EP3069092B1 - Apparatus and process for drying a web of material - Google Patents

Description

The invention relates to a dryer for sheet materials, in particular sheets, films or foils. The invention also relates to a method for drying such flat materials.

From the British patent GB 847,548 a device for treating webs, for example plastic films, is known. The device is intended to heat the web and, in the case of a plastic film, then stretch it, for example, in order to achieve an alignment of the polymer molecules in the web. The device has a plate made of a gas-permeable material such as sintered metal, especially sintered bronze. A treatment gas is conveyed through this sintered material. The web is guided along above the plate and is kept at a distance from the sintered metal plate by the gas flow which passes through the sintered metal. The sintered metal used is said to have a porosity of about 27%.

From the U.S. Patent 5,293,699 a dryer for treating a coated strip of material is known which is provided with numerous guide elements which have a gas guide surface facing the strip of material. The gas guide surface is a side surface of an air-permeable body, which consists for example of sintered metal or porous glass. The material strip is held at a distance above the guide surface by an air flow passing through the gas guide surface.

From the U.S. patent US 5,147,690 Another dryer for drying a liquid film on a substrate web is known. In the dryer, a gas stream is passed onto the film to be dried through filter plates made of porous material. The porous material can be realized by means of slits, nozzles, holes or porous materials.

From the European patent application EP 1 921 407 A2 a dryer for drying bulk goods is known. Air is blown onto the material to be dried using the dryer. This is done through nozzles in a ceramic plate. Instead of a ceramic plate with nozzles, foam ceramic, a metal foam or a sintered material can also be used.

From the U.S. patent application US 2013/0228300 A1 a method for impregnating a continuous paper web is known.

The invention is intended to provide an improved dryer for sheet materials and an improved method for drying sheet materials, with which even extremely sensitive sheet materials, for example very thinly coated plates or sensitive, in particular coated films or foils, can be obtained quickly and in an extremely gentle manner let dry.

According to the invention, a dryer for flat materials, in particular plates, films or foils with the features of claim 1 and a method with the features of claim 8 is provided for this purpose. A porous, gas-permeable metal plate is provided for arrangement at a distance from the flat material to be dried, means for conveying a gaseous fluid through the metal plate and wherein the metal plate consists of a metal foam.

By conveying a gaseous fluid through the metal plate made of porous, gas-permeable metal foam, that is to say open-pore metal foam, an extremely uniform flow distribution of the gaseous fluid on the flat material to be dried can be achieved. By using a porous, gas-permeable metal plate made of open-pore metal foam, above all locally higher flow velocities, which inevitably lead to an uneven drying process of the flat material to be dried, can be completely avoided. Compared to dryers that work with several individual nozzles, the invention enables a uniform flow velocity and uniform flow conditions to be set over the entire surface of the flat material to be dried, so that extremely uniform and material-friendly drying can also be achieved.

According to the invention, the means for conveying a gaseous fluid have suction means for sucking gas from a region between the metal plate and the sheet material to be dried.

Particularly gentle drying can be achieved by sucking in gas from the area between the metal plate and the sheet material to be dried, since no flow is directed at the sheet material to be dried, but only a flow is generated away from the sheet material to be dried. This creates a negative pressure between the flat material to be dried and the metal plate. If necessary, it can be provided that gas flows laterally into the space between the flat material to be dried and the metal plate, which then, in order to achieve a uniform flow distribution, advantageously also flows through a metal plate made of an open-pore metal foam. The negative pressure can also be set so low that only insignificant Flow in quantities of gas and essentially only gases or vapors escaping from the flat material to be dried are extracted.

Regardless of whether gaseous fluid is conveyed in the direction of the sheet material to be dried through the open-pore metal foam or is sucked in from the space between the sheet material to be dried and the open-pore metal foam, the metal plate can be inclined from the metal foam to the sheet material to be dried be arranged. As a result, a gas distribution in the space between the metal plate and the flat material to be dried can be influenced such that the desired flow conditions are present in the space between the metal plate and the flat material to be dried.

According to the invention, the means for conveying a gaseous fluid have at least one flow space which is delimited on one side by a surface of the metal plate, this surface facing away from the flat material to be dried, the flow space having at least one inlet opening and at least one outlet opening for Conveying gas has and is designed to lead the conveying gas past the surface of the metal plate lying in the flow space in order to produce a suction effect through the metal plate.

Through these measures, a suction effect can be generated by means of the so-called Venturi effect. The gaseous fluid, which can be, for example, nitrogen, a noble gas or another suitable gas, is guided past the surface of the metal plate that faces away from the flat material to be dried. A relatively high flow rate is preferably achieved. The gaseous fluid then flows past the many open pores in the open-pore metal foam. This creates a suction effect through the so-called Venturi effect, through which gas, which is located in the space between the metal plate and the flat material to be dried, i.e. the drying space, is sucked out through the pores of the metal foam. This happens evenly over the entire surface of the metal plate, since the metal plate has open pores over its entire surface. In the drying space between the metal plate and the flat material to be dried, essentially constant flow conditions can be generated over the entire surface.

In a further development of the invention, a plurality of flow spaces, each with at least one inlet opening and at least one outlet opening, are arranged in the longitudinal direction of the material to be dried.

In this way, for example, different flow velocities can be set in the flow spaces. For example, the flow velocity in a flow space in which the drying process is only just beginning is set very low in order to treat the liquid or gel-like sheet material in a particularly gentle manner and to draw in only a little gas from the drying space. Alternatively, a very high flow rate can also be set in such a front flow space in order to accelerate the drying process, especially at the beginning. Flow spaces that lie above flat material that has already been pre-dried can then be adjusted in such a way that an ideal negative pressure in the drying space is set for the material to be dried.

In a further development of the invention, the metal plate is arranged above a circulating belt, onto which a liquid material for producing the flat material is applied and which solidifies on the belt.

In this way, when producing films or foils, the liquid material applied to a tape can be dried extremely gently and efficiently as soon as it is applied.

In a further development of the invention, at least one sluice is provided upstream and / or downstream of a drying chamber of the dryer, the sluice having at least one strip-shaped or rod-shaped strip arranged transversely to the longitudinal direction of the flat material to be dried, the flat material being on the strip in the longitudinal direction is moved past, wherein the strip consists of porous, gas-permeable metal foam over at least part of its outer surface facing the sheet material, and wherein means for conveying lock gas through the metal foam in the direction of the sheet material are provided.

The strip-shaped or rod-shaped strip can thus consist of a metal foam strip or also of a tubular rod made of metal foam. In the case of a tubular rod, the lock gas can be introduced into the interior of the rod and then exits to the outside through the metal foam. Areas of the outer surface of the rod that face away from the material to be dried can be sealed. Such sealing can be effected by grinding the metal foam, but also, for example, by applying a sealing compound, for example an adhesive.

In a development of the invention, the metal foam consists of a stainless steel, in particular of chrome-nickel-stainless steel.

By using chrome-nickel-stainless steel, the metal foam can be made very corrosion-resistant and can also be used in corrosive environments. This is also essential so that corrosion products of the metal foam do not fall from the metal foam onto the material to be dried and thereby contaminate it.

In a development of the invention, the metal foam has between 45% and 80% nickel and between 15% and 45% chromium. The metal foam advantageously has carbon, copper, iron, molybdenum, manganese, phosphorus and / or zinc, in each case with a percentage of less than 1%.

In a development of the invention, the metal foam has a porosity of 90% or more.

The porosity refers to the voids in the foam metal. A porosity of 90% means that 90% of the total volume of the metal foam consists of air or cavities and only 10% of solid.

In a further development of the invention, the metal foam has an average pore size in a range between 0.3 mm and 2.5 mm.

The pore sizes of metal foam are more or less statistically distributed, on average they can be between 0.3 mm and 2.5 mm. The average pore size is matched to the desired throughput of gaseous fluid through the metal foam.

A method for drying flat materials, in particular plates, films or foils, is provided, in which at least one metal plate made of porous, gas-permeable metal foam is arranged at a distance from the flat material to be dried and gaseous fluid is conveyed through the metal plate.

By using a plate made of open-pore metal foam, very even flow conditions can be set in an area between the flat material to be dried and the metal plate, that is to say the drying room, which enable very gentle and efficient drying.

In a development of the invention, the sheet material to be dried is guided past the metal plate.

Such a passing of the flat material is particularly useful in the case of sheet-like flat materials, for example films or foils, in order to achieve continuous operation. However, the method according to the invention can also be operated in a so-called batch mode are used, so that the material to be dried is immovably arranged under the dryer. Such a batch operation can be used for research purposes, but also when, for example, coated glass plates are to be dried and a continuous drying operation is not absolutely necessary.

According to the invention, the suction of gaseous fluid through the metal plate is provided from an area between the sheet material and the metal plate.

By sucking gaseous fluid out of the drying room, the flat material can be dried particularly gently and efficiently.

In a further development of the invention, the arrangement of a first metal plate at a distance from a first surface of the flat material and the arrangement of at least one second metal plate at a distance from a second surface of the flat material and the conveyance of gaseous fluid through the first and second metal plates are provided.

In this way, the two opposite surfaces of the sheet material can be dried simultaneously.

In a further development of the invention, contactless drying of the flat material is provided in the area between the two metal plates.

According to the invention, the conveyance of conveying gas is provided along a surface of the metal plate facing away from the sheet material to be dried, and the suction of gaseous fluid through the metal plate by means of the conveying gas which is carried past.

Through these measures, the so-called Venturi effect can be used to suck gas out of the drying room through the pores of the metal foam. The gas is sucked in over the entire surface of the metal plate, so that very even flow conditions are achieved in the drying room.

Further features and advantages of the invention result from the claims and the following description of preferred embodiments of the invention in connection with the drawings. Individual features of the different embodiments and from the individual figures can be combined with one another in any manner without going beyond the scope of the invention.

Fig. 1

eine schematische Darstellung einer Fertigungseinrichtung für bahnförmige flächigen Materialien mit zwei hintereinander angeordneten erfindungsgemäßen Trocknern,

Fig. 2

eine schematische Darstellung eines weiteren erfindungsgemäßen Trockners,

Fig. 3

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners,

Fig. 4

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners,

Fig. 5

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners,

Fig. 6

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners,

Fig. 7

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners,

Fig. 8

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners,

Fig. 9

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners,

Fig. 10

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners und

Fig. 11

eine schematische Darstellung einer weiteren Ausführungsform eines erfindungsgemäßen Trockners.

The drawings show:

Fig. 1

1 shows a schematic representation of a production device for sheet-like flat materials with two dryers according to the invention arranged one behind the other,

Fig. 2

2 shows a schematic representation of a further dryer according to the invention,

Fig. 3

1 shows a schematic representation of a further embodiment of a dryer according to the invention,

Fig. 4

1 shows a schematic representation of a further embodiment of a dryer according to the invention,

Fig. 5

1 shows a schematic representation of a further embodiment of a dryer according to the invention,

Fig. 6

1 shows a schematic representation of a further embodiment of a dryer according to the invention,

Fig. 7

1 shows a schematic representation of a further embodiment of a dryer according to the invention,

Fig. 8

1 shows a schematic representation of a further embodiment of a dryer according to the invention,

Fig. 9

1 shows a schematic representation of a further embodiment of a dryer according to the invention,

Fig. 10

a schematic representation of a further embodiment of a dryer according to the invention and

Fig. 11

is a schematic representation of a further embodiment of a dryer according to the invention.

The schematic representation of the Fig. 1 shows a production system 10 for sheet-like materials, for example film or foil. A flow direction is shown in the Fig. 1 left to right. A film or a release film to be coated is pulled off a drum 12 and guided onto the upper run of a circulating belt 14. An application device 16 for liquid material is provided at the beginning of the upper run of the belt 14. This application device 16 is designed, for example, as a slot nozzle which extends over the entire width of the belt 14. With this application device 16 material for a film to be cast is applied to the band 14, in particular a steel band, and the finished film can then be pulled off at the end of the upper run of the band 14.

The liquid material is applied to the belt 14 and then solidifies or dries in the course of the movement of the belt 14. The liquid material is applied by the application device 16 to the top of the film to be coated, which is arranged between the belt 14 and the application device 16 is. A dryer 18 according to the invention is arranged above the upper run of the circulating belt 14. The dryer 18 has a porous, gas-permeable metal plate 20 made of metal foam, which is arranged at a constant distance above the flat material to be dried, which is in the form of a film by means of the application device 16 on the upper run of the belt 14 or on the top of the film rests. A flow space 22 is arranged above the metal plate 12, which is closed at the top by a gas-impermeable plate and is closed at the sides by means of gas-permeable plates 24, 26. The plates 24, 26 can also consist of open-pore metal foam, but they can, for example, also be simple perforated sheets in order to achieve a uniform flow through the flow space 12.

The plates 24, 26 simultaneously form an inlet opening or an outlet opening for the flow space 22. Gas is introduced into the flow space 22 through the plate 24, and the gas leaves the flow space 22 again through the plate 26. The gas flows within the drying space in the direction of an arrow 28 and thereby flows past the open pores of the metal plate 20. Due to the so-called Venturi effect, a negative pressure is generated within the pores of the metal plate 20, which ultimately leads to the fact that gas is sucked in from a drying space 30 between the metal plate 20 and the flat material to be dried on the upper strand of the belt 14. This gas is then discharged through the plate 26 together with the gas flowing through the flow space 22. Gas is drawn in from the drying chamber 30 over the entire underside of the metal plate 20, so that essentially constant flow conditions are achieved in the drying chamber over the entire length of the metal plate 20. The web-shaped film on the upper run of the circulating belt 14 can thereby be dried very gently and evenly, but at the same time also efficiently and quickly.

In the area of a Fig. 1 Deflection drum 32 arranged on the right for the circulating belt 14, the coated carrier film 12 leaves the circulating belt 14 and is introduced into a floating dryer 34 according to the invention. The floating dryer 34 has at its upstream end a lock with two tubular rods 36 extending transversely to the longitudinal direction of the web-like material to be dried. These rods 36 consist at least in sections of metal foam and serve to lock gas in the direction to promote the web-like material to be dried and thereby prevent ambient gas from being introduced into the actual drying area of the floating dryer 34 downstream of the lock 36. Substantially identically designed locks with tubular rods 36 are also arranged at the downstream end of the floating dryer 34, with a lock with two tubular rods 36 being arranged at the downstream end both above and below the web-like material to be dried.

In the actual drying area 38 of the floating dryer 34, a plurality of flow spaces 40, 42, 44 and 46 are arranged one behind the other, as seen in the direction of flow of the web-shaped material. In the same way, a plurality of flow spaces 41, 43, 45 and 47 are arranged one behind the other opposite the underside of the web-shaped material. The flow spaces 40 to 48 are each delimited by means of a metal plate made of open-pore and thus gas-permeable metal foam towards the web-like material to be dried. In the flow spaces 40, 44 and 43 and 47, gas is conveyed through the respective metal plate in the direction of the web-like material to be dried. This ensures on the one hand that the web-shaped material is held in the middle between the opposing metal plates of the flow spaces 40 to 48. At the same time, the gas is passed over the top and bottom of the sheet material so that it dries. In contrast, gas is drawn off from the flow spaces 42, 46, 41 and 45. As a result, stable flow conditions can be created in the region above and below the sheet material to be dried, since, for example, the gas conveyed through the metal plate of the flow space 40 in the direction of the sheet material is sucked out again through the metal plate of the flow space 42.

On the top and bottom of the sheet material, the flow spaces 40 and 43, through the metal plates of which gas is conveyed in the direction of the sheet material, are offset in the longitudinal direction. In the same way, the flow spaces 41 and 42, through the metal plates of which gas is conveyed away from the web-shaped material, are offset in the longitudinal direction from one another. This is also the case with the flow spaces 44 and 47 or 45 and 46.

The floating dryer 34 thereby makes it possible to dry web material to be dried on both sides. The number of flow spaces at the top and bottom is determined by the belt speed and the solvent content of the applied material. This also applies to further dryers according to the invention with several flow spaces.

Downstream of the floating dryer 34, the web-like material is then passed over a drum 50 and into a first post-treatment device 52 and then also into a second Post-treatment device 54 performed. In the aftertreatment devices 52, 54, the aftertreatment of the sheet material can be carried out using liquid and also gaseous media in order to refine the sheet material. For example, non-contact aftertreatment of the sheet-like material by means of liquid media takes place in after-treatment device 52 and non-contact after-treatment of the sheet-like material by means of hot gas in post-treatment device 54. A course of the web-shaped material within the aftertreatment devices 52 and 54 is not shown for the sake of simplicity. Downstream of the aftertreatment device 54, the dried and thereby finished web-like material 12 is then wound onto a storage drum 56.

The representation of the Fig. 2 shows a further embodiment of a dryer 60 according to the invention. The dryer 60 is similar to the dryer 18 of FIG Fig. 1 constructed, only at the upstream end of the drying room 30 and at the downstream end a lock 62 and 64 are arranged. The locks 62 and 64 prevent ambient gas from entering the drying room 30.

Liquid material is applied to the upper run of the circulating belt 14 by means of an application device 16. The applied liquid material forms a liquid film on the upper run of the belt 14. This liquid film is introduced through the lock 62 into the drying room 30. The drying chamber 30 is bounded at the top by a metal plate 20 made of open-pore and gas-permeable metal foam. Above the metal plate 20, the flow space 22 is arranged, through which, as already shown in FIG Fig. 1 and was explained there with the aid of the dryer 18, gas flows in the direction of the arrow 28. The gas 28 flows past the open pores of the metal plate 20 and thereby sucks gas from the drying space 30 into the flow space 22. The liquid film on the upper run of the belt 14 can thereby be dried uniformly over the entire underside of the metal plate 20 by the drying room and thus gas is extracted from the surface of the liquid film. In the course of the movement of the liquid film together with the upper run of the belt 14, the film thereby dries and, after it has passed the downstream lock 64 of the dryer 60, can be removed from the belt 14 as a dried, stable film 64 and, for example, fed to a post-treatment become. A drying speed can be optimized by adjusting the height of the metal plate 20. A flow velocity and a volume flow in the flow space 22 can be optimized by changing the height of the flow space 22. It can be expedient to optimize the volume flow in, against and across the suction direction through the plate 20.

The locks 62, 64 are designed in the same way as on the basis of the dryer 34 Fig. 1 has been described. The locks 62 and 64 each have two tubular rods 36 through the lock gas is conveyed in the direction of the film to be dried or in the direction of the film 64. The tubular rods 36 each consist of gas-permeable metal foam, so that the lock gas emerges in the direction of the latter at a low flow rate and uniformly over the entire width of the film or film 64. The film or the film is not adversely affected by this, but at the same time it can reliably be ensured that no ambient gas enters the drying chamber 30. The rods 36 can be adjusted in height relative to the belt 14 or the material to be dried in order to adjust the flow of lock gas. A selection of the porosity of the rods 36 also serves this purpose.

The representation of the Fig. 3 shows a further embodiment of a dryer 70 according to the invention. The dryer 70 is a floating dryer and is therefore comparable to that with reference to FIG Fig. 1 explained floating dryer 34 formed. The dryer 70 of the Fig. 3 but has a total of four locks 72, 74, 76, 78, each having two tubular rods 36, which are arranged at a distance from the sheet material to be dried and is conveyed through the lock gas in the direction of the sheet material to be dried. The tubular rods each consist of gas-permeable metal foam. The lock 72 is arranged above the web material 80 to be dried at the upstream end of a first drying chamber 62, the downstream end of which is closed with the lock 74. The lock 76 is arranged at the upstream end of a second drying space 84, which lies between the underside of the sheet material and the metal foam plates of the flow spaces below the sheet material 80. The downstream end of the drying room 84 is closed off by the lock 78.

The web-like material 80 is provided with a coating upstream of the floating dryer 70 by means of an application device 16 and then passed through the dryer 70 without contact and thereby dried on its upper side and on its lower side. A detailed explanation of the individual flow spaces of the dryer 70 is dispensed with here, since they are identical to the dryer 34, which is already based on FIG Fig. 1 was explained.

The representation of the Fig. 4 shows a further embodiment of a dryer 90 according to the invention. The dryer 90 is designed for continuous belt operation and is similar to the dryer 18, which is already based on the Fig. 1 was explained. In contrast to the dryer 18 of the Fig. 1 For example, a metal plate 92 made of open-pore metal foam is arranged at an angle to a flat material 94 to be dried, so that a drying space 96 reduces its height in the direction of movement of the material 94 to be dried. Above the metal plate 92, two flow spaces 98 and 100 are arranged, through which gas opposes the direction of movement of the web-like material 94 is conveyed on the upper run of the circulating belt 14, thereby sucking gas from the drying room 96. Tilting the metal plate 92 makes it possible to set different flow conditions within the drying space 96. A lower vacuum can be set below the flow space 100 than below the flow space 98 in order to influence the drying behavior of the web-like material 94 as it passes through the dryer 90.

The representation of the Fig. 5 shows a dryer 110 according to the invention according to a further embodiment of the invention. The dryer 110 is in the form of a floating dryer and is therefore similar to that already based on Fig. 1 explained dryer 34 formed. In contrast to the floating dryer 34 the Fig. 1 the porous, gas-permeable metal plates 112 of the flow spaces 114, 116, 118, 120, 122 and 124 are arranged at a first distance from the sheet material 108 to be dried. Gas is conveyed through the flow spaces 114, 116, 118, 120, 122, 124 in the direction of the upper side or lower side of the web-shaped material 108 in order to keep it suspended between the metal plates 112. In contrast, gas is extracted from the flow spaces 115, 117, 119, 121, 123 and 125. The porous, gas-permeable metal plates 126, with which the flow spaces 115, 117, 119, 121, 123 and 125 are each closed, are arranged at a second distance from the top or bottom of the sheet material 108, the second distance being greater than the first distance that the porous, gas-permeable metal plates 112 from the sheet material 108 are arranged. With such a measure, the web-shaped material 108 can be reliably held in suspension and thus dried without contact. It can also be seen that the areas of the metal plates 112 are only about half as large as the areas of the metal plates 126. This also ensures reliable drying on the one hand and that the sheet-like material can be reliably held in suspension.

The representation of the Fig. 6 shows a further dryer 130 according to the invention, which is designed as a floating dryer for drying a web-shaped material 132 on both sides. The dryer 130 has a total of 5 flow spaces 134 above the web-shaped material 132 and five identically designed, but arranged below the web-shaped material 132 flow spaces 136, which are each bounded by a porous, gas-permeable metal plate towards the web-shaped material 132 and by the gas in the direction is conveyed onto the web-shaped material 132. The dryer 130 also has four flow spaces 138 which are arranged above the sheet-like material and which are likewise delimited towards the sheet-like material 132 by means of a porous, gas-permeable metal plate. Four flow spaces 140, which are identical to the flow spaces 138, are arranged below the web-shaped material 132. From the flow spaces 138 and 140, gas is drawn off, so that a negative pressure is created between the porous, gas-permeable metal plates of the flow spaces 138 and 140 and the top and bottom of the sheet-like material 132. In the case of the dryer 130, the flow spaces 134 and 136 are arranged exactly opposite one another and the area of the porous gas-permeable metal plates of the flow spaces 134 and 136 is essentially twice as large as the area of the porous, gas-permeable metal plates of the flow spaces 138 and 140. The porous, gas-permeable Metal plates of the flow spaces 138 and 140 are also arranged at a greater distance from the top or bottom of the sheet-like material 132 than the porous, gas-permeable metal plates of the flow spaces 134 and 136. Depending on the type of the sheet-like material 132 to be dried, the level of negative pressure, with the gas is sucked out of the respective drying room and the level of the excess pressure or the flow rate with which the web-shaped material 132 is kept in suspension can be adjusted. Locks 142 are arranged upstream and downstream of the drying rooms of the dryer 130, respectively.

The dryer of the Fig. 5 and 6 can also be arranged and operated vertically, for example for films coated on both sides.

The representation of the Fig. 7 shows a further dryer 150 according to the invention. The dryer 150 is designed as a contactless dryer and a web-shaped material 152 to be dried is passed vertically between two porous, gas-permeable metal plates 154 made of metal foam. Dry gas flows through the metal plates 154 in the direction of the web material 152 to be dried. The drying gas is then sucked out of the drying rooms on both sides of the web material 152 again to the respective upper end of the drying room.

The representation of the Fig. 8 shows a dryer 160 according to the invention according to a further embodiment. A web-like material to be dried is guided in a meandering manner between porous, gas-permeable metal plates 164 and is thus dried on both sides without contact. A deflection region 166, in which the sheet material 162 must be kept in suspension against its gravity, has a curved porous, gas-permeable metal plate made of metal foam 168, through which gas is conveyed in the direction of the sheet material 162, thereby spacing it apart to hold and redirect from the metal plate 168.

The representation of the Fig. 9 shows a further dryer 170 according to the invention according to a further embodiment. The dryer 170 is provided for the so-called batch operation, in which, for example, a coated glass plate 172 to be dried is introduced into a drying room 174, is then completely dried there and only then again is removed from the drying room 174. The drying chamber 174 is delimited on the one hand by the coated glass plate 172 to be dried and on the other hand by a metal foam plate 176. The metal foam plate 176 is arranged to be adjustable in height and can therefore be matched to various flat materials to be dried. A flow space 178 is arranged above the metal foam plate 176, from which gas is sucked off by means of a suction fan 180. Gas flows into the flow space 178 from the surroundings or from a gas source via a heat exchanger 182. A first flow straightener 184 is arranged on the inlet side of the flow space 178, that is to say immediately downstream of the heat exchanger 182, and a further flow straightener 186 is arranged on the outlet opening of the flow space 178. The flow straighteners 184, 186 each consist of open-pore metal foam plates and thereby ensure very uniform flow conditions within the flow space 178. Gas is sucked into the flow space 178 from the drying space 174 via the venturi effect.

The representation of the Fig. 10 shows a further dryer 190 according to the invention according to a further embodiment. The representation of the Fig. 10 is only designed schematically and serves to illustrate a cover 192, which forms a closed space together with a fixed base 194. Within this closed space, on the one hand, the flat material 196 to be dried is arranged, and also a drying space 198, which is delimited on its top by a metal foam plate 200. A flow space 202 is arranged above the metal foam plate, through which gas is passed in order to in turn draw in gases from the drying space 198 via the Venturi effect. The flow space 202 is thus delimited on the one hand by the metal foam plate 200 and on the other hand by a hood 204. There is an intermediate space between the hood 204 and the hood 192, through which in turn gas can laterally enter the drying chamber 198.

The representation of the Fig. 11 schematically shows another dryer 210 according to the invention. The dryer 210 is designed in the manner of a continuous tunnel and has a bent metal foam plate 212 which delimits a drying space above a flat material 214 to be dried. A hood 216 is arranged above the bent metal foam plate 212, which defines a flow space 218 between it and the metal foam plate 212. The hood 216 stands on a solid base 220.

Claims (11)

1. A dryer (18; 60; 90; 170; 190; 210) for flat materials, in particular panels, films or sheets, comprising a porous, gas-permeable metal plate (20; 92; 176; 200; 212) for arranging at a distance from the flat material which is to be dried, wherein means are provided for delivering a gaseous fluid through the metal plate (20; 92; 176; 200; 212), wherein the metal plate (20; 92; 176; 200; 212) consists of a metal foam, wherein the means for delivering a gaseous fluid have at least one flow space (22; 98; 100; 178; 202; 218) which is bounded on one side by a surface of the metal plate (20; 92; 176; 200; 212), wherein said surface is directed away from the flat material which is to be dried, wherein the flow space (22; 98; 100; 178; 202; 218) has at least one entry opening and at least one exit opening for delivery gas, characterized in that the means for delivering a gaseous fluid have intake means for taking in gas from a region between the metal plate (20; 92; 176; 200; 212) and the flat material which is to be dried, wherein the flow space (22; 98; 100; 178; 202; 218) is designed to guide the delivery gas past that surface of the metal plate (20; 92; 176; 200; 212) which is located in the flow space (22; 98; 100; 178; 202; 218), in order to generate an intake action through the metal plate (20; 92; 176; 200; 212).
2. The dryer as claimed in claim 1, characterized in that a plurality of flow spaces (98, 100), each with at least one entry opening and at least one exit opening, are arranged one behind the other in the longitudinal direction of the material which is to be dried.
3. The dryer as claimed in one of the preceding claims, characterized in that the metal plate (20; 92; 200; 212) is arranged above a circulating belt (14), to which a liquid material is applied in order to produce the flat material, said material solidifying on the belt (14).
4. The dryer as claimed in at least one of the preceding claims, characterized by at least one airlock (62, 64) upstream and/or downstream of a drying space (30) of the dryer, wherein the airlock (62, 64) has at least one bar-like or rod-like strip (36) arranged transversely to the longitudinal direction of the flat material which is to be dried, wherein the flat material is moved past the strip (36) in the longitudinal direction, wherein the strip (36), at least over a part of its outer surface which is directed toward the flat material, consists of porous, gas-permeable metal foam, and wherein means are provided for delivering airlock gas through the metal foam in the direction of the flat material.
5. The dryer as claimed in at least one of the preceding claims, characterized in that the metal foam consists of a stainless steel, in particular of chromium-nickel stainless steel.
6. The dryer as claimed in at least one of the preceding claims, characterized in that the metal foam has a porosity of 90 percent or more.
7. The dryer as claimed in at least one of the preceding claims, characterized in that the metal foam has an average pore size ranging between 0.3 mm and 2.5 mm.
8. A method for drying flat materials, in particular panels, films or sheets, comprising arranging at least one metal plate (20; 92; 176; 200; 212) made of porous, gas-permeable metal foam at a distance from the flat material which is to be dried and delivering gaseous fluid through the metal plate (20; 92; 176; 200; 212), characterized by taking in gaseous fluid through the metal plate from a region between the flat material and the metal plate (20; 92; 176; 200; 212), and guiding past delivery gas along a surface of the metal-plate (20; 92; 176; 200; 212) which is directed away from the flat material which is to be dried and taking in gaseous fluid through the metal plate (20; 92; 176; 200; 212) by means of the delivery gas guided past.
9. The method as claimed in claim 8, characterized in that the flat material which is to be dried is guided past the metal plate (20; 92; 176; 200; 212).
10. The method as claimed in claim 8 or 9, characterized by arranging a first metal plate (154) at a distance from a first surface of the flat material and arranging at least a second metal plate (154) at a distance from a second surface of the flat material and delivering gaseous fluid through the first and second metal plates (154).
11. The method as claimed in claim 10, characterized by a contactless drying of the flat material in the region between the two metal plates (154).

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