US3528180A - Method of treating fibrous or filamentary material - Google Patents

Description

P 1970 F. w.J. KARRER T L 3,528,

METHOD OF TREATING FIBROUS OR FILAMENTARY MATERIAL Filed March 25, 1968 2 Sheets-Sheet 1 STEAM I N VEN TOR 5.

FRIEDRICH WILHELM JOHANN KARRER, ALBERTQ PEDRETTI the r Sept. 15, 1970 w, J, KARRER ET AL 1 3,528,180

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z\ k us 1 N v a N E: 9 4 M a n '45 N e I G :3 m g Q g N s I m a 3 T h as Lg a INVENTORS.

FRIEDRICH WILHELMI JOHANN KARRER ALBERTO PEDRETTI their uropmsrs United States Patent 3,528,180 METHOD OF TREATING FIBROUS 0R FILAMENTARY MATERIAL Friedrich Wilhelm Johann Karrer, Strandvagen 37, Stockholm 0, Sweden, and Alberto Pedretti, Via Chelini 9, Rome, Italy Filed Mar. 25, 1968, Ser. No. 715,782 Claims priority, application Sweden, Jan. 18, 1968, 665/68 Int. Cl. F26b 3/00 US. Cl. 34-9 Claims ABSTRACT OF THE DISCLOSURE A method of treating fibrous or filamentary materials in a closed container in which two chambers are formed and the only communiction between the chambers is through the material. The material is first treated with one or more liquid treating agents, such as dye, bleach, and wash, and is then dried. The drying procedure is composed of an initial phase in which both air and steam are simultaneously passed through the material by establishing a pressure difference between the two chambers, the air and steam being introduced in a proportion such that a minimum amount of steam leaves the downstream side of the material and the major portion of the steam is condensed to transfer the heat of vaporization thereof into the material. The air serves both to mechanically expel moisture from the material and as a condensing assistant for the transfer of heat. When the material has been preheated and mechanically dried to a maximum practical degree, further drying is accomplished substantially by vaporization of moisture from the material by passing hot air through it. In the later phases of the drying procedure, a small amount of steam may also be introduced with the hot air to add heat and thereby provide a greater rate of vaporization.

BACKGROUND OF THE INVENTION This invention relates to a method of treating fibrous or filamentary materials, particularly textile materials in the form of a spool or roll, such as a cross-wound spool of yarn or a roll of fabric or randomly distributed fibers.

There are many specific techniques for treating rolls or spools of textile materials with liquids, particularly dyeing and bleaching treatments. After these processes the material must be dried, and particular problems are encountered in obtaining rapid, efiicient, low cost drying. A number of previously proposed techniques for drying rolls or spools of textile materials employ containers which are formed with two chambers and in which the material is disposed in such a way as to communicate the two chambers solely across the material. For example, the container structure may include perforated tubular elements constituting one chamber in the container and receiving the rolls or spools in surrounding relation. The external surfaces of the spools are thus exposed to the other chamber in the container, and communication between the two chambers is solely through the material wound on the rolls or spools.

The material has conventionally been dried by passing a gaseous drying medium through it. The techniques in this regard have varied. For example, one drying procedure op erates under relatively high pressure, say five atmospheres, and uses superheated steam as a drying medium during the initial phase of the drying procedure and heated air in the later stages. Other methods use heated air alone and operate at various rates and under various conditions to evaporate moisture. Some of the specific techniques previously proposed have provided reasonably good results,

3,528,180 Patented Sept. 15, 1970 but they require considerable amounts of energy in the form of heat and pressure and therefore tend to be costly to carry out. Moreover, the high temperatures, particularly in closed circuit systems, can adversely affect various components of the equipment, notably compressors, particularly where the compressors are handling superheated steam. In any case, the procedures heretofore proposed and used have frequently involved passing considerable quantities of air or steam through the material without efficient utilization of the heat content of these media, thereby considerably reducing the efiiciency of energy utilization. For example, where steam is used in the drying process, only a relatively minor proportion of the heat content of the steam is transferred to the material to assist in removing moisture from the material, the major portion of the steam passing through the material and being lost or conducted elsewhere for some other use. Moreover, in a closed circuit system, the condensor does not remove all of the vapor particles so that the drying air is highly moist and its ability to receive moisture from the material is correspondingly impaired.

SUMMARY OF THE INVENTION There is provided, in accordance with the invention, a novel and improved method of treating fibrous and filamentary materials, and particularly a method of drying the materials after a liquid treating process. The method provides substantial improvements in the efliciency of the drying procedure as compared to those previously proposed or used.

More particularly, the method is carried out utilizing a container which is composed of two chambers and in which the material forms the only path of communication between the two chambers. Preferably, both the liquid treatment and the drying of the material are accomplished in the same container utilizing a single compressor for establishing pressure differences between the chambers. The liquid treatment is accomplished by reducing the pressure in the container first to draw air out of the material and then to suck the liquid treating medium into the container through the material. The liquid treating material can also be pumped back and forth between the chambers repeatedly across the material using a circulation system, and can ultimately be expelled from the vessel by positive pressure from the compressor, followed by applying vacuum to suck out any remaining liquid.

After the liquid treatment phase, the material is dried, according to the invention, by introducing both steam and air into one of the chambers during at least part of the procedure and causing the air and steam to pass through the material by establishing and maintaining a pressure difference between the two chambers. During the initial phases of drying when the material is saturated and at the temperature of the last liquid treatment (usually a cold water wash), the air and steam are passed across the material to expel the moisture from it by primarily mechanical action and to heat the material so that further drying by vaporization of the moisture is facilitated. In the later stages of drying where the moisture is removed from the material by vaporization, it is desirable to continue to use both steam and air, the steam, however, being introduced in relatively small amounts to add heat to the material to assist in vaporizing the moisture.

Wherever both air and steam are simultaneously utilized in the drying procedure, the steam is introduced in only relatively small amounts as a source of heat, the major constituent of the drying medium being air. During the initial phase of drying, the steam is preferabl kept at a level such that substantially all of the steam is condensed in the container and a minimum amount leaves the downstream side of the material. Thus, the heat of vaporization of the steam is transferred into the material to increase its temperature to slightly above the boiling point under the existing pressure conditions. The air serves as a carrier for the steam, aids in condensing the steam to recover heat from it, and is a recipient of and carrier for the vapor evolved from the material.

In the initial stage of the drying procedure, according to the invention, it is preferable to employ a relatively cold air, such as air drawn directly from the atmosphere. In combining with the steam in the container, and particularly in the material, the relatively cool airacts as a condensing agent for the steam and provides for recovery of the heat of vaporization from the steam and heat transfer into the material for rapid preheating. The heating of the moisture in the material also reduces its viscosity and facilitates its removal.

In the final stage of the drying procedure, i.e., the part of the drying procedure after the moisture in the material has begun to boil under the prevailing conditions, hot air, preferably obtained by preheating air drawn directly from the atmosphere, and preferably a small amount of steam, are used. The final stage of drying may also use hot air alone, i.e., without steam. The temperature of the air should be high enough that the steam does not condense in the chamber during the later drying stages.

The air and steam, or where employed, air alone are preferably drawn through the material during the entire drying process by reducing the pressure in the chamber on the downstream side of the material to below atmospheric. The reduced pressure in the downstream chamber should be kept sufiiciently low during the final stage that the moisture in the material boils. Thus the moisture is removed from the material primarily by boiling. The pressure in the upstream chamber is maintained at a higher level to cause transfer of heat to the material to enable the drying thereof to take place. The pressure in the upstream side is desirably just slightly less than atmospheric.

A particular advantage of the treating method of the invention is that it is well suited for effecting drying in the same apparatus as used for a preceding liquid treatment of the fibrous or filamentary material, for instance, dyeing or bleaching, particularly when, for the purpose of hastening the said treatment, there is connection to a vacuum pump for evacuating the container. A plant in which the treatment apparatus is connected to a pump unit functioning at different times as a compressor and vacuum pump is particularly suited to such a process, the suction and pressure sides of the pump being alternately brought into connection with the treatment apparatus for providing the respective evacuation and rise in pressure.

Significant improvements in efficiency are obtained, particularly in the initial preheating stage by utilizing to a maximum the heat input of the steam in heating the material and in permitting only a minimum of steam to pass straight through the equipment. Because most of the steam is condensed before the outfiowing gases reach the compressor unit, the volume of fluids handled by the pump is substantially reduced as compared to systems in which large quantities of steam pass through a compressor. Similar results are obtained in the later drying stages. Moreover, the compressor is not subjected to as severe heating. The power requirements for the compressor are similarly reduced by the reduced volume of fluids being handled.

DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference may be made to the following description of an exemplary embodiment, taken in conjunction with the figures of the accompanying drawings, in which:

FIG. 1 is a generally schematic illustration of a con- 4 tainer and associated components useful in carrying out the method of the invention, the view showing the container in cross-section; and

FIG. 2 is a schematic diagram of equipment for dyeing, bleaching and drying a material according to an exemplary method.

DESCRIPTION OF EXEMPLARY EMBODIMENT Referring first to FIG. 1, the principal component of equipment for carrying out the method of the invention is a well insulated container 1 for the material to be treated. Disposed in the lower portion of the container 1 is a closed inner chamber 3 which is connected to a vacuum pump 4 by a conduit 5. Material supports 6 in the form of perforated tubes open at the lower end but closed at the top are mounted on the chamber 3 and communicate with the interior of the Same. The material supports 6 are adapted to support crosswound spools 7, rolls or the like. The main chamber 8 of the container surrounding the spools 7 communicates with an inlet conduit 9, a heat exchanger 10 heated, for example, by means of steam being installed in the conduit, and with a steam line 11.

FIG. 2 shows diagrammatically a plant for dyeing, bleaching and drying textile material which incorporates the basic apparatus of FIG. 1. The plant includes a container 21, which is substantially the same as the container described in FIG. 1 and receives stationarily arranged material to be treated, e.g., cross-wound spools or fabric rolls, a container 22 for liquid dye, and a container 23 for bleaching liquid.

Connected to the treatment container 21, which may be heat insulated or provided with a steam jacket for heating the material during and/or prior to the process, is a circulation system comprising a conduit 24, which is provided with a cut-off valve 25, a heat exchanger 26 adapted to be heated by water or steam supplied through a conduit 27, a conduit 28, a circulation pump 29 and its valve, and a conduit 30 provided with a valve 31. The conduit 30 is the counterpart of the conduit 5 in the container of FIG. 1 and communicates with the chamber 3 and thence with the interior of each material support tube 6 (see FIG. 1) in the container 21, while the conduit 24 communicates with the main chamber 8 surrounding the material.

The liquid dye container 22 is provided with an outlet 32 having a cut-off valve 33 and a discharge conduit 34 by means of which liquid dye can be transferred to the treatment container 21 by means of the circulation system through a conduit 35 having a cut-off valve 36. The liquid dye container 22 also communicates with the treatment container 21 through a conduit 37 provided with a valve 38.

The bleaching liquid container 23 has an outlet 39 provided with a cut-off valve 40. The bleaching liquid can be transferred from the container 23 through a conduit 41 having a valve 42 and a conduit 43 connected to the conduit 30. Further, connected to the conduit 43 is an outlet conduit 44 provided with a cut-off valve 45 and a water supply conduit 46 provided with a cut-off valve 47.

Also connected to the main chamber 8 of the container 21 is a conduit 48, which is provided with a valve 49 and communicates with one branch 51a of a 4-way valve 51. A second branch 51b of the valve 51 is connected to the suction side of a compressor and vacuum pump unit 52 through a conduit 53, and a third branch 51c communicates with the pressure side of the pump unit 52 via a conduit 55 which has a water-separator 54. The fourth branch 51d is an outlet conduit 56 for exhaust air and may lead to the atmosphere or to any suitable place where hot air might find use. The 4way valve 51 can be shifted so that the container 21 is placed in communication with the pressure side (the position shown in FIG. 2) of the pump unit 52, or with its suction side. A conduit 59 provided with a cut-off valve 60 connects the conduit 30 with the conduit 48. An air inlet conduit 50, equipped with a valve 50a and a heat exchanger 57, and a steam supply line 58 having a cut-off valve 58a lead into the main chamber 8 (see FIG. 1) of the container 21.

The procedure employed to dye material using the equipment of FIG. 2 begins after the material has been introduced into the container 21 by placing the container in communication with the suction side of the pump unit 52 by shifting the 4-way valve 51 to connect branches 51a and 51b so that the container is evacuated through lines 30, 59 and 53. At this point, all valves other than valve 60 are closed, the heat exchangers are shut 01f, and the pump 29 is not operating. When a maximum vacuum in the container has been reached, dyeing liquid is drawn or sucked into the treatment container 21 from the dye container 22 until the material in the container 21 is completely covered with the liquid. The heat exchanger 26 is then started up and circulation by means of the circulation pump 29 of dye through the material is begun. The 4-way valve 51 is shifted to the position shown in FIG. 2, and the valve 49 opened so that the container 21 can be subjected to positive pressure. The positive pressure can be maintained during the whole of the circulation process, or merely for a portion of the same. Further, in certain cases it may be suitable to subject the container 21 alternately to positive pressure and sub-pressure by shifting the valve 51 appropriately.

On completion of the dyeing process and when the circulation has been stopped, the used liquid dye can be removed through the conduits 30, 43 and 44 by the aid of positive pressure in the container 21 or, if so desired, returned to the container 22 through the conduit 37. Water for washing the material can then be supplied from the conduit 46, by first re-connecting the container 21 to the suction side of the pump unit 52 and evacuating it, then admitting the water and finally pulling it out by vacuum and discharging it to the separator 54, from which it may be removed. Alternatively, the water can be pushed out by positive pressure just as the dye and bleach are (see above). The wash process is repeated until the material has been properly washed.

Bleaching is in principle effected in the same way as that described above, after bleaching liquid from the container 23 has been introduced into the container 21 and surplus bleaching liquid returned, by means of positive pressure, to the container 23. The material may be heated during bleaching processes according to my patents U.S. Nos. 2,808,715 and 2,959,047 by introducing steam and hot or cold air and drawing them through the material in the container 21 by suction from the unit 52. Air may be injected particularly in the case of hypochlorite bleaching, the carbon dioxide of the air hastening the bleaching process. Air can also be injected on completion of the dyeing process to neutralize certain pigments.

After completing the dyeing, washing and bleaching treatments, the drying of the material is started by placing the container in communication with the suction side of the compressor unit 52 through the conduit 59, valve 51 and conduit 53 by simultaneously introducing air and steam into the container through the conduits 50 and 58, respectively. The initial phase of the drying process is a mechanical dewatering and preheating stage in which the air and steam are drawn through the material in a manner mechaniclly removing the major portion of the moisture in the then saturated material and in which the material, which is then usually at the temperature of the bleach, or dye or a final wash, is raised to slightly above the boiling point for the conditions obtaining in the container. The proportion of air and steam is preferably established such that substantially all of the steam is condensed in the material and will generally be between 1:1 and 15:1 by weight. The air may be relatively cool and desirably is drawn directly from the atmosphere without any preconditioning, other than filtering. As the steam and air pass through the material, the steam is condensed by the air and the relatively cool material so that substantially all of the steam is condensed and its heat of vaporization is transferred into the material. The optimum conditions, in general, exist when a minimum amount of steam is leaving the downstream side of the material. The steam is desirably superheated so that additional heat is introduced upon expansion in the container and so that minimum condensation occurs in the chamber 8 prior to entry of the air and steam into the material. If chemical residues remain on the fibers, the condensing steam aids in dissolving and washing them away, so that the previous Washing step can be shortened.

The passage of the air and steam through the material is effected by reducing the pressure in the chamber 3 by means of the compressor unit 52. The pressure in the chamber 3 may be on the order of 0.5 to 0.7 atm. The pressure in the main chamber 8 of the container will be somewhat higher due to the resistance of flow through the material, say on the order of 0.1 to 0.3 atm. higher than in the chamber 3. Desirably, the main chamber is at or only slightly below atmospheric pressure.

The introduction of air and steam to mechanically dewater and to preheat the material is continued until the temperature of the material has been raised sufficiently so that a favorable condition for the further process is achieved. When this point has been reached, further drying is accomplished by introducing hot air into the main chamber, preferably along with a minor amount of steam to add additional heat to the material as drying proceeds. Nevertheless, hot air alone may be used from this point on, or steam may be introduced only periodically. Where steam is used, it is preferably superheated and is intro duced in proportions relative to the air introduced with it, ranging from preferably about 1:10 to 1:100 by weight. The pressure conditions are maintained substantially as in the preheating stage. The air used for further drying is drawn in through the inlet conduit 50 and is heated by the heat exchanger 57, which is turned on at the point when hot air is to be used subsequently, to a temperature above the boiling point in the chamber but not so high as to damage the material. Where steam is used, it will be noted that the hot air does not permit condensation of the steam in the container. Nonetheless, the steam will condense out in the vacuum pump. Its volume per unit heat input is small, and the vacuum pump can therefore be of lower capacity than if hot air alone were used. Drying with hot air is continued to completion of drying as indicated by the temperature of the vaporladen air leaving the chamber 3.

A typical example of the drying process as applied to spools of cotton yarn is as follows: When drying begins, the yarn is saturated with wash water to about 200%. The suction side of the compressor unit 52 is brought into communication with the chamber 3, as above, and the introduction of air and steam into the main chamber of the container is commenced. The proportion of air to steam is on the order of 7:1 by volume, and the steam is superheated to 120 C. The compressor is operated to provide a pressure of approximately 0.7 atm. in the chamber 3 so that with a pressure of 0.3 atm. across the material the main chamber in the container is at substantially atmospheric pressure. The mechanical dewatering and preheating of the yarn under these conditions takes approximately five minutes, and completion ofthe initial stage of drying is indicated by a temperature of the vaporladen air leaving the chamber 3 of C. This temperature is indicative of a temperature on the outside of the spools of about C.

At this point, the heat exchanger 57 is turned on so that the air conducted into the container is preheated. The temperature of the heated air used during the remainder of the drying procedure should be slightly over 100 C. During the later drying, a small amount of steam, say one part to 50 parts air, superheated to say C. can be introduced simultaneously with the air to add further heat to the material, although this is optional.

7 The drying of the material using hot air, and preferably a small amount of steam is continued to completion, and it has been found to take on the order of one hour.

The above-described embodiment of the invention is intended to be merely exemplary, and those skilled in the art will be able to make numerous variations and modifications of it without departing from the spirit and scope of the invention.

We claim:

1. A method of treating fibrous or filamentary materials in a closed container in which two chambers are formed and the only communication between the chambers is through the material comprising as at least part of a drying procedure the steps of establishing and maintaining a pressure difference between the chambers effective to conduct a gaseous drying agent through the material, simultaneously introducing in the initial stage of the drying procedure both air and steam into the higher pressure chamber partially to dry the material by primarily a mechanical action and to preheat the material to a temperature facilitating later drying primarily by vaporizing the moisture in the material, the air and steam being introduced in a proportion such that a minimum amount of steam leaves the downstream side of the material and the major portion of the steam is condensed in the material thereby to transfer the heat of vaporization thereof into the material, the steam being superheated to an extent such that minimum condensation takes place in the chamber prior to entry into the material on the upstream side thereof, and thereafter in the later stages of drying introducing heated air into the said one chamber to further dry the material primarily by vaporizing the moisture therein.

2. A method according to claim 1 wherein the proportion by weight of air to steam introduced during the said initial stage of drying is between about 1:1 and :1.

3. A method according to claim 1 wherein the steam introduced during the initial stage of the drying procedure is superheated to a temperature of about 120 C.

4. A method according to claim 1 wherein the initial stage of the drying procedure in which the drying of the material is primarily by a mechanical action is carried out until the temperature of the vapor-laden air measured in the downstream chamber of the container, relative to the flow of gaseous drying agent through the material, reaches a value of about C.

5. A method according to claim 1 wherein the air introduced in the said later stages of drying is introduced at a temperature above C.

6. A method according to claim 1 wherein the proportions of air to steam introduced in the later stages of the drying procedure is from about 10:1 to 100:1 by weight.

7. A method according to claim 1 wherein the air introduced during the said initial stage of the drying procedure is at a temperature substantially below the temperature of the steam, thereby to aid in condensing the steam.

8. A method according to claim 1 wherein the air is introduced during both of said stages of the drying procedure at atmospheric pressure, and wherein the pressure difference between the chambers is created by reducing the pressure in the other one of said chambers to below atmospheric pressure.

9. A method according to claim 1 wherein steam is introduced simultaneously with air during at least a part of the said later stages of the drying procedure to add heat to the material to aid in the vaporization of the moisture therefrom.

10. A method according to claim 1 further comprising the step of treating the material with a liquid prior to the drying procedure by conducting the liquid between the chambers through the material.

References Cited UNITED STATES PATENTS 630,293 8/ 1899 Maertens 3415 X FOREIGN PATENTS 494,838 7/1950 Belgium.

JOHN J. CAMBY, Primary Examiner US. Cl. X.R.

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