CZ274094A3 - Heat treatment process of fibrous material and apparatus for making the same - 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

Technical field

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

BACKGROUND OF THE INVENTION

DK-2558/78 discloses a curing oven comprising means for passing a hot gas stream 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 hot air to the heat cured binder contained in the mineral fiber web is proportional to the pressure at which hot air is fed 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 increase in differential pressure may result in irregular compression of the mineral fiber web, which compression is likely due to the fact that the mineral fibers are

2 in areas where the relatively low fiber density is displaced by high differential pressures and curing of the binder is insufficient at this point.

As a result of these compressions, an uncontrollable number of cavities can easily be formed in the fiber web, giving the fiber web an unacceptable appearance and unequal insulating ability.

DE-A-22753 discloses a method of the above type. In this known method, the hot gas streams are fed from opposite sides of the mineral fiber web and by slotted openings that extend perpendicular to the direction of movement of the mineral are forced to move parallel to the plane of the web. moving the mineral fiber web or in the opposite direction before the gas is discharged from the fibrous web through slotted openings that pass through the chamber 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 mineral fibers, usually 500 m ² / kg, there is an almost instantaneous change in temperature of the mineral fibers as soon as the fibrous web is exposed to hot or cold gas streams. Therefore, it is not necessary to force these gas streams to remain in the fibrous web for a long time. In contrast to the facts disclosed in DE-A-22753, it has been shown that the gases can be allowed to escape immediately after contact with the mineral fibers. That is, the distance that the gases must travel in the mineral fiber web can be short and that the gases can be supplied under high pressure without compression of the fibers.

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PCT / DK93 / 00154

SUMMARY OF THE INVENTION

Therefore, the principle of the method according to the invention is that the gas streams are fed into the web from a plurality of separate inlet regions, where the rows extend transversely to reduce the web movement, and the gas streams are released from the same side. areas.

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

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

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The method according to the invention is particularly suitable for heat treatment of fibrous webs and the gas stream model obtained in the heat treatment of fibrous webs according to the preferred embodiment of the drawings, wherein Fig. 1 is moved by two 4 in a plane perpendicular to the plane of the method 2, which gas-conveying conveyor belts of paper. The gas inlet regions 2, which are elongated and extend in the direction of movement of the fibrous web 2, deflect the hot gas streams which follow the deviations to move parallel to the plane of the web once more to be discharged through the exit regions 3 located next to the air the inlet ducts 2, out of the fibrous material web 2.

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The arrangement of the jet model as shown in the figure allows to increase the curing ability by 2 to 3 times compared to curing by means of a hot air stream passing through the cross-web.

As mentioned in connection with the description of the drawings, the gas inlet regions and the gas outlet regions may be elongated.

It is preferred that the regions to which the hot air is supplied from one side of the fibrous web are positioned exactly opposite the gas supply region from the opposite side, but the two regions may be slightly offset from each other. Further, the opposing regions are not necessarily the same size. Usually, however, at least 25¾ 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 made in various ways. However, it is preferred to use a pressure higher than atmospheric pressure in the gas inlet region and atmospheric pressure or less than atmospheric pressure in the gas outlet region (s). However, it may also be advantageous to use less than atmospheric pressure in the gas outlet region (s) and atmospheric pressure in the gas inlet region.

It is essential that differential pressures in adjacent areas be maintained 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 elongate gas inlet regions are preferably divided in the longitudinal direction to form individual compartments, rvr / DKy3 / 00154, and different pressures can be maintained in adjacent compartments.

It is therefore advantageous to maintain low pressure differences between the first compartment in the gas inlet region and the corresponding gas outlet region than between the subsequent compartments and correspond to their gas outlet region (s).

During the initial heat treatment, portions of the fibrous web in which the density of the fibers is lower are most exposed to compression. It is therefore important that this initial heat treatment is carried out at relatively low differential pressures.

Since the gas flow is strongest in regions having a low fiber density, curing and the resulting fiber reinforcement 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 above-mentioned increased curing capability is not conditioned by carrying out the entire operation as described above. Therefore, o

It has been found that an increase in curing capacity can be achieved by adjusting the sections of existing curing ovens, eg 20-90%, and in particular the first half of these% is preferred that curing is carried out by the method of the invention.

Furthermore, it was found. 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 through which usually the fiber pipe passes through the curing furnace, thereby forming thin cured surface layers by contacting the strips with the fiber web surface. Thus, when the initial curing is carried out as described above and the formation of said thin surface layers is followed, higher differential pressures can be used without the risk of recessing in the surface of the fibrous web.

According to the invention, the fibrous web is preferably maintained between two gas-permeable strips, such as lamella strips, and is thermally treated with gas streams supplied from opposite sides.

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

The process according to the invention is suitable for the heat treatment of fibrous webs having densities over a wide range, but is particularly suitable for processing light products of e.g. mineral fiber webs having a density of up to 7 kg / m ³ , but preferably a density of 15-60 kg. m ³ · Fibrous webs can be composed of one or more layers of fibers.

FI-B-80102 discloses a method for drying a fibrous web. wherein the fibrous web is arranged between two airtight

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PCT / DK93 / 00154 guide strips are heated by supplying heat to the. belts.

GB 367530 discloses an apparatus for drying textile fibers, wherein the fibrous web is kept loosely suspended in the drying zone and hot air is blown to 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 supporting and moving the mineral fiber web between the gas inlet openings located on opposite sides of the mineral fiber web and the gas outlet openings, characterized in that the gas inlet openings form a line extending transverse to the direction of movement of the fibrous web and alternate with the gas outlet openings.

According to the invention, each gas outlet channel ε is preferably connected to the 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 gas to flow out of the fibrous product and to be recirculated and optionally reheated and recycled to the fibrous product to minimize heat loss.

As mentioned above, the method and apparatus of the present 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.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is illustrated in the accompanying drawings. FIG. Yippee. Fig. 2 is a vertical sectional view of a preferred embodiment of the device according to the invention; and Fig. 3 is a partial perspective view of the device according to the invention of Fig. 2, wherein some parts are in section.

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DETAILED DESCRIPTION OF THE INVENTION ^!

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. The upper branch 20 is connected to the upper gas inlet region and is divided into compartments 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 inlet region, which is divided into compartments 28 by gas outlet channels 30, which are open at the ends. At the ends, the outlet ducts 24 and 32 are connected to the gas collection areas 32 and 34, which are connected to the outlet duct 40 via the connection ducts 36.

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As can be seen from FIG. 2, the outlet channel 40ΰθ is connected to a heating device 42 consisting of a burner 43 which can be used to reheat the gas leaving the curing chamber.

16. The gas supply to the device 42 and the supply of hot gas to the inlet duct 13 is provided by a centrifugal blower 44.

the device works as follows:

The hot air from the heater 42 is blown through channel 13 via blower 44 and branches 50 and 52 into sections 54 and 23. From there, the hot gas passes through strips 10 and 12 to mineral fiber web 14 and from there to adjacent gas outlet channels 26 and 30; generates an 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 via the connecting channels 36 and 3' to the outlet channel 40 and back to the device 42.

From the above description, it is apparent that the hot gas is lined with the mineral fiber web 14 immediately after introduction, i.e., the operation can be carried out using small pressure differences between the compartments 54, 23 and the gas outlet passages 26 and 30. the device allows efficient heat treatment of the mineral fiber web 14 without the risk of forming recesses in the surface of the fibrous web.

Claims (11)

PATENT REQUIREMENTS γΙ & ΙϋιώΆο »wa.4eritík 1. Method of heat treatment of a mineral fiber web, in which case. se. The oppositely directed gas streams feed 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, the row extending transversely to the direction of movement of the web; the gas streams are discharged from the same side from which they are fed by exit regions which are arranged in alternation with the inlet regions. 2. The method of claim 1 wherein the gas inlet and gas outlet regions are elongated. A method according to claim 1 or 2, characterized in that. It is used to process a mineral fiber product containing a heat curable binder. hot gas streams having a temperature above the curing temperature of the 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. 5. The method of claim 3 wherein the gas inlet regions through which the hot gas stream is fed to the fibrous product from one side partially overlaps the gas inlet regions through which the hot gas stream is fed from the opposite side. .. .. “II modified page of 09.05.94 PCT / DK93 / 00-154 6. The method of 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 opposite side constitutes at least 25% of the smaller of the two regions. * 7. A method according to any one of claims 3 to 6, wherein the gas inlet regions are maintained at a pressure greater than atmospheric, and the gas outlet regions are maintained at or below atmospheric pressure. 8. Method according to of claim 2 marked width input areas gas is greater than or equal to output width gas areas. - 9. Method according to Claim 2 v marked with t m elongated the inlet regions of the piyn are longitudinally divided to form separate compartments. The method of claim 9, characterized in that different pressure differences are maintained between the compartment in the gas inlet region and the adjacent gas outlet region and between the remaining compartment (s) and the adjacent gas outlet region (s) 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, 29) located on opposite sides of the mineral web (14) The gas inlet openings (24, 29) are arranged in a line extending transversely to the direction of movement of the fibrous web and are arranged alternately with the gas outlet openings (26, 30). i 2 t ί (Γ. That each one of the inlet is arranged or cooling Apparatus according to claim 11, characterized in that the gas outlet opening (26, 30) is connected to at least a gas opening (24, 28) via a gas pipe (40, 18) therein, and a pump (44) and optionally heating means (42). Apparatus according to claim 11 or 12, characterized in that the gas inlet openings (24, 28) are elongated.