Title:
COTTON PROCESSING WITH IMPROVED PROCEDURE FOR REDUCING THE BYSSINOTIC EFFECT THEREOF
United States Patent 3802030
Abstract:
A process of treating cotton intended for spinning to reduce the byssinotic effect thereof in the subsequent conventional procedures leading up to the spinning operation which comprises subjecting the cotton to an environment containing dry steam at a temperature and for a time period sufficient to bring the cotton to a temperature of at least approximately 100° C without appreciably wetting the same.
US Patent References:
Process and apparatus for controlling the moisture content of seed cotton
Bryant - December 1957 - 2815537
Process and apparatus for treating materials with a fluid which is under pressure
Fleissner - May 1967 - 3319275
Process and apparatus for controlling the moisture content of seed cotton
Bryant - December 1957 - 2815537
Process and apparatus for treating materials with a fluid which is under pressure
Fleissner - May 1967 - 3319275
Application Number:
05/249340
Publication Date:
04/09/1974
Filing Date:
05/01/1972
View Patent Images:
Export Citation:
Assignee:
Burlington Industries (Greensboro, NC)
Primary Class:
Other Classes:
68/5D, 8/149.300
International Classes:
D01G37/00; D01B3/04
Field of Search:
19/66R,66CR,41 68/5D 8/156,149.3 34/210,218,227,22,26,36,37
Primary Examiner:
Newton, Dorsey
Attorney, Agent or Firm:
Cushman, Darby & Cushman
Claims:
What is claimed is
1. A process of converting raw cotton into a supply of cotton bales for subsequent processing through conventional carding and spinning procedures with a substantially reduced byssinotic effect comprising the steps of ginning the raw cotton to obtain a supply of seedless cotton, forming a supply of cotton bales from the supply of seedless cotton, and subjecting one of the aforesaid supplies of cotton obtained after said ginning step to an environment containing dry steam at a temperature and for a time sufficient to bring the one cotton supply to a temperature of at least approximately 100° C without appreciably wetting the same to thereby render said one supply of cotton capable of being subsequently processed through a conventional carding step without detrimentally affecting the speed of such subsequent processing or the quality of the fibers produced by such processing while substantially reducing the byssinotic effect resulting from such processing.
2. A process as defined in claim 1 wherein the supply of seedless cotton obtained in said ginning step comprises a substantially continuous supply of cotton in generally loose form which constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone having an inlet end and a discharge end, said substantially continuous supply of cotton in loose form being subjected to said dry steam environment by progressively compressing the same into the inlet end of said zone while progressively loosening and conveying away compressed cotton from the discharge end of said zone.
3. A process as defined in claim 1 wherein the supply of seedless cotton obtained in said ginning step comprises a substantially continuous supply of cotton in lap form which constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone, said substantially continuous supply of cotton in lap form being subjected to said environment by continuously conveying the same through said treatment zone while maintaining the lap form thereof.
4. A process as defined in claim 1 wherein the supply of cotton bales constitutes said one supply of cotton, said supply of cotton bales being subjected to said dry steam environment by repetitively (1) placing at least one cotton bale from said supply into a pressure chamber, (2) alternately, evacuating said pressure chamber and passing dry steam into said chamber under pressure and (3) recovering the number of said cotton bales placed in said pressure chamber therefrom.
5. A process of converting a supply of cotton bales into carded sliver form for subsequent spinning with a substantially reduced byssinotic effect comprising the steps of opening the supply of cotton bales to obtain a supply of loose cotton, converting the supply of loose cotton into a supply of cotton in lap form, carding the supply of cotton in lap form to obtain a supply of cotton in sliver form, and subjecting one of said supplies of cotton prior to said carding step to an environment containing dry steam at a temperature and for a time sufficient to bring the one cotton supply to a temperature of at least approximately 100° C without appreciably wetting the same to thereby render said one supply of cotton capable of being subsequently processed through said carding step without detrimentally affecting the speed of such subsequent processing or the quality of the fibers produced by such processing while substantially reducing the byssinotic effect resulting from such processing.
6. A process as defined in claim 5 wherein the supply of loose cotton constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone having an inlet end and a discharge end, said supply of loose cotton being substantially continuous and being subjected to said dry steam environment by progressively compressing the same into the inlet end of said zone while progressively loosening and conveying away compressed cotton from the discharge end of said zone.
7. A process as defined in claim 5 wherein said supply of cotton in lap form constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone, said supply of cotton in lap form being subjected to said environment by continuously conveying the same through said treatment zone while maintaining the lap form thereof.
8. A process as defined in claim 5 wherein the supply of cotton bales constitutes said one supply of cotton, said supply of cotton bales being subjected to said dry steam environment by repetitively (1) placing at least one cotton bale from said supply into a pressure chamber, (2) alternately, evacuating said pressure chamber and passing dry steam into said chamber under pressure and (3) recovering the number of said cotton bales placed in said pressure chamber therefrom.
9. A process as defined in claim 5 wherein the supply of loose cotton which is converted into a supply of cotton in lap form is blended with other fibers in loose form prior to the conversion step and the supply of loose cotton obtained in said blending step constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone having an inlet end and a discharge end, said supply of cotton in loose form being subjected to said dry steam environment by progressively compressing the same into the inlet end of said zone while progressively loosening and conveying away compressed cotton from the discharge end of said zone.
1. A process of converting raw cotton into a supply of cotton bales for subsequent processing through conventional carding and spinning procedures with a substantially reduced byssinotic effect comprising the steps of ginning the raw cotton to obtain a supply of seedless cotton, forming a supply of cotton bales from the supply of seedless cotton, and subjecting one of the aforesaid supplies of cotton obtained after said ginning step to an environment containing dry steam at a temperature and for a time sufficient to bring the one cotton supply to a temperature of at least approximately 100° C without appreciably wetting the same to thereby render said one supply of cotton capable of being subsequently processed through a conventional carding step without detrimentally affecting the speed of such subsequent processing or the quality of the fibers produced by such processing while substantially reducing the byssinotic effect resulting from such processing.
2. A process as defined in claim 1 wherein the supply of seedless cotton obtained in said ginning step comprises a substantially continuous supply of cotton in generally loose form which constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone having an inlet end and a discharge end, said substantially continuous supply of cotton in loose form being subjected to said dry steam environment by progressively compressing the same into the inlet end of said zone while progressively loosening and conveying away compressed cotton from the discharge end of said zone.
3. A process as defined in claim 1 wherein the supply of seedless cotton obtained in said ginning step comprises a substantially continuous supply of cotton in lap form which constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone, said substantially continuous supply of cotton in lap form being subjected to said environment by continuously conveying the same through said treatment zone while maintaining the lap form thereof.
4. A process as defined in claim 1 wherein the supply of cotton bales constitutes said one supply of cotton, said supply of cotton bales being subjected to said dry steam environment by repetitively (1) placing at least one cotton bale from said supply into a pressure chamber, (2) alternately, evacuating said pressure chamber and passing dry steam into said chamber under pressure and (3) recovering the number of said cotton bales placed in said pressure chamber therefrom.
5. A process of converting a supply of cotton bales into carded sliver form for subsequent spinning with a substantially reduced byssinotic effect comprising the steps of opening the supply of cotton bales to obtain a supply of loose cotton, converting the supply of loose cotton into a supply of cotton in lap form, carding the supply of cotton in lap form to obtain a supply of cotton in sliver form, and subjecting one of said supplies of cotton prior to said carding step to an environment containing dry steam at a temperature and for a time sufficient to bring the one cotton supply to a temperature of at least approximately 100° C without appreciably wetting the same to thereby render said one supply of cotton capable of being subsequently processed through said carding step without detrimentally affecting the speed of such subsequent processing or the quality of the fibers produced by such processing while substantially reducing the byssinotic effect resulting from such processing.
6. A process as defined in claim 5 wherein the supply of loose cotton constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone having an inlet end and a discharge end, said supply of loose cotton being substantially continuous and being subjected to said dry steam environment by progressively compressing the same into the inlet end of said zone while progressively loosening and conveying away compressed cotton from the discharge end of said zone.
7. A process as defined in claim 5 wherein said supply of cotton in lap form constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone, said supply of cotton in lap form being subjected to said environment by continuously conveying the same through said treatment zone while maintaining the lap form thereof.
8. A process as defined in claim 5 wherein the supply of cotton bales constitutes said one supply of cotton, said supply of cotton bales being subjected to said dry steam environment by repetitively (1) placing at least one cotton bale from said supply into a pressure chamber, (2) alternately, evacuating said pressure chamber and passing dry steam into said chamber under pressure and (3) recovering the number of said cotton bales placed in said pressure chamber therefrom.
9. A process as defined in claim 5 wherein the supply of loose cotton which is converted into a supply of cotton in lap form is blended with other fibers in loose form prior to the conversion step and the supply of loose cotton obtained in said blending step constitutes said one supply of cotton, said dry steam environment being established by continuously passing dry steam through a treatment zone having an inlet end and a discharge end, said supply of cotton in loose form being subjected to said dry steam environment by progressively compressing the same into the inlet end of said zone while progressively loosening and conveying away compressed cotton from the discharge end of said zone.
Description:
This invention relates to the processing of cotton up to and through the point of spinning and more particularly to improved procedures in such processing for reducing the byssinotic effect theretofore experienced in such processing.
Conventional cotton processing has always had an adverse effect on the pulmonary function of personnel working with it. Since the advent of mechanization of cotton harvesting in the field, there has been a noticeable increase in this adverse effect. The effect is more prominent with personnel working the opening, blending and carding than in subsequent operations. This adverse effect gives rise to what is known as byssinosis and the effect has been referred to as the byssinotic effect of cotton.
In recent years, a considerable effort has been made to reduce the instances of byssinosis occurring in personnel working in the cotton processing industry. Early researchers noted that the processing of surgical cotton did not produce a byssinotic effect. However, the processing of surgical cotton did not involve the same type of carding operation utilized in conventional processing of cotton to the point of spinning. In the processing of surgical cotton, the cotton is subjected to a washing treatment, the washing solution containing primarily heated water with some chemicals such as three percent sodium hydroxide or the like. Proceeding on the basis that it was this washing process utilized with surgical cotton which accounted for the absence of a byssinotic effect, eperimental efforts have been made to develop a washing treatment for cotton which is to be processed through the conventional steps to the point of spinning. Experiments of this nature were carried out under the direction of Dr. James A. Merchant and did, in fact, show that the byssinotic effect of cotton could be substantially reduced by washing the cotton in a manner similar to the washing process performed with surgical cotton. In these experiments, after the washing process had been performed, the washed cotton was then dried at 325° F. for 10 minutes. These washing experiments were also repeated with water as the sole washing medium. While the byssinotic effects of the cotton were substantially reduced, the dry cotton was in such a matted condition that the subsequent carding of the same could not be practically performed. Additional tests under the direction of Dr. Merchant were performed where the cotton was steamed in a vat with wet steam and then likewise dried at 325° F. for 10 minutes. Here, again, the results showed that the byssinotic effect of the cotton was substantially reduced. However, while the resultant cotton could be processed through the carding machine more readily than that obtained by the washing treatment, nevertheless, the carding operation could not be performed at production speeds. Moreover, the resultant carded cotton was reduced in fiber length and exhibited considerably more neps than the same cotton which was not subjected to the steaming treatment.
An object of the present invention is to provide an improved procedure in the conventional processing of cotton up to the point of spinning for reducing the byssinotic effect thereof during each processing, which procedure is compatible with existing production speeds and has no substantial effect on the quality of the cotton produced. In accordance with the principles of the present invention, this objective is obtained by subjecting the cotton to an environment of dry steam at a temperature and for a time period sufficient for the cotton to reach at least approximately 100° C. In accordance with the principles of the present invention, this treatment can be performed either at the gin or at the spinning mill with the cotton in loose form, in lap form, or in bale form. The process is readily capable of being performed at rates compatible with production rates utilized in conventional processing both at the gin and at the spinning mill.
Another object of the present invention is the provision of an improved procedure in a conventional cotton processing line which will reduce the byssinotic effect in subsequent steps of the conventional process and which can be economically carried out without materially affecting the production rate of the processing line or the quality of the cotton produced therein.
These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.
The invention may best be understood with reference to the accompanying drawing wherein a schematic flow diagram of the procedures of the present invention is illustrated.
With reference to the drawing, it will be noted that the conventional cotton processing steps are indicated in general sequential order by a box flow diagram on the left-hand portion of the drawing. As indicated, the process steps included are those performed conventionally at the gin as well as at the spinning mill. The process at the spinning mill is shown up to the point of obtaining a sliver from the carding machine. Past experience has indicated that the greatest byssinotic effect occurs in the carding room and, consequently, in order for the present treatment to be of substantial effect, it must be performed before the carding operation. As indicated in the block diagram, the steps at the gin would include the feeding of a supply of raw cotton through the gin which produces a supply of seedless cotton. The present invention contemplates that the ginning operation can be carried out by conventional machines which produce the supply of seedless cotton in loose form as well as those conventional machines which produce the seedless cotton in lap form. In any event, the supply of seedless cotton is then conventionally fed to the bale press. A typical feed rate of loose cotton from the gin to the bale press is approximately 3,000 lbs. per hour and above. Where the gin produces seedless cotton in lap form, a typical feed rate to the bale press is approximately 500 lbs. per hour and above. From the bale press, a supply of cotton bales is obtained. A typical outfeed rate of a baling press is approximately six bales per hour, each of which contains approximately 500 lbs. of cotton.
Conventionally, the supply of cotton bales is then shipped to the spinning mill. At the spinning mill, the first procedure is to open the bales, which produces a supply of cotton in loose form at a typical production rate of approximately 3,000 lbs. per hour. As shown in the block diagram, it is usually the case that the supply of cotton in loose form is then run through a blending line. In the blending line, the cotton may be blended with other cotton or with other types of fibers as, for example, polyester, rayon, nylon, and the like. The blending line conventionally produces a supply of blended cotton in loose form, again at a typical production rate of 3,000 lbs. per hour. This supply of blended cotton in loose form is then fed to a lapping machine where the supply of loose cotton is converted into lap form.
As indicated in the drawing, it is sometimes the case that a portion of the supply of blended cotton in loose form obtained from the blending line is baled and stored for future use at the spinning mill. Also, as indicated in the block diagram, the supply of cotton in loose form obtained from the opening machine, in many instances, can be fed directly into the lapping machine. The lapping machine produces a supply of cotton in lap form at a rate of approximately 400 lbs. per hour. In the conventional process, the laps are then fed to the carding machine which produces a sliver. The cotton sliver is then conventionally fed to roving machines and finally to conventional spinning machines.
The improved procedure of the present invention consists essentially of subjecting the cotton at one stage in the above-described conventional process to an environment of dry steam at a temperature and for a time period sufficient to bring the temperature of the cotton up to at least approximately 100° C. The time period and temperature will vary according to the particular variety and grade of cotton being processed. Some varieties require considerably higher temperatures and longer treatments than the typical example indicated above, that is, a temperature of approximately 100° C. for an instantaneous time period. In some instances, as much as 30 minutes at 125° C or more may be necessary. Moreover, in accordance with the principles of the present invention, this procedure should be carried out so as to handle the cotton in the line at a rate which is commensurate with the rate of movement through the line under existing circumstances. The provision of a dry steam environment is essential to the present invention in that this environment insures that the cotton will not be appreciably wetted so that it can be processed through the line without any reduction in the line speed and without diminishing the quality of the finished product in terms of nips produced and fiber length as well as other characteristics. Typically, this dry steam environment is established by feeding a source of superheated steam into environmental contact with the cotton being processed. A typical exemplary embodiment of a dry steam source utilized is superheated steam at a temperature of 138° C. and a pressure of 30 psig. When the cotton is subjected to an environment of dry steam from such a source, the moisture which is absorbed in the cotton can be held to as little as 2 to 4 percent by weight. In accordance with the principles of the present invention, it is desirable to keep the addition of moisture to the cotton during the dry steam procedure to a minimum, although an addition of as much as 25 percent moisture by weight has not proved substantially deleterious to subsequent processing speed and quality, provided the moisture is reduced by drying below about 15 percent before carding. It is essential, however, that the cotton should not be subjected to an environment of wet steam, although the use of superheated steam can be eliminated if sufficient care is utilized to reduce moisture, as by preheating the cotton or the like. Preheating, however, is not regarded to be desirable in that it adds costs and does not in any way add to the reduction of the byssinotic effect of the cotton.
With the above in mind, and again referring to the drawing, the improved procedure of the present invention can be carried out with the cotton either in a loose form, in lap form, or in bale form. An exemplary schematic apparatus arranged for use in carrying out the procedure with a supply of cotton in loose form is indicated generally at 10 in the drawing. The apparatus 10 includes a treatment chamber 12 which may be of rectangular cross-section and disposed vertically with its open upper end constituting an inlet end and its open lower end constituting a discharge end. At the inlet end, the apparatus includes an inlet hopper 14 for receiving the supply of cotton in loose form from a continuously moving conveyor in the line. The apparatus 10 also includes feed means adjacent the hopper for receiving the cotton deposited therein and moving it into the central portion of the chamber 12, which constitutes a treatment zone, indicated at 16. The feed means may be in any suitable form, such as conventional cooperating spiked rollers 18 or the like. Disposed at the lower end of the treatment chamber is a similar pair of spiked rollers 18 which serve to engage the cotton compressed in the bottom of the treatment zone and discharge it onto a suitable discharge conveyor 20 therebelow for movement back into the line. The apparatus 10 also includes means for introducing a source of superheated steam within the treatment zone 16, which is schematically illustrated at 22.
As indicated in the drawing, the apparatus 10 may be used to process the supply of seedless cotton in loose form obtained in the ginning operation, in which case, the discharge conveyor of the apparatus returns the cotton to the baling press. Alternatively, the apparatus 10 may be used to treat the supply of cotton in loose form from the opening machine, in which case, the discharge conveyor 20 returns it either to the blending machine or to the lapping machine where no blending is included in the line. Likewise, the apparatus 10 may be used to process the supply of blended cotton in loose form obtained from the blending machine, in which case, the conveyor 20 will return the cotton to the lapping machine or to the baling machine in the event that the blended cotton is to be stored.
As previously indicated, a typical cotton processing line flow rate for handling cotton in loose form is of the order of 3,000 lbs of cotton per hour. In order to operate at a production rate of this magnitude, an exemplary apparatus 10 is provided with a treatment chamber 12 in which the distance between the sidewalls is approximately 18 inches and the distance between the end walls is approximately 60 inches, the chamber having a height of approximately 96 inches from its inlet end to its discharge end. The infeed mechanism is preferably operated to obtain a compression of the cotton within the treatment zone 16 of approximately five pounds per cubic foot. Dry superheated steam at a temperature of approximately 138° C. and at a pressure of approximately 30 psig is fed continuously from the conduit 22 into the treatment zone so as to effect a uniform treatment of the cotton progressively moving therethrough, the spent steam passing out of the inlet and outlet. The exemplary time required for an incremental portion of cotton to move from the inlet end of the treatment zone to the discharge end thereof is approximately 6 minutes, with a progressive movement of approximately 1.3 feet per minute.
The drawing also illustrates schematically an apparatus, generally indicated at 24, for treating a supply of cotton in lap form. As shown, the apparatus includes a treatment chamber 26 having horizontally aligned inlet and outlet openings 28 and 30. Extending horizontally through the chamber from the inlet opening to the outlet opening thereof is the horizontal operative flight of an endless foraminous belt 32 suitably trained about a series of rollers 34 and driven continuously. The apparatus includes a transfer chute or conveyor 36 which is adapted to receive the supply of cotton in lap form coming from the production line and to direct the same onto the operative flight of the belt 32 so that it will pass through the inlet 28 into the interior of the treatment chamber which forms a treatment zone 38. A source of superheated steam is provided for the treatment zone 38, as indicated at 40.
As shown in the drawing, the apparatus 24 is used to treat the supply of seedless cotton obtained from the gin when the latter is in lap form; the cotton lap from the operative flight of the belt 32 is stripped therefrom and returned to the baling press. The apparatus 24 may also be used to process the supply of cotton in lap form obtained from the lapping machine in which case the processed cotton is returned into the line to be fed to the carding machine.
As previously indicated, a typical production line rate of movement of cotton in lap form is 500 pounds per hour so that the continuous speed of the operative flight of the belt 32 and the dimensions of the chamber 26 are appropriately chosen to suit the particular circumstances. Dry superheated steam at a temperature of 138° C and a pressure of 30 psig is continuously supplied into the treatment zone 38 through valve conduit 40, the dry steam exhausting through the inlet and outlet.
Finally, it will be noted that the drawing also illustrates apparatus, generally indicated at 42, for use in processing cotton in bale form. As shown, the apparatus includes a pressure chamber 44 which is capable of being opened and closed in a manner similar to a conventional autoclave. The chamber is provided with a valve-controlled conduit 46 or the like which serves to communicate the interior of the pressure chamber 44 with a vacuum source. The apparatus 42 also includes a valve conduit 48 connected with a source of superheated steam.
An apparatus capable of receiving 6 bales of cotton is appropriate to keep up with a conventional gin operation. After the bales are loaded in the chamber, the treatment zone therein is alternately evacuated and filled with dry superheated steam to insure full penetration of the interior cotton of the bales. An exemplary schedule would be (1) evacuate to 24 inches Hg, (2) fill with dry superheated steam at 138° C and 30 psig and then relieve the pressure after 5 minutes, (3) repeat (1) and (2), (4) repeat (1) and (2) relieving pressure after 45 minutes, (5) evacuate to 24 inches Hg, (6) relieve vacuum pressure, open and remove.
Although not essential and not shown in the schematic drawings of the steam treatment units, an exhaust line including a suitable condenser is desirable for trapping volatiles removed from the cotton, to prevent atmospheric contamination in the steaming area.
It will be understood that it is preferable to use the apparatus 42 at the gin, although it can be used at the spinning mill as well. Particularly, this is true where the spinning mill includes a baling operation for storing blended cotton bales, as aforesaid.
From the above, it can be seen that the improved procedure will be most effective when performed as early as possible in the conventional processing. Logically, this reasoning would dictate that the present anti-byssinotic treatment be performed at the gin immediately following the ginning operation, or at least after the baling operation. Dry steaming at the gin of cotton in loose form in apparatus of the type of schematic apparatus 10 is generally believed to be the preferred way to apply the invention. However, since experience has shown that the most severe byssinotic effect occurs in the carding operation, substantial advantages can also be obtained by subjecting the cotton in the spinning mill processing line to the dry steam treatment any time before the carding operation.
It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.
Conventional cotton processing has always had an adverse effect on the pulmonary function of personnel working with it. Since the advent of mechanization of cotton harvesting in the field, there has been a noticeable increase in this adverse effect. The effect is more prominent with personnel working the opening, blending and carding than in subsequent operations. This adverse effect gives rise to what is known as byssinosis and the effect has been referred to as the byssinotic effect of cotton.
In recent years, a considerable effort has been made to reduce the instances of byssinosis occurring in personnel working in the cotton processing industry. Early researchers noted that the processing of surgical cotton did not produce a byssinotic effect. However, the processing of surgical cotton did not involve the same type of carding operation utilized in conventional processing of cotton to the point of spinning. In the processing of surgical cotton, the cotton is subjected to a washing treatment, the washing solution containing primarily heated water with some chemicals such as three percent sodium hydroxide or the like. Proceeding on the basis that it was this washing process utilized with surgical cotton which accounted for the absence of a byssinotic effect, eperimental efforts have been made to develop a washing treatment for cotton which is to be processed through the conventional steps to the point of spinning. Experiments of this nature were carried out under the direction of Dr. James A. Merchant and did, in fact, show that the byssinotic effect of cotton could be substantially reduced by washing the cotton in a manner similar to the washing process performed with surgical cotton. In these experiments, after the washing process had been performed, the washed cotton was then dried at 325° F. for 10 minutes. These washing experiments were also repeated with water as the sole washing medium. While the byssinotic effects of the cotton were substantially reduced, the dry cotton was in such a matted condition that the subsequent carding of the same could not be practically performed. Additional tests under the direction of Dr. Merchant were performed where the cotton was steamed in a vat with wet steam and then likewise dried at 325° F. for 10 minutes. Here, again, the results showed that the byssinotic effect of the cotton was substantially reduced. However, while the resultant cotton could be processed through the carding machine more readily than that obtained by the washing treatment, nevertheless, the carding operation could not be performed at production speeds. Moreover, the resultant carded cotton was reduced in fiber length and exhibited considerably more neps than the same cotton which was not subjected to the steaming treatment.
An object of the present invention is to provide an improved procedure in the conventional processing of cotton up to the point of spinning for reducing the byssinotic effect thereof during each processing, which procedure is compatible with existing production speeds and has no substantial effect on the quality of the cotton produced. In accordance with the principles of the present invention, this objective is obtained by subjecting the cotton to an environment of dry steam at a temperature and for a time period sufficient for the cotton to reach at least approximately 100° C. In accordance with the principles of the present invention, this treatment can be performed either at the gin or at the spinning mill with the cotton in loose form, in lap form, or in bale form. The process is readily capable of being performed at rates compatible with production rates utilized in conventional processing both at the gin and at the spinning mill.
Another object of the present invention is the provision of an improved procedure in a conventional cotton processing line which will reduce the byssinotic effect in subsequent steps of the conventional process and which can be economically carried out without materially affecting the production rate of the processing line or the quality of the cotton produced therein.
These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.
The invention may best be understood with reference to the accompanying drawing wherein a schematic flow diagram of the procedures of the present invention is illustrated.
With reference to the drawing, it will be noted that the conventional cotton processing steps are indicated in general sequential order by a box flow diagram on the left-hand portion of the drawing. As indicated, the process steps included are those performed conventionally at the gin as well as at the spinning mill. The process at the spinning mill is shown up to the point of obtaining a sliver from the carding machine. Past experience has indicated that the greatest byssinotic effect occurs in the carding room and, consequently, in order for the present treatment to be of substantial effect, it must be performed before the carding operation. As indicated in the block diagram, the steps at the gin would include the feeding of a supply of raw cotton through the gin which produces a supply of seedless cotton. The present invention contemplates that the ginning operation can be carried out by conventional machines which produce the supply of seedless cotton in loose form as well as those conventional machines which produce the seedless cotton in lap form. In any event, the supply of seedless cotton is then conventionally fed to the bale press. A typical feed rate of loose cotton from the gin to the bale press is approximately 3,000 lbs. per hour and above. Where the gin produces seedless cotton in lap form, a typical feed rate to the bale press is approximately 500 lbs. per hour and above. From the bale press, a supply of cotton bales is obtained. A typical outfeed rate of a baling press is approximately six bales per hour, each of which contains approximately 500 lbs. of cotton.
Conventionally, the supply of cotton bales is then shipped to the spinning mill. At the spinning mill, the first procedure is to open the bales, which produces a supply of cotton in loose form at a typical production rate of approximately 3,000 lbs. per hour. As shown in the block diagram, it is usually the case that the supply of cotton in loose form is then run through a blending line. In the blending line, the cotton may be blended with other cotton or with other types of fibers as, for example, polyester, rayon, nylon, and the like. The blending line conventionally produces a supply of blended cotton in loose form, again at a typical production rate of 3,000 lbs. per hour. This supply of blended cotton in loose form is then fed to a lapping machine where the supply of loose cotton is converted into lap form.
As indicated in the drawing, it is sometimes the case that a portion of the supply of blended cotton in loose form obtained from the blending line is baled and stored for future use at the spinning mill. Also, as indicated in the block diagram, the supply of cotton in loose form obtained from the opening machine, in many instances, can be fed directly into the lapping machine. The lapping machine produces a supply of cotton in lap form at a rate of approximately 400 lbs. per hour. In the conventional process, the laps are then fed to the carding machine which produces a sliver. The cotton sliver is then conventionally fed to roving machines and finally to conventional spinning machines.
The improved procedure of the present invention consists essentially of subjecting the cotton at one stage in the above-described conventional process to an environment of dry steam at a temperature and for a time period sufficient to bring the temperature of the cotton up to at least approximately 100° C. The time period and temperature will vary according to the particular variety and grade of cotton being processed. Some varieties require considerably higher temperatures and longer treatments than the typical example indicated above, that is, a temperature of approximately 100° C. for an instantaneous time period. In some instances, as much as 30 minutes at 125° C or more may be necessary. Moreover, in accordance with the principles of the present invention, this procedure should be carried out so as to handle the cotton in the line at a rate which is commensurate with the rate of movement through the line under existing circumstances. The provision of a dry steam environment is essential to the present invention in that this environment insures that the cotton will not be appreciably wetted so that it can be processed through the line without any reduction in the line speed and without diminishing the quality of the finished product in terms of nips produced and fiber length as well as other characteristics. Typically, this dry steam environment is established by feeding a source of superheated steam into environmental contact with the cotton being processed. A typical exemplary embodiment of a dry steam source utilized is superheated steam at a temperature of 138° C. and a pressure of 30 psig. When the cotton is subjected to an environment of dry steam from such a source, the moisture which is absorbed in the cotton can be held to as little as 2 to 4 percent by weight. In accordance with the principles of the present invention, it is desirable to keep the addition of moisture to the cotton during the dry steam procedure to a minimum, although an addition of as much as 25 percent moisture by weight has not proved substantially deleterious to subsequent processing speed and quality, provided the moisture is reduced by drying below about 15 percent before carding. It is essential, however, that the cotton should not be subjected to an environment of wet steam, although the use of superheated steam can be eliminated if sufficient care is utilized to reduce moisture, as by preheating the cotton or the like. Preheating, however, is not regarded to be desirable in that it adds costs and does not in any way add to the reduction of the byssinotic effect of the cotton.
With the above in mind, and again referring to the drawing, the improved procedure of the present invention can be carried out with the cotton either in a loose form, in lap form, or in bale form. An exemplary schematic apparatus arranged for use in carrying out the procedure with a supply of cotton in loose form is indicated generally at 10 in the drawing. The apparatus 10 includes a treatment chamber 12 which may be of rectangular cross-section and disposed vertically with its open upper end constituting an inlet end and its open lower end constituting a discharge end. At the inlet end, the apparatus includes an inlet hopper 14 for receiving the supply of cotton in loose form from a continuously moving conveyor in the line. The apparatus 10 also includes feed means adjacent the hopper for receiving the cotton deposited therein and moving it into the central portion of the chamber 12, which constitutes a treatment zone, indicated at 16. The feed means may be in any suitable form, such as conventional cooperating spiked rollers 18 or the like. Disposed at the lower end of the treatment chamber is a similar pair of spiked rollers 18 which serve to engage the cotton compressed in the bottom of the treatment zone and discharge it onto a suitable discharge conveyor 20 therebelow for movement back into the line. The apparatus 10 also includes means for introducing a source of superheated steam within the treatment zone 16, which is schematically illustrated at 22.
As indicated in the drawing, the apparatus 10 may be used to process the supply of seedless cotton in loose form obtained in the ginning operation, in which case, the discharge conveyor of the apparatus returns the cotton to the baling press. Alternatively, the apparatus 10 may be used to treat the supply of cotton in loose form from the opening machine, in which case, the discharge conveyor 20 returns it either to the blending machine or to the lapping machine where no blending is included in the line. Likewise, the apparatus 10 may be used to process the supply of blended cotton in loose form obtained from the blending machine, in which case, the conveyor 20 will return the cotton to the lapping machine or to the baling machine in the event that the blended cotton is to be stored.
As previously indicated, a typical cotton processing line flow rate for handling cotton in loose form is of the order of 3,000 lbs of cotton per hour. In order to operate at a production rate of this magnitude, an exemplary apparatus 10 is provided with a treatment chamber 12 in which the distance between the sidewalls is approximately 18 inches and the distance between the end walls is approximately 60 inches, the chamber having a height of approximately 96 inches from its inlet end to its discharge end. The infeed mechanism is preferably operated to obtain a compression of the cotton within the treatment zone 16 of approximately five pounds per cubic foot. Dry superheated steam at a temperature of approximately 138° C. and at a pressure of approximately 30 psig is fed continuously from the conduit 22 into the treatment zone so as to effect a uniform treatment of the cotton progressively moving therethrough, the spent steam passing out of the inlet and outlet. The exemplary time required for an incremental portion of cotton to move from the inlet end of the treatment zone to the discharge end thereof is approximately 6 minutes, with a progressive movement of approximately 1.3 feet per minute.
The drawing also illustrates schematically an apparatus, generally indicated at 24, for treating a supply of cotton in lap form. As shown, the apparatus includes a treatment chamber 26 having horizontally aligned inlet and outlet openings 28 and 30. Extending horizontally through the chamber from the inlet opening to the outlet opening thereof is the horizontal operative flight of an endless foraminous belt 32 suitably trained about a series of rollers 34 and driven continuously. The apparatus includes a transfer chute or conveyor 36 which is adapted to receive the supply of cotton in lap form coming from the production line and to direct the same onto the operative flight of the belt 32 so that it will pass through the inlet 28 into the interior of the treatment chamber which forms a treatment zone 38. A source of superheated steam is provided for the treatment zone 38, as indicated at 40.
As shown in the drawing, the apparatus 24 is used to treat the supply of seedless cotton obtained from the gin when the latter is in lap form; the cotton lap from the operative flight of the belt 32 is stripped therefrom and returned to the baling press. The apparatus 24 may also be used to process the supply of cotton in lap form obtained from the lapping machine in which case the processed cotton is returned into the line to be fed to the carding machine.
As previously indicated, a typical production line rate of movement of cotton in lap form is 500 pounds per hour so that the continuous speed of the operative flight of the belt 32 and the dimensions of the chamber 26 are appropriately chosen to suit the particular circumstances. Dry superheated steam at a temperature of 138° C and a pressure of 30 psig is continuously supplied into the treatment zone 38 through valve conduit 40, the dry steam exhausting through the inlet and outlet.
Finally, it will be noted that the drawing also illustrates apparatus, generally indicated at 42, for use in processing cotton in bale form. As shown, the apparatus includes a pressure chamber 44 which is capable of being opened and closed in a manner similar to a conventional autoclave. The chamber is provided with a valve-controlled conduit 46 or the like which serves to communicate the interior of the pressure chamber 44 with a vacuum source. The apparatus 42 also includes a valve conduit 48 connected with a source of superheated steam.
An apparatus capable of receiving 6 bales of cotton is appropriate to keep up with a conventional gin operation. After the bales are loaded in the chamber, the treatment zone therein is alternately evacuated and filled with dry superheated steam to insure full penetration of the interior cotton of the bales. An exemplary schedule would be (1) evacuate to 24 inches Hg, (2) fill with dry superheated steam at 138° C and 30 psig and then relieve the pressure after 5 minutes, (3) repeat (1) and (2), (4) repeat (1) and (2) relieving pressure after 45 minutes, (5) evacuate to 24 inches Hg, (6) relieve vacuum pressure, open and remove.
Although not essential and not shown in the schematic drawings of the steam treatment units, an exhaust line including a suitable condenser is desirable for trapping volatiles removed from the cotton, to prevent atmospheric contamination in the steaming area.
It will be understood that it is preferable to use the apparatus 42 at the gin, although it can be used at the spinning mill as well. Particularly, this is true where the spinning mill includes a baling operation for storing blended cotton bales, as aforesaid.
From the above, it can be seen that the improved procedure will be most effective when performed as early as possible in the conventional processing. Logically, this reasoning would dictate that the present anti-byssinotic treatment be performed at the gin immediately following the ginning operation, or at least after the baling operation. Dry steaming at the gin of cotton in loose form in apparatus of the type of schematic apparatus 10 is generally believed to be the preferred way to apply the invention. However, since experience has shown that the most severe byssinotic effect occurs in the carding operation, substantial advantages can also be obtained by subjecting the cotton in the spinning mill processing line to the dry steam treatment any time before the carding operation.
It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.