SE451381B - DEVICE FOR DRYING A RANGE OF MOVEMENT - Google Patents

Description

15 20 25 30 35 451 381 2 quartz plate in the vicinity of the moving web being dried. The heating modules or housings have a sufficient mounting gap, so that air flows through the gaps to hit the moving web and increase the drying effect.

Research, Inc. of Minneapolis, Minnesota manufactures a high density radiant heater for tubular quartz lamps with tungsten filament. A clear quartz window encloses the lamps to prevent the workpiece or material being cooled from convection cooling by the heater's air cooling.

When achieving an efficient drying unit, the environmental conditions, for example in a paper machine, are of course of great importance. Thus, a drying unit is sought which can be easily installed across the width of a relatively large web of paper in motion, for example to provide a number of drying modules which have high intensity and give good effect at low cost, and also to provide a drying device which is easy to maintain and does not malfunction. Malfunctions in such a device are of course very serious in a paper machine, as they may require a shutdown of the entire process.

An object of the invention is to provide an improved device for regulating the moisture profile of a moving web.

This object is achieved with a device for drying a web in motion, which device has an elongate construction part, the length of which is at least equal to the extent of the web in the transverse direction and which carries a plurality of side-by-side drying modules for drying the web, wherein each drying module has a plurality of spaced apart, parallel, elongate heating elements very close to the web and carries a solid barrier between the heating elements and the web, which barrier is substantially permeable to the heat-generating radiation of the heating elements, and which device is characterized in that An air chamber is connected to all the drying modules, that each drying module has air passage means between the air chamber and the heating elements to enable cooling of the heating elements with air from the air chamber, that air cooling means are arranged for supplying cooling air to the air chamber, and that at least an opening is designed in the barrier to with provide air passage from the air chamber over the heating elements to the space between the web and the barrier. from a location near the track.

The invention will now be described in more detail with reference to the accompanying drawings.

Fig. 1 is a perspective view showing a device according to the invention and its installation in a paper machine.

Fig. 2 is an enlarged plan view with some parts broken away and showing a part of Fig. 1.

Fig. 3 is a fragmentary cross-sectional view taken along line 3-3 of Fig. 2.

Fig. 4 is a cross-sectional view taken along line 4-4 of Fig. 2.

Fig. 5 is a plan view showing a heating module portion taken along line 5-5 of Fig. 4.

Fig. 6 is a partial cross-sectional view taken along line 6-6 of Fig. 4.

Fig. 7 is a fragmentary perspective view showing an alternative embodiment of the invention.

Fig. 8 is a fragmentary cross-sectional view, corresponding to Fig. 4, showing the alternative embodiment.

Fig. 1 shows a drying device 10 according to the present invention, which is arranged transversely or in the transverse direction of a sheet of paper 11, the direction of movement of which is indicated by an arrow 12. In the position shown, drying units housed inside the device are very close to the moving web. ll, for example less than 2.54 cm from it. Dotted lines 13 show the device swung away from the web for quick removal of the heat source in the event of a web break and for preventing damage to the individual heating elements.

As stated in the aforementioned U.S. patent application, the dryer has a plurality of individually controlled heating modules, which are arranged side by side across the paper to enable drying of individual zones or parts of the paper with individual specifications. The device 10 has a plurality of drying units 16a-16g with four heating or drying modules per unit. Of course, the number of units 16 can vary according to the width of the web, and the number shown is only an example. Each cover for units 16a-16g has bolts 29a, 29b, which make access to the drying modules easy.

At the ends of the drying device are arranged support means 17a and 17b, which are mounted on each fixed, vertical support 18a and 18b, respectively. A hydraulic drive system 19 is built into each end support 17a, 17b. In operation, the hydraulic drive systems rotate the portion of the drying device over the paper as indicated by the dotted lines 13 away from the paper and back again to a position in the vicinity thereof. This rotation takes place around an elongate structural part, which has a large diameter and has the shape of a circular conduit, which is shown by dotted lines 21. A square part or other equivalent part can also be used. The entire pivotable device is fastened in a cantilevered manner around the construction part, which acts as a headrest for the drying device. The ends of the structural part are thus stored in bearings in the end pieces 17a, 17b.

Each hydraulic unit 19 comprises a cylinder 22, which is attached to the end support at a pivot point 23. The end 24 of the unit 19 is pivotally coupled to the center part 13 of the drying device. Its end 26 illustrates the performed position of the piston.

The hollow part 21 functions not only as a head support for the drying device but also as a conduit for electrical wires inside the device.

Cooling air is provided by an air fan 27, which is connected to one end piece by means of a hose 28. In practice, both end pieces can be used in a suitable manner for introducing air into the drying units 16a-16g. Such side-by-side units form a closed structure which is a continuous main air chamber 30 (see Fig. 4).

Fig. 2 shows the cover 20 of the unit 16g with broken away parts and one of the individual heating modules 31 and a part of another is shown. They are supported by the pivotable construction and are interchangeable to facilitate repair.

The hydraulic assembly 19 is pivotally connected at 24 to an end wall 41 on the center part. The same construction is located at the opposite end 17a.

As described in more detail in the aforementioned U.S. patent application, the modules 31 are supplied with energy and individually controlled by means of conductor pairs 32, 33, etc., which extend from holes 34 in the structural member 21 to the heating module itself. Such conductors have a fairly considerable size, since a typical output power for a single heating module is 24 kw at 480 V.

As will be apparent, in addition to its carrying function, the part 21 has the function of supporting and cooling (via the hole 34) the electrical conductors which supply energy to the drying modules.

To thermally insulate the end supports 17a, 17b, the pivotable center section at each end also has a sheet 42 of insulating material.

Since the center section of the dryer is pivotable, a pair of bearings are provided in the end sections 17a, 17b at 36a and 36b. The bearing is shown in more detail in Fig. 3, where a fixed bearing support is formed by the wall 37 of the end support 17b, which forms mounting blocks 38, to which a bearing bracket 39 is attached. The bearing itself is made of sintered brass, ie a typical sleeve bearing.

Fig. 4 is a cross-sectional view of the entire drying unit and better shows how the device is attached in a cantilevered manner to the main construction part 21. This also provides interchangeable support of the drying modules 31 side by side. Wing-shaped support parts 43 and 44 are welded to the part 21 and extend therefrom. The lower part 44 has a shelf 46, on which one end of a heating module 31 rests. An opposite shelf part 47 is supported by spaced apart holders 48 (shown in broken lines and with broken away parts), which are attached to the wing-shaped holder 43. They are spread, for example, on every fourth unit 16. Between the shelves 46 and 47 there are an open space for quartz lamp heater 51, which are arranged to act on the paper immediately below. Each drying unit contains several 5l quartz lamp heaters. The axes of the heating module heater 51 of the heating module 31 coincide with the direction of movement 12 (Fig. 1) of the web. The lamps are supplied with energy via the conductors 32 and connections 52 and 53 connected via the heaters 51. A third conductor 35 forms a safety ground.

The upper part of each drying module consists of a perforated plate 54 with a number of holes 55 (see Fig. 2), which allows air to enter a pressure chamber 56. The air is of course supplied by means of the fan system via the main air chamber 30.

The bottom side of the chamber 56 is formed by a ceramic disc or plate 57 with slits, which is better shown in Fig. 5. The number of slits is approximately equal to the number of quartz lamp heaters. The plate 57 is supported inside the rack of the drying module by means of ceramic locking blocks 59 and 61. Both these blocks and the plate itself can be made of such materials as alumina.

Air is captured by articulated flanges 49 and 50 (see also Fig. 2), which conduct air to both ends of the quartz heaters 51, as shown by arrows. The ends of the lamps 51 constitute the first point where faults can occur and must therefore be kept cooler than the main part of the lamps. The hinge flanges ensure a suitable air flow.

A quartz plate 60 closes the bottom of each heating module 31. The plate is divided into two parts 60a and 60b, as best shown in Fig. 6, a slot 65, which is parallel to the heating elements 51, extending along the center line of the plate 60. Since the plate 60 is held only at its ends by means of U-shaped end pieces 62 and 63, as shown in Fig. 4, slits 66 are formed between plates of adjacent heating modules. The slots 65 and 66 allow the cooling air to flow into the space between the sheet material 11 and the plate 60 and then flow out at the front and rear of the modules 31, as indicated by arrows in Fig. 4.

As specifically shown in Fig. 4, an optical coating 64 may be applied to either side of the quartz glass plate 60 to eliminate or reduce the amount of visible light.

It is to the benefit of staff working nearby and who would otherwise be adversely affected or bothered by such light. Although only one centerline slot 65 is shown in the plate, depending on the application, more slots of greater or lesser width may be used to provide adequate airflow and back pressure.

Through the above, several benefits are obtained. Cooling air outflow from the quartz lamps is achieved and at the same time the outflowing air is used to produce relatively cold air between the moving path and the heating modules. In other words, relatively cold air is provided between the paper and the heating module, since, as shown in Fig. 6, the air circulation continuously sweeps away moisture air from the surface of the web 11 which is dried via the slot 65 in the quartz plate 60 and the side slots 66. protective effect by keeping the web away from the hot heater, thereby reducing the risk of fire.

The glass plate prevents the paper or web material from hitting the heating elements, which, depending on the type, do not have very high mechanical strength. Finally, back pressure is provided for the chamber 56, whereby a uniform distribution of air to all the modules 31 is obtained.

Depending on the application, for example, when the heating elements do not need to be shielded from the glass plate, it can be completely dispensed with to enable free air flow from the quartz lamps to the paper sheet.

Fig. 6 shows a cross section of the heating module with its upper perforated plate 54, which lets air into the chamber 56, which air after equalization in the chamber flows through all the slots 58 in the ceramic plate 57. In fig. 6 shows a plurality of quartz heating tubes or lamps 51, which are slightly offset from the slots 58, so that they are not hit by a direct air flow. This displacement also prevents radiant energy from being transmitted in the "line of sight" through the slots to the chamber 56. This air naturally causes cooling of the heat casings, which due to being made of quartz do not absorb any major amount of radiant energy. but which absorb a sufficient amount to require cooling.

Figures 7 and 8 show an alternative embodiment of the heating elements, which are now denoted by 51 '. As mentioned in connection with Fig. 4, the hinge flanges 49 and 50 are used to divert air to cool the ends of the heating elements. Due to the high temperatures involved, it has been found that the cooling of these parts of the heating elements is critical. As shown in Fig. 4, the heating elements are enclosed in box-type casings, which is the manufacturing standard.

However, as shown in Fig. 7, these housings have now been eliminated, leaving only the clamped flat ends 67 of the heating elements. These ends are held by clamps 68.

Extending from the ends are electrical conductors 69, which are shielded by insulating sleeves 71.

For example, the air flows from a hinge flange, as shown by an arrow 72. It is believed that a Venturi type effect increases the airflow or volume of airflow due to the constriction caused by the cylindrical portion of the tube 51 'relative to the compressed, flat portion 67. The critical end part of the heating element is thus cooled more efficiently.

Since no end caps of the standard type are used, the ends 67 are now almost completely exposed to the cooling air. The clamps 68 cover only a small part of the surface of the ends 67 in order to obtain better cooling.

Another modification in the embodiment of Figs. 7 and 8 consists, as best shown in Fig. 8, in that the insulating plate 57 of Fig. 6 is modified to eliminate the slots 58 and provide a solid barrier 57. '.

As a result, substantially the entire air flow from the chamber 30 (see Fig. 4 which extends over the entire closed structure) is forced to flow via the hinge flanges 49 and 50 first over the ends 67 of the heating elements 51 'and then over the elements themselves.

As stated above, the quartz protection plate 60 naturally has slots 65 and 66 (see Fig. 6) to allow cooling air flow into the space between the paper and the plate 60.

Since the plate 57 'is now solid, the pressure chamber 56 according to Figs. 4 and 6 can be eliminated. Alternatively, the plate 54 may be solid without holes 55.

The drying unit thus has a very simple construction as a result of the use of a construction part 21, which supports the rest of the drying device arranged in a cantilevered manner. Only by opening one of the covers 20 and removing the electrical connections can each individual drying module 31 be quickly removed. Since the individual quartz heat lamps are held at each end by means of clamps, ß- “I can easily remove them when the heating module is outside the stand. Finally, the air circulation through the heating modules and the rest of the drying device serves to equalize temperatures, thereby preventing the occurrence of hot spots, and to generally extend the service life of all components.

Claims (5)

10 15 20 25 30 451 381 10 PATENT REQUIREMENTS A device for drying a web (11) in motion, which device has an elongate structural part (21), the length of which is at least equal to the extent of the web in the transverse direction and which carries a plurality of side-by-side drying modules (31) for drying. of the web, each drying module having a plurality of spaced apart, parallel, elongate heating elements (51) very close to the web and supporting a solid barrier (60) between the heating elements and the web, which barrier is substantially permeable to the heat generating elements of the heating elements. air chamber (30) is connected to all drying modules (31), radiation, characterized in that each drying module (31) has air passage means (49, 50, 55, 58) between the air chamber (30) and the heating elements (51) for to enable cooling of the heating elements with air from the air chamber, that air cooling means (27, 28) are arranged for supplying cooling air to the air chamber (30), and that at least one opening (65) is formed in the barrier (60) for allowing air passage from the air chamber (30) over the heating elements (S1) to the space between the web (II) and the barrier (60). Device according to Claim 1, characterized in that the opening formed in the barrier (60) is a slot (65) parallel to the heating elements (S1). Device according to claim 2, characterized in that the barrier (60) is only held at its ends to form an additional slot (66) for air flow between adjacent drying modules (31). Device according to claim 1, characterized in that the heating elements are in the form of glass tubes (51 ') with clamped, flat ends (67), from which electrical conductors (69) extend and on which fastening clamps (68 ) are fixed, the flat ends and the fastening clamps allowing free flow of cooling air for cooling the glass tubes. 5. A device according to claim 1, characterized in that the barrier (60) has a coating (64) for filtering out visible radiation. . ... 1- »N -...-.-... 4. nn ~.» 4 “4 ~ .._ w. ~.». ~ M_-w_- | _ falun- ..