The invention relates to a device and a method for the heat treatment of continuously conveyed sheet-like structures. The device and method are suitable particularly for the heat treatment of a warp or of an elongate textile sliver. Heat treatment may be, for example, drying and/or drafting of a previously treated thread or fabric. In the production of tire cord, for example, the fabric impregnated with an adhesion promoter has to be led through a dryer. Moreover, the plastic fibers are subsequently drafted.
A device for the heat treatment of tire cord products became known, for example, from DE 2 108 263 A. The device shown there has a plurality of modules which are arranged next to one another and through which the material to be treated is led in a meander-like manner in loops. Each module has a system for feeding and discharging hot gas into and out of a heating chamber. Two inlets for the hot gas and one outlet arranged at the upper end of a module tower are provided for each module.
Moreover, devices are known in which heating sections, each with three nozzle boxes, are present. Hot air is introduced laterally into a middle nozzle box. The exhaust air is sucked away again laterally in an upper or a lower nozzle box section (see also the illustration in
In practice, these arrangements have various disadvantages. Thus, unfavorable flow conditions may arise in the heating chambers, and this may lead to a final product of deficient quality. Especially when uneven temperature distributions arise in the heating chambers, this may lead to product properties distributed unevenly over the width of the sliver. Especially when lower airflows prevail in regions (see, for example, the lower region in
Moreover, in particular, lightweight slivers can be moved transversely with respect to the transport direction on account of a cross flow (see also
Another problem is that, on account of process-related dryer heights, above all lightweight material is excited to oscillate over the free length. This fluttering may lead to undesirable contact with the mechanical parts of the dryer and cause damage to the material. In such a case, with existing dryers, only the plant speed can be minimized, which, in turn, results in a loss of plant productivity.
A further problem in known devices is that the heating energy employed cannot be utilized optimally. Energy costs make up the main constituent of the production costs in such treatment devices. Finally, a problem in known devices is also that they require a large closed-in space, that likewise increases the investment costs.
An object of the present invention, therefore, is to avoid the disadvantages of the prior art and, in particular, to provide a device and a method, in which the process conditions in the heating chambers can be controlled accurately and which can nevertheless be used universally for a multiplicity of different process conditions. Thus, for example, different coatings in respect of their chemical composition and different types of sheet-like structures made from different materials should be able to be treated by means of the same device. The device is then to be distinguished by a low energy demand and low space requirement, fluttering and creasing even of lightweight fabrics are to be prevented and homogeneous energy transmission in the entire heating chamber is to be achieved.
These objects are achieved, according to the invention, by means of a device and by means of a method having the features of the preamble of the independent claims.
According to a first aspect of the present invention, the device for heat treatment has at least one treatment module. The device serves for the heat treatment and, in particular, for the drafting of continuously conveyed sheet-like structures. Such sheet-like structures are typically a warp or a textile sliver, in particular tire cord or conveyor belt fabric. In addition to drying, the device is also used in a way known per se for the drafting of plastic fibers.
The treatment module has at least one heating section. The sliver can be led along a transport path approximately vertically through at least one heating chamber of this heating section. The guidance of the sliver takes place approximately vertically in an upward direction and optionally, after it passes through a deflection means, in a downward direction through a further heating chamber of the heating section. The cloth is typically deflected via a roller for looped material guidance.
The heating section has at least one line connection for feeding a heating medium into the heating chamber. The heating medium is typically hot air. Moreover, the heating section has suction extraction means for discharging the heating medium out of the heating chamber. In addition to the exhaust air, if appropriate, substances emitted from the coating of the sliver, such as, for example, smoke-generating exhaust gases, can also be discharged.
The line connection is connected to at least one nozzle box which extends in the transport direction and transversely thereto. Typically, by means of the nozzle box, air is injected uniformly, over the entire width of the sheet-like structure into the heating chamber approximately perpendicularly to the sheet-like structure.
According to the invention, the suction extraction means are arranged essentially symmetrically with respect to the transport path and/or at one end of the heating section. By virtue of this arrangement at the end of the heating section, the air injected into the heating chamber is distributed essentially homogeneously in the heating chamber and is guided, parallel to the sheet-like structure or the sliver, in an essentially laminar flow in the direction of the end of the heating section or of the heating chamber. The end of the heating section is understood in this context to mean both an entry end and an exit end for the sheet-like structure. The suction extraction means is typically arranged in each case at that end of a heating section in which the sheet-like structure is delivered to or discharged from the device or is delivered via a deflection arrangement to a further following treatment module or from a preceding treatment module.
The nozzle boxes are arranged in each case laterally with respect to the transport path of the sheet-like structure, so that a heating chamber is formed between two adjacent nozzle boxes. The nozzle boxes are otherwise designed in a way known per se.
Excitation to oscillation or fluttering of the fabric web is greatly reduced by the established flow being essentially laminar.
Since the air moves symmetrically or parallel to the cloth run, there is also less risk of creasing because transverse force no longer acts upon the sliver.
According to a preferred embodiment, two heating sections are provided in each treatment module, a second heating section being provided above a first heating section, so as to give rise to a vertical transport path, running through the two heating sections, parallel to the sliver through the treatment module. In this case, the suction extraction means of the lower heating section are arranged at the lower or bottom-side end of the heating section. The suction extraction means of the upper heating section are arranged at the upper end of the heating section and therefore also of the treatment module. By the air being suction-extracted in these marginal regions, energy efficiency is improved, since this prevents hot exhaust air from passing into the surroundings.
Especially preferably, the suction extraction means are formed by suction extraction bodies which project into the heating chambers and which have at least one suction extraction port. By means of such specially configured additional suction extraction bodies, the flow of air within the heating chamber can be deliberately influenced so that, as far as possible, no dead corners occur and such that the airflow is as laminar as possible and runs parallel to the cloth run. A dead corner is understood in this context to mean a region in the heating chamber in which no or only insignificant air movement occurs and in which another, typically lower temperature would accordingly prevail.
Especially preferably, a suction extraction body is provided on each side of the transport path or of the sheet-like structure. Especially preferably, in the case of a treatment module with a transport path running vertically upward and a transport path running vertically downward parallel to it, three suction extraction bodies arranged next to one another are provided. The sliver is then led in each case in a gap space through between two adjacent suction extraction bodies in each case. If three nozzle boxes arranged next to one another are present in a heating section and define two heating chambers, preferably in each case each nozzle box is assigned a suction extraction body. Nozzle boxes which blow the air toward the sliver on one side are provided with a suction extraction body which also sucks in the air again from one side. Nozzle boxes which on both sides direct air against a sliver, for example a sliver guided upward in the vertical direction on one side and a sliver guided downward in the vertical direction on the other side, are provided with a suction extraction body which sucks away air from two sides. This ensures that air routing within a heating chamber is homogeneous and that homogeneous air routing and therefore temperature distribution prevail in a heating chamber even on both sides of the sliver.
The suction extraction body is preferably of box-shaped design. It typically is a rectangle in profile cross section. Such suction extraction bodies can be produced simply and, moreover, are adapted in their shape to the surface of the sliver led past. The suction extraction body typically has an approximately straight region and an entry region, adjoining the latter, with a widening flow cross section. The entry region adjoins the suction extraction means and a corresponding line connection. Suction extraction ports are arranged in the box-shaped suction extraction body in the sidewalls running in the transport direction and/or in further boundary surfaces. Designing the suction extraction body as a box with sidewalls allows suction extraction ports to be freely positioned. Tests can in this case make it possible to find an optimal arrangement of the suction extraction ports for generating as homogeneous and as laminar an airflow as possible. Ports prove to be especially suitable which are arranged as long holes in the sidewall adjacently to the end face facing the line connection and in an endwall facing away from the line connection. An additional port in the entry region having the widening flow cross section is likewise preferred. It is conceivable, however, that other suction extraction ports likewise bring about the desired effect of as laminar a flow as possible and as uniform a temperature distribution as possible.
The suction extraction body extends transversely with respect to the transport direction over at least 80% of the width of the sliver into the heating chamber. The suction extraction body preferably extends over the entire width of the treatment module.
A further aspect of the invention relates to a device for heat treatment, with at least one treatment module which has a first heating section and a second heating section arranged above the first heating section. Each heating section has a line connection for feeding a heating medium and suction extraction means for discharging the heating medium out of the heating section. According to the invention, the suction extraction means of the first heating section are connected via a line to the line connection for feeding a heating medium of the second heating section. The suction extraction means of the second heating section are connected via a line to the line connection for feeding a heating medium of the first heating section. This crosswise connection of the first and of the second heating section achieves as homogeneous a distribution of the temperature as possible in the two heating sections of a heating module. At the same time, the concentration of, for example, solvents in the two heating sections is kept as identical as possible, so that essentially identical process conditions prevail. The line connections are preferably in each case preceded by a blower unit, by means of which the air is conveyed out of one heating section into the other heating section. The lines which connect the two heating sections to one another are in this case preferably arranged on the same side of the treatment module, specifically, in particular, on a side wall which stands transversely to the sliver or to the transport path. Different treatment modules can thus be arranged compactly next to one another. The lines connecting the individual heating sections project laterally from the modules in only one direction. The space requirement is consequently reduced.
The natural convection in the mainly vertically arranged heating zones ensures a colder region at the lower end of the heating zone and a warmer region at the upper end of the heating zones. As a result of the crosswise arrangement of suction extraction and the injection, the temperature difference occurring due to convection between top and bottom is homogenized.
While such a crosswise connection of the air feed and air discharge of the individual heating sections is already advantageous in itself, this type of air routing is especially advantageous in combination with the above-described arrangement of air discharge on the end faces and with suction extraction bodies. By virtue of this combination, a further unification of the process conditions and more homogeneous temperature distribution can be achieved.
Yet another aspect of the invention relates to a device for the heat treatment and, in particular, for the drying and drafting of continuously conveyed sheet-like structures, in particular a warp or textile sliver. The device has at least one treatment module with at least one heating section. The sliver can be led for the purpose of treatment through the treatment module and through the heating section. The heating section has at least one line connection for feeding a heating medium, in particular heating air, into at least one heating chamber. The line connection is provided with a blower unit for conveying the hot air. The line connection is connected to at least one nozzle box, via which the heating medium can be introduced into the heating chamber. According to the invention, a heat exchanger is arranged on the pressure side between the blow unit and the line connection. The heat exchanger may, for example, be a directly heating burner arrangement operating with gas or light fuel oil or with other fuels or an indirectly operated heat exchanger device through which treatment fluid flows. It was shown that, by the heat exchanger being arranged on the pressure side between the nozzle boxes and the blower, much more homogeneous air distribution can be achieved in the nozzle box and subsequently in the heating chambers. The heat exchanger has in this case a laminarizing effect upon the air flowing through. Admittedly, by the heat exchanger being installed on the pressure side, the velocity of the airflow is somewhat reduced. Instead, a dynamic pressure is built up which leads to uniform velocity distribution in the air after it leaves the heat exchanger and which thereby achieves uniform heat transfer over the entire heat exchanger cross section. This aspect of the invention, too, is preferred in itself, but may especially advantageously be combined in combination with the above-described measures for improving the uniformity of air distribution. On account of the more regular velocity distribution, better heat transmission occurs. This results in higher efficiency of the heat exchanger.
A plurality of treatment modules may be arranged next to one another. In this case, the sliver can be conveyed by upper and lower deflection means in each case in a meander-like manner in loops through the device from one module to the next module.
The components, such as blower, heat exchanger and lines, used in the individual treatment modules lying next to one another may in this case be in each case designed identically. Since the air distribution and temperature distribution in the individual heating chambers are homogeneous due to the structural measures taken, further modifications or adaptations to the air guide elements in order to bring about this desired homogenization are not necessary. The measures according to the invention therefore make it possible to provide a modular type of construction which by means of a few standardized components enables universally usable devices to be provided, even in terms of economic factors.
A further aspect of the invention relates to a method for the heat treatment and, in particular, for the drying or drafting of continuously conveyed sheet-like structures. The method is typically carried out, using a device as described above. The sheet-like structure is preferably led approximately vertically in an upward direction and optionally, after passing through a deflection means, in a downward direction through at least one heating section of a treatment module. In this case, the sheet-like structure is acted upon via a heating medium. The sheet-like structure is introduced via a nozzle box into at least one heating chamber of the heating section. According to the invention, the heating medium is subsequently sucked away via a suction extraction means arranged on an end face of the heating section, such that homogeneous temperature distribution and laminarized flow parallel to the sliver direction occur over the width of the sheet-like structure and an airstream running in the conveying direction, that is to say in the upward or the downward direction, is generated.
Yet another aspect of the invention relates to a method for the heat treatment and, in particular, for the drying of continuously conveyed sheet-like structures, particularly using a device as described above. In this case, the sheet-like structure is preferably led approximately vertically in an upward direction and optionally, after passing through the deflection means, in a downward direction through two successively connected heating sections of a treatment module. According to the invention, the air discharged out of one heating section via a suction extraction means is heated again via a heat exchanger and is fed again in each case to the other heating section via a line connection.
Yet a further aspect of the invention relates to a method for the heat treatment and, in particular, for the drying of continuously conveyed sheet-like structures, particularly using a device as described above. In this case, the sheet-like structure is led through at least one heating chamber of a treatment module. According to the invention, a heating medium is introduced by means of a blower through a heat exchanger and then in to the heating chamber. In this case, the heat exchanger is arranged on the pressure side between the blower and the heating chamber. An especially uniform introduction of the hot air into the heating chamber can consequently be achieved.
The invention is explained in more detail below by means of the drawings and in exemplary embodiments. In the drawings:
a shows a perspective illustration of a treatment device with air feed and air discharge according to the prior art,
b shows an arithmetic determination of the air velocity in the heating chamber according to
The line connections 13 and the suction extraction lines 14 are in this case arranged on the housing of the treatment modules 10 laterally, that is to say on the side faces perpendicular to the sliver. The pipelines 40, 41 and line connections 13 and suction extraction lines 14 consequently all project in the same direction, so that the three treatment modules illustrated in
The hot air is injected into the heating sections 11a, 11b by means of a blower 42. A heat exchanger 43 is arranged on the pressure side of the blower between the blower and the line connection 13. On account of this arrangement, uniform air distribution can be achieved even with a very short pipe length between the fan 42 and line connection 13. The device 1 can consequently have a space-saving build. The device shown in
Suction extraction bodies 16 are arranged in the entry region on the end face 9 of the module. Each nozzle box 15 is assigned a suction extraction body 16. The suction extraction line 14 has a branch into three suction extraction connection pieces 24, in each case a suction extraction connection piece 24 being assigned a suction extraction body 16.
The heat exchanger is designed as a fluid heat exchanger, a heating fluid being fed and being discharged again via connections (44). The fan (42) is typically a radial air blower with lateral blow-out. The nozzle boxes (15) are designed in a way known per se. The middle nozzle box has on both sides nozzle ports directed outward. The in each case outer nozzle boxes 15 have only inwardly directed nozzle ports. The sliver led through the heating chambers 20 formed between the nozzle boxes is in this case acted upon with hot air from both sides.
Between the suction extraction bodies 16, gaps spaces 18 are formed, through which the sliver W is led. Since a suction extraction body 16 is assigned to each nozzle box 15, a suction extraction of warm air from both sides of the sliver is produced over the entire width of the latter. The suction extraction body 16 has a width B which corresponds at least to the width b of the nozzle boxes.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2009/068033 | 12/30/2009 | WO | 00 | 8/3/2012 |