EP1333117A1 - Method and apparatus for moistening textile materials - Google Patents

Abstract

Prior to entering the vacuum chamber (D) for steam treatment, the material is actively cooled in a cooling chamber (C). In cases where the initial material temperature is above the ambient temperature, it can be exposed in a passive pre-cooling zone (B) till the temperature has been reduced by at least 1 degree. Also claimed is a conditioning plant including a pre-cooling zone (B), an enclosed refrigerated cooling zone (C) with forced air circulation and a vacuum chamber supplied with steam. Preferred Features: When processing yarns, the bobbins are arranged in batches on bobbin carriers. In the case of cotton, the initial moisture content is 0 to 5 %. Cooling takes place for 20 to 40 minutes at a temperature at least 10 degreesC below ambient. The vacuum chamber is fed with saturated steam at 68 degreesC or below.

Description

The invention relates to a method and an arrangement suitable therefor Moistening textile material, especially textile yarns and fabrics.

Textiles are hygroscopic, ie they absorb moisture. This ability varies from fiber to fiber. Air humidity, temperature and other external influences play a major role. It is currently common in the textile industry to "condition" the yarns that are produced on the spools of natural, synthetic, and mixed fibers and that are wound on bobbins. The aim of conditioning is to bring the moisture lost during the spinning process back into the yarn as much as possible. The residual moisture remaining after spinning is, for example in the case of cotton yarns, of the order of 5 percent by weight, while the commercial product is said to have 8.5 percent by weight of moisture which corresponds to the original yarn moisture. This water content is also necessary so that the fibers in the yarn smooth themselves sufficiently after spinning and remain elastic so that thread breakage occurs as little as possible at the usual working speeds of weaving and knitting machines. On the other hand, it is in the interest of the seller of textile materials to offer products whose actual moisture content is not, or not substantially below, that which is customary for the commercial goods, since a material of lower moisture, ie with a higher dry weight, does not achieve a higher price. The following are the commercially available moisture supplements for the most important fiber materials: cotton 8.50% flax 12.00% Wool 18.25% silk 11.00% viscose 11.00 to 14.25% (depending on the type) polyacrylic 1.50 to 2.00% (depending on the type) polyamide 6.25% polyester 1.50%

In the case of mixed yarns, the moisture surcharge is based on the for The unmixed yarns apply surcharges based on the proportion of each fiber in the Mixture calculated. A standard climate (20 ° Celsius, 65% relative air humidity) based on.

The most important parameters for assessing the yarn properties and their detection are e.g. described in booklet III for training in the Spinning mill ("characteristics and testing of fibers, strips, rovings and yarns"), published by Industrieverband Garne e.V., 9th edition Eschborn 1992.

There are two methods for determining yarn moisture:

a) Weight analysis after heat drying

Samples are taken from the delivery or packages provided for dispatch. These are weighed, then dried completely in a hot air stream and then weighed again. The difference in weight, expressed as a percentage of the weight of the dried samples, is the so-called drying loss. The trade weight (H) is then calculated using the following formula: H = Gn x 100% + r t 100% + u t G _n = net weight of the delivery, without sleeves and packaging
r _t = standard moisture surcharge
u _t = loss on drying (in% of dry weight)

b) Electrical determination

A faster method is the capacitive determination of the yarn moisture with a commercially available measuring device (e.g. the device from Forté).

It is supposed to carry out the exact weight analysis of the moisture Do not replace drying in the oven, but provide sufficiently precise documents for operational monitoring. This method has the advantage that the test material is here is not changed, the measurement time is very short and handling is convenient is.

There are also handheld moisture meters for practical use, where the moisture content in the bale, ribbon, roving and Yarn (cops, bobbins) using needle electrodes or measuring probes with satisfactory Accuracy can be determined.

Finally, the term fineness of trade is explained:

In the formulas for yarn count dtex = grams / 10,000 meters or Nm = meters / gram the weight of the thread is included. The yarn count also fluctuates with the weight fluctuations mentioned in the previous section due to different moisture content. In order to eliminate these fluctuations, you put the trade weight in the formula. One then speaks of commercial fineness (trade number) or conditioned yarn fineness (yarn number).

Conditioning takes place in so-called vacuum humidifiers, evacuable containers, the batches of yarn on suitable carriers, e.g. Pallets, thorn carts, Pick up creels, hedgehog trolleys, perforated aluminum trolleys, boxes can. You evacuate, i.e. you bring the one loaded with the spools of thread Apparatus under reduced pressure and creates a saturated steam atmosphere in the apparatus, which corresponds to the reduced pressure (e.g. 55 to 68 ° C). The condensing water penetrates into the package and is removed from the fiber surface or capillary voids in the fibers. In the Condensation transfers heat to the material at the same time. The condensation comes to a standstill when the material reaches the saturated steam temperature Has. The process is canceled depending on the desired humidification result, with economic considerations regarding the duration of treatment Role-play. A suitable duration of treatment is e.g. at 10 minutes up to one hour and preferably between 20 and 40 minutes.

Differences in water absorption capacity result from the different Hygroscopicity of the different textile fibers, the influence of the physical and chemical substance data, as well as the yarn density, type of yarn winding, Fiber and yarn titer. These material constants should not be considered further here become. There are differences in the efficiency of the humidification process from the performance of the vacuum pumps, i.e. of the vacuum drawn (achieved reduced pressure), with a better vacuum also a better one Condensation result. This is because the effective condensing surface with improved vacuum on increasingly deeper layers of yarn extends within the coils. This is also inherent in the system and should be here not be considered further.

When conditioning you try the usual moisture surcharges (e.g. 8.5% by weight for cotton). Has the cotton before Conditioning a residual moisture of e.g. 5.0% and a yarn temperature of 20 ° C, can be done by means of vacuum humidification (without the one described below active cooling according to the invention) a moisture increase of hardly more than 2.5% (after 20 minutes and after evaporation after the conditioning process). Practically, the desired commercial standard becomes Moisture surcharge of 8.5% for cotton not reached.

With a residual moisture of e.g. 5% and a yarn temperature of e.g. 30 ° C reached only one essential under otherwise identical process parameters less moisture gain than 2.5%. It is then around 1.7%, also after 20 minutes of evaporation after the conditioning process.

In practice, however, the desired humidity is not achieved. It also includes to take into account that the residual moisture is distributed approximately evenly in all coil layers, while remoistening the outer coil layers preferred and the innermost areas are often hardly captured. This is true especially in so-called "warm countries" to: e.g. are the cotton producers Countries in subtropical regions and are also processing countries, i.e. Seat of yarn manufacturers. There is water loss of the fibers because of the higher temperatures in the spinning mills particularly high and therefore rewetting of the yarns produced is particularly important. The one described above However, the current method of conditioning sets the facts especially under these climatic conditions: where the yarns on the the conditioning result is particularly urgent bad. In addition, the steam temperature of the saturated steam goes up is limited. Especially when processing paraffin yarns for the Knitting is the highest permissible process temperature in the conditioning process at 65 ° C, i.e. it is saturated steam of reduced pressure, which the available pressure difference between atmospheric pressure and cannot fully utilize the performance of the vacuum pumps.

There is therefore a need for a method by which the currently operated Vacuum humidification process can be significantly improved.

The invention is based on the observation that in addition to those mentioned in the introduction (and generally cannot be influenced further) material constants the difference between the temperature of the saturated steam and the intrinsic temperature of the package to be moistened has a major influence on the moistening efficiency Has.

The invention therefore proposes a method, the essential feature of which consists in the textile materials before exposure to water vapor Actively pre-cool the vacuum humidifier (C in the attached sketch). As an "active Pre-cooling "is the action of air or an inert gas such as nitrogen the refrigerated goods referred to a temperature below a chiller brought from room temperature. This happens expediently Pre-cooling in a separate cooling zone or station (B in the attached sketch) before inserting the coils into the vacuum humidifier and not inside this humidifier, because otherwise its walls are always alternately cooled and would have to be reheated, or the cold walls the supplied water vapor would let condense. A suitable cooling zone is expedient lockable cold room or a cooling section provided with locks arranged, the residence time in this cooling zone - apart from economic Considerations - of the desired degree of cooling, but equally as when moistening also influencing factors such as yarn density, type of yarn winding, Fiber and yarn titer depends. The air temperature to which the refrigerated goods are exposed should, if possible, be at least 10 degrees below the ambient temperature but is generally not below 0 ° C useful, otherwise damage to the yarn could occur.

The cooling achieved will normally affect the outside and the inside Impact coil layers differently, i.e. while the outer layers already a temperature difference of 20, 30 or more degrees from the starting temperature the coil interior may not yet be noticeable Has experienced cooling. The cooling should therefore take as long as possible until it has also reached the inside of the coil, which is of course due to economic considerations is restricted. In principle, even a slight cooling can significantly improve the conditioning result. A suitable cooling period is generally of the same order of magnitude as subsequent moistening, e.g. ie at 10 minutes to 2 hours, preferably 20 minutes to 40 minutes, i.e. that the dwell times in the zones provided according to the invention or routes or their capacities can be chosen approximately the same size.

It may be advantageous to do the cooling in stages, i.e. that too Goods to be treated in batches (in batches) several cooling zones in succession or continuously a correspondingly dimensioned cooling zone in counterflow to run against a temperature gradient. Here, e.g. the Cooling air is supplied at the end of the cooling section at a certain temperature and moves towards the goods to be cooled, where it warms up. The warmed Air can advantageously be recycled, recooled and, if necessary can also be moistened. It is important to use lots of lots Process the time span from one cooling zone to the next as short as possible, especially when the ambient temperature is high, to keep the efficiency of the cooling process high. The same applies to the Period between leaving the (last) cooling zone and moving to the vacuum humidifier. The vacuum humidifier can also be used to further increase efficiency duplicated or used multiple times. As well can be provided, the refrigerated goods several times between the cooling zone and to move the vacuum humidifier back and forth.

In general, it is advisable to move the cooling air within the cooling zone and in such a way that the coils are intensely exposed to the cooling air on all sides be washed around. Moving the cooling air can be done using conventional fans happen, which can lie entirely within the refrigerator. But it can also be advantageous to use a circulating air process in which the cooling air is initially via external heat exchanger (evaporator of the refrigeration system), then through the cooling zone according to the invention and finally back into the heat exchanger to be led. This method has the advantage that the cooling performance is special can be well monitored and regulated. If a suitable facility is present, it may be advantageous to alternately reduce the cooling space Suspend pressure and bring it back to atmospheric pressure to "ventilate", so to speak, to allow gas exchange between the inside of the coil and to promote the ambient air.

Active precooling, treatment in a vacuum humidifier may be appropriate or repeat both steps. Several cooling zones are useful and vacuum humidifier arranged spatially close one behind the other. In this If it is preferred, both steps in succession a first and then a second or further times. The other steps of the process, including weighing and other common preparation measures the materials for shipping can also be duplicated if necessary be run through without leaving the scope of the invention.

The effect of the active cooling according to the invention is thereby advantageous supports that the spools of thread after the spinning process and before the pre-cooling process additionally cool (passively) in or after the production rooms leaves if the local conditions, i.e. the ambient temperature and the available space make such a measure seem reasonable. This process takes place expediently in a zone which is called a buffer zone can denote, and in which the means of transport also to lots (batches) for put the yarn into the cooling zone according to the invention can be. The preferred way of working is between the Spinning process and the cooling zone according to the invention to switch on a buffer zone, the existing differences between the coils' own temperature and the environment, possibly also the intrinsic moisture and the air humidity of the Takes advantage of the environment. In an air exchange process, the exhaust air from the cooling zone this upstream buffer zone are fed to the remaining cooling capacity exploit, as indicated in the attached figure is.

• eine Abladezone (A), wo die vorbereiteten Träger angeliefert werden, z.B. mittels eines Gabelstaplers;
• eine erste und eine zweite passive Vorkühl- und Pufferzone (jeweils mit B bezeichnet); in der dargestellten Ausführungsform wird diesen Vorkühl- und Pufferzonen Abluft aus der nachgeordneten Kühlkammer (C) zugeführt;
• eine Kühlkammer (C) mit zugeordneten - vor oder hinter der Zeichenebene angeordnet zu denkenden - Kälteanlagen (K);
• einen Vakuumbefeuchter (D), der mit einer Einrichtung zur Erzeugung des verminderten Drucks (V) und einem Dampferzeuger (W) ausgerüstet ist;
• eine Zone zur (passiven) Abkühlung (E);
• einer Wiegestation (F);
• eine Verpackungsstation (G), z.B., um die Ware mit einer Stretch-Folie zu umwickeln;
• einen Entnahmeplatz (H);

wobei an sich bekannte Fördermittel vorgesehen sind, die einen mindestens halbkontinuierlichen Durchsatz des zu kühlenden bzw. zu befeuchtenden Guts durch die Verfahrensstrecke ermöglichen.The process according to the invention is advantageously carried out in a device which can be referred to as a process section and which has zones schematically illustrated in the accompanying drawing:

• a unloading zone (A) where the prepared carriers are delivered, for example by means of a forklift;
• first and second passive pre-cooling and buffer zones (each designated B); in the embodiment shown, these pre-cooling and buffer zones are supplied with exhaust air from the downstream cooling chamber (C);
• a cooling chamber (C) with associated cooling systems (K) to be thought of, arranged in front of or behind the drawing plane;
• a vacuum humidifier (D) equipped with a device for generating the reduced pressure (V) and a steam generator (W);
• a zone for (passive) cooling (E);
• a weighing station (F);
• a packaging station (G), for example to wrap the goods with a stretch film;
• an extraction point (H);

where known conveying means are provided which allow an at least semi-continuous throughput of the goods to be cooled or moistened through the process section.

• Messung der Innentemperatur und Restfeuchte der zur Behandlung anstehenden Garnspulen,
• Messung der Luftfeuchte und der Raumtemperatur in der Vorkühl- und Pufferzone,
• Messung der Luftfeuchte und der Raumtemperatur in der aktiven Kühlzone.

There are also preferably means for

• Measurement of the internal temperature and residual moisture of the yarn packages to be treated,
• Measurement of air humidity and room temperature in the pre-cooling and buffer zone,
• Measurement of air humidity and room temperature in the active cooling zone.

• die Menge der durchzusetzenden Garnspulen,
• die unmittelbar nach der Produktion vorliegende Innentemperatur der Garnspulen sowie vorzugsweise der vorhandenen Restfeuchte,
• Raumtemperatur und Luftfeuchte in der passiven Kühl- und Pufferzone,
• Raumtemperatur und Luftfeuchte in der in der aktiven Kühlzone,
• einen Wert für die Abkühlungsgeschwindigkeit bei gegebener Raumtemperatur als Parameter,
• die Temperatur der aktiven Kühlzone und/oder mindestens einen Temperaturgradienten innerhalb der aktiven Kühlzone,
• die Geschwindigkeit der Rückbefeuchtung bei gegebener Restfeuchte und gegebener Spulentemperatur als Parameter, sowie
• gegebenenfalls weitere Informationen,

und dem Stellgrößen entnommen werden, mittels derer mindestens

• die Verweildauer der Spulen vor der Einführung in die aktive Kühlzone,
• die Verweildauer in der aktiven Kühlzone,
• die Kühlleistung bzw. Temperatur der Kühlkammer,
• die Verweildauer im Vakuumbefeuchter

derart gewählt werden können, dass mindestens eine der folgenden Größen ein Minimum wird:

• die Gesamtverweilzeit einer gegebenen Menge an Spulen in der Vorrichtung einschließlich der Vorkühlzone,
• der Kühlaufwand in der Kühlkammer,
• die Differenz zwischen dem handelüblichen Feuchtezuschlag r_t und der tatsächlichen Garnfeuchte.

There is also preferably a process computer which is supplied with information about

• the amount of spools of thread to be pushed through,
• the internal temperature of the yarn bobbins immediately after production and preferably the residual moisture present,
• Room temperature and humidity in the passive cooling and buffer zone,
• Room temperature and humidity in the active cooling zone,
• a value for the cooling rate at a given room temperature as a parameter,
• the temperature of the active cooling zone and / or at least one temperature gradient within the active cooling zone,
• the speed of remoistening for a given residual moisture and given coil temperature as a parameter, and
• if necessary, further information,

and the control values are taken, by means of which at least

• the dwell time of the coils before being introduced into the active cooling zone,
• the length of stay in the active cooling zone,
• the cooling capacity or temperature of the cooling chamber,
• the dwell time in the vacuum humidifier

can be chosen such that at least one of the following sizes becomes a minimum:

• the total residence time of a given amount of coils in the device including the pre-cooling zone,
• the cooling effort in the cooling chamber,
• the difference between the standard moisture surcharge r _t and the actual yarn moisture.

There are also preferably means that determine the cooling capacity of the cooling chamber limit in such a way that during the cooling phase the yarn packages do not or only a little moisture is extracted, for example, the deepest possible the associated refrigeration system evaporation point is set at 0 ° C.

With the method according to the invention or the arrangement provided therefor can in particular the required energy expenditure and / or the residence time in the active cooling can be minimized and the increase in moisture in the Spools of thread in a desired ratio to energy consumption and / or Dwell time.

Slight loss of moisture in the passive and / or active cooling zone can optionally additionally reduced by, for example, supplying steam-saturated air or be balanced.

a) auf Paletten gestapelt,

b) auf Dornenwagen aufgesteckt oder

c) in Kartons.

The spools of yarn coming from the spinning hall are generally located in groups of suitable means, for example

a) stacked on pallets,

b) attached to thorn car or

c) in boxes.

In semi-continuous operation, they are in a first buffer zone, which too can cause a pre-cooling by the ambient air, more suitable to batches Size compiled and fed to the active cooling zone.

a) einer thermisch möglichst gut isolierten Kühlkammer,

b) mindestens einer Kälteanlage, die für die Kühlung von Luft, Stickstoff oder Argon ausgelegt ist,

c) mindestens einem Geber für die Innentemperatur,

d) mindestens einem Geber für die Luftfeuchtigkeit,

e) Ventilatoren für Luftumwälzung und/oder Luftaustausch,

f) bedarfsweise Mitteln zur Befeuchtung der Betriebsluft der Kühlzone oder Kühlzonen,

g) fördertechnischen Mitteln wie Rollstrecken, Bändern und/oder Kettenförderern für den Transport der Träger (Paletten, Dornenwagen usw.).

The active cooling zone consists of:

a) a thermally well insulated cooling chamber,

b) at least one refrigeration system which is designed for cooling air, nitrogen or argon,

c) at least one sensor for the internal temperature,

d) at least one sensor for air humidity,

e) fans for air circulation and / or air exchange,

f) if necessary, means for humidifying the operating air of the cooling zone or cooling zones,

g) conveyor means such as roller tracks, belts and / or chain conveyors for the transport of the carriers (pallets, thorn carts, etc.).

The active cooling zone can be designed as a cooling chamber in the broadest sense; e.g. a cooling tunnel with sliders at both ends is just as suitable as a Boiler with a front cap designed as a gate, which receives the yarn carriers can. Before and especially after the cooling zone can serve as locks Routes may be provided. While in the first case the refrigerated goods through the in the Process tunnels lying on a conveyor system are passed a boiler is usually filled in batches and can be purchased on the entire process route, e.g. also be arranged laterally from this. The selected embodiment can also be based on existing devices judge that were intended for another purpose and for the invention Use should be set up.

The yarn packages are expediently located in a buffer zone upstream of the cooling zone preferably in each case for the capacity of the active ones behind Areas suitable for the cooling zone or the vacuum humidifier, i.e. also several Pallets / mandrel wagons / boxes etc. put together and together using Conveyors in the cycle (i.e. semi-continuous) these work zones fed and enforced by this. Possibly the compilation also take place after this buffer zone. The active cooling zone and the Vacuum humidifiers can have a different absorption capacity at all have, however, it should be noted that there are not too large dwellings and Transport times between these components occur so that the cooling effect does not is lost again. After leaving the vacuum humidifier, the Spools of thread may have been removed from the mandrel carriage, weighed and the Storage fed. When arranged on pallets or in boxes, one can Separation from these means of transport is advantageously eliminated. If necessary the funding is returned to the entrance of the process route.

Depending on the design, the cooling zone can accommodate one or more lots. The necessary cooling capacity results from the dwell time, the amount of yarn and the desired temperature. It can be useful, especially if you already have one Humidification systems, the active cooling zone according to the invention in several to split parallel units. This can also be done from the point of view of Availability of existing facilities on the market can be given the needs of the method according to the invention can be set up.

When the ambient temperature is low, i.e. active cooling only need to perform relatively low, it may be appropriate to Operating air intended for the active cooling zone to achieve a higher relative Humidify before or after the cooling process while through the cooling of operating air from a high ambient temperature to the operating temperature generally a sufficient increase in relative humidity is achieved.

The method is advantageously operated in such a way that by controlling the active Cooling zone optionally either a reduction in temperature during a preselected (constant) time or a reduction to a constant Temperature (variable time) can be set. The cooling capacity should be on the expected Parameters can be matched.

Claims (11)

Process for moistening or rewetting (conditioning) textile materials, in particular textile yarns, which during spinning have lost moisture during spinning to a residual moisture which is lower than the original moisture during spinning due to the action of water vapor under reduced pressure the textile material or yarn, characterized in that the textile material is subjected to active cooling in a separate room or zone before the action of water vapor. A method according to claim 1, characterized in that the residual moisture in cotton is between 0 and 5 percent by weight. A method according to claim 1, characterized in that yarns processed into yarn packages are pre-cooled or moistened and the yarn packages are arranged in part on support frames. A method according to claim 1, characterized in that the air temperature to which the refrigerated goods are exposed is at least 10 degrees below the ambient temperature, but above 0 ° C. A method according to claim 4, characterized in that the air temperature to which the refrigerated goods are exposed is at least 20 degrees below the ambient temperature, but above 0 ° C. A method according to claim 1, characterized in that the initial temperature of the saturated steam is set to 68 ° C or less in a manner known per se. A method according to claim 1, characterized in that the duration of the cooling is between 10 minutes and two hours. A method according to claim 7, characterized in that the cooling time is between 20 and 40 minutes. A method according to claim 1, characterized in that the cooling is preceded by passive precooling if the ambient temperature is lower than the average temperature of a yarn package such that the yarn packages are exposed to the ambient temperature until the average package temperature is at least 1 degree lower than before exposure to ambient temperature. Arrangement for carrying out the method according to one of claims 1 to 9, characterized in that it comprises a plurality of zones or stations along a process route: optionally a passive pre-cooling zone or station, at least one active cooling zone or station, in which the cooling is operated as air cooling in at least one closable cooling space or a cooling section separate from the humidification device, to which a humidification device is spatially connected, at least one vacuum humidifier as humidification device, where known conveying means are provided which allow an at least semi-continuous throughput of the material to be moistened through the process section. Arrangement according to claim 10, characterized in that the cooling air is moved within the cooling zone or station and is guided such that the coils are washed around by the cooling air on all sides.

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