRMD TORKCYLINDER

The invention relates to a steam-heated drying cylinder having a cylindrical jacket with a flange formed at each end for attaching the cylinder head, and in which a thermal insulation layer 1 is arranged in the region of the flanges on the inner surface of the drying cylinder.

10 Especially in high-speed paper machines, where the web is dried with rotating steam-heated drying cylinders, the undesired effect is that the web dries from the edges faster than the rest of the web, which can lead to creases and web tears. As a result, over-stretched and over-stretched edges are of poorer quality than the rest of the track and also cause difficulties and wreckage during polishing and pre-processing. Efforts have been made to eliminate this effect by spraying water on a drying track, however, technological success has been limited and the need for energy for drying has increased as a result.

One reason for the drying of the edges is certainly that the circulation of air in the edge area is more efficient.

It is known from U.S. Pat. No. 3,065,552 to seek to eliminate over-drying of the edges by forming a thermal insulating layer on portions of the cylindrical inner sheath surfaces. However, this measure is not sufficient, especially when the width of the paper web is only slightly smaller than the length of the drying blade 30.

The invention is based on the object of finding even more effective measures to avoid over-drying of the edges of the web and thereby to improve the quality of the paper, to reduce the proportion of wreckage and to reduce the amount of waste. In this case, the cylinder must be as narrow as possible in order to dry a track of a certain width. In addition to the lowering of the drying cylinder, this also has the advantage that the override ropes can be arranged close to the paper web, as a result of which the overrunning of the paper web 2 66447 takes place more easily, faster and more safely after the interruption.

This object is solved in that the insulating layer is arranged on the lower end surface 11e of each flange, i.e. in the area where the cylindrical part of the sheath becomes a cylindrical part of the flange. Preferably, an adhesive layer of insulating working material is used. The inventor has stated the following: The known effect of air circulation in the edge · 10 region is, however, correct. However, there are two other effects: On the other hand, heat can flow axially in the cylinder shell from the hotter edge, which does not transfer any heat at all, to the edge of the paper that uses the heat of vaporization. On the other hand, the capacitor ring 11a has a considerable insulating effect in the cylindrical part 15 of the jacket, which is missing from the inner end surface of the flange, since this area already protrudes from the condenser ring. It is therefore not advisable to fit an insulating layer at all to the blade-like part of the jacket. However, in the part of the jacket which rises from the condensate 1, but the full thickness of the flange has not yet been reached, the thermal resistance is small because on the one hand the condensate 1 von has no thermal resistance and on the other hand the wall thickness is smaller than in the outer flange area.

25 It is now not necessary to attach an insulating layer to all shrink cylinders in a curved or rounded other turn area between the jacket and the flange. A significant improvement is obtained if only a part of the cylinder is provided with an insulating adhesive layer. Especially if the insulating layer 30 is made thick enough, it is sufficient if only 1/3 or less of the cylinder is insulated in the edge area to compensate for the edge effect.

As the web shrinks in width during drying, the position of the web edge 35 with respect to the width of the cylinder changes. To take account of this effect, it is expedient in each case to allow the insulating layer to extend into the cylindrical part of the flange (at the beginning of the drying part) or into the cylindrical part of the jacket (at the end of the drying part). When the right material for the insulation is selected, it also has a condensate effect outside the condensate 11, as the thermal conductivity of the material is only a fraction of the thermal conductivity of the condensate 11.

5 If an adhesive layer with a very low thermal conductivity is selected, an insulating effect of more than 2 mm thick condenser can be obtained with a layer thickness of 0.5 mm.

10 However, since it is cheaper to place the insulation on only a few cylinders, a layer of adhesion of considerable thickness to these few cylinders, e.g. up to 5 mm, can be chosen to compensate for the drying of the edges y 1 in other cylinders. At this thickness, the insulating effect is already so great that it is hardly appropriate to go even thicker.

If large layer thicknesses are selected, then it is appropriate to form these as a "mat" or "mat" and to glue or vulcanize the area of the cylinder to be insulated.

In a very preferred embodiment, the insulating adhesive layer is brushed from the curable working medium. In this case, it is possible to use self-curing multicomponent-25 active compound mixtures or to use softened solids which harden due to evaporation of the solvent. Applying the adhesive in a pasty state is particularly suitable in the case of smaller layer thicknesses or layers which, in addition to covering the area of change between the jacket and the flange, must extend into the cylindrical jacket and / or flange area.

The invention is described in more detail with the aid of Figures 1-3. In this case, all three images show a partial cut-off of the head of the cylinder with a different paper web width.

On the right, the cylinder head associated with the flange is not shown because it has no effect on the object of the invention.

Fig. 1 shows a wide path extending into the cylindrical part of the flange.

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Fig. 2 shows a track of medium width, which extends only to the other 11 μm between the cylinder liner and the flange.

Fig. 3 shows a narrow path which ends in the blade-like part of the cylinder shell.

The three figures show a cylindrical part of the valve 1 with a conversion area 2 into a flange and a cylindrical flange 10 3. Notice the insulating adhesive layer k and the paper web 5 passing over the cylinder and the condensate ring 7. Curve 6 shows the dry new distribution in the web at the machine end if not the adhesive layer according to the invention is used.

15 In all three cases, the y1 <drying on the edge a of curve 6 1uee11 a can be clearly observed (low height of the curve means lower final moisture).

In Figure 1, the paper web 5 extends far into the pointed flange portion of the sheath core. In this case, in particular, other turns occur between the cylinder liner 1 and the flange part 3. At the very edge, the humidity of the track may possibly increase slightly again when going to the right (see curve 6), depending on the respective flap height and axial heat radiation.

25

In this case, the moisture profile can be corrected by the insulation of the inner cylinder wall.

Figure 2 shows a track of medium width which extends only between the area of change between the jacket 1 and the flange 3. Curve 6 shows a very strong over-drying in the edge area of the track 5. This overgrowth can be compensated by an insulating adhesive layer 11a extending over and over area 2 and partially Ia i ppa-a1ueelie 3.

The three figures 1-3 can also be viewed as three successive steps in the drying process of the paper web during drying in the multi-cylinder drying section. In this case, Fig. 1 shows a non-shrinking track width at the beginning of drying, Fig. 2 a partially shrinking track width in the middle area of the drying section and Fig. 3 would shrink the known track width at the end of the drying section.

It is now possible to vary the width of the insulating layer from the beginning to the end of the drying section in the width direction of the web, in accordance with the proposal of Figures 1-3, in order to achieve complete compensation for the drying effect. In practice, however, for the vast majority, it is sufficient to apply an insulating layer of average width to all the cylinders, e.g. as proposed in Figure 2. Curve 6 then - using the invention - becomes a straight (horizontal-1 5 s line) line.

Claims (2)

6 66447 A steam-heated drying cylinder, comprising a cylindrical jacket (1) having a flange (3) formed at each end for attaching the cylinder head, and in which a thermal insulation layer (4) is provided on the inner surface of the drying cylinder in the region of the flanges (3). that the insulating layer (k) is arranged on the inner end surface 11e (2) of each flange (3). Shot blade according to Claim 1, characterized in that the layer also extends into the cylindrical part of the flange (3). *