JPS634116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of drying, finishing, fixing, and fixing fiber strips while continuously and non-contactly measuring the temperature of the strips.
The present invention relates to a method and apparatus for controlling continuous convection heat treatment during dyeing, etc.

This kind of method is described in the magazine “Melliand
Textilberichte”, August 1965, page 887 The report on the right column describes the case of drying humidified fabrics. It states that under uniform drying conditions, fabrics are allowed to dry until a certain critical residual moisture is reached, which varies depending on the fiber type. It is observed that the temperature remains approximately constant. Once this moisture is reached, the drying rate must be significantly reduced and a uniform increase in the fabric temperature must be observed. The fabric is completely dry and due to the evaporation of water When no more energy is expended, there is an almost constant temperature at the high level achieved.The onset of a more uniform temperature increase indicates that the critical residual moisture has been reached, so that temperature changes can be made more easily due to the decreasing moisture content. Therefore, in the known technology, the temperature of the material can be directly measured.
However, it is continuously measured without contact using a temperature sensor such as a radiation thermometer.

Temperature curves for each device such as a tenter,
When recording along the processing path in hot-free and perforated drums or sieve drums or sieve belt devices, different processes are possible in which the temperature rise point or the breaking point of the temperature curve is located at a different location along the processing path depending on the respective requirements. Due to the conditions, temperature sensors must also be placed along this path in the form of a screen that makes it possible to check all "temperature corners". The control of continuous convective heat treatments has hitherto only been possible to a very limited extent, since the widely available temperature sensors which operate without contact, such as radiation pyrometers, are very expensive. In this case, such a control serves to better adapt the temperature curve of the equipment used to the respective processing purpose with the aim of energy saving, and in such a way that the necessary costs are of course compensated for by the energy saving. must be taken into consideration.

Therefore, simple temperature measuring instruments that operate without contact have already been developed for working with heat treatment equipment such as tenters (Magazine Textibetrieb, 1981, 4).
month (see page 55). In this case, the temperature of the boundary layer of the material to be controlled is measured. Fluttering of the material in a heat treatment device, such as a tenter or hot freeze, is unavoidable, and since the thickness of the boundary layer suitable for measurement is only a few mm, contact between the measuring device and the material is unavoidable. The material side of the measuring device is therefore coated with a friction-reducing plastic. In practice, this device can only be used in special cases, since when processing many strips of fabric, marks occur to some extent even with low friction.

The object of the present invention is to obtain a device for recognizing the processing progress in a continuous convection heat treatment device for fiber strips and controlling the transport speed. It should be possible to control and/or adjust parameters based on measurements and to be able to manufacture and operate at a cost that is fully compensated by the savings in energy and production time.

This object is achieved by the above-mentioned apparatus for controlling the continuous convective heat treatment of a fiber strip while continuously measuring the temperature of the strip without contact, according to the present invention. solved by means.

In this case "air" refers to all process gases used. The device according to the invention uses a nozzle arrangement having a number of nozzle rows or nozzle areas that follow one after the other on a transport path, for each temperature difference measurement along and/or perpendicular to the web transport path. For this purpose, one sensor is arranged at the nozzle outlet directly on the strip, and another sensor is arranged in the return passage of the nozzle arrangement directly on the strip. Such a device can be installed in a tenter or hot fly. Alternatively, the device according to the invention provides for the processing of webs according to the flow-through principle, for example in the case of sheave drum or sieve belt systems, with one sensor for each temperature difference measurement parallel and/or perpendicular to the web transport path. In front of the strip in the direction of air flow, another sensor is arranged after the strip in the direction of air flow.

Therefore, according to the measures of the invention, the amount of heat imparted to the strip by the heated air, which is actually proportional to the difference between the temperature of the arriving air and the temperature of the material, is reflected or passed through to the temperature of the arriving air. It is measured as a function of the difference between the temperature of the cooled air or the reflux air.
Furthermore, the temperature of the air blown onto the material is constant;
or at least that it can be measured directly, so that the measurement according to the invention of the thermal energy imparted to the strip results in the temperature of the material itself, especially when measured at a number of successive positions on the transport path. A curve corresponding to is obtained.

Since only air thermometers or thermocouples are required according to the invention to control the continuous convective heat treatment, the cost is very low and the cost of installing multiple devices on the transport path of the strip is reduced by the cost of each device. Fully compensated by energy savings during operation.

Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows two nozzle boxes 1 and 2 of the tenter from which air or other heated process gas in the direction of arrow 3 is blown onto a fiber strip 5 moving in the direction of arrow 4. FIG. High-temperature air flowing in the direction of arrow 3 from inside the nozzle boxes 1 and 2 is reflected by the strip 5 and flows into the reflux passage 7 arranged between the two nozzle boxes 1 and 2, respectively.
flows in the direction of arrow 6. The blown gas gives a constant amount of heat Q to the strip according to the difference between the temperature t _D of the blown gas and the temperature t _W of the strip 5, and the reflux gas gives the strip 5 a lower temperature t _R. reflux in the direction of arrow 6. As mentioned above, the temperature difference Δt _L =t _D −t _R between the blown gas and the reflux gas is compared to the amount of heat Q given to the strip 5 from the heated gas. This amount of heat is theoretically proportional to the difference between the temperature t _D of the blown gas and the temperature t _W of the strip, and it is assumed that the temperature t _D is constant or known, so the temperature t can be directly calculated from the temperature difference Δt _{L. W} can be estimated so that Δt _L ~t _W for a constant t _D .

If the thermometers 8 and 9 are placed directly at appropriate points in the nozzle box 1 and the reflux passage 9 and connected in such a way that the measured temperature difference Δt _L = t _D −t _R can be obtained, the corresponding positions can be determined. The value of Δt _L can directly indicate the local temperature t _W of the strip. Furthermore, if thermometers 8, 9 are placed at the exit of the nozzle box and the entrance of the reflux channel along the transport path of the strip 5 at mutual distances that depend on the individual case, a temperature curve such as that shown in FIG. 2 can be measured, for example. can do.

FIG. 2 shows the temperature course of the strip 5 over the path or length of the strip in the respective heat treatment device for various cases. The air flowing from the nozzle boxes 1, 2 to the strip 5 has a constant temperature _tD in this case. Therefore the temperature of the band cannot rise above _tD . If the yarn is supplied with a pre-moistened fiber strip for pure drying purposes, the temperature curve will in principle follow curve A. If, on the other hand, the already dried strip is simply fixed, a temperature curve of curve B results. In practice, in many cases the strip is fixed at the same time as it dries. The temperature curve in that case is shown by curve C in FIG.

If only drying of the wet strip is desired, the strip is heated to the so-called evaporation equilibrium temperature t _G immediately after introduction of the strip into the respective device. This temperature remains approximately constant while the liquid contained in the strip gradually evaporates, up to a critical residual moisture content. When the critical residual moisture is reached, a breaking point appears on the temperature curve, and the temperature increases thereafter. If a temperature break point and a subsequent progression of temperature increase are observed or determined according to the invention, the transport speed of the strips in the respective drying device is adjusted such that the strips reach a predetermined degree of dryness T at the exit. be done.

On the other hand, if the purpose is simply to fix a pre-dried strip at a relatively high temperature _tD , the temperature _TW of the strip will very quickly reach approximately the blown gas temperature _tD along curve B due to the absence of moisture. Rise. At this fixed temperature, the strip is fixed for a certain residence time, for example a few seconds. According to the invention, the point in time at which a fixed temperature is reached can be precisely determined, so that the transport speed of the respective device can be adjusted in such a way that the strip is held exactly at the fixed temperature for the desired residence time. If, on the other hand, it is not possible to accurately determine the point at which a fixed temperature is reached, for example because the measurement costs are too high, then the transport speed of the device must be selected in such a way that the required residence time is maintained in all cases. Up to now, therefore, work has often been carried out with unnecessarily long residence times and associated energy and production losses for safety reasons.

To date, particularly difficult problems have arisen in terms of measurement technology when drying and fixing humidified strips. That is, the temperature increase range after the break point on the temperature curve following the end of the evaporation equilibrium temperature range varies greatly depending on the humidification, the weight of the strip, the material thereof, etc. For the recording or positioning of the break point of the temperature curve following the end of the evaporation equilibrium temperature level and reaching a fixed temperature approximately equal to the temperature t _D , and therefore the band temperature along the length of the transport path. A large number of measurement positions are required to determine the temperature difference Δt _L corresponding to T _W . This requires an arrangement in the form of a very small screen, in particular the precise measurement of the break point in the temperature curve representing the beginning of reaching the fixed temperature, and the remaining residence time V ₂ in the respective device fixing the strip. must be controlled so that it is sufficient to do so. The advantages of the invention are particularly clear in this case, since the cost per measuring unit is considerably lower in the case of the invention compared to known devices. This is because, despite the large number of measurement positions, the energy savings and production increases achieved by the invention greatly exceed the cost for the apparatus of the invention.

When the present invention is applied to a porous or sieve belt or sieve drum device for drying, fixing, etc., the principle is the same as in the case of a tenter nozzle system. According to FIG. 3, the strip 5 is a belt 1 having holes 11 through which the process gas flows in the direction of the arrow 12.
3 in the direction 14, in which case the transport direction 1
Processing gas flows through the strip in directions 4 and 12 approximately perpendicular to the plane of the strip. Thermometers 15 to 17 or 18 for measuring gas temperature before and after the strip 5
~20 are used. If sufficient thermometer pairs are placed along the treatment section, the second
The temperature curve in the figure can be recorded. Although FIG. 3 relates to a sheave belt system with a flat belt, this belt can also be viewed as the surface of a perforated drum system projected onto a plane.

If the temperature curve is recorded perpendicularly, rather than parallel, to the direction of transport of the strip in the system of Figures 1 or 3, the air supply or suction to the strip will result in a temperature plateau with the same temperature across the width of the strip. Adapt it to occur.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a portion of the tenter nozzle system, FIG. 2 is a diagram showing the temperature progression along the length of the heat treatment apparatus, and FIG. 3 is a longitudinal sectional view of a portion of the sieve belt system. 1, 2... Nozzle box, 3... Spraying direction, 5...
Band-shaped body, 6... Reflux direction, 8, 9; 15 to 17; 1
8-20...Thermometer.

Claims (1)

[Claims] 1. For blowing heated air onto a moving strip,
It has a nozzle outflow passage close to the band-like body and a nozzle outflow passage and a return passage close to the band-like body for guiding the air reflected by the band-like body, and a large number of nozzle rows or In a device for controlling the continuous convective heat treatment of the fiber web 5, with continuous non-contact measurement of the temperature in a tenter frame with a nozzle area, for each measurement carried out along the web transport path 4, the temperature A thermometer 8 for detecting the temperature _tD of the heated air flowing onto the strip 5 is arranged at the outlet of the nozzle box of the nozzle outlet passage 1, and the thermometer 8 detects the temperature tD of the heated air flowing onto the strip 5, which is reflected by the strip 5. A device for controlling continuous heat treatment of a fiber strip, characterized in that a thermometer 9 for detecting the temperature of the heated air 6 is disposed at the entrance of the reflux passage 7. 2. In an apparatus that controls continuous convective heat treatment of a fiber strip by flowing heated air through the strip in an apparatus having a sieve drum or a sieve belt and continuously measuring the temperature t _W of the strip without contact, the flow-through principle is used. For each measurement, the temperature t _D of the air heading towards the strip and the strip 5 are
along the strip transport path ₁₄ and/or
Thermometers 15 to 17 for detecting the temperature _tP of the air heading toward the strip 5 are arranged in front of the strip in the direction of the air flow, transversely to the strip transport passage 14, and detect the temperature tP of the air flowing through the strip. 1. A device for controlling continuous convective heat treatment of a fiber strip, characterized in that a thermometer for detecting the temperature t _R is placed behind the strip in the direction of airflow.