SK134394A3 - Method of heat-treatment of a fiber product and device for realization of this method - Google Patents

Abstract

A method and an apparatus for treating a fibre product containing a thermocuring binder wherein oppositely directed gas streams are introduced into the fibre product opposites sides thereof in at least one zone from and wherein the gas streams introduced into the fibre product leave the fibre product on the same side as and in zones which are adjacent to the zones into which the gas streams are introduced into the fibre product.

Description

Method of heat treatment of fibrous product vyioníówswc, iohk)

Technical field

The invention relates to a method of heat treating a moving web of directed fibrous material, in which the gas streams are fed back into the fibrous web from opposite sides thereof in at least one gas treatment area.

BACKGROUND OF THE INVENTION

DK patent application no. 2558/78 discloses a curing oven comprising means for passing a stream of hot gas through a mineral fiber web arranged between two gas permeable conveyor belts in a direction perpendicular to the plane of the web.

It is known that the amount of heat that is transferred from the hot air to the heat cured binder contained in the mineral fiber web is proportional to the pressure at which hot air is supplied to the mineral fiber web.

Therefore, attempts have been made to increase the curing capacity of curing ovens of the above type by increasing the air pressure at the inlet side of the web of fibrous material.

In the case of heat treatment of fibrous webs, and in particular of low density fibrous webs, an irregular compression of the mineral fiber web may occur due to an increase in the differential pressure, possibly due to the fact that the mineral fibers are in areas where the relatively low fiber density displaced by high differential pressure and the curing of the binder at this point is then insufficient.

As a result of such compression, an uncontrollable number of cavities can easily be formed in the web of fibrous material, giving the fibrous web an unacceptable appearance and uneven insulating ability.

Published application DE-A-22753 describes a method of the type already mentioned. In this known method, the hot gas streams are fed from opposite sides of the mineral fiber web and the apertures that extend perpendicular to the direction of movement of the mineral web are forced to move parallel to the plane of the web in the direction of movement of the mineral fiber web or opposite. as the gas is discharged from the fibrous web through apertures that extend perpendicular to the direction of movement of the web.

It is stated that the purpose of this forced movement of the hot gas parallel to the plane of the web is to keep the gas in the mineral fiber web as long as possible in order to release as much heat as possible.

The invention is based on the discovery that due to the exceptionally large surface area of the mineral fibers, usually 500 m ² / kg, the temperature of the mineral fibers is almost instantaneously changed as soon as the fibrous web is exposed to hot or cold gas streams. Freto does not need to force these gas streams to remain in the fibrous web for a long time. Contrary to the facts disclosed in DE-A-22753, it has been shown that gases can be allowed to escape immediately after contact with the mineral fibers. That is, the distance that the gases in the mineral fiber web need to cover can be short and that the gases can be supplied under high pressure without compressing the fibers.

SUMMARY OF THE INVENTION

Therefore, the essence of the method. According to the invention, the gas streams are fed into the web from a plurality of separate inlet regions, where the rows extend transversely to the direction of movement of the web and the gas streams are released from the same side from which they are fed through the exit regions.

As used herein, the terms "gas" and "gases" mean any hot gas medium, including water vapor.

The method of the invention is particularly suitable for curing a binder of a mineral fiber product comprising a non-cured thermosetting binder and will be described in more detail below in connection with a curing process in which hot gases are used to cure the thermosetting binder. However, it is to be understood that the method is also suitable for other heat treatment, including cooling, of the mineral fiber product by supplying hot or cold gases to the mineral fiber product.

The method of the invention is particularly suitable for heat treatment of fibrous webs, and the gas flow model obtained in the heat treatment of fibrous webs according to a preferred embodiment of the method of the invention is shown in the accompanying drawings, Fig. 1 is a cross-section of a fibrous web X of the conveyor belts 4 in a plane perpendicular to the plane of the paper. The gas inlet regions 2 that extend and extend in the direction of movement of the fibrous web X are hot gas streams that follow the deviations so as to move parallel to the web of the web, once again deflected to be discharged by the exit regions located next to the air inlet ducts. 2, out of the web X of fibrous material.

The arrangement of the jet models as shown in the figure allows to increase the curing ability by 2 to 3 times compared to curing by means of hot air streams passing through the fiber web.

As mentioned with reference to the drawings, the gas inlet regions and gas outlet regions may be elongated.

It is preferred that the areas where hot air is fed from one side of the fibrous web are located exactly opposite the areas where the gas is fed from the other side, but the two areas can be easily offset. Furthermore, the opposing regions do not necessarily have the same size. Usually, however, at least 25% of the smaller area should be covered by the opposite area.

The pressure difference between the gas inlet region and the adjacent gas outlet region (s) can be produced in various ways. However, it is preferred that a pressure higher than atmospheric pressure in the gas inlet region and atmospheric or lower than atmospheric pressure in the gas outlet region (s) is used. However, it may also be advantageous to use lower than atmospheric pressure in the gas outlet region (s) and atmospheric pressure in the gas inlet region.

It is essential that the differential pressures in adjacent areas are kept within appropriate ranges.

When elongated gas inlet regions extending in the direction of movement of the fibrous web are used, the widths of these regions are preferably greater than or equal to the widths of adjacent gas outlet regions.

The extended gas inlet regions are preferably divided in the longitudinal direction so as to form individual sections and different pressures can be maintained in adjacent sections.

It is advantageous to maintain small pressure differences between the first section in the gas inlet region and the corresponding gas outlet region, as between the following sections and the corresponding gas outlet region (s).

During fibrous exposure to thermal back pressures.

while the nonwoven, in compression.

Heat treatment processes are areas where the density of the fibers is less, at most

It is therefore important to do this relatively to make this initial low differential

Since the gas flow in the regions having a low fiber density is strongest, the curing and the resulting fiber consolidation are achieved very quickly in these regions. In this way, these regions obtain such a high degree of compression resistance of the fibers that increased differential pressures can be used in the following sections without the risk of fiber compression.

The aforementioned increased curing ability is not conditional upon carrying out the entire operation as described above. Therefore, it was found. That enhancement of the curing capacity can be achieved by adapting sections of existing curing ovens, e.g. 20 to 90% and in particular it is preferred that the first half of these% be cured by the method according to the invention.

It has further been found that it may be advantageous to allow the first part of the curing operation to be conducted by conducting heat by supplying heat to the gas-permeable strips by which usually the fibrous webs pass through the curing oven, thereby contacting the strips with the fibrous web surface. Thus, when the initial curing is carried out as described above, and when the formation of said thin surface layers is followed, higher differential pressures can be used without the risk of depressions being formed in the surface of the fibrous web.

According to the two gas is thermally sides.

In the present invention, the fibrous web is preferably permeable webs such as e.g. lamellar processes air streams fed it keeps between the belts, taking from opposing

As used herein, the term mineral fiber means inorganic fibrous mineral products. Examples of these fibers are mineral wool fibers, glass wool fibers and slag fibers.

The process of the invention is suitable for heat treating fibrous webs having densities in wide ranges, but is particularly suitable for treating light products of e.g. mineral fiber webs having a density of up to 7 kg / m ³ , but preferably a density of 15 to 60 kg / m ³ . The fibrous webs may consist of one or more layers of fibers.

FI-B-80102 discloses a method of drying a fibrous web in which the fibrous web arranged between two airtight guide strips is heated by supplying heat to the strips.

GB patent no. 867530 discloses a textile fiber drying apparatus wherein the fibrous web is held loosely suspended in a drying zone and hot air is blown on both sides of the fibrous web by means of slotted nozzles located on opposite sides of the fibrous web.

The invention further relates to an apparatus for carrying out the method described above. The apparatus comprises means for carrying and moving the mineral fiber web between the gas inlet openings disposed on opposite sides of the mineral fiber web and the gas outlet openings, characterized in that the gas inlet openings form a line extending transversely to the direction of movement of the fibrous web and alternate with the gas outlet openings.

According to the invention, each gas outlet channel is preferably connected to at least one gas inlet opening by means of a conduit in which a gas pump and optionally heating means are arranged.

This embodiment allows the gas to flow out of the fibrous product and to be recirculated and optionally re-heated and fed back to the fibrous product to minimize heat loss.

As already mentioned, the method and apparatus of the invention are particularly suitable for curing a continuous mineral fiber web comprising a binder, but can also be used to cure a series of successive individual mineral fiber elements. They can also be used to cure individual elements or their bundles.

Description of the drawings

An exemplary embodiment of the invention is shown in the accompanying drawings, in which: FIG. 1 is a cross-sectional view of a fiber web moved by conveyor belts; FIG. 2 is a vertical section through a preferred embodiment of the device according to the invention; and FIG. 3 is a partial perspective view of the device of the invention of FIG. 2, wherein some parts are in section.

Description of exemplary creation

2 and 3 consists of an upper endless gas permeable belt 10 and a lower endless gas permeable belt 12 which can serve to move the mineral fiber web 14 through the curing chamber 16.

The apparatus further comprises an inlet channel 18 for supplying hot gas. The channel 18 is divided into an upper branch 20 and a lower branch 22. Upper branch. 20 is connected to the upper gas inlet region and is divided into sections 24 by means of longitudinal outlet channels 26 which are open at the ends.

In a similar manner, the lower branch 22 is connected to the lower gas region, which is divided into sections 28 by means of the gas outlet channels 30, which are open at the ends. At the ends, the outlet ducts 24 and 30 are connected to the gas collection areas 32 and 34, which are connected to the outlet duct 40 by means of the connection ducts 36 and 38.

the duct 40 is connected to a burner 43 which can gas to the device 42 and the inlet 18 is made by means of

As shown in FIG. 2, an outlet heater 42 consisting of being used again for heating from the curing chamber 16. Supplying hot gas gas to the inlet duct of the centrifugal blower 44

The device works as follows:

The hot air from the heater 42 is blown through the channel 18 via the blower 44 and branches 20 and 22 into the sections 24 and 28. From there, the hot air passes through the strips 10 and 12 to the mineral fiber web 14 and from there to the adjacent gas outlet channels 26 and 30 the air flow in the form shown in FIG. From the channels 26 and 30, the gas flows to the collecting areas 32 and 34 and through the connecting channels 36 and 38 to the outlet channel 40 and back to the device 42.

From the above description, it is apparent that the hot gas exits the mineral fiber web 14 immediately after introduction, i.e. the operation can be performed using small pressure differences between the sections 24, 28 and the gas outlet ducts 26 and 30. Therefore, the device allows efficient operation. heat treating the mineral fiber web 14 without the risk of forming a recess in the surface of the fibrous material of the web.

Claims (13)

PATENT CLAIMS 1. A method of heat treating a mineral fiber web in which oppositely directed gas streams are fed into the fibrous web from opposite sides thereof in at least one gas treatment zone, characterized in that the gas streams are fed into the web from a plurality of separate inlet regions wherein the row extends transversely to the direction of movement of the web and the gas streams are discharged from the same side from which they are supplied by exit regions, which are arranged alternately with the entry regions. Method according to claim 1, characterized in that the gas inlet region and the gas outlet region are elongated. Method according to claim 1 or 2, characterized in that hot gas streams having a temperature higher than the curing temperature of the binder are used for treating the mineral fiber product comprising a thermosetting binder to cure the binder. Method according to claim 3, characterized in that the gas inlet regions through which the hot gas is supplied from one side of the fiber product are located exactly opposite the gas inlet regions through which the gas is supplied on the opposite side. Method according to claim 3, characterized in that the gas inlet regions through which the hot gas stream is fed to the fiber product from one side partially overlap the gas inlet regions through which the hot gas stream is fed from the other side. 6. A method according to claim 5, wherein the area in which the gas inlet region on one side of the fibrous product overlaps the corresponding gas inlet region on the other side constitutes at least 25% of the area of the smaller of the two regions. Method according to any one of claims 3 to G, characterized in that pressure is maintained above atmospheric in the gas inlet regions and atmospheric pressure or below atmospheric pressure in the gas outlet regions. 8. The method of claim 2, wherein the width of the gas inlet regions is greater than or equal to the width of the gas outlet regions. 9. The method of claim 2, wherein the elongated gas inlet regions are divided longitudinally to form separate sections. Method according to claim 9, characterized in that different pressure differences are maintained between the section in the gas inlet region and the adjacent gas outlet region and between the remaining section (s) and the adjacent outlet region (s). gas in adjacent sections. Apparatus for heat treating a moving fiber web (14) with gas streams comprising means (10, 12) for supporting and moving the mineral fiber web between gas inlet openings (24, 28) located on opposite sides of the mineral web (14) The gas inlets (26, 30) are characterized in that the gas inlets (24, 28) are disposed in a line extending transversely to the direction of movement of the fibrous web and are arranged in alternation with the gas outlet openings (26, 30). characterized Apparatus according to claim 11, characterized in that each gas outlet (26, 30) is connected to at least one gas inlet through a conduit (40, 18) in which a gas pump (44) is disposed and optionally heating or cooling means (42). Apparatus according to claim 11 or 12, characterized in that the gas inlet openings (24, 28) are elongated.